University of Southern California Dissertations and Theses

Kinetics and configurations of cobalt(iii)-bisimethylglyoxime complexes

(USC Thesis Other)

Kinetics and configurations of cobalt(iii)-bisimethylglyoxime complexes

PDF

Download

Open document

Flip pages

Download a page range

Download transcript

Copy asset link

Request this asset

Transcript (if available)

Content KINETICS AND CONFIGURATIONS OF COBALT(III) -BISDIMETHYLGLYGXIME COMPLEXES by Hon Gee T sia n g A D i s s e r t a t i o n P r e s e n te d t o th e FACULTY OF THE GRADUATE SCHOOL UNIVERSITY OF SOUTHERN CALIFORNIA I n P a r t i a l F u l f i l l m e n t o f th e R eq u irem en ts f o r t h e D egree DOCTOR OF PHILOSOPHY (C h e m istry ) S eptem ber 1968 UNIVERSITY O F SOUTHERN CALIFORNIA THE GRADUATE SCHOOL UNIVERSITY PARK LOS ANGELES. CALIFORNIA 9 0 0 0 7 This dissertation, written by under the direction of h..is.. Dissertation Com mittee, and approved by all its members, has been presented to and accepted by The Gradu ate School, in partial fulfillment of require ments for the degree of HON GEE TSIANG D O C T O R OF P H I L O S O P H Y Dean Date . January, 1969 DISSERTATION COMMITTEE L A rl.r.lf: Chairman ') L . v. — it v ACKNOW LEDGMENT F or g u id a n c e and i n s p i r a t i o n , th e a u th o r i s g r a t e f u l to h i s R e se a rc h D i r e c t o r , P r o f e s s o r Wayne K. W il- m arth . F or c o r r e c t i o n o f t h i s d i s s e r t a t i o n , th e w r i t e r w ish es t o th a n k Mr. H. K e n d a ll W ilcox. TABLE OF CONTENTS ACKNOWLEDGEMENT ......................................................................... LIST OF TABLES ........................................................................... LIST OF FIGURES ......................................................................... PREFACE ............................................................................................. CHAPTER I . RATES AND EQUILIBRIUM QUOTIENTS FOR THE DISPLACEMENT OF ^ 0 IN TRANS-SULFITO- AQUOBIS(DIMETHYLGLYOXIMATE)COBALT(III) BY VARIOUS NUCLEOPHILES ................................... I n t r o d u c t i o n .......................................................... E x p e rim e n ta l S e c tio n ...................................... R e s u lts and D is c u s s io n s ............................... I I . THE CONFIGURATIONS OF NaCo(DH)2 (S03 >0H2 •5H20 AND CIS-NaCo(DH)2 (0H)2 *5H20 .......... I n t r o d u c t i o n .......................................................... R e s u lts and D is c u s s io n ................................. 1. The C o n f ig u r a tio n o f NaCo(DH)o (S03 )0H2 ................................................•. . 2. The L in k ag e Between S u l f i t e and C o b a lt ............................................................ 3. NMR and IR s t u d i e s o f cis-N aC o (DH)2 (OH)2 • 5H20 ...................................... APPENDICES ..................................................................................... BIBLIOGRAPHY ................................................................................. i i iv v 1 4 4 7 17 67 67 70 70 74 79 88 97 i i i LIST OF TABLES T a b le Page 1. pH T i t r a t i o n o f C o C D H ^C S O ^O ^...................................... 19 2. W av elen g th s and A bsorbancy I n d ic e s f o r M easurem ents ................................................................................... 23 3. F o rm a tio n Q u o tie n t M easurem ent f o r Co(DH)2 (S03 )SCN“ 2 ...................................................................... 25 4 . F o rm a tio n Q u o tie n t M easurem ent f o r Co(DH)2 (S03 ) I ~ z .............................................................................. 26 5. The R ate o f F o rm a tio n o f Co(DH)2 (S03 ) 2 ^ ................. 35 6 . The R ate o f F o rm a tio n o f Co(DH)0 (SOo) SCN .............................................................. 42 7. The R ate o f F o rm a tio n o f Co(DH)2 ( 6 0 3 ) SCN"2 a t V a rio u s p H 's ............................................................ 43 8 . The R ate o f F o rm a tio n o f Co(DH)9 ( 8 0 3 ) T h io u re a " .......................................................................................... 48 9. The R ate o f F o rm atio n o f Co(DH)9 (SOq) N^ 2..................................................................... . . . . ........................... 49 _ 3 10. The R ate o f F o rm a tio n o f Co(DH)9 (S 0o) 9 by HSO3 ......................................................... 50 11. The R ate o f F o rm atio n o f Co(DH)2 (S0 3 )P y ” .............. 51 12. The R ate o f F o rm a tio n o f Co(DH)9 (SOo) ...................... 52 S2 ° 3 3 13. The R ate o f F o rm a tio n o f Co (DH)o(S 0 q) 1 -2.....................................................................j . . . i ........................... 54 14. The R ate o f A q u atio n o f Co(DH) 2 ( S O ^ ^ ...................... 59 15. The A b s o rp tio n Band o f O--H— 0 i n Co- b a l t - b is d im e th y lg ly o x im e Complexes ............................ 71 16. The A b s o rp tio n Bands o f S u l f i t e G roups i n C o b a lt- b is d im e th y lg ly o x im e Complexes .................. 78 iv LIST O F FIGURES F ig u r e 1. C a l i b r a t i o n Curve o f pH M eter ....................... 2. E v a lu a tio n o f th e A c i d i t y Q u o tie n t o f c o (d h ) 2 ( s o 3 ) o h - ....................................................... 3. E v a lu a tio n o f th e F o rm atio n Q u o tie n ts _ o f Co(DH)2 (S03 )SCN“ 2 and Co(DH)2 (S03 > I" z 4 . M olar A bsorbancy I n d ic e s o f Co(DH)~(S0~) OHZ i n 1 .0 M NaClO^, 0 .1 M P y r i d i n e , and 1.6 M NaBr s o l u t i o n s ............................................. 5. M olar A bsorbancy I n d ic e s o f Co(DH) (SO ) OH^ i n SO^2 , SCN", N3 , S2 O3 , 1“ , In d 3 6 . P l o t o f A b s o rb a n c ie s o f Co(DH)2 (S0 3 ) 0 H2 V ersu s th e C o n c e n tr a tio n o f B r“ .................. 7. P s e u d o - f i r s t - o r d e r R ate C o n s ta n t V ersu s S u l f i t e C o n c e n tr a tio n ........................................... 8 . P s e u d o - f i r s t - o r d e r R ate C o n s ta n t V ersus t h e C o n c e n tr a tio n o f 1“ , t h i o u r e a , SCN“ , N^, P y r i d i n e , HS03 , S2 O3 2 ................................. 9. P s e u d o - f i r s t - o r d e r R ate C o n s ta n t V ersu s pH a t 0 .1 M o f SCN" ................................................ 10. The R ate C o n s ta n t o f A q u a tio n o f Co(DH)„ (S0 3 >2 3 .............................................................................? 11. I n f r a r e d S p e c tr a o f Na Co(DH)_(S0 )SCN and Co(DH)2 (NCS)OH2 . . ? .............2 ...> ? .............. 12. I n f r a r e d S p e c tr a o f NaCo(DH)o(SOo) T h io u re a and N a^oC D H ^C SC ^)^ ....................... 13. I n f r a r e d S p e c tr a o f NaCo(DH)2 ( S C ^ O ^ and NaCo(DD)2 ( 5 0 3 ) 0 0 3 ........................................... F ig u r e Page 14. C a l i b r a t i o n c u rv e o f osm om eter............................................ 80 15. E q u iv a le n t C onductance o f NaCoCDH)^(OH)^ V ersu s fC ...................................................................................... 81 16. M olar A bsorbance I n d ic e s o f cis-N aC o (DH)2 (0H )2 .5H20 ............................................................................ 82 17. I n f r a r e d S pectrum o f NaCoCDH^COH^ ......................... 87 18. The P l o t o f L in e a r V e l o c i t y o f Flow V e rsu s M otor Speed a t V a rio u s C lu tc h V a lu e s .................................................................................................. 93 19. The F i l t e r i n g C i r c u i t o f t h e S to p p ed - Flow A p p a ratu s .............................................................................. 94 v i PREFACE Complex compounds o f t e r v a l e n t c o b a l t w ith d i - m eth y lg ly o x im e w ere f i r s t p r e p a re d by Chugaev^ i n 1905. A ll o f t h e s e compounds c o n t a i n two d im e th y lg ly o x im e m ole c u le s p e r c o b a l t atom . Chugaev d e s c r ib e d r e p r e s e n t a t i v e s o f a l l t h e s e p o s s i b l e ty p e s : Co(DH)2 A2 X, CoX(DH)2 A, and HCoX2 (DH)2 , w here A r e p r e s e n t s ammonia o r an o r g a n ic am in e, and X i s an a c id r a d i c a l o ccu p y in g one c o o r d i n a t io n s i t e . DH i s th e d im e th y lg ly o x i- m ate io n . C o b a lt( I I I ) - d im e th y lg ly o x im e com plexes have a ro u s e d much i n t e r e s t i n t h e l a s t d e c a d e . R e c e n tly a l a r g e num ber o f c o b a l t com plexes c o n ta in in g two a c id g ro u p s i n th e i n n e r c o o r d i n a t io n s i t e s have b een p r e p a re d by Ablov and h i s c o w o rk e rs. S c h ra u z e r and h i s g ro u p h av e p r e p a re d a s e r i e s o f c o b a lt- b is d im th y lg ly o x im e compounds c o n ta in in g c o b a l t - c a r b o n b o n d s, e s p e c i a l l y a l k y l g ro u p s. T h e re a r e a number o f re a s o n s f o r c o n tin u e d i n t e r e s t in th e c o b a l t ( I I I ) - b i s d i m e t h y l g l y o x i m e co m p lex es. One re a s o n i s b e c a u s e o f th e q u e s tio n o f th e g e o m e tric c o n f i g u r a t i o n o f t h e two d im e th y lg ly o x im e m o le c u le s , i . e . , ■*-L.A . Chugaev, Zhur. Russ. F iz-K him . Obshch. , 37, 610 (1 9 0 5 ). ------------------------------------------------------ 1 w h e th e r t h e s e two d im e th y lg ly o x im e m o le c u le s a r e c o p la n a r . R e c e n tly t h e c o b a lt- b is d im e th y lg ly o x im e com plexes in c i s 2 c o n f i g u r a t i o n a r e r e p o r t e d t o b e s y n th e s iz e d . A n o th er 3 r e a s o n i s a l s o b e c a u s e , as m e n tio n ed by S c h r a u z e r , th e b is d im e th y lg ly o x im e com plexes o f c o b a l t c l o s e l y re se m b le v ita m in B-^ d e r i v a t i v e s . T h e r e f o r e , t h e c o b a l t ( I l l ) - d i - m e th y lg ly o x im e com plexes ca n be u sed a s s im p le m odel com p o u n d s, w hich a r e e a s i l y p r e p a r e d i n l a r g e q u a n t i t y and - w hich may s e r v e to t e s t th e m e c h a n is tic p o s t u l a t e s d e r iv e d from b io c h e m ic a l e x p e rim e n ts . A lth o u g h a g r e a t number o f c o b a l t ( I I I ) - d i m e t h y l g l y o x i m e com plexes have b e en made, t h e k i n e t i c s and m echanism o f r e a c t i o n o f t h e s e com plexes h av e r a r e l y b een s t u d i e d . ^ A lso th e g e o m e tric c o n f i g u r a t i o n o f th e cis-N aC o(D H )2 (0 H)2 > w hich was r e p o r te d by A blov e t a l . , i s s t i l l i n c o n tr o v e r s y . T h is work i s d iv id e d i n t o two c h a p t e r s . In t h e f i r s t c h a p t e r th e k i n e t i c s and m echanism o f t h e s u b s t i t u t i o n r e a c t i o n o f w a te r i n N aCo(D H )^(SO ^O I^ by S0 “ ^ , SCN", HSO", I " , N ", S^O"^, p y r i d i n e , and t h i o u r e a a r e d is c u s s e d . The a c i d - c a t a l y z e d r a t e o f a q u a tio n o f CoCDH)^(SO^)"^ i s a l s o d i s c u s s e d . The e q u i l i b r i u m q u o t i e n t s o f f o rm a tio n ^A.V. A blov, N. M. Sam us1 and O.A. B o lo g a, R uss. J . I n o rg . Chem. , 8> , 440 (1 9 6 3 ). ^G.N. S c h ra u z e r and R .J . W in d g assen , J . Am. Chem. S o c . , 8 6 , 3738 (1 9 6 6 ). ---------------------- ^D.N. Hauge and J . Halpern, Inorg. Chem., 6 , 2059 (1 9 5 7 ). o f Co(DH)^(S0^)SCN"2 and Co(DH)^(S0^)I“2 from s p e c t r o - p h o to m e tric m easurem ents a r e c o n s id e r e d . The bond in g b etw een c o b a l t and l ig a n d s f o r Co(DH)^(SO^)SCN"^ and CoCDH)^ (SO^SCN^H* h av e b e e n d e te rm in e d w ith i n f r a r e d s p e c t r a . I n th e seco n d c h a p t e r t h e t r a n s c o n f i g u r a t i o n o f t h e s u l f i t o and aquo g ro u p s i n CoCDH)^(SO^)OH“ was co n firm e d . The lin k a g e b etw een s u l f i t e and c o b a l t i s d i s c u s s e d . A b lo v 's w ork i n t h e s tu d y o f cis-N aCo(D H )^(O H )^ •5H20 was r e p e a te d and t h e g e o m e tric c o n f i g u r a t i o n o f t h i s compound was s tu d i e d by u s in g n u c l e a r m a g n e tic r e so n a n c e and i n f r a r e d s p e c tr o s c o p ic m ethods. CHAPTER I RATE AND EQUILIBRIUM QUOTIENTS FOR THE DISPLACE MENT OF H20 IN TRANS-SULFITOAQUOBIS (DIMETHYLGLYOXIMATE)COBALT(III) BY VARIOUS NUCLEOPHILES I . I n t roduc t io n As m en tio n e d by B aso lo and P e a r s o n , s u b s t i t u t i o n o f one l ig a n d by a n o th e r i n a com plex c an b e c o n v e n ie n tly c l a s s i f i e d i n two m a jo r g r o u p s , n u c l e o p h i l i c s u b s t i t u t i o n , Sjg, and e l e c t r o p h i l i c s u b s t i t u t i o n , Sg. T hese s u b s t i t u t i o n m echanism s can b e f u r t h e r d iv id e d i n t o two k i n d s , n am ely , d i s s o c i a t i o n m echanism s, S ^ l ( o r S ^ l ) , and d i s p la c e m e n t m echanism s, S^2 ( o r S^,2). The l i m i t i n g ty p e o f S ^ l m echanism , o r d i s s o c i a t i v e m e c h a n i s m ,^ i s b a se d on th e f a c t t h a t t h e f i v e c o o r d i n a t e r e a c t i v e i n t e r m e d i a t e i s g e n e r a te d and h a s a l i f e t i m e lo n g enough t o d i s c r i m i n a t e b etw een v a r i o u s n u c l e o p h i l e s p r e s e n t i n th e s o l u t i o n . The f i r s t w e ll-d o c u m e n te d l i m i t i n g ty p e S ^ l m echanism was ^F. B aso lo and R.G. P e a rs o n , "M echanism s o f I n o r g a n ic R e a c tio n s ," Jo h n W iley and S o n s, In c . , New Y ork, N.Y. 2nd E d ., 1967. ^C.H. L an g fo rd and H.B. G ray , "L ig an d S u b s t i t u t i o n P r o c e s s e s ," W.A. B enjam in, New Y ork, 1966. 5 s tu d i e d i n o u r l a b o r a t o r y . I t h a s been shown t h a t th e r a t e o f s u b s t i t u t i o n o f H^O i n Co(CN)^OH"^ by N~ and SC N ",^5^ 5^ i s in d e p e n d e n t o f th e c o n c e n tr a tio n s o f lig a n d s when th e c o n c e n tr a tio n s o f lig a n d s a r e l a r g e . A nalogous r e s u l t s h av e b een o b ta in e d i n a s tu d y o f th e s u b s t i t u t i o n o f H20 in Co(CN)4 (S03 )0H- 3 b y CN~ , 1 0 and i n Co(NH3 >4 (S03 )0H+ b y NH3 , CN“ e t c . 1 1 A ll t h e s e r e a c t i o n s p ro c e e d th ro u g h a l i m i t i n g ty p e o f S ^ l m echanism , i . e . , t h e l i f e t i m e o f th e f i v e c o o r d in a te d i n t e r m e d i a t e g e n e r a te d from th e d i s s o c i a t i o n o f ^ 0 i s lo n g enough to e x h i b i t a s e l e c t i v e r e a c t i v i t y to w ard th e v a r io u s n u c l e o p h i l e s i n th e s o l u t i o n . T h is work was i n i t i a t e d f o r two r e a s o n s . F i r s t o f a l l , we in te n d e d t o f i n d o t h e r r e a c t i o n s w hich p r o c ee d ed by th e l i m i t i n g ty p e o f S ^ l m echanism . S e c o n d ly , t h e s u b s t i t u t i o n r e a c t i o n s o f 1 ^ 0 i n Co(CN)4 (S0 3 ) 0 H“ 3 and ^A. Haim and W.K. W ilm a rth , In o rg . C hem ., 1, 573 (1 9 6 2 ). “ ^A. Haim and W.K. W ilm a rth , In o rg . C hem ., 1 ,5 8 3 (1 9 6 2 ). “ 9 A. Haim, R .J . G ro ss and W.K. W ilm a rth , "A dvances i n C h e m istry S e r i e s , " No. 9 , A m erican C hem ical S o c ie ty , W ash in g to n , D .C ., 1965, p . 31. ^ P . H . T e w a ri, R.W. G a v e r, H.K. W ilco x , and W.K. W ilm a rth , I n o rg . Chem ., 6 ,6 1 1 (1 9 6 7 ). 11J . H a lp e rn , R.A. P alm er and L.H. B la k le y , J . Am. Chem. S o c . , 8 8 , 2877 (1 9 6 6 ). CoCNH^^CSO^OH^ p ro c e e d v e r y r a p i d l y . T h is may be e x p la in e d by th e f a c t t h a t th e t r a n s e f f e c t e x i s t s in o c t a h e d r a l co m p lex es, w here a lig a n d u n d e rg o e s s tr o n g 12 m e t a l - t o - l i g a n d 7t b o n d in g . The s u l f i t e lig a n d l a b i l i z e s t h e lig a n d t r a n s t o i t s e l f . 