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Chemistry of the hard-ligated organorhodium complexes

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Chemistry of the hard-ligated organorhodium complexes

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Content CHEMISTRY OF THE HARD-LIGATED ORGANORHODIUM COMPLEXES by Lin Wang A Dissertation Presented to the FACULTY OF THE GRADUATE SCHOOL UNIVERSITY OF SOUTHERN CALIFORNIA In Partial Fulfillment of the Requirements for the Degree DOCTOR OF PHILOSOPHY (Chemistry) December 1993 Copyright 1993 Lin Wang UMI Number: DP22062 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a com plete manuscript and there are missing pages, th ese will be noted. Also, if material had to be removed, a note will indicate the deletion. Dissertation Publishing UMI DP22062 Published by ProQuest LLC (2014). Copyright in the Dissertation held by the Author. Microform Edition © ProQuest LLC. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code ProQuest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, M l 4 8 1 0 6 -1 3 4 6 UNIVERSITY OF SOUTHERN CALIFORNIA THE GRADUATE SCHOOL UNIVERSITY PARK LOS ANGELES, CALIFORNIA 90007 This dissertation, w ritten by L in > # Wang............................................................................. under the direction of h.tS. Dissertation Committee, and approved by all its members, has been presented to and accepted b y The Graduate School, in partial fulfillm ent of re quirements for the degree of D O C TO R OF PH ILO SOPH Y Dean of G raduate Studies Date . . . J ; ERTATION COMMITTEE Chairperson p h . a c V / 2 - 4 ^ Acknowledgments First I wish to express my sincere appreciation to Professor Tom Flood for his friendship, careful guidance and invaluable help during the past four years. His help and encouragement have always been the driving force for me to keep trying to achieve scientific excellence. Over the years Dr. Robert Bau et al. have given me tremendous help in defining the single crystal structures o f several rhodium compounds. The people who have contributed to this work are Roy Lu, Dong Zhao, Robert Gellert and Janet Manning. Collaborations with Dr. Paul Gassman and Dr. John Sowa at the University of Minnesota, and with Dr. Dennis Lichtenberger and Dr. Lalitha Subramanian at the University o f Arizona have been particularly helpful for the understanding o f the hard-ligated organorhodium system. Dr. Ronald Shinomoto and Mobil Chemical Co. R&D are gratefully acknowledged for measurement of the properties o f the polyethylene. Over the years, there are many other wonderful people who have helped me in various ways: Allan Kershaw, Dr. Gil Yang, Dr. Gordon Miskelly, Dr. Chris Reed, Dr. Nicos Petasis and Dr. Richard Deonier, to name just a few. I would also like to thank my colleagues in the Flood group who have been great fun to work with: Mark Deming, John Lim, Harald Holcomb, Ginette Struck, Chunming Wang, Mark Kozak and Janet Manning. My parents have been very supportive during these years. Their love and expectations have always been the impetus for me to face difficulties in science and life, particularly in a totally new environment. The support from my parents-in-law, my brother and my sister is also deeply appreciated. Finally, I wish to express my sincere gratitude to my wife, Yuan, for all her help and understanding over the years. With her, life is more enjoyable. | Table of Contents I Acknowledgments List of Tables List of Figures Introduction Chapter 1 Chemistry of Hard-Ligated Organorhodium Complexes in Organic Phase Results and Discussion | Preparation of the "CnRh" Complexes I Solvolysis Spectroscopic Properties Reaction of CnRhMe2 OTf with C2H4 and CO Polymerization of Ethylene j Anion and Ligand Conclusions I Experimental General Ligand Preparations I Rhodium Compounds j HBR4 .(Et20 ) 2 ; Polyethylene X-ray Crystal Structure Analysis Kinetic Experiments Data J Chapter 2 Chemistry of Hard-Ligated Organorhodium Complexes | in Protic Solvents Results and Discussion Transformation of "CnRh" Species in Aqueous Phase | Coordination Polymerization of Ethylene in Aqueous Phase Reactions of CnRh Complexes with Ethylene in Methanol ; Generation of Rhodium Alkyl Hydride Species in Methanol ! Conclusions Experimental ; General [ "CnRh" Complexes ! | Polymerization of Ethylene I Kinetic Experiments I Data Chapter 3 Photoelectron Spectroscopy of Hard and Soft-Ligated Organorhodium Complexes Results and Discussion Synthesis of (PMe3)3 RhMe3 and its derivatives 184 Synthesis of 3PRhMe3 and its derivatives 185 XPS of Hard and Soft-Ligated Organorhodium Complexes 189 UPS of Hard and Soft-Ligated Organorhodium Complexes 197 Conclusions 206 Experimental XPS Experiments 207 Synthesis of ”(PMe3)3Rh" and "3PRh" compounds 207 Data 213 References 225 Selected Bibliography 230 iv List of Tables Page Table 1.1 The correlation between tire JH NMR chemical shift (6 ) of RhCiT3 in CnRhMe3_ nXn (n = 0, 1, 2) and n. 22 1.2 The correlation between the of RhCH3 in CnRhMe3_ nXn (n = 0, 1,2) and n. 23 1.3 Changes of rate constants with [C2 H4] in the reaction of CnRhMe2OTf with C2 H4. 47 1.4 Physical properties of polyethylene generated from different conditions in non-protic organic solvents. 32 1.5 Selected bond lengths and bond angles of CnRhMe3 and NhCnRhMe3. 65 3 . 1 Effect of CH-f, CL, B r , OH" and CF3S 0 3 “ ligands on the binding energies of organorhodium complexes. 191 3.2 UPS peak parameters for CnRhMe3. 198 v List of Figures Page Synthesis of Cn. 9 ORTEP drawing of the structure of CnRhMe3. 12 Synthesis of the CnRh complexes. 13 Solvolysis of CnRhMe(OTf)2, 3, in DMSO-c^, detected by !H NMR. 15 iH NMR of [CnRhMe(H20 ) 2](0Tf)2, 13, in D2 0 . 16 iH N M R of [CnRhMe(OTf)(H20)]+, 14, and [CnRhMe(H2 0 )2]2+ , 13, in CD3N 0 2. 17 NMR spectra of CnRhMe3 , 1, in C6 D6 and DMSO-g^. 21 13C{’H}NMR of [CnRh1 3CH3(0Tf)(H 2 0 )]0 T f in CD3N 0 2. 25 Reaction of (triphos)RhMe2 BF4 and (Me2PhP)3RhMe2 BF4 with CO. 27 Reaction of complex 2 with CO. 27 Reaction of (triphos)RhMe2BF4 and (Me2PhP)3RhMe2BF4 with CH2-C H 2. 29 1 3C{]H}NMR spectra of the reaction of CnRh(1 3CH 3)2 OTf, 2-1 3C, in CD2 C1 2 with 1 3C-C2H4 with temperature. 34 NMR spectra of the reaction of CnRhMe2OTf with C2 H4 in CD2C1 2 at -35 °C with time. 35 ORTEP drawing of the cation part of the structure of [CnRh(ri3-allyl)(Cl)]OTf, 2 1 . Scheme of the reaction between CnRhMe2OTf and ethylene. 37 Figure 1.16A Isotope labeling experiment of 2-,3C and C2D4 at -30 °C. 1.16B Possible a-bond metathesis paths. 1.17 1 3C{lH} NMR of the isotope scrambling of 20 at -15 °C. 1.18 The reversible equilibrium of 20 and 19 at -15 °C. I 1.19 Kinetic expression of the transformation of 2 , 16 and 20. 1.20 Full Kinetic scheme of the transformation of 2, 16 and 20. 1.21 Line fitting of calculated concentrations of 2, 16 and 20 to experimental data. 1.22 The lnk3 ~ 1/T plot for the insertion reaction of 16. 1.23 Eyring plot for ethylene insertion reaction of 16. 1.24 1 3C{1H}NMR spectra of CnRhMe(BF4 ) 2 (13% 1 3 C of RhMe) in reaction with 1 3CH2= 13CH2 in CD3N 0 2. 1.25 Mechanism for the formation of 1-butene. 1.26 Dimerization of ethylene by C5R5(L)Rh(Et)(C2 H4)+. 1.27 Preparation of HBR4 (Et2 0 ) 2 and its acid cleavage reactions. 1.28 ORTEP drawing of the cation part of the molecular structure of complex 24. 1.29 Synthesis of the new RCn ligands. 1.30 Synthesis of the rhodium complexes with RCn ligands. 1.31 1 H NMR of NhCnRhMe3 , 28, in C6 D6. i i 1.32 ORTEP drawing of the structure of complex 28. 2 .1 ORTEP diagram of the cation part of the molecular structure of [CnRhMe(OTf)(H20)]OTT I i ; l ; Figure 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 2.10A 2.10B 2.11 2.12 2.13 2.14 2.15 ORTEP diagram of the cation part of the molecular structure of [CnRhMe(H2 0 )2](0 Tf)2 . 125 Transformation of complexes 13, 29 and 30. 126 Relationship of the pKa2 of H2 A with the pH of HA". 128 ]H NMR of aqueous phase transformations of 13, 29 and 30. 131 Kinetic plot of protonolysis of 2 in D20 at 24 °C. 132 Transformation scheme of 2 , 3, 13, 29, 30 and 31. 133 Kinetic plot of protonolysis of 29 in D20 at 50 °C. 134 Thermolysis of 29-D at 50 °C. 134 i 1 3C{]H}NMR spectra of the reaction of 29-1 3 C and ethylene-1 2 C in D20 at 24 °C. 137 Kinetic plot of ethylene polymerization by 29-1 3 C in D20 at 50 °C at different ethylene pressure. 138 Mechanism and rate expression of the reaction between 29 and C2H4. 139 Mechanism and rate expression of the reaction between 29 and C2 H4. 141 Kinetic plot of the reaction of 13 and ethylene at 50 °C in D20 at pH = 2. 143 Kinetic plot of the reaction of 32 with ethylene in acetone-c/^ at 2 2 °C. 145 Scheme of the reaction between 33 and ethylene in methanol-<f4. 148 V I1 1 Figure 2.16 2.17 2.18 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 Kinetic plot of reaction of 3 and ethylene in CD3OD at 20 °C. 151 Two possible paths of reaction of 33 in CH3OD. 153 Generating [CnRhMe(H)(solv)]+ by different starting materials. 154 Preparations of fac-(PMe3)3RhMe3. 185 ORTEP diagram of the structure of fac-(PMe3)3RhMe3. 186 Synthesis of "3P" and 3PRhMe3. 187 ORTEP diagram of the structure of 3PRhMe3. 188 XPS absorption bands of CnRhBr3. 194 Diagram of the XPS data of CnRh and 3PRh complexes. 196 He He He He He He I and He II of CnRhMe3 in the region 15-5 eV. 199 j I and He II of CnRhMe3 in the region 9-6 eV. 200 I photoelectron spectra of the Cn ligand. 202 I and He II of 3PRhMe3 in the region of 16-6 eV. 203 I and He II of 3PRhMe3 in the region of 9-6 e V. 204 I of the 3P ligand. 205 ix INTRODUCTION Rhodium is one of the exceedingly rare elements with an abundance in the earth's crust of some 10*9%.1 Despite its rareness, rhodium has been found to be a very useful element in chemical transformations, particularly in catalysis. One of the most important features of the chemistry of rhodium is the easy oxidative addition to four-coordinate, 16-electron rhodium(I) and the facile reductive elimination from octahedral, 18-electron rhodium(III).2 The reversibility of Rh(I) and Rh(III) oxidation states of such reactions is largely responsible for the ability of organorhodium complexes to catalyze a wide range of organic reactions.2 Catalytic hydrogenation and hydroformylation of carbon- carbon double bonds of organic compounds by [RhCl(PPh3 )3 ] discovered by Wilkinson's group are among the most important catalytic transformations.3 A tremendous amount of work has been done on the organometallic chemistry of rhodium, most of this has been associated with "soft" ligands (e.g. Cp, PR3 , CO, etc.). Those ligands are strong field, polarizable, and generally n- acidic. On the other hand, the chemistry of organorhodium compounds bearing "hard", non-7c-interacting (neither donor or acceptor) ligands has not been explored. We are very interested in examining the effects of using hard ligands in organorhodium chemistry, particularly amine ligands. There are indications in the literature that use of nitrogen-containing ligands can give substantially different reactivity to organometallic compounds compared to analogous complexes containing soft ligands. 4 By comparing the thermostability and reactivity of PdMe2 (tmeda) (tmeda = N,N,N',N'-tetramethylethanediamine) and PdMe2(dmpe) (dmpe = l,2-bis(dimethylphosphino)ethane), Boersma et al. 1 found that palladium-nitrogen coordination is thermodynamically weaker than palladium-phosphorus coordination. 4 3 The relatively weak coordination of amines compared to phosphines is most probably because the overlap between the comparatively small sp3 hybrid orbital of the nitrogen lone pair and the orbital of palladium(II) is not as good as the overlap between the larger and more diffuse sp3 orbital of the phosphorus lone pair and the orbital of Pd(II) 4 3 With the observation that the rate of reaction of Mel with PdMe2 (tmeda) is much greater than with PdMe2(dmpe), they concluded that the presence of two purely cr-donating amines and two covalent PdMe bonds renders the palladium center more nucleophilic. However, whether the diamine really stabilizes the Pd(IV) oxidation state (transition state stabilization), or whether it makes palladium(II) more reactive (ground state destabilization), or both remains an open question 4 3 To explore the hard-ligated organorhodium chemistry, we are especially interested in saturated tertiary amine ligands. The requirement that they be tertiary arises from the general need to use basic alkylating agents (e.g. CH3Li) to form alkyl-metal bonds. Since C-N and M-N bonds are shorter than C-P and M-P bonds, it is likely that L3M- or L4 M-containing complexes will be far too crowded to be stable. CPK molecular models show that chelated tertiary amines* coordination to rhodium is overall less crowded than with corresponding non-chelated tertiary amines. For this reason, we have initially been examining the chemistry of chelating ligands to allow simultaneous coordination of several trialkylamine ligands. Three such ligands that we are interested in are N,N,N',N",N"-pentamethyldiethylenetriamine 2 (Me2NCH2 CH2)2NCH3 , PMETA, l,l-tris(dimethylaminomethyl)ethane, (MeC(CH2NMe2 ) 3 and l,4,7-trimethyl-l,4,7-triazacyclononane (Cn). We have been particularly interested in and, in fact, have been having the most success with Cn. With its enforced fac coordination, Cn should offer some interesting comparisons to triphos5 (MeC(CH2PPh2)3 ), rj-Cp, T]-Cp* and tj-C6H6 6 -electron ligands, perhaps even more so than pyrazolylborate or tripyridylmethane ligands which still have delocalized n systems and so are not as hard as tertiary amines should be. While Cn coordinates via first row atoms and so, in principle, might be vulnerable to p-H eliminations to form iminium complexes, models indicate that the methylene hydrogens are sterically inaccessible. Elimination from the N-methyl group also seems unlikely because of significant strain that the rest of the chelation of the ligand would impose on the ^-coordinated iminium group. The inorganic chemistry of Cn is extensive, and far more extensive for the non-methylated 1,4,7-triazacyclononane. 6 The major impetus for making macrocyclic multidentate amines has been in preparing low-molecular-weight compounds of bioinorganic relevance. In order to understand spectroscopic properties and the reactivity of transition metal centers in metalloproteins (also in vitamin B1 2 ), low-molecular-weight model complexes have been designed and synthesized. So far, "the preparative tools developed have reached a level of sophistication that enables the bioinorganic chemists to design specifically ligands that mimic steric and electronic factors of the metal ions in a given metalloprotein" . 6 In our work, we wish to address the totally unexplored implication of Cn as a ligand for organometallic complexes. By reacting Cn with RhCl3 .3H20 in ethanol, Wieghardt et al. obtained CnRhCl3 . 7 > 8 Heating the alkaline aqueous solution of CnRhCl3 resulted in the 3 formation of the hydroxo-bridged dimer [CnRh(OH)3RhCn]3 + , which is stable in 2 M perchloric acid. 7 An aqueous suspension of CnRhCl3 reacts with NaBH4 yielding, upon addition of KPF6, red-brown crystals of air-stable hydride- bridged dimer [Cn2Rh2 (H)2 (p-H)2 ](PF6)2 . 8 Comparison of the electrochemical properties of this hydride dimer with its tridentate phosphine (CH3C(CH2PPh2)3 ) analog shows that Cn stabilizes Rhm more efficiently than its tridentate phosphine analog. 8 The aqueous phase inorganic chemistry of Cn- coordinated rhodium complexes appears to be generally well behaved. The kinetic inertness of Cn is one aspect that makes it so useful in synthetic inorganic chemistry. In some cases, Cn-coordinated metal complexes can be treated with hot concentrated acid or base without the usual acid catalyzed ligand dissociation or formation of metal hydroxides.6 Cn is also relatively redox-inactive; it coordinates to metal centers that have a wide range of metal oxidation states. For example, both CnMo(CO) 3 and CnW(CO) 3 are air-stable compounds, and they both react with H2 0 2 affording CnM o0 3 and CnW 0 3 in excellent yields. No dissociation of Cn was observed upon changing the oxidation state of the respective metal center by six electrons. 6 In recent years, the chemistry of Cp, Cp*, and triphos (CH3(CH2PPh2)3 ) coordinated organorhodium complexes has been extensively studied. 5 ’9 ’10 Caulton5 reported that the triphos-coordinated rhodium complex (triphos)RhMe2 BF4 readily reacts with CO to give acetone and (triphos)Rh(CO)2 +, the Rh1 complex, as the final products. Also he reported that under ethylene pressure, (triphos)RhMe2BF4 reacts with ethylene to form the ethylene-coordinated Rhr complex [(triphos)Rh(C2H4 ) 2 ] + . 5 In both cases 4 Rh1 is the preferred oxidation state of the final products. Brookhart and coworkers have recently reported that the complexes C5R5(L)Rh(Et)(C2 H4)+ (R = H, Me; L = PMe3 , P(OMe)3 ) can catalyze the dimerization of ethylene. 9 Cp*(P(OMe)3)Rh(C2H4)(H)+ was found to be an excellent catalyst for the dimerization of methyl acrylate. 1 0 The nature of the CpRh and Cp*Rh cationic complexes in their reactions is electrophilic. 9 >10 There are also reports of organometallic chemistry of [tris(pyrazolyl)borato]Rh (TpRh) complexes in recent years. Their C-H activation chemistry in particular has been extensively explored by Graham and Jones. 11 The Tp and Cp ligands are said to be sterically and electronically similar.llb Also there have been organometallic studies12 of rhodium-containing porphyrins and vitamin B 12 models, some of the most recent of which is fascinating. 1213 As mentioned before, no hard-ligated organorhodium chemistry has been done. We are aware of only one previous example13 of alkyl complexes of rhodium which bear only saturated amine ligands with or without additional hard ligands. Based on the previous discussions, one might expect that for amine ligands, that the absence of 7t-acidic bonding and the much lower polarizability of nitrogen, compared to phosphorus or to extended-7i-system carbon ligands, would mean that amines would tend to favor higher oxidation states over lower ones. As mentioned before, the electrochemistry of the hydride complex [Cn2Rh2(H)2 (p-H)2](PF6 ) 2 indicates that Cn stabilizes Rh01 more efficiently than triphos does. We deduce that it would be worthwhile to attempt to prepare CnRhMe2BF4 and to study its reactions with ethylene and CO and to compare the chemistry with its phosphine analog 5 (triphos)RhMe2 BF4. By reacting ethylene with CnRh complexes, it would be very interesting to see whether they would demonstrate different chemistry from their phosphine analogs. For example, if the Cn ligand would stabilize the Rhm oxidation state under conditions of reaction with ethylene, would the ethylene insertion into the rhodium-methyl bond operate? If so, it would offer a distinct comparison to its phosphine analog since ethylene insertion was not observed for the latter compound. If ethylene insertion did operate for the CnRh complex, it would offer a nice comparison with the CpRh (or Cp*Rh) system, since for the CpRh system, P-H elimination from the alkyl chain on rhodium is dominant (compared to further ethylene insertion) and this results in the formation of butenes without further oligomerization of ethylene. As the inorganic complexes of CnRh have well-defined chemistry in aqueous phase, it would also be worthwhile to explore the organometallic chemistry of the Cn coordinated organorhodium complexes in protic solvents, with the hope that their chemistry would also be well-behaved in protic phase. As mentioned before, with its enforced fac coordination, Cn should offer some interesting comparisons to triphos, p-Cp, rj-Cp* and t]-C6H6 6 -electron ligands, perhaps even more so than tris(pyrazolyl)borate which still has delocalized % systems and so is not as hard as Cn. Of these ligands, triphos might offer the most reasonable comparison to Cn as both of them are neutral ligands. Of course the triphos ligand has six phenyl groups on it, so CH3C(CH2PMe2 ) 3 ("3P") might be an even closer analog of Cn than triphos. If a series of Cn coordinated organorhodium compounds could be synthesized and their organometallic reactivities were different from their phosphine analogs, we 6 phosphine analogs, we would carry out photoelectron spectroscopic studies of Cn coordinated organorhodium compounds as well as their phosphine coordinated analogs in order to understand the possible reasons for the reactivity differences. The first chapter of this thesis focuses on the synthesis of Cn- coordinated organometallic compounds, their properties and their reactions with different reagents in organic solvents, and the comparisons of the reactivities of these hard-ligated organorhodium complexes to their soft-ligated analogs. The second chapter concerns the chemistry of the Cn-coordinated organorhodium compounds in water and methanol. The third chapter discusses the photoelectron spectroscopy studies of the Cn-coordinated organorhodium compounds and their corresponding phosphine analogs. 7 CHAPTER 1 Chemistry of Hard-Ligated Organorhodium Complexes in Organic Phase* Results and Discussion Preparation of the CnRh Complexes l,4,7-Trimethyl-l,4,7-triazacyclononane is extremely expensive to purchase. The synthesis of the Cn ligand for this research was based on modifications of literature preparations. The basic reaction scheme is listed in Figure 1. The literature preparation for the tritosylate of 1,4,7- triazacyclononane works well and was used as given. 15 The first modification is in the transformation of the tritosylate of 1,4,7-triazacyclononane to the hydrogen bromide salt of 1,4,7-triazacyclononane. The second modification is in the reductive amination — methylation of 1,4,7-triazacyclononane to give Cn. The modified preparations work extremely well and the combined yield of the last two steps is very high (ca. 80%). Wieghardt6 ’8 has reported the synthesis of CnRhCl3 by addition of an ethanol Cn solution to an ethanol solution of RhCl3 .xH20 followed by reflux. We have found that it is a very straightforward reaction and 87-90% yield are generally obtained (6 6 % yield was reported). This air stable, yellow compound * The X-ray crystal structure analyses of organorhodium compounds throughout this thesis have been done in collaboration with Professor Robert Bau's group at the University of Southern California. 8 was treated with an excess of "halide free" CH3Li16 in THF for 2 or 3 days. Methylene chloride and benzene extraction of the residue from evaporation of 1 H O ^ O H + 2 CH3 - ^ S 0 2 C 1 - Pyridine ,» TsO OTs 2. HN(CH2CH2 NH2)2 + 3CH3C6H4S02C1 ■ J ^ ^ ^ TsN(CH2CH2 NHTs)2 C2 H5 ONa ^ - / \ / \ - 3. TsN(CH2 CH2 NHTs)2 —----— -------— ► Na+ N N N Na+ c2 h5 oh, f | s Is Is 4. N a + i j ^ Y NNa+ + Ts(/ W -- Ts Ts Ts V N > I Ts /N N\ H N N H HBr NP -,u r > W ^ < w > i — W I H Ts / \ CH3 v / — \ / ' 6. H /N y 3HBr H2 CO, HCOOH _ N N i T H2 0 . 1 V - N y CHj CHq Figure 1.1 Synthesis of Cn. 9 THF gives up to 85% yields of pale yellow CnRhMe3, 1 (Figure 1.3). It is air and water stable and is unaltered after 24 h in benzene-^ at 1 1 0 °C. Slow evaporation of a methylene chloride and toluene solution of 1 resulted in formation of cylindrical single crystals of 1. Solution of the X-ray diffraction data of 1 show the expected facial Cn coordination with average Rh- N and Rh-C bond lengths of 2.23 and 2 . 1 0 A , respectively (Figure 1.2). The bond angles (NRhN,80°; CRhC, 87°) clearly indicate that the Cn ligand is slightly slipped up along the three-fold axis, and the whole molecule has C3 symmetry. Stoichiometric treatment of 1 with H 0S(0) 2 CF3 (triflic acid, HOTf), HBF4, or HC1 (in Et20/CH 2C12 ) generates the species 2-7 (Figure 1.3), all essentially quantitatively1 7 . Intermediates in the acid cleavages could not be detected by !H NMR even at -80 °C in CH2 C12. For species 2-5, the relatively weakly coordinating ligands OTf" and BF4" slowly undergo chlorine exchange at room temperature with the CH2C1 2 solvent in which they are made. For this reason, during the preparation of 2-5, they should not be allowed to stay in CH2 C1 2 for more than 2 h at RT. CnRhMe2Br, CnRhMeBr2 and CnRhBr3 were made by ion exchange of the corresponding triflate compounds with (n- Butyl)4 NBr in THF or CH3N 0 2 (Figure 3). Complexes 1, 6 , 7, 8 , and 9 are air stable. Complexes 2 and 4 react with water, the chemistry of which is discussed in Chapter 2. Complexes 3, 5 and 10 are hygroscopic. The solubility of the CnRh complexes in different solvents depends on the dipole moment of the CnRh molecule and the polarity of the solvent. For CnRhCl3 , since the three amine groups are electron donating and the three 10 chloride groups electron withdrawing, the dipole moment of the molecule (directed from Cn to Cl) is significant. In fact, CnRhCl3 dissolves in water, and only slightly dissolves in DMSO and DMF; it does not dissolve in acetone, THF and CH2C12. The dipole moments of CnRhMeX2 (X = Cl, Br, OTf and BF4) are probably slightly smaller than that of CnRhCl3, therefore CnRhMeX2 ! (X = Cl, Br, OTf and BF4) dissolve in acetone and more polar solvents (H2 0 , | DMSO, CH3N 0 2, etc.), but not in solvents that are less polar than acetone ! (THF, CH2C12, etc.). CnRhMe2 X (X = Cl, Br, OTf and BF4 ) should have smaller dipole moments than CnRhMeX2 (X = Cl, Br, OTf and BF4). In fact, CnRhMe2X dissolves in CH2C12, THF and solvents that are more polar than | CH2 C1 2 (acetone, DMSO, water, etc.). They do not dissolve in benzene. | CnRhMe3, on the other hand, contains three methyl groups that are not ; significantly electron withdrawing, and so its dipole moment should be smaller than CnRhMe2X. Indeed, CnRhMe3 turns out to be a less polar molecule. It : does not dissolve in H20 but dissolves in benzene, CH2 C12, THF, DMSO, etc. I j Solvolysis | The phenomenon of ligand dissociation and metal coordination by | ] i solvent is fairly common for the relatively weekly coordinating anions in metal ! complexes. 17 In Beck's review17 of metal complexes with weakly coordinating I | anions, he lists the order of relative coordinating ability (a-donor strength)of the I anions: AsF6", SbF6", PF6", < BF4" < FS03 ", CF3S 0 3 ' < C104' < OTeF5", I R e04' « Cl". He found that in the system CpM(CO)2(L)X (M = Mo, W; L = } I CO, PR3; X = BF4", PF6", AsF6“, SbF6", CF3S 03"), the order of increasing 11 C5 C12 C ll C6 N2 CIO C7 C4 Rh C3 Cl C2 ! Figure 1.2 ORTEP drawing of the molecular structure of CnRhMe3 (structure | | solved by Robert Gellert, Dong Zhao and Robert Bau). 12 THF 25 or CnRhCl3 + excess CH3 Li ’ » CnRhMe, CnRhMe, HX CH2C1 2 CnRhMe2 X 2 (OTf) 4 (BF4) 6 (Cl) HX CH2C1 2 CnRhMeX2 3 (OTf) 5 (BF4 ) 7 (Cl) CnRhMe2OTf 2 (n-Butyl)4 NBr THF -► CnRhMe2 Br 8 CnRhMe(OTf) 2 2 (n-Butyl)4 NBr ^ CnRhMeBr2 THF excess TfOH excess (n-Butyl)4 NBr „ „ CnRhMe-i — ------- ► CnRh(OTf) 3 — -► CnRhBr3 CH3N 0 2 c h 3n o 2 10 Figure 1.3 Synthesis of the CnRh complexes. ability to substitute weaker ligands is as follows: CH2 C12, ~ PF6" ~ AsF6_ ~ SbF6- < Et20 < BF4- < THF < Me2CO < H20 < CF3S 03- <CO<~ MeCN ~ PR3. The kinetics of solvent substitution of coordinated CF3S 0 3 " have been reviewed18. It was found that for Rh(NH3)5(OTf)2 + , the rate constants of solvolysis increase for the following solvents: methanol < DMSO < water. 19 The rate constant for water solvation in this case is 1.9X10-2 s*1 . 13 j j We have observed solvolysis in this CnRh system, particularly for ) j species 2-5. Complexes 2 and 4 can be easily solvated by DMSO, water, and methanol. They slowly react with water and methanol, the chemistry of which is discussed in Chapter 2. 1 HNMR clearly indicates the complete solvation of 2 and 4 in these solvents since in a given solvent their spectra are identical j i ([CnRhMe2(solv)]+ ). The NMR spectra of complexes 2 and 4 in CH2 C1 2 are I different. Species 2 almost certainly does not solvate in CH2 C12, but we can not ! be certain if 4 does or does not solvate in this solvent, although we suspect it does not. A variable temperature 1 9 F NMR experiment of 4 might be very [ i I useful in this regard, but was not pursued. Complexes 3 and 5, on the other hand, can be completely solvated by DMSO and water, and partially mono solvated by methanol. 1 HNMR spectra indicate that a few minutes after complex 3 dissolves in DMSO at room temperature, it forms a mixture of mono-solvated CnRhMe(OTf)(DMSO)+> 11, and di-solvated ; CnRhMe(DMSO)2 2+, 12 (Figure 1.4). About 2 h later, 1 HNMR indicates that I all the mono-solvated species has been transformed to the di-solvated species j j (Figure 1.4). From Figure 1.4, one can see that 11 is chiral since three different basal ligands on rhodium cause the three methyls of the Cn ligand to be distinct I (labeled c in Figure 1.4). The di-solvated complex 12 possesses a plane of symmetry which makes two methyls on the ligand equivalent. Therefore the ; methyls on the ligand have a two-to-one ratio as shown in Figure 1.4. Once dissolved in water, 3 forms the diaqua spices CnRhMe(H2 0 )2 2+ , 13, immediately (Figure 1.5). The degree of aquation of 3 can be controlled by adding different amounts of water to a nitromethane solution of 3. When one 1 h r (DMSO) (DMSO) fe w m i n (DMSO) 1 ' i 1 i 1 — r '— i — 1 — ! — '— i — '— i — 1 — r 3 * 3 3 2 * 2 f> 2 2 2 2 0 t * I f cow Figure 1.4 Solvolysis of CnRhMe(OTf)2, 3 in DMSO-t/^ with time, detected by !H NMR. r T T r T T T 3 . 2 3 . 0 2 . 8 2 . 6 2 . 4 2 . 2 2 . 0 1. B PPM' ^ Figure 1.5 lH NMR of [CnRhMe(H20)2](0Tf)2,13,in D2O. o _______ _ _____ R h r C h / y > T f JL V a J L Rh 2+ C H 3 O H ,OH2 ‘ v - j ' ~ r~ i i i | i i i i | - i i i i • i - 1 i i j t " T— r T ~ | [ " i | ; i 5.5 5.0 4.5 4.0 3.5 3.0 PPM i j i i rT -p -r 3 . 0 Figure 1.6 *H NMR of [CnRhMe(0Tf)(H20)]+, 14 and [CnRhMe(H20 )2]2+,13 in CD3 N 0 2 ' 17 equivalent of water (compare to 3) is added, the mono-aqua solvated [CnRhMe(OTf)(H20 )]+ can be cleanly generated and the coordinated water can be observed by 1 HNMR (Figure 1.6). Addition of another equivalent of water results in partial conversion from 14 to 13, and eventually a large excess of water causes complete conversion to 13 (Figure 1.6). Although 2 and 4 can be completely solvated by methanol, 3 can only be mono-solvated by ca. 20% in methanol at room temperature with 80% of 3 remaining unchanged. Complex 5, on the other hand, can be mono-solvated by ca. 60% in methanol at room temperature with 40% of 5 remaining unchanged. In both cases no di-solvated product can be observed by 1HNMR. The chemical shifts of 3 and 5 and their monosolvated species are all different since they bear different anions. The quantitative difference of mono-solvated species formed for 3 and 5 indicates that BF4“ is more weakly bonding than OTf". From the solvation experiments of CnRhMe(OTf)2, 3, the coordinating ability of the solvents were found to follow the following order:, MeOH < DMSO < water. The same trend was reported for the [Rh(NH3)5(OTf)]2 + system19 mentioned above. In this CnRh system, an interesting observation is that complexes CnRhMeX2 (X = OTf, BF4") are relatively harder to solvate than complexes CnRhMe2X (X = OTf, BF4-). This may be attributed to the fact that the effective positive charge on CnRhMeX2 is higher due to the di-substitution of relatively weakly coordinating ligands. The much stronger coulombic interaction between the higher charged rhodium in CnRhMeX2 (compared to CnRhMe2X) and its ligands may render the formation of the charged species unfavorable. In methanol, the second solvation is not observed. Water was found to be a 18 stronger ligand than OTf" for CnRhMe(OTf)2, 3, while for the CpM(CO)2 (L)OTf (M = Mo, W; L = CO, PR3 ) 17 system, the reverse trend was observed. The compound CnRhMe2 Br, 8 , very slowly solvates in DMSO at room temperature with a t ^ of ca. 1 0 days. CnRhMe2 Cl, 6 , on the other hand, solvates in DMSO much slower than compound 8 . CnRhMeBr2 and CnRhMeCl2 do not solvate in DMSO. Therefore, for this CnRh system, the coordinating ability of the anions follows the trend: BF4" < OTf" « Br" < Cl". Also, CnRhMeX2 was found to be harder to solvate than CnRhMe2X. The coordinating abilities of the solvents are ranked as follows: CH2 C1 2 « MeOH < DMSO < water. Spectroscopic Properties As in most organometallic systems, ]H and 1 3 CNMR are powerful tools for the characterization of CnRh complexes. The information obtained from NMR spectra of the CnRh complexes includes the symmetry of the molecule, degree of solvation, purity and even the electronic effect from the degree of substitution (n) of the CnRhMe3.n Xn (n = 0, 1, 2) complexes. The 1 HNMR spectra of CnRhMe3 , 1, in benzene-^ and DMSO-4j clearly demonstrate the C3 v symmetry of this molecule (although in the solid state, due to the restricted interconversion of puckered Cn conformations, the symmetry of the molecule is strictly C3 ), therefore all the methyls on the Cn ligand are equivalent, and so are the three methyls on rhodium (Figure 1.7). The two kinds of methylene protons (in and out of the Cn ring) couple each 19 other with second order behavior. The doublet peak of Rh(CH3 )3 is caused by 1 0 3 Rh (I = 1/2, 100%) coupling with 2Jri,h ° f 2.5 Hz. An interesting observation from 1 HNMR spectra is that the chemical shift of the NCjF j T 3 peak (8 2.26 ppm) of 1 is more down field than the NCH2 protons (8 1.58-2.07 ppm) if benzene-^ is used as the solvent. However, if D M SO -^ is used as solvent, the NCH3 peak ( 2.35 ppm) is more upfield than the NCH2 peaks (8 2.45-2.70 ppm). The chemical shift of Rh(C/f3 )3 also differs quite a lot in these two solvents (8 0.27 ppm for benzene-c^ and 8 -0.58 ppm for DMSO-cQ (Figure 1.7). The 1 3 CNMR spectra of 1 in benzene-<i6 and DMSO-d6, on the other hand, do not vary much at all: (in benzene-^, 5 -0.30 (Rh(C//3 )3 ), 48.24 (NCH3 ), 56.94 (NCtf2); in DMSO-J5, 8 -0.21 (Rh(CH3)3 ), 47.73 (NCH3 ), 56.72 (NCH2) ). The large chemical shift differences of the 1 HNMR of 1 seem to be caused by benzene solvent since the chemical shifts of 1 do not differ much in solvents other than benzene (e.g. THF, DMSO, CH2C12). The large differences in !HNMR chemical shifts in benzene compared to other solvents were also observed in CnScMe3 and CnYMe3 complexes.20 The reason why benzene effects the chemical shifts of !H nuclei so much more than those of 1 3 C nuclei is not clear at this point. The *H NMR chemical shifts of the RhC/73 peaks are found to be very sensitive to the degree of replacement of the methyl groups by electron withdrawing groups on CnRhMe3 _ n Xn (n = 0, 1, 2). As shown in Table 1.1, the ]H chemical shift of the RhC/f3 for CnRhMe3 is 8 -0.58ppm. The lH chemical shift of RhC//3 for CnRhMe2X is more down field in the range from 8 0.22 ppm 20 In Benzene-^ 1 — i— I— ]— i— i— I— I— j— I— I— i— i— I— i— I— r — i— j— i— i— i— I— ]— I— I— !