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UBC Theses and Dissertations

Manganese, rhenium and rhodium complexes containing pyrazolylgallate ligands Louie, Brenda Maureen 1984

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MANGANESE, RHENIUM AND RHODIUM COMPLEXES CONTAINING PYRAZOLYLGALLATE LIGANDS By BRENDA MAUREEN LOUIE B.Sc. ( H o n o u r s ) , Simon F r a s e r U n i v e r s i t y , 1978 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY i n THE FACULTY OF GRADUATE STUDIES (Dep a r t m e n t 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 UNIVERSITY OF BRITISH COLUMBIA A p r i l 1984 (c) B r e n d a Maureen L o u i e , 1984 I n p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t o f t h e r e q u i r e m e n t s f o r an a d v a n c e d d e g r e e a t t h e 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 , I a g r e e t h a t t h e 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 t u d y . I f u r t h e r a g r e e 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 p u r p o s e s may be g r a n t e d by t h e h e a d o f my d e p a r t m e n t o r by h i s o r h e r r e p r e s e n t a t i v e s . I t i s u n d e r s t o o d t h a t 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 n o t be a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n . D e p a r t m e n t o f CHEMISTRY 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 1956 Main Mall V a n c o u v e r , Canada V6T 1Y3 E-6 (3/81) ABSTRACT D i m e t h y l b i s ( 1 - p y r a z o l y l ) g a l l a t e a n i o n s r e a c t e d w i t h [ R e ( C O ) ^ C l ] 2 t o f o r m u n s t a b l e r h e n i u m t e t r a c a r b o n y l c o m p l e x e s o f t h e t y p e [ M e 2 G a ( C 3 H N 2 R 2 ) 2 ] R e ( C O ) (R=H o r Me). T h e s e com-pounds r e a c t e d w i t h P P h 3 o r pzH, t h e n u c l e o p h i l e d i s p l a c i n g t h e c a r b o n y l g r o u p m u t u a l l y c i s t o b o t h d o n o r s i t e s o f t h e c h e l a t i n g , b i d e n t a t e l i g a n d . N o v e l b i d e n t a t e d i m e t h y l m o n o C l - p y r a z o l y l ) h y d r o x o g a l l a t e l i g a n d s have been p r e p a r e d and f o u r r h e n i u m c o m p l e x e s i n c o r -p o r a t i n g t h e s e l i g a n d s , [ M e 2 G a ( C 3 H N 2 R 2 ) ( O H ) ] R e ( C O ) 3 X (R=H o r Me; X=CO o r PPh-j) a r e d i s c u s s e d . The p h o s p h i n o b r i d g e d r h e n i u m m o l e c u l e , [Me 2Ga(pz)(PPh,,) ] Re(CO)^ has a l s o b e en c o n s i d e r e d . The r e a c t i o n s between v a r i o u s t r i d e n t a t e u n s y m m e t r i c mono-( 1 - p y r a z o l y l ) g a l l a t e l i g a n d s and e i t h e r [Re (CO) 4 C 1 ] 2 o r Mn (CO) j-Br r e s u l t e d i n a s e r i e s o f t r i c a r b o n y l p r o d u c t s . The n i t r o s y l a t i o n s o f s e l e c t e d p y r a z o l y l g a l l a t e r h e n i u m s p e c i e s a r e d i s c u s s e d . The e x p o s u r e o f t h e s e n i t r o s y l a t e d c a t i o n s t o a h y d r i d e s o u r c e d i d n o t l e a d t o t h e i s o l a t i o n , o r s p e c t r o s c o p i c i d e n t i f i c a t i o n , o f any r e d u c e d c o o r d i n a t e d c a r b o n y l m o i e t i e s . I n a d d i t i o n , s e l e c t e d p y r a z o l y l g a l l a t e r h e n i u m t r i c a r b o n y l o r n i t r o s y l c a t i o n i c s p e c i e s c o u l d n o t be i n d u c e d t o u n d e r g o c a r b o n y l m e t a t h e s i s w i t h t e r t i a r y p h o s p h i n e s . The u n i q u e s t e r e o i s o m e r s f o r m e d f r o m t h e r e a c t i o n s between [ R e ( C O ) 4 C l ] 2 and t r i d e n t a t e p y r a z o l y l g a l l a t e a n i o n s c o n t a i n i n g a c h i r a l c a r b o n a r e a l s o d i s c u s s e d . A s e r i e s o f r h o d i u m ( I ) c o m p l e x e s c o n t a i n i n g t h e [ M e 2 G a ( p z ) 2 ] ~ b i d e n t a t e l i g a n d have been p r e p a r e d . These m o l e -c u l e s were f o u n d t o be s t e r e o c h e m i c a l l y n o n r i g i d i n s o l u t i o n . A l t h o u g h one compound c o n t a i n i n g t h e more s t e r i c a l l y demanding [Me 2Ga(pz") ] a n i o n c o u l d be i s o l a t e d , t h e m a j o r i t y o f r e a c -t i o n s w i t h t h i s l i g a n d r e s u l t e d i n t h e f o r m a t i o n o f e x t r e m e l y s t a b l e 3,5 d i m e t h y l p y r a z o l y l b r i d g e d r h o d i u m d i m e r s , t o g e t h e r w i t h [ M e 2 G a ( y - p z " ) ] 2 -The r e a c t i o n o f [ M e G a ( p z ) 3 ] ~ w i t h [ R h ( C O ) 2 C l ] r e s u l t e d i n t h e n o v e l t r i p l y c a r b o n y l b r i d g e d d i m e r [MeGa (pz) 3 ] 3 • The f i r s t e x a m p l e s . o f t r a n s i t i o n m e t a l c a r b o n y l s p e c i e s c o n -t a i n i n g a m e r i d i o n a l l y c o o r d i n a t e d u n s y m m e t r i c m o n o ( 1 - p y r a z o l y l ) g a l l a t e t r i d e n t a t e l i g a n d have been d i s c u s s e d , namely [ M e 2 G a ( . p z ) COCH 2CH 2NMe 2) ]Rh(CO) (n=l and 2). I n a d d i t i o n t h e f i r s t example o f a mixed t r a n s i t i o n m e t a l p y r a z o l y l g a l l a t e com-p l e x , [ M e G a ( p z ) 3 ] M o R h ( P - C O ) 2 ( C O ) ( P P h 3 ) 2 , i s p r e s e n t e d . None o f t h e n o v e l p y r a z o l y l g a l l a t e r h o d i u m s p e c i e s p r e p a r e d e x h i b i t e d m e a s u r a b l e a c t i v i t y as 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 1-hexene o r c y c l o h e x e n e . - i v -TABLE OF CONTENTS Page ABSTRACT.... i i TABLE OF CONTENTS i v L I S T OF TABLES x L I S T OF FIGURES x i i L I S T OF ABBREVIATIONS x v i ACKNOWLEDGEMENT x i x CHAPTER I INTRODUCTION 1 1^1 G e n e r a l I n t r o d u c t i o n 1 1.2 G e n e r a l T e c h n i q u e s 12 1.3 A n a l y s e s and P h y s i c a l Measurements 13 CHAPTER I I RHENIUM CARBONYL DERIVATIVES OF BIDENTATE PYRAZOLYLGALLATE LIGANDS 15 2.1 I n t r o d u c t i o n 15 2.2 E x p e r i m e n t a l 19 2.2.1 S t a r t i n g M a t e r i a l s 19 2.2.2 P r e p a r a t i o n o f [ M e 2 G a ( C 3 H N 2 R 2 ) 2 ] R e ( C O ) 4 (R=H o r Me) 19 2.2.3 P r e p a r a t i o n o f [ M e 2 G a ( C 3 H N 2 R 2 ) 2 ] R e ( C O ) 3 X (R=H o r Me; X=PPh 3 o r pzH) 19 2.2.4 P r e p a r a t i o n o f t h e L i g a n d s N a + [ M e 2 G a ( C 3 H N 2 R 2 ) ( O H ) ] " (R=H o r Me). 