13 However, Hauge and H a lp e rn i n th e s tu d y o f s u b s t i t u t i o n r e a c t i o n s o f ^ 0 i n Co(DH)2 ( N C ^ O ^ by v a r io u s n u c l e o p h i l e s , h av e shown t h a t t h i s p r i n c i p l e i s n o t g e n e r a l l y t r u e . The s u b s t i t u t i o n s p ro c e e d much s lo w e r th a n t h a t in CoCDH)^ ( S O ^ O ^ , r e g a r d l e s s o f th e f a c t t h a t th e n i t r i t e g ro u p can form even s tr o n g e r m e t a l - t o - l i g a n d - 2 b o n d in g th a n SO^ . The compound, NaCo(DH)2 ( S O ^ O ^ , was c h o se n f o r s tu d y f o r t h r e e r e a s o n s . F i r s t , t h e r e i s s tr o n g e v id e n c e ( d is c u s s e d in C h a p te r I I ) t h a t i t has a t r a n s c o n f i g u r a t i o n . S econd, th e n e g a t i v e c h a rg e o f th e com plex s h o u ld m in im ize th e fo rm a tio n o f io n p a i r s w ith n e g a t i v e n u c le o p h i l e s and s im p lif y t h e i n t e r p r e t a t i o n o f t h e k i n e t i c d a t a . T h ir d , th e weak a c i d i t y o f th e w a te r l i g a n d , w ith a pK o f a p p ro x im a te ly 1 0 .3 , p e r m itte d s t u d i e s u s in g a n io n s o f r e l a t i v e l y weak a c id s w ith o u t th e f o rm a tio n o f t h e c o n ju g a te b a s e o f t h e com plex, a f e a t u r e w h ich a l s o s i m p l i f i e s th e k i n e t i c b e h a v io r. l ^ c . J . B a llh a u s e n and H.B. G ray , I n o rg . Chem ., 2, 426 (1 9 6 3 ). l^H auge and H a lp e rn , op. c i t . , 6, 2059. I I . E x p e rim e n ta l S e c tio n REAGENTS A ll co m m ercial c h e m c ia ls w ere o f r e a g e n t g ra d e . S to c k s o l u t i o n s o f NaClO^ w ere p r e p a re d by s lo w ly a d d in g s t o i c h i o m e t r i c am ounts o f 707o HCIO^ to an h y d ro u s Na2 C0 2 « T h is s o l u t i o n was h e a te d on a h o t p l a t e u n t i l i t became c l e a r and th e f i n a l pH was a d j u s t e d to b etw een 6 .5 and 7 .0 by a d d i t i o n o f NaOH o r HCIO^. The c o n c e n t r a t i o n s o f th e s to c k s o l u t i o n s w ere th e n d e te rm in e d u s in g io n ex ch an g e te c h n iq u e s . F iv e m i l l i l i t e r s o f s to c k s o l u t i o n NaClO. s o l u t i o n w ere d i l u t e d w ith d e io n iz e d w a te r in a 4 500 ml v o lu m e tr ic f l a s k and 20 ml o f t h e d i l u t e NaClO. 4 s o l u t i o n w ere t r a n s f e r r e d i n t o a c a t i o n i c ex ch an g e column (Dowex 50W-X4, H+ fo rm , 5 0 -100 m esh). The c o n c e n t r a t i o n o f t h e s to c k NaClO^ c o u ld th e n b e d e te rm in e d by t i t r a t i n g t h e e l u t e d s o l u t i o n w ith s ta n d a r d NaOH. P y r id i n e was p u r i f i e d by th e s e l e c t i o n o f th e f r a c t i o n o f t h e d i s t i l l a t e a t 1 1 3 .8 - 1 1 4 .0 ° C from an a l l g l a s s 1 5 - p l a t e O ld e rs h a e p e r f o r a t e d p l a t e f r a c t i o n a t in g colum n. ANALYSES A ll e le m e n ta l a n a ly s e s (C, H, N, S) w ere c a r r i e d o u t by A lf re d B e rn h a rd t M ik r o a n a ly tis c h e s L a b o ra to riu m im M ax-P lanck I n s t i t u t , 5251 E ib ac h u b e r E n g e ls k ir c h e n , West Germany, e x c e p t t h a t o f Na2 Co(DH)2 (SO-j)SCN* 5 ^ 0 , 8 w h ich was done by Schw arzkopf M icro A n a l y t i c a l L a b o ra to r y , 56-16 3 7 th A venue, W oodside 77, N.Y. D e te rm in a tio n o f c o b a l t ^ was c a r r i e d o u t by v o lu m e tr ic t i t r a t i o n u s in g d iso d iu m e th y le n e d ia m in e t e t r a a c e t a t e as t i t r a n t and erochrom e b la c k T a s i n d i c a t o r . Sam ples o f a b o u t 0 .1 5 gram w ere d i g e s t e d i n c o n c e n tr a te d I^SO^ by h e a t i n g to d ry n e s s s e v e r a l tim es u n t i l t h e r e s i due was r o s e - r e d . The sam p les w ere th e n d i s s o l v e d in 0 .1 M H.SO. and t r a n s f e r r e d to 100 ml v o lu m e tr ic f l a s k s . 2 H - To 10 ml o f t h i s s o l u t i o n , 20 ml o f 0 .0 1 M d iso d iu m s a l t o f EDTA w ere added and t h e pH was a d ju s te d to 10 w ith 6 M NH.OH (a b o u t 6 m l). The e x c e ss EDTA was t i t r a t e d w ith a 4 s ta n d a r d s o l u t i o n o f z in c n i t r a t e (0 .0 1 M) u n t i l th e c o l o r ch anged from b lu e to w in e - re d . S ta n d a rd z in c n i t r a t e s o l u t i o n w ere p re p a re d by d i s s o l v i n g 1 .5 grams an h y ro u s ZnO i n 6 ml o f 1 :1 HNO^ and d i l u t i n g t o 1 l i t e r . The t i t r a t i o n s h o u ld b e c a r r i e d o u t im m e d ia te ly a f t e r a d d in g th e i n d i c a t o r to th e s o l u t i o n s in c e i n t e r f e r e n c e o f th e end p o in t may r e s u l t from d i s s o c i a t i o n o f c o b a l t from th e EDTA com p le x . The c o n c e n t r a t i o n s o f sodium t h o i c y a n a t e , sodium b ro m id e , and sodium i o d i d e s o l u t i o n s w ere d e te rm in e d by u s in g s i l v e r n i t r a t e as t i t r a n t and e o s in as i n d i c a t o r . ^ l ^ F . J . W elch er, "The A n a l y t i c a l Uses o f E th y le n e - d i a m i n e t e t r a a c e t i c a c i d , " Van N o s tra n d , New Y ork, 1957. 1-^I.M. K o lth o f f and R. B e lc h e r, " V o lu m e tric A n aly s i s , " V ol. I I , I n t e r s c i e n c e P u b l i s h e r , I n c . , New Y ork, 1957, p. 249. The c o l o r ch an g e from th e w h ite p r e c i p i t a t e s o f AgSCN o r Agl t o p in k i n d i c a t e s t h e end p o i n t . The sodium a z id e c o n c e n t r a t i o n was d e te rm in e d 1 z : u s in g t h e f o llo w in g p r o c e d u re . To a 500 ml f l a s k , 0 .5 ml o f CS^, 6 -8 ml o f a c e to n e and a m o d e ra te ex c e ss o f s ta n d a r d 0 .1 N s o l u t i o n w ere added. Then a m easured amount o f th e a z id e s o l u t i o n was added. When th e s o l u t i o n was s t i r r e d , ^ g as w a s .e v o lv e d . When t h e e v o l u t i o n o f g a s e s c e a s e d (5 -1 0 m i n u te s ) , t h e s o l u t i o n was d i l u t e d w ith 250 ml o f w a te r and th e e x c e ss was b a c k t i t r a t e d w ith s ta n d a r d 0 .1 N S^O"^, u s in g s t a r c h as i n d i c a t o r . Sodium s u l f i t e , sodium b i s u l f i t e , and sodium t h o i s u l f a t e c o n c e n t r a t i o n s w ere d e te rm in e d by t i t r a t i o n w ith s ta n d a r d io d in e s o l u t i o n , u s in g s t a r c h as i n d i c a t o r . PREPARATION OF COBALT-DIMETHYLGLYOXIME COMPLEXES 1. P r e p a r a t i o n o f NaCo(DH)^(S0^)0H^‘ 5H^0 T h is compound was f i r s t p r e p a re d by Ablov e t 1 7 18 a l . ’ We p r e p a re d t h e sodium compound, NaCo(DH) 2 (S0 g ) 0 H2 ‘ 5 H2 O, u s in g a m ethod d e v e lo p e d in d e p e n d e n tly . About 3 ml o f w a te r w ere added to 3 .4 2 grams (0 .0 1 m ole) ^ I . M . K o lth o f f and R. B e lc h e r, " V o lu m e tric A n aly s i s , " V o l. I l l I n t e r s c i e n c e P u b l i s h e r , I n c . , New Y ork, 1957, p. 312. ■*^A.V. Ablov and G .P. S y r ts o v a , R uss. J . I n o r g . Chem. , _5, 588 (1 9 6 0 ). 1 8 G .P. S y r ts o v a and L.N. K o r le ty a n u , R uss. J . I n o r g . Chem ., 11, 1233 (1 9 6 6 ). 10 o f Co(DH)„ C10H9 . ^ 1 .2 6 gram s (0 .0 1 m ole) o f Na SO ^ ^ I 3 w ere added t o th e above s u s p e n s io n , w hich was th e n h e a te d and s t i r r e d a t a b o u t 50°C f o r 10 m in u te s u n t i l t h e s o l u t i o n became a re d d is h -b ro w n . T h is s o l u t i o n was th e n c o o le d and f i l t e r e d t o remove t h e r e s i d u e , w hich i s p r o b a b ly Co(DH) (OH ) C l. The f i l t r a t e i s th e n e v a p o ra te d a t a te m p e r a tu r e low er th a n 50°C , and th e s o l i d form ed i s r e c r y s t a l l i z e d f i v e tim e s from w a te r . The c r y s t a l s w ere d r ie d i n a i r f o r t e n h o u r s . U nder a m ic ro s c o p e th e s o l i d a p p e a rs as re d d is h -b ro w n r i g h t a n g le c r y s t a l s . The y i e l d i s a b o u t 207,. A nal. C alcd . f o r NaCoC0 H „,N ,0. 0 S: Co, 1 1 .7 8 ; 8 26 4 13 C, 1 9 .2 0 ; H, 5 .2 4 ; N, 1 1 .2 0 ; S, 6 .4 0 ; H y d ra te H2 0 , 1 9 .0 0 . Found: Co, 1 1 .7 6 ; C, 1 9 .4 5 ; H, 5 .0 8 ; N, 1 1 .2 4 ; S, 6 .2 5 . H y d ra te H2 0 d e te rm in e d by w e ig h t l o s s u n d e r e v a c u a tio n f o r 6 h o u rs a t 100°C, was fo u n d t o be 19.097o 2. P r e p a r a t i o n o f Na9 Co(DH)9 (SOQSCN*5 H9 O 0 .5 gram (0 .0 0 1 m ole) o f NaCo(DH) 2 (S0^)0H 2 * 5 ^ 0 and 0 .0 8 1 gram NaSCN w ere m ixed i n 1 ml o f w a te r . As i t w i l l be shown l a t e r , th e f o rm a tio n o f Na2 Co(DH)2 (SO^) SCN* 5 ^ 0 (y e llo w ) i s n o t c o m p le te , so th e r e a c t i o n m ix t u r e alw ays c o n ta in s NaCo(DH)2 (S0 ^ ) 0 H2 and NaSCN. S in c e t h e c o l o r and d e n s i t y o f t h e s e t h r e e compounds a r e d i f f e r e n t , th e y can b e s e p a r a t e d i n anhydrous d i e t h y l e t h e r ■^A.V. Ablov and N.M. Samus' , Russ. J. Inorg. Chem., 4 , 410 (1 9 6 0 ). 11 u s in g d e c a n t a t i o n m eth o d s. The above s o l u t i o n was e v a p o r a te d a b o u t 50°C to d ry n e s s and th e f i n e l y ground im p u r e p r o d u c t was su sp en d ed by r a p i d s t i r r i n g i n d i e t h y l e t h e r . A p p ro x im a te ly 1 .0 m in u te a f t e r th e s t i r r i n g was t e r m i n a t e d , th e to p t h r e e q u a r t e r s o f th e e t h e r s u s p e n s io n was removed by d e c a n t a t i o n , le a v in g t h e b u lk o f th e re d im p u r ity i n t h e re m a in in g q u a r t e r o f t h e e t h e r s u s p e n s io n . I n o b t a i n i n g t h e f i n a l p r o d u c t, th e d e c a n t a t i o n p r o c e d u re was r e p e a te d a seco n d tim e . A nal. C alcd . f o r Na2CoCgH24N^O-^2^2: 1 9 .1 8 ; H, 4 .3 0 ; N, 1 2 .4 2 ; S, 1 1 .4 0 . Found: C, 1 8 .9 9 ; H, 4 .0 5 ; N, 1 2 .1 3 ; S , 1 2 .1 2 . 3. P r e p a r a t i o n o f NaCoCDtQoCSOpSCNoH/^I^O 0 .5 gram (0 . 0 0 1 m ole) o f NaCo(DH)2 (S03 )0H2 - 51^0 and 0 .0 7 6 gram o f t h i o u r e a (0 .0 0 1 m ole) w ere d i s s o l v e d in 1 ml w a te r . The y ello w p r o d u c t was o b ta in e d by e v a p o ra t i o n a t 50°C and p u r i f i e d b y d e c a n t a t i o n m ethods. A nal. C alcd . f o r NaCoCgH2 2 NgOgS2 - ' C, 2 1 .4 2 ; H, 4 .4 0 ; N, 1 6 .6 5 ; S, 1 2 .6 9 . Found: C, 2 1 .4 8 ; H, 4 .8 5 ; N, 1 6 .6 6 ; S, 1 2 .9 5 . 90 4 . P r e p a r a t i o n o f CoCDlQo^CS^Ho^HoO 3 .5 1 grams (0 .0 1 m ole) o f Co(DH)2 (N02 )0H2 2 1 w ere added t o 50 ml o f w a te r , and a s m a ll amount o f NH^ was 90 A.V. Ablov and N.M. Samus and M.S. Popov, D o k l. Akad. Nauk USSR 106, 665 (1 9 5 6 ). ^ L . A . Chugaev, B e r . , 4 1 , 2226 (1 9 0 8 ). 12 added. 0 .8 1 gram o f NaSCN was added t o t h e s o l u t i o n and t h e m ix tu re was h e a te d u n t i l th e c o l o r tu r n e d from th e d a r k re d Co(DH)2 (N0 2 ) 0 H2 t o t h e y e llo w i n s o l u b l e Co(DH) 2 ( n c s) oh2 . A n al. C a lc d . f o r CoCgH-^gN^OgS: Co, 1 5 .3 8 ; h y d r a t e w a te r 4 .7 0 . Found: Co 1 5 .4 1 ; w e ig h t l o s s a t 100°C vacuum oven f o r 10 h o u r s , 4 .7 5 . 5. P r e p a r a t i o n o f N a g C o f o H ^ ^ O ^ o * 1 2 HqO^ 3 .4 2 gram s (0 .0 1 m ole) o f CoClCDH^Ol^ and 5 .0 4 gram s (0 . 0 2 m ole) o f Na2 S0 g w ere m ixed t o g e t h e r i n 1 0 ml o f w a te r . The m ix tu re was th e n h e a te d a t 50°C f o r 15 m in u te s . E th a n o l was g r a d u a l l y added t o t h e above s o l u t i o n p r e c i p i t a t i n g a l i g h t y e llo w pow der. The p r e c i p i t a t e was s e p a r a t e d and r e c r y s t a l l i z e d from w a te r . U nder a m ic ro sc o p e NagCo(DH)2 (SOg)2 * 1 2 ^ 0 a p p e a rs a s g o ld e n y e llo w , lo n g r e c t a n g u l a r c r y s t a l s . A nal. C a lc d . f o r NagCoCgHggN^0 2 2 S2 : C, 1 3 .0 7 ; H, 5 .2 1 ; N, 7 .6 2 ; S, 8 .7 1 . Found: C, 1 3 .2 1 ; H, 5 .3 0 ; N, 7 .6 4 ; S, 8 .6 4 . 6 . P r e p a r a t i o n o f cis-N aC o(D H )2 (OH)2 • 5HqO^ 5 gram s o f Co(DH) 2 (NCS)0 H2 o r C o C l ^ H ^ O ^ was m ixed w ith 20 ml o f 507, NaOH and a b o u t 10 ml o f w a te r and 22 A.V. Ablov and G .P. S y r ts o v a , R u ss, J . I n o r g . C hem ., 5 , 588 (1 9 6 0 ). 23 A blov, Samus and B o lo g a, op. c i t . , 8 , 440. 13 s t r o n g l y h e a te d on a h o t p l a t e u n t i l th e s o l u t i o n becam e a d a rk re d c o l o r . A f t e r c o o l i n g , t h e s o l u t i o n was f i l t e r e d and t h e f i l t r a t e was e v a p o r a te d . The N aC o^H )^ (0 H)2 ’ 5 H2 0 com plex form s d a r k re d r e c t a n g u l a r p l a t e l e t s . R e c r y s t a l l i z a t i o n was c a r r i e d o u t tw ic e from w a te r. A n al. C a lc d . f o r NaCoCg^gN^O-^: C, 2 2 .0 0 ; H, 5 .5 0 ; N, 1 2 .8 2 ; Co, 1 3 .5 0 ; h y d r a t e K^O, 2 0 .6 4 ; m ole c u l a r w e ig h t, 436. Found: C, 2 2 .2 6 ; H, 5 .2 4 ; N, 1 2 .8 6 ; Co, 1 3 .2 3 . H y d ra te ^ 0 , d e te rm in e d by w e ig h t l o s s u n d e r e v a c u a tio n f o r 10 h o u rs a t 100°C, was found t o b e 2 0 .4 9 ; m o le c u la r w e ig h t, 430*30 ( s e e C h a p te r I I ) . T h is compound i s r e a d i l y d i s s o l v e d i n w a te r , s l i g h t l y s o l u b l e i n e t h a n o l , m e th a n o l, DMF, DMSO, i s o - p r o p y l a l c o h o l , d io x a n e , and i n s o l u b l e i n C ^ C ^ j CHgNC^, CHClg, CHgCl, e t c . APPARATUS E x t i n c t i o n c o e f f i c i e n t s o f d i f f e r e n t sy stem s w ere m easu red w ith a C ary Model 14PM R ec o rd in g S p e c tro p h o to m e te r . F o rm a tio n q u o t i e n t s w ere m easu red u s in g a Beckman DU s p e c tro p h o to m e te r . A Beckman R e se a rc h Model pH m e te r , eq u ip p ed w ith an E3 g l a s s e l e c t r o d e and a f r i t t e d r e f e r e n c e e l e c t r o d e No. 39071, was u se d in th e pH m easu rem en ts. The r e f e r e n c e e l e c t r o d e was f i l l e d w ith 4 M NaCl i n o r d e r to m easu re th e pH o f th e s o l u t i o n s c o n ta in in g CIO4 . The pH m e te r was 14 c a l i b r a t e d a t u n i t i o n i c s t r e n g t h i n h ig h a c id and b a s e r e g io n s by a c id and b a s e t i t r a t i o n . The lo g a r ith m o f th e a c t u a l h y d ro g en io n c o n c e n t r a t i o n can be e x p re s s e d by an e m p ir ic a l fo rm u la , - lo g [H*] = 0.9 9 8 7 pH + 0 .2 6 6 and t h a t o f h y d ro x y l io n c o n c e n t r a t i o n , - lo g [OHl = 1 .0 5 3 pH + 14.073 F ig . 1 shows th e c a l i b r a t i o n c u rv e f o r th e pH m e te r from a p l o t o f th e m e te r r e a d in g a g a i n s t th e lo g a r ith m o f a c t u a l h y d ro g en io n c o n c e n t r a t i o n a t u n i t i o n i c s t r e n g t h , w here NaClO^ was u se d as s u p p o r tin g e l e c t r o l y t e . In t h i s f i g u r e 24 t h e n u m b e ric a l v a lu e o f io n i c p ro d u c t o f w a te r , pK = 14 1 3 .7 7 o r K = 1 .7 0 x 10 , was u se d f o r t h e c o n v e r s io n w o f h y d ro x y l io n c o n c e n t r a t i o n to h y d ro g en io n c o n c e n t r a t i o n . A P e rk in -E lm e r Model 137 I n f r a r e d S p e c tr o p h o to m e te r was u se d f o r IR m easu rem en ts. KBr p e l l e t s w ere p r e p a re d f o r each e x p e rim e n t by m ix in g 1 mg o f c o b a l t com plex w ith 0 .1 gram o f KBr. The m ix tu re was ground f i n e l y i n a m o r ta r , and d r i e d i n a vacuum oven a t 100°C f o r 10 m in u te s b e f o r e p r e s s i n g . The KBr m ix tu re was p r e s s e d up to 6000 l b s / s q . i n . , g iv in g a t r a n s p a r e n t p e l l e t . The IR s p e c t r a w ere ta k e n im m e d ia te ly a f t e r th e p e l l e t s w ere made. I t was shown t h a t t h e com plexes ground 24 R. N asanen and P. M e r ila in e n , Suomen K em ., 33B, 149 (1 9 6 0 ). 15 with nujol gave the same IR spectra. In making KBr pel lets fine grinding is necessary in order to obtain a smooth spectrum. N u c le a r m a g n e tic re s o n a n c e s p e c t r a w ere d e te rm in e d w ith V a ria n A-60 and H-100 s p e c tr o m e te r s a t 60 M C and 100 M C r e s p e c t i v e l y . Tetram ethylam m onium c h l o r i d e was u sed as i n t e r n a l s ta n d a r d . The stopped-flow apparatus was purchased from Atom-Mech Machine Co. It has been described in detail 25 by Dulz and Sutin. I n a l l th e k i n e t i c m easurem ents t h e t o t a l t r a n s m itta n c e ch an g e o f th e r e a c t i o n s o l u t i o n i n th e o b s e rv a t i o n was k e p t n e a r 37». In t h i s ra n g e th e change i n t r a n s m itta n c e i s a p p ro x im a te ly p r o p o r t i o n a l to th e change in o p t i c a l d e n s i t y and h e n ce t o t h e c o n c e n t r a t i o n change o f th e a b s o rb in g s p e c i e s . T h e r e f o r e , th e v e r t i c a l s c a l e o f t h e o s c illo g r a m s can be t r e a t e d a s o r d in a r y c o n c e n t r a t i o n ( s e e A ppendix I ) . At least three oscillograms were taken for each ligand concentration. The rate constants were obtained from the slope of a linear plot of log (C^ - Cfc). ^ G . D ulz and N. S u t i n , I n o r g . Chem., 2, 917, (1 9 6 3 ). ~ 16 14 12 10 8 6 r e a d in g 4 2 0 4 6 8 10 12 0 2 -log [H+ ] F ig . 1 C a l i b r a t i o n Curve o f pH M eter a t 1 .0 M o f NaClO^ 17 I I I . R e s u lts and D is c u s s io n s 1. S to ic h io m e tr y I n th e r e s u l t s t o b e p r e s e n t e d below t h e g e n e r a l a s su m p tio n w i l l b e made t h a t d is p la c e m e n t o f i n Co(DH)2 (S03 )0H2 i s n o t accom panied by r a p i d a q u a tio n o f _ 2 e i t h e r a SOg o r DH lig a n d . The a s su m p tio n seems to be i n h e r e n t l y p l a u s i b l e a n d , f o r t u n a t e l y , w ith some lig a n d s t h e r e i s e x p e r im e n ta l s u p p o rt f o r i t s v a l i d i t y . The s t r o n g e s t e v id e n c e i s b a s e d on th e p r e p a r a t i v e c o n v e r s io n o f aqueous Co(DH)2 (S03 )0H2 t o Na2 Co(DH)2 (S03 ) SCN-5H20 and N aC o(D I^(S03 )SCN2 H4*2H2 0 . A n a ly s is o f th e r e a c t i o n p r o d u c ts i n d i c a t e s t h e c o r r e c t n e s s o f th e a s s ig n e d fo rm u la . I n a d d i t i o n , i n a n a t i o n r e a c t i o n w ith th e n u c - -2 l e o p h i l e s S0 3 and HSOg th e a b s o r p t i o n s p e c t r a a f t e r r e a c t i o n a r e i n q u a n t i t a t i v e l y ag re e m e n t w ith t h a t o f a s o l u t i o n o f Na3 Co(DH)2 (SC>3 ) 2 * 12H20. I n view o f t h e s e r e s u l t s , i t seems v e r y u n l i k e l y t h a t any o f th e l i g a t i o n r e a c t i o n s in v o lv e a n y th in g s o t h e r th a n th e d is p la c e m e n t o f H2 0 i n t h e com plex. 2. pH T i t r a t i o n o f Co(DH)2 (S03 )0Hq The d i s s o c i a t i o n c o n s ta n t o f Co(DH)2 (SOg)OH2 to _ o form i t s c o n ju g a te b a s e Co(DH)2 (S 03 )0H was d e te rm in e d by pH t i t r a t i o n . c o ( d h ) 2 ( s o 3 )o h 2 + 0H“ Co(DH)2 (S03 )0H- 2 + h2 o (1 ) 18 CM < b O O 1 — 1 4 .0 3 .0 3.5 - lo g [OH_] F ig . 