— i— |— I— I— I— I— j— T - 2.5 2.0 1.5 1.0 .5 0.0 -.5 PPM 5 0.0 2.5 2.0 1.5 1.0 PPM Figure 1.7 1 HNMR spectra of CnRhMe3 , 1 in benzene-^ and DMSO-cL. 21 to 8 0.39 ppm. The chemical shift of RhC//3 for CnRhMeX2 is even more down field in the range from 81.54 ppm to 5 1.67 ppm. The excellent correlation between the NMR chemical shift of RhC//3 and the degree of substitution of electron withdrawing groups on CnRhMe3 makes it very easy to tell from 1 HNMR spectra of CnRhMe3 .n Xn (n = 0, 1,2) whether there are impurities resulting from a different degree of substitution for these compounds. Also from the 1 HNMR spectrum, based on the chemical shift of RhC/f3 (a typical doublet with J r ^ of ca. 2 Hz, which is very easy to detect), the degree of substitution by electron withdrawing groups of an unknown CnRh compound can be immediately deduced. Table 1.1 The correlation between the 1 HNMR chemical shift (8) of RhC//3 in CnRhMe3 _ nXn (n = 0, 1,2) and the degree of substitution, n (all in DMSO-d^). CnRhMe3 (n = 0) CnRhMe2X (n = 1) CnRhMeX2 (n = 2) 8 (ppm) -0.58 X = Br; Cl; OTf* 0.39; 0.32; 0.22 X = Br; Cl; OTf** 1.67; 1.54; 1.58 * Solvated [CnRhMe2(DMSO)]+; ** Disolvated [CnRhMe(DMSO)2]2+ , the 8 Rh-CH3 of monosolvated [CnRhMe(OTf)(DMSO)]+ is at 1.90 ppm. The 1 0 3 Rh-1 3 C coupling constant, Jr^ , may also offer valuable information about the degree of substitution of the methyl groups by electron withdrawing groups on CnRhMe3 _ n Xn (n = 0, 1, 2). As shown in Table 1.2, the jRhc ° f CnRhMe3 is 35.3 Hz. The Jr^ for CnRhMe2X are smaller and range from 26.6 to 28.6 Hz. For CnRhMeX2, the Jr^c's are even smaller, ranging from 23.0 to 26.5 Hz. The cause of this apparent correlation might be that the 22 rhodium-I3C coupling constants reflect the electron richness of the rhodium ! center. X-ray photoelectron spectroscopy of the CnRh complexes (Chapter 3) j has revealed that the electron richness of the these complexes follows the i sequence of: CnRhMe3 > CnRhMe2Cl = CnRhMe2Br > CnRhMe2OTf > j CnRhMeCl2 = CnRhMeBr2 > CnRhMe(OTf)2 > [CnRhMe2(CO)]OTf. In the case of CnRhMe2OTf and CnRhMe(OTf)2, due to the solvation of DMSO, the solvated complexes may be more electron rich than their corresponding non solvated compounds. The coordination of CO makes [CnRhMe2(CO)]OTf, 15, even less electron rich than CnRhMeBr2 and CnRhMeCl2. In fact, the coupling | constant between rhodium and the rhodium methyl carbon (JRhc) in 15 is 22.9 i i i i j : Hz, which is almost the same as that of CnRhMeBr2 (Jr^c = 23.0 Hz). This is i i again consistent with the correlation of the electron richness of the rhodium | center with the JR h C of the rhodium methyl. The reason why the 1 0 3 Rh-1 3 C | coupling constants of [CnRhMe2(DMSO)]+ and [CnRhMe(DMSO)2]2+ are so j ! close is not clear at this point. s i s I j j Table 1.2 The correlation between the Jr^ of RhCH3 in CnRhMe3 _ nXn (n = 0, ■ 1,2) and the degree of substitution, n (all in DMSO-d^). CnRhMe3 (n = 0) CnRhMe2 X (n = 1) CnRhMeX2 (n =2) ^R hC (Hz) 35.3 X = Br; Cl; OTf* 28.6; 29.5; 26.6 X = Br; Cl; OTf** 23.0; 24.4; 26.5 I * Solvated [CnRhMe2(DMSO)]+; ** Disolvated [CnRhMe(DMSO)2]2+ , the ; monosolvated complex [CnRhMe(OTf)(DMSO)]+ has Jr^ = 25.8 Hz. I 23 I As mentioned before, *H and 1 3 CNMR can reveal important information about the symmetry of molecules. Complex [CnRhMe(0Tf)(H20 )]+0 T f', 14 offers one of the good examples of utilizing NMR spectroscopy to identify the symmetry of organometallic compounds. As shown in the top spectrum of Figure 1.6, the rhodium center is chiral. This results in three distinct NCH3 peaks (labeled c) in the NMR spectrum. The ^C ^H } NMR spectrum of 14 (Figure 1.8), on the other hand, also announces the chirality of this complex. Due to the chirality of the rhodium center, nine ligand (Cn) 1 3 C peaks appear in the spectrum simply because all the ligand carbons are inequivalent. Reaction of CnRhM e2O T f with CO and C2H4 Complex CnRhMe2OTf, 2, and CnRhMe2BF4 , 4, were found to have similar chemistry in various reactions. However, 2 could be prepared in more pure form than 4, and so complex 2 is selected as the representative of them throughout this thesis. Trifluoromethanesulfonate (OTf‘) is a relatively weakly coordinating anionic ligand18. Therefore there is a readily available incipient coordination site in complex 2, this electrophilic site is susceptible to attack by stronger nucleophiles. We were particularly interested in the chemistry that might occur if ethylene or CO were introduced at this labile site. Caulton5 reported that the triphos (MeC(CH2PPh2)3) coordinated rhodium complex (triphos)RhMe2BF4 readily reacts with CO to give acetone and (triphos)Rh(CO)2+ (Figure 1.9). The triphos can be considered the phosphine analog of Cn (both of them are facially coordinating) except that 24 Figure 1.8 1 3 C{1 H}NMR of [CnRhi3CH3(0TfXH20 )]+0Tf-, 14 in CD3 N 0 2. 25 | triphos is much more crowded than Cn and also it demonstrates rich "arm-off' | behavior5 which has not been observed in the CnRh system so far. The mer- (PhMe2 P)3 RhMe2BF4 complex21 behaves similarly once it is exposed to CO. It first coordinates CO, and then acetone and [RhP4]BF4 are subsequently generated (Figure 1.9). In these two phosphine coordinated "RhMe2 BF4" systems, CO insertion into the Rh-CH3 bond followed by reductive elimination ! of acetone was observed. The Rh1 oxidation state seems to be the stable [ i I oxidation state for these phosphine coordinated complexes under these particular experimental conditions. | By treating CnRhMe2OTf with CO in CH2C12, Chunming Wang in our | group obtained the stable compound [CnRhMe2(CO)]+OTf", 15, quantitatively. l | Complex 15 does not exchange with 13CO over 9 days at 25 °C. It is stable and | does not undergo CO insertion into the Rh-CH3 bond even up to 80 °C for 24 h ! in CH2C12 (Figure 1.10). Clearly, the Cn coordination results in totally | different reactivity compare to the phosphine coordinated L3RhMe2X j complexes. Rh1 1 1 seems to be the stable oxidation state under this particular set of experimental conditions. The IR absorption band of the rhodium bound CO ( : i | DCO) of complex 15 is at 2020 cm"1 . The chemical shift (13CNMR) of the CO I i i i in complex 15 is at 187.9 ppm in D M SO -^ with the coupling constant of Jr^c ! = 70.1Hz. ; | Caulton5 reported that (triphos)RhMe2BF4 does not react with ethylene j i under mild conditions (ca. 1 atm of C2H4). No ethylene-coordinated adduct ; [(triphos)RhMe2(C2 H4)]+ could be detected. Under forcing conditions (100 psi 26 RK+ BF4 PPh2 PPh2 PPh2 "triphos" CO, 1 atm CH2C12, 2 5 0 c fast rn O / k ♦ \ k rn oc/ \ o [(Me2 PhP)3 RhMe2]BF4 CO, latm THF, 25°C CO Vacuum + T L— ^ h — Me L Me O ^ k CO, CH2 C12 Figure 1.9 Reaction of (triphos)RhMe2BF4 and (Me2 PhP)3 RhMe2 BF4 with CO n N- n N- J / CO, 1 atm | y / Rh CH2 C12 , 25°C '''Rh + OTf- Very stable m / \ OTf fast r H / ^ X CO C °mpleX c h 3 c h 3 3 CH3 2 IS Figure 1.10 Reaction of Complex 2 with CO. 27 of ethylene), [(triphos)Rh(C2 H4 )2 J+BF4 was generated nearly quantitatively (Figure 1.11). On the other hand, (Me2 PhP)3RhMe2 BF4 reacts with C2 H4 to immediately give ethane and [RhP4 ]BF4 2 1 (Figure 1.11). In both cases Rh1 is the stable oxidation state of the final product and no ethylene insertion into the RI1-CH 3 bond was observed in either of the two reactions. An interesting question here is whether CnRhMe2 OTf, 2, has reactivity different from its phosphine analogs upon reacting with ethylene since the reactivity of 2 toward CO is totally different from its phosphine analogs. By reacting CnRhMe2 OTf, 2 in CD2 C1 2 with latm of 1 3C-ethylene in a sealed NMR tube at room temperature, the rhodium methyl groups of 2 disappeared and methane-12C was formed as detected by 1HNMR. ^C ^H JN M R verifies the disappearance of 2 , it also indicates that the products are two isomers since there are two pairs of high intensity 13C peaks at 53 ppm and 116 ppm. The high intensity of these peaks in the ^C ^H jN M R spectrum and the detection of only 1 2CH4 by 1 HNMR demonstrate that methane's carbon came from 2 while the products' carbons came from 1 3C-ethylene. The transformation is quantitative. No intermediates could be detected at room temperature since once the reaction mixture was allowed to warm up to room temperature, the transformations were complete. To try to understand the reaction and monitor possible intermediates that might be involved along the reaction coordinate, variable temperature (VT) NMR experiments were carried out. The obvious hope was that by lowering the temperature of the reaction system, the rate of the reaction would be slowed down, making intermediates observable. 28 PPh2 -PPh2 PPh2 "triphos" ~hi + b f 4 - CH{ CH3 rn ■ k . / . CH2=CH2, 100 psi CH2Cl2 [(Me2 PhP)3 RhMe2]BF4 CH2-CH 2 5 2 atm » ■ CH3CH3 + RhL4 + + . . . CH2C 1 2 Figure 1.11 Reaction of (triphos)RhMe2BF4 and (Me2PhP)3RhMe2BF4 with CH2=CH2 The first experiment was to react CnRhMe2 OTf, 2, with 1 3C-ethylene in CD2 Cl2 . One atmosphere 1 3C-ethylene (ca. 4 eq to Rh) was transferred by temperature. The flame-sealed tube was then placed in a dry ice-acetone bath before the VT NMR experiment. The -78°C sample tube was quickly placed in the NMR probe with the pre-set temperature of -80 °C. At -80 °C, only the starting materials 2 and 1 3C-C2 H4 were observed. Once the probe's temperature was allowed to warm up to -57 °C, one doublet peak grew slowly at 78.94 ppm as indicated by ^C ^H JN M R . The !H coupled 13C NMR spectrum revealed that this intermediate was ethylene-coordinated complex [CnRhMe2(13- C2 H4 )]+OTf“, 16, since it exhibited a triplet of doublets. The J^ C ^ H * s 162 vacuum line to the CD2 Cl2 solution of 2 in a NMR tube at liquid nitrogen 29 Hz and the J 1 0 3Rh1 3 C * s 8 - 2 Hz. At -57 °C, no further reaction from this complex was occurring. At -47 °C, two 1 3 C NMR doublet of doublet peaks grew slowly at 36.4 and 104.1 ppm with the same U ^C -^C coupling constant of 43.4 Hz, indicating that these two carbons are connected carbons in the molecule and they are from 1 3C-C2 H4. The !H coupled 13C NMR spectrum revealed that one of them is a CH2 group (tdd, 5 36.4 ppm, JC h = 162 Hz, JCc = 43.4 Hz, JRhc = 10.9 Hz) and the other one is a CH group (ddd, 8 104.1 ppm, JC h ~ 156 Hz, Jcc = 43.4 Hz, = 6 . 2 Hz). Both of the carbons are sp2 carbons. Meantime, the 1 HNMR spectrum indicated the formation of rhodium hydride at -22.40 ppm. 1 2C-methane could also be observed by 1HNMR. Allowing the probe to warm above 0 °C resulted in formation of the two isomers as final products as mentioned above. From this experiment, ethylene coordinated intermediate 16 was observed. One possible explanation for the formation of the rhodium hydride intermediate and 1 2C-CH4 at that point was that the coordinated ethylene inserted to one of the Rh-CH3 bonds to form the transient intermediate [CnRhCH3 (C3H 7 )(solv)]+, 17, which experience fast J3-H elimination to give [CnRhCH3 (H)(propylene)]+, 18, a compound whose hydride could be observed at -22.40 ppm. This complex was thought to experience methane reductive elimination to liberate CH4 and generate two isomers of [CnRh(propylene)(solv)]+, 19. But the fact that the rhodium methyl proton absorption peak of complex 18 could not be observed in NMR spectra argued against the assumption that the rhodium hydride was attributable to complex 18. Also, the explanation of two isomers of complex 19 as final products did not seem to be a satisfying answer. To try to fully understand the course of the reaction, a second VT NMR experiment was carried out. 30 The second VT NMR experiment basically followed the experimental I conditions as the first except that in this case CnRh(1 3CH3 )2 OTf, 2-1 3C, and | 1 2C-C2 H4 were used as reactants. This would certainly fill in the missing | information by using different isotope labeling than the first VT experiment. At j j -43 °C, the rhodium methyl peak of [CnRh(1 3CH3 )2 (C2H4)]+ could be clearly ; ; observed at 8.20 ppm (Jr^c = 22.5 Hz) by 1 3C{1H}NMR. This again ! confirmed the formation of the ethylene-coordinated complex 16. By waiting a longer time at this temperature, we observed a 1 3C{1H}NMR doublet peak growing in at 36.4 ppm (JRhc = 10.9 Hz). This was exactly the same peak as j observed by reacting CnRhMe2OTf with 1 3C-C2 H4 in the first VT experiment. j ' I | | This means that this 13C peak's carbon came from both ethylene and the i i rhodium methyl of complex 2. Since both of the two carbons ( 8 36.4, 104.1 | ppm) of this intermediate are sp2, a reasonable explanation is the formation of | allyl hydride [CnRh(r|3 -allyl)(H)]+, 20, instead of complex 18 in which the three carbons on the propylene would all be different. Complex 18 probably i j i I was involved in the reaction sequence but the subsequent methane loss followed | by C-H activation of the allylic carbon to form complex 20 was too fast to make | I i j 18 and 19 observable. The final products were thought to be the two rotational | j | j i I isomers of allyl chloride [CnRh(r|3 -allyl)(Cl)]+, 21, which resulted from ; chlorine exchange with CD2 C1 2 solvent. j | To confirm the above information and to make a complete story, j CnRh(1 3 CH3 )2 OTf, 2-13C and 1 3C-C2 H 4 were selected as reactants in a third VT NMR experiment. As shown in Figure 1.12, the reaction proceeded as I j ■ I I expected. At -80 °C, the Rh-CH3 peak of complex 2-13C at -0.85 ppm (JRhc = I I 31 | 29.4 Hz) was the only CnRh peak that appeared in the ^C ^H JN M R spectrum. At -31 °C after 50 min, the concentration of 16 reached its maximum at which I time a small amount of allyl hydride 2 0 was also formed. On staying at -15 °C : for 1.2 hr, all the transformation to allyl hydride 20 was completed. The j j formation of 1 3CH4 was also observed. On warming up to room temperature, | the allyl hydride was quantitatively transformed to the allyl chloride products, | j 21, as indicated by 1 3 C NMR. The elemental analysis results are consistant I 5 with the chemical composition of 2 1 . ! The 3 H NMR spectra of this reaction sequence are much more [ complicated than the 1 3C{1H}NMR spectra. The successful assignment of the j reaction species in the ^C ^H JN M R and 13C NMR spectra made it possible to ; assign the reaction species in the !H NMR spectra. As shown in Figure 1.13, at j -35 °C, the ]H NMR absorption peaks of the intermediates can be assigned. 1 i i After 2.4 hr at -35°C, the ligand methyl peaks, rhodium methyl peak and even j | the coordinated ethylene peak ( 8 3.27 ppm, J r ^ =1.5 Hz) of complex 16 are j I distinctive. About 5.7 hr later, allyl hydride , 2 0 , is the dominant species. The | i | central allyl proton is at 4.32 ppm (tt, J^ns = 11.8 Hz, Jcis = 7.3 Hz) coupled by | i j j | two trans and two cis protons to give nine peaks in a ratio of 1:2:2:1:4:1:2:2:1. j | i The absorption peak of the protons that are trans to the central allyl proton is at ; ! 2.17 ppm (Jtrans = 1 1 . 8 Hz) whereas the peak of the cis-protons is at 2.58 ppm j j (Jcis = 7.3 Hz). The assignments were further confirmed by homonuclear decoupling NMR experiments. The principle of these experiments is that for nuclei that are coupling to each other, if one is irradiated to saturation, those 1 E | ; coupled to it will lose their coupling. The allyl ligand's 1 HNMR absorption j ! 32 j [ ! bands in complex 2 0 are in the normal region of metal-ri3-allyl compounds22. The 2 to 20 transformation is quantitative as indicated by NMR. To study the structure of final product 21, its yellow single crystals were obtained by ether diffusion into a concentrated methylene chloride solution of 21 under nitrogen at room temperature. As shown in Figure 1.14, the allyl group is parallel to the Cn ligand. The central allylic carbon is pointing away from the chlorine atom. The OTf“ group is not bonded to the rhodium center and so is not shown. The structure in Figure 1.14 presumably represents one of two isomers which exist in solution. The crystal of 21 suffered severe decomposition in the X-ray beam, so the R factor is ca. 9%. The full reaction scheme is listed in Figure 1.15. Notice that the arrows between complexes 2 and 16, 17 and 18, as well as 19 and 20 are all labeled as reversible. The reason for this will be explained in the following deuterium labeling and kinetic experiments. One conceivable alternative pathway of methane formation would involve a-elimination of hydride from a methyl group, e.g., formation of [(k2 N,N'-Cn)Rh(H)(=CH2 )(CH3 )(T 12 -CH2 =CH2 )]+. Therefore, C2 D4 was used to react with 2-1 3C. If methane is generated via the carbene path, then it should be 100% 1 3CH4 . 2 3 On the other hand, if the reaction is going through the ethylene insertion path as mentioned above and the transformation from 17 to 18 is not reversible, 100% 1 3CH3D (no 1 3CH4) should be generated. At -30 °C, the reaction between 2-13C and C2 D4 resulted in the formation of 83% 1 3CH3D and 17% 1 3CH4. This result eliminates the possibility of direct generation of methane from a carbene complex itself since that would give 100% 1 3CH4. The CH, 25 °C, 4 hr ca, CH, -15‘C, 1.2 hr ' V . -31*C, 50 min JTSPV N N „ X l / ^CH, C "* Rh V^OTf *CH, -43’C, 1.5 hr A Rh-UCH3 1 3 C {1 H> NMR CnRh(,3CHj)jOTr + 4 > 3 CH2 =>3CH2 in CD2 C12 -80°C, 45 min t t t f j i n i j i i i r p f r r j r r l i . j " »' "T 7 i j r U S It* M IN * • i ) J I F T T 7 T ' i H T T T T I r T TTrrrl l I S t* I I i I m j r r r r f & ppm Figure 1 . 1 2 1 3C{ ^ JN M R spectra of the reaction of CnRh(1 3CH3 )2 OTf, 2-13C in CD2 Cl2 with l3 C-C2 H4 with temperature. CH, 5.7 hr CH, . J j L - Rh C H ; CH; 1.1 hr CH, I 1 ! ' i 1 I 1 I 1 I 1 I 1 I 1 I 1 i 1 i ' I 4.B 4.4 4.3 4 .a ] . l 3.8 3 4 3.3 3 3 M 3.8 3 . 4 ' 3.3 i 1 ! 1 ! 1 ! ' T 2.0 l.a 1.6 1.4 T ~T ; r 2 1.0 T a 2 4 s ppm Figure 1.13 1 HNMR spectra of the reaction of CnRhMe2OTf with C2 H 4 in CDoCU at -35 °C with time. Figure 1.14 ORTEP drawing of the molecular structure of the cation part of [CnRh(rj3 -allyl)(Cl)]OTf, 21(structure solved by Roy S. Lu and Robert Bau). Rh CH3 £H3 N ° Tf N < ! / ^ Rh + ^ i V ^ - CH 18 I- CH4 N N. * 0 / Rh + (solv)^ Ns^ ^ ' ' 19 c h 2 = c h 2 c d 2ci2 above -57°C fast N jj Rh + r' w ^ 3 CH 16 above -47° C <W Rh + CH3 / i n / c h 3 / = c h 2 - c h 2 (solv) 17 / ? S ? ^ -N N. ' 1 / Rh + H 20 -N N - ' 1 / Rh + >-10°C s c d 2ci2 c r 21 Figure 1.15 Scheme of the reaction between CnRhMe2OTf, 2 and ethylene. 37 presence of 17% 13CH4 also suggests that isomerization of Rh(CD2CD2 13CH3) in 17, presumably to Rh(13CH2CHDCD3) by 0-hydride elimination-insertion as in 17 = 5 =^ 18 , is competitive with the reductive elimination of methane from 18 (Figure 1.16). The labeled allyl hydride 20 formed at -30 °C contains all of its 13C-labeled carbon as 13CH2 and the central allylic carbon is fully deuterated, so 17 can not be extensively scrambled. 1 HNMR integration reveals a maximum of 1% of the intensity of one H at 8 4.3 where the central allyl resonance of 20 appears. Also, as little as 2 or 3% of 13CHD would be easily detectable in the presence of 13CH2 in the ^-coupled, 13C spectrum of labeled 20, [CnRh(H or D)(rj3-CD2CD13CH2)]+, but none is observed. Production of 17% 13CH4 and a maximum of only 1% of 20 with a central allyl C-H suggests that the H/D isotope effects on both 0-H elimination from labeled 17, [CnRh(13CH3)(13CH2CHDCD3)]+, and reductive elimination of methane from labeled 18, [CnRh(i3CH3)(D)(i3CH2=CHCD3)]+, are large (Figure 1.16A). The production of 17% 13CH4 and formation of 100% 13CH2 allyl hydride 20 strongly argue against the possibility that 17% 13CH4 was generated from C2D4 insertion into the Rh=CH2 bond in [(K 2N,N'-Cn)Rh(H)(=CH2 )(CH3 )(r12- CD2=CD2)]+ followed by hydride metallocyclobutane reductive elimination and subsequent chemistry of reversible 0-H elimination-insertion similar to the scheme shown in Figure 1.16A, since the generation of 17% 13CH4 by this path would certainly result in formation of at least a few percent of 13CHD at the 13C-labeled allyl hydride position. This would be easily detected by 13C NMR. A third conceivable mechanism for C-C bond formation might involve a cr-bond metathesis of 3-(13C)2 with C2D4 liberating 13CH3D followed by 38 reductive elimination from [CnRh(C2D3)(13CH3)]+ to form labeled 19, [CnRh(r| 2-CD2=CD13CH3)]+, and from there labeled 20, complex F (Figure 1.16B). But this mechanism is difficult to reconcile with formation of 17% 13CH4 in the C2D4 insertion experiment since the initial metathesis would form only 13CH3D. Generation of 13CH4 would require subsequent rapid metathetical | exchange at -30 °C of 13CH3D with a Rh13CH3 group in either 3-(13C)2 or [CnRh(C2D3)(13CH3)]+— complex B (Figure 1.16B). No other source of H for | the CH4 is reasonable for the metathesis mechanism since the yield of allyl r I | hydride is essentially quantitative and the stoichiometry requires quantitative I I I involvement of both methyl groups. It was found that an 8-fold excess of CH4 undergoes no detectable (< 1%) a-bond metathesis with 2-(13C)2 at 20 °C over 15 h in CD2C12. Therefore, path X in Figure 1.16B is ruled out. However, it is still possible that 2 and B would metathesize methyl groups at comparable rates through path Y in Figure 1.16B to generate 17% *CH4. The following argument is against this possibility. That is, in the reaction of 2-(*C)2 with i C2 D4, the 17% of *CH4 would have to form by metathesis of the initially formed *CH3 D with intermediate B to give C. Complex C should account for 17% of all the rhodium species. Intermediate C would then generate somewhere between 11 and 17% E with one deuterium on the 1 3 C-labeled allyl carbon, depending on the H/D isotop effect for allyl C-H activation. The I deuterium coupled material at the allyl 1 3 C chemical shift could not be detected j where 2-3% would have been easily visible. Therefore, path Y of a-bond I ' i metathesis is also ruled out. ■ 1 \ ! 39 I "Rh" - CnRh* 1 3 ^ C D , CD2 CI2 > -30 °C I // -------- — * K - V ^CD, c® 2 Insertion CHi 0 1 3 * T X-° \ ^*CH3 X - ‘C H ^D Rh--— . ^ — C ° 2 83% •CH, r 4 - CD, 17% •CH, X X y / CD, < 1% 7/ CD, X — - chr X / / I CD \ ^ C H j c — 83% •cH r R 1^ X ,CH3 XC D j X t (X h T ) C <■ D \ 0)3 17% H / \ D CD3 H 0 \ / * C H T 'R K ^CHf'C D X B ■ f - o r | w r ' c v I C “ N co, < 1% • C H - iD G X ' cd3 X D . / \ E H CD, etc. Figure 1.16A Isotope labeling experiment of 2-1 3 C and C2 D4 at -30 °C. After the 16 to 20 conversion is complete at -30 °C, warming to -15 °C causes the slow isomerization of deuterium onto the 13C allyl carbon as indicated by the ^-coupled, l3C NMR spectrum (Figure 1.17) without any appearance of a proton resonance for the central allylic position, indicating that the 19 20 transformation is reversible. The reversible equilibrium results in the scrambling of isotopic labels on the terminal allylic carbons without affecting the central allylic carbon (Figure 1.18). Based on calculation, the ratio of different possibilities of isotopic combination for the terminal 1 3 C allylic carbon after the scrambling comes to equilibrium will be CH2 :CHD:CD2 = 2:4.48:1 (assuming the equilibrium kinetic isotope effect KH /KD of rhodium hydride and rhodium deuteride is 1). As shown in Figure 1.17, although the 1 3 CD2 peak (should be very broad) is not as distinct as 1 3 CH2 (triplet) and 1 3 CHD(large doublet), it does seem to exist since the base line of the expected 1 3 CD2 region is much higher than the normal baseline. Also the integrals of the peaks that presumably have 1 3CD2 underneath them are larger than those of the peaks that do not overlap or have less overlap with the absorption peak of 1 3 CD2. The integral ratio of 1 3CH2:1 3 CHD =1:2 clearly excludes the possibility that exchange only occurs between the inner allyl protons and the rhodium hydride (or deuteride), in which case the ratio would be 1:0.64. The 1 3 C atoms of 1 3CH2 and 1 3 CHD may have slightly different T, which might affect the integrals. Since 1 3 CHD very likely has a longer Tx than 1 3CH2, then 1 3CHD's integral reflects less percentage of 1 3CHD. Therefore, the argument is still resonable even if their Tj values affect the integration. 41 "Rh"= CnRh+ / Rh *CH{ *CH3 2 -(1 3 C)2 + CD2-CD 2 -*c h 3 d PathY * C H //R hxeD B & +*c h 3 d - * c h 4 PathX +CD 2=CD2 - *CH2D2 + CD2=CD2 D, +*c h 3 d -*CH4 /R h *C H / n * c h ,d --------- -*■ H2D*C' CD -*c h 3 d C CD, Rh V * C H 3 D ,C 19 / H * c h 2 Rh—) C -D d o 2 20(F) \ *CHD *CH2 Rh—) c - D + Rh—)c-D H (^d - D 0 3 , D Rh. t - * C H 2 D E D I j Figure 1.16B Possible a-bond metathesis paths. ; ! Based on the observations so far, the reaction has a very strong | ■ ■ I | | temperature dependence. At -80 °C, ethylene does not interact with 2. Once the | | temperature warmed up to -57 °C, ethylene-coordinated complex 16 is formed | but ethylene insertion into the Rh-CH3 bond does not occur at this temperature. ? I : : . ! l | | Warming to between -47 °C and -30 °C results in ethylene insertion. | f Subsequent p-H elimination-insertion between 17 and 18 competes with Is i! | i : ! ; 4 2 i Cn R h HX> Cn H.D Rh. H.D H.D H.D A t-15 °C for 10 h H.D 34.0 35.5 35.0 34.5 36.0 36.5 37.5 37.0 38.5 38.0 □ D U j Figure 1.17 coupled) NMR o f the isotope scrambling of 20 at -15°C 43 methane reductive elimination, and formation of the allyl hydride 20. Complex 2 0 does not reductive eliminate to form 19 until the temperature is raised up to -15 °C. Warming above -10 °C results in chlorination to the allyl hydride. The temperature dependence of the transformations implies that different kinetic barriers exist in different steps, presumably in an increasing sequence, step by step. This reaction offers a rare example of direct observation of the insertion of an alkene into the metal-carbon bond in a well-defined M(R)(alkene) complex. 2 4 To fully understand the ethylene insertion into the Rh-CH3 bond in this reaction, kinetic experiments were carried out. Kinetic experiments were first carried out at -36 °C with 2 and ethylene's concentration in CD2 C1 2 to be 0.055 M and 0.15 M, respectably. Since the concentration of intermediate 16 is significant during the reaction, the steady D D D D CnRh Y>— D CnRh + CnRh )V D ( i v j n D Figure 1.18 The reversible equilibrium of 20 and 19 at - 15°C state approximation can not be applied to the kinetics of the transformation between 2 , 16 and 2 0 , so the fully integrated equation must be used. Also, it was unknown whether the transformation between 2 and 16 is reversible, therefore it must be assumed at first to be reversible. The 2 = 5 =^ 16 -> 20 transformation can be followed by monitoring the concentrations of 2 , 16 and 20 versus the internal standard benzene by 1 HNMR integration at -36 °C. The integrated kinetic equations2 5 of the concentrations of X, Y and Z for kl m X Y Z are as follows: = m 2 - ki g-m ^ + kt - mt e_ m2t m 2 -m 1 m2 - m 1 Y = 5 ^ 5 1 { e-m “ - e " " * } m 2 -mit mi -m9 t 7 = _ ----- — e 1 + — e z + i ^ m2- m x m2 - mj ^ 1 m i - y { ( k i + k. 2 + k3 ) - a / (k 1 + k. 2 + k3 ) 2 - 4kxk3 m 2= 2 " { ( ki + k -2 + k3) + V ( k 1 + k .2 + k3 ) 2 - 4kjk3 m[m2 = kjk3 Rate constants k1 } k. 2 and k3 for reactions of 2 and 16 were determined kl by fitting calculated concentrations for first order reactions 2 16 2 0 to the experimental data. At -36 °C, with concentrations of 2 and ethylene at 0.055 M and 0.15 M, respectively, the kb k_2, and k3 are 1.52x10^, 4xl0-6, and j 1.38xl(M s'1 , respectively. The k_2 term was found to be necessary to give the j best fit of the calculated concentrations with the experimental data. This is why | in Figure 1.15 the transformation between 2 and 16 was labeled as reversible. The simple kinetic representation of this process is shown in Figure 1.19: + I CnRh j j j Figure 1.19 Kinetic expression of the transformation of 2,16 and20. I \ I Disappearances of 2 and 16 are each first order at constant excess ethylene concentration. The pseudo-first order rate constant for disappearance of 2 is nearly independent of ethylene concentration! A 34 fold increase in [C2 H4] leads to a 58% increase in kj (Table 1.3). This implies that the j j ’ substitution reaction 2 — » 16 is dissociative, probably to an ion pair, with triflate i | dissociation being largely rate determining. Figure 1.20 demonstrates the full kinetic scheme of the transformation. Notice that the kinetic expression in I Figure 1.19 still stands since it is a the simplified version of the scheme of ! ; Figure 1.20. The term in Figure 1.19 can be treated as kobs which contains kb i l i , | | k.r and k2 [C2 H4] terms in Figure 1.20. | The line fitting of calculated concentrations for the first order reaction | j I sequence of 2 = 5*=^ 16 -> 20 at -36 °C to the experimental data is shown in Table 1.3 Changes of rate constants with [C2H4] at -36 °C([2]0 = 0.055M, CD2CI2). Figure 1.20 Full Kinetic scheme of the transformation of 2,16 and 20. Since this reaction offers a rare opportunity of observing the olefin insertion into the metal-alkyl bond in a relatively wide temperature range, kinetic experiments were carried out in the range of -48 to -23 °C to determine the activation parameters of the ethylene insertion step. From the lnk3 ~ 1/T plot and ln(k3/T) ~ 1/T plot as shown in Figure 1.22 and Figure 1.23, the activation parameters for the insertion reaction of 16 at -36 °C were determined. They are Ea = 19.2 (0.6) kcal/mol and AS* = 3.3 (2.6) eu. The small AS* (close to 0 eu) is consistent with the fact that the ethylene insertion into the rhodium- methyl bond in 16 is an intramolecular migratory insertion and there is no significant difference of orientation of solvents for the intermediate cation 16 in its ground and transition state of the reaction. [C2H4] kl(observed)(s_ 1 ) 1.98 M 0.15 M 0.058 M 2.24 x 10-4 1.52x10-4 1.42X10-4 In(F igl.l9) k j= ko5s = ki’k3[C2 H4] (In Fig 1.20) k_j + k3[C2H4 ] k2 [C2H4] 2 V 16 20 47 CH, ^ \^ o m C H, c o a u f l a > o f i o \t-36°C: = 1.52 x 10*4 i ! = 4.0 x 10-* time Figure 1.21 Line fitting of calculated concentrations (in line) for 2 16 -* 20 to the experimental data. ([2] 0 = 0.055 M, [C2 H4] = 0.15 M, -36°C in CD 2 C12) I The reaction of alkene insertion into metal-carbon bonds in transition 1 | metal complexes is very important in organometallic chemistry. The insertion reactions of olefins into the metal-carbon bond of unsaturated d° metal alkyl | complexes have been extensively studied since the electrophilic d° species are I clearly the active intermediates in Ziegler-Natta catalytic systems. 2 6 So far, I none of such olefin alkyl complexes has been observed as intermediates in these 48 10.5" 1 0 - 9" 2 c T 8 .5 ’ 7.5- Regression Output Constant -31.9071 Std Err of Y Est 0.1118 R Squared 0.997781 No. of Observations 4 Degrees of Freedom 2 X Coeffident(s) Std Err of Coef. 9644.036 321.6249 1/T(X1000) Figure 1.22 The lnk3 ~ 1/T plot for the insertion reaction of 16 (- 48° to - 23 °C) d° systems. For dn systems when n > 0, a few stable alkyl olefin complex have been isolated, but many of these complexes do not exhibit olefin insertion reactions presumably due to high kinetic barriers. 2 1 ’2 6 * 2 8 For CpNi(C2H4 )R24(a) and C 5R 5Co(C 2 H4 )(CH3 ) 2 (R = H, CH3 ),23’ 24< b) (3-migratory insertion of j ethylene into the M-C bond was observed. Recently, a few metal alkyl olefin | complexes of group IV, d2 metal complexes have been observed but none of j j them undergo Ziegler chemistry. 2 7 Brookhart9 > 2 4 ( d )’2 6 has reported the AG* for I the p-migratory insertion reaction of [Cp*Rh[P(OCH3)3](C2H 5)(C2 H4)]+. I However, only in one case have all of the activation parameters been reported for the ethylene insertion into the Rh-C bond, that is, in the case of j [ C 2H 5R h (C 2H 4) C l3( s o l v ) ] +.30 This 2 16 — » 20 transformation is a rare example of direct observation of olefin insertion into the metal-carbon bond in a well-defined M(R)(alkene) complex. 2 4 '2 6 The 162 Hz L H - ,3C coupling constant of the I coordinated ethylene in complex 16 does not seem to be informative about the extent to which the C=C bond is weakened in 16 (UC H coupling constants for transition metal ethylene complexes are typically 150-160 Hz) . 2 7 A better | | experiment might be running a VT Raman experiment at -50 °C to first allow 1 the concentration of 16 to build up and then measure the stretching frequencies of the coordinated ethylene and free ethylene. This would provide direct ; evidence about the extent to which the C=C bond is weakened in 16. Regression Output Constant -25.4377 StdErrofYEst 0.111183 R Squared 0.997693 No. of Observations 4 Degrees of Freedom 2 X Coeffirient(s) 9406.945 Std Err of Coef. 319.8487 3 96 4 4.05 4!l 4.15 4.2 4 2 5 4.3 4.35 4.4 4.45 1/T(X1000) Figure 1.23 Eyring plot for ethylene insertion reaction of complex 16. a-olefins were also selected to react with complex 2 in CD2 C12. VT NMR experiments revealed that the reaction between 2 and propylene, ethyl vinyl ether and vinyl bromide are all very complicated and not clean, although they all appear to first undergo the insertion reaction with liberation of methane. The only a-olefin which was investigated that has clean chemistry with 2 is methyl acrylate. Chunming Wang in our group found that methyl acrylate reacts with 2 in a fashion similar to ethylene to give the substituted allyl chloride product with the ester group at the terminal position of the allyl. The methyl acrylate-coordinated intermediate could not be detected in a VT NMR experiment. Polymerization of Ethylene As complexes 2 and 4 demonstrate well defined ethylene insertion chemistry, it would be a logical question to ask whether complexes 3 and 5 (CnRhMeX2) will also have rich ethylene insertion chemistry since they also have a Rh-CH 3 bond and relatively weakly coordinated anions. Upon reacting complexes 3 or 5 in CH3N 0 2 with 5 -2 5 atm of ethylene in sealed glass tubes at room temperature, polyethylene was obtained. At room temperature, under ca. 15 atm of ethylene and at ca. 0.01 M 5, precipitation of polyethylene from CH3N 0 2 or CH2 C1 2 begins within 2 0 minutes and from acetone or THF in several hours. The solubilities of 3 and 5 are poor in CH2 C1 2 and THF. Beginning with 15 or 25 atm of ethylene and 0.01 M 5 in sealed glass tubes, continued agitation of the samples resulted in the formation of white colored polyethylene . The Mw is 8,800-15,000, the polydispersity is in 51 I : the range 2-2.3 (Table 1.4). Infrared spectra show no detectable branching , indicating that it is high density polyethylene2 9 which is typical for Ziegler- | Natta type ethylene polymerization. The relatively faster polymerization rate in ! CH3N 0 2 and CH2C1 2 may be attributed to the fact that they are relatively j j I I weakly coordinating solvents. Although reaction initiates faster in CH3N 0 2 j ! than in acetone, the Mw of the polyethylene obtained from acetone is larger I I I than in CH3N 0 2 (Table 1.4). The reason for this is not clear at this point, j j As indicated by the polydispersities (2-2.3), these coordination j i polymerization reactions are not living polymerization. At high ethylene j ; ! 