UBC Theses and Dissertations

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UBC Theses and Dissertations

Sulfoxide complexes of rhodium and iridium and their potential use as asymmetric hydrogenation catalysts Morris, Robert Harold 1978

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SULFOXIDE COMPLEXES OF RHODIUM AND IRIDIUM AND THEIR POTENTIAL USE AS ASYMMETRIC HYDROGENATION CATALYSTS by ROBERT HAROLD MORRIS B.Sc.(Hon.), U n i v e r s i t y o f W a t e r l o o , 1975 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY i n THE FACULTY OF GRADUATE STUDIES Department o f C h e m i s t r y We a c c e p t t h i s t h e s i s as c o n f o r m i n g t o t h e r e q u i r e d s t a n d a r d The U n i v e r s i t y o f B r i t i s h C o l u m b i a November, 1978 © R o b e r t H a r o l d M o r r i s , 1978 In p r e s e n t i n g t h i s t h e s i s in p a r t i a l f u l f i l m e n t o f the requ i rement s f o r an advanced degree at the U n i v e r s i t y o f B r i t i s h Co lumb ia , I a g ree that the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and s tudy . I f u r t h e r agree t h a t p e r m i s s i o n f o r e x t e n s i v e c o p y i n g o f t h i s t h e s i s f o r s c h o l a r l y purposes may be g r a n t e d by the Head o f my Department o r by h i s r e p r e s e n t a t i v e s . It i s u n d e r s t o o d that c o p y i n g o r p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l not be a l l o w e d w i thout my w r i t t e n p e r m i s s i o n . Department o f C^-^ m ' s l V y The U n i v e r s i t y o f B r i t i s h Co lumbia r 2075 W e s b r o o k P l a c e V a n c o u v e r , C a n a d a V6T 1W5 Date Oct IT!, f?7? i i ABSTRACT E f f i c i e n t p r e p a r a t i v e r o u t e s t o s e v e r a l new rhodium complexes and some i r i d i u m compounds c o n t a i n i n g s u l f o x i d e l i g a n d s a r e d e s c r i b e d . C h i r a l s u l f o x i d e complexes o f rhodium were t e s t e d as p o s s i b l e c a t a l y s t s f o r t h e homogeneous asymmetric h y d r o g e n a t i o n o f p r o c h i r a l o l e f i n s . A l s o t e s t e d were c h i r a l s u l f o x i d e - i r i d i u m complexes as p o t e n t i a l c a t a l y s t s f o r H2 t r a n s f e r f r o m i s o p r o p a n o l t o p r o c h i r a l o l e f i n s and k e t o n e s . The s u l f o x i d e s used i n c l u d e : t h e monodentate l i g a n d s d i m e t h y l (DMSO), t e t r a m e t h y l e n e (TMSO), d i - n - p r o p y l (NPSO), m e t h y l p h e n y l (MPSO), and d i p h e n y l s u l f o x i d e (DPSO); t h e monodentate c h i r a l l i g a n d s ( + ) - ( R ) - m e t h y l -p - t o l y l s u l f o x i d e (MPTSO), ( + ) - ( R ) - t - b u t y l - p - t o l y l s u l f o x i d e (TBPTSO), ( - ) - ( S ) - o - t o l y l - p - t o l y l s u l f o x i d e (OTPTSO), and ( + ) - ( S ) - 2 - m e t h y l b u t y l -( S , R ) - m e t h y l s u l f o x i d e (MBMSO); and t h e p o t e n t i a l l y c h e l a t i n g l i g a n d s m e s o - l , 2 - b i s ( m e t h y l s u l f i n y l ) e t h a n e (MSE), ( R , R ) - 1 , 2 - b i s ( p - t o l y l s u l f i n y l ) e t h a n e (PTSE), and ( - ) - ( 2 R , 3 R ) - 2 , 3 - 0 - i s o p r o p y l i d e n e - 2 , 3 - d i h y d r o x y -1 , 4 - b i s ( m e t h y l s u l f i n y l ) b u t a n e (DIOS). D i s p l a c e m e n t o f t h e l a b i l e a c e t o n e l i g a n d from [ R h ( d i e n e ) ( P P h ^ ) ( a c e t o n e ) ] A ( d i e n e = l , 5 - c y c l o o c t a d i e n e (COD), n o r b o r n a d i e n e (NBD); A=PF^ , SbFg ) a l l o w s f a c i l e c o o r d i n a t i o n o f d i a l k y l o r d i a r y l s u l f o x i d e s , and [ R h ( d i e n e ) ( P P h 3 ) L ] + complexes (L=DMSO,TMSO,NPSO,MBMSO,MPSO,MPTSO, and TBPTSO) have been s y n t h e s i z e d ; compounds w i t h L=AsPh.j,py and (CO)2 a l s o f orm. D i a r y l s u l f o x i d e s and DIOS c o o r d i n a t e , b u t no s o l i d s were i s o l a t e d . The u p f i e l d s h i f t s o f t h e s u l f o x i d e r e s o n a n c e s (^ "H nmr), r e f l e c t i n g s h i e l d i n g by t h e a d j a c e n t p h e n y l groups o f P P h q , and t h e d e c r e a s e i n i i i v(SO) on c o o r d i n a t i o n , a r e i n d i c a t i v e o f O-bonding i n a l l c a s e s . NMR d a t a on t h e o l e f i n i c d i e n e p r o t o n s s u g g e s t t h e o c c u r r e n c e o f some d i s p r o p o r t i o n a t i o n o f t h e mixed l i g a n d complexes t o [ R h ( d i e n e ) (PPh^) 2]"*" and [ R h ( d i e n e ) ( L ) 2 ] + > depending on L, and t h e p r e s e n c e o f 3 - c o o r d i n a t e , and 5 - c o o r d i n a t e ( f o r diene=NBD o n l y ) i n t e r m e d i a t e s . The h y d r o g e n a t i o n o f i t a c o n i c a c i d u s i n g c a t a l y s t s w i t h L=R-MPTSO o r DIOS r e s u l t e d i n no asym m e t r i c i n d u c t i o n i n t h e a - m e t h y l s u c c i n i c a c i d p r o d u c t because o f d i s p r o p o r t i o n a t i o n and c a t a l y s i s v i a t h e b i s ( t r i p h e n y l p h o s p h i n e ) system. E f f i c i e n t h y d r o f o r m y l a t i o n o f 1 - a l k e n e s i s e f f e c t e d u s i n g [ R h ( d i e n e ) ( P P h ^ ) ( C O ) 2 j + as c a t a l y s t p r e c u r s o r s . Aqueous i s o p r o p a n o l s o l u t i o n s o f RhC^^-SH^O on t r e a t m e n t w i t h s u l f o x i d e s p r o v i d e an e f f i c i e n t r o u t e t o R h C ^ L ^ complexes (L=DMSO, R-MPTSO,MPSO,TMSO) t h a t c o n t a i n i n s o l u t i o n , a t l e a s t f o r t h e f i r s t t h r e e s y s t e m s , two S-bonded s u l f o x i d e s t r a n s t o a c h l o r i d e , and an 0-bonded l i g a n d . The 0-bonded s u l f o x i d e i s d i s p l a c e d by amides, amine o x i d e s , and p h o s p h i n e o x i d e s t o g i v e mer-RhCfc^(DMSO)^(OL) complexes. The DMSO c i s t o OL i n RhC£^(DMSO)^(OL) or RuC£ 2(DMSO) 3(OL) can be i d e n t i f i e d i n t h e nmr by u s i n g t h e r i n g c u r r e n t s h i e l d i n g e f f e c t s o f OPPti^Me. R h C ^ L ^ r e a c t w i t h (1:1) i n base promoted r e a c t i o n s t o y i e l d R h ( I ) presumably v i a u n d e t e c t e d R h ( I I I ) - H s p e c i e s . RhC^.SH^O r e a c t s w i t h DPSO i n i s o p r o p a n o l t o g i v e R h ( I ) as t h e c h l o r i d e - b r i d g e d s p e c i e s [RhC£(DPSO) 2J 2• T h e r e a c t i o n w i t h NPSO g i v e s a R h ( I ) dimer ( i n d i r e c t e v i d e n c e ) and a R h ( I I I ) p r o d u c t , i s o l a t e d as [H(NPSO) 2][RhC£^(NPSO) 2] c o n t a i n i n g a s y m m e t r i c a l h y d r o g e n - b r i d g e d c a t i o n . A c r y s t a l s t r u c t u r e o f trans-[H(DMSO) ] [RhC£^(DMSO) ] r e v e a l s t h e s h o r t oxygen-oxygen d i s t a n c e (^2.45A) i n the c a t i o n e x p e c t e d f o r i v s t r o n g H-bonds. Such c a t i o n s d i s p l a y i n t e n s e v (OHO) bands a t 1700-di 1100 and 900-600 cm" 1. The a i r - s e n s i t i v e complexes [RhC£(C 0H,.)(DPS0)]_, [RhC£(DMS0)„]., [RhC£(DIOS) 2] 2 and [RhC£(MPSO)(PPh 3)] 2, i s o l a t e d from [RhC£(cyclooctene) ] ^ l i g a n d s o l u t i o n s , c o n t a i n v e r y l a b i l e Rh-S bonds t h a t do not appear t o i n v o l v e Rh(diT)+S (d-rr) b a c k b o n d i n g . A t t e m p t s a t g e n e r a t i n g h y d r i d e complexes by o x i d a t i v e a d d i t i o n o f H 2 o r HC£ t o R h ( I ) r e s u l t e d n o r m a l l y i n e i t h e r m e t a l f o r m a t i o n o r s u l f o x i d e r e d u c t i o n ; even i n the p r e s e n c e o f p r o c h i r a l o l e f i n s t h e s e c o m p l i c a t i o n s o c c u r r e d r a t h e r t h a n c a t a l y t i c a symmetric h y d r o g e n a t i o n . The compound [ R h ( M S E ) 2 ] P F ^ was i s o l a t e d from t h e r e a c t i o n o f H 2 w i t h [ R h ( N B D ) 0 ] P F , and 2 MSE i n a l c o h o l s o l u t i o n s . / o The compounds mer-IrC£ 2(H)(DMS0)^ w i t h t r a n s c h l o r i d e s , and mer-IrC£(H) 2(DMSO)^ w i t h c i s h y d r i d e s , were o b t a i n e d from o x i d a t i v e a d d i t i o n r e a c t i o n s i n v o l v i n g HC£ and E^, r e s p e c t i v e l y , w i t h [ I r C £ ( C g H ^ ) 2 ] 2 i n DMSO. The fo r m e r c a t a l y z e s t h e e f f i c i e n t s e l e c t i v e r e d u c t i o n o f a,$-u n s a t u r a t e d a l d e h y d e s t o t h e u n s a t u r a t e d a l c o h o l s . A t t e m p t s a t asymmetric s y n t h e s i s u s i n g as c a t a l y s t s IrCi^.3H20/chiral s u l f o x i d e m i x t u r e s f a i l e d . A s i m p l e bent M-K ) = L v i b r a t i o n a l model i s used t o e s t i m a t e from v(M0) and v (S0) t h e f o r c e c o n s t a n t s F.„ and F„ T u s i n g d a t a f o r s e v e n t y 0-bonded MO OL DMSO, DMSO-d,, and TMSO complexes o f s e v e r a l m e t a l s . The c o r r e l a t i o n o o F„=-(1.24±0.12)F w.+(8.78±0.12) mdyne/A appears t o h o l d f o r a l l m e t a l OL MO complexes e x c e p t i n g t h o s e o f group IVA and VA e l e m e n t s . V TABLE OF CONTENTS ABSTRACT TABLE OF CONTENTS LIST OF TABLES LIST OF FIGURES ABBREVIATIONS ACKNOWLEDGEMENTS CHAPTER 1. I n t r o d u c t i o n 1 1.1 The Importance o f C a t a l y t i c Asymmetric S y n t h e s i s 1 1.2 Aim 4 1.3 C a t a l y t i c P o t e n t i a l o f Rh, I r S u l f o x i d e Complexes 5 1.3.1 H y d r o g e n a t i o n o f O l e f i n s 5 1.3.2 S o l v e n t T r a n s f e r H y d r o g e n a t i o n o f 14 Keton e s and A l d e h y d e s 1.3.3 O x i d a t i o n R e a c t i o n s 15 1.3.4 Homogeneous Asymmetric H y d r o g e n a t i o n 15 1.4 S u l f o x i d e s as L i g a n d s 19 CHAPTER 2. A p p a r a t u s and G e n e r a l E x p e r i m e n t a l P r o c e d u r e s 22 2.1 I n s t r u m e n t a t i o n 22 2.2 Gas-Uptake A p p a r a t u s 23 2.3 Gas-Uptake E x p e r i m e n t a l P r o c e d u r e 23 2.4 M o d i f i c a t i o n s o f Gas-Uptake A p p a r a t u s 25 2.4.1 Gas I n l e t B u b b l e r 25 2.4.2 T e f l o n S t o p c o c k s 26 2.4.3 C o n v e n i e n t Ampoules 26 2.4.4 Low Temperature Uptake V e s s e l 27 2.5 Work-Up of H y d r o g e n a t i o n s o f I t a c o n i c A c i d 27 2.6 S t a r t i n g M a t e r i a l s 29 .2.6.1 Gases 29 2.6.2 S o l v e n t s 29 2.6.3 S i l v e r S a l t s 29 2.6.4 Rhodium S t a r t i n g M a t e r i a l s 29 2.6.4.1 [ R h ( n o r b o r n a d i e n e ) ] P F 6 30 2.6.4.2 [ R h ( c y c l o o c t a d i e n e J 2 ] S b F 6 30 2.6.5 I r i d i u m S t a r t i n g Complexes 30 2.6.6 S u l f o x i d e s ' 30 2.6.6.1 ( R ) - ( + ) - M e t h y l - p - t o l y l s u l f o x i d e , 31 18 2.6.6.2 ( R , R ) - ( l , 2 ) - b i s ( p - t o l y l s u l f i n y l ) 32 et h a n e , jL4_ v i 2.6.6.3 ( M e s o ) - ( l , 2 ) - b i s ( m e t h y l s u l f i n y l ) 34 ethane 2.6.6.4 ( S ) - M e t h i o n i n e - ( S ) - s u l f o x i d e , _16 35 CHAPTER 3. M i x e d S u l f o x i d e - T r i p h e n y l p h o s p h i n e C a t i o n i c Complexes 38 o f Rhodium(I) 3.1 S y n t h e s e s and S p e c t r o s c o p i c P r o p e r t i e s 38 3.1.1 I n t r o d u c t i o n 38 3.1.2 E x p e r i m e n t a l 38 3.1.2.1 [Rh ( d i e n e ) ( P P h o ) ( a c e t o n e ) ] A 39 3.1.2.2 [Rh(COD)(PPh 3)(DMSO)]PF 6 39 3.1.2.3 [Rh(COD)(DMSO-d 6) 2]SbF 6 44 3.1.2.4 [ R h ( N B D ) ( P P h 3 ) ( p y ) ] S b F 6 44 3.1.2.5 [ R h ( d i e n e ) ( P P h 3 ) ( A s P h 3 ) ] P F 6 : 45 diene=COD,NBD 3.1.2.6 [ R h ( d i e n e ) ( P P h 3 ) ( C O ) 2 ] P F 6 : 45 diene=COD,NBD 3.1.2.7 [ R h ( d i e n e ) ( P P h 3 ) ( D I O S ) ] P F 6 : 54 diene=COD,NBD 3.1.3 R e s u l t s and D i s c u s s i o n 54 3.1.3.1 A c e t o n e Complexes 54 3.1.3.2 S u l f o x i d e Complexes . 66 3.1.3.3 DMSO and TMSO Complexes 67 3.1.3.4 Other S u l f o x i d e Complexes. 74 3.1.3.5 Other M i x e d L i g a n d Complexes 76 3.2 The R e a c t i o n s o f t h e Mi x e d L i g a n d Complexes w i t h 77 Hydrogen 3.2.1 I n t r o d u c t i o n 77 3.2.2 E x p e r i m e n t a l 78 3.2.2.1 The nmr Spectrum of 79 [ R h ( N B D ) ( P P h 3 ) ( D I O S ) ] P F 6 + 2.5 H 2 3.2.3 R e s u l t s and D i s c u s s i o n 79 3.3 A t t e m p t s a t t h e Asymmetric H y d r o g e n a t i o n o f 85 P r o c h i r a l O l e f i n s 3.4 H y d r o f o r m y l a t i o n R e a c t i o n s U s i n g [ R h ( N B D ) ( P P h 3 ) ( C O ^ ] 86 3.4.1 I n t r o d u c t i o n 86 3.4.2 E x p e r i m e n t a l and R e s u l t s 87 3.4.3 D i s c u s s i o n 88 CHAPTER 4. S u l f o x i d e s S u l f u r - B o n d e d t o Rhodium 89 4.1 S y n t h e s i s and S p e c t r o s c o p i c P r o p e r t i e s 89 4.1.1 I n t r o d u c t i o n 89 4.1.2 E x p e r i m e n t a l 90 4.1.2.01 RhC£ 3L 3; L=DMS0, DMS0-d 6, TMSO, 90 MPSO, R-MPTSO 4.1.2.02 RhC£ 3(DMS0) 2(0L); (0L)=DMF,NFP 92 4.1.2.03 RhC£ 3(DPSO) 2(HOCH(CH 3) 2) . 92 4.1.2.04 [H(NPS0) 2][RhC£ 4(NPSO) 2] 92 4.1.2.05 [H(DMS0) 2][RhC£ 4(DMSO) 2] 93 v i i 4.1.2.06 [NEt 4][RhC£ 4(DMSO) 2] ' 93 4.1.2.07 [P.S.H][RhC£ 4(DMSO) 2]5 P.S.= 94 " P r o t o n Sponge", l , 8 - b i s ( d i m e t h y l -a m i n o ) n a p h t h a l e n e 4.1.2.08 [RhC£(DPSO) 2] 2 94 4.1.2.09 [RhC£(DPS0)(cyclooctene)] 2 95 4.1.2.10 [RhC£(DMSO) 2] 2 96 4.1.2.11 [RhC£(DIOS) 2] 2 96 4.1.2.12 [RhC£(MPS0)(PPh 3)] 2 98 4.1.3 R e s u l t s and D i s c u s s i o n 98 4.1.3.1 N e u t r a l R h ( I I I ) Complexes from 98 I s o p r o p a n o l S o l u t i o n s 4.1.3.2 D i p h e n y l s u l f o x i d e Complexes 109 4.1.3.3 A n i o n i c R h ( I I I ) Complexes 110 4.1.3.4 Rhodium(I) Complexes from 118 [RhC£(olefin) 2] 2 4.1.3.5 The N a t u r e o f R h o d i u m - S u l f u r B o n d i n g 120 i n S u l f o x i d e Complexes 4.2 R e a c t i o n s o f R h o d i u m - S u l f o x i d e Complexes w i t h Hydrogen; 123 A t t e m p t s t o Form M e t a l - H y d r i d e Complexes 4.2.1 I n t r o d u c t i o n 123 4.2.2 E x p e r i m e n t a l 123 4.2.2.1 R e a c t i o n s o f R h C £ 3 L 3 123 4.2.2.2 P r e p a r a t i o n o f [P.S.H][RhC£ 2(DMS0) 2] 123 4.2.2.3 R e a c t i o n o f RhC£ 3(DMS0) 3 w i t h 124 P r o t o n Sponge under A r 4.2.2.4 P r e p a r a t i o n o f [Rh(MSE) 2]PF 6:MSE= 130 m e s o - 1 , 2 - b i s ( m e t h y l s u l f i n y l ) e t h a n e 4.2.3 R e s u l t s and D i s c u s s i o n 131 4.2.3.1 The H e t e r o l y t i c C l e a v a g e o f H 2 by 131 RhC£ 3(sulfoxide) 3 Complexes 4.2.3.2 O x i d a t i v e A d d i t i o n R e a c t i o n s o f 134 R h ( I ) S u l f o x i d e Complexes 4.2.3.3 The R e a c t i o n s o f P r o t o n Sponge w i t h 136 RhC£ 3(DMS0) 3 4.3 A t t e m p t s a t C a t a l y t i c Asymmetric H y d r o g e n a t i o n 138 4.3.1 I n t r o d u c t i o n 138 4.3.2 E x p e r i m e n t a l 139 4.3.3 R e s u l t s and D i s c u s s i o n 139 CHAPTER 5. H y d r i d o i r i d i u m S u l f o x i d e Complexes 145 5.1. P r e p a r a t i o n and S p e c t r o s c o p i c P r o p e r t i e s 145 5.1.1 I n t r o d u c t i o n 145 5.1.2 E x p e r i m e n t a l 145 5.1.2.1 Trans-[H(DMSO) 2][IrC£ 4(DMSO) 2] 146 5.1.2.2 Cis-[H(DMS0) 2][IrC£4(DMSO) 2] 146 5.1.2.3 T r a n s - d i c h l o r o - m e r - t r i s ( D M S O ) h y d r i d o 147 i r i d i u m ( I I I ) 5.1.2.4 C h l o r o - c i s - d i h y d r i d o - m e r - t r i s ( D M S P ) 150 i r i d i u m ( I I I ) v i i i 5.1.2.5 At t e m p t e d P r e p a r a t i o n o f [IrC£(DMSO) 2]2 152 5.1.2.6 A t t e m p t e d P r e p a r a t i o n o f I r C J c ^ I ^ ; 152 L=MPSO,DPSO,MBMSO,TBPTSO,OTPTSO 5.1.3 D i s c u s s i o n 152 5.2 A t t e m p t s a t t h e Asymmetric H y d r o g e n a t i o n o f P r o c h i r a l 156 Keto n e s and O l e f i n s u s i n g I r i d i u m - C h i r a l S u l f o x i d e Complexes 5.2.1. I n t r o d u c t i o n 156 5.2.2 E x p e r i m e n t a l 157 5.2.3 R e s u l t s and D i s c u s s i o n 159 5.3 S o l v e n t T r a n s f e r H y d r o g e n a t i o n of a , ^ - U n s a t u r a t e d 162 Al d e h y d e s t o t h e U n s a t u r a t e d A l c o h o l s C a t a l y z e d by H y d r i d o i r i d i u m S u l f o x i d e Complexes 5.3.1 I n t r o d u c t i o n 162 5.3.2 E x p e r i m e n t a l 162 5.3.3 R e s u l t s and D i s c u s s i o n 162 CHAPTER 6. V i b r a t i o n a l A n a l y s i s o f Oxygen-Bonded S u l f o x i d e Complexes 166 6.1 I n t r o d u c t i o n 166 6.2 C a l c u l a t i o n s 167 6.3 R e s u l t s and D i s c u s s i o n 172 CHAPTER 7. C o n c l u s i o n s and Recommendations 183 7.1 C o o r d i n a t i o n C h e m i s t r y 183 7.1.1 P r e p a r a t i o n o f S u l f o x i d e Complexes o f Rhodium 183 and I r i d i u m 7.1.2 S p e c t r o s c o p i c P r o p e r t i e s o f t h e S u l f o x i d e Complexes 188 7.2 A t t e m p t s a t t h e C a t a l y t i c Asymmetric H y d r o g e n a t i o n o f 191 P r o c h i r a l O l e f i n s and Ketones 7.3 Other C a t a l y t i c R e a c t i o n s 192 BIBLIOGRAPHY:REFERENCES FOR CHAPTER 1 194 CHAPTER 2 201 CHAPTER 3 203 • CHAPTER 4 206 CHAPTER 5 211 CHAPTER 6 213 CHAPTER 7 216 i x LIST OF TABLES T a b l e Number Page 3.1 A n a l y t i c a l D a t a f o r t h e Rhodium(I) Complexes 40 3.2 I n f r a r e d D a t a (cm" 1) f o r [ R h ( d i e n e ) ( P P h 0 ) L ] P F , 41 Complexes 3.3 1 H nmr Data f o r [ R h ( C O D ) ( P P h 0 ) L ] P F , 42 j o Complexes a t 35°C 3.4 1 H nmr Data f o r [ R h ( N B D ) ( P P h 3 ) L ] P F 6 43 Complexes 3.5 Some I n f r a r e d D a t a (cm" 1) f o r [Rh(COD) ( P P h 0 ) L ] P F / . 70 J 6 L=DMS0 and DMSO-d^ 6 3.6 Some L i g a n d V i b r a t i o n s o f [ R h ( d i e n e ) ( P P h 3 ) L ] + 71 3.7 S t o i c h i o m e t r y o f Hydrogen Uptake by 83 [ R h ( d i e n e ) ( P P h 3 ) L ] A Complexes 4.1 S o l u t i o n I n f r a r e d Data f o r Rhodium S u l f o x i d e 100 Complexes i n Degassed CH 2C& 2 4.2 1 H nmr Data f o r RhCSl^(DMSO)3+0L 103 RhC£ 3(DMSO) 2(OL)+DMSO (4.1) 4.3 1 H nmr Data f o r RuC£ 2(DMSO) 4+0L 106 RuCJl 2(DMS0) 3(0L)+DMS0 (4.2) 4.4 • P h y s i c a l D a t a f o r S u l f u r - B o n d e d DMSO Adducts 122 4.5 "4l nmr Data f o r t h e R e a c t i o n o f P r o t o n Sponge 126 w i t h RhCJt- 3(DMSO) 3 i n C D 2 C £ 2 '' 4.6 Hydrogen Uptake Data f o r R h o d i u m - S u l f o x i d e 132 Complexes 4.7 A t t e m p t s a t C a t a l y t i c H y d r o g e n a t i o n u s i n g 142 R h o d i u m - S u l f o x i d e Complexes X T a b l e Number Page 5.1 The R e d u c t i o n o f Ketones C a t a l y z e d by I r ( I I I ) - 160 S u l f o x i d e Complexes. 5.2 The R e d u c t i o n o f O l e f i n s C a t a l y z e d by I r ( I I I ) - 161 S u l f o x i d e Complexes 5.3 H y d r o g e n a t i o n o f a , ^ - U n s a t u r a t e d A l d e h y d e s 164 6.1 I n f r a r e d D a t a f o r 0-Bonded DMSO and TMSO 168 Complexes 6.2 V i b r a t i o n a l D a t a f o r S u l f o x i d e Complexes 173 6.3 V i b r a t i o n a l Data f o r Other S u l f o x i d e Complexes 175 6.4 V i b r a t i o n a l Data f o r Group IVA and VA Complexes 181 x i LIST OF FIGURES F i g u r e Number Page 1.1 Amino A c i d P r e c u r s o r s : S u b s t r a t e s Used 3 i n C a t a l y t i c Asymmetric H y d r o g e n a t i o n 1.2 L i g a n d s f o r C a t a l y s t s o f t h e Type [ R h ( C O D ) P 2 ] + 3 1.3 C h i r a l S u l f o x i d e L i g a n d s 6 1.4 R h , I r S u l f o x i d e Complexes i n t h e L i t e r a t u r e 7 up t o 1978 1.5 S i m p l i f i e d Schemes o f Homogeneous 9 H y d r o g e n a t i o n s I n v o l v i n g P l a t i n u m M e t a l s 1.6 The P r o p o s e d Mechanism f o r S o l v e n t T r a n s f e r 12 H y d r o g e n a t i o n o f C h a l c o n e C a t a l y z e d by IrCJL 2(H)L 3,L=DMSO 1.7 Cis-PtC£ 2(S-MPTSO)(Olefin) D i a s t e r e o m e r s 16 1.8 The S t r u c t u r a l and S p e c t r o s c o p i c Data f o r 20 DMSO Complexes 2.1 C o n s t a n t P r e s s u r e Gas-Uptake A p p a r a t u s 24 2.2 C o n v e n i e n t Ampoule T e c h n i q u e s 27 2.3 Low Temperature Uptake V e s s e l 28 2.4 100 MHz 1 H nmr Spectrum of ( R , R ) - ( 1 , 2 ) - b i s 33 ( p - t o l y l s u l f i n y l ) e t h a n e , 1A_ 2.5 100 MHz """H nmr Spectrum of ( M e s o ) - ( 1 , 2 ) - b i s 36 ( m e t h y l s u l f i n y l ) e t h a n e 3.01 60 MHz 1 H nmr Spectrum o f [Rh(COD) (DMSO) ] +" 46 S b F J i n CDC£ 0 6 3 x i i F i g u r e Number 3.02 100 MHz 1 H nmr Spectrum o f [ R h ( C O D ) ( P P h n ) ( A s P h - ) ] P F , j j o (CD 3 ) 2 C O a t -50°C 3.03 100 MHz 1 H nmr Spectrum o f [Rh(NBD)(PPh.,)(AsPh„)]PF, J J O i n C D 2 C £ 2 a t -50°C 3.04 100 MHz 1 H nmr Spectrum o f [Rh(COD)(PPh 0)(C0)„]PF, -J 2 6 i n CDC£ 3 a t 35°C 3.05 100 MHz 1 H nmr Spectrum o f [Rh(NBD)(PPh,,)(acetone)]PF, -> 6 under CO i n CDC£ 3 a t a) -30°C b) 35°C 3.06 100 MHz 1 H nmr Spectrum o f [ R h ( C O D ) ( P P h . ) ( a c e t o n e ) ] P F , J 6 + DIOS i n CDC£ 3 a t 35°C 3.07 60 MHz 1 H nmr Spectrum o f [ R h ( N B D ) ( P P h _ ) ( a c e t o n e ) ] P F , J 6 + DIOS i n CDC£ 3 a t 35°C 3.08 100 MHz 1 H nmr Spectrum o f [ R h ( N B D ) ( P P h _ ) ( a c e t o n e ) ] P F , J 6 + DIOS i n CDC£ 3 a t -50°C 3.09 60 MHz 1 H nmr Spectrum o f [ R h ( C O D ) ( P P h _ ) ( a c e t o n e ) ] P F , 3 6 i n CDC£ 3 a t 35°C 3.10 60 MHz •'"H nmr Spectrum o f [Rh(NBD) ( P P h 0 ) ( a c e t o n e ) ] P F , J 6 i n CDC£ 3 a t 35°C 3.11 60 MHz 1 H nmr Spectrum o f [ R h ( N B D ) ( P P h _ ) ( a c e t o n e ) ] P F -> 6 i n a c e t o n e - d , a t 35°C 6 3.12 100 MHz "hi nmr Spectrum o f [ R h ( N B D ) ( P P h _ ) ( a c e t o n e ) ] P F , J 6 i n a c e t o n e - d , a t -60°C 6 3.13 60 MHz 1 H nmr Spectrum o f [Rh(NBD)(PPh„)(DMSO)1SbF, J 6 i n CDC£ 3 a t 35°C 3.14 100 MHz "Si nmr Spectrum of [Rh(NBD)(PPh 0)(DMSO)1SbF, 3 6 i n CDC£ 3 a t -30°C x i i i F i g u r e Number Page 3.15 60 MHz 1 H nmr Spectrum of [Rh(COD)(PPh 3)(DMSO)]SbF 6 68 i n CDC£ 3 a t 35°C 3.16 The I n f r a r e d S p e c t r a o f [ R h ( C O D ) ( P P h 3 ) ( L ) ] P F g as 72 a N u j o l m u l l ; (a) L=DMS0, (b) L=DMS0-d 6 3.17 The I n f r a r e d S p e c t r a o f [ R h ( C O D ) L 2 ] S b F 6 as a 73 N u j o l M u l l ; (a) L=DMS0, (b) L=DMS0-d 6 3.18 [ Rh ( d i e n e ) ( P P h J ( D I 0 S ) ] P F , 75 3.19 100 MHz nmr Spectrum o f [ R h ( N B D ) ( P P h 3 ) ( a c e t o n e ) ] P F 6 80 + DIOS R e a c t e d O v e r n i g h t w i t h H 2 i n ( C D ^ C O 3.20 (a) 100 MHz H i g h F i e l d """H nmr Spectrum of [Rh(NBD) ( P P h 3 ) 81 ( a c e t o n e ) ] P F , + 2.5 H„ i n DMA (b) Spectrum o f [Rh(NBD)(PPh„)„]SbF, + 3H„ i n DMA 81 J I D / 4.01 (a) I n f r a r e d Spectrum U s i n g N u j o l M u l l o f 97 [RhC£ (DMSO) 2 ] .DMSO (b) N u j o l M u l l o f [RhC£(DMS0-d 6) 2] 2 97 4.02 The L o c a l Environment o f Rh i n mer-RhC& 3(DMSO) 2(OL) 99 4.03 63.8-2.3 R e g i o n o f 100 MHz "Si nmr S p e c t r a u s i n g 104 CDCi>3 o f (a) RhC£ 3(DMSO) 3 + 3DMF (b) RhC£ 3 (DMS0) 3 ( c ) RhCi! 3(DMSO) 3 + 2 0PPhMe 2 (d) RhCX-3 (DMS0) 3 + 4.5 0PPh 2Me 4.04 The L o c a l Environment o f Ru i n RuC£ 2(DMS0)^ 105 4.05 63.8-2.5 R e g i o n o f 100 MHz 1 H nmr S p e c t r a u s i n g CDC£ 3 o f (a) RuC£ 2(DMSO) 4 + 6DMF (b) RuC£ 2(DMSO) 4 (c) RuC£ 2(DMSO) 4 + 4 0PPhMe 2 (d) RuC£ 2(DMSO) 4 + 107 4 0PPh 2Me x i v The M a i n P r o d u c t from t h e S e l e c t i v e Exchange R e a c t i o n o f RhC£„(DMS0)„ w i t h DMSO-d, i n CHC£„ 3 3 o 3 I n f r a r e d Spectrum of a N u j o l M u l l o f [H(NPSO) 2][RhC£ 4(NPSO) 2] I n f r a r e d Spectrum of a N u j o l M u l l o f [H(DMSO)]+" [RhC£ 4(DMSO) 2] -The C o n t e n t s o f a U n i t C e l l i n C r y s t a l l i n e [H(DMSO) 2][RhC£ 4(DMSO) 2] I n c l u d i n g S e l e c t e d Bond D i s t a n c e s , C o r r e c t e d f o r Thermal L i b r a t i o n s The Range of Bon d i n g Modes f o r S-bonded S u l f o x i d e s (a) The Hydrogen Uptake o f RhC£ 3(DMSO> 3 + 2 P r o t o n Sponge i n 1,2-C 2H 4C£ 2 a t 30°C (b) A n o t h e r E q u i v a l e n t o f RhC£ 3(DMSO) 3 was Added a t Th P o i n t 100 MHz "*"H nmr Spectrum o f 0.8 P r o t o n Sponge + RhC£ 3(DMSO) 3 i n C H 2 C £ 2 a t 38°C a f t e r l l h . 100 MHz nmr Spectrum u s i n g C D 2 C £ 2 o f Orange C r y s t a l s from t h e R e a c t i o n i n C H 2 C £ 2 o f 0.8 P.S. + RhC£ 3(DMSO) 3 100 MHz "'"H nmr Spectrum u s i n g C D 2 C £ 2 of t h e Orange C r y s t a l s from t h e R e a c t i o n o f 0.8 P.S. + RhC£ 3(DMSO-d 6) 3 100 MHz """H nmr Spectrum o f IrC£ 2H(DMSO> 3 .DMSO i n CDC£ 3 100 MHz "Si nmr Spectrum o f IrC£H 2(DMS0) 3 + HC£.DMA i n CDC£ n XV F i g u r e Number Page 5.3 The F o r m a t i o n and Some R e a c t i o n s o f I r - S u l f o x i d e 154 H y d r i d e Complexes 6.1 P l o t o f Frequency S h i f t o f v(SO) on C o o r d i n a t i o n 169 of 0-bonded S u l f o x i d e v s . v(MO) 6.2 Bent MOL Model 170 6.3 C o r r e l a t i o n o f F o r c e C o n s t a n t Data f o r TMSO Complexes 176 6.4 C o r r e l a t i o n o f F o r c e C o n s t a n t Data f o r TMSO, DMSO, 179 and DMS0-d 6 Complexes 6 - 5 C o r r e l a t i o n o f F o r c e C o n s t a n t Data f o r DMSO and DMS0-d ( Complexes of Some Group IVA and VA e l e m e n t s . 182 XVI ABBREVIATIONS A Ac A n a l . BDIOS Bu 1,2-C 2H 4C£ 2 C 8 H 1 4 C a l c d C a t * COD d DDIOS DIOP DIOS DMA DMF DMS DMSO DMSO DMSO-d, a n i o n , S b F , ,PF, 6 6 a c e t y l a n a l y s i s (2R, 3 R ) - 2 , 3 - 0 - i s o p r o p y l i d e n e - 2 , 3 - d i h y d r o x y - l , 4 -b i s ( b e n z y l s u l f i n y l ) b u tane n - b u t y l c o n c e n t r a t i o n i n g/100 g s o l v e n t 1 , 2 - d i c h l o r o e t h a n e c i s - c y c l o o c t e n e c a l c u l a t e d c h i r a l c a t a l y s t 1 , 5 - c y c l o o c t a d i e n e d o u b l e t ( 2R, 3R) - 2 , 3 - d i h y d r o x y - 1 , 4 - b i s ( m e t h y l s u l f i n y l ) b u t a n e ( 2 R , 3 R ) - 2 , 3 - 0 - i s o p r o p y l i d e n e - 2 , 3 - d i h y d r o x y - l , 4 - b i s ( d i p h e n y l p h o s p h i n o ) b u t a n e ( 2 R , 3 R ) - 2 , 3 - 0 - i s o p r o p y l i d e n e - 2 , 3 - d i h y d r o x y - l , 4 - b i s ( m e t h y l s u l f i n y l ) b u t a n e , see f i g u r e 1.3 N, N - d i m e t h y l a c e t a m i d e d i m e t h y l f o r m a m i d e d i m e t h y l s u l f i d e oxygen-bonded d i m e t h y l s u l f o x i d e s u l f u r - b o n d e d d i m e t h y l s u l f o x i d e h e x a d e u t e r o d i m e t h y l s u l f o x i d e x v i i DPSO d i p h e n y l s u l f o x i d e DSS sodium 2 , 2 - d i m e t h y l - 2 - s i l a p e n t a n o n e - S - s u l f o n a t e EA e t h y l a t r o p a t e e.e. e n a n t i o m e r i c e x c e s s E t e t h y l o F f o r c e c o n s t a n t (mdyne/A) F a v e r a g e f o r c e c o n s t a n t G.C. g a s - l i q u i d chromatography h h o u r s HOMO h i g h e s t o c c u p i e d m o l e c u l a r o r b i t a l HSAB Hard and S o f t A c i d s and Bases [HCP^SO)2]"^" s u l f o x i d e s b r i d g e d v i a t h e oxygens by hydrogen bonds I n u c l e a r s p i n I.A. ' i t a c o n i c a c i d , H 2C=C(COOH) (C^COOH) i r i n f r a r e d L l i g a n d LUMO l o w e s t u n o c c u p i e d m o l e c u l a r o r b i t a l m m u l t i p l e t M m o l a r i t y ; m e t a l MBMSO (-)-(S)-2-methyl b u t y l - ( S , R ) - m e t h y l s u l f o x i d e Me m e t h y l ME 2-methoxyethanol Men (-)-menthoxy MET ( S ) - m e t h i o n i n e min m i n u t e x v i i i m.p. m e l t i n g p o i n t MPSO m e t h y l p h e n y l s u l f o x i d e MPTSO ( R ) - m e t h y l - p - t o l y l s u l f o x i d e MSE m e s o - ( 1 , 2 ) - b i s ( m e t h y l s u l f i n y l ) e t h a n e mV m i l l i v o l t s NBD n o r b o r n a d i e n e NFP N - f o r m y l p i p e r i d i n e NPSO d i - n - p r o p y l s u l f o x i d e OL o x y g e n - d o n a t i n g l i g a n d OTPTSO o - t o l y l - p - t o l y l s u l f o x i d e P . t e r t i a r y p h o s p h i n e PBS p h e n y l b e n z y l s u l f i d e Ph p h e n y l ppm p a r t s p e r m i l l i o n P.S. " P r o t o n Sponge", 1 , 8 - b i s ( d i m e t h y l a m i n o ) n a p h t h a l e n e [ P . S . H ] + p r o t o n a t e d P r o t o n Sponge PTSE ( R , R ) - ( l , 2 ) - b i s ( p - t o l y l s u l f i n y l ) e t h a n e py p y r i d i n e PyNO p y r i d i n e N - o x i d e q q u a r t e t qu q u i n t e t r bond l e n g t h R a l k y l , a r y l s s i n g l e t ( n m r ) ; s t r o n g ( i r ) S s t y r e n e s e c second t t i m e x i x T t e m p e r a t u r e TBPTSO ( R ) - t - b u t y l - p - t o l y l s u l f o x i d e THF t e t r a h y d r o f u r a n TMS t e t r a m e t h y l s i l a n e TMSJD oxygen-bonded t e t r a m e t h y l e n e s u l f o x i d e t u t h i o u r e a V volume &a asymmetric d e f o r m a t i o n mode 8 c h e m i c a l s h i f t (ppm from TMS) 6 + p a r t i a l p o s i t i v e c h a r g e A c r y s t a l f i e l d s p l i t t i n g energy X normal mode f r e q u e n c y r o c k i n g mode :=C o l e f i n v • f r e q u e n c y (cm ^) X e l e c t r o n e g a t i v i t y X X ACKNOWLEDGEMENTS I w i s h t o e x p r e s s my g r a t i t u d e t o P r o f e s s o r B. R. James f o r h i s e x p e r t a d v i c e and f l e x i b l e g u i d a n c e i n g e n e r o u s l y accommodating f o r any d i g r e s s i o n s I made fr o m t h e main a i m o f my p r o j e c t . S i n c e r e t h a n k s i s a l s o e xtended t o Dr. K. J . Reimer f o r an i n t r o d u c t i o n t o S c h l e n k tube t e c h n i q u e s and rhodium c h e m i s t r y , t o Dr. A. W i l l i s and P r o f e s s o r F. W. B. E i n s t e i n f o r p r e l i m i n a r y r e s u l t s o f a c r y s t a l s t r u c t u r e d e t e r m i n a t i o n , and t o Dr. R. B a l l and P r o f e s s o r J . T r o t t e r f o r an a t t e m p t e d s t r u c t u r a l s t u d y on t h e m y s t e r i o u s P r o t o n Sponge complex. I acknowledge w i t h t h a n k s s u p p o r t from t h e N a t u r a l S c i e n c e s and E n g i n e e r i n g R e s e a r c h C o u n c i l o f Canada i n t h e form o f summer s t u d e n t -s h i p s and p o s t g r a d u a t e s c h o l a r s h i p s . I am i n d e b t e d t o Anna Wong f o r h e r d i l i g e n c e i n t y p i n g t h i s m a n u s c r i p t . F i n a l l y I w i s h t o than k C o l l e e n , whose encouragement i n s u r e d t h e r a p i d p r o g r e s s o f my work; our impending wedding was a g r e a t i n c e n t i v e . - 1 -1. I n t r o d u c t i o n 1.1 The Importance o f C a t a l y t i c Asymmetric S y n t h e s i s I f one were t o s t e p "Through t h e L o o k i n g G l a s s " 1 as A l i c e d i d , one w o u l d soon d i s c o v e r t h e e s s e n t i a l r o l e c h i r a l m o l e c u l e s p l a y i n our l i v e s . The f o o d and p h a r m a c e u t i c a l s t h e r e would be u s e l e s s o r even p o i s o n o u s t o t h e human system because n a t u r a l enzymes may not i n t e r a c t w i t h , o r may even be i n h i b i t e d by, m i r r o r image p r o t e i n s , c a r b o h y d r a t e s , n u c l e i c a c i d s , a l k a l o i d s e t c . . And t h e m i r r o r c h e m i s t s w i t h a l l o ur p r e s e n t knowledge c o u l d s y n t h e s i z e a s y m m e t r i c a l l y o n l y a few o f t h e c o r r e c t e n a n t i o m e r s one would need t o s u r v i v e i n t h e i r l o o k i n g g l a s s w o r l d . W i t h o u t t h e a i d o f enzymes o r c a t a l y s t s , a t t e m p t s a t such s y n t h e s i s would r e q u i r e t h e use o f l a r g e i m p r a c t i c a l amounts of c h i r a l r e s o l v i n g a g e n t s . However t h i s s i t u a t i o n i s c h a n g i n g w i t h t h e advent o f e f f e c t i v e homogeneous asymmetric s y n t h e s i s c a t a l y s t s ( C a t * ) . L i k e some enzymes t h e s e s o l u b l e c a t a l y s t s a r e c o m p r i s e d o f c h i r a l m o l e c u l e ( s ) bonded t o a t r a n s i t i o n m e t a l t h a t can s t i l l accommodate t h e b i n d i n g o f r e a c t a n t s , n o r m a l l y a m o l e c u l e X-Y and a p r o c h i r a l u n s a t u r a t e d s u b s t r a t e . W h i l e t h e m e t a l a c t i v a t e s t h e r e a c t i o n , t h e c h i r a l l i g a n d i n t e r a c t s w i t h t h e s u b s t r a t e so t h a t t h e a d d i t i o n o f X-Y t o one d i a s t e r e o t o p i c f a c e o f t h e u n s a t u r a t e , and hence t h e f o r m a t i o n o f one o p t i c a l isomer o f p r o d u c t , i s f a v o u r e d . I n t h i s f a s h i o n a s m a l l amount o f c h i r a l complex c a n e f f i c i e n t l y g e n e r a t e c a t a l y t i c a l l y a huge amount of o p t i c a l l y a c t i v e p r o d u c t . - 2 -R C a t * + X-Y -> > - C X R X-Y=H asymmetric 3 4 h y d r o g e n a t i o n ' (1.01) 1 2 R X=H, Y="C(0)H"(CCH-H 2) (1.02) asymmetric h y d r o f o r m y l a t i o n ^ R , C = 0 + X-Y R R C a t * X v . Y > C - 0 X-Y=H asymmetric V. A «-• 3 ' 6 h y d r o g e n a t x o n X=H; Y = S i R 3 asymmetric h y d r o s i l y l a t i o n 3,6 (1.03) (1.04) A decade o f r e s e a r c h i n t o a g r e a t number of c a t a l y s t s f o r r e a c t i o n s (1.01-1.04) has y i e l d e d some i n s i g h t i n t o t h e cause o f asymmetric i n d u c t i o n , and most i m p o r t a n t l y has r e s u l t e d i n t h e development o f some c h i r a l p h o s p h i n e - r h o d i u m complexes f o r e f f i c i e n t homogeneous h y d r o g e n a t i o n . These complexes a c t as c a t a l y s t s , a t ambient t e m p e r a t u r e and p r e s s u r e , f o r t h e s y n t h e s i s v i a e q u a t i o n (1.01) o f 85-100% o p t i c a l l y p u r e amino a c i d d e r i v a t i v e s o f S - " L " - a l a n i n e ( s u b s t r a t e 1 _ w i t h c a t a l y s t w i t h | o r 10, f i g u r e s 1.1, 1.2), R - " D " - a l a n i n e (1 w i t h 9 ) , S - p h e n y l a l a n i n e (3 w i t h 7,8,10,11,12, o r (-)-13) - 3 -F i g u r e 1.1. Amino a c i d p r e c u r s o r s : s u b s t r a t e s used i n c a t a l y t i c a symmetric h y d r o g e n a t i o n . for alanine for leucine H for phenylalanine for phenylalanine F i g u r e 1.2. L i g a n d s f o r c a t a l y s t s o f t h e t y p e [Rh(COD)P,J +. {+)-{RhZ' Ph 2 P (S,S>9 PPh, 9 >H P h 2 p v / - p p h 2 (R>109 PPhg PPhg PPhc — N <+)-&.R}-1312 -4-and (4_ w i t h 8 ) , R - p h e n y l a l a n i n e (3 w i t h 9_ o r ( + ) - 1 3 ) , S - l e u c i n e (2^ w i t h 8^  o r 1 0 ) , R - l e u c i n e (2 w i t h 9) , S - t y r o s i n e (5 w i t h 10 o r 12) , R-t y r o s i n e (5 w i t h 9), and L-DOPA, a dr u g t o combat P a r k i n s o n ' s d i s e a s e (6 w i t h J7_,_8,jL0, o r 1 2 ) . V a r i o u s Rh complexes o f DI0P (15b, f i g u r e 1.3) 1 _ 13,14 a r e a l s o e f f e c t i v e . I t i s c l e a r from t h e numerous r e v i e w s of s t u d i e s of rhodium-phosphine 3 \^ 15 16 17 and o t h e r m e t a l - c h i r a l l i g a n d c a t a l y s t s ' ' ' ' f o r r e a c t i o n s (1.01-1.04), t h a t t h e i n t e n s e i n t e r e s t i n t h i s a r e a w i l l r e s u l t i n t h e d i s c o v e r y of o t h e r t r a n s f o r m a t i o n s t h a t can be c a t a l y z e d w i t h t h e same h i g h e n a n t i o -s p e c i f i c i t y . P e rhaps i n t h e f u t u r e s y n t h e t i c o r g a n i c c h e m i s t s w i l l r o u t i n e l y l e a v e u n s a t u r a t e d l i n k a g e s as l a t e n t c h i r a l s i t e s t h a t can be d e v e l o p e d a t a l a t e r c o n v e n i e n t s t e p by t h e a p p l i c a t i o n o f an asymmetric c a t a l y s t . These 18 19 20 f u t u r e c a t a l y s t s w i l l l i k e l y be t e t h e r e d t o an i n s o l u b l e s u p p o r t ' ' t o f a c i l i t a t e t h e i r r e c o v e r y f r o m t h e p r o d u c t s . The use o f h e t e r o g e n e o u s c a t a l y s t s m o d i f i e d w i t h c h i r a l m o l e c u l e s i s a l e s s p r o m i s i n g a p p r o a c h ; a l t h o u g h m e t h y l a c e t o a c e t a t e and a m i n o - a c i d p r e c u r s o r s have been h y d r o -21 22 g e nated t o 90% e.e. i n s p e c i a l c a s e s . ' A l t e r i n g t h e c h e m i s t r y of a m e t a l s u r f a c e and f o l l o w i n g t h e r e a c t i o n s by s p e c t r o s c o p y a r e much more d i f f i c u l t t h a n s t u d y i n g homogeneous c a t a l y s t s . C e r t a i n l y c h e m i s t s , u s i n g t h e s e d e v e l o p m e n t s , w i l l be a b l e t o s u p p l y A l i c e , who d i d s w a l l o w some s t r a n g e f o o d s i n t h e l o o k i n g g l a s s w o r l d , w i t h some n a t u r a l n u t r i e n t s . 1.2 Aim Due p r o b a b l y t o t h e s u c c e s s o f c h i r a l p h o s p h i n e - r h o d i u m c a t a l y s t s , 23 24 25 o t h e r c h i r a l l i g a n d s y s t e m s , i n c l u d i n g Rh-amides , Co-amines ' , P t -26 _ 27 28 1 f .. 29,30,31 amines , Rh, I r - S c h i f f b ases , R u - c a r b o x y l a t e s , and R u - s u l f o x i d e s - 5 -have r e c e i v e d much l e s s a t t e n t i o n even though t h e y may i n v o l v e c o m p l e t e l y d i f f e r e n t l i g a n d - s u b s t r a t e i n t e r a c t i o n s . T h i s i s a main r e a s o n why c h i r a l 31 s u l f o x i d e s c o o r d i n a t e d t o r u t h e n i u m were f i r s t s t u d i e d i n our l a b o r a t o r y and why t h i s l e d t o t h e s t u d y of t h e i r c o o r d i n a t i o n t o rhodium and i r i d i u m , t h e s u b j e c t of t h i s t h e s i s . S u l f o x i d e s have been d e v e l o p e d ( f i g u r e 1.3) w i t h s t r u c t u r e s a n a l o g o u s t o t h e s u c c e s s f u l c h e l a t i n g p h o s p h i n e s shown i n f i g u r e 1.2, as w e l l as ones w i t h q u i t e d i f f e r e n t f u n c t i o n a l g r o u p i n g s . Some have a l r e a d y been used s u c c e s s f u l l y i n a s ymmetric h y d r o g e n a t i o n : RuCft,, (DIOS)(DDIOS), where DDIOS i s t h e a c e t a l c l e a v e d d e r i v a t i v e of DIOS, gave S - N - a c e t y l a l a n i n e i n 7.2% e.e. and R-methyl s u c c i n i c a c i d w i t h up t o 25.2% e . e . ( r e f . 3 1 , page 228); [ R u C i l 2 ( M B M S O ) 2 l 3 gave 1.5% and up t o ! 6 % , r e s p e c t i v e l y ( r e f . 31, page 202). B o t h of t h e s e c a t a l y s t s c o n t a i n l i g a n d s w h i c h a r e m i x t u r e s of S,S and S,R d i a s t e r e o m e r s a t s u l f u r . I t was t h e r e f o r e o f i n t e r e s t t o f i n d out whether b e t t e r r e s u l t s c o u l d be o b t a i n e d w i t h o p t i c a l l y p u r e 14,16,18,19,20 on a rhodium o r i r i d i u m c e n t e r . The r e l a t i v e l y few s u l f o x i d e complexes o f Rh and I r r e p o r t e d up t o 1978 ( f i g u r e 1.4), a p a r t from t h o s e o f t h i s t h e s i s , were g e n e r a l l y s y n t h e s i z e d u s i n g t h e s u l f o x i d e as t h e s o l v e n t or i n g r e a t e x c e s s . Con-s e q u e n t l y an aim o f t h i s work was t o d e v i s e r o u t e s t o complexes t h a t u t i l i z e a minimum o f t h e v a l u a b l e c h i r a l r e a g e n t s . 1.3 C a t a l y t i c P o t e n t i a l o f Rh, I r S u l f o x i d e Complexes  1.3.1 H y d r o g e n a t i o n o f O l e f i n s H y d r o g e n a t i o n s u s i n g homogeneous p l a t i n u m m e t a l c a t a l y s t s have been found t o o c c u r m a i n l y t h r o u g h t h e two t y p e s o f schemes e x e m p l i f i e d i n -6-F i g u r e 1.3 ( R , R ) - l , 2 - b i s ( p - t o l y l s u l f l n y l ) e t h a n e 3 2 ( P T S E ) 14 c f . 8 H O -R -R H .31 R=(R,S)-S(0)CH 3 g i v e s 2R,3R-(-)-DIOS 15a; R=PPh 2 g i v e s 2R,3R-(-)-DIOP 15b 33 ( S ) - m e t h i o n i n e - ( S ) - s u l f o x i d e (METO) 16 ( + ) - ( S ) - 2 - m e t h y l b u t y l - ( R , S ) - m e t h y l s u l f o x i d e 3 1 ( M B M S O ) 17 MPTSO 18 TBPTSO 19 OTPTSO 20 ( + ) - ( R ) - m e t h y l -p - t o l y l s u l f o x i d e 3 0 ' 3 4 ( + ) - ( R ) - t - b u t y l -p - t o l y l s u l f o x i d e 3 4 ( - ) - ( S ) - o - t o l y l -p - t o l y l s u l f o x i d e 3 ^ - 7 -F i g u r e 1.4 Rh, I r S u l f o x i d e Complexes i n t h e L i t e r a t u r e up t o 1 9 7 8 ^ RhOO R h C £ ( D M S 0 ) ( P P h ) 3 5 , RhC£(CO)(DMSO) 3 6 , [Rh(COD) (DMSO) J B F 3 7 z — 2 4 21 22 23 I r ( D [ I r ( C O ) ( D M S O ) ( P P h „ ) „ ] C J l 0 3 8 — J 2 4 24 R M I D R h 2 ( 0 2 C R ) 4 . 2 R 2 S 0 3 9 ' 4 0 25 L(im mer-RhC£ 3 ( R 2 S 0 ) 2 ( R ^ O ) 4 1 ' 4 2 ' 4 3 , trans-Na[RhC£ 4(R^O) ] 4 1 ' 4 4 Rh( 26 . 27 mer-RhC£ 3 (DMSO) ( p y r i d i n e ) 2 4 5 , RhC£ 3 (DMSO) ( e n ) 4 6 28 29 [RhC£(DMSO) 5][C£0 4] 2 4 7 30 [H(DMSO) 2 ) [RhC£ 4 (DMSO) 2 ] 4 8 , [Rh ( M e ^ p ) (DMSO) 3 ] [ P F 6 ] 4 9 31 32 I r ( I I I ) cis,trans-[H(DMSO) 2][IrC£ 4(DMSO) 2] 5 0, [ I r ( M e ^ p ) (DMSO) ] [PF ] 4 9 33 34 6 2 I r C £ 3 ( D M S O ) 3 5 0 , IrC£ 3(DMSO) 2(DMSO) 5 0, IrC£ 2(H)(DMSO) 5 0 35 36 37 IrC£(H) 2(DMS^0) 3 5 0 38 (a) not i n c l u d i n g t h o s e o f 51 r - i t h i s t h e s i s . 0 and JS mean T~ST\T\ 51 M L u c o i o . w emu o mean i L i m I r C £ 4 ( D M S 0 ) 2 , [ H ( D M S O ) 2 ] 2 [ I r C £ 6 ] M r e s p e c t i v e l y 0- and S- b o n d i n g o f t h e s u l f o x i d e . Me Cp means 12. 40 p e n t a m e t h y l c y c l o p e n t a d i e n y l . - 8 -3 15 f i g u r e 1.5. ' The schemes d i f f e r m a i n l y i n t h e mode of hydrogen a d d i t i o n t o t h e complex; t h e y have been t h o r o u g h l y r e v i e w e d by 3 15 52 53 o t h e r s ' ' ' , and hence o n l y some r e c e n t f i n d i n g s a l o n g w i t h r e l e v a n t examples w i l l be mentioned h e r e . The o x i d a t i o n s t a t e o f t h e m e t a l i n scheme I does n o t change t h r o u g h o u t t h e v a r i o u s c y c l e s because t h e i s h e t e r o l y t i c a l l y c l e a v e d t o H and H + v i a e q u a t i o n (1.05) o r (1.08) and t h e h y d r i d e l i g a n d s u b s t i t u t e s i n t o t h e m e t a l c o o r d i n a t i o n s p h e r e . An example i s t h e h y d r o g e n a t i o n o f a c r y l a m i d e i n DMA by [RuCJl^ (DMSO)^] t h a t goes v i a 31 t h e " h y d r i d e r o u t e " ( 1 . 0 5 ) , ( 1 . 0 6 ) . A d d i t i o n o f base promotes r e a c t i o n (1.05) and i n d e e d i n t h i s c a s e w i t h o u t s u b s t r a t e p r e s e n t , h y d r i d e s a r e d e t e c t e d by rimr.. D i r e c t e v i d e n c e f o r t h e p r o t o n o l y s i s o f an a l k y l ^6_ v i a (1.10) was o b t a i n e d i n t h e h y d r o g e n a t i o n o f d i p h e n y l -a c e t y l e n e by IrC£ 2(H) (DMS0) 3 > 37.. The a l k e n y l i n t e r m e d i a t e 52^ c o u l d be H_C, C,H C,H C,H 37 + C AH,C=CC,H + 5 6 > = / 6 5 — • > K l Z 6 5 — 6 5 6 5 / \^ HC£ > v + _35 H IrC£ 9(DMSO) H H 52 1 1 i s o l a t e d and t h e n t r e a t e d w i t h a c i d t o g i v e t h e reduced p r o d u c t and 35, 54 a p r e c u r s o r t o t h e h y d r i d e _3_7. The h y d r o g e n o l y s i s o f t h e a l k y l 46 ( e q u a t i o n 1.11) i s e x e m p l i f i e d by RhH(CO)(PPh^)^ systems ( r e f . 15, page 402), I n scheme I I , t h e o x i d a t i o n s t a t e and c o o r d i n a t i o n number o f t h e m e t a l change by two when hydrogen i s o x i d a t i v e l y added"'"' (1.12, 1.15) and when t h e s a t u r a t e d p r o d u c t i s e l i m i n a t e d ( 1 . 1 6 ) . W i l k i n s o n ' s c a t a l y s t , -9-F i g u r e 1.5 S i m p l i f i e d Schemes o f Homogeneous H y d r o g e n a t i o n s i n v o l v i n g P l a t i n u m M e t a l s * L may be v a r i o u s l i g a n d s o r s o l v e n t s . R i s a a-bonded a l k y l . Some s t e p s w i l l be r e v e r s i b l e . Charges on t h e complexes have been i g n o r e d . -10-R hC£(PPh 3) 3, i s t hought t o f o l l o w b o t h t h e h y d r i d e r o u t e ( 1 . 1 2 ) , (1.14) and t h e u n s a t u r a t e r o u t e ( 1 . 1 3 ) , (1.15) a l t h o u g h r e c e n t s t u d i e s i n d i c a t e t h a t t h e f o r m e r p r e d o m i n a t e s . ^ * I n t e r m e d i a t e 48 may be f i v e -c o o r d i n a t e b ecause of t h e l a r g e t r a n s i n f l u e n c e of t h e h y d r i d e s , and 5 6 i f s o , _50 would t h e n be f a v o u r e d . Rearrangement t o j j l may be n e c e s s a r y t o a l l o w t r a n s f e r of b o t h h y d r i d e s t o t h e s u b s t r a t e . There i s good e v i d e n c e t h a t a c i s o r i e n t a t i o n of h y d r i d e and o l e f i n (51) i s t h e i n t e r -m e d i a t e t o a l k y l f o r m a t i o n , s i n c e a c i s , c i s c o m p l e x ^ I r H 2 ( C O D ) ( P P h ^ M e ) ^ ] ^ 60 has now been o b s e r v e d and s t u d i e d a t low t e m p e r a t u r e . I n c o n t r a s t , t h e c i s - h y d r i d e t r a n s - p h o s p h i n e isomer e q u i v a l e n t t o _50 was more s t a b l e and c o u l d be i s o l a t e d . ^ The O s b o r n - t y p e c a t a l y s t s , J54, _55, d e r i v e d from [Rh ( d i e n e ) L ^ ] + , 53, v i a e q u a t i o n s ( 1 . 1 8 ) , ( 1 . 1 9 ) , [ R h ( d i e n e ) L n ] + + 3H 2 ->- a l k a n e + [ H 2 R h L n ( s o l v e n t ) x ] + (1.18) 53 54 54 v -1 H + + \HRhL ( s o l v e n t ) (1.19) n y . 55 L = P R 3 , A s R 3 n=2 o r 3 x,y=l,2 o r 3 h y d r o g e n a t e o l e f i n s and a c e t y l e n e s by b o t h schemes s i n c e t h e a c t i v e mono-h y d r i d e of I , ^ 2 , can i n t e r c o n v e r t w i t h t h e d i h y d r i d e of I I , 48^, v i a 53 e q u a t i o n (1.19=1.17 i n scheme I I ) . By f o r c i n g one r egime t h r o u g h t h e a d d i t i o n of e x c e s s a c i d or b a s e , i t was deduced t h a t _55_ was a v e r y good h y d r o g e n a t i o n and i s o m e r i z a t i o n c a t a l y s t whereas was good f o r h y d r o -53 g e n a t i o n and poor f o r i s o m e r i z a t i o n . Of i n t e r e s t , t h e c a t i o n i c - 1 1 -d i p h o s p h i n e s [ R h ( d i e n e ) L ] + , L =diphos, DIOP, and p r o b a b l y t h e o t h e r l i g a n d s o f f i g u r e 1.2, do not form d i h y d r i d e s and so l i k e l y f o l l o w __ 61,62 t h e u n s a t u r a t e r o u t e of scheme I I . Only l i g a n d s f u l f i l l i n g c e r t a i n c r i t e r i a s u p p o r t t h e c a t a l y s i s d e s c r i b e d i n f i g u r e 1.5. (1) They must be o f s u f f i c i e n t c r y s t a l f i e l d s p l i t t i n g s t r e n g t h t o t h e r m o d y n a m i c a l l y f a v o u r h y d r i d e f o r m a t i o n -i f t h e energy gap between t h e HOMO and LUMO ( A ) o f t h e m e t a l i s t o o low, t h e h y d r i d e b o n d i n g e l e c t r o n i s e a s i l y promoted t o an a n t i b o n d i n g o r b i t a l and t h e h y d r i d e becomes t o o l a b i l e - but not so s t r o n g t o r e n d e r 52 t h e h y d r i d e k i n e t i c a l l y i n e r t . I r i d i u m ( I I I ) c a t a l y s t s t e n d t o be l e s s a c t i v e t h a n t h o s e o f R h ( I I I ) b ecause o f t h e i n c r e a s e i n A , i n g o i n g from the second t o t h e t h i r d row o f 52 t h e p e r i o d i c t a b l e and hence t h e d e c r e a s e i n l a b i l i t y o f I r - H . T h i s i n c r e a s e i n s t a b i l i t y , h o w e v e r , a l l o w s t h e i s o l a t i o n o f i n t e r e s t i n g i n t e r -m e d i a t e s such as _52. Lower v a l e n t I r ( I ) and R h ( I ) t e n d t o be more r e a c t i v e because o f t h e l o w e r A v a l u e s . (2) Good sigma donor a n c i l l a r y l i g a n d s a r e r e q u i r e d t o " a c t i v a t e " t h e h y d r i d o o l e f i n i n t e r m e d i a t e s 44^ and _5_1, e s p e c i a l l y i n a symmetric h y d r o -g e n a t i o n where s u b s t r a t e s s u c h as 1 t o 6 have e l e c t r o n w i t h d r a w i n g g r o u p s . (3) Some o f t h e l i g a n d s must be l a b i l e t o y i e l d r e a c t i v e , c o o r d i n a t i v e l y u n s a t u r a t e d s p e c i e s f o r s t e p s ( 1 . 