2 E v a lu a tio n o f th e a c i d i t y q u o t i e n t o f Co(DH)^ (SOg)OH2 . A p l o t o f log[A~^] /[H A ] v s . - logfH +1a t u n i t i o n i c s t r e n g t h o f NaCIO . 19 T a b le 1. pH T i t r a t i o n o f Co(DH) 2 (SOg) ( 0 ^ ) Volume o f NaOH -log{OH-} [A ] (mM) TH A ] (mM) lo g rA]/jHA~J (m l) 0 . 6 4 .2 3 0 0.0 6 0 0 3 0 .4 4 0 -0 .8 6 4 0 . 8 4 .0 9 3 0 .0 7 9 8 0 .4 2 0 -0 .7 2 0 1 . 0 4 .0 0 0 0 .0 9 9 8 0 .4 0 0 -0 .6 0 2 1 . 2 3 .9 0 0 0 .1 1 9 4 0 .3 8 1 -0 .5 0 3 1 .4 3.8 2 6 0 .1 3 9 0 .3 6 1 -0 .4 1 3 1 . 6 3 .7 5 0 0 .1 5 9 0 .3 4 1 -0 .3 3 2 1 . 8 3 .6 8 2 0 .1 7 8 0 .3 2 2 -0 .2 5 7 2 . 0 3 .6 1 6 0 .1 9 7 0 .3 0 3 -0 .1 8 5 2 . 2 3.5 6 1 0 .2 1 7 0 .2 8 4 -0 .1 1 6 2 .4 3 .4 9 7 0 .2 3 5 0 .2 6 5 -0 .0 5 1 2 .6 2 3.4 3 9 0 .2 5 6 0 .2 4 4 0 . 0 2 0 2 . 8 3 .4 0 0 0 .2 7 3 0 .2 2 7 0 .0 8 0 3 .0 3.338 0 .2 9 0 0 . 2 1 0 0 .1 4 3 3 .2 3 .2 7 6 0 .3 0 8 0 .1 9 2 0.2 0 5 3 .4 3 .2 2 3 0 .3 2 5 0 .1 7 5 0 .2 6 9 3 .6 3.185 0 .3 4 3 0 .1 5 7 0 .3 3 9 3 .8 3.119 0 .3 5 8 0 .1 4 2 0 .4 0 1 4 .0 3 .0 7 0 0 .3 7 4 0 .1 2 6 0 .4 7 2 4 .2 3.009 0 .3 8 8 0 . 1 1 2 0 .5 3 9 4 .4 2 .9 6 4 0 .4 0 3 0 .0 9 7 1 0 .6 1 9 4 .6 2.9 0 5 0 .4 1 5 0.0 8 5 2 0 . 6 8 8 20 T a b le 1. ( c o n 't ) Volume o f NaOH -log([O H l [A"] (mM) [HA K™M) lo g [A]/[HA~] (ml) 4 .8 2.849 0.426 0.0738 0.763 5 .0 2.799 0.438 0.0624 0.846 [Co(DH)2 (S03 )0H"2] jCo(DH)2 (S03 )0H2Jj0H"| 0.2500 gram of NaCo(DH)2 (S03 )0H2 -5H20 in 50 ml (0 .5 mM) o f 1 .0 M NaClO^ s o l u t i o n was t i t r a t e d w ith 0.1049 M NaOH. Both th e t i t r a n t and th e t i t r a t e d s o l u t i o n were m a in ta in e d a t u n i t io n ic s t r e n g t h . The p l o t (F ig. 2) o f log [A -2] / [HA~], where [A-2) -2 r e p r e s e n t s th e c o n c e n t r a t i o n of Co(DH)2 (SOg)OH and [HAl th e c o n c e n tr a tio n of Co(DH) 2 (S O ^ jO ^ , v e rs u s - log [OH] g iv e s a s t r a i g h t l i n e w ith a s lo p e o f 1 .1 . The r e a son f o r a s lo p e of 1.1 and n o t 1 .0 i s n o t u n d e rsto o d . The pK o f Co(DH)2 (SO^OH^ to form i t s c o n ju g a te base i s 4 .9 x 10"1 1 , where th e v a lu e 1.70 x 10 ^ f o r th e io n ic p ro d u ct o f w a te r in u n i t NaClO^ s o l u t i o n a t 25°C was used. _ 2 3. F orm ation q u o tie n ts f o r Co(DH)2 (Sp3 )SCN and Co(DH)2 (sopr2 The fo rm a tio n q u o tie n t f o r th e r e a c t i o n Co(DH)2 (S03 )0H2 + X" Co(DH)2 (S03 )X_2+ H£0 (3) i s g iv e n by K = [ c o ( d h ) 2 ( s o 3 ) x “ 2] ( 4 ) [Co(DH) 2 (S0^)0H~] [Xl where X" r e p r e s e n ts th io c y a n a te o r io d id e . Absorbancy m easurem ents of s o lu t i o n s of Co (DH)2 22 (SO^)OH” a t v a r io u s c o n c e n tr a tio n s of SCN“ and u n i t io n ic s t r e n g t h were c a r r i e d o u t a t th e w av elength 325 m/t. The _2 measurem ents f o r t h e fo rm a tio n o f Co(DH)2 (SO^)I were c a r r i e d out a t 380 m ^u.. The fo rm a tio n q u o tie n t was c a l c u l a t e d from th e fo llo w in g e x p re s s io n : A - A ( ^ROH. - ^RX) [X"] K. o 2 1 [C] t x 1 1 + where [C] t i s th e t o t a l c o n c e n t r a t i o n o f NaCo(DH)2 (S03) OH^*511^0, and 1 i s th e c e l l l e n g t h , which i s eq u al to 1 cm. and ^rqH2 a r e t * ie e x t ^n c t ^-on c o e f f i c i e n t s of Co(DH)2 (S03 )SCN~ 2 o r Co(DH)2 (S03 > I ' 2 , and Co(DH>2 (S03> 0H~ r e s p e c t i v e l y . A i s th e ab so rb an ce o f Co(DH) (SO ) ^ o 2 3 OH^ in th e ab sen ce of X " , and A i s th e ab so rb an ce o f th e complex a t v a r io u s c o n c e n tr a tio n s of X- . The n u m e ric a l v a lu e of K -^ f o r th e fo rm a tio n of Co(DH)2 (S03 )SCN“ 2 i s 229, and t h a t of Co(DH) (SO ) I ~ 2 i s 2 .5 4 . R e s u lts were o b ta in e d 2 3 from a com puter c a l c u l a t i o n u s in g a n o n - l i n e a r l e a s t sq u a re program. The cu rv e s i n F ig . 3 a r e th e c a l c u l a t e d v a lu e o f (A - A ) / [C] a t d i f f e r e n t c o n c e n tr a tio n s of o t SCN~ w ith th e fo rm a tio n q u o t i e n t of 229, and t h a t of I - , 2 .5 4 . T a b le 2. W avelengths and A bsorbance I n d ic e s f o r K in e tic M easurem ents. Compound W avelength (m^) Absorbancy Index NaCo (DH) 2 (S03 )0H2 • 5 ^ 0 320 7.08 X 1 0 3 325 5.45 X 1 0 380 9.92 X 1 0 2 460 3.04 X 1 0 2 Na2Co (DH) 2 (S03 )SCN- 5 ^ 0 325 2.33 X 1 0 4 Na2 Co(DH)2 (S0 3 )N3 325 2.41 X io4 Na2 Co(DH)2 (S03 ) I 380 1.15 X 1 0 4 Na3 Co(DH)2 (S0 3 ) 2 - 1 2 H2 0 325 2.62 X io4 Na3 Co(DH)2 (S0 3 )S 2 0 3 320 2.67 X 1 0 4 / NaCo(DH)2 (S03) th i o u r e a 325 2.61 X 1 0 2 NaCo(DH)2 (S03 )Py 460 1.42 X 1 0 2.0 (A-Aq) [CU SCN 1 . 1 . xlO 1 . 0 . 0 . 0 . 0 . 0 . 0.125 0 0.5 0.25 0.375 Ligand C o n c e n tra tio n (M) F ig . 3 (A - A0 ) / t C J t V ersus th e C o n c e n tra tio n s of T h io c y a n a te and I o d id e 24 25 _2 T able 3. F orm ation Q u o tie n t o f Co(DH)^(SO^)(SCN) a t U n it I o n ic S tre n g th . A= 325 mu. The w eighted c o n c e n t r a t i o n of t h e complex i s 2.88 x 10 ^ M. [ SCN~ ] (M) A A-A.. x 1 0 CC]t 0 0.170 (A0 ) 0 . 0 1 0.562 1.36 0 . 0 2 0.620 1.56 0.03 0.662 1.70 0 .04 0.678 1.78 0.06 0.698 1.84 0.08 0.707 1.87 0 . 1 0 0.715 1.89 0 . 1 2 0.716 1.90 0.15 0.716 1.90 0 . 2 0 0.720 1.91 0 .30 0.720 1.91 0.35 0.720 1.91 0 .4 0 0.720 1.91 0 .5 0 0.720 1.91 26 T able 4. F orm ation Q u o tie n t of Co(DH)2 ( S O g ) ( I ) a t U n it I o n ic S tr e n g th . The weighed C o n c e n tra tio n of th e Complex i s 1.155 x 10"^. A= 380 m^. [ I " ] (M) Absorbance (A) A - A. „ _______ x 1 0 “ J [C]t 0 . 0 0 0.120 <Aq ) 0 . 0 1 0.158 0.329 0 . 0 2 0 . 2 0 0 0.695 0.03 0.245 1.08 0.05 0.285 1.43 0.07 0.340 1.91 0 . 1 0 0.431 2.70 0.15 0.530 3.55 0 . 2 0 0.610 4 .2 4 0.25 0.709 5 .1 0 0.30 0.770 5.65 0.35 0.800 5 .9 0 0 .40 0.860 6 .4 4 0.50 0.960 7.30 Molar Absorbancy I n d ic e s 1 5x10 3x10 2x 1 0 1 5x10 2 x 1 0 1 50 20 10 200 400 300 , 600 500 W avelength (tnu) F ig . 4 M olar ab so rb an cy in d ic e s o f Co(DH) (S0„) £ J OH^ in 1 M NaClO^ (Curve a ) , 0.1 M p y r id i n e /* ■ - 1 (Curve b ) , and 1 M NaBr (Curve c ) . 2 # 2 x 1 0 1 x 1 0 5 x 10' i -Q 0 3 u < u o o 03 - T - l JQ -O c c H 3 - 1 C tf i— l o o c 2 X 10' 1 X 10- 200 250 300 W avelength (mu) 350 400 Fig* 5 Molar absorbancy in d ic e s of Co(DH) 2 (S0 „ ) 0 H2 in SOo , SCN", N3 , S2 O3 , I " , and t h i o u r e a s o l u t i o n s . Absorbance 29 0.38 0 .36 0.34 0.32 0 .30 0.28 0.26 0 .2 4 0.22 0.8 0 .4 0.6 1.0 0.2 Bromide , M F ig . 6 . The a b so rb an ce of C o^H ^C S O )0H“ (3 x 10“-* M/1) in NaBr s o l u t i o n \ = 320 mu, n = 1, NaC104 . 30 An a tte m p t t o m easure th e a n a tio n r a t e and e q u i l i brium c o n s ta n ts f o r Co(DH) 2 (SO ^O I^ w ith Cl and Br was made. The e x t i n c t i o n c o e f f i c i n e t s of Co(DI^(SO^OH^ NaBr a r e p l o t t e d i n F ig . 6 . The ab so rb an ce change o f Co(DH)2 (S0 g ) 0 H“ i n d i f f e r e n t c o n c e n tr a tio n s o f NaBr i s v e ry sm all even a t th e c o n c e n t r a t i o n of Br- up to 1 M. The f a i l u r e to o b t a i n th e fo rm a tio n q u o t i e n t and a n a tio n r a t e o f Cl i s due to th e f a c t t h a t th e e x t i n c t i o n c o e f f i c i e n t s of CoCDH^(SO^OH^ in NaCl a r e v e r y c l o s e to th o s e of th e sim p le complex. This i n d i c a t e s t h a t th e ten d en cy to form th e c h lo r o complex i s v e r y weak. The s t a b i l i t y o f th e fo rm a tio n o f th e complexes between CoCDH^CSO^OH" and th e h a l i d e s and SCN" can be e x p re sse d in t h e o r d e r: SCN" > I" > B r “ > Cl" T his s t a b i l i t y o r d e r i s c o n s i s t e n t w ith Hauge and Hal- p e r n 's work i n t h e a n a tio n of Co(DH) (NO and CoCDH^ ( I ) 0 H2 by Cl and Br . 4. The s u b s t i t u t i o n of HqO i n CoCDtQoCSO^OI^ by V ario u s Ligands Based on q u a l i t a t i v e p r e p a r a t i v e s t u d i e s , i t was f i r s t p o in te d out by B a i l a r and Peppard t h a t th e s u l f i t e group s tr o n g l y l a b i l i z e s th e group t r a n s to i t s e l f . ^ J . C . B a i l a r and D.F. Peppard, J . Am. Chem. S o c ., 62, 105 (1940). 31 T h e ir s ta te m e n t was co n firm ed by t h e s tu d y of th e a n a tio n - 3 - 27 r e a c t i o n s o f Co(CN)4 (SOg)OH2 by CN , and t h e s u b s t i t u t i o n i n Co(NHg)4 (SQj)X^”n by a s e r i e s of l i g a n d s , 2® where X"n i s NH3 , OH", N C > 2 , o r SCN". S u l f i t e i n c o b a l t ( I I I ) - b isd im e th y lg ly o x im e complex e x h i b i t s s i m i l a r b e h a v io r. F i r s t o f a l l , th e s u b s t i t u t i o n of w a te r , which i s t r a n s to th e s u l f i t e group in Co(DH)2 (S0 3 ) 0 H2 ( s e e C hapter I I ) , p r o ceeds r a p i d l y w ith a l l lig a n d s s tu d ie d i n t h i s c h a p te r . _ 3 S econdly, th e a q u a tio n o f Co(DH)2 (S0 3 ) 2 proceeds r a p i d l y w ith i n c r e a s i n g a c i d i t y . T h is b e h a v io r i s p a r a l l e l to - S 7Q th e a q u a tio n of Co(CN)^(S0 3 ) 2 • In t h i s s e c t io n t h e a n a tio n r e a c t i o n s o f Co(DH) 2 (S0 3 ) 0 H2 by S032 , SCN", HS03 , N3 , S2 032 , I " , p y r i d i n e , and t h i o u r e a can be c o n v e n ie n tly d iv id e d in to fo u r ty p e s , which w i l l be d is c u s s e d s e p a r a t e l y . (1) The S u b s t i t u t i o n o f H 0 i n Co(DH) (SO )0H1 by 2 2 3 2 S°3 _ 2 The k i n e t i c s of s u b s t i t u t i o n of w a te r by S03 was s tu d i e d a t 25°C. The sodium io n c o n c e n t r a t i o n was h e ld a t u n i t y by th e a d d i t i o n of NaClO^. S in c e th e pK o f ^ T e w a r i , Gaver, W ilcox, and W ilm arth, op. c i t . , 6 , 611. 2®Halpem , P alm er, and B la k le y , 8 8 , 2877. 29h. Ho Chen, M.S. Tsao, R.W. G aver, P.H. Tew ari, and W.K. W ilm arth, In o rg . Chem. , _5, 1913 (1966). Co(DH)2 (SO^OH^ i s 1 0 .3 1 , i t i s n e c e s s a ry to ho ld th e pH of th e s o l u t i o n a t 7.5 o r low er to p re v e n t th e fo rm a tio n of a p p r e c ia b le amounts o f th e u n r e a c t i v e s p e c i e s , Co(DH) 2 -2 ( S O g ) O H . For t h i s re a so n H S O g was added to th e system . The d i s s o c i a t i o n c o n s ta n ts o f ^ S O g , K -^ and K2 , in NaClO^ _ 2 medium w ith io n i c s t r e n g t h a t u n i t y a r e 4 .2 6 x 10 and -7 30 4 .5 7 x 10 r e s p e c t i v e l y . The up p er cu rv e in F ig . 7 shows th e r e s u l t s a t 0 .1 M HSOg, and th e low er a t 0.05M H S O g . The w av elen g th f o r th e k i n e t i c m easurements was chosen a t 325 my. (T able 2). - 2 In o rd e r to p r o t e c t th e HSO^ and SOg from a i r o x i d a t i o n , d e io n iz e d w a te r was purged w ith gas f o r 2 0 m inutes b e f o r e th e s o l u t i o n s were p r e p a re d , and t h e k i n e t i c runs were c a r r i e d o u t u n d er n i t r o g e n atm osphere. S0 ” ^ o r HS0“ were th e n t i t r a t e d i o d i m e t r i c a l l y o r by a c id - b a s e t i t r a t i o n . No a p p r e c i a b l e change i n c o n c e n tr a tio n from a i r o x id a tio n was o b serv ed . The p s e u d o - f i r s t - o r d e r r a t e c o n s ta n ts o f t h e sub- -2 s t i t u t i o n of H O by SO a t d i f f e r e n t c o n c e n tr a tio n s of ^ 3 s u l f i t e a r e p l o t t e d i n F ig . 7 and shows t h a t th e r a t e -2 c o n s ta n ts a r e in d ep en d en t of th e c o n c e n t r a t i o n of S0g a t c o n c e n tr a tio n s g r e a t e r th a n 0 .1 M. T his i n d i c a t e s t h a t t h e a n a tio n o f Co(DH)2 (S0^)0H“ p ro ceed s a l i m i t i n g ty p e o f S^l mechanism. Co(DH)2 (S03 )0H- Co(DH)2 (S0 3)- + H2 0 ( 6 ) Frydman, F. M ils se n , T. Rengems, and H.G. S i l - l e n , Acta Chemica S c a n d ., 12, 878 (1958). 33 C o ( D H ) 2 ( S 0 3 ) - + S O ' 2 ^ C o ( D H ) 2 ( S 0 3 ) “ 3 ( 7 ) Here we have assumed t h a t th e r e a c t i v e i n te r m e d ia te Co(DH)2 (S0 g)~ g e n e ra te d d u rin g r e a c t i o n has a l i f e t i m e long enough to e x h i b i t a s e l e c t i v e r e a c t i v i t y p a t t e r n -2 -2 tow ard th e SOg and H20 i n th e system . The SOg competes so e f f e c t i v e l y t h a t th e r e a c t i o n (7) i s i r r e v e r s i b l e . The p s e u d o - f i r s t - o r d e r r a t e c o n s t a n t , k , can be e x p re sse d as kitso:2] k = — ------ ^---------------------- + kgCHSOg] ( 8 ) k 2 / k g + [ S O g 2 ] The r a t e c o n t r i b u t e d by HSOg i s t h e term o f kg[H S0g] , which im p lie s t h a t th e r e a c t i o n p ro ceed s by th e fo llo w in g p a th : C o ( D H ) 2 ( S O g ) O H 2 + H S O g ' * C o ( D H > 2 ( S O g > 2 3 + H g 0 + ( 9 ) kg i s o b ta in e d from th e r a t e measurement in th e ab sen ce of - 2 S O g when th e c o n c e n t r a t i o n o f H S O g i s a t 0.05 and 0 .1 M r e s p e c t i v e l y . The n u m b e ric a l v a lu e o f k^ i s eq u al to 0 .5 5 7 ^ 0 .0 3 , and k 2 / k 3= 0 .0808^0.005. These v a lu e s were o b ta in e d from th e com puter c a l c u l a t i o n by u s in g a non l i n e a r l e a s t sq u a re method. The a v erag e e r r o r f o r th e 16 p o in ts i s 3.1% and t h e maximum e r r o r i s 8 . 6 %. The s o l i d l i n e s i n F ig . 7 r e p r e s e n t th e p r e d i c t e d v a lu e s of k based on th e v a lu e s o f th e k i n e t i c p a ra m e te rs l i s t e d above. In q u a n t i t a t i v e term s th e mechanism does n o t sec .0 (HSOo” ) = 0.10M .8 r\ . 6 ( hso3~ 0 . 05M .4 2 0 0.04 0 .16 0.08 0.12 0.20 (S03— ) , M F ig . 7. P s e u d o - f i r s t - o r d e r Rate C o n stan t v e r s u s S u l f i t e C o n c e n tra tio n 35 T a b le 5. P s e u d o - f i r s t - o r d e r Rate C o n sta n ts f o r th e Sub s t i t u t i o n W ater i n Co(DH)2 (SO g)(O I^)” by S O ^ a t U n it I o n ic S tre n g th . I SOy-] (M) [HSO3 J (M) - log [H+] t ^ ( s e c . ) k (secT 1 ) 0 . 0 0 0 . 1 0 5.086 1 . 1 2 0.621 0 . 0 2 0 . 1 0 5.857 0.956 0.725 0 .03 0 . 1 0 6.132 0.922 0.752 0 .04 0 . 1 0 6.142 0.865 0.801 0.05 0 . 1 0 6.232 0.825 0.840 0.06 0 . 1 0 6.307 0.789 0.878 0.075 0 . 1 0 6.414 0.745 0.930 0 . 1 0 0 . 1 0 6.532 0.702 0.987 0.14 0 . 1 0 6.677 0.687 1.009 0.16 0 . 1 0 6.755 0.694 0.999 0 . 2 0 0 . 1 0 6.849 0.685 1 . 0 1 0 0 . 0 0 0.05 5.041 2.31 0.300 0 . 0 2 0.05 6.291 1. 78 0.388 0.05 0.05 6.674 1.40 0.494 0 . 1 0 0.05 6.996 1.16 0.600 0.13 0.05 6.956 1.08 0.641 0.175 0.05 7.132 1 . 1 0 0.630 0 . 2 0 0.05 7.273 1.09 0.635 3 6 q u i t e seem to re p ro d u c e th e e x p e rim e n ta l d a t a to w ith in o u r e s tim a te o f th e e x p e rim e n ta l e r r o r . I n p a r t i c u l a r , th e c a l c u l a t e d v a lu e s of k a r e to o low a t i n t e r m e d ia te -2 SO3 c o n c e n t r a t i o n i n th e ex p erim en ts a t 0 .1 M HSO^ and _ o a r e to o h ig h a t th e h i g h e s t SO^ c o n c e n t r a t i o n in th e ex perim ents a t 0.05 M HSOg. At p r e s e n t we have no s a t i s f a c t o r y e x p la n a tio n f o r t h i s d is c re p a n c y . (2) The S u b s t i t u t i o n o f ^ 0 i n Co(DH)2 (SOg)OH2 by SCN' The k i n e t i c s o f r e a c t i o n (10) was s tu d ie d a t 25°C and an io n ic s t r e n g t h of 1 . 0 . Co (DH) 2 (S03 ) OH^ + SCN" -------* Co(DH)2 (S03 )SCN" 2 + f^O ( 10) F ig . 8 shows a p l o t o f th e p s e u d o - f i r s t - o r d e r r a t e co n s t a n t s v e r s u s th e c o n c e n t r a t i o n o f SCN' i n n e u t r a l s o l u t i o n of pH n e a r 7, th e F ig . 8 shows th e r a t e c o n s ta n ts v e rs u s t h e pH a t a c o n s ta n t c o n c e n t r a t i o n o f SCN' o f 0.1 M. The d a t a a r e l i s t e d in T a b le s 6 and 7. From F ig . 8 i t i s a p p a re n t t h a t Co(DH)2 (SO^OH^ becomes k i n e t i c a l l y i n e r t when t h e pH o f th e s o l u t i o n i s g r e a t e r th a n 7 .5 , and th e s u b s t i t u t i o n r a t e by SCN' w i l l be in d ep en d en t of pH i f th e pH o f th e s o l u t i o n i s l e s s th a n 7 .5 . T h e re fo re th e k i n e t i c m easurements of s u b s t i t u t i o n o f H2 O by SCN" were c a r r i e d o u t a t pH l e s s th a n 7 .5 . The pH o f th e s o l u t i o n was a d ju s te d by adding v e ry 37 sm all amounts o f HC10,. The r e a c t i o n was fo llo w e d a t 4 w av elen g th 325 mu (Table 2, F ig . 