1 ; Table 1.4 physical properties of polyethylene generated from different I conditions in non-protic organic solvent. Solvent pressure (atm) Time (day) Mw m n Mw /Mn m.p.(°C) Acetone 15 7 15,000 6,500 2.3 120-125 Nitromethane 15 7 8,800 4,500 2 . 0 120-125 Nitromethane 25 7 13,600 6,500 2 . 1 120-130 concentrations (PC 2h4 = 8 atm), very small amounts of terminal olefin side products (including propylene) can be observed. They presumably result from ij J3-H elimination from the Rh-alkyl chain. At low ethylene concentrations \ (PC2 H 4 < 1 atm), the amounts of terminal olefin side products are significant. To study the mechanism of the chain propagation and chain transfer of this reaction, a VT 1 3C{1H}NMR experiment was carried out. Some 13% 1 3C- i i j 52 ! labeled CnRh*Me(BF4)2, 5, (0.11 M in CD3N 0 2) and 1 3C-labeled ethylene (5 I atm) were sealed in a NMR tube at low temperature. At -20 °C , no ethylene | i complex of 5 could be detected, and no polymerization occurs. At room \ temperature, polymerization occurs rapidly, but again no ethylene complex of 5 \ could be detected. As shown in Figure 1.24, after warming the sample to 25 °C for 30 min, the resonances of the methyl terminus (5 14.5 ppm) and the first methylene ( 8 23.8 ppm) of the polymer can all be clearly observed by 1 3C{1H}NMR, as well as a huge peak at 30.8 ppm corresponding to the large | amount of polymer that has been formed. If no chain transfer reaction (p-H elimination) were to occur, the methylene peak at 8 23.8 ppm should be comprised of 13% triplet and 87% doublet peaks which would be attributed to I | 13% of R-*CH2-*CH2-*CH3 and 87% R-*CH2 -*C/7r CH3, respectively. As I shown in Figure 1.24, at 5 atm of ethylene for 30 min at 25 °C, the triplet peak counts for a little more than 13% of the overall area at 23.8 ppm indicating that P-H elimination is a minor path (but it is operating) under 5 atm of ethylene and j so chain propagation is dominant. 1 3C{1H}NMR spectra also show that as ( 1 3C)2 H4 is consumed, the amount of 1 3 C in the methyl terminus of the polymer increases , and the resonance of the first methylene of the polymer j ( 1 3CH2 1 3CH2 CH3 ) exhibits an increasing percentage of triplet and less doublet. I Apparently, as ethylene pressure decreases, the rate of p-elimination followed by ( 1 3C)2H4 uptake increases with respect to the rate of ethylene incorporation into the growing polymer; i.e., the transfer/propagation ratio increases. The | kinetics of reaction of CnRhMe(OTf)2, 3, and ethylene in the 3-catalyzed ethylene polymerization have not yet been measured. There are no literature precedents for rhodium-based polymerization of ethylene -- heterogeneously or homogeneously; single component or with co- catalysts or activators. Only the dimerization of ethylene by rhodium complexes has been reported previously. 9 > 2 4 (d )>2 6 > 3 0 Cramer3 0 reported the rhodium chloride catalyzed dimerization of ethylene to linear butenes. As shown in Figure 1.25, rhodium trichloride is first reduced to a bis(ethylene)rhodium(I) complex, A (path la). Complex A can also be generated by reacting (C2H4)2 Rh(|j.-Cl)2Rh(C2 H4 ) 2 with HC1 (path lb). "RhCl3 .3H20" C2H4 (la) C2H4 + [C2H5RhniCl3S2]2- C +s [(C2H4 )2Rh(p-Cl) ] 2 [Cl2RhI(C2H4)2 ]“ - ™ »• [C2H5RhniCl3(C2H4)s]- A C2H4 (4) (2) B +s [Cl2RhiS (CH2CH2CH=CH2)]- E (3) - HC1 [CH3(CH2)3RhniCl2 s2]- D s = solvent Figure 1.25 Mechanism for the formation of 1-butene30. Starting from complex A, the catalytic mechanism was believed to follow the four steps as shown in Figure 1.25. It was found that at high ethylene pressures and in ethanol solutions above ca. 0.1 M HC1, most of the 54 25 C 1 day L J 25 C 30 min 0 c 1 hr R -*C H 2 -*C H 2- C H 2-R r - * c h 2 - c h 3 R -*C H 2 -C H 2 -C H 3 + R-*CH 2 -C H 2 -*CH 3 J n 1 i ' i > i ■ i — '— [ .~t~ i ' i 1 i ' i 1 i * i ■ i i i i 36 34 32 30 2R 26 2< 22 20 13 16 14 12 10 PPM Rh-CH3 (13% 13C) Figure 1.24 , 3C{!H}NMR Spectra of the Aliphatic Region of CnRhMe(BF4 ) 2 (13% ,3C of RhMe) in Reaction with 1 3CH2= 13CH2 (5 atm) in CD 3N 0 2. 55 rhodium in the reaction system is in the form of the ethylrhodium complex B waiting to go through the rate-determining insertion step, but at ethylene pressures near 1 atm, B dissociates extensively, rapidly, and reversibly to ethylene and the ethylrhodium(III) complex C . 3 0 The Ea for the step of ethylene insertion into the Rh-C2H 5 bond was measured to be 17.2 kcal at 30 °C. The absence of higher olefins in the ethylene dimerization product is due to the fact that chain termination is much faster than the subsequent insertion. Brookhart9 > 2 4 ( d )>2 6 has reported catalytic dimerization of ethylene by C 5R 5 (L)Rh(Et)(C2 H4)+ (R = H, Me; L = PMe3 , P(OMe)3 ). The mechanism of M -E t >. [M— Bu]+ P-H elim . limiting step fast fast H i!*- fast exchange + M- I H ▼ M - c H M I H A ; Butenes Figure 1.26 Dimerization of ethylene by C5R5(L)Rh(Et)(CyT4)+. 56 the reaction is shown in Figure 1.26. The rate-determining step is the ethylene insertion into the Rh-C2H 5 bond. The AG* at 23 °C of the insertion reaction of Cp*P(OMe)3Rh(Et)(C2 H4)+ was found to be 22.4 kcal/mol. The CnRhMeX2 (X = BF4-, OTf") complexes offer the only example of coordination polymerization of ethylene by rhodium catalysts. Clearly the change of propagation vs transfer rates for rhodium in this novel coordination environment is striking. Propylene was found to react with CnRhMeX2 (X = BF4-, OTf-) complexes. The !H NMR spectra show that the Rh-CH3 absorption peaks of CnRhMeX2 (X = BF4", OTf-) disappear during the reaction. As indicated by ]H NMR, no polypropylene or even long propylene oligomers were formed since none of the absorption peaks of the products are many times more intense than the absorption peaks of the Cn ligand on rhodium after 5 days at room temperature. Also, their is no precipitate formed. The inability of this system to polymerize propylene may due to two reasons. The bigger steric effect of propylene compared to ethylene slows down the insertion reaction; also P-H elimination is fast and significant, especially when the insertion reaction is slow. Anion and Ligand There are two factors that need to be improved in this CnRh ethylene polymerization system. The fust one is that the CnRhMeX2 (X = BF4", OTf-) complexes do not dissolve in weakly coordinating solvents, i.e. hexanes, benzene, toluene and CH2 C12. Since coordinating solvents certainly slow down 57 the polymerization reaction, the catalysts need to be modified so that they can dissolve in weakly coordinating solvents. The second factor is that the BF4" and OTf" anions themselves are at the strongly coordinating end of the weakly coordinating ligand family. To make the catalysts more active, even more weakly coordinating ligands must be utilized. The aim of this part of our work is to make the catalysts as soluble as possible in weakly coordinating solvents and to make the catalytic sites as labile as possible. The important properties for weakly coordinating anions are low overall charge and a high degree of charge delocalization. 31 In recent years, the search for larger and more weakly coordinated anions has been one of the most important topics in coordination chemistry. The large and more weakly coordinating anions include BPh4" and its derivatives (e.g. [3,5-(CF3)2Ph]4B"), CBn H 1 2 " and related carborane anions, and OTeF5 " and its derivatives (e.g. Ti[OTeF5]5 "), etc. 31 Many of these anions are found to be less coordinating than BF4", PF6", C104" and SbF6". There are several major ways of introducing these anions: through protonolysis of metal-alkyl bonds, R" abstraction by Lewis acids, halide abstraction with Ag(I) and T1(I) salts, H" abstraction by CPh3 + cation, and the oxidation of metal-alkyl bonds by Ag(I) or Fe(Cp)2+ ions. 31 Reaction of CnRhMe2Cl with AgBPh4 or AgPF6 does not give the expected product CnRhMe2BPh4 or CnRhMe2 BF4. Acids with high or moderate acidity (e. g. HOTf, HBF4, HC1, CF3COOH, C6 F5OH) can effect acid cleavage of the methyls of CnRhMe3 , 1, but weak acids (e.g. CH3COOH) cannot. This may imply that the methyls on 1 are not very basic (compared with, say, Cp2MMe2, M = Ti, Zr). It might also 58 be true that the Lewis basicity of the methyls on 1 is low, in which case methyl abstraction by a Lewis acid (i.e. B(C6 F5 ) 3 ) 3 2 to generate a weakly coordinating site might not work for complex 1 . The [3,5-(CF3)2Ph]4 B“, BAr4“ anion is believed to be one of the least coordinating anions. 3 1 -3 4 Brookhart's group3 4 has been able to obtain the dietherate of its acid, HBAr4 (Et2 0 )2, the preparation of which is shown in Figure 1.27. They found that this anion is very weakly coordinating and it tends to impart substantial organic solubility to its salt. 3 4 -3 5 Since acid cleavage of 1 by strong acids works well, the HBAr4 .(Et2 0 ) 2 acid was selected to react with 1. Treating 1 with 1 eq of the acid in CH2 C1 2 followed by stripping of solvent under vacuum resulted in the quantitative formation of CnRhMe2BR4, R = R— Br Mg » R— MgBr NaBp4». NaBR4 • xHzO NaBR4 e th e r/+ - HC1 - NaCl HBR4 (Et2 0 ) 2 CnRhMe3 1 eqHBR 4 (Et20 ) 2 / 1 \ 2 eq HBR4(Et2 0 ) 2 CnRhMe2BR4 [CnRhMe(Et2 0 )2](BR4 ) 2 22 23 Figure 1.27 Preparation of H B R /E ^O ^ and its acid cleavage reactions. 59 22, with no ether coordination with the complex as indicated by 1 HNMR in DMSCWtf. The 1 HNMR spectrum of 22 is the same as the spectra of complex 2 j and 4 since all of them are solvated. Complex 22 demonstrates modest t i ■ solubility in C6 F6 in which CnRhMe2 OTf, 2, does not dissolve. Reaction between 22 and C2H4 gives more soluble [CnRh(r] 3-allyl)(H)]+BR4’ which is stable for at least an hour in C6F6 without significant change at room temperature. About 36 h later upon standing in C6F6, most of the allyl hydride complex is gone. Reacting 1 with 2 eq of the acid in CH2 C1 2 followed by i ; stripping of the solvent under vacuum overnight resulted in the quantitative formation of ether coordinated [CnRhMe(Et2 0 ) 2 ](BR4)2, 23, as indicated by ]HNMR in DMSO-d6. Clearly the BR4- anions in C n R h M e ^ R ^ are so i [ j ; weakly coordinating that ether molecules replace BR4" anions to give ether \ j ! coordinated 23 which holds the ether strongly even under vacuum. Note that j complex 22 cannot hold ether under vacuum while 23 can, indicating that the j ! | dication is much more electrophilic than 2 2 . j Complex 23 dissolves in CH2C12 or ether very well due to the presence j ! i of the large anions. 3 5 Thus, while we have solved the solubility problem j reasonably well, we now found that the ethers were tenaciously coordinated to j : J ; ; j the rhodium, making the ethylene polymerization catalyzed by 23 not too I different in rate from that catalyzed by 5. : i j l j Prolonged standing of a solution of 23 in CH2 C1 2 resulted in formation of ! the dichloride-bridged dimeric compound [CnRhMeCl]2 (BAr4)2, 24. Slow | I evaporation of the CH2 C1 2 solution of 24 under N 2 led to isolation of single i i - | i crystals of 24. X-ray single crystal analysis of 24 confirmed its dimeric i 60 : structure (Figure 1.28), although the R factor to date is only ca. 12%. As 22 does not dissolve in benzene at all, it has been difficult to find a weakly coordinating solvent for 22. Chlorobenzene sometimes is used to substitute for CH 2 C1 2 as a solvent to avoid chloride abstraction, since the C-Cl bond in chlorobenzene is stronger than that of CH2 C12. However, chlorobenzene was found to slowly react with CnRhM e^R,,, 2 2 , to give as yet unidentified bright yellow precipitates. Therefore chlorobenzene is unlikely to be a good solvent for 23 since 23 is much more electrophilic than 22. The testing of other weakly coordinating solvents (e.g. o-difluorobenzene) for this system is currently in progress. Large BR4" anions impart substantial organic solubility to the CnRh complexes, but this is not the only way to solve the solubility problem of these catalysts in weakly coordinating organic solvents. Another way to enhance the solubility of CnRh complexes is to replace the methyl groups on the Cn ligand by larger R groups to make larger new "RCn" ligands. The larger RCn- coordinated rhodium complexes will be more organic than their CnRh analogs and will presumably have better solubility in weakly coordinating organic solvents. Our efforts at making larger new Cn ligands have been very successful. As shown in Figure 1.29, the l,4,7-trineopentyl-l,4,7-triazacyclononane (NpCn), 1,4,7-tribenzyl-1,4,7-triazacyclononane (BzCn), and 1,4,7-trineohexyl- 1,4,7-triazacyclononane (NhCn) ligands have been synthesized with yields of 53%, 91% and 95%, respectively. At room temperature, BzCn and NhCn are colorless, thick liquids. The NpCn, on the other hand, is initially also a 61 Figure 1.28 ORTEP drawing of the molecular structure of the cation part of 24 j l (structure solved by Roy S. Lu and Robert Bau). The carbon atoms on the | ligands and the anions are not shown. i j ; J ! i I ! i 62 1 I I colorless, thick liquid but at room temperature or lower, it slowly forms white crystals. BzCn and NhCn readily coordinate with RhCl3 in ethanol to generate BzCnRhCl3 (71%) and NhCnRhCl3 (42%), respectly; but NpCn does not (Figure 1.30). Probably the NpCn is too crowded for coordination with rhodium to be possible. Methylation of BzCnRhCl3 , 25, by MgMe2 leads to the formation of BzCnRhMe3, 26, in 57% yield. It was found that use of methyl lithium as the alkylation reagent for BzCnRhCl3 results in the activation of phenyl rings on the ligand. Surprisingly, the solubility of 26 in benzene is not even as good as CnRhMe3, 1! This may be caused by the high lattice energy resulted from ordered packing of the molecule in the crystal lattice because of the presence of the phenyl rings. NhCnRhCl3, 27, readily methylates with MeLi to give NhCnRhMe3 , 28, in 54% yield. Indeed, 28 is substantially more soluble in non-polar solvents than CnRhMe3, 1. Complex 28 dissolves in toluene (>10mg/mL at 25 °C) while complex 1 does not. The !HNMR spectrum of 28 is shown in Figure 1.31. Complexes 26 and 28 are both air stable, like complex 1. Slow evaporation of the benzene solution of 28 in air lead to the isolation of light yellow single crystals. The X-ray diffraction data of 1 show the expected facial NhCn coordination with average Rh-N and Rh-C bond lengths of 2.24 and 2.05 A, respectively (Figure 1.32). The bond angles (NRhN, 80°; CRhC, 8 6 °) clearly indicate that the NhCn ligand is slightly slipped up along the C3 axis in the same way as the Cn ligand in 1 (Figure 1.2). The structures of 28 and 1 are extremely similar as indicated by their bond lengths and bond angles (Table 1.5). Strong similarity of their chemistry should be expected. As the solubility 63 HN W w H H N ^ N H HBr + CHO + NaBH3CN C H ,O H ^ V * 3 A sieves V'N— ' NpCn W H B r + H c h 3 o h ' ^ ' n^ n' ^ C ^ c h o + N a B H ^ i & r r N hC n HN ^NH ^ y • 3 HBr + NaOH + H PhCH2- N / \ NX H 2Ph c h 2 c i pH > u » V - n- ^ Et0H/H20 I CH 2Ph BzCn Figure 1.29 synthesis of the new RCn complexes. of 28 is substantially better than that of 1 in weakly coordinated solvents like toluene, we are on the right track toward making more soluble catalysts. Combination of the large RCn ligand on rhodium with large BR4“ anions to make more active and more soluble catalysts is in progress. Conclusions A series of Cn coordinated organorhodium complexes has been synthesized and characterized. X-ray diffraction data of CnRhMe3 , 1, show the | i expected facial coordination of Cn and the C 3 symmetry of this molecule. The 64 x ^ tl Vkx. w y . NpCN R h C I3 > ( ▼ NpCnRhCl3 phcH 2 ^ N / \ N-C H 2Ph C H 2Ph BzCn R h C I 3 BzCnRhCl3 25 M gM e2 ▼ BzCn R h CH3 CH3CH3 26 NhC n R h C I 3 N hC nR hC I3 27 M eL i v N hC n / T V CH3 k CH3 28 Figure 1.30 Synthesis o f the rhodium complexes with new "Cn" ligands. Tablel.5 Selected bond lengths and bond angles of CnRhMe3 and NhCnRhMe3 CnRhMe3 Rh-C bond (pm) 210 Rh-N bond (pm) 223 C-Rh-C angle (degree) 87 N-Rh-N angle (degree) 80 NhCnRhMe3 205 224 86 80 65 !H NMR chemical shift of the methyl(s) on rhodium in CnRhMe3.nXn (n = 0 , 1 , 2 ) complexes has very good correlation with the degree of substitution (n) of i ' I j : electron withdrawing substituents on CnRh complexes. More electron ! withdrawing groups on rhodium cause down field shifts of the Rh(CH3 )3 .n | peak in the NMR spectrum. The 1 0 3Rh-1 3 C coupling constant, J ^ , of : CnRh3.nXn (n = 0, 1,2) also has good correlation with the degree of substitution ; i i (n) of electron withdrawing substituents on CnRh complexes as indicated by j j | l3 C{1H}NMR. The reason for this correlation might be that the rhodium carbon j I ; coupling constants reflect the electron richness of the rhodium center as j i j : ! indicated by XPS (Chapter 3). More electron withdrawing groups on rhodium f ; i i i ; ! ; ! ; result in smaller 1 0 3Rh-1 3 C coupling constants of CnRh(CH3)3.nXn complexes. | ; ; The CnRhMe3.nXn (n = 0, 1, 2) complexes have well behaved solvation ; j ! : 3 ! properties, particularly when X = OTf" and BF4 -. The coordinating ability of ; ; the anions for this CnRh system follows the trend o f : BF4" < OTf" « B r < ! | s • I j : Cl“. The coordinating ability of the solvents is ranked as follows: CH2 C1 2 << I : • i j : MeOH < DMSO < H2 0 . ! Complexes 2 , 3, 4 and 5 have well-defined chemistry in organic solvents. h i Complex 2 reacts with CO to form [CnRhMe2 (CO)]+OTf', 15, which does not undergo CO insertion into the Rh-CH3 bond even at 80 °C while the phosphine i f . ^ analogs5 - 21 of 2 insert CO and eventually give acetone and Rh1 complexes. In the reaction with ethylene, complex 2 first coordinates ethylene at low temperature to form [CnRhMe2 (C2H4)]+OTf', 16, which can be observed by ! both 3 H NMR and 1 3 C NMR. Raising the temperature results in ethylene * i insertion into the Rh-CH3 bond, followed by reversible |3-H elimination, 66 . K . __ v-*-'' — i— i— i— 1 — r— 1 — i— 1 — — 1 — i— 1~ i > i i ' i 1 i r ! 1 i 1 r 3.2 3.0 2.8 2. G 2.4 2.2 2.0 1.8 1.6 1.4 1.2 1.0 .8 .6 .4 PPM. a s •vj Figure 1.31 ]HNMR spectrum of 28. | Figure 1.32 ORTEP drawing of the molecular structure of 28 (structure solved i by Dr. Charles Campana, Roy Lu and Dr. Robert Bau). 68 then loss of methane, and, finally, activation of the allylic C-H bond to form allyl hydride 2 0 . At higher temperature, 2 0 is chlorinated by CH2 C1 2 solvent to allyl chloride 21, which structure was confirmed by X-ray crystallography. The 16 -» 2 0 transformation is a rare example of the direct observation of the insertion of an alkene into the metal-carbon bond in a well-defined M(R)(alkene) complex. 2 4 The kinetic parameters for the ethylene insertion step are consistent with the fact that it is an intramolecular insertion reaction. A deuterium labeling experiment revealed that the transformations between 17 and 18, 19 and 20 are reversible. The 2 — » 2 1 transformation is very temperature dependent. This reaction is again in strong contrast to that of its phosphine analogs5 * 21, which form Rh1 species without ethylene insertion into the Rh-CH 3 bond. Complexes 3 and 5 were found to be ethylene polymerization catalyst in organic solvents. The GPC analysis = 2-2.3) revealed that this system is not a living polymerization system. Infrared spectra of the polyethylene generated in this system show no detectable branching , indicating that this system is a typical coordination polymerization system. At high ethylene pressure (> 5 atm), chain transfer (|3-H elimination) is not significant. At low ethylene pressure (< 1 atm), the transfer/propagation ratio increases. Only the dimerization of ethylene by rhodium complexes has been reported previously. 9 ’2 4 ^ ) * 2 6 ’3 0 The change in propagation vs transfer rates for rhodium in this novel coordination environment is striking. To enhance the solubility of the ethylene polymerization catalysts in weakly coordinating organic solvents and also to make the coordinated anions 69 more labile, HBR4 (Et2 0 ) 2 (R = 3,5-(CF3)2Ph) acid has been prepared. The acid cleavage reaction of 1 was successful by using 2 eq of the acid but [CnRhMe(Et2 0 )2 ](BR4 )2, 23, was generated instead of C n R h M ^B R ^ due to the tenacious coordination of ether. Prolonged standing of 23 in CH2 C1 2 resulted in chlorine abstraction from the solvent to form the dimer [CnRh(p- Cl)2RhCn](BR4 )2, 24. BzCn, NhCn and NpCn have also been made to enhance the solubility of the new RCn coordinated complexes in weakly coordinating solvents. The complex NhCnRhMe3, 28, demonstrates better solubility than CnRhMe3, 1, in weakly coordinating solvents such as toluene. Experiments of combining 28 and the acid cleavage by the bulky etherate of HBR4 to generate more soluble and more active polymerization catalysts are currently in progress. So far, in organic solvents, the hard-ligated CnRh system has been demonstrating different chemistry from its known phosphine and Cp soft-ligated analogs. EXPERIM EN TAL General Chemical shifts of NMR spectra, recorded on 360-, 250- or 500 MHz FT spectrometers, are reported in parts per million (5) down field from tetramethylsilane for 'H and 1 3 C and from 85% H 3P 0 4 for 31P spectra; all coupling constants are apparent, not calculated, with absolute values reported in Hertz. 70 I : All reactions involving organometallic compounds, unless otherwise | j ! mentioned, were carried out under an atmosphere of dinitrogen or argon purified over reduced copper catalyst (BASF R3-11) and Aquasorb and in flamed-out glassware using standard vacuum line, Schlenk and dinitrogen atmosphere box techniques. The glove box was a Vacuum Atmospheres model HE-553-2 equipped with a DriTrain MO 40-2 inert gas purifier. The oxygen I content of the dry box was monitored by Cr(acac)2, a light orange color indicating that it was sufficiently air free for use. Benzene, ether, hexanes, pentanes and THF were distilled from purple solutions of sodium/benzophenone. CH2 C1 2 was distilled twice from CaH2. Transfers of ethylene, CO and other gases were performed on a vacuum | line. 3 6 Elemental analyses were performed by Galbraith Laboratories, i Knoxville, Tennesee. Ligand Preparation l,4,7-Trim ethyl-l,4,7-triazacyc!ononane (Cn). The literature preparation for the tritosylate of 1,4,7-triazacyclononane works well and was used as given1 5 . Preparation of the hydrogen bromide salt of 1,4,7-triazacyclononane, j ! tacn(H Br ) 3 A solution of 96 g. (0.16 mol) of tacn tritosylate (recrystallized S ' ! from CHCl3/EtOH) in 98% H2 S 0 4 (260 mL) was stirred at 100 °C for 3 days. I i To the room temperature solution was added 800 mL of ethanol, and then 2 ■ i liters of ether, all with stirring, resulting in formation of a light gray precipitate. | The suspension was cooled for a while in an ice bath with continued stirring, j * I then the solid was collected by suction filtration on a fritted funnel. The tacky | ! ! 7 i ! hygroscopic material was quickly transferred into a 400-mL beaker, and was dissolved in a minimum amount of water with stirring on a hot plate. Then 275 mL of 48% aqueous HBr (conc. HBr) was added, resulting in immediate precipitation of a dense, off-white solid. This mixture was cooled in an ice bath, and the solid was collected on a fritted filter. The solid was washed with conc. HBr, then twice with ether, and then air dried in the dark: 55.7g., 92% yield. Preparation of the Cn Ligand: First 24 lg. of tacn(HBr) 3 was dissolved in 190 mL of water in a 2-liter RB flask. The pH of this solution was adjusted to ca. 8 with saturated aqueous NaOH. (Universal pH indicator paper was used for approximate pH determinations.) Then 380 mL of an 8 8 % HCOOH solution was added, followed by 310 mL of 38% HCHO. The saturated NaOH was used to further adjust the pH to a value between 1 and 2. At this point, the slow evolution of C 0 2 bubbles commenced and NaOH addition was stopped. The solution was heated at reflux for 24 hr. The pH of the room temperature solution was adjusted using the saturated NaOH solution to a value of 12 or more, and this was extracted with 5x1200 mL portions of pentane. Evaporation of pentane and reduced pressure distillation of the residue led to collection of 96.0 g (87% yield) of colorless liquid (56-58 <€ / 3mm). !HNMR (C6D6): 8 2.28 (s, 9H NCH3 ), 5 2.66 (s, 12H N CH2). i3C{iH}NMR (C6D6): 5 46.8 (NCH3 ), 8 57.7 (NCH2). 1,4,7-Tribenzyl 1,4,7-triazacyclononane (BzCn): First 10.0 g (0.0268 mol) of tacn(HBr) 3 salt was dissolved in 14mL of water which contained 2.15 g (0.0538 72 I mol) NaOH in a 125 mL Erlenmeyer flask. Then 56 mL ethanol was added to it followed by 9.28 mL (0.0806 mol) benzyl chloride. Under stirring, NaOH solid I was added piece by piece until the pH of the solution is 11 or slightly higher | (indicated by Universal pH paper). This solution was allowed to stir for 4 h and ! then to settle. The three phases of clear solution, oil, and white salts can be ‘ clearly seen. The oil was separated out and the remaining salts and clear | solution were extracted by 3x20 mL hexanes. The combined oil hexanes solution was washed with 3x40 mLof water. Evaporation of the solvent at low j temperature gave 9.77 g (91%) colorless oil which was pure enough for general | purpose. The oil does not boil even at 200 °C/lpmHg. 1 HNMR (CD3COCD3 ): 5 2.78 (s, 12H, NCiT2 C //2N), 5 3.59 (s, 6 H, PhCiT2), 5 7.12-7.40 (m, 15H, j Q/Zs-). | | l,4,7-Trineohexyl-l,4,7-triazacyclononane (NhCn): 1.24 g ( 3.33 mmol) i tacn(HBr) 3 was added to a 50-mL schlenk flask which contained 12 mL dry s methanol, 0.267 g (6.67 mmol) NaOH and 3 A molecular seives. This was i s 1 I j stirred for 2 0 min and allowed to stand for 8 h to have the water generated from | | the reaction to be fully absorbed by molecular seives. This solution was then ' cannulated to another schlenk flask which contained 2.5 mL (2.0 g, 0.020 mol) i 3,3-dimethylbutyraldehyde, 8 mL of dry CH3OH and 3 A molecular sieves, ! | i j followed by 2x5 mL dry methanol wash. Then 14 mL of 1 M N aBH 3CN THF j ; | solution was added to the reaction mixture. This mixture was allowed to stir for [ I j 5 days. In air, the molecular sieves were filtered out and washed with 3x7 mL 5 | ; | of methanol. Conc. HC1 aqueous solution was added to bring the pH to be ca. ! i I 2. The solvents were then evaporated. Then 50 mL of water was added to the | 73 | : ! residue. The pH of the solution was adjusted by NaOH to ca. 12. The aqueous solution was extracted with 3x50 mL pentanes. Evaporation of pentanes under reduced pressure gave 1.20g (94.5%) colorless viscous liquid which is pure enough for general purposes. 1 HNMR (C6 D5 ): 8 0.91 (s, 27H, C(CH 3 )3 ), 1.49 (m, 6 H, RCiT2CH2N), 2.58 (m, 6 H, N C//2CH2 R), 2.84 (s, 6 H, N C //2 Ctf2N). 1 3C{1H}NMR (C6 D6 ): 8 29.77 (s, C(CH3 )3), 42.04 (s, CH2 C(CH3 )3 ), 55.25 (s, NCH 2 CH2 CR3 ), 56.85 (s, NCH2 CH2N). l,4,7-TrineopentyI-l,4,7-triazacyclononane (NpCn): This reaction is much slower than the last one, presumably due to the steric effect. First 2.50 g (6.72 mmol) tacn(HBr) 3 was added to a 50-mL schlenk flask which contained 15 mL dry methanol, 0.54 g (13.5 mmol) NaOH and 3A molecular seives. This mixture was then stirred for 2 0 min and allowed to stand for 8 h to have the water generated from the reaction to be fully absorbed by molecular seives. This solution was then cannulated to another schlenk flask which contained 2.92 mL (2.32 g, 0.0269 mol) pivaldehyde, 38 mL of dry CH3 OH and 3A molecular sieves, followed by 2x5 mL dry methanol wash. Then 14 mL of 1 M NaBH3 CN THF solution was added to the reaction mixture. This mixture was allowed to stir for 3 days. In air, the molecular sieves were filtered out and washed with 3x7 mL of methanol. Conc. HC1 aqueous solution was added to bring the pH to be ca. 2. The solvents were then evaporated. To the residue, 50 mL of water was added. The pH of the solution was adjusted by NaOH to ca. 12. The aqueous solution was extracted with 3x50 mL pentanes. Evaporation of pentanes under reduced pressure gave a colorless oil which was a mixture of mono- and di-alkylated species. Apparently the reaction was not done yet. The 74 oil was mixed with 30 mLof dry methanol, 5.84 mL of pivaldehyde, 3A molecular sieves and 28 mL of 1 M NaBH3 CN THF solution. This was allowed to stir at RT for 5 days. The workup was the same as before. A mixture of 85% NpCn and 15% di-alkylated products were obtained. This mixture was again treated with 50 mL dry methanol, 4.38 mL of pivaldehyde, 3A molecular sieves and 14 mL of 1 M N aB H 3CN THF solution and stired at RT for another 5 days. Workup of this reaction gave 1.20 g (53%) white crystals which were pure NpCn. 1 HNMR (C6D6): 5 0.96 (s, 27H, C(C/f3 )3 ), 2.25 (6 H, C/f2 CR3 ), 2.93 (12H, N C //2 Cf/2N). 1 3C{!H}NMR (C6D6): 8 28.25 (s, C(CH3 )3 ), 29.18 (s, C(CH3 )3 ), 59.89 (s, NCH 2 CH2N), 73.46 (NCH2 CR3 ). Recovery of RCn (Cn, BzCn, NhCn) Ligands: As excess of Cn ligands are typically used in the synthesis of RCnRhCl3, recovery of the RCn ligands turns out to be important and necessary. There are two ways to recover the RCn ligands. One way is to wash the RCn (Cn, BzCn, NhCn) residue with conc. NaOH water solution and extract the aqueous solution of RCn three times with pentanes. Evaporation of pentane often gives pure RCn. In the case of Cn, further distillation of the ligand can be applied under reduced pressure if necessary. If one does not like to deal with the aqueous solution, then excess of CH3 Li ether solution can be used as the base to effect the recovery of the RCn ligands. The reason that base is necessary for the recovery of RCn is that these ligands can be slowly protonated by ethanol. In the case of BzCn, [BzCnH]+ can be observed by 1HNMR. 75 Rhodium Compounds CnRhCl3 (The synthesis of this compound has been reported by Wieghardt6- 8.) To a dark red solution of 1.0 g RhCl3 .3H20 in 20 mL of ethanol was added with stirring 15 mL of the ethanolic solution of Cn ligand (0.57 M ) at room temperature. The resulting bright yellow mixture was then refluxed for 2 hr. Yellow precipitates were collected by filtration at room temperature, washed with 3xl0mL of ethanol, then 3xl0mL of ether and air dried. Yield: 1.3 g (90%). 1 HNMR ( C D 3 S O C D 3 ) 8 2.85 (s, 9H NC/73 ), 8 2.92-3.22 (m, 12H NCH2). Anal. Calcd for C9H2 1N 3Cl3Rh: C, 28.41; H, 5.56; N, 11.04. Found: C, 28.75; H, 5.88; N, 10.70. CnRhM e3 To a stirring suspension of 0.75 g CnRhCl3 in 22 mL of THF, 6.2 mL (1.6 M) halide free CH3Li1 6 was added at room temperature. It was found that this methylation reaction is very sensitive to halide concentration. High halide contents in CH3Li often delay and hinder the completion of methylation. The halide concentration of the CH3 Li ether solution purchased from Alderich varies from time to time althrough it is labeled low halide concentration. Therefore, most CH3 Li used in this research was synthesized from CH 3C1 gas and lithium metal. This is so-called "halide free" CH3Li.1 6 . This mixture was allowed to stir at RT for 2 days during which time the color of the solution became completely dark. CH2 C1 2 or wet THF was slowly added until gas evolution ceased. Volatiles were evaporated at reduced pressure and the residue was extracted with 60 mL of CH2 C1 2 by stirring at RT for 20 min. The insoluble solids were filtered out and the solvent was evaporated at reduced pressure. The yellow solids were extracted by 50 mL of refluxing benzene for 76 | 30mins. The room temperature solution was filtered and the solvent was i | evaporated at reduced pressure; 0.535g (85% yield) light yellow product was j j i obtained. The product is air stable. 'HNMR (C6D6): 5 0.27 (d, JRhH = 2.5 Hz, | Rh(CH 3 )3), 2.26 (s, 3[NC//3 ] ), 1.58-2.07 (m, N C //2); 1 3C{!H}NMR (C6D6): 8 - 0.30 (d, Jm iC = 36.2Hz, Rh(CH3)3 ), 48.24 (NCH3 ), 56.94 (NCH2). Anal. Calcd for C 1 2H 3 0N 3Rh: C, 45.14; H, 9.47. Found: C, 45.06; H, 9.01. I CnRhM e2O Tf To a solution of 0.50 g (1.57 mmol) CnRhMe3 in 20 mL of | \ CH2 C1 2 at -78°C, 2.10 ml of 0.709 //triflic acid ether solution was slowly 5 added. Then 5 mins after stirring at -78 °C, the solution was allowed to slowly i j warm to room temperature and was stirred at this temperature for 1 hr. j | Volatiles was evaporated under vacuum and the resulting solid was washed with ' j j j 2x20 mL of benzene to clean out the remaining CnRhMe3. The solid was dried j i under vacuum; 0.62 g (92%) yellow product was obtained. 1 HNMR j (CD3 SOCD3 ): 8 0.22 (d, J r ^ = 2.3Hz, Rh(CH 3 )2), 8 2.48, 2.78 (s, NCJ73 ), 8 2.55-3.25 (NCH2); 1 3C{'H}NMR (CD 3SOCD3 ): 8 4.16 (d, J r ^ = 26.6Hz, I I Rh(CH3 )2), 8 49.26, 50.53, 56.58, 57.98, 60.12 (s, NCH3, NCH2). Anal. Calcd for C 1 2H2 7N 30 3F 3SRh: C, 31.97; H, 6.00j Found: C, 32.09; H, 5.91. J j CnRhM e(OTf) 2 To a solution of 0 . 