0 5 ) , ( 1 . 0 6 ) , ( 1 . 0 7 ) , ( 1 . 0 8 ) , (1.13) and 63 ( 1 . 1 4 ) . B u l k y l i g a n d s may have t h i s p r o p e r t y . (4) O x i d a t i v e a d d i t i o n r e a c t i o n s (1.12) and (1.15) a r e promoted by l i g a n d s w h i c h f a v o u r t h e R h ( I I I ) , I r ( I I I ) s t a t e (PPh 3>C0) and w h i c h f a v o u r f o u r o v e r f i v e c o o r d i n a t e I r ( I ) , R h ( I ) . ~ ^ C l e a r l y t h e r e a c t i v e s o l v a t e d h y d r i d e s j>4_ and J5_5 f u l f i l t h e s e r e q u i r e m e n t s , h a v i n g s t r o n g l y -12-bonded good a d o n o r s (L) and l a b i l e s o l v e n t l i g a n d s . The few r e p o r t s on s u l f o x i d e s and s u l f i d e s o f I r and Rh as o l e f i n h y d r o g e n a t i o n c a t a l y s t s s u g g e s t t h a t t h e s e s u l f u r l i g a n d s do have c a t a l y t i c p o t e n t i a l d e s p i t e t h e i r r e p u t a t i o n as p o i s o n s o f h e t e r o g e n e o u s 64 c a t a l y s i s . The I r s u l f o x i d e complexes 33, 35, 36, and _37_ ( f i g u r e 1.4) c a t a l y z e t h e B.^ t r a n s f e r from b o i l i n g i s o p r o p a n o l t o a , 6 - u n s a t u r a t e d k e t o n e s and a c e t y l e n e s t o g i v e s a t u r a t e d k e t o n e s and c i s o l e f i n s , r e s p e c t i v e l y . " * 4 ' ^ Under s i m i l a r c o n d i t i o n s c h l o r o i r i d i u m complexes 66 go t o m e t a l . The common r e a c t i v e b u t i s o l a b l e complex f o r t h e s u l f o x i d e systems i s IrCZ^(H) (DMSO)^, _37_, s i n c e i t r e a c t s d i r e c t l y w i t h s u b s t r a t e s t o y i e l d t h e i s o l a b l e a l k y l i n t e r m e d i a t e s _5_2 and 56 ( f i g u r e 1 . 6 ) ^ ; t h i s i s a n a l o g o u s t o a pathway o f scheme I : ( 1 . 0 5 ) , ( 1 . 0 6 ) , ( 1 . 0 9 ) , ( 1 . 1 0 ) . Thus DMSO f i t s c r i t e r i o n (1) f o r h y d r i d e f o r m a t i o n and c r i t e r i o n (3) f o r complex l a b i l i t y , where s u l f u r - b o n d e d F i g u r e 1.6 The P r o p o s e d Mechanism f o r S o l v e n t T r a n s f e r H y d r o g e n a t i o n o f C h a l c o n e C a t a l y z e d by IrC£ 9(H)L,, L=DMS0; X may be L o r s o l v e n t . 57 -13-DMSO must d i s s o c i a t e i n s t e p s (1.20) and p o s s i b l y (1.22) t o a l l o w f o r i s o p r o p a n o l c o o r d i n a t i o n . R e p o r t s i n v o l v i n g Rh s u l f o x i d e ' c a t a l y s t s a r e s c a r c e . R u s s i a n w o r k e r s g i v e no d e t a i l s i n t h e i r c l a i m t h a t RhCJi^ (DMSO) 3 , _26, as w e l l as I r ( I I I ) c omplexes, a r e i n e r t as homogeneous h y d r o g e n a t i o n and 67 i s o m e r i z a t i o n c a t a l y s t s , and t h a t 2j5 goes t o m e t a l under H^. W i t h t h e a d d i t i o n o f 6 NaBH^ p e r Rh i n DMSO, complex 26_ i s r e d u c e d t o what i s s a i d t o be an a c t i v e Rh(I)-DMS0 complex f o r pentene r e d u c t i o n and 68 i s o m e r i z a t i o n a t 20°C, a l t h o u g h l i t t l e e v i d e n c e i s p r e s e n t e d . Formed 69 i n s i t u f rom h o t DMSO and R h C £ 3 ( H 2 0 ) 3 , _26 does h y d r o g e n a t e DMSO ( t h e s o l v e n t ) t o d i m e t h y l s u l f i d e and w a t e r a t 80°C and 1 a t m . 7 ^ A r e a c t i v e R h ( I I I ) - H was p o s t u l a t e d , and a s l o w r e d u c t i o n t o R h ( I ) ( c f . scheme I,42-»47) was thought t o d e a c t i v a t e t h e c a t a l y s t . R h C £ 3 ( E t 2 S ) 3 i n DMSO c a t a l y z e s b o t h DMSO and m a l e i c a c i d r e d u c t i o n a t 80°C, a l t h o u g h t h e s o l v e n t r e a c t i o n d i s c o u r a g e d f u r t h e r s t u d y o f t h e o l e f i n system ( r e f . 71, page 180). P r e s u mably t h i s o l e f i n r e d u c t i o n f o l l o w s t h e same p a t h as t h a t c o n s i d e r e d f o r t h e R h C £ 3 ( E t 2 S ) 3 r e d u c t i o n o f c i n n a m i c a c i d , m a l e i c a c i d , and e t h y l e n e i n DMA a t 70°and 1 atm. Here t h e R h ( I I I ) complex i s i n i t i a l l y r e d u c e d t o a R h ( I ) s p e c i e s , by l o s i n g a s u l p h i d e l i g a n d and t h e n by h e t e r o l y t i c a l l y c l e a v i n g H 2 v i a (1.05) t o a R h ( I I I ) - H i n t e r m e d i a t e t h a t decomposes t o 47. H y d r o g e n a t i o n t h e n p r o c e e d s v i a t h e u n s a t u r a t e r o u t e o f scheme I I : ( 1 . 1 3 ) , ( 1 . 1 5 ) , ( 1 . 1 6 ) . K i n e t i c d a t a o b t a i n e d u s i n g s o l u t i o n s o f [RhC£(cyclooctene) 2] 2 and 4 E t 2 S i n DMA, t o g e n e r a t e s i m i l a r R h ( I ) s p e c i e s i n s i t u , a r e i n good agreement w i t h t h e s e f i n d i n g s ( C h a p t e r 6 i n r e f . 7 1 ) . I n t h e absence o f a s t a b i l i z i n g o l e f i n s u c h as m a l e i c a c i d (but n ot c y c l o o c t e n e ) , such i n s i t u R h ( I ) -14-s o l u t i o n s d i s p r o p o r t i o n a t e t o R h ( I I ) and Rh m e t a l ( r e f . 71, page 134) whether under o r N^. T h i s i s a l s o t h e c a s e f o r t h e c o r r e s p o n d i n g SPh^ and SCCH^Ph^ systems. C l e a r l y t h e s e l i g a n d s a r e not as e f f e c t i v e as p h o s p h i n e s i n removing e l e c t r o n d e n s i t y from R h ( I ) and t h e y a r e a l s o not as e f f e c t i v e as c h l o r i d e s i n a c t i v a t i n g 49_ toward o x i d a t i v e a d d i t i o n o f ( c r i t e r i o n ( 4 ) ) , s i n c e t h e c h l o r o r h o d a t e ( I ) / m a l e i c 72 acid/DMA system i s f i v e t i m e s more a c t i v e . 1.3.2 S o l v e n t T r a n s f e r H y d r o g e n a t i o n o f Ketones and A l d e h y d e s 66 73 Both IrC£ 2H(DMSO)° , 37, and RhC£(DMSO)(PPh^) 2 , 21> c a t a l y z e e q u i l i b r i u m ( 1 . 2 3 ) . To d r i v e t h i s r e a c t i o n t o t h e r i g h t (98% p r o d u c t s ) , 74 R^R 2CO must be e a s i e r t o r e d u c e t h a n R^R^CO by about 100 mV , a l t h o u g h R 1R 2C=0 + R ^ C H O H v s R ^ C H O H + R 3R 4C=0 (1.23) i f a p r o d u c t i s c o n t i n u o u s l y removed ( e . g . a c e t o n e ) t h i s p o t e n t i a l d i f f e r e n c e can be l e s s . The s p r e a d o f o x i d a t i o n p o t e n t i a l s f o r p r i m a r y and s e c o n d a r y a l c o h o l s i s 300 mV; t h i s range i n c l u d e s s e c o n d a r y a l c o h o l s w i t h e l e c t r o n d o n a t i n g groups (60-160), s e c o n d a r y a l c o h o l s w i t h e l e c t r o n w i t h d r a w i n g groups (160-360), and p r i m a r y a l c o h o l s w i t h 74 e l e c t r o n w i t h d r a w i n g groups (200-300). Hence, 2 - p r o p a n o l w i t h e l e c t r o n d o n a t i n g groups i s a c o n v e n i e n t r e d u c t a n t o f most k e t o n e s and a l d e h y d e s . C h l o r o i r i d a t e ( I I I ) s p e c i e s i n r e f l u x i n g D M S O / i s o p r o p a n o l ^ o r H 3 P 0 3 / i s o p r o p a n o l ^ r e d u c e d c y c l o h e x a n o n e s a t a h i g h e r r a t e , and w i t h a much h i g h e r a x i a l t o e q u a t o r i a l a l c o h o l p r o d u c t r a t i o , t h a n c o r r e s -p o n d i n g p h o s p h i n e systems. W i t h DMSO, t h e a c t i v e s p e c i e s I r C & 2 H ( D M S 0 ) 3 , -15-37, i s thought t o be formed a l o n g w i t h a c e t o n e by c o o r d i n a t i o n o f t h e i s o p r o p a n o l as an a l k o x i d e l i g a n d , f o l l o w e d by 3 - h y d r i d e a b s t r a c t i o n . The k e t o n e s u b s t r a t e i s thought t o c o o r d i n a t e and r e a c t a f t e r h y d r i d e f o r m a t i o n , s i n c e no asymmetric s y n t h e s i s o f a c h i r a l a l c o h o l from a p r o c h i r a l k e t o n e was d e t e c t e d u s i n g ( - ) o c t a n - 2 - o l as s o l v e n t and r e d u c t a n t . ^ On t h e o t h e r hand,RuC£ 2(PPh 3) 3 i s thought t o m e d i a t e t h e c o n c e r t e d i n t r a m o l e c u l a r h y d r i d e t r a n s f e r from c o o r d i n a t e d a l k o x i d e t o c o o r d i n a t e d k e t o n e ^ , and t h i s i s s u b s t a n t i a t e d by t h e r e p o r t o f t h e asymmetric h y d r o g e n a t i o n o f p r o c h i r a l a , 3 - u n s a t u r a t e d k e t o n e s t o c h i r a l s a t u r a t e d k e t o n e s u s i n g t h i s r u t h e n i u m complex and a g l u c o f u r a n o s e d e r i v a t i v e as c h i r a l a l c o h o l d o n o r . ^ Even i n t h e p r e s e n c e o f e x c e s s DMSO and k e t o n e , [NH,]„[RhC£,] i s H 3 D 66 r e d u c e d t o m e t a l i n r e f l u x i n g 2 - p r o p a n o l . However, RhC£(DMSO)(PPh^) 2, 73 21, w i t h 2 - p r o p a n o l does r e d u c e c y c l o h e x a n o n e s ; i n a range o f R h C ^ P P h ^ ^ L complexes,L=PPh 3 was most a c t i v e and L=CO and DMSO, 21, were l e a s t a c t i v e , s u g g e s t i n g t h a t s u l f u r bonded DMSO i s e l e c t r o n w i t h d r a w i n g on R h ( I ) . 1.3.3 O x i d a t i o n R e a c t i o n s The I r and Rh a c i d s 33 and 3_1 ( f i g u r e 1.4) i n h ot aqueous i s o p r o p a n o l c a t a l y z e t h e 0 2 o x i d a t i o n o f DMSO t o ( 0 ) 2 S ( M e ) 2 , a n d O S ( P h ) 2 t o ( 0 ) 2 S ( P h ) ^ . I n t e r m e d i a t e h y d r i d e s , M ( I I I ) - H , a r e c o n s i d e r e d t o be i n v o l v e d i n t h e p r o c e s s . O r g a n i c s u l f i d e s were n o t o x i d i z e d due t o t h e f o r m a t i o n o f s t a b l e R h ( I I I ) s u l f i d e s . James e t a l ^ r e p o r t e d t h a t m i x t u r e s o f H 2 and 0 2 o x i d i z e DMSO w i t h R h C £ 3 ( H 2 0 ) 3 as c a t a l y s t p r e c u r s o r , and a g a i n t h e i n v o l v e m e n t o f a R h ( I I I ) h y d r i d e was s u g g e s t e d . 1.3.4. Homogeneous Asymmetric H y d r o g e n a t i o n The d e s i g n i n g of asy m m e t r i c s y n t h e s i s systems t h a t g i v e p r o d u c t s -16-w i t h a h i g h e n a n t i o m e r i c e x c e s s (e.e.) r e q u i r e s a d e t a i l e d u n d e r s t a n d i n g of t h e f a c t o r s i n v o l v e d i n t h e d i s c r i m i n a t i n g i n t e r a c t i o n o f t h e c h i r a l l i g a n d between t h e two p o s s i b l e e n a n t i o m e r s o f t h e c o o r d i n a t e d p r o c h i r a l o l e f i n - i . e . a d i a s t e r e o t o p i c d i s c r i m i n a t i o n . T h i s i n t e r a c t i o n can be d i v i d e d i n t o t h r e e components: (1) l i g a n d - o l e f i n , (2) m e t a l - o l e f i n , and (3) l i g a n d - m e t a l . A s t u d y o f c i s - P t C & 2 ( S - M P T S O ) ( O l e f i n ) complexes, (R-methyl p - t o l y l s u l f o x i d e i s d e s i g n a t e d as S on c o o r d i n a t i o n ) , where s i m p l e a l k y l and a r y l s u b s t i t u e n t s on t h e o l e f i n were n o t e x p e c t e d t o i n t e r a c t w i t h t h e 78 m e t a l ( i n t e r a c t i o n ( 2 ) ) , was c o n d u c t e d by B o s n i c h e t a l . t o d e t e r m i n e t o what e x t e n t c h i r a l s u l f o x i d e l i g a n d s were c a p a b l e o f d i s t i n g u i s h i n g t h e o l e f i n e n a n t i o m e r s shown i n f i g u r e 1.7. F i g u r e 1.7 Cis-PtC£~(S-MPTSO)(Olefin) D i a s t e r e o m e r s s S c e n t e r on o l e f i n S c e n t e r on s u l f o x i d e R c e n t e r on o l e f i n S c e n t e r on s u l f o x i d e -17-C r y s t a l s o f t h e R^CH^H.^,58, C H ( C H 3 ) 2 , 5 9 , and C ( C H 3 ) 3 > 6 0 , d e r i v a t i v e s were i s o l a t e d i n 100% S f o r m , and a c r y s t a l s t r u c t u r e o f t h e i s o p r o p y l 79 complex _5_9_. showed t h a t t h i s b u l k y group p o i n t e d away from t h e s u l f o x i d e , as i n f i g u r e 1.7. However, on d i s s o l u t i o n , s l o w e q u i l i b r a t i o n of d i a s t e r e o -mers t a k e s p l a c e by o l e f i n d i s s o c i a t i o n t o g i v e S/R r a t i o s w i t h r e s p e c t t o t h e o l e f i n o f 55/44 f o r 58, 66/34 f o r 59 and 100/0 f o r 60 a t 30°C, a l t h o u g h t h e l a t t e r may not have e q u i l i b r a t e d . S t r a n g e l y t h e R^=CH 3, C^H^, and OCH 2CH 3 d e r i v a t i v e s , 61, 62 and 63_, p r e f e r t h e R c o n f i g u r a t i o n i n s o l u t i o n w i t h r a t i o s o f 44/56, 25/75, and 25/75. The R p r e f e r e n c e o f t h e s t y r e n e d e r i v a t i v e , j>2, i s e x p l a i n e d by t h e p h e n y l i n t e r a c t i o n w i t h 8 0 t h e s u l f o x i d e p - t o l y l g roup, c l e a r l y o b s e r v e d i n t h e c r y s t a l s t r u c t u r e . The R o l e f i n i s r o t a t e d 180° from t h e one of f i g u r e 1.7 t o a l l o w t h e a r o m a t i c r i n g s t o f a c e each o t h e r . S i n c e t h e propene d e r i v a t i v e , 61, l i k e s t h e R e n a n t i o m e r , whereas t h e 1-butene s p e c i e s , _58, p r e f e r s t h e S one, t h e a u t h o r s f e e l t h a t because o f s u l f o x i d e r o t a t i o n , t h e c h i r a l p r e f e r e n c e o f t h e o l e f i n i s n e a r l y "washed o u t " . They c o n c l u d e t h a t s u l f o x i d e s a r e poor c h i r a l d i s c r i m i n a t o r s j u d g i n g f r o m t h e v a l u e s n e a r u n i t y o f t h e S/R r a t i o s , b u t i t must be emphasized t h a t t h e s e a r e thermo-dynamic v a l u e s . There may be a l a r g e r k i n e t i c d i s c r i m i n a t i o n as o l e f i n b i n d i n g o c c u r s , as i n t h e c a s e o f 60. The same group d i d n o t i c e a d r a m a t i c k i n e t i c e f f e c t i n v o l v i n g o l e f i n r o t a t i o n . A l t h o u g h s t y r e n e , t - b u t y l e t h y l e n e , and h i g h e r s u b s t i t u t e d 78 81 o l e f i n s , do n o t r o t a t e ' , even a t 50°C, \58, _59 and 61 do o s c i l l a t e i n an odd f a s h i o n ( f i g u r e 1.7) s i n c e R^ cannot pass by t h e b u l k y c i s c h l o r i d e . R o t a t i o n f o r t h e S - o l e f i n i s f ound t o be much e a s i e r ( t h e b a r r i e r i s l o w e r ) t h a n f o r t h e R e n a n t i o m e r because o f t h e l o c a t i o n of t h e m e t h y l and p-t o l y l groups o f t h e s u l f o x i d e i n t h e d i f f e r e n t t r a n s i t i o n s t a t e s f o r -18-78 r o t a t i o n o f t h e two i s o m e r s . I n c o n c l u s i o n , t h i s s t u d y p o i n t s out two t y p e (1) i n t e r a c t i o n s : ' ( i ) b u l k y groups p o i n t away from t h e s u l f o x i d e as i n f i g u r e 1.7 e x c e p t i n t h e c a s e o f ( i i ) t h e o l e f i n -l i g a n d p h e n y l - p h e n y l i n t e r a c t i o n . The l a t t e r s p e c i f i c i n t e r a c t i o n may be i m p o r t a n t f o r t h e c h e l a t i n g d i p h e n y l p h o s p h i n e s 7-13, f i g u r e 1.2, but t h e p r o d u c t i o n o f S - l e u c i n e and S - a l a n i n e i n h i g h e.e. cannot i n v o l v e p h e n y l g r o u p s . I n s t e a d i t appears t o be t h e b u l k y and c h i r a l arrangement of t h e p h e n y l s a l t e r -8 9 82 n a t i v e l y "edge and f a c e " ' ' around t h e rhodium c e n t e r t h a t l e a d s t o t h e i m p o r t a n t t y p e (1) i n t e r a c t i o n . These e f f e c t i v e p h o s p h i n e s l o c k t h e p h e n y l s i n t h i s c o n f i g u r a t i o n by p"^ (8,9,10,11,12), P~N (12?,13) and P^b(7_,8) c h e l a t i o n t o rhodium ( a l l t y p e ( 3 ) i n t e r a c t i o n s ) , a l t h o u g h i t i s not c l e a r how c h e l a t i o n i s p o s s i b l e i n t h e d i h y d r i d e o l e f i n i n t e r m e d i a t e , j>l_ ( f i g u r e 1.5), where t h e l i g a n d i s a l l o w e d o n l y two c o o r d i n a t i o n s i t e s . The i m p o r t a n c e of l o c k i n g t h e c arbons j o i n i n g t h e p h o s p h o r u s atoms i n t o one c o n f o r m a t i o n by u s i n g m e t h y l groups has a l s o 9 been d e m o n s t r a t e d . A n o t h e r c r u c i a l f a c t o r i s t h e a b i l i t y o f s u b s t r a t e s L t o 6^  t o c h e l a t e t o rhodium by t h e o l e f i n and t h e enamide oxygen as 31 83 84 d e m o n s t r a t e d by P nmr , and a c r y s t a l s t r u c t u r e . Thus a t y p e ( 2 ) i n t e r a c t i o n enhances t h e c h i r a l d i s c r i m a t i o n of t y p e ( 3 ) . The e f f e c t o f s o l v e n t and t e m p e r a t u r e on c h i r a l i n d u c t i o n i s p o o r l y u n d e r s t o o d . These p o i n t s , many of w h i c h were r e p o r t e d d u r i n g t h e c o u r s e o f t h e s t u d i e s i n t h i s t h e s i s , c o n f i r m e d our t h o u g h t s t h a t c h e l a t i n g s u l f o x i d e s , 14-16, were p r o m i s i n g l i g a n d s t o t r y on Rh o r I r . I n t e r m e d i a t e _56 ( f i g u r e 1.6), i n h y d r o g e n a t i o n s i n v o l v i n g I r C ^ ^ D M S O ) ^ shows a good t y p e ( 2 ) i n t e r a c t i o n and t h e r e f o r e a c a t a l y s t c o n t a i n i n g c h i r a l l i g a n d s -19-might be q u i t e e f f e c t i v e i f t h e h y d r o g e n a t i o n p r o c e e d s by t h i s r o u t e . 1.4 S u l f o x i d e s as L i g a n d s B o t h t h e s u l f u r and oxygen have a l o n e p a i r o f e l e c t r o n s e n a b l i n g a s u l f o x i d e t o a c t as an a m b i d e n t a t e L e w i s base. S u l f u r c o o r d i n a t i o n 85 3— i s o b s e r v e d o n l y f o r some c l a s s b a c i d s ( p l a t i n u m m e t a l s , [Fe(CN)^(DMSO)] , C r ( 0 ) , M n ( 0 ) , C H 3 + ) and so oxygen a d d u c t s a r e much more common i n i n o r g a n i c 86 87 c h e m i s t r y . The o n l y c a s e s o f l i n k a g e i s o m e r i s m a r e IrC£^(DMSO)^, 35, w i t h IrC£ 3(DMSO) 2(DMSO), 36, and i s o m e r s of complex 34 ( f i g u r e 1.4). A v a r i e t y o f s p e c t r o s c o p i c t e c h n i q u e s r e a d i l y d i s t i n g u i s h e s ; b e t w e e n t h e two modes o f b o n d i n g . The S-0 m u l t i p l e bond caused by d o n a t i o n of oxygen 2p e l e c t r o n s i n t o empty s u l f u r 3d o r b i t a l s c r e a t e s an i n t e n s e a b s o r p t i o n band i n t h e i r . The amount of t h i s p i - b o n d i n g i s d e c r e a s e d on 0 - c o o r d i n a t i o n ( f i g u r e 1.8,1), o r i n c r e a s e d on S - c o o r d i n a t i o n , I I I , as a f u n c t i o n o f t h e m e t a l , M; t h i s change i n s t r e n g t h and l e n g t h o f t h e SO bond i s r e f l e c t e d d r a m a t i c a l l y and c h a r a c t e r i s t i c a l l y i n t h e v a l u e o f v(S0) and r ( S 0 ) . D e s h i e l d i n g o f m e t h y l p r o t o n s a t o t h e SO group o b s e r v e d by nmr i s g e n e r a l l y much g r e a t e r f o r t h e c a s e of s u l f u r t h a n f o r oxygen c o o r d i n a t i o n . E l e c t r o n s p e c t r o s c o p y f o r c h e m i c a l a n a l y s i s (E.S.C.A.) a l s o 88 d i s t i n g u i s h e s I from I I I . 89 The d o r b i t a l s o f a s u l f u r c o o r d i n a t e d t o good b a c k - b o n d i n g groups 2+ 3-s u c h as [Ru(NH 3)^] and [Fe(CN)^] ca n a c c e p t m e t a l d e l e c t r o n s a t t h e expense c f p i e l e c t r o n s from t h e oxygen. The s p e c t r o s c o p i c p r o p e r t i e s of t h e s e a d d u c t s a r e c o n s i s t e n t w i t h an SO bond o r d e r o f o n l y two as i n t h e c a s e of f r e e s u l f o x i d e , I I . The i r - a c c e p t o r a b i l i t y o f v a r i o u s s u l f u r l i g a n d s on M n ( C 0 ) 2 ( C p ) L was o r d e r e d as 0SPh 2>0S~(CH 2) 4 = O S ( C H ^ ) 2 > S P h 2 = i — i 90 S E t 2 = S ( C H 2 ) 4 . Hence, use of s u l f o x i d e s i n s t e a d o f s u l f i d e s i n t h e - 20 -F i g u r e 1.8 (a) The S t r u c t u r a l and S p e c t r o s c o p i c D a t a f o r DMSO Complexes © 0 © © Bonding CH 3 CH 3 CH 3 ^ > - 6 : > = Q. > = 0 : II in i r v ( S 0 ) cm" 1 8 6 0 - 1 0 0 0 ( b ) 1 0 5 5 ( b ) 1 0 6 0 - 1 1 9 8 ( c ) S t r u c t u r a l r ( S 0 ) A 1 . 5 6 - 1 . 5 3 ( b ) 1 . 5 3 1 ( b ) 1 . 5 3 - 1 . 4 1 ( c ) 1 H nmr 6(-CH 3) 3 . 1 - 2 . 6 ( b ) ' ( d ) 2 . 5 7 ( b ) 3 . 1 - 3 . 6 ( c ) ' ( d ) E.S.C.A. (0 -S ) e . v . 365.8±.3 ( e ) 365.0±.3 ( e ) j-s z p 3 / 2 (a) The v a l u e s f o r a l l known DMSO complexes f a l l i n t h e r a n g e s g i v e n . (b) See c h a p t e r s 3,6. (c) See c h a p t e r 4. (d) These r a n g e s e x c l u d e c a s e s o f m a g n e t i c s h i e l d i n g by n e i g h b o u r i n g groups. (e) See r e f e r e n c e 88. » -21-c a t a l y t i c r e a c t i o n s d i s c u s s e d m i ght be e x p e c t e d t o s t a b i l i z e R h ( I ) more e f f e c t i v e l y . S u l f o x i d e s a r e s t r o n g oxygen donor p r o t o n i c bases i n t h e o r d e r : O S ( C H 2 ) 4 = OSBu 2>OS(CH 3) 2>OS(CH 3)Ph>OSPh 2. 9 1 The s p e c t r o c h e m i c a l s e r i e s f o r such l i g a n d s oxygen-bonded t o t r a n s i t i o n m e t a l s p a r a l l e l s 92 t h i s o r d e r i n g . Oxygen-bonded s u l f o x i d e s i n g e n e r a l a r e l a b i l e QT 2+ 94s ( e . g . [ C o ( D M S O ) ( N H 3 ) 5 ] [ C £ 0 4 1 3 7 J and c i s - [ P t ( D M S O ) £ ( D M S O ) ^ 1, and t h i s may be an i m p o r t a n t f a c t o r i n t h e r e a c t i v i t y o f c a t a l y s t s s u c h as RhC& 3(DMSO) 2(DMSO),26, i n DMSO. S u l f u r c o o r d i n a t e d s u l f o x i d e s have a pronounced t r a n s - e f f e c t 95 ( k i n e t i c e f f e c t ) when c o o r d i n a t e d t o P t ( I I ) and t h i s a l s o may be a f a c t o r i n R h ( I ) c a t a l y s i s . However t h e r e i s d i s a g r e e m e n t whether 96 t h e y have a s t r o n g t r a n s - i n f l u e n c e , a thermodynamic e f f e c t ( p r o : r e f e r e n c e s 97,98,99,100,101; mixed v i e w : 102; con: 45, 104, 105, 106). The a f o r e m e n t i o n e d c a t a l y t i c r e d u c t i o n and o x i d a t i o n o f s u l f o x i d e s u s i n g Rh and I r complexes p o i n t out a l i m i t a t i o n o f s u l f o x i d e l i g a n d s . C o n d i t i o n s where such r e d o x r e a c t i o n s o c c u r must be a v o i d e d , e s p e c i a l l y s i n c e t h e s e r e a c t i o n s would d e s t r o y t h e o p t i c a l a c t i v i t y o f l i g a n d s c h i r a l a t t h e s u l f u r . O t h e r w i s e s u l f o x i d e s a r e q u i t e i n e r t t o r a c e -103 m i z a t i o n o v e r a wi d e r a n g e o f c o n d i t i o n s . -22-2. A p p a r a t u s and G e n e r a l E x p e r i m e n t a l P r o c e d u r e s 2.1 I n s t r u m e n t a t i o n S y n t h e t i c p r o c e d u r e s and s o l u t i o n measurements were c o n d u c t e d under a r g o n atmosphere by u s i n g s t a n d a r d S c h l e n k tube t e c h n i q u e s . I n f r a r e d s p e c t r a were r e c o r d e d on a P e r k i n Elmer 457 g r a t i n g s p e c t r o m e t e r . S o l i d s were r u n as m u l l s i n N u j o l o r h e x a c h l o r o b u t a d i e n e between C s l p l a t e s . F o r s o l u t i o n s , 0.1 mm NaCJl c e l l s f i t t e d w i t h serum caps were used w i t h CECi^, CH^CSL^, o r CH^Br^; t h e l a s t two s o l v e n t s have u s e f u l windows f r o m 1200-1000 and 1070-850 cm 1 r e s p e c t i v e l y . {4l NMR s p e c t r a were r e c o r d e d on a V a r i a n T60 o r XL100 s p e c t r o m e t e r u s i n g t e t r a m e t h y l s i l a n e as a r e f e r e n c e w i t h s o l v e n t s CC& 4, C D C ^ J CD2C&2* C ^ C J ^ * ( C D ^ ^ C O and ( C D ^ ^ S O , and u s i n g sodium 2 , 2 - d i m e t h y l - 2 - s i l a p e n t a n o n e -5 - s u l f o n a t e (D.S.S.) w i t h D 2 0 . C o n d u c t i v i t y measurements were made i n n i t r o m e t h a n e a t 25°C u s i n g a Thomas S e r f a s s c o n d u c t i v i t y b r i d g e and a c e l l t h a t a l l o w s p u r g i n g w i t h a r g o n . O p t i c a l r o t a t i o n s were d e t e r m i n e d on a P e r k i n Elmer 141 p o l a r i m e t e r a t room t e m p e r a t u r e u s i n g a one d e c i m e t e r m i c r o c e l l w i t h a 1 ml volume. Gas c h r o m a t o g r a p h i c a n a l y s e s were c o n d u c t e d on a t e m p e r a t u r e p r o -grammable H e w l e t t P a c k a r d 5750 w i t h a t h e r m o c o n d u c t i v i t y d e t e c t o r . One e i g h t h i n c h columns packed w i t h "Durapak" s u p p l i e d by C h r o m a t o g r a p h i c S p e c i a l i t i e s were used f o r o l e f i n s w i t h l e s s t h a n 9 c a r b o n s , and columns w i t h 10% Carbowax 20M on 60-80 mesh Chromosorb W f o r u n s a t u r a t e d k e t o n e s and a l d e h y d e s . C,H,N, and CI a n a l y s e s were p e r f o r m e d by Mr. P. Borda o f t h i s d e partment. -23-2.2 Gas-Uptake A p p a r a t u s The c o n s t a n t p r e s s u r e a p p a r a t u s , ( f i g . 2 . 1 ) , was used f o r k i n e t i c and f o r s t o i c h i o m e t r i c e x p e r i m e n t s . A f l e x i b l e g l a s s s p i r a l t u b e con-n e c t e d a c a p i l l a r y manometer D a t t a p C t o a p y r e x two necked r e a c t i o n f l a s k e q u i p p e d w i t h a d r o p p i n g s i d e arm b u c k e t . The r e a c t i o n f l a s k was t h e r m o s t a t t e d i n an o i l b a t h and shaken by means of a p i s t o n - r o d and d r i v e n by an o f f s e t w heel c o n n e c t e d t o a Welch v a r i a b l e speed e l e c t r i c motor. The manometer D c o n t a i n e d n - b u t y l p h t h a l a t e and was c o n n e c t e d t o a gas m e a s u r i n g b u r e t t e c o n s i s t i n g o f a mercury r e s e r v o i r E and a 10 m l p i p e t t e o f known d i a m e t e r . The gas b u r e t t e was c o n n e c t e d v i a an Edwards h i g h vacuum m e t e r i n g v a l v e , M, t o t h e g a s - h a n d l i n g p a r t of t h e a p p a r a t u s . T h i s p a r t c o n s i s t e d o f a m e r c u r y manometer F, gas i n l e t Y, and vacuum pump G. The c a p i l l a r y manometer and gas b u r e t t e were t h e r m o s t a t e d @ 25°C i n a p e r s p e x w a t e r b a t h . T h e r m o s t a t i n g of t h e o i l b a t h and w a t e r b a t h was c o n t r o l l e d by Jumo t h e r m o - r e g u l a t o r s and Merc t o Merc r e l a y c o n t r o l c i r -c u i t s , w i t h h e a t i n g a c c o m p l i s h e d by a 40 w a t t e l o n g a t e d l i g h t b u l b . The b a t h s were w e l l s t i r r e d , and t h e o i l b a t h i n s u l a t e d . The t e m p e r a t u r e was h e l d t o ±0.05°C. A v e r t i c a l mounted c a t h e t o m e t e r f o l l o w e d t h e gas u p t a k e i n t h e b u r e t t e , and t i m e was r e c o r d e d w i t h a L a b c h r o n 1400 t i m e r . 2.3 Gas-Uptake E x p e r i m e n t a l P r o c e d u r e I n a t y p i c a l g a s - u p t a k e experiment, 5 ml o f s o l v e n t was p l a c e d i n t h e 25 ml r e a c t i o n f l a s k . Weighed . s u b s t r a t e s were added t o t h e s o l v e n t d i r e c t l y and weighed c a t a l y s t v i a t h e b u c k e t a f t e r t h e s o l v e n t was degassed and t h e f l a s k f i l l e d w i t h r e a c t a n t gas. D e g a s s i n g f o r DMA s o l v e n t was e f f e c t e d by pumping on t h e s o l v e n t w h i l e s h a k i n g . F o r h i g h e r vapour p r e s s u r e s o l v e n t s t h e f r e e z e thaw under s t a t i c vacuum t e c h n i q u e was employed. F o r b o t h Figure 2 . 1 . Constant pressure gas-uptake apparatus 25-methods a d e g a s - r e f i l l c y c l e was r e p e a t e d t h r e e t i m e s . I n i t i a l l y t h e r e a c t i o n f l a s k was f i l l e d w i t h r e a c t a n t gas a t a p r e s s u r e somewhat l e s s t h a n t h a t r e q u i r e d f o r t h e e x p e r i m e n t , a t 0, ( f i g . 2.1). The t a p s C and p. were t h e n c l o s e d and t h e r e a c t i o n f l a s k c o m p l e t e w i t h s p i r a l d i s c o n n e c t e d from 0 and a t t a c h e d t o H and t h e s h a k e r r o d . The whole system up t o t a p C was t h e n pumped down w i t h t a p s H, K, L , J and M open. R e a c t a n t gas was a d m i t t e d t o t h i s p a r t o f t h e system a t a p r e s s u r e g r e a t e r t h a n t h a t i n t h e r e a c t i o n f l a s k b u t l e s s t h a n t h a t d e s i r e d f o r t h e r e a c t i o n . A f t e r t h e r m a l e q u i l i b r a t i o n o f t h e r e a c t i o n f l a s k was a t t a i n e d (-15 m i n . ) , t a p C was opened and t h e p r e s s u r e of t h e whole system a d j u s t e d t o t h e d e s i r e d r e a c t i o n p r e s s u r e by i n t r o d u c t i o n of gas t h r o u g h Y. S h a k i n g of t h e r e a c t i o n v e s s e l was t h e n done t o s a t u r a t e t h e s o l v e n t w i t h gas a t t h e r e a c t i o n p r e s s u r e (-5 m i n . ) . An e x p e r i m e n t a l r u n was t h e n s t a r t e d by d r o p p i n g t h e c a t a l y s t b u c k e t , s t a r t i n g t h e s h a k e r , c l o s i n g t a p s K and L and s t a r t i n g t h e t i m e r . Gas-uptake was i n d i c a t e d by a d i f -f e r e n c e i n o i l l e v e l s i n manometer D. The manometer was b a l a n c e d by a d m i t t i n g gas i n t o the b u r e t t e t h r o u g h t h e m e t e r i n g v a l v e M. C o r r e s p o n d i n g changes i n m e r c u r y l e v e l s i n t h e p i p e t t e N were t r a n s l a t e d t o volume changes of gas r e a c t e d , per u n i t t i m e . D i f f u s i o n c o n t r o l o f t h e r e a c t i o n s was e l i m i n a t e d by u s i n g f a s t s h a k i n g r a t e s and a l a r g e i n d e n t e d r e a c t i o n f l a s k . 2.4 M o d i f i c a t i o n s o f Gas-Uptake A p p a r a t u s 2.4.1 Gas I n l e t B u b b l e r : A mercury b u b b l e r was c o n n e c t e d t o t a p Y as shown i n f i g u r e 2.1 so t h a t gas c o u l d be c o n t i n u o u s l y c i r c u l a t e d p a s t i n l e t Y a t a p r e s s u r e o f 1000 mm. The advantages o f t h i s s ystem o v e r -26-s i m p l y c o n n e c t i n g a gas c y l i n d e r t o t a p Y a r e t h a t p r e s s u r e b u i l d u p s r e s u l t i n g i n t h e u p s e t of manometer F a r e a v o i d e d , t h e p u r g i n g o f t h e i n l e t t u b i n g i s e a s i e r , and t h e gas i n l e t s ystem t o t a p M can be m a i n t a i n e d a t a maximum p o s i t i v e p r e s s u r e d u r i n g an u p t a k e e x p e r i m e n t . However, t a p Y must be opened c a r e f u l l y t o a v o i d s u c k i n g m e r c u r y i n t o t h e system. 2.4.2 T e l f o n S t o p c o c k s ; S i n c e t h e s e c t i o n o f t h e a p p a r a t u s t o t h e r i g h t o f t a p M i n f i g u r e 2.1 i s n o r m a l l y under a p r e s s u r e g r e a t e r t h a n 1 atm, K o n t e s t e f l o n t a p s a r e s u p e r i o r t o g r e a s e d ones. They a l s o a l l o w e a s i e r m e t e r i n g o f gases when s e t t i n g t h e p r e s s u r e i n F. However s p r i n g -l o a d e d , g r e a s e d t a p s a r e b e s t f o r H, K, L, J because t h e y a r e more r a p i d l y opened and c l o s e d t h a n t e f l o n ones and t h e y do n o t a l t e r t h e volumes of t h e gas b u r e t t e s , w h i c h t e f l o n ones do when th e y a r e opened and c l o s e d . 2.4.3 C o n v e n i e n t Ampoules: S e v e r a l o f t h e complexes i n t h i s work were s e n s i t i v e i n t h e s o l i d s t a t e t o hydrogen so t h a t t h e b u c k e t i n t h e u p t a k e p r o c e d u r e c o u l d not be used. I n s t e a d a b u l b was blown on a g l a s s t u b e , a c o n s t r i c t i o n was p l a c e d i n t h e stem and a g l a s s r o d was m e l t e d o n t o t h e bottom o f t h e b u l b t o weaken i t . The l a t t e r t r i c k was e s s e n t i a l t o g u a r a n t e e b r e a k a g e o f t h e ampoule. A f t e r b e i n g t e s t e d f o r l e a k s , t h e b u l b was f i l l e d w i t h sample and t h e n sand, and t h e n s e a l e d o f f under a r g o n u s i n g t h e h y d r o g e n a t i o n b a l l o o n t o r e g u l a t e t h e p r e s s u r e as i n f i g u r e 2.2. These p r e c a u t i o n s m i n i m i z e gas u p t a k e when t h e ampoule b r e a k s . The g l a s s -27-F i g u r e 2.2 w H y d r o g e n a t i o n B a l l o o n Rubber vacuum t u b i n g G l a s s r o d Sample G l a s s tube Sand S e a l - o f f Hook formed d u r i n g s e a l - o f f s h o u l d be s e a l e d o f f i n t h e shape of a hook ( f i g u r e 2.2) so t h e ampoule can be hooked t o t h e b u c k e t d r o p p e r o f t h e u p t a k e f l a s k . 2.4.4 Low Temperature Uptake V e s s e l : Rhodium m e t a l w h i c h formed i n many of t h e e x p e r i m e n t s t o be d e s c r i b e d can o n l y be removed from g l a s s by u s i n g l a r g e q u a n t i t i e s o f ^ S O ^ a t 150°C. I t was t h e r e f o r e n e c e s s a r y t o d e s i g n an u p t a k e v e s s e l t h a t c o u l d be f i t t e d w i t h a d i s p o s a b l e t e s t t u b e ( f i g u r e 2 . 3). The gauze p r e v e n t s t h e b u c k e t o r ampoule from i n t e r -f e r i n g w i t h t h e s t i r r e r . T h i s assemblage was immersed i n a c o n s t a n t t e m p e r a t u r e b a t h b u t t h e r e s t o f t h e u p t a k e p r o c e d u r e i s t h e same. Gas u p t a k e s a t t e m p e r a t u r e s l o w e r t h a n ambient were measured u s i n g t h i s a p p a r a t u s . 2.5 Work Up o f H y d r o g e n a t i o n s o f I t a c o n i c A c i d The r e a c t i o n s o l u t i o n s were f i r s t pumped t o d r y n e s s a t 0.2 mm p r e s s u r e . The r e s i d u e was d i s s o l v e d i n 25 ml o f 10% NaOH s o l u t i o n and f i l t e r e d t h r o u g h -28-F i g u r e 2.3 Low Temperature Uptake V e s s e l R e a c t i o n S o l v e n t S t a i n l e s s S t e e l Gauze o r F l a t t e n e d G l a s s Rod -29-C e l i t e . The f i l t r a t e was e x t r a c t e d w i t h 25 m l c h l o r o f o r m t o remove any f r e e s u l f o x i d e and the n made j u s t a c i d i c w i t h 10% HC£. The p r o d u c t was e x t r a c t e d from t h e aqueous phase w i t h d i e t h y l e t h e r (5x25 ml) and d r i e d o v e r MgSO^. The e t h e r was removed t o y i e l d p r o d u c t and s u b s t r a t e . 2.6 S t a r t i n g M a t e r i a l s 2.6.1 Gases: P u r i f i e d hydrogen and C. P. grade c a r b o n monoxide were o b t a i n e d from t h e Matheson Gas Co., w h i l e p u r i f i e d n i t r o g e n and a r g o n were from t h e Ca n a d i a n L i q u i d A i r L t d . Hydrogen was pas s e d t h r o u g h a Deoxo Hydrogen P u r i f i e r b e f o r e use. Arg o n and N 2 were n o r m a l l y p a s s e d t h r o u g h a CaC& 2 d r y i n g t ower. When more r i g o r o u s anhydrous c o n d i t i o n s were r e q u i r e d , a m i x t u r e o f f r e s h ^2^5 an<^ m o l e c u l a r s i e v e s was employed. 2.6.2 S o l v e n t s : S p e c t r a l grade s o l v e n t s were n o r m a l l y used w i t h o u t f u r t h e r p u r i f i c a t i o n and were s t o r e d where a p p r o p r i a t e o v e r m o l e c u l a r s i e v e s (BDH, t y p e 5A). They were vacuum-degassed b e f o r e u s e . Where n e c e s s a r y , t h e f o l l o w i n g d r y i n g s t e p s were p e r f o r m e d . A l c o h o l s were r e f l u x e d and t h e n d i s t i l l e d f rom t h e i r c o r r e s p o n d i n g magnesium a l k o x i d e s under N 2- E t h e r and THF were s t i r r e d i n , and t h e n d i s t i l l e d f r o m , sodium/benzophenone under N^. DMSO was d r i e d w i t h KOH and t h e n vacuum d i s t i l l e d . DMA s u p p l i e d by F i s h e r was s t i r r e d w i t h CaH 2 o v e r n i g h t and t h e n vacuum d i s t i l l e d . 2.6.3 S i l v e r S a l t s : AgSbF^ and AgPF^ were s u p p l i e d by A l p h a C h e m i c a l s or C a t i o n i c s L t d . Ex p o s u r e o f t h e s e s a l t s t o a i r ( m o i s t u r e ) and l i g h t was m i n i m i z e d . These compounds, even as s o l i d s , e t c h g l a s s r a p i d l y . 2.6.4 Rhodium S t a r t i n g M a t e r i a l s : R h o d i u m ( I I I ) t r i c h l o r i d e was o b t a i n e d as t h e t r i h y d r a t e from J o h n s o n , M a t t h e y L i m i t e d . L i t e r a t u r e methods were -30-1 2 used f o r t h e s y n t h e s i s o f [RhC£(cyclooctene)^] 2 , [RhC£(C 2H ) ^ \ , 3 4 5 [RhC£(l,5-cyclooctadiene)] 2 , [RhC i l ( C O ) 2 ] 2 , and [RhC£(norbornadiene) ] , ex c e p t f o r t h e l a s t compound where t h e i n g r e d i e n t s were s t i r r e d , n o t shaken; t h e method r e p o r t e d by Osborn e t a l f o r the n o r b o r n a d i e n e complex r e s u l t e d i n a low y i e l d . The p r e p a r a t i o n s o f [ R h ( n o r b o r n a d i e n e ) - ] P F , and [Rh(l,5-cyclooctadiene)„]• z o I SbF^ were adapt e d from one r e p o r t e d by Osborn, e t a l . / 2.6.4.1 [ R h ( n o r b o r n a d i e n e ) 2 ] P F ^ : To a s t i r r e d , degassed s u s p e n s i o n o f 0.43 g [RhC£(NBD)] 2 i n 20 ml a c e t o n e were added 0.51 g AgPFg d i s s o l v e d i n 1 ml o f a c e t o n e . The orange s o l u t i o n was t h e n f i l t e r e d f rom the AgC£, and 0.21 m l n o r b o r n a d i e n e were added. Red c r y s t a l s p r e c i p i t a t e d as t h e volume was r e d u c e d t o 4 m l . P r e c i p i t a t i o n was co m p l e t e d by a d d i n g 4 ml e t h e r . The c r y s t a l s were r e c o v e r e d by d e c a n t i n g o f f t h e s o l v e n t , w a s h i n g w i t h e t h e r and d r y i n g i n v a c u o . Y i e l d 0.6 g ( 7 5 % ) . A n a l . C a l c d f o r R h C 1 4 H 1 6 P F 6 : C , 3 8 . 9 1 ; H,3.73. Found: C,39.09; H.3.93. 2.6.4.2 [Rh(cyclooctadiene)„]SbF,: AgSbF, (0.27 g) i n THF was added Z — D O t o 0.19 g o f [RhC£(C0D)] 2 i n 4 ml o f THF; t h e method o f 2.6.4.1 was t h e n f o l l o w e d . Y i e l d , 75%. C a l c d f o r RhC, ,H 0 /SbF,: C,34.62; H,4.36. Found: I D 44 o C,34.66; H,4.28. 2.6.5 I r i d i u m S t a r t i n g Complexes: H y d r a t e d I r C l ^ (56% I r ) was p u r c h a s e d f r o m E n g e l h a r d I n d . [NH 4] 2[IrC£g] and I r C J l ^ were s u p p l i e d by J o h n s o n , M a t t h e y L i m i t e d . The " I n o r g a n i c S y n t h e s e s " p r e p a r a t i o n f o r [IrC£(cyclo-o c t e n e ) 2 ] 2 was f o l l o w e d . 1 2.6.6 S u l f o x i d e s : A p a r t f r o m t h e d r y i n g o f t h e DMSO, no p u r i f i c a t i o n o f t h e s u l f o x i d e s was p e r f o r m e d . S u p p l i e r s were: A l d r i c h f o r t e t r a m e t h y l e n e - 3 1 -s u l f o x l d e (TMSO), Eastman f o r d i p h e n y l s u l f o x i d e (DPSO), and KaK Labs f o r n - p r o p y l (NPSO) and m e t h y l p h e n y l (MPSO) s u l f o x i d e . S u l f i d e s were s u p p l i e d by KaK Labs ( 2 , 5 - d i t h i a h e x a n e ) and N u t r i t i o n a l B i o c h e m i c a l s C o r p o r a t i o n ( L - m e t h i o n i n e ) . ( S ) - ( + ) - 2 - M e t h y l b u t y l - ( S , R ) - m e t h y l s u l f o x i d e and (-)-DIOS were p r e p a r e d by R. M c M i l l a n . ( R ) - t - B u t y l p - t o l y l s u l f o x i d e , and ( S ) - o - t o l y l - p - t o l y l s u l f o x i d e were k i n d l y d o n a t e d by B. B o s n i c h and H. Boucher (U. o f T o r o n t o ) . 2.6.6.1 ( R ) - ( + ) - M e t h y l - p - t o l y l s u l f o x i d e ,18. The method o f p r e -p a r a t i o n has been p u b l i s h e d . ^ The s y n t h e t i c r o u t e , w h i c h a l s o a p p l i e s t o t h e o t h e r s u l f o x i d e s c h i r a l a t s u l f u r , i s o u t l i n e d i n scheme ( 2 . 1 ) . 18 An e f f e c t i v e method f o r removing t h e y e l l o w i m p u r i t y t h a t c o n t a m i n a t e s t h e c r u d e MPTSO (10 g) i s a S o x h l e t e x t r a c t i o n u s i n g 50 ml o f ACS hexanes, t h e s o l v e n t used f o r r e c r y s t a l l i z a t i o n o f MPTSO. The y e l l o w i m p u r i t y i s l e f t i n t h e t h i m b l e and when t h e hexane i s a l l o w e d t o c o o l , 25° w h i t e c r y s t a l s o f pur e s u l f o x i d e s e p a r a t e ; [ a ] D =148° ( C = l , a c e t o n e ) . T h i s a v o i d s t h e r e p e t i t i v e use o f a c t i v a t e d c h a r c o a l s u g g e s t e d o r i g i n a l l y . -32-A r e c e n t r e p o r t shows t h a t h i g h e r y i e l d s and c l e a n e r p r o d u c t m i x t u r e s can be a c h i e v e d by r e p l a c i n g t h e G r i g n a r d r e a g e n t i n scheme (2.1) w i t h o rganocopper l i t h i u m r e a g e n t s . 2.6.6.2 ( R , R ) - ( l , 2 ) - B i s ( p - t o l y l s u l f i n y l ) e t h a n e , 14. The f o l l o w i n g 13 p r e p a r a t i o n was based on t h e s k e t c h y c o m m unication o f M i s l o w e t a l . They succeeded i n c o u p l i n g two m e t h y l s u b s t i t u t e d e n a n t i o m e r i c a l l y p u r e s u l f o x i d e s by t h e copper promoted o x i d a t i v e c o u p l i n g of t h e a - c a r b a n i o n s t o y i e l d t h e o p t i c a l l y p u r e s u b s t i t u t e d e t h a n e , r e a c t i o n ( 2 . 2 ) . 9 STRONG^ 9 C u C I 2 ^ r W "I J§f^C H 3 B A S 6 > 0 K H 2 S — ^ | - C H 2 j -18 67 (2.2) R e c e n t l y t h e methane a n a l o g u e has been made w i t h 100% o p t i c a l p u r i t y 14 by r e a c t i n g t h e a - c a r b a n i o n 67_ w i t h t h e m e n t h y l e s t e r , 66. Method: The s t r o n g b a s e , l i t h i u m d i e t h y l a m i d e was p r e p a r e d by a d d i n g d r o p w i s e a s t a n d a r d i z e d s o l u t i o n 1 " ' o f n - b u t y l l i t h i u m (34 m l o f 1.37 M i n hexane) t o 4.8 m l N H E t 2 c o o l e d t o -78°C under d r y A r . A f t e r p r e c i p i t a t e d base was d i s s o l v e d by a d d i n g 10 m l d r y THF, t h e s o l u t i o n was t r a n s f e r r e d u s i n g an a i r t i g h t s y r i n g e t o a 125 m l e q u a l i z i n g f u n n e l a t t a c h e d t o a 250 ml two n e c k f l a s k c o n t a i n i n g 6.5 g ( R ) - p - t o l y l m e t h y l s u l f o x i d e i n 150 m l d r y THF a t -78°C under A r . The b ase was added p o r t i o n w i s e . A f t e r a g i t a t i n g t h e s o l u t i o n f o r 20 m i n u t e s , 6.8 g o f anhydrous CuC£ 2 ( p r e p a r e d by r e f l u x i n g CuC£ 2.2H 20 w i t h S0C£ 2) F i g u r e 2.4 (a) 100 MHz H nmr spectrum of ( R , R ) - ( l , 2 ) - b i s ( p - t o l y l s u l f i n y l ) -e thane, 14. (b) S i m u l a t e d spectrum o f methylene r e g i o n . -34-was added w i t h t h e r e s u l t i n g s p e c t a c u l a r f o r m a t i o n of a b l u e c o l o u r ( presumably C u ( I ) ) and LiC£. A f t e r s h a k i n g f o r a n o t h e r 15 m i n u t e s a t -78°C, t h e s o l u t i o n was warmed t o room t e m p e r a t u r e and s a t u r a t e d w i t h oxygen f o r 15 m i n u t e s . A f t e r h y d r o l y s i s (450 ml of 10% t ^ S O ^ ) , t h e m i x t u r e was e x t r a c t e d (1x150, 3x50 m l CHCil^) , and t h e combined e x t r a c t s were washed w i t h 200 m l d i l u t e NH^OH, 2x100 m l H 20, d r i e d w i t h K 2 C ° 3 ' f i l t e r e d , and e v a p o r a t e d t o a brown o i l . T h i s was added t o a column c o n t a i n i n g 500 ml of s i l i c a g e l / C H C ^ . 300 ml CHC£ 3 e l u t e d a brown band w i t h no o p t i c a l a c t i v i t y . 600 m l o f 5% EtOH i n CHC£ 3 y i e l d e d t h e p r o d u c t and a brown band mixed t o g e t h e r . Brown i m p u r i t y was a l s o l e f t on t h e column. The d e s i r e d f r a c t i o n s were e v a p o r a t e d t o a brown o i l . R e c r y -s t a l l i z a t i o n f rom h o t t o l u e n e y i e l d e d 0.7 g (11%) y e l l o w i s h c r y s t a l s 25 [ a ] D =220°. R e c r y s t a l l i z a t i o n from CHC£ 3/heptane y i e l d e d w h i t e c r y s t a l s (0.5g) [a ] J 5=+270° ( l i t e r a t u r e : +278°, C=0.044, C H 3 O H ) 1 3 . A n a l . C a l c d f o r C, ,HL o S o 0 o : 0,62.60; H,5.90. Found: C,62.70; H,5.92. nmr (CDC£„) 67.35 ( m , 8 , a r o m a t i c ) ; 2.42 ( s , 6 , C H 3 ) ; F i g u r e 2.2 shows a s i m u l a t e d s p e c t r u m o f t h e m e t h y l e n e r e s o n a n c e s (an AA'BB' p a t t e r n ) based on p a r a -m e t e r s from r e f e r e n c e 17: 6 =2.75, 6 =3.31, J . . ^J.,.,,^3.4, J . =J. ^,=-12.0, A B AA BB ' AB A B J ^=J ^ =11.2 Hz. A g r e e m e n t ' w i t h t h e o b s e r v e d s p e c t r u m i s good. AtS A Jo 2.6.5.3 ( M e s o ) - l , 2 - b i s ( m e t h y l s u l f i n y l ) ethane o r 2 , 5 - d i t h i a h e x a n e - 2 , 5 -d i o x i d e , 68. MSE: I n v i e w o f t h e s m a l l y i e l d o f PTSE, 1A_, from t h e p r e v i o u s p r e p a r a t i o n , i t was d e s i r a b l e t o use a more r e a d i l y o b t a i n a b l e compound f o r e x p l o r a t o r y e x p e r i m e n t s . MSE, J58, can be s y n t h e s i z e d i n a p u r e c h i r a l 18 f o r m but t h e p r o c e d u r e i s l a b o r i o u s and t h e y i e l d v e r y low. Thus a non-c h i r a l i s o m e r of MSE was chosen. -35-The o r i g i n a l p r e p a r a t i o n , i n v o l v i n g t h e o x i d a t i o n o f 2,5 d i t h i a h e x a n e 19 20 w i t h H^O^, y i e l d s a m i x t u r e o f s u l f i d e s , s u l f o n e s , and s u l f o x i d e s . ' The meso and d l forms o f t h e d i s u l f o x i d e can be s e p a r a t e d by r e p e a t e d 19 20 21 f r a c t i o n a l r e c r y s t a l l i z a t i o n s . ' ' • A c l e a n e r p r e p a r a t i o n o f t h e h i g h e r m e l t i n g d i a s t e r e o m e r (75% y i e l d ) i s t h e a c i d c a t a l y z e d oxygen 19 exchange from DMSO t o t h e s u l f i d e . T h i s i s o m e r was thought t o be j-|22 ., , 18 • . , 21 , . d l u n t x l more r e c e n t work , and a c r y s t a l s t r u c t u r e showed i t t o be meso. Method: A m i x t u r e o f 10.4 g of 2 , 5 - d i t h i a h e x a n e , 20 m l o f DMSO, and 0.18 g of 12 M HC£ was s t i r r e d and h e a t e d a t 100° o v e r n i g h t i n an Er l e n m e y e r f l a s k . A f t e r c o o l i n g , t h e p r e c i p i t a t e was f i l t e r e d , washed w i t h 3 m l benzene, and r e c r y s t a l l i z e d t h r e e t i m e s f r o m EtOH. Y i e l d , 9 g. A n a l . C a l c d f o r C 4 H 1 0 S 2 0 2 : C > 3 1 - 1 3 ; H,6.53. Found: C.31.01; H,6.70. m.p. 163-164°C. nmr (CDC£ ) . 52.63 ( S , 6 , C H 3 ) ; 3.10 (m,4,CH 2); see f i g u r e 2.5. 2.6.6.4 ( S ) - M e t h i o n i n e - ( S ) - s u l f o x i d e , 16: A s i m p l e s t e r e o s p e c i f i c o x i d a t i o n o f m e t h i o n i n e t o 1 6 ( f i g u r e 1.3), by u s i n g c h l o r o a u r i c a c i d 23 (HtAuCJt.