4 and 5 ). The a n a tio n of Co(DH)2 (SO^)OH" by SCN" p r e s e n ts an i n t e r e s t i n g mechanism. The e x p e rim e n ta l p o in ts i n F ig. 8 show t h a t th e c u r v a t u r e a t low c o n c e n tr a tio n o f SCN", a lth o u g h s m a ll, i s s i g n i f i c a n t . The o bserved r a t e con s t a n t , k , i s alm ost l i n e a r l y p r o p o r t i o n a l to th e c o n c e n t r a t i o n of SCN", when SCN" i s g r e a t e r th a n 0 .2 M. This i n d i c a t e s t h a t t h e s u b s t i t u t i o n mechanism p ro ceed s th ro u g h two p a r a l l e l p a t h s , i . e . , th e l i m i t i n g ty p e of S.,1, and S„2 mechanism. A d d itio n a l evidence i s o b ta in e d N N from t h e f a c t t h a t a t h ig h SCN" c o n c e n t r a t i o n th e r e a c t i o n p ro ceed s f a s t e r th an th e l i m i t i n g S ^l mechanism p r e d i c t s by a f a c t o r o f n e a r l y 16. kl P a th a Co(D H ).(S0.)0H : *— a Co(DH)0 (SO_) + H Q (11) Z J Z X e Z J Z 2 k 3 -2 Co(DH)? (S0 ) + SCN" Co(DH)9 (S0 )SCN (12) k4 k5 P a th b Co(DH)0 (S00)OHl + SCN Co(DH)_(S0Q) L 5 L 6 z J SCN' 2 + H20 (13) From th e measurement of th e fo rm a tio n q u o t i e n t o f Co(DH)2 (SOg)SCN"2 , th e a n a tio n r e a c t i o n does n o t p roceed t o c o m p le tio n , e s p e c i a l l y a t low c o n c e n t r a t i o n o f SCN and h ig h pH. The fo rm a tio n q u o t i e n t f o r th e a n a tio n r e - p a c t i o n 38 * 1 _2 ROH2 + SCN" RSCN + H20 (14) i s Kx = [RSCN~2] , [ROH^ [SCNl (15) where R r e p r e s e n t s Co(DH)2 (SO^)" r a d i c a l . ROH2 i n th e s o l u t i o n i s i n e q u ilib r iu m w ith i t s O c o n ju g a te b a s e ROH . ROH2 + OH' - ROH' 2 + H20 (16) Let CR]t be t h e t o t a l amount of com plex, which i s equal to [R]t = [ RSCN"2] + [R0H~3 + [ROH- 2 ] = [ r s c n “ 2 ] + [roh- ] + [ r o h ^ k 2 [oh"J = t RSCN- 2 ] + [ROH~ 3 { l + K [OH] } (17) o r [ROH^] = [Kl - tRSCN' 2] {[R]t - [ RSCN- 2)}tSCN- ] (18) S u b s t i t u t e (18) i n t o (15) and s im p l i f y , and we g e t Ki [RSCN-2 ] 1 = (19) 1 + K2 [o h ! {[R]t - [ RSCN' 2 ]}[ SCN"] The a n a tio n p ro ceed s o n ly to 69.57., i f [ SCNl i s a t 0 .0 1 M i n n e u t r a l s o l u t i o n of pH 7, and o n ly to 63.27> i n 0 .1 M SCN" a t pH 11.33. 39 The p re s e n c e o f t h e i n e r t s p e c i e s , Co(DH)2 (S03 ) _ 2 OH , c a u se s th e d e c r e a s e o f r a t e c o n s ta n ts o f forw ard r e a c t i o n s (k^ and k^) by a f a c t o r o f 1 /(1 + k^[O H ]), b u t th e r e v e r s e r e a c t i o n s (k^ and k^) a r e in d ep en d en t of OH c o n c e n tr a tio n . The o b serv ed r a t e c o n s ta n t f o r th e a n a tio n p r o c e ed in g th ro u g h p a th a and p a th b can be e x p re sse d as k . k x [SCNl x 1 + k T /Kt k 2/ k 3 + [SCN"] 1 + K2 [OH"] k 2 / k 3 + [ SCN"] k , [SCN“] k R , v + 5_________ + 5 (20) 1 + k2[ oh“ ] K where K -^ i s th e fo rm a tio n q u o t i e n t . From th e m ic ro sc o p ic r e v e r s i b i l i t y re q u ire m e n ts o f th e a n a t i o n , i s eq u al to k-L k 2 / k 3 k ^ , o r k 5 / k 6 . The n u m e ric a l v a lu e s o f t h e k ' s were o b ta in e d from a n o n - l i n e a r l e a s t sq u a re com puter program c a l c u l a t i o n w ith t h e f ix e d p a ra m e te r k = 0.557 o b ta in e d from th e _ 1 _ 2 a n a t i o n of Co(DH)2 (S03 )0H2 by S03 . The c a l c u l a t e d v a lu e s a r e k 2 / k 3 = 0 .1 0 2 -0 .0 2 0 , k5= 8 .3 1 - 0 .0 6 , Kx = 267-62, and K2 = 6727*1300. The a v e ra g e e r r o r f o r th e 25 p o in ts i s 5.187o, and th e maximum e r r o r i s 297o. The v a lu e s of and K2 o b ta in e d from e x p e rim e n ta l measurem ents a r e K -^ = 229, and K2 = 2880 (se e pH t i t r a t i o n ) . The e x p e rim e n ta l d a t a f o r were t r e a t e d by a non- SCN 4 Tu 3 HSO 2 1 1 0 0.1 0.2 0.4 0 .3 0.5 (X 'n ) , M F ig . 8 . P s e u d o - f i r s t - o r d e r Rate C o n stan ts o f Ana t i o n of Co(DH)2 (SOg)(OH2 ) by T h io u re a , SCN~ , i ” , N^, P y r id in e , S2 O2 , and HSO3 • 1 7 3 1 12 6 10 4 8 2 - lo g [H+] F ig . 9. P s e u d o - f i r s t - o r d e r Rate C on stan t v e rs u s pH a t 0 .1 M of SCN- . 42 T ab le 6 . P s e u d o - f i r s t - o r d e r R ate C o n sta n ts f o r th e D is placem ent of H2 O i n CoCDH^CSO^) (O I^ )' by SCN" a t c o n s ta n t - lo g [H+] o f 7 .0 . [ SCN~] (M) t , ( s e c . ) k ( s e c - ^) 1 2 0 . 0 1 4 .3 3 0.160 0 . 0 2 2.75 0.252 0.03 2.69 0.388 0.04 1.28 0.542 0.06 0.940 0.738 0.08 0.717 0.968 0 . 1 0 0.609 1.14 0 . 1 2 0.518 1.34 0.15 0.418 1 . 6 6 0 . 2 0 0.320 2.17 0.30 0.232 2.99 0.35 0.205 3.38 0.40 0.182 3.80 0 .5 0 0.152 4 .5 4 43 T ab le 7. P s e u d o - f i r s t - o r d e r R ate C o n sta n ts f o r th e Dis placem ent o f H20 in Co(DH)2 (S 0 3 )0H 2 by SCN“ a t v a r io u s a c i d i t i e s . The SCN” c o n c e n tr a tio n 0 .1 M. -lo g [H +] t i ( s e c . ) k ( s e c . " l ) 0 .5 4 0.604 1.14 1 . 6 6 0.604 1.14 2 .7 0 0.604 1.14 5.32 0.604 1.14 6 . 62 0.604 1.14 7.15 0.604 1.14 8 .8 0 0.687 1 . 0 1 8.89 0.697 0.995 10.40 1.70 0.409 11.03 4.89 0.142 11.33 6 . 2 0 0 . 1 1 2 44 l i n e a r l e a s t sq u a re com puter program c a l c u l a t i o n . Among th e t o t a l 14 p o in ts th e a v e ra g e e r r o r i s 0.87, and t h e m axi mum e r r o r i s 2.47.. The u p p e r c u rv e i n F ig . 3 was drawn w ith th e c a l c u l a t e d fo rm a tio n q u o t i e n t o f 229. A lthough th e s e v a lu e s a r e of th e same o r d e r of mag n i t u d e , th e d e v i a t i o n i s l a r g e e s p e c i a l l y f o r K^. An a tte m p t to c a l c u l a t e th e k ' s was c a r r i e d out by f i x i n g = 0 .5 5 7 , = 229, and = 2880. The r e s u l t s o b ta in e d w ere ^ ^ 3 ~ 0*119*0.017 and k^ = 8 .3 1 * 0 .0 9 . The av erag e e r r o r i s 7.87. and t h e maximum e r r o r i s 577,. Both s e t s of k ' s g iv e alm ost th e same c a l c u l a t e d c u rv e i n F ig . 8 , which f i t s th e e x p e rim e n ta l p o i n t s v e r y w e ll. However, in F ig . 9 th e dashed l i n e c a l c u l a t e d from th e n u m e ric a l v a lu e s o f o n ly one f ix e d p a ra m e te r f i t s th e e x p e rim e n ta l p o in ts b e t t e r th a n th e s o l i d c u rv e , where th e t h r e e k ' s were f ix e d . (3) The S u b s t i t u t i o n of ^ 0 i n Co (DH) 2 ( 8 0 3 ) 0 ^ by T h io u re a , A zide, B i s u l f i t e , P y r id in e , and T h i o s u l f a t e . The a n a tio n r e a c t i o n s of Co(DH) 2 ( S O ^ O ^ pro ceed e s s e n t i a l l y to c o m p letio n . The r e a c t i o n s can be e x p re sse d by th e fo llo w in g e q u a tio n . k - C o ( D H ) 2 ( S 0 3 ) 0 H - + X " n --------> C o ( D H ) 2 ( S 0 3 ) X " n " l + ^ 0 ( 2 1 ) where X~n = S C ^ I ^ , N^, HS0“ , C ^ N , and S2 O3 2 . The wave le n g th s chosen f o r k i n e t i c measurem ents a r e l i s t e d in 45 T able 2. 31 S in ce p y r id i n e i s a weak b a s e , th e s o lu t i o n s f o r k i n e t i c m easurements were b u f fe r e d w ith 0.05 M p y r i- dinium p e r c h l o r a t e . Under t h i s c o n d itio n th e c o n c e n tr a t i o n of th e i n e r t s p e c ie s (Co(DH) (SO )0H"2 i s n e g l i g i b l e . ^ 32^ 33 S in ce t h i o u r e a i s a l s o a weak b a s e , and a z id e i s th e s a l t of a weak a c i d , t h e i r s o l u t i o n s a r e b a s ic (Appendix I I ) . A sm all amount o f HCIO^ was added to t h e s o lu t i o n s and th e pH was a d ju s te d to t h e re g io n 4 - 7 . T h i o s u l f a t e decomposes in a c i d i c s o l u t i o n when th e pH i s s m a lle r th an _ 2 5, so th e pH o f $ 2 0 ^ s o l u t i o n were a d ju s te d t o th e re g io n 6 - 7. The p s e u d o - f i r s t - o r d e r r a t e c o n s ta n ts v e rs u s th e c o n c e n tr a tio n of th e s e lig a n d s a r e p l o t t e d i n F ig . 8 , and l i s t e d in Tables 8- 12. The r a t e un d er th e p s e u d o - f i r s t - o r d e r c o n d itio n can be e x p re sse d in t h e fo llo w in g form. d [Co(DH)2 (S0 3 ) 0 H2] = k £ Co(DH) 2 (So 3 )OH2 ] ( 2 2 ) d t where k i s th e observed r a t e c o n s ta n t, which i s eq u al to k '[X ~ n ]. k 1 i s th e s p e c i f i c second o rd e r r a t e c o n s ta n t. 3 1 j. B jerium , Chem. Rev. , 46, 381 (1950). ^ R . J . Bruchlman and F.H. Verhoek, J . Am. Chem. S o c . , 70, 1401 (1948). ■^E.A. Burns and F.D. Chang, J . Phys. Chem. , 63, 1314 (1959). 46 S t r a i g h t l i n e s w ith z e ro i n t e r c e p t were found f o r th e t h i o u r e a , a z i d e , b i s u l f i t e , and t h i o s u l f a t e system s. T h is i n d i c a t e s t h a t th e a n a tio n by t h e s e f o u r lig a n d s p ro c e e d s to co m p letio n and t h a t th e r e v e r s e r e a c t i o n i s n e g l i g i b l e . For th e p y r id i n e c a s e a s t r a i g h t l i n e w ith non z e ro i n t e r c e p t i s o b ta in e d . S in ce th e ex perim ents f o r th e s e system s were c a r r i e d o u t i n weak a c id medium, th e e q u ilib r iu m betw een th e p y r id i n e and p y rid in iu m io n e x i s t s i n th e s o l u t i o n . Py + H+ PyH+ (23) The e q u ilib r iu m c o n s ta n t f o r t h e above r e a c t i o n 5 04 i s found to be 1.62 x 10 . Under th e e x p e rim e n ta l c o n d itio n s u se d , a c o n s id e r a b le amount of p y r id i n e i s in t h e form o f PyH+ and th e c o n c e n t r a t i o n of f r e e p y r id in e i s reduced by t h e p re s e n c e o f a c id . Column 4 o f T ab le 11 g iv e s th e e f f e c t i v e c o n c e n t r a t i o n (for c a l c u l a t i o n s e e Appendix I I ) of p y r id i n e in th e s o l u t i o n , and th e p l o t o f o b se rv e d r a t e c o n s ta n ts v e rs u s t h e e f f e c t i v e c o n c e n t r a t i o n o f p y r id i n e i s a s t r a i g h t l i n e w ith z e ro i n t e r c e p t . This r e s u l t im p lie s t h a t th e a n a t i o n by p y r id i n e p ro ceed s to c o m p letio n . The n u m e ric a l v a lu e s o f s p e c i f i c second o r d e r r a t e c o n s ta n ts f o r t h e above system s o b ta in e d from th e slo p e s 34 B jerium , op. c i t . , 46, 381. o f l i n e a r p l o t s a r e l i s t e d as below . 47 L ig an d X_n k 1 (secT ^ ) t h i o u r e a 8 .3 6 a z i d e 7 .3 8 b i s u l f i t e 6 . 1 0 p y r i d i n e 5 .1 0 t h i o s u l f a t e 1 .4 5 The o r d e r o f r e a c t i v i t y o f t h e s e l ig a n d s f o r th e a n a tio n o f Co(DH)2 (SO^)OH" i s t h i o u r e a > a z i d e ) b i s u l f i t e > p y r i d i n e ) t h i o s u l - fate The s u b s t i t u t i o n by t h i o u r e a i s th e f a s t e s t among t h e s e l i g a n d s , p o s s i b l y b e c a u se i t i s a n e u t r a l m o le c u le w ith o u t n e g a t i v e c h a r g e , and a l s o i t h as g r e a t e r te n d e n c y to form 7T bonds (C o-S) in th e a c t i v a t e d com plex th a n -2 t h a t in p y r i d i n e and a z id e . A lth o u g h S i n SO^ can form bonds w ith c o b a l t , i t c a r r i e s two n e g a t i v e c h a r g e s , so th e a n a t i o n r a t e i s s lo w e r th a n t h a t o f t h i o u r e a . T h io - s u l f a t e io n c a r r i e s two n e g a tiv e c h a r g e s , c o n s e q u e n tly , th e a n a tio n r a t e i s t h e s lo w e s t. 48 T a b le 8 . The R ate o f F orm ation o f Cc^DH^CSO^) T h io u rea a t 25°C and I o n ic S tr e n g th 1 .0 T h io u re a (M) - logCH+ 3 t i ( s e c ) k ( s e c " ^ ) *2 0 . 0 2 6 .4 4 3 .6 9 0 .1 9 3 0 .0 5 7 .3 4 1 .6 5 0 .4 2 0 0 . 1 0 5 .0 0 0.8 3 5 0 .8 3 0 0 . 2 0 6 .4 2 0 .4 1 0 1 .6 9 0 .3 0 5 .5 3 0 .3 0 0 2 .3 1 0 .4 0 4 .4 8 0.2 0 8 3 .3 3 0 .5 0 4 .7 5 0 .1 6 5 4 .2 0 49 T a b le 9 . The R ate o f F orm ation o f CoCDH^CSO^) a t 25°C and I o n ic S tr e n g th 1 .0 L N„] (M) - lo g [H+] t x ( s e c ) k ( s e c *) 0 . 0 2 7 .5 0 3 .3 0 0 . 2 1 0 0 .0 5 7 .1 5 1 .6 1 0 .4 3 0 0 . 1 0 6 .7 9 0 .9 2 5 0 .7 5 0 0 . 2 0 7 .1 3 0 .4 6 0 1 .5 1 0 .3 0 7 .2 0 0 .3 1 5 2 . 2 0 0 .4 0 7 .3 3 0 .2 3 4 2 .9 6 0 .5 0 7 .2 6 0 .1 9 1 3 .6 4 50 T a b le 10. P s e u d o - F ir s t- O r d e r R a te C o n s ta n ts f o r th e S u b s t i t u t i o n o f W ater i n Co(DH) 2 (SO^) (O I^) by HSO^ a t U n it I o n ic S t r e n g t h . [HSO " ] (M) - lo g [H+ ] ti, ( s e c . ) kCSecT1 ) J 2 0 .0 2 5 .0 2 0 5 .7 7 0 .1 2 0 0 .0 4 5 .0 4 4 3 .1 5 0 .2 2 0 0 .1 0 5 .0 1 0 1 .1 1 0 .6 2 1 0 .2 0 5 .0 5 0 0 .5 7 7 1 .2 0 0 .4 0 5 .0 4 0 0 .2 7 7 2 .5 0 0 .5 0 5 .0 1 4 0 .2 2 8 3 .0 4 51 T a b le 11. The R ate o f F orm ation o f CoCDH^CSO^) P y r id in e a t 25°C and I o n ic S tr e n g th 1 .0 . T o ta l Cone, o f C o r r e c te d P y r i d i n e , (M) -lo g [H + ] t i , ( s e c . ) C o n e .o f Py k ( s e c . ) (M ) 0 .0 5 5 .1 6 6 7 .2 0 0 .0 2 4 0 0 .0 9 0 0 .0 6 5 .4 2 6 3 .6 7 0 .0 3 7 3 0 .1 8 9 0 . 1 0 6 .2 2 6 1 .5 1 0 .0 9 1 3 0 .4 6 0 0 .3 0 6 .5 4 6 0.485 0 .2 8 7 1 .4 3 0 .4 0 6 . 646 0 .3 5 4 0 .3 8 7 1 .9 6 0 .5 0 6 .8 0 6 0 .2 7 6 0 .4 8 8 2 .5 1 52 T a b le 12. The R ate o f F orm ation o f Co(DH)2 (S 0 g )S 202^ a t 25°C and I o n ic S tr e n g th 1 .0 . [ s 2 0 “ 2j (m) - log[H + ] t ^ ( s e c . ) k (s e c T ^ ) 0 . 0 2 6 .9 6 2 1 . 0 0 .0 3 3 0 .0 4 6 .9 4 1 3 .6 0 .0 5 1 0 .0 8 6 .8 4 6 .3 6 0 .1 0 9 0 .1 5 6 .8 2 3.1 6 0 .2 1 9 0 .2 5 6 . 8 6 1.8 9 0 .3 6 7 0 .3 5 6 .6 7 1 .5 0 0 .4 6 2 0 .5 0 7.15 0 .9 3 0 .7 4 5 53 (4 ) The S u b s t i t u t i o n o f H^O i n Co(DH)2 (SOg)OH2 by I~ The s u b s t i t u t i o n o f 1 ^0 by I ” d o es n o t go to com p l e t i o n . The e v id e n c e f o r t h i s i s o b ta in e d from t h e f a c t t h a t th e a b s o rb a n c e a t 380 mp i n c r e a s e s w ith i n c r e a s i n g i o d i d e c o n c e n t r a t i o n . F ig . 5 g iv e s th e a b s o rb a n c e o f Co(DH)2 (SOg)OH^ i n 0 .3 1 8 M I - s o l u t i o n . The p s e u d o - f i r s t - o r d e r r a t e c o n s ta n ts f o r t h e s u b s t i t u t i o n o f w a te r by I" a r e shown i n F ig . 8 . The e x t i n c t i o n c o e f f i c i e n t o f Co(DH) 2 ( S O ^ I ^ a t 380 m^i i s 1 .1 4 x 1 0 ^ , w hich was o b ta in e d from t h e i n t e r c e p t o f a l i n e a r p l o t o f [ c 3 t /( A - Aq ) v e r s u s The a n a t i o n o f Co(DH)2 (SOg)OH2 by I - was fo u n d to a t t a i n a m e a s u ra b le e q u i l i b r i u m a t I" c o n c e n t r a t i o n s up to 0 .5 M. The r a t e o f a p p ro a c h to e q u i l i b r i u m u n d e r t h e p s e u d o - f i r s t - o r d e r r e a c t i o n c o n d i t i o n i s 1 / C l " ] . c o ( d h ) 0 ( s o 0 )o h : + i d [Co(DH)2 (S03 )0H2 3 k [Co(DH)2 (S03 )0H-J[ I " ] - k _1 tCo(DH)2 (S03 ) I ’ 2 ] Co(DH)2 (S03 ) I - 2 + H20 (24) d t (25) [Co(DH) (SO )0H~] [Co(DH) (SO )0 H "j - [Co(DH (SO )0H~ ) 2 3 2 * > 2 3 2 t (26) k = k^ [ I 3 + k ^ (2 7 ) 54 T a b le 13. P s e u d o - F ir s t- O r d e r R a te C o n s ta n ts f o r th e Sub s t i t u t i o n o f W ater i n Co(DH>2 (S0 g) (OHL,)” by I a t U n it I o n ic S t r e n g t h . [ I “ ] (M) ti ( s e c . ) k (sec?-*-) 0 .0 1 8 0 .3 1 5 2 . 2 0 0 .0 4 6 0 .2 9 0 2 .3 9 0 .0 6 9 0 .2 6 9 2 .5 8 0 .0 9 2 0 .2 7 2 2.55 0 .1 1 7 0 .2 4 8 2 .8 0 0 .1 8 8 0 .2 1 6 3 .2 1 0 .2 4 7 0 .1 9 7 3 .5 3 0 .2 9 9 0 .1 8 1 3 .8 3 0 .3 4 0 0 .1 6 2 4 .2 8 0 .3 9 2 0 .1 5 7 4 .4 1 0 .4 6 7 0 .1 5 3 4 .5 3 55 The l i n e a r p l o t o f k v e r s u s [ I “! i n F ig . 8 g iv e s n u m e ric a l v a lu e s o f k and k o f 5..50 and 2 .1 5 r e s p e c t - 1 - 1 - i i v e l y . The r a t i o o f k and k i s 2 .5 5 M , w hich i s i n 1 -1 e x c e l l e n t ag reem en t w ith t h e f o rm a tio n q u o t i e n t m e a su re m en t, K = 2 .5 4 M ” \ a t th e w a v e le n g th o f 380 mjx. The f o rm a tio n q u o t i e n t , K = 2 .5 4 ^ 0 .0 3 M - ^ , was o b ta in e d from t h e co m p u ter c a l c u l a t i o n o f a n o n - l i n e a r l e a s t s q u a re program . The a v e ra g e e r r o r f o r th e 13 p o i n t s i s 3.27», and t h e maximum e r r o r i s 14.1% 5. The A q u a tio n o f Co (D H ^ ( S O g ) ^ _ 3 The a q u a tio n o f Co(DH)^ (S O ^ ^ was s t u d i e d a s a f u n c t io n o f pH a t 25°C and u n i t i o n i c s t r e n g t h . The _ 3 s p e c tru m o f Co(DH)2 (S O ^ ^ i-n a c i d i c s o l u t i o n i s i n q u a n t i t a t i v e ag reem en t w ith t h a t o f a s o l u t i o n o f NaCo (D H ^CSO pC H ^’S ^ O . I t was e s t a b l i s h e d t h a t t h e a q u a tio n i s c o m p le te even when t h e h y d ro g en c o n c e n t r a t i o n i s as low a s 1 0 ” ^M. Co (DH) (SO ) - 3 + H 0+ -----> Co (DH) (SO )0H"+ HSO" 2 3 2 3 2 3 2 3 (28) The a c i d i t y was m easu red w ith a pH m e te r , w hich had b e e n c a l i b r a t e d w ith a known h y d ro g en io n c o n c e n tr a t i o n . The w a v e le n g th c h o se n f o r th e a q u a tio n s tu d y was a t 325 mia. The k i n e t i c s o f th e a c i d - c a t a l y z e d a q u a tio n o f Co(DH) (SO ) “ 3 i s e n t i r e l y a n a lo g o u s to t h a t r e p o r t e d 56 - 5 35 f o r Co(CN )^(S0 2 ) 2 • The k i n e t i c d a t a can b e i n t e r p r e t e d a s th e a q u a tio n o f two p r o to n a te d c o m p le x e s, HCo(DH) (SO ) , and H Co(DH) SO ) “ . 2 3 2 2 2 3 2 Co(DH) (SO ) “ 3 + H 0 — U Co(DH) (SO )0H“ + SO" 2 (29) 2 3 2 2 2 3 2 3 HCo(DH) (SO ) " 2 H+ + Co(DH) (SO ) ' 3 (30) 2 3 2 2 3 2 - 9 k 9 HCo(DH) (SO ) + H 0 — ^ Co(DH) (SO )OH + HSO (31) 2 3 2 2 2 3 2 3 and H Co(DH) (SO ) - H + + HCo(DH) (SO ) “ 2 (32) 2 2 3 2 2 3 2 - k 9 H2 Co(DH)2 (S03 ) 2 — 1* Co(DH)2 (S03 )0H2 + S02 (33) The o b s e rv e d r a t e c o n s ta n t i s g iv e n by th e e x p r e s s io n : k = k A Ks + V M hH] + V H + ] 2 0 4 ) K.K. + K [H+] + [H 4! 