2 0 g (0.626 mmol) CnRhMe3 in 15 mL of i j CH2 C12 at -78 °C, 1.35 mL of 0.898 N (1.22 mmol) triflic acid ether solution j j I was slowly added. About 5 mins after stirring at -78 °C, the solution was i j j allowed to slowly warm to room temperature and was stirred at this temperature | for 1 hr during which time white solids precipitated from the solution. The | j j | : flask was allowed to stand in an ice bath for 15 min and the supernatant was j i removed by cannula. The solids were washed with lOmL of CH2 C1 2 at 0°C. : j i I 77 ■ S Again the supernatant was removed by cannula. The resulting solid was dried under vacuum; 0.33 g (92%) of milky white product was obtained. 1 HNMR (CD 3 SOCD3): 8 1.58 (d, Jrijh = 2.1Hz, RhCH 3 ), 8 2.38, 2.80 (s, NCH3\ 2.67- 3.20 (m ,N CH2y, ^C ^H JN M R (CD 3SOCD3 ): 5 8.45 (d, J ^ c = 26.5 Hz, RhCH3 ), 8 46.47, 51.28, 54.12, 60.85, 62.62 (s, NCH3 , NCH2). Anal. Calcd for C 1 2H2 4N 3 0 6 F6 S2Rh: C, 24.54; H, 4.12; N, 7.15. Found: C, 24.17; H, 4.13; N, 6.95. CnRhM e 2BF 4 and CnRhM e(BF 4 ) 2 The syntheses of these two complexes are the same as preparing CnRhMe2OTf and CnRhMe(OTf) 2 except that 85% HBF4 •Et20 was directly added to the reaction system since it does not dissolve in ether well. The NMR spectra of these complexes are the same as their triflic analogs in DMSO-d^ due to solvation. The products prepared here are good enough for general purposes although they failed elemental analysis. Caulton5 reported that for the synthesis of (triphos)RhMe2BF4, direct addition of HBF4 acid to the slurry of (triphos)RhMe3 in CH2C1 2 produces a less pure product and addition of the acid as a CH2 C1 2 solution is important to give pure product. Further attempts to make pure CnRhMe2 BF4 and CnRhMe(BF4 ) 2 were not carried out since the preparations of their pine triflic analogs work very well. CnRhM e2Cl To a solution of 0.20 g (0.626 mmol) CnRhMe3 in 15 mL of CH2 C1 2 at -78 °C, 1.04 mL 0.574 N (0.597 mmol) HC1 ether solution was slowly added. Then 5 min after stirring at -78 °C, the solution was allowed to slowly warm to room temperature and was stirred at this temperature for 1 hr. Volatiles were evaporated under vacuum and the resulting solids were washed with 15 mL of benzene to clean out the remaining CnRhMe3. The 78 I resulting solids were dried under vacuum; 0 .193g (95%) light yellow product * j was obtained. 1 HNMR (CD3SOCD3 ): 6 0.32 (d, J r ^ = 2.4Hz, j Rh(C//3 )2), 8 2.24 (d, J r ^ = 1.7Hz, N C //3 ); 5 2.61 (s, 2NCH3 ), 8 2.50-2.97 (m, N CH2). ^C ^H JN M R (CD3SOCD3): 8 -0.84 (d, J r ^ = 29.5Hz, Rh(CH3 )2), 8 48.01, 50.16, 55.25, 56.94, 61.23 (s, NCH3, NCH2). Anal. Calcd for Cn H2 7N 3ClRh: C, 38.89; H, 8.01. Found: C, 38.68; H, 7.93. CnRhM eCl2 To a solution of 0 . 2 0 g (0.626 mmol) CnRhMe3 in 15 mL of CH2C1 2 at -78°C, 2.15 mL 0.574 N (1.23 mmol) HC1 ether solution was slowly added. Then 5 mins after stirring at -78°C, the solution was allowed to slowly warm to room temperature and was stirred at this temperature for 1 hr. The yellow precipitates were filtered out and washed with 3x8 mL of pentane and air dried; 0.208g (94%) yellow product was obtained. 1 HNMR (CD3 SOCD3 ): 8 1.54 (d, Jrjjh - 2.6Hz, RhCH 2 ), 8 2.49, 2.96 (s, NCH 3 ), 8 2.60-3.11 (m, NCH2). 1 3C{'H}NMR (CD3 SOCD3 ): 8 2.92 (d, J r ^ = 24.4Hz, RhCH3 ), 8 48.21, 50.78, 55.19, 60.39, 61.85 (s, NCH3, NCH2). Anal. Calcd for Ci0 H2 4N 3Cl2 Rh: C, 33.35; H, 6.72. Found: C, 33.91; H, 6.76. CnRhM e2Br To a mixture of 0.150 g (0.331 mmol) CnRhMe2OTf and 0.107 g (0.331 mmol) (n-Butyl)4NBr, 15 mL of THF was added at RT. This was ' allowed to stir at RT for 3 days. Upon filtration, THF was stripped off and the [ j | resulting orange solids were transferred to a fritted glass filter, quickly washed ! with 5x4 mL of water, then 2x2 mL of ether and vacuum dry. Yellow product ; was obtained. Yield: 65 mg (51%). ]HNMR (CD3 SOCD3 ): 8 0.39 (d, J r ^ = 2.3Hz, Rh(Ctf3 )2), 8 2.22, 2.69 (s, N C/f3 ), 8 2.42-3.15 (m, NCJ72). j j j ! ^C ^H jN M R (CD 3SOCD3 ): 8 -2.1 (d, J r ^ = 28.6Hz, Rh(CH3 )2), 8 48.93, 79 49.73, 55.27, 57.20, 61.18 (s, NCH3, NCH2). Anal. Calcd for Cn H2 7 N3 BrRh: C, 34.39; H, 7.08. Found: C, 34.02; H,6.80. CnRhM eBr2 To a mixture of 0.150 g (0.255 mmol) CnRhMe(OTf)2 and 0.165 g (0.511 mmol) (n-Butyl)4 NBr, 15 mL of THF was added at RT. This mixture was allowed to stir at RT for 3 days. The orange precipitates were filtered , washed with 3x3mL of THF, then 3x3mL of ether and air dry; 75 mg (65%) of orange product was obtained. 1 HNMR (CD3SOCD3 ): 8 1.67 (d, J r ^ = 2.5Hz, RhCH3 ), 8 2.59 (d, 3 ^ = 0.75Hz, 2NCtf3 ), 8 3.09 (s, N C //3 ), 8 2.61-3.20 (m, N C //2). i3CNMR{iH} (CD3SOCD3 ): 8 0.37 (d, = 23.0Hz, RhCH3 ), 8 49.73 (s, NCH3 ), 8 51.64 (s, 2NCH3 ), 8 55.53, 60.25, 62.12 (s, NCH2). Anal. Calcd for C1 0 H2 4 N3 Br2Rh: C, 26.75; H, 5.39; N, 9.36. Found: C, 27.13; H, 5.49; N, 9.29. CnRhBr3 {Data from Chunming Wang)'. To the solution of 0.12 g (0.376 mmol) CnRhMe3 in 6 mL CH3 N 0 2 at -20 °C, triflic acid ether solution (0.2 mL CF3S 0 3 H in 2.5 mL ether) was added. After about 10 min, this solution was allowed to warm to room temperature and was stirred for 3 hr. Solvent was evaporated and the solids were washed with 3x5mL of ether. The resulting solids (presumably CnRh(OTf)3 ) were dissolved in 10 mL CH3 N 0 2, followed by addition of l.Og (n-butyl)4 NBr (3.10 mmol). This mixture was allowed to stir for 5 days under N2. About 20 mL of THF was added to the reaction mixture, this resulted in immediate precipitation of orange colored solids. The upper solution was cannulated out and the solids were washed with 3x5 mL of THF and dried under vacuum. Orange product was obtained. Yield: 0.15g (78%). Anal. Calcd for C9 H21N3Br3 Rh: C, 21.04; H, 4.12; N, 8.18. Found: C, 21.15; H, 4.11; N, 7.97. 80 [CnRhMe2(CO)]+OTf" {Data from Chunming Wang): CnRhMe2OTf (0.3 g, 0.662 mmol) was dissolved in 10 mL of CH2C12. After a freeze-pump-thaw cycle, excess CO gas was transfered into the system under liquid nitrogen temperature. The solution was allowed to warm to room temperature and was stirred for 2 hours. Solvent was evaporated and the resulting solid was dried under vacuum for 4 h. Light yellow product was obtained. The transformation is quantitative based on Rhodium. 1 HNMR (CD3SOCD3 ): 8 0.36 (d, J r ^ = 1.95Hz, Rh(CH3 )2), 8 2.54, 2.80 (s, NCH 3 ), 8 2.74-3.10 (m, NCH2). 1 3 C{]H}NMR (CD3SOCD3 ): 8 1.54 (d, = 22.9Hz, Rh(CH3 )2), 8 47.99, 51.57, 55.64, 59.15, 60.79 (s, NCH3 , NCH2), 8 187.9 (d, Jr^ = 70.1Hz, RhCO). Anal. Calcd for C1 3 H2 7 N 3 F30 4SRh: C, 32.44; H, 5.65. Found: C, 32.64; H, 5.78. [CnRhM e2(C2H 4 )]+OTf-, 16, [CnRh(ri3-aIIyI)(H)]+OTf-, 20 and [CnRh(Ti3- allyl)(Cl)]+OTf", 21. Complexes 16 and 20 were generated and observed in CD2C12 at low temperature and they were assigned by their NMR spectra. In the dry box, 7.5 mg (0.0165 mmol) CnRhMe2OTf, 2 was dissolved in 0.40 mL of CD2C12 in a NMR tube equipped with stopcock and vacuum joint that is capable of vacuum seal. This tube was then brought out of the box and freeze- pump-thaw three times to degas the solution. Ethylene (0.066 mmol) was then delivered to the NMR tube under liquid nitrogen temperature on the vacuum line with mercury bubbler as the pressure indicator. The flame sealed NMR tube was then removed from the liquid nitrogen and quickly placed in a dryice- acetone bath before a VT NMR experiment. For the VT NMR experiment, the -78 °C NMR tube was quickly placed in the NMR probe with the pre-set 81 temperature of -80 °C. At -80 °C, no reaction occurred. At -55 °C the ! concentration of 16 very slowly built up, but no ethylene insertion product could be observed. Raising the temperature to -40 to -15 °C resulted in the | formation of 20. The 2 16 — » 20 process could be clearly followed by and 1 3 C NMR. The building up of 16 and 20 was very clear and this made the NMR assignment of 16 and 20 possible. Raising the temperature above -10 I °C resulted in the formation of two rotational isomers of 21 in CD2C12. One of j j j ; the crystalized isomer's structure of 21 has been confirmed by its X-ray j diffraction data. »H NMR of 16 (CD2C12, -32°C): 8 0.28 (d, jRhH = 1.8 Hz, ! Rh(Ci/3 )2), 2.56 (s, 2[NC/73]), 2.64(d, Jr^ = 0.8 Hz, N C //3 ), 2.3-3.2 (m, | N C F2), 3.27 (d, JnRh = 1-5 Hz, CH2=CH2). UC^HJNM R of 16 (CD2C12, - | ; 32°C): 5 8.20 (d, JC R h - 22.5 Hz, Rh(CH3 )2), 49.50, 49.66, 57.55, 58.52, 60.32 | (NCH2 and NCH3 ), 78.94 (d, JC R h = 8.2 Hz, Rh[CH2=CH2]). *H NMR of 20 (CD2C12, -15°C): 8 -22.40 (d, J r ^ = 16.5 Hz, RhH), 2.17 (ddd, 2H, = 11.8 j Hz, 3 Jnc-RhH = 2Jhc-R!i = 2 Hz, anti terminal allyl), 2.54 (d, Jr^h = 1.0 Hz, j N C //3 ), 2.58 (br d, 2H, Jcis = 7.3 Hz, syn terminal allyl), 2.6-2.7 + 2.9-3.3 (m, S NC/f2), 3.37 (s, 2[NCH3]), 4.32 (tt, J = 11.8, 7.3 Hz, central allyl). S 1 3 C{1 H}NMR of 20 (CD2C12, -15°C): 8 36.40 (dd, Jcc = 43.4 Hz, Jr^ = 10.9 | Hz, terminal allyl), 58.08 (2[NCH3]), 50.58, 58.13, 59.89, 60.40 (NCH2 and NCH3), 104.09 (td, Jcc = 43.4 Hz, JC R h = 6.2 Hz, central allyl). Elemental analysis for 21~Calcd for C 1 3 H2 6 N 30 3 F3ClSRh: C, 31.24; H, 5.24. Found: C, ! 30.94; H, 5.35. NhCnRhM e3 NhCn ethanol solution (0.8 g (2.15 mmol) NhCn ligand in 7 mL j ; ethanol) was slowly added to a stirring solution of 0 .142g (0.538 mmol) 82 RhCl3.3H20 in 5 mL of ethanol in a 50 mL RB flask. Yellow solids came out I of solution upon adding of the ligand but they dissolved back in afterwards. | This mixture was allowed to stir under nitrogen at room temperature for 7 days. | Yellow precipitates were filtered out, washed with 3x5 mL ether, then 3x5 mL pentane and dried under vacuum. Yield: 0.135 g (42%). This yellow product i does not seem to dissolve in anything. Then 0.128 g of the yellow solids (presumably NhCnRhCl3 ) was treated with 5 eq of halide free CH3Li in 10 mL | of THF in a 50 mL schlenk flask for 3 days at room temperature. Wet THF was slowly added to the reaction mixture until gas bubbling was ceased. Solvents sere stripped off under reduced pressure and the residue was extracted by 30 j i j mL of benzene followed by filtration and subsequent 2x5 mL of benzene wash. !i | | Evaporation of benzene gave light yellow product which was slightly j j | l contaminated by small amount of free NhCn ligand. The product was then jj washed with 3x5 mL of pentane and dried under vacuum. Yield: 62 mg (54%). j The light yellow product is air stable. 'HNMR (C6D6): 8 0.39 (d, J = 2.5 | Hz, Rh(CH3 )3), 0.90 (s, C(CH3 )3 ), 1.19 (m, CH2C(CH3 )3 ), 1.91, 2.43 (m, NGH2Gtf2 N), 3.05 (m, N C //2CH2CR3 ). ^C ^H jN M R (Q A ): 8 0.78 (d, J r ^ 1 | = 36.5 Hz, Rh(CH3 )3 ), 29.5 (s, C(CH3 )3 ), 29.90 (s, C(CH3 )3 ), 35.44 (s, l ; j CH2C(CH3 )3 ), 52.23 (s, NCH2CH2 N), 53.50 (NCH2CH2CR3 ). Anal. Calcd for | C27H6 0 N 3 Rh: C, 61.22; H, 11.42; N, 7.93. Found: C, 61.62; H, 11.89; N, j 8 .01 . BzCnRhM e3 Under stirring, 20 mL of BzCn ethanol solution (4.56 g (11.4 mmol) in 16 mL of ethanol) was slowly added 1.0 g (3.80 mmol) of ! | | RhCl3.3H20 in 20 mL of ethanol in a 100-mL RB flask. Yellow precipitates ] 83 j :j _ j formed right away. Then 5 min after adding was finished the mixture was allowed to reflux for 1.5 h. The room temperature mixture was filtered, washed with 3x10 mL of ethanol and 3x10 mL of ether and dried under vacuum. Yellow solids were obtained. Yield: 1.64 g (71%). iHNMR(CD3SOCD3 ): 8 2.46, 3.59 (m, NCH2), 4.76 (s, C/f2Ph), 7.30-7.70 (m, C J{5). The trichloride product BzCnRhCl3 (0.175g, 0.287 mmol) was treated with 6 eq (1.72 mmol, 1.94 mL 0.89 M ether solution) of MgMe2 in 10 mL THF in a 50 mL Schlenk flask. The mixture was allowed to stir at room temperature for 4 days after which time wet THF was added to it until bubbling was ceased. Solvents were stripped off under reduced pressure. The residue was extracted with 40 mL refluxing benzene for 1 h. The room temperature solution was then filtered, followed by 5ml benzene wash. Evaporation of benzene gave 89 mg (57%) of light yellow colored product. 1 HNMR (C6D6): 8 0.62 (d, J r ^ = 2.5 Hz, Rh(Ctf3 )3 ), 1.64, 2.75 (m, NCH2\ 4.12 (s, CH2Ph), 6.90-7.20 (m, Q /^ ) . Recovery of Rhodium: Recovery of rhodium residues and reconversion to RhCl3 is often a worthwhile procedure. The literature recovery procedure3 7 works well and can be applied to the CnRh residues' recovery. HBR4(Et20 ) 234: The preparation of Na{B[C6H3 (CF3 )2]4) was carried out as literature reported.3 4 The sodium salt (4.0 g, 4.51 mmol) was first dissolved in 70 mL of ether over 3 A molecular sieves to remove any water of hydration for 12 h. Under stirring, the dehydrated NaBR4 ether solution was then added to the flask containing 6.74 mL 0.770 N (5.19 mmol) HC1 ether solution at room 84 temperature. White NaCl precipitates formed right away. This mixture was allowed to stir at RT for 50 min. The solution was then filtered and concentrated down to a very small volume until the solution became quite viscous. The viscous solution was cooled to -78 °C for 10 min, the supernatant was cannulated out at -78 °C. The resulting mixture was shaken to be loosen i and dried under vacuum for 2 h. White (or light manilar folder colored) product was obtained. Yield : 3.90 g (85%). The acid is indefinitely stable at -20 °C but not very stable at room temperature.3 4 After the acid is made, it should be stored in the freezer in a dry box. 1 HNMR (CD3SOCD3): 5 1.05 (t, 12H, CH 3 ), 3.33 (q, 8H, CH2), 7.60, 7.64 (s, 12H, Ai-H). CnRhM e2 BR4 To a -78 °C solution of 0.150 g CnRhMe3 (0.470 mmol) in 15 mL of CH2C12, 4 mL HBR4(Et20 )2 ether solution (0.476g (0.470 mmol) in 3.5 mL of ether) was slowly added. Five minutes after completion of the addition, this mixture was allowed to warm up to RT slowly and was stirred at this temperature for 50 min. Solvents were then reduced to ca. 2 mL under reduced pressure and 20 ml of pentane was injected to the flask. This resulted the formation of viscous material at the bottom of the Schlenk flask even upon stirring. The supernatant was cannulated out, followed by 2x15mL pentane wash of the product. The viscous material was dried under vacuum for several hours. Yellow solids were obtained. Yield: 0.47 g (86%). The 1 HNMR spectrum is the same as CnRhMe2OTf and CnRhMe2BF4 in DMSO-d^ except the absorptions of the BR4" anion at 7.60 (s, 8H) and 7.70 ppm (s, 4H) can be observed for CnRhMe2BR4. 85 Polyethylene ~ The typical polymerization condition of this CnRh system is as follows: 15 mg (0.032 mmol) CnRhMe(BF4)2 was dissolved in 2.5 mL organic solvent (acetone, methylene chloride, nitromethane or THF) in a 9 mm medium walled glass tube. Ethylene was transfered to the glass tube through vacuum line by freezing ethylene with liguid nitrogen. The amount of ethylene was calculated beforehand so that the pressure in the tube at room temperature would be 15 atm. The sealed tube was held on the stirring rod of the mechanical stir, the speed of which is controlled by a variac so that the slow spin of the stirring rod will give the effective agitation of the solution in the tube. The agitation was stopped after 7days. The glass tube was openned under liquid nitrogen temperature and the room temperature mixture was filtered. The white product was washed with 3x5 mL of 1 N triflic acid ether solution, then 3x5 mL of ether and vacuum dry. White polyethylene solid was obtained. 1 HNMR ( CDC12CDC12, 100 °C): 5 1.30 (s, (CH2)n). X-ray single crystal analysis of the "C nR h" complexes: CnRhMe3 and NhCnRhMe3 are air stable compounds thus they were mounted in air. [CnRh(q 3-allyl)(Cl)]+OTf- and [CnRh(CH3 )(p-Cl)2(CH3 )RhCn](BR4)2 are air sensative compounds, they were covered with thick oil in the dry box and then brought out of the box and mounted in the special small glass tubes (for X-ray) under oil protection. The tubes were then flame sealed. Data of all above crystals (except NhCnRhMe3 ) were collected on a Siemens P2j diffractometer at room temperature using Mo K a radiation (k = 0.71069 A). Data of NhCnRhMe3 was 86 collected on a Siemens P4/RA diffractometer with molybdeum rotating anode generater using Mo K a (X = 0.71073 A), by the favor of Dr. Charles Campana of Siemens Analytical Instrument Co. at Madison, Wisconsin. K inetic Experiments The preparation of the samples has been mentioned in the text. For the data collection at low temperature, the NMR tube of the sample was taken out of the -78 °C bath and quickly placed in the NMR detecting probe, the temperature of which had been presetted. The programmed (automated) data collection was started immediately. Data of over three half lives of CnRhMe2OTf were collected in all experiments. The built-in automated program of the Bruker 360 MHz NMR machine has been used for the peak integration and spactra printing. The Quattro Pro program(Version 4.0) was used for data analysis. Data kinetic Data: From page 88 to page 95. X-ray Data: From page 96 to page 122. 87 A - B - C O a ta se tO n e CnRhMe,OTf ([C]„ = 0.055M ) + C\H4 ([=]A V G = 0.058 M) in CD2CI2 at -36 °C k l k-2 k3 M l M2 M1*M2 M2-M1 M1/(M2-M1) M2/(M2-M1) j lime A A Norm A Calcd B BNorm B C alcd C C Norm, C Calcd 0 2.97 1.00 1.00 0 0.00 0.00 0 0.00 -0.00 1.42E-04 1207 2.52 0.84 0.85 0.43 0.14 0.14 0.067 0.02 0.02 3.00E-05 2165 2.24 0.74 0.74 0.656 022 021 0.15 0.05 0.05 1.85E-04 3122 1.98 0.65 0.65 0.786 026 0.26 0 2 7 0.09 0.09 4079 1.72 0.58 0.58 0.857 029 0 2 8 0.395 0.13 0.14 1.04E-04 5038 1.56 0.52 0.51 0.894 0.30 0.30 0.561 0.19 0.19 2.53E-04 5994 1.37 0.46 0.46 0.901 0.30 0.30 0.702 0 2 4 0 2 4 2.63E-08 6952 1 2 0.41 0.41 0.87 0.30 0.30 0.852 0 2 9 0.30 1.50E-04 7909 1.09 0.37 0.36 0.863 0 2 9 0 2 9 1.02 0.34 0.35 6.93E-01 8866 0.957 0.33 0.32 0.811 0 2 8 0 2 8 1.16 0.40 0.40 1.69E+00 9824 0.842 0.29 0.29 0.753 0 2 6 0 2 6 1 2 7 0.44 0.45 10781 0.771 0.26 0.26 0.726 0 2 5 0 2 5 1.43 0.49 0.49 11739 0.695 0.24 0.23 0.677 0 2 3 0 2 3 1.54 0.53 0.53 12696 0.626 0.21 0.21 0.636 0 2 2 0 2 2 1.68 0.57 0.57 13656 0.565 0.19 0.19 0.587 0 2 0 0 2 0 1.8 0.61 0.61 14611 0.507 0.17 0.17 0.542 0.19 0.19 1.88 0.64 0.65 15568 0.444 0.16 0.15 0.472 0.17 0.17 1.91 0.68 0.68 16526 0.395 0.14 0.14 0.429 0.15 0.16 1.97 0.71 0.71 17483 0.361 0.13 0.12 0.4 0.14 0.14 2.07 0.73 0.73 18440 0.331 0.12 0.11 0.367 0.13 0.13 2.17 0.76 0.76 19398 0.299 0.10 0.10 0.336 0.12 0.12 2 2 3 0.78 0.78 20355 0.264 0.09 0.09 0.301 0.11 0.11 2 2 4 0.80 0.80 0.8- 0 .6- 0.4- ■° 6 ' 2165 ‘ 4079 * 5994 7909 ' 9824'11/’ 39 13^56'15^68'17483'19098' 1207 3122 5038 6952 8866 10781 1269614611 16526 18440 20355 88 A-B-C Data set Two CnRhM e,OTf ([C]0 = 0.055M ) + C,H4 ([=]A V t; = 1.98 M) in CD2C12 at -36 °C time A A Norm A Calcd B B Norm B C alcd C C Norm C Calcd 0 0.93 1.00 1.00 0 0.00 0.00 0 0.00 -0.00 k l 224E -04 209 0.896 0.96 0.95 0.04 0.04 0.05 0 0.00 0.00 k-2 0.O0E+OO 566 0.808 0.88 0.88 0.097 0.11 0.11 0.008 0.01 0.00 k3 125E-04 924 0.765 0.79 0.81 0.169 0.18 0.18 0.03 0.03 0.01 1281 0.713 0.73 0.75 02 3 7 0 2 4 0 2 3 0.023 0.02 0.02 M 1 125E-04 1638 0.651. 0.70 0.69 02 6 4 0 2 8 0.28 0.018 0.02 0.03 M2 224E -04 1995 0.61 0.65 0.64 02 9 5 0.31 0.32 0.037 0.04 0.04 M1*M2 2.80E-08 2353 0.576 0.60 0.59 0.337 0.35 0.35 0.049 0.05 0.06 M2-M1 9.90E-05 2710 0.524 0.55 0.54 0.376 0.40 0.38 0.051 0.05 0.08 M1/(M2-M1) 126E+00 3067 0.493 0.50 0.50 0.411 0.41 0.40 0.088 0.09 0.09 M2/(M2-M1) 226E +00 3425 0.431 0.45 0.46 0.43 0.45 0.42 0.09 0.09 0.11 3783 0.41 0.43 0.43 0.41 0.43 0.44 0.131 0.14 0.13 4140 0.391 0.40 0.40 0.461 0.47 0.45 0.132 0.13 0.15 4497 0.36 0.36 0.37 0.464 0.47 0.46 0.165 0.17 0.17 4854 0.34 0.35 0.34 0.448 0.47 0.47 0.174 0.18 0.19. 5212 0.302 0.31 0.31 0.477 0.49 0.48 0.192 0 2 0 021 5569 0 2 4 7 0 2 7 0 2 9 0.456 0.50 0.48 0 2 1 8 0 2 4 0.23 5927 0251 0 2 6 0 2 7 0.468 0.49 0.48 0 2 3 6 0.25 0 2 6 6284 0211 0 2 3 0 2 4 0.443 0.48 0.48 0 2 6 3 0.29 0.28 6641 0 2 0 7 0 2 2 0 2 3 0.448 0.48 0.48 0 2 8 0.30 0.30 6999 0201 0 2 2 021 0.421 0.46 0.47 0 2 9 9 0.32 0.32 7356 0.168 0.18 0.19 0.443 0.48 0.47 0.319 0.34 0.34 7714 0.135 0.15 0.18 0.412 0.47 0.46 0.334 0.38 0.36 8071 0.132 0.14 0.16 0.432 0.46 0.45 0.366 0.39 0.38 8429 0.146 0.16 0.15 0.386 0.42 0.45 0.38 0.42 0.40 8786 0.107 0.12 0.14 0.392 0.43 0.44 0.408 0.45 0.42 9143 0.099 0.11 0.13 0.361 0.42 0.43 0.401 0.47 0.44 9501 0.116 0.13 0.12 0.364 0.39 0.42 0.443 0.48 0.46 9859 0.095 0.10 0.11 0.347 0.38 0.41 0.468 0.51 0.48 0.8- 0.6- 0.4- 0.2- ■ - 0 2 89 A - B - C Data set Three CnRhM e.OTf ([C J,, » 0.055M ) + C2H4 <[=JAV(. = 0.154 M) in C,D2CI2 at -36 °C time A A Norm A Calcd B B Norm B Calcd C C Norm C Calcd 0 3.59 1.00 1.00 0.00 0.00 0.00 0.00 0.00 0.00 k1 1.52E-04 269 3.42 0.95 0.96 0.15 0.04 0.04 0.02 0.01 0.00 k-2 4.00E-06 927 3.15 0.86 0.87 0.46 0.13 0.12 0.04 0.01 0.01 k4 1.38E-04 1584 2.87 0.78 0.79 0.71 0.19 0.19 0.09 0.02 0.02 2242 2.6 0.71 0.71 0.90 0 2 5 0 2 5 0.16 0.04 0.04 M 1 122E -04 2899 2.34 0.65 0.65 1.05 0 2 9 0 2 9 0 2 3 0.06 0.07 M2 1.72E-04 3556 2.09 0.58 0.58 1.16 0.32 0.32 0.33 0.09 0.09 M1*M2 2.10E-08 4217 1.88 0.53 0.53 123 0.35 0.35 0.42 0.12 0.12 M2-M1 5.03E-05 4871 1.71 0.48 0.48 1 2 9 0.37 0.36 0.53 0.15 0.16 M1/(M2-M1) 2.42E+00 5529 1.49 0.44 0.44 128 0.38 0.37 0.62 0.18 0.19 M2/(M2-M1) 3.42E+00 6186 1.31 0.40 0.40 1 2 6 0.38 0.38 0.71 0 2 2 0 2 2 6843 1.16 0.36 0.36 1 2 4 0.39 0.38 0.82 025 0 2 6 7501 1.04 0.33 0.33 122 0.38 0.38 0.93 0 2 9 0 2 9 8158 1 0.30 0.30 127 0.38 0.38 1.10 0.33 0.33 8816 0.83 0 2 7 0 2 7 1.13 0.37 0.37 1.06 0.35 0.36 9473 0.81 0 2 4 0 2 4 1 2 0 0.36 0.36 1.32 0.40 0.40 10130 0.73 0 2 2 0 2 2 1.14 0.35 0.35 1.41 0.43 0.43 10788 0.67 0 2 0 0 2 0 1.12 0.34 0.34 1.53 0.46 0.46 11445 0.61 0.18 0.18 1.07 0.32 0.33 1.62 0.49 0.49 12103 0.53 0.17 0.17 1.00 0.31 0.32 1.65 0.52 0.52 12760 0.49 0.16 0.15 0.95 0.30 0.30 1.71 0.54 0.55 13417 0.45 0.15 0.14 0.91 0.30 0 2 9 1.72 0.56 0.57 14075 0.41 0.13 0.13 0.87 0 2 7 0 2 8 1.91 0.60 0.60 14732 0.36 0.12 0.11 0.81 0.26 0 2 6 1.93 0.62 0.62 15389 0.34 0.10 0.10 0.79 0 2 4 0.25 2.12 0.65 0.65 16047 0.3 - 0.10 0.09 0.72 0 2 3 0 2 4 2.09 0.67 0.67 16704 0 2 6 0.09 0.09 0.67 0 2 2 0 2 2 2.10 0.69 0.69 17362 0 2 6 0.08 0.08 0.67 0 2 0 021 2.34 0.72 0.71 18019 0 2 2 0.07 0.07 0.60 0.19 0 2 0 2 2 7 0.73 0.73 18677 0 2 2 0.06 0.07 0.61 0.18 0.19 2.59 0.76 0.75 19334 0.19 0.06 0.06 0.56 0.17 0.18 2.55 0.77 0.76 0.9- 0.8- 0.7 0.6- 0.5- 0.4 0.3- 0.1 (Thousands) 9 0 CnRhM e,OTf ([C]„ = 0.055M) + C2H4 «=1AW = 0 .178 VI) in CD2C h at-26 "C A - B - C Data sat Fota at S t C time A A Norm A Calcd a 8 Norm B Calcd C C Norm C Calcd 0 321 1.00 1.00 0.00 0.00 0.00 0.00 0.00 0.00 kl a90E-04 221 2.99 0.83 0.82 0.55 0.15 0.16 0.08 0.02 0.02 k2 2.00E-05 380 2 3 5 0.72 0.71 0.78 0 24 02 4 0.14 0.04 0.05 k3 a75E-04 540 2.01 0.62 0.S2 0.96 0.30 0.30 0 2 5 0.08 0.08 696 1.78 05 4 0.54 1.09 0.34 0.33 0.39 0.12 0.13 Ml 7.59E-04 a ss 1.5 0.47 0.47 1.14 0.38 0.38 0.53 0.17 0.17 M2 1.03E-03 1013 128 0.41 0.41 1.15 0.37 0.37 0.68 02 2 02 2 M1-M2 7.79E-07 1171 1.15 0.38 0.38 1.19 0.37 0.37 0.86 02 7 02 8 M2-M1 267E-04 1329 0.95 0.31 0.31 1.11 0.36 0.38 0.99 0.32 0.33 M1/(M2-M1) 2.84E+00 1488 0.86 0 2 7 02 7 1.11 0.35 0.35 1.16 0.37 0.38 M2/(M2-M1) 3:84E+00 1648 0.73 0 2 4 02 4 1.05 0 34 0.34 1 2 9 0.42 0.42 1804 0.85 021 021 1.02 0.32 0.32 1.46 0.47 0.47 1963 0.59 0.18 0.18 0.99 0.31 0.31 1.84 051 0.51 2121 0.5 0.18 0.16 0.91 02 9 0 2 9 1.78 0 5 6 0.55 2279 0.44 0.14 0.14 0.85 0 2 7 0 2 7 1.91 0.60 0.59 2437 0.38 0.12 0.12 0.79 0 2 5 0 2 5 2 0.63 0.63 2596 0.34 0.11 0.11 0.73 0 2 3 02 3 2.13 0.67 0.66 2754 0.3 0.09 0.09 0.88 021 021 2 2 3 0.69 0.69 2912 0 2 8 0.08 0.08 0.83 0.19 0 2 0 2.35 0.73 0.72 0.9- 0. 8- 0.7- 0.6- 0.5- 0.4- 0.3- 0.2- 0 . 1- 696 1013 1329 1646 1963 2279 2596 2912 380 221 540 855 1171 1488 1804 2121 2437 2754 CnRhiVle2O Tf ([C]0 = 0.055M ) + C2H4 ([=]A V U = 0.187 M) in CD2C12 at -23 °C A • 3 • C Data sat Five at* 23C raw n o rm tim e A A N o rm A C a lc d B 8 N o rm B G a te d C C N o rm C C a t a d ln(A) ln(a) 0 2 .2 3 1 .0 0 1 .0 0 0 0 .0 0 0 .0 0 0 0 . X 0 .0 0 0 .8 0 O X k1 1 .1 5 6 * 0 3 2 0 0 1 .4 9 0 .81 0 .7 9 0 .3 1 0 .1 7 0 .1 8 0 .0 3 O X O X 0 .4 0 - 0 2 1 k -2 0 0 0 6 + 0 0 2 5 9 1 .6 4 0 .7 6 0 .7 4 0 .4 6 0 2 1 0 2 2 0 .0 6 O X 0 .0 4 0 .4 9 • 0 .2 8 K3 1 .3 0 6 -0 3 3 1 8 1 .4 9 0 .7 0 0 .6 9 0 .5 3 0 .2 5 0 2 5 0.1 O X o x 0 .4 0 -0 .3 5 3 7 8 1 .4 5 0 .6 6 0 6 5 0 .6 1 0 2 8 0 2 7 0 .1 4 O X 0 .0 6 0 .3 7 0 . 4 2 M1 1 .1 5 6 -0 3 4 3 7 1 .3 0 0 .6 1 0 .6 0 0 .6 8 0 .3 0 O X 0 2 0 .0 0 o . t o O .X 0 . 4 9 M 2 1 .3 0 6 * 0 3 4 9 6 1 .3 0 .5 7 0 .5 7 0 .7 2 0 .3 2 0 .3 1 0 . 2 6 0 .1 1 0 .1 2 O X 0 . 5 6 M 1 ”M 2 1 .5 0 6 -0 6 5 5 5 1 2 0 .5 3 0 .5 3 0 .7 5 0 .3 3 0 .3 2 0 .3 0 .1 3 0 .1 5 0 .1 8 0 . 6 3 M 2-M 1 1 .5 0 6 -0 4 6 1 4 1 .0 9 0 .5 0 0 .4 9 0 .7 5 0 .3 4 O X 0 .3 6 a i6 0 .1 7 0 .0 9 0 . 7 0 M 1/(M 2-M 1) 7 . 6 7 6 + 0 0 6 7 3 0 .9 9 0 .4 6 0 .4 6 0 .7 5 0 .3 5 0 .3 4 0 .3 9 0 .1 8 0 .2 0 -0 .0 1 0 . 7 7 8 .6 7 6 + 0 0 7 3 2 0 .9 1 0 .4 3 0 4 3 0 .7 4 0 .3 5 0 .3 4 0 .4 5 0 2 1 0 2 3 - 0 .0 9 0 . 8 4 7 9 2 0 .3 8 0.41 0 .4 0 0 .7 7 0 .3 5 O X 0 .5 2 0 2 4 0 .2 5 -0 .1 3 O X 8 51 0 .3 4 0 .3 8 0 .3 8 0 .7 9 0 .3 5 0 .3 5 0 .6 0 2 7 0 .2 8 -0 .1 7 O X 9 1 0 0 .7 8 0 .3 5 0 .3 5 0 .7 8 0 .3 5 0 .3 4 0 .6 7 O X 0 .3 1 -0 .2 5 -1 .0 5 9 6 9 '0 . 7 5 0 .3 3 0 .3 3 0 .7 8 0 .3 4 0 .3 4 0 7 4 O X o x -0 .2 9 -1.1 1 1 0 2 8 0 .6 8 0.X 0 .3 1 0 .7 6 0 .3 4 0 .3 4 0 .8 1 0 .3 6 0 .3 6 - O X - 1 2 0 1 0 8 7 0 .6 4 0 2 8 0 2 9 0 .7 5 0 .3 3 O X 0 .8 7 a x O X - 0 .4 5 • 1 2 6 1 1 4 6 0.61 0 2 7 0 2 7 Q .74 O X O X O X 0 .4 1 0.4 1 •0 .4 9 -1.3 1 1 2 0 6 0 .5 7 0 2 5 0 2 5 0 .7 2 0.31 o x 1.01 0 .4 4 0 .4 3 - 0 .5 6 - 1 .4 0 1 2 6 5 0 .5 3 0 2 3 0 2 3 0 .6 9 0.31 0 .3 1 1 .0 4 a46 0 .4 6 - O X - 1 .4 5 1 3 2 4 0 .4 7 0 2 1 0 2 2 0 .6 5 O X O X 1 .0 8 0 .4 9 0 .4 8 •0 .7 6 -1 .5 4 1 3 8 3 0 .4 5 0 2 1 O X 0 .6 2 0 2 8 O X 1.11 0 .5 1 0 5 0 -0 .8 0 -1 .5 8 1 4 4 2 0 .4 2 0 .1 9 0 .1 9 0.61 0 2 7 0 2 8 t x 0 .5 4 o x -0 .8 7 -1 .6 7 1501 0 .4 1 0 .1 8 0 .1 8 0 .6 0 0 2 7 0 2 8 I X 0 .5 5 O X - O X -1 .7 0 1 5 6 0 0 .3 6 0 .1 6 0 .1 7 0 .5 6 0 .2 S 0 2 7 I X 0.X 0 .5 7 - 1 .0 2 -1.81 16 2 0 0 .3 4 0 .1 5 0 .1 6 0 .5 4 0 2 4 O X 1 .3 5 0 .6 1 O X -1 .0 8 • 1 .8 9 1 6 7 9 0 .3 3 0 .1 5 0 .1 5 0 .5 3 0 2 4 O X 1 .3 9 0 .6 2 0 .6 1 -1 .1 1 -1 .9 2 17 3 8 0 .3 0 .1 4 0 .1 4 0 .5 0 0 2 3 0 2 4 1 .3 9 0 .6 3 O X •1 .2 0 - I X 1 7 9 7 0 2 9 0 .1 3 0 .1 3 0 .4 9 . 0 2 2 O X 1 .4 7 0 .6 5 0 .6 4 - 1 2 4 -2 .0 5 1S 5 6 0 2 7 0 .1 2 0 .1 2 0 .4 7 0 2 1 o x 1 .4 9 0 .6 7 0 .6 6 -1.3 1 -2.1 1 1 9 1 5 0 2 4 0.11 0 .1 1 0 .4 3 O X 0 2 1 1 .5 3 0 .7 0 0 .6 8 - 1 .4 3 - 2 2 2 1 9 7 4 0 .2 3 0 .1 0 0 .1 0 0 .4 2 0 .1 9 0 2 0 1 .5 8 0 .7 1 0 .6 9 -1 .4 7 - 2 2 7 2 0 3 3 0 2 3 0 .1 0 0 .1 0 0 .4 1 0 .1 8 0 .1 9 1 .6 6 0 7 2 0 .7 1 -1 .4 7 -2 .3 0 2 0 9 3 0 2 0 .0 9 0 .0 9 0 .3 7 0 .1 7 0 .1 9 1 . X 0 .7 4 0 .7 2 -1.6 1 -2 .3 9 2 1 5 2 0 .1 9 0 0 9 0 .0 8 0 .3 6 0 .1 6 0 .1 8 1 .6 6 0 .7 5 0 .7 4 -1 .6 6 - 2 .4 5 2 2 1 1 0 .1 9 0 .0 8 0 .0 8 0 .3 5 0 .1 6 0 .1 7 1 .7 0 .7 6 0 .7 5 -1 .6 6 -2 .4 7 0.4- 500 1000 1500 2000 2500 j i s 92 CnRhMe2O Tf ([C]„ = 0.0S5M ) + C,H4 ([=]A V (; = 0.14 M) in CD;CU at -48 °C A - B - C Data set Six Sme A A Norm A Calcd 8 • BNorm B C alcd C C Norm C Calcd Q 3 2 1.00 1.00 0 0.00 0.00 0 0.00 0.00 k1 2.65E-05 323 3.28 0.97 0.99 0.1 0.03 0.01 0 0.00 0.00 k-2 6.60E-07 4739 2.94 0.86 0.88 0.4 0.12 0.11 0.07 0.02 0.01 k3 1.90E-05 9154 2.65 0.78 0.79 0.64 0.19 0 2 0 0.1 0.03 0.02 13570 2.42 0.70 0.70 0.88 0 2 5 0 2 6 0.17 0.05 0.04 M 1 1.77E-05 17986 2.06 0.61 0.62 1.04 0.31 0.32 0 2 6 0.08 0.06 M2 2.85E-05 22401 1.72 0.53 0.55 1.09 0.34 0.35 0.41 0.13 0.09 Mt*M2 5.04E-10 26817 1.51 0.49 0.49 1.16 0.37 0.38 0.43 0.14 0.12 M2-M1 1.08E-05 31233 1.4 0.43 0.44 127 0.39 0.40 0.58 0.18 0.15 M1/(M2-M1) 1.64E+00 35648 1.35 0.39 0.39 1.42 0.41 0.42 0.71 0 2 0 0.19 M2/(M2-M1) 2.64E+00 40064 1.05 0.35 0.35 122 0.41 0.42 0.71 0 2 4 0 2 2 44480 1.01 0.31 0.31 1.35 0.42 0.43 0.86 0 2 7 0 2 6 48895 0.88 0 2 8 0 2 8 1.32 0.42 0.42 0.92 0 2 9 0.30 53311 0.71 0 2 5 0 2 5 1.16 0.41 0.42 0.98 0.34 0.33 57727 0.71 0 2 2 0 2 2 129 0.41 0.41 1.18 0.37 0.37 62143 0.63 0 2 0 0 2 0 1 2 6 0.40 0.40 12 8 0.40 0.40 66558 0.56 0.18 0.18 121 0.39 0.39 1.34 0.43 0.43 70974 0 5 0.16 0.16 1.16 0.38 0.37 1.39 0.46 0.46 75390 0.42 0.14 0.14 1.09 0.36 0.36 1.5 0.50 0.50 79805 0.44 0.14 0.13 1.13 0.35 0.35 1.64 0.51 0.53 84221 0.37 0.12 0.12 1.04 0.33 0.33 1.74 0.55 0.55 88637 0.43 0.13 0.10 1.09 0.32 0.32 1.84 0.55 0.58 93052 0.3 0.10 0.09 0.93 0.31 0.30 1.81 0.60 0.61 97468 0.26 0.08 0.08 0.9 0 2 8 0 2 9 2.02 0.64 0.63 101884 0 2 4 0.08 0.08 0.83 0 2 8 0 2 7 1.85 0.63 0.65 106299 0.23 0.07 0.07 0.83 0 2 6 0 2 6 2.1 0.66 0.68 110715 021 0.07 0.06 0.8 0 2 5 0 2 4 2.19 0.68 0.70 115131 0.17 0.06 0.05 0.67 0 2 3 0 2 3 2.04 0.71 0.72 119547 0.15 0.04 0.05 0.7 021 0.21 2.51 0.75 0.74 123962 0.19 0.05 0.04 0.75 021 0.20 2.62 0.74 0.75 0.9- 0.8- 0.7- 0.5- 0.4- 02 - 93 The -Ink3 - 1/T plot for the insertion reaction of 16 (-48 - -23C). k3 -In (k 3) t(C ) T (K ) (1/T)X1E3-ln(k3)calcd 0.0013 6.645391 -23 250.15 3.997601 6.645959 0.000875 7.041287 -26 247.15 4.046126 7.11393 0.000138 8.888257 -36 237.15 4.21674 8.759344 1.9E-05 10.87107 -48 225.15 4.441483 10.92677 -31.9071 0.1118 } 0.997781 j 4 ! 2 : X Coefficient(s) 9644.036 Std E r r of Coef. 321.6249 i 10.5-- 10-- 2 c T 8.5 7.5 .45 1/T(X1000) Regression O u tp u t: Constant Std E r r of Y Est R Squared No. of Observations Degrees of Freedom The -In k ^ - 1 fT plot for the insertion reaction of 16 (-48 - -23C). k3 t(C ) T (K ) 1/T X 1E 3 -In (k 3/T ) -In(k3/T )calcd 0.0013 -23 250.15 3.997601 12.16745 12.16751 0.000875 -26 247.15 4.046126 12.55128 12.62398 0.000138 -36 237.15 4.21674 14.35695 14.22894 1.9E-05 -48 225.15 4.441483 16.28784 16.34309 Regression O utput Constant Std ErrofYEst R Squared No. of Observations Degrees of Freedom X Coefficient(s) 9406.945 . Std E r r of Coef. 319.8487 16.5- 1 & - 15.5-' 15-- P 14.5- 14-- 13.5- 15- 12.5- 1/T(X1000) -25.4377 0.111183 0.997693 4 2 Table 1: Summary of Crystal Data and Refinement Results for CnRhMe3 molecular weight(g/mole) 319.3 space group P2an (No. 30) molecules per unit cell 4 a (angstrom) 14.757 b (angstrom) 7.777 c (angstrom) 13.118 a(deg) 90.00 |3(deg) 90.00 y(deg) 90.00 V (angstrom3) 1505.49 crystal dimensions (mm) 0.3 x 0.3 x 0.4 calculated density (g cm '3) 0.8484 wavelength (angstrom) u sed , for data collection 0.71069 Sine/X limit (angstrom-1) 0.5947 total number of reflections m easured 1562 number of reflections used in structural analysis 1 > 3o(l) 1153 number of variable param eters 144 final agreem ent factors R(F) = 0.0378 Table 2: Final Atomic Coordinates for CnRhMe3 Atom X y z RH1 0.5980( 1) 0.3156( 1) 10.0000( 0) N1 0.6851 < 9) 0.4680(13) -0.1080(11) N2 0.5162( 5) 0.5546( 9) -0.0055(13) N3 0.6727( 9) 0.4815(13) 0.1107(11) C1 0.5283(11) 0.1905(15) -0.1213(11) C2 0.6855( 7) 0.1017(11) 0.0123(12) C3 0.5154(10) 0.1820(14) 0.0990(10) C4 0.7306(10) 0.3625(15) -0.1891(11) C5 0.6052(11) 0.5847(14) -0.1552(11) C6 0.5269(10) 0.6361(15) -0.1004(12) C7 0.4163( 7) 0.5245(13) 0.0222(11) C8 0.5504( 9) 0.6689(14) 0.0851(11) C9 0.6282(10) 0.6350(13) 0.1375(11) C10 0.6976(10) 0.3858(14) 0.2084(11) C11 0.7634( 9) 0.5126(14) 0.0505(11) C12 0.7484(10) 0.5810(15) -0.0546(12) Table 3: Tem perature Factors for CnRhMe3 Atom Un X103 u 22x io 3 U33X103 U12X103 U13X103 U23X103 RH1 34( 0) 32( 0) 51 ( 0) -1(0) 0( 1) 3( 1) N1 63 ( 2) 45( 2) 55( 2) 5( 2) 21(2) 3( 2) N2 37( 2) 48( 2) 69( 2) 4( 2) 0( 2) 3( 2) N3 49( 2) 56( 2) 58( 2) -2( 2) -17( 2) 7( 2) C1 74( 2) 72( 2) 78( 2) -24( 2) -10( 2) -13( 2) C2 53( 2) 44( 2) 75( 2) 7( 2) 5( 2) -9( 2) C3 62f 2) 60( 2) 61(2) -14( 2) 4( 2) 18( 2) C4 80( 2) 102( 2) 72( 2) 7(2) 32( 2) -10( 2) C5 85( 2) 80( 2) ' 73( 2) 4( 2) -2( 2) 23( 2) C6 78( 2) 94( 2) 85( 2) 8( 2) -1(2) 24( 2) C7 39( 2) 91 ( 2) 92( 2) 10( 2) -5( 2) -6( 2) C8 67 ( 2) 68( 2) 82( 2) 18< 2) 13( 2) -39( 2) C9 76( 2) 58( 2) 64( 2) 6( 2) -12( 2) -21( 2) CIO 83{ 2) 89( 2) 63( 2) 24( 2) -28( 2) 9( 2) C11 43( 2) 78( 2) 92( 2) -24( 2) -13( 2) 1( 2) C12 66( 2) 93 ( 2) 99( 2) -24( 2) -4( 2) 9( 2) The complete temperature factor is exp[-2jt2(U1,h2a’2 + U22k2b’2 + U33l2c’2 + 2U12hka'b' + 2U13hla’c’ + 2U23klb’c’] Table 4: Bond D istances(angstrom s)for CnRhMe3 RH1 —N1 RH1 —N2 RH1 —N3 RH1 —C1 RH1 —C2 RH1 —C3 N1 —C4 N1 —C5 N1 —C12 N2 — C6 N2 —C7 N2 —08 N3 —C9 N3 —C10 N3 —C11 C5 —C6 C8 —C9 C11 —C12 2.250(12) 2.217( 7) 2.233(12) 2.130(14) 2.111 ( 9) 2.062(13) 1.502(17) 1.611(18) 1.462(18) 1.406(21) 1.537(13) 1.568(18) 1.407(16) 1.527(18) 1.573(19) 1.419(21) 1 363(19) 1.495(16) Table 5: Bond Angles (deg) for CnRhMe3 N1 -RH1-N2 81.3( 4) N1 -RH1-N3 79.8( 3) N2 -RH1 -N3 78.8( 4) N1 -RH1-C1 92.6(5) N2 -RH1 -C1 95.5( 5) N3 -RH1-C1 171.1( 5) N1 -RH1-C2 96.6( 4) N2 -RH1-C2 174.6( 4) N3 -RH1-C2 96.0( 4) C1 -RH1-C2 89.6( 5) N1 -RH1-C3 178.2( 5) N2 -RH1-C3 96.9( 5) N3 -RH1 -C3 100.0( 5) C1 -RH1-C3 87.4( 4) C2 -RH1-C3 85.2( 5) RH1 -N1 -C4 114.4( 7) RH1 -N1 -C5 97.0( 8) C4 -N1 -C5 111.3(12) RH1 -N1 -C12 112.3( 9) C4 -N1 -C12 112.4(11) C5 -N1 -C12 108.2( 9) RH1-N2 -C6 110.2( 9) RH1-N2 -C7 112.8( 6) C6 -N2 -C7 112.7(11) RH1 -N2 -C8 106.0( 7) C6 -N2 -C8 112.3( 8) C7 -N2 -C8 102.5(11) RH1 -N3 -C9 115.0( 9) RH1 -N3 -C10 112.5( 7) C9 -N3 -C10 108.4(12) RH1 -N3 -C11 100.5( 8) C9 -N3 -C11 113.1(10) C10-N3 -C11 106.9(10) N1 -C5 -C6 124.0(12) N2 -C6 -C5 114.4(11) N2 -C8 -C9 122.9( 9) N3 -C9 -C8 115.5(11) N3 -C11 -C12 113.0(12) N1 -C12-C11 108.8(11) 100 Table 1: Summary of Crystal Data and Refinement Results for [CnRh(Cl)(n’-allyl)]OTf molecular weight(g/mole) 499.78 space group C2 (No. 5) molecules per unit cell 4 a (angstrom) 14.837 b (angstrom) 8.8660 c (angstrom) 16.221 ct(deg) 90.00 |}(deg) 95.76 7(deg) 90.00 V (angstrom3) 2123.01 crystal dimensions (mm) 0.3 x 0.3 x 0.3 calculated density (g cm'3) 1.569. wavelength (angstrom) used for data collection 0.71069 Sine/A. limit (angstrom-1) 0.5947 total number of reflections measured 1469 number of reflections used in structural analysis I > 3a(l) 1191 number of variable parameters 226 final agreement factors R(F) = 0.0910 Table 2: Final Atomic Coordinates for [CnRh(CI)(y-allyI)]OTf Atom X y z RH 1 0.2143( 1) 10.0000( 0) 0.1565( 1) CL 2 0.1955( 4) -0.0003(22) 0.0095( 3) S 3 0.3529( 4) 0.4990(21) 0.3297( 4) N 4 0.2078(11) 0.0133(33) 0.2869(10) N 5 0.1111(15) -0.1600(26) 0.1617(16) N 6 00953(17) 0.1593(29) 0.1542(18) C 7 0.3271(19) 0.1687(32) 0.1504(19) C 8 0.3348(21) -0.1178(32) 0.1335(21) C 9 0.3584(15) -0.0517(33) 0.1746(19) C 10 0.1157(20) -0.2203(34) 0.2450(22) C 11 0.1387(20) -0.1257(32) 0.3079(19) C 12 0.1830(21) 0.1510(33) 0.3064(19) C 13 0.0963(20) 0.2124(34) 0.2420(22) C 14 0.0228(18) 0.0921(29) 0.1155(17) C 15 0.0125(17) -0.0700(28) 0.1502(17) C 16 0.0893(21) -0.2817(32) ' .0.0884(21) C 17 0.2913(17) 0.0421(27) 0.3469(15) C 18 0.1292(21) 0.3009(30) 0.1084(19) C 19 0.3281(19) 0.5055(44) 0.4325(18) 0 20 0.4117(12) 0.3774(24) 0.3266(13) O 21 0.2656(15) 0.5077(40) 0.2911(14) O 22 0.3825(18) 0.6469(30) 0.3074(19) F 23 0.266^15) 0.3888(26) 0.4417(14) F 24 0.3023(16) 0.6266(28) 0.4656(14) F 25 0.4006(17) 0.4677(32) 0.4886(14) Table 3; Temperature Factors for [CnRh(Cl)(77'-aI!yl)]OTf Atom U,,X103 U,2X103 U33X103 U,2X103 U,3X103 U23X103 RH 1 24( 1) 53(1) 41 ( 1 ) 7( 2) 13( 0) 4( 2) CL 2 59( 3) 72( 3) 42( 2) -4( 4) 19( 2) 4(4) S 3 55( 3) 64( 3) 57( 3) •15( 4) 23( 2) 6( 4) N 4 42( 4) 53( 5) 38( 4) 3( 5) 6( 4) -1( 5) N 5 31( 5) 33< 4) 47( 4) -1( 4) 1(4) -6{ 4) N 6 44( 5) 45< 5) 54( 5) 8( 4) 12( 4) -4( 4) C 7 37( 5) 76( 5) 68( 5) ■19( 5) 16 < 5) -6( 5) C 8 42( 5) 74( 5) 83( 5) 24( 5) 15( 5) -8( 5) C 9 14( 4) 119( 5) 93( 5) 5( 5) 23 ( 4) -4( 5) C 10 60( 5) 69( 5) 61(5) -11( 5) 14( 5) 20( 5) C 11 67(5) 70( 5) 61 ( 5) -19( 5) 16( 5) 5( 5) C 12 73( 5) 71 ( 5) 62( 5) 15( 5) 20( 5) 3( 5) C 13 57( 5) 74( 5) 63( 5) 5( 5) 13( 5) -18( 5) C 14 52( 5) 48( 5) 57( 5) 6 < 5) -3( 5) -6( 5) C 15 39( 5) 53( 5) 58( 5) -2( 5) 4( 5) ■ 7( 5) C 16 66( 5) 60( 5) 83( 5) 5( 5) 9( 5) -16( 5) C 17 58( 5) 68( 5) 48( 5) -4( 5) -11(4) 3( 5) C 18 78( 5) 49( 5) 69( 5) 18( 5) 21 ( 5) 17( 5) C 19 82( 5) 77( 5) 90( 5) 7( 5) 21(5) 3( 5) O 20 40( 4) 71 ( 5) 77( 5) 16( 4) 25( 4) •16( 4) O 21 96( 5) 113( 5) 114( 5) 0( 5) -26( 5) -1( 5) 0 22 77( 5) 96 ( 5) 127( 5) 1( 5) 24( 5) 26( 5) F 23 88( 5) 101 ( 5) 108{ 5) -15( 5) 33( 4) 13( 5) F 24 112( 5) 114( 5) 87( 5) 15( 5) 11( 5) -33( 5) F 25 157( 5) 147( 5) 112( 5) -7( 5) 9( 5) 7( 5) The complete temperature factor is exp[-2it2(U11h2a '2 + U22k2b'2 + U33l2c '2 + 2U12hka'b‘ + 2U,3hla'c' + 2U23klb’c'] 103 Table 4: Bond Distances(angstroms)for [CnRh(Cl)(ijJ-alIyl)]OTf RH 1— CL 2 2.373( 5) RH 1—N 4 2.130(15) RH 1—N 5 2.095(23) RH 1—N 6 2.259(25) RH 1— C 7 2.253(27) RH 1—C 8 2.135(28) RH 1—C 9 2.177(22) S 3—C 19 1.744(28) S 3—0 20 1.390(23) S 3—0 21 1.384(21) S 3—0 22 1.440(30) N 4—C 11 1.659(35) N 4—C 12 1.323(38) N 4—C 17 1.520(28) N 5—C 10 1.448(41) N 5—C 15 1.660(33) N 5—C 16 1.614(38) N 6—C 13 1.499(43) N 6—C 14 1.331(34) N 6—C 18 1.567(38) C 7—C 9 2.038(42) C 8—C 9 0.930(39) C 10—C 1 1 1.339(43) C 12—C 13 1.666(44) C 12—C 17 1.932(38) C 14—C 15 1.557(32) C 19—F23 1.395(39) C 19— F 24 1.277(41) C 19—F25 1.379(34) Table 5: Bond Angles (deg) for [CnRh(CI)(^-allyl)]OTf CL 2-RH 1-N 4 170.2( 5) CL2-RH 1-N 5 91.5( 8) N 4-RH 1-N 5 83.8( 9) CL2-RH 1-N 6 88.3( 8) N 4-RH 1-N 6 82.4( 9) N 5-RH 1-N 6 81.4( 6) CL 2-RH 1-C 7 88.2( 8) N 4-RH 1-C 7 96.6(10) N 5-RH 1-C 7 179.0(10) N 6-RH 1-C 7 99.6(10) CL 2-RH 1-C 8 80.8( 9) N 4-RH 1-C 8 108.9(10) N 5-RH 1-C 8 107.7(11) N 6-RH 1-C 8 165.9(11) C 7-RH 1-C 8 71.3(11) CL 2-RH 1-C 9 98.6( 8) N 4-RH 1-C 9 91-1 ( 9) N 5-RH 1-C 9 124.3( 9) N 6-RH 1-C 9 152.8(10) C 7-RH 1-C 9 54.7(11) C 8-RH 1-C 9 24.9(10) C 19-S 3-0 20 104.7(16) C 19-S 3-0 21 98.8(14) O20-S 3-0 21 126.2(20) C 19-S 3-0 22 107.9(20) 0 20-S 3-0 22 119.3(13) 0 21-S 3-0 22 97.5(20) RH 1-N 4-C 11 104.7(15) RH 1-N 4-C 12 109.3(19) C 11-N 4-C 12 116.4(21) RH 1-N 4-C 17 122.0(14) C 11-N 4-C 17 1183(19) C 12-N 4-C 17 85.4(21) RH 1-N 5-C 10 108.8(17) RH 1-N 5-C 15 108.0(14) C 10-N 5-C 15 103.9(22) RH 1-N 5-C 16 121.1(19) C 10-N 5-C 16 115.3(23) C 15-N 5-C 16 . 