21 2.2.5 P r e p a r a t i o n o f [ M e 2 G a ( C 3 H N 2 R 2 ) ( O H ) ] Re (CO). (R=H o r Me) 22 - v -Page 2.2.6 P r e p a r a t i o n o f [ M e 2 G a ( C 3 H N 2 R 2 ) ( O H ) ] Re (CO) 3 (PPh 3) (R=H o r Me) 22 2.2.7 P r e p a r a t i o n o f [ M e 2 G a ( p z ) ( P P h 2 ) ] R e ( C 0 ) 4 24 2.3 R e s u l t s and D i s c u s s i o n . . . . 25 2.3.1 [ M e 2 G a ( C 3 H N 2 R 2 ) 2 ] R e ( C O ) 4 (R=H o r Me) 2 5 2.3.2 [ M e 2 G a ( C 3 H N 2 R 2 ) 2 ] R e ( C O ) 3 X (R=H o r Me; X=PPh 3 o r pzH) 28 2.3.3 [ M e 2 G a ( C 3 H N 2 R 2 ) ( O H ) ] R e ( C O ) 3 X (R=H o r Me; X=C0 o r P P h 3 ) 39 2.3.4 [Me 2Ga (pz) ( PPh 2) ]Re (CO) 4 45 2.4 Summary. 48 CHAPTER I I I RHENIUM AND MANGANESE CARBONYL DERIVATIVES OF TRIDENTATE PYRAZOLYLGALLATE LIGANDS.... 4 9 3.1 I n t r o d u c t i o n 49 3.2 E x p e r i m e n t a l 51 3.2.1 S t a r t i n g M a t e r i a l s 51 3.2.2 P r e p a r a t i o n o f [ M e G a ( p z ) 3 ] R e ( C O ) 3 . . 52 3.2.3 A t t e m p t e d P r e p a r a t i o n o f [ M e G a ( p z " ) 3 ] R e ( C O ) 3 52 3.2.4 P r e p a r a t i o n o f HSCH 2CH 2NH 2 52 3.2.5 P r e p a r a t i o n o f HSCH 2CH 2NMe 2 53 3.2.6 P r e p a r a t i o n o f t h e L i g a n d s N a + [ M e 2 G a ( C 3 H N 2 R 2 ) ( X C H 2 C H 2 N R ' 2 ) ] " (R,R'=H o r Me; X=0 o r S) 53 3.2.7 A l t e r n a t e P r e p a r a t i o n o f t h e L i -gand N a + [ M e 9 G a ( p z ) ( S C H „ C H N M e „ ) ] " . . 54 - v i -Page 3.2.8 P r e p a r a t i o n o f t h e Complexes [Me 2Ga ( C 3 H N 2 R 2 ) (XCR^CR^NR' ) ] Re ( C 0 ) 3 (R, R'=H o r Me; X=0 o r S ) . . 55 3.2.9 P r e p a r a t i o n o f t h e Complexes [ M e 2 G a ( C 3 H N 2 R 2 ) ( S C H 2 C H 2 N R ' 2 ) ] M n ( C 0 ) 3 (R, R'=H o r Me) 55 3.2.10 P r e p a r a t i o n o f t h e Complexes [ M e 2 G a ( p z " ) ( O d ^ O ^ S R ' ) ] Re ( C O ) 3 (R'=Ph o r E t ) . . . 58 3.2.11 N i t r o s y l a t i o n o f LRe(CO) 58 (a) L = [ M e G a ( p z ) 3 ] ~ 61 (b) L = [ M e 2 G a ( C 3 H N 2 R 2 ) ( O C H 2 C H 2 N M e 2 ) ] ~ (R=H o r Me) 61 (c) L = [ M e 2 G a ( C 3 H N 2 R 2 ) ( S C H 2 C H 2 N R , 2 ) ] ~ (R, R'=H o r Me)... 61 3.2.12 R e a c t i o n s o f [ R e ( C O ) 2 ( N O ) C l 2 ] 2 . . . . 61 3.2.13 A t t e m p t e d H y d r i d e R e d u c t i o n o f a C o o r d i n a t e d C a r b o n y l ... 6 2 3.2.14 A t t e m p t e d P r e p a r a t i o n o f i ) LRe ( C O ) 2 ( P P h 3 ) {L = [ M e G a ( p z ) 3 ] ~ o r [ M e 2 G a ( C 3 H N 2 R 2 ) ( O C H 2 C H 2 N M e 2 ) ] " (R=H o r Me)} and i i ) { [ M e 2 G a ( p z " ) (OCH 2CH 2NMe 2) ]Re(CO) (NO) (PPh 3) } + PF ~~ 6 3 6 3.2.15 P r e p a r a t i o n o f Complexes I n c o r -p o r a t i n g a C h i r a l L i g a n d , [Me 2Ga ( p z " ) ( O C H 2 C * H R - N H 2 ) ] R e ( C O ) 3 (R=Me o r E t ) 64 3.3 R e s u l t s and D i s c u s s i o n 65 3.3.1 L M ( C O ) 3 • 65 i - v i i -Page (a) M = Re; L = [MeGa ( C 3 H N 2 R 2 ) ] " (R=H o r Me) 6 5 (b) M = Re; L = [ M e 2 G a ( C 3 H N 2 R 2 ) (OCH 2CH 2NR' 2 ) . ] " (R, R'=H o r Me).... 69 (c) M = Mn o r Re; L = [Me 2Ga ( C 3 H N 2 R 2 ) ( S C H 2 C H 2 N R ' 2 ) ] ~ (R, R'=H o r Me). . . . i . . . 7 5 Cd) M = Re; L = . [Me 2Ga (.C 3HN 2R 2) ('OCH2CH2SR' ) ] " (R=Me ; R 1 =Et o r Ph) . 7 8 3.3.2 R e a c t i v i t y o f L ' R e ( C O ) 3 {L 1 = [.MeGa (pz) 3 ] ~ o r [Me 2Ga ( C 3 H N 2 R 2 ) (OCH 2CH 2NMe 2) ] ~ (R=H o r Me)} 81 (a) N i t r o s y l a t i o n o f L 1 Re ( C O ) 3 . . . . 83 (b) A t t e m p t e d R e d u c t i o n o f a C o o r d i n a t e d CO i n [Me 2Ga (C 3HN 2R 2). COCH 2CH 2NMe 2) ] Re (CO) 2 CNO) + (JR=H. o r Me) 89 Cc) A t t e m p t e d P r e p a r a t i o n o f L'Re (CO) 2 (PR' 3) and [Me 2Ga (.C3HN2R2). COCH 2CH 2NMe 2) ]Re(CO) CNO) (PPh 3) CR=H o r Me; R'=Ph, OPh o r OMe) 92 3.3.3 L * R e ( C O ) 3 {L* = [ M e 2 G a ( p z " ) (OCH 2C*HR-NH 2)]~ • (R=Me o r E t ) } . . . . 95 3.4 Summary 102 CHAPTER IV RHODIUM DERIVATIVES OF BIDENTATE BIS-. PYRAZOLYLGALLATE LIGANDS 104 4.1 I n t r o d u c t i o n 104 4.2 E x p e r i m e n t a l 105 4.2.1 S t a r t i n g M a t e r i a l s 105 4.2.2 P r e p a r a t i o n o f [ M e , G a ( p z ) , ] R h ( C O ) , . 105 - v i i i -Page 4.2.3 P r e p a r a t i o n of [Me^Ga (pz). ^  ] RhCCO). (PPh 3) 106 4.2.4 P r e p a r a t i o n of [Me,,Ga (pz).' ] R h ( P P h 3 ) 2 106 4.2.5 P r e p a r a t i o n of [Me 2Ga(pz) 2]RhCCOD). 107 4.2.6 Reactions of [Me 2Ga (.pz) 2 ]Rh (CO) (a) Attempted Metathesis of CO w i t h pzH or E t 3 N 107 (b) Attempted O x i d a t i o n w i t h r 2 . . . 109 4.2.7 Reactions of N a + [ M e 2 G a ( p z " ) 2 ] ~ wi t h [ R h ( C O ) 2 C l ] 2 or [Rh(COD),Cl] 2. 109 4.2.8 P r e p a r a t i o n of [Me 2Ga ( p z " ) 2 ] R h (CO) (PPh 3) 110 4.3 R e s u l t s and D i s c u s s i o n 113 4.3.1 [Me 2Ga(pz) 2]Rh(X)(Y) [(X) = CO or PPh 3, (Y) = CO or PPh 3; (X)(Y) = COD] 113 4.3.2 Attempted P r e p a r a t i o n of [Me 2Ga(pz") 2]Rh(X)(Y) [(X)(Y) = (CO) (CO) or COD] 122 4.3.3 [Me 2Ga (pz") 2 ] R h (CO) (PPh 3) 126 4.4 Summary 130 CHAPTER V RHODIUM DERIVATIVES OF TRIDENTATE PYRAZOLYLGALLATE LIGANDS 131 5.1 I n t r o d u c t i o n 131 5.2 Experimental 13 3 5.2.1 S t a r t i n g M a t e r i a l s 133 5.2.2 P r e p a r a t i o n of [MeGa(pz)3]2 R n2 C P - C 0 ) 3 133 - i x -Page 5.2.3 R e a c t i o n s o f [MeGa(pz) ] 2 R n 2 ( y - C O ) 3 134 5.2.4 R e a c t i o n o f [ M e G a ( p z " ) 3 ] ~ and [ R h ( C O ) 2 C l ] 2 135 5.2.5 R e a c t i o n o f [ M e G a ( p z ) 3 ] and [ R h ( C O D ) C l ] 2 135 5.2.6 P r e p a r a t i o n o f [ M e 2 G a ( p z ) ( 0 C H „ C H „ N M e o ) ] R h ( C O ) (n=l and 2 ) . . 