2 4 5 5 w h ere k ^ , k 2 , k 3> K^, and K2 a r e c o n s ta n ts f o r r e a c t i o n s (29) th ro u g h (3 3 ). The n o n - l i n e a r l e a s t s q u a re co m p u ter c a l c u l a t i o n g iv e s th e k i n e t i c p a r a m e te rs a s f o llo w s : k 1 = ( 4 .3 3 ± 1 .6 6 ) x l0 " 3 , k 2 =0. 2 1 -0 . 2 4 , k 3= 3 .1 1 - 0 .1 8 , K4 =<L.67± 1 . 3 7 ) x l 0 - 3 , K3 = H 6 . 1 9 * 1 .4 6 )x 1 0 ~ 3 , w here t h e u n c e r t a i n t i e s l i s t e d a r e th e s ta n d a r d d e v i a t i o n s . I n th e n o n l i n e a r l e a s t s q u a re c a l c u l a t i o n s i n d i v i d u a l k v a lu e s w ere Chen, T sa o , G a v e r, T e w a ri, W ilm a rth , op. c i t . , 5 , 1913. 57 w e ig h te d b y t h e f a c t o r 1 / k ^ , a p r o c e d u re w hich assum es t h a t t h e p e r c e n t e r r o r i n a l l e x p e rim e n ts i s th e same. The c u rv e i n F ig . 10 r e p r e s e n t s t h e v a lu e s o f k c a l c u l a t e d f o r th e d a t a o b ta in e d in NaClO^ s o l u t i o n s u s in g t h e s e p a r a m e te rs . The a v e ra g e e r r o r f o r 14 p o i n t s i s 9.57>, and th e maximum e r r o r i s 187o. 5 .0 2.0 1.0 0 .5 ‘cT1 0.2 0.1 0 .0 5 0.02 0.01 0.0 0 5 0 1 2 3 4 5 - lo g [H + ] -3 F ig . 10. The R ate o f A q u atio n o f Co(DH)2 (SO^)^ a t u n i t I o n ic S t r e n g t h , NaClO^. 58 59 T a b le 1 4 . The R ate o f A q u ation o f C o ( D H ) 2 ^ 0 . j ) at D if f e r e n t A c id ity a t U n it I o n ic S tr e n g th PH - lo g [H+ ] R a te C o n s ta n t ( s e c l i ) 0 .1 3 0 0 .3 8 8 3 .2 2 0 .1 7 0 0 .4 2 8 3 .2 7 0 .2 5 0 0 .5 0 7 2 .9 5 0 .5 3 0 0 .7 8 5 2 .9 1 1 .3 8 0 1 .6 2 7 2 .5 8 1 .6 4 0 1 .8 8 3 1 .7 6 1 .9 8 6 2.2 2 7 1 .6 3 2 .2 9 8 2 .5 6 6 0 .9 2 0 2 .4 5 0 2.6 8 7 0 .4 9 3 2 .9 9 0 3 .2 2 3 0.1 4 2 3.075 3.3 0 6 0.0975 3 .5 1 0 3 .7 3 7 0.0347 4 .2 3 8 4 .4 5 8 0.00782 4 .3 3 8 4 .5 5 7 0.00915 60 6 . I n f r a r e d s tu d y o f th e b o n d in g b etw een c o b a l t and SCN , and t h i o u r e a i n Co(DH) (SO )SCN"^ and 2 3 Co(DH) (SO )SCN H_ . 2 3 2 4 The mode o f a tta c h m e n t o f th e SCN~ lig a n d t o c o b a l t c a n b e d e te rm in e d on th e b a s i s o f th e IR s p e c t r a . The a s s ig n m e n t, o f v a r i o u s v i b r a t i o n s f o r th e t h i o c y a n a t e com plexes h av e b e e n made by many a u t h o r s . 3 6 ,3 7 ,3 8 ,3 9 The f re q u e n c y r a n g e , i n cm“ ^ u n i t , f o r d i f f e r e n t modes i s l i s t e d i n th e t a b l e as below : V ib r a tio n s N b o n d in g S b o n d in g NCS b e n d in g 475 400-4 4 0 * C-S s t r e t c h i n g 780-860 670-740 C-N s t r e t c h i n g 2 1 0 0 2 1 0 0 * More th a n one band a p p e a r s , b u t 420 i s th e m ost in - t e n s e one. The C-S s t r e t c h i n g fre q u e n c y i s th e m ost w id e ly 36p.C . M it c h e l l and R .J .P . W illia m s , J . Chem. S o c . , 1912 (1 9 6 0 ). 37 M.M. C h am b e rla in and J .C . B a i l e r , J r . , J . Am. Chem. S o c. , 8 1 , 6412 (1 9 5 9 ). ^ A. T urco and C. P e c i l e , N a tu r e , 1 9 1 , 6 6 (1 9 6 1 ). OQ A. S a b a tin and I . B e r t i n i , I n o rg . Chem., 4 , 959 (1 9 6 5 ). 61 u s e d . The s u l f u r bonded t h i o c y a n a t e com plexes show v e r y weak C-S s t r e t c h i n g f r e q u e n c ie s b etw een 670-740 c m '^ , w h ereas f o r N bonded i s o t h i o c y a n a t e co m p le x es, th e a b o rp - t i o n i s v e r y s h a rp a t h ig h e r f re q u e n c y 780-860 cm- *-. The C-N s t r e t c h i n g , a lth o u g h s tr o n g and s h a r p , i s l e s s u s e f u l i n s t r u c t u r e a s s ig n m e n t. The IR s p e c t r a o f Na2 Co(DH)2 (SOg)SCN and Co(DH) 2 (NCS)0 H2 a r e shown i n F ig . 11. The o b s e rv e d a b s o r p t i o n b ands a r e l i s t e d i n t h e f o llo w in g t a b l e . V ib r a tio n s Co(DH)2 (NCS)OH2 Na2 Co(DH)2 (S03 )SCN NCS b e n d in g 465 weak 420 s h o u ld e r C-S s t r e t c h i n g 820 s h a rp 710 s h o u ld e r C-N s t r e t c h i n g 2 1 0 0 s tr o n g 2 1 2 0 s tr o n g The e x i s t e n c e o f t h e 820 cm"'*- band i n Co(DH) 2 (NCS)0 H2 s t r o n g l y i n d i c a t e s t h e b o n d in g i s th ro u g h th e n i t r o g e n atom . The weak C-S s t r e t c h i n g f o r Na^Co(DH)^ (SOg)SCN i s p a r t l y o v e rla p p e d by th e band o f d im e th y - lg ly o x im e , w hich a p p e a rs a t 740 cm"*-. However, t h e d i s a p p e a ra n c e o f t h e s h a rp a b s o r p t i o n p eak a t 820 cm"*- i n d i c a t e s th e b o n d in g i s n o t th ro u g h n i t r o g e n atom in Na2 Co(DH)2 (S03 )SCN. The 2060 cm- * - band i n N a2Co(DH)2 (SO^)SCN i s due to t r a c e s o f NaSCN. T h is was c o n firm e d by th e f a c t t h a t 62 th e i n t e n s i t y o f 2060 cm ^ band i n c r e a s e s v e r y much a f t e r a d d in g e x t r a NaSCN. The t r a c e NaSCN i s due t o th e decom- _o p o s i t i o n o f Co(DH) 2 (SOg)SCN when i t was p r e p a r e d in aqueous s o l u t i o n . I t i s i n t e r e s t i n g to n o te t h a t th e r e a c t i o n o f Co(DH)^(NCS)OH^ w ith Na^SQ g iv e s a p ro d u c t w hich h a s th e same IR sp e c tru m a s t h a t o f Co(DH)2 (S0 )SCN" 2 d e s c r ib e d above. I n o r t h e r w ords th e c h a r a c t e r i s t i c C-S s t r e t c h i n g a t 820 cm” '* ' f o r Co(DH)2 (NCS)0H2 d is a p p e a r s upon r e a c t i o n . T h is le a d s t o th e p o s t u l a t i o n t h a t t h e i s o m e r i z a t i o n o f th io c y a n a te l i g a n d i n t h e com plex o c c u r s . Co(DH)2 (NCS)OH2 + SO” 2 * Co(DH)2 (NCS)S0^ 2 + H20 (35) Co(DH) (NCS)SO" 2------- > Co(DH) (SO )SCN" 2 (36) fa J V The u l t r a v i o l e t s p e c tru m s u p p o r ts th e above p o s tu l a t i o n . The a b s o r p t i o n o f Co(D H ^(N CS)0 H2 i n 0 .1 M _ 2 SOg 136 h o u rs a f t e r m ix in g i s th e same as t h a t o f Co (DH)2 (S0 3 ) 0 H2 i n 0 .1 M SO^2 . The r e a c t i o n o f Co(DH) 2 _ 2 (NCS)0 H2 i n 0 .1 M SO^ p ro b a b ly p ro c e e d s t h e s te p s ex p r e s s e d i n R e a c tio n s (37) and (3 8 ). Co(DH) (SO )SCN- 2 + H 0 -----> Co(DH) (SO )0H_ + SCn" (37) 2 3 2 2 3 2 Co(DH) (SO )0H" + SO- 2 -----> Co(DH) (SO ) ' 3 + H 0 (38) 2 3 2 3 2 3 2 2 — 9 ~ The e x i s t e n c e o f SO” s h i f t s th e R e a c tio n (3 7 ) to th e r i g h t s i d e and form s more s t a b l e Co(DH) (SO ) “ 3. 2 3 2 (B) A bsorb an ce 600 400 2500 2000 1000 800 1500 1200 1300 1100 900 700 500 0.1 F req u en cy (cm' (A) 0.2 0 .3 0 .4 0 .5 0.6 0 .7 1.0 F req u en cy (cm ) 400 600 800 2500 2000 1500 1200 1000 1300 1100 900 700 500 F ig . 11. I n f r a r e d S p e c tr a o f Na2 Co(DH)2 (S03 >(SCN) (A ), Co(DH)2 (NCS)OH2 ( B ) . 64 I t i s f e l t t h a t t h e b o n d in g o f SCN" i n Co(DH) 2 _ o (SOg)SCN i s th ro u g h th e s u l f u r atom b e c a u s e o f th e a v a i l a b i l i t y o f 7 C b o n d in g b etw een t h e c o b a l t and s u l f i t e g ro u p . The % b o n d in g i s form ed b etw een t h e d e l e c t r o n s o f t h e c o b a l t and an empty a n tib o n d in g 7[ o r b i t a l lo c a t e d on th e S atom o f th e s u l f i t e g ro u p . The a v a i l a b i l i t y o f th e c o b a l t d e l e c t r o n s f o r th e c o b a l t and t h i o c y a n a t e g ro u p w i l l b e re d u c e d by th e p a r t i c i p a t i o n i n X b a c k _ 2 b o n d in g w ith th e 7 U a c c e p t o r SO^ lig a n d . I t th u s c a u s e s th e c o v a le n t b o n d in g c h a r a c t e r betw een Co and SCN" to b e w eakened. On t h e o t h e r h a n d , i n Co(D H ^(N C S)0 H2 th e Co-NCS b o n d in g i s u n a f f e c t e d s in c e t h e r e a r e no e l e c t r o n 40 a c c e p to r s p r e s e n t . L ew is, Nyholm and S m ith s u g g e s te d t h a t i n th e NCS" io n th e lo n e p a i r s on th e S atom a r e more e a s i l y p o l a r i z e d th a n th o s e on th e N atom , and th e p erm an en t lo n e p a i r d i p o l e on t h e n i t r o g e n atom i s l a r g e r th a n t h a t on th e s u l f u r atom . The way i n w hich th e NCS" g ro u p i s b onded, i . e . , th ro u g h S o r N, w i l l be d e c id e d b y t h e r e l a t i v e bond e n e r g ie s o f a c o v a le n t m e t a l - s u l f u r bond and o f th e m ore i o n i c m e t a l - n i t r o g e n bond. I t i s o f i n t e r e s t t o know w h e th e r th e bond betw een c o b a l t and t h i o u r e a i s th ro u g h th e n i t r o g e n o r th e s u l f u r atom . Sw am inathan and I r v i n g p o in te d o u t t h a t i f th e L ew is, R .S. Nyholm and P.W. S m ith , J . Chem. S o c . , 4590 (1 9 6 1 ). 65 c o o r d i n a t i o n i s th ro u g h th e n i t r o g e n atom , i t may r e s u l t i n an i n c r e a s e o f t h e C-S s t r e t c h i n g fre q u e n c y w ith a d e c r e a s e o f t h e C-N s t r e t c h i n g f r e q u e n c y .^ * On th e o t h e r h an d , i f t h e c o o r d i n a t io n i s th ro u g h S atom , th e C-N s t r e t c h i n g f re q u e n c y i n c r e a s e s and t h e C-S s t r e t c h i n g d e c r e a s e s . T h e re w i l l b e no a p p r e c i a b l e ch an g e o f th e N-H s t r e t c h i n g . Sw am inathan and I r v i n g h av e a s s ig n e d t h e band a t 730 cm"* i n p u re t h i o u r e a to C-S s t r e t c h i n g . I n NaCo (DH) (SO ) T h io u re a (F ig . 12) t h i s band i s s p l i t and s h i f t e d to 710 cm"*. The o t h e r C-S s t r e t c h i n g band a t 1412 cm"* i n p u re t h i o u r e a i s s p l i t to 1420 and 1380 cm ^ on fo rm in g m e t a l - s u l f u r bond. A ll t h i s e v id e n c e i n d i c a t e s t h a t t h e bond b etw een c o b a l t and t h i o u r e a i s th ro u g h t h e s u l f u r atom . ^*K. Sw am inathan and H.M.H. I r v i n g , J . I n o r g . N u cl. Chem ., 26, 1291 (1 9 6 4 ). Absorbance A b so rb an ce (A) 0.5 _ 0. 7 _ 1 . 0 - 3400 3000 2500 2000 1300 (B) 900 1000 F req u en cy (cm- 1 ) 1100 700 500 600 400 1500 1200 800 F r equenc y (cm "L) 2500 2000 1500 13001200 1100 1000 900 800 700 600 500 400 F ig . 12. I n f r a r e d S p e c tr a o f NaCo(DH)2 (S0 3 >Tu (A ), Na.jCo(DH)2 (8 0 3 ) 2 (B). CHAPTER I I THE CONFIGURATIONS OF NaCo(DH>2 (SO )OH . 5 ^ 0 AND cis-N aC o(D H )2 (0H)2-5H20 I . I n t r o d u c t i o n C h a p te r I g iv e s th e k i n e t i c s o f t h e s u b s t i t u t i o n o f H2 0 i n NaCo(DH)2 (S0^)0H 2 .5H2 0 , and shows t h a t a l l r e a c t i o n s s tu d i e d p ro c e e d r a p i d l y . The f a s t s u b s t i t u t i o n r a t e o f H2 0 c a n b e e x p la in e d b y c o n s i d e r a t i o n o f th e t r a n s e f f e c t o f SO” ^ i n o c t a h e d r a l co m p lex e s, assum ing t h a t th e two d im e th y lg ly o x im e m o le c u le s l i e i n one p la n e . The p r e s e n c e o f SO“ ^ c o u ld c a u s e th e r a p i d s u b s t i t u t i o n . The c o n f i g u r a t i o n s o f c o b a l t ( I I I ) - b i s d i m e t h y l g l y o - xim e com plexes h av e b een a rg u e d s in c e 1931, when T h ilo 42 and H e ilb o m f i r s t p o s t u l a t e d t h a t t h e two d io x im e g ro u p s w ere i n one p la n e . I n 1936 T su c h id a and N a k a h a r a ^ s t a t e d t h a t th e y had r e s o lv e d t h e o p t i c a l iso m e rs o f Co(DH) (NH.)C1 by d i f f e r e n t i a l a b s o r p tio n on o p t i c a l l y 2 4 a c t i v e q u a r t z . Such a r e s u l t le a d s n a t u r a l l y to th e c i s form o f t h e com plex. N ak ah ara, F u j i t a and T su c h id a o b s e rv e d an a b s o rp - ^ E . T h ilo and H. H e ilb o r n , B e r. , 6 4 , 1441 (1 9 3 1 ). ^ R . T sc h u d a , M. K o b a y a sh i, and A. N akam ura, B u l l . Chem. Soc. J a p a n , 1 1 , 238 (1 9 3 6 ). 67 t i o n band a t 1725 cm ^ i n H C o ^ H ^ C ^ w hich th e y s u g g e s te d was a t t r i b u t a b l e t o t h e OH" s t r e t c h i n g fre q u e n c y u n d e r t h e f o rm a tio n o f an i n t r a m o l e c u l a r 0 --H — 0 h y d ro g en bond i n th e d im e th y lg ly o x im e r i n g . ^ They a l s o found t h a t o t h e r d im e th y lg ly o x im e com plexes e x h i b i t an a b s o rp t i o n i n th e ra n g e o f 1686-1770 cm"^. They c o n c lu d e d t h a t t h e p r e s e n c e o f t h e h y d ro g en bonds i s a p r o o f o f th e t r a n s c h a r a c t e r o f th e m o le c u le . G i l l a r d and W i l k i n s o n ^ s t u d i e d s e v e r a l c o b a l t ( I I I ) - b is d im e th y lg ly o x im e com plexes h av e a t r a n s c o n f i g u r a t i o n from th e a p p e a ra n c e o f a b s o r p t i o n bands a t 1700 cm ^ i n t h e IR s p e c t r a . They a l s o found an a b s o r p t i o n a t 1000 c / s low f i e l d com pared w ith t e t r a m e t h y l s i l a n e , TMS, as t h e s ta n d a r d i n th e NMR m easu rem en ts. A blov and h i s co w o rk ers i n 1963 r e p o r t e d t h a t i f c o ld c o n c e n tr a te d i s added to Co(DH)2 (0 1 ) 0 ^ , Co(DH)2 ( 0 H)0 H2 i s o b ta in e d . However, i f Co(DH)2 ( 0 1 ) 0 ^ i s h e a te d w ith 507o K0H, a d ih y d ro x y l compound, KCo(DH) 2 (O H ^ , i s o b ta in e d . The a b s o r p t i o n s p e c t r a o f t h e s e two p r o d u c ts i n s u f f i c i e n t a c i d medium t o c o n v e r t t h e s e two compounds i n t o d ia q u o com pounds, d i f f e r e d from one a n o t h e r . Two d i f f e r e n t s p e c t r a w ere o b ta in e d f o r t h e s e ^ A . N a k ah a ra , J . F u j i t a , and R. T sch u d a, B u l l . Chem. S o c . J a p a n , 29_, 296 (1 9 5 6 ). ^-*R.D. W illa r d and G. W ilk in s o n , J . Chem. Soc. , 6041 (1 9 6 3 ). 69 two compounds i n a l k a l i n e medium. From t h i s th e y assum ed t h e e x i s t e n c e o f two form s o f th e b is d im e th y lg ly o x im a to - d i a q u o c o b a l t ( I I I ) c a t i o n , and a l s o two form s o f th e d i - h y d r o x y l b i s d i m e t h y l g l y o x i m a t o c o b a l t ( I I I ) . They p o s t u l a t e d t h a t t h e compound o b ta in e d from 507, KOH i s cis-K Co(D H )^ ( oh) 2 . I n t h i s c h a p te r t h e c o n f i g u r a t i o n o f c o b a l t ( I I I ) - b is d im e th y lg ly o x im e com plexes w i l l b e d is c u s s e d i n t h r e e r e s p e c t s . F i r s t o f a l l , i t i s o f i n t e r e s t t o know w h e th e r o r n o t t h e two d im e th y lg ly o x im e m o le c u le s a r e c o p la n a r i n NaCo(DH)2 (SO^)OH2 . S e c o n d ly , i f t h e two d im e th y lg ly o x im e m o le c u le s a r e c o p l a n a r , w hat i s t h e b o n d in g ty p e b etw een s u l f i t e and c o b a lt? T h i r d l y , A b lo v 's work i n p r e p a r in g cis-N aC o(D H )2 (OH) 2 was r e p e a t e d , and NMR and IR m ethods w ere u s e d t o s tu d y th e c o n f i g u r a t i o n o f t h i s compound. I I . R e s u lts and D is c u s s io n s 1. The C o n f ig u r a tio n o f NaCo(DH) (SO )0H j ....- z The i n f r a r e d s p e c t r a o f NaCo(DH)2 (S O ^ O I^ and i t s d e u t e r a t e d d e r i v a t i v e w ere ta k e n and a r e shown i n F ig u r e 13. I n o r d e r t o c l a r i f y th e i n t r a m o l e c u l a r h y d ro g en b o n d in g i n c o b a l t ( I I I ) - b i s d i m e t h y l g l y o x i m e com p l e x e s , Co(DH)2 (N02 )0H2 , Na3 Co(DH)2 (S03 ) 2 (F ig . 12) and t r a n s Co(DH)2 (0H2 ) 2 C1 w ere p r e p a r e d . T a b le 15 g iv e s th e 0 — H — 0 s t r e t c h i n g and b e n d in g f r e q u e n c i e s . The a s sig n m e n t f o r t h e h y d ro g en b o n d in g i n IR 46 s p e c t r a i s v e r y am biguous. N ak ah ara c o n c lu d e d t h a t a l l th e b is d im e th y lg ly o x im a to c o b a l t ( I I I ) com plexes show s i m i l a r 0 - - H s t r e t c h i n g bands i n t h e r e g io n o f 1725 cm*^ u n d e r t h e f o rm a tio n o f i n t r a m o l e c u l a r h y d ro g en b o n d s. 47 S i m i l a r l y G i l l a r d and W ilk in so n r e p o r t e d t h a t th e a b s o r p t i o n band o c c u r in g a t 1750 cm"^ i s a t t r i b u t e d to th e h y d ro g e n b o n d in g i n t h e c o b a lt- b is d im e th y lg ly o x im e com p l e x e s . However, th e y d id n o t m e n tio n t h e ty p e o f v i b r a t i o n s f o r t h e band i n th e 1700 cm"'*’ r e g io n . 48 P im e n ta l and M cC le lla n g av e th e r e g io n f o r th e 46 N a k a h a ra , F u j i t a , and T sch u d a, B u ll. Chem. S o c . J a p a n , 2 9 , 296 (1 9 5 6 ). 47 W illa r d and W ilk in s o n , op. c i t . , 6041. ^ G . C . P im e n ta l and A.L. M c C le lla n , "H ydrogen Bond", W.H. Freem an and C o ., San F r a n c i s c o , 1960, p . 6 8 . 70 71 T a b le 15. The 0 - - H — 0 s t r e t c h i n g and b e n d in g f r e q u e n c ie s i n c o b a l t ( I I I ) - b i s d i m e t h y l g l y o x i m e com plexes ( i n cm- ^ u n i t ) . Compounds 0 --H — 0 s t r e t c h i n g 0 --H — 0 b e n d in g NaCo(DH)2 (S03 )0H2-5H20 NaCo(DD)2 (S03 )0D2 • 5D20 Na3Co(DH)2 (S03) 2 .12H20 c o ( d h ) 2 (no2 )o h 2 . h 2o c o ( d h ) 2 ( n c s ) o h 2 NaCo(DH)2 (S03 ) SCN Co(DH)2 (S03 )SCN2 H^2H20 tra n s-C o (D H )2 (0 H2 ) 2 C1 2350 s h a rp 1630 s h o u ld e r 2320 s h a rp 2350 s h a rp 2375 b ro ad 2350 b ro ad 2360 b ro a d 2370 b ro a d 1770 weak 1166 weak 1670 s h o u ld e r 1760 b ro a d 1690 b ro a d 1750 b ro a d 1780 b ro a d 1700 b ro a d Absorbance A bsorbance (B) 0 .4 400 600 800 1200 1000 2000 1500 2500 500 900 700 1300 ' 1100 F re q u en c y (cm "!) (A) 0 .4 1500 1200 1100 1000 900 800 700 600 500 400 2500 2000 F re q u e n cy (cnT^) F ig . 