^]) as t h e s t o i c h i o m e t r i c o x i d a n t has r e c e n t l y been communicated. The a s y m m e t r i c i n d u c t i o n may a r i s e from a p r e f e r r e d c h e l a t e d c o n f i g u r a t i o n o f t h e s u l f i d e on t h e g o l d . Four a t t e m p t s a t r e p r o d u c i n g t h e i r p r o c e d u r e u s i n g m e t h i o n i n e s u p p l i e d by N u t r i t i o n a l B i o c h e m i c a l s Co. o r Eastman Kodak L t d . and HlAuCic-^] .xH^O ( a p p r o x i m a t e l y 31% Au) s u p p l i e d by A l p h a C h e m i c a l s o r B.D.H. C h e m i c a l Co. r e s u l t e d i n p r o d u c t s c o n t a i n i n g l a r g e amounts o f c o n t a m i n a n t s o f c o l l o i d a l g o l d o r g o l d s a l t s t h a t were not r e a d i l y removed i n p u r i f i c a t i o n a t t e m p t s . Method: A s t o i c h i o m e t r i c amount o f ( S ) - m e t h i o n i n e (0.33 g) i n 20 ml of H^O was added t o a s t i r r e d s o l u t i o n o f HfAuCJt-^] (0.8 g) i n 20 m l of t^O. jl ( m e t h y l s u l f I n y l ) e t h a n e . -37-Th e orange s o l u t i o n went t u r b i d , and t h e n f a d e d t o y e l l o w w i t h t h e d e p o s i t i o n o f some g o l d , a l t h o u g h i t was r e p o r t e d t h a t t h e s o l u t i o n 23 s h o u l d s t a y c l e a r f o r h o u r s . A f t e r 30 m i n u t e s of s t i r r i n g , a t t e m p t s t o p r e c i p i t a t e t h e p r o d u c t by a d j u s t i n g t h e pH t o 4 (aqueous KOH o r NH^OH) and a d d i n g a c e t o n e and 23 e t h a n o l , r e s u l t e d i n t h e p r e c i p i t a t i o n o f c o l l o i d a l g o l d , a p u r p l e i n o r g a n i c compound, and t h e p r o d u c t , 16. P u r p l e c o n t a m i n a n t s were s t i l l p r e s e n t a f t e r t h i s s o l i d m i x t u r e was r e d i s s o l v e d i n H^O, f i l t e r e d t h r o u g h c e l i t e , and r e p r e c i p i t a t e d . Y e l l o w g o l d compounds can be e x t r a c t e d from t h e o r i g i n a l y e l l o w r e a c t i o n m i x t u r e by r e p e t i t i v e t r e a t m e n t s w i t h e t h e r (8x20 m l ) . However p u r p l e c o n t a m i n a n t s r e a p p e a r when t h e pH i s a d j u s t e d t o 4. I f t h e y e l l o w r e a c t i o n s o l u t i o n i s l e f t f o r 16 h o u r s most o f t h e g o l d p r e c i p i t a t e s . The s o l u t i o n was t h e n b r o u g h t t o pH 4 (aqueous KOH), f i l t e r e d t h r o u g h c e l i t e and t h e n added t o 100 ml o f a c e t o n e - e t h a n o l ( V / V = l ) . The p r o d u c t , a w h i t e powder was c o l l e c t e d by f i l t r a t i o n , 25 washed w i t h a c e t o n e and d r i e d i n vacuo: [ c ] ^ =+60° (C=0.8, IN HC&; 23 l i t e r a t u r e g i v e s +132°). R e p r e c i p i t a t i o n from d i d n o t a l t e r 25 [ a ] ^ =+60°. (Due t o t h e h i g h s u r f a c e t e n s i o n o f t h e s e s o l u t i o n s a i r b u b b l e s had t o be removed from t h e p o l a r i m e t e r m i c r o c e l l w i t h a s y r i n g e ) The nmr i n D^O i s c o n s i s t e n t w i t h t h e s t r u c t u r e o f JL6. 62.71 ( s , 3 , C H 3 ) ; 3.03 (m,2,S-CH 2); 2.30 (m,2,C-CH 2-C); 3.81 ( t , l , N - C H ) . A n a l . C a l c d f o r C 5 H 1 1 ° 3 S N : c ' 3 6 - 3 4 ; H » 6 - 7 1 ; N,8.47. Found: C.19.03; H,3.46; N,4.37. T h i s impure compound was not s t u d i e d f u r t h e r . -38-3. Mixed S u l f o x l d e - T r i p h e n y l p h o s p h i n e C a t i o n i c Complexes of Rhodium(I)  3.1 S y n t h e s i s and S p e c t r o s c o p i c P r o p e r t i e s . 3.1.1. I n t r o d u c t i o n C a t a l y s t s d e r i v e d from t h e complexes [RhCdiene)]^]A, _5_3,- (diene=l,5-c y c l o o c t a d i e n e (COD), n o r b o r n a d i e n e (NBD); L= n e u t r a l donor l i g a n d ; A= a n i o n ) a r e known t o be u s e f u l f o r t h e h y d r o g e n a t i o n o f a v a r i e t y o f u n s a t u r a t e d o r g a n i c s u b s t r a t e s . 1 The s e l e c t i v i t y and e f f i c i e n c y o f such r e a c t i o n s ( e . g . , h y d r o g e n a t i o n v s . i s o m e r i z a t i o n ) a r e l i k e l y dependent on t h e n a t u r e of L, t y p i c a l l y a t e r t i a r y p h o s p h i n e o r a r s i n e , and suggest • t h a t c a t a l y t i c s e l e c t i v i t y m i g ht be f u r t h e r c o n t r o l l e d by u s i n g mixed 1 2 l i g a n d p r e c u r s o r s , [ R h ( d i e n e ) L L ]A, 69_. Complexes such as J53 a r e t y p i c a l l y p r e p a r e d 1 by t h e a d d i t i o n o f e x c e s s L t o [RhC£(diene)]^, a p r o c e d u r e n o t a p p l i c a b l e t o t h e s y n t h e s i s o f 69; b u t we have found t h a t 1 2 t h e l a t t e r a r e e a s i l y o b t a i n e d from [ R h ( d i e n e ) L ( a c e t o n e ) ] A , 70. I n t h i s c h a p t e r t h e u t i l i t y o f 70_ as a s y n t h e t i c p r e c u r s o r f o r [ R h ( d i e n e ) ( P P h ^ ) ( s u l f o x i d e ) ] A s p e c i e s w i l l be d e s c r i b e d . An a p p r e c i a t i o n 1 2 + of t h e e l e c t r o n i c and s t e r i c r e q u i r e m e n t s of t h e [ R h ( d i e n e ) L L ] c a t i o n and t h e p r o p e r t i e s of s u l f o x i d e d e r i v a t i v e s ( e . g . , 0-vs S-bonding) i s e s s e n t i a l f o r an e v a l u a t i o n o f such compounds as p o t e n t i a l c a t a l y s t s . D u r i n g t h e c o u r s e o f t h i s work, C r a b t r e e r e p o r t e d t h e use o f [Rh(COD)-+ 3 ( P P h g ) ( p y ) ] , _71> f o r t h e h y d r o g e n a t i o n of 1 - a l k y n e s t o 1 - a l k e n e s , and + 4 5 t h e use o f [ I r ( C O D ) ( p h o s p h i n e ) ( p y ) ] f o r t h e r e d u c t i o n o f o l e f i n s . ' 3.1.2. E x p e r i m e n t a l S y n t h e t i c p r o c e d u r e s and s o l u t i o n measurements were con d u c t e d under an a r g o n atmosphere. V i b r a t i o n a l d a t a a r e r e p o r t e d i n cm 1 . The p h e n y l -39-r e s o n a n c e s o f t h e PPh^ complexes come a t 67-8 i n t h e nmr but t h e d a t a f o r t h i s r e g i o n y i e l d l i t t l e i n f o r m a t i o n and a r e not t a b u l a t e d . P r e p a r a t i o n o f t h e Complexes 3.1.2.1. [ R h ( d i e n e ) ( P P h J ( a c e t o n e ) ] A ; diene=COD,NBD;A=PF , SbF,: To 3 b b a C H 2 C £ 2 s o l u t i o n (15 ml) o f P P h 3 (0.409 g, 1.56 mmol) and [RhC£(C0D)] 2 (0.384 g, 0.774 mmol) was added d r o p w i s e , w i t h s t i r r i n g , A g P F ^ (0.395 g, .1.56 mmol) d i s s o l v e d i n a c e t o n e (10 m l ) ; f l o c c u l e n t w h i t e AgC£ p r e c i p i t -a t e d . A f t e r 10 min t h e b r i g h t orange s o l u t i o n was f i l t e r e d under a r g o n and c o n c e n t r a t e d t o 5 ml. G r a d u a l a d d i t i o n o f e t h e r gave orange c r y s t a l s w h i c h were c o l l e c t e d , washed w i t h e t h e r , and d r i e d . A d d i t i o n a l p r o d u c t was o b t a i n e d upon f u r t h e r c o n c e n t r a t i o n , and a d d i t i o n o f e t h e r . The f r a c t i o n s were combined, d i s s o l v e d i n an equivolume a c e t o n e / d i c h l o r o -methane m i x t u r e , and c r y s t a l l i z e d by t h e a d d i t i o n o f e t h e r ( y i e l d = 8 0 % ) . S o l v e n t o f c r y s t a l l i z a t i o n ( C H 2 C £ 2 ) , u s u a l l y found i n samples so o b t a i n e d , was removed by p r o l o n g e d e v a c u a t i o n . The NBD compound was p r e p a r e d s i m i l a r l y . 3.1.2.2..[Rh(COD)(PPh 0)(DMS0)]PF,: DMSO (21 u£, 0.29 mmol) and J b [ R h ( C O D ) ( P P h 3 ) ( a c e t o n e ) ] P F & (0.20 g, 0.29 mmol) were d i s s o l v e d i n C H 2 C £ 2 (3 ml) and s t i r r e d f o r 15 min. A d d i t i o n o f e t h e r gave y e l l o w c r y s t a l s w h i c h were r e c r y s t a l l i z e d f r o m d i c h l o r o m e t h a n e / e t h e r , washed w i t h e t h e r , and d r i e d i n vacuo f o r s e v e r a l h o u r s . A l l o f t h e s u l f o x i d e complexes ( t a b l e 3.1) were s i m i l a r l y p r e p a r e d from t h e a p p r o p r i a t e a c e t o n e p r e c u r s o r . Y i e l d s were t y p i c a l l y 80-90%. T a b l e s 3.2-3.4 l i s t t h e i r and nmr d a t a f o r t h e s e compounds. T a b l e 3.1 A n a l y t i c a l d a t a f o r the r h o d i u m ( I ) complexes Complex D e c o m p o s i t i o n point(°C) c %C Found C a l c u l a t e d A n a l y s i s Found %H C a l c u l a t e d [ R h ( C O D ) ( P P h . ) ( a c e t o n e ) ] P F . j 6 148-150 51.53 51.49 4.89 4.92 [ R h ( N B D ) ( P P h 0 ) ( a c e t o n e ) ] P F , 3 0 145-150 50.71 50.93 4.41 4.43 [ R h ( N B D ) ( P P h 3 ) ( a c e t o n e ) ] S b F 6 145-148 44.84 44.77 3.97 3.89 [Rh(COD)(PPh 0)(DMSO)]PF, J 0 179-180 48.67 48.28 4.80 4.77 [Rh(NBD)(PPh.)(DMSO)]SbF, J 0 139-140 42.02 42.04 3.70 3.79 [Rh(COD)(PPh Q)(TMSO)]PF, J 6 173-175 49.46 49.87 4.66 4.88 [ R h ( C O D ) ( P P h 0 ) ( N P S O ) ] P F * J 0 119-121 48.43 48.37 5.22 5.26 [Rh(COD)(PPh 3)(MBMSO)]PFg 57-59 50.75 51.07 5.50 • 5.50 [Rh(COD)(PPh.)(MPSO)]PF J° J 0 96-98 50.58 50.62 4.68 4.50 [Rh(COD)(PPh 0)(MPTSO)]PF r 3 6 137-139 52.56 52.85 5.00 4.83 [Rh(COD)(PPh Q)(TBPTSO)]PF, -> D 140-143 54.75 54.55 5.20 5.30 a The c a l c u l a t e d a n a l y s i s i n c l u d e s 0.7 CH 2C1 2; nmr shows approx. 0.6 CH 2C1 b The c a l c u l a t e d a n a l y s i s i n c l u d e s 0.4 C H 2 C1 2; nmr shows approx. 0.5 CH 2C1 c U n c o r r e c t e d , i n a i r . - 4 1 -T a b l e 3.2 I n f r a r e d d a t a (cm ) f o r [ R h ( d i e n e ) ( P P h ) L ] P F c o m p l e x e s -L v(CO) o r v(SO) - ' - P r ( C H 3 ) -'- Av(SO) -ac e t o n e 1658 s,br ac e t o n e (NBD) 1663 s,br DMSO 958 s,br (947 s,br) 992s (983s) 108 DMSO (NBD) 922 s , b r (945 s,b r ) 983s (985s) 110 TMSO 935 s,br (938 s , b r ) 84 TBPTSO 947 s,br (940 s) 97 NPSO 942 s,br (947 s,b r ) 70 L v(900-1000 cm bands) Av -MBMSO 937m, 967s ( 9 6 5 s , b r ) 65 MPSO 958s, 942s (959s, 945sh) 91, 105 MPTSO 957s, 939s (959s, 943sh) 88, 104 a. D i e n e = COD, u n l e s s i n d i c a t e d o t h e r w i s e . b_ N u j o l m u l l s ; v a l u e s i n p a r e n t h e s e s f o r C E ^ B ^ s o l u t i o n s . c_ s = s t r o n g , b r = b r o a d , m = medium, sh = s h o u l d e r cl D e f i n e d as [v ( S 0 ) f o r f r e e l i g a n d - v(S0) c o o r d i n a t e d l i g a n d ] i n CH^Br e^  D e f i n e d as v( S 0 ) f o r f r e e l i g a n d - v i n s o l u t i o n . -42-Table 3.3 1H nmr data^ 3- 1 for [Rh(COD)(PPh,)L]PF, c o m p l e x e s a t 35°C. J 0 5 d i e n e ( o l e f l n l c ) L «P \ 6 .coordinated L acetone 5.20 3.AO 2.05(s , C H 3 - ) ( d ) DMSO 5.15 3.15 2.20(s,S-CH3) NPSO 5.13 3.17 2.50(m,S-CH 2),1.58(tq,-CH 2-), 0.90(t,CH 3-). MPSO 5.18 3.18 2.38(s,S-CH3) MPTSO 5.17 3.17 2.38 (s , S-CH3) , 2.38 (s , p-Cl^-) TBPTSO 5.18 3.15 0.98(s,S-C(CH 3) 3),2.37(s,p-CH 3-) MBMSO 5.15 3.17 2.22(s,s-CH ) ^ e ) , 1.2(m,methine), 0.80(m,CH3CH2+C-CH3). (a) Measured i n pptn (downfield positive) from TMS i n CDCH^i phenyl resonances omitted; s=singlet, m=multiplet, t = t r i p l e t , tq=triplet of quartets. (b) TMSO complex i n s u f f i c i e n t l y soluble. (c) Appear as broad s i n g l e t s ; Hp and H L = o l e f i n i c protons trans to PPhj and L respectively; methylene resonances appear as multiplets at 61.8-2.5. (d) This i s the po s i t i o n of free acetone. (e) S-CH, resonance obscured. T a b l e 3.4 1 H nmr d a t a ^ f o r [Rh(NBD) (PPh„)L]PF Complexes O D S o l v e n t T°C L K ( 3 . 3 ) 6 d i e n e ( o l e f i n i c ) h. l\ \ \ 6 d i e n e (methine) 6 d i e n e (CH 2) 6L CDC£ 3 35 (b) a c e t o n e 4.4 4.4 4.4 3.7? 4.2-3.8 1.4 2 . 3( ? ) 2 ( C D 3 ) 2 C O 35 acet o n e 4.5 4.5 4.5 4.5 4.0 1.43 2.05 (CD 3 ) 2 C O -60 ac e t o n e o . i ( d ) 5.4 3.2 4.6 4.1 3.9 1.34 2.10 CDCJ>3 35 DMSO 3.9 3.9 4.4 4.1? 3.9 1.35 2.45 CDC£ 3 -30 DMSO 0.06 ( d> 5.3 3.2 4.5 4.3 4.0 1.4 2.55 C D 2 C £ 2 -50 A s P h 3 0.2<d> 4.2 4.7 4.4 4.5 4.0 1.45 7.4-7.0 I 00 I (a) Measured i n ppm d o w n f i e l d from TMS; p h e n y l r e s o n a n c e s o m i t t e d . (b) T h i s g i v e s a complex, c o n c e n t r a t i o n dependent spectrum. These a r e n o t f i r m a s s i g n m e n t s , There i s a l s o an u n i d e n t i f i e d s p e c i e s w i t h 6 ( o l e f i n i c ) = 6 . 2 - 5 . 9 , 6(methine)=3.15. (c) S i g n a l may be due t o [ R h ( N B D ) ( a c e t o n e ) 2 ] + . (d) E r r o r i n K d e t e r m i n a t i o n e s t i m a t e d t o be ±40%. -44-3.1.2.3. [Rh(COD)(DMSO-d 6) 2]SbF 6: To a s u s p e n s i o n o f [RhC£ (COD) ] 2 (0.24 g, 0.47 mmol) i n 15 ml of a c e t o n e was added w i t h s t i r r i n g AgSbF^ (0.34 g, 0.97 mmol) d i s s o l v e d i n 5 m l of a c e t o n e . A f t e r 5 min th e AgC£ was f i l t e r e d f rom t h e y e l l o w s o l u t i o n under A r . A f t e r t h e a d d i t i o n o f DMSO-d, (0.18 m l , 2.4 mmol), t h e s o l u t i o n was c o n c e n t r a t e d t o 2 m l . E t h e r O (10 ml) was g r a d u a l l y added u n t i l t h e s o l u t i o n was al m o s t t u r b i d ; a d d i t i o n o f 20 u £ DMSO-d^ a t t h i s p o i n t i n d u c e d s l o w f o r m a t i o n o f y e l l o w c r y s t a l s . Y i e l d was 50%. A n a l . C a l c d f o r R h S b F g S ^ C ^ D ^ H ^ : C, 23.43; H+D, 4.42. Found: C, 23.43; H, 4 . 1 2 . i r , v(S0) 950s; v(Rh-0) 443s, 435s; 6(CD 3) 1020s; p (CD„) 832s, 767s. n m r ( C D C O 63.93 (m, 4 ,-C=C-H); 2.40(m,4,CH ) 1.65 (m,4,CH 2). P r o p e r t i e s o f t h e DMSO ad d u c t : i r , v ( S 0 ) 950s; v(Rh-0) 473s, 465s; 6(CH 3) 1327s, 1320s; P r ( C H 3 ) 985s, 970s. nmr(CDCJ!,3) 62. 75 ( s , 6 ,DMS0) ; d i e n e peaks as above; c f . f i g u r e 3.01; The c o r r e c t s t o i c h i o m e t r y o f r e a c t a n t s used f o r t h i s p r e p a r a t i o n i s e s s e n t i a l s i n c e e x c e s s DMSO caused o i l i n s t e a d o f c r y s t a l p r e c i p i t a t i o n . The use o f impure AgSbF^ r e s u l t e d i n d e c o m p o s i t i o n o f t h e r e a c t i o n s o l u t i o n t o a g r e e n s o l u t i o n , p o s s i b l y c o n t a i n i n g R h(II) formed by an o x i d a t i o n r e a c t i o n . No p r o d u c t c o u l d be i s o l a t e d when THF was used as t h e s o l v e n t , presumably because t h e l a t t e r i s a s t r o n g e r 0-donor t h a n a c e t o n e . 3.1.2.4. [Rh(NBD) ( P P h 3 ) ( p y ) ] S b F 6 : P y r i d i n e (12 0.15 mmol) was added t o [ R h ( N B D ) ( P P h 3 ) ( a c e t o n e ) ] S b F ^ (0.096 g, 0.13 mmol) i n 1 ml C H 2 C £ 2 > A d d i t i o n o f e t h e r t o t h i s v e r y a i r - s e n s i t i v e s o l u t i o n y i e l d s y e l l o w m i c r o -c r y s t a l s . A n a l . C a l c d f o r R h S b P N F 6 C 3 0 H 2 g : C, 46.66; H, 3.65; N, 1.81. Found: C, 46.82; H, 3.80; N, 1.54. i r , c h a r a c t e r i s t i c p y r i d i n e v i b r a t i o n a t 1603 m. - 4 5 -3.1.2.5. [ R h ( d i e n e ) ( P P h 3 ) ( A s P h 3 ) ] P F 6 ; diene=COD, NBD: [ R h ( C O D ) ( P P h 3 ) a c e t o n e ] P F g ( 3 3 mg, 0.05 mmol) and A s P h 3 ( 1 5 mg, 0.05 mmol) were mixed i n 0.5 ml of CDC£ 3 f o r an nmr sample. Orange c r y s t a l s of t h e CDC£ 3 s o l v a t e d e p o s i t e d a f t e r one day ( 7 0 % ) . A n a l . C a l c d f o r RhP„F,AsC.,H,„.CDC£„: C, 51.72; H, 4.05; C£, 10.18. Found: C, 51.80; z o 44 4z -j H, 3.91; C£, 1 0 . 4 9 . i r , c h a r a c t e r i s t i c bands of A s P h 3 : 330s, 325s and 315s; bands of P P h 3 : 1103s, 1098s, 527s, 511s. nmr(CDC£ 3) 64.87(m,1.7, C=C-H); 4.30(m,1.6,C=C-H); 4.68(m,0.3,C=C-H), 4.53(m,0.3,C=C-H); 2.67-1.95 (m,8,CH 2). An i d e n t i c a l s p e c t r u m was o b t a i n e d i n CCI^^CO a t -50°C ( f i g u r e 3.02). The NBD a n a l o g u e p r e c i p i t a t e s f rom CDC& 3 but can be o b s e r v e d by nmr i n CD 2C£ 2- nmr(CD 2C£ 2,35°C) . 64.53(m,4,C=C-H); 4.03(m,2,methine); I . 56(m,2,CH 2) . nmr (CD 2CJ> 2 ,-50°C) , 64. 71 (m, 1. 5, C=C-H) ; 4.22(m,1.5,C=C-H) ; 4.50(m,0.5,C=C-H); 4.36(m,0.5,C=C-H); 3 . 9 8 ( m , 2 > m e t h i n e ) ; 1.42(m,2,CH 2). See f i g u r e 3.03. 3.1.2.6. [ R h ( d i e n e ) ( P P h 0 ) (CO) J P F , ; diene=C0D, NBD: The complexes j z o  p r e c i p i t a t e d when e t h e r was added t o C O - s a t u r a t e d C H 2 C £ 2 s o l u t i o n s o f t h e a c e t o n e c a t i o n s . A n a l . C a l c d f o r t h e COD d e r i v a t i v e : C, 50.18; H, 4.21. Found: C, 50.25; H, 4.40. i r ( N u j o l ) , v(C0) 2029; ir(CHC£ 3), v(C0) 2050, 1983. nmr (CDC£ 3, 35°C), 5.56(m,4,C=C-H); 3.0-2.2(m,8,CH ). See f i g u r e 3.04. A n a l . C a l c d f o r t h e NBD d e r i v a t i v e : C, 49.26; H, 3.52. Found: C, 49.36; H, 3.75. i r ( N u j o l ) , . v(C0) 2080sb. ir(CHC£ 3), v(C0) 2080s, 2045s. nmr (CDC£ 3, 35°C, under A r o r CO) 64.23(m,4,C=C-H); 3.76(m,2,methine); 1.42(m,2,CH 2). nmr(CDC£ 3, -30°C, under CO) 4.07(m,4,C=C-H), 3.74(m,2,methine), 1.40 (m,2,CH 2), see f i g u r e 3.05. nmr(CDC£ 3 , -20°C, under A r ) 65.7(m,0.3,C=C-H), 4.50(m,0.3,C=C-H), 4.36(m,0.3,C=C-H), 4.08(m,3,C=C-H); 3.74(m,2,methine); F i g u r e 3.01. 60 MHz H nmr spectrum o f [Rh(COD)(DMSO) ]SbF i n CDC£ (a)! (b) I o I ppm F i g u r e 3.05. 100 MHz 1 H nmr spectrum o f [Rh(NBD)(PPh ) ( a c e t o n e ) ] P F under CO i n CDC«,3 a t a) -30°C, (b) 35°C. 7 5 ppm 3 1 Figure 3.06. 100 MHz "4 nmr spectrum of [Rh(COD)(PPh.)(acetone)]PF +DI0S in CDC£ at 35°C. Impurity at 6375, 1.2 is ether. F i g u r e 3.07. 60 MHz H nmr spectrum o f [ R h ( N B D ) ( P P h . ) ( a c e t o n e ) ] P F +DI0S a t 35°C i n CDCJ> . 5 ppm 3 F i g u r e 3.08. 100 MHz -""H nmr spec t r u m o f [Rh(NBD) (PPh.) ( a c e t o n e ) ]PF,+DI0S i n CDC£ 3 a t -50°C. -54-1.42(m,2,CH2). A gas u p t a k e i n DMA, u s i n g t h e ampoule t e c h n i q u e , y i e l d e d a CO/Rh s t o i c h i o m e t r y of 1.9. 3.1.2.7. [ R h ( d i e n e ) ( P P h 3 ) ( D I O S ) ] P F 6 ; diene=COD,NBD: A t t e m p t s a t i s o l a t i o n o f t h e s e complexes f a i l e d . I n s i t u systems u s i n g one DIOS per Rh a c e t o n e c a t i o n gave t h e f o l l o w i n g s p e c t r a . F o r t h e COD d e r i v a t i v e : nmr(CDC£ 3),DIOS: 64.19-3.95(m,2,methine); 3.1-2.8(m,4,CH 2"S); 2.45 ( s , 1 . 9 , C H 3 - S ) , 2.41(s,3.2,CH 3-S), 2.39(s,0.9,CH 3-S); 1.42-1.39(m,6, CH 3-C). nmr(CDC£ 3) ,, COD: 65. 39 (m, 2 ,C=C-H),3. 23 (m, 2, C=C-H) ; 2.58-2.30 (m,4,CH 2), 2.2-1.8(m,4,CH 2), r e f e r t o f i g u r e 3.06. F o r t h e NBD d e r i v a t i v e : nmr(CDCJ> 3, 35°),DIOS: 64.4-3.9 (m, 2 , m e t h i n e ) ; 2.95(m,broad,4,S-CH 2); 2 . 5 5 ( s , b r o a d , 6 , S - C H 3 ) ; 1.30(s,6,C-CH 3).NBD: 4.13 (m,4,C=C-H); 3.82(m,2,methine); 1.30(m,2,CH 2). nmr(CDC& 3,-50°C)>DI0S: 4.4-3.9(m,2,methine); 3.1-2.8l(m,4,CH^-S);2.54(s,broad,CH^-S); 1.36 (m,6,CH 3-C). NBD: 5.22(m,2,C=C-H), 3.29(m,2,C=C-H); 4.34(m,0.5, [ R h N B D ( P P h 3 ) 2 ] + ) ; 3.99(m,2,methine), 1.24(m,2,CH ). F i g u r e 3.07 and f i g u r e 3.08 show nmr s p e c t r a a t 35° and -50°, r e s p e c t i v e l y . 3.1.3. R e s u l t s and D i s c u s s i o n I n f r a r e d d a t a f o r a l l o f t h e complexes r e p o r t e d h e r e show t h a t t h e a n i o n s a r e u n c o o r d i n a t e d , s i n c e o n l y t h e c h a r a c t e r i s t i c bands of PF^ and SbF^ a r e o b s e r v e d a t 840vs, 560s, and 658vs, 290s cm r e s p e c t i v e l y . ^ ' ' ' 3.1.3.1. A c e t o n e Complexes 8—12 F a c i l e c l e a v a g e o f t h e c h l o r i d e b r i d g e o f [RhCJt ( d i e n e ) J 2 by a L e w i s base L \ can g i v e a monomeric d e r i v a t i v e [RhC£(diene)L 1] , _7_2, but e x c e s s r e a c t a n t ( e s p e c i a l l y where L 1 = p h o s p h i n e o r a r s i n e ) i n a p o l a r s o l v e n t may d i s p l a c e t h e l a b i l e c h l o r i d e f o r m i n g [ R h ( d i e n e ) L 1 ^ ] ^ . 1 3 ' 1 4 -55-The r e m o v a l of c h l o r i d e as a s i l v e r s a l t from 7_2 f a c i l i t a t e s t h e c o o r d i n a t i o n o f a c e t o n e , a weak and e a s i l y d i s p l a c e d l i g a n d 1 " ' ; r e a c t i o n s 3.1 and 3.2. [RhC£(diene)] 2 + 2 L 1 -> 2[RhCJl(diene)L, 1] (3.1) 72. [•RhCjKdienejL 1] + AgA ^ (3.2) CH 2C£ 2/acetone [ R h ( d i e n e ) L 1 ( a c e t o n e ) ] A + AgC£ 70 u • * i - J T, • 10,11 12 8,9 A l t h o u g h a v a r i e t y o f l i g a n d s s u c h as amines , a r s i n e s , p hosphmes , g h a l i d e s , e t c . , have been used t o e f f e c t r e a c t i o n 3.1, we have c o n f i n e d our i n i t i a l i n v e s t i g a t i o n t o t r i p h e n y l p h o s p h i n e d e r i v a t i v e s . T h i s p r o v i d e s a s y n t h e t i c a d v a n t a g e , as c r y s t a l l i n e samples of t h e a c e t o n e c a t i o n , 70, a r e e a s i l y o b t a i n e d when L ^ P P h ^ , as a r e t h e s u b s e q u e n t l y d e r i v e d s u l f o x i d e complexes. T a b l e 3.1 g i v e s m i c r o a n a l y t i c a l d a t a . The i n s i t u s y n t h e s i s o f o t h e r r e a c t i v e a c e t o n e complexes i s r e a d i l y a c c o m p l i s h e d . S o l i d s t a t e i r measurements on _70 show v(C0) a t VL660 cm 1 ( t a b l e 3 . 2 ) , c o n s i s t e n t w i t h a c o o r d i n a t e d a c e t o n e moi e t y . 1 " ' The extreme l a b i l i t y o f t h e a c e t o n e l i g a n d i s d e m o n s t r a t e d by t h e r e p l a c e m e n t of t h i s band by one o f t h e f r e e l i g a n d a t 1710 cm 1 d u r i n g t h e r e c o r d i n g o f s o l u t i o n i r i n C H 2 C £ 2 . F u r t h e r m o r e , o n l y a s i n g l e t a t 62.05 f o r f r e e l i g a n d i s p r e s e n t i n t h e "'"H nmr s p e c t r a ( t a b l e 3.3, f i g u r e 3.09), and t h e r e i s no e v i d e n c e o f c o o r d i n a t e d a c e t o n e . I n c o n t r a s t , w i t h t h e c a t i o n i c complexes [ M ( C 0 ) ( a c e t o n e ) ( P P h ^ ) 2 ] , M=Rh, I r , t h e c o o r d i n a t e d a c e t o n e s i n g l e t a p p e ars a t 61.6-1.8, due t o d i a m a g n e t i c s h i e l d i n g by t h e c i s p h o s p h i n e s ( r e f e r e n c e s F i g u r e 3.09. 60 MHz H nmr spectrum o f [ R h ( C O D ) ( P P h 3 ) ( a c e t o n e ) ] P F & i n CDC£ a t 35°C. -57-13, 15, and see b e l o w ) , and f r e e a c e t o n e i s d e t e c t e d o n l y a f t e r s e v e r a l h o u r s . The d i s s o c i a t i o n of a c e t o n e s u g g e s t s t h e f o r m a t i o n of f o r m a l l y t h r e e - c o o r d i n a t e s p e c i e s . A l t h o u g h s u c h s p e c i e s a r e u s u a l l y c o n s i d e r e d t o be s o l v a t e d f o u r - c o o r d i n a t e s q u a r e p l a n a r ( t h e weak b i n d i n g of 17 C H C ^ t° P t ( I I ) has been d e m o n s t r a t e d ) , e v i d e n c e has been p r e s e n t e d g f o r t h r e e - c o o r d i n a t e i n t e r m e d i a t e s i n r e a c t i o n s of d , o r g a n o m e t a l 18 19 s ystems. ' U n s y m m e t r i c a l T- and Y- shaped c o n f i g u r a t i o n s were 19 f a v o u r e d and t h e f o r m e r , o r s o l v a t e d f o u r - c o o r d i n a t e s p e c i e s , c o u l d a c c o u n t f o r t h e i n e q u i v a l e n c e o f t h e COD o l e f i n i c p r o t o n s i n t h e p r e s e n t system. Two s e t s of r e s o n a n c e s a t <55.2 and 3.4 a r e o b s e r v e d i n CDCJt.^ s o l u t i o n ( t a b l e 3.3, f i g u r e 3.09). A s i n g l e o l e f i n i c s i g n a l i s o b s e r v e d f o r t h e NBD a n a l o g u e but a t -50°C th e two s e t s a r e f r o z e n out (see t a b l e 3.4, f i g u r e s 3.10-3.12, and b e l o w ) . The p r o b a b i l i t y o f a 3 - c o o r d i n a t e s p e c i e s i s f u r t h e r s u b s t a n t i a t e d by t h e i s o l a t i o n o f t h e T-shaped 3-20 c o o r d i n a t e complex, [RhXPPh^)^]ClO^ , c h a r a c t e r i z e d a f t e r our work was c o m p l e t e d ; i n t e r a c t i o n o f t h e v a c a n t Rh s i t e w i t h a p h e n y l c a r b o n , as o b s e r v e d i n t h e c r y s t a l s t r u c t u r e a n a l y s i s , c o u l d a l s o e x p l a i n t h e d i s -s o c i a t i o n of a c e t o n e from _70_. However a t t e m p t s t o i s o l a t e such a s p e c i e s by r e p r e c i p i t a t i o n o f 7_0_ i n C ^ C J t ^ o n a d d i n g e t h e r f a i l e d , s i n c e r e a c t i o n 1 2 3.3 i s f a v o u r e d , L = PPh 3 > L =acetone, and t h e l e a s t s o l u b l e complex, 2 [ R h ( d i e n e ) L 1 L 2 ] + ^ 3 ' 3 ^ [ R M d i e n e ) ! 1 ] 4 " + [ R h ( d i e n e ) L 2 ] + (3.3) 13 [ R h ( d i e n e ) ( P P h ^ ^ l P F ^ , c r y s t a l l i z e s i n s t e a d o f t h e p o s s i b l e t h r e e --61-c o o r d i n a t e one. Hence samples of 70_ must be r e c r y s t a l l i z e d i n t h e p r e s e n c e o f e x c e s s a c e t o n e . When pure [Rh(COD) (PPh_) ( a c e t o n e ) ]PF,. i s d i s s o l v e d i n CDC£ 0, J O 3 a s m a l l amount of d i s p r o p o r t i o n a t i o n (K^ 3<0.01) o c c u r s and i s s i g n a l l e d by o l e f i n r e s o n a n c e s of v e r y low i n t e n s i t y o f t h e b i s p h o s p h i n e c a t i o n • 13 (at 64.6) and b i s a c e t o n e c a t i o n ( a t 64.0) i n t h e nmr, f i g u r e 3.09; e q u i l i b r i u m 3.3 must be s l o w on t h e nmr t i m e s c a l e because b r o a d e n i n g of t h e COD i n e q u i v a l e n t o l e f i n i c r e s o n a n c e s i s not o b s e r v e d a t 35°C. E q u i l i b r i u m 3.3 i s a l s o s l o w and l i e s v e r y f a r t o the l e f t f o r a l l t h e [ R h ( C O D ) ( P P h ^ ) ( s u l f o x i d e ) ] + complexes s y n t h e s i z e d , as w e l l as f o r a l l th e mixed l i g a n d complexes, [ R h ( C O D ) ( p h o s p h i n e ) ( a m i n e ) ] P F ^ , r e c e n t l y 21 + p r e p a r e d by C r a b t r e e e t a l . t h r o u g h t h e r e a c t i o n o f [Rh(COD)(phosphine)^] and [ R h ( C O D ) ( a m i n e ) 2 ] + v i a r e a c t i o n 3.3. I n c o n t r a s t , t h e new c r y s t a l l i n e complex, [ R h ( C O D ) ( P P h ^ ) ( A s P h ^ ) ] + , was s y n t h e s i z e d , and found t o d i s p r o p o r t i o n a t e e x t e n s i v e l y a c c o r d i n g t o e q u i l i b r i u m 3.3 i n CDCil^ a t 35°; i n t h i s c a s e o l e f i n i c r e s o n a n c e s due t o [ R h ( C O D ) ( P P h 3 ) 2 ] + and [ R h ( C O D ) ( A s P h 3 ) 2 ] + 1 3 were c l e a r l y o b s e r v e d a t 64.53 and 4.68 r e s p e c t i v e l y , and a K 3 3=0.10±0.04 c o u l d be c a l c u l a t e d . About t h e same c o n s t a n t i s o b t a i n e d from t h e nmr spec t r u m of a sample i n ( C D 3 ) 2 C O , measured a t -50°C ( f i g u r e 3.02). We a r e c o n f i d e n t t h a t t h e [ R h ( d i e n e ) L 2 J + s p e c i e s o b s e r v e d i n t h e nmr s p e c t r a o f [ R h ( C O D ) ( P P h 3 ) ( A s P h 3 ) ] + , and t h e mixed l i g a n d complexes w i t h diene=NBD t o be d e s c r i b e d , r e s u l t from e q u a t i o n (3.3) and a r e n o t i m p u r i t i e s c o - p r e c i p i t a t e d w i t h t h e d e s i r e d complex. I t would be t o o g r e a t a c o i n c i d e n c e t h a t s u c h i m p u r i t i e s a r e p r e s e n t always i n e q u i m o l a r -62-amounts i n s o l u t i o n ( t o a g r e e w i t h t h e nmr d a t a ) and t h e s o l i d s t a t e ( t o g i v e t h e c o r r e c t a n a l y s i s and g i v e good l o o k i n g c r y s t a l l i n e s a m p l e s ) , e s p e c i a l l y c o n s i d e r i n g t h e g r e a t d i f f e r e n c e i n s o l u b i l i t y o f t h e two d i s p r o p o r t i o n a t i o n p r o d u c t s i n c e r t a i n c a s e s - e.g. [ R h ( C O D ) ( P P h 3 ) 2 ] + i s much l e s s s o l u b l e i n C H 2 C £ 2 t h a n [ R h ( C O D ) ( a c e t o n e ) 2 ] + . 4 R e c e n t l y C r a b t r e e and M o r r i s have p r e s e n t e d good e v i d e n c e t h a t t h e i n t e r m o l e c u l a r l i g a n d exchange r e a c t i o n (3.3) i n v o l v i n g i r i d i u m complexes 1 2 w i t h L =phosphine, L = p y r i d i n e , ahd diene=COD, pr o c e e d s by way of t h r e e c o o r d i n a t e i n t e r m e d i a t e s . The d i s p r o p o r t i o n a t i o n r e a c t i o n and t h e proposed t h r e e - c o o r d i n a t e b e h a v i o u r o f [Rh(COD)(PPh„)(acetone)]PF, d i s c u s s e d i n 3 b t h i s t h e s i s s u p p o r t t h e g e n e r a l i z a t i o n t h a t t h e f o r m a t i o n o f 3 - c o o r d i n a t e i n t e r m e d i a t e s a l l o w s t h e l i g a n d exchange r e p r e s e n t e d by e q u i l i b r i u m (3.3) t o o p e r a t e . I f L 1 i s a h a l i d e , t h e n l i g a n d — b r i d g e d , f i v e - c o o r d i n a t e i n t e r m e d i a t e s have been p o s t u l a t e d t o be t h e s o u r c e o f such l i g a n d exchange r e a c t i o n s , a l t h o u g h t h r e e - c o o r d i n a t e ones have sometimes been i m p l i c a t e d . " ' " 8 The NBD d e r i v a t i v e s g i v e more complex s p e c t r a because d i s p r o p o r t i o n -a t i o n v i a e q u a t i o n ( 3 . 3 ) , p o s s i b l y i n v o l v i n g 3 - c o o r d i n a t e i n t e r m e d i a t e s , i s always o b s e r v e d , and 5 - c o o r d i n a t e f l u x i o n a l s p e c i e s a r e a l s o b e l i e v e d t o be p r e s e n t a t room t e m p e r a t u r e . E v i d e n c e f o r t h e e x i s t e n c e o f s u c h s p e c i e s i s p r o v i d e d by v a r i a b l e t e m p e r a t u r e nmr as f o l l o w s . The o l e f i n i c r e s o n a n c e s a s s i g n e d t o [ R h ( N B D ) ( P P h 3 ) L ] + a r e e q u i v a l e n t a t 35°C but can be f r o z e n t o i n e q u i v a l e n c e a t low t e m p e r a t u r e ( t a b l e 3.4, f i g u r e s 3.10-3.14). P r e v i o u s _ ,. 17,18,22,23 . , . , , . . , j j s t u d i e s i n v o l v i n g n e u t r a l and c a t i o n i c • m i x e d donor complexes o f I r and Rh have d e m o n s t r a t e d t h a t NBD complexes undergo r e a r r a n g e m e n t s -63-•22 more r e a d i l y t h a n COD a n a l o g u e s . F i v e c o o r d i n a t e i n t e r m e d i a t e s , even c o n t a i n i n g w e a k l y bonded c h l o r i n a t e d hydrocarbons"*"^, appear t o be i n v o l v e d ; r e c e n t l y a f i v e c o o r d i n a t e p y r i d i n e adduct o f a ( d i e n e ) ( p e n t a n - 2 , 4 - d i o n a t o ) r h o d i u m ( I ) complex was i s o l a t e d by e m p l o y i n g a 24 n o r b o r n a d i e n e w i t h e l e c t r o n w i t h d r a w i n g s u b s t i t u e n t s . A l s o r e l e v a n t i s t h a t f o r [ R h ( d i e n e ) L ] + complexes, n may be 3 f o r NBD, but o n l y 2 f o r 13 COD systems. The s t r o n g e r fr-backbonding p r o p e r t i e s o f NBD have been 23 i n v o k e d t o r a t i o n a l i z e t h e r e a c t i v i t y p a t t e r n . T here a r e a l s o peaks i n t h e 35° s p e c t r a ( f i g u r e s 3.10 and 3.13) t h a t can be a s s o c i a t e d w i t h t h e d i s p r o p o r t i o n a t i o n p r o d u c t s o f e q u i l i b r i u m ( 3 . 3 ) . Resonances t h a t do not appear t o be broadened o r averaged by ex-change, a r e o b s e r v e d f o r [Rh(NBD) (V"Ph^)^]+ i n t h e spec t r u m o f [ R h ( N B D ) ( P P h 3 ) ( D M S O ) ] + , and [ R h ( N B D ) ( a c e t o n e ) 2 ] + i n t h e spectrum o f [ R h ( N B D ) ( P P h 3 ) ( a c e t o n e ) ] + (see t a b l e 3.4). Resonances o f t h e o t h e r p r o d u c t s a r e masked by o t h e r peaks. Thus, l i k e t h e COD d e r i v a t i v e s , t h e s e complexes appear t o exchange l i g a n d s v i a e q u a t i o n (3.3) s l o w l y on t h e nmr t i m e s c a l e , and a g a i n 3 - c o o r d i n a t e s p e c i e s may be i n v o l v e d . V a l u e s of K^ 3 3 ^ can be e s t i m a t e d (see t a b l e 3.4) from t h e low t e m p e r a t u r e s p e c t r a ( f i g u r e s 3.12, 3.14) where t h e p r o d u c t s o f e q u i l i b r i u m (3.3) a r e c l e a r l y v i s i b l e . I n summation, three-, four-, and f i v e - c o o r d i n a t e complexes may be g e n e r a t e d when [ Rh (NBD) ( P P h 3 ) ( a c e t o n e ) ]"*" i s d i s s o l v e d , whereas o n l y t h r e e - a n d f o u r - c o o r d i n a t e d e r i v a t i v e s n o r m a l l y appear f o r t h e a n a l o g o u s COD system. i i i i I I I I I I I I I I I I I I I I I I I I 1 1 1 L 7.0 6.0 5.0 PPM'*' 4.0 3.0 F i g u r e 3.13. 60 MHz 1 H nmr spectrum o f [Rh(NBD)(PPh„)(DMSO) 2.0   H nmr spectrum o f Rh(NBD)(PPh„)(DMSO)]SbF, i n 3 6 CDC2.- a t 35°C. The i m p u r i t y a t 62.1 i s a c e t o n e . i ON i -66-3.1 .3.2. S u l f o x i d e Complexes D e s p i t e t h e somewhat complex s o l u t i o n b e h a v i o u r o f such s o l u t i o n s r e a c t w i t h an e q u i v a l e n t o f a s u l f o x i d e t o g i v e y e l l o w (COD) o r y e l l o w - o r a n g e (NBD) c r y s t a l l i n e p r o d u c t s . A n a l y t i c a l d a t a a r e p r e s e n t e d i n T a b l e 3.1. The complexes a r e r e a s o n a b l y a i r - s t a b l e i n t h e s o l i d s t a t e . I n s o l u t i o n t h e NBD d e r i v a t i v e s a r e v e r y a i r - s e n s i t i v e , w h i l e t h e COD d e r i v a t i v e s show r e a c t i v i t y o n l y a f t e r s e v e r a l h o u r s . F o r [Rh(COD)(PPh 3)(DMSO)]A (A=PF 6,SbF 6) a mo l a r c o n d u c t a n c e o f -2 85 mho cm i s o b s e r v e d i n n i t r o m e t h a n e i d e n t i c a l t o t h a t f o r 13 [ R h ( C O D ) ( P P h 3 ) 2 ] P F 6 , a known 1:1 e l e c t r o l y t e . However, s o l u t i o n i r s p e c t r a o f t h e s e DMSO complexes i n n i t r o m e t h a n e show t h a t t h e s o l u t i o n s p e c i e s i s p r o b a b l y [ R h ( C O D ) ( P P h 3 ) ( M e N 0 2 ) ] + : v (SO) i s d e t e c t e d a t 1055 cm 1 , t h a t o f f r e e DMSO. The "*"H nmr s p e c t r a f o r t h e COD d e r i v a t i v e s i n CDC£ 3 show two s i g n a l s f o r t h e n o n - e q u i v a l e n t o l e f i n i c p r o t o n s . The d o w n f i e l d r e s o n a n c e a t 6^5.2 i s a s s i g n e d t o t h e p r o t o n s (Hp) t r a n s t o P P h 3 , c o n s i s t e n t w i t h 25 4 p r e v i o u s and r e c e n t a s s i g n m e n t s f o r t h e n e u t r a l compounds [MC£(C0D)PPh 3] M=Rh,Ir; i n t h e s e , t h e s i g n a l due t o t h e p r o t o n s t r a n s t o c h l o r i d e a p p ears a t 6^3, s i m i l a r t o t h a t found h e r e f o r t h o s e ( H ) o p p o s i t e t h e s u l f o x i d e Li l i g a n d s ( t a b l e 3.3). The down- and u p - f i e l d s h i f t s o f o l e f i n i c d i e n e p r o t o n s t r a n s t o P P h 3 and s u l f o x i d e , r e s p e c t i v e l y , a r e f u r t h e r s u p p o r t e d by t h e r e s p e c t i v e p o s i t i o n s o f t h e e q u i v a l e n t o l e f i n i c p r o t o n s a t 64.6 and 3.9 f o r t h e c a t i o n s [ R h ( C O D ) ( P P h 3 ) 2 ] + 1 3 and [ R h ( C O D ) ( D M S O ) 2 ] + . 2 3 The m e t h y l e n e p r o t o n s o f t h e d i e n e appear as a b r o a d s i g n a l between - 6 7 -61.8-2.5. The """H nmr r e s o n a n c e s o f t h e o l e f i n i c p r o t o n s o f t h e d i e n e i n t h e N B D - s u l f o x i d e compounds a r e complex a t room t e m p e r a t u r e , as d i s c u s s e d above. A l l t h e s u l f o x i d e complexes c o n t a i n 0-bonded s u l f o x i d e (see b e l o w ) . A l t h o u g h t h e l i g a n d exchange p r o c e s s e s o b s e r v e d by nmr as d e s c r i b e d above o c c u r i n s o l u t i o n s o f a l l t h e s e complexes, no f r e e s u l f o x i d e i s d e t e c t e d i n t h e s o l u t i o n i r s p e c t r a ( s e e t a b l e 3.2). 3.1.3.3. DMSO and TMSO Complexes A s h a r p 1 H nmr s i n g l e t due t o DMSO m e t h y l p r o t o n s o f [Rh(COD)(PPh^)-(DMSO)] + appears a t 62.2 ( f i g u r e 3.15), compared t o 62.6 f o r t h e f r e e s u l f o x i d e and 62.8 f o r [Rh(COD) (DMSO) J B F . 2 3 , and [Rh (COD) (DMSO) JSbF,. Z 4 Z D ( f i g u r e 3.01). D o w n f i e l d s h i f t s o f up t o 1 ppm a r e u s u a l l y c h a r a c t e r i s t i c o f S-bonded DMSO, w h i l e t h e 0-bonded complexes, i n w h i c h t h e p r o t o n s a r e f u r t h e r removed f r o m t h e m e t a l show c o n s i d e r a b l y l e s s v a r i a t i o n f r o m t h e f r e e v a l u e s ( r e f . 26 and f i g u r e 1.8, c h a p t e r 1 ) . The p r o x i m a l p h e n y l r i n g s of PPh^ must be r e s p o n s i b l e f o r t h e u p f i e l d s h i f t s o b s e r v e d h e r e , and n o t e d p r e v i o u s l y 2 7 f o r [Ir(CO)(DMS0)<PPh ) 2]C£0 4 ( 6 1 . 8 ) . Indeed, space f i l l i n g models s u g g e s t t h a t t h e most f a v o u r a b l e o r i e n t a t i o n i s one where a p h e n y l group p r e s e n t s a r i n g : c e n t e r t o t h e a d j a c e n t s u l f o x i d e l i g a n d , and such a c o n f o r m a t i o n w i l l l i k e l y p e r s i s t d u r i n g t h e m a j o r i t y o f r o t a t i o n a l m o t i o n . A d d i t i o n o f e x c e s s DMSO t o a s o l u t i o n o f [R h ( C O D ) ( P P h 3 ) ( D M S O ) ] + i n CDCA^ g i v e s a sh a r p r e s o n a n c e a t a w e i g h t e d mean p o s i t i o n o f f r e e and c o o r d i n a t e d l i g a n d , s u g g e s t i n g t h a t t h e exchange i s f a s t on t h e nmr tim e s c a l e . I n t e r e s t i n g l y , t h e COD (-CH=) re s o n a n c e s a r e not broadened w h i c h - 6 9 -a g a i n i m p l i e s 3 - c o o r d i n a t e b e h a v i o u r . F a c i l e exchange o f 0-bonded s u l f o x i d e s , l e s s so f o r S - b o n d e d 2 8 , has been n o t e d by o t h e r s 2 ^ ' 2 9 and t h i s , t o g e t h e r w i t h t h e o t h e r nmr and i r e v i d e n c e (see b e l o w ) , i s c o n s i s t e n t w i t h t h e 0-bonded n a t u r e o f DMSO i n t h e p r e s e n t i n s t a n c e . The p o s i t i o n o f t h e s u l f u r - o x y g e n s t r e t c h i n g v i b r a t i o n i s d i a g -n o s t i c o f t h e b o n d i n g mode; S-bonding u s u a l l y causes an i n c r e a s e o f v(SO) t o about 1100 cm \ whereas a s h i f t t o a l o w e r range (1000-900 cm ^) i s i n d i c a t i v e o f d o n a t i o n from oxygen ( f i g u r e 1.8, r e f e r e n c e s 26,28,30, c h a p t e r 6 ) . However, a s s i g n m e n t s o f v ( S 0 ) f o r 0-bonded s u l f o x i d e s w i t h a -methyl groups a r e c o m p l i c a t e d by t h e p r e s e n c e o f m e t h y l r o c k i n g v i b r a t i o n s w h i c h a r e s i m i l a r i n energy t o t h e S-0 s t r e t c h (see c h a p t e r 6 ) . Bands a t 983 and 947 cm 1 a r e o b s e r v e d i n t h e C T ^ B ^ s o l u t i o n i r o f [Rh(COD)(PPh 3)(DMSO)]A. The h i g h e r f r e q u e n c y band i s absent i n t h e spe c t r u m o f t h e DMSO-d,. ana l o g u e ( t a b l e 3.5) i n d i c a t i n g t h a t t h e major b c o n t r i b u t i o n t o t h i s band i s a m e t h y l r o c k i n g mode. By c o m p a r i s o n of t h e i r s p e c t r a o f t h e p r e s e n t compounds w i t h t h o s e o f o t h e r rhodium d i e n e s p e c i e s we have a s s i g n e d v(Rh-0) f o r t h e TMSO (432 cm" 1) and DMSO (450 cm" 1) compounds. The l a t t e r a p p e ars t o be s h i f t e d t o 430 cm 1 i n t h e DMSO-d, compound ( f i g u r e 3.16) and t h e b f r e q u e n c y r a t i o 1.046 tend s t o c o n f i r m t h i s a ssignment and i n d i c a t e 31 t h a t t h e v i b r a t i o n a l modes a r e a l m o s t p u r e Rh-0 s t r e t c h e s (see c h a p t e r 6 ) . Other i r bands f o r [ R h ( d i e n e ) (PPh^)!,]* a r e l i s t e d i n t a b l e 3.6. + 23 The d i s c o v e r y o f a b e t t e r p r e p a r a t i o n o f [Rh(COD)(DMSO)^] and i t s DMSO-d^ a n a l o g u e i n v o l v i n g o n l y s t o i c h i o m e t i c amounts o f s u l f o x i d e a l l o w e d us t o c o n f i r m t h e 0-bonded n a t u r e o f t h e DMSO l i g a n d s ; v(SO)=950 cm \ v(Rh-0)=473,465 cm \ f i g u r e 3.17. The Rh-0 s t r e t c h e s a g a i n e x h i b i t -70-a -1 T a b l e 3.5. Some I n f r a r e d Data (cm ) f o r [Rh(C0D)(PPh ) L ] P F ,L= DMSO and DMSO-d, 3 6 6 DMSO DMSO-d. 0 v ( H compound) Frequency Assignment Frequency Assignment v(D compound) b v(CH) 2260 m v(CD) b v(CH) 2125 m v(CD) 1420 m 6(CH) 1042 m 6 (CD) 1327 m 6(CH) 1020 s 6 (CD) 1038 s P r ( C H 3 ) (831 s)° P r ( C D 3 ) ( 1 . 2 5 ) C 992 s (983) P r ( C H 3 ) b P r ( C D 3 ) 958 s,br (947) v(SO) • 950 s,br (955) v(S0) 450 m v(Rh-O) 430 m v(Rh-0) 1.046 a N u j o l m u l l s ; v a l u e s i n p a r e n t h e s e s f o r C t L j B ^ s o l u t i o n s ; 4000-250 cm" 1. b Obscured; o t h e r 6 and p r modes a r e a l s o o b s c u r e d i n t h e 1450-950 cm 1 r e g i o n , and th u s t h e i s o t o p e r a t i o s h e r e cannot be a s s i g n e d w i t h c e r t a i n t y . c From SbF^ complex, s i n c e o b s c u r e d i n t h e PFg~ d e r i v a t i v e . - 7 1 -T a b l e 3.6. Some L i g a n d V i b r a t i o n s o f [ R h ( d i e n e ) ( P P h ^ L ] ^ NBD: 1480s, 1331m, 1310s, 1181s, 1155m, 1070w, 1000s, 878m, 800m, 775m, 560s. COD: 1480s, 1340m, 1315m, 1230m, 1189w, 1165m, 1080m, 1000m, 875m, 865s, 488s, 450m. P P h 3 : 3060m, 1975w, 1900w, 1820w, 1585w, 1574w, 1480s, 1442s, 1415m, 1268w, 1192s, 1100s, 1029m, 755s, 743s, 707s, 700s, 530s, 512s, 418s. 1200 1000 WAVENUMBER ICM"1) 400 F i g u r e 3.16. The i n f r a r e d s p e c t r a o f [Rh(COD) (PPh^) (L) ]PFg as a N u j o l mull,, (a) L=DMS0, (b) L=DMS0-d 6. There a r e p o l y s t y r e n e c a l i b r a t i o n peaks a t 1601 and 905 c m - 1 . I I WAVENUMBER (CM"1) F i g u r e 3.17. The i n f r a r e d s pectrum of [ R h ( € O D ) L 2 ] S b F 6 as a N u j o l m u l l . (a) L=DMSO, (b) L=DMS0-d6. There a r e p o l y s t y r e n e c a l i b r a t i o n peaks a t 1601 and 905 c m ~ l . -74-t h e e x p e c t e d d e u t e r i u m s h i f t o f about 1.05. A c o r r e l a t i o n e x i s t s between t h e bands a s s i g n e d as v(M-O) and t h e f r e q u e n c y r e d u c t i o n o f v(S 0 ) on c o o r d i n a t i o n o f s u l f o x i d e s t o m e t a l s ; t h i s i s t h e t o p i c o f c h a p t e r 6. 3.1.3.4. Other S u l f o x i d e Complexes The "*"H nmr d a t a o f t h e o t h e r s u l f o x i d e complexes ( t a b l e 3.3) show t h a t , e x c e p t f o r p-CH^, a l l r e s o n a n c e s a r e s h i f t e d u p f i e l d from t h e f r e e l i g a n d p o s i t i o n s , i n d i c a t i n g a g a i n a p h e n y l d i a m a g n e t i c s h i e l d i n g o f 0-bonded s u l f o x i d e l i g a n d s . The i r d a t a ( t a b l e 3.2) i n t h e 900-1000 cm..1 r e g i o n f o r systems u n c o m p l i c a t e d by t h e p r e s e n c e o f a-m e t h y l r o c k i n g modes ( i . e . , f o r t h e DMSO-d,, TMSO, TBPTSO, and NPSO systems) show t h a t t h e SO s t r e t c h s h i f t s D by 70-110 cm 1 on c o o r d i n a t i o n t o t h e m e t a l . T h i s wide s h i f t range p r e c l u d e s i t s use i n h e l p i n g a s s i g n v(S0) i n t h e MBMSO, MPSO, and MPTSO systems w h i c h c o n t a i n t h e m e t h y l r o c k i n g modes; t h e s h i f t o f b o t h bands i n t h e r e g i o n o f i n t e r e s t i s i n the same 70-110 cm 1 range ( t a b l e 3.2). N e v e r t h e l e s s , t h e i n c r e a s e d c o m p l e x i t y i n t h e 900-1000 cm 1 r e g i o n upon c o o r d i n a t i o n w i t h t h e a - m e t h y l - c o n t a i n i n g s u l f o x i d e s i s c o n s i s t e n t w i t h 0-bonding. A s s i g n m e n t s o f v(Rh-0) were p r e c l u d e d by t h e m u l t i p l i c i t y o f i r bands i n t h e 400-500 cm 1 r e g i o n . A l t h o u g h d i a r y l s u l f o x i d e s appear t o be 0-bonded t o rhodium ( u p f i e l d nmr s h i f t s ) i n s o l u t i o n , we have been u n a b l e t o i s o l a t e d i s c r e t e complexes, p o s s i b l y due t o u n f a v o u r a b l e s t e r i c i n t e r a c t i o n s i n t h e s o l i d s t a t e ; t h e d i a r y l s u l f o x i d e s s t u d i e d were d i p h e n y l s u l f o x i d e (DPSO), and S - o - t o l y l p - t o l y l s u l f o x i d e . The c h o i c e o f S-vs O - c o o r d i n a t i o n w i t h a s u l f o x i d e l i g a n d has 29 u s u a l l y been r a t i o n a l i z e d i n terms o f s t e r i c e f f e c t s . However, c o n s i d e r i n g t h a t b o t h t h e DMSO l i g a n d s a r e 0-bonded i n th e u n h i n d e r e d [ R h ( C O D ) ( D M S O ) c o m p l e x , e l e c t r o n i c f a c t o r s must p l a y a s u b s t a n t i a l r o l e i n t h e c a t i o n i c r h o d i u m ( I ) d i e n e complexes. Other r e c e n t examples showing 0-bonded DMSO l i g a n d s a r e th e R h ( I I I ) c a t i o n , 3_2 ( f i g u r e 1.4) w i t h t h r e e 0-bonded DMSO 3 2 and [Ru(COD)(DMSO)^] 2 + w i t h f o u r . 3 3 Thus s u l f o x i d e s can probe t h e " h a r d n e s s " (oxygen bonding) o r " s o f t n e s s " 34 ( s u l f u r b o n d i n g ) o f a s i t e on a m e t a l . The h a r d s i t e s found h e r e and on o t h e r s o f t - l i g a n d - R h ( I ) - c a t i o n m o i e t i e s , s u c h as [R h ( P P h 3 ) 2]"*", have s i g n i f i c a n c e f o r c a t a l y t i c p r o c e s s e s . F o r example, as mentioned i n c h a p t e r I , t h e h a r d - h a r d i n t e r a c t i o n s o f an enamide group on s u b s t r a t e s , w i t h a R h ( I ) c a t i o n , i s an i m p o r t a n t f a c t o r i n a c h i e v i n g h i g h e n a n t i o -s e l e c t i v i t y i n homogeneous asymmetric h y d r o g e n a t i o n . A t t e m p t s a t i s o l a t i n g [Rh(NBD)(DMSO)JSbF, as w e l l as [Rh(COD)(MPSO)„]~ Z D L [ R h ( C O D ) ( D P S O ) 2 ] + , [Rh (COD) (MBMSO) 2 1 + and [ R h ( C O D ) ( D I O S ) ] + y i e l d e d o n l y t h i c k o i l s o r brown s o l i d s r e s u l t i n g from d e c o m p o s i t i o n . The complexes [ Rh ( d i e n e ) (PPh,,) (DIOS) ] P F , , p r e p a r e d i n s i t u , appear t o be f i v e - c o o r d i n a t e ( e . g . f i g u r e 3.18). PPh, F i g u r e 3.18. [ R h ( d i e n e ) ( P P h 3 ) ( D I O S ) ] P F 6 < - 76 -The o l e f i n i c d i e n e p r o t o n s a r e i n e q u i v a l e n t a t 35°C f o r diene=COD and -50°C f o r NBD ( f i g u r e s 3.06, 3.08). A t t h e s e t e m p e r a t u r e s t h e a-me t h y l s o f DIOS r e s o n a t e a t 62.5 i n t h e nmr and t h e r e f o r e must b o t h be d i a m a g n e t i c a l l y s h i e l d e d by t h e p h e n y l groups o f PPh^* The t h r e e peaks c o r r e s p o n d i n g t o t h e s e m e t h y l s i n t h e COD d e r i v a t i v e may r e p r e s e n t t h e v a r i o u s d i a s t e r e o m e r s ( a t s u l f u r ) o f DIOS, c h e l a t e d t o Rh. The m e t h y l s o f ( S , S ) ( a t s u l f u r ) - D I O S a r e c h e m i c a l l y d i f f e r e n t from (R,R)-DI0S because o f t h e c h i r a l c e n t e r s a t c a r b o n . (R,S)-and (S,R)-DI0S s h o u l d have t h e same c h e m i c a l s h i f t b u t t h e y s h o u l d d i f f e r from t h e f i r s t two. A p p a r e n t l y c o o r d i n a t i o n t o t h i s R h ( I ) c e n t e r enhances t h e s e d i f f e r e n c e s so t h a t t h e t h r e e peaks a r e o b s e r v e d . The i n e q u i v a l e n c e o f t h e a c e t a l m e t h y l s a l s o s u p p o r t s t h e s t r u c t u r e i n f i g u r e 3.18. I t appears t h a t t h e DIOS c h e l a t i o n overcomes t h e r e l u c t a n c e o f COD t o s u p p o r t 5 - c o o r d i n a t i o n . The s o l u t i o n i r o f t h e s e DIOS s p e c i e s i s complex b u t t h e r e i s a s t r o n g v (S0) a t 950 cm 1 (oxygen b o n d i n g ) . 3.1.3.5. Other Mixed L i g a n d Complexes The v e r s a t i l i t y o f t h e a c e t o n e - c o n t a i n i n g c a t i o n s as p r e c u r s o r s f o r mixed l i g a n d complexes i s f u r t h e r d e m o n s t r a t e d by t h e ease o f p r e -p a r a t i o n o f t h e new complexes [ R h ( d i e n e ) (PPh^) ( C 0 ) 2 ] P F g , [Rh(NBD) ( P P h ^ ) -( p y ) ] S b F 6 , and [ R h ( C O D ) ( P P h 3 ) ( A s P h 3 ) ] P F 6 . The mixed p h o s p h i n e complexes, [Rh ( d i e n e ) ( P P h j ) (PPhMe,,) ] + c o u l d n o t be i s o l a t e d . The nmr spec t r u m a t -20°C o f t h e COD d e r i v a t i v e p r e p a r e d i n s i t u from t h e a c e t o n e c a t i o n and one PPhMe 2 i n CDC£ 3 showed o l e f i n i c peaks a t 6 3 . 1 5 ( [ R h ( C O D ) ( P P h 3 ) ( P P h M e ^ 2 ] + ? ; c f . 