135 z. z z. n 5.2.7 R e a c t i o n o f [ M e 2 G a ( p z ) ( O C H 2 C H 2 N M e 2 ) ] Rh(CO) (n=l..and 2) w i t h PPh_ . . . . . . 136 n 3 5.2.8 P r e p a r a t i o n o f [MeGa(pz) 3]MoRh(y-CO) 2 (CO) ( P P h ^ . . 137 5.3 R e s u l t s and D i s c u s s i o n 137 5.3.1 [MeGa (pz) 3 ] 2 R h 2 (p-CO) 3 137 5.3.2 R e a c t i o n s o f [ M e G a ( p z ) 3 ] 2 R h 2 ( . y - C O ) 3 145 5.3.3 [ M e 2 G a ( p z ) (OCH 2CH 2NMe 2) ] Rh tCO) (n=l and 2) 14 6 5.3.4 [MeGa(pz) 3]MoRh(y-CO) 2 (CO) CPPh ) 153 5.4 Summary 156 CHAPTER V I CONCLUSION AND PERSPECTIVES 158 BIBLIOGRAPHY 162 APPENDICES 169 APPENDIX I GAS UPTAKE APPARATUS 17 0 APPENDIX I I STEREO DIAGRAMS, BOND LENGTHS AND BOND AN-GLES OF SOME OF THE PREPARED DERIVATIVES.. 173 APPENDIX I I I THEORETICAL INTENSITY PATTERNS FOR MASS SPECTROSCOPIC ANALYSIS 195 - x -L I S T OF TABLES T a b l e Page I P h y s i c a l d a t a f o r [ M e ^ G a ( C 3 H N 2 R 2 ) 2 ^ R E ( C O ) 3 X (R=H o r Me; X=cO, P P h 3 o r pzH) 20 I I P h y s i c a l d a t a f o r [ M e 2 G a ( C 3 H N 2 R 0 ) ( O H ) ] R e ( C O ) 3 X (R=H o r Me; X=CO o r P P h 3 ) 23 I I I Mass s p e c t r a l d a t a o f [ M e 2 G a ( p z ) 2 ] R e ( C O ) 4 26 IV 1 H nmr d a t a f o r [ M e 2 G a ( p z ) 2 ] R e ( C O ) 3 (pzH) 35 V Mass s p e c t r a l d a t a o f [ M e 2 G a ( p z ) ( O H ) ] R e (CO) 3 (PPh 3) 46 V i S e l e c t e d p h y s i c a l d a t a f o r [Me^Ga(C3HN2R2) (XCH2CH2NR' 2)]M(CO)3 (R=H o r Me, R^=H o r Me, X=S when M=Mn; R=H o r Me, R'=H o r Me, X=0 o r S when M=Re) 56 V I I P h y s i c a l d a t a f o r [ M e 2 G a ( p z " ) ( O C H 2 C H 2 S R ' ) ] Re (CO) 3 (R'=Ph o r E t ) 59 V I I I IR and """H nmr d a t a f o r L R e ( C O ) 3 y L R e ( C O ) 2 ( N O ) PF 6~ , 60 IX S e l e c t e d p h y s i c a l d a t a f o r [ M e 2 G a ( p z " ) (OCH 2C*HR-NH 2)]Re(CO)3 (R=Me o r E t ) 66 X 1 H nmr d a t a f o r tMe 2Ga ( C 3 H N 2 R 2 ) (XCH CH NR' ) ] M( C O ) 3 (R=H o r Me, R'=H o r Me, X=S when M=Mn; R=H o r Me, R'=H o r Me, X=0 o r S when M=Re) 71 XI Mass s p e c t r a l d a t a o f [M e 2 G a ( p z ) ( X C H - C H ^ N R ' 2 ) ] M ( C 0 ) 3 (X=0 o r S when M=Re; X=S when M=Mn)... 74 X I I 400 MHz 1 H nmr d a t a f o r [ M e 2 G a ( p z " ) ( 0 C H 2 C * H R - N H 2 ) J R e ( C O ) 3 (R=Me o r E t ) 100 X I I I P h y s i c a l d a t a f o r [ M e 2 G a ( p z ) 2 ] R h ( X ) ( Y ) [ ( X ) = CO o r P P h 3 , (Y)=CO o r P P h 3 ; (X) (Y)=COD] 108 XIV IR and 1 H nmr d a t a f o r [ ( y - p z " ) Rh (X) ] 2 {(X) = ( C O ) 2 o r COD] I l l - x i -T a b l e Page XV P h y s i c a l d a t a f o r [ M e 2 G a ( p z " ) 2 ] R h ( C O ) ( P P h 3 ) . . 112 XVI C o m p a r i s o n o f vCO v a l u e s i n LRh(CO) c o m p l e x e s 113 X V I I Mass s p e c t r a l d a t a f o r [ M e - G a ( p z ) 9 ] R h ( X ) ( Y ) [(X)=CO o r P P h ~ , (Y)=CO o r PPh ; T X ) ( Y ) = COD] 7 114 - x i i -L I S T OF FIGURES F i g u r e Page 1 P y r a z o l e and i m i d a z o l e 1 2 C o o r d i n a t i o n modes o f t h e p y r a z o l a t e a n i o n . . . . 3 3 P l a n a r and b o a t c o n f o r m a t i o n o f t h e b i s ( 1 - p y r a z o l y l ) b o r a t e b i d e n t a t e l i g a n d 5 4 [HB(pz) ]Cu-(CO) 6 5 [ H 2B ( C 3 H N 2 R 2 ) 2 ] 2Mn (R=H o r Me) 7 6 (a) D i m e t h y I b i s ( 1 - p y r a z o l y l ) g a l l a t e a n i o n (b) D i h y d r o b i s ( 1 - p y r a z o l y l ) b o r a t e a n i o n (c) 1,3 d i k e t o n a t e a n i o n 15 7 R e l a t i v e bond d i s t a n c e s i n t h e f-M- (N-N) 2~M ' f r i n g s i n c o m p l e x e s c o n t a i n i n g b i s p y r a z o l y l b i d e n t a t e l i g a n d s (M=Ga o r B, M'= t r a n s i -t i o n m e t a l ) 16 8 P r o p o s e d p l a n a r g e o m e t r y o f t h e [ M e 2 G a ( C 3 H N 2 R 2 ) ( O H ) ] l i g a n d i n o c t a h e d r a l r h e n i u m m o l e c u l e s (R=H o r Me) 18 9 [ M e 2 G a ( p z ) 2 ] R e ( C O ) 4 27 10 IR s p e c t r a o f [ M e 2 G a ( p z ) 2 ] R e ( C O ) 3 ( p z H ) 29 11 M o l e c u l a r s t r u c t u r e o f [ M e 2 G a ( p z ) 2 ] R e ( C O ) 3 (PPh 3) 31 12 Room t e m p e r a t u r e 100 MHz "''H nmr s p e c t r u m f o r [ M e 2 G a ( p z ) 2 ] R e ( C O ) 3 ( P P h 3 ) i n C & D 6 32 13 (a) Room t e m p e r a t u r e 100 MHz ''"H nmr s p e c t r u m f o r [Me Ga(pz) 2 ] R e (CO) 3 (pzH) i n C g D 6 33 (b) Expanded p y r a z o l y l / p y r a z o l e r e g i o n o f 13(a) 34 (c) Computer s i m u l a t e d s p e c t r u m o f t h e p y r a z o l y l / p y r a z o l e r e g i o n shown i n 13(b) u s i n g t h e c o u p l i n g c o n s t a n t s and c h e m i c a l s h i f t s g i v e n i n T a b l e IV 34 14 P r o p o s e d p r o d u c t s i n t h e p r e p a r a t i o n o f [ M e 2 G a ( p z " ) 2 ] R e ( C O ) 3 ( p z H ) 37 - x i i i -F i g u r e Page 15 P r o p o s e d s o l u t i o n mechanism f o r t h e exch a n g e o f p y r a z o l e and p y r a z o l y l g r o u p s i n [ M e 2 G a ( p z " ) 2] Re (CO) 3 (pzH) 37 16 (a) C o n f o r m a t i o n o f [Me,Ga(pz")(OCH,CH N M e J ] Re (CO) 1 l 2. z (b) P r o p o s e d c o n f o r m a t i o n o f [ M e 2 G a ( C 3 H N 2 R 2 ) ( O H ) ] R e ( C O ) 4 (R=H o r Me)...... 42 17 Room t e m p e r a t u r e 100 MHz "*"H nmr s p e c t r u m f o r [ M e 2 G a ( p z " ) (OH)] R e ( C O ) 4 .15 THF i n ( C D ^ C O . . . 43 18 Room t e m p e r a t u r e 100 MHz "^ H nmr s p e c t r u m f o r [ M e 2 G a ( p z ) (OH)] R e ( C O ) 3 ( P P h 3 ) 44 19 P r o p o s e d c o n f o r m a t i o n o f [ Me 2Ga (pz) ( P P h 2 ) ] Re (CO) 4 47 20 Room t e m p e r a t u r e 27 0 MHz ''"H nmr s p e c t r u m f o r [ MeGa (pz) 3 ] Re (CO) 3 67 21 M o l e c u l a r s t r u c t u r e o f [ MeGa (pz) 3] Re (CO) 3 68 22 P o s s i b l e m e r i d i o n a l and f a c i a l c o o r d i n a t i o n modes o f t h e u n s y m m e t r i c p y r a z o l y l g a l l a t e t r i d e n t a t e l i g a n d s 7 0 23 C a r b o n y l r e g i o n o f t h e C f iH,„ s o l u t i o n IR s p e c t r u m o f [ M e 2 G a ( p z ) ( O C H 2 C H 2 N M e 2 ) ] R e ( C O ) 3 . . . 