13. I n f r a r e d S p e c tr a o f N aC o (D H )^(S O ^O ^ (A ), NaCo(DD)2 (SO^)OD2 (B) 73 v i b r a t i o n a l o f h y d ro g en bond. The 0 --H — 0 s t r e t c h i n g i s i n t h e r e g io n 3500-2500 cm’ ^ , and th e b e n d in g ( in p la n e ) i s 1 7 0 0 -1000cm"1 . 49 B lin c and H adzi i n 1958 p o in te d o u t t h a t th e band n e a r 2340 cm" 1 b e lo n g s t o t h e 0 --H — 0 s t r e t c h i n g v i b r a t i o n . They i n d i c a t e d t h a t t h e w eakness o f t h i s band le d to t h e f a i l u r e o f o t h e r i n v e s t i g a t o r s to n o t i c e them . They b e l i e v e d t h a t t h e p r e v io u s a ssig n m e n t o f th e band n e a r 1 700"1 t o th e 0 --H s t r e t c h i n g was n o t r e l i a b l e . T h is p ro b le m was f u r t h e r s tu d i e d by C aton and Banks."*® They showed t h a t t h e 2300 cm" 1 bands f o r NiCDH)^ d i s a p p e a re d when Ni(DH) i s d e u t e r a t e d a s N i(D H )0-d . How- 2 2 6 e v e r , a new band a p p e a rs a t 1530 cm"1 , w hich i s b e l i e v e d t o b e t h e 0 --D — 0 s t r e t c h i n g . A s i m i l a r r e s u l t was found i n t h e IR m easurem ent o f NaCo(DH)2 ( 8 0 2 ) 0 ^ . From T a b le 15, i t i s se e n t h a t t h e 0 --H — 0 s t r e t c h i n g o c c u rs a t 2350 cm" 1 and t h a t o f b e n d in g a t 1750 cm- 1 . A f t e r two r e c r y s t a l l i z a t i o n s from D2 O t h e b an d s a t 2350 and 1770 cm” 1 d is a p p e a r . I t i s e x p e c te d from th e p r o d u c t r u l e t h a t 0 --H — 0 s t r e t c h i n g a t 2350 cm" 1 w i l l b e s h i f t e d to 1650 cm" 1 a f t e r th e r e p la c e m e n t o f H by D. F ig . 13 shows th e s p e c t r a o f th e d e u t e r a t e d com plex. A s h o u ld e r i s o b s e rv e d a t 1630 cm" 1 ^ R . B l i n c and D. H a d z i, J . Chem. S o c ., 4536 (1 9 5 8 ). U J .E . C ato n , F r . , and C.V. B anks, I n o r g . Chem., 6 , 1670 (1 9 6 7 ). 74 w h ich i s b e l i e v e d t o b e t h e 0 --D — 0 s t r e t c h i n g mode. The c o n f i g u r a t i o n o f NaCoCDH^CSO^OH,, was f u r t h e r s t u d i e d by NMR. The c h e m ic a l s h i f t o f th e i n t r a m o l e c u l a r h y d ro g en b o n d in g i n NaCoCDH)^(SO^OH^ i s a t t =- 7 .4 ppm i n d im e th y l s u l f o x i d e medium. T h is i s i n ag re e m e n t w ith G i l l a r d and W ilk in s o n 's r e p o r t . The i n t e n s i t y o f th e 0 --H — 0 b o n d in g i n NaCoCDH^CSO^Ol^ i s v e r y weak. T h is i s due i n p a r t t o th e low s o l u b i l i t y i n d im e th y l s u lf o x i d e , and p a r t l y b e c a u s e o f t h e e x i s t e n c e o f c o o r d in a te d H^O i n t h e compound w hich r a p i d l y ex ch an g es i t s p r o to n s w ith t h e h y d ro g en atom i n t h e i n t r a m o l e c u l a r h y d ro g en bond in DH m aking i t d i f f i c u l t t o o b t a i n a c c u r a t e m e asu rem en ts. The m e th y l re s o n a n c e was s t u d i e d i n 1^0 and D^O. O nly one l i n e w ith th e c h e m ic a l s h i f t a t t = 7 .7 2 ppm was o b s e rv e d , i n d i c a t i n g t h a t CoCDH)^(S0^)0H“ h a s th e t r a n s c o n f i g u r a t i o n . I f i t w ere t h e c i s c o n f i g u r a t i o n t h r e e l i n e s w ith t h e r e l a t i v e i n t e n s i t i e s 1 : 1 : 2 a r e ex p e c te d to b e o b s e rv e d . From t h e IR and NMR s t u d i e s NaCo(DH) (SO )0H was Li O Lt f o rm u la te d as h a v in g a t r a n s c o n f i g u r a t i o n . 2. The L in k ag e b etw een S u l f i t e and C o b a lt I t i s o f i n t e r e s t t o know th e m anner o f lin k a g e b etw een c o b a l t and s u l f i t e . Sidgwick^® h a s p o in te d o u t t h a t t h e r e a r e f o u r p o s s i b l e s t r u c t u r e s f o r m e ta l s u l f i t e c o m p le x e s . As i t h a s b e e n shown t h a t th e s u l f i t e and w a te r g ro u p s i n NaCo(DH)^(SO^)OH^ a r e t r a n s to e ach o t h e r , th e p o s s i b i l i t y o f fo rm in g a b i d e n t a t e com plex ( s t r u c t u r e s I I I and IV) i n t h i s compound i s e x c lu d e d . F o r a u n i - d e n t a t e two p o s s i b l e s t r u c t u r e s e x i s t , n am ely , c o b a l t - s u l f u r b o n d in g ( s t r u c t u r e I ) , o r c o b a lt- o x y g e n bond in g ( s t r u c t u r e I I ) . The c r i t e r i a f o r d e te r m in in g t h e b o n d in g ty p e a r e b a s e d on th e num ber o f a b s o r p tio n bands and a l s o th e f re q u e n c y s h i f t on fo rm in g th e com plex as com pared w ith t h e f r e e io n . The sym m etry p o i n t g ro u p o f t h e s u l f u r b o n d in g s t r u c t u r e i s C . I n t h i s c o n f i g u r a t i o n t h e r e a r e 3N-6=9 3v v i b r a t i o n a l m odes. T hese n in e v i b r a t i o n s can b e s u b d i v id e d i n t o 3A^ + 3E, w here E i s d o u b ly d e g e n e r a te . From t h e s e l e c t i o n r u l e s , b o th A^ and E a r e Raman and IR a c t i v e . T h e r e f o r e i t i s e x p e c te d t h a t s i x b an d s w i l l b e o b s e rv e d i n th e i n f r a r e d r e g io n . Two o f them a r e th e 76 S -0 s t r e t c h i n g , n am ely , vs (S -0 ) and v __( S - 0 ) ; two b e n d in g ® c l o S s (0 -S - 0 ) and £a s ( 0 - S - 0 ) ; one s t r e t c h i n g Co-S; and one S0 ^ ro c k in g . C o o r d in a tio n o f a c o b a l t atom to one oxygen i n O SOT lo w e rs t h e symm etry from C t o C . As a r e s u l t , 3 3v s t h e d e g e n e r a te v i b r a t i o n s s p l i t i n t o two b a n d s , 6 A1 + 3A” . From t h e s e l e c t i o n r u l e s b o th A' and A" a r e Raman and IR a c t i v e . Thus n in e v i b r a t i o n s a r e e x p e c te d to b e o b s e rv e d . T h re e b an d s w i l l b e o b s e rv e d i n th e s t r e t c h i n g r e g io n , c o r re s p o n d in g t o one v (S -0 ) and two v ( S - 0 ) , « S S w hich a r i s e from t h e s p l i t t i n g o f v (S -0 ) i n t h e C. a s 3v c o n f i g u r a t i o n . M oreover S ^ (O -S -O ), t h e E s p e c ie s i n C ^ j s h o u ld b e s p l i t i n t o two a b s o r p t i o n bands A' and A". The f re q u e n c y s h i f t s i n t h e two ty p e s o f b o n d in g a r e d i f f e r e n t . C o tto n and F r a n c i s " ^ i n th e s tu d y o f IR s p e c t r a o f m e t a l - d i m e t h y l s u l f o x i d e (DMSO) c o n c lu d e d t h a t upon c o o r d i n a t i o n o f DMSO to a m e ta l th ro u g h s u l f u r atom , t h e s t r e t c h i n g fre q u e n c y o f S -0 w i l l become l a r g e r . How e v e r , t h e fre q u e n c y s h i f t s to a lo w er v a lu e i f c o o r d in a t i o n i s th ro u g h t h e oxygen atom . B abaeva, K h a rito n o v , 52 and Novozhenyuk e x p la in e d t h e fre q u e n c y s h i f t i n Ir-S O ^ ■^F.A. C o tto n and R. F r a n c i s , J . Am. Chem. S o c ., 8 2 , 2986 (1 9 6 0 ). 52 A.V. B abaeva, Yu. Ya. K h a rito n o v , and Z.M. N ovozhenyuk, R uss. J . In o rg . Chem. , 6 , 1159 (1 9 6 1 ). 77 c o m p lex es. The c o o r d i n a t io n o f s u l f i t e t o I r th ro u g h t h e s u l f u r atom s h i f t s t h e e l c t r o n s from th e oxygen atom i n t o t h e S -0 i n te r a to m ic s p a c e . T h is r e s u l t s in th e s t a b i l i z a t i o n o f th e S -0 bond and s h i f t s th e S -0 a b s o r p t i o n to a h i g h e r fre q u e n c y . The oxygen bond in g com plexes w ere s tu d ie d by Naka- co C / moto i n Co-ONO1 and B r i n t z i n g e r and H e s te r in M -O N O ^ j w here O' r e p r e s e n t s th e end oxygen atom , and 0 t h e c o o r d in a te d oxygen atom . They b e lie v e d t h a t th e v i b r a t i o n f re q u e n c y o f XO (X=S, N ), w here 0 c o o r d i n a t e s to m e ta l, s h o u ld become s m a lle r th a n t h a t i n th e f r e e io n ; on th e o t h e r h a n d , th e fre q u e n c y o f X -0 ' s h o u ld become h ig h e r th a n t h a t o f t h e f r e e io n . The IR s p e c t r a o f s e v e ra l s u l f i t o com plexes w ere ta k e n and l i s t e d in T a b le 16. The s u l f i t o g ro u p s in t h e s e com plexes a r e fo rm u l a t e d as s u l f u r b o n d in g s t r u c t u r e s f o r th e f o llo w in g two r e a s o n s . F i r s t o f a l l , o n ly two bands w ere o b se rv e d i n t h e r e g io n o f 400-700 cm’ \ c o r re s p o n d in g t o th e O-S-O b e n d in g . However, i f t h e bond in g i s th ro u g h an oxygen s ^ ~\J. F u j i t a , A.E. M a r t e l l , and K. Nakamoto, J . Chem. P h y s . , 3 6 , 339 (1 9 6 2 ). "^H. B r i n t z i n g e r and R. E. H e s te r , In o rg . Chem., 5 , 980 (1 9 6 6 ). “ ’-’j . C . Evans and J . J . B e r s t e i n , Can. J . C hem ., 3 3 , 1270 (1 9 5 5 ). (See T a b le 1 6 , p ag e 78") 78 T a b le 16. V i b r a t i o n a l F re q u e n c ie s o f S u l f i t o b i s d i m e th y - lg ly o x im a to c o b a lt Complexes ( in cm" ^) Compounds Na2S0355 NaCo(DH)2 (S03 )0H2 NaCo(DD)2 (S03 )0D2 Na2Co(Dl02(S03 )SCN Na3Co(DH)2 (S03) 2 NaCo(DH) (S03 ) t h i o u r e a 1010 633 1 1 2 9 (sh ) 6 3 4 (s ) 1 1 2 9 (sh ) 6 3 4 (s ) 11 4 2 (w) 6 3 9 (s ) 1126(w) 6 3 5 (s ) 1 1 2 0 (w) 6 2 1 (s ) 947 1 0 8 5 (s h ) 1 0 8 5 (sh ) 1 0 8 2 (s h ) 1 0 6 6 (sh ) 1 0 8 6 (sh ) 494 570(w) 570(w) 574(w) 575(w) 572(w) 79 atom , t h r e e bands a r e e x p e c te d t o be o b s e rv e d . S e c o n d ly , t h e r e i s no S -0 s t r e t c h i n g band w hich i s below 950 cm"^. T h is im p lie s t h a t t h e s u l f i t o g ro u p i n t h e s e com plexes a r e lin k e d to c o b a l t th ro u g h t h e s u l f u r atom . As m e n tio n ed a l r e a d y , i f t h e c o o r d i n a t io n i s th ro u g h oxygen atom , th e S -0 s t r e t c h i n g f re q u e n c y , w here 0 i s c o o r d in a te d to th e m e ta l, s h o u ld b e s m a lle r th a n t h a t o f f r e e s u l f i t e . 3. NMR and IR s t u d i e s o f cis-N aC o (D H )„(0 H )„• 5H„0 ----- A b lo v ’s p r o c e d u re f o r t h e p r e p a r a t i o n o f cis-N aC o (DH)2 (OH) 2 i s in c lu d e d i n t h e e x p e rim e n ta l s e c t i o n . The m o le c u la r w e ig h t was found t o be 4 3 0 -3 0 i n th e c o n c e n t r a t i o n ra n g e o f t h e com plex 0 .0 0 7 2 - 0 .0 3 6 M, u s in g a v a p o r p r e s s u r e o sm o m eter,m odel 301A, M echrolab I n c . , M ountain View, C a l i f o r n i a . The r e a d in g o f R from th e o so m e te r was c a l i b r a t e d by u s in g NaCl s o l u t i o n a s a s t a n d a rd . F ig . 14 g iv e s t h e c a l i b r a t i o n c u rv e . The e q u i v a le n t c o n d u c ta n c e was m easu red by a Beck man Type RC c o n d u c t i v i t y b r i d g e . The c e l l c o n s ta n t i s 0 .2 2 6 cm- '* -. The c o n d u c ta n c e v a lu e s w ere p l o t t e d a g a i n s t th e s q u a re r o o t o f c o n c e n t r a t i o n (F ig . 1 5 ). At i n f i n i t e d i l u t i o n ( */c = 0 ) , th e e x t r a p o l a t e d v a lu e o f e q u i v a le n t c o n d u c ta n c e i s 1 5 6 .5 ohm"'*', i n d i c a t i n g t h e compound i s an 1 : 1 e l e c t r o l y t e . The UV and v i s i b l e a b s o r p t i o n s p e c t r a a r e p r e s e n te d i n F ig . 16, and th e y a r e i d e n t i c a l to th o s e r e p o r t e d by 0 .0 2 0 .0 4 0 .0 6 0 .0 8 0 .1 0 (N a C l), M. F ig . 14. C a l i b r a t i o n C urve o f Osmometer N5 o U> o -p' o < c d t - s cn 3 cn O] X K * 00 C n W ► Q 3 H - < 0) i - 1 C D 3 rt- n o 3 C l * 3 o rt 3 3 O f l> O i-h a 3 o o a x to O E d K 3 E q u iv a le n t C o n d u c tan c e, ohm" 1 C n o O' o o o o o -p - o o co o 00 o Molar Absorbancy In d ex 2 x 1 0 1 x 1 0 5 x 1 0 2 x 1 0 1 x 1 0 5 x 1 0 2 x 1 0 1 x 1 0 5 0 200 4 0 0 6 0 0 3 0 0 5 0 0 W avelength F ig . 16. E x t i n c t i o n C o e f f i c i e n t s o f NaCoCDH)^ (OH) • 5H 0 2 2 83 A blov. ^ A pH t i t r a t i o n was c a r r i e d o u t. The pK and pK 1 + 2 w ere o b ta in e d from t h e l i n e a r p l o t o f lo g [ HA] / [H A ] and 2 lo g [A'l /[HAl v e r s u s pH, and w ere found t o b e 3 .9 and 8 . 6 r e s p e c t i v e l y , w here [A- ] r e p r e s e n t s th e c o n c e n t r a t i o n o f Co(DH) (OH)", [HAl , Co(DH) (OH)OH ; and[H A+ ] , Co(DH) 2 2 2 2 2 2 ^**2^2° However, th e s lo p e o f th e p l o t was 0 .7 3 r a t h e r th a n th e t h e o r e t i c a l v a lu e o f 1 . 0 . The p u r i t y o f c is-N a C o (D H ^ (OH^* 5 ^ 0 was ch eck by u s in g a c a t i o n i c exchange colum n, Dowex 50W-X8, 200-400 m esh. A s o l u t i o n o f th e compound a t pH 3 was e l u t e d from t h e colum n w ith 1 M NaClO^, a l s o a t pH 3. In a d d i t i o n to t h e m ain b a n d , w hich g iv e s t h e t h r e e NM R l i n e s i n th e i n t e n s i t y r a t i o o f 1 : 1 : 2 , t h e r e i s a s m a ll b a n d , w hich i s h e ld more t i g h t l y on th e colum n, i n d i c a t i n g a s m a ll amount o f im p u r ity . The e n v iro n m en t o f t h e m e th y l g ro u p s was s tu d ie d by NMR. The NM R s p e c t r a w ere ta k e n i n ^ 0 , D^O, m e th a n o l- d ^ , and d im e th y l s u lf o x i d e - d ^ . I n ^ 0 and t h r e e l i n e s w ere o b s e rv e d w ith t h e r e l a t i v e i n t e n s i t i e s 1 : 1 : 2 , w here 1 r e p r e s e n t s t h r e e p ro to n s c a l i b r a t e d w ith an i n t e r n a l r e f e r e n c e o f (CH^)^NClo The t h r e e l i n e p a t t e r n does n o t change i n a c i d i c o r b a s ic s o l u t i o n ; how ever, -^A .V . A blov, M.P. F i l i p p o v , and N.M. S am u s', D okl. Akad. Nauk USSR 133, 575 (1 9 6 0 ). i n s tr o n g a c i d i c s o l u t i o n a p r e c i p i t a t e form ed c a u s in g t h e i n t e n s i t y t o d e c r e a s e . I n m e t h a n o l - d ,, t h e h ig h 4 i n t e n s i t y l i n e s p l i t s i n t o two l i n e s , w hich im p lie s t h a t a l l f o u r g ro u p s a r e in d i f f e r e n t e n v iro n m e n ts. An e x p la n a tio n f o r th e t h r e e l i n e NMR sp e c tru m c an b e made by assum ing t h a t th e two h y d ro x y l g ro u p s i n th e c i s compound can form an u n sy m m e tric a l h y d ro g en b o n d in g r in g w ith s o lv e n t H^O o r D^O. I n o r d e r t o c o n firm t h a t t h e compound h a s a c i s c o n f i g u r a t i o n , a tte m p ts to p r e p a r e cis-CoCD H ^C^O ” , c i s - C o ^ H ^ e n * , and cis-C o (D H ^ (C N ) w ere made. I t i s e x p e c te d t h a t i f t h e s e compounds e x i s t , two l i n e s o f e q u a l i n t e n s i t y w i l l b e o b s e rv e d . However, t h e NM R s p e c t r a o f t h e aqueous s o l u t i o n s o f t h e s e com pounds s t i l l show t h r e e l i n e s as does th e cis-C o(D H )^ (OH)” , i n d i c a t i n g t h a t e i t h e r t h e r e i s no r e a c t i o n o r t h e p ro d u c t i s n o t in c i s c o n f i g u r a t i o n . The a s su m p tio n o f t h e f o rm a tio n o f u n sy m m e tric a l h y d ro g en b o n d in g t o s o l v e n t w a te r le a d s t o two d i f f i c u l t i e s . 1. The NM R s p e c t rum i s n o t pH d e p e n d e n t i n t h e pH r e g io n w here th e com p le x i s b e in g p r o to n a te d . 2. Hydrogen b o n d in g to s o lv e n t s h o u ld h av e a r a p i d exchange r a t e . A n o th e r a l t e r n a t i v e e x p la n a tio n i s t h a t t h e com pound s t i l l h a s a t r a n s c o n f i g u r a t i o n b u t one o f th e d im e th y lg ly o x im e m o le c u le s c o o r d in a te s t o c o b a l t th ro u g h t h e oxygen atom to form a six-m em bered r i n g . I n t h i s c a s e i t i s e x p e c te d t h a t th e f o u r m e th y l g ro u p s w i l l 85 b e d i f f e r e n t from one a n o th e r . However, two o f them ( t r a n s to each o t h e r ) a r e v e r y s i m i l a r , so t h r e e l i n e s w ould b e o b s e rv e d , from t h e i n f r a r e d sp e c tru m f o u r f e a t u r e s w ould b e e x p e c te d t o b e o b s e rv e d . 1. The i n t r a m o le c u la r h y d ro g e n b o n d in g a t 2350 cm"^ s h o u ld a p p e a r. 2. The C=N s t r e t c h i n g s h o u ld b e s p l i t i n t o two bands f o r d i f f e r e n t ty p e s o f b o n d in g . The c o o r d i n a t io n th ro u g h oxygen atom w ould c a u s e th e s h i f t o f e l e c t r o n d e n s i t y t o o xygen, and w eaken t h e s t r e t c h i n g o f C=N. 3. The s t r e t c h i n g o f N-0 s h o u ld become s t r o n g e r i n oxygen b o n d in g s t r u c t u r e s . 4 . Two ty p e s o f m e ta l lig a n d s s t r e t c h i n g a r e e x p e c te d to b e o b s e rv e d , n am ely , C o-0, and Co-N. The f o llo w in g t a b l e shows t h e IR bands o f c i s - NaCo(DH)^(OH)^ (F ig . 17) com pared to tran s-C o (D H )^(0 H ^)^C 1 . 