62.97 f o r [ R h ( N B D ) ( P P h M e 2 ) 3 ] + 1 3 ) , 4.52 ( [ R h ( C O D ) ( P P h 3 ) 2 ] + ) , 4.91 ([Rh(COD) (PPhMe 2) 1] + , c f . 65.06 f o r [Rh(NBD) (PPhMe 2) 2 ] + 1 3 ) , 5.38, -77-5 . 6 8 ( [ R h ( C O D ) ( P P h M e 2 ) ( P P h 3 ) ] + ? ) . The p r e s e n c e of t h e s e p r o d u c t s , each i n s i g n i f i c a n t amount, i s i n a c c o r d w i t h t h e l i g a n d exchange r e a c t i o n s d e s c r i b e d e a r l i e r . [ R h ( N B D ) ( P P h ^ ) ( A s P h ^ ) ] P F ^ was p r e p a r e d by S c h r o c k 13 and Osborn from [ R h ( N B D ) 2 ( P P h ^ ) p l u s A s P h 3 , but t h e y d i d n o t d e m o n s t r a t e t h e f l u x i o n a l b e h a v i o u r and i n e q u i v a l e n c e of t h e d i e n e p r o t o n s ( t a b l e 3.4, f i g u r e 3.03). The f i v e - c o o r d i n a t e c a r b o n y l complexes under CO a r e f l u x i o n a l even below -30°C. Some a v e r a g i n g p r o c e s s w i t h t h e NBD d e r i v a t i v e c a uses t h e o l e f i n i c p r o t o n s t o s h i f t f rom 64.23 a t 35°C t o 4.07 a t -30°C w h i l e t h e m e t h i n e peak rem a i n s s t a t i o n a r y a t 3.75 ( f i g u r e 3.05). Under A r , t h e NBD d e r i v a t i v e d i s p r o p o r t i o n a t e s t o s e v e r a l s p e c i e s p resumably due t o t h e l o s s o f CO. The h i g h e r v(C0) range i n CHC£ 3 o f t h e NBD d e r i v a t i v e (2080, 2045 cm' 1) compared t o t h a t o f t h e COD complex (2050, 1983 cm "*") i s c o n s i s t e n t w i t h t h e g r e a t e r i r - a c i d i t y o f t h e NBD l i g a n d . The i m p l i e d l a b i l i t y o f t h e s e w e a k l y h e l d c a r b o n y l 13 groups s u g g e s t e d t h e i r p o s s i b l e use as h y d r o f o r m y l a t i o n c a t a l y s t s ( s e c t i o n 3.4). 3.2 The R e a c t i o n s of t h e M i x e d L i g a n d Complexes w i t h Hydrogen. 3.2.1. I n t r o d u c t i o n The r e a c t i v i t y o f t h e Osborn t y p e c a t a l y s t s (eg [ R h ( d i e n e ) ( P P h 3 ) 2 ] + , see c h a p t e r 1.3.1) i s due i n p a r t t o t h e r e p l a c e m e n t of t h e d i e n e by l a b i l e s o l v e n t m o l e c u l e s v i a t h e h y d r o g e n a t i o n r e a c t i o n ( 1 . 1 8 ) . [ R h ( d i e n e ) ( P P h 3 ) 2 ] + + 3 H 2 -»- [ R h ( H ) 2 ( P P h 3 ) 2 ( s o l v e n t ) 2 ] + + norbornane (1.18) A c c o r d i n g l y t h e mixed l i g a n d complexes s y n t h e s i z e d i n t h e p r e s e n t -78-work were t r e a t e d w i t h R^, e s p e c i a l l y t o see i f S—bonding of t h e s u l f o x i d e s c o u l d be encouraged. The o b s e r v a t i o n a t low t e m p e r a t u r e o f t h e f i r s t d i h y d r i d o d i e n e i n t e r m e d i a t e , [ I r ( H ) ^ ( d i e n e ) ( P P h ^ ) > 35 r e p o r t e d d u r i n g t h e c o u r s e o f our work, s u g g e s t e d a n o t h e r a r e a t o e x p l o r e . 3.2.2. E x p e r i m e n t a l The hydrogen u p t a k e by some o f t h e mixed l i g a n d complexes p r e p a r e d i n s e c t i o n (3.1) was measured, g e n e r a l l y i n DMA s o l u t i o n , u s i n g t h e ampoule t e c h n i q u e s and t h e low t e m p e r a t u r e , m a g n e t i c a l l y s t i r r e d h y d r o g e n a t i o n v e s s e l d e s c r i b e d i n c h a p t e r 2. A l l of t h e i s o l a t e d complexes l i s t e d i n t a b l e 3.7 r e a c t w i t h i n t h e s o l i d s t a t e . The DMA was degassed s i m p l y by s t i r r i n g and pumping on i t f o r 5 min a t 0°C. Some systems were p r e p a r e d i n s i t u u s i n g DIOS, t h i o u r e a ( t u ) , DPSO, p h e n y l b e n z y l s u l f i d e (PBS), and i t a c o n i c a c i d (IA) l i g a n d s by d r o p p i n g an ampoule c o n t a i n i n g t h e [ R h ( d i e n e ) ( P P h ^ ) ( a c e t o n e ) ] + c a t i o n i n t o degassed DMA c o n t a i n i n g t h e l i g a n d . The b i s - c a r b o n y l complex was p r e p a r e d i n s i t u by r e a c t i n g t h e a c e t o n e - c o n t a i n i n g c a t i o n w i t h 1 atm CO; e x c e s s CO was pumped o f f and t h e gas u p t a k e was measured i m m e d i a t e l y a f t e r was r a p i d l y i n t r o d u c e d i n t o t h e f l a s k . A t t e m p t s a t p r e p a r i n g h y d r i d e o l e f i n i n t e r m e d i a t e s a t low tem-p e r a t u r e i n v o l v e d b u b b l i n g E^ f o r 5 min v i a hypodermic t u b i n g t h r o u g h a s o l u t i o n o f t h e mixed l i g a n d complex i n an nmr t u b e immersed i n a d r y i c e / a c e t o n e s l u s h b a t h . The sample was t h e n dropped i n t o t h e XL 100 probe s e t a t -60°C. -79-3.2.2.1. The nmr s p e c t r u m of [ R h ( N B D ) ( P P h 3 ) ( D I O S ) ] P F & + 2 . 5 H 2 (a) In (CD o)„C0: [ R h ( N B D ) ( P P h _ ) ( a c e t o n e ) ] P F , (30 mg, 0.045 mmol) and 1 Z 5 b DIOS (12 mg, 0.045 mmol) were r e a c t e d w i t h i n degassed ( C D ^ C O i n an nmr tube a t room t e m p e r a t u r e o v e r n i g h t . The s o l u t i o n changed from r e d t o deep brown. The DIOS peaks i n the nmr ( f i g u r e 3.19) were broadened by exchange: nmr (DIOS) 64.6-4.2(m,2,methine); 3.9-2.9(m, 7,§.-CH3+S-CH2) ; 2. 9-2.4 (m,3,_0-S-CH ) ; 1.46(m, 6,C-CH 3) . nmr (norbornene) 65.2(m,2,C=C-H); 2.8(m,2,methine); 1.5-1.0(m,4,CH 2). nmr (norbornane) 62.3(m,0.5,methine), 1.6-1.0(m,l,CH 2). No h y d r i d e s c o u l d be d e t e c t e d i n t h e h i g h f i e l d nmr r e g i o n . (b) I n CDC£ q: The hydrogen r e a c t i o n i s c o m p l i c a t e d by a r e a c t i o n w i t h t h e s o l v e n t w h i c h l e d t o a brown u n i d e n t i f i e d p r e c i p i t a t e . (c) I n DMA: The H 2 u p t a k e o f [ R h ( N B D ) ( P P h 3 ) ( a c e t o n e ) ] P F & (0.056 g, 0.085 mmol) and DIOS (0.030 g, 0.09 mmol) i n 1 ml degassed DMA was f o l l o w e d t o a c o m p l e t e d u p t a k e o f 2.5 moles H 2 per Rh a f t e r 100 min a t 30°C. T h i s deep brown s o l u t i o n was t r a n s f e r r e d t o an nmr tube under H 2 and t h e nmr s p e c t r u m was r e c o r d e d i n t h e h y d r i d e r e g i o n . The d o u b l e t o f t r i p l e t s o b s e r v e d a t 31.5T t h a t was a l s o measured f o r t h e [ R h ( N B D ) ( P P h 3 ) 2 ] + complex i n DMA under H 0, i s a t t r i b u t e d t o [Rh(H) „ (PPh„) 0 (DMA) „ ] + , J.,, = Z Z o Z Z Kn—rl 23 Hz, J „=16 Hz; f i g u r e 3.20. Norbornane i n t h e s o l u t i o n was d e t e c t e d Jr—n by gas chromatography. 3.2.3. R e s u l t s and D i s c u s s i o n The r e s u l t s i n t a b l e 3.7 i n d i c a t e t h a t t h e P P h 3 , A s P h 3 > DIOS, and t u d e r i v a t i v e s , by consuming a p p r o x i m a t e l y 3 moles of H 2, form s o l v a t e d F i g u r e 3.19 100 MHz 1 H nmr spectrum of [Rh(NBD) ( P P h 3 ) ( a c e t o n e ) ] P F 6 + DIOS r e a c t e d o v e r n i g h t w i t h H 9 i n (CD-) 7C0. -82-d i h y d r i d e s p e c i e s and norbornane ( c f . , t h e s t o i c h i o m e t r y o f r e a c t i o n 1.13, s e c t i o n 3.2.1.). The b i s c a r b o n y l s p e c i e s r e a c t s w i t h o n l y 2 moles of t o form e i t h e r a d i h y d r i d e and n o r b o r n e n e , o r a s o l v a t e d , n o n - h y d r i d i c s p e c i e s t h a t can h y d r o g e n a t e n o r b o r n e n e t o no r b o r n a n e . The o t h e r monodentate S-, N-, and 0-donors do n o t p r e v e n t a p r e f e r e n t i a l r e d u c t i o n o f t h e complex t o m e t a l . The f i n a l g r e e n i s h s o l u t i o n s o f t h e monodentate s u l f o x i d e / N B D complexes a r e c h a r a c t e r i s t i c 3 6 o f R h ( I I ) s p e c i e s and so r e d u c t i o n o f t h e d i e n e t o monoene f o l l o w e d by d i s p r o p o r t i o n a t i o n a c c o r d i n g t o r e a c t i o n (3.4) i s p o s s i b l y o c c u r r i n g . 2Rh(I) -> Rh(0) + R h ( I I ) (3.4) The o t h e r c a s e s must i n v o l v e h y d r i d e f o r m a t i o n and t h e n r a p i d d e c o m p o s i t i o n t o m e t a l . The f i n d i n g t h a t t h e DMSO/COD d e r i v a t i v e i s l e s s s u s c e p t i b l e t o h y d r o g e n a t i o n t h a n t h e NBD ones, a g r e e s w i t h t h e n o t e d ease o f h y d r o -g e n a t i o n o f [ R h ( N B D ) L 2 ] + compared t o [Rh^OD)!^]" 1", L = t e r t i a r y p h o s p h i n e 1 or a r s x n e . I t a c o n i c a c i d a p p ears t o be p r e f e r e n t i a l l y r e d u c e d i n s t e a d o f t h e d i e n e , a t l e a s t i n t h e c a t a l y t i c h y d r o g e n a t i o n o f t h i s a c i d d i s c u s s e d i n s e c t i o n 3.3, and m e t a l p r o d u c t i o n o c c u r s o n l y a f t e r t h i s s u b s t r a t e i s c o m p l e t e l y h y d r o g e n a t e d . I n i t i a l c o o r d i n a t i o n o f t h e l i g a n d i n t h e i n s i t u r e a c t i o n s must be f a s t s i n c e t h e same r e s u l t s f o r h y d r o g e n a t i o n a r e o b t a i n e d s t a r t i n g w i t h t h e preformed complexes. These f a s t h y d r o g e n u p t a k e r e a c t i o n s were found t o be d i f f u s i o n c o n t r o l l e d u s i n g t h e v e s s e l w i t h m a g n e t i c s t i r r i n g . A r u n w i t h L=PPh Q -83-T a b l e 3.7. S t o i c h i o m e t r y o f Hydrogen Uptake by [ R h ( d i e n e ) ( P P h 3 ) ( L ) ] A C o m p l e x e s v ' I s o l a t e d Complexes T Moles H 2/Rh (b) F i n a l S o l u t i o n T o t a l Time d i e n e L A °C NBD P P h 3 SbF. 0 30 3.0 NBD P P h 3 0 2.7 NBD DMSO SbF, 6 30 0.7 NBD py SbF, 6 30 0.2 NBD a c e t o n e P F 6 30 0.2 COD DMSO P F 6 20 0.6( e> I n S i t u Complexes NBD P P h 3 SbF, 6 30 2.9 NBD A s P h 3 SbF, 6 30 2.8 NBD DIOS SbF, 0 30 2.5 . NBD t u SbF, 6 30 2.0 2.8 NBD ( co ) 2 SbF, 6 30 1.8 NBD IA SbF, 6 30 1.2 NBD 3' DMSO SbF, 6 30 0.8 NBD 3 DMSO SbF, 6 30 0.9 NBD PBS SbF, 6 30 0.9 NBD DMA S b F 6 30 0.2 (a) (b) (c) 5 ml DMA, 1 Measured a t On s t a n d i n g atm H 2, [Rh]^8mM. t i m e o f m e t a l f o r m a t i o n i f t h i s f o r a few h o u r s t h e s e s o l u t i o n s c l e a r g o l d (c) (c) f o r r e a c t i o n 60 min 20 m i n ( d ) c l e a r g o l d green-brown+metal 10 min y e l l o w + m e t a l 3 min orange+metal 4 min yellow-brown+metal 110 min (c) g o l d g old-brown d a r k brown r e d red-brown red-brown 60 min 80 min 90 min 90 min 700 min 170 min orange-brown+metal 8 min g r e e n - y e l l o w + m e t a l 17 min g r e e n - y e l l o w + m e t a l 15 min orange-brown+metal 10 min orange+metal 4 min t o some r e a c t i o n o f t h e h y d r i d e w i t h t h e DMA. (d) The f l a s k was shaken c o n t i n u o u s l y , (;more v i g o r o u s a g i t a t i o n t h a n s t i r r i n g ) , (e) i n a c e t o n e . -84-u s i n g i n s t e a d a w e l l shaken r e a c t i o n f l a s k was too f a s t t o f o l l o w even a t 0°C. Thus, a l t h o u g h d i s t i n c t b r e a k s were o b s e r v e d i n some o f t h e u p t a k e v e r s u s t i m e p r o f i l e s u s i n g t h e v e s s e l w i t h s t i r r i n g , t h e s e may have r e s u l t e d from a d i f f u s i o n c o n t r o l l e d p r o c e s s , and t h e c o l l e c t i o n o f m e a n i n g f u l k i n e t i c d a t a was j u d g e d i m p o s s i b l e u s i n g t h i s v e s s e l . The nmr spec t r u m o f t h e DIOS d e r i v a t i v e r e a c t i o n w i t h 2.5 H^/Rh i n DMA i n d i c a t e s t h a t a d i s p r o p o r t i o n a t i o n r e a c t i o n (3.5) o c c u r s s i n c e t h e o n l y h y d r i d e d e t e c t e d was t h a t a s s i g n a b l e t o [ R h ( H ) 2 ( P P h 3 ) 2 ( D M A ) 2 ] + w i t h c i s - h y d r i d e s and t r a n s - p h o s p h i n e s ( f i g u r e 3.20). 2 [Rh(NBD) (PPh )(DIOS) ] P F , + 5H. -> 3 6 2 (3.5) 2 norbornane + [ R h ( H ) 2 ( P P h 3 ) 2 ( D M A ) 2 ] + + [ R h ( D I 0 S ) 2 ] + The b i s p h o s p h i n e d i h y d r i d e was formed i n d e p e n d e n t l y f r o m [Rh(NBD)(PPh,.)„]SbF 1 i n DMA. P r o t o n nmr s i g n a l s a t t r i b u t a b l e t o t h e bis-DIOS c a t i o n can be o b s e r v e d on c a r r y i n g out t h e H 2 r e a c t i o n i n a c e t o n e - d ^ . A l t h o u g h t h e sp e c t r u m i s broadened by exchange, t h e r e a r e r e s o n a n c e s c o r r e s p o n d i n g t o b o t h S- and 0-bonded s u l f o x i d e ( f i g u r e 3.19), d i f f e r e n t t o t h o s e r e c o r d e d f o r t h e i n s i t u [ R h ( d i e n e ) ( P P h ^ ) ( D I O S ) ] + c a t i o n (see s e c t i o n 3.1.2.7). A t t e m p t s a t g e n e r a t i n g [ R h ( D I 0 S ) 2 ] + by h y d r o g e n a t i n g [Rh(NBD) 2]PFg and DIOS ( r a t i o 1:2) were n o t s u c c e s s f u l ( c h a p t e r 4.2). The norbornane produced by r e a c t i o n (3.5) was d e t e c t e d by G.C. and nmr. No h y d r i d e s were o b s e r v e d i n t h e nmr a t -60°C of s o l u t i o n s o f [Rh(NBD)(PPh„)(DMSO)]PF, i n ( C D o ) o C 0 o r CDC£ 0 w h i c h had been r e a c t e d 3 O J Z 3 -85-w i t h H2 a t -78°C; no change i n t h e orange c o l o u r o f t h e s o l u t i o n s was n o t e d on r e a c t i o n w i t h H^. When t h e s e s o l u t i o n s were warmed m e t a l formed r a p i d l y , w h i c h may i n d i c a t e m e t a l h y d r i d e f o r m a t i o n a t some s t a g e . 3.3. A t t e m p t s a t t h e A s y m m e t r i c H y d r o g e n a t i o n o f P r o c h i r a l O l e f i n s The brown s o l u t i o n (5 m l , 0.01 M i n Rh) g e n e r a t e d by r e a c t i o n (3.5) c a t a l y t i c a l l y h y d r o g e n a t e d 0.1 g i t a c o n i c a c i d (IA) t o a - m e t h y l s u c c i n i c a c i d , but w i t h no e.e., i n 150 min a t 30°C. C o n s i d e r i n g t h e l a c k o f a s ymmetric i n d u c t i o n i n t h e p r o d u c t , t h e b i s p h o s p h i n e d i h y d r i d e complex i s a l m o s t c e r t a i n l y t h e a c t i v e c a t a l y s t . I f PTSE (14, f i g u r e 1.3) i s u sed i n p l a c e o f DIOS, th e "same" system d e p o s i t s m e t a l a f t e r 20 min s u g g e s t i n g t h a t the b i s PTSE c a t i o n formed v i a e q u a t i o n (3.5) i s s u s -c e p t i b l e t o r e d u c t i o n under H.^ (see a l s o c h a p t e r 4.2). The complexes [ R h ( d i e n e ) ( P P h 3 ) L ] P F 6 , diene=C0D, NBD; L=acetone, DMSO, MPTSO (18, f i g u r e 1.3) a l l h y d r o g e n a t e d , i t a c o n i c a c i d a t about t h e same i n i t i a l r a t e i n e i t h e r MeOH o r a c e t o n e a t 20°C. Thus 5 ml o f a 1.5 mM s o l u t i o n o f t h e c a t a l y s t s h y d r o g e n a t e s 0.1 g s u b s t r a t e i n 100 -4 min w i t h an i n i t i a l h ydrogen u p t a k e r a t e o f (1.0±0.3)xl0 M/sec. E x c e s s 1 , 2 - b i s ( d i p h e n y l p h o s p h i n o ) e t h a n e was added t o t h e f i n a l r e a c t i o n s o l u t i o n t o d i s p l a c e any c o o r d i n a t e d COD; t h i s s o l u t i o n was a n a l y z e d by gas chromatography and COD was d e t e c t e d . The a - m e t h y l s u c c i n i c a c i d p r o d u c t from t h e r e a c t i o n w i t h L=R-MPTS0 was not o p t i c a l l y a c t i v e . The i t a c o n i c a c i d i s p r e f e r e n t i a l l y h y d r o g e n a t e d and t h e l i g a n d L does not i n f l u e n c e t h e r a t e o r p r o d u c t o f t h i s r e a c t i o n and t h u s a common i n t e r m e d i a t e such as [Rh(H)„(diene)(IA)(PPh„) ] + can be p o s t u l a t e d . The - 8 6 -21 v e r y a c t i v e homogeneous h y d r o g e n a t i o n c a t a l y s t , [Rh(COD) (PPh^) (py) ]PF^. , p r o b a b l y i n v o l v e s a s i m i l a r p y r i d i n e - f r e e i n t e r m e d i a t e s i n c e i t was shown i n s e c t i o n (3.2.3) t h a t t h e a n a l o g o u s NBD/py system goes t o m e t a l i n t h e absence of s u b s t r a t e s ( a l k y n e s o r a l k e n e s ) . H y d r o g e n a t i o n of c o o r d i n a t e d COD i s s l o w e r t h a n NBD ( s e c t i o n 3.2.3), and t h i s i s c o n s i s t e n t w i t h t h e r e p o r t t h a t m e t a l i s formed a f t e r a few h o u r s when th e COD/py c a t a l y s t A 2 1 i s u s e d . A t r o p i c a c i d , a n o t h e r p r o c h i r a l s u b s t r a t e , was not h y d r o g e n a t e d by t h e s e mixed l i g a n d c a t a l y s t s a t 30°C. At h i g h e r t e m p e r a t u r e s (50°C) t h e s o l u t i o n s d e p o s i t m e t a l . The r e s u l t s of t h e s e e x p e r i m e n t s i n d i c a t e t h a t t h e s t u d y o f complexes w i t h t h e l e s s l a b i l e s u l f u r - b o n d e d c h i r a l s u l f o x i d e l i g a n d s as opposed t o 0-bonded ones, and h o p e f u l l y w i t h s i m p l e r s o l u t i o n b e h a v i o u r , would be more p r o f i t a b l e i n t h e s e a r c h f o r an asymmetric h y d r o g e n a t i o n c a t a l y s t ( c h a p t e r 4 ) . 3.4. H y d r o f o r m y l a t i o n R e a c t i o n s u s i n g [ R h ( N B D ) ( P P h 3 ) ( C O ) ^ ] + 3.4.1. I n t r o d u c t i o n The complexes RhH(CO)P 3,where P i s a t e r t i a r y p h o s p h i n e , a r e v e r y 37 38 39 e f f i c i e n t and s e l e c t i v e h y d r o f o r m y l a t i o n c a t a l y s t s . ' ' U n l i k e Co 39 complexes t r a d i t i o n a l l y used f o r t h e Oxo p r o c e s s , t h e rhodium c a t a l y s t s a c h i e v e , a t c o n d i t i o n s o f 1 atm and 90°C, l i n e a r t o b r a n c h e d a l d e h y d e 39 p r o d u c t r a t i o s o f 10 w i t h no h y d r o g e n a t e d s i d e p r o d u c t s , and i n d e e d , 38 Rh based c a t a l y s t s a r e now r e p l a c i n g Co ones i n i n d u s t r i a l p r o c e s s e s . S t u d i e s have shown t h a t t h e t r i s p h o s p h i n e complex, RhH(CO)(PPh^)^, i s t h e most s e l e c t i v e . To p r e v e n t p h o s p h i n e l i g a n d d i s s o c i a t i o n and f o r m a t i o n o f l e s s s e l e c t i v e c a t a l y s t s s u c h as RhH(CO)^(PPh^) 2> r e a c t i o n s a r e c a r r i e d -87-out w i t h an e x c e s s o f ph o s p h i n e present. J° Few d a t a i f any e x i s t on c a t i o n i c h y d r o f o r m y l a t i o n c a t a l y t i c s y s t e m s , and so i t was o f i n t e r e s t t o t e s t t h e [ R h ( N B D ) ( P P h 3 ) ( C O ) 2 1 + complex. 3.4.2. E x p e r i m e n t a l and R e s u l t s The gas u p t a k e e x p e r i m e n t s were c a r r i e d o u t i n a d i m p l e d f l a s k w i t h a s i d e arm i n t h e u s u a l f a s h i o n ( s e c t i o n 2.3). 1-Hexene and 1-heptene s u b s t r a t e s were f i r s t p a ssed down a l u m i n a columns t o remove p e r o x i d e i m p u r i t i e s , and t h e n h y d r o f o r m y l a t e d as f o l l o w s : a) An ampoule c o n t a i n i n g 40 mg [Rh(NBD)(PPh„)(acetone)]PF, was dropped i n t o a deoxygenated s o l u t i o n o f DMA (5 ml) and o l e f i n (0.2-0.4 ml) under a CO atmosphere a t 25°C. The CO/Rh gas u p t a k e r a t i o o f 2.0 was v e r i f i e d . The CO p r e s s u r e was t h e n r e d u c e d t o 380 t o r r , t h e t e m p e r a t u r e was r a i s e d t o 50°, and was i n t r o d u c e d t o a t o t a l o f 1 atm a t t h e new b a t h t e m p e r a t u r e . A r a p i d u p t a k e o f 1.0 mole of gas (H^) per Rh was measured and t h i s was accompanied by a s o l u t i o n c o l o u r change from y e l l o w t o orange. The h y d r o f o r m y l a t i o n r e a c t i o n t h e n s t a r t s v e r y s l o w l y b u t b u i l d s up t o g i v e a maximum r a t e o f 1x10 ^M ( H ^ + C O ) / s e c a f t e r 200 min. The s o l u t i o n i s gold-brown a t t h i s p o i n t . The 1-hexene (0.21 ml) r e a c t i o n was s t o p p e d a f t e r 20h and t h e p r o d u c t s were a n a l y z e d by G.C.: 16% 1-hexene, 60% 1 - h e p t a n a l , and 24% 2 - h e p t a n a l , The 1-heptene (0.43 ml) r e a c t i o n gave a f t e r 40 h: 45% 1-heptene, 40% 1 - o c t a n o l , and 15% 2 - o c t a n o l . b) A s l i g h t l y more a c t i v e c a t a l y s t i s p r e p a r e d by f o r m i n g t h e b i s - c a r b o n y l compound as above and t h e n r e p l a c i n g the CO by a pure B.^ atmosphere. A t o t a l u p t a k e o f 2.0 moles o f H ? per Rh t a k e s p l a c e a t 50°C and a brown -88-s o l u t i o n r e s u l t s ; t h e r e was no f u r t h e r c a t a l y t i c r e d u c t i o n o f 1-hexene. Then t h e s y n t h e s i s gas (CO/H^) m i x t u r e i s i n t r o d u c e d and t h e h y d r o -f o r m y l a t i o n r e a c h e s a maximum r a t e o f 3x10 ~*M/sec a f t e r 40 min a t 50°C. The l i n e a r / b r a n c h e d s e l e c t i v i t y o f t h e p r e v i o u s method was r e p r o d u c e d u s i n g 1-hexene; a f t e r 16 h o u r s : 25% 1-hexene, 54% 1 - h e p t a n a l , 21% 2 - h e p t a n a l . c) The [ R h ( N B D ) ( P P h 3 ) ( C 0 ) 2 ] P F 6 complex i s a h y d r o g e n a t i o n c a t a l y s t f o r 1-hexene i n 2-methoxyethanol: a t 1 atm and 50° w i t h c a t a l y s t and —6 o l e f i n c o n c e n t r a t i o n s as above, t h e i n i t i a l r a t e o f u p t a k e was 6x10 M/sec. T h i s system a l s o h y d r o f o r m y l a t e s 1-hexene a t t h e same r a t e as when DMA i s used as t h e s o l v e n t . 3.4.3. D i s c u s s i o n The complex [Rh(NBD) (PPh^) (CO)is a p r e c u r s o r t o a h y d r o f o r m y -l a t i o n c a t a l y s t o f good s e l e c t i v i t y and a c t i v i t y . The r a t i o o f l i n e a r t o b r a n c h e d a l d e h y d e p r o d u c t i s 2.5 f o r b o t h 1-hexene and 1-heptene; n o r m a l l y s u c h good s e l e c t i v i t y i s o b s e r v e d f o r n e u t r a l Rh c a t a l y s t s o n l y 38 39 when t h e r a t i o o f PPh-j t o Rh i s t h r e e o r g r e a t e r . ' I n a d d i t i o n most o f t h e n e u t r a l Rh systems r e q u i r e h i g h e r t e m p e r a t u r e s and p r e s s u r e s t o 39 e f f e c t t h i s r e a c t i o n . A d e t a i l e d s o l u t i o n s t u d y would be r e q u i r e d t o e l u c i d a t e t h e n a t u r e o f t h e a c t i v e c a t a l y s t . A s o l v a t e d c a t i o n i c complex i s a good p o s s i b i l i t y s i n c e t h e s e l e c t i v i t y i s h i g h e r t h a n t h a t e n c o u n t e r e d f o r 38 n e u t r a l c a t a l y s t s w i t h PPh^/Rh-l , and s i n c e t h e h y d r o g e n a t i o n o f t h e n o r b o r n a d i e n e does o c c u r . - 8 9 -4. S u l f o x i d e s S u l f u r - B o n d e d t o Rhodium 4.1. S y n t h e s i s and S p e c t r o s c o p i c P r o p e r t i e s 4.1.1. I n t r o d u c t i o n A c c o r d i n g t o t h e p r i n c i p l e s o f Hard and S o f t A c i d s and Bases ( H . S . A . B . ) b o t h R h ( I ) and R h ( I I I ) s h o u l d p r e f e r c o o r d i n a t i o n t o t h e " s o f t " s u l f u r atom o f a s u l f o x i d e l i g a n d . R h ( I ) i s a c l a s s (b), " s o f t " L e w i s a c i d because i t i s l a r g e i n s i z e and r i c h i n d e l e c t r o n s . R h ( I I I ) , w h i c h i s s m a l l e r and more p o s i t i v e , b o r d e r s on t h i s " s o f t " c l a s s i f i c a t i o n . However l i g a n d s around t h e s e i o n s can g r e a t l y i n -f l u e n c e t h e i r e l e c t r o n i c b e h a v i o u r . I n c h a p t e r 3 i t was d e m o n s t r a t e d t h a t n e u t r a l , " s o f t " l i g a n d s (CODjPPh^) on t h e m e t a l can i m p a r t c l a s s (a) c h a r a c t e r t o R h ( I ) i n terms of t h e o t h e r c o o r d i n a t i o n s i t e s . T h e r e f o r e i t was a n t i c i p a t e d t h a t " h a r d e r " e l e c t r o n d o n o r s s u c h as C£ would encourage s u l f u r b o n d i n g o f s u l f o x i d e s when a t t a c h e d t o Rh. The compounds [RhC£(cyclooctene)^\ 2 a n c * [RhC£(ethylene)^]^ were e x p e c t e d t o be e f f i c i e n t p r e c u r s o r s t o c h l o r o - s u l f o x i d e complexes of Rh, s i n c e t h e s e compounds c o n t a i n l a b i l e l i g a n d s t h a t s h o u l d be r e a d i l y d i s p l a c e d by s u l f o x i d e i n low c o n c e n t r a t i o n . I n a r e d u c i n g e n v i r o n m e n t , 2 3 R h C ^ ^ ^ O i s a l s o a u s e f u l p r e c u r s o r t o rhodium complexes. ' The p o t e n t i a l o f s u l f u r d onors f o r s u p p o r t i n g homogeneous h y d r o -g e n a t i o n was emphasized i n c h a p t e r 1. A c o n s i d e r a t i o n was t h e hope t h a t m e t a l d s u l f u r d b a c k b o n d i n g , s i m i l a r t o t h a t o b s e r v e d i n IT TT if | / o c [Ru(DMSO)(NH 3) 5] and [Fe(DMSO)(CN) 5] , might be s i g n i f i c a n t i n R h ( I ) - s u l f o x i d e c o m plexes, and m i g h t f a v o u r a b l y i n f l u e n c e t h e i r c a t a l y t i c b e h a v i o u r . -90-4.1.2. E x p e r i m e n t a l S y n t h e t i c p r o c e d u r e s and s o l u t i o n measurements i n v o l v i n g R h ( I ) complexes were con d u c t e d under an ar g o n atmosphere. A l l t h e R h ( I ) -DMSO a d d u c t s were m u l l e d i n a g l o v e bag under d r y A r . The i s o p r o p a n o l w i t h 0.1% w a t e r was used as s u p p l i e d by F i s h e r Chem. Co.. The phos-p h i n e o x i d e s (OPPh2Me,OPPhMe2,0PPhEt2) were p r e p a r e d by o x i d i z i n g t h e ph o s p h i n e s i n a s l i g h t e x c e s s o f h o t , d i l u t e H2O2, and t h e n e x t r a c t i n g t h e p r o d u c t i n t o CECH^, d r y i n g o v e r MgSO^, removing t h e s o l v e n t , and r e c r y s t a l l i z i n g from EtOH. I n f r a r e d d a t a r e f e r t o N u j o l m u l l s u n l e s s o t h e r w i s e s t a t e d . NMR s p e c t r a l d a t a g i v e n t o 3 d e c i m a l s were a c q u i r e d on a U.B.C.-made 270 MHz s p e c t r o m e t e r c o n s i s t i n g o f an O x f o r d I n s t r u m e n t s s u p e r c o n d u c t i n g magnet i n t e r f a c e d t o a N i c o l e t 1080 computer. P r e p a r a t i o n o f t h e Complexes 4.1.2.01. RhC£ 3L 3;L=DMSO,DMSO-d 6,TMSO,MPSO,R-MPTSO R h C ^ ^ ^ O (0.2 g, 0.76 mmol) was d i s s o l v e d and s t i r r e d f o r 30 m i n i n 3 m l 2 - p r o p a n o l and 0.6 ml ^ 0 . When L (2.28 mmol) was added, t h e s o l u t i o n t u r n e d from r e d t o y e l l o w w i t h i n one hour. Brown s u s p e n s i o n s o f t e n formed i n i t i a l l y , b u t w i t h s t i r r i n g t h e s e were c o n v e r t e d t o s u s -p e n s i o n s o f y e l l o w p r o d u c t . Sometimes s o l u t i o n s f o r t h e L=DMS0,DMS0-d^, and TMSO systems remained c l e a r , and d e p o s i t e d orange c r y s t a l s ( y i e l d , 80-95%) on s t a n d i n g o v e r n i g h t . The L=MPS0 and MPTSO systems y i e l d e d f i n e y e l l o w powders on s t i r r i n g f o r 18 h ( 9 0 % y i e l d ) . The p r o d u c t s were f i l t e r e d , washed w i t h 2 - p r o p a n o l and e t h e r , and d r i e d i n vacuo. A l l t h e complexes can be r e c r y s t a l l i z e d f r o m C H 9 C £ 9 by a d d i t i o n o f e t h e r ; t h e - 9 1 -R-MPTSO adduct i s o b t a i n e d as f e a t h e r y y e l l o w c r y s t a l s i n c o r p o r a t i n g 0.5 moles CH^Cic^. The compound RhCJi^(DMSO) 3 can a l s o be p r e p a r e d by h e a t i n g 0.2 g o f RhCJ> 3.3H 20 i n 1.0 ml DMSO a t 70° f o r 4 h, and then a d d i n g 100% EtOH u n t i l t h e m i c r o c r y s t a l l i n e s o l i d p r e c i p i t a t e s . T a b l e 4.1 l i s t s s o l u t i o n i r d a t a f o r t h e compounds. A n a l . (DMSO a d d u c t ) C a l c d f o r RhC.H, oC£„0 oS„: C, 16.24; H, 4.09. Found: C, 16.39; H, 4.03. nmr(CDC£ 3), s„ee t a b l e 4.2, f i g u r e 4 . 0 3 ( b ) . nmr(CD 2C£ 2), 63.53(s,5,S^-CH^) , 3 . 4 3 ( s , 3 , i m p u r i t y o f RhC£ 3(DMS0) 3?) , 3.35 ( s , 5 , S - C H 3 ) , 2.80(s,5,0-S-CH 3). i r , v(SO)1150s,1135s,935s; P r ( C H 3 ) 1032s,996s,977s; v(Rh-C£)335s,340m,297m. A n a l . (TMSO a d d u c t ) . C a l c d f o r R h C ^ H ^ C ^ O ^ : C , 27.62; H, 4.63. Found: C, 27.61; H, 4.82. nmr(CDC£ 3) 64.37 (m, 2.6, S-C-H) , 3.91(m,2.0,S-C-H), 3.53(m,6,S-C-H+0-S-C-H), 3.03(m,1.3,JD-S-C-H), 2.29(m,12,S-C-CH 2"). i r , ( v(SO)1150s,1133s,907s;v(ring)1095m,1075s,1035m,955m,890s,880s; v(Rh-C£) 345s,318s. A n a l . (MPSO a d d u c t ) . C a l c d f o r R h C ^ H ^ C ^ O ^ : C, 40.04; H, 3.84. Found: C, 39.65; H, 3.72. nmr(CDC£ 3). 68.1-7.4(m,15,phenyl); r e s o n a n c e s of S^-CH3: 4.03(s, 1.2) ,3.96(s,0.8) ,3.91 (s,0.5) ,3.84(s, 1.2) , 3 . 7 6 ( s , 1.1) , 3 . 6 8 ( s , l . l ) ; r e s o n a n c e s o f 0-S-CH^ 2 . 8 6 ( s , 0 . 4 ) , 2 . 8 0 ( s , 0 . 3 ) , 2 . 7 2 ( s , 1 . 8 ) , 2 . 5 2 ( s , 0 . 2 ) . i r , v ( S O ) 1 1 5 0 s , 1 1 4 0 s , 9 3 0 s ; p r ( C H 3 ) 9 8 7 s , 9 7 2 s , 9 5 7 s ; v(Rh-C£) 352s,317s. A n a l . (R-MPTSO a d d u c t ) C a l c d f o r R h C ^ H ^ C ^ O ^ . - 0 . 5 C H 2 C £ 2 : C, 41.18; H, 4.34. Found: C, 40.43; H, 4.28. nmr(CDC£ 3) . 68.0-7.2(m,12,phenyl); 5.2(s,l,CH 2C£. 2); 3.86 (s , 3 ,^-CH 3), 3. 58 (s ,3 ,S-CH 3) , 2.80 (s ,3 ,C>-S-CH3) ; 2.38 ( s , 3 , C - C H 3 ) . i r , . v(SO)1156s,933s; p r(CH 3)960s;v(Rh-C£)354s,310m. -92-4.1.2.02 RhC£ 3(DMSO) 2(0=L); (0=L)=dimethylformamide, N - f o r m y l p i p e r i d i n e RhC£ 3(DMSO) 3 (0.15 g, 0.34 mmol) was d i s s o l v e d and s t i r r e d f o r 4 h a t 50°C i n a s t o p p e r e d tube c o n t a i n i n g 4 m l 1 , 2 - d i c h l o r o e t h a n e and 1.5 ml 0=L. A f t e r t h e s o l u t i o n was c o n c e n t r a t e d t o 2 ml under vacuum, e t h e r was s l o w l y added t o o b t a i n orange c r y s t a l s (50% y i e l d ) . A n a l . (DMF a d d u c t ) C a l c d f o r R h C ^ g C ^ O ^ N : C, 19.16; H, 4.36; N, 3.19. Found: C, 19.27; H, 4.47; N, 3.27. nmr(CDC£ 3) 68.27(s,1,0-C-H), 3.646 ( s , 6 , S - C H 3 ) , 3.447(s:,6,S-CH 3),3.11(s,3,N-CH 3),3.08(s,3,N-CH 3). i r , v(C0) 1635s; v(SO)1148s,1135m; v(Rh-C£)354s,338m,295m. A n a l . (NFP a d d u c t ) . C a l c d f o r R h C ^ H ^ C i c ^ O ^ N : C, 25.09; H, 4.84; N, 2.92. Found: C, 25.35; H, 4.84; N, 2.93. nmr (CDC«,3), 3. 3 0 ( s , 1,0-C-H); 3.647 ( s , 6 , S - C H 3 ) , 3.437(s,6,S-CH 3). i r , v(CO)1620s; v(SO)1145s,1132s; (Rh-C£) 355s,333m. 4.1.2.03 RhC£ 3(DPSO) 2(HOCH(CH 3) 2) RhC£ 3?3H 20 (0.050 g, 0.19 mmol) was d i s s o l v e d and s t i r r e d i n 1 ml 2 - p r o p a n o l f o r 30 m i n u t e s . The brown-orange p r o d u c t p r e c i p i t a t e d a few m i n u t e s a f t e r t h e a d d i t i o n o f 0.14 g (0.57 mmol) of DPSO. The s u s p e n s i o n was s t i r r e d f o r 4 h o u r s , f i l t e r e d , washed w i t h 2 - p r o p a n o l and e t h e r , and d r i e d i n vacuo ( 7 0 % ) . A n a l . C a l c d f o r R h C ^ H ^ g C J ^ O ^ : C, 48.12; H, 2.99. Found: C, 47.99; H, 3.26. nmr(CDC£ 3) 68.2-7.4(m,20,phenyl); 4.05(m,0.5,methine),2.3-1.9 (broad s i n g l e t , 3 , C H 3 ) , 1.22(d,3,CH 3). i r , v(OH)3400w;v(SO)1147m,936s; v(Rh-C£)350s. 4.1.2.04 [(NPSO) 2H][RhC£ 4(NPSO) 2] (a) RhC£^-3H 90 (0.16 g, 0.72 mmol) was d i s s o l v e d and s t i r r e d i n -93-2 ml degassed 2 - p r o p a n o l f o r 30 m i n u t e s . The s o l u t i o n l i g h t e n e d t o re d - o r a n g e when 0.29 ml NPSO (2.5 mmol) was added. A f t e r 1 day t h e volume was r e d u c e d t o 1 ml under vacuum; a d d i t i o n o f 3 m l degassed hexane p r e c i p i t a t e d an orange m i c r o c r y s t a l l i n e s o l i d t h a t was f i l t e r e d , washed w i t h hexane and d r i e d i n vacuo. Use of CHCi^/hexane a l l o w e d r e c r y s t a l l i z a t i o n . Y i e l d , 40%. C a l c d f o r R h C ^ H ^ C J c ^ O ^ : C, 36.82; H, 7.28. Found: C, 36.67; H, 7.24. nmr(CDC£ 3) 64.3-3.3 (m,8,:S_-C-H) , 3.1 (m,8,0-S-C-H), 1.88(m,16,S-C-C-H), 1.1(m,24,S-C-C-C-H). i r ,v(SO)1122s; v(S-O-H-O-S)1600-1100 mb,880-600 sb; v(Rh-C£)3.50 m, 337s; see f i g u r e 4.07. (b) A s o l u t i o n o f RhC£ 3'3H 20 (0.1 g, 0.38 mmol) i n 0.15 ml co n -c e n t r a t e d HC£ a t 70°C was c o o l e d t o 25°C b e f o r e 0.75 ml (5 mmol) o f NPSO were added. The orange c r y s t a l s t h a t formed o v e r 5 h o u r s were f i l t e r e d , washed w i t h a l i t t l e 2 - p r o p a n o l , a i r - d r i e d , and r e c r y s t a l l i z e d as above. Y i e l d , 65%. S p e c t r a l d a t a a g r e e w i t h t h o s e g i v e n above i n ( a ) . 4.1.2.05 [H(DMS0) 2J[RhC£ 4(DMSO) 2] The method o f Henbest e t a l . was used t o p r e p a r e t h e compound as o r a n g e - r e d c r y s t a l s . nmr(D 20) . 63.56(s,4. 2, trans-[RhCJt^(DMSO) (D 20) ]~) , 3.50(s,4.0,trans-[RhC£ 4(DMSO) 2]~), 2 . 7 0 ( s , b r o a d , 1 6 , f r e e DMSO). i r , v (S0) 1125;v(S-0-H-0-S)1600-1100 mb, 900-600 sb; p^(CH3)1020s,972m;v(Rh-C£) 350s,336s; see f i g u r e 4.08. 4.1.2.06 [NEt 4][RhC£ 4(DMSO) 2] A f t e r RhC£ 3(DMSO) 3(0.067 g, 0.15 mmol) and NEt 4C£ (0.025 g, 0.15 mmol) were warmed a t 40°C f o r 30 m i n u t e s i n C H ? C £ ? , s o l v e n t was pumped -94-o f f u n t i l an orange p r e c i p i t a t e formed. The m i x t u r e was c o o l e d t o 0°C and t h e n f i l t e r e d . R e c r y s t a l l i z a t i o n f rom h o t CH 2C£ 2/ether y i e l d e d a m i c r o c r y s t a l l i n e s o l i d . Y i e l d , 70%. A n a l . C a l c d . f o r R h C 1 2 H 3 2 C £ 4 N 0 2 S 2 : C, 27.13; H, 6.07; N, 2.63. Found: C, 27.25; H, 6.0; N, 2.50. nmr(D 20) 63. 54 ( s , 6, S_-CH3); 2. 67 ( s , 6 , f r e e DMSO); 3.19 (q,8,N-CH), 1. 25(t,12,N-C-CH) . nmr(CD 2C£ 2) 3.43(s, 12,S-CH,,); 3.26(q,8, N-CH), 1.31(t,12,N-C-CH). i r , v(SO)1140s; (C^) 1017m, 979m, 935m; v(Rh-C£)345m, 335s. 4.1.2.07 [P.S.H ][RhC£ 4(DMS0) 2]; P.S.="Proton Sponge", 1 , 8 - b i s -( d i m e t h y l a m i n o ) n a p h t h a l e n e [H(DMS0) 2][RhC£ 4(DMSO) 2] (29 mg) was d i s s o l v e d i n 5 ml C H 2 C £ 2 by a d d i n g 11 mg P r o t o n Sponge. The orange p i n k p r e c i p i t a t e t h a t formed when the s o l v e n t was g r a d u a l l y removed i n vacuo was f i l t e r e d , washed w i t h e t h e r , and a i r d r i e d . A n a l . C a l c d f o r R h C , 0 H 0 1 C £ , N o 0 o S o : C, 35.07; 18 31 4 2 2 2 H, 5.07; N, 4.54. Found: C, 35.13; H, 4.96; N, 4.52. nmr(D 20) 67.9 (m,6,aromatic H); 3.14(s,12,N-CH 3); 3.57(s,6,^-CH^), 2 . 7 0 ( s , 6 , f r e e DMSO). nmr(CD 2C£ 2) 8.0-7.5(m,6,aromatic H); 3.29(d,J=2Hz,12,N-CH 3); 3.47(s,12,S-CH 3). 4.1.2.08 [RhC£(DPS0) 2J 2 To t h e r e d s o l u t i o n , o b t a i n e d by s t i r r i n g RhC£ 3*3H 20 (0.1 g, 0.38 mmol) i n degassed 2 - p r o p a n o l (1.5 ml) and w a t e r (0.4 ml) f o r 30 m i n u t e s , was added DPS0 (0.27 g, 1.3 mmol). The r e s u l t i n g s o l u t i o n d e p o s i t e d r e d c r y s t a l s a f t e r s t a n d i n g f r o m 8 t o 24 h o u r s . The p r o d u c t was f i l t e r e d under A r , washed w i t h degassed 2 - p r o p a n o l and d r i e d i n vacuo. Y i e l d , 65%. An attempt a t r e c r y s t a l l i z a t i o n f rom degassed CH 0C£ o/ether -95-y i e l d e d brown, p a r t i a l l y o x i d i z e d p r o d u c t . A n a l . C a l c d f o r r e d c r y s t a l s o f R h ^ g H ^ C J t ^ O ^ : C, 53.09; H, 3.71; C£, 6.53. Found: C, 52.98; H, 3.83; C£, 7.32. i r , v (SO)1101s; v ( p h e n y l ) 1 0 6 8 s ; v(Rh-C£)<250. 4.1.2.09 [RhC£(DPS0) ( c y c l o o c t e n e ) ] (a) [RhC£(cyclooctene)^]2 (0.1 g, 0.14 mmol) was added t o a degassed s o l u t i o n o f DPSO (1.2 g, 6 mmol) i n 3 ml CH^CJt^ • A f t e r 8 ml o f d r y EtOH were added, t h e s o l u t i o n was warmed t o 35°C, and was c o n c e n t r a t e d by e v a c u a t i o n u n t i l a y e l l o w powder formed. The a i r -s e n s i t i v e m i c r o c r y s t a l l i n e s o l i d o b t a i n e d by c o o l i n g t h e m i x t u r e a t -10°C was f i l t e r e d under A r , washed w i t h d r y EtOH, and d r i e d i n vacuo. A n a l . C a l c d f o r Rh„C._H. oC£ o0„S„: C, 53.28; H, 5.26. Found: C, 52.97; H, 5.26. nmr(CDC£ 3). 67.8-7.2(m,20,phenyl); 3 . 9 ( m , 4 . o l e f i n i c H ) , 2.00 (m,8,C=C-CH), 1.40(m,16,C=C-C-CH). i r , v(SO)1109s; v ( p h e n y l ) 1 0 6 2 s ; v ( C g H 1 4 ) 1180m, 1137m, 1128m,960m,922m,etc.jv(Rh-C£) <250. (b) [RhC£(DPSO) 2] 2 ( 5 7 m § ) w a s added t o 14 y l c i s - c y c l o o c t e n e i n 0.5 ml degassed C Y L ^ I ^ - Degassed EtOH (0.8 ml) was added and p r o c e d u r e (a) was f o l l o w e d . An orange o i l f i r s t formed but soon c r y s t a l l i z e d y i e l d i n g [RhC£(DPSO)(cyclooctene)] . (c) [RhC£(TMSO)(CgH^^)] 2was p r e p a r e d v i a p r o c e d u r e (a) b u t was to o a i r - s e n s i t i v e t o o b t a i n a good a n a l y s i s , i r , v(S0)1118s," v(CgH^ 4) 1175m,1135m,etc.;v(Rh-C£)<250. (d) P r o c e d u r e (a) was a t t e m p t e d u s i n g [RhC£ ^ 2 ^ ) 2] 2 a n a DPSO. An a i r - s e n s i t i v e compound c o n t a i n i n g b o t h c o o r d i n a t e d C2H^ ( i r 1217s, 997s) and DPS0(v(S0)1113s) was i s o l a t e d but- t h e a n a l y s i s c o r r e s p o n d e d -96-t o [ R h C £ ( C 2 H 4 ) 1 • ( D P S O ) Q ? ] , 4.1.2.10 [RhC£(DMSO) 2] 2 (a) To a degassed s o l u t i o n o f e x c e s s s u l f o x i d e (1.5 ml) i n 5 ml of C H 2 C £ 2 was added 0.25 g [RhC£(cyclooctene) ] 2 . A f t e r f i l t r a t i o n under A r , t h e s o l u t i o n was c o n c e n t r a t e d t o 1.5 m l ; 10 ml d r y EtOH was added f o l l o w e d by 4 ml d r y e t h e r , and t h e r e s u l t i n g degassed s o l u t i o n was c o o l e d t o -10°C. The v e r y h y g r o s c o p i c and a i r - s e n s i t i v e orange c r y s t a l s were f i l t e r e d and washed w i t h d r y e t h e r under A r ; t h e y appear t o o c c l u d e DMSO ( v(SO)1020s). A n a l . C a l c d f o r Rh„C 0H„.C£ o0.S,.C„H,S0: C, 17.98; H, 4.49. Found: 2 8 24 2 4 4 2 6 C, 18.04; H, 4.44. nmr(CDC£ 3), 6 2 . 8 ( s , b r o a d , DMSO). i r , v ( S 0 ) 1 1 0 1 s ; P r(CH 3)1020s,1007s,972s,937w;v(Rh-C£)<250(see f i g u r e 4.01). (b) [RhC£(DMSO-dg) 2] 2 was p r e p a r e d by p r o c e d u r e (a) but an orange , e x t r e m e l y a i r - and w a t e r - s e n s i t i v e powder was o b t a i n e d . C a l c d f o r R h 2 C g D 2 4 C £ 2 0 4 S 4 ; C, 15.67; D, 3.91. Found: C, 15.34; D, 4.00. i r , v(SO)1109s,1099s,1089s; 6 g(CD 3)1022m, 1008m; (CD 3)820s,767m; v(Rh-C£)<250 (see f i g u r e 4.01). When t h e m u l l was exposed t o a i r i t t u r n e d from y e l l o w t o b l a c k i n 3 m i n u t e s . 4.1.2.11 [RhC£(DIOS) 2] 2 A degassed s o l u t i o n o f DIOS.H 20(0.25 g, 0.92 mmol) i n 5 m l C H 2 C £ 2 was added t o [RhC£(cyclooctene) 2] 2 under A r . S o l v e n t was removed under vacuum t o y i e l d a red-brown o i l . A f t e r b e i n g washed w i t h d e gassed e t h e r (3x10 m l ) , t h e r e s u l t i n g l i g h t brown powder was t a k e n up i n 1 m l C H 2 C £ 2 and r e p r e c i p i -t a t e d by s l o w l y a d d i n g e t h e r . The p r o d u c t was f i l t e r e d , and d r i e d i n vacuo. Y i e l d , 90%. C a l c d f o r R h C £ S 4 0 g C 1 8 H 3 6 . H 2 0 : C , 31.63; R, 5.85. Found: C, 31.76; - 9 7 -1200 1000 W A V E N U M B E R fc*T') F i g u r e 4.01 (a) I n f r a r e d s p e c t r u m u s i n g N u j o l m u l l o f [RhC£(DMSO) 2] 2.DMSO. 400 "1256 TOo V W t N W M l E R ( C M " ' ) (b) Nujol mull of [RhC£(DMSO-d6)2]2. -98-H, 5.70. nmr(CDC£ 3) 64. 6-4.0 (m,4,methine) ; 3.9-3. 2 (m,6,_S-CH 3+S-CH 2); 3 . 0 ( s , b r o a d , 6 , f r e e S-CH 2); 2 . 6 5 ( s , b r o a d , 8 , f r e e S-CH 3); 1.45(s,12, 0-C-CH 3). i r , v(0H) 3600-3200 mb; v ( S 0 ) + p ( C H 3 > 1 1 5 0 - 1 0 0 0 sb; P r ( C H 3 > 980-950sb,890m;v(Rh-C£)<250. 4.1.2.12 [RhC£(MPS0)(PPh 3)] 2 A degassed s o l u t i o n o f m e t h y l p h e n y l s u l f o x i d e (0.09 g, 0.64 mmol) i n 3 m l C H 2 C £ 2 was added t o [RhC£(cyclooctene)^] 2 (0.11 g, 0.15 mmol). T r i p h e n y l p h o s p h i n e (0.083 g, 0.31 mmol) and t h e n e t h e r (15 ml) were added under A r . When t h i s s o l u t i o n was c o o l e d o v e r n i g h t a t 0°C a i r s e n s i t i v e r e d c r y s t a l s d e p o s i t e d . These were c o l l e c t e d , washed w i t h e t h e r , and d r i e d i n vacuo. Y i e l d , 20%. C a l c d f o r R h ^ g H ^ P ^ ^ O ^ . C H 2 C £ 2 . ( C H 3 C H 2 ) 2 0 : C, 53.25; H, 4.67. Found: C, 54.07; H, 4.82. nmr (CDC£ 3) 67.7-6.9(m,40,phenyl); 5.2(s,2,CH 2C£ 2); 3.43(q,J=7,4,0-CH 2); 2 . 7 ( s , b r o a d , 6 , S - C H 3 ) ; 1 . 1 7 ( t , 6 , 0 - C - C H 3 ) . i r , v (S0)1117S; p r ( C H 3 ) 9 5 5 s . 4.1.3 R e s u l t s and D i s c u s s i o n T a b l e 4.1 l i s t s s o l u t i o n i r d a t a f o r some of t h e compounds s y n t h e s i z e d . A l l c o n t a i n s u l f u r - b o n d e d s u l f o x i d es i n s o l u t i o n . F o r pur p o s e s o f t h e d i s c u s s i o n o f t h e i r s y n t h e s i s and s p e c t r o s c o p i c p r o p e r t i e s , t h e compounds can be c l a s s e d a s : 4.1.3.1. n e u t r a l R h ( I I I ) complexes; 4.1.3.2. d i p h e n y l s u l f o x i d e complexes; 4.1.3.3. a n i o n i c R h ( I I I ) complexes; and 4.1.3.4. R h ( I ) complexes. 4.1.3.1. N e u t r a l R h ( I I I ) Complexes from I s o p r o p a n o l S o l u t i o n s A c o n v e n i e n t p r e p a r a t i o n o f t h e complexes RhC£ 3L 3, L=DMS0, DMSO-d^, TMSO, MPSO, and R-MPTSO was d i s c o v e r e d d u r i n g a t t e m p t s t o g e n e r a t e R h ( I ) -99-complexes f r o m R h C ^ ^ ^ O and s u l f o x i d e s by u s i n g i s o p r o p a n o l as t h e s o l v e n t and r e d u c t a n t ( s e e s e c t i o n 4.1.3.2). The R h ( I I I ) complexes a r e o b t a i n e d i n h i g h y i e l d s (80-95%) s i m p l y by c o l l e c t i n g a f t e r 1 day t h e y e l l o w p r e c i p i t a t e r e s u l t i n g from t h e a d d i t i o n o f 3 e q u i v a l e n t s o f s u l f o x i d e t o one of RhCSc^'^^O, p r e d i s s o l v e d f o r a t l e a s t 15 min i n i s o p r o p a n o l c o n t a i n i n g 20% V/V w a t e r . The brown compounds t h a t o f t e n p r e c i p i t a t e i n i t i a l l y , were found by t h e i r i r s p e c t r a t o c o n t a i n w a t e r o r i s o p r o p a n o l , b u t on s t i r r i n g o v e r s e v e r a l h o u r s , t h e s e i n t e r m e d i a t e s a r e c o n v e r t e d t o R h C i ^ L ^ . C r y -s t a l l i n e samples f o r L=DMS0, DMSO-d^, and TMSO were sometimes d e p o s i t e d on l e a v i n g t h e systems t o s t a n d . The complexes R h C £ 3 L 3 , L=DMS0, DMSO-dg, TMSO, and d i e t h y l s u l f o x i d e have been p r e p a r e d p r e v i o u s l y f r o m h o t aqueous s o l u t i o n s o f NafRhCX,^]. 7 8 9 F o r L=DMS0, c r y s t a l l o g r a p h i c and i r a n a l y s i s show t h a t i n t h e s o l i d s t a t e t h e i s o m e r p r e s e n t i s mer-RhC& 3 (DMSO) ^  (DMSCD) ( f i g u r e 4.02), b u t s o l u t i o n s p e c t r a were n o t examined. When c r y s t a l s o f RhC^ 3(DMS0) 3, p r e p a r e d f r o m i s o p r o p a n o l , o r w a t e r , o r DMSO, a r e d i s s o l v e d i n CHC£ 3 o r Cl^CJc^s t h e i r s p e c t r a show o n l y one b r o a d v ( S 0 ) band and one v ( S 0 ) band ( s ee t a b l e 4.1). The nmr s p e c t r u m ( t a b l e 4.2, f i g u r e 4 .03(b)) d i s p l a y s more t h a n t h e two DMSO m e t h y l r e s o n a n c e s e x p e c t e d f o r a raer-RhC5- 3(DMSO)^(DMSO) s p e c i e s . S e l e c t i v e r e p l a c e m e n t o f t h e oxygen-bonded s CI I £\ Rh S ' | "CI \ F i g u r e 4.02. The l o c a l e nvironment o f Rh i n mer-RhC£ 3(DMS0) 2(OL).. -100-T a b l e 4.1 S o l u t i o n I n f r a r e d D a t a f o r Rhodium S u l f o x i d e Complexes  i n Degassed CH^Cl^. (a) (c) R h ( I I I ) C o m p l e x e s RhC£ 3(DMSO) 2(DMSO) K J RhC£ 3 (TMSO) 2 (TMSO) RhC£ 3 (MPSO) (MPSO) RhC£ 3(MPTSO) 2(MPTSO) RhC£ 3(DPSO) 2(CH 3) 2CHOH [ (DMSO) 2H] [RhC£ 4 (DMS_0) £ ] [NEt 4J[RhC£ 4(DMS0) 2] [P.S.H.][RhC£ 4(DMS0) 2] [(NPS0) 2H][RhC£ 4(NPS0) 2] (c) R h ( I ) C o m p l e x e s [RhC£(DMS0) 2] 2 [RhC£(DMS0-d 6) 2] 2 [P.S.H][RhC£ 2(DMS0) 2] [RhC£(DPS0) 2l 2 [RhC£(DP5K))(CgH l 4)] 2 [RhC£(TMS_0) ( C g H 1 4 ) ] 2 (e) v(SO) 114'2[15],929[17] 1139[13],928[9] 1147[15],932[12] 1154[12],926[10] 1145[20],930[18] 1 1 2 7 s ( d ) 1138[15] 1138[15] 1 1 2 7 [ 1 0 ] , 1 0 1 8 [ 5 ] , 9 3 3 [ 1 0 ] v ( S O ) ; S o l u t i o n under A r 1100[15],1055[10] 1100[20],1053[10] 1095[15] 1125[10] 1105[15] H l O t l O ] Av(SO) (b) 1021s,981s,940m 87,-126 117,-94 968m,957s 969m,959s 102,-113 109,-119 100,-109 1018s,1000m,976m 80 1027s,1017m 80 110,-84 v ( S 0 ) ; under A i r 1140[20],1053[10] 1130[20],1056[10] 1045[10] 1133[20],1022[8] 45 45 40 72 60 89 (a) B r a c k e t e d f i g u r e s g i v e w i d t h o f peak a t h a l f h e i g h t . (b) D e f i n e d as v ( S O ) c o o r d i n a t e d s u l f o x i d e " v( s°)free s u l f o x i d e -(c) Known t o be a m i x t u r e o f i s o m e r s (see t e x t ) . (d) Measured i n N u j o l s i n c e t h i s complex i s i n s o l u b l e i n C H 2 C £ 2 . (e) T h i s compound i s d e s c r i b e d i n s e c t i o n 4.2 but i s i n c l u d e d h e r e f o r c o m p a r i s o n p u r p o s e s . -101-DMSO l i g a n d by o t h e r oxygen d o n o r s , 0=L, w i t h t h e r e t e n t i o n o f mer s t e r e o c h e m i s t r y i n a l l c a s e s ( f i g u r e 4.02, see b e l o w ) , a l l o w s t h e assignment o f t h e prominent nmr peaks o f RhCJl^ (DMSO)^ i n CDCl^. The <53.620 r e s o n a n c e i s a t t r i b u t e d t o DMSO t r a n s t o DMS0_, t h e 3.435 s i g n a l t o DMSO t r a n s t o C£, and t h e 2.860 s i g n a l t o DMSO ( t a b l e 4.2). A 5% i m p u r i t y o f mer-RhC£ 3 (DMSO) ,j c o u l d e x p l a i n t h e s m a l l e r m e t h y l r e s o n a n c e s a t 63.503 and 3.492 ( i n t e n s i t y 2:1) o b s e r v e d i n CDC£ 3, and t h e c o r r e s p o n d i n g d e g e n e r a t e s i n g l e peak a t 63.43 i n CD2C£,.,. T h i s c o u l d a l s o a c c o u n t f o r t h e o b s e r v e d DMSO/DMSC) i n t e g r a t i o n r a t i o , o f g r e a t e r t h a n 2:1, t h a t i s e x p e c t e d f o r mer-RhC£ 3(DMSO) 2(DMSO). The p r o p o r t i o n o f t h i s " i m p u r i t y " i n s o l u t i o n i n c r e a s e s s l o w l y a t 25° o v e r s e v e r a l d a y s , a l o n g w i t h a new s p e c i e s c o n t a i n i n g DMSC) t h a t r e s o n a t e s a t 62.72. A t t e m p t s a t s e p a r a t i n g t h e i s o m e r s by r e p e a t e d r e c r y s t a l l i -z a t i o n s from CH 2C£ 2/ether, o r by t h i n l a y e r chromatography on s i l i c a g e l , f a i l e d . A n a l y t i c a l d a t a , and t h e f a c t t h a t added DMSO has no e f f e c t on th e s p e c t r a , a rgue a g a i n s t t h e p r e s e n c e o f c h l o r i d e - b r i d g e d s p e c i e s . S i n c e p l a n e s o f symmetry o f t h e m o l e c u l e make t h e m e t h y l s o f each DMSO e q u i v a l e n t , m e t h y l i n e q u i v a l e n c e " ^ cannot a c c o u n t f o r t h e e x t r a DMSO peaks. A u t o i o n i z a t i o n t o [RhC£ 2(DMSO) 4] +[RhC£ 4(DMSO) 2]~, s i m i l a r t o t h a t o b s e r v e d f o r t h e a n a l o g o u s d i m e t h y l s u l f i d e (DMS) complex"'""'", i s a l s o n o t 103 c o n s i s t e n t w i t h t h e nmr d a t a . C u r i o u s l y , Rh (I=%) c o u p l i n g t o m e t h y l 12 p r o t o n s i s o b s e r v e d f o r t h e DMS complex r e p o r t e d as mer-RhC£.j (DMS) 3 , but not f o r t h e c o r r e s p o n d i n g DMSO one. T a b l e 4.2 p r e s e n t s nmr d a t a f o r r e a c t i o n 4.1 i n CDC£.j and rough e s t i m a t e s f o r t h e a s s o c i a t e d e q u i l i b r i a c o n s t a n t s , ^. A l l e q u i l i b r i a were shown t o be e s t a b l i s h e d by warming t h e s o l u t i o n s a t 40°C f o r 30 -102-m i n u t e s . A d d i t i o n o f 0=L has l i t t l e i n f l u e n c e on t h e peaks a s s i g n e d t o t h e p o s s i b l e mer-RhC£ 3(DMSO) 3 i m p u r i t y (see f i g u r e 4.03). K 4 1 mer-RhC£ 3(DMS0) 2(DMSO)+0==L v — - — 1 m e r - R h C £ 3 (DMSO) 2 (0=L)+DMSO (4.1) NMR s p e c t r a o f t h e i s o l a t e d compounds, mer-RhC£ 3(DMSO) 2(0=L), where OL i s DMF, N F P ( N - f o r m y l p i p e r i d i n e ) , and P y N 0 ( p y r i d i n e N - o x i d e ) , show o n l y t h e e x p e c t e d two e q u a l l y i n t e n s e , DMSO m e t h y l r e s o n a n c e s . A t h i r t y f o l d e x c e s s o f each o f t h e weaker d o n o r s , DMA and 0PPh 2Me, r e f l u x e d w i t h RhC£ 3(DMSO) 3 i n l^-CpH^CJ!