72 24 Room t e m p e r a t u r e 100 MHz "*"H nmr s p e c t r u m f o r [Me 2Ga (pz) (OCH 2CH 2NMe 2) ] Re (CO) 3 i n CgDg 73 25 M o l e c u l a r s t r u c t u r e o f [Me 2Ga (pz")(OCH 2CH 2NMe 2) ] Re (CO) 3 75 26 [Me G a f C J N R J (XOCH CH 2NR ' 2 ) ] M (CO) (M=Mn o r Re, X=0 o r S, R=H o r Me, R^=H o r Me). 77 27 M o l e c u l a r s t r u c t u r e o f [ M e 2 G a ( p z " ) ( 0 C H 2 C H 2 S P h ) ] R e ( C O ) 80 28 [MeGa (pz) 3 ] Re (CO) 2 (NO) + 84 29 V a r i a b l e t e m p e r a t u r e 100 MHz ''"H nmr s p e c t r a o f t h e p y r a z o l y l r e g i o n (~xl-4) f o r [MeGa(pz) 3 ] Re(CO) 2 (NO) i n ( C D ^ C O 85 30 S u b s t i t u t i o n s i t e s i n [Me-Ga(C^HN^R^) ( 0 C H o C H o N M e „ ) ] Re (CO) _ (R=H o r Me) . 7 87 - x i v -Figure Page 31 Diastereomers r e s u l t i n g from the n i t r o s y l a t i o n of [Me 2Ga(C,HN 2R 2) (OCH2CH2NMe2) ]Re(CO) 3 (R=H or Me) 88 32 (n5~C-H,.) Re (CO) _ and [Me Ga (C HN R ) (OCH CH^NR' )]Re(CO)_ (R=H or Mef R'=H or Me)......;.. 90 3 3 Charge separation i n a t e r m i n a l l y coordinated CO l i g a n d 92 34 A s s o c i a t i v e phosphine s u b s t i t u t i o n of ( N 5 - C 5 H 5 ) R e ( C O ) 3 93 35 P o s s i b l e stereoisomers f o r [Me 2Ga(pz") (OCH2C*HR-NH2) ]Re (CO) 3 97 36 (i) Room temperature 400 MHz "''H nmr spectrum f o r [Me Ga (pz" ) (2A1P) ] Re (CO) i n C D 98 ( i i ) - ( v i i ) Double resonance spectra of [Me„Ga(pz") (2A1P) ]Re(CO)_ i n C,D' 98 2 3 6 6 _ g g 37 Molecular s t r u c t u r e of (trans)(+)(R) [Me 2Ga(pz") (2A1B)]Re(CO) 101 38 Proposed ' i n v e r t i n g boat' mechanism f o r [Me Ga(pz) ]Rh(X) (.Y) [ (X) (Y) = (CO) , CCOrCPPh )^or (COD)] f 116 39 V a r i a b l e temperature 100 MHz ^H nmr spectra f o r [Me 2Ga(pz) 2]Rh(CO)(PPh 3) i n (CD 3) 2CO 118 4 0 V a r i a b l e temperature 100 MHz "*"H nmr spectra f o r [Me2Ga (pz) 2]Rh (COD) i n (CT>3) 2CO 119 41 Molecular s t r u c t u r e of [Me 2Ga(pz) 2]Rh(COD)... 121 4 2 V a r i a b l e temperature 100 MHz "*"H nmr spectra of the 'GaMe ' reg i o n f o r [Me.Ga(pz)-]Rh ( P P h 3 ) 2 i n (CD 3) 2CO f T 123 43 Molecular s t r u c t u r e of [(p-pz")Rh(CO) 2] 125 44 Molecular s t r u c t u r e of [(y-pz")Rh(COD)] 2 125 45 Room temperature 100 MHz "^"H nmr spectrum f o r [Me 2Ga(pz") 2]Rh(CO) (PPh 3) i n C gD 6 129 46 Molecular s t r u c t u r e of [Me ?Ga(pz") ?]Rh (CO) (PPh 3) 7 7 130 - XV -F i g u r e Page 4 7 Room t e m p e r a t u r e 27 0 MHz "'"H nmr s p e c t r u m f o r [MeGa (pz) 3 ] 2 R h 2 (y-CO) 3 i n C 6 D g 138 48 M o l e c u l a r s t r u c t u r e o f [MeGa ( p z ) 3 ] 2 R h 2 (y-CO) 3 139 49 { [HN(CH 2CH 2NHCH 2CH 2) 2 0 ] 2 R h 2 (y-CO) 3> + 2 144 50 I R ( c m ^) i n THF o f t h e c a r b o n y l r e g i o n f o r r h o d i u m c a r b o n y l s p e c i e s i n t h e r e a c t i o n b e t w e e n [ R h ( C O ) 9 C l ] ? and [ M e 2 G a ( p z ) ( O C H 2 C H 2 N M e 2 ) ] 148 51 Room t e m p e r a t u r e 100 MHz "*"H nmr s p e c t r u m f o r [Me 2Ga (pz) (OCH 2CH 2NMe 2) ]Rh(CO) i n ( C D ^ C O . . . 150 52 S t e r e o c h e m i c a l a r r a n g e m e n t s f o r [Me 2Ga (pz) 'COCH 2CH 2NMe 2) ]Rh (CO) 2 151 53 LMoRh(y-CO) 0 (CO) ( P P h O „ { L = [MeGa (pz) ] ~ o r ( n 5 - C 5 H 5 f " } ... 155 54 Gas u p t a k e a p p a r a t u s 171 - x v i -L I S T OF ABBREVIATIONS The f o l l o w i n g a b b r e v i a t i o n s have been u s e d t h r o u g h o u t t h i s t h e s i s : A : A n g s t r o m 2A1B : 2 - a m i n o - l - b u t a n o l 2A1P : 2 - a m i n o - l - p r o p a n o l amu : a t o m i c mass u n i t ( s ) A n a l . : A n a l y s i s b r : b r o a d °C : d e g r e e s C e l s i u s C a l ' d . : C a l c u l a t e d c f . : c o n f e r ( i . e . compare) cm ^ : wave number ( r e c i p r o c a l c e n t i m e t e r s ) COD : 1,5 c y c l o o c t a d i e n e c o n t ' d : c o n t i n u e d d : d o u b l e t e . g . : e x e m p l i g r a t i a ( f o r example) E q . : E q u a t i o n (s) E t . : e t h y l ex : e x c e s s F i g . : F i g u r e ( s ) F.T. : F o u r i e r T r a n s f o r m g : gram(s) h : h o u r ( s ) 1 H : p r o t o n - x v i i -Hz : H e r t z ( c y c l e s p e r s e c o n d ) i . e . : i d e s t ( t h a t i s ) IR : i n f r a r e d J : m a g n e t i c r e s o n a n c e c o u p l i n g c o n s t a n t I : l i t r e ( s ) m : m u l t i p l e t M : m o l e s / l i t r e m/e : mass t o c h a r g e r a t i o Me : m e t h y l med : medium min : m i n u t e ( s ) ml : m i l l i l i t r e ( s ) mmol : m i l l i m o l e ( s ) nmr : n u c l e a r m a g n e t i c r e s o n a n c e P : p a r e n t Ph : p h e n y l ppm : p a r t s p e r m i l l i o n p z : p y r a z o l y l , C ^ H ^ ^ p z " : 3,5 d i m e t h y l p y r a z o l y l , C^ti^^ pzH : p y r a z o l e , C ^ H ^ ^ pz"H : 3,5 d i m e t h y l p y r a z o l e , C j - H g ^ s : s i n g l e t s t : s t r o n g t : t r i p l e t THF : t e t r a h y d r o f u r a n U.B.C. : 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 - x v i i i -uv : u l t r a v i o l e t v s : v e r y s t r o n g > : g r e a t e r t h a n : a p p r o x i m a t e l y A : r e f l u x e : e x t i n c t i o n c o e f f i c i e n t n 2 : d i h a p t o n 4 : . t e t r a h a p t o n 5 : p e n t a h a p t o n 6 : h e x a h a p t o x : nmr c h e m i c a l s h i f t y : b r i d g i n g v : IR s t r e t c h i n g f r e q u e n c y - x i x -AC KNOWLEDGEMENT I w o u l d l i k e t o t h a n k p a s t and p r e s e n t c o w o r k e r s and t h e t e c h n i c a l s t a f f o f t h i s d e p a r t m e n t , i n p a r t i c u l a r Ms. M a r g a r e t Heldman (nmr s p e c t r o s c o p y ) and D r . S t e v e R e t t i g ( X - r a y c r y s -t a l l o g r a p h y ) . I w o u l d a l s o l i k e t o a c k n o w l e d g e Dr. D a v i d D o l p h i n f o r t h e g e n e r o u s l o a n o f a t y p e w r i t e r , and Dr. M i c h a e l F r y z u k f o r h i s s u g g e s t i o n s and comments c o n c e r n i n g t h i s t h e s i s . I w o u l d l i k e t o t h a n k R. D a v i d Dobson f o r h i s e n c o u r a g e m e n t . M o s t i m p o r t a n t l y , I am s i n c e r e l y g r a t e f u l t o Dr. A l a n S t o r r whose i d e a s , o p t i m i s m and u n f a i l i n g c h e e r f u l n e s s c o n t r i b u t e d s i g n i f i c a n t l y t o t h e c o m p l e t i o n o f t h i s work. - 1 -CHAPTER I INTRODUCTION 1.1 G e n e r a l I n t r o d u c t i o n Two i s o m e r s , p y r a z o l e and i m i d a z o l e , f o r m t h e c l a s s o f f i v e - m e m b e r e d d i a z o l e c y c l i c compounds. F i g u r e 1. P y r a z o l e (a) and i m i d a z o l e ( b ) . By c o n v e n t i o n n u m b e r i n g a r o u n d e a c h r i n g b e g i n s a t t h e p r o t o n -a t e d n i t r o g e n and p r o c e e d s i n t h e d i r e c t i o n o f t h e s e c o n d n i t r o g e n . The c h e m i s t r y o f i m i d a z o l e , a key s t r u c t u r a l f e a t u r e o f h i s t a m i n e and t h e amino a c i d h l s t i d i n e , has l o n g b e e n an a r e a o f i n t e r e s t . W h i l e a l a r g e number o f i m i d a z o l e d e r i v a t i v e s c a n be f o u n d t h r o u g h o u t n a t u r e , n a t u r a l l y o c c u r r i n g examples o f p y r a z o l e a r e e x c e e d i n g l y r a r e . U n t i l 1954, when J a p a n e s e w o r k e r s i s o l a t e d 3 - n - n o n y l p y r a z o l e f r o m t h e t r o p i c a l A s i a n p l a n t , Houttaynia Covdata ( 1 ) , t h e p y r a z o l e r i n g was b e l i e v e d t o be n o n e x i s t e n t i n n a t u r e . I n 1966 T r o f i m e n k o r e p o r t e d t h e f i r s t s y n t h e s i s o f a - 2 -t r a n s i t i o n m e t a l b o r o n p y r a z o l e complex ( 2 ) . S i n c e t h a t t i m e p y r a z o l e d e r i v e d l i g a n d s have o c c u p i e d a s t e a d i l y g r o w i n g a r e a i n o r g a n o m e t a l l i c c h e m i s t r y and s e v e r a l r e v i e w s have b e e n p u b l i s h e d on t h e s u b j e c t (3-5) . P y r a z o l e c a n be r e a d i l y d e p r o t o n a t e d by a p p r o p r i a t e b a s e s , f o r m i n g t h e p y r a z o l a t e a n i o n as shown i n e q u a t i o n [ 1 ] . A c i r c l e i s drawn i n s i d e t h e a n i o n r i n g t o summarize t h e r e s o -n ance forms w h i c h c a n be e n v i s a g e d . -f- N a H N a + f l ] N N T h i s a n i o n i s c a p a b l e o f i n t e r a c t i n g w i t h s u i t a b l e t r a n s i t i o n m e t a l s t h r o u g h one o f t h r e e p o s s i b l e c o o r d i n a t i o n modes. I n t h e most commonly f o u n d c o o r d i n a t i o n g e o m e t r y t h e p y r a z o l a t e a n i o n a c t s as an e x o b i d e n t a t e b r i d g e between two m e t a l s , w h i c h may be i d e n t i c a l o r d i f f e r e n t ( F i g . 2 a ) . T h e r e a r e numerous examples o f s t a b l e compounds r e p o r t e d i n t h e l i t e r a t u r e c o n -t a i n i n g s u c h b r i d g e s ( e . g . 6-10). The p y r a z o l a t e a n i o n may a l s o r e m a i n m o n d e n t a t e upon c o o r d i n a t i o n t o a t r a n s i t i o n m e t a l ( F i g . 2 b ) , however examples o f t h i s t y p e r e m a i n r e l a t i v e l y few ( e . g . 11, 1 2 ) . 3 N N / \ / M M M M (a) (b) (c) F i g u r e 2. C o o r d i n a t i o n modes o f t h e p y r a z o l a t e a n i o n . I n one u n i q u e c a s e an X - r a y c r y s t a l s t r u c t u r e a n a l y s i s o f a u r a n i u m (IV) comple x c o n f i r m e d n 2 - e n d o b i d e n t a t e c o o r d i n a t i o n o f a p y r a z o l a t e a n i o n ( F i g . 2 c ) . I t has been s u g g e s t e d t h a t t h i s u n u s u a l b o n d i n g mode i s a r e f l e c t i o n o f i ) t h e i o n i c c h a r a c t e r o f t h e u r a n i u m - n i t r o g e n b o n d s , and i i ) t h e l a r g e r a t o m i c r a d i u s o f u r a n i u m ( 1 3 ) . When c o o r d i n a t e d t o c e r t a i n m a i n g r o u p e l e m e n t s m o n o d e n t a t e i n t e r a c t i o n s o f t h e p y r a z o l a t e a n i o n (as shown i n F i g . 2b) become more common ( e . g . 1 4 - 1 7 ) . The most w i d e l y s t u d i e d o f t h e s e main g r o u p s y s t e m s a r e t h e p o l y ( 1 - p y r a z o l y l ) b o r a t e s w i t h t h e g e n e r a l f o r m u l a T h e s e p y r a z o l y l b o r a t e s c a n be p r e p a r e d by t h e r e a c t i o n o f p y r a z o l e w i t h an a l k a l i m e t a l b o r o h y d r i d e , t h e e x t e n t o f s u b s t i t u t i o n d e p e n d e n t on t h e r e a c t i o n t e m p e r a t u r e as shown i n scheme 1 ( 1 4 ) . The s t a b i l i t y o f t h e p o l y ( 1 - p y r a z o l y l ) b o r a t e s p e c i e s i n s o l u t i o n [ H n B ( p z ) 4-n (n= 0 , l , 2 ; p z = p y r a z o l y l , C_H,N_) - 4 -(c) (b) Scheme 1. d e c r e a s e s a s t h e number o f h y d r o g e n s a t t a c h e d t o t h e b o r o n i n c r e a s e , a l t h o u g h t h e s a l t s o f a l l t h r e e a n i o n s a r e a i r s t a b l e and c a n be s t o r e d i n d e f i n i t e l y i n t h e s o l i d s t a t e . The p o l y ( 1 - p y r a z o l y l ) b o r a t e s h a v e b e e n shown t o be v e r s a t i l e l i g a n d s w i t h e x c e l l e n t c h e l a t i n g a b i l i t i e s . They c a n a c t a s e i t h e r b i d e n t a t e o r t r i d e n t a t e l i g a n d s , c o o r d i n a t i o n t o a t r a n s i t i o n m e t a l o c c u r r i n g v i a a