86 d e u t e r a t e d T ran s-C o Co(DH)_ cis-N aC o cis-N aCo(D H ) (DH)2 (OH2 ) 2 3 (DH)2 (OH) 2 (OH) 2 2 Cl C o -lig a n d 510 500 4 8 5 , ^ , 5 3 0 4 8 5 ,5 0 5 ,5 3 0 N -0 s t r e t c h i n g 1030,1080 s h a rp 1 2 2 0 1060 1230 1085 b ro a d 1230, 1085 b ro a d C=N s t r e t c h i n g 1580 1570 1585,1550 1580,1550 O-H-O 2380,1790 weak I t seems p o s s i b l e to e x p l a i n a l l th e e x p e rim e n ta l f a c t s w i t h th e t r a n s c o n f i g u r a t i o n i n w hich one oxygen atom c o o r d in a te s to c o b a l t . However, th e f i n a l c o n c lu s io n s t i l l rem ain s u n s o lv e d u n t i l X -ra y d i f f r a c t i o n s t u d i e s o f t h i s compound c a n b e made. .0 .1 .2 .3 0 .4 0 .5 0.6 0 .7 .0 400 600 800 2500 2000 1500 1200 1000 1100 900 700 500 F re q u e n c y (cm- l ) F ig . 17. I n f r a r e d S p ectru m o f NaCo(DH)^ (OH)^ oo "v j APPENDIX I S e v e r a l p o i n t s w i l l be m en tio n ed f o r o p e r a tin g th e s to p p e d - f lo w a p p a r a tu s . 1. The s o l u t i o n s to b e m easu red m ust b e f r e e o f any s u s p e n s io n w hich may c a u s e d r i f t o f t h e t r a c e . S o l i d s , d u s t , o r b ro k e n g l a s s f l a k e s a r e a b s o l u t e l y n o t a llo w e d i n t o t h e s to p p e d -flo w a p p a r a t u s . T hese s m a ll p a r t i c l e s may b lo c k th e i n l e t s o f th e m ix in g c h a n b e r o r s c r a t c h th e t e f l o n s to p c o c k s . 2. I t i s d e s i r a b l e t h a t th e s o l u t i o n s to b e m ixed h av e th e same i o n i c s t r e n g t h i n o r d e r t o re d u c e t h e i n t e r f e r e n c e from s c h l i e r e n and m in im ize any a d d i t i v e volum e ch an g e. The s to p p e d -flo w a p p a r a tu s can b e u se d f o r m e a su r in g slow r e a c t i o n s w ith th e h a l f l i f e a b o u t 30 seco n d s by s e t t i n g t h e tim e b a s e knob a t 5 s e c . / d i v i s i o n t o g e t h e r w ith t h e u n c a l i b r a t e d knob a t i t s l e f t ex tre m e . T h is tim e b a se i s m easu red t o b e 1 3 .6 s e c . / d . Thus i t i s p o s s i b l e to o v e r la p t h e s to p p e d -flo w m ethod w ith th e c l a s s i c a l m ethods. I n th e m easurem ents o f slow o r m o d e ra te r a t e r e a c t i o n s w ith h a l f l i f e o f 0 . 2 seco n d s o r g r e a t e r , le a k s a r e a s e r i o u s p ro b lem . They w i l l o c c u r a t th e s to p p in g s y r in g e and t h e d r i v i n g s y r i n g e s . I n o r d e r to e l i m i n a t e th e le a k s from th e s y r i n g e s , i t i s n e c e s s a r y t o u s e 88 89 s y r in g e s w ith 0 - r i n g s . F o r t h e s to p p in g s y r in g e A piezon g r e a s e ca n be sm eared b etw een th e p lu n g e r and th e o u t e r b a r r e l . I t i s im p o rta n t to n o te t h a t t h e A piezon g r e a s e c a n n o t be u s e d to o h e a v i l y o r t h e r e s i s t a n c e o f th e p lu n g e r w i l l be to o g r e a t and c a u s e a slow flow r a t e . One o f th e m ethods f o r re d u c in g th e le a k s i s by re d u c in g th e p r e s s u r e i n th e s y r i n g e sy stem . T h is can be done by u s in g a slow m otor sp eed and low c l u t c h v a lu e . I t i s found t h a t th e c l u t c h v a lu e a t 30 and m o to r sp eed a t 30 i s s a t i s f a c t o r y . The p r e s s u r e c a n a l s o b e re d u c e d by s w itc h in g o f f th e m otor and c l u t c h a f t e r t r i g g e r i n g o r by d i s c o n n e c tin g t h e s to p c o c k s b etw een t h e s to p p in g s y r in g e s and t h e d r iv e n s y r i n g e s . F ig . 18 g iv e s th e l i n e a r v e l o c i t y ( m e te r/s e c o n d ) a t d i f f e r e n t m otor sp eed s and c l u t c h v a lu e s f o r q u a r tz o b s e r v a t i o n tu b e w ith an i n s i d e d ia m e te r o f 0 .1 9 9 cm. F o r f a s t r e a c t i o n s w ith h a l f l i f e s o f l e s s th a n 0 . 1 s e c o n d , i t i s n e c e s s a r y t o c h e ck th e m ix in g r a t e o f th e a p p a r a tu s . The m ix in g r a t e was ch eck ed by u s in g th e 56 f o llo w in g r e a c t i o n a t 460 m/^ OH~ + H 0(]}N02 > “0 ^ 2 > n02 + H2 ° I t i s known t h a t t h i s r e a c t i o n i s c o m p le te i n l e s s th a n on m i l l i s e c o n d . In t h e s tu d y o f f a s t r e a c t i o n s s e v e r a l ■^J.Fo Below, J r . , R.E. C o n n ick , and C.P. C o p p el, J . Am. Chem. Soc. , 80, 2961 (1 9 5 8 ). 90 p o i n t s may a f f e c t th e o b s e rv e d r a t e c o n s t a n t s . 1. C lu tc h c u r r e n t and m o to r s p e e d . The d i s t a n c e betw een th e m ix in g cham ber and t h e o b s e r v a t i o n p o i n t i n th e l i g h t p a th i s a b o u t 0 .5 cm. The tim e n eed ed f o r th e r e a c t i o n m ix tu re t o r e a c h t h e o b s e r v a t i o n p o i n t from t h e m ix in g cham ber i s 2 .5 m sec, a t c l u t c h v a lu e o f 25 and a m o to r sp e e d o f 30. F o r f a s t r e a c t i o n i t i s n e c e s s a r y to s e t th e c l u t c h c u r r e n t and m o to r sp eed a t h ig h e r v a l u e s , e . g . , c l u t c h , 4 0 , m o to r s p e e d , 40. 2. The n o i s e o b s e rv e d i n th e o s c i l l o sc o p e comes from t h e p h o t o m u l t i p l i e r and i n c r e a s e s e x p o n e n t i a l l y w ith t h e b ia s v o l t a g e . T h is n o i s e ca n be re d u c e d by a f i l t e r c i r c u i t . F ig . 19 shows th e f i l t e r c i r c u i t and t h e t r i g g e r i n g c i r c u i t . T hese c i r c u i t s w ere em ployed f o r a l l s to p p e d -flo w m easu rem en ts. The tim e c o n s t a n t , w h ich i s t h e p ro d u c t o f th e c a p a c i t a n c e and t h e r e s i s t a n c e , d e te rm in e s th e r e s p o n s e tim e o f t h e c i r c u i t , and i s v e r y im p o rta n t i n t h e r a t e m easu rem en ts. F o r e f f i c i e n t f i l t e r i n g a l a r g e c a p a c ita n c e i s n e c e s s a r y . However, s i n c e th e node c i r c u i t o f t h e p h o t o m u l t i p l i e r h a s l a r g e im p ed an ce, t h e RC p r o d u c t becom es s i g n i f i c a n t i f h ig h c a p a c i t a n c e i s u s e d , w hich i n t u r n d e la y s th e re s p o n s e tim e and r e s u l t s i n t h e s lo w e r o b s e rv e d r a t e . I t i s q u i t e s a f e t o u s e t h e p o s i t i o n o f 11 f o r slow r e a c t i o n s o f th e o r d e r o f h a l f l i f e up to 0 . 2 s e c . F o r f a s t r e a c t i o n s w ith h a l f l i f e l e s s th a n 0 .1 s e c o n d , i t i s n e c e s s a r y to s e t a t p o s i t i o n 7 o r 8 . 91 I n o r d e r to i n c r e a s e th e r a t i o o f s i g n a l to n o i s e t h e h ig h v o l t a g e on t h e p h o t o m u l t i p l i e r s h o u ld b e k e p t a s low a s p o s s i b l e . T h is can b e o b ta in e d by u s in g a l i g h t s o u r c e o f h ig h i n t e n s i t y (d e u te riu m lam p) and f o c u s in g t h e l i g h t s o u r c e ( a d j u s t i n g th e r e f l e c t i n g m i r r o r ) and l i g h t p a th p o s i t i o n . The o r d i n a t e o f t h e t r a c e i n t h e o s c i l l o s c o p e r e p r e s e n t s th e t r a n s m i t t a n c e c h an g e. I f th e a b s o rb a n c e ch an g e i s s m a ll, th e n a b s o rb a n c e i s p r o p o r t i o n a l t o t h e t r a n s m i t t a n c e and t h e o r d i n a t e may b e t r e a t e d a s co n c e n t r a t i o n . L et Ap and A r e p r e s e n t t h e a b s o rb a n c e o f th e p r o d u c t and r e a c t a n t r e s p e c t i v e l y . The d i f f e r e n c e i s AA = A - A = lo g 1/T - lo g 1 /T , (39) p r p p w h ere T and T a r e t h e t r a n s m i t t a n c e o f p ro d u c t and p r r e a c t a n t r e s p e c t i v e l y . S in c e AT = Tr - T , (4 0 ) AA = lo g Tr /T p = log(Tp+AT) /T p = l o g ( l + A T / T p ) - 1 /2 .3 0 3 l n ( l + AT/Tp) = 1 /2 .3 0 3 AT/Tp . (4 1 ) T h e r e f o r e , A i s p r o p o r t i o n a l to th e t r a n s m i t t a n c e c h an g e o n ly when T i s s m a ll. Assume th e ch an g e i n t r a n s m i t t a n c e i s o n ly 37o, o r AT/Tp = 0 .0 3 , th e n &A = 1 A T (42) 2 .3 0 3 T = 0 .0 1 3 P The maximum c o n c e n t r a t i o n em ployed i n s to p p e d -flo w i s o b ta in e d from A A = ^pCpl - £t Cr l 92 I f t h e r e a c t i o n i n c o m p le te C = % C , A = (% 6 - 6 ) p r p r C 1 w here 1 i s th e l e n g t h o f l i g h t p a th f o r th e q u a r tz tu b e a p p ro x im a te 0 . 2 cm. The a p p r o p r i a t e c o n c e n t r a t i o n f o r th e s to p p e d -flo w m easurem ent ca n b e c a l c u l a t e d from th e n u m e ric a l v a lu e s o f th e a b s o rb a n c y i n d i c e s o f r e a c t a n t and p r o d u c t. Some a u th o r s r e p o r t e d ^ t h a t t h e ch an g e i n a b s o rb a n ce may b e a s l a r g e a s 0 .1 I n t h i s c a s e t h e t r a n s m i t ta n c e ch an g e w i l l be g r e a t e r th a n 37o. 5?d .W. C a r l y l e and J .H . E sp en so n , In o rg . Chem., 6 , 1370 (1 9 6 7 ). 4 3 L in e a r V e l o c i t y , m /se c . 2 1 0 20 30 40 50 60 70 M otor Speed F ig . 18. The P l o t o f L in e a r V e lo c ity o f Flow v e r s u s M otor Speed a t V a rio u s C lu tc h V a lu e s . C lu tch 45 (75 mA) 40 ( 6 8 mA) 35 (60 mA) 30 (50 mA) E M 1 6256 B Photom ultiplier 94 P/S Fluke 4 0 9 A *0.35 M *2 Rs; Re R ? . Re< R c Rio< R |(; R12: RI3< rI4< D , D 2 d 3 d 4 d 5 d 6 : d 7 d 8 d 9 Dio D | | D|2 :Di3 Anode 0-10 Microammeter ©Adjust ON/OFF -jCathode^-Q \0p 2N 336 Operate 534 DA Pre. Amp i ' u 1 .100 “ 6 Capacitance control > ■ I 2 5 10 15 22 33 4768100 uF > 1 1 1 1 1 1 1 1 1 1 1 l20V 0.1 M lO p F l ^ 0 .1 M Helipot 10 turns ON/OFF r- 225 V A-B Tetronix ( > a All resistances 0.5 Watt, 1% R, = 200 K, R 2 ~ R|4 = 100 K F ig . 19. The F i l t e r i n g C i r c u i t o f th e S to p p e d -flo w A p p a r a tu s . APPENDIX I I 1. C a l c u l a t i o n o f t h e E f f e c t i v e C o n c e n tr a tio n o f P y r id i n e . P y r id i n e i s a weak b a s e . The f o rm a tio n q u o t i e n t f o r t h e r e a c t i o n P y + H+ c— PyH+ is K - f P y H + ]_________________ ( 4 3 ) [Py] tn+] The t o t a l c o n c e n t r a t i o n o f p y r i d i n e , [Py] , i s th e sum o f t h e f r e e p y r i d i n e and p y r id in iu m io n . [Py] t = [Py] + [Pytf*| (44) S u b s t i t u t i n g E q u a tio n (44) i n t o (43) and r e a r r a n g in g , [Py] (45) [Py] - 1 + KtH*] The n u m e ric a l v a lu e o f K u s e d i n t h e c a l c u l a t i o n 5 58 was 1 .6 2 x 10 . The e f f e c t i v e c o n c e n t r a t i o n o f p y r id i n e was l i s t e d i n T a b le 11. 2. T h io u re a i s a weak b a s e i n aqu eo u s s o l u t i o n . The d i s s o c i a t i o n c o n s t a n t ^ Qf th e r e a c t i o n 1 2 , 878. 5 9 58 Frydm an, N i l s s e n , Rengems, and S i l l e n , op. c i t . B ruchlm an and V erh o ek , op. c i t . , 7 0 , 1401. 95 96 TuHOH Tuff1 - + OH" i s [TuHl [OHl K - 1 .1 x 10' 1 1 [TuHOH] I n 0 .1 M t h i o u r e a s o l u t i o n , t h e pH i s a b o u t 7 .9 , w here th e i n e r t s p e c ie s Co(DH)2 (S0 3 ) 0 H"^ i s i n c o n s i d e r a b le am ount. I t was n e c e s s a r y t o add 0 .2 5 ml o f 1 M HCIO^ i n o r d e r t o lo w e r th e pH. 3. The d i s s o c i a t i o n c o n sta n t^ ® o f a z o ic a c i d i s 2 .3 9 x 10- 5 . The h y d r o ly s i s c o n s ta n t o f a z id e i n t h e r e a c t i o n , N~ + H20 HN3 + OH" i s K = [HN ] [OH"] Q 3________ = 4 .0 2 x 10 iU tN'3] I n 0 .1 M o f Ng s o l u t i o n , t h e pH i s a b o u t 8 .2 . 0 .0 2 5 m M o f HC10. w ere added t o _ t h e 0.01,M o f N~ s o l u t i o n 4 3 and 1 .2 5 mM f o r 0 .5 M o f Nj i n o r d e r t o lo w er th e b a s i c i t y . fiO Burns and Chang, op. c i t . , 6 3 , 1314. BIBLIOGRAPHY Books A blov, A.V. , " P ro c e e d in g s 1 0 th I n t e r n a t i o n a l Complexes on C o o r d in a tio n C h e m is try ," 1967, p . 278. B a s o lo , F. and P e a r s o n , R .G ., "M echanism s o f I n o r g a n ic R e a c tio n s ," Jo h n W iley and S o n s, I n c . , New Y ork, N .Y ., 2nd E d ., 1967. Haim, A ., G r o s s , R . J . , and W ilm a rth , W .K ., "A dvances in C h e m istry S e r i e s , " No. 9 , A m erican C hem ical S o c ie ty W ash in g to n , D .C ., 1965, p . 31. K o l t h o f f , I.M . , and B e lc h e r, R . , " V o lu m e tric A n a ly s is ," V ol. I l l , I n t e r s c i e n c e P u b l i s h e r , I n c . , New Y ork, 1957, p. 312. K o l t h o f f , I.M . , and S t e n g e r , V.A. , " V o lu m e tric A n a ly s is ," V ol. I I , I n t e r s c i e n c e P u b l i s h e r , I n c . , New Y ork, 1957, p. 249. L a n g fo rd , C.H ., and G ray , H.B., " L ig a n d S u b s t i t u t i o n P ro c e s s e s , " W.A. B en jam in , New Y ork, 1966. P im e n ta l, G.C. , and M c C le lla n , A .L ., "H ydrogen Bond," W.H. Freem an and C o., San F r a n c i s c o , 1960, p. 6 8 . S id g w ick , N.V., "The C hem ical E lem ents and T h e ir Compounds' C la re n d o n P r e s s , O x fo rd , 1949, p. 910. W elc h e r, F .J. , "The A n a l y t i c a l U ses o f E th y le n e d ia m in e - t e t r a a c e t i c A c id ," Van N o s tra n d , New Y ork, 1957. P e r i o d i c a l s A blov, A.V., F i l i p p o v , M.P., and Sam us1, N.M., D o k l. Akad. Nauk USSR, 1 3 3 , 575 (1 9 6 0 ). A blov, A.V. , Sam us1 , N.M., R uss. J . I n o r g . Chem ., 4 410 (1 9 6 0 ). A blov, A.V., S a m u s', N.M., and B o lo g a, O.A., R u ss. J . I n o rg . Chem. , 8, 440 (1 9 6 3 ). 98 A blov, A.V., S a m u s', N.M., and Popov, M.S., D o k l. Akad. Nauk USSR, 1 0 6 , 665, (1 9 5 6 ). A blov, A.V. and S y r ts o v a , G . P . , R uss. J . In o rg . C hem ., 5, 588 (1 9 6 0 ). B abaeva, A.V. , K h a rito n o v , Yu. Y a ., and B a r a n o v s k ii, I . B . , R uss. J . I n o r g . Chem. , 7_y 643 (1 9 6 2 ). B abaeva, A.V., K h a rito n o v , Yu. Y a ., and N ovozhenyuk, Z.M., R uss. J . In o rg . Chem. , 6 , 1159 (1 9 6 1 ). B a i l a r , J . C . , and P e p p a rd , D . F . , J. Am. Chem S o c . , 62, 105 (1 9 4 0 ). B a llh a u s e n , C.J. and G ray , H.B., In o rg . Chem ., 2 , 426 (1 9 6 3 ). Below, J . F . J r . , C o n n ick , R .E ., and C o p p el, C . P . , J. Am. Chem. Soc. , 8 0 , 2961 (1 9 5 8 ). B jerru m , J . , Chem. Rev., 46, 381 (1 9 5 0 ). B lin c , R. , and H a d z i, D . , J . Chem. S o c ., 4536 (1 9 5 8 ). B r i n t z i n g e r , H . , and H e s t e r , R .E ., I n o r g . Chem., 5 , 980 (1 9 6 6 ). B ruchlm an, R.J. and V erh o ek , F .H ., J. Am. Chem. S o c . , 70, 1401 (1 9 4 8 ). B u rn s, E.A., and Chang, F .D . , J. Phys. Chem., 6 3 , 1314 (1 9 5 9 ). C a r l y l e , D.W. and E sp en so n , J . H . , In o rg . Chem ., 6 , 1370 (1 9 6 7 ). C ato n , J.E. J r . , and B anks, E.V. , In o rg . Chem ., 6 , 1670 (1 9 6 7 ). C h a m b e rla in , M.M. and B a i l a r , J.C. J r . , J. Am. Chem. S o c ., 81 , 6412 (1 9 5 9 ). Chen, H. Ho, T sa o , M.S., G a v er, R.W., T e w a ri, P .H ., and W ilm a rth , W.K. , In o rg . Chem. , 5_, 1913 (1 9 6 6 ). Chugaev, L .A ., Z hur. R uss. F iz-K him . O b s h c h ., 37, 610 (1 9 0 5 ). Chugaev, L .A ., B e r . , 4 1 , 2226 (1 9 0 8 ). 99 C o tto n , F .A ., and F r a n c i s , R . , J . Am. Chem. Soc., 82 2986 (1 9 6 0 ). D u lz , G . , and S u t i n , N . , I n o r g . Chem. , 2, 917 (1 9 6 3 ). E v a n s, J . C . , and B e r s t e i n , H . J . , Can. J . Chem ., 3 3 , 1270 (1 9 5 5 ). Frydm an, M ., N i l s s e n , G . , Rengems, T . , and S i l l e n , H.G., A cta Chemica S c a n d ., 1 2 , 878 (1 9 5 8 ). F u i i t a , J . , M a r t e l l , A .E ., and Nakamoto, K . , J . Chem. P h y s . , 3 6 , 339 (1 9 6 2 ). Haim A ., and W ilm a rth , W.K., I n o rg . C hem ., I , 573 (1 9 6 2 ). Haim A ., and W ilm a rth , W.K. , I n o rg . Chem. , 1_, 583 (1 9 6 2 ). H a lp e rn , J . , P a lm e r, R.A. and B la k le y , L .H ., J. Am. Chem. S o c . , 8 8 , 2877 (1 9 6 6 ). H auge, D.N. , and H a lp e rn , J . , In o rg . Chem. , 6, 2059 (1 9 6 7 ). L e w is, J . , Nyholm, R.S., and S m ith , P.W., J. Chem. Soc., 4590 (1 9 6 1 ). M i t c h e l l , P .C .H ., and W illia m s , R . J . P . , J. Chem. Soc., 1912 (1 9 6 0 ). N ak ah ara, A ., F u j i t a , J . , and T sch u d a, R . , B u ll. Chem. Soc. J a p a n , 29, 296 (1 9 5 6 ). N asan en , R. and M e r ila in e n P . , Suomen Kern., 33B, 149 (1 9 6 0 ). S a b a t i n , A ., and B e r t i n i , I . , In o rg . C hem ., 4 , 959 (1 9 6 5 ). S c h r a u z e r , G.N., and W in d g assen , R . J . , J. Am. Chem. Soc., 8 6 , 3738 (1 9 6 6 ). Sw am inathan, K . , and I r v i n g , H.M.H., J. I n o r g . N u cl. C hem ., 2 6 , 1291 (1 9 6 4 ). S y r ts o v a , G . P . , and K o r le ty a n u , L .N ., R uss. J . In o rg . C hem ., 11, 1233 (1 9 6 6 ). T e w a ri, P .H ., G av er, R.W., W ilco x , H.K., and W ilm arth , W.K., I n o r g . C hem ., 6 , 611 (1 9 6 7 ). Thilo, E . , and H e ilb o r n , H ., B e r . , 64, 1441 (1 9 3 1 ). 100 T sc h u d a , R . , K o b a y a sh i, M ., and N akam ura, A . , B u ll. Chem. Soc. J a p a n , 1 1 , 238 (1 9 3 6 ). T u rc o , A ., and P e c i l e , C . , N a tu r e , 1 9 1 , 6 6 (1 9 6 1 ). W i l l a r d , R.D., and W ilk in s o n , G . , J . Chem. Soc., 6041 (1 9 6 3 ). This dissertation has been microfilmed exactly as received 69-9044 TSIANG, Hon Gee, 1934- KINETICS AND CONFIGURATIONS OF COBALT(III)- BISDIMETHYLGLYOXIME COMPLEXES. University of Southern California, Ph.D., 1969 Chem istry, inorganic University Microfilms, Inc., Ann Arbor, Michigan