97.4(17) RH 1-N 6-C 13 104.4(17) RH 1-N 6-C 14 108.7(18) C 13-N 6-C 14 121.3(26) RH 1-N 6-C 18 102.8(16) C 13-N 6-C 18 103.1(22) C 14-N 6-C 18 114.7(25) [CnRh(Cl)(7>3-allyl)]OTf Table 5: (continued) RH 1-C 7-C 9 60.7(10) RH 1-C 8-C 9 80.1(24) RH 1-C 9-C 7 64.5(10) RH 1-C 9-C 8 75.0(24) C 7-C 9-C 8 113.8(31) N 5-C 10-C 11 117.6(26) N 4-C 11-C 10 115.2(24) N 4-C 12-C 13 111.5(25) N 4-C 12-C 17 51.6(14)' C 13-C 12-C 17 160.1(23) N 6-C 13-C 12 115.2(23) N 6-C 14-C 15 110.3(24) N 5-C 15-C 14 111.5(21) N 4-C 17-C 12 43.0(15) S 3-C 19-F23 106.3(23) S 3-C 19-F24 122.1(27) F23-C 19-F24 110.6(23) S 3-C 19-F25 113.4(21) F23-C 19-F25 102.9(27) F24-C 19-F25 100.0(27) Table 1: Summary of Crystal Data and Refinement Results for [CnRh(CH3)(M -Cl)2(CH3)RhCn](BR4)2 molecular weight(g/mole) 2375.8 (dimer) space group P,bar(No. 2) molecules per unit cell 2 a (angstrom) 13.612 b (angstrom) 14.448 c (angstrom) 12.809 a(deg) 94.43 P(deg) 96.91 iKdeg) 86.40 V (angstrom3) 2489.80 crystal dimensions (mm) 0.3 x 0.4 x 0.5 calculated density (g cm'3) M l wavelength (angstrom) used for data collection 0.71069 Sine/X limit (angstrom'1) 0.5947 total number of reflections measured 5870 number of reflections used in structural analysis I > 3cr(l) 2819 number of variable parameters 334 final agreement factors R(F) = 0.118 107 Table 2: Final Atomic Coordinates for [CnRh(CH0(M-Cl)2(CH3)RhCn](BR4)2 Atom X y z RH 1 0.4391 ( 2) 0.0804( 2) 0.0864( 2) CL 2 0.4311( 6) 0.0406( 7) -0.0940( 6) N 3 0.3331(13) 0.1910(13) 0.0798(16) N 4 0.4590(15) 0.1165(16) 0.2490(17) N 5 0.3167(15) 0.0043(14) 0.1313(18) C 6 0:5348(24) 0.1633(27) 0.0370(27) B 7 0.2065(15) 0.7155(16) 0.4085(16) C 8 0.1515(13) 0.8207(12) 0.3811(14) C 9 0.0931(15) 0.8315(14) 0.2912(15) C 10 0.0509(14) 0.9213(16) 0.2692(16) C 11 0.0720(15) 0.9987(15) 0.3343(17) C 12 0.1331(15) 0.9870(14) 0.4242(14) C 13 0.1756(14) 0.8987(12) 0.4504(15) C 14 0.3030(15) 0.7043(14) 0.3410(14) C 15 0.3874(14) 0.7498(13) 0.3798(15) C 16 0.4693(15) 0.7434(15) 0.3277(16) C 17 0.4657(17) 0.6955(15) 0.2285(17) C 18 0.3785(16) 0.6542(14) 0.1821(14) C 19 0.2988(16) 0.6579(15) 0.2400(15) C 20 0.2370(15) 0.7014(13) 0.5301(14) C 21 0.1807(15) 0.7411(14) 0.6079(15) C 22 0.2082(17) 0.7187(14) 0.7135(16) C 23 0.2886(16) 0.6596(15) 0.7433(16) C 24 0.3417(15) 0.6197(14) 0.6644(16) C 25 0.3181(15) 0.6382(13) . 0.5611(15) C 26 0.1260(14) 0.6347(14) 0.3756(13) C 27 0.0211(15) 0.6531(15) 0.3675(16) C 28 -0.0387(15) 0.5826(16) 0.3424(17) C 29 -0.0063(17) 0.4876(15) 0.3292(17) C 30 0.0921(17) 0.4708(16) 0.3435(17) C 31 0.1638(17) 0.5391(14) 0.3650(15) C 32 0.4269( 8) 0.5521 ( 8) 0.6921(10) F 33 0.4245(12) 0.4758( 9) 0.6318(12) F 34 0.4346(15) 0.5250(14) 0.7870(10) F 35 0.5125(10) 0.5839(10) 0.6842(17) C 36 0.1444( 9) 0.7591(9) 0.7959( 8) F 37 0.0615(10) 0.8031(10) 0.7642(10) F 38 0.1202(14) 0.7001(10) 0.8584(13) F 39 0.1933(10) 0.8199(13) 0.8578(14) C 40 0.1298( 9) 0.3706( 7) 0.3329(10) F 41 0.2221(9) 0.3555(10) 0.3690(13) F 42 0.0825(11) 0.3142(12) 0.3801(14) F 43 0.1237(13) 0.3367(12) 0.2358( 9) C 44 -0.1482( 8) 0.5986(11) 0.3356(13) F 45 -0.1962(15) 0.5549(13) 0.3963(15) F 46 -0.1747(13) 0.6855(10) 0.3541(19) F 47 -0.1899(15) 0.5772(16) 0.2412(12) 108 Table 2: (continued) o c m r— i c U X u C D y C M O N C O co ■ — y v ~ y > * - T - (J) in 00 in <o u o y o C D C M 00 o cn co 00 lO 5- C O N o 8 o o o o a o O ' i n o 5 T 9 . m i ^ . 2 o o o T ~ C M ■V ▼ “ ▼- C M C M C M m C M m m N o i n o m C D 00 i n o <0 (0 00 i n Tf in C M t " o o o o o o o n ^ to io iS T - i f n i n t o c o co it- cn < j) c m o > O C M C M < M O O a; u U I co S T o n co o cd < 0 y f T o ^ ^ ^ o T c o o c m o S r — ^ r — ^ y ^ y ^ r - ^ r - y ^ . C M ^ ^ C M O J CM Sf2m<7>S^ococMST-^>t;tf)r-cMoinintno , f : .r '- » c £ :in c 0 < 0 o . OOOq Oq qOO^ o>a)co<o<M^<oo5^T-is. _^u)-r~c\ioinintoocoC4^o> o>co9oT-r-oJWr-ooor-cgo 0 0 ^ ^ ^ ^ 0 0 0 0 0 0 0 0 0 c u y y y CD -M- O CM ( D CO y in a* co o a w y ■ * ■ * * y < w y * ■ “ y "W * - y y y y CM CM in c d in CM CM 0 0 ( 0 CM t o 5 T in s y " to r*'. 0 0 0 0 CO T— y CM V CD in m O 0 0 CO s o CM r-» CO m LO o y o o 0> o CD t o in ( 0 CO CO w o y o o y C M CO CO d d o o o o o o o o o o o d o o d C O O y O C D C M <* ^ C M C M C M C M C M o o o o o o o o o C D o in in C M in 8 3 in in (0 in in 00 in CD m o to y to C M 10 o ll UL u . O U- U L IL LL LL u . O LL IL 109 - r m T i O T i ' m i O ' n ' n T i O ' n T T n O O O O O O O O O O O O O O O O O O O O O O O O O C D O Z Z Z O J J NO>Ol5uN-‘o<D®'<(JiOI^QM-‘ 0(O O O SO >O IA w k)-‘0(C a)M O )O l4kC dlO -‘0 (0® ®0 '* UIO -. > o 3 ® o i 0 ^ r o - ‘ Oco-‘ y i o s o i o o i O ) i P '4 S M A M i i w 'j ® u i O ) g ) M a i u i w ( j i u u i f u o ) w w u N i N ^ O ( o M o a i-^ ^ ^ jM o o ^ o io jN j^ o jg jD jS jS j^ ^ ^ n c j^ c jjjjo ^ ^ ^ J ^ C R jo jo o o ^ o ij^ jk W o c s o to ^ o jj^ o i^ UUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUCJUUM o u G J M -» -» 0 > '■ 'I - * - * ®g)0)uK5om-‘Mg)uiUN!U'^2wuMA«^Mg!ft“!(,’^ ^ ^ ^ g j J “ 2®®tJmu! S o ^ o N O o i ^ ^ ^ a i a i ^ o i a j C T i - ' M — odoo^i-‘ b aijO 'g K )d i o u D 0 3 6 j io w to ^ g i o a ip 6 3 =i p r* p ^ t UUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUM % < ro'Niro-*--*coro-*ro-* A -^oitocD A -^-^corofooocooo _ _ . . cooia>a>^0}0 «sicj)uiO )-fcC O cnO '^K )io^oo f\3 -* ^ o cn to ro cn q» C O t O C O C O C O C O C O C O C O C O C O C O C O C O C O C O C J C O C O C O C O C O C O C O C O C O C O t O C O C O C O C O C O C O C O t O C O G O C O C O C O C O C O C O C O C O O J X , , . , i i ro . , , • , • «i i > , , , , -* a ^ o> ro -*cjtocn-±-*cJoi-* , -* ro co iv> -» ro -* -* ro-* , -*00-*, , a -* co ro a -* c o o o i ^ c n r o o o ^ A a ^ o o o r o ^ r a ^ ^ t o j g ^ c g o t o f o ^ ^ ^ ^ j ^ ^ c o j ^ ^ j ^ j M j O U i c n j O G D C D c n o o j N j ^ D c n ^ N i C O C O C O t O C O t O C O C O C O t O C O C O C O C O t O t O C O C O L O C O C O C O C O C O t O t O C O C O C O C O C O C O C O C O C O C O C O C O t O C O C O C O C O t O C O t O - * cn a <0 cn -* a . corocoQ>-*ro-*a>co-gcn-* . . , to . . . r o - * ro no . _ -* ■ ro A o> -* co cd -0 a r o o -* ro cn co coco 00 ^ ^ j g ^ o ^ ^ c o u i j ^ ^ j o r o ^ a j j ^ c j o t n j D ^ c n r o j ^ o ^ c o r o ro C O t O C O C O t O C O t O C O C O C O C O C O C O C O C O C O C O t O t O t O C O C O C O C O C O C O C O C O C O C O C O C O C O C O C O C O C O C O C O C O C O C O C O C O C O C O o Cl ) . ro ro to a ■ 'O to , -*oo , c j> — * ■ no — * — 1 co ro . , C n 'N lO C 0 (£ > A A C 0 C 0 '0 0 ) C 0 A (£>A '0 A , , , O i , , _k «* -*roco-*. ro -0 ro co . -* o o c n o o A c n ro c n - o - ^ n o r o o o o r o to r o o -* < * > 'N i o c o j £ j ^ j u j o c o j ;o a )co jx jD ^ A j= s j j ^ ^ c > j ~ g o c n r o c n _ _ _ _ _ _ _ _ _ _ _ (ococotocococococococococotooocotococococotococococococototocococococotococococococococococo o Table 3 : Temperature Factors for f C n R h ( C H ;,)(A t- C l) 2( C H 3) R h C n J (B R 4)2 Table 3: (continued) [ C n R h ( C H 3) (^ - C ! )2 (C H 3) R h C n ] ( 3 R 4)2 C 43 3Q( 3) 121(3) 94( 3) 0( 3) 7( 3) 19( 3 F 49 87( 3) 144( 3) 148( 3) -44( 3) -51(3) 45(3 F 50 82( 3) 104(3) 196( 3) •10( 3) -S( 3) -13(3 F 51 76< 3) 262( 3) 140( 3) -50( 3) 22( 3) 2 (3 C 52 108( 3) 129( 3) 39( 3) 13( 3) 16(3) -5(3 F 53 258( 3) 138( 3) 114(3) -58( 3) 37(3) -68( 3 F 54 177( 3) 232(3) 98( 3) -8( 3) 73( 3) -58(3 F 55 313( 3) 320( 3) 27( 3) 211(3) -29< 3) -20(3 C 56 104(3) 83( 3) 131(3) 15( 3) -61(3) • 25( 3 F 57 181(3) 18S( 3) 126( 3) 66( 3) -16( 3) 86( 3 F 58 83( 3) 576{ 3) 126( 3) -92( 3) •S3( 3) 142(3 F 58 367( 3) 194( 31 114( 3) 79( 3) -162( 3) •24( 3 C 60 57( 3) 68( 3) 79( 3) 2(3) -4( 3) 4{ 3 F 61 333(3) 60( 3) 149( 3) -38{ 3) -30( 3) -33(3 F 62 149{ 3) 121(3) 173( 3) -101(3) 76( 3) -74( 3 F 53 124f 3) 7 7 { 3) 23S( 3) 10( 3) 28(3) -61 ( 3 C 64 238( 3). 125( 3) 129( 3} 51(3) -103( 3) -86(3 C 65 126( 3) 79( 3) 211( 3) -27(3) -90( 3) -7(3 C 66 73( 3) 71 ( 31 178( 3) -24( 3) . -60( 3) -17( 3 C.67 ' 75( 3) 131(3) 319(3) -27(3) 7(3) S6( 3 c se 136( 3} 236(3) 47( 3) . - -72(3) -29(3) 37(3 C 69 111(3) 159( 3) 62( 3) -21(3) 19( 3) 36( 3 C 70 81(3) 252( 3) 104( 3) -96( 3) -40( 3) -48( 3 C 71 172( 3) 138{ 3) 179( 3) 49( 3) 107( 3) 105(3 C 72 227( 3) 84( 3) 158( 31 -72( 3) -28( 3) 17(3 The complete temperature factor is exp[-2jt2(U11h2a*2 + U22k2b*2 + Uggl2© ’2 + 2U12hka"b* + 2U13hla*c* + 2U23klbV] 11 0 0 0 O 0 O 0 O O O O 0 O O O O C O 1 0ro fo ro 1 0 ro ro ro ro ro ro ro ro ~ A 0 to 0 0 0 0 * * > 1o> 9 * f cp ro rp 9 0 f o 6 1 O 6 6 O 6 6 6 • O 1 O O 6 O O o C O C O a 1 0 ro C O ro C O ro ro C O ro £9 ro ro cn -* 0 E to 0 0 _& -si ro Ul * o> C O K 5cn _ i. ro to G O & O) -* a gi M O X O O lO G J M O ) <^6666666666666666 ow^ajo^^foooMoto^-^oai I X X X I X p o z z z o ro a> cn ^ co ^ w M (\3 w ro IN) ^.CO^^CO-U-^^GOCOUlCO^^CO^U^-^-OJCO-^CO^- r o . f r . o o i o c o . k r o i o o o o o c D - ^ r o t o o c o o - ^ t o c n o o o . U o o s o ^ o i u D u i N i r o N j o u i s m o Q o o o o s o o o ^ - ^ ^ooiO)A^wo>aio>o)ui^^^yiuicnf^^oMOOU -*tnN>a>ro-*Go.fc.ootn<o-*'vj'vioia>a>-*'k-vjo-*C)<oooco mMWOOOOJStDOQCONtDOlMNOl^ai^OS^OlO c o c o fo c o c o r o r o r o r o c o r o t o r o r o r o f o c o c o r o r o f o r o r o f o r o r o r o r o c o r o f u c o r o c o r o c o c o c o c o c o c o c o c o c o r - s c o r o r o - 1 ™ rofoM-*.ocx>'viroc»o-^to-si'vi'00--‘ OcototocD'-jKS'0'sjrocDOcnaiO'>io<o-uco^rooo-^a)K}^.Sooro-*oo^ K > Table 4 : Bond Distances(angstroms)for [ C n R h ( C H ,) ( M- C l) 2( C H 3) R h C n ] ( B R 4)2 [CnRh(CH3XAt-Cl)2(CHORhCn](BR4)2 Table 4: (continued) C 30—C 40 C 32—F 33 C 32—F 34 C.32—F 35 C 36—F 37 C 36—F 38 C 36—F 39 C 40—F 41 C 40—F 42 C 40—F 43 C 44—F 45 C 44— F 46 C 44—F 47 C 48—F 49 C 48—F 50 C 48—F 51 C 52—F 53 C 52—F 54 C 52—F 55 C 56—F 57 C 56—F 58 C 56—F 59 C 60—F 61 C 60— F 62 C 6 0 --F 63 C 64—C 65 C 66—C 67 C 68—C 69 1.507(25) 1.297(18) 1.297(19) 1.296(19) 1.296(17) 1.296(21) 1.296(20) 1.296(17) 1.296(22) 1.296(17) 1.297(26) 1.296(21) 1.296(21) 1.296(18) 1.296(17) 1.296(19) 1.296(20) 1.296(20) 1.296(19) 1.296(20) 1.296(21) 1.296(20) 1.297(18) 1.296(20) 1.297(17) 1.456(42) 1.440(40) 1.269(38) Table 5: Bond Angles (deg) for [C nR h(C H 0(/i-C l)2(C H 3)RhCnJ(BR4)2 CL 2-RH 1-N 3 97.6( 6) CL 2-RH 1-N 4 175.3( 6) N 3-RH 1-N 4 85.3( 8) CL 2-RH 1-N 5 102.0( 6) N 3-RH 1-N 5 83.3 ( 8) N 4-RH 1-N 5 81.9( 8) CL 2-RH 1-C 6 76.2(10) N 3-RH 1-C 6 88.6(12) N 4-RH 1-C 6 100.2(12) N 5-RH 1-C 6 171.4(11) RH 1 -N 3-C 65 105.5(14) RH 1 -N 3-C 66 107.1(14) C 65-N 3-C 66 114.6(21) RH 1-N 3-C 71 114.2(16) C65-N 3-C 71 108.6(20) C 66-N 3-C 71 107.0(19) RH 1 -N 4-C 64 105.6(15) RH 1-N 4-C 69 103.0(14) C64-N 4-C 69 104.8(20) RH 1-N 4-C 70 114.7(16) C64-N 4-C 70 113.2(22) C 69-N 4-C 70 114.5(21) RH 1-N 5-C 67 104.3(17) RH 1-N 5-C 68 108.9(16) C67-N 5-C 68 113.1(22) RH 1-N 5-C 72 119.8(17) C67-N 5-C 72 105.8(20) C 68-N 5-C 72 105.2(22) C 8-B 7-C 14 104.9(16) C 8-B 7-C 20 115.3(15) C 14-B 7-C 20 112.1(15) C 8-B 7-C 26 109.3(14) C 14-B 7-C 26 113.9(15) C 20-B 7-C 26 101.7(16) B 7-C 8-C 9 120.8(16) B 7-C 8-C 13 119.0(14) C 9-C 8-C 13 120.0(17) C 8-C 9-C 10 119.3(17) C 9-C 10-C 11 122.5(18) C 9-C 10-C 56 116.5(16) C 11-C 10-C 56 120.9(18) C 10-C 11-C 12 117.6(19) C 11-C 12-C 13 122.0(18) C 11-C 12-C 60 115.0(17) C 13-C 12-C 60 123.0(15) C 8-C 13-C 12 118.6(16) B 7-C 14-C 15 119.1(16) B 7-C 14-C 19 122.1(17) [CnRh(CH3)(M-CI)2(CH3)RhCn](BR4)2 Table 5: (continued) C 15-C 14-C 19 118.4(19) C 14-C 15-C 16 121.9(18) C 15-C 16-C 17 119.3(19) C 15-C 16-C 48 119.0(17) C 17-C 16-C 48 121.6(19) C 16-C 17-C 18 120.7(21) C 17-C 18-C 19 118.1(17) C 17-C 18-C 52 122.5(18) C 19-C 18-C 52 119.2(17) C 14-C 19-C 18 121.2(19) B 7-C20-C21 122.2(17) B 7-C 20-C 25 119.4(17) C 21-C 20-C 25 118.0(17) C 20-C 21-C 22 118.8(18) C 21-C 22-C 23 122.9(19) C 21-C 22-C 36 118.1(17) C 23-C 22-C 36 118.9(17) C 22-C 23-C 24 117.2(19) C 23-C 24-C 25 122.4(18) C 23-C 24-C 32 119.2(17) C 25-C 24-C 32 118.4(17) C 20-C 25-C 24 120.8(18) B 7-C 26-C 27 123.4(17) B 7-C 26-C 31 118.0(16) C 27-C 26-C 31 118.3(18) C 26-C 27-C 28 119.3(19) C 27-C 28-C 29 125.0(19). C 27-C 28-C 44 120.9(19) C 29-C 28-C 44 113.9(18) C 28-C 29-C 30 115.0(20) C 29-C 30-C31 125.7(21) C 29-C 30-C 40 116.9(19) C 31-C 30-C 40 117.3(18) C 26-C 31-C 30 116.5(19) C 24-C 32-F 33 113.3(13) C 24-C 32-F 34 115.3(15) F 33-C 32-F 34 104.5(13) C 24-C 32-F 35 113.5(13) F 33-C 32-F 35 104.5(13) F 34-C 32-F 35 104.5(15) C 22-C 36-F 37 117.9(12) C 22-C 36-F 38 115.0(14) F 37-C 36-F 38 104.5(13) C 22-C 36-F 39 109.1(13) F 37-C 36-F 39 104.5(12) F 38-C 36-F 39 104.5(13) C 30-C 40-F 41 114.7(13) C 30-C 40-F 42 114.5(15) F 41-C 40-F 42 104.5(13) C 30-C 40-F 43 112.9(14) [CnRh(CH 3)(/x-CI)2(CH 1)RhCn](BR4)2 Table 5: (continued) F 41-C 40-F 43 104.5(13) F 42-C 40-F 43 104.5(13) C 28-C 44-F 45 118.7(16) C 28-C 44-F 46 112.2(15) F45-C 44-F 46 104.5(16) C 28-C 44-F 47 111.2(16) F 45-C 44-F 47 104.5(15) F 46-C 44-F 47 104.5(17) C 16-C 48-F 49 113.1(14) C 16-C 48-F 50 114.7(12) F 49-C 48-F 50 104.5(12) C 16-C 48-F 51 114.4(13) F 49-C 48-F 51 104.5(12) F 50-C 48-F 51 104.5(13) C 18-C 52-F 53 116.8(13) C 18-C 52-F 54 114.1(14) F 53-C 52-F 54 104.5(14) C 18-C 52-F 55 111.2(13) F 53-C 52-F 55 104.5(14) F 54-C 52-F 55 104.5(12) C 10-C 56-F 57 115.5(14) C 10-C 56-F 58 109.9(14) F 57-C 56-F 58 104.5(15) C 10-C 56-F 59 116.6(14) F 57-C 56-F 59 104.5(13) F 58-C 56-F 59 104.5(15) C 12-C 60-F61 112.4(12) C 12-C 60-F 62 113.3(13) F 61-C 60-F 62 104.5(13) C 12-C 60-F 63 116.4(13) F 61-C 60-F 63 104.5(13) F 62-C 60-F 63 104.5(12) N 4-C 64-C 65 114.2(23) N 3-C 65-C 64 111.4(23) N 3-C66-C 67 122.7(22) N 5-C 67-C 66 112.2(22) N 5-C 68-C 69 115.2(26) N 4-C 69-C 68 122.2(23) 116 NhCnRhMe3 STRUCTURE DETERMINATION SUMMARY Crystal Data Empirical Formula Color; Habit Crystal size (mm) Crystal System Space Group Unit Cell Dimensions Volume Z Formula weight Density(calc.) Absorption Coefficient F(000) C27 H60 N3 Pale yellow prism 0.10 x 0.10 x 0.12 Hexagonal a - 12.418(1) A c - 11.585(1) A 1547.0(6) A 3 2 529.7 1.137 Mg/m3 0.568 mm ^ 576 D a t a C o l l e c t i o n N h C n R h M e 3 Diffractometer Used Radiation Temperature (K) Monochromator 26 Range Scan Type Scan Speed Scan Range (u) Background Measurement Standard Reflections Index Ranges Reflections Collected Independent Reflections Observed Reflections Absorption Correction Siemens P4/RA MoKa ( X - 0.7107 3 A) 295 Highly oriented graphite crystal 3.5 to 45.0° 9/29 Variable; 2.00 to 15.00°/min. in cj 0.50° Stationary crystal and stationary counter.at beginning and end of scan, each for 0.5Z of total scan time 3 measured - every 47 reflections -1 < h < 13, -13 < k < 1 - 1 < 1 <■ 12 2025 808 (R. - 7.06X) int 577 (F > 4 . 0er(F) ) N/A 118 S o l u t i o n a n d R e f i n e m e n t N h C n R h M e ^ System Used Solution Refinement Method Quantity Minimized Absolute Structure Extinction Correction Hydrogen Atoms Weighting Scheme Number of Parameters Refined Final R Indices (obs. data) R Indices (all data) Goodness—of—Fit Largest and Mean A/ a Data—to—Parameter Ratio Largest Difference Peak Largest Difference Hole Siemens SHELXTL PC (Version 4.2) Direct Methods Full—Matrix Least-Squares Iw(Fo-Fc)2 r > - 0.9(3) X - 0.00019(5), where ,F* - F [ 1 + O.OO2xF2/sin(20) : Riding model, fixed isotropic U w_1 - o2(F) + 0.0000F2 94 R - 2.83 Z, wR - 2.35 Z R - 4.74 Z, wR - 2.65 Z 1.03 0.008, 0.001 6 . 1:1 0.27 eA” 3 - 0 .2 1 eA"3 119 N h C n R h M e3 Table 1. Atomic coordinates (xlO ) and equivalent isotropic • 2 3 displacement coefficients (A xlO ) X y z U(eq) Rh 6667 3333 3859 49(1) N(l) 5261(5) 3191(5) 5148(5) 46(3) C(l) 5456(7) 1956(8) 2766(7) 77(6) C( 2) 4843(8) 1983(8) 5695(9) 81(6) C(3) 5782(8) 1678(7) 5989(8) 75(5) C(4) 4207(6) 3206(7) 4566(7) 62(4) C(5) 3078(7) 2947(8) 5282(7) 67(4) C(6) 2072(8) 3089(8) 4643(9) 64(5) C( 7) 2572(8) 4437(8) 4291(8) 98(6) C(8) 1005(8) 2707(10) 5470(9) 112(7) 0(9) 1623(9) 2273(9) 3586(10) 106(8) * Equivalent isotropic U defined as one third of the trace of the orthogonalized U.. tensor Table 2. Bond lengths (A) Rh-N(1) 2.236 (6) Rh-N(lA) 2.236 (7) Rh-C(lA) 2.054 (10) N(l)-C(2) .1.463 (11) N(1)-C(3A) 1.480 (11) C(3)-N(lA) 1.480 (11) C(5)-C(6) 1.536 (15) C(6)-C(8) 1. 507 (14) Rh-C(l) 2.054 (7) Rh-N(IB) 2.236 (6) Rh-C(IB) 2.054 (6) N(l)-C(4) 1.481 (11) C(2)-C(3) 1.435 (16) C(4)-C(5) 1.518 (12) C(6)-C(7) 1.522 (13) C(6)-C(9) 1.508 (14) 1 2 0 T a b l e 3. Bond a n g l e s ( ° ) N h C n R h M e3 N(l)-Rh-C(l) 97.4(3) N(l)-Rh-N(1A) 80.3(2) C(l)-Rh-N(lA) 96.3(3) N(l)-Rh-N(1B) 80.3(2) C(l)-Rh-N(IB) 176.1(3) N(1A)-Rh-N(IB) 80.3(2) N(l)-Rh-C(IA) 176.1(3) C(l)-Rh-C(IA) 86.0(3) N(1A)-Rh-C(lA) 97.4(3) N(1B)-Rh-C(lA) 96.3(2) N(l)-Rh-C(IB) 96.3(3) C(l)-Rh-C(IB) 86.0(4) N(1A)-Rh-C(IB) 176.1(3) N(IB)-Rh-C(IB) 97.4(3) C(1A)-Rh-C(IB) 86.0(3) Rh-N(l)-C(2) 103.5(6) Rh-N(l)-C(4) 110.8(5) C(2)-N(l)-C(4) 110.3(5) Rh-N(l)-C(3A) 108.2(4) C(2)-N(1)-C(3A) 111.2(6) C(4)-N(1)-C(3A) 112.4(6) N(l)-C(2)-C(3) 117.0(6) C(2)-C(3)-N(lA) 116.0(8) N(l)-C(4)-C(5) 118.5(7) C(4)-C(5)-C(6) 115.4(7) C(5)-C(6)-C(7) 110.4(6) C(5)-C(6)-C(8) 107.1(8) C(7)-C(6)-C(8) 109.1(10) C(S)-C(6)-C(9) 111.3(10) C(7)-C(6)-C(9) 109.4(8) C(8)-C(6)-C(9) 109.5(7) Table 4. Anisotropic displacement coefficients (A xlO ) uu U22 U33 U12 U13 U2 3 Rh ^8(1) 48(1) 52(1) 24(1) 0 0 N(l) 36(4) 37(4) 67(5) 20(3) -4(4) 0(4) C(l) 78(7) 101(8) 64(7) 53(7) 3(6) -3(6) C(2) 62(6) 62(7) 130(10) 39(6) 25(6) 30(7) C(3) 76(7) 74(6) 89(7) 48(6) 29(6) 28(6) C(4) 48(5) 77(5) 68(5) 38(4) 3(5) -2(5) C(5) 61(5) 63(5) 80(7) 33(4) 4(5) -1(6) C(6) 50(6) 84(7) 76(7) 47(6) -8(6) -7(6) C(7) 99(7) 115(7) 113(11) 78(6) -8(7) 8(7) C(8) 70(6) 162(10) 125(9) 73(7) -6(7) -2(9) C(9) 87(8) 137(9) 118(16) 73(7) -37(9) -34(10) The anisotropic displacement exponent takes the form: — 2 *^ (h^a*^U^ + ... + 2 hka*b*U^2 ) 121 NhCnRhMe3 Table 5. H—Atom coordinates (xlO ) and isotropic • 2 3 displacement coefficients (A xlO ) X y z U H(1A) 5902 1657 2316 80 H( IB) 5074 2280 2261 80 H( 1C) 4826 1284 3212 80 H(2A) 4405 1960 6390 80 H(2B) 4251 1360 5170 80 H(3A) 5418 788 6054 80 H(3B) 6159 2050 6712 80 H(4A) 4546 4035 4263 80 H(4B) 3955 2627 3935 80 H(5A) 2708 2092 5528 80 H(5B) 3348 3479 5940 80 H(7A) 2860 4959 4963 80 H(7B) 1922 4519 3929 80 H(7C) 3248 4684 3760 80 H(8A) 360 2787 5095 80 H(8B) 1287 3234 6139 80 H(8C) 688 1859 5702 80 H(9A) 2304 2514 3061 80 H(9B) 985 .2371 3216 80 H(9C) 1293 1419 3803 80 122 CHAPTER 2 Chemistry of H ard-Ligated Organorhodium Complexes in Protic Solvents Results and Discussion Transform ations of CnRh Species in Aqueous Phase As described in Chapter 1, CnRh complexes have well-defined chemistry in organic solvents. Since some of the CnRh organometallic complexes demonstrate unusual water and oxygen stability, the chemistry of the CnRh complexes in aqueous phase has thus been explored and the results are discussed in this chapter. When dissolved in water, complex 3 forms dihydrate [CnRhMe(H2 0 )2]2+, 13, the 'H NMR spectrum of which is shown in Figure 1.5. The degree of water solvation of 3 can be controlled by adding different quantities of water to a nitromethane solution of 3. When one equivalent of water (compared to 3) is added, the monoaqua solvated [CnRhMe(OTf)(H2 0 )]+, 14, can be cleanly generated and the coordinated water can be observed by *H NMR (Figure 1.6). Ether diffusion into the concentrated nitromethane solution of 14 resulted in formation of yellow single crystals of 14. Its structure has been confirmed by X-ray crystallography (Figure 2.1). The Rh-N bond that is trans to the methyl group is significantly longer (2 . 2 2 A ) than the Rh-N bonds that are trans to the triflate group and water (2.03, 2.05 A), consistent with the stronger trans-influence of the methyl group. Adding another equivalent of water to the nitromethane solution of 14 results in partial conversion from 14 to 13, and addition of a large excess of water causes complete conversion to 13 123 F 2 3 GFy 2 2 Figure 2.1 ORTEP diagram of the molecular structure of the cation part of [CnRhM e(0Tf)(H 2 0)]+0 T f“, 14 (structure solved by Roy Lu and Robert Bau). 124 i Figure 2.2 ORTEP diagram o f the molecular structure o f the cation part of j j [CnRhMe(H2 0 ) 2 ](0Tf)2, 13 (structure solved by Roy Lu and Robert Bau). (Figure 1.6). Adding ten equivalents of water to the nitromethane solution of 3 and letting the mixture stand in air resulted in the formation of yellow single crystals of 13, the structure of which has been confirmed by X-ray crystallography (Figure 2.2). The Rh-N bond that is trans to the methyl group is again significantly longer (2.21 A) than the Rh-N bonds that are trans to water (2.04 A). This again emphasizes the larger trans-influence of the methyl group. In aqueous solution, complex 13 was found to be a diprotic acid. It can be deprotonated twice by adjusting the pH of the solution with NaOH to form [CnRhMe(OH)(H2 0 )]+, 29, and CnRhMe(OH)2, 30, in turn, as shown in Figure 2.3. Cn Cn Cn I 2+ p K a-| = 8.6 I + pKa2 = 10.7 I Rh ► R l \ » Rh c h / I h2o c h 3 I h2o ~ c h 3 - | \ QH h2o oh oh (13) (29) (30) Figure 2.3 Transformation of Complexes 13, 29 and 30. Measurement of the pKa of 13 gave pKa, = 8 . 6 and pKa2 = 10.7. There are two ways of obtaining the pKa in this case. The first is to measure the pKaj by measuring the pH of the solution which contains equal concentrations of 13 and 29. For very weak acid, simply mixing with equal amount of its conjugated base won't change the fact that the concentrations of the acid and the base are 126 j equal. As pKa = pH - loglA'MHA]^ when [A“] = [HA], the measured pH is the pKa. By mixing the solutions of 13 and 29 (equal concentrations (0.01 M )) to make the final concentration to be 0.005 M for both of the two species and measuring the pH, the pKa! was found to be 8 .6 . Complex 30 has not yet been j isolated, but by adding half equivalent of NaOH to the solution of 29 directly generated the mixed solution of 29 and 30 in 1:1 ratio. Measuring the pH of the solution gave pKa2 = 10.7. The second way of obtaining pKas of 13, particularly pKa2 is by calculation. As for a very weak binary acid H2A, the sum of pKai and pKa2 equals 2 times of the pH of HA", this way, by knowing the the pKa! and the pH of the solution of 29, the pKa2 can be easily calculated out. 3 8 The pH of the 0.01 M solution of 29 is 9.66. The pKa! of 13 was known to be 8 .6 , then the pKa2 was calculated to be 10.7. Thus, two independent methods of measuring pKa2 gave the same result. The pKaj can also be ^ obtained by measuring the pH of the solution of 13 that was mixed with half I i equivalent of NaOH or the solution of 29 that was mixed with half equivalent of i j HC1. All essentially gave the same result. The basis of the calculation of pKa2 I of the weak binary acid is shown in Figure 2.4. j Based on the calculation from the pKa of 13 and 29, a 0.01 M aqueous 1 I J solution of 13 contains 1 0 " 3 -3 A/ 29, that is, only 0.05% of 13 will deprotonate in 0.01 M aqueous solution to form 29 and liberate proton. The 0.01 M aqueous ! solution of 29 contains 2% 13 based on calculation. Note that the concentration I of water is not counted in the pKa and pKb terms here, although water is : involved in the [CnRhMe(OH)(H2 0 )]+ + H20 [CnRhMe(H2 0 ) 2]2+ + OH" i equilibrium. Calculation indicates that 0 . 0 1 M aqueous solution of 30 (mixing J i 127 ; For the solution of HA", the following equilibria exist: [HA"][H+] H2 A =*= HA" + H+ Ki " [H2A] HA" — A2- + H+ k 2 = ^ [ A 2 ~ 3 2 [HA’] [A2 "] = [H+] - [H2A] 2 = K]K2 [HA~] K r + [HA-] As [HA"] » Ki So [H+ ] 2 = K lK2 (0.01 M ) ( 1 0 [H+ ] = / ^ K 2 pKai + pKa2 pH = .... ^ ........ pKa2 = 2pH - pKar Figure 2.4 Relationship of the pKa2 o f H2 A with the pH of HA". an aqueous solution of 29 with leq of OH" to make 0.01 M solution o f 30, is equivalent to directly dissolving 30 in water to make the 0.01 M solution) contains 20% 29 simply because the pKbj of 30 is relatively small. By adjusting the pH of the solution of 30 (0.01 M ) to be 12, the content of 29 is reduced to 4.8%. That is, at pH > 12, the 0.01 M aqueous solution of 30 will contain less than 5% of 29 out of the total concentration of rhodium complexes. Adding 5eq of OH" to 0.0 IM aqueous solution of 30 (or add 6 eq of OH" to 0.01 M aqueous solution of 29) reduces the content of 29 to 0.8%, that is, less i 128 ! than 1% of the total concentration of the rhodium species. The measured pH's of the 0.01 M aqueous solution of 13, 29 and 30 (pH 6.0, 9.7 and 11.7, respectively) are some what off from the calculated pH of 13, 29 and 30 (pH 5.3, 10.3 and 11.4, respectively), repeated measurements gave almost the same result. As water dissociation is unlikely to cause the differences of the measured and calculated pH's to be bigger than 0.3 unit for the 0.01 M solutions, the differences of calculated and measured pHs might came from error in measurement of small amount of sample (e.g. weight of CnRh, volume of water, volume of NaOH, etc.). The aqueous phase transformation of 13, 29 and 30 can be clearly followed by *H NMR. The ]H NMR spectrum in D20 (referenced to DSS, Me3Si(CH2 )3S0 3Na) changes continuously with the acidity of the solution (5 13, 1.78; 29, 1.51; 30, 1.21 ppm) with limiting shifts for 13 and 30 (Figure 2.5). Adding leq of NaOH to the solution of 13 moved the Rh-CH3 absorption from 1.78 ppm to near 1.50 ppm, indicative of the formation of 29. Adding another equivalent of NaOH shifts the Rh-CH3 absorption to 1.23 ppm with the distinct coupling of ca. 2 Hz. This absorption peak is the averaged Rh-CH3 peak of 80% 30 and 20% 29 (based on calculation). As proton transfer (e.g. protonation of Rh-OH) in aqueous solution is faster than NMR time scale, only one Rh-CH3 peak can be observed as a result of averaging. Adding another 2eq of NaOH shifts the Rh-CH3 absorption to 1.21 ppm with no additional shift upon adding more NaOH. Adding acid solution to the solution of 30 resulted in the transformation from 30 to 29 and then 13, with the limiting Rh-CH3 chemical shift of 1.78 ppm for 13 as indicated by ]H NMR. 129 The transformation of 13, 29 and 30 can also be followed by UV-Visible spectra. Complex 13 has a distinct X m ax at 269.5 nm while 29 and 30 have no distinct Amax. But the transformation can still be clearly followed by observing the shape of the absorption peaks of different species. There have been many reports about the water coordinated 18e organometallic complexes. 3 9 The coordination chemistry of aqua ions have been extensively studied.4 0 -41 It was found that all aqua ions are more or less acidic.41 The acidity of solvated cations can be ascribed to the influence of the positive charge on the metal ion facilitating the loss of a water proton.4 2 The acidity is in general charge dependent, with 4+ cations often more acidic than 3+ , 3+ generally more acidic than 2+, and 1+ often so weakly acidic that their pKas verge on the immeasurable 4 2 As for the relative size of pKaj and pKa2, for some series the pKa2 were found to be 1 to 2 units higher than the pKa^ 4 2 The pKas of aqua ions span a very wide range. In D2 0 , the pKas were found to be 0.1 to 0.5 unit bigger than the corresponding pKas in H2 0 .4 2 CnRhMe2 OTf, 2, forms the water solvated complex [CnRhMe2 (H2 0 )]+, 31, immediately once dissolved in water NMR spectra are the same for OTf" and BF4"). Dissolution of 2 in D20 at 24 °C results in evolution of one equivalent of CH3D (both JH and 1 3 C NMR show only this isotopomer) with a pseudo first-order rate constant k = 3.80 (0.08) x 10“ 5 s- 1 (Figure 2.6) and yields 29-D directly. Removal of the water solvent under vacuum, instead of forming the salt of 29, leads to the isolation of CnRhMe(OH)(OTf), 32, which has been fully characterized by and 1 3 C NMR, as well as elemental analysis. O f course once 32 is dissolved in water, it forms [CnRhMe(OH)(H2 0 ))+, 29, 130 C n 5 1.78 2+ C H C n 5 1.51 C H : 5 1.21 C n R h C H ; PPM Figure 2.5 NMR spectra of aqueous phase transformation o f 13, 29 and 30, with DSS ((CH3)3Si(CH2)3S0 3Na) as reference. 