d o n a t i o n o f t h e l o n e p a i r o f - 5 -e l e c t r o n s on t h e ' f r e e ' n i t r o g e n [ i . e . N ( 2 ) J o f e a c h p y r a z o l y l g r o u p . A l l t h r e e a n i o n s shown i n ..scheme \ 1 c a n f u n c t i o n a s b i d e n t a t e c h e l a t i n g l i g a n d s . When c o o r d i n a t e d i n a b i d e n t a t e manner t h e y a r e u n i n e g a t i v e , f o u r e l e c t r o n d o n o r s , and f o r m a l l y a n a l o g o u s y t o t h e w e l l known g - d i k e t o n a t e i o n s . I n c o m p l e x e s c o n t a i n i n g a b i d e n t a t e p y r a z o l y l b o r a t e l i g a n d , t h e f-B- (N-N) 2 _ M J " ( M = t r a n s i t i o n m e t a l ) six-membered r i n g must r e m a i n e i t h e r p l a n a r o r i n a b o a t c o n f o r m a t i o n t o accommodate t h e two p l a n a r b r i d g i n g p y r a z o l y l r i n g s . (a) (b) F i g u r e 3. P l a n a r (a) and b o a t (b) , c o n f o r m a t i o n o f t h e b i s ( 1 - p y r a z o l y l ) b o r a t e b i d e n t a t e l i g a n d . M o l e c u l a r m o d els i n d i c a t e t h a t s t e r i c f a c t o r s f a v o u r a b o a t o v e r a p l a n a r a r r a n g e m e n t and s e v e r a l c r y s t a l s t r u c t u r e s have shown t h a t a p r o n o u n c e d b o a t i s i n f a c t t h e most common geometry o f b i s p y r a z o l y l b o r a t e - t r a n s i t i o n m e t a l c o m p l e x e s i n t h e s o l i d - 6 -s t a t e ( e . g . 1 8 , 1 9 ) . The c o o r d i n a t e d t r i d e n t a t e [EB(pz)^] and [ B ( p z ) 4 ] ~ l i g a n d s have a p p r o x i m a t e C 3 v symmetry and occupy, t h r e e , m u t u a l l y c i s p o s i t i o n s when c o o r d i n a t e d t o a t r a n s i t i o n m e t a l . 1 A t y p i c a l example i s shown i n F i g . 4. The t r i d e n t a t e b o r a t e l i g a n d s a r e u n i n e g a t i v e , s i x e l e c t r o n d o n o r s and a r e most o f t e n compared t o t h e i s o e l e c t r o n i c c y c l o p e n t a d i e n y l a n i o n . I t i s p o s s i b l e t o a l t e r t h e e l e c t r o n d o n a t i n g s t r e n g t h o r g r e a t l y change t h e s p a c e r e q u i r e m e n t o f t h e p o l y ( 1 - p y r a z o l y l ) -b o r a t e l i g a n d s by s u b s t i t u t i n g i ) t h e h y d r o g e n s on t h e p y r a z o l y l r i n g s , o r i i ) t h e h y d r o g e n s on t h e b o r o n w i t h d i f f e r e n t a l k y l o r a r y l g r o u p s o r h a l o g e n s . T h i s p r o p e r t y f u r t h e r e n h a n c e s t h e s y n t h e t i c v e r s a t i l i t y o f t h e l i g a n d s . F o r example, m e t h y l s u b s t i t u e n t s c a n be e a s i l y i n t r o d u c e d a t t h e C(3) and C(5) p o s i t i o n s o f t h e p y r a z o l y l g r o u p s by u s i n g 3,5 d i m e t h y l p y r a z o l e i n s t e a d o f p y r a z o l e i n t h e l i g a n d s y n t h e s i s . Thus w h i l e t h e b i d e n t a t e l i g a n d [ t ^ B f p z ^ ] f o r m s a i r s e n s i t i v e b i s b i d e n t a t e c h e l a t e s w i t h M n ( I I ) ( F i g . 5 a ) , t h e c o r r e s p o n d i n g compound F i g u r e 4. [ H B ( p z ) 3 ] C u ( C O ) - 7 -c o n t a i n i n g [ H 2 B ( p z " ) 2 ] (pz" = 3,5 d i m e t h y l p y r a z o l y l , C^ -H^ N,,) ( F i g . 5b) i s an a i r s t a b l e s o l i d (20). I t has g e n e r a l l y b e en f o u n d t h a t a l k y l s u b s t i t u e n t s on e i t h e r t h e p y r a z o l y l r i n g s o r t h e b o r o n have an a d d i t i o n a l s t a b i l i z i n g e f f e c t on r e s u l t i n g c o o r d i n a t i o n c o m p l e x e s . T h i s has been i n t e r p r e t e d as r e s u l t i n g f r o m a c o m b i n a t i o n o f i ) t h e i n c r e a s e d e l e c t r o n d o n a t i n g a b i l i t y o f t h e l i g a n d , and i i ) t h e a d d i t i o n a l s t e r i c p r o t e c t i o n o f t h e t r a n s i t i o n m e t a l (2). A l k y l s u b s t i t u t i o n s on p o l y ( 1 - p y r a z o l y l ) b o r a t e l i g a n d s have a l s o e f f e c t e d some s u r p r i s i n g c h a n g es i n t h e r e a c t i v i t y o f r e s u l t i n g c o o r d i n a t i o n c o m p l e x e s . F o r example, w h i l e a r e n e d i a z o n i u m c a t i o n s r e a c t e d w i t h [ H B ( p z ) 3 ] M o ( C O ) 3 t o y i e l d a s t r a i g h t f o r w a r d c a r b o n y l d i s p l a c e m e n t p r o d u c t as shown i n e q u a t i o n [2] (21), [ H B ( p z " ) 3 ] M o ( C O ) 3 e x p o s e d t o t h e same r e a c t i o n c o n d i t i o n s r e s u l t e d i n t h e f o r m a t i o n o f an u n e x p e c t e d n o v e l n 2 _ a r o y l p r o d u c t {Eq. [3]} (22). F u r t h e r m o r e , when t h e same r e a c t i o n was c a r r i e d o u t i n m e t h y l e n e c h l o r i d e , a complex (a) R = H (b) R =Me F i g u r e 5. [ H 2 B ( C 3 H N 2 R 2 ) 2 ] 2 M n . - 8 -H—B^—/ N/^ Mv M°(CO)," • • -CO DMF \<0>/ M,Ar [ 2 ] N—N MotCO)^ • Ar ArN, CH.CI, M*CN or 4* N—N [3] c o n t a i n i n g an u n p r e c e d e n t e d n 1 - c h l o r o m e t h y l i d y n e m o i e t y was i s o l a t e d ( 2 3 ) . A l t h o u g h t h e b o r a t e s have been t h e most e x t e n s i v e l y s t u d i e d o f t h e p o l y ( 1 - p y r a z o l y l ) m u l t i d e n t a t e l i g a n d s , r e l a t e d l i g a n d - 9 -s y s t e m s i n c o r p o r a t i n g o t h e r m a i n g r o u p e l e m e n t s have a l s o b e en p r e p a r e d . The c h a r g e on t h e s e l i g a n d s depends on t h e m a i n g r o u p e l e m e n t i n v o l v e d and t h e number o f p y r a z o l y l g r o u p s l i n k e d t o i t . C o o r d i n a t i o n compounds c o n t a i n i n g p o l y ( 1 - p y r a -z o l y l ) a l k a n e s (3, 15, 2 4 ) , t r i s ( 1 - p y r a z o l y l e t h y l ) a m i n e s (17) and p h e n y l ( 1 - p y r a z o l y l ) p h o s p h i n e s (25, 26) h a v e b e e n r e p o r t e d . P r e v i o u s work i n t h i s l a b o r a t o r y has c o n c e n t r a t e d on t h e s y n t h e s e s and c o o r d i n a t i n g a b i l i t i e s o f p o l y ( 1 - p y r a z o l y l ) g a l -l a t e l i g a n d s (16, 2 7 - 3 3 ) , as w e l l as u n u s u a l u n s y m m e t r i c mono-( 1 - p y r a z o l y l ) g a l l a t e t r i d e n t a t e l i g a n d s ( 3 4 - 4 6 ) . P o l y ( 1 - p y r a z o l y l ) g a l l a t e l i g a n d s w i t h t h e g e n e r a l f o r m u l a [Me G a ( C 3 H N 2 R 2 ) 4 ] ~ (n=l,2; R=H o r Me) have been p r e p a r e d (16, 30, 3 1 ) . Compared t o t h e marked s t a -b i l i t y o f t h e p o l y ( 1 - p y r a z o l y l ) b o r a t e s a l t s , a l k a l i m e t a l s a l t s o f t h e s e p y r a z o l y l g a l l a t e a n i o n s a r e e x t r e m e l y h y g r o s c o p i c , w h i t e s o l i d s . The s t a b i l i t y o f t h e s e s a l t s i m p r o v e s when m e t h y l s u b s t i t u e n t s a r e p r e s e n t a t t h e C(3) and C(5) p o s i t i o n s o f t h e p y r a z o l y l r i n g s . Numerous a i r s t a b l e compounds have been i s o l a t e d f r o m t h e r e a c t i o n s between p o l y ( 1 - p y r a z o l y l ) g a l l a t e a n i o n s and t r a n s i t i o n m e t a l d e r i v a t i v e s . I n g e n e r a l t h e c o o r d i n a t i n g b e h a v i o u r o f t h e s e m u l t i d e n t a t e l i g a n d s r e s e m b l e s t h a t o f t h e i r b o r o n a n a l o g s . However one n o t a b l e d i f f e r e n c e between t h e p y r a z o l y l g a l l a t e s and b o r a t e s i s t h e c a p a c i t y t o p r e p a r e u n s y m m e t r i c m o n o ( 1 - p y r a -z o l y l ) g a l l a t e l i g a n d s . T h i s c a n be a c c o m p l i s h e d by s u b s t i t u t i n g - 1 0 -a s u i t a b l e m o l e c u l e c o n t a i n i n g an a c i d i c h y d r o g e n i n p l a c e o f p y r a z o l e i n t h e o r i g i n a l g a l l a t e l i g a n d s y n t h e s i s . A t y p i c a l example i s i l l u s t r a t e d b elow. Scheme 2 . Thus t h e s u b s t i t u t i o n o f p y r a z o l e f o r 2-N,N-dimethy1amino-e t h a n o l r e s u l t s i n t h e f o r m a t i o n o f a p o t e n t i a l l y t r i d e n t a t e l i g a n d s y s t e m . The a l k a l i m e t a l s a l t s o f t h i s and s i m i l a r mono-( 1 - p y r a z o l y l ) a n i o n s a r e e x t r e m e l y u n s t a b l e and a t t e m p t s t o i s o l a t e them i n t h e s o l i d s t a t e have been u n s u c c e s s f u l . Con-s e q u e n t l y t h e y have been c h a r a c t e r i z e d i n s o l u t i o n o n l y ( 3 4 ) . U n l i k e t h e t r i s ( 1 - p y r a z o l y l ) g a l l a t e o r b o r a t e l i g a n d s , - 11 -w h i c h a r e n o t p h y s i c a l l y c a p a b l e o f c o o r d i n a t i n g i n a m e r i d i o n a l manner, t h e u n s y m m e t r i c g a l l a t e l i g a n d s c a n b i n d i n e i t h e r a m e r i d i o n a l (35,39) o r f a c i a l (35,37) a r r a n g e m e n t . The e x i s t e n c e o f b o t h t y p e s o f l i g a n d g e o m e t r i e s has been c o n f i r m e d by 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 s . I n t e r e s t i n g l y , a t t e m p t s t o p r e p a r e a n a l o g o u s b o r o n unsym-m e t r i c l i g a n d s have n o t been s u c c e s s f u l (47) . To d a t e t h e unsym-m e t r i c t r i d e n t a t e m o n o ( 1 - p y r a z o l y l ) g a l l a t e l i g a n d s have no c o u n t e r p a r t among p y r a z o l e d e r i v e d l i g a n d s y s t e m s . I n C h a p t e r I I o f t h i s work r e a c t i o n s between t h e s y m m e t r i c b i s ( 1 - p y r a z o l y l ) g a l l a t e l i g a n d s , [ M e 2 G a ( C 3 H N 2 R 2 ) ] " (R=H o r Me), and r h e n i u m c a r b o n y l c h l o r i d e a r e d i s c u s s e d . I n a d d i t i o n n o v e l u n s y m m e t r i c b i d e n t a t e m o n o ( 1 - p y r a z o l y l ) g a l l a t e l i g a n d s o f t h e t y p e [ M e 2 G a ( C 3 H N 2 R 2 ) ( Y ) ] ~ (R=H o r Me, Y*OH; R=H, Y=PPh 2) have been p r e p a r e d i n situ and t h e i r r e a c t i o n s w i t h r h e n i u m c a r b o n y l h a l i d e a r e d e t a i l e d . A number o f o c t a h e d r a l R e ( I ) and Mn(I) c o m p l e x e s i n c o r p o r a t -i n g t r i d e n t a t e p y r a z o l y l g a l l a t e l i g a n d s a r e d i s c u s s e d i n C h a p t e r I I I . New u n s y m m e t r i c l i g a n d s c o n t a i n i n g s u l f u r a s one o f t h e l i g a n d d o n o r s i t e s have been p r e p a r e d and t h e i r c o o r d i n a t -i n g p r o p e r t i e s s t u d i e d . I n a d d i t i o n t h e s t e r e o c h e m i s t r y o f R e ( I ) m o l e c u l e s when a c h i r a l c a r b o n i s i n t r o d u c e d i n t o t h e u n s y m m e t r i c t r i d e n t a t e l i g a n d i s c o n s i d e r e d . C e r t a i n i i a s p e c t s o f t h e r e a c t i v i t y o f t h e new p y r a z o l y l g a l l a t e r h e n i u m c o m p l e x e s s y n t h e s i z e d a r e a l s o d i s c u s s e d . - 12 -R e a c t i o n s o f b i d e n t a t e ( C h a p t e r IV) and t r i d e n t a t e '(Chap-t e r V) p y r a z o l y l g a l l a t e l i g a n d s w i t h v a r i o u s r h o d i u m p r e c u r s o r s r e s u l t e d i n some i n t e r e s t i n g and n o v e l compounds. S e v e r a l o f t h e s e c o m p l e x e s were t e s t e d as p o t e n t i a l 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 o l e f i n s . No c a t a l y t i c a c t i v i t y was n o t e d -p e r h a p s e m p h a s i z i n g t h e g e n e r a l s t a b i l i t y o f p y r a z o l y l g a l l a t e t r a n s i t i o n m e t a l c o m p l e x e s i n s o l u t i o n as w e l l as i n t h e s o l i d s t a t e . 1. 