^ y i e l d s m i x t u r e s o f t h e tris-DMSO and t h e d e s i r e d bis-DMSO complexes. No r e a c t i o n was o b s e r v e d w i t h l a r g e e x c e s s e s o f 0 P P h 3 , 0 2SMe 2, and 0 P ( 0 E t ) 3 -I n g e n e r a l , t h e 0=L l i g a n d s c a u s e g r e a t e r s h i f t s i n t h e cis-DMSO r e s o n a n c e s t h a n i n t h e t r a n s . The d i a m a g n e t i c s h i e l d i n g o f t h e c i s -DMSO m e t h y l group by t h e p h e n y l s o f c o o r d i n a t e d OPPh^le i s g r e a t enough t o a l l o w t h e unambiguous a s s i g n m e n t o f t h e u p f i e l d m e t h y l peak t o t h e cis-DMSO i n t h e mer-RhC£ 3 (DMSO) 2 (OL) complexes. The c h e m i c a l s h i f t s o f the DMSO m e t h y l s t r a n s t o 0=L might be e x p l a i n e d by a t r a n s - d i r e c t e d s h i e l d i n g o f t h e s e m e t h y l p r o t o n s by t h e 0=L l i g a n d . Indeed t h e amount o f s h i e l d i n g o f t h e s e m e t h y l p r o t o n s , as j u d g e d by t h e i r c h e m i c a l s h i f t , 13 c o r r e l a t e s r o u g h l y w i t h t h e oxygen donor s t r e n g t h o f 0=L : DMA<DMF< OPPhMe 2=0PPhEt 2=DMSO<OPPh 2Me=NPSO<OP(nBu) 3<PyNO (see t a b l e 4.2). By 14 a n a l o g y , t h e d o w n - f i e l d DMSO m e t h y l peak o f IrC£ 3(DMSO) 2(DMSO) a t 63.66 c o r r e s p o n d s t o DMSO t r a n s t o DMSO^ , and t h e o t h e r a t 3.56, t o DMSO t r a n s t o C L Table 4.2 l (a) H nmr data for RhCl (DMSO). + OL 4.L OL DMSO DMA NFP DMF OPPhMe2 OPPhEt„ OPPh2Me OP(nBu), NPSO PyNO 3 V DMSO trans to OL 63.620 3.67(+0.05) 3.647(+0.027) 3.646(+0.026) 3.63(+0.01) 3.63(+0.01) 3.62(0.0) 3.58(-0.04) 3.62(0.0) 3.57(-0.05) RhCH. (DMSO) „ (OD+DMSO (4.1) DMSO c i s to OL 63.435 3.49(+0.055) 3.437(0.0) 3.447(+0.012) 3.4K-0.025) 3.43(0.0) 3.29(-0.145) 3.37(-0.065) 3.43(0.0) 3.5K+0.075) Peaks of coordinated OL 62.860 3.17,3.08(s,N-CH3) 1.68(s,C-CH3) 3.5(m,N-CH2) ,1.7(in,CH2) 8.30(s,H-C=0) 3.11,3.08(s,N-CH3) 8.27(s,H-C=0) 2.11,Jp_H=14 (d,P-CH3) 7.5-7.9(m,phenyl) 2.2-1.7(m,CH2) 1.14,J=8(t,CH3),7.5-7.9 (m.phenyl) 2.54,J p_ H=14(d,CH 3) 7.5-7.9(m,phenyl) 2.0- 1.5(m,CH2) 0.9,J=7(t,CH3) 3.1- 2.5(m,S-CH2) 2.0-1.8(m,-C-CH2-) ,1.07, J=7(t,CH 3) 9.0(m,ortho) 7.85,7.50(m,meta,para) (b) 4.1 0.01 0.2 0.8 0.3 0.05 0.6 0.9 100 i t—* o i (a) Measured i n CDC*., using the peaks of RhClj (DMSO) as an Internal standard. Frequency s h i f t s from these peaks to corresponding peaks of ,RhCj>3(DMS072(OL) are given in parentheses. A l l the spectra contain the "contaminants" of mer-Rh«3(DMSO) 3 at 63.503 and 3.492 (see figure 4.03). (b) The 2 value i s calculated from one spectrum and i s accurate to ±50%. 0 o (01 031 5 z> Q Q 1 I CO CO * o UjQ LL UJW Q L L Q r y LA w. o <0I Q I co z < DC LUO aico DC5 (a) 3.620 3.435 2.860 O toi Z> Q I CO z < cr O col Q I co o L U O LUCO ecu U - Q (D CM 0. 0-Ol ft (C) (d) F i g u r e 4.03. 63.8-2.3 r e g i o n o f 100 MHz H nmr s p e c t r a u s i n g CDC£ (b)RhC£ 3(DMSO) 3 (c)RhC£ 3(DMSO) 3 +2 0PPhMe 2 (d)RhC£ 3 (1)MS0)3 + 4 .5 JOPPh 2Me ~ - - - - - - - - - - - i 8 6 0 o f (a)RhC£~(DMS0)„+3DMF " J S c a l e marks c o r r e s p o n d t o t h e peaks o f RhC£.j(DMSO)^ a t 63.620, 3.435, and 2. -105-I n a l l c a s e s t h e r a t i o o f m e t h y l peak i n t e g r a t i o n s f o r the s u l f u r bonded DMSO t o t h e oxygen-bonded DMSC) p l u s f r e e DMSO was 2.0. S t r o n g donors such as PPh^, p y r i d i n e , p i p e r i d i n e , and NEt^, as w e l l as g r e a t e r t h a n 1:1 e x c e s s e s w i t h r e s p e c t t o Rh o f 0 P ( n B u ) 3 , PyNO, and NPSO, d i s p l a c e some DMSO as w e l l as DMSO from RhC£ 3(DMSO) 3. Replacement o f DMSO i n RuC£ 2(DMSO) 3(DMSO), w h i c h i s known t o have t h e s o l i d s t a t e s t e r e o c h e m i s t r y d e p i c t e d i n f i g u r e 4.041"', by some 0=L l i g a n d s a i d s i n e x p l a i n i n g t h e complex nmr sp e c t r u m o f the. t e t r a k i s ( d i m e t h y l s u l f o x i d e ) complex ( t a b l e 4.3, f i g u r e 4.05). s CI. I C l ' j o F i g u r e 4.04. The l o c a l e n v ironment o f t h e Ru i n RuC£„(DMS0).. The i n s i t u RuC£ 2(DMS0) 3(DMF) complex a p p e a r s t o have t h e e x p e c t e d s t e r e o c h e m i s t r y w i t h t h r e e DMSO r e s o n a n c e s o f e q u a l i n t e n s i t y a t 63.52 ( t r a n s t o DMF), and 3.43 and 3.32 (two s e t s o f i n e q u i v a l e n t m e t h y l s b o t h c i s t o DMF). Thus RuC£ 2(DMSO) 4 i n CDC£ 3 a p p e a r s t o d i s p r o p o r t i o n a t e i n t o o t h e r i s o m e r s w i t h t h e cis-RuC£ 2 (DMSO) 3 (DMSC)) is o m e r a p p e a r i n g a t 63.49, 3.43, and 3.32. The l a s t two peaks a r e s h i f t e d a s e x p e c t e d t o 63.38 and 3.28, r e s p e c t i v e l y , f o r t h e OPPhMe -106-T a b l e 4.3 1 ( a) H nmr d a t a f o r RuC£ 2(DMSO) 4+0=L*=RuC£ 2(DMSO) (OL)+DMSO (4,2) DMSO DMSO DMSO OL t r a n s t o OL c i s t o 0L of o t h e r i s o m e r s K, „ 4.2 DMSO 3.49[4.1] 3. 43 [.4.1],3.32[3.8] 3. 5 2 [ 3 . 1 ] , 3 . 4 3 [ 3 . 3 ] DMF 3.52(+0.03) 3. 4 3 ( 0 . 0 ) , 3 . 3 2 ( 0 . 0 ) 1 0PPhMe 2 3.49(0.0) 3. 3 8 ( - 0 . 0 5 ) , 3 . 2 8 ( - 0 . 04) 3. 49 0.2 0PPh 2Me 3.49(0.0) 3. 2 7 ( - 0 . 1 6 ) , 3 . 2 1 ( - 0 . 11) 3. 49 0.05 (a) Measured i n CDCJ.3 u s i n g t h e peaks o f RuC£ 2(DMSO)4 a s i n t e r n a l s t a n d a r d s . Frequency s h i f t s from t h e s e peaks t o t h e c o r r e s p o n d i n g peaks o f RuC£ 2(DMSO)3(0L) a r e g i v e n i n round b r a c k e t s . Square b r a c k e t s g i v e t h e number o f p r o t o n s c a l c u l a t e d from peak i n t e g r a t i o n s , (see f i g u r e 4.05). / F i g u r e 4.05. 63.8-2.5 r e g i o n o f 100 MHz H nmr s p e c t r a ( u s i n g CDC£ 3) o f (a) RuCj>2(DMSO)4 + 6 D M F Q>) RuC&2(DMSO)4 (c) RuC£2(DMSO)4 + 4 0PPhMe2 (d) RuCJl-CDMSO^ + 4 OPPl^Me. S c a l e m a r k i n g s r e f e r t o t h e peak p o s i t i o n s of ( b ) . -108-adduct, and to 63.27 and 3.21 for OPPh^ Me although these weak donors seem to give another species with peaks at 63.49 and possibly 3.43. Again, for a l l the spectra examined, the ratios of DMSO to (DMS0+ free DMSO) were approximately 3:1. We have confirmed by nmr studies the earlier observation that the S-bonded ligands of RhC£ 3(DMSO) 3 exchange at different rates'^, and can now state that i t is the DMSO trans to DMSO as well as the DMSO of the supposed mer-RhC£ 3(DMSO) 3 "impurity" that exchange faster than DMSO trans to C£. In fact the 0-bonded DMSO and the DMSO situated trans to i t in mer-RhC£3(DMSO)2(DMSO) appear to exchange at approximately the same rate. For example, after a solution of RhC£ 3(DMS0) 3 (4x10 M) and DMSO-d6(0.4M) in CHC£ 3 is reacted at 35° for 80 minutes, the yellow powder that is precipitated on addition of a large excess of ether contains 75% DMS0-d6 trans to DMSO, <5% DMSO-dg trans to C£, and 85% DMS0-d& (figure 4.06). The "opposite" product containing DMSO-d, trans to C£, o and DMSO trans to DMSO, could be obtained using RhC£,(DMSO-dt),/DMSO mixtures. Such "labelled" compounds could be useful in nmr studies of substitution reactions. O' CI CI Figure 4.06. The main product from the selective exchange reaction of RhC£ 3(DMSO) 3 with DMSO-dg in CHC£ -109-The o t h e r R hC£ 3L 3 complexes (L=TMS0,MPS0, and R-MPTSO) g i v e i r and nmr d a t a c o n s i s t e n t w i t h 2 S- and 1 0-bonded l i g a n d s . The s i m i l a r s p e c t r a o f t h e R-MPTSO complex t o t h a t o f RhCX- 3(DMS0) 3 s u p p o r t t h e same s t r u c t u r a l a s s i g n m e n t : mer-RhC£ 3(S-MPTSO) 2(R-MPTSO)^; o n l y t h e two £>-CH3 ~*"H nmr r e s o n a n c e s e x p e c t e d f o r t h e S-bonded l i g a n d s a r e o b s e r v e d . Use o f r a c e m i c MPSO r e s u l t s i n a m i x t u r e o f " m u l t i s t e r e o -i s o m e r s " , RhC^ 3(R-MPSO)(R-MPSO)(R-MPSO), RhC£ 3(S-MPSO)(R-MPSO)(R-MPSO) e t c . , w h i c h i n t u r n p r o d u c e s t h e complex s e t o f m e t h y l peaks t h a t i s o b s e r v e d . F o r t h e TMSO a d d u c t , a r e m a r k a b l e d o w n f i e l d s h i f t o f 1.6 ppm on c o m p l e x a t i o n i s n o t e d f o r t h e a-methylene p r o t o n w h i c h i s p r o b a b l y endo w i t h r e s p e c t t o an S-bonded TMSO r i n g and hence i n c l o s e p r o x i m i t y t o the m e t a l . S t e r e o c h e m i c a l a s s i g n m e n t s f o r R h C i ^ L ^ , L=TMS0,MPS0, and R-MPTSO, based on v(Rh-C£) a r e r i s k y but would f a v o u r t h e f a c isomer ( a p p r o x i m a t e l y C 3 y , 2 i r bands) o v e r t h e m e r ( a p p r o x i m a t e l y C^y* 3bands). However nmr d a t a , a t l e a s t f o r L=R-MPTS0, a r e more c o n s i s t e n t w i t h t h e mer f o r m u l a t i o n . A t t e m p t s a t i s o l a t i n g complexes f o r R-TBPTSO and S-0TPTS0 were n o t s u c c e s s f u l . 4.1.3.2. D i p h e n y l s u l f o x i d e Complexes When 3 DPSO a r e added t o RhC£ 3'3H 20 p r e d i s s o l v e d i n wet i s o p r o p a n o l , f a i r l y a i r - s t a b l e , r e d c r y s t a l s a r e d e p o s i t e d a f t e r 8-24 h, and t h e s e a r e b e s t f o r m u l a t e d as [RhC£(DPSO) 2] 2 > T h e a i r s e n s i t i v i t y o f s o l u t i o n s o f ={= R-MPTSO becomes S-MPTSO when s u l f u r - b o n d e d t o a m e t a l . -110-t h i s complex i m p l y t h a t R h ( I ) has i n d e e d been p r o d u c e d ; a s i n g l e v(S_0) a t 1116 cm 1 i n C H 2 C £ 2 under A r i s r e p l a c e d by one a t 1045 cm 1 ( f r e e DPSO) on expo s u r e t o a i r . A brown o x i d a t i o n p r o d u c t p r e c i p i t a t e s out o f t h e CR^Ci^ s o l u t i o n and shows no v ( C - H ) , and t h e r e f o r e i s p r e -sumably a s i m p l e c h l o r o o x i d e o f Rh. The o x i d a t i o n s t a t e o f t h e r e d c r y s t a l s was c o n f i r m e d t o be R h ( I ) when t r e a t m e n t w i t h a s t o i c h i o m e t r i c amount o f c i s - c y c l o o c t ene i n CH^Ci!^ y i e l d e d [RhC£ ( c y c l o o c t e n e ) (DPSO) ] 2 • An independent p r e p a r a t i o n o f t h e l a t t e r complex i s d e s c r i b e d i n s e c t i o n 4.1.3.4. The r e d u c t i o n o f R h ( I I I ) p r o b a b l y o c c u r s by r e a c t i o n 4.3, L=DPS0. The d i m e r , [RhCS.(cyclooctene),,] 2> has p r e v i o u s l y been p r e p a r e d a c c o r d i n g t o r e a c t i o n 4.3, L = c i s - c y c l o o c t e n e . RhCX, 3*3H 20 + 2L + ( C H ^ C H O H -> % [ R h C J l L 2 ] 2 + 3H 20.+ 2HC& + ( C H ^ C O (4.3) I f d r y i s o p r o p a n o l i s u s e d , t h e r e a c t i o n y i e l d s a brown powder a n a l y z i n g c o r r e c t l y f o r R h C & 3 ( D P S O ) 2 ( i s o p r o p a n o l ) . I n f r a r e d s p e c t r a s u g g e s t t h a t t h i s powder i s a m i x t u r e o f i s o m e r s c o n t a i n i n g DPSO and DPSC). Exchange p r o c e s s e s i n v o l v i n g t h e c o o r d i n a t e d a l c o h o l a r e s i g n a l l e d by a b r o a d e n i n g o f t h e i s o p r o p y l m e t h y l peaks i n t h e nmr (CDCA^). T h i s compound c o n s t i t u t e s a n i n t e r e s t i n g i n t e r m e d i a t e i n t h e d e h y d r o g e n a t i o n of i s o p r o p a n o l by RhC£ 3.3H 20/DPSO m i x t u r e s ( r e a c t i o n 4 . 3 ) , because when the powder i s suspended i n t h e a l c o h o l c o n t a i n i n g 20% V/V w a t e r under A r , r e d c r y s t a l s o f [RhC£(DPSO) 2] 2 s l o w l y form. The w a t e r added i n t h i s r e a c t i o n may enhance HC& e l i m i n a t i o n and consequent r e d u c t i o n o f the R h ( I I I ) . T r a c e s o f a s i m i l a r a l c o h o l adduct c o n t a i n i n g o n l y 0-bonded s u l f o x i d e were r e c o v e r e d u s i n g t h e S-OTPTSO l i g a n d , b u t t h e c o r r e s p o n d i n g -111-R h ( I ) adduct c o u l d n o t be i s o l a t e d . 4.1.3.3. A n i o n i c R h o d i u m ( I I I ) Complexes The a l k y l c h a i n s o f NPSO may s o l u b i l i z e any Rh s p e c i e s formed i n t h e RhCl^'3H20/isopropanol r e a c t i o n because no p r e c i p i t a t e formed a f t e r s e v e r a l d a y s . A d d i t i o n o f hexane t o a d a y - o l d s o l u t i o n under A r p r e c i p i t a t e d [ (NPSO) 2H] [RhCJ> 4(NPSO) 2] i n low y i e l d ( 4 0 % ) . E q u a t i o n 4.4 r e p r e s e n t s a p o s s i b l e r e a c t i o n scheme a l t h o u g h no R h ( I ) s p e c i e s were d e t e c t e d . The t e t r a c h l o r o r h o d a t e ( I I I ) compound can be p r e p a r e d i n RhC£ '3H-0 + 3 NPSO + i ( C H )„CH0H •|[ (NPSO) 2H] [RhCJl 4(NPSO) ] + y" [RhC£ (NPSO) £] " + - j ( C H 3 ) 2 C O + 3H 20 b e t t e r y i e l d f rom RhC£ 3'3H 20 i n c o n c e n t r a t e d HC£, as i n i t i a l l y d e s c r i b e d f o r t he p r e p a r a t i o n o f t h e DMSO a n a l o g u e , [H(DMS0) 2][RhC£ 4(DMSO)^], by Henbest e t a l . ^ , a l t h o u g h t h e s e w o r k e r s d i d n o t r e p o r t any s p e c t r a l p r o p e r t i e s . B o t h t h e NPSO and DMSO t e t r a c h l o r o r h o d a t e ( I I I ) complexes have s u r p r i s i n g l y i n t e n s e and b r o a d a b s o r p t i o n bands i n t h e s o l i d s t a t e a t 1600-1100 and 900-600 cm" 1 ( s e e f i g u r e s 4.07,4.08) t h a t a r e n o t caused by t h e a n i o n as e v i d e n c e d by t h e spect r u m o f t h e c o r r e s p o n d i n g N E t 4 + s a l t . S a l t s c o n t a i n i n g hydrogen-bonded bases as c a t i o n s a r e known t o cause such b r o a d bands i n t h e s e r e g i o n s " ^ , and so a s t r u c t u r e o f the c a t i o n s was thought t o be [ R 2 S 0 - H - 0 S R 2 ] + . An X- r a y c r y s t a l s t r u c t u r e d e t e r m i n a t i o n o f [H(DMSO)^][RhC£ 4(DMSO) ] , c u r r e n t l y i n p r o g r e s s , has 18 now v e r i f i e d t h i s p r o p o s a l . The s t r u c t u r e , r e f i n e d t o R=2.9%, R =3.3%/ w ^ i s shown i n f i g u r e 4.09. J . . U .1 l-IJ. I 1 I I M i l 1200 WAVENUMBER ( C M F i g u r e 4.07. I n f r a r e d s p e c t r u m of a N u j o l m u l l o f [H(NPSO) ] [RhCS, 4(NPSO) ] The o n l y a b s o r p t i o n i n t h e 4000-1800 r e g i o n i s v ( C H ) . 6.0 7.0 8.0 9.0 10 12 14 16 18 20 2 5 30 35 40 I I I [ I I I I II 1 I I I I I I II [ I I I I M II I I II I 1 II 1 I I II I I II I M I I II I I ! I 1 I I I I! I I I I I I I I i I I I II I I I I H I I II I M I II I I II M I I I i I ! 1400 1200 1000 800 600 400 WAVENUMBER (CM -') F i g u r e 4.08. I n f r a r e d Spectrum of N u j o l m u l l o f [H(DMSO) ][RhCl,(DMSO) ] # -114-F i g u r e 4.09. The c o n t e n t s of a u n i t c e l l i n c r y s t a l l i n e [H(DMS0) 2][RhC£ 4(DMSO) 2] i n c l u d i n g s e l e c t e d bond d i s t a n c e s , c o r r e c t e d f o r t h e r m a l l i b r a t i o n s . One c a t i o n i s not shown. 1.482(3) 1 . 7 8 3 ( 5 ) -j-1.561(4) O -H O 2 . 4 2 0 ( 5 ) ^ / 1.765(5) -1.535(3) o -115-The hydrogen b i s ( d i m e t h y l s u l f o x i d e ) c a t i o n o The v e r y s h o r t 0—0 d i s t a n c e (2.42—2.47A depending on t h e method o f t h e r m a l m o t i o n c o r r e c t i o n ) i s c o n s i s t e n t w i t h t h e p r e s e n c e o f a s t r o n g h y d r o g e n b o n d . 1 7 D i s t i n g u i s h i n g between a s y m m e t r i c a l s i n g l e minimum p o t e n t i a l o r a c l o s e l y spaced d o u b l e minimum p o t e n t i a l f o r 19 t h e p r o t o n i s not p o s s i b l e by t h i s d i f f r a c t i o n s t u d y . The mean o S-0 bond l e n g t h , 1.547(15)A, i s l o n g e r t h a n t h a t o f 20 c r y s t a l l i n e DMSO(1.531 a t -5°C o r 1.471 a t -60°C) , and t h i s i s 21 22 c o n s i s t e n t w i t h p r o t o n a t i o n a t oxygen (see c h a p t e r 1, f i g u r e 1.8). ' 20 The d e c r e a s e i n t h e mean CSO a n g l e (104.1±1.6) from f r e e DMSO(107°) has a l s o been o b s e r v e d b u t not d i s c u s s e d i n 0-bonding o f DMSO t o t r a n s i t i o n 15 23 m e t a l complexes. ' The CSC a n g l e s and C-S l e n g t h s a r e t y p i c a l o f f r e e o r c o o r d i n a t e d DMSO (100°,1.78(1) r e s p e c t i v e l y ) . The s o l i d s t a t e i r bands a s s o c i a t e d w i t h t h e c a t i o n s o f t h e DMSO and NPSO complexes, as w e l l as w i t h t h e c a t i o n s o f [H(DM S O ) 2 ] [ I r C i ^ ( D M S O ) 2 ] 24 and p r o b a b l y H [ IrC£,].4DMS0 , a r e v e r y s i m i l a r (see f i g u r e s 4.07,4.08). o As f o r o t h e r compounds w i t h s t r o n g and s y m m e t r i c a l h y d r o g e n bonds, v (OHO) i s v e r y i n t e n s e , v e r y b r o a d (1600-600 cm "*"), and c e n t e r e d a t a p p r o x i m a t e l y 1000 cm 1 . 1 7 A u n i q u e f e a t u r e o f t h e s u l f o x i d e c a t i o n s i s t h e l o s s o f v ( S 0 ) , e x p e c t e d as a b r o a d peak a t -950 cm 1 t o be c o n s i s t e n t w i t h t h e r e d u c t i o n i n S-0 bond o r d e r t r a n s i t i o n m e t a l complexes w i t h an S-0 ° 15 23 d i s t a n c e o f 1.54A absorb a t t h i s f r e q u e n c y . ' T h i s may be e x p l a i n e d by t h e p r e s e n c e o f t h e o t h e r a n o m a l i e s : t h e w i d e " t r a n s m i s s i o n w i n d o w " 1 7 i n t h e v (OHO) a b s o r p t i o n e n v e l o p e a t 1100-900, a l o n g w i t h t h e enhanced 3. i n t e n s i t y o f t h e 900-600 cm 1 r e g i o n : t h e a p p a r e n t b o r r o w i n g o f v(S0) i n t e n s i t y may w e l l r e s u l t from a F e r m i r e s o n a n c e e f f e c t s u g g e s t e d 14 -116-previously"""' as a p o s s i b l e o r i g i n o f t r a n s m i s s i o n windows o b s e r v e d a l s o , f o r example, i n [ (DMF) 2H] [ P d ^ J l g ] 2 5 , and [H(OAsPh 3) 2 ] 2 [ H g 2 B r 6 ] . 2 6 D i r e c t s p e c t r o s c o p i c o b s e r v a t i o n o f t h e [ H ( N P S O ) 2 ] + c a t i o n i n CHC£ 3 o r t h e [ H ( D M S O ) 2 ] + c a t i o n i n D 20 i s not p o s s i b l e . The s o l u t i o n i r o f t h e fo r m e r s u g g e s t s t h a t HC£ i s e l i m i n a t e d when t h e t e t r a c h l o r o -r h o d a t e s a l t i s d i s s o l v e d , s i n c e [RhCJt.^(NPSO) 2(NPSO) ] a p p ears t o form ( t a b l e 4.1). The DMSO a s s o c i a t e d w i t h t h e c a t i o n o f t h e l a t t e r i n t h e s o l i d s t a t e , appears i n t h e nmr a t t h e c h e m i c a l s h i f t f o r f r e e DMSO i n D 20. S o l u t i o n i r e v i d e n c e f o r a 2:1 adduct o f DMSO w i t h HNCS has J 2 7 been r e p o r t e d . P r o t o n a t e d s u l f o x i d e s have been p o s t u l a t e d as i n t e r m e d i a t e s i n 28 t h e a c i d - c a t a l y z e d d e c o m p o s i t i o n o f s u l f o x i d e s ; p r i o r t o t h e p r e s e n t work o n l y i n d i r e c t e v i d e n c e from s t u d i e s i n magic a c i d e x i s t e d f o r 29 p r o t o n a t i o n a t oxygen. T r a n s - T e t r a c h l o r o - b i s ( d i m e t h y l s u l f o x i d e ) r h o d a t e ( I I I ) A c r y s t a l s t r u c t u r e o f t h e sodium s a l t o f t h i s o c t a h e d r a l a n i o n 30 has been communicated by S o k o l e t a l . , but t h e o n l y f i g u r e s p r o v i d e d o o o were: R=10.3%, Rh-S 1=2.220A, Rh-S 2=2.360A, and Rh-C£=2.320-2.340A. No r e a s o n was g i v e n f o r t h e u n e q u a l Rh-S d i s t a n c e s . I n c o n t r a s t , t h e t r a n s DMSO l i g a n d s i n f i g u r e 4.09 a r e r e l a t e d by a C 2 a x i s o f symmetry, g i v i n g e q u i v a l e n t Rh-S bond l e n g t h s o f 2.322(2) f o r one a n i o n and 2.329(2) f o r t h e o t h e r i n t h e u n i t c e l l . The Rh-C£ d i s t a n c e s , r a n g i n g from 2.331(8) t o 2.371(7), w i t h a mean o f 2.354, a r e s l i g h t l y l o n g e r t h a n t h o s e found by t h e R u s s i a n w o r k e r s . C o n s i s t e n t w i t h t h e i d e a t h a t S-bonding i n c r e a s e s t h e S-0 bond o r d e r o f DMSO ( e x c e p t f o r t h e case o f s i g n i f i c a n t m e t a l -117-+ s u l f u r d^ b a c k b o n d i n g ) , t h e S-0 bond l e n g t h s , 1.482(3) and 1.479(3) o a r e s h o r t e r t h a n t h a t found i n f r e e DMSO, 1.531A. I n our c r y s t a l , t h e a n i o n s o f t h e u n i t c e l l a r e u n d i s t o r t e d o c t a h e d r a , a l t h o u g h one i s d i s o r d e r e d . I t e x i s t s i n two p o s s i b l e o r i e n t a t i o n s o f a s q u a r e p l a n a r arrangement o f c h l o r i d e s , one r e l a t e d t o th e o t h e r by a 16° r o t a t i o n about t h e S-Rh-S a x i s . I f t h e r e were d o u b l e bond c h a r a c t e r i n t h e Rh-S bonds due t o Rhd -> Sd b a c k b o n d i n g , one TT - TT might e x p e c t t h e r e t o be o n l y one o r i e n t a t i o n o f the DMSO l i g a n d s w i t h r e s p e c t t o t h e c h l o r i d e s where optimum o v e r l a p o f such o r b i t a l s c o u l d o c c u r ; t h e e x i s t e n c e o f two d i f f e r e n t o r i e n t a t i o n s o f t h e c h l o r i d e a r r a y s w i t h r e s p e c t t o t h e DMSO l i g a n d s o b s e r v e d i n t h i s c r y s t a l a rgues a g a i n s t b a c k b o n d i n g . o I n a d d i t i o n , t h e Rh-S d i s t a n c e s o f 2.332 and 2.329A a r e much l o n g e r t h a n t h o s e o f some o t h e r Rh-DMSO complexes: e.g. t h e Rh-S t r a n s t o ° 31 py i n RhC£ 3(py) 2(DMS0) i s 2.283A, and t h e Rh-S d i s t a n c e s t r a n s t o DMSO o g and C£ i n RhC£ 3(DMSO) 3 a r e 2.231 and 2.254A, r e s p e c t i v e l y . A s i m i l a r l e n g t h e n i n g o f m u t u a l l y t r a n s S-bonded DMSO was n o t e d f o r t r a n s -PdC£ 2(DMS0) 2 3 2compared t o c i s - P d ( N 0 3 ) 2 ( D M S O ) 2 - 3 3 T h e r e f o r e S-bonded DMSO ap p e a r s t o e x e r t a s u b s t a n t i a l t r a n s i n f l u e n c e by way o f i t s o-34 b o n d i n g o r b i t a l s . I n g e n e r a l t h e R h C £ 3 L 3 complexes, L=DMSO,TMSO,MPSO, r e a d i l y r e a c t 9 w i t h NaC£ i n H 20, o r [NEt^]C£ i n C H 2 C £ 2 o r w a t e r , t o fo r m t h e a n i o n s , trans-[RhC£ 4L 2] . Other s a l t s o f t h e s e a n i o n s can be p r e p a r e d f r o m t h e i r [ H ( R 2 S O ) 2 ] d e r i v a t i v e s by a d d i n g s t r o n g b a s e s , as r e p o r t e d p r e v i o u s l y f o r [H(DMSO) 2][IrC£ 4(DMSO)^ . 1 4 F o r example, a d d i t i o n o f th e n o n c o o r d i n a t i n g base l , 8 - b i s ( d i m e t h y l a m i n o ) n a p h t h a l e n e , t r i v i a l l y -118-c a l l e d P r o t o n Sponge ( P . S . ) , t o t h e NPSO and DMSO Rh a n i o n s , d i s s o l v e d and suspended r e s p e c t i v e l y i n C H 2 C £ 2 , f o l l o w e d by a d d i t i o n o f e t h e r , p r e c i p i t a t e s t h e complex, [P.S.H] [RhCJl^(R^O) ] , where [P.S.H ] + i s p r o t o n a t e d P r o t o n Sponge. S-bonding o f t h e presumably t r a n s s u l f o x i d e s i s o b s e r v e d f o r a l l o f t h e s e s a l t s i n t h e s o l i d s t a t e and i n CR^CJ^ s o l u t i o n . F o r 0.05M [RhC£ 4(DMSO) 2]~in D 20, one s u l f o x i d e i s s u b s t i t u t e d by D 20 i n l e s s t h a n 30 seconds a t 35°C a c c o r d i n g t o e q u i l i b r i u m 4.5. F o r example, b o t h [RhC£ 4(DMS0) 2]~ and [RhCl^(DMSO)(D20)]~ a r e r e c o g n i z e d i n t h e 1 H nmr sp e c t r u m o f t h e [ H ( D M S 0 ) 2 ] + s a l t , by th e m e t h y l peaks a t 63.50 c'4-c' cf I >CI s + D«0 2^ ^ D M S O + S Rh C f I NCI ( 4 . 5 ) and 3.56 r e s p e c t i v e l y ; a v a l u e o f ,.=0.5±0.2M a t 35°C was e s t i m a t e d by a d d i n g known amounts o f DMSO and m e a s u r i n g t h e i n t e n s i t i e s a t t h e two c h e m i c a l s h i f t s . Thus r e a c t i o n (4.5) i l l u s t r a t e s t h e h i g h k i n e t i c t r a n s 35 e f f e c t o f S-bonded s u l f o x i d e s . The mono-aquated s p e c i e s i s s t a b l e f o r weeks i n aqueous s o l u t i o n . The c o r r e s p o n d i n g I r a n i o n s undergo a q u a t i o n a t a s l o w e r r a t e (see c h a p t e r 5 ) . 4.1.3.4. Rhodium(I) Complexes from [RhC£(olef i n ) 2 ] , . , The d i s p l a c e m e n t o f l a b i l e c i s - c y c l o o c t e n e o r e t h y l e n e f r o m t h e t i t l e R h ( I ) d i m e r s i n C H 2 C £ 2 by donor l i g a n d s , L, p r o v i d e s c o n v e n i e n t r o u t e s t o [RhC£L 2] 2 and RhCJlI^complexes when L i s a p h o s p h i n e , a r s i n e , -119-36 e t c . . However, even w i t h a t e n f o l d e x c e s s o f DPSO and TMSO pe r rhodium atom, o n l y [RhC£(olefin)L]^ complexes c o u l d be i s o l a t e d , where L i s t h e S-bonded l i g a n d ( r e a c t i o n 4.6). S i m i l a r mixed o l e f i n - c h i r a l s u l f o x i d e P t complexes, u s e f u l i n t h e s t u d y o f asymmetric i n d u c t i o n (see c h a p t e r 1.3.4), have been c h a r a c t e r i z e d 37 by d i f f r a c t i o n s t u d i e s . (4.6) O t h e r s u l f u r - b o n d e d mixed l i g a n d Rh complexes, s u c h as [RhC£(MPSO)-( P P h ^ ) ^ * can a l s o be p r e p a r e d . [ R h C M D M S O ^ ^ a n ^ i t s DMSO-d^ a n a l o g u e a r e p r e p a r e d by u s i n g an e x c e s s o f s u l f o x i d e l i g a n d . The complexes a r e e x t r e m e l y h y g r o s c o p i c and a i r - s e n s i t i v e i n t h e s o l i d s t a t e ; on e x p o s u r e t o 0^, t h e v ( S 0 ) a t 1100 cm 1 i s r a p i d l y r e p l a c e d by one a t 1140 cm 1 w h i c h must p e r t a i n t o a h i g h e r o x i d a t i o n s t a t e , R h ( I I ) o r R h ( I I I ) . F o r m a t i o n o f s u l f o n e , ( C H ^ S O ^ was n o t d e t e c t e d . I n degassed w a t e r , t h e complexes r a p i d l y d i s p r o p o r t i o n a t e 38 t o Rh m e t a l and a g r e e n f i l t r a t e l i k e l y c o n t a i n i n g R h ( I I ) . The C H 2 C £ 2 s o l u t i o n i r s p e c t r u m o f [RhC£(DMSO) 2] ( t a b l e 4.1) c o n s i s t s o f peaks f o r S-bonded and f r e e DMSO, b u t n o t 0-bonded DMSO. The nmr s p e c t r u m i n CDC£.j i s a s i n g l e b r o a d peak a t 62.80, a c h e m i c a l s h i f t i n t e r m e d i a t e between t h a t o f f r e e and S-bonded l i g a n d , and t h i s c o n f i r m s t h a t d i s s o c i a t i o n o f DMSO i s o c c u r r i n g , and i t i s f a s t on t h e nmr t i m e 30 s c a l e . Such l a b i l e b e h a v i o u r , n o t o b s e r v e d f o r t r a n s - P d C ^ t D M S O ^ . w o u l d i n p a r t a c c o u n t f o r t h e r e a c t i v i t y o f t h e R h ( I ) complex. -120-A complex f o r m u l a t e d as [RhC£(DIOS)^]^• ^ I^O can a l s o be p r e p a r e d v i a t h e r h o d i u m ( I ) o l e f i n p r e c u r s o r . T h i s compound g i v e s no t e r m i n a l -1 40 v(Rh-Cd) and no v(SO) w h i c h w o u l d be e x p e c t e d i n t h e i r a t >250 cm and -930 cm \ r e s p e c t i v e l y , a l t h o u g h v(S_0) and v(S0) o f f r e e s u l f o x i d e a r e p r e s e n t ; a s t r u c t u r e can be e n v i s a g e d w i t h " d a n g l i n g " , monodentate DIOS l i g a n d s , a n a l o g o u s t o t h a t o f m e t a l complexes w i t h d a n g l i n g DIOP 41 l i g a n d s . A d e f i n i t i v e i n t e r p r e t a t i o n o f t h e nmr d a t a cannot be made due t o exchange p r o c e s s e s t h a t must be o c c u r r i n g , but s u l f u r - b o n d e d s p e c i e s a r e o b s e r v e d . Thus R h ( I ) complexes w i t h t h i s S-bonded c h e l a t i n g l i g a n d a r e v e r y l a b i l e . A l l o f t h e R h ( I ) compounds d i s c u s s e d h e r e have been f o r m u l a t e d as di m e r s s o l e l y on t h e b a s i s o f t h e agreement o f such s t r u c t u r e s w i t h t h e a n a l y t i c a l d a t a ( 3 - c o o r d i n a t e R h ( I ) i s r a r e ) , and t h e i r s p e c t r a w h i c h do n o t show t e r m i n a l v(Rh-C£) s t r e t c h e s , n o r m a l l y e x p e c t e d a t >250 cm 4.1.3.5. The N a t u r e o f R h o d i u m - S u l f u r Bonding i n S u l f o x i d e Complexes S e v e r a l t r e n d s a r e a p p a r e n t f r o m some s p e c t r o s c o p i c and s t r u c t u r a l d a t a g i v e n i n t a b l e 4.4 f o r t h e DMSO complexes d e s c r i b e d i n t h i s work and f o r some o t h e r DMSO complexes o f t h e p l a t i n u m m e t a l s . The S-0 bond o r d e r i n c r e a s e s from about 2 ( t h a t o f f r e e s u l f o x i d e ) i n t h e F e ( I I ) and th e f i r s t R u ( I I ) compound, t o p r o b a b l y a l m o s t 3 f o r t h e AuC£ 3(DMS0) complex; t h e s e extremes can be r a t i o n a l i z e d s i n c e i n t h e Fe and Ru syst e m s , m e t a l d^ •> s u l f u r d^ ba c k b o n d i n g i s o p t i m i z e d ( f i g u r e 4.10, I ) and competes s u c c e s s f u l l y w i t h oxygen P^ s u l f u r d^ m u l t i p l e b o n d i n g , whereas f o r t h e Au system, t y p e I I I b o n d i n g i s l i k e l y a pproached due t o t h e g r e a t e r e l e c t r o n e g a t i v i t y o f A u ( I I I ) . - 1 2 1 -© I I F i g u r e 4.10. The range o f b o n d i n g modes f o r S-bonded s u l f o x i d e s . The o t h e r complexes l i s t e d , i n c l u d i n g t h o s e o f Rh, a r e l i k e l y o f i n t e r m e d i a t e t y p e I I b o n d i n g w i t h l i t t l e m e t a l t o s u l f u r b ack-b o n d i n g : g e n e r a l l y i t i s e x p e c t e d t h a t t h e l a r g e r t h e Av(SO) v a l u e , t h e s t r o n g e r w i l l be t h e M-S bond (a s h o r t e r M-S bond) and, o f c o u r s e , t h e s t r o n g e r t h e S-0 bond. Thus t h e S-M bond s t r e n g t h s , based g on A v ( S O ) , f o r t h e n e u t r a l d complexes i n t a b l e 4.4 d e c r e a s e i n t h e o r d e r A u ( I I I ) > P t ( I I ) : : : P d ( I I ) > R h ( I ) w h i c h i s i n k e e p i n g w i t h a r e l a t i v e l y " h a r d " 1 s u l f u r donor o f s u l f o x i d e s . The r e l a t i v e l y weak DMSO-Rh(II) a d d u c t , i n terms o f Av(SO), i s p r o b a b l y a r e s u l t o f t h e h i g h t r a n s i n f l u e n c e o f t h e m e t a l - m e t a l bond."^ The Rh complexes s y n t h e s i z e d i n t h e p r e s e n t work show t h e e f f e c t o f t h e f o r m a l o x i d a t i o n s t a t e o f t h e m e t a l on v ( S 0 ) . N e u t r a l R h ( I I I ) complexes o f DPSO,TMSO, and DMSO ( c f . t a b l e 4.1) a b s o r b i n t h e i r a t 30 t o 40 cm 1 h i g h e r , and p r o b a b l y form s t r o n g e r M-S bonds, t h a n s i m i l a r R h ( I ) a d d u c t s . The Av(SO) s e r i e s : 95,108 cm" 1 f o r [ R h C £ L 5 ] 2 + , 80,95 cm" 1 f o r RhCji^L^, and 65-85 cm 1 f o r [RhCJl^L^] , r e v e a l s t h e e x p e c t e d i n f l u e n c e on v(SO) o f c h a r g e on t h e complexes. -122-T a b l e 4.4 P h y s i c a l D a t a f o r S u l f u r - B o n d e d DMSO Adduct s Complex A v ( S O ) ( a ) r ( S - 0 ) ( b ) r ( M - S ) ^ R e f e r e n c e f r e e DMSO 0 1.531 20 [ F e ( C N ) 5 ( D M S 0 ) ] 3 _ 15 5 [ R u ( N H 3 ) 5 ( D M S 0 ) ] 2 + 0 1.53 2.19 4 fac-[RuC£ 3(DMS0) 3]~ 45 1.49 2.26 42 cis-RuC£ 2 (DMSO) 3(DMSO) 35,65 1.48 2.27 15 [RhC£(DMS0) 2J 2 46 t h i s work RhC£(C0)(DMSO) 2 52,62 43 [ R h ( 0 A c ) 2 ( D M S 0 ) ] 2 31 44 t r a n s - [ RhC£ 4 (DMSO) ] " 65-85 1.47 2.29 8 , t h i s work mer-RhC£ 3 (DMSO) 2 (DMSO) [RhC£(DMSO) 5] 2 + 80,95 1.43 2.24 7 , t h i s work 95,108 45 trans-PdC£ 2 (DMSO) 61 1.47 2.29 32 c i s - P d ( N O 3 - ) 2 ( D M S 0 ) 2 81,102 1.46 2.24 33 cis-[Pd(DMSO) 2(DMSO) ] 2 + 85,95 39,46 cis-[IrC£ 4(DMSO) 2]~ 45,85 1 4 , c h a p t e r 5 t r a n s - [ IrC£ 4 (DMSO) 2 ] ~ 70 1 4 , c h a p t e r 5 mer-IrC£ 3(DMSO) (DMSO) 85 14 IrC£ 3(DMS^0) 3 95 14 I r ( C 1 5 H 1 3 0 ) C £ 2 (DM±>°) 2 72 1,45 2.235 4 7 , c h a p t e r 5 cis-PtC£ 2(DM_SO) 2 80,105 1.46 2.235 48 cis-[Pt(DMSO) 2(DMSO) ] + 88,99 46 AuC£ 3(DMS0) 143 49 (a) Av(SO)=v(S0)-1055 ( f r e e DMSO) i n cm 1 . Data r e f e r t o N u j o l m u l l s . (b) The averaged S-0 bond d i s t a n c e f o r DMSO i n t h e m o l e c u l e ( A ) . (c) The aver a g e m e t a l - s u l f u r d i s t a n c e i n A. (d) C 1 5 H 1 3 0 i s b e n z y l a c e t o p h e n o n e c h e l a t e d t o I r by oxygen and b e n z y l . c a r b -123-4.2 R e a c t i o n s o f R h o d i u m - S u l f o x i d e Complexes w i t h Hydrogen; A t t e m p t s t o Form M e t a l - H y d r i d e Complexes. 4.2.1. I n t r o d u c t i o n M e t a l - h y d r i d e f o r m a t i o n i s a c r u c i a l s t e p i n m e t a l - c a t a l y z e d homogeneous h y d r o g e n a t i o n . Thus i f a Rh s u l f o x i d e complex i s o b s e r v e d t o undergo such a r e a c t i o n , i t has p r o m i s e as a p o t e n t i a l c a t a l y s t . H y d r i d e complexes can be g e n e r a t e d from R h ( I I I ) and R h ( I ) complexes by t h e modes of H 2 a d d i t i o n d i s c u s s e d i n c h a p t e r 1.3: (1) base-promoted h e t e r o l y t i c c l e a v a g e o f H 2 ( e q u a t i o n 4.7, c f . e q u a t i o n s 1.05,1.08 i n f i g u r e 1.5); (2) o x i d a t i v e a d d i t i o n R h ( I I I ) + H 2 > [ R h ( I I I ) - H ] ~ + H + (4.7) o f HX, X=H,C£,etc. ( r e a c t i o n 4.8, c f . e q u a t i o n s 1.12,1.15). Rh(I)+HX ->• Rh ( I I I ) (X) (H) (4.8) 4.2.2 E x p e r i m e n t a l The H e t e r o l y t i c C l e a v a g e o f Hydrogen 4.2.2.1 R e a c t i o n s of RhC&^L^: Hydrogen u p t a k e s by s o l u t i o n s w i t h d r y DMA, o r 1,2-02^0^2 d r i e d w i t h P 20,-,as s o l v e n t s , were measured a c c o r d i n g t o t h e p r o c e d u r e d e s c r i b e d i n c h a p t e r 2. P r o t o n Sponge ( P . S . ) , 1 , 8 - b i s -( d i m e t h y l a m i n o ) n a p h t h a l e n e was s u b l i m e d b e f o r e u s e . 4.2.2.2 P r e p a r a t i o n o f [P.S.H] [RhCJt.,, (DMSO) Q] : D u r i n g t h e measurement of t h e H 2 u p t a k e o f a 1,2-C 2H 4CJt- 2 s o l u t i o n (5 ml) o f RhC£ 3(DMSO) 3 (0.095 g, 0.21 mmol) and P r o t o n Sponge (0.046 g, 0.21 mmol) a t 30° and 1 atm, a v e r y a i r - s e n s i t i v e y e l l o w p r e c i p i t a t e formed a f t e r 50 m i n u t e s . The same compound -124-can a l s o be p r e p a r e d by f i r s t a d d i n g 0.10 g P.S. t o a degassed s u s p e n s i o n o f 0.19 g RhC£ 3(DMSO) 3 i n 3 m l CH 2C& 2 a t 30° and 1 atm, and t h e n s t i r r i n g t h e s o l u t i o n v i g o r o u s l y f o r 40 m i n u t e s , a l t h o u g h o c c a s i o n a l l y t h e compound does not p r e c i p i t a t e . A f t e r l h t h e s u s -p e n s i o n was c o o l e d , and t h e n f i l t e r e d under A r . The compound was washed w i t h 1 m l c o l d , degassed C H 2 C £ 2 , and d r i e d i n vacuo. Y i e l d , 20%. A n a l . C a l c d f o r RhC g H C £ 2 N 2 0 2 S 2 : C, 39.63; H, 5.73; N, 5.13. Found: C, 39.21; H, 5.73; N, 4.83. nmr(CDCJ^/(CD 3> 2C0) 68.0-7.5 (m,6,aromatic H ) ; 3.32(s,broad,18,DMSO and N-CH 3); 2 . 6 0 ( s , 6 , f r e e DMSO); peaks due t o i m p u r i t i e s o f C H 2 C £ 2 , and some Rh-DMSO complex ( a t 63.50,2.63) were p r e s e n t i n m i n o r amounts, i r ( t h e N u j o l m u l l t u r n e d from y e l l o w t o brown w h i l e t h e s p e c t r u m was r e c o r d e d ) , 1230m, 845s ( p r o t o n a t e d P r o t o n Sponge, [ P . S . H ] + ) ; v(S_0)1138; v (Rh-C£) 352. S o l u t i o n i r d a t a a r e l i s t e d i n t a b l e 4.1. The hydrogen u p t a k e f o r s u c h a r e a c t i o n i s p l o t t e d i n f i g u r e 4 Uptakes u s i n g a P.S./Rh r a t i o o f 1 o r 2 b o t h r e s u l t i n a H 2/Rh r a t i o o f 0.39 4.2.2.3 R e a c t i o n o f RhC& 3(DMS0) 3 w i t h P r o t o n Sponge under A r : When P.S.(0.17 g, 0.80 mmol) was added t o a degassed s u s p e n s i o n o f RhCJL 3(DMSO) 3 (0.44 g, 1.0 mmol) i n 8 m l CH 2C^ 2 a t 38°C, a r e d s o l u t i o n r e s u l t e d . A f t e r 11 h o u r s o f r e a c t i o n , t h e s o l u t i o n was f i l t e r e d . A sample was w i t h d r a w n under A r , and i t s nmr s p e c t r u m was r e c o r d e d ( f i g u r e 4.12). Degassed EtOH (8 ml) was added, and t h e volume o f s o l v e n t was s l o w l y r e d u c e d by e v a c u a t i o n u n t i l an orange powder formed (0.05 g ) . T h i s p r o d u c t was c o l l e c t e d , and r e c r y s t a l l i z e d t w i c e f r o m CH 2C£ 2/Et0H. A n a l . Found: C, 35.35; H, 4.83; N, 4.61. i r ( N u j o l ) , v ( S 0 ) 1 1 2 8 s ; v ( c o o r d i n a t e d P.S.)1635w, 1605m, 1590m, 1022s, 825s; v ( [ P . S . H ] + ) 840m n m r ( C D 2 C J l 2 ) , see t a b l e 4.5, f i g u r e 4.13. T h i s compound -125-F i g u r e 4.11 (a) The h y d r o g e n u p t a k e o f RhCJt.3(DMSO)3+2 P r o t o n Sponge i n 1,2-C2H4CJL 2 a t 30°C. (b) A n o t h e r e q u i v a l e n t o f RhC£3(DMSO) 3 was added a t t h i s p o i n t . The f i n a l t o t a l Rh c o n c e n t r a t i o n was 6 . 4 x l O - 2 M (5 ml s o l v e n t ) . 0 . 8 1 1 1 1 i 1 1 1 r * I M E ( S E C ) -126-Table A.5 nmr data for the reaction of Proton Sponge with RhCi^DMSO)^ in CD 2C£ 2. Species Rh(I)-DMSO+free DMSO Rh-(DMSO) Rh-(DMSO) / Coordinated Proton Sponge ^ Derivative Peak Peak PosJ.tj.on(5) and Integration(no. of "''H) Type (a) 0.8 P. S. l^+RhCl.^ ( D M S O ) 0 . 8 P.S. + Reaction after l l h i n CH2C&2 at 38 c s,br s s m,C=C-H dof d,J1=2,J2=7Hz s,br,N-CH3? s,br,N-CH3 s,N-CH3 2.60(7) 3.49(4) 3.45(6) 7.7-7.5(2.1) 7.0 ( e ) ( 0 . 4 ) 5.15 ( e )(0.75) 3.79(2.5) 3.44(1.5) Orange RhCfl., (DMSO-d,)„ Crystals'-^ Crystals l " - 1 3.50(3) 3.54(11) 7.7-7.5(5) 7.0 (1) 5.15(1.5) 3.75(6) 3.47(3) 7.7-7.5(5) 7.0 (1) 5.15(1.3) 3.75(6) 3.47(2.6) Protonated Proton Sponge s,br,N-H m,C=C-H d,J=2Hz,N-CH, 18.3(0.5) ( e ) 8.0-7.7(2.5) 3.29(5) (f) (f) 8.0-7.5(1.2) 8.0-7.5(1.3) 3.29(6) 3.29(3.4) (a) s=singlet, d-doublet, m=multiplet, br=broad. (b) The stoichiometry of the reaction was determined by nmr. P.S. added in excess of 0.8 moles per mole Rh remains unreacted. (c) R e c r y s t a l l i z e d several times from C^CJi^/EtOH (see figure 4.13). (d) R e c r y s t a l l i z e d from DMSO-d^/acetone (see figure 4.14). (e) Observed using CD2CJ,,,. (f) Solution was too d i l u t e to observe thi s peak. F i g u r e 4.13. 100 MHz H nmr spectrum ( u s i n g CD C£ 2> o f orange c r y s t a l s from t h e r e a c t i o n i n CH.CJl^ o f 0.8 P.S. + RhCjU (DMSO). I m p u r i t i e s i n t h e C D 2 C £ 2 a r e the peaks a t 65.35 and 1.67 OQ c tD U l 3 • ro o UJ Cu o O Ln n a >* rt S Ln H* 3 n • O N O 3 rO U l h-1 o ra • Ml n 3 o 3 • i-t o 03 CO TJ 13 ^ ' • ro w n • rt LO I-t • + s 3 U l 3* /-> & n c ^ CO LO H-3 • a oo s U l c/i o rt o a '—s 1 r-o M rt ON O v - / h o WLo w *—- • O l - h w • >! rt t—1 rt 3-^—s i-t ro Cu CU o 3 O fD ro i-t rt O Cu O C 3 3 CO HQ ro ro ro o 1—' cu i-t • ?r ^  U l co cn U l rt cu cu i t h - 1 s-ro co pu H i o> i-t I-I Ul o • 3 rt ON U i rt " 3* ro •o 3 CO [P.S.H] PS. DERIVATIVE PS DERIVATIVE ^>PS. DERIVATIVE . — [ P S . H J + c - 6 3 1 --130-i s s p a r i n g l y s o l u b l e i n CH 2C& 2, l s v e r y s o l u b l e i n DMSO, and r e a c t s w i t h H 20. A f u r t h e r p r e c i p i t a t e o b t a i n e d from t h e mother l i q u o r i s a complex m i x t u r e . The i n i t i a l p r e c i p i t a t e d e s c r i b e d above can a l s o be r e c r y s t a l l i z e d by d i s s o l u t i o n i n a minimum amount o f DMSO f o l l o w e d by a d d i t i o n o f a c e t o n e . nmr(CD 2C£ 2), s e e t a b l e 4.5, f i g u r e 4.14, i r as above. A t t e m p t s a t chromatography of t h e p o l a r p r o d u c t s u s i n g a l u m i n a f a i l e d . O x i d a t i v e A d d i t i o n R e a c t i o n s IL, u p t a k e measurements were co n d u c t e d on some o f t h e R h ( I ) compounds s y n t h e s i z e d , and on some t h a t were g e n e r a t e d i n s i t u . The l a t t e r t y p e i n v o l v e d f i r s t d r o p p i n g a b u c k e t c o n t a i n i n g a R h ( I ) precursor([RhC£(C 0rL, , ) „ ] „ o 1 4 Z 1 [ R h ( N B D ) 2 ] P F 6 , [RhC£(C0) 2] 2) i n t o a degassed s o l u t i o n o f t h e s u l f o x i d e d i s s o l v e d i n a s o l v e n t o f h i g h v apour p r e s s u r e (DMA, 2-methoxyethanol (ME)), a l l under vacuum a t 20-50°C. A f t e r t h e rhodium complex d i s s o l v e d , hydrogen was i n t r o d u c e d , t h e f l a s k was shaken and t h e u p t a k e r e c o r d e d . The r e s u l t s a r e l i s t e d i n t a b l e 4.6. Some r e a c t i o n s w i t h HC£, added i n t h e form of t h e c r y s t a l l i n e HC£"DMA a d d u c t ^ 1 , were c a r r i e d out by r a p i d l y w e i g h i n g t h i s h y g r o s c o p i c compound and a d d i n g i t t o a S c h l e n k tube c o n t a i n i n g a R h ( I ) complex i n degassed s o l u t i o n . 4.2.2.4 P r e p a r a t i o n o f [ R h ( M S E ) 2 ] P F 6 ; M S E = m e s o - l , 2 - b i s ( m e t h y l s u l f i n y l )  e t h a n e : [ R h ( N B D ) 2 ] P F & (30 mg, 0.070 mmol) was added t o MSE (40 mg, 0.2 mmol) i n 4 m l o f degassed 2-methoxyethanol. A f t e r a few m i n u t e s , was i n t r o d u c e d and t h e s o l u t i o n was v i g o r o u s l y s t i r r e d f o r 30 min a t 30°C. The p a l e y e l l o w , m i c r o c r y s t a l l i n e p r e c i p i t a t e , w h i c h was f i l t e r e d , washed w i t h e t h e r , and d r i e d i n v a c u o , i s n o t a i r s e n s i t i v e i n t h e s o l i d s t a t e . A t 190-195°C i n -131-a i r t h e compound t u r n s brown. Y i e l d , 90%. A n a l : C a l c d f o r RhCgH^S^O^PF^.: C, 17.27; H, 3.62. Found: C, 17.16; H, 3.56. nmr(DMSO-dg), 6 3 . 4 0 ( s , b r o a d , 8 , C H 2 - S ) ; 3.07(s,broad,12,CH 3-S). i r ( N u j o l ) , v (SO)1110s, 1085s; v ( o t h e r MSE modes)1406s, 1322s, 1254m, 1130s, 1015m, 975s, 960m; v ( P F 6 ) 840s, 560s. 4.2.3 R e s u l t s and D i s c u s s i o n 4.2.3.1 The H e t e r o l y t i c C l e a v a g e o f by RhC& 3 ( s u l f o x i d e ) ^ Complexes. The RhC^^L^ complexes, L = s u l f o x i d e , a r e i n e r t t o r e a c t i o n w i t h 1 atm H„ i n 1,2-C„H,C£„ o r CH„C£„ a t 30-50°C. However i f 2 moles NEt„ a r e 2 2 4 2 2 2 3 added, t h e RhC£ 3(DMSO) 3 complex ( t h e o n l y one t e s t e d ) t a k e s up one mole of H 2 w i t h a c o n c o m i t a n t s o l u t i o n c o l o u r change from y e l l o w t o deep brown. I t a c o n i c a c i d and p r o b a b l y s u l f o x i d e ( s u l f i d e s were s m e l l e d ) a r e s l o w l y h y d r o g e n a t e d c a t a l y t i c a l l y by t h i s s o l u t i o n under t h e same c o n d i t i o n s . An u p t a k e of one mole of H 2 by R h C i ^ L ^ a l s o o c c u r s i n t h e b a s i c s o l v e n t DMA. These d a t a , l i s t e d i n t a b l e 4.6, a r e c o n s i s t e n t w i t h t h e b a s e -promoted h e t e r o l y t i c c l e a v a g e of H 2 , r e a c t i o n 4.7, but s i n c e R h ( l I I ) - H s p e c i e s were n o t d e t e c t e d by s o l u t i o n nmr and i r s t u d i e s , r a p i d e l i m i n -a t i o n o f HC£ t o form R h ( I ) s p e c i e s i s i n d i c a t e d : RhC£ 3(DMSO) 3+H 2 "H-Rh(HI)-C£" R h ( I ) C o n s i s t e n t w i t h t h i s , t h e r e d u c t i o n o f RhC£ 3(DMSO) 3 i n t h e p r e s e n c e o f 1 mole N E t 3 r e s u l t s i n a r a t i o o f H 2/Rh o f o n l y 0.5: RhC£ 3(DMSO) 3+%H 2 — % R h C £ 3 ( D M S O ) 3 + " 5 5 R h ( I ) " A l t h o u g h N E t 3 c o o r d i n a t e s t o RhC£ 3(DMSO) 3 ( s e c t i o n 4.1.3.1), i t must s t i l l be a v a i l a b l e f o r r e a c t i o n w i t h HC£. -132-Table 4.6 Complex Maximum Total Concen- Rate of moles tration Solvent Temp. Uptake H2/Rh<a) 10 M °C 105M/sec RhCS.3(DMSO)3 6 1,2-C2H4C42 30 0 0 Rh« 3(DMSO) 3+2.0 P.S. (+>2P.S. 32 1,2-C2H4CJ>2 30 6.0 0.39 [RhC£,(DMSO) (acetone) lPF, I X 'y J 6 27 1,2-C2H4CS.2 30 4.3 0.9,metal at RhC^3(DMSO)3+2NEt3 22 1,2-C 2H 4C£ 2 30 6.3 4000s 1.1 [RhCJ>4(DMSO)2]NEt4+2P.S. 15 1,2-C 2H 4C£ 2 30 0 0 RhCi3(DMSO)3 6 DMA 30 2.0 1.0 RhCJl3(MPSO)3 6 DMA 40 2.5 1.2 [RhC£(DPSO)2]2 11 DMA 40 2.5 1.5,metal at (c) 1000s [Rh(NBD)2]PF&+1.3MET+2.6P.S, 5 ME 20 (d) +2MSE 6.5 ME 20 (d) 2(e) +2.4DIOS 7.4 ME 50 0.8 0.5,metal at +1.2PTSE 5 ME 20 (d) , ^ 400s (d) metal at [RhCJl (CgH 1 4) 2] 2 ( f }+2. 4DI0S 100s 8 DMA 53 0.9 1.2 ( 8 ) (a) No mention of metal formation means that the system was stable with respect to H2 reduction for at least 30 min. (b) Prepared by adding AgPFg to RhC*3(DMSO)3 in acetone, filtering the AgCJi, removing the acetone in vacuo, and adding 1.2-C2H4C&2-(c) Without adding Proton Sponge, the ligand does not dissolve. (d) These reactions were monitored by using an ordinary Hg manometer. Only the MSE system gave a measurable uptake. (e) [Rh(MSE)2]PF6 precipitated at this point. (f) DIOS was the only chelating ligand that solubilized this compound in DMA or ME. (g) The hydrogenation of cyclooctene, rapid i n i t i a l l y , had almost stopped at the point (1000s). -133-F i n a l c o n f i r m a t i o n o f t h e r e d u c t i o n p r o c e s s i s t h e i s o l a t i o n o f a R h ( I ) compound f o r m u l a t e d as [P.S.H.][RhC& 2(DMSO)^]. L i k e [RhC£(DMS0) 2] 2, t h e RhC£ 2(DMSO) ~ a n i o n goes t o m e t a l and presumably R h ( I I ) when d i s s o l v e d i n degassed H o0. The H„ r e d u c t i o n o f RhC£„(DMS0) o i n t h e p r e s e n c e o f P.S. i s c o m p l i c a t e d by s i d e r e a c t i o n s i n c l u d i n g t h e c o o r d i n a t i o n o f t h e b a s e t o Rh ( s e e b e l o w ) , and so an u p t a k e o f o n l y 0.4 moles H 2 p e r Rh i s measured, and a poor y i e l d o f t h e R h ( I ) compound i s o b t a i n e d . The u p t a k e p l o t s show an i n d u c t i o n p e r i o d ( f i g u r e 4.11), w h i l e f u r t h e r a d d i t i o n o f RhC£ 3 (DMSO) 3 t o t h e f i n a l r e a c t i o n s o l u t i o n r e s u l t s i n no i n d u c t i o n p e r i o d b e f o r e subsequent H 2 u p t a k e . T h i s s u g g e s t s t h a t t h e R h ( I ) p r o d u c t may be i n v o l v e d i n an a u t o c a t a l y t i c s t e p o f t h e o v e r a l l r e a c t i o n ; s u c h b e h a v i o u r i s w e l l e s t a b l i s h e d f o r t h e 52 CO r e d u c t i o n o f R h ( I I I ) t o R h ( I ) complexes and t h e H 2 r e d u c t i o n o f 53 Ru(IV) t o R u ( I I I ) complexes. I n s e c t i o n 4.1.3.3. i t was dem o n s t r a t e d t h a t C£~ s u b s t i t u t e s r e a d i l y i n t o RhCil^(DMSO) 3 t o g i v e [RhC£ 4(DMS0) 2]~, and t h i s was found t o be i n e r t t o H 2 ( t a b l e 4.6). Some i n d i r e c t s u p p o r t f o r t h e i n v o l v e m e n t o f such a s i d e r e a c t i o n i n t h e H 2 r e d u c t i o n o f RhC£.j(DMSO) 3 comes from t h e measured H 2:Rh u p t a k e r a t i o o f about 1.0 when RhC£ 3(DMSO) 3 i s t r e a t e d w i t h 1 e q u i v a l e n t o f AgPF^ p r i o r t o t h e base-promoted H 2 r e a c t i o n ( u s i n g P.S.). A l t h o u g h t h e h y d r i d e Ir(H)C£ 2(DMSO) 3 r e a d i l y forms f r o m IrC£ 3(DMSO) 3 14 i n i s o p r o p a n o l a t room t e m p e r a t u r e , no h y d r i d e s were i s o l a t e d o r d e t e c t e d i n t h e i s o p r o p a n o l r e a c t i o n s w i t h t h e R h ( I I I ) complexes d i s c u s s e d i n s e c t i o n s 4.1.3.1., 4.1.3.2., and 4.1.3.3. F o r example, an u n d e t e c t e d h y d r i d e i n t e r m e d i a t e must be i n v o l v e d i n r e a c t i o n 4.3, L=DPS0. At 60° an i s o p r o p a n o l s o l u t i o n o f RhC£ 3.3H 20 and 3 DMSO d e p o s i t e d m e t a l , i n d i c a t i v e -134-o f some r e d u c t i o n p r o c e s s . I t was hoped t h a t a n a l o g u e s t o M c Q u i l l i n ' s a c t i v e h y d r o g e n a t i o n 54 c a t a l y s t , RhCl2(BH^) (py) 2DMF , c o u l d be i s o l a t e d u s i n g RhCJc^L.