131 [Rh]0 = 0.022 M 0.9- 0 .8- 0.7- o 0.6 - 0.5- 0.4- 0.3- 0.2 - 0.1 341 2665 4989 7312 9636 11960 14284 16608 18931 21255 1503 3827 6150 8474 10798 13122 15446 17770 20093 22417 t(s) Figure 2.6 Kinetic plot of the protonolysis of 2 in D20 at 24 °C. I immediately. The full aqueous phase transformation scheme o f species 2, 3, 13, 29, 30 and 31 is shown in Figure 2.7. Complex 29 is very stable in water at room temperature. At 50 °C, heating the D20 solution o f 29 evolves the second equivalent of CH3D in a cleanly pseudofirst-order reaction with kobsd = 4.08 (0.15) x 10" 7 s" 1 (Figure 2.8). The resulting intermediate, A, presumably [CnRh(OD)2 (OD2)]+, slowly i i ! ' forms a final product, B, the structure of which is as yet uncertain (Figure 2.8). | Slow evaporation of the water solution of B resulted in formation of light CH, CH 'i Cn Rh (3) OTf Cn Rh 'I \ ^ 3 C H , OTf (2) H00 CH, H 2 O Cn 1 2+ h pKa1 = 8 .6 \ -- H20 --------- H 2 O (13) Cn Rh CH-s \ c h 3 (31) H 2 0 CH Cn Rh> 3 I H ,0 OH (29) CH-i pKa2 = 10.7 Cn Rh | > OH \ OH (30) Figure 2.7 Transformation scheme of 2 ,3 ,1 3 , 29,30 and 31. yellow crystals of B. X-ray diffraction data of B reveals that the crystals of B so far have been twinned. The structure of B may be [CnRh(OH)-p- (OH)2 Rh(OH)Cn] + 2 (ion exchange chromatography on Sephadex-SP C-25 resin suggests that B bears +2 charge while A bears +1 charge), but in any event, it is clear from UV-visible spectra that it is not the dimer [CnRh(p-OH)3RhCn] + 3 reported by Wieghardt.7 Complex B has only one at 343 nm and it is sensitive to acid (adding of acid to the solution of B resulted the shifting of the ) while [CnRh(p-OH)3RhCn] + 3 has two A m ax (332 and 396 nm) and it is not acid sensitive. With 0.2 M N aC l and 0.01 M NaOH aqueous solution as the 133 1.8 1.6- 1.4- 1.2 - 5 s z o c c: O c 0 .8- l 0.6- 0.4- 0.2- 2 2.5 Time (sec) 0.5 (M illions) Figure 2.8 Kinetic plot of protonolysis o f 29 in D20 at 50 °C. eluant, complex A and B can be clearly separated out by Sephadex-SP C-25 resin. The light yellow band of A moves faster than the yellow band of B. Unlike complex B, A has no distinct X ^x in UV-visible spectrum. C H - Cn I . R h / I x 50°C OD (29)-D OD. D20 -ch3d Cn I + R h ] 0 0 OD o d 2 (A)-D D OD O^ I 2 + [ CnRh ^RhCn ] 0 0 8 ^ (B)-D ? Figure 2.9 Thermolysis o f 29-D at 50 °C. 134 [CnRhMe(H2 0 )2]2+, 13 and CnRhMe(OH)2, 30 are much more stable than 29. At pH = 2 at 50 °C, 13 (0.01 M ) is unchanged in D20 solution after a month. Dihydroxo complex 30 (0.01 M)is also unchanged in D20 (pH = 13) at 50 °C after a month. Complex 13 decomposes very slowly at 80 °C in D20 at pH 6.0 with the half life of 36 days and cleanly generates one species with at 343.3 nm in UV-visible spectrum. The !H NMR spectrum of this species is different from that of complex A and B (See Experimental). Coordination Polymerization of Ethylene in Aqueous Phase As complex 3 and 5 have shown fascinating chemistry of coordination polymerization of ethylene in organic solvents, their related organorhodium species have been tested for the possibility of catalyzing ethylene polymerization in aqueous phase although there was no previous example of aqueous phase coordination polymerization of ethylene by catalysts based on any metal.4 3 Under ethylene pressure of from 15 to 60 atmospheres at 24 °C, complex 29 in water slowly generates polyethylene. An oligomer suspension is first visible after 15 days at 40 atm of ethylene. Propylene did not react with 29 in water. Methyl acrylate and methyl methacrylate compete with water to coordinate to the rhodium center of 29, but in neither of these two cases was the insertion of the C=C bond into the Rh-CH3 bond observed. Monitoring the reaction of [CnRh(i3CH3 )(0H)(H 2 0)](0T f), 29-i3 C, with ethylene by 1 3C{]H}NMR clearly shows resonances of the growing oligomer Rh(CH2 CH2 )n(1 3CH3 ) with the largest resonance ultimately at the chemical shift 135 | o f the terminal methyl group in a long alkane chain (5 16.2 ppm in D20 : i referenced to DSS). At the early stage of the polymerization reaction, the first | newly appeared peak at 18.6 ppm (DSS as reference) is clearly due to the first insertion, that is, RhCH2 CH2 1 3CH3 (Figure 2.10A). The peaks at 16.4 and 16.5 ? ppm may due to the second and the third insertion as they appeared after the j j appearance of the 18.6 ppm peak and before the appearance of the 16.2 ppm I peak (Figure 2.10A). Using catalyst 29 (0.022 M in H2 0)at 24 °C and constant ethylene | pressure of 60 atm, after 90 days the product is low molecular weight i polyethylene with Mw = 5,100 and polydispersity index of 1.6 (GPC). The j average turnover number for this sample was ca. one per day. The infrared j! | spectrum of this polyethylene sample showed no detectable branching, | consistent with the coordination polymerization nature of this system. An i interesting observation is that the polymerization reaction is much faster if j j : CnRhMe2 OTf, 2 is directly used than if 29 is used. Complex 2 was known to I ! | undergo protonolysis in D20 at 24 °C to generate 29 with a half life of 5.1 h, | that is, in 25.5 h, 97% of 2 will be transformed to 29. Using 2 (0.022 M in \ H2 0 ) under 16 atm of ethylene in a sealed glass tube (pressure decreases during \ | the reaction), after 80 days the product is low molecular weight polyethylene ! with Mw = 6,150 and the polydispersity index of 1.6. If the reaction rate is first I : order to [C2H4], then complex 2 polymerizes ethylene at a rate of at least five fold of the rate of 29. ]H NMR spectra also reveal that in D20 under ethylene j i ' pressure, the solution of complex 2 initiates the ethylene insertion reaction | much faster than the solution of 29 (or 32). The CH2 peak of the oligomer 136 t = 40 days I T - 1 . . J liL . A Jik L.i» » . ij t = 9 days vL lA JiM V W itA t-j-juJV ^^ hiWjkjul/ ViuejUUAiuLu^Jkti t = 34 h A i M t J . t H 0 T Y K ujjJuaj r r ^ 1 - * r i i l A A m f l r f J M A Ahkn iilk ll 1 f t l ’ ijw A j^vi*L 1 ALuJ L- t= I h J 1 | . [ ~ 18 16 1 1 r 14 i f — i — r B 6 PPM 12 10 Figure 2 .10A 13C{1H} spectra of the reaction of 29-1 3 C and ethylene-1 2 C (15 atm) in D20 at 24 °C (reference to DSS). Only part o f the spectrum is shown. 137 chain on rhodium (] H NMR) grows much faster for the solution of 2 than the solution of 29. Also polymer precipitates came out from the solution of 2 much faster than from the solution of 29. The possible reason for this is discussed below. At 50 °C, by using the Si-CH3 group of DSS as the internal standard, the disappearance of the Rh(13CH3) 1 3 C NMR resonance of 29-1 3 C (0.044 M) in the presence o f ethylene follows the rate law kobsd[29][C2H4] (Figure 2.10), consistent with reversible dissociation of water from 29 followed by rate- determining ethylene uptake (Figure 2.1 1 ). The pressures (7, 14, 33 atm) are 2.5- I c __i 33 atm 7atm 14atm 1.5- 0.5- 300 350 1 0 0 200 2 5 0 Figure 2 .1 0 B Kinetic plot of ethylene polymerization by 29-1 3 C in D20 at 50 °C at different ethylene pressure. 138 the starting pressures at room temperature. Good linear plots were obtained over ca. 4 half-lives. Ethylene concentration in D20 was determined by ]H NMR integration of the sample equilibrated to 22 °C by reference to DSS. Since NM R spectra were taken at 22 °C, the ethylene concentrations at 50 °C are not known. The rate constants are reported for each 22 °C-measured [C2 H4] as k = kobsd[C2 H4]: 0.0070 M, k = 7.59 (0.10) x 1 0 - 6 s-i; 0.020 M, k = 2.19(0.02) X 10-5 s-i; 0.036 M, k = 4.34 (0.05) x 10-5 s-i It was known that 29 slowly undergoes protonolysis in D20 at 50°C with kobsd = 4.08 (0.15) X lO-'V1. This means that even at 0.007 M [C2 H4] (7 atm), the protonolysis rate of 29 only counts 5% of the overall rate of the disappearance of 29, implying that the Cn Cn Cn I + ki I + k2[=] I + R h ► R h R h 13c h 3 - I d" o d 2 ^ O ] 13c h 3 - I d d 2o / (Idv ^ CH3 (29-1 3 G-D) (I) (P) (I) can not be observed in the reaction process, therefore: ki[29] k,[29] = k .lC D2 0]P] + k2[=][I] [I]= As k .1[D2 0 ] » k 2[=], |TJ= k ‘p 9 ] * k _ i[D 20 ] 1 J Figure 2.11 Mechanism and rate expression of the reaction between 29 and C2H4. 139 d I I olefin insertion path is dominant. The replacement of aqua ions by incoming I !i ] ligands (e.g. C2H4) can go through dissociative or associative pathways, and in < principle the two paths can give the same kinetic expression. 4 4 In the case of ! I ; the reaction between complex 29 and ethylene, we believe the water dissociation path is more reasonable. Consideration about the lone pair effect ; | of the hydroxyl ligand of 29 and further information about complexes 13 and 30 ! j given in later in this chapter all support the dissociative mechanism. One I possible reason that the aqueous solution of 2 polymerizes ethylene much faster ! '! than 29 is that in the protonolysis of 2, the active intermediate (I) which is j j j i crucial for the initiation of the polymerization reaction is generated directly. j i i ° ! The rate of protonolysis , kp, also the concentration of complex 31 (or 2) both ! !■ !l ; ; i i I involved in the kinetic expression (Figure 2.12). Their contribution (kp[31] i term) to the rate expression should result faster initiation (at the time when 2 is ; present, tl/2 = 5.1 h) and facilitate the overall polymerization reaction. The 1 H NM R spectrum of the reaction of 31 with 15 atm of ethylene in D20 after 40 ' days is essentially the same as the spectrum of the reaction of 29 with 15 atm of ; ethylene in D20 after 24 days, suggesting that these reactions very likely go j through the same path, that is, through intermediate (I). There are no j observable rhodium allyl species and propylene in both of the two reactions as ! indicated by ]H NMR. As some quantitative information (e.g. kp at 50 °C) is j still lacking, more work need to be done to fully understand this system. For instance, whether 31 reacts with ethylene in water to undergo ethylene insertion reaction to destroy the catalyst precursor or not is not clear at this point. To measure the rate of the disappearance of 31 at 24 °C under ethylene pressure | | 140 ! and to compare this rate with the rate of protonolysis of 31 at 24 °C can easily solve the puzzle. Cn Cn I ^ i + Rh D2 0 R tL / I <■-. - 3 I OD CH 3 2 (2) (31) kp j -CH3 D Cn Cn Cn + + k2t=] I + Rh ► Rh ► Rh ' 1 ^ o d 2 r o o i CH3 1 D c / I ^ C H OD k.-iL^O] OD ° 2° o d 3 (29) (I) (P) (I) can not be observed in the reaction process, therefore: kp[31]+ ki[29] kp[31 J + k,[29] = k_,[D2 0][l] + k2[=]P] [I] = + kj =] As k.1 p 2 0 ] » k 2[=], [I]= -kP[311 + k|[29] k -lP 2 °] m = k2[=m = k2[=](kp[31] + ^[29]) * k .,p 2 o] Figure 2.12 Mechanism and rate expression o f the reaction of 2 and C2H4 . The rate of reaction of 29 with ethylene is very pH dependent: at pH < 6 at room temperature (13 present) and pH > 1 2 (30 present) there is no reaction. 141 By mixing 29 with 1 eq of NaOH in D2 0 , this solution was found to polymerize ethylene much slower than the solution of 29 since the former solution only contains 20% of 29. To make sure that the solution of 30 contains less than 5% of 29, the pH of the solution was adjusted to 12 or higher. Although only 29 is an active catalyst while 13 and 30 are both inactive at room temperature, 13 does effect polymerization at 50 °C, but much slowly than does 29 at this temperature. The kinetic plot of 13-catalyzed ethylene polymerization at 50 °C in D20 at pH = 2 is shown in Figure 2.13. By using the residual HOD in D20 as the internal standard, the rate of disappearance of 13’s Rh-CH 3 absorption (corresponding to the first insertion) was followed by !H NMR. The rate expression was found to be cleanly pseudo first order in [13] with the rate constant k = 1.24 x 1 0 - 6 s’ 1 with the 22 °C-measured [C2H4] to be 0.011M ([C2 H4] is again unknown at 50 °C). Although the kinetic order of the reaction with respect to ethylene was not determined in this case, it is also very likely to be first order. If this were true, then at 50 °C complex 13 affects the first ethylene insertion reaction 10 fold more slowly than does 29 at this temperature (for 13, k = 1.24 x 10" 6 s" 1 with 22 °C-measured [C2H4] = 0.011M while for 29, k = 2.19 X 10- 5 s" 1 with 22 °C-measured [C2H4] = 0.020 M). Note that the presence of a large amount of DSS in D20 seems to enhance the solubility of ethylene. At 50 °C under 2 0 atm of ethylene, the methyl group of 29 is consumed and the NMR clearly shows formation of alkane, but no precipitate forms (even the reaction mixture was cooled to room temperature), so the products of the reaction are small oligomers with molecular weight lower than ca. 700 (the precipitates in the early stage of ethylene polymerization by 29 in D20 at 142 [Rh] 0 - 0.069M, [=]average = 0.0091 M a t 21 °C (15 atm at 21 °C) -0.3; -0.4- -0.5- 'o’ -0.6- 5 -0 .7 - -0 .8- -0.9- 0.2 0.8 time(S) (Millions) Figure 2.13 Kinetic plot of the reaction of 13 and ethylene at 50 °C in D20 at pH = 2. room temperature were found to have Mw = 690). Apparently, at the higher temperature protonolysis o f the Rh-C bond in the monocation, [CnRh(OH)(OH 2 )R]+, competes more effectively with chain propagation. This is not surprising since 29 itself was known to be stable at room temperature but slowly undergoes protonolysis at 50 °C with kobsd = 4.08 (0.15) X 10" 7 s_1. On j the other hand, [CnRhMe(H 2 0 )2]2+ is very stable at 50 °C, and so its alkyl j analogs, [CnRh(OH 2)2 R]2+, do not undergo appreciable protonolysis to | terminate the polymerization reaction. Therefore, at 50 °C, unlike 29, the ! | ■ l | thermostability of [CnRh(OH2 )2R]2+ complexes allows 13 to be the ethylene | | j polymerization catalyst at this temperature. Complex 32, CnRhMe(OH)(OTf), can also serve as a catalyst precursor for ethylene polymerization in acetone and CH2 C12, all much faster than in water. Under 15 atm ethylene pressure, precipitation of polyethylene from the CH2 C12 solution of 32 (0.01 M ) begins in several hours and from acetone solution of 32 (0.04 M ) in ca. a day. In acetone-^ the observed pseudo-first- order rate constant for the disappearance of the methyl group of 32 (by !H NMR) is kobsd = 8.82 (0.04) X 10" 6 s" 1 at 22 °C under 15 atm of ethylene (Figure 2.14). The kinetic order of the reaction with respect to ethylene was not determined in acetone. By treating the 0.01 M CH2 C12 solution of 32 with 15 atm of ethylene in a sealed 9 mm glass tube for a few weeks (it probably does not need to be this long), the polyethylene product (m.p. 128-131 °C) had Mw of 16,200 and a polydispersity index of 2.9, with no detectable branching in its infrared spectrum. The much faster ethylene polymerization rates of 32 in these less coordinating solvents clearly demonstrate that the very unfavorable water dissociation preequilibrium is the single factor that makes the 29 (or 32) catalyzed ethylene polymerization reaction in aqueous phase so inefficient. The key to the reactivity of 29, compared to 13 and 30, lies in three factors: the single positive charge of 29 allows easier ligand dissociation than from dication 13; the good leaving group water (compare to OH") is not present in 30; and leaving of water from 29 is facilitated by ^-donation of the lone pairs of the hydroxyl ligand. 4 5 4 6 Probably, neither 13 nor 30 becomes unsaturated at a significant rate at room temperature. It was found that [CnRhMe2 (H2 0 )]+, 31, undergoes hydrolysis of its methyl group with t 1 /2 of 5 . 1 h at 24 °C, and [CnRhMe(H2 0)(OH)]+, 29, also 144 [Rh]0 = 0.043 M, M a v e r a g e = 0.157 h i -0.5- - 1 - -1.5- -3- -3.5- -4- -4.5 20 40 60 t (hr) 80 120 Figure 2.14 Kinetic plot of the reaction of 32 and ethylene in acetone-d6 at 22°C. experiences hydrolysis of its methyl group with t 1 /2 of 20 days at 50 °C, while CnRhMe(H 2 0 )2]2+, 13, and CnRhMe(OH)2, 30, are very stable at 50 °C in D 2 0 . It is possible that the basicity of the rhodium methyl group and the acidity of the aqueous solution both play a certain role in the protonolysis of the rhodium methyl group for these aqueous organorhodium species. The rhodium methyls of 31 are certainly more basic than that o f 29 (a hydroxyl group is more electron withdrawing than a methyl group), and even more so than that of 13 in which case rhodium is dicharged. Coordination of water in complex 31 certainly increases its acidity and consequently effects the protonolysis of the methyl group on rhodium. In CnRhMe(OH)2, 30, the rhodium methyl might be similar 145 or even more basic than that of 31 (Chapter 3), but the extremely low proton concentration in the aqueous solution of 30 (its environment is very basic) might be the reason why 30 does not undergo protonolysis at 50 °C at a noticeable rate. The stability of 13 even in acidic (pH = 2) aqueous solution at 50 °C might due to the fact that 13 is dicharged, causing the rhodium methyl to be less nucleophilic than that of 31 and 29. An extreme example of the lack of nucleophilicity of the metal alkyl species is Bercaw's [PtCl5R]2" (R = CH3, CH 2 CH2 OH) complexes. 4 7 Due to the high oxidation state of the metal (PtIV ), the alkyl on platinum becomes so electrophilic that it undergoes SN2 nucleophilic attack by H20 and Cl" in aqueous phase to generate a mixture of the corresponding alcohol and alkyl chloride. Therefore, if the protolytic stabilities of 13, 29 and 30 are effected by both the basicity of the rhodium methyls and the acidity of the aqueous solution, or the coordinated aquo ligand, that is , low basicity of the rhodium methyls can enhance their stability while high acidity of the aqueous solution can facilitate the protonolysis of the methyls on Rh, then 29 appears to be right at the intersection of the two trends. X-ray photoelectron spectroscopy of the CnRh complexes (Chapter 3 of this thesis) reveals the following trend in electron richness of the rhodium center: CnRhMe(OH)2, 30 > CnRhMe2 OTf, 2 > CnRhMe(OH)(OTf), 32 > CnRhMe(OTf)2, 3 with the binding energies of Rh(3d5/2) at 307.7*, 308.2, 308.6 and 309.4 eV, respectively. This should mean that the basicity of the rhodium methyls of these complexes would likely to follow the trend of 2 > 32 > 3. This trend is consistent with the fact that the aqueous solution of 2 (31) undergoes protonolysis much faster than the solution of 32 (29) and the solution * Extrapolated value (see Chepter 3). 146 of 3 (13) does not experience protonolysis at 50 °C due to the low basicity of the rhodium methyl. Reaction of CnRh Com plexes W ith Ethylene in M ethanol As complexes 2, 3 and 32 have well defined chemistry in aqueous phase, their chemistry in another protic solvent — methanol has also been studied. Complex 2 dissolves in methanol forming a species believed to be the solvate [CnRhMe2 (HOMe)]+, 33, since the !H NMR is identical with OTf" or BF4" counterion. In methanol-c/ 4 33 reacts with ethylene over several hours at room temperature to form the allyl hydride [CnRh(r|3-allyl)(H)]+, 20, and one equivalent of CH4 (no CH 3D) (Figure 2.15). Complex 2 0 can not be isolated, and in 24 h in m ethanol-^ it undergoes complete solvolysis with the liberation of propene-fi^ and eventually leads to the formation of a mixture of two rhodium hydride products, the structures of which are as yet uncertain. The generation of propene from the reaction of 33 with ethylene again reveals that the transformation between 19 and 20 is reversible, this time at room temperature (the 19 = 5^ 2 0 transformation inferred from NMR data in CD2 C12 at -15 °C1 4 ). The liberation of propene-<s? 0 in methanol-<i4 establishes that there is no deuteron-hydride exchange beteen 2 0 and methanol-d^ solvent. Complex CnRhMe(OTf)2, 3 in methanol at room temperature forms a solution of ca. 20% of a chiral species (8 RhC/ / 3 =1.83 ppm), presumably [CnRhMe(HOMe)(OTf)]+, and 80% of an achiral species (8 RhCH3 = 1.99 ppm) which should be unionized 3, since its chemical shift is substantially different 147 N _ N Rh CH c h 3 33 OTf / ^ S T 5 ^ N N . ^ < ! / ^ Rh + C H ^ A N X ^ ' 18 CH, / ^ S 7 N \ " < \ / ^ Rh + (so iv )^ 19 c h 2 = c h 2 CD3OD, RT fast Propene-<i( Slow / ? S 7 ^ .N N, " < » / Rh + , / i ' CHf £ h 3 / 16 / ? S 7 * \ \ < » / Rh + / i N / CH3 x £ c h 2 - c h 2 (solv) 17 -N n N> < » / Rh + CH, H 20 "Rh-H" products Figure 2.15 Scheme of the reaction between 33 and ethylene in m ethanol-^. 148 for OTf" and BF4". Complex CnRhMe(BF4)2, 5 in methanol at room temperature forms a solution of ca. 60% of [CnRhMe(HOMe)(BF4)]+ (8 RI1C/ / 3 = 1.73 ppm) and 40% of unionized 5 (5RhC/ / 3 =1.82 ppm), the assignment for 5 is based on the assumption that solvation shifts the Rh-C/ / 3 resonance upfield (this trend has been found to be a general rule for the CnRh system). These results again demonstrate that BF4" has slightly less coordinating ability than OTf". The rhodium species in the methanol solution of 3 are so stable that they remain unchanged after 43 days at 50 °C. Complex 3 can affect ethylene polymerization in methanol at a rate that is comparable to 3 in THF and acetone but slower than 3 in CH2 C1 2 and CH 3N 0 2. By reacting 3 (0.005 M) with 15 atm of ethylene in methanol in a sealed 9 mm glass tube with agitation for a few weeks, the polyethylene (m.p. 126-131 °C) obtained has Mw of 12,700 and polydispersity of 2.4. By using the residue CD3OH in methanol-<i4 as the internal standard and following the disappearence of the two Rh-CH 3 peaks by NMR, it was found that at 20 °C under 4 and 15 atm of ethylene complex 3 in m ethanol-^ exhibits rates of disappearance of its methyl group that conform to the expression kobsd[Rh][C2H4], where the second-order constant is 7.2 X 10" 6 M- 1s- 1 (Figure 2.16). When CnRhMe(OH)(OTf), 32 dissolves in methanol, if [32]0 < 0.05 M, there is only one major species present as shown by !H NMR. This species is presumably [CnRhMe(OMe)(solv)]+, 34, resulting from the rapid OH" and CH 30" exchange and solvation. Although there are three distinct sharp peaks in the ligand region that may lead to the conclusion that it is a chiral molecule, the 149 2:1:1 integral ratio seems to argue against it. A fast 1 3 C NMR spectrum of 32's methanol solution would be helpful to further confirm the above conclusion (prolonged solution in methanol results in the slow decomposition which leads to deterioration of the spectrum). When a more concentrated solution of 32 is made ([32]0 > 0.1M), besides 34, another major species is also observed by NMR, indicating that either it is unionized CnRhMe(OMe)(OTf) due to higher [OTf-] or [CnRhMe(OH)(solv)]+ due to the higher [OH-] in the solution of 32. Therefore, to make the solution of mostly 34, a relative dilute solution ([32]0 < 0.05 M) is necessary. There are also a few minor "CnRhMe" species present at both low and high rhodium concentrations, judging from the rhodium coupled methyl resonances in NMR spectrum. CnRhMe(OH)(OTf), 32, in methanol, oligomerizes ethylene much faster than 32 in water, and slightly faster than 32 in acetone (all at 15 atm of ethylene). The reason why 32 in methanol can only oligomerize ethylene instead of polymerize ethylene is that 32 was found to slowly decompose in methanol solution and thus is presumably also true for its alkyl analogs. The instability of 32 in methanol is discussed later in this chapter. Generation of Rhodium M ethyl H ydride Species in M ethanol When dissolved in methanol, CnRhMe2 OTf, 2 forms the solvate [CnRhMe2 (HOMe)]+, 33, immediately. Complex 33 was found to slowly decompose in methanol (at a rate that is much slower than 33 reacts with ethylene to form the allyl hydride product). Evolution of methane from 33 is several times slower than from aquo complex [CnRhMe2 (H2 0 )]+, 31, in water. 150 [Rh]0 - 0.074 M, [~]a V erage = 0.049 M (4 atm) 2 .7 - 2.& 2.5 2.4- If 2.2 2 . 1- 2.5 0.5 time(S) (Millions) time(S) Figure 2.16 Kinetic plot of reaction o f 3 and ethylene in m ethanol-^ at 20 °C. However, unlike [CnRhMe(OH)(H 2 0 )]+, 29, which is relatively stable in water, the presumed intermediate [CnRhMe(OMe)(solv)]+, 34, in methanol undergoes loss of the second methyl group at about the same rate as the first is lost from 33. At 50 °C loss of both methyl groups from 33 occurs within 6-7 hours, j When CD3OD is used as solvent, the methanes formed are mostly CH3 D with a | small amount of CH2 D 2 as a significant but minor product. With CH3OD I solvent, the methane is 50% CH4 and 50% CH 3D. This result clearly rules out ! ! path A in Figure 2.17 in which case double protonolysis of 33 would result in ; the formation of CH3 D only. The result indicates that the first equivalent of methane arises from protonolysis of 33 by the solvent, while the second comes about by P-H elimination from the methoxide ligand of 34 followed by reductive elimination of methane (path B in Figure 2.17). There are two rhodium hydride complexes formed as the final products which are the same as from the reaction of 2 and ethylene in methanol. One of the final hydridic products (generated in m ethanol-^) contains terminal hydride with a distinct rhodium coupling ( J r ^ = 23.3 Hz) at -14.03 ppm in acetone-d5 in ]H NMR spectrum at room temperature. The other hydridic product has a dimeric structure as the NMR absorption of the hydride is a distinct triplet peak (Jr^h = 29.0 Hz) at -26.38 ppm in acetone-^ at room temperature. Neither of these two rhodium hydride materials is the same as Wieghardf s hydride dimer [CnRh(H)(p-H)2Rh(H)Cn]2+ that is generated by treating CnRhCl3 with NaBH 4 in refluxing water.4 8 Note that the terminal and bridging hydrides in Wieghardt's hydride dimer are fluctional which results in an averaged broad signal for the hydrides at -20.4 ppm at room temperature in acetone-^. Based on the above experiments, the rhodium methyl hydride species [CnRhMe(H)(solv)]+, 35 was believed to be an intermediate in the reaction. The logical question here would be whether it can be observed during the reaction or not. By reacting 2 with CH3OD at room temperature, a rhodium hydride resonance can be observed at -18.7 ppm (Jr^h = 27.3 Hz), but the rhodium methyl peak corresponding to 35 can not be seen in the !H NMR spectrum. With the suspicion that the rhodium methyl resonance of 35 may actually overlap with the rhodium methyl resonance of the starting material 33 (0.65 ppm in CH 3OD), CnRhMe(OH)(OTf), 32 was chosen to react with 152 CH3OD ^ /-*\ • J / — --------- ► '• J h< - - (A) » "Rh-H" Rh. -CH3D RhL CH3OD CH / i (SOLV) Cu / e N(SOLV) - ch3d 3 ch3 3 OCH3 (33) (34) (B) ( 3 - H elimination ,rCH 3O D / f S ? ^ ,N N. K 1 / -c h 4 R h + -------- CH3/ i N (SOLV) (35) " R h -H " Figure 2.17 Two possible paths o f reaction of 33 in CH3OD. CH 3OH. As 32 experiences fast OH" and CH 30 ' exchange with CH3OD solvent to directly generate 34, for the detecting of 35's rhodium methyl peak without the interference of 33's rhodium methyl peak, 32 is ideal for this purpose (Figure 2.18). Indeed, 9 h after dissolving 32 in CH 3OD, a large doublet peak at 0.65 ppm (Jrhh = 2.3 Hz) corresponding to the rhodium methyl of 35 can be clearly seen in the NMR spectrum. O f course the hydride peak again can be seen at -18.7 ppm. In addition, a large singlet peak of CH4 can be seen near 0.2 ppm. The three distinct ligand methyl peaks indicate that 35 is a chiral molecule. As CnRhMe2 OTf, 2, forms the solvate [CnRhMe2 (HOMe)]+, 153 CH3OD CH, * h _ CH3D / \ N (SOLV) ch3 (33) CH3OD C H /pST^x K \ / R h / I^O T f O H (32) CH- N N N , < y / R h + OCH3 (34) (SOLV) p - H elimination C H N ,N R h + / i ^(SOLV) H (35) CH , " R h -H " Figure 2.18 Generating [CnRhMe(H)(solv)]+ by different starting materials. 33, in methanol, [CnRhMe(H)(HOMe)]+, 35, is believed to be the dominant form of the rhodium methyl hydride in methanol. On reacting CnRhMe(OH)(OTf), 32, or CnRhMe2 OTf, 2, with CD 3OD, besides CH3D, a small amount of CH2D2 was also formed. By dissolving [CnRh(CH3)(D)(PMe3)]BR4 in chlorobenzene or DMSO, at room temperature, Chunming Wang in our group found that the protons of the methyl group on rhodium and the deuterium on rhodium scramble intramolecularly, presumably through reductive elimination and reactivation of methane.4 9 The bonding between methane and the rhodium(I) center of the intermediate seems to be 154 substantial. In the reaction of 32 or 2 with CD3OD, since the only deuterium source is CD 3OD, to generate CH2 D2 should certainly require both reversible intramolecular methane reductive elimination followed by methane reactivation and also the isotope exchange of rhodium hydride (or deuteride) with CD3OD solvent (by protonate the "Rh-H" to generate HD and "RhOCD3" followed by P -D elimination to give Rh-D) or with the coordinated CD20 (by reversible hydride insertion followed by P-D(H) elimination). Attempts to trap the rhodium methyl hydride species 35 in methanol with NMe3 and PMe3 were not successful. Trapping 35 with other ligands to make more stable rhodium hydride products is in progress. One particularly l ; j interesting ligand is CO since [CnRJhMe(H)CO]+ will offer direct comparison ) J chemistry to [CnRhMe(H)(PMe3 )]+. Its dialkyl analog [CnRhMe2 (CO)]OTf, 15 j was found to be a very stable molecule. i! i j So far, there are only two rhodium alkyl hydride species that have been | isolated and characterized: (Me3P)3Rh(H)(CH 2 C(0)CH 3)Cl5 0 and j ; j CnRhMe(H)(PMe3)]BR4 . 4 9 There are only a few reports about rhodium alkyl j hydrides that can be observed at room temperature. 51 Clearly, complex 35, j j [CnRhMe(H)(solv)]OTf, is one of the rare examples of rhodium alkyl hydride | complexes that can be observed at room temperature. j Conclusions A series of CnRh complexes has been synthesized and characterized in water and methanol. These complexes demonstrate well-defined chemistry in protic phase. CnRhMe2OTf, 2, dissolved in water at room temperature evolves 155 one equivalent of methane and forms [CnRhMe(0H)(H 2 0 )]0 T f, 29. Removal of solvent yields CnRhMe(OH)(OTf) which has been fully characterized. I j [CnRhMe(OTf)(H2 0)]0T f, 14, and [CnRhMe(H2 0 ) 2 ](0Tf)2, 13, can be generated by adding different amounts of water to a nitromethane solution of ! CnRhMe(OTf)2, 3. The structures of 13 and 14 have been confirmed by X-ray I crystallography. Once dissolved in water, CnRhMe(OTf)2, 3, forms the solvate : [CnRhMe(H2 0 ) 2 ](0Tf)2, 13, immediately. Complex 13 can be deprotonated twice by adjusting the pH of the solution forming [CnRhMe(0H)(H 2 0 )]0 T f j (29, pKa! = 8 .6 ) and CnRhMe(OH) 2 (30, pKa2 = 10.7) in turn. At 50 °C, 29 slowly decomposes in water, while 13 (pH < 6 ) and 30 (pH > 12) are both stable in water. It seems that the basicity of the methyls on rhodium and the j ; ! ; acidity of the aqueous solution can both effect the stability of the CnRhMe I species in water. The stability of 2, 32 and 3 in aqueous solution correlates I very well with the electron richness of the rhodium center of these species as I : indicated by X-ray photoelectron spectroscopy (Chapter 3). ! ' 1 At 24 °C, 29 slowly catalyzes ethylene polymerization in water with an average turnover number of one per day under 60 atm of ethylene pressure. At ! | 50 °C, disappearance of 29 in the presence of ethylene follows the rate law | ! £obsd[29][C2H4]. The pH vs. polymerization rate profile in water indicates that j ■ I I ; 29 is the most effective catalyst while 13 and 30 are not at room temperature. ! ! I s . ! ; But 13 does effect ethylene polymerization at 50 °C. The key to the reactivity | of 29, compared to 13 and 30, lies in three factors: the single positive charge of 29 allows easier ligand dissociation than from dication 13; the good leaving | ! 156 group water is not present in 30; and leaving of water from 29 is facilitated by 71-donation of the lone pairs of the hydroxyl ligand. Probably, neither 13 nor 30 becomes unsaturated at a significant rate at room temperature. The fact that 29 polymerizes ethylene much faster in CH2C1 2 and acetone than in water indicates that less coordinating solvents are important for faster ethylene polymerization. The reactions of 2 and 3 with ethylene in methanol are basically very similar to the reactions in non-protic organic solvents. Complexes 2 and 32 slowly decompose in methanol to eventually form two rhodium hydride products. The rhodium methyl hydride [CnRhMe(H)(solv)]OTf intermediate, 35, can be clearly observed by *H and 1 3 C NMR in the decomposition process of 2 and 32. This CnRh system offers the first example of aqueous phase coordination polymerization of ethylene. Although the rate of polymerization of ethylene in this system is extremely slow, the nature of the catalysts and the reaction conditions are very novel. The rhodium methyl hydride [CnRhMe(H)(HOMe)]+ is one of the rare examples of rhodium alkyl hydride complexes that can be observed at room temperature. Experimental General Newly distilled water ( pH « 7) was used for the aqueous phase chemistry. For the measurement of pH, a Coming pH meter (Model 125) was employed. To obtain accurate pH, the electrode of the pH meter was soaked in distilled water for at least 1 2 h followed by calibration with standard buffer 157 solutions ( pH - 4 , 1 and 10) before the real measurements. Methanol (also deuterited methanol) was distilled onto activated 3A molecular sieves. All of the methanol phase experiments were done under nitrogen with standard vacuum line and dry box techniques (Chapter 1). CnRh Complexes CnRhM e(OH)(OTf) To 1.00 g of CnRhMe2OTf in a Schlenk flask, 15 mL of distilled water was added at RT under nitrogen. This was allowed to stir for 36 hours and the solution was filtered to another Schlenk flask, followed by 5 mL water wash. Water was removed under vacuum. The resulting yellow solids were vacuum dried overnight; 0.94g (94%) of yellow product was obtained. m NMR(D 20 ; DSS, (Me3 Si(CH2 )3S 0 3Na)reference): 5 1.51 (d, J r ^ = 2.2 Hz, KhCH3 ), 2.50 (s, 6 H [NCH3] \ 2.98 (s, 3H [NC/f3]), 2.70-3.20 (m, NOT2). 1 3C{1H}NMR: 8 8.41 (d, J r ^ = 26.8 Hz, RhCH3), 49.60 (one NCH3), 53.73 (two NCH3 ), 57.42, 63.32, 65.35 (NCH2). Anal. Calcd for Cn H 2 5N 30 4F 3 SRh: C, 29.02; H, 5.53. Found: C, 29.14; H, 5.47. [CnRhM e(H 2 0 ) 2 ](0T f)2, [CnRhM e(OH)(H 2 0 )]O T f and CnRhM e(OH ) 2 Complex CnRhMe(OTf) 2 slowly dissolves in water. On dissolution it immediately forms the disolvate [CnRhMe(H2 0 ) 2 ](0Tf)2. !H NMR of [CnRhMe(D2 0 )] 2](0Tf) 2 in D20 (reference to DSS): 8 1.78 (d, J r ^ = 2.0 Hz, 3H, RhCH3 ), 2.54 (s, 6 H, NC/73 ), 3.07 (s, 3H, N C //3 ), 2.85-3.35 (m, N Ctf2). ^ C I^ J N M R (D2 0 , reference to DSS): 8 10.12 (d, J r ^ = 25.2 Hz, RhCH3 ), 49.88, 54.32, 57.26, 63.96, and 66.27 (s, NCH2, NCH3). Adding leq of NaOH to the aqueous solution of [CnRhMe(H2 0 ) 2 ](0Tf) 2 resulted in the formation of 158 j [CnRhMe(0H)(H 2 0)]0T f, the *H NMR of which is the same as CnRhMe(OH)(OTf) in D 20 . Adding excess ( > 4eq) NaOH to the aqueous j ; solution of [CnRhMe(0H)(H 2 0 )]0 T f results in the formation of I j ; CnRhMe(OH)2. NMR of CnRhMe(OD) 2 in D20 (reference to DSS): 5 1.21 | (d, 3 ^ = 2.2 Hz, 3H, R hC #3), 2.46 (s, 6 H, N C # 3), 2.77 (s, 3H, N C # 3), 2.80- 3.12 (m, N C #2). 1 3 C NMR of CnRhMe(OD) 2 in D20 (reference to DSS): 8 j 7.25 (d, Jrkc = 27.7 Hz, RhCH3), 49.27, 53.20, 57.45, 62.67, 64.50 (s, NCH2 | and NCH3 ). Therm olysis product of [C nR hM e(0H )(H 20 ) ] 0 T f , 29 in D20 : At 50 °C 29 I decomposes slowly (t1 /2 = 20 days) in D20 to form complexes A and B. By | j running the reaction at 80 °C, the reaction reaches completion much faster than ; | at 50 °C. Based on ion exchange resin analysis, A was found to be a t i I j monocation and B a dication. Complex A and B can be separated by ion I j exchange resin (Sephadex-SP C-25, 40-120p) with a aqueous solution of 0.2 M I I | NaCl and 0.01 A/NaOH as the eluant (the resin separation of A and B is | | I discussed below). So far, complexes A and B are believed to be I [CnRh(0H)2 (H2 0 )]+ and [CnRh(OH)(^-OH)2 (OH)RhCn]2+, respectively. JH j NMR of A in D20 (reference to HOD): 8 2.58 (s, 9H, N C #,), 2.94 (s, 12H, i N C # 2). m NMR of B in D20 (reference to HOD): 2.96 (s, 9H, N C #,), 3.05 ! | j i j (s, 12H, n c # 2). I I i ! i j Separation of complex A and B by ion exchange resin (with the help from Dr. ! Gordon Miskelly) General information: Since higher charged metal ions bind | resin more strongly than lower charged metal ions, therefore lower charged metal ions should be eluted out first. For the separation of basic metal ions by ■ I : j 1 5 9 ! Sephadex-SP C-25 ion exchange resin, if the metal ion is mono-charged, it should be eluted by 0.1M NaCl and 0.01 M N aO H mixed eluant at a reasonable i rate; if the metal ion is di-charged, it should be eluted by 0.2 M NaCl and 0.01M NaOH mixed eluant at a reasonable rate; if the metal ion is tri-charged, j it should be eluted out by 0.5 M N aC l and 0.01 M N aO H mixed eluant at a reasonable rate. A small amount of Sephadex-SP C-25 ion exchange resin was mixed I ; j j with water. Then the swallowed resin gel was transferred to a pipet that has a pre-cut and wet glass wool blocked tip, followed by adding of 1 mL of water to ! the top of the resin column (column height ca.5cm). Right before the water i j layer on the top of the resin column disappeared, 0.3 mL solution of the mixture j j of A and B (A:B = 1:2 based on Rh as indicated by NMR) was placed on the j j j ! top of the column. Right before the aqueous layer on the top of the column i : disappeared, eluant was added to the top of the resin column. It was found that ; 0.2 M N aC l and 0.01 M N aO H gave good separation result. About 15 min later, | i the light yellow band of A and the intense yellow band of B were well I separated. By adding more eluant, complex A was separated first, the elution | i j i rate of which corresponds to the rate of monocation; complex B was separated I after A, its elution rate is typical for dication. I Thermolysis product of CnRhM e(OTf)2, 3 in D2 0 : Complex 3 was found to i j slowly decompose in D20 at 80 °C (t1 /2 = 36 days) to form complex C. The I structure of complex C has not been determined yet. !H NMR reveals that this I molecule has a plane symmetry (2:1 ratio of NCH3 ). Clearly C is different from I : A and B. *H NMR of C in D20 (reference to HOD): 8 2.76 (s, 3H, NCftT3 ), ■ : 2.91 (s, 6 H, N C //3), 3.01, 3.03-3.28 (s, m, NCH2). 