Linked assets

University of Southern California Dissertations and Theses

Conceptually similar

PDF

The Substitution Reactions Of Tetracyanosulfatoaquo Cobalt(Iii)

PDF

Oxidation and substitution reactions of cobalt cyanide complexes

PDF

Rare-earth carbides: structural and hydrolytic studies

PDF

The Chemistry Of Some Boron Hydrides And Their Derivatives In The Presence Of Basic Reagents

PDF

The Kinetics And Mechanism Of Oxidation Of Mercurous Ion By Peroxydisulfate

PDF

Kinetics of the reaction of peroxydisulfate ion with bromide ion in aqueous solution

PDF

A Study Of Mu-Superoxo And Mu-Peroxo Cobalt Binuclear Complexes

PDF

Some Aspects Of The Homogeneous Hydrogenation Of Persulfate Ion In Aqueous Solution

PDF

Fluorocarbon polyphosphine chemistry

PDF

A kinetic study of the base hydrolysis of chloroamminebis (dimethylglyoximato) cobalt (III)

PDF

A study of the polargraphic behavior of decaammine-[mu]-peroxodicobalt (III,IV) perchlorate

PDF

A study of the activation of hydrogen by cuprous salts in quinoline / by Max K. Barsh

PDF

Rare-Earth And Alkaline-Earth Amides And Pernitrides

PDF

Some Reactions Of Nido 4,5-Dicarbahexaborane(8) And Closo 1,5-Dicarbapentaborane(5)

PDF

Studies Of Rare-Earth Hydrogen Systems

PDF

Electrode-Potentials Of Rare-Earth Couples In Liquid Ammonia

PDF

The Representation Of The Static And Dynamic Chemistry Of Pentacoordinatemolecules By Mathematical Structures

PDF

Magnetic Circular Dichroism Of Impurities In Solids: D--->D Transitions In Magnesium-Oxide: Cobalt(Ii) And Potassium-Magnesium Fluoride: Cobalt(Ii)

PDF

The role of water in the heat denaturation of egg albumin

PDF

A study of the kinetics of the reaction of sulfenyl halides with olefins

Asset Metadata

Creator Tsiang, Hon Gee, 1934- (author)

Core Title Kinetics and configurations of cobalt(iii)-bisimethylglyoxime complexes

School Graduate School

Degree Doctor of Philosophy

Degree Program Chemistry

Degree Conferral Date 1968-09

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

Tag chemistry, inorganic,OAI-PMH Harvest

Language English

Contributor Digitized by ProQuest (provenance)

Advisor Wilmarth, Wayne K. (committee chair), [illegible] (committee member), Warf, James C. (committee member)

Permanent Link (DOI) https://doi.org/10.25549/usctheses-c18-666279

Unique identifier UC11361348

Identifier 6909044.pdf (filename),usctheses-c18-666279 (legacy record id)

Legacy Identifier 6909044.pdf

Dmrecord 666279

Document Type Dissertation

Rights Tsiang, Hon Gee

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...

Repository Name University of Southern California Digital Library

Repository Location USC Digital Library, University of Southern California, University Park Campus, Los Angeles, California 90089, USA