^, L = s u l f o x i d e , r a t h e r t h a n RhCJ^py^ as p r e c u r s o r . However, a d d i t i o n of NaBH^ t o a DMF s o l u t i o n o f any of t h e R h C ^ ^ complexes r e s u l t s i n r e d u c t i o n t o m e t a l and f o r m a t i o n o f s u l f i d e s . H y d r o g e n a t i o n c a t a l y s t s based on 6:1 BH^ /RhCH^(DMSO)probably i n v o l v e s u l f i d e and p o s s i b l y BH^ l i g a n d s . 4.2.3.2. O x i d a t i v e A d d i t i o n R e a c t i o n s o f R h ( I ) - S u l f o x i d e Complexes w i t h H„ and HC£ r The hydrogen r e a c t i o n s w i t h t h e R h ( I ) s y s t e m s , l i s t e d i n t a b l e 4.6., f a i l e d t o y i e l d i s o l a b l e d i h y d r i d e s v i a r e a c t i o n 4.8(a) a l t h o u g h h y d r i d e i n t e r m e d i a t e s must be i n v o l v e d i n t h e r e d u c t i o n o f R h ( I ) t o m e t a l , and i n any r e d u c t i o n o f c o o r d i n a t e d o l e f i n . R h ( I ) + H 2 R h ( I I I ) ( H ) 2 4.8(a) The i n s i t u r e a c t i o n o f [Rh(NBD)„]PF. w i t h m e t h i o n i n e and base I D may g e n e r a t e a d i n u c l e a r complex s i m i l a r t o one o f P t ( I I ) r e c e n t l y 56 c h a r a c t e r i z e d , b u t t h e R h ( I ) system i s i n any case r e d u c e d t o m e t a l i n t h e p r e s e n c e o f added o l e f i n i c s u b s t r a t e and H 2 ( s e c t i o n 4.3). A d d i t i o n o f 2 moles o f m e s o - 1 , 2 - b i s ( m e t h y l s u l f i n y l ) e t h a n e , MSE, t o [ R h ( N B D ) 2 ] P F ^ under H 2 r e s u l t s i n t h e p a r t i a l h y d r o g e n a t i o n o f t h e d i e n e and p r e c i p i t a t i o n o f [Rh(MSE)_]PF,. The v(S 0 ) a t 1110 and 1085 cm' l b — s u g g e s t an a l l S-bonded R h ( I ) complex i n t h e s o l i d s t a t e . T h i s compound i s o n l y s o l u b l e i n s t r o n g donor s o l v e n t s s u c h as DMA or DMSO. Exchange -135-p r o c e s s e s must be i n v o k e d t o e x p l a i n t h e e q u i v a l e n c e o f a l l t h e met h y l e n e p r o t o n s and a l l t h e m e t h y l p r o t o n s i n the 1H nmr, measured i n DMSO-d, a t 35°C. N e v e r t h e l e s s , t h e c h e m i c a l s h i f t s o f t h e s e 6 re s o n a n c e s (63.40 and 63,07, r e s p e c t i v e l y ) a r e c o n s i s t e n t w i t h a l l S-bonding t o R h ( I ) . Analogous a l l S-bonded complexes, [M(meso-MSE)2] +> 46 M = P d ( I I ) , P t ( I I ) , have been p r e p a r e d . U n f o r t u n a t e l y t h i s f a c i l e r o u t e f o r t h e p r e p a r a t i o n o f t h e Rh(I)-MSE c h e l a t e s i s n o t a p p l i c a b l e f o r t h e DIOS l i g a n d ( t a b l e 4.6). S u l f o x i d e s such as DPSO,MPSO, and PTSE, s u b s t i t u t e d w i t h a r o m a t i c g r o u p s , do n o t s t a b i l i z e R h ( I ) o r R h ( I I I ) a g a i n s t r e d u c t i o n by H 2 t o m e t a l even though t h e s e l i g a n d s appear t h e most l i k e l y t o promote Rh->-S bac k b o n d i n g (see c h a p t e r 1.4). T h i s o b s e r v a t i o n was a l s o n o t e d f o r [RuC£ 2(MPTSO) 2 1 3 ( r e f e r e n c e 57, page 2 1 3 ) , and f o r i n s i t u R h ( I ) complexes c o n t a i n i n g S P h 2 ( r e f e r e n c e 58, page 134). [RhC£(DPSO) 2] 2 i n C H 2 C £ 2 does n o t r e a c t w i t h s t o i c h i o m e t r i c amounts o f HC£ ( e q u a t i o n 4 . 8 ( b ) ) , added i n t h e f o r m o f t h e c r y s t a l l i n e HCJl *DMA adduc t . [RhC£(DMSO) 2J 2 i n DMSO does s l o w l y r e a c t w i t h HC£-DMA a t 20°C but no h y d r i d e s c o u l d be d e t e c t e d by nmr; s u l f i d e s were p r o d u c e d , p o s s i b l y t h r o u g h t h e d e c o m p o s i t i o n o f R h ( I I I ) - H s p e c i e s . D i h y d r i d e s o f C o ( I I I ) — R h ( I ) + HC£ R h ( I I I ) (H) (C£) 4.8(b) 5 9 a r s i n e s a r e known t o re d u c e DMSO a t ^ 40°C , and P t ( I I ) — s u l f o x i d e complexes a r e r e p o r t e d t o decompose t o s u l f i d e s i n t h e p r e s e n c e o f 60 a c i d , a t room t e m p e r a t u r e , RhC£ 3(DMS0) 3 c a t a l y t i c a l l y r e d u c e s DMSO 61 a t 80°C, 1 atm H 2 but u n t i l t h e p r e s e n t s t u d y , no r e d u c t i o n i n v o l v i n g -136-Rh under such m i l d c o n d i t i o n s had been o b s e r v e d , and c l e a r l y t h i s may p r e s e n t a pr o b l e m i n c a t a l y t i c h y d r o g e n a t i o n systems i n v o l v i n g s u l f o x i d e s . 4.2.3.3. The R e a c t i o n o f P r o t o n Sponge w i t h RhC£^(DMSO)^ The p r e v i o u s l y m entioned r e a c t i o n o f P r o t o n Sponge w i t h RhC& 3(DMSO) 3 i n C l ^ C J i ^ under A r i s i n t e r e s t i n g because t h i s base has been used t o promote a c t i v a t i o n i n c a t a l y t i c s t u d i e s w i t h t h e a s s u m p t i o n t h a t i t i s u n l i k e l y t o c o o r d i n a t e a t a m e t a l c e n t e r . The s t o i c h i o m e t r y o f t h i s r e a c t i o n , as j u d g e d by nmr s t u d i e s , i n v o l v e s 0.8 moles P.S. r e a c t i n g w i t h 1.0 moles RhCJc.^ (DMSO) ^  t o g i v e e q u a l amounts o f u n c o o r d i n a t e d p r o -t o n a t e d p r o t o n sponge, [P.S.H ] + , and a Rh complex w i t h a m o i e t y d e r i v e d from p r o t o n sponge, a l o n g w i t h p r o b a b l y a n o t h e r Rh(III)-DMSO complex and a l i t t l e Rh(I)-DMS0 ( t a b l e 4.5). The r e a c t i o n i n Cr^CJc^ a t 30°C i s s i g n a l l e d i n t h e i r by t h e d i s a p p e a r a n c e o f t h e i n t e n s e P.S. band a t 1580 cm 1 and t h e DMSO band a t 930 cm 1 o v e r 40 m i n u t e s , and t h e appearance o f new pe a k s , a s s i g n e d as f o l l o w s : 1605 cm \ c o o r d i n a t e d P.S.; 1100, Rh(I)-DMS0 s i n c e t h i s peak r a p i d l y d i s a p p e a r s on exposure o f t h e s o l u t i o n t o a i r ( c f . t a b l e 4.1); 1055, f r e e DMSO; and 830, [P.S.H ] + . The b r o a d peak a t 1140 of Rh(III)-DMSO, and t h e P.S. peak a t 820 cm" 1 a r e r e d u c e d s l i g h t l y i n i n t e n s i t y . The r e a c t i o n i n CT^CJc^ c a n be m o n i t o r e d by nmr. The f i n a l s p e c t r u m i s shown i n f i g u r e 4.12 and peak a s s i g n m e n t s a r e l i s t e d i n t a b l e 4.5. Resonances d e r i v e d from t h e P.S. m e t h y l g r o u p s , i n i t i a l l y a t 62.78 i n the f r e e b a s e , a r e c o n v e n i e n t l y a s s i g n e d by u s i n g RhC£^(DMSO-d^)^. The [P.S.H ]"*" m e t h y l peak a t 63.29 i s i n i t i a l l y broadened by exchange o f t h e -137-p r o t o n w i t h f r e e P.S., but a f t e r 1 h r i n t o t h e r e a c t i o n , s h a r p e n s t o a d o u b l e t w i t h a c o u p l i n g c o n s t a n t o f 2 Hz due t o t h e p r o t o n a t e d n i t r o g e n . Unexpected m e t h y l peaks o f what i s assumed t o be a c o o r d i n a t e d P.S. d e r i v a t i v e a r e n o t e d a t 65.15, 3 . 7 9 ,and 3.44, as w e l l as a s s o c i a t e d a r o m a t i c peaks a t 6.95 and 7.5-7.7 not o b s e r v e d i n [P.S.H ]BF^ o r o t h e r [P.S.H-]" 1" complexes. S i n c e t h e b r o a d peak a t 618.3, due t o t h e p r o t o n on t h e n i t r o g e n o f [P.S.H ] + , s t i l l a p p e a rs i n t h e r e a c t i o n o f RhC£„(DMSO-d,)„ + P.S. i n CTKC£ 0, i t must be t h e P.S. and n o t t h e DMSO groups t h a t a r e b e i n g d e p r o t o n a t e d . S m a l l amounts o f c r y s t a l l i n e m a t e r i a l c o n t a i n i n g a c o o r d i n a t e d P.S. m o i e t y b u t d i s p l a y i n g peaks t h a t do not c o r r e s p o n d t o t h o s e o f t h e r e -a c t i o n s o l u t i o n , can be i s o l a t e d (see t a b l e 4 . 5 ) . None o f t h e c r y s t a l s gave m e a n i n g f u l X - r a y d i f f r a c t i o n d a t a . V a r y i n g amounts o f a [ P . S . H . ] + s a l t a r e a p p a r e n t l y c o - c r y s t a l l i z e d w i t h t h e p r o d u c t s i n c e t h e i n t e g r a t i o n o f t h e m e t h y l r e s o n a n c e s o f [ P . S . H . ] + i n t h e nmr g i v e s v a r i a b l e r e s u l t s d e pending on t h e mode of r e c r y s t a l l i z a t i o n . The p r o t o n sponge complex may c o n t a i n R h ( I ) s i n c e s o l u t i o n s o f t h e c r y s t a l s i n Cl^CJc^ t u r n d a r k e r orange o v e r a p e r i o d o f days i n a i r . Indeed, a s l o w oxygen u p t a k e o f 0.4 moles 0 2/Rh was measured a f t e r 1 day on a 1 , 2 - C 2H 4 C £ 2 s o l u t i o n o f RhC& 3(DMSO) 3/P.S. r e a c t e d b e f o r e h a n d f o r 4 hours a t 38°C under N 2 . The s o l u t i o n changed from r e d t o opaque brown and a brown s o l i d p r e c i p i t a t e d w i t h s p e c t r a l p r o p e r t i e s s i m i l a r t o t h o s e o f t h e P.S. complex. F o r m u l a t i o n o f a s t r u c t u r e t h a t g i v e s t h e c o r r e c t amounts o f i n -e q u i v a l e n t P.S. m e t h y l groups and y e t p r o v i d e s a f a i r l y u n i f o r m d e s h i e l d i n g -138-o f a l l t h e a r o m a t i c p r o t o n s has n o t y e t been a c h i e v e d . D e p r o t o n a t i o n o f a m e t h y l o f t h e P.S. by a n o t h e r P.S. and t h e n c h e l a t i o n o f Rh by t h e r e s u l t i n g CH~ group and an a r o m a t i c r i n g i s a p o s s i b i l i t y , a l t h o u g h s u c h a case o f a c t i v a t i o n o f a n i t r o g e n - a t t a c h e d c a r b o n - h y d r o g e n bond i s unknown. S t u d i e s w i t h m o l e c u l a r models s u g g e s t t h a t Rh c o o r d i n a t i o n w i t h a n i t r o g e n l o n e p a i r , f o l l o w e d by o r t h o m e t a l l a t i o n t o g i v e a four-membered m e t a l l o c y c l e , i s not f e a s i b l e because of s t e r i c i n t e r -a c t i o n s between t h e N-methyl g r o u p s , and t h e s t r a i n c r e a t e d i n f o r m i n g s u c h a r i n g . The o n l y l i t e r a t u r e r e p o r t i n v o l v i n g t h e o r g a n o m e t a l l i c c h e m i s t r y o f P.S. i s t h e i s o l a t i o n o f a Ru(0) complex formed by t h e 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 o f a c o o r d i n a t e d a r e n e r i n g i n t o a P.S. 62 r i n g , b u t i f such a r e a c t i o n o c c u r r e d w i t h RhCfc^(DMSO)^, a d i m e r i z e d P.S. d e r i v a t i v e would r e s u l t w h i c h would have too many i n e q u i v a l e n t N-methyl groups t o be c o n s i s t e n t w i t h t h e nmr d a t a . 4.3 A t t e m p t s a t C a t a l y t i c Asymmetric H y d r o g e n a t i o n  4.3.1. I n t r o d u c t i o n The m e r i t s o f u s i n g c h e l a t i n g l i g a n d s (L) on R h ( I ) c e n t e r s , e.g. as [ R h L ( s o l v e n t ) ] + o r RhCJc-L(solvent) , f o r asymmetric s y n t h e s i s were d i s c u s s e d i n c h a p t e r 1. A few c h e l a t i n g s u l f o x i d e complexes w i t h such s t r u c t u r e s have been s y n t h e s i z e d as d e s c r i b e d i n s e c t i o n s 4.1 and 4.2, and o t h e r s can be formed i n s i t u f rom [Rh(NBD)„]PF, o r [RhC£(C 0H_.).]„ Z t> o 14 Z Z p r e c u r s o r s . I t a c o n i c a c i d ( m e t h y l e n e - s u c c i n i c a c i d ) i s a u s e f u l p r o c h i r a l s u b s t r a t e as a t e s t f o r c a t a l y t i c a c t i v i t y b e c a u s e t h e o l e f i n i c a c i d i s r e a d i l y a v a i l a b l e , i s e a s i l y r e d u c e d s i n c e i t i s a c t i v a t e d toward -139-H a t t a c k , and has a c i d f u n c t i o n a l i t i e s l i k e t h e a-amino a c i d p r e c u r s o r s shown i n f i g u r e 1.1, c h a p t e r 1. S i n c e t h e a c i d i c c a r b o x y l a t e s can 63 e i t h e r decompose rhodium h y d r i d e s o r promote t h e i r f o r m a t i o n ( c f . e q u a t i o n 1.19, c h a p t e r 1.3) and t h u s i n f l u e n c e t h e a c t i v i t y o f a Rh c a t a l y s t f o r h y d r o g e n a t i o n , i t i s a l s o u s e f u l t o t r y n o n - a c i d sub-s t r a t e s s u c h as s t y r e n e d e r i v a t i v e s o r u n s a t u r a t e d e s t e r s . 4.3.2. E x p e r i m e n t a l 64 a - E t h y l s t y r e n e was p r e p a r e d a c c o r d i n g t o a r e p o r t e d p r o c e d u r e . T h i s i s n o t a v e r y c o n v e n i e n t s u b s t r a t e t o use because o f t h e low s p e c i f i c r o t a t i o n o f t h e h y d r o g e n a t e d p r o d u c t , and t h u s i t i s n e c e s s a r y t o measure t h e o p t i c a l r o t a t i o n s o f n e a t a - m e t h y l p r o p y l benzene r e -c o v e r e d from t h e r e a c t i o n m i x t u r e ( i n a t l e a s t 1 ml q u a n t i t y t o f i l l t h e p o l a r i m e t e r m i c r o c e l l ) . E t h y l a t r o p a t e was p r e p a r e d by K. W. Wang (U. of B r i t i s h C o l u m b i a ) . The p r e p a r a t i o n of t h e v a r i o u s r e a c t i o n m i x t u r e s i s o u t l i n e d i n t a b l e 4.7. Gas u p t a k e s were measured i n shaken f l a s k s u s i n g the p r o c e d u r e d e s c r i b e d i n c h a p t e r 2. F l a s k s c o u l d be c l e a n e d o f Rh m e t a l by i m m e r s i o n i n c o n c e n t r a t e d H„SO, a t 150° f o r 2 4 4h f o l l o w e d by s o a k i n g i n a l c o h o l i c KOH. 4.3.3. R e s u l t s and D i s c u s s i o n The c h e l a t i n g s u l f o x i d e s (DIOS,MSE,PTSE, see t a b l e 4.7) do not s t a b i l i z e t h e R h ( I ) systems a g a i n s t r e d u c t i o n t o m e t a l under homogeneous c a t a l y t i c h y d r o g e n a t i o n c o n d i t i o n s (50-90°, 1 atm H^^ 0.2M s u b s t r a t e ) . The Rh m e t a l produced i n t h e s e e x p e r i m e n t s , w h i c h i s n o r m a l l y an e x c e l l e n t h e t e r o g e n e o u s h y d r o g e n a t i o n c a t a l y s t , must be p o i s o n e d by s u l f u r donors s i n c e t h e r e was g e n e r a l l y no e f f e c t i v e r e d u c t i o n o f t h e o l e f i n i c s u b s t r a t e s . -140-F o r c a t i o n i c complexes d e r i v e d from [Rh(NBD)^JPF^ and t h e added s u l f o x i d e s DIOS, PTSE, and. MSE, no c a t a l y t i c h y d r o g e n a t i o n was a c h i e v e d . The c a t i o n i c system w i t h m e t h i o n i n e and base ( P . S . ) , r e a c t i o n 14, t a b l e 4.7, does a c t i v e l y h y d r o g e n a t e s t y r e n e but un-f o r t u n a t e l y t h e system does n o t h y d r o g e n a t e e t h y l a t r o p a t e , a p r o c h i r a l o l e f i n . I t i s n o t c l e a r however whether MET c o o r d i n a t e s i n t h e s e c a t a l y t i c r e a c t i o n s s i n c e , w i t h o u t t h i s added l i g a n d , t h e [ R M N B D ^ J P F ^ complex i s s t i l l an a c t i v e h y d r o g e n a t i o n c a t a l y s t (see r e a c t i o n 16, t a b l e 4.7, and r e f e r e n c e 6 5 ) . C h l o r o r h o d i u m complexes of t h e c h e l a t i n g s u l f o x i d e s a r e r e d u c e d t o m e t a l o n l y a f t e r s e v e r a l h o u r s a t 50°C, 1 atm H^. However o n l y t h e DIOS complexes a r e a c t i v e c a t a l y s t s f o r t h e h y d r o g e n a t i o n o f i t a c o n i c a c i d and e t h y l s t y r e n e ; u n f o r t u n a t e l y a s i d e r e a c t i o n , p o s s i b l y s u l f o x i d e r e d u c t i o n or m e t a l f o r m a t i o n , decomposes t h e a c t i v e s p e c i e s q u i t e r a p i d l y . The one c a s e where enough h y d r o g e n a t e d p r o d u c t ( a - m e t h y l s u c c i n i c a c i d ) was r e c o v e r e d t o measure o p t i c a l r o t a t i o n s , r e a c t i o n 2, t a b l e 4.7, gave no m e a s u r a b l e e n a n t i o m e r i c e x c e s s ( e . e . ) . C a r b o n y l complexes a r e not r e d u c e d t o m e t a l but a r e i n a c t i v e h y d r o g e n a t i o n c a t a l y s t s . As might be e x p e c t e d , monodentate s u l f o x i d e complexes a r e more s u s c e p t i b l e t o H^ r e d u c t i o n t o m e t a l ( r e a c t i o n s 19, 20 and r e f e r e n c e 6 6 ) . A n i n s i t u c a t a l y s t s y s t e m formed by warming R h C ^ ' S ^ O i n (+)-2-m e t h y l - b u t y l m e t h y l s u l f o x i d e as s o l v e n t and l i g a n d , r e a c t i o n 21, s e l e c -t i v e l y r e d u c e d c a t a l y t i c a l l y t h e s u l f o x i d e i n s t e a d of i t a c o n i c a c i d . T h i s was v e r i f i e d by n o t i n g t h e s u l f i d e i n t h e ^H nmr o f t h e r e a c t i o n s o l u t i o n (CH^S a t 62.1, r e f e r e n c e 57, page 3 2 ) , and the c o p i o u s amounts o f condensed -141-w a t e r i n t h e upt a k e a p p a r a t u s : R ^ S O + H 2 > Rh c a t a l y s t S m a l l amounts o f m e t h y l s u c c i n i c a c i d were a l s o d e t e c t e d . The s u l f o x i d e s s t u d i e d a p p a r e n t l y f a i l t o meet c e r t a i n o f t h e c r i t e r i a l i s t e d i n c h a p t e r 1.3.1. f o r l i g a n d s t h a t s u p p o r t c a t a l y t i c h y d r o g e n a t i o n . The work i n d i c a t e s t h a t t h e s u l f o x i d e s f a i l t o promote the g e n e r a t i o n o f h y d r i d e s i n s u f f i c i e n t c o n c e n t r a t i o n t o be c a t a l y t i -c a l l y a c t i v e . T h i s i s p r o b a b l y because s u l f o x i d e s do n o t b i n d s t r o n g l y enough t o R h ( I ) (see s e c t i o n 4.1) t o s t a b i l i z e Rh-H s p e c i e s ( c r i t e r i o n 1) o r t o encourage o x i d a t i v e a d d i t i o n r e a c t i o n s ( c r i t e r i o n 4 ) . The i n s t a b i l i t y o f any R h - s u l f o x i d e h y d r i d e s i s s u p p o r t e d by t h e i r con-s i d e r a b l e r e a c t i v i t y i n terms o f t h e s e l f r e d u c t i o n o f R h ( I ) complexes and t h e r e d u c t i o n o f c o o r d i n a t e d s u l f o x i d e s . I n g e n e r a l , s u l f o x i d e s w i t h b e t t e r e l e c t r o n d o n a t i n g groups ( e . g . DIOS compared t o PTSE) s h o u l d b i n d more s t r o n g l y t o Rh i n t h e absence o f metal->sulfur b a c k b o n d i n g . E t 2 S i s e x p e c t e d t o be a s t r o n g S-donor t h a n MPSO and, i n d e e d , RhC£ 3(Et 2S) i s a p r e c u r s o r t o an a c t i v e R h ( I ) c a t a l y s t f o r t h e h y d r o g e n a t i o n o f m a l e i c a c i d ^ w h e r e a s RhC£.j (MPSO)^ i s f a i r l y i n a c t i v e and u n s t a b l e under s i m i l a r c o n d i t i o n s ( r e a c t i o n 20) . The c o m p l i c a t i o n o f s u l f o x i d e r e d u c t i o n , n o t e d i n s e c t i o n 4.2, i s a g a i n e n c o u n t e r e d i n t h e c a t a l y t i c r e d u c t i o n i n v o l v i n g RhC£ 3"3H 20 and MBMSO, and p o s s i b l y i n t h e d e a c t i v a t i o n o f t h e DIOS systems. R X R 2 S + H 20 T a b l e 4.7 Att e m p t s C a t a l y s t ( a ) ( b ) C o n c . M ( c ) T °C Max. S o l u t i o n ( d ) Comments ( e ) Cone. mM O l e f i n S o l v e n t R a t e 10 5M/ C o l o u r s e c 1. [Rh(NBD) 2]PF 6 +1.2 DIOS 13 I.A. 0.25 DMA 43 0 B - m e t a l a t 100s 2. [ R h C £ ( C g H 1 4 ) 2 ] 2 +2.4 DIOs(f) 8 I.A. 0.38 DMA 63 4.0 B - m e t a l between 2 and 16h - c a t a l y s t s l o w l y d e a c t i v a t e d -20% S.A. w i t h no e.e. a f t e r 16h 3. [R h C £ ( C g H 1 4 ) 2 ] 2 +4 DlOS^g) 6 M.S. 0.34 DMA 58 1.0 RB - c a t a l y s t s l o w l y d e a c t i v a t e d - s t o p p e d a t 30% conv. a f t e r 5h 4. [ R h C £ ( C g H 1 4 ) 2 ] 2 +4 DIOs(g) 11 E.S. 0.60 BuOH 65 6.4 R - c a t a l y s t r a p i d l y d e a c t i v a t e d - m e t a l a t 3h, 20% conv.(h) 5. [RhC£(DI0S) o] z n 8 I.A. 0.36 ME 63 0.5 Y - m e t a l between 2 and 16h 8 I.A. 0.36 BuOH 63 0.3 Y - m e t a l between 2 and 16h - c a t a l y s t r a p i d l y d e a c t i v a t e d 6. [ R h C £ ( C g H 1 4 ) 2 ] 2 +2 BDIOS^g) 1.5 I.A. 0.32 BuOH 63 0 Y - m e t a l b e f o r e 16h 7. [ R h ( M S E ) 2 ] P F 6 2.3 I.A. 0.15 DMA 50 0 Y -no m e t a l 2.3 I.A. 0.15 DMA 80 0 Y - m e t a l a t 100s 8. [ R h C £ ( C g H 1 4 ) 2 ] 2 +2 MSE 11 I.A. 0.15 ME 50 0 0 - m e t a l a t 4000s 9. [RhC£(CO) 2] 2 +2 MSE 13 I.A. 0.15 ME 50 0 Y -CO e v o l u t i o n , no m e t a l 1 0 . [ R h ( N B D ) 2 ] P F 6 6 S 0.19 ME 50 0 0 - m e t a l a t 100s +DTH T a b l e 4.7 ( c o n t . ) [Rh(NBD)2]PF6 +PTSE [RhC£(C gH l 4) 2] 2 +3PTSE [Rh(NBD)2]PF6 +MET [Rh(NBD)2]PF6 +MET+2P.S. [Rh(NBD)2]PF6 +MET+2P.S. [Rh(NBD)2]PF6 +2P.S. [RhC£(C gH l 4) 2] 2 +2MET [RhCJl(CO)2]2 +2MET [RhC£(CgH l 4) 2] 2 +4MPTS0 RhC£ 3(MPSO) 3 ( f^ RhC«-3-3H20(i) Cone. mM 5 13 10 6 15 O l e f i n ( ^ C o n c . M E.A. 0.19 I.A. E.A. 2.0 I.A. I.A. (c) S o l v e n t v w T °C 60 ME I.A. 0.15 DMA 0.15 ME 0.19 ME 0.23 ME 0.19 ME 0.15 ME 0.15 ME I.A. 0.15 DMA I.A. 0.12 DMA I.A. 1.5 MBMSO 70 86 Max. S o l u t i o n R a t e C o l o u r 105M/sec (d) Comments (e) 53 0 50 0 63 1.1 50 M.0 50 0 50 0 60 0 0.4 0.5 B 0 - m e t a l a t 300s - m e t a l b e f o r e 24h - m e t a l a t l h 50 VL0 YG - m e t a l o n l y a t 100% conv - m e t a l a t 500s - m e t a l o n l y a t 100% conv - m e t a l a t 4000s -CO e v o l u t i o n -no m e t a l - m e t a l a t 200s - m e t a l a t 2000s - o n l y s u l f o x i d e r e d u c e d - r a t e d e c r e a s e s s l o w l y -50% conv. a t lOOh T a b l e 4.7 ( c o n t . ) R e a c t i o n s o l u t i o n s were p r e p a r e d , u n l e s s o t h e r w i s e n o t e d , by f i r s t d i s s o l v i n g t h e Rh complex, t h e l i g a n d , and t h e s u b s t r a t e i n 5 ml s o l v e n t i n vacuo a t 20°C, and t h e n i n t r o d u c i n g 1 atm C g H j ^ c i s - c y c l o o c t e n e ; BDIOS=DIOS w i t h b e n z y l groups i n s t e a d of m e t h y l s a t o t h e s u l f o x i d e group; DTH=2,5-dithiahexane; MET=(S)-methionine. I . A . = i t a c o n i c a c i d ; M. S.=a-methyl s t y r e n e ; E . S . = a - e t h y l s t y r e n e ; S = s t y r e n e ; E . A . = e t h y l a t r o p a t e . DMA=dimethylacetamide; BuOH=n-butanol; ME=2-methoxyethanol; MBMSO=(+)-2-methyl-butyl m e t h y l s u l f o x i d e . B=brown; RB=red-brown; R=red; Y=yellow; O=orange; G=green. S.A.= m e t h y l s u c c i n i c a c i d ; c o n v . = c o n v e r s i o n of s u b s t r a t e . The o l e f i n was added under a p o s i t i v e p r e s s u r e of H2 a f t e r t h e s o l u t i o n was p r e t r e a t e d a c c o r d i n g t o t h e c o n d i t i o n s l i s t e d i n t a b l e 4.6. The l i g a n d and R h - p r e c u r s o r were premixed i n degassed CH^CJ^- The s o l v e n t was t h e n removed by e v a c u a t i o n and t h e r e s u l t i n g o i l was t a k e n up i n a s o l u t i o n o f t h e s u b s t r a t e d i s s o l v e d i n t h e r e a c t i o n s o l v e n t . The s o l u t i o n , d i s t i l l e d from t h e r e a c t i o n m i x t u r e , gave no o p t i c a l r o t a t i o n . The c h i r a l compound MBMSO (1 m l ) , and RhC^.SH^O were h e a t e d f o r l h a t 60°C i n v a c u o , and t h e n H2 was i n t r o d u c e d . -145-5. H y d r i d o i r l d l u m S u l f o x i d e Complexes 5.1. P r e p a r a t i o n and S p e c t r o s c o p i c P r o p e r t i e s 5.1.1. I n t r o d u c t i o n A n o t h e r a p p r o a c h t o t h e use o f c h i r a l s u l f o x i d e s i n c a t a l y t i c a s y m m e t r i c s y n t h e s i s i s t h e s y n t h e s i s o f c h i r a l a n a l o g u e s o f IrC£ 2H(DMS0)^, a known c a t a l y s t f o r some h y d r o g e n a t i o n and o x i d a t i o n r e a c t i o n s (see c h a p t e r 1.3). The DMSO complex has been p r e p a r e d i n low y i e l d (20%) i n two s t e p s s t a r t i n g from [IrC£^] The i n i t i a l s t e p i n v o l v e d t h e s y n t h e s i s of e i t h e r t h e y e l l o w c i s - o r p i n k t r a n s -a c i d complexes, [H(DMS0) 2][IrC£ 4(DMS0) 2]. The y e l l o w isomer was i d e n t i f i e d as t h e c i s a c i d s o l e l y on t h e b a s i s o f i t s g r e a t e r s t a b i l i t y i n p o l a r s o l v e n t s . A t e n t a t i v e r a t i o n a l i z a t i o n i n v o l v i n g nmr c h e m i c a l s h i f t s o f t h e m e t h y l p r o t o n s was a l s o p r o p o s e d . 1 I n t h e second s t e p of the s y n t h e s i s , an I r a c i d complex was r e a c t e d w i t h i s o p r o p a n o l t o y i e l d a h y d r i d e complex and a c e t o n e ; t h e t r a n s a c i d was t h o u g h t t o y i e l d t r a n s - d i c h l o r o - m e r - t r i s ( D M S O ) - h y d r i d o i r i d i u m ( I I I ) . Two r o u t e s t o I r h y d r i d e complexes c o n t a i n i n g c h i r a l s u l f o x i d e s were b r i e f l y i n v e s t i g a t e d h e r e . The s y n t h e s i s o f I r C i l ^ L ^ was a t t e m p t e d , s i n c e t h e s e compounds s h o u l d r e a c t w i t h i s o p r o p a n o l t o y i e l d h y d r i d e s , a t l e a s t i n s i t u . A l s o s i n c e t h e i r i d i u m ( I ) complex, [IrC£(cyclooctene) 2] 2, can be e f f i c i e n t l y p r e p a r e d from c o m m e r c i a l l y a v a i l a b l e I r s t a r t i n g m a t e r i a l s , and s i n c e i t m i g h t be e x p e c t e d t o o x i d a t i v e l y add HC£ i n t h e p r e s e n c e o f s u l f o x i d e , p r e l i m i n a r y e x p e r i m e n t s o f t h i s k i n d were a l s o t r i e d . 5.1.2. E x p e r i m e n t a l C h a l c o n e ( b e n z y l i d e n e a c e t o p h e n o n e ) was p r e p a r e d by c o n d e n s i n g acetophenone -146-and b e n z a l d e h y d e . z The complexes c i s - and trans-[H(DMSO)^][IrC£^(DMSO) ] have been p r e p a r e d from H ^ I r C ^ ] , and c h a r a c t e r i z e d 1 ; f o r t h i s work the y were p r e p a r e d from IrC£^ o r IrC£ 3.3H 20 as f o l l o w s . 5.1.2.1. Trans-[H(DMSO) 2][IrC£ 4(DMSO) 2] A f t e r IrC£ 4(0.45 g, 1.3 mmol) had r e a c t e d w i t h c o n c e n t r a t e d HC£ (0.3 m l , 4 mmol) i n 5 ml i s o p r o p a n o l f o r 4 ho u r s a t 55°C, t h e r e s u l t i n g g r e e n - r e d s o l u t i o n was c o o l e d t o room t e m p e r a t u r e , and DMSO (2.5 m l , 35 mmol) was added. The orange n e e d l e s t h a t c r y s t a l l i z e d out o v e r n i g h t were f i l t e r e d i n a i r , washed w i t h i s o p r o p a n o l and e t h e r , and d r i e d i n vacuo. Y i e l d , 0.45 g, 52%.' m-.p. 152-154°. nmr(D 20) 63.50(s,12,DMS0), 2 . 7 1 ( s , 1 2 , f r e e DMSO); 4.72(HOD). i r , v (S0) 1127s; P r ( C H 3 ) 1027s, 980s; v(OHO) 1700-llOOm, 900-600s; (Ir-C£) 335m, 326s. 5.1.2.2. Cis-[H(DMSO)J[IrC£(DMSO) ] DMSO (0.53 m l , 7.5 mmol) was added t o t h e r e d s o l u t i o n formed by h e a t i n g IrC£ 3.3H 20 (0.3 g, 0.87 mmol) and aqueous HC£ (1.1 m l , 2.4M) a t 85° f o r 30 m i n u t e s . H e a t i n g was c o n t i n u e d f o r 38h i n a i r i n a c l o s e d g l a s s - s t o p p e r e d S c h l e n k t u b e . When t h e tube was opened, a s t r o n g s m e l l o f d i m e t h y l s u l f i d e emanated f r o m t h e orange s o l u t i o n . The s o l u t i o n was red u c e d t o an o i l by pumping, and t h e r e s i d u e was d i s s o l v e d i n 1 ml w a t e r and e x t r a c t e d w i t h CH 2C£ 2(3xlO m l ) . P r o p a n - 2 - o l (5 ml) and DMSO (0.5 ml) were added t o t h e s y r u p , o b t a i n e d by e v a p o r a t i n g t h e aqueous l a y e r , t o y i e l d t h e a c i d . Y i e l d , 0.21 g, 40%. S p e c t r a l d a t a a g r e e w i t h t h o s e p u b l i s h e d . 1 nmr(D 20) 63.52(s,12,DMS0), 6 2 . 7 1 ( s , 1 2 , f r e e DMSO). The C H 2 C £ 2 e x t r a c t s y i e l d e d 0.02 g o f IrC£ 3(DMSO) 2(DMSO). 1 -147-5.1.2.3. T r a n s - d i c h l o r o - m e r - t r i s (DMSO) hydr i d o i r i d i u m ( I I I ) (a) [ I r C X , ( c y c l o o c t e n e ) ^ ] 2 (0.1 g, 0.11 mmol) formed a y e l l o w s o l u t i o n on d i s s o l v i n g i n d r y DMSO (0.4 m l , 5.6 mmol) and CH^C^ (3 ml) a t 10°C under A r . A few l a r g e c r y s t a l s o f HC£.DMA (0.027g, 0.22 mmol) were r a p i d l y weighed and added. The s o l u t i o n , now c o l o u r l e s s , was r e d u c e d i n volume t o 0.5 ml i n vacuum, and d r y e t h e r was s l o w l y added u n t i l t h e s o l u t i o n went t u r b i d . T h i s was warmed u n t i l c l e a r and t h e n l e f t t o d e p o s i t w h i t e c r y s t a l s a t room t e m p e r a t u r e . A f t e r more c r y s t a l l i z a t i o n was i n d u c e d a t 0°C, t h e p r o d u c t was f i l t e r e d under A r , washed w i t h a l i t t l e e t h e r , and d r i e d i n v acuo; the w h i t e c r y s t a l s a r e v e r y h y g r o s c o p i c and t u r n t o a y e l l o w o i l i n m o i s t a i r . Y i e l d , 70%. A n a l . C a l c d f o r t h e mono-DMSO s o l v a t e , IrC£ oS o0„C,H, n.S0C„H.: C, 16.66; H, 4.37. Found: 2 3 3 6 19 2 6 C, 18.13; H, 4.13. T h i s sample was l i k e l y c o n t a m i n a t e d w i t h a s m a l l amount o f c y c l o o c t e n e but o t h e r s were n o t , as e v i d e n c e d by t h e i r nmr d a t a ( f i g u r e 5.1). nmr(CDC£ 3) 63.73(s,6,DMSO), 3.57(s,12,DMS0), 2.62 (s,6,DMSO o f s o l v a t i o n ) ; T 2 8 . 8 6 ( S , 1 , h y d r i d e ) . i r , v ( I r - H ) 2180s; v ( S 0 ) 1134s,1110s; P r ( C H 3 ) + v(S 0 ) o f s o l v a t e 1027s; v(Ir-C£) 302w. (b) The h y d r i d e complex c a n a l s o be o b t a i n e d w i t h o u t s o l v a t i n g DMSO and i n good y i e l d as f o l l o w s . When HC&.DMA (68 mg, 0.56 mmol) i s added t o a degassed s u s p e n s i o n o f [IrC£(cyclooctene)^\ ^  (0.25 g, 0.28 mmol) i n 5 ml 2 - p r o p a n o l and 1.0 ml DMSO, t h e suspended compound t u r n s from orange t o w h i t e i n 10 min. a t room t e m p e r a t u r e . The w h i t e p r o d u c t was f i l t e r e d , washed w i t h e t h e r , and r e c r y s t a l l i z e d by d i s s o l u t i o n i n 1 ml DMSO and a d d i t i o n o f i s o p r o p a n o l / e t h e r ( V / V = l / 2 ) . Y i e l d , 60%. A n a l . C a l c d f o r I r C £ 2 S 3 0 3 C 6 H i g : C, 14.46; H, 3.81. Found: C, 15.52; H, 4.17. The s p e c t r a l • i i I . . . . • . . I 5 ppm 3 1 F i g u r e 5.1. 100 MHz 1 H nmr spectrum o f IrCJ£2H(DMS0)--DMS0 i n CDCl -149-d a t a were s i m i l a r t o t h o s e o f t h e p r o d u c t (a) exce p t t h a t t h e r e was no f r e e DMSO peak; a l i t t l e f r e e c y c l o o c t e n e (65.5, 2.0, 1.4) was a l s o d e t e c t e d . (c) Three a t t e m p t s s t a r t i n g w i t h e i t h e r t h e c i s o r t r a n s a c i d complexes f a i l e d t o r e p r o d u c e t h e p u b l i s h e d p r e p a r a t i o n o f IrCJc^HtDMSO) . I n s t e a d o n l y a few m i l l i g r a m s o f a y e l l o w compound p r e c i p i t a t e d , and t h i s was i d e n t i f i e d as a m i x t u r e o f h y d r i d e s and o t h e r n e u t r a l complexes, nmr (CDC£ 3) 63.51 (main DMSO peak); 3.73, 3.63, 3.57, 3.21, 2.91 ( s m a l l DMSO p e a k s ) ; T29.45 (main h y d r i d e ) ; 28.85 ( s m a l l amount o f h y d r i d e from ( a ) ) , i r , v ( I r - H ) 2150-2180; v( S 0 ) 1 1 3 0 - l l O O s . (d) R e a c t i o n w i t h c h a l c o n e : The h y d r i d e from (a) and c h a l c o n e were 3 r e a c t e d i n i s o p r o p a n o l a c c o r d i n g t o th e method o f Henbest e t a l . . The p a l e y e l l o w i s o m e r o f t h e r e p o r t e d a l k y l complex, I r ( C ^ r L ^ O ) C l ^ ( D M S O ) 2 > was o b t a i n e d j u d g i n g from the agreement o f t h e nmr d a t a (CDC£ 3): 68.4-7.2 ( m , 1 0 , a r o m a t i c ) ; 3.92, 3.50, 3.38, 2.04 (each s,3,S-CH 3); 5.71, 4.69, 3.65 (each q o f AMX s y s t e m , J A M = 1 0 , J' A X =^» J M X = 2 2 H z ' 1 ' i n e c l u l v a l e n t : p r o t o n s o f a l k y l c h e l a t e r i n g ) . The i r d a t a d i f f e r s l i g h t l y f r o m t h o s e r e p o r t e d : v ( p h e n y l ) 1580; v(C0) 1540; v ( S 0 ) 1127; P r ( C H 3 ) 1022; v(Rh-C£) were t o o weak t o o b s e r v e . R e f e r e n c e 3 g i v e s v(C0) 1580 cm \ (e) R e a c t i o n w i t h CDCJc^: When IrHC£ 2 (DMSO) . DMSO was h e a t e d a t 40°C f o r 24h i n CDC£ 3 under A r , t h e s o l u t i o n t u r n e d from c o l o u r l e s s t o y e l l o w and a t l e a s t two f u r t h e r I r s p e c i e s w i t h c o n c e n t r a t i o n s s i m i l a r t o t h e r e m a i n i n g unreac'ted h y d r i d e appeared t o form: IrC£ 3(DMSO) 2(DMSO^) 1 w i t h e q u a l i n t e n s i t y peaks a t 63.63, 3.52, 2.88; IrC£ 3(DMSO) 1 w i t h peaks a t 63.56 and 3.46 ( r a t i o 1:2); CHDC£ 0 a t 65.2. -150-5.1.2.4. C h l o r o - c i s - d i h y d r i d o - m e r - t r i s ( D M S O ) i r i d i u m ( I I I ) (a) [IrC£(cyclooctene) 2]2 (0.1 g) was d i s s o l v e d i n 0.4 ml DMSO and 3 ml CH^Ci^ under A r . Upon i n t r o d u c t i o n o f 1 atm E^, t h e s o l u t i o n t u r n e d c o l o u r l e s s ; a f t e r 5 min. i t was c o n c e n t r a t e d t o 0.5 ml under vacuum and 1 ml i s o p r o p a n o l and t h e n enough e t h e r were added t o g i v e a w h i t e , a i r - s t a b l e p r e c i p i t a t e . T h i s s u s p e n s i o n was c o o l e d f o r a few ho u r s and t h e n f i l t e r e d . The p r o d u c t was washed w i t h e t h e r and d r i e d i n v a cuo. Y i e l d , 70%. A n a l . C a l c d , f o r I r C i > S ^ C ^ Q : C, 15.53; H, 4.34. Found: C, 15.57; H, 4.42. nmr(CDC£ 3) 63.57(s,6,DMSO), 3.53(s,6,DMS0), 3.39(s,6,DMSO); x26.3(d,J=6 H z , I r - H ) , 29.5(d,J=6Hz,Ir-H) . i r , v ( I r - H ) 2177s, 2087s; v ( S 0 ) 1128s, 1120sh, 1090m; P r ( C H 3 ) 1035s, 978w; v(IrC£) too weak. (b) R e a c t i o n o f t h e d i h y d r i d e w i t h CDC£ 3: A f t e r 20h a t 22°C i n CDC£ 3, s m a l l amounts o f a t l e a s t two d e c o m p o s i t i o n p r o d u c t s o f t h e d i h y d r i d e were o b s e r v e d : t h e o n l y m o n o h y d r i d o i r i d i u m s p e c i e s d e t e c t a b l e was t h a t d e s c r i b e d i n s e c t i o n 5.1.2.3(63.72,3.57,x28.86); a peak a t 63.45 may be due t o mer-IrC£ 3(DMS0) 3, a l t h o u g h t h e r e q u i r e d second peak a t 3.56 was h i d d e n ; CHDC£2 was o b s e r v e d a t 65.2 i n s i g n i f i c a n t amounts. (c) R e a c t i o n w i t h HC£.DMA: A s t o i c h i o m e t r i c amount o f HC£.DMA r e a c t s r a p i d l y w i t h t h e d i h y d r i d e i n CDC£ 3 t o g i v e t h e f o l l o w i n g nmr spect r u m w h i c h i s a s s i g n e d t o IrHC£ 2(DMSO) 2(DMSO) w i t h c i s - c h l o r i d e s and DMSO t r a n s t o t h e h y d r i d e : 63.56(s,6,DMSO), 3.-51(s,6,DMSO), 2.68(s,6,DMS0); x 3 0 . 6 0 ( s , l , I r - H ) . Other peaks o b s e r v e d a r e : 6 2 . 6 3 ( s , l , f r e e DMSO); 3.01(s,broad,6,N-CH 3), 2.16(s,3,C-CH 3). See f i g u r e 5.2. The e q u i v a l e n c e of t h e N-CH_ groups o f DMA must r e s u l t from p r o t o n exchange w i t h some -152-u n r e a c t e d H C £ . D M A ; t h e spect r u m o f H C £ . D M A i n CDCSL^ a l s o shows one peak due t o e q u i v a l e n t N - C H ^ g r o u p s . 5.1.2.5. The At t e m p t e d P r e p a r a t i o n o f [I r C & ( D M S O ) ^ ] 2 The p r o c e d u r e used f o r t h e p r e p a r a t i o n o f [RhC£(DMSO)^] 2 w a s f o l l o w e d ( s e c t i o n 4.1.2.). A w h i t e i r i d i u m h y d r i d e , p o s s i b l y formed from t r a c e s o f w a t e r by o x i d a t i v e a d d i t i o n , p r e c i p i t a t e d on a d d i t i o n o f e t h e r , i r , v ( I r - O H ) 3440s, s h a r p ; 2200 v ( I r - H ) ; v(S0) 1143s, 1103s; P r ( C H 3 ) 1030s. 5.1.2.6. The At t e m p t e d P r e p a r a t i o n o f I r C J l ^ L ^ ; L=MPS0, DPSO, MBMSO, TBPTSO, OTPTSO When I r C £ 3 . 3 H 2 0 (0.07 g) and L ( I r : L = l : 4 ) were h e a t e d a t 63°C i n MeOH (6 ml) and H^O (0.6 ml) f o r 16h under A r , t h e s o l u t i o n s t u r n e d from r e d t o amber. No compound c o u l d be p r e c i p i t a t e d o r chromatographed from t h e s e s o l u t i o n s . Use of i s o p r o p a n o l l e a d t o m e t a l f o r m a t i o n . 5.1.3. D i s c u s s i o n Routes t o t h e DMSO compounds were f i r s t s t u d i e d . The a c i d complexes, [H(DMS0) 2][IrC£ 4(DMS0) 2] were r e a d i l y s y n t h e s i z e d from t h e a v a i l a b l e s t a r t i n g m a t e r i a l s , I r C J t . ^ , o r I r C & 3 . 3 H 2 0 , by s l i g h t l y m o d i f y i n g t h e method of Henbest e t al . ? * I t i s n o t c l e a r whether t h e s e w o r k e r s r e c o g n i z e d t h e n a t u r e o f t h e [ H ( D M S 0 ) 2 ] + c a t i o n , but i n d e e d , t h e i r bands due t o a s y m m e t r i c a l l y hydrogen-bonded system a r e p r e s e n t i n t h e s p e c t r a o f t h e s e a c i d s (see c h a p t e r 4.1.3.3 f o r a d i s c u s s i o n o f t h e ana l o g o u s rhodium c o m p l e x e s ) . -153-An orange c r y s t a l l i n e m o d i f i c a t i o n o f t h e t r a n s isomer was formed from t h e p r e p a r a t i o n i n v o l v i n g IrC£^. I f t h e t r a n s complex i s warmed a t 65° f o r 15 min i n T>20, t h e aquated s p e c i e s trans-[IrCft^(DMSO) (D^O) ] ~ i s formed and i d e n t i f i e d by th e m e t h y l peaks t h a t grow i n t h e """H nmr a t 63.58. T h i s r e a c t i o n p a r a l l e l s t h a t o f t h e c o r r e s p o n d i n g t r a n s Rh a c i d ( c h a p t e r 4.1.3.3) and s u p p o r t s t h e s t e r e o c h e m i c a l a s s i g n m e n t . Only minor amounts o f t h e D 2 0 - s u b s t i t u t e d p r o d u c t s from t h e c i s a c i d a r e ob s e r v e d a f t e r h e a t i n g f o r 15 min. The l a r g e amount o f d i m e t h y l s u l f i d e formed i n t h e p r e p a r a t i o n o f t h e c i s a c i d may r e s u l t from t h e a c i d -c a t a l y z e d d e c o m p o s i t i o n o f DMSO o r c o o r d i n a t e d DMSO. The f o r m a t i o n and d e c o m p o s i t i o n o f h y d r i d o i r i d i u m s p e c i e s i s n o t a l i k e l y s o u r c e o f s u l f i d e s i n c e no r e d u c i n g agent was p r e s e n t . The o x i d a t i v e a d d i t i o n o f a s t o i c h i o m e t r i c amount o f HCJ". (added as t h e DMA a d d u c t ) t o [ I r C J c . ( c y c l o o c t e n e ) 2 ] 2 i n DMSO/CH 2C£ 2 s o l u t i o n s a l l o w s t h e i s o l a t i o n o f IrC£ 2H(DMSO)^, 3_7 ( e q u a t i o n 5.1, f i g u r e 5.3). The use o f e x c e s s DMSO i n t h e r e a c t i o n s o l u t i o n (DMSO:Ir=10:1) appears n e c e s s a r y t o a v o i d t h e f o r m a t i o n o f a. cyclooctene/DMSO mixed complex o b t a i n e d when a 3:l=DMS0:Ir r a t i o was employed; b r o a d peaks o f t h e c o o r d i n a t e d o l e f i n come i n t h e nmr s p e c t r u m (CDCA.^) a t 64.7, 2.5, and 1.5 a l o n g w i t h a DMSO peak a t 63.46. I f e x c e s s HC£ gas i s u s e d , then [H(DMSO) 2] [IrCJ~, 4(DMS0) 2] i s produced. The o n l y s t e r e o c h e m i s t r y f o r t h e h y d r i d e complex t h a t i s c o n s i s t e n t w i t h t h e two m e t h y l r e s o n a n c e s o f i n t e g r a t i o n r a t i o 1:2 i n t h e nmr spe c t r u m i s one w i t h t r a n s c h l o r i d e s and m e r i d i a l DMSO l i g a n d s ( f i g u r e 5.3, 3 7 ) ; o t h e r i s o m e r s s h o u l d g i v e t h r e e peaks because t h e two m e t h y l -154-F i g u r e 5.3. The Formation and Some Reactions of Ir-Sulfoxide Hydride Complexes -r- H C I D M S O (5.1) CI | S H S 37 C D C I , 56 (5.2) - C H D C U S N L C I ° 6 C l s i a CI I X I s + H2. D M S O (5.3) CI rKk^CDC I 3 ^ - C H D C l , 38 <5-5) || is cis-cyclooctene. S represents S-bonded DMSO. 0 represents DMSO. N ' C I CI | X H S + CI | N C I s -155-groups i n some of t h e DMSO t h e n become m a g n e t i c a l l y i n e q u i v a l e n t . I t i s c o n f u s i n g t h e r e f o r e t h a t a p r e l i m i n a r y c r y s t a l s t r u c t u r e o f a y e l l o w h y d r i d e complex p r e p a r e d by Henbest e t a l . 1 shows t h i s geometry ( 3 7 ) ; t h i s h y d r i d e has t h e same v ( I r - H ) a t 2180 cm 1 but d i f f e r e n t v(Ir-C£) a t 334s and 300w ( v e r s u s 302w, t h e v a l u e found h e r e ) , and a d i f f e r e n t h i g h f i e l d nmr peak a t T35.29 ( v e r s u s 28.86). U n f o r t u n a t e l y m e t h y l peak p o s i t i o n s were n o t r e p o r t e d . S m a l l amounts o f h y d r i d e s p e c i e s , p r e p a r e d a c c o r d i n g t o t h e method o f Henbest e t a l . , showed no t r a c e of a h y d r i d e a t x35.29 a l t h o u g h peaks a t x29.45 and 28.86 were p r e s e n t . The w h i t e h y d r i d e p r e p a r e d h e r e does r e a c t w i t h c h a l c o n e t o form t h e c h e l a t e d a l k y l complex, _56 (see r e a c t i o n 1.20, f i g u r e 5.3 o r c h a p t e r 1.3). The u p f i e l d s h i f t s ( o f up t o 1.5 ppm!) f o r t h e r e s o n a n c e s of t h e i n e q u i v a l e n t DMSO m e t h y l s , o b s e r v e d i n t h e nmr o f t h i s p r o d u c t , a r e t h e 3 same as t h o s e r e p o r t e d , and a r e caused by t h e r i n g c u r r e n t s o f t h e p r o x i m a l p h e n y l s o f t h e a l k y l s . A c i s d i h y d r i d e , _3_8, f i g u r e 5.3, was a l s o p r e p a r e d i n good y i e l d by t h e o x i d a t i v e a d d i t i o n o f H^ t o t h e c y c l o o c t e n e dimer i n DMSO. The s t e r e o c h e m i s t r y shown i s unambiguously d e t e r m i n e d by t h e nmr s p e c t r a l d a t a ; t h e m u t u a l l y t r a n s DMSO c o n t a i n m a g n e t i c a l l y i n e q u i v a l e n t m e t h y l groups. I t appears t h a t t h e w h i t e d i h y d r i d e o r i g i n a l l y p r e p a r e d 1 i s t h e isomer o f _38_ c o n t a i n i n g an 0-bonded DMSO t r a n s t o t h e h y d r i d e . T h i s would a c c o u n t f o r t h e d i f f e r e n t s p e c t r a l d a t a r e p o r t e d ; 1 v ( l r - H ) a t 2170, 2250 cm 1 , 62.78(s,3,DMS()); o t h e r w i s e , t h e r e p o r t e d s p e c t r a a r e i d e n t i c a l t o t h o s e f ound i n t h e p r e s e n t s t u d y . -156-Th e h y d r i d e s _3J7 and _38_ decompose i n t h e p r e s e n c e o f CDCH^ o r HC&.DMA. The major p r o d u c t s , as d e t e r m i n e d by nmr, appear i n f i g u r e 5.3; nmr d a t a n o t e d i n t h i s and p r e v i o u s w o r k 1 a l l o w a f a i r l y c o n f i d e n t a ssignment o f t h e i r s t e r e o c h e m i s t r i e s . The r e a c t i o n o f t h e d i h y d r i d e w i t h HC&.DMA (5.4) r e s u l t s i n t h e q u a n t i t a t i v e f o r m a t i o n of a new mono-h y d r i d e s p e c i e s o f s t e r e o c h e m i s t r y t h a t i s n o t c o n s i s t e n t w i t h t h e r u l e t h a t r e a c t i o n s between i r i d i u m h y d r i d e s ( p h o s p h i n e complexes) and HC£ p r o c e e d w i t h o u t r e a r r a n g e m e n t o f o t h e r l i g a n d s . ~* R e a c t i o n s o f t h e h y d r i d e s w i t h CDC£^ p r o c e e d as e x p e c t e d : an i r i d i u m c h l o r i d e i s formed as t h e h y d r i d e i s t r a n s f e r r e d t o t h e h a l o g e n a t e d h y d r o c a r b o n , y i e l d i n g CHDC£ 2 i n t h i s c a s e . B r i e f a t t e m p t s t o i s o l a t e pure complexes w i t h o t h e r s u l f o x i d e s d i d not s u c c e e d . M i x t u r e s o f t h e c y c l o o c t e n e dimer and e x c e s s DPSO i n CH^C/^ d i d not r e a c t w i t h HCJl.DMA. O x i d a t i v e a d d i t i o n r e a c t i o n s on i n s i t u i r i d i u m ( I ) systems c o n t a i n i n g an e x c e s s of a c h i r a l s u l f o x i d e were no t a t t e m p t e d . No compounds were i s o l a t e d from r e a c t i o n s o f MPSO, DPSO, MBMSO, TBPTSO, o r OTPTSO w i t h IrC£ 3-3H 20 i n MeOH. On u s i n g i s o p r o p a n o l and t h e p h e n y l s u b s t i t u t e d s u l f o x i d e s , t h i s p r o c e d u r e gave I r m e t a l . 5.2. A t t e m p t s a t the Asymmetric H y d r o g e n a t i o n o f P r o c h i r a l Ketones and  O l e f i n s u s i n g I r i d i u m - C h i r a l S u l f o x i d e Complexes 5.2.1. I n t r o d u c t i o n I r i d i u m - s u l f o x i d e complexes a r e known t o c a t a l y z e t h e t r a n s f e r o f H 2 from a l c o h o l s and o t h e r H 2 donors t o k e t o n e s t o g i v e a l c o h o l s , and t o a,3-unsaturated k e t o n e s t o g i v e s a t u r a t e d k e t o n e s (see c h a p t e r 1.3.2). T h e r e f o r e t h e use of c h i r a l s u l f o x i d e l i g a n d systems w i t h p r o c h i r a l -157-s u b s t r a t e s seemed a p o t e n t i a l method t o a c h i e v e c a t a l y t i c a s ymmetric h y d r o g e n a t i o n . The asymmetric h y d r o g e n a t i o n of p r o c h i r a l k e t o n e s t o a l c o h o l s of h i g h o p t i c a l p u r i t y (70-80%) has been a c c o m p l i s h e d u s i n g v a r i o u s Co and Rh c a t a l y s t s and hydrogen. N o r m a l l y a - d i k e t o n e s g i v e t h e b e s t 7 r e s u l t s , e.g. b e n z i l (79%) , t h e l a c t o n e of 2 - o x o - 3 , 3 - d i m e t h y l - 4 -8 9 h y d r o x y b u t y r i c a c i d (80%) , and 2,3-butanedione ; 2 - o c t a n o l w i t h 13% e.e. has been produced from 2 - o c t a n o n e . H o w e v e r no asymmetric s y n t h e s i s has been r e p o r t e d u s i n g a w e l l - d e f i n e d c h i r a l c a t a l y s t f o r h y d r o g e n a t i o n i n v o l v i n g t r a n s f e r from s o l v e n t , a l t h o u g h a system w i t h RuCi^CPPhg)^ and a c h i r a l a l c o h o l s o l v e n t has p r o v e n e f f e c t i v e . 1 1 H y d r o g e n a t i o n o f a , ^ - u n s a t u r a t e d k e t o n e s , p r o c h i r a l a t t h e o l e f i n , u s i n g t h e Henbest c a t a l y s t system (IrCJi^I^DMSO) ^  formed i n s i t u ) has n o t been r e p o r t e d , a l t h o u g h s u c h s u b s t r a t e s have been r e d u c e d u s i n g R u C J t ^ C P P h . ^ 12 as t h e hydrogen t r a n s f e r c a t a l y s t . The o l e f i n i c bond i n a t r o p i c a c i d 13 and i t a c o n i c a c i d c o u l d not be r e d u c e d w i t h I r - s u l f o x i d e c a t a l y s t s . 5.2.2. E x p e r i m e n t a l Samples o f 3-methyl-3-penten-2-one, 4-methyl-3-penten-2-one, and 2-octanone ( A l d r i c h Chem. Co.) were k i n d l y donated by P r o f . D. D o l p h i n (U. o f B r i t i s h C o l u m b i a ) . P r o f . R. P i n c o c k (U.B.C.) donated samples o f b e n z i l and 2,3-butanedione (Eastman O r g a n i c C h e m i c a l s ) . l , 3 - D i p h e n y l - 2 -m e t h y l p r o p e n - l - o n e was p r e p a r e d by f i r s t r e a c t i n g a -methyl cinnamaldehyde (Eastman) w i t h p h e n y l magnesium b r o m i d e , and t h e n o x i d i z i n g t h e r e s u l t i n g a,£-unsaturated a l c o h o l w i t h a c t i v a t e d t f r ^ . 