160 j [CnRhM e(H)(HOM e)]OTf, 35. Complex 35 is an intermediate for the decomposition of CnRhMe2 OTf, 2, or CnRhMe(OH)(OTf), 32, in methanol. Nine hours after dissolving complex 32 in CD3OD, the concentration of 35-D has built up and can be clearly observed as a chiral molecule by NMR (CD 3OD): 8 0.65 (d, = 2.3 Hz, RhCi/3 ), 2.66 (d, J r ^ = 2.3 Hz, NCH 3 ), 2.73, 3.00 (s, N C/f3 ), 2.80-3.30 (m, NC£f2). If CH3 OD is used as reactant and solvent, the rhodium hydride absorption of 35 is at -18.7 ppm (Jr^h = 27.3 Hz). The coupling between the rhodium hydride and the protons of the rhodium methyl, 3Jc//3Rhtf is 0.9 Hz. If 1 3C-labeled 32 is used to react with CH3 OD, the rhodium methyl peak can be clearly observed at -8 .1 ppm ( J r ^ = 29.1 Hz) by 1 3 C NMR. The coupling between 1 3CH3 and the hydride 2JC H was observed to be 8.0 Hz by *H NMR. polymerization of Ethylene: The [CnRhMe(OH)(H2 0)]OTf, 29, catalyzed ethylene polymerization under 60 atm of ethylene in water was carried out in a 100 mL high pressure stainless steel bomb with continuous agitation of the solution by a magnetic stirring bar. The bomb was connected to the ethylene tank through metal tubing together with a control valve and a pressure gage. The pressure of ethylene in the bomb was kept relatively constant by quickly opening and closing the valve once a day. This reaction was allowed to proceed at 24 °C for 90 days. Workup procedure was as usual (Chapter 1). The polyethylene obtained had Mw = 5,100 and polydispersity of 1.6. Other ethylene polymerization experiments were carried out in sealed tubes, the details of which have been discussed in chapter 1 . 161 Kinetic Experiments For all the kinetic experiments that were carried out at 50 °C in this chapter, since their rates are relatively slow, all of the samples were taken from the 50 °C bath and cooled to room temperature just before the NMR spectra were taken at room temperature. For the kinetic experiments of 29-catalyzed ethylene polymerization, reactions were carried out in sealed 5-mm NMR tubes in a constant temperature bath at 50 °C without agitation of the tubes. Rates in D20 were followed by observation of the 1 3C{1H} resonance of 99% enriched [CnRhC1 3CH 3)(OD)(OD2)]+, 29-1 3 C, with respect to internal DSS. Good linear plots were obtained over ca. 4 half-lives. Ethylene concentration in D20 was determined by NMR integration of the sample equilibrated to 22 °C. Since the ethylene concentrations at 50 °C were not known, the rate constant are reported for each 22 °C-measured [C2 H4] as k = kobsd[C2 H4]: 0.0070 M, k = 7.59(0.10) X 10" 6 s"1; 0.020M, k = 2.19(0.02) X 10-5 s"1 ; 0.036M ,k = 4.34(0.05) X 10-5 s - i. Data Kinetics Data: From page 163 to page 171. X-ray Data: From page 172 to page 183. 162 Protonolysis OF CnRhMe2(OTf) in D20 at 24C le (s) StartMat Ln(SM) Ln(SM)Calc 0 R egression Output: 341 2 .7 7 8 1.021731 1.049404 Constant 1503 2 .7 4 8 1.010873 1.005119 Std Err o fY E s t 2665 2 .6 3 4 0 .968504 0.960835 R Squared 3827 2 .5 0 2 0.91709 0.91655 No. of O bservations 4 9 8 9 2 .4 0 4 0 .877134 0 .8 7 2 2 6 5 D egrees of Freedom 6150 2.301 0.833344 0 .828018 7312 2 .2 8 5 0 .8 26366 0.783733 X Coefficient(s) -3.8E -05 8474 2 .0 9 0 .7 37164 0 .739448 Std Err of Coef. 7.58E -07 9 6 3 6 1.965 0.675492 0.695164 10798 1.902 0 .6 42906 0.6 50879 1 i9 6 0 1.817 0 .5 97187 0.606594 13122 1.7 0 .5 30628 0.5 62309 14284 1.657 0 .5 05009 0.518024 15446 1.602 0.471253 0.4 73739 16608 1.612 0.477476 0.429454 17770 1.481 0 .3 92718 0.38517 18931 1.422 0.3 52064 0.340923 20 0 9 3 1.387 0.327143 0.296638 21 2 5 5 1.267 0.2 36652 0.252353 22 4 1 7 1.19 0.173953 0.208068 0.9- 0 ,8- 0.7- I 0 .6. _c 0.5- 0.4- 0.3- 0 .2- 0.1 341 2665 4989 7312 9636 11960 14284 16608 18931 21255 1503 3827 6150 8474 10798 13122 15446 17770 20093 22417 163 CnRhMe(OH)(OTf) protonolysis Kinetics in D20 at 50C Time %RhMe+ Time Ln(Rh) Ln(Rh) (minutes) (secs) (calcd) 0 1 0 0 0.056789 3108 0.869 186480 0.140412 0.132707 Regression Output 6060 0.837 363600 0.177931 0.204815 Constant 8266 0.767 495960 0.265268 0.258701 StdErrofYEst 12564 0.685 753840 0.378336 0.363687 R Squared 15959 0.645 957540 0.438505 0.446616 No. of Observations 18455 0.61 1107300 0.494296 0.507586 Degrees of Freedom 24047 0.523 1442820 0.648174 0.64418 29684 0.443 1781040 0.814186 0.781874 X Coefficient(s) 4.0711366E-07 44626 0.323 2677560 1.130103 1.14686 Std E rr of Coef. 4.2441884E-09 55689 0.242 3341340 1.418818 1.417094 67055 0.184 4023300 1.69282 1.694729 1.6- 1.4- 12- < D 0 .8 - > 0.6- 0.4- 0.2- 0.5 3.5 4.5 Time (sec) (M illions) 164 [Rh]( ) = 0.044 M, PC2 H4 = 7 atm (22 °C) Ethylene insertion rates in to C nR hM e(O H )(O T f) in D20 at 50C tim e (h r ) time(sec) A /A o L n (A /A o) L n(A /A )calcd 0 0 1 0 0 17 61200 0.598 0.514165 0.464757 39 140400 0.367 1.002393 1.066207 59 212400 0.206 1.579879 1.612979 79 284400 0.1197 2.122767 2.159752 98 352800 0.0642 2.745752 2.679186 Regression O u tput: Constant 0 Std E r r of Y Est 0.051784 R Squared 0.99744 N o. of Observations 6 Degrees of Freedom 5 X Coefficient(s) 7.59 E-06 Std E r r of Coef. 9.89E-08 2.5 o 1 1& 0.5 50 350 400 t(s) (Thousands) 165 [Rh]0 = 0.044 M, PC2H4 = 14 atm (22 °C) Ethylene insertion rates into C nR hM e(O H )(O T f) in D20 at50C tim e (h r ) time(sec) A /A o L n (A /A o) L n(A /A )calcd 0 0 1 0 0 12 43200 0.388 0.94675 0.945059 16 57600 0.297 1.214023 1.260078 20 72000 0.204 1.589635 1.575098 25 90000 0.139 1.973281 1.968872 30 108000 0.089 2.419119 2.362646 36 129600 0.061 2.796881 2.835176 Regression O utput: Constant 0 Std E r r of Y Est 0.034182 R Squared 0.998694 N o. of Observations 7 Degrees of Freedom 6 X Coefficient(s) 2.19E-05 Std E r r of Coef. 1.58E-07 2.5 0 1 £ I 0.5 20 60 80 t(s) (Thcxj sands) 140 166 [Rh]0 = 0.044 M, PC2H4 = 33 atm (22 °C) Ethylene insertion rates in to C nR hM e(O H )(O Tf) in D20 at 50C tim e (h r ) time(sec) A /A o L n (A /A o) L n(A /A )calcd 0 0 1 0 0 3.5 12600 0.544 0.608806 0.546421 6.5 23400 0.344 1.067114 1.014783 9.5 34200 0.228 1.47841 1.483144 12.5 45000 0.147 1.917323 1.951505 16 57600 0.0827 2.492536 2.497926 Regression O u tp u t: Constant 0 Std E r r of Y Est 0.039624 R Squared 0.998061 No. of Observations 6 Degrees of Freedom 5 X Coefficient(s) 4.34E-05 Std E r r of Coef. 4.66E-07 2.5- 20 30 t(s) 40 50 60 (Thousands) 167 [Rh]0 = 0.069 M, [=]average = 0.0091 A/ at 21 °C (15 atm at 21 °C) p o ly of ethylene b y R h M eO T f2 in D20 a t p H 2 at 50C ir ) tim e(sec) S ta rt M a t L n (S M ) L n (S M )C a lc 0 0 0.73 -0.31471 -0.30525 143 514800 0.551 -0.59602 -0.61108 198 712800 0.493 -0.70725 -0.72871 237 853200 0.432 -0.83933 -0.81211 3 1 1 1119600 0.379 -0.97022 -0.97037 R egression O u tp u t: C on stan t S td E r r of Y E st R Squared N o. of O bservations D egrees of F reed om -0.30525 0.022491 0.993947 5 3 X C oefficien t(s) S td E r r of C oef. -5.94068E-07 2.676643E-08 -0.3; -0.4- -0.5- q -0.7- - 0 .8- -0.9- 0.2 0.4 0.8 time(S) (Millions) 168 [Rh]„ = 0.043 M, [=]a v e r a g e = 0.157 M Polym erization of Ethylene by C nR hM e(O H )(O T f) in acetone at 24C tim e(hr) time(sec) R h M eZ (R h M e) ln(R h/R ho ln(Rh)calc 0 0 1 0 -0.78368 19.5 70200 0.248 -1.39433 -1.40278 45 162000 0.108 -2.22562 -2.21237 92.7 333720 0.0242 -3.7214 -3.72677 116.5 419400 0.0113 -4.48295 -4.48239 Regression O u tp u t: Constant -0.78368 Std E r r of Y Est 0.011755 R Squared 0.999953 N o. of Observations 4 Degrees of Freedom 2 X Coefficient(s) Std E r r of Coef. -8.81903E-06 4.271689E-08 -0.5- - 1 - -1.5- - 2 - ■ c -2.5- -3- -3.5- -4- -4.5 40 60 t (hr) 80 100 120 169 [Rh]u = 0.074 M, [= L „ agc = 0.049 M (4 atm) p o ly of ethylene b y R h M e O T f2 in M e O H @ 4 a tm a t 20C i r ) tim e(sec) S ta r t M a t L n ( S M ) L n (S M )C a lc 0 0 1 2 43200 13.7 2.617396 2.630892 264 950400 10.23 2.325325 2.298544 432 1555200 7.93 2.070653 2.076979 600 2160000 6.35 1.848455 1.855414 R egression O u tp u t: C o n sta n t 2.646718 S td E r r o f Y E st 0.022224 R S q u a red 0.997 N o . o f O b servation s 4 Degrees o f F reed o m 2 X C o efficien t(s) -3.66344E-07 S td E r r o f C oef. 1.420926E -08 2.7- 2 .& 2.5 2.4 2 . 1- 1.9- 0 .5 time(S) (Millions) [Rh]u = 0.074 M, [=]a v e ra g c « 0.177 M. poly of ethylene by RhMeOTf2 in MEOH @ 15atm at 20C tim e (h r ) tim e(sec) S ta r t M a t L n ( S M ) L n (S M )C a lc 0 0 10.85 2.384165 2.372745 48 172800 8.14 2.09679 2.158925 75 270000 8.25 2.110213 2.038652 130 468000 5.73 1.745716 1.79365 170 612000 5 .2 1 1.65058 1.615467 218 784800 4.09 1.408545 1.401648 243 874800 3.58 1.275363 1.290284 C o n sta n t 2.372745 S td E r r o f Y E st 0.050819 R S q u a red 0.986804 N o . o f O b servation s 7 Degrees o f F reed o m 5 X C o efficien t(s) -1.23738E-06 S td E r r o f C oef. 6.399 0 6 7 E -O 8 RhMe(OTf)2 in MeOH 2 .2- S* 1.8 ' 1 .6 - 1.4- 1.2 900 time(S) (Thousands) 171 Table 1: Summary of Crystal Data and Refinement Results for [CnRhMe(OTf)(H2 0)]OTf molecular weight(g/mole) 587.1 space group P1 21/n 1 (No, molecules per unit cell 4 a (angstrom) 8.9264 b (angstrom) 14.551 c (angstrom) 18.733 a(deg) 90.00 P(deg) 112.5 V(deg) 90.00 V (angstrom3) 2247.98 crystal dimensions (mm) 0.3x0.4x0.5 calculated density (g cm"3) 1.74 wavelength (angstrom) used for data collection 0.71069 SinO/a. limit (angstrom"1) 0.5947 total number of reflections measured 4077 number of reflections used in , structural analysis I > 3o(l) 3445 number of variable parameters 279 final agreement factors R(F) = 0.0557 R(W) = 0.0557 172 Table 2: Final Atomic C oordinates for [CnRhMe(OTf)( H2Q)]OTf Atom X y z RH 1 0.3890( 1) 0.5241 ( 1) 0.2873( S 2 0.0Q55( 3) 0.4607( 2) 0.2018( S 3 0.1172( 3) 0.6884( 2) 0.4609( N 4 0.6040( 8) 0.5841(5) 0.3519( N 5 0.5290( 7) 0.4268( 5) 0.2630( N 6 0.4171 ( 8) 0.6009( 5) 0.1906( 0 7 0.1727( 6) 0,4612( 4) 0.2079( 0 8 -0.0374( 7) 0.3842( 5) 0.2378( 0 9 -0.0508( 7) 0.5489( 5) 0.2147( C 10 0.7454( 9) 0.5228( 6) 0.3537( C 11 0.6862( 9) 0.4256( 6) 0.3315( C 12 0.5539( 9) 0.4530( 6) 0.1902( C 13 0.4334( 9) 0.5235( 6) 0.1423( C 14 0.5693(10) 0.6570( 7) 0.2258( C 15 0.6083(10) 0.6733( 6) 0.3103( C 16 0.6283(10) 0.6078( 7) 0.4337( C 17 0.4542(10) 0.3315( 6) 0.2523( C 18 0.2752(11) 0.6593( 7) 0.1447( C 19 0.3648(10) 0.4491(7) 0.3780( C 20 -0.1006(10) 0.4410( 7) 0.0986( C 21 0.1960(12) 0.7934( 8) 0.5107( F 22 -0.2580( 7) 0.4419( 6) 0.0784( F 23 -0.0639( 8) 0.5024( 5) 0.0580( F 24 -0.0584( 8) 0.3594( 5) 0.0794( F 25 0.0943(12) 0.8504( 7) 0.5114( F 26 0.3064(10) 0.7825( 5) 0.5774( F 27 0.2643(11) 0.8399( 6) 0.4672( 0 28 0.2571(10) 0.6460( 7) 0.4583( 0 29 -0.0014(8) 0.7150( 6) 0.3890( 0 30 0.0562(10) 0.6457( 7) 0.5133( 0 31 0.2478( 7) 0.6299( 4) 0.3088( o 1 1 4 4 4 3 4 4 5 5 5 5 6 6 5 6 6 5 6 7 4 3 4 7 4 6 5 4 5 4 173 Table 3: T em perature Factors for [CnRhMe(0Tf)(H2 0)]0T f Atom *Un X103 U22X103 U33X103 U12X103 U13X103 U23X103 RH 1 35( 0) 38{ 0) 39( 0) 0 ( 0) 18( 0) -3( 0) S 2 36( 1) 54( 1) 47( 1) - 1( 1) 19( 1) -1( 1) S 3 50( 1) 61( 1) 49( 1) -2 ( 1) 14( 1) -3( 1) N 4 44( 2) 46( 2) 46( 2) -1( 1) 22 ( 1) -4( 2) N 5 37( 2) 40( 2) 45 ( 2 ) 2 ( 1) 17( 1) 0 ( 1) N 6 45( 2) 38( 2 ) 50( 2) 1( 1) 17(1) • 2 ( 2 ) O 7 37( 1) 62( 2 ) 52(1) 0 ( 1) 23( 1) -6( 1) O 8 62( 2 ) 71(2) 67( 2) -13( 2) 30( 1) 17( 2) O 9 55( 2) 63( 2) 79( 2 ) 11( 1) 35( 1) -8 ( 2 ) C 10 35( 2) 57( 2) 56( 2) 2 ( 2) 16( 2) *3( 2) C 11 40( 2) 52( 2) 47( 2) 10( 2) 9( 2) 0 ( 2 ) C 12 53( 2 ) 55( 2) 40(2) 7( 2 ) 27{ 1) 3( 2) C 13 56( 2) 54( 2) 41(2) 0 ( 2) 27(1) 0 ( 2 ) C 14 57( 2) 58( 2) 67( 2) -16( 2 ) 24( 2) 3( 2) C 15 61(2) 44( 2) 69( 2) -15( 2 ) 16( 2 ) -1( 2 ) C 16 71(2) 86( 2 ) 46( 2) -6 ( 2) 23( 2) -26( 2 ) C 17 57( 2) 35( 2) 75( 2) -4< 2) 26( 2 ) "4( 2) C 18 70( 2 ) 70( 2) 69( 2) 19( 2) 23( 2) 2 0 ( 2 ) C 19 6 8 ( 2 ) 70( 2) 44( 2) 1( 2) 31(2) 1( 2) C 20 48( 2) 88( 2 ) 54( 2) 0 ( 2) 24( 2) - 1( 2 ) C 21 112 ( 2 ) 69( 2) 67( 2) 6( 2 ) 25( 2) -7( 2) F 22 45( 1) 185( 2) 63( 2) -6 < 2) 11( 1) -8 ( 2) F 23 98( 2) 124( 2) 59( 1) 0 ( 2 ) 38{ 1) 23 ( 2) F 24 11 1( 2 ) 105( 2) 70( 2 ) -5( 2) 31(2) -28( 2 ) F 25 2 1 1( 2 ) 133( 2) 190( 2 ) 87( 2) 2 0 ( 2 ) -63( 2) F 26 185( 2) 85( 2) 6 6 ( 2) -16( 2 ) -23( 2) -5( 2) F 27 194( 2) 119( 2) 150( 2 ) -71(2) 14( 2 ) 36( 2) 0 28 95( 2) 140( 2 ) 108( 2) 38( 2 ) 2 1 ( 2 ) -47( 2) 0 29 69( 2) 109( 2) 58( 2) -16( 2 ) 3( 2) 18( 2 ) 0 30 113( 2) 147( 2) 89( 2) -37{2) 2 0 ( 2 ) 50( 2) 0 31 51(2) 49( 2) 8 8 ( 2 ) 6( 1) 30(1) -14( 2 ) The complete tem perature factor is exp[-2ji2(U11h2a * 2 + U22k2b" 2 + U33l2c*2 + 2U12hka*b' + 2U 13hla*c’ + 2U23klb'c*] Table 4: Bond D istances(angstrom s)for [CnRhMe(0Tf)(H2 0)]0T f RH 1— N 4 RH 1— N 5 RH 1—N 6 RH 1—0 7 RH 1—C 19 RH 1—0 31 S 2—0 7 S 2—0 8 S 2—0 9 S 2—C 20 S 3—C 21 S 3—0 28 S 3—0 29 S 3—0 30 N 4—C 10 N 4—C 15 N 4—C 16 N 5—C 11 N 5—C 12 N 5—C 17 N 6—C 13 N 6—C 14 N 6—C 18 C 10—C 11 C 12—C 13 C 14—C 15 C 20— F 22 C 20—F 23 C 2 0—F 24 C 21—F 2 5 C 21—F 2 6 C 2 1 —F 27 2.033( 6 ) 2.052( 6) 2.222{ 7) 2.140( 5) 2.099( 9) 2.123( 6) 1.453{ 5) 1,427( 6 ) 1,432( 7) 1.821(10) 1.787(11) 1.411( 8) 1.411(7) 1.433( 9) 1.537(10) 1.522(11) 1.503(11) 1.496< 9) 1.512(10) 1.519(10) 1.486(11) 1.504(10) 1.494(11) 1.511(12) 1.509(11) 1.502(14) 1.308( 9) 1.296(11) 1.336(12) 1.234(13) 1.271(11) 1.369(14) 175 Table 5: Bond Angles (deg) for [CnRhMe(0Tf)(H2 0)]0T f N 4-RH 1-N 5 85.0( 3) N 4-RH 1-N 6 83.9( 3) N 5-RH 1-N 6 84.2( 3) N 4-RH 1-0 7 173.1 < 2) N 5-RH 1-0 7 90.9( 2) N 6-RH 1-0 7 90.1(2) N 4-RH 1-C 19 96.1(3) N 5-RH 1-C 19 94.6 ( 3) N 6-RH 1-C 19 178.8( 3) 0 7-RH 1-C 19 89.7 ( 3) N 4-RH 1-0 31 94.0( 3) N 5-RH 1-0 31 177.0( 3) N 6-RH 1-0 31 92.9( 3) 0 7-RH 1-0 31 89.9( 2) C 19-RH 1-0 31 88.3( 3) O 7-S 2 -0 8 114.8( 4) 0 7-S 2 -0 9 113.5( 4) 0 8 -S 2 -0 9 116.4( 4) 0 7-S 2-C 20 100.7( 4) O 8 -S 2-C 20 104.7( 4) 0 9-S 2-C 20 104.3( 4) C 21-S 3 -0 28 102.4( 5) C 21-S 3 -0 29 105.4( 5) 0 28-S 3 -0 29 116.0( 5) C 2 1 -S 3 -0 30 1 0 1.0( 6 ) 0 28-S 3 -0 30 114.0( 6 ) 0 29-S 3 -0 30 115.4( 5) RH 1-N 4-C 10 110.1(5) RH 1-N 4-C 15 105.3{ 5) C 10-N 4-C 15 108.9( 6 ) RH 1-N 4-C 16 116.2( 5) C 10-N 4-C 16 108.4( 6 ) C 15-N 4-C 16 107.8( 7) RH 1-N 5-C 11 105.6( 5) RH 1-N 5-C 12 109.7( 5) C 11-N 5-C 12 111.3( 6 ) RH 1-N 5-C 17 112.6 ( 5) C 1 1-N 5-C 17 108.9( 6 ) C 12-N 5-C 17 108.7( 6 ) RH 1-N 6-C 13 100.6( 5) RH 1-N 6-C 14 106.3( 5) C 13-N 6-C 14 113.3( 6 ) RH 1-N 6-C 18 114.8(6) C 13-N 6-C 18 109.8( 7) C 14-N 6-C 18 111.6( 7) RH 1-0 7-S 2 133.1(4) [CnRhMe(0Tf)(H2 0 )]0 T f Table 5: (continued) N 4-C 10-C 11 109.9( 6) N 5-C 11-C 10 109.8( 7) N 5-C 12-C 13 113.0( 6) N 6-C 13-C 12 111.5( 6) N 6-C 14-C 15 110.7( 7) N 4-C 15-C 14 111.4( 7) S 2-C 20-F 22 111-7( 7) S 2-C 20-F 23 111 -7( 7) F 22-C 20-F 23 107.9( 8) S 2-C 20-F 24 109.9( 7) F 22-C 20-F 24 108.3( 8) F 23-C 20-F 24 107.1( 8) S 3-C 21-F 25 115.8( 8) S 3-C 21-F 26 114.2{ 8) F25-C 21-F 26 111.7(11) S 3-C 21-F 27 106.7( 8) F25-C 21-F 27 99.8(11) F26-C 21-F 27 107.0( 9) 177 Table 1: Summary of Crystal Data and Refinement Results for [CnRhMe(H2 0 )2](OTf)2 molecular weight(g/mole) 623.4 space group Pna21 (No. 33) molecules per unit cell 4 a (angstrom) 14.371(9) b (angstrom) 18.269(13) c (angstrom) 8.687(5) a(deg) 90.00 P(deg) 90.00 7(deg) 90.00 V (angstrom3) 2281 (3) crystal dimensions (mm) 0.3x0.4x0.4 calculated density (g cm '3) 1.82 wavelength (angstrom) used for data collection 0.71069 SinOA. limit (angstrom-1) 0.5947 total num ber of reflections m easured 1866 number of reflections used in structural analysis 1 > 3o(l) 1045 number of variable param eters 289 final agreem ent factors R(F) = 0.0521 178 Table 2: Final Atomic C oordinates for [CnRhMe(H20 )2](0Tf)2 : Atom X y z Rh 1 0.5245( 1) 0.3Q32( 1) 10.0 0 0 0( 0 ) 0 2 0.6288(17) 0.2895(11) 0.1712(26) O 3 0.6336(15) 0.2715(10) -0.1565(24) N 4 0.4680(10) 0.1908( 8) 0.0015(40) N 5 0.4282(18) 0.3280(15) 0.1652(25) N 6 0.4169(20) 0.3180(17) -0.1548(28) C 7 0.5735(16) 0.4119(11) -0.0008(42) C 8 0.4317(19) 0.1852(15) 0.1623(29) C 9 0.3818(24) 0.2526(21) 0.2155(29) C 10 0.3458(22) 0.3773(15) 0.0770(28) C 11 0.3358(17) 0.3490(13) -0.0670(26) C 12 0.3934(28) 0.2488(22) -0.2349(34) C 13 0.3939(22) 0.1848(19) -0.1197(33) C 14 0.5394(16) 0.1322(11) -0.0263(29) C 15 0.4448(20) 0.3761(17) 0.2937(26) C 16 0.4701 (22) 0.3580(16) -0.2975(28) S 17 0.8459( 5) 0.6547( 3) -0.0006(19) O 18 0.7677(21) 0.6613(15) 0.0908(31) O 19 0.8288(18) 0.6684(11) -0.1602(26) 0 20 0.9304(16) 0.6878(12) 0.0463(27) C 21 0.8747(22) 0.5563(15) -0.0031(42) F 22 0.8025(14) 0.5191(10) 0.0428(29) F 23 0.9383(21) 0.5500(14) 0.1085(30) F 24 0.9242(22) 0.5345(11) -0.1230(26) S 25 0.2034( 5) 0.0966( 3) 0.4923(23) 0 26 0.2131(26) 0.1202(18) 0.3412(32) O 27 0.2146(18) 0.1481(12) 0.6202(29) O 28 0.1350(14) 0.0446(12) 0.4710(32) C 29 0.3145(19) 0.0482(14) 0.5038(40) F 30 0.3809(12) 0.0924(13) 0.4748(33) F 31 0.3126(17) -0.0088(13) 0.4210(28) F 32 0.3222(23) 0.0203(17) 0.6456(30) 179 Table 3: T em perature Factors for [CnRhMe(H20 )2](0Tf)2 Atom Un X103 U22X103 U33XIO3 U12X103 U ,3X103 U23X103 Rh 1 25(1) 28 ( 1) 29( 1) 0 ( 1) 11( 2) 3( 3) O 2 56( 4) 22( 4) 58( 4) 21(4) -26( 4) -19( 4) O 3 35( 4) 21(4) 49 ( 4) 0( 4) 11(4) 21(4) N 4 26( 4) 33 ( 4) 47( 4) 6( 4) 7( 5) -11(5) N 5 16(4) 35( 4) 43 ( 4) •3( 4) 11(4) 2( 4) N 6 35( 4) 47( 4) 36( 4) -6 ( 4) 14( 4) -4( 4) C 7 69(4) 28( 4) 59( 4) -16( 4) 9( 5) -18( 5) C 8 56( 4) 31(4) 58( 4) -26( 4) 21(4) 9( 4) C 9 63( 4) 46( 4) 32( 4) 16( 4) 22( 4) 17( 4) C 10 117( 5) 36(4) 102( 5) *4( 4) -12( 4) -18( 4) C 11 35( 4) 37( 4) 42( 4) 36( 4) -13( 4) -11(4) C 12 107( 5) 40( 4) 60( 4) -34( 4) . ■16( 4) -6(4) C 13 81(4) 66( 4) 90( 4) -13( 4) -44( 4) 35(4) C 14 56( 4) 29( 4) 56( 5) 12( 4) 9( 4) 2( 4) C 15 63( 4) 85( 5) 76( 4) 7( 4) 17( 4) -45( 4) C 16 63 ( 4) 60( 4) 43 ( 4) 23( 4) -21(4) 34( 4) S 17 60( 3) 39( 3) 45( 3) 7( 2 ) 39( 4) 10( 4) O 18 172( 4) 79(4) 173(4) 14(4) 136( 4) -14( 4) O 19 123( 4) 40( 4) 75( 4) -36( 4) -25(4) 16( 4) O 20 123( 4) 75( 4) 115< 5) -3( 4) -47(4) -13(4) C 21 128( 5) 75( 4) 52( 4) -4( 4) 6 { 5) 20( 5) F 22 114( 4) 64( 4) 184( 5) -36( 4) -28( 4) 25( 4) F 23 138( 4) 95( 4) 123( 4) 45( 4) -27( 4) 27( 4) F 24 187( 4) 40< 4) 84( 4) 30(4) -16( 4) -27( 4) S 25 52( 3) 39( 3) 97( 4) 13( 3) 32( 4) 4( 4) 0 26 169( 5) 142( 5) 107( 4) 2( 5) 0( 4) 69( 4) 0 27 101(4) 61(4) 131(4) 6( 4) 64( 4) -65( 4) 0 28 8 6 ( 4) 92( 4) 136( 5) -25( 4) -41(4) 50( 4) C 29 94( 4) 61(4) 46( 4) 26( 4) 33( 5) 0( 5) F 30 61(4) 175( 4) 170( 5) •20( 4) 53( 4) 31(5) F 31 108( 4) 104( 4) 175( 5) 55( 4) 22( 4) -33( 4) F 32 203( 5) 161 ( 5) 114( 4) 42( 4) -61(4) 46( 4) The complete temperature factor is e x p l - ^ U ^ h V 2 + U22k2b'2 + U ^ lV 2 + 2U12hka'b* + 2U13h laV + 2U23klb'c*] 180 Table 4: Bond D istances(angstrom s)for [CnRhMe(H20 )2](0Tf)2 Rh 1—0 2 Rh 1—0 3 Rh 1—N 4 Rh 1— N 5 Rh 1— N 6 Rh 1— C 7 N 4—C 8 N 4—C 13 N 4—C 14 N 5—C 9 N 5—C 10 N 5—C 15 N 6—C 11 N 6—C 12 N 6—C 16 C 8—C 9 C 10—C 11 C 12—C 13 S 17—O 18 S 17—0 19 S 17—0 20 S 17—C 21 C 21—F 22 C 2 1 —F 23 C 21—F 24 S 25—0 26 S 25—0 27 S 25—0 28 S 25—C 29 C 29—F 30 C 29—F 31 C 29— F 32 2.126(19) 2.155(18) 2.210(13) 2.044(20) 2.067(24) 2.105(17) 1.494(35) 1.501(33) 1.502(21) 1.591(39) 1.673(33) 1.440(34) 1.504(31) 1.481(41) 1.631(28) 1.498(37) 1.362(25) 1.540(41) 1.382(22) 1.430(22) 1.417(20) 1.844(24) 1.302(27) 1.338(35) 1.323(34) 1.389(26) 1.466(23) 1.379(18) 1.827(22) 1.276(26) 1.266(29) 1.337(35) 181 Table 5: Bond Angles (deg) for [CnRhMe(H20)2](0Tf), 0 2-Rh 1-0 3 O 2-Rh 1-N 4 O 3-Rh 1-N 4 O 2-Rh 1-N 5 O 3-Rh 1 -N 5 N 4-Rh 1-N 5 O 2-Rh 1-N 6 O 3-Rh 1-N 6 N 4-Rh 1-N 6 N 5-Rh 1-N 6 O 2-Rh 1-C 7 O 3-Rh 1-C 7 N 4-Rh 1-C 7 N 5-Rh 1-C 7 N 6-Rh 1-C 7 Rh 1-N 4-C 8 Rh 1-N 4-C 13 C 8-N 4-C 13 Rh 1-N 4-C 14 C 8-N 4-C 14 C 13-N 4-C 14 Rh 1-N 5-C 9 Rh 1-N 5-C 10 C 9-N 5-C 10 Rh 1-N 5-C 15 C 9-N 5-C 15 C 10-N 5-C 15 Rh 1-N 6-C 11 Rh 1-N 6-C 12 C 11-N 6-C 12 Rh 1-N 6-C 16 C 11-N 6-C 16 C 12-N 6-C 16 N 4-C 8-C 9 N 5-C 9-C 8 N 5-C 10-C 11 N 6-C 11-C 10 N 6-C 12-C 13 N 4-C 13-C 12 84.1(5) 98.4( 8) 91.2( 7) 90.7( 8) 174.3( 8) 87.3( 8) 176.2( 8) 99.7( 8) 81.3(9) 85.5( 5) 83.0( 9) 90.5( 8) 177.9( 6) 91.1( 9) 97.2(10) 101.3(13) 108.9(16) 113.8(16) 114.2(10) 109.9(19) 108.7(20) 106.5(14) 106.1(14) 107.1(17) 124.5(16) 112.6(20) 98.3(15) 107.4(14) 111.4(21) 112.6(22) 101.6(14) 125.4(21) 97.6(18) 113.6(18) 115.2(20) 106.9(21) 121.8(23) 110.0(21) 113.8(22) 182 r [CnRhMe(H2 0)2 ](0Tf)2 Table 5: (continued) O 18-S 1 7 -0 19 113.7(16) 0 18-S 1 7 -0 20 119.6(16) O 19-S 1 7 -0 20 110.6(13) 0 18-S 17-C 21 105.9(14) 0 19-S 17-C 21 101.4(14) O 2 0 -S 17-C 21 103.2(12) S 17-C 21-F 22 109.1(19) S 17-C 2 1 -F 23 103.2(20) F 22-C 21-F 23 106.1(24) S 17-C 2 1 -F 24 115.1(19) F 22-C 21-F 24 120.8(26) F 23-C 21-F 24 100.2(21) O 26-S 2 5 -0 27 120.4(14) 0 26-S 2 5 -0 28 99.1(19) O 27-S 2 5 -0 28 128.5(15) O 26-S 25-C 29 96.6(17) O 27-S 25-C 29 100.0(14) 0 28-S 25-C 29 107.2(11) S 25-C 29-F 30 109.6(16) S 25-C 29-F 31 110.4(20) F30-C 29-F 31 115.2(23) S 25-C 29-F 32 107.9(20) F 30-C 29-F 32 111.1(28) F 31-C 29-F 32 102.3(22) 183 _ l CHAPTER 3 Photoelectron Spectroscopy of H ard and Soft-Ligated Organorhodium Complexes Results and Discussion The X-ray photoelectron spectroscopy (XPS) work has been done in collaboration with Prof. Paul G. Gassman* and Dr. John R. Sowa, Jr. of the University of Minnesota, Minneapolis. The UV photoelectron spectroscopy (UPS) work has been done in collaboration with Prof. Dennis L. Lichtenberger and Dr. Lalitha Subramanian at the University of Arizona, Tucson. Synthesis of fac-(PMe3)3RhM e3 and Its Derivatives As the CnRh complexes have shown very different chemistry from their phosphine-coordinated analogs (Chapter 1), to try to understand the reasons behind the reactivity differences, photoelectron spectroscopy studies of the CnRh and phosphine-coordinated rhodium complexes were carried out. The synthesis of facially coordinated complex (Me3 P)3 RhMe3, 36, was reported by Wilkinson's group.5 2 It turns out that this preparation works very well (Figure 3.1). An alternative way of making 36 is to displace the Cn ligand of CnRhMe3 with excess PMe3 at 80 °C or above (Figure 3.1). As the alkyls on phosphorus are all saturated alkyl groups, this complex should offer an appropriate model for a soft-ligated analog of the CnRhMe3 complex. Slow evaporation of the hexane solution of 36 lead to the formation of large light yellow crystals of 36. When 36 is obtained pure (e.g. in crystalline * Deceased, April 21, 1993. 184 Rh2(0 2CMe)4 + excess PMe3 Ether MgMe2 Ether fac-(PMe3 )3RhMe3 CnRhMe3 + excess PMe3 > 80°C fac-(PMe3 )3RhMe3 Benzene Figure 3.1 Preparations of fac-(PMe3 )3 RhMe3, form), it is air stable. The X-ray diffraction data of 36 show the expected facial coordination of the three phosphines with average Rh-P and Rh-C bond lengths of 2.33 and 2.13 A, respectively (Figure 3.2). The average bond angle of P-Rh- P (97°) indicates that the steric interactions among the phosphines must be severe. The average N-Rh-N angle of CnRhMe3 is 80°, indicates that the Cn ligand is slightly slipped up along its C3 axis. Stoichiometric treatment of 36 with 1 or 2 eq of HC1 (in Et20/C H 2C12) generates the mer-(PMe3 )3 RhMe2Cl, 37 and mer-(PMe3 )3RhMeCl2, 38 respectively. The structures of 37 and 38 were assigned from their !H and 31P spectra. Complex 36 was found to be unstable under the conditions of UV or X-ray photoelectron experiments. The results of the physical measurements of 36, 37 and 38 will be discussed later in this chapter. To solve the stability problem, we proposed to use the ligand 1,1,1- tris(dimethylphosphinomethyl)ethane ("3P"), the obvious hope being that the chelated phosphine (3P) coordinated rhodium trimethyl complex would demonstrate much better stability than complex 36. Synthesis of 3PRhM e3 and Its Derivatives The synthesis of the ethyl analog of 3P had been reported.5 3 By treating l,l,l-tris(chloromethyl)ethane with lithium dimethylphosphide in THF 185 C 9 C I4 Cl I CIO C 13 C 8 C 12 Rh C 6 C 7 C5 Figure 3.2 ORTEP diagram of the molecular structure of fac-(PMe3)3RhMe3 (Structure solved by Janet Manning and Robert Bau). followed by distillation, the 3P ligand was synthesized (Figure 3.3). Addition |of an ethanol solution of 3P to an ethanol solution of RhCl3.3H20 resulted in the immediate precipitation of yellow solids. Treatment of the isolated solids I : j (presumably 3PRhCl3 ) with methyllithium in THF resulted in the formation of j ! 3PRhMe3, 39, as snow-white colored solids. The solubility of 3PRhMe3 in j relatively non-polar organic solvents is similar to CnRhMe3. Both of them RhCI3.3H20 EtOH (39) Figure 3.3 Synthesis of ”3P" and 3PRhMe3. dissolve in benzene but not in hexane. On the other hand, fac-(PMe3 )3 RhMe3 is very soluble in hexane. The poor solubility of 3PRhMe3 and CnRhMe3 in hexane may attribute to the restricted motion of the chelated 3P and Cn ligands compared to the three non-chelated PMe3 ligands in fac-(PMe3 )3 RhMe3. Slow evaporation of a methylene chloride and toluene solution of 39 in air resulted in the formation of single crystals of 39. The X-ray diffraction data of 39 show the expected facial 3P coordination with average Rh-P and Rh-C bond lengths of 2.29 and 2.17 A, respectively (Figure 3.4). The average P-Rh-P angle in 39 is 89° which is closer to the N-Rh-N angle (80°) of CnRhMe3 than is the P-Rh-P angle (97°) of fac-(PMe3 )3 RhMe3. Note that the Rh-P bonds of 3PRhMe3 are 0.04 A shorter than that of fac-(PMe3 )3 RhMe3. Stoichiometric treatment of 39 with 1 or 2 eq of triflic acid (in Et20/C H 2C12) generates 3PRhMe2OTf, 40, and 3PRhMe(OTf)2, 41, 187 respectively, with the 3P ligand facially coordinating with rhodium in all cases. Complexes 40 and 41 have been fully characterized. Figure 3.4 ORTEP diagram of the molecular structure of 3PRhMe3 (structure solved by Roy Lu and Robert Bau). 188 The closest triamine coordinated analog of 3PRhMe3 is the 1,1,1- tris(dimethylaminomethyl)ethane ("3N") coordinated 3NRhMe3 complex. The synthesis of the 3N ligand had been reported.5 4 The reaction between 3N and RhCl3.3H20 in ethanol didn't give the expected product of 3NRhCl3. CPK models suggest that 3N is much more crowded than Cn in the coordination sphere of RhCl3. This might be the reason why 3NRhCl3 was not obtained. In any event, as CnRhMe3 and 3PRhMe3 are very similar in structure (e.g. both have C3 v symmetry in gas phase), the comparison o f their photoelectron spectroscopy data should be meaningful, particularly with regard to seeking the possible reasons behind the reactivity differences of the Cn and phosphine-coordinated organorhodium complexes. XPS of H ard and Soft-Ligated Organorhodium Complexes In a photoelectron experiment, a photon (hv) provides the energy to eject an electron from a bound state. By measuring the kinetic energy of the ejected electron (Ek), the ionization energy (El ) can be obtained as Ej = hv - Ek. Core electron X-ray photoelectron spectroscopy (XPS) has been found to be a powerful tool in characterizing ligand effects in transition metal complexes.55* 5 6 In simple terms, relatively electron-donating ligands will lower the binding energies of the core level electrons and relatively electron- withdrawing ligands will raise the binding energies of the core level electrons. A quantitative understanding of ligand effects in transition metal complexes provides insight into their reactivity especially for those reactions that depend on the electron richness or electrophilicity of the transition metal center.57’5 8 In this chapter, the characterization of hard and soft-ligated organorhodium 189 this chapter, the characterization of hard and soft-ligated organorhodium complexes by XPS will be discussed. These complexes include CnRhMe3.n Xn (n = 0, 1, 2, 3; X = Cl", B r, OH", OTf“), 3PRhMe3.n Xn (n = 0, 1, 2; X = OTf“) and (PMe3)3RhMe3.nXn (n = 0, 1, 2; X = Cl“). The Rh(3d5 /2) and Rh(3d3/2) binding energies of the these organorhodium complexes were measured on a PHI-548 X-ray Photoelectron Spectrometer. The binding energies of all the organorhodium complexes are listed in Table 3.1. The Rh(3d5 /2) binding energy is the most reliable since its signal intensity is the highest. Starting with CnRhMe3 (Rh(3d5 /2) = 306.9 eV) replacement of methyl with chloride results in a 0.7 eV increase in binding energy for CnRh(CH3 )2Cl (307.6 eV) and a further increase by 0.7 eV for CnRhMeCl2 (308.3 eV). An additive effect of replacement of methyl by chloride ligands was previously reported for a serious of zirconocene derivatives where sequential replacement of methyl by chloride in Cp2ZrMe2 (Zr(3d5/2) = 180.7 eV) resulted in a 0.5 eV increase for each chloride5 9 (i.e. Cp2ZrMeCl, 181.2 eV, and Cp2ZrCl2, 181.7 eV). However, replacement of the final methyl ligand in CnRhMeCl2 by chloride results in a 1.0 eV increase in binding energy for CnRhCl3 (309.3 eV) which is greater than the 0.7 eV change for the two preceding complexes in the series. Replacement of a methyl ligand by a triflate ligand results in a 1.2 - 1.3 eV increase in the Rh binding energy which is much greater than the 0.7 eV effect of the chloride ligand (Table 3.1). This is attributed to the weak coordinating ability of the triflate ligand1 8 > 3 1 » 6 0 which makes it a poor electron 190 donor and creates a higher effective positive charge at the rhodium center. For CnRhMe2OTf and CnRhMe(OTf)2, the effect of replacement of methyl by Table 3.1 Effect of CH3 ", Cl", B r, OH" and CF3SO3" ligands on the Rh(3d5/2) and Rh(3d5/2) binding energies of organorhodium complexes. Compound Binding Energy (± 0.1 eV) Rh(3d5 /2) ^(3^3/2) CnRhMe3 306.9 311.7 CnRhMe2Cl 307.6 312.3 CnRhMeCl2 308.3 313.0 CnRhCl3 309.3 314.0 CnRhMe2OTf 308.2 313.0 CnRhMe(OT f) 2 309.4 314.1 CnRhMe(OH)(OT f) 308.6 313.3 CnRhMe(OH) 2 307.7a [CnRhMe2 (CO)]OTf 309.5 314.2 CnRhMe2Br 307.6 312.4 CnRhMeBr2 308.3 313.0 CnRhBr3 309.0 313.7 3PRhMe3 307.5 312.0 3PRhMe2OTf 308.3 313.0 3PRhMe(OTf) 2 309.2 313.9 fac-(PMe3)3RhMe3 b b mer-(PMe3 ) 3 RhMe2Cl 308.3C 312.9C mer-(PMe3) 3RhMeCl2 308.4 313.0 a. Value extrapolated from the XPS data of complexes 1, 2 and 32. b. Irreproducible results due to decomposition of the sample. c. Sample was contaminated with mer-(PMe3)3RhMeCl2 which may lead to a skewing to higher binding energy. 191 triflate on the rhodium binding energy is additive. We were not able to prepare CnRh(OTf) 3 in pure form. The CnRhMe(OH)(OTf) complex (Rh(3d5/2) = 308.6 eV) turns out to be less electron rich than CnRhMe2OTf (308.2 eV) and more electron rich than CnRhMe(OTf) 2 (309.4 eV) which indicates that a hydroxyl group is more electron withdrawing than a methyl group (by 0.4 eV) and less electron withdrawing than a triflate group (by 0.8 eV). If the effect of replacement of methyl by hydroxyl on the rhodium binding energy is additive, then the Rh(3d5/2) binding energy of CnRhMe(OH) 2 would be 307.7 eV based on extrapolation. If it is true, the CnRhMe(OH ) 2 complex would be more electron rich than CnRhMe2 OTf, CnRhMeOHOTf and CnRhMe(OTf) 2 by 0.5 eV, 0.9 eV and 1.7 eV, respectively. In the case of [CnRhMe2(CO)]OTf, its higher binding energy (309.5 eV) by 1.3 eV compared to that of CnRhMe2OTf (308.2 eV) is attributed to the n- acidic character of the CO ligand and the overall cationic charge on the complex. The binding energies of bromo substituted complexes CnRhMe2Br (307.6 eV) and CnRhMeBr2 (308.3 eV) suggest that the bromide ligand has the same effect on the rhodium binding energies as the chloride ligand. The difference of the electronegativities of Cl (3.2) and Br (3.0) suggests the bromide complexes should have lower binding energies than the chloride complexes. This was shown in a series of dihalotitanocene derivatives where the bromide complexes were 0.1 - 0.3 eV lower in bonding energy than the corresponding chloride complexes. 6 1 > 6 2 However, there are also a few reports 192 where the trend goes in the other direction.6 2 6 3 It is possible that the small difference between the electronegativities of Cl and Br is not enough to produce a significant effect on metal binding energies in the CnRh system. The important absorption peaks in XPS of CnRhBr3 are shown in Figure 3.5. As fac-(PMe3 )3RhMe3, 36 is not stable under XPS condition, the binding energy of 36 determined at room temperature or at liquid nitrogen temperature varied irreproducibly. For mer-(PMe3 )3 RhMe2Cl, 37, a value of 308.3 eV was obtained which is suspect as the sample was contaminated by a small amount of mer-(PMe3 )3 RhMeCl2, 38. Complex 38 gave a value of 308.4 eV which is the same within experimental error as CnRhMeCl2, 7. This result suggests that the net effect of a-donating and 7i-accepting of the three phosphines to the rhodium center in mer-(PMe3 )3 RhMeCl2, 38 is the same as the a-donating effect of facially coordinated Cn in 7. The chelated phosphine complex 3PRhMe3, 39, on the other hand, shows good stability under the experimental conditions of XPS. The binding energy (Rh(3d5/2)) of 39 (307.5 eV) suggests that 39 is less electron rich than CnRhMe3 , 1 (306.9 eV). The Cn ligand is 0.6 eV more electron donating than the net effect of a-donating and ^-accepting of the 3P ligand through coordination with the "RhMe3" species. Complex 3PRhMe2OTf, 40 (308.3 eV), on the other hand, is only 0.1 eV less electron rich than CnRhMe2OTf, 2; and complex 3PRhMe(OTf)2, 41 (309.2 eV), is even 0.2 eV more electron rich I than CnRhMe(OTf)2. These results indicate that when the electron density on : i rhodium is relatively high, Cn is more electron donating than the net effect of | the 3P ligand; but when the electron density on rhodium is relatively low, Cn N(E), counts sec * (1-0 195 190 185 180 175 170 165 160 155 320 318 316 314 312 310 308 binding energy, eV ^ Figure 3.5 The Rh(3d3 /2 ) and Rh(3d5 /2 ) XPS absorption bands of CnRhBr3. v o . ■ ................................ ................................ is less electron donating than the net effect of the 3P ligand. The reason for this is that phosphines are both electron donor (through a) and electron acceptor (through it).6 4 In the case of 3PRhMe3 , since the electron density on rhodium is relatively high, the n-back bonding from rhodium 7t-symmetry electrons to phosphines is probably significant while for 3PRhMe(OTf)2, since the electron density on rhodium is relatively low, the 7c-back bonding from rhodium % - symmetry electrons to phosphines is probably not as significant. As amines are considered not to be rc-acidic64, the XPS data suggests that 3P ligand is a stronger a-donor than Cn. In a sense, due to the fact that phosphines are both a -donor and 71-acceptor, the 3P ligand effects the binding energy of rhodium in a flexible way while Cn does not. Note that it is hard to separate the a and n interactions of the phosphines.6 4 Based on the XPS data of the CnRh complexes, the effect of the anionic ligands in this system on increasing metal binding energy is ranked in the following order: CH3 ” < OH” < Br" = Cl” < OTf”. The higher binding energies of the triflate substituted complexes are consistent with the weakly coordinating nature of the triflate group and the fact that triflate can be easily replaced by CO, C2H4, H20 and other neucleophiles. The XPS data of the CnRh complexes also offer valuable evidence about the basicity of the methyls on rhodium in these complexes and help to explain the hydrolytic stabilities of some CnRh complexes in water (Chapter 2), as well as the correlation of the rhodium carbon coupling constants of various CnRh complexes with the electron richness of the rhodium center (Chapter 1). An interesting observation in the study of the 3PRh complexes is that the 3P ligand effects the electron density of 195 Rh(3d5 /2 ) Binding Energy (eV) N N N : K \ / > Rh ; l / ^ M e M e i -306.5 -307- -307.55 (Cl, Br) Me1 (Cl, Br) -308.5- M e2p*PMe2 PM e2 ' *A / Rh / i \ . -309- M e MeM e RhCI3 -309.5- -310 n for L3 RhMe(3 .n )Xn ^ : Figure 3.6 Diagram of the XPS data of CnRh and 3PRh complexes. v o OV rhodium in a flexible way while the Cn ligand does not. The diagram of the XPS data of CnRh complexes and 3PRh complexes is shown in Figure 3.6 where the effects of different substituents and degree of substitution can be clearly seen. UPS of H ard and Soft-Ligated Organorhodium Complexes In XPS experiments, high energy photons (hv commonly greater than 1000 eV) are applied to eject electrons primarily from atomic core levels.65 In UPS experiments, low energy photons (hv commonly less than 50 eV) are utilized to eject the electrons primarily from the valence shell.6 5 Thus, UPS offers information about both electron richness and bonding of molecules. For transition metal complexes, the valence spectra often clearly reflect the basic d electron configurations and electronic symmetry at the metals. The most useful and widely used light source in UPS is a discharge in pure helium which gives the He I resonance line at 584 A, equivalent to a photon energy of 21.22 eV, as its main output.66 The He I light is energetic enough to cause ionization of the majority of valence electrons. Discharges in pure helium can also generate a series of lines from ionized helium, He II, with the main line at 303 A, equivalent to a photon energy of 40.81 eV.66 The most widely used experimental technique for identifying predominant metal character in ionizations of organometallic complexes takes advantage of the different relative ionization band intensities obtained with the He I and He II excitation sources.6 5 Main group (C, N, etc.) s and p orbitals generally show relatively large He I intensities and relatively small He II intensities in comparison to 197 transition metal d orbitals.65 For organometallic complexes, this empirical relationship of relative He I and He II ionization band intensities provides an invaluable experimental indication of orbital metal or ligand character in the ionization.6 5 The UPS data of CnRhMe3 are very informative about the bonding and symmetry of this molecule. As shown in Figure 3.7 and 3.8, by changing the light source from He I to He II, the relative intensity of the peaks at 6.17 and 6.44 eV increases dramatically, an indication that they result from ionizations of the 4d6 rhodium lone pair electrons (a and e in symmetry); meantime the peaks at 7.90, 9.99, and 10.88 eV all decrease in relative intensity, an indication that they result from ionizations of C and N bonding electrons; in fact, these peaks correspond to Rh-C, Rh-N and C-H, respectively (table 3.2). Peak parameters for CnRhMej. The N lone pair ionization data for the free Cn ligand is quoted within parantheses. Position (eV) Assignment Width High Width Low Relative Intensity He I H en 6.17 < * z2 0.27 0.17 1.00 1.00 6.44 ^X y»dx2-v2 0.27 0.21 2.02 1.93 6.66 vibrational 0.37 0.21 0.30 0.41 7.90 Rh-C bonds 0.96 0.80 4.44 2.52 9.99 (7.66,8.25)* Rh-N bonds (N lone pair) 1.06 (0.72,0.72) 0.81 (0.72,0.72) 6.35 2.50 10.88 C-H bonds 0.90 0.90 4.86 1.34 *The numbers in parentheses correspond to N lone pair ionization in the free "Cn" ligand. Table 3.2 Peak parameters for CnRhMe3. 198 CnRhMe3 He I H en 5 15 11 13 9 7 Ioni ration Energy (eV ) Figure 3.7 He I and He II of CnRhMe3 in the region 15-5 eV. 199 CnRhMe3 Hen 6 9 8 7 Ion ization E nergy (eV ) n l i | Figure 3.8 He I and He II of CnRhMe3 in the region 9-6 eV. The two metal ionizations are at 6.17 (a, (^2) and 6.44 eV (e, (1 * 2 _ y 2). This result is consistent with the C3 v symmetry of this molecule. As non bonding electrons in a molecule give their typical sharp absorptions due to the lack of bond distance change from the ground state to the excited state, the sharp peaks of the 4d6 electrons of CnRhMe3 indicate that the metal ionizations of CnRhMe3 are almost completely non-bonding. This observation is consistent with the fact that hard-ligated amines are considered not to be 7t-acidic. This is the first example of such non-bonding character that can be observed in organorhodium complex. The observation of such non-bonding character is unusual for organotransition metal compounds.6 7 The photoelectron spectra of free Cn ligand are shown in Figure 3.9. As shown in Table 3.2, the N lone pair ionization has stabilized in the complex by about 1.8 eV. The PMe3-coordinated complex fac-(PMe3 )3 RhMe3 was found to decompose during heating under vacuum, thus the measurement of fac- (PMe3 )3RhMe3 did not go as well. Although the He I spectrum of it showed the broad absorption of the 4d6 electrons of rhodium which is in accord with the bonding nature of the 4d6 electrons, the data are not reliable. Complex 3PRhMe3 is very stable under the experimental conditions of UPS. As shown in Figure 3.10 and 3.11, the first broad band between 6.0-9.0 eV increases in intensity when the source is changed from He I to He II indicating that this is predominantly metal in character (4d6 of Rh). The shape of the peaks of 4d6 rhodium electrons of 3PRhMe3 are much broader than that of CnRhMe3 indicates that the 4d6 electrons of rhodium in 3PRhMe3 have 201 Free Cn ligand i i i i I I y i v i V I 16 14 12 10 8 6 Ionization E nergy (eV) Figure 3 .9 He I photoelectron spectra o f the free Cn ligand. The full valence region and the close-up o f the N lone-pair regions are shown. The latter is fit with two bands. ' 202 HC(Me2 PCH2 )3 RliMe3 He I 16 14 10 12 8 6 Io n iza tio n . E n ergy (e V ) Figure 3.10 He I and He II of 3PRhMe3 in the region o f 16-6 eV. HCCMejPCH^RhM^ He I 6 9 8 7 If Ion izaticm E n ergy (e V ) | Figure 3.11 He I and He II of 3PRhMe3 in the region of 9-6 eV. 204 P lane pair 16 14 12 10 8 6 Io n iz a tio n E n erg y (e V ) Figure 3.12 He I of the free 3P ligand. bonding character, that is, rhodium can back bond to the 3P ligand. It seems that the first broad band between 6-9 eV is composed by two bands of 4d6 j rhodium electrons that are located at 6.95 eV (a band) and 7.69 eV (e band) as shown in Figure 3.11. The ionization energies (6.95 and 7.69 eV) of the i valence rhodium electrons are higher than that of the CnRhMe3 (6.17 and 6.44 j eV), indicates again that 3PRhMe3 is less electron rich than CnRhMe3. This |iresult is in agree with the XPS results of 3PRhMe3 and CnRhMe3. 1 The He I spectrum of free 3P ligand is shown in Figure 3.12. The [| | | assignment of additional absorption peaks of 3PRhMe3 is currently in progress. i ! j 205 Conclusions The Rh(3d5/2) and Rh(3d3/2) binding energies of the CnRh and 3PRh complexes were measured by XPS. The effect of the anionic ligands in this study on increasing metal binding energy is ranked in the following order: CH3 " < OH" < Br" = Cl" < OTf". The higher binding energies of the triflate substituted complexes are consistent with the weakly coordinating nature of the triflate group and the fact that triflate can be easily replaced by CO, C2H4, H20 and other neucleophiles. The XPS data of the CnRh complexes also offer valuable evidence about the basicity of the methyls on rhodium in such complexes and help to explain the protolytic stabilities of some CnRh complexes in water (Chapter 2), as well as the correlation of the rhodium carbon coupling constants of various CnRh complexes with the electron richness of the rhodium center (Chapter 1). An interesting observation in the study of the 3PRh complexes is that the 3P ligand effects the electron density of rhodium in a flexible way while the Cn ligand does not. This might be one of the fundamental differences of hard and soft ligands. The UPS study of CnRhMe3 indicates that the two metal ionizations are almost completely non-bonding. This is the first example of such non-bonding character that can be observed in organorhodium compounds, and is unusual for organotransition metal compounds. The UPS study of 3PRhMe3 reveals that the metal ionizations are at least partially bonding, this is consistent with the fact that phosphines are both a-donor and 7i-acceptor ligands. Both XPS and UPS studies have suggested that the rhodium center of CnRhMe3 is more electron rich than that of 3PRhMe3. 206 To try to fully understand the reactivity differences of CnRh and its phosphine-ligated rhodium analogs, more efforts are currently underway on the XPS and UPS studies of the two series of hard and soft-ligated organorhodium complexes and on the comparative chemistry of the two types of systems. Experimental General See Chapter 1. XPS Experiments: The Rh(3d5/2) and Rh(3d3 /2) binding energies of all the organorhodium complexes were measured on a PHI-548 X-ray Photoelectron Spectrometer by using Mg K a X-rays. Approximately 0.5 mg of compound was dissolved in CH2C12 solvent (~ 1 mL) in a glove box under a nitrogen J atmosphere. A few (3-4) small drops of the solution were evaporated onto a polyethylene coated aluminium chip (1X1 cm) to form a thin layer of the metal complex on the polyethylene surface. The complexes which were not soluble in CH2C12 were pressed onto a polyethylene chip as powders. The Cls binding energy of polyethylene which has a value of 284.6 eV was used as an internal reference. None of the samples sublime, thus, all spectra were recorded at room temperature. At least three separate runs of each compound were performed on separate samples. The binding energy values are reported as the average of the runs with a maximum error of ± 0.1 eV. j Synthesis of (PMe3)3Rh and 3PRh Complexes | fac-(PMe3)3RhM e3 The synthesis of this compound was reported,5 2 and | proceeds well without modification. 207 m er-(PM e3)3RhM e2Cl To a stirring solution o f 80 mg (0.213 mmol) (PMe3 )3 RhMe3 in 8 mL of CH2C12 at -78 °C, 0.276 mL of 0.770 A T (0.213 mmol) HC1 ether solution was slowly added under nitrogen. Ten minutes after completion of the addition, this solution was allowed to warm to RT slowly and was stirred at this temperature for 30 minutes. Solvents were removed under vacuum. The yellow solids were vacuum dried for 3 h. The conversion was quantitative based on rhodium. !H NMR (C6D6 ): 5 -0.14, 0.54 (m, RhCH3 ), 1.00, (d, JPH = 6.4 Hz, lP(C tf3 )3 ), 1.15 (t, JPH = 3.0 Hz, 2P(C//3 )3 ). 3ip(iH} NMR (C6D6): 8 -21.39 (dt, Jr^ = 85.1 Hz, JPP = 29.2 Hz, lPM e3 ), -5.52 (dd, jRhP = 109.5 Hz, JPP = 29.2 Hz, 2PMe3 ). m er-(PM e3)3RhM eCl2 The procedure was the same as the last one except that 2 eq of HC1 was used in this case. The transformation was quantitative based on rhodium. Yellow colored product was obtained. !H NMR (C6D6): 8 0.61 (m, RhCtf3 ), 0.90 (d, JPH = 9.8 Hz, lP(Ci73 )3 ), 1.31 (t, JPH = 3.5 Hz, 2P(CH 3 )3 ). 31P{1 H}NMR (C6D6): 8 -8.26 (dd, J r ^ = 96.7 Hz, JP P = 32.4 Hz, 2PMe3 ), 8.01 (dt, Jrhr = 135.7 Hz, JPP = 32.4 Hz, lPM e3 ). Tetram ethyldiphosphine68 (Caution: Tetramethyldiphosphine ignites spontaneously in air.) First 18.6 g (0.100 mol) tetramethyldiphosphine disulphide and 36.0 g (0.645 mol) iron powder (hydrogen reduced, 97%, ~ 325 mesh, Aldrich) were mixed in a mortar. They were subsequently transferred to a 100 mL RB flask equipped with a short Vigreux column distillation apparatus with a 50 mL Schlenk flask as the receiver. This system was evacuated and refilled with nitrogen twice. Under nitrogen, the mixture was heated by the 208 weak flame of a Bunsen burner. The disulfide salt melted and the tetramethyldiphosphine product was generated and started to reflux. After heating at reflux for 10 min, stronger flame was applied and the product was distilled at 138-164 °C. The product in the Schlenk flask was frozen in a dry ice-acetone bath. The schlenk flask was quickly removed from the distillation apparatus under positive nitrogen flow and capped right away. The product amounted to 11.7g (96%) of colorless liquid. 1 HNMR (C6D6): 5 0.93 (vt). 3 1 P{1 H}NMR (C6 D6 ): 8 -57.97 (s). l,l»l-T ris(chlorom ethyl)ethane With a drying tube on the top of the constant pressure addition funnel, 105 mL (1.32 mol) of pyridine was mixed with 34.2g (0.285 mol) of l,l,l-tris(hydroxymethyl)ethane in a 500-mL RB flask. Under stirring, 125 mL (1.71 mol) of thionyl chloride was slowly added. Addition was finished in 3 hours of reflux, followed by 3 hours of reflux, resulting in a dark red solution. To the room temperature solution, 100 mL of cold water was slowly added and 150 mL of pentane was used to extract the product. This resulted in the formation of gray precipitates which were subsequently collected on a filter and washed twice with 50 mL of pentane. The pentane layer was separated by separatory funnel. The aqueous solution was further extracted with 2x100 mL of pentane. The pentane solutions were combined, washed with 100 mL of water, then 100 mL of Na2C 0 3 water solution, and finally 2x100 mL of water. Pentane was evaporated under reduced pressure and the red brown residue was distilled under vacuum; 40 g (80%) of colorless product was collected at 60 »C/5mmHg. 1 HNMR (C6D6): 8 0.70 (s, CH 3 ), 3.02 (s, 3C/72). 1 3 C{1 H}NMR (C6 D6): 8 18.82 (s, CH3), 41.63 (s, CH3CR3 ), 48.10 (s, 3CH2). 209 I,l,l-Tris(dim ethylphosphinom ethyl)ethane. (The first part o f this experiment was carried out under argon.) Under oil protection, 2.61 g (0.377 mol) lithium rod was pounded by hammer on the lab bench to flakes. The flakes were transferred to a 250-mL 2-necked flask with a condenser and argon atmosphere. The flakes were washed with 3x45 mL of ether, then 30 mL of THF. Then 60 mL of THF was added to the system, followed by cannulation of II.5 g (0.0942mol) tetramethyl diphosphine , then 3x20 mL THF wash. With stirring, the reaction initiated in about 5 mins. The color of the solution turned bright yellow. After stirring at RT for 20 mins, the mixture was heated at reflux for 4 hrs. A cloudy bright yellow solution was obtained with (excess) lithium flakes floating on the top. The lithium dimethylphosphide solution was cannulated and filtered through a large filter (40-60pm pore) to a 250-mL RB flask which was equipped with distillation apparatus with a 250 mL Schlenk flask as receiver. The residue was washed with 3x10 mL THF and transferred to the same flask by filtering. This flask was then cooled in an ice water bath. To this 0 °C solution, 8.25 g (0.0470 mol) of l,l,l-tris(chloromethyl) ethane was slowly added, during which time the color of the solution became pale buff. Addition was finished in 35 min. This mixture was then allowed to warm up to RT and stir overnight. THF was distilled from the reaction mixture at atmospheric pressure. The residue was distilled at reduced pressure (0.15 mmHg) until the flask was almost dry. The mixture was redistilled. The 39 °C/0.2mmHg portion was the colorless unreacted trichloride. A second fraction, 5.0g (48% overall yield), of bright yellow colored liquid was collected at 74-77 °C/0.2mmHg. 1 HNMR (C6D6): 8 0.91 (d, JPH = 2.9Hz, P(C//3 )2), 1.15 (s, CH3 ), 1.71 (d, JP H = 3.5Hz, CH2). 3 1 P{!H}NMR (C6 D6): 8-61.54 (s). 210 3PRhM e3 First 20 mL of deoxygenated ethanol was used to dissolve 1.00 g (3.80 mmol) of RhCl3.3H20 in a 100-mL 2-necked RB flask which was equipped with a condenser. Under nitrogen, 15 mL of an ethanol solution of 3P (1.13 mL 3P in 14 mL ethanol) was slowly added to the dark red solution of RhCl3 with stirring. This resulted in immediate precipitation of light yellow solids. Addition was finished in 10 mins. The mixture was allowed to stir at RT for 20 min and then was heated at reflux for 6 hours. The room temperature mixture was filtered in air. The yellow solid was washed with 3x8 mL of ethanol, then 3x8 mL of ether, and 3x8 mL of pentane, and then vacuum dry to yield 1.42g yellow solid. This solid (presumably 3PRhCl3 ) was mixed with 0.507 g CH3Li (80% by weight), 35 mL of THF was added and the mixture was stirred. Reaction initiated in ca. 2 min, whereupon the color of the solution turned red brown and the solution became homogeneous. This was allowed to stir at RT for 1 day. Wet THF was slowly added to the reaction mixture with stirring until bubbling ceased. Solvent was evaporated . The residue was extracted with stirring by 70 mL of benzene under reflux for 40 min. The room temperature solution was filtered, and the residue was washed with 3x5 mL benzene. Evaporation of benzene gave 0.33 g of a light yellow mixture of 80% 3PRhMe3 and 20% 3PRhMe2Cl. This was further treated with 90 mg of CH3 Li (80% by weight) in 12 mL of THF with stirring for 1 day. Workup as just mentioned yielded 0.23 g (15%) of snow white product. The residue of the first benzene extraction was extracted with 75 mL of CH2C12 at RT for 1 hour. The solution was filtered and the solvent was evaporated, and 0.35 g of yellow solid was obtained (partially 3PRhMe2Cl). This was treated 211 with 0.20 g of CH3 Li (80% by weight) in 12 mL of THF and stirred for 1 day. The workup procedure was as usual. From this 0.14 g (9%) light yellow product was obtained (The color was due to contamination by a trace amount of 3PRhMe2Cl, but the product was quite pure enough for most purposes.) Combined yield: 0.37g (24% based on Rh). 1HNMR(C6 D6): 8 0.45 (m, Rh(Ctf3 )3 ), 0.59 (q, JP H = 2.5Hz, CH3), 0.69 (q, CH2), 0.94 (t, P(C//3 )2). 31P{1 H}NMR (C6D6): 8-11.93 (d, J r ^ = 77.9 Hz) Anal, calcd for C1 4 H36P3 Rh: C, 42.01; H 9.07. Found: C, 42.34; H, 9.06. 3PRhM e2O Tf To a stirring solution of 0.100 g (0.250 mmol) 3PRhMe3 in 10 mL CH2C12 at -78 °C, 0.337 mL of a 0.705 N (0.237 mmol) triflic acid ether solution was slowly added under nitrogen. The color of the solution turned milky white during the addition. Then 5 min after completion of the addition, the solution was allowed to slowly warm to RT and was stirred at this temperature for 40 min. The solvent was then reduced to ca. 2 mL under reduced pressure and 15 mL of pentane was added by syringe to induce precipitation of the product. The mother liquor was removed by cannula, and the solid was washed with pentane (2x15 mL). The solid was dried under vacuum for several hours; 0.116g (91%) milky white solid was obtained. 1 HNMR (CD3SOCD3 ): 8 -0.06 (Rh(C/f3 )2), 1.12 (CCH 3 ), 1.36, 1.41, 1.52, 1.66 (CH2,? C H 3). 3 1 P{1 H}NMR (CD3SOCD3 ): 8-18.27 (dd, J r ^ = 74.5 Hz, JP P = 35.4 Hz, 2P(CH3 )2), 8 14.56 (dt, J r ^ = 113.8 Hz, JP P = 35.4 Hz, 1P(CH3 )2). Anal. Calcd for C1 4 H33P3 F3S 0 3 Rh: C, 31.47; H, 6.23. Found: C, 31.21; H, 6.38. 212 3PRhMe(OTf)2 A solution of triflic acid in ether (0.691 mL of a 0.705 N solution, 0.487 mmol) was slowly added to a stirring solution of 0.100 g (0.250 mmol) of 3PRhMe3 in 10 mL of CH2C12 in a Schlenk flask under nitrogen at - 78 °C. The solution became cloudy during the addition. Five min after the completion of the addition, the solution was allowed to slowly warm to RT and the mixture was stirred at this temperature for 50 min. The white precipitates were allowed to settle and the mixture was cooled to 0 °C. The supernatant was removed by cannula. The residue was allowed to warm to RT and 15 mL of benzene was added. The supernatant was again removed by cannula and the solid was washed again with 15 mL of benzene. The resulting solid was dried under vacuum for several hours; 0.143g (91%) of snow white solid was obtained. 1 HNMR (CD3SOCD3 ): 5 0.63 (RhC//3 ), 1.18(CCtf3 ), 1.39, 1.56, 1.76, 1.81(CH2, PCH3 ). 3ip{iH}NMR (CD3 SOCD3 ): 5 -13.33 (dt, J^p = 71.2 Hz, JpP = 28.7 Hz, 1P(CH3 )2), 33.55 (dd, J r ^ = 122.6, JPP = 28.6 Hz, 2P(CH3 )2). Anal. Calcd for C1 4 H3 0 P3 F6S2O6Rh: C, 25.16; H, 4.52. Found: C, 25.62; H, 4.53. Data X-ray data: From page 214 to page 224. 213 Table 1: Summary of Crystal Data and Refinement Results for fac-(PMe3 )3 RhMe3 molecular weight(g/mole) 376.24 space group P21 /n molecules per unit cell 4 a (angstrom) 9.436 b (angstrom) 13.724 c (angstrom) 15.413 a(deg) 90.00 P(deg) 93.89 7<cleg) 90.00 V (angstrom3) 1991.38 crystal dimensions (mm) x o.$- calculated density (g cm '3) 0.756 wavelength (angstrom) used for data collection 0.71069 Sine/1 limit (angstrom 1) 0.5947 total number of reflections / S '/? m easured number of reflections used in structural analysis I > 3o(l) 1519 number of variable param eters 262 final agreem ent factors R(F) = 0.0452 R(wF) = 0.0494 Table 2: Final Atomic C oordinates for fac -(P M e 3 ) 3 RhMe3 Atom X y z RH 0.5674( 1) 0.2626( 1) 0.8215( 1) P2 0.4381(3) 0.2759( 3) 0.9446( 2) P3 0.4600( 4) 0.1210( 2) 0.7641 ( 2) P4 0.7668( 3) 0.1866( 3) 0.8889( 3) C5 0.6906(14) 0.2794(11) 0.7111(9) H51 0.6270(21) 0.3209(20) 0.6629(20) H52 0.7139(21) 0.2073(20) 0,6850(20) H53 0.7887(21) 0.3160(20) 0.7313(20) C6 0.4115(13) 0.3392(10) 0.7429( 9) H61 0.3100(21) 0.3344(20) 0.7718(20) H62 0.4444(21) 0.4133(20) 0.7362(20) H63 0.4013(21) 0.3036(20) 0.6782(20) C7 0.6470(14) 0.4037( 9) 0.8576( 9) H71 0.7312(21) 0.4218(20) 0.8145(20) H72 0.6931(21) 0.4001(20) 0.9232(20) H73 0.5618(21) 0.4550(20) 0.8514(20) C8 0.2876(13) 0.3600(10) 0.9384(10) H81 0.2641(21) 0.3809(21) 1.0023(21) H82 0.1956(21) 0.3246(21) 0.9048(21) H83 0.3135(21) 0.4236(21) 0.9007(21) C9 0.3488(13) 0.1702(10) 0.9888( 9) H91 0.2878(21) 0.1336(21) 0.9361(21) H92 0.2796(21) 0.1953(21) 1.0361(21) H93 0.4281(21) 0.1216(21) 1.0168(21) C10 0.5280(14) 0.3220(12) 1.0417(10) H101 0.6224(21) 0.2784(21) 1.0565(21) H102 0.4593(21) 0.3143(21) 1.0940(21) H103 0.5552(21) 0.3966(21) 1.0315(21) C11 0.4833(12) 0.0022( 9) 0.8167( 9) H111 0.4624(21) 0.0090(21) 0.8832(21) H112 0.5906(21) -0.0215(21) 0.8109(21) H113 0.4117(21) -0.0481(21) 0.7851(21) C12 0.5015(14) 0.0835(11) Q.6538( 9) H121 0.4933(21) 0.1459(21) 0.6112(21) H122 0.4279(21) 0.0278(21) 0.6304(21) H123 0.6087(21) 0.0562(21) 0.6566(21) C13 0.2666(13) 0.1238(10) 0.7467(10) H131 0.2230(21) 0.1447(21) 0.8070(21) H132 0.2286(21) 0.0533(21) 0.7272(21) H133 0.2367(21) 0.1762(21) 0.6960(21) C14 0.7538(14) 0.1049(11) 0.9825(10) H141 0.6942(21) 0.1408(21) 1.0310(21) H142 0.8590(21) 0.0885(21) 1.0099(21) H143 0.6997(21) 0.0393(21) 0.9613(21) C15 0.8691(14) 0.1074(12) 0.8220(11) H151 0.9028(21) 0.0451(21) 0.8593(21) H152 0.9592(21) 0.1484(21) 0.7997(21) H153 0.8035(21) 0.0848(21) 0.7650(21) C16 0.9065(13) 0.2663(12) 0.9347(10) H161 0.9823(21) 0.2241(21) 0.9729(21) HI 62 0.8608(21) 0.3205(21) 0.9733(21) H163 0.9572(21) 0.3009(21) 0.8817(21) 215 Table 3: Tem perature Factors for fac-(P M e3)3RhM e3 Atom U^XIO3 U22X103 U33X103 U12X103 U1 3X103 u 23x io 3 RH 58( 0) 45( 0) 48 ( 0) •7( 1) 14( 0) 7( 1) P2 66( 1) 68( 2) 68( 1) 8( 1) 23(1) -9( 1) P3 66< 2) 66( 1) 56 ( 1) -3( 1) -11( 1) *4( 1) P4 44( 1) 92( 2) 92( 2) -3( 1) 4(1) -18( 2) C5 H51 H52 H53 134( 2) 53{ 2) 52( 2) 54{ 2) 130( 2) 97( 2) -14( 2) 56( 2) 2( 2) C6 H61 H62 H63 122( 2) 53( 2) 53( 2) 55(2) 95( 2) 107( 2) 19( 2) -22( 2) 23( 2) C7 H71 H72 H73 127( 2) 54( 2) 54( 2) 53 ( 2) 76( 2) 114( 2) -15( 2) 18( 2) 0(2) C8 H81 H82 H83 89( 2) 21000( 2) 21000( 2) 21000( 2) 111(2) 131(2) 17( 2) 52( 2) -8( 2) C9 H91 H92 H93 125( 2) 21000( 2) 21000( 2) 21000( 2) 112( 2) 92( 2) *14( 2) 49( 2) 10( 2) C10 H101 H102 H103 124( 2) 21000( 2) 21000( 2) 21000( 2) 151(2) 104( 2) 3( 2) 11( 2) -38( 2) C11 H111 H112 H113 94( 2) 21000( 2) 21000( 2) 21000(2) 70( 2) 99( 2) •17( 2) -10( 2) •4( 2) C12 H121 H122 H123 136( 2) 21000( 2) 21000(2) 21000( 2) 115(2) 97 ( 2) 1(2) 3( 2) -25( 2) C13 H131 H132 H133 84( 2) 21000( 2) 21000( 2) 21000( 2) 113( 2) 133( 2) -5( 2) -14( 2) -20( 2) C14 H141 H142 H143 121 ( 2) 21000( 2) 21 G00( 2) 21000( 2) 119{ 2) 127( 2) 20( 2) -28( 2) 23(2) C15 H151 H152 H153 110( 2) 21000( 2) 21000( 2) 21000( 2) 149( 2) 149( 2) 33(2) 18( 2) -29( 2) C16 H161 H162 H163 106( 2) 21000( 2) 21000( 2) 21000( 2) 143( 2) 154{ 2) -12(2) -21 (2) -25( 2) The complete temperature factor is e x p ^ jt^ U ^ l^ a '2 + U22k2b*2 + UggFc*2 + 2U12hka*b* + 2U13hla*c* + 2U23klbV] Table 4: Bond D istances(angstrom s)for fac-(P M e3)3R hM e3 RH —P2 2.332( 3) RH —P3 2.337( 3) RH —P4 2.332{ 4) RH —C5 2.138(12) RH —C6 2.120(12) RH —C7 2.137(13) P2 —C8 1.827(12) P2 —C9 1.832(13) P2 — C10 1.786(14) P3 —C11 1.827(13) P3 —C12 1.844(14) P3 —C13 1.826(12) P4 —C14 1.837(15) P4 —C15 1.820(15) P4 — C16 1.819(14) C5 —H51 1.084(29) C5 —H52 1.095(30) C5 —H53 1.080(25) C6 — H61 1.086(26) C6 —H62 1.071(29) C6 —H63 1.108(32) C7 —H71 1.099(28) C7 —H72 1.074(30) C7 — H73 1.068(26) C8 —H81 1.063(33) C8 —H82 1.094(27) C8 — H83 1.085(32) C9 —H91 1.086(30) C9 — H92 1.068(30) C9 —H93 1.072(28) CIO —H101 1.085(26) CtO — H102 1.074(31) C10 —H103 1.070(31) C11 —H111 1.061 (33) C11 —H112 1.073(24) C11 —H113 1.061(27) C12 —H121 1.080(32) C12 —H122 1.078(28) C12 — H123 1.077(24) C13 — H131 1.081(33) C13 —H132 1.068(30) C13 —H133 1.086(32) C14 —H141 1.084(32) C 14—H142 1.076(24) C14 —H143 1.075(30) C 15—H151 1.067(32) C15 —H152 1.095(28) C15 —H153 1.086(31) C16 —H161 1.066(29) C16 —H162 1.062(32) C16 —H163 1.084(33) 217 Table 5: Bond Angles (deg) for fac-(PM e3)3Rh iV f e3 P2 -RH -P3 P2 -RH -P4 P3 -RH -P4 P2 -RH -C5 P3 -RH -C5 P4 -RH -C5 P2 -RH -C6 P3 -RH -C6 P4 -RH -C6 C5 -RH -C6 P2 -RH -C7 P3 -RH -C7 P4 -RH -C7 C5 -RH -C7 C6 -RH -C7 RH -P2 -C8 RH -P2 -C9 C8 -P2 -C9 RH -P2 -C10 C8 -P2 -C10 C9 -P2 -C10 RH -P3 -C11 RH -P3 -C12 C11 -P3 -C12 RH -P3 -C13 C11 -P3 -C13 C12-P3 -C13 RH -P4 -C14 RH -P4 -C15 C14-P4 -C15 RH -P4 -C16 C14-P4 -C16 C15-P4 -C16 RH -C5 -H51 RH -C5 -H52 H51 -C5 -H52 RH -C5 -H53 H51 -C5 -H53 H52-C5 -H53 RH -C6 -H61 RH -C6 -H62 H61-C6 -H62 RH -C6 -H63 H61 -C6 -H63 H62-C6 -H63 RH -C7 -H71 RH -C7 -H72 H71 -C7 -H72 RH -C7 -H73 H71 -C7 -H73 H72 -C7 -H73 97.8( 1) 97.1 ( 1) 96.5( 1) 169.2( 4) 91.9(4) 86.4( 4) 92.6( 4) 86.0( 4) 169.6( 4) 83.4( 5) 84.9( 4) 170.9( 4) 91.8( 4) 84,8( 5) 85.2( 5) 117.1 ( 5) 121.3( 5) 98.3( 6) 117.7( 5) 98.2( 7) 100.0( 7) 122.5( 4) 117.8(5) 97.7( 6) 116.2( 5) 100.0( 6) 98.2( 6) 121,9( 4) 117.2( 5) 98.4( 7) 116.5( 5) 98.5( 7) 100.4( 7) 107.2(16) 109.1(17) 109.8(25) 108.8(19) 112.1(24) 109.7(21) 109.4(18) 109.4(15) 111.5(23) 108.0(15) 108.5(22) 109.9(26) 107.6(18) 108.4(17) 108.4(22) 109.0(16) 111.5(24) 111.7(25) 218 fac-(PMe3 )3RhMe3 Table 5: (continued) P2 -C8 -H81 109.4(17) P2 -C8 -H82 109.4(17) H81 -C8 -H82 110.5(22) P2 -C8 -H83 109.5(14) H81 -C8 -H83 110.4(26) H82-C8 -H83 107.7(25) P2 -C9 -H91 108.8(18) P2 -C9 -H92 108.5(18) H91 -C9 -H92 110.0(22) P2 -C9 -H93 108.5(16) H91 -C9 -H93 109.4(24) H92-C9 -H93 111.6(25) P2 -C10-H101 108.5(19) P2 -C10-H102 108.5(17) H101-C10 -H102 108.5(26) P2 -C10-H103 108.7(20) H101-C10 -H103 111.0(22) H102-C10 -H103 111.6(26) P3 -C11 -H111 109.0(18) P3 -C11 -H112 108.6(18) H111-C11 -H112 110.2(23) P3 -C11 -H113 ' 108.8(18) H111-C11 -H113 110.3(24) H112-C11 -H113 109.8(23) P3 -C12-H121 109.2(19) P3 -C12-H122 109.6(19) H121-C12 -H122 109.9(24) P3 -C12-H123 108.6(20) H121-C12 -H123 109.2(23) H122-C12 -H123 110.4(23) . P3 -C13 -H131 108.3(15) P3 -C13-H132 109.6(15) H131-C13 -H132 110.0(25) P3 -C13-H133 109.2(15) H131-C13 -H133 110.4(25) H132-C13 -H133 109.3(25) P4 -C14-H141 109.3(19) P4 -C14-H142 109.1(19) H141-C14-H142 109.4(25) P4 -C14-H143 109.1(20) H141-C14 -H143 109.5(24) H142-C14 -H143 110.5(23) P4 -C15-H151 108.9(20) P4 -C15-H152 109.0(19) H151-C15 -H152 111.8(21) P4 -C15-H153 109.5(16) H151-C15 -H153 109.8(26) H152-C15 -H153 107.7(26) P4 -C16-H161 109.2(19) P4 -C16-H162 109.1(15) H161-C16 -H162 110.8(27) P4 -C16-H163 108.4(18) H161-C16 -H163 109.9(22) H162-C16 -H163 109.4(27) Table 1: Summary of Crystal Data and Refinement Results for RhP3Me3 (P3 = CH3 C(CH2 PMe2 )3 ) molecular weight(g/mole) 400.27 space group Pna21 (No. 33) molecules per unit cell 4 a (angstrom) 14.454(1) b (angstrom) 9.492(2) c (angstrom) 14.258(1) a(deg) 90.00 P(deg) 90.00 7(deg) 90.00 V (angstrom3) 1956.35(36) crystal dimensions (mm) 0.3 x 0.2 x 0.4 calculated density (g cm'3) 1.364 wavelength (angstrom) used for data collection 0.71069 Sine/a. limit (angstrom-1) 0.5947 total number of reflections measured 1402 number of reflections used in structural analysis 1 > 3o(l) 1202 number of variable parameters 163 final agreement factors R(F) = 0.0339 2 2 0 Table 2: Final Atomic Coordinates for RhP3Me3 Atom X y z RH 1 0.3320( 1) 0.5185( 1) 10.5000( 0) P 2 0.1876( 2) 0.42,16( 3) 0.5056( 4) P 3 0.3526( 2) 0.4152( 3) 0.3562( 3) P 4 0.2711(2) 0.7103( 3) 0.4253( 3) C 5 0.4683( 7) 0.6128(11) 0.5037(12) C 6 0.3965( 8) 0.3398(11) 0.5695( 9) C 7 0.3149( 9) 0.6055(12) 0.6391(9) C 8 0.0956( 8) 0.5106(12) 0.2339( 9) C 9 0.1647( 8) 0.5114(10) 0.3134( 7) C 10 0.1297( 8) 0.4100(11) 0.3888( 8) C 11 0.2612( 8) 0.4633(11) 0.2727( 8) C 12 0.1703( 8) 0.6682(11) 0.3505( 9) C 13 0.1725( 9) 0.2400(12) 0.5490(9) C 14 0.0976( 9) 0.5106(12) 0.5748( 9) C 15 0.3523( 9) 0.2218(11) 0.3517( 9) C 16 0.4565( 9) 0.4486(13) 0.2887(10) C 17 0.2225( 8) 0.8564(10) 0.4924(11) C 18 0.3466( 9) 0.8099(12) 0.3437(10) 2 2 1 T able 3: T em perature F acto rs for R hP3Me3 Atom Un X103 U22X103 U33X103 U12X103 U13X103 U23X103 RH 1 28( 0) 37(0) 33( 0) 0( 0) -2( 1) -3( 1) P 2 37(1) 48( 1) 47( 1) -6( 1) 7( 1) 8( 2) P 3 47(1) 57( 1) 46(1) 8(1) 8( 1) -11( 1) P 4 60 ( 1) 29( 1) 57( 1) -2( 1) -4( 1) -1(1) C 5 57< 2) 84( 2) 87( 2) -18( 2) 0( 2) 0( 2) C 6 65( 2) 65( 2) 58( 2) 12( 2) -4( 2) 2( 2) C 7 71(2) 78( 2) 56( 2) 4(2) -7(2) -10( 2) C 8 71(2) 73( 2) 64( 2) 1(2) -19( 2) -6( 2) C 9 52( 2) 47( 2) 46( 2) 4( 2) -9(2) 0(2) C 10 50(2) 56( 2) 55( 2) -13( 2) -7( 2) 1(2) C 11 68( 2) 65( 2) 56( 2) 4( 2) 1(2) -2( 2) C 12 64( 2) 52( 2) 62( 2) 2( 2) -8( 2) 0( 2) C 13 77( 2) 69( 2) 79( 2) -9( 2) 3( 2) 13( 2) C 14 69( 2) 87(2) 73( 2) 6( 2) 8( 2) -3(2) C 15 77( 2) 65( 2) 74( 2) 11(2) -1(2) -7( 2) C 16 80( 2) 95( 2) 83( 2) 5(2) 14( 2) -1(2) C 17 80( 2) 63( 2) 79( 2) 8( 2) 1(2) -3( 2) C 18 80( 2) 74( 2) 86(2) -9( 2) 2( 2) 7( 2) The complete temperature factor is exp[-2ji2(U11h2a’2 + U22k2b*2 + U ^ c ' 2 + 2U12hka*b* + 2U13hla’c* + 2U23klb*c‘] Table 4: Bond D istances(angstrom s)for RhPjM cj RH 1—P 2 RH 1—P 3 RH 1—P 4 RH 1—C 5 RH 1—C 6 RH 1— C 7 P 2 - r C 10 P 2—C 13 P 2—C 14 P 3—C 11 P 3—C 15 P 3—C 16 P 4—C 12 P 4—C 17 P 4—C 18 C 8—C 9 C 9—C 10 C 9—C 11 C 9—C 12 2.282( 2) 2.292( 3) 2.285< 3) 2.166(10) 2.175(11) 2.163(12) 1.866 (12) 1.844(11) 1.839(12) 1.836(12) 1.837(11) 1.812(13) 1.849(12) 1.826(12) 1.855(13) 1.511(15) 1.529(14) 1.579(15) 1.581(14) T able 5: B ond A ngles (deg) for RhP3Me3 P 2-RH 1-P 3 88.7( 1) P 2-RH 1-P 4 89.2( 1) P 3-RH 1-P 4 88.5( 1) P 2-RH 1-C 5 176.5( 5) P 3-RH 1-C 5 94.6 ( 4) P 4-RH 1-C 5 91.9( 3) P 2-RH 1-C 6 93.6( 3) P 3-RH 1-C 6 91.1(3) P 4-RH 1-C 6 177.2( 3) C 5-RH 1-C 6 85.5( 4) P 2-RH 1-C 7 91.0(3) P 3-RH 1-C 7 176.9( 3) P 4-RH 1-C 7 94.5( 3) C 5-RH 1-C 7 85.6( 5) C 6-RH 1-C 7 85.9( 4) RH 1-P 2-C 10 113.7( 4) RH 1-P 2-C 13 119.8( 4) C 10-P 2-C 13 101.0( 5) RH 1-P 2-C 14 118.7(4) C 10-P 2-C 14 100.9( 6) C 13-P 2-C 14 99.5( 6) RH 1-P 3-C 11 112.4( 4) RH 1-P 3-C 15 117.3( 5) C 11-P 3-C 15 103.0( 6) RH 1-P 3-C 16 120.6( 5) C 11-P 3-C 16 10i2.0( 6) C 15-P 3-C 16 99.1 (6) RH 1-P 4-C 12 113.6( 3) RH 1-P 4-C 17 120.6( 5) C 12-P 4-C 17 99.4( 5) RH 1-P 4-C 18 118.2( 4) C 12-P 4-C 18 102.2( 6) C 17-P 4-C 18 99.7( 5) C 8-C 9-C 10 107.8( 9) C 8-C 9-C 11 107.9( 9) C 10-C 9-C 11 111.7( 8) C 8-C 9-C 12 106.8( 8) C 10-C 9-C 12 112.0( 9) C 11-C 9-C 12 110.5{ 9) P 2-C 10-C 9 116.2( 7) P 3-C 11-C 9 117.9(8) P 4-C 12-C 9 115.9( 7) 224 References 1. 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Creator Wang, Lin (author)

Core Title Chemistry of the hard-ligated organorhodium complexes

Contributor Digitized by ProQuest (provenance)

Degree Doctor of Philosophy

Degree Program Chemistry

Publisher University of Southern California (original), University of Southern California. Libraries (digital)

Tag chemistry, organic,OAI-PMH Harvest

Language English

Advisor Flood, Thomas C. (committee chair), Deonier, Richard (committee member), Yang, Gilbert (committee member)

Permanent Link (DOI) https://doi.org/10.25549/usctheses-c17-667510

Unique identifier UC11343530

Identifier DP22062.pdf (filename),usctheses-c17-667510 (legacy record id)

Legacy Identifier DP22062.pdf

Dmrecord 667510

Document Type Dissertation

Rights Wang, Lin

Type texts

Source University of Southern California (contributing entity), University of Southern California Dissertations and Theses (collection)

Access Conditions The author retains rights to his/her dissertation, thesis or other graduate work according to U.S. copyright law. Electronic access is being provided by the USC Libraries in agreement with the au...

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