1 ^ The p r o d u c t was p u r i f i e d by column chromatography u s i n g s i l i c a g e l i n 30-60° p e t r o l e u m e t h e r and benzene ( 1 : 1 ) , and t h e n by e l u t i n g w i t h t h i s s o l v e n t m i x t u r e ; t h e a,B-u n s a t u r a t e d k e t o n e was i d e n t i f i e d by i t s mass s p e c t r u m (M+ a t 222, m/e), -158-and i t s nmr (CDCJc^): 6 2 . 2 3 ( s , 3 , C H 3 ) , 7 . 0 - 7 . 7 ( m , l l . p h e n y l + C=C-H). A more d i r e c t p r e p a r a t i o n i n v o l v e s t h e c o n d e n s a t i o n o f b e n z a l d e h y d e 2 and 1 - p h e n y l p r o p a n - l - o n e . The H2 t r a n s f e r r e a c t i o n s were c a r r i e d o ut i n a 10 m l round bottom f l a s k f i t t e d w i t h a septum, a thermometer, and a condenser. The system c o u l d be degassed v i a c o n n e c t i o n s t o a vacuum pump and a N 2 s o u r c e from t h e t o p of t h e condenser. S o l u t i o n s were t h e r m o s t a t t e d i n an o i l b a t h and s t i r r e d u s i n g a m a g n e t i c f l e a . P r o f . W. C u l l e n and K. B r z e z i n s k a k i n d l y p r o v i d e d t h e r e a c t i o n f l a s k and o t h e r f a c i l i t i e s . S t a n d a r d c o n d i t i o n s were m a i n t a i n e d f o r t h e e x p e r i m e n t s : t e m p e r a t u r e o f 83°, 4 ml i s o p r o p a n o l , 0.1 ml w a t e r , 15 mg t r a n s -[H(DMS0) 2]tIrC£ 4(DMS0) 2] ( 5 . 7 x l O ~ 3 M ) , and s u b s t r a t e (0.24M). The a l c o h o l , w a t e r , and c a t a l y s t were f i r s t s t i r r e d under N 2 a t 83° f o r 2h t o form i n s i t u h y d r i d e s p e c i e s . When t h e c h i r a l s u l f o x i d e s were u s e d , IrC£ 3.3H 20 (15 mg) and 3 e q u i v a l e n t s o f s u l f o x i d e were h e a t e d f o r l h i n t h e i s o p r o p a n o l / w a t e r s o l u t i o n . Then s u b s t r a t e (^0.1 ml) was i n j e c t e d and t h e r e a c t i o n was m o n i t o r e d by gas chromatography ( s e e c h a p t e r 2.1). Where p o s s i b l e , t h e r e a c t i o n s were a l s o m o n i t o r e d by nmr. A l l t h e s u b s t r a t e s had peaks w i t h c h e m i c a l s h i f t s between 61.8 and 3.0, o r g r e a t e r t h a n 65.5, so t h a t t h e c o n v e r s i o n o f t h e s u b s t r a t e c o u l d be f o l l o w e d d e s p i t e t h e l a r g e i s o p r o p a n o l and w a t e r peaks. Thus a serum-capped nmr tube w i t h degassed r e a c t i n g s o l u t i o n (under N 2) was a l s o p l a c e i n t h e t h e r m o s t a t t e d o i l b a t h , and s p e c t r a were r e c o r d e d o c c a s i o n a l l y . The p r e s e n c e o f i n d u c e d c h i r a l i t y i n t h e 2 - o c t a n o l p r o d u c t was t e s t -159-f o r u s i n g a c h i r a l l a n t h a n i d e nmr s h i f t r e a g e n t , t r i s [ 3 - ( h e p t a f l u o r o b u -t y r y l ) - d - c a m p h o r a t o ] e u r o p i u m ( I I I ) s u p p l i e d by A l p h a C h e m i c a l s . T y p i c a l l y t h e i s o p r o p a n o l and w a t e r were e v a p o r a t e d from t h e r e a c t i o n s o l u t i o n i n v a c u o , and t h e n t h e r e s i d u e was t a k e n up i n 0.2 m l CCH^; t h i s s o l u t i o n was d e c a n t e d from any s o l i d s and t r a n s f e r r e d t o an nmr t u b e . Then 0.2 ml o f a s t a n d a r d s o l u t i o n o f s h i f t r e a g e n t i n CCl^ was added so t h a t t h e r a t i o o f r e a g e n t t o h y d r o g e n a t e d p r o d u c t was about one. The d i a s t e r e o t o p i c a l l y r e s o l v e d m e t h y l groups a t o t h e h y d r o x y l of 2 - o c t a n o l appear as d o u b l e t s a t 6 ^ 1 5 . ^ 5.2.3. R e s u l t s and D i s c u s s i o n The a t t e m p t s a t t h e asymmetric h y d r o g e n a t i o n o f s a t u r a t e d k e t o n e s a r e summarized i n t a b l e 5.1; t h o s e i n v o l v i n g o l e f i n s a r e g i v e n i n t a b l e 5.2. The l a c k o f e f f e c t i v e c h i r a l i n d u c t i o n i n t h e p r o d u c t s from s u c c e s s f u l l y h y d r o g e n a t e d s u b s t r a t e s u s i n g c a t a l y s t s c o n t a i n i n g TBPTSO may be due t o a c o n c u r r e n t r e d u c t i o n o f t h e c h i r a l s u l f o x i d e , s i n c e an orange compound, c o n t a i n i n g no v ( S 0 ) i r band, p r e c i p t a t e d from t h e r e a c t i o n mixtures.. An e n a n t i o m e r i c e x c e s s i n t h e 2 - o c t a n o l p r o d u c t from t h e MPTSO system may have been t o o s m a l l t o d e t e c t u s i n g t h e c h i r a l s h i f t r e a g e n t method. A n o t h e r p o s s i b i l i t y i s t h a t i r i d i u m m e t a l , formed d u r i n g t h e r e a c t i o n , was t h e s o u r c e of t h e n o n e n a n t i o s p e c i f i c c a t a l y s i s . The b u l k y s u b s t r a t e s s u c h as 1 , 3 - d i p h e n y l - 2 - m e t h y l p r o p e n - l -one and b e n z i l were n o t h y d r o g e n a t e d . -160-T a b l e 5.1 The r e d u c t i o n o f k e t o n e s c a t a l y z e d by I r ( I I I ) - s u l f o x i d e •• Complexes ( a) S u b s t r a t e L i g a n d Time u n t i l 100% c o n v e r s i o n e. e. 2,3-butanedione 2,3-butanedione b e n z i l 2-octanone 2-octanone DMSO (R.R)-PTSE DMSO R-MPTSO R-TBPTSO 18h 72h no r e d u c t i o n 4 8 h ( c ) 25% c o n v e r s i o n i n 14h(e) (b) (b) <4% <4% (d) (d) (a) The s t a n d a r d c o n d i t i o n s were: T=83°, 4 ml 2 - p r o p a n o l , 0.1 ml H 20, 0.24M s u b s t r a t e , [IrCJc.4(DMSO)2JI" o r ["IrC£ 3(sulfoxide) 3"]= 6 x l O _ 3 M . 9 (b) A c e t o i n and p r o d u c t s from r e d u c t i v e d i m e r i z a t i o n were o b s e r v e d by G.C. but t h e y c o u l d n o t be i s o l a t e d . (c) Some I r m e t a l formed. (d) The e.e. of t h e 2 - o c t a n o l p r o d u c t was d e t e r m i n e d u s i n g t h e c h i r a l s h i f t r e a g e n t . An e.e. o f l e s s t h a n ^ 4 % w o u l d n o t be d e t e c t e d j u d g i n g from t h e s i g n a l t o n o i s e r a t i o o f t h e nmr s p e c t r a . (e) An orange p r e c i p i t a t e , presumably an I r - s u l f i d e complex, formed. -161-T a b l e 5.2 The r e d u c t i o n o f o l e f i n s c a t a l y z e d by I r ( I l l ) - s u l f o x i d e complexes (a) S u b s t r a t e L i g a n d Maximum Rate o f H y d r o g e n a t i o n 3-methyl-3-penten-2-one 4-methyl-3-penten-2-one 1 , 3 - d i p h e n y l - 2 - m e t h y l -p r o p e n - l - o n e i t a c o n i c a c i d e t h y l a t r o p a t e N - a c e t a m i d o c i n n a m i c a c i d DMSO R-TBPTSO DMSO DMSO R-TBPTSO (R,R)-PTSE DMSO DMSO DMSO (7.5±2.0)xlO~ 4M m i n - 1 100% c o n v e r s i o n i n 400 m i n ^ 85% c o n v e r s i o n i n 68h -4 -1 < l x l 0 M min (c) (d) (a) The s t a n d a r d c o n d i t i o n s were: T=83°, 4 ml 2 - p r o p a n o l , 0.1 ml H 20, 0.24 M s u b s t r a t e , [ I r C ^ C D M S O ^ ] - o r ["IrC£3 ( s u l f o x i d e ) 3 " ] = 6x10" 3M. (b) The p r o d u c t was shown by G.C. and nmr t o be t h e s a t u r a t e d k e t o n e i n >90% y i e l d . A w h i t e D M S O - h y d r i d o i r i d i u m complex ( v ( I r - H ) = 2250 cm--'-) p r e c i p i t a t e d a t t h e end of t h e r e a c t i o n . (c) C o n d i t i o n s used h e r e were: T=83°, 6 m l 2 - p r o p a n o l , 0.2 m l H 20, 0.25 ml s u b s t r a t e , t I r ] = 1 . 3 x l O " 2 M , [ s u l f o x i d e ] = 4 x 1 0 " 2 M . A c o n c e n t r a t e d f r a c t i o n o f s a t u r a t e d k e t o n e i n 2 - p r o p a n o l was d i s t i l l e d f rom t h e r e a c t i o n m i x t u r e b u t i t had no o p t i c a l r o t a t i o n . An orange I r - s u l f i d e complex p r e c i p i t a t e d d u r i n g t h e r e a c t i o n . (d) An u n i d e n t i f i e d y e l l o w I r complex p r e c i p i t a t e d . -162-5.3. S o l v e n t T r a n s f e r H y d r o g e n a t i o n o f a , g - U n s a t u r a t e d A l d e h y d e s t o t h e U n s a t u r a t e d A l c o h o l s C a t a l y z e d by H y d r i d o i r i d i u m S u l f o x i d e Complexes. 5.3.1. I n t r o d u c t i o n A w i d e v a r i e t y o f t r a n s i t i o n m e t a l complexes a r e a v a i l a b l e f o r the c a t a l y t i c h y d r o g e n a t i o n o f t h e o l e f i n i c bond i n a , g - u n s a t u r a t e d c a r b o n y l compounds, a l t h o u g h a prob l e m e n c o u n t e r e d f o r a l d e h y d e sub-16 s t r a t e s can be d e a c t i v a t i o n o f t h e c a t a l y s t by CO a b s t r a c t i o n . To a c c o m p l i s h t h e s e l e c t i v e h y d r o g e n a t i o n o f t h e c a r b o n y l f u n c t i o n ( e . g . , r e a c t i o n 5 .6), e s p e c i a l l y f o r u n h i n d e r e d s u b s t r a t e s , i s more d i f f i c u l t , and t o our knowledge o n l y one e f f i c i e n t homogeneous c a t a l y s t has been d i s c o v e r e d 1 ^ and t h i s i n v o l v e s t h e use o f [RhC£(CO) 2] 2 i - n t h e p r e s e n c e o f t e r t i a r y amines (and a c o r r e s p o n d i n g p o l y m e r - s u p p o r t e d system) under 2 h y d r o f o r m y l a t i o n c o n d i t i o n s ( e . g . 80 kg/cm , C0/H 2=1, 90°C). H RCH=CHCH0 ^ RCH=CHCH20H (5.6) The p r e s e n t work shows t h a t Henbest's c a t a l y s t system (see s e c t i o n 5.2) a t 80°C under a N 2 atmosphere, c o n v e r t s a , g - u n s a t u r a t e d a l d e h y d e s t o t h e u n s a t u r a t e d a l c o h o l (see t a b l e 5.3). 5.3.2. E x p e r i m e n t a l C r o t o n a l d e h y d e , c i n n a m a l d e h y d e , and a-m e t h y l cinnamaldehyde were o b t a i n e d from Eastman O r g a n i c C h e m i c a l s . The t e c h n i q u e s and s t a n d a r d c o n d i t i o n s n o t e d i n s e c t i o n 5.2.2 were used. The c i n n a m y l a l c o h o l p r o d u c t s can be r e c o v e r e d by e v a p o r a t i o n o f t h e r e a c t i o n s o l v e n t f o l l o w e d by chromatography o f t h e r e s i d u e on a l u m i n a . 5.3.3. R e s u l t s and D i s c u s s i o n W i t h cinnamaldehyde a t 90% c o n v e r s i o n , t h e r e i s e s s e n t i a l l y no -163-r e d u c t i o n o f t h e o l e f i n i c bond; c i n n a m y l a l c o h o l i s formed i n h i g h y i e l d s b u t , depe n d i n g on t h e w a t e r c o n t e n t , up t o 12% b y - p r o d u c t s 18 ( i n c l u d i n g e t h e r s ) were d e t e c t e d . a - M e t h y l cinnamaldehyde a t t h e same 90% c o n v e r s i o n g i v e s t h e u n s a t u r a t e d a l c o h o l w i t h 100% s e l e c t i v i t y . C r o t o n a l d e h y d e , l e s s h i n d e r e d a t t h e o l e f i n i c bond, s t i l l g i v e s t h e t r a n s - 2 - b u t e n - l - o l w i t h >90% s e l e c t i v i t y a t 90% c o n v e r s i o n . The maximum s e l e c t i v i t i e s a c h i e v e d f o r t h e s e t h r e e s u b s t a n c e s u s i n g t h e Rh systems were 90, 87, and 50%, r e s p e c t i v e l y . " ' " 7 Use o f Ir C J l 2 H ( D M S O ) 3 , 3_7, i n s t e a d o f t h e i n s i t u c a t a l y s t f r o m t r a n s - [ H ( D M S O ) 2 ] [ I r C J l 4 ( D M S O ) 2 ] , s h o r t e n e d r e a c t i o n t i m e s c o n -s i d e r a b l y ( t a b l e 5.3). A t h i g h e r w a t e r c o n c e n t r a t i o n s (<10:1 V/V 2 - p r o p a n o l - H 2 0 ) , t h e H 2 t r a n s f e r r e a c t i o n s were s t r o n g l y i n h i b i t e d , and t h i s i s l i k e l y due t o t h e d e c o m p o s i t i o n o f t h e h y d r i d e , _3_7_, w h i c h t u r n s y e l l o w i n t h e p r e s e n c e o f m o i s t u r e . 13 G u l l o t t i e t a l , , u s i n g i n s i t u s u l f o x i d e c a t a l y s t s formed from IrC£ 3-3H 20,had used l o n g r e a c t i o n t i m e s (72h) and had n o t e d r e d u c t i o n o f t h e o l e f i n i c bond as w e l l as t h e c a r b o n y l group w i t h u n s a t u r a t e d a l d e h y d e s u b s t r a t e s . W i t h t h e system d e s c r i b e d h e r e f u r t h e r r e d u c t i o n o f c i n n a m y l a l c o h o l and t h e 2 - b u t e n - l - o l t o t h e s a t u r a t e d a l c o h o l s was r e l a t i v e l y s l o w ; a-methyl c i n n a m i c a l c o h o l showed no r e d u c t i o n even a f t e r 20h. The r e a s o n s f o r t h e p r e f e r e n t i a l r e d u c t i o n o f t h e c a r b o n y l m o i e t y a r e n o t t o o c l e a r , s i n c e t h e same c a t a l y s t system e f f e c t s t h e 3 h y d r o g e n a t i o n o f t h e o l e f i n i c bond i n a , g - u n s a t u r a t e d k e t o n e s and a l s o , b u t more s l o w l y , t h e r e d u c t i o n o f s a t u r a t e d c y c l o h e x a n o n e s t o -164-T a b l e 5.3 H y d r o g e n a t i o n o f a ,ig-Unsaturated A l d e h y d e s S u b s t r a t e Time f o r 90% Conv.,min. A t 90% C o n v e r s i o n % Unsat. % S a t . % S a t . A l c o h o l A l d e h y d e A l c o h o l cinnamaldehyde a-methyl cinnamaldehyde 250 c r o t o n a l d e h y d e 50 80 ( o r 1 5 ( b ) ) 78 90 85 (c) t r a c e 0 5 0 0 t r a c e (a) (b) (c) 0.25 M s u b s t r a t e , i n s i t u 10 ZM I r , i n i s o p r o p a n o l - w a t e r (30:1 V/V) a t 80°C under N 2 . U s i n g 10~ 2M HIrC£ 2(DMSO) 3, 10~ 2M aqueous HC£, 30:1 V/V i s o p r o p a n o l - w a t e r . About 12% b y - p r o d u c t s ; a t 300:1 V/V i s o p r o p a n o l - w a t e r , t h e % c i n n a m y l a l c o h o l = 8 5 % w i t h 5% b y - p r o d u c t s ; a t 10:1 V/V, t h e h y d r o g e n a t i o n was c o m p l e t e l y i n h i b i t e d . -165-18 t h e a l c o h o l s . S t e r i c f a c t o r s c o u l d f a v o u r r e d u c t i o n o f t h e a l d e h y d e group v e r s u s a k e t o n e group b u t , s i n c e t h e c a t a l y s t s w i t h p h o s p h i n e -t y p e l i g a n d s i n v a r i a b l y r e d u c e t h e o l e f i n i c bond i n a , 3 - u n s a t u r a t e d 15 17 19 a l d e h y d e s whether u s i n g gas o r a hydrogen donor s o l v e n t ' ' , e l e c t r o n i c arguments a r e f a v o u r e d . Some exchange d a t a 1 w i t h IrCJc^HCDMSO) i n d i c a t e more a c i d i c c h a r a c t e r i n t h e hydrogen t h a n i n t h e c a s e o f c o r r e s p o n d i n g p h o s p h i n e complexes, and t h i s c o u l d enhance a d d i t i o n o f t h e m e t a l h y d r i d e a t t h e c a r b o n y l e.g. H + RCH=0 -> RCH-0 — *RCH(OH) -> RCH„OH (5.7) I r H I r - H I r R e d u c t i o n of a l d e h y d e groups v i a t r a n s i t i o n - m e t a l h y d r i d e c a t a l y s t s i s u s u a l l y c o n s i d e r e d t o be enhanced w i t h i n c r e a s i n g h y d r i d i c c h a r a c t e r v i a a d d i t i o n o f t h e m e t a l h y d r i d e i n t h e r e v e r s e d i r e c t i o n t o t h a t shown i n ( 5 . 7 ) , but b o t h modes of a d d i t i o n seem f e a s i b l e ( r e f . 16, pp. 165-167, 182, 188). -166-6. V i b r a t i o n a l A n a l y s i s o f Oxygen-Bonded S u l f o x i d e Complexes 6.1. I n t r o d u c t i o n D e s p i t e the' c o m p l e x i t y o f i n f r a r e d s p e c t r a o f c o o r d i n a t e d oxygen donors o f t h e t y p e 0=L, f o r example, s u l f o x i d e s , p h o s p h i n e o x i d e s , and p y r i d i n e o x i d e s , a number o f r e c e n t s y n t h e t i c p a p e r s r e p o r t t h e l o c a t i o n o f v(M-K)) and v(LO) modes f o r a wide range o f m e t a l s and l i g a n d s . P a r t i -c u l a r l y r e l i a b l e a r e d a t a f o r DMSO ( d i m e t h y l s u l f o x i d e ) and TMSO ( t e t r a -m e t h y l e n e s u l f o x i d e ) complexes based on t h e d e t a i l e d v i b r a t i o n a l s t u d i e s 1 2 3 of Adams and Trumble and Berney and Weber ' . The e v i d e n c e f o r a s s i g n i n g Mf-0 c h a r a c t e r t o c e r t a i n bands i s c o m p r i s e d o f t h e f o l l o w i n g : ( i ) t h e bands cannot be a t t r i b u t e d t o f r e e l i g a n d v i b r a t i o n s , ( i i ) t h e y a r e n o r m a l l y o f medium i n t e n s i t y and a r e m e t a l - s e n s i t i v e , ( i i i ) t h e y a r e s h i f t e d t o l o w e r f r e q u e n c y when t h e d e u t e r a t e d l i g a n d i s u s e d , u s u a l l y s u g g e s t i n g t h a t 0=L moves as a whole d u r i n g M-K) s t r e t c h i n g , ( i v ) t h e y y i e l d a c o n s t a n t r a t i o o f v(M-K)) v a l u e s f o r two d i f f e r e n t l i g a n d complexes o f a g i v e n m e t a l , f o r example, 0.93 f o r TMSO v e r s u s DMSO 3, (v) t h e y sometimes agree w i t h c r y s t a l f i e l d s t a b i l i z a t i o n energy 2 3 7 o r d e r i n g o f a s e r i e s o f t r a n s i t i o n m e t a l -MD=L complexes ' ' . The l a s t c r i t e r i o n i n d i c a t e s t h a t m e t a l - l i g a n d bond s t r e n g t h s , w h i c h r e f l e c t s u c h t r e n d s , can be e s t i m a t e d from t h e s e d a t a , e s p e c i a l l y i f f o r c e c o n s t a n t s c o u l d be c a l c u l a t e d . The s u c c e s s o f such c a l c u l a t i o n s i n d e s c r i b i n g t h e i n f r a r e d s p e c t r a 3 of h e x a c o o r d i n a t e TMSO complexes encouraged us t o a n a l y z e o ur c o m p i l a t i o n -167-of v(SO) and v(MO) d a t a f o r s u l f o x i d e complexes d e s c r i b e d i n t h e l i t e r a t u r e and i n t h i s t h e s i s . 6.2. C a l c u l a t i o n s A rough c o r r e l a t i o n was i n i t i a l l y n o t e d between t h e bands a s s i g n e d as v(M-O) and t h e f r e q u e n c y r e d u c t i o n o f v(SO) on c o o r d i -n a t i o n o f s u l f o x i d e t o m e t a l . D a t a a r e g i v e n i n t a b l e 6.1 f o r 0-bonded DMSO and TMSO i n some t r a n s i t i o n m e t a l complexes. There i s sometimes a m b i g u i t y i n t h e assignment o f t h e 0-bonded S O - s t r e t c h w i t h i n 15 16 c e r t a i n o f th e DMSO complexes because o f t h e m e t h y l r o c k i n g modes ' (two Av(SO) v a l u e s a r e t h u s g i v e n ) , b u t n e v e r t h e l e s s v(M-0) i n c r e a s e s g e n e r a l l y w i t h i n c r e a s i n g Av(S-O). Such a r e l a t i o n s h i p has been 19 s u g g e s t e d , b ut n o t p r e v i o u s l y documented. F i g u r e 6.1 shows t h e d a t a p l o t t e d f o r systems where t h e r e i s t hought t o be no a m b i g u i t y . 3+ Except f o r t h e [ C r L , ] complexes (L=DMS0, TMSO), t h e d a t a f a l l w i t h i n D a r e m a r k a b l y w e l l - d e f i n e d band f o r a l l t h e mono-, b i - , and t r i v a l e n t s p e c i e s . F i g u r e 6.1 u n f o r t u n a t e l y does not a i d i n e s t a b l i s h i n g t h e 2+ c o r r e c t a s s i g n m e n t s f o r v(SO).and p^(CE^) i n t h e [M(DMSO)^] s p e c i e s ( M = M n ( I I ) , F e ( I I ) , C o ( I I ) , N i ( I I ) ) . We th o u g h t t h a t a more m e a n i n g f u l c o r r e l a t i o n s h o u l d be o b t a i n e d u s i n g t h e c o r r e s p o n d i n g f o r c e c o n s t a n t s w h i c h s h o u l d c o r r e c t t h e d e v i a t i o n s from t h i s l i n e a r r e l a t i o n s h i p o f some i o n s such as C r ( I I I ) and A£(III). -168-T a b l e 6.1 I n f r a r e d i d a t a — f o r 0-bonded DMSO and TMSO complexes Complex— A v ( S O ) - v(MO) R e f e r e n c e 1. [ C r ( D M S 0 ) , ] 3 + 127 529 2,8 2. 2+ c i s - [ P t ( D M S O ) (DMSO) 2] 176,158 517 9 3. cis-[Pd(DMSO) 2(DMSO) ] 2 + 135,150 493 9 4. mer-RhCl 3(DMSO)(DMSO) 120 491 1 0 , c h a p t e r 4 5. c i s - R u C l 2 ( D M S O ) ( D M S 0 ) 3 140 480 11,12 6. [ F e ( D M S O ) , ] 3 + 115 475 8,13 7. [Rh(COD)(DMSO) ] 105 473,465 c h a p t e r 3 8. [Rh(COD)(PPh ) ( D M S O ) ] + 97 450 c h a p t e r 3 [Mn(DMSO),] 100 o r 55 418 2,8,14 2+ [Fe(DMSO) J 105 o r 70 438,415 2,8,14 2+ [Co(DMSO),] 105 o r 61 436 2,8,15,16 2+ [Ni(DMSO),] 105 or 55 444 2,8,14 2+ [Cu(DMSO) 4] 115 o r 67 467 8,15,17 tr a n s - C u C l 2 ( D M S O ) 132 o r 75 496,481 1,8,18 9. [ C r ( T M S O ) , ] 3 + 90 484 3,13 10. 2+ c i s - [Pt (TMSO) 2 (TMSO) ] 143,127 480,469 9 11. cis-[Pd(TMSO) 2(TMSO) ] 2 + 121,102 473,458 9 12. [ F e ( T M S O ) , ] 3 + 102 440 3,13 13. [Rh(COD)(PPh )(TMSO)] 87 432 c h a p t e r 3 14. [ N i ( T M S O ) 6 ] 52 413 3,13 15. [ C o ( T M S O ) , ] 2 + 54 406 3,13 16. 2+ [Fe(TMSO),] 55 397 3,13 17. 2+ [Mn(TMSO) ] — 6 48 388 3,13 a. M u l l s ; i n cm _b DMSO and DMSC) d e s i g n a t e S- and 0-bonded, r e s p e c t i v e l y (and f o r TMSO) c: Frequency s h i f t on 0 - c o o r d i n a t i o n . 2 0 0 S 150-1 u t—\ o ^ 1 0 0 <1 5 0 H o2 ^2 10 8 5 JO J l 4 J2 >8 .13 .17 ,16 J 5 J4 ON I 4 0 0 F i g u r e 6.1. 4 5 0 \) (MO), c m " 1 5 0 0 P l o t of f r e q u e n c y s h i f t of v(S0) on c o o r d i n a t i o n o f 0-bonded s u l f o x i d e v s . v(M0);O, d i m e t h y l s u l f o x i d e complexes; • , t e t r a m e t h y l e n e s u l f o x i d e complexes. Numbers ref e r -t o complexes l i s t e d i n t a b l e 6.1. - 1 7 0 -F i g u r e 6.2 3 The bent MOL model ( f i g u r e 6.2) o u t l i n e d by Berney and Weber w i l l y i e l d t h e most u s e f u l r e s u l t s f o r t h e m o l e c u l e s o f v a r i e d geometry d i s c u s s e d h e r e . I n t h e u s u a l e x p e r i m e n t o n l y v ( S 0 ) and v(M0) a r e l o c a t e d . A c c o r d i n g l y , o n l y t h e c r u d e t r e a t m e n t i n v o l v i n g a d i a g o n a l F m a t r i x i s j u s t i f i e d so t h a t t h e pro b l e m can be s o l v e d e a s i l y by u s i n g 20 t h e expanded s e c u l a r e q u a t i o n (6.1) f o r a bent t r i a t o m i c . X 3 - X 2 ( A F 1 1 + B F 2 2 + C F 3 3 ) + A ( D F 1 1 F 2 2 + E F 2 2 F 3 3 + G F 3 3 F 1 1 ) - H F 1 1 F 2 2 F 3 3 = 0 (6.1) The F m a t r i x has d i a g o n a l e lements F i i = F M 0 ' F 2 2 = F 0 L ' a n d F 3 3 = F M O L ' t h e a n g l e b e n d i n g c o n s t a n t . The c o n s t a n t s A,B,C,D,E,G,H, d e r i v e d from r e f e r e n c e 20, a r e : yM P L V M L A = y M + y 0 B = y L + y 0 C = 2~ + 2~ + ~T~2 r0M r 0 L r 0 M r 0 L D = y2sinVuMyL+uLy0+yoyM E = OL 2 , R M L - r 0 L S I A V L y 0 ( 2 2 ) + ~ ~ ~ r 0 M r 0 L "OM Y L y0 ( R ML + r0M) • y0 Y M 2 2 _2 r 0 M r 0 L "OM G = + 2 2  y 0 ( ^ OM 2 • 2 A " r 0 M S i n • 2 2 r 0 M r 0 L ) y M y L OL y L y 0 U0L y 0 y M ( r M L + r 0 L ) 2 2 r r OM OL -171-_ 4 ( yL +V+ y L ( y M + V + V M L ( V V + P M P L t J 0 ( r M L + r O M + r O L ) 2 2 2 2 2 2 r0M r 0 L rOM rOL rOM rOL The y , y , and y a r e t h e masses, i n a.m.u., of t h e m e t a l , t h e oxygen, and t h e s u l f o x i d e ( s u b t r a c t i n g t h e mass o f t h e ox y g e n ) , r e s p e c t i v e l y . The unknowns o f t h e t h r e e s i m u l t a n e o u s e q u a t i o n s a r e ^ Q ' ^ O L ' A N ^ <S (MOL)=A,j, w h i c h i s n o r m a l l y t o o low i n f r e q u e n c y t o be l o c a t e d i n o i n f r a r e d a n a l y s e s . The v a l u e ^ j O L = ^ ' " ^ m ^ y n e A d e t e r m i n e d by more 3 e l a b o r a t e c a l c u l a t i o n s was us e d , o r , i f v a r i e d , had t h e same s e n s i t i -3 v i t i e s t o F a n d F ^ p r e v i o u s l y d e s c r i b e d . E q u a t i o n (6.1) can be s o l v e d f o r F ^ o r T?^ u s i n g e q u a t i o n s (6.2) and ( 6 . 3 ) . T h e r e f o r e w i t h o A^ c o r r e s p o n d i n g t o v(MO) and an i n i t i a l guess f o r F 2 2 = 6 . 0 mdyne/A, F ^ can be o b t a i n e d and used w i t h A2 c o r r e s p o n d i n g t o v(OL) t o s o l v e f o r 1?22" Thus i t e r a t i v e l y t h e e q u a t i o n s r a p i d l y c onverge t o a u n i q u e s o l u t i o n . F 1 1 = [ A 3 - A 2 ( B F 2 2 + C F 3 3 ) + A 1 E F 2 2 F 3 3 ] / [ A 2 A - A 1 ( D F 2 2 + G F 3 3 ) + H F 2 2 F 3 3 ] (6.2) F 2 2 = [ A 2 - A 2 ( A F 1 1 + C F 3 3 ) + A 1 E F 3 3 F 1 1 ] / [ A 2 B - A 2 ( D F 1 1 - r E F 3 3 ) + H F 1 1 F 3 3 ] (6.3) The a p p r o x i m a t e s t r u c t u r a l p a r a m e t e r s used i n c a l c u l a t i n g t h e G m a t r i c e s a r e a l l w i t h i n 5% o f known c r y s t a l l o g r a p h i c a l l y d e t e r m i n e d v a l u e s ( f o r example see r e f e r e n c e s 11,21,22,23). These were an MOL a n g l e o o o f 124°, an LO=SO l e n g t h o f 1.54A, an MO l e n g t h o f 1.36A p l u s t h e i o n i c 23 r a d i u s o f t h e m e t a l i o n , and an L mass e q u a l t o t h e l i g a n d mass minus 16.0 f o r oxygen ( e . g . , 88 amu f o r TMSO). -172-As m entioned above, a c o m p l i c a t i o n i n t h e a n a l y s i s of t h e i n f r a r e d s p e c t r a of 0-bonded DMSO complexes i s t h e p r e s e n c e o f m e t h y l r o c k i n g v i b r a t i o n s p^CCH^) w h i c h a r e s i m i l a r i n energy to t h e S-0 8 15 16 25 s t r e t c h ' ' ' , and w h i c h may borrow i n t e n s i t y o r be c o u p l e d t o t h e 2+ -1 l a t t e r . I n d e ed, Co(DMSO), has two i n t e n s e bands a t 994 and 950 cm , b 2+ -1 whereas Co (DMSO-d^.) ^  has o n l y one a t 970 cm . A l t h o u g h t h e p^CCH^) bands a r e s h i f t e d w e l l b e l o w 900 cm on d e u t e r a t i o n i t i s n o t o b v i o u s t h a t v ( S 0 ) s h o u l d a l s o s h i f t , and t h i s a rgues perhaps i n f a v o u r o f c o u p l i n g between modes. I n t h i s s t u d y , F and F ^ were c a l c u l a t e d u s i n g t h e f r e q u e n c i e s o f a l l bands thought t o have v(S0) c h a r a c t e r . T h i s y i e l d e d t h e a v e r a g e v a l u e s F Q L and F ^ w h i c h , i n f a c t , were found t o obey t h e same r e l a t i o n s h i p c a l c u l a t e d f o r t h e DMSO-d, and TMSO —o complexes, where no a m b i g u i t y i n t h e v(SO) v a l u e e x i s t s . C e r t a i n l y , t h e use o f t h e s u l f o x i d e s w i t h no p^CCH^) v i b r a t i o n s p r o v i d e s t h e more r e l i a b l e d a t a , a l t h o u g h f o r some DMSO complexes t h e g r e a t e r i n t e n s i t y o f v ( S 0 ) o r i t s s i m i l a r p o s i t i o n found i n c o r r e s p o n d i n g TMSO o r DMSO-d, —6 compounds o f t e n a l l o w s i t s u n i q u e assignment ( c h a p t e r 3, r e f e r e n c e s 6,26, 2 7 ) . Average F v a l u e s were a l s o e s t i m a t e d i n t h e c a s e s where v(M0) s p l i t t i n g s were o b s e r v e d . 6.3. R e s u l t s and D i s c u s s i o n T a b l e 6.2 l i s t s t h e f o r c e c o n s t a n t s c a l c u l a t e d f o r t h e compounds w i t h t h e most r e l i a b l e v ( S 0 ) and v(M0) v a l u e s ( e i t h e r t h e DMSO-dg and/or TMSO c o m p l e x . i s c h a r a c t e r i z e d , as w e l l as t h e DMSO one ) . I n a l l c a s e s o t h e b e n d i n g constant- F„_,. was h e l d a t 0.35 mdyne A i n a c c o r d w i t h p r e v i o u s MOL COMPLEX [MnLg] 2+ [FeL 6] [CoL g] [NiL g] 2+ 2+ 2+ DMSO v(SO) v(MO) F_ F OL MO -1 -1 o o cm cm md/A md/A ^ ± ± l ^ t i ^ s u l f o x i d e c o f f l p l e x e s DMSO-d v(SO) v(MO) F TMSO OL FMO v ( S 0 > V ( M ° ) F m MO v(MOL) Ref. A£Me 3L AiEt^L AfcEt-CllL 3+ [A<IL 6] J + [ F e L 6 ] 3 + -[Rh(COD)L 2] + -tRh(COD)(PPh 3)L] + [ C r L , ] 3 + -mer-RhCfl,L„L d 3^2% ^ i s - t P d L ^ ] 2 4 " : i s - [ P t L * L 2 J 2 + 955 418 6.79 1.45 1000 950 438 '6762 T753 985 415 950 436 6766 1763 970 409 994 950 444 6768 1770 1000 992 490 6.91 1.63 971 465 985 473 6797 1.50 982 452 1001 991 505 6.86 1.75 984 485 960 539 "6731 2700 965 515 964 526 970 522,506 974 388 7.22 967 397 7.09 6.81 1.40 968 406 7.07 970 413 7.09 6.76 1.58 6.97 1.35 1.22 122 1.30 123 1.39 123 1.45 124 6.92 1.60 940 480 6.06 2.05 950 473 6717 1723 950 443 4 6 5 435 958 450 6.36 2.01 950 928 529 5.67 2.58 928 935 491 5.86 2.49 935 905 920 493 1731 2.55 904 916 879 897 b 517 4790 3.23 6.58 1.85 953 499 6.68 921 443 6.25 6.38 1.90 6.41 1.80 935 432 6.44 5.87 2.33 932 484 6.27 6.05 2.21 M O L - ° - 3 5 ndyne A - B a r Indicates an average ', ~ d a g e ^"0D-l,5-cyclooctadlene - L*=sulfur 5.68 2.24 901 473 1792 920 458 879 480 1745 895 469 d 1.75 159 1.71 128 1.85 107 2.09 132 2724 1U 2.58 102 2,3,8,13,14 2,3,8,13,14 2,3,8,13,15,16 2,3,8,13,14 26 26 26 3,6 3,8,13 Chapter 3 Chapter 3 2,3,8,13 Chapter 4 9,27 •bonded sulfoxide -174-3 c a l c u l a t i o n s . T h i s a p p r o x i m a t i o n w i l l be d i s c u s s e d below. The F,„ MO o and F v a l u e s c a l c u l a t e d f o r TMSO+M a r e c o n s i s t e n t l y 0.07 mdyne/A 3 h i g h e r and l o w e r , r e s p e c t i v e l y , t h a n t h o s e o b t a i n e d by Berney and Weber , not a s e r i o u s d i s c r e p a n c y . I t must be emphasized t h a t t h e s e c o n s t a n t s a r e c r u d e a p p r o x i m a t i o n s t o t h e t r u e v a l u e s , s i n c e t h e y a r e based on 2 17 f r e q u e n c i e s t h a t may not be pure M-0 o r 0-S s t r e t c h e s ' . F o r example, 3 s i g n i f i c a n t d e r e a l i z a t i o n o f v i b r a t i o n a l energy i s e x p e c t e d and ob s e r v e d f o r complexes w i t h l i g h t i o n s l i k e Al(III).The F v a l u e s , w h i c h a r e UJ-i c a l c u l a t e d u s i n g v (S0) v a l u e s , a r e p r o b a b l y h i g h e r t h a n t h e t r u e F up c o n s t a n t s ; p r e d i c t e d v a l u e s o f v(MOL) g i v e n i n t a b l e 6.2 f o r TMSO-^M systems a r e l i k e l y l o w , e s p e c i a l l y i f t h e y a r e t o c o r r e s p o n d t o 6(ML) 1 3 v a l u e s . 1 ' N e v e r t h e l e s s , t h e F and F ^ numbers g i v e t h e t r u e s t i d e a o f M-0 and 0-S bond s t r e n g t h s g i v e n t h e l i m i t e d d a t a , w h i c h a r e c o m p r i s e d o f f a i r l y w e l l known s t r u c t u r a l p a r a m e t e r s but o n l y two s t r e t c h i n g f r e -q u e n c i e s . E s s e n t i a l l y F a r e v(M0) v a l u e s c o r r e c t e d f o r t h e mass and s i z e o f t h e i o n s and l i g a n d s . -175-T a b l e 6.3. V i b r a t i o n a l d a t a f o r o t h e r s u l f o x i d e c o m p l e x e s ^ Complex v(SO) -1 v(M0) -1 F OL 0 F MO o Ref. cm cm mdyne/A mdyne/A [Ca(TMSO) J 2 + b 1019 372 8.00 1.00 13 [Zn(TMSO) J 2 + 6 973 399 7.16 1.36 3 HgC£ 2(DMSO) 2 992,943 410 6.59 1.71 28 Hg(SCN) 2(DMSO) 2 952,935 424 6.19 1.88 28 Mo0 2C£ 2(DMSO) 2 986^ 454,436 6.80 1.89 29 M o ( E t 2 N C S ) 2 ( N 3 ) ( N O ) ( D M S O ) 955 ^ 450 6.32 1.95 30 [ C u ( D M S O ) 4 ] 2 + 940,988 467 6.44 1.96 8,15,17 trans-CuC£ 2(DMSO) 2 923,980 496,481 6.18 2.21 1,8,18 cis-RuC£ 2(DMSO) (DMSO) 915 480 5.62 2.36 11,12 La(NO_) 0(DMSO), J 3 4 1000 40 2 - 7.11 1.58 31,32 Nd(NO„)„(DMSO) / 3 J 4 1000 405- 7.10 1.61 31,32 Y b ( N 0 3 ) 3 ( D M S O ) 3 1000 420 3- 7.05 1.79 31,32 L u ( N 0 3 ) 3 ( D M S O ) 3 1000 422 - 7.04 1.82 31,32 — The d a t a f o r t h e l a n t h a n i d es were not used i n t h e c o r r e l a t i o n s because o f t h e d i f f i c u l t y i n a s s i g n i n g v(MO). — The band r e p o r t e d a t 1030 or 1024 cm 1 . xs more l i k e l y t o be p r (CH 3> F i g u r e 6.3. C o r r e l a t i o n o f f o r c e c o n s t a n t d a t a f o r TMSO complexes; F t a k e n 0.35 mdyne/A. M 0 L -177-When F Q L i s p l o t t e d a g a i n s t ( f i g u r e 6.3) f o r a l l t h e TMSO complexes ( t a b l e s 6.2,6.3), a good l i n e a r c o r r e l a t i o n r e s u l t s . To 95% c o n f i d e n c e a l i n e a r l e a s t s q u a r e s f i t , w h i c h n e g l e c t s t h e C a ( I I ) d a t a , g i v e s F Q L = -(1.30±0.22)F M O + (8.85±0.38) w i t h a c o r r e l a t i o n c o e f f i c i e n t r=0.97. The o v e r a l l t r e n d o f S-0 bond weakening w i t h i n c r e a s i n g M-0 bond s t r e n g t h i s q u a l i t a t i v e l y e x p l a i n e d by t h e r e d u c t i o n o f oxygen ( p ^ ) - ^ s u l f u r ( d ^ ) d o u b l e bond c h a r a c t e r as 33 t h e m e t a l draws e l e c t r o n d e n s i t y from the oxygen f o r s t r o n g e r b o n d i n g P e r h a p s s u r p r i s i n g i s t h e h i g h e r s t r e n g t h o f " s o f t " m e t a l - " h a r d " oxygen l i n k a g e s w i t h R h ( I ) , P d ( I I ) and P t ( I I ) , a l t h o u g h t h e r e i s s i m i l a r b e h a v i o u r , a t l e a s t f o r P d ( I I ) and P t ( I I ) , w i t h o x a l a t e s and v a r i o u s c a t i o n i c 27 complexes . I t i s our f e e l i n g t h a t t h e c h a r g e on t h e m e t a l , and t h e t r a n s l i g a n d ( n o r m a l l y a s o f t e r one such as S-bonded s u l f o x i d e ) c r e a t e a " h a r d " s i t e , and t h e s t r e n g t h o f M-*-0 band i s t h e n d e t e r m i n e d by t h e e l e c t r o n e g a t i v i t y x o f t h e i o n . T h i s would a l s o e x p l a i n why t h e s t e r i -c a l l y u n h i n d e r e d complex [Rh(COD)(DMSO) 2] + of t h e s o f t R h ( I ) c e n t r e d i s p l a y s 0- i n s t e a d o f S - c o o r d i n a t i o n ( s e e c h a p t e r 3 ) . I n d e e d , t h e M-MD bond 35 36 s t r e n g t h o r d e r g e n e r a l l y f i t s i n w e l l w i t h t h e o r d e r o f x v a l u e s ' (X i n b r a c k e t s ) : C a i : t ( 1 . 0 0 ) < M n I X ( 1 . 5 5 ) ^ e ^ l . 8 3 ) < Z n I X ( 1 . 6 5 ) < C o i : C ( l . 90) <Ni I I(1.91)<Fe I I I(1.96)<A£ I I I(>1.61)<Rh I(2.2)<Cr I I(>1.66)<Pd I I(2.20) <Vt^(2.28).Although Z n ( I I ) i s o r d e r e d i n c o r r e c t l y a c c o r d i n g t o x, i t i s i n i t s u s u a l p o s i t i o n i n terms of t h e I r v i n g - W i l l i a m s o r d e r (see a l s o r e f e r e n c e 3 on t h i s p o i n t ) . I n t e r a c t i o n s o f v(M0) w i t h o t h e r v i b r a t i o n a l modes p r o b a b l y a c c o u n t f o r t h e h i g h e r t h a n e x p e c t e d F ^ v a l u e s f o r A£(III) and C a ( I I ) ; o f f - d i a g o n a l c o n s t a n t s i n t h e F m a t r i x -178-3 t e n d t o l o w e r t h e F.,,. v a l u e o f -Ail ( I I I ) , -though a d i f f e r e n t a n a l y s i s MO o r has y i e l d e d an F.,_ f o r k l ( I I I ) o f 1.80 mdyne/A. MO C r ( I I I ) complexes were an e x c e p t i o n t o t h e Av(SO) v e r s u s v(M0) c o r r e l a t i o n p r o p o s e d above. C o n s i d e r i n g t h e r e l a t i v e l y s t r o n g TMSO->-Cr(III) bond,v (MO) =484 cm" 1, t h e former r e l a t i o n s h i p p r e d i c t s t h a t v (S0) of TMSO s h o u l d be l o w e r e d on c o m p l e x a t i o n t o about 900 cm 1 i n s t e a d o f t h e 932 cm 1 o b s e r v e d . However, F w r t and F. T t a k e i n t o MO OL acco u n t t h e l i g h t e r mass of Cr ( I I I ) asid improve t h e t r e n d ( f i g u r e 6.3). The e x c e l l e n t agreement ( f i g u r e 6.4) of t h e d a t a f o r t h e DMSO-d, —6 complexes, and l e s s w e l l - d e f i n e d DMSO d a t a from t a b l e s 6.2 and 6.3, w i t h t h e c o r r e l a t i o n o f f i g u r e 6.3 i s s u r p r i s i n g c o n s i d e r i n g t h e v a r i e t y o f complexes i n c l u d e d . The l e a s t s q u a r e s l i n e t o 95% c o n f i d e n c e f o r f i g u r e 6.4 i s F =-(1.24± i12)F M O+(8.78+.12). The c o r r e l a t i o n c o e f f i c i e n t i s r=0.95. Compounds w i t h v e r y weak and s t r o n g MO bonds ( i . e . , F ^ Q < 1 . 2 and >2.6 mdyne/A) a r e r a r e , and hence t h e number of d a t a p o i n t s d e c r e a s e s as t h e s e extremes a r e approached. Our f i n d i n g s c a s t doubt on r e c e n t v(MO) a s s i g n m e n t s f o r some 31 l a n t h a n i d e complexes M ( N 0 3 ) 3 ( D M S 0 ) n , where M=La,Nd,Yb,Lu, and n=3 o r 4. T h i s p a p e r a s s i g n e d bands n e a r 400 cm \ p r e v i o u s l y a s s i g n e d t o v(M0) ( t a b l e 6.3, r e f e r e n c e 3 2 ) , as 6(CSO) bands, and peaks near 200 c m - 1 t o v(MO), We f i n d t h a t t h e l a t t e r number g i v e s F v a l u e s n e a r 0.0, w i t h F v a l u e s t h a t f a l l f a r from t h e l i n e a r r e g i o n o f f i g u r e 6.4; t h e f o r m e r l y a s s i g n e d v a l u e s do f i t t h e . c o r r e l a t i o n . The 6(SO) v i b r a t i o n s a r e d i f f i c u l t t o l o c a t e ' ' , and i t i s p o s s i b l e t h a t t h e s e bands c o m p l i c a t e t h e s e l a n t h a n i d e systems by o v e r l a p p i n g w i t h v(M0) i n t h e 400 cm 1 r e g i o n . The supposed v(M0) a t 200 cm 1 must a l s o be q u e s t i o n e d on t h e grounds t h a t t h e y do not s h i f t on u s i n g DMSO-d^, w h i l e t h e 400 cm -1 -180-bands do. I n p r i n c i p l e , F _ v a l u e s s h o u l d be e s s e n t i a l l y t h e same f o r ML) DMSO and DMSO-d^ complexes, w h i l e t h e d a t a i n t a b l e 6.2 show t h a t F^Q v a l u e s f o r t h e d e u t e r a t e d complexes a r e c o n s i s t e n t l y l o w e r by o 0.05 t o 0.30 mdyne/A, p r o b a b l y because v( S 0 ) f o r t h e DMSO complexes a r e somewhat i l l - d e f i n e d and because t h e v i b r a t i o n s a r e n ot pure modes. S u l f o x i d e complexes o f some group IVA and VA elements do not f o l l o w t h e c o r r e l a t i o n o f f i g u r e 6.4 (see t a b l e 6.4, f i g u r e 6.5). The e q u a t i o n o f t h e l i n e drawn i n f i g u r e 6.5 i s FOL = - ( 1 - 0 2 ± ° - 3 4 ) F M O + (7.95±0.60), w i t h r = 0.83. E i t h e r t h e r e l a t i v e l y low v(M0) o f most o f t h e compounds t o g e t h e r w i t h h i g h i o n masses r e s u l t i n a low e s t i m a t i o n o f F o r , e q u a l l y l i k e l y , d i f f e r e n t b o n d i n g i n t e r a c t i o n s weaken S-0 more tha n f o r t h e t r a n s i t i o n m e t a l s y s t e m s . The o r d e r i n g o f t h e i o n s c o n s i d e r e d h e r e i s u n l i k e l y t o be a f f e c t e d by v a r i a t i o n o f th e b e n d i n g f o r c e c o n s t a n t F M Q L . By v a r y i n g F ^ from o 0.10 t o 0.60 mdyne A f o r a l l t h e compounds, F i n c r e a s e d by 1% w h i l e Ui-i 3 F^Q d e c r e a s e d by a p p r o x i m a t e l y 30%, i n agreement w i t h r e f e r e n c e . F M 0 L i s e x p e c t e d t o change i n a c o n t i n u o u s f a s h i o n as F ^ i n c r e a s e s , so t h a t t h e t r e n d s o b s e r v e d h e r e w i l l be p r e s e r v e d . -181-T a b l e 6.4. V i b r a t i o n a l d a t a f o r group IVA and VA Complexes COMPLEX v(SO) v(M0) F OL F MO Ref SbC£ 3(DMSO) 2 982,926,913 424,405 6.21 1.66 37 SbBr 3(DMSO) 979,897 405 6.21 1.57 37 BiC£ 3(DMSO) 2 980,908 411 6.25 1.74 37 B i B r 3 ( D M S O ) 2 977,908 408 6.24 1.71 37 BiC£ 3(DMSO) 3 984,930 403,394 6.47 1.61 37 B i B r 3 ( D M S O ) 3 979,929 404,394 6.42 1.61 37 [ B i P h 3 ( D M S O ) 2 ] 2 + 900 430 5.56 1.95 5 [ B i P h 3 ( D M S O - d 6 ) 2 ] 2 + 895 415 5.64 1.79 5 [ B i P h 3 ( D M S O ) 0 ] 2 + 940 405 6.20 1.66 5 [BiPh.(DMSO-d,)0] 2 + J —D Z 960 370 6.70 1.31 5 SnEt 2C£ 2(DMSO) 2 941 413,406 6.21 1.59 38 SnMe 2C£ 2(DMSO) 2 942 414 6.23 1.64 38 SnMe 2Br 2(DMSO) 2 942 430,419 6.20 1.75 38 [ S n P h 2 ( N 0 3 ) ( D M S O ) 3 ] + 950 410 6.36 1.60 23 SnPh 2C£ 2(DMSO) 2 947 420 6.29 1.70 38,39 S n M e 2 ( N 0 3 ) 2 ( D M S O ) 1 954 435 6.34 1.86 40 c i s - S n I 4 ( D M S O ) 2 928 459,451 5.89 2.09 38 c i s - S n B r 4 ( D M S O ) 2 911 471 5.59 2.30 38 cis-SnC£ 4(DMSO) 2 923,907 482,477 5.60 2.41 38 -183-7. C o n c l u s i o n s and Recommendations The p r i m a r y g o a l s of t h i s r e s e a r c h were t o s t u d y t h e c o o r d i n a t i o n c h e m i s t r y o f s u l f o x i d e s t o Rh and I r c e n t e r s and t o use t h i s knowledge t o d e s i g n homogeneous, p l a t i n u m m e t a l c a t a l y s t s f o r a symmetric s y n t h e s i s u s i n g c h i r a l s u l f o x i d e s as l i g a n d s . A summary o f t h e new i n f o r m a t i o n g a i n e d w h i l e p u r s u i n g t h e s e o b j e c t i v e s , and some i m p l i c a t i o n s , a r e d i s c u s s e d below. 7.1. C o o r d i n a t i o n C h e m i s t r y 7.1.1. P r e p a r a t i o n o f S u l f o x i d e Complexes o f Rhodium and I r i d i u m D i s p l a c e m e n t of t h e l a b i l e a c e t o n e l i g a n d from [ R h ( d i e n e ) ( P P h ^ ) -( a c e t o n e ) ] A ( d i e n e = l , 5 c y c l o o c t a d i e n e , n o r b o r n a d i e n e ; A=PF^ >SbFg ) a l l o w s f a c i l e c o o r d i n a t i o n of s u l f o x i d e s t h r o u g h the oxygen l o n e p a i r s , and [ R h ( d i e n e ) ( P P h ^ ) ( s u l f o x i d e ) ] + complexes have been c h a r a c t e r i z e d u s i n g DMSO, TMSO, NPSO, MBMSO, MPSO, R-MPTSO, and R-TBPTSO l i g a n d s . D i a r y l s u l f o x i d e s (DPSO, S-OTPTSO) and DIOS c o o r d i n a t e , but s o l i d s were not i s o l a t e d . The g e n e r a l r e a c t i v i t y of t h e p r e c u r s o r a c e t o n e complex was a l s o d e m o n s t r a t e d when o t h e r [ R h ( d i e n e ) ( P P h 3 ) L ] + complexes ( L = A s P h 3 , p y , ( C O ) 2 ) were s y n t h e s i z e d . Of t h e c a t i o n i c s p e c i e s [ R h ( d i e n e ) -( s u l f o x i d e ) 2 l + , o n l y t h e COD/DMSO s u b s t i t u t e d d e r i v a t i v e c o u l d be i s o l a t e d a l t h o u g h i n s i t u p r e p a r a t i o n o f o t h e r s i s p o s s i b l e . Aqueous i s o p r o p a n o l s o l u t i o n s o f RhCA^.SH^O on t r e a t m e n t w i t h many s u l f o x i d e s p r o v i d e an easy and e f f i c i e n t r o u t e t o RhCA^L^ complexes (L=DMSO,TMSO,MPSO, and R-MPTSO). N o r m a l l y two s u l f o x i d e s a r e s u l f u r -bonded and one i s oxygen-bonded; t h e c h l o r i d e s a r e a r r a n g e d m e r i d i a l l y around t h e Rh i n most c a s e s . No complexes showing s u l f u r b o n d i n g o f -184-t h e m o l e c u l e s R-TBPTSO o r S-OTPTSO c o u l d be i s o l a t e d ; p resumably t h e b u l k y groups around s u l f u r h i n d e r c o o r d i n a t i o n t o Rh; a s i m i l a r o b s e r v a t i o n was r e p o r t e d 1 f o r P t ( I I ) c e n t e r s . The oxygen-bonded s u l f o x i d e i n RhCA^L^ i s l a b i l e , and t h i s a l l o w s t h e g e n e r a t i o n i n s i t u , and i n some c a s e s t h e i s o l a t i o n , o f t h e complexes mer-RhC&g(DMSO)2(0=L) u s i n g amides, amine o x i d e s , and pho s p h i n e o x i d e s . The u t i l i t y o f RuCJ^(DMSO)^ as a s t a r t i n g m a t e r i a l f o r o t h e r R u ( I I ) 2 compounds has been d e m o n s t r a t e d ; t h e r e i s e q u a l l y p r o m i s e f o r RhC&^L^ complexes now t h a t a c o n v e n i e n t p r e p a r a t i o n has been d i s c o v e r e d . Some 3 R h ( I I I ) complexes o f N-donors have been made p r e v i o u s l y from RhCJl^ (DMSO), 4 i n c l u d i n g RhCil^ (py) 2 (DMSO) , an a n t i - t u m o r agent. D i p h e n y l s u l f o x i d e (DPSO) r e a c t s w i t h t h e rhodium t r i c h l o r i d e s o l u t i o n s t o g i v e R h ( I ) d i r e c t l y as t h e c h l o r i d e - b r i d g e d s p e c i e s [ R h C J K D P S O ^ ^ . v i a RhC£^(DPSO)^(isopropanol) i n t e r m e d i a t e s : RhC£ 3.3H 20 + 2L + ( C H ^ C H O H -> ^ [ R h C ^ ^ + ( C H ^ C O + 2HC£ (7.1) D i - n - p r o p y l s u l f o x i d e (NPSO) r e a c t s t o g i v e a c o r r e s p o n d i n g R h ( I ) dimer ( i n d i r e c t e v i d e n c e ) and a R h ( I I I ) p r o d u c t , i s o l a t e d as [ (NPSO) 2H] [RhC£^(NPSO)2!"containing a s y m m e t r i c a l l y h y d r o g e n - b r i d g e d c a t i o n [ ^S=0-H-0=S^ ] + . The complexes [H(DMSO) 2] [ I r C J i ^ D M S O ^ ] , ( [ H ( D M S O ) 2 ] + ) 2 [IrC£,]7 and trans-[H(DMSO)„][RhC£.(DMSO)„] must a l s o c o n t a i n t h i s c a t i o n . 0 z 4 z A c r y s t a l s t r u c t u r e o f t h e l a s t complex r e v e a l s t h e s h o r t oxygen-oxygen o d i s t a n c e (^2.45A) between t h e DMSO o f t h e c a t i o n t h a t i s e x p e c t e d f o r a s t r o n g H-bond. I n a d d i t i o n , v e r y l o n g Rh-S d i s t a n c e s a r e o b s e r v e d because o f t h e s t r o n g t r a n s i n f l u e n c e of t h e m u t u a l l y t r a n s DMSO l i g a n d s . -185-The ease o f a q u a t i o n o f t h i s a n i o n t o tra n s - [ R h C i ^ ( D M S O ) ( r ^ O ) ] r e f l e c t s t h e weakening o f t h e Rh-S bonds. The much m i l d e r c o n d i t i o n s r e q u i r e d f o r t h e p r e p a r a t i o n o f RhC£.jL.j u s i n g i s o p r o p a n o l r a t h e r t h a n water"* may r e s u l t from t h e p r e s e n c e o f t r a c e s o f R h ( I ) , g e n e r a t e d by r e a c t i o n 7.1, t h a t c o u l d c a t a l y z e t h e f o r m a t i o n o f RhCJc-^L^ i n a r e a c t i o n s i m i l a r t o one employed f o r t h e s y n t h e s i s o f R h ( I I I ) - p y r i d i n e c omplexes.^ The RhCJl^L^ complexes r e a c t s t o i c h i o m e t r i c a l l y w i t h H 2 ( l : l ) i n b a s e promoted r e a c t i o n s : - H + - + R h ( I I I ) + H 2 > [ H R h ( I I I ) ] > R h ( I ) + H (7.2) U s i n g P r o t o n Sponge (P.S.) as a ba s e , [P.S.H][RhC£ 2(DMSO)^] was p r e p a r e d by s u c h a r o u t e a l t h o u g h t h e r e were c o m p l i c a t i o n s due t o s i d e r e a c t i o n s , i n c l u d i n g a p o s s i b l e m e t a l l a t i o n o f t h e p r o t o n sponge a t t h e r i n g and/ or t h e N-methyl g r o u p s . The r h o d i u m ( I I I ) h y d r i d e i n t e r m e d i a t e s o f r e a c t i o n (7.2) have not been o b s e r v e d o r i s o l a t e d . The r h o d i u m ( I ) c y c l o o c t e n e p r e c u r s o r , [RhC£(C 0H 1,) 0]„, has been o 14 2. 2 used t o i s o l a t e a range o f complexes i n c l u d i n g [RhC£(C 0rL .)L]„,L=DPSO, o 14 z -TMSO, [RhC£(DMS0) 2] 2, [RhC£(DIOS) 2] 2, and [RhC£(MPSO)(PPh^)] . S u l f o x i d e s seem t o form t h e r m o d y n a m i c a l l y weak a d d u c t s w i t h R h ( I ) w i t h no a p p r e c i a b l e s t a b i l i z i n g i n t e r a c t i o n s s u c h as Rh(dir)-+S (d-rr) b a c k b o n d i n g . A c c o r d i n g l y s u l f o x i d e l i g a n d s appear u n a b l e t o c l e a v e Rh-C£-Rh b r i d g e s , and o n l y p a r t i a l l y d i s p l a c e c o o r d i n a t e d c y c l o o c t e n e , o r e t h y l e n e , e x c e p t when the s u l f o x i d e i s added i n g r e a t e x c e s s . The R h ( I ) complexes do n o t y i e l d i s o l a b l e d i h y d r i d e s p e c i e s t h r o u g h t h e o x i d a t i v e a d d i t i o n o f hydrogen. I n s t e a d , complexes of monodentate -186-s u l f o x i d e s , I n c l u d i n g t h e mixed s u l f o x i d e - t r i p h e n y l p h o s p h i n e c a t i o n s , a r e r e d u c e d t o rhodium m e t a l presumably v i a t r a n s i t o r y h y d r i d e compounds. Some R h ( I ) complexes o f t h e c h e l a t i n g s u l f o x i d e s , DIOS and MSE, a r e i n e r t t o hydrogen under c e r t a i n c o n d i t i o n s . F o r example, [ R h ( D I O S ) 2 ] + a p p e a r s t o be formed a l o n g w i t h [ R h ( H ) 2 ( P P h 3 ) 2 ( D M A ) 2 ] + i n a d i s p r o p o r -t i o n a t i o n r e a c t i o n o f [ R h ( N B D ) ( P P h ^ ) ( D I O S ) ] + i n DMA under H 2. A l s o [ R h ( M S E ) 0 ] P F , p r e c i p i t a t e s from m i x t u r e s o f [Rh(NBD)„]PF, and MSE ( r a t i o Z D Z D 1:2) i n 2-methoxyethanol under H,,. Other i n s i t u complexes g e n e r a t e d u s i n g [ R h ( N B D ) 2 ] P F 6 o r [RhC £ ( C g H ^ ) 2 ] 2 w i t h t h e p o t e n t i a l l y b i d e n t a t e l i g a n d s DIOS, MSE, PTSE, and MET, underwent H 2 r e d u c t i o n t o Rh m e t a l . H y d r i d e s were a l s o n o t o b s e r v e d i n the a t t e m p t e d o x i d a t i v e a d d i t i o n o f HC£ t o R h ( I ) complexes. I n t h e r e a c t i o n w i t h [RhC£(DMSO)^] , d i m e t h y l s u l f i d e was produced e i t h e r by d e c o m p o s i t i o n i n v o l v i n g a R h ( I I I ) - H i n t e r m e d i a t e o r v i a an a c i d - c a t a l y z e d DMSO d e c o m p o s i t i o n . The r e a c t i o n o f e x c e s s HC£ gas w i t h [IrC£(cyclooctene) 2] 2 i n DMSO r e s u l t s i n t h e f o r m a t i o n o f [H(DMSO)"J [ I r C J l ^ D M S O ) ^ . However, when HC£ i s added i n a s t o i c h i o m e t r i c amount (1:1) as t h e c r y s t a l l i n e DMA a d d u c t , t h e h y d r i d e complex, IrHC£ 2(DMSO)^, w i t h t r a n s c h l o r i d e s and m e r i d i n a l S-bonded DMSO can be i s o l a t e d . A h y d r i d o i r i d i u m complex w i t h t h e same s t r u c t u r e b u t w i t h d i f f e r e n t s p e c t r o s c o p i c p r o p e r t i e s was r e p o r t e d by Henbest e t al.7 We were u n a b l e t o r e p r o d u c e h i s p r e p a r a t i o n , and cannot e x p l a i n t h e d i f f e r e n c e s i n t h e s p e c t r a l d a t a . A c i s d i h y d r i d e compound w i t h mer S-bonded s u l f o x i d e s , f o r m u l a t e d as I r C ( D M S O ) 3 i s o b t a i n e d by t h e r e a c t i o n o f H 2 w i t h [ I r C U C g H ^ ) ^ i n DMSO. Henbest p r e p a r e d by a n o t h e r r o u t e 7 a d i f f e r e n t d i h y d r i d e isomer w i t h a p p a r e n t l y an 0-bonded DMSO t r a n s t o a h y d r i d e . The mono- and -187-d i h y d r i d e complexes p r e p a r e d i n t h e p r e s e n t s t u d i e s r e a c t w i t h CHCJl^ o r s t o i c h i o m e t r i c amounts o f HC£ t o y i e l d new i r i d i u m complexes con-t a i n i n g one l e s s c o o r d i n a t e d h y d r i d e l i g a n d : H 2IrC£ + HC£ HIrC£ 2 + H 2 H IrC£ + CHC£ + HIrC£ ? + CH C L > 'Ir=Ir(DMSO) HIrC£ 2 + CHC£ 3 •+ IrC£ 3 + C H 2 C £ 2 The r e a c t i o n o f HC£.DMA w i t h t h e d i h y d r i d e complex, f o r example, y i e l d s i n s i t u , what appears t o be IrC£ 2(H)(DMSO) 2(DMSO) w i t h c i s DMSO, c i s c h l o r i d e s , and DMSC) t r a n s t o t h e h y d r i d e . T h i s r e a c t i o n r e q u i r e s t h e f o r m a t i o n o f m o l e c u l a r H 2, but t h i s was n o t t e s t e d f o r . P r e l i m i n a r y a t t e m p t s t o i s o l a t e complexes from t h e r e a c t i o n of t h e c h i r a l s u l f o x i d e s R-MPTSO, R-TBPTSO, S-OTPSO, and PTSE w i t h IrC£ .3H 20 me t h a n o l o r 2 - p r o p a n o l were n o t s u c c e s s f u l . I t i s l i k e l y t h a t s u c h p r e p a r a t i o n s produce s e v e r a l s t a b l e i s o m e r i c complexes t h a t a r e d i f f i c u l t t o s e p a r a t e . A c l e a n e r r o u t e t o h y d r i d o complexes might i n v o l v e o x i d a t i v e a d d i t i o n r e a c t i o n s t o [IrC£(C 0H 1.)„]„ , a l t h o u g h t h e p r e s e n c e o f e x c e s s o 1 4 2 2 c h i r a l l i g a n d may be n e c e s s a r y t o d i s p l a c e t h e o l e f i n . A l l o f t h e p r e p a r a t i v e r o u t e s d e s c r i b e d i n t h i s s e c t i o n a r e a p p l i -c a b l e i n p r i n c i p l e t o o t h e r S-donors. An i n t e r e s t i n g a r e a t o p u r s u e would be t h e s y n t h e s i s o f d i a l k y l s u l f i d e complexes o f R h ( I ) and I r ( I ) ; t o d a t e none have been i s o l a t e d . C a t a l y t i c r e a c t i o n s o f i n s i t u R h ( I ) 8 complexes o f s u l f i d e s have been s t u d i e d and so t h e i s o l a t i o n o f compounds c o u l d f u r t h e r t h e u n d e r s t a n d i n g o f such c a t a l y s t s . -188-7.1.2. S p e c t r o s c o p i c P r o p e r t i e s o f t h e S u l f o x i d e Complexes B o t h i r and nmr s p e c t r o s c o p y y i e l d v a l u a b l e i n f o r m a t i o n on t h e s t r u c t u r e and b e h a v i o u r of t h e s e complexes i n s o l u t i o n , and more s p e c i f i c a l l y , on t h e n a t u r e of t h e s u l f o x i d e - m e t a l bonds. The i r f r e q u e n c y o f t h e S-0 s t r e t c h i n g mode unambiguously i n d i c a t e s t h e mode o f s u l f o x i d e - m e t a l b o n d i n g . F o r DMSO complexes t h i s peak a l w a y s f a l l s i n t h e range o f 1200-1055 cm 1 f o r S-bonding, and 1000--1 f 860 cm f o r 0 b o n d i n g , whether t h e sample i s i n s o l u t i o n o r t h e s o l i d s t a t e . The a c t u a l assignment o f v(S0) can be e q u i v o c a l f o r t h e c a s e o f 0-bonding i f t h i s f r e q u e n c y l i e s n e ar t o an i n t e n s e m e t h y l r o c k i n g mode o f t h e s u l f o x i d e w h i c h i s s i t u a t e d n ear 980±20 cm t h e s y n t h e s i s o f complexes w i t h o u t bands t h a t c o m p l i c a t e t h e v(S0) r e g i o n e.g. [ R h ( d i e n e ) ( P P h . ) L ] + , L=DMS0-d, and TMSO, and [ Rh (COD) (DMSO-d,) J + , J o o Z a l l o w e d t h e l o c a t i o n o f v ( S 0 ) a t 950 cm f o r t h e DMSO a n a l o g u e s and t h e a s s i g n m e n t o f v (RhO) a t -450 cm Crude a p p r o x i m a t i o n s f o r t h e c a l c u l a t i o n s o f f o r c e c o n s t a n t s f o r M-<-0=L systems i n t h e c a s e o f s u l -f o x i d e complexes have been shown t o l e a d t o a u s e f u l c o r r e l a t i o n between t h e f o r c e c o n s t a n t s F and F ^ Q J and t h e o b s e r v e d d i r e c t p r o p o r t i o n a l i t y may be used t o v e r i f y v(S0) and v(M0) a s s i g n m e n t s . A wide range of complexes had t o be c o n s i d e r e d t o expose t h e p r o p o r t i o n a l i t y ; some more l i m i t e d s t u d i e s had found l i t t l e s i g n i f i c a n c e i n changes i n v ( S 0 ) on 9 c o o r d i n a t i o n t o m e t a l c e n t e r s . I t might be p r o f i t a b l e t o a n a l y z e c o r r e s p o n d i n g d a t a f o r s e r i e s o f compounds w i t h p h o s p h i n e - , a r s i n e - , and p y r i d i n e - o x i d e l i g a n d s . -189-The TMSO and DMSO-d^ l i g a n d s have p r o v e d u s e f u l f o r p r o b i n g t h e s t r e n g t h o f M-0 i n t e r a c t i o n s . The 0-bonding o f s u l f o x i d e s t o t h e u n h i n d e r e d [ R h ( C O D ) ] + m o i e t y s u g g e s t s t h a t t h i s R h ( I ) c e n t e r i s " h a r d " i n t h e HSAB c l a s s i f i c a t i o n scheme. A s t u d y o f i r d a t a f o r a range o f s u l f u r - b o n d e d DMSO a d d u c t s i n d i c a t e s t h a t s i n c e v(SO) s h i f t s t o h i g h e r f r e q u e n c y on c o o r d i n a t i o n t o " h a r d e r " m e t a l s i n t h e absence o f m e t a l diT->SdiT b a c k b o n d i n g , t h e s u l f u r o f a s u l f o x i d e i s a r e l a t i v e l y " h a r d " donor atom. C r y s t a l s t r u c t u r e and i r d a t a p r o v i d e no e v i d e n c e f o r b a c k b o n d i n g i n t h e case of rhodium complexes, and t h e r e f o r e t h e f i n d i n g t h a t t h e S-0 bond a b s o r b s a t 30-40 c m - 1 h i g h e r f o r Rh(III)-DMS0 t h a n Rh(I)-DMS0 i s c o n s i s t e n t w i t h f o r m e r h a v i n g a s t r o n g e r h a r d - h a r d i n t e r a c t i o n . An i n c r e a s e i n t h e f o r m a l p o s i t i v e c h a r g e on Rh(III)-DMS0 complexes was a l s o shown t o i n c r e a s e t h e energy o f v ( S 0 ) , as e x p e c t e d . The complexes c o n t a i n i n g t h e [R2S0-H-0SR2] + c a t i o n have b r o a d , i n t e n s e a b s o r p t i o n bands i n t h e i r a t 1 6 0 0 - i l O O and 900-600 cm t h a t a r e thought t o be due t o t h e v (0-H-0) mode of s y m m e t r i c a l l y b r i d g i n g a h y d r o g e n bonds. D i f f e r e n c e s between t h e s e s p e c t r a l f e a t u r e s and t h o s e of o t h e r H-bond b r i d g e d systems have been e x p l a i n e d i n terms o f F e r m i r e s o n a n c e e f f e c t s ; t h e n a t u r e o f t h e s e e f f e c t s has been d i s c u s s e d by o t h e r s . The nmr c h e m i c a l s h i f t s o f p r o t o n s a t o t h e SO group g i v e i n f o r m a t i o n about t h e mode of b o n d i n g o f t h e s u l f o x i d e . Oxygen—bonded DMSO i n t h e complexes [Rh(COD) (DMSO) 2 ] + , RhC£^ (DMSO) ^  (DMSJ3) , and IrC£„(DMSO)_(DMSO) 7 r e s o n a t e a t 52.80, 2.86, and 2.92, r e s p e c t i v e l y , -190-whereas t h e S bonded l i g a n d s o f R h ( I I I ) , I r ( I I I ) f a l l i n t h e range 63.7-3.4. The l a b i l e Rh(I)-DMS0 l i g a n d s r e s o n a t e a t 62.8, a w e i g h t e d mean p o s i t i o n o f t h e f r e e and c o o r d i n a t e d l i g a n d , and a low t e m p e r a t u r e nmr s t u d y i s r e q u i r e d t o l o c a t e t h e v a l u e f o r c o o r d i n a t e d DMSO. The u p f i e l d s h i f t s o f t h e s u l f o x i d e r e s o n a n c e s f o r t h e complexes [ R h ( d i e n e ) -( P P h ^ ) ( s u l f o x i d e ) ] + where 0-bonding o c c u r s , r e f l e c t s h i e l d i n g by t h e a d j a c e n t p h e n y l groups o f PPh^. S i m i l a r s h i e l d i n g e f f e c t s by t h e ph o s p h i n e o x i d e s OPPl^Me and OPPhMe^ were e x p l o i t e d t o a s s i g n t h e mer c o n f i g u r a t i o n t o t h e RhCJ"^(DMSO)^(0=L) complexes. T h i s t e c h n i q u e i s g e n e r a l l y a p p l i c a b l e t o systems o f unknown s t e r e o c h e m i s t r y t h a t c o n t a i n a l a b i l e 0-donor l i g a n d , f o r example RuCJl,,(DMSO)^(DMSO). The m a g n e t i c i n e q u i v a l e n c e o f t h e m e t h y l groups o f t h e DMSO i n c e r t a i n complexes a l s o a i d s i n s t e r e o c h e m i c a l d e t e r m i n a t i o n s . The i n e q u i v a l e n c e i n t h e nmr s p e c t r a o f t h e o l e f i n i c p r o t o n s i n 1 2 + 1 2 [ R h ( d i e n e ) L L ] com p l e x e s , where L and L a r e d i f f e r e n t monodentate l i g a n d s , p r o v e d e x t r e m e l y u s e f u l i n s t u d y i n g t h e s o l u t i o n b e h a v i o u r o f t h e s e complexes. E v i d e n c e f o r t h e e x i s t e n c e o f t h e d i s p r o p o r t i o n a t i o n r e a c t i o n 7.3, as w e l l as f o r 3 - c o o r d i n a t e T-shaped COD i n t e r m e d i a t e s and 3- and 5 - c o o r d i n a t e NBD i n t e r m e d i a t e s , was p r o v i d e d by s t u d y i n g t h e nmr b e h a v i o u r o f t h e d i e n e p r o t o n s . (7.3) -191-7.2. A t t e m p t s a t t h e C a t a l y t i c Asymmetric H y d r o g e n a t i o n o f P r o c h i r a l  O l e f i n s and Ketones Only a few o f t h e rhodium complexes p r e p a r e d i n t h i s t h e s i s c a t a l y t i c a l l y h y d r o g e n a t e d p r o c h i r a l o l e f i n s - u s u a l l y i t a c o n i c a c i d -and i n no c a s e was t h e r e d e t e c t a b l e i n d u c e d asymmetry i n t h e p r o d u c t s . The complexes [ R h ( d i e n e ) ( P P h 3 ) ( L ) ] + , L=acetone, DMSO, R-MPTSO, diene= COD, NBD, h y d r o g e n a t e i t a c o n i c a c i d r a p i d l y a t 30°C i n a c e t o n e or'MeOH, b u t t h e d i h y d r i d o - o l e f i n i n t e r m e d i a t e i n t h e p r o c e s s i s thought t o be [R h ( d i e n e ) (PPh^) (IA) (H) 2]"*" where a c h i r a l s u l f o x i d e i s not c o o r d i n a t e d and t h u s cannot l i k e l y cause any e n a n t i o m e r i c e x c e s s (e.e.) i n t h e hy d r o g e n a t e d p r o d u c t . A g a i n i t a c o n i c a c i d i s h y d r o g e n a t e d u s i n g [ R h ( N B D ) ( P P h 3 ) ( a c e t o n e ) ] + and DIOS i n a mo l a r r a t i o o f 1:1 i n DMA. The a c t i v e c a t a l y s t i s l i k e l y t o be [ R h ( H ) 2 ( P P h 3 ) 2 ( D M A ) ^ i n t h i s c a s e as no e.e. was d e t e c t e d i n t h e a-methyl s u c c i n i c a c i d p r o d u c t . I n t h e s e c a s e s , t h e l a b i l i t y o f t h e s u l f o x i d e s c o o r d i n a t e d t o a R h ( I ) c e n t e r a l l o w s u n f a v o u r a b l e l i g a n d r e d i s t r i b u t i o n r e a c t i o n s t o o c c u r . Of t h e c h l o r o - s u l f o x i d e Rh complexes, o n l y t h o s e p r e p a r e d from [RhC£ (CQH.. .) „] and DIOS i n a m o l a r r a t i o o f 1:2 o r g r e a t e r , u s i n g o 14 2 2 a l c o h o l s o r DMA as t h e s o l v e n t , h y d r o g e n a t e d i t a c o n i c a c i d a t a r e a -s o n a b l e r a t e but even t h e s e r a p i d l y d e a c t i v a t e d b e f o r e 20% c o n v e r s i o n ; t h e r e a s o n f o r t h e r a p i d d e c r e a s e i n a c t i v i t y i s thought t o be a r e d u c t i o n of t h e s u l f o x i d e t o s u l f i d e . F o r example an i n s i t u complex o f RhCJ^.S^O i n MBMSO s e l e c t i v e l y r e d u c e d t h e s u l f o x i d e i n s t e a d o f i t a c o n i c a c i d t h a t was a l s o p r e s e n t . Thus r e d o x p r o c e s s e s a t t h e c o o r d i n a t e d s u l f o x i d e p r e s e n t problems i n d e s i g n i n g an asymmetric c a t a l y t u s i n g such l i g a n d s . -192-R e d u c t i o n of t h e s u l f o x i d e a l s o appears t o o c c u r i n t h e t r a n s f e r h y d r o g e n a t i o n from i s o p r o p a n o l t o 3-methyl-3-penten-2-one, and t o 2-o c t a n o n e , c a t a l y z e d by i n s i t u c a t a l y s t s g e n e r a t e d by h e a t i n g I r C J ^ - ^ I ^ O and TBPTSO t o g e t h e r i n a m o l a r r a t i o o f 1:3. I n t h e s e c a s e s , an i r i d i u m complex w i t h presumably c o o r d i n a t e d s u l f i d e l i g a n d s p r e c i p i t a t e s , and t h i s d e s t r u c t i o n o f t h e c h i r a l l i g a n d would e x p l a i n t h e l a c k of e.e. i n t h e p r o d u c t s w h i c h were 3-methyl pentan-2-one and 2 - o c t a n o l , r e s p e c t i v e l y . These s t u d i e s s u g g e s t t h a t i t i s t h e weak b o n d i n g of s u l f o x i d e s t o R h ( I ) , and t h e s u s c e p t i b i l i t y o f c o o r d i n a t e d s u l f o x i d e s t o be r e d u c e d by R h ( I I I ) - and I r ( I I I ) - h y d r i d e s t h a t l i m i t t h e i r u s e f u l n e s s as h y d r o g e n a t i o n and asymmetric h y d r o g e n a t i o n c a t a l y s t s . The f i r s t l i m i t a t i o n c o u l d be remedied perhaps by u s i n g c h e l a t i n g s u l f o x i d e s w i t h s t r o n g l y e l e c t r o n d o n a t i n g g r o u p s . The second l i m i t a t i o n i s a more s e r i o u s one. 7.3. Other C a t a l y t i c R e a c t i o n s The complex [Rh(NBD)(PPh„)(CO)„]PF, i s a p r e c u r s o r t o a h y d r o -J Z D f o r m y l a t i o n c a t a l y s t t h a t o p e r a t e s i n DMA under m i l d c o n d i t i o n s - a t 50° and 1 atm (CO+I^). B o t h 1-hexene and 1-heptene s u b s t r a t e s a r e c o n v e r t e d t o a 72/28 m i x t u r e of l i n e a r / b r a n c h e d a l d e h y d e p r o d u c t s . The g r e a t e r e f f i c i e n c y and s e l e c t i v i t y o f t h i s c a t a l y s t s ystem compared t o a n a l o g o u s n e u t r a l rhodium c a r b o n y l compounds may r e s u l t from t h e p r e s e n c e of c a t i o n i c a c t i v e s p e c i e s , and f u r t h e r s t u d y of t h e u n e x p l o r e d a r e a o f c a t i o n i c rhodium h y d r o f o r m y l a t i o n c a t a l y s t s c o u l d be p r o f i t a b l e . The u n u s u a l s e l e c t i v e h y d r o g e n a t i o n o f a, (3-unsaturated a l d e h y d e s t o t h e u n s a t u r a t e d a l c o h o l s has been a c c o m p l i s h e d c a t a l y t i c a l l y under m i l d c o n d i t i o n s u s i n g t h e i r i d i u m complex IrHC£„(DMSO)- i n p r o p a n - 2 - o l , -193-th e s o l v e n t b e i n g t h e s o u r c e of hydrogen. T r a n s i t i o n m e t a l p h o s p h i n e complexes n o r m a l l y h y d r o g e n a t e t h e o l e f i n i c bond and so s u l f o x i d e s l i g a n d s must a l t e r t h e r e a c t i v i t y o f i r i d i u m h y d r i d e s , p o s s i b l y by r e n d e r i n g t h e c o o r d i n a t e d hydrogen more a c i d i c . F u r t h e r s t u d i e s on t h e use o f s u l f u r - d o n o r l i g a n d s i n homogeneous c a t a l y s i s might b r i n g t o l i g h t o t h e r examples of s e l e c t i v e r e a c t i o n s t h a t a r e not c a t a l y z e d by t h e f a m i l i a r w e l l - s t u d i e d p h o s p h i n e based systems. -194-R e f e r e n c e s f o r C h a p t e r 1 C. L. Dodgson, "Through t h e L o o k i n g G l a s s and What A l i c e Found T h e r e " , Mount Vernon, N.Y. ( 1 9 6 0 ) . S. H. W i l e n , Top. Stereochem. 107 (1971). B. R. James, Adv. Organomet. Chem. 1 7 , i n t h e p r e s s . J . D. M o r r i s o n and H. S. Mosher, "Asymmetric O r g a n i c R e a c t i o n s " , Am. Chem. S o c , W a s h i n g t o n , D.C. ( 1 9 7 6 ) . P. P i n o , G. C o n s i g i l i o , C. B o t t e g h i , and C. Salomon, Adv. Chem. S e r . 132, 295 ( 1 9 7 4 ) . I . O j i m a , K. Yamamoto, and M. Kumada, " A s p e c t s o f Homogeneous C a t a l y s i s " , (R. Ugo e d . ) , p.186, R e i d e l , D o r d r e c h t ( 1 9 7 7 ) . W. S. K nowles, M. J . Sabacky, and B. D. V i n e y a r d , Adv. Chem. S e r . 132, 274 ( 1 9 7 4 ) . B. D. V i n e y a r d , W. S. Knowles, M. J . Sabacky, G. L. Backman, and D. J . W e i n k a u f f , J . Am. Chem. Soc. 99, 5946 (1977). M. D. F r y z u k and B. B o s n i c h , J . Am. Chem. Soc. 99, 6262 (1977). R. G l a z e r , M. Twaik, S. G e r e s h , and J . B l u m e n f e l d , T e t . L e t t . ( 1 9 7 8 ) , i n p r e s s . T. H a y a s h i , T. M i s e , S. M i t a c h i , K. Yamamoto, and M. Kumada, T e t . L e t t . 1133 ( 1 9 7 6 ) . W. R. C u l l e n and E.-S. Yeh, J . Organomet. Chem. 139, C13 (1977). T. P. Dang, J-C. P o u l i n , and H. B. Kagan, J . Organomet. Chem. 91, 105 ( 1 9 7 5 ) . B. R. James and D. Mahajan, u n p u b l i s h e d r e s u l t s . B. R. James, "Homogeneous H y d r o g e n a t i o n " , John W i l e y and Sons, New Y o r k (1973). J . D. M o r r i s o n , W. F. M a s l e r , and M. K. Neuberg, Adv. C a t . Z5, 81 (1976). -195-C h a p t e r 1 B. B o g d a n o v i c , B. Hene, A. L o s l e r , B. M e i s t e r , H. P a u l i n g , and G. W i l k e , Angew. Chem. I n t . Ed. 12, 954 (1973). E. Bayer and V. S c h u r i g , Chem. Tech.. 212 (1976). F. R. H a r t l e y and P. N. Vezey, Adv. Organomet. Chem. 15, Academic P r e s s , N.Y. (1977). C. U. P i t t m a n , J r . , and A. H i r a o , J . Org. Chem. 43, 640 (1978). Y. O r i t o , S. Niwa, and S. I m a i , Chem. L e t t . 1131 (1977). N. I z u m i y a , S. Lee, T. Kanmera, and H. A o y a g i , J . Am. Chem. Soc. 99, 8346 (1977). F. J . M c Q u i l l i n , "Homogeneous H y d r o g e n a t i o n i n O r g a n i c C h e m i s t r y " , R e i d e l , D o r d r e c h t ( 1 9 7 6 ) . Y. O h a s h i and Y. Sasada, B u l l . Chem. Soc. J p n . _50, 2863 (1977) and r e f e r e n c e s t h e r e i n . R. W. Waldron and J . H. Weber, I n o r g . Chem. 16, 1220 (1977). T. H a y a s h i , K. Yamamoto, and M. Kumada, J . Organomet. Chem. 112, 253 (1976). Y. Ohgo, S. T a k e u c h i , Y. N a t o r i , and J . Y o s h i m u r a , Chem. L e t t . 1327 (1974) . G. Sbrana, G. B r a c a , and E. G i a n n e t t i , J . Chem. Soc. D a l t o n T r a n s . . 1847 (1976). B. R. James and R. S. M c M i l l a n , Can. J . Chem. 55, 3927 (1977). B. R. James, R. S. M c M i l l a n , R. H. M o r r i s , and D. K. W. Wang, Adv. Chem. S e r . 167, 122 (1978). R. S. M c M i l l a n , Ph.D. D i s s e r t a t i o n , U n i v e r s i t y o f B r i t i s h C o l u m b i a , ( 1 9 7 6 ) . C. A. M a r y a n o f f , B. E. M a r y a n o f f , R. Tang, and K. M i s l o w , J . Am. Chem. Soc. 95, 5839 (1973). -196-C h a p t e r 1 33. G. N a t i l e , E. B o r d i g n o n , and L. C a t t a l i n i , I n o r g . Chem. 15, 246 (197 6 ) . 34. M. A x e l r o d , P. B i c k a r t , M. M. Green, and K. M i s l o w , J . Am. Chem. Soc. 90, 4835 (1968). 35. Y. N. K u k u s h k i n , N. D. R u b t s o v a , and M. M. S i n g h , Russ. J . I n o r g . Chem. 15, 965 (1970). 36. D. N. Lawson and G. W i l k i n s o n , J . Chem. Soc. 1900 (1965). 37. M. Green and T. A. Kuc, J . Chem. Soc. D a l t o n T r a n s . 832 (1972). 38. C. A. Reed and W. R. Roper, J . Chem. Soc. D a l t o n T r a n s . 1365 (1973). 39. S. A. Johnson, H. R. Hunt, and H. M. Neumann, I n o r g . Chem. 2_, 960 (1963). 40. T. A. M a l ' k o v a and V. N. S h a f r a n s k i i , Zh. Obshch. Khim. 47, 2592 (1977). 41. E. F. S t r i z h e v , K. A. Khokhryakov, Y. N. K u k u s h k i n , and A. V. G o r d i e v s k i i , Russ. J . I n o r g . Chem. 20_, 1685 (1975). 42. V. I . S o k o l and M. A. P o r a i - K o s h i t s , K o o r d . Khim. 1, 577 (1975). 43. I . P. Evans, A. Spencer, and G. W i l k i n s o n , J . Chem. Soc. D a l t o n T r a n s . 204 (1973) . 44. V. I . S o k o l , N. D. R u b t s o v a , and A. Y. G r i b e n y u k , Z h . S t r u k t . Chim. 15, 318 (1974). 45. P. C o l a m a r i n o and P. O r i o l i , J . Chem. Soc. D a l t o n T r a n s . 845 (1976). 46. Y. N. K u k u s h k i n and N. D. R u b t s o v a , Russ. J . I n o r g . Chem. 14, 980 (1969). 47. Y. N. K u k u s h k i n , N. D. R u b t s o v a , and N. V. I v a n n i k o v a , Russ. J . I n o r g . Chem. 15, 1032 (1970). 48. H. B. Henbest and J . Trocha-Grimshaw, J . Chem. Soc. P e r k i n I . 607 (1974). -197-C h a p t e r 1 C. W h i t e , S. J . Thompson, and P. M. M a i t l i s , J . Chem. Soc. D a l t o n T r a n s . 1654 (1977). Y. M. Y. Haddad, H. B. Henbest, and J . Trocha-Grimshaw, J . Chem. Soc. P e r k i n I , 592 (1974). P. G. Antonov, Y. N. K u k u s h k i n , V. F. Shkredov, L. V. K o n o v a l o v , B. I . I o n i n , Koord. Khim. _3> 907 (1977). M. M. T a q u i Khan and A. E. M a r t e l l , "Homogeneous C a t a l y s i s by M e t a l Complexes", _1, 1, Acad. P r e s s , New Y o r k (1974). R. R. S c h r o c k and J . A. Osborn, J . Am. Chem. Soc. 9_8, 2134, 2143, 4450 (1 9 7 6 ) , and r e f e r e n c e s t h e r e i n . J . Trocha-Grimshaw and H. B. Henbest, J . Chem. Soc. Chem. Commun. 757 ( 1 9 6 8 ) . J . H a l p e r n , A c c . Chem. Res. _3> 386 (1970). J . H a l p e r n , T. Okamoto, and A. Z a k h a r i e v , J . M o l . C a t a l . 2_, 65 (1977). Y. O h t a n i , M. F u j i m o t o , a n d A. Y a m a g i s h i , B u l l . Chem. Soc. J p n . 50, 1453 (1977). C. A. Tolman, P. Z. M e a k i n , D. L. L i n d n e r , and J . P. J e s s o n , J . Am. Chem. Soc. 96, 2762 (1974). Y. D e m o r t i e r and I . de A g u i r r e , B u l l . Soc. Chim. F r a n c e , 1614, 1619 (19 7 4 ) . R. H. C r a b t r e e , H. F e l k i n , T. Khan and G. E. M o r r i s , J . Organomet. Chem. 144, C15 (1978). J . H a l p e r n , D. P. R i l e y , A. S. C. Chan, and J . J . P l u t h , J . Am. Chem. Soc. 99, 8055 (1977). J . H a l p e r n , C.I.C./A.C.S. M e e t i n g , M o n t r e a l , May 29 (1 9 7 7 ) . C. A. Tolman, Chem. Rev. 77^, 335 (1977). -198-C h a p t e r 1 64. R. B. A n d e r s o n , " C a t a l y s i s " 4_, 242 (P.H. Emmett, ed.) R e i n h o l d , New Y o r k (1956). 65. H. B. Henbest and J . Trocha-Grimshaw, J . Chem. Soc. P e r k i n I , 601 (1974). 66. Y. M. Y. Haddad, H. B. Henbest, J . Husbands, T. R. B. M i t c h e l l , and J . Trocha-Grimshaw, J . Chem. Soc. P e r k i n I , 596 (1974). 67. L. K. F r e i d l i n , Y. A. K o p y t t s e v , N. M. N a z a r o v a and T. I . V a r a v a , I z v . Akad. Nauk. S.S.S.R. Ser Khim. 1325 (1974). 68. Y. A. K o p y t t s e v , L. K. F r e i d l i n , N. M. N a z a r o v a , and I . P. Y a k e v l e v , i b i d , 997 (1975). 69. B. F. G. Johnson and R. A. W a l t o n , S p e c t r o c h i m . A c t a J22, 1853 (1966). 70. B. R. James, F. T. T. Ng and G. L. Rempel, Can. J . Chem. 47, 4521 (1969). 71. F. T. T. Ng, Ph.D. D i s s e r t a t i o n , U n i v e r s i t y o f B r i t i s h C o l u m b i a , ( 1 9 7 0 ) . 72. B. R. James and F. T. T. Ng, J . Chem. Soc. D a l t o n T r a n s . 355 (1972). 73. L. K. F r e i d l i n , Y. A. K o p y t t s e v , N. M. N a z a r o v a , B. L. Lebedev and B. L. K h u s i d , I z v . Akad. Nauk. S.S.S.R. S e r . Khim., 1325 (1974). 74. H. A d k i n s , R. M. E l o f s o n , A. G. Rossow, and C. C. R o b i n s o n , J . Am. Chem. Soc. 71, 3622 (1949). 75. H. B. Henbest and T. R. B. M i t c h e l l , J . Chem. Soc. ( C ) , 785 (1970). 76. Y. Sasson and J . Blum, J . Org. Chem. _40, 1887 (1975). 77. G. D e s c o t e s and D. S i n o u , T e t . L e t t . 4083 (1976). 78. H. Boucher and B. B o s n i c h , J . Am. Chem. Soc. 99_, 6253 (1977). 79. R. G. B a l l and N. C. Payne, I n o r g . Chem. 16, 1871 (1977). -199-C h a p t e r 1 80. R. G. B a l l and N. C. Payne, I n o r g . Chem. 15, 2494 (1976). 81. H. Boucher and B. B o s n i c h , I n o r g . Chem. 1_6, 717 (1977). 82. R. G. B a l l and N. C. Payne, I n o r g . Chem. 16, 1187 (1977). 83. J . M. Brown and P. A. C h a l o n e r , J . Chem. Soc. Chem. Commun. 321 (1978). 84. J . H a l p e r n , p e r s o n a l communication. 85. R. G. P e a r s o n , J . Am. Chem. Soc. 85, 3533 (1963). 86. W. L. R e y n o l d s , P r o g . I n o r g . Chem. 12, 1 (1970). 87. J . J . M a c D o u g a l l , J . H. N e l s o n , M. W. B a b i c h , C. C. F u l l e r , and R. A. J a c o b s o n , I n o r g . Chim. A c t a Z7_, 201 (1978) and r e f e r e n c e s t h e r e i n . 88. C-C. Su and J . W. F a l l e r , I n o r g . Chem. L3, 1734 (1974). 89. H. Taube, from l e c t u r e a t U. of B r i t i s h C o l u m b i a (1978). 90. W. S t r o h m e i e r and J . F. G u t t e n b e r g e r , Chem. B e r . 97_, 1871 (1964). 91. E. M. A r n e t t , E. J . M i t c h e l l and T. S. S. R. M u r t y , J . Am. Chem. Soc. 9_6, 3875 (1974). 92. A. H. M. F l e u r and W. L. G r o e n v e l d , Rec. T r a v . Chim. 91, 317 (1972) and r e f e r e n c e s t h e r e i n . 93. C. R. P i r i z M a c - C o l l and L. B e y e r , I n o r g . Chem. 12, 7 (1973). 94. J . H. P r i c e , A. N. W i l l i a m s o n , R. F. Schramm, and B. B. Wayland, I n o r g . Chem. 11, 1280 (1972). 95. Y. N. K u k u s h k i n , I n o r g . Chim. A c t a 9, 117 (1974). 96. T. G. A p p l e t o n , H. C. C l a r k , and L, E. Manzer, Coor. Chem. Rev. 10, 335 (1973). 97. R. S. M c M i l l a n , A. M e r c e r , B. R. James, and J . T r o t t e r , J . Chem. Soc. D a l t o n T r a n s . 1006 (1975). -200-C h a p t e r 1 98. M. J . B e n n e t t , F. A. C o t t o n , D. L. Weaver, R. J . W i l l i a m s , and G. H. Watson, A c t a C r y s t . 23, 788 (1967). 99. D. A. Langs, C. R. Hare, and R. G. L i t t l e , J . Chem. Soc. Chem. Commun. 1080 (1967). 100. F. C. March and G. F e r g u s o n , Can. J . Chem. 49, 3585, 3590 (1971). 101. A. M e r c e r and J. T r o t t e r , J . Chem. Soc. D a l t o n T r a n s . 2480 (1975). 102. M. M c P a r t l i n and R. Mason, J . Chem. Soc. ( A ) , 2206 (1970). 103. D. R. Rayner, E. G. M i l l e r , P. B i c k a r t , A. J . Gordon, and K. M i s l o w , J . Am. Chem. Soc. 88, 3138 (1966). 104. C. J . L. L o c k , R. A. S p e r a n z i n i , and J . P o w e l l , Can. J. Chem. 54, 53 (1976). 105. R. Me l a n s o n , J . H u b e r t , and F. D. Rochon, A c t a C r y s t . B32, 1914 (1976). 106. R. M e l a n s o n , F. D. Rochon, Can. J . Chem. 53., 2371 (1975). -201-R e f e r e n c e s f o r Ch a p t e r 2 1. A v a n d e r Ent and A. L. O n d e r d e l i n d e n , I n o r g . S y n t h e s e s 14, 92 (1973 ) . 2. R. Cramer, I n o r g . Chem. 1, 722 (1962). 3. J . C h a t t and L. M. V e n a n z i , J . Chem. Soc. 4735 ( 1 9 5 7 ) . 4. J . A. M c C l e v e r t y and G. W i l k i n s o n , I n o r g . S y n t h e s e s 8^ , 211 (1966). 5. E. W. A b e l , M. A. B e n n e t t , and G. W i l k i n s o n , J . Chem. Soc. 3178 (1959). 6. R. R. Shrock and J . A. Osborn, J . Am. Chem. Soc. 93, 2397 (1971). 7. R. R. S h r o c k and J . A. Osborn, J . Am. Chem. Soc. 93, 3089 (1971). 8. R. S. M c M i l l a n , Ph.D. D i s s e r t a t i o n , U n i v e r s i t y o f B r i t i s h Columbia (1976). 9. M. A x e l r o d , P. B i c k a r t , M. M. Green, and K. M i s l o w , J . Am. Chem. Soc. 90, 4835 ( 1 9 6 8 ) . 10. B. R. James, R. S. M c M i l l a n , R. H. M o r r i s , and D. K. W. Wang, Adv. Chem. S e r . 167, 122 (1978). 11. H. Boucher and B. B o s n i c h , I n o r g . Chem. 1_6, 717 (1977). 12. D. N. Harpp, S. M. V i n e s , J . P. M o n t i l l e s , and T. H. Chan, J . Org. Chem. 41, 3987 (1976). 13. C. A. M a r y a n o f f , B. E. M a r y a n o f f , R. Tang, and K. M i s l o w , J . Am. Chem. Soc. 95, 5839 (1973). 14. N. K u n i e d a , J . Nokami, and M. K i n o s h i t a , B u l l . Chem. Soc. J p n . 49, 256 (1976). 15. The N.M.R. method o f R. J o n e s , J . Organomet. Chem. 18, 15 ( 1 9 6 9 ) , was used t o s t a n d a r d i z e t h e n - b u t y l l i t h i u m . A known volume of benzene was used as t h e s t a n d a r d . -202-C h a p t e r 2 16. A. R. P r a y , I n o r g . S y n t h e s e s 5_, 153 (1957). 17. M. C i n q u i n i and S. C o l o n n a , I n t . J . S u l f u r Chem. 8_, 603 (1976). 18. H. Nieuwenhyse and R. Louw, J . Chem. Soc. P e r k i n I , 839 (1973). 19. C. M. H u l l and T. W. B a r g a r , J . Org. Chem. 40, 3152 (1975). 20. E. V. B e l l and G. M. B e n n e t t , J . Chem. Soc. . 1798 (1927). 21. T. S v i n n i n g , F. Mo and T. Bruun, A c t a Cryst.. B32, 759 (1976). 22. R. Louw and H. Nieuwenhyse, Chem. Commun. 1561 (1968). 23. G. N a t i l e , E. B o r d i g n o n , and L. C a t t a l i n i , I n o r g . Chem. 15, 246 (197 6 ) . -203-R e f e r e n c e s f o r Chap t e r 3 1. R. R. S c h r o c k and J . A. Osborn, J . Am. Chem. Soc. 98, 2134, 2143, 4450 ( 1 9 7 6 ) , and r e f e r e n c e s t h e r e i n . 2. K. J . Reimer d i s c o v e r e d t h e f i r s t o f t h e s e complexes w i t h diene=C0D, L 1=PPh„, A=PF~. 3 D 3. R. H. C r a b t r e e , J . Chem. Soc. Chem. Commun. 647 (1975). 4. R. H. C r a b t r e e , and G. E. M o r r i s , J . Organomet. Chem. 135, 395 (1977). 5. R. H. C r a b t r e e , H. F e l k i n , and G. E. M o r r i s , J . Organomet. Chem. 141, 205 (1977). 6. H. C. C l a r k and R. J . O ' B r i e n , I n o r g . Chem. 2, 1020 (1 9 6 3 ) . 7. 0. A. S e r r a , M. P e r r i e r , V. K. L. O s o r i o , and Y. Kawano, I n o r g . Chim. A c t a 17, 135 (1976). 8. J . C h a t t and L. M. V e n a n z i , J . Chem. Soc. 4735 (1957). 9. E. W. A b e l , M. A. B e n n e t t , and G. W i l k i n s o n , J . Chem. Soc. 3178 (1959). 10. P. Fougeroux, B. D e n i s e , R. B o n n a i r e , and G. P a n n e t i e r , J . Organomet. Chem. 60, 375 (1973). 11. M. P. L i and R. S. Drago, J . Am. Chem. Soc. 98, 5129 (1976). 12. K. V r i e z e and H. C. V o l g e r , J . Organomet. Chem. 11, P17 (1968). 13. R. R. S c h r o c k and J . A. Osborn, J . Am. Chem. Soc. 93, 2397 (1971). 14. L. M. H a i n e s , I n o r g . Chem. 9_, 1517 (1970). 15. H. C. C l a r k and K. J . Reimer, I n o r g . Chem. 14, 2133 (1975). 16. H. C. C l a r k and K. J . Reimer, U n p u b l i s h e d R e s u l t s . 17. P. Haake and R. M. P f e i f f e r , J . Am. Chem. Soc. 9_2, 5243 (1970). 18. K. V r i e z e , H. C. V o l g e r , and P. W. N. Van Leeuwen, I n o r g . Chim. A c t a Rev. _3, 109 (1969),and r e f e r e n c e s t h e r e i n . -204-C h a p t e r 3 19. S. Komiya, T. A. A l b r i g h t , R. Hoffmann, and J . K. K o c h i , J . Am. Chem. Soc. 98, 7255 (1976). 20. Y. W. Y a r e d , S. L. M i l e s , R. Bau, and C. A. Reed, J . Am. Chem. Soc. 9_9, 7076 (1977). 21. R. H. C r a b t r e e , A. G a u t i e r , G. G i o r d a n o , and T. Khan, J . Organomet. Chem. 141, 113 (1977). 22. H. I . H e i t n e r and S. J . L i p p a r d , I n o r g . Chem. 11, 1447 (1972). 23. M. Green and T. A. Kuc, J . Chem. Soc. D a l t o n T r a n s . 832 (1972). 24. R. P. Hughes, N. K r i s h n a m a c h a r i , C. J . L. Lo c k , J . P o w e l l , and G. T u r n e r , I n o r g . Chem. 16, 314 (1977). 25. K. V r i e z e , H. C. V o l g e r , and A. P. P r a a t , J . Organomet. Chem. 14, 185 (196 8 ) . 26. I . P. Evans, A. Spencer, and G. W i l k i n s o n , J . Chem. Soc. D a l t o n T r a n s . 204 (1973). 27. C. A. Reed and W. R. Roper, J . Chem. Soc. D a l t o n T r a n s . 1365 (1973). 28. R. S. M c M i l l a n , A. M e r c e r , B. R. James, and J . T r o t t e r , J . Chem. Soc. D a l t o n T r a n s . 1006 (1975). 29. J . H. P r i c e , A. N. W i l l i a m s o n , R. F. Schramm, and B. B. Wayland, I n o r g . Chem. 11, 1280 (1972). 30. W. L. R e y n o l d s , P r o g . I n o r g . Chem. 12, 1 (1970). 31. C. V. Berney and J . H. Weber, I n o r g . Chem. _7_, 283 (1968). 32. C. W h i t e , S. J . Thompson, and P. M. M a i t l i s , J . Chem. Soc. D a l t o n T r a n s . 1654 (1977). 33. T. V. A s h w o r t h , E. S i n g l e t o n , and J . J . Hough, J . Chem. Soc. D a l t o n T r a n s . 1809 (1977). -205-C h a p t e r 3 34. R. G. P e a r s o n , J . Am. Chem. Soc. 85_, 3533 (1963). 35. R. H. C r a b t r e e , H. F e l k i n , T. Khan and G. E. M o r r i s , J . Organomet. Chem. 144, C15 (1978). 36. B. R. James and F. T. T. Ng, J . Chem. Soc. D a l t o n T r a n s . 355 (1 9 7 2 ) ; K. Thomas, J . A. Osborn, A. R. P o w e l l , and G. W i l k i n s o n , J . Chem. Soc. ( A ) , 1801 (1968). 37. G. H e n r i c i - O l i v e and S. O l i v e , T r a n s . Met. Chem. 1, 77 (1976). 38. R. F o w l e r , H. Connor, and R. A. B a s e h l , Chem. Tech. 772 (1976). 39. F. E. P a u l i k , C a t a l y s i s Rev. 6, 49 (1972). -206-R e f e r e n c e s f o r Ch a p t e r 4 1. R. G. P e a r s o n , J . Am. Chem. Soc. 85, 3533 (1963). 2. A F e n s t e r , B. R. James, and W. R. C u l l e n , I n o r g . S y n t h e s e s 17_, 81 (1977). 3. R. D. G i l l a r d and G. W i l k i n s o n , I n o r g . S y n t h e s e s 10, 64 (1967) ; J . A. Osborn and G. W i l k i n s o n , i b i d . 10, 67 (1967). 4. F. C. March and G. F e r g u s o n , Can. J . Chem. 4£, 3585, 3590 ( 1 9 7 1 ) . 5. H. E. Toma, J . M. M a l i n , and E. G i e s b r e c h t , I n o r g . Chem. 1_2, 2084 (1973). 6. H. B. Henbest and J . Trocha-Grimshaw, J . Chem. Soc. P e r k i n I , 607 (1974). 7. E. F. S t r i z h e v , K. A. Khokhryakov, Y. N. K u k u s h k i n , and A. V. G o r d i e v s k i i , Russ. J . I n o r g . Chem. 20, 1685 (1 9 7 5 ) . 8. V. I . S o k o l and M. A. P o r a i - K o s h i t s , K o o r d . Khim. .L, 577 (1975). 9. Y. V. Fadeev, Y. N. K u k u s h k i n , and K. A. Khokhryakov, Russ. J . I n o r g . Chem. 20, 1519 (1975). 10. I . P. Evans, A. Spencer, and G. W i l k i n s o n , J . Chem. Soc. D a l t o n T r a n s . 204 ( 1 9 7 3 ) . 11. V. I . S o k o l , V. N. N i k o l a e v , M. A. P o r a i - K o s h i t s , A. P. K o c h e t k o v a , and L. B. S v e s k n i k o v a , Koord. Khim. 1, 675 (1975). 12. E. A. A l l e n and W. W i l k i n s o n , J . Chem. Soc. D a l t o n T r a n s . 613 (1972). 13. E. M. A r n e t t , E. J . M i t c h e l l , and T. S. S. R. M u r t y , J . Am. Chem. Soc. £6, 3875 ( 1 9 7 4 ) ; J . R e e d i j k , P. W. N. M. Van Leeuwen, and W. L. G r o e n e v e l d , Rec. T r a v . Chim. 87_, 1073 (1968). R. S. Drago, G. C. V o g e l , and T. E. Needham, J . Am. Chem. Soc. 93, 6014 (1971). 14. Y. M. Y. Haddad, H. B. Hen b e s t , and J . Trocha-Grimshaw, J . Chem. Soc. P e r k i n I , 592 (1974). -207-C h a p t e r 4 15. A. M e r c e r and J . T r o t t e r , J . Chem. Soc. D a l t o n T r a n s . 2480 (1975). 16. A. van d e r Ent and A. L. O n d e r d e l i n d e n , I n o r g . S y n t h e s e s 1_4, 92 (1973). 17. D. H a d z i and S. B r a t o s , "The Hydrogen Bond", (Ed. P. S c h u s t e r , G. Z u n d a l , and C. S a n d o r f y ) 2, 567, N o r t h - H o l l a n d , N.Y. ( 1 9 7 6 ) , and r e f e r e n c e s t h e r e i n . 18. F. E i n s t e i n and A. W i l l i s , P e r s o n a l Communication from Simon F r a s e r U n i v e r s i t y . 19. W. C. H a m i l t o n and J . A. I b e r s , "Hydrogen Bonding i n S o l i d s " , p i . W. A. B e n j a m i n , N.Y. (1968). 20. R. Thomas, C. B. Shoemaker, and K. E r i k s , A c t a C r y s t . 21, 12 (1966); M. A. V i s w a m i t a r u and K. K. Kannan, N a t u r e 209, 1016 (1966). 21. P. B i s c a r i n i , L. F u s i n a , G. D. N i v e l i n i , A. Mangia, and G. P e l i z z i , J . Chem.Soc.Dalton Trans.1846 (1 9 7 4 ) ; and r e f e r e n c e s t h e r e i n . 22. J . E. F e r g u s s o n , C. T. Page, and W. T. R o b i n s o n , I n o r g . Chem. 15, 2270 (1976) and r e f e r e n c e s t h e r e i n . 23. M. J . B e n n e t t , F. A. C o t t o n , and D. L. Weaver, A c t a C r y s t . 23, 581 (1967 ) . 24. P. G. Antonov, Y. N. K u k u s h k i n , V. F. Shkredov, L. V. K o n o v a l o v , and B. I . I o n i n , K o o r d . Khim. 3, 907 (1977). 25. D. M o r e l l i , R. Ugo, F. C o n t i , and M. D o n a t i , J . Chem. Soc. Chem. Commun. 801 (1967). 26. G. S. H a r r i s , F. I n g l i s , J . McKechnie, K. K. Cheung, and G. F e r g u s o n , J . Chem. Soc. Chem. Commun. 442 (1967). 27. S. D e t o n i , D. H a d z i , R. S m e r k o l j , J . Hawranek, and L. Sobezyk, J . Chem. Soc. ( A ) , 2851 (1970). -208-C h a p t e r 4 28. G. Modena, I n t . J . S u l f u r Chem. C7_, 95 (1972). 29. M. Spiekermann and B. S c h r a d e r , Angew. Chem. I n t . Ed. 16, 197 (1977). 30. V. I . S o k o l , N. D. R u b t s o v a , and A. Y. Gri b e n y u k , Zh. S t r u k t . Chim. 15, 318 (1974). 31. P. C o l a m a r i n o and P. O r i o l i , J . Chem. Soc. D a l t o n T r a n s . 845 (1976). 32. M. J . B e n n e t t , F. A. C o t t o n , D. L. Weaver, R. J . W i l l i a m s , and G. H. Watson, A c t a C r y s t . 23, 788 (1967). 33. D. A. Langs, C. R. Hare, and R. G. L i t t l e , J . Chem. Soc. Chem. Commun. 1080 (1967). 34. T. G. A p p l e t o n , H. C. C l a r k , and L. E. Manzer, Coord.Chem. Rev. 10, 335 (1973). 35. Y. N. K u k u s h k i n , I n o r g . Chim. A c t a 9_, 117 (1974). 36. W. P a r t e n h e i m e r and E. F. Hoy, J . Am. Chem. Soc. 95, 2840 ( 1 9 7 3 ) , and r e f e r e n c e s t h e r e i n . 37. H. Boucher and B. B o s n i c h , J . Am. Chem. Soc. 99, 6253 (1977). 38. K. Thomas, J . A. Osborn, A. R. P o w e l l , and G. W i l k i n s o n , J . Chem. Soc. ( A ) , 1801 (1968). 39. B. B. Wayland and R. F. Schramm, I n o r g . Chem. 8_, 971 (1969). 40. M. A. B e n n e t t , R. J . 11. C l a r k , and D. L. M i l n e r , I n o r g . Chem. b_, 1647 (1967). 41. B. R. James, R. S. M c M i l l a n , R. H. M o r r i s , and D. K. W. Wang, Adv. Chem. S e r . 167, 122 (1978). 42. R. S. M c M i l l a n , A. M e r c e r , B. R. James, and J . T r o t t e r , J . Chem. Soc. D a l t o n T r a n s . 1006 (1975). 43. D. N. Lawson and G. W i l k i n s o n , J . Chem. Soc. 1900 (1965). -209-C h a p t e r 4 44. S. A. J o h n s o n , H. R. Hunt, and H. M. Neumann, I n o r g . Chem. 2^ , 960 (1963). 45. Y. N. K u k u s h k i n , N. D. R u b t s o v a , and N. V. I v a n n i k o v a , Russ. J . I n o r g . Chem. 15, 1032 (1970). 46. J . H. P r i c e , A. N. W i l l i a m s o n , R. F. Schramm, and B. B. Wayland, I n o r g . Chem. 11, 1280 (1 9 7 2 ) . 47. M. M c P a r t l i n and R. Mason, J . Chem. Soc. ( A ) , 2206 (1970). 48. R. M e l a n s o n and F. D. Rochon, Can. J . Chem. 53, 2371 (1975). 49. R. A. P o t t s , J . I n o r g . N u c l . Chem. 34, 1749 (1972). 50. J . G. Norman, J r . and H. J . K o l a r i , J . Am. Chem. Soc. 100, 791 (1978) . 5 1 . W-W. Tso, C H . Snyder, and H.B. P o w e l l , J . Org. Chem. 35,849 (1970). 52. B. R. James and G. L. Rempel, J . Chem. Soc. ( A ) , 78 (1969). 53. J . F. H a r r o d , S. C i c c o n e , and J . H a l p e r n , Can. J . Chem. 39, 1372 (1961). 54. P. A b l e y , I . J a r d i n e , and F. J . M c Q u i l l i n , J . Chem. Soc. ( C ) , 840 (197 1 ) . 55. Y. A. K o p y t t s e v , L. K. F r e i d l i n , N. M. N a z a r o v a , and I . P. Y a k e v l e v , I z v . Akad. Nauk. S.S.S.R. S e r . Khim. 997 ( 1 9 7 5 ) . 56. W. A. Freeman, J . Chem. Soc. Chem. Commun. 607 (1977). 57. R. S. M c M i l l a n , Ph.D. D i s s e r t a t i o n , U n i v e r s i t y o f B r i t i s h Columbia ( 1 9 7 6 ) . 58. F. T. T. Ng, Ph.D. D i s s e r t a t i o n , U n i v e r s i t y o f B r i t i s h C o l u m b i a , ( 1 9 7 0 ) . 59. B. B o s n i c h , W. G. J a c k s o n , and S. T. D. Lo, I n o r g . Chem. 14, 1460 (1975). -210-Cha p t e r 4 60. H. Boucher and B. B o s n i c h , I n o r g . Chem. Ij5, 717 (1977). 61. B. R. James, F. T. T. Ng and G. L. Rempel, Can. J . Chem. 47, 4521 (1969) . 62. J . M i i l l e r and S. S c h m i t t , J . Organomet. Chem. 97_, 275 (1 9 7 5 ) . 63. B. R. James and D. Mahajan, I s r . J . Chem. 15, 214 (1977). 64. R. E. B u r n e t t , Ph.D. d i s s e r t a t i o n , U. of New Hampshire (1971). 65. R. R. Schrock and J . A. Osborn, J . Am. Chem. Soc. £ 3 , 3089 (1971). 66. B. R. James, R. S. M c M i l l a n , and K. J . Reimer, J . M o l . C a t a l . 1, 439 (1976). 67. B. R. James and F. T. T. Ng, J . Chem. Soc. D a l t o n T r a n s . 355 (1972). -211-R e f e r e n c e s f o r Chap t e r 5 1. Y. M. Y. Haddad, H. B. Henbest, and J . Trocha-Grimshaw, J . Chem. Soc. P e r k i n I , 592 (1974). 2. E. P. K o h l e r and H. M. C h a d w e l l , Org. Syntheses, 1, 78 (1948). 3. H. B. Henbest and J . Trocha-Grimshaw, J . Chem. Soc. P e r k i n I , 601 (1974). 4. M. M c P a r t a i n and R. Mason, J . Chem. Soc. ( A ) , 2206 (1970). 5. J . C h a t t , R. S. C o f f e y , and B. L. Shaw, J . Chem. Soc. 7391 (1965). 6. R. A. Schunn, " T r a n s i t i o n M e t a l H y d r i d e s " , 245 (E. L. M u e t t e r t i e s , ed.) M a r c e l D ekker, N.Y. (1971). 7. R. W. Waldron and J . H. Weber, I n o r g . Chem. 16, 1220 (1977). 8. K. A c h i w a , Chem. L e t t . 297 (1978). 9. Y. Ohgo, Y. N a t o r i , S. T a k e u c h i , and J . Y o s h i m u r a , Chem. L e t t . 709 ( 1 9 7 4 ) . 10. J . S o l o d a r , Chem. Tech. _5» 4 2 1 (1-975). 11. G. D e s c o t e s and D. S i n o u , T e t . L e t t . 4083 (1976). 12. Y. Sasson and J . Blum, J . Org. Chem. 40, 1887 (1975). 13. M. G u l l o t t i , R. Ugo, and S. C o l o n n a , J . Chem. Soc. ( C ) , 2652 (1971). 14. J . A t t e n b u r r o w , A. F. B. Cameron, J . H. Chapman, R. M. Evans, B. A. Hems, A. B. A. J a n s e n , and T. W a l k e r , J . Chem. Soc. 1094 (1952). 15. H. L. G o e r i n g , J . N. E i k e n b e r r y , and G. S. Koermer, J . Am. Chem. Soc. 93, 5913 (1971). 16. See i n d e x i n B. R. James, "Homogeneous H y d r o g e n a t i o n " , W i l e y , N.Y. (19 7 3 ) ; B. R. James, Adv. Organomet. Chem. 17_, i n t h e p r e s s . 17. T. M i z o r k i , K. S e k i , S. Meguro, and A. O z a k i , B u l l . Chem. Soc. J p n . 50, 2148 (1977). -212-C h a p t e r 5 18. Y. M. Y. Haddad, H. B. Henbest, J . Husbands, T. R. B. M i t c h e l l , and J . Trocha-Grimshaw, J . Chem. Soc. P e r k i n I , 596 (1974). 19. H. I m a i , T. N i s h i g u c h i , and K. Fukuzumi, J . Org. Chem. 4J_, 665 (1976). -213-R e f e r e n c e s f o r Ch a p t e r 6 1. D. M. Adams and W. R. Trumble, I n o r g . Chem. 15, 1968 (1970). 2. C. V. Berney and J . H. Weber, I n o r g . Chem. 7_, 283 (1968). 3. C. V. Berney and J . H. Weber, I n o r g . Chim. A c t a 5, 375 (1 9 7 1 ) . 4. R e f e r t o t h e i r s t u d i e s i n C h a p t e r 3 o f t h i s t h e s i s . 5. R. E. Beaumont, R. G. G o e l , and H. S. P r a s a d , I n o r g . Chem. 12, 944 ( 1 9 7 3 ) . 6. J . M e u n i e r and M. T. F o r e l , Can. J . Chem. 50, 1157 (1972). 7. Y. K a k i u t i , S. K i d a , and J . V. Q u a g l i a n o , S p e c t r o c h i m . A c t a 19, 201 ( 1 9 6 3 ) . 8. F. A. C o t t o n , R. F r a n c i s , and W. D. H o r r o c k s , J r . , J . Phys. Chem. 64, 1534 (1 9 6 0 ) . 9. J . H. P r i c e , A. N. W i l l i a m s o n , R. F. Schramm, and B. B. Wayland, • I n o r g . Chem. 11, 1280 (1972). 10. Y. V. Fadeev, Y. N. K u k u s h k i n , and K. A. Khokhryakov, Russ. J . I n o r g . Chem. 20, 1519 (1975). 11. R. S. M c M i l l a n , A. M e r c e r , B. R. James, and J . T r o t t e r , J . Chem. Soc. D a l t o n T r a n s . 1006 (1975). 12. I . P. Evans, A. Spencer, and G. W i l k i n s o n , J . Chem. Soc. D a l t o n T r a n s . 204 (1973). 13. J . R e e d i j k , P. W. N. M. v a n Leeuwen, and W. L. G r o e n e v e l d . Rec. Tr a v . Chim. 87, 1073 (1968). 14. W. F. C u r r i e r and J . H. Weber, I n o r g . Chem. 6, 1539 (1967). 15. R. C. Drago and D. Meek, J . Phys. Chem. 65, 1446 (1961). 16. C. R. P i r i z M a c - C o l l and L. B e y e r , I n o r g . Chem. 12, 7 (1973). -214-C h a p t e r 6 17. B. F. G. Johnson and R. A. W a l t o n , S p e c t r o c h i m . A c t a 22, 1853 (1966). 18. J . S e l b i n , W. E. B u l l , and L. H. Holmes, J r . , J . I n o r g . N u c l . Chem. 16, 219 (1961). 19. D. W. Meek, D. K. S t r a u b , and R. S. Drago, J . Am. Chem. Soc. 82, 6013 (1960). 20. E. B. W i l s o n , J r . , J . C. D e c i u s , and P. C. C r o s s , " M o l e c u l a r V i b r a t i o n s " , p.71. M c G r a w - H i l l , New Y o r k (1955). 21. M. J . B e n n e t t , F. A. C o t t o n , D. L. Weaver, A c t a C r y s t . 23, 581 (1967). 22. R. D. W i l l e t t and K'un Chang, I n o r g . Chim. A c t a 4, 447 (1970). 23. L. C o g h i , C. P e l i z z i , and G. P e l i z z i , J . Organomet. Chem. 114, 53 (1976) . 24. R. D. Shannon and C. T. P r e w i t t , A c t a C r y s t . B26, 1076 (1970). 25. M. T. F o r e l and M. T r a n q u i l l e , S p e c t r o c h i m . A c t a 26A, 1023 (1970) 26. J . M e u n i e r and M. T. F o r e l , S p e c t r o c h i m . A c t a 29A, 487 (1973). 27. B. B. Wayland and R. F. Schramm, I n o r g . Chem. _8, 971 (1969). 28. S. C. J a i n and R. R i v e s t , I n o r g . Chim. A c t a 3_, 552 (1969). 29. R. J . B u t c h e r , H. P. Gunz, R. G. A. R. MacLagan, H. K. J . P o w e l l , C. J . W i l k i n s and Y. S. H i a n , J . Chem. Soc. D a l t o n T r a n s . 1223 (1975). 30. J . A. Broomhead, J . Budge, W. P. Grumley, J . R. Norma and M. S t e r n s , A u s t . J . Chem. 29, 275 (1976). 31. Y. Kawano and V. K. L. O s o r i o , J . In o r g . a n d N u c l e a r Chem. 39, 701 (1977). 32. A. Iwase and S. Tada, N i p p o n Kagaku K a i s h i , 60 (1973). -215-C h a p t e r 6 33. F. A. C o t t o n , R. D. Barnes and E. B a n n i s t e r , J . Chem. Soc. 2199 (1960). 34. K. Nakamoto, " I n f r a r e d S p e c t r a o f I n o r g a n i c and C o o r d i n a t i o n Compounds," 2nd Edn. p.244, W i l e y - I n t e r s c i e n c e , New Y o r k (1973). 35. A. L. A l l r e d , J . I n o r g . &. N u c l e a r Chem. 17_, 215 (1961). 36. Where o n l y X f o r M"""is known, a l o w e r l i m i t f o r h i g h e r o x i d a t i o n s t a t e s i s quo t e d . 37. R. P. O e r t e l , S p e c t r o c h i m . A c t a 26A, 659 (1970). 38. T. Tanaka, I n o r g . Chim. A c t a 1, 217 (1967). 39. L. C o g h i , M. N a r d e l l i , C. P e l i z z i , and G. P e l i z z i , Gazz. Chim. I t a l . 105, 1187 (1975). 40. C. C. A d d i s o n , W. B. Simpson, and A. W a l k e r , J . Chem. Soc. A, 2360 (1964). - 2 1 6 -R e f e r e n c e s f o r C h a p t e r 7 1. H. Boucher and B. B o s n i c h , I n o r g . Chem. J_6, 717 (1977) . 2. I . P. Evans, A. Spencer, and G. W i l k i n s o n , J . Chem. Soc. D a l t o n T r a n s . 204 (1973) . 3. Y. N. K u k u s h k i n and N. D. R u b t s o v a , Russ. J . I n o r g . Chem. 14, 980 (1969) . 4. P. C o l a m a r i n o and P. O r i o l i , J . Chem. Soc. D a l t o n T r a n s . 845 (1976) . 5. E. F. S t r i z h e v , K. A. Khokhryakov, Y. N. K u k u s h k i n , and A. V. G o r d i e v s k i i , Russ. J . I n o r g . Chem. 20, 1685 (1975) . 6. A. W. A d d i s o n , R. D. G i l l a r d , P. S. S h e r i d a n , and L. R. H. T i p p i n g , J . Chem. Soc. D a l t o n T r a n s . 709 (1974) . 7. Y. M. Y. Haddad, H. B. Henbest, and J . Trocha-Grimshaw, J . Chem. Soc. P e r k i n I , 592 (1974) . 8. F. T. T. Ng, Ph.D. D i s s e r t a t i o n , U n i v e r s i t y o f B r i t i s h C olumbia (1970) . 9. C. V. Berney and J . H. Weber, I n o r g . Chem. 7_, 283 (1968) . 

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