2 G e n e r a l T e c h n i q u e s A i r s e n s i t i v e m a t e r i a l s were m a n i p u l a t e d i n a Vacuum/ A t m o s p h e r e s C o r p o r a t i o n d r y box (model DRI LAB HE-43-2) c o n -t a i n i n g n i t r o g e n ( L i n d e USP, U n i o n C a r b i d e ) and f i t t e d w i t h a HE 493 D r i t r a i n . U n l e s s o t h e r w i s e s p e c i f i e d , r e a c t i o n s were c a r r i e d o u t i n t h e d r y box o r i n a n i t r o g e n b l a n k e t e d atmos-p h e r e . S p e c t r o g r a d e s o l v e n t s were u s e d f o r s o l u t i o n IR, g e n e r a l l y 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 . D e u t e r a t e d s o l v e n t s , u s e d i n "*"H nmr s a m p l e s , were t h o r o u g h l y d e g a s s e d on a h i g h vacuum l i n e and s t o r e d u n d e r vacuum. A l l r e a c t i o n s o l v e n t s were d r i e d a c -c o r d i n g t o l i t e r a t u r e methods (48) and d i s t i l l e d u n d e r n i t r o g e n b e f o r e u s e . The f r e q u e n t l y u s e d s o l v e n t s THF and b e n z e n e , d r i e d o v e r s odium/benzophenone and m o l t e n p o t a s s i u m r e s p e c t i v e l y , were r e f l u x e d c o n t i n u o u s l y i n 21 s t i l l p o t s and c o l l e c t e d j u s t p r i o r t o u s e o r s t o r e d i n t h e d r y box f o l l o w i n g d i s t i l l a t i o n . - 13 -1 . 3 A n a l y s e s and P h y s i c a l Measurements E l e m e n t a l a n a l y s e s were p e r f o r m e d by Mr. P. B o r d a o f t h e U.B.C. M i c r o a n a l y t i c a l L a b o r a t o r y . 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 E l m e r 598 s p e c t r o m e t e r u s i n g e i t h e r t h e g r a t i n g change a t 2000 cm ^ o r t h e 1601 cm band o f p o l y s t y r e n e f o r c a l i b r a t i o n p u r p o s e s . Samples were p r e p a r e d as N u j o l m u l l s between KBr. p l a t e s o r as s o l u t i o n s , u s u a l l y i n c y c l o h e x a n e o r m e t h y l e n e c h l o r i d e . "^H nmr s t u d i e s were p r i m a r i l y c a r r i e d o u t on a B r u k e r WP 8 0 o r a V a r i a n XL-100 s p e c t r o m e t e r by t h e U.B.C. nmr s t a f f , u s i n g F T t e c h n i q u e s . Where b e t t e r r e s o l u t i o n o r more d e t a i l e d s p e c t r a were d e s i r a b l e a N i c o l e t - O x f o r d H-270 o r B r u k e r WH-400 s p e c t r o -meter'. -vMs; -u<sej§!:. Samples were p r e p a r e d by c o n d e n s i n g ~1 ml o f s o l v e n t (CgDg o r d g - a c e t o n e ; Merck S h a r p and Dohme o f Canada L t d . o r A l d r i c h Chem. Co.) o n t o t h e s o l i d m a t e r i a l c o n t a i n e d i n a nmr t u b e f i t t e d w i t h a t a p a d a p t o r . The nmr t u b e was s u b s e q u e n t l y f l a m e s e a l e d u n d e r a vacuum. C h e m i c a l s h i f t s were m e a s u r e d r e l a t i v e t o t h e s o l v e n t , w h i c h s e r v e d as an i n t e r n a l s t a n d a r d . xCgHg i s d e f i n e d t o e q u a l 2.84 ppm and xCCH^^CO i s d e f i n e d t o e q u a l 7.8 9 ppm i n a l l s p e c t r a . Mass s p e c t r a were r e c o r d e d by t h e U.B.C. mass s p e c t r o m e t r y s e r v i c e . G e n e r a l l y s p e c t r a were r e c o r d e d on a VARIAN/MAT CH4B s p e c t r o m e t e r when t h e m o l e c u l a r w e i g h t o f t h e sample was l e s s t h a n 50 0 amu. T h e s e s p e c t r a were o b t a i n e d on c h a r t p a p e r and t h e r e l a t i v e i n t e n s i t i e s and masses o f i o n s i g n a l s d e t e r m i n e d m a n u a l l y . F o r h e a v i e r s a m p l e s (>500 amu) s p e c t r a w e r e . r e c o r d e d - 14 -on an AES MS 50 ( K r a t o s ) s p e c t r o m e t e r i n t e r f a c e d t o a computer p r i n t o u t s y s t e m . H e r e m/e v a l u e s and r e l a t i v e , as w e l l as a b s o l u t e , i n t e n s i t i e s c o u l d be r e a d d i r e c t l y f r o m t h e p r i n t o u t . I n c a l c u l a t i n g t h e r e l a t i v e i n t e n s i t i e s o f f r a g m e n t s w h i c h c o n t a i n e d more t h a n one i s o t o p e , i s o t o p e i i n t e n s i t i e s were added t o g e t h e r t o o b t a i n t h e t o t a l i n t e n s i t y o f t h e f r a g m e n t i n q u e s t i o n . M e l t i n g and d e c o m p o s i t i o n p o i n t s (°C) a r e u n c o r r e c t e d and were d e t e r m i n e d on a G a l l e n k a m p a p p a r a t u s u s i n g s e a l e d c a p i l l a r y t u b e s when n e c e s s a r y t o c o n t a i n t h e s a m p l e . On o p t i c a l l y a c t i v e compounds a b s o r p t i o n maxima were d e t e r m i n e d u s i n g a CARY 14 u v - v i s i b l e s p e c t r o m e t e r . Samples were p r e p a r e d a s a c e t o n i t r i l e s o l u t i o n s and were h a n d l e d i n t h e a i r . These same s a m p l e s were i n s e r t e d i n t o an ORD CD s p e c t r o m e t e r (J-20 JASCO I n c . ) and t h e i r c i r c u l a r d i c h r o i s m s p e c t r a m e a s u r e d . ;nus W i t h n s e l e c t e d r h o d i u m c o m p l e x e s , h y d r o g e n a t i o n e x p e r i m e n t s were p e r f o r m e d a t ~720 t o r r p r e s s u r e w i t h an a p p a r a t u s c a p a b l e e^f' m e a s u r i n g gas u p t a k e . T h i s a p p a r a t u s was c o u p l e d t o a h i g h vacuum l i n e t o e n s u r e e x c l u s i o n o f o x y g e n and o t h e r c o n t a m i n a n t s f r o m t h e r e a c t i o n v e s s e l . A d i a g r a m and d e s c r i p t i o n o f t h i s e x p e r i m e n t a l a p p a r a t u s i s i n A p p e n d i x 1. X i r a y s t r u c t u r a l a n a l y s e s were p e r f o r m e d by D r . S. R e t t i g o f t h e c r y s t a l l a b o r a t o r y a t U.B.C. C r y s t a l l o g r a p h i c d e t e r m i n a -t i o n s were c o n d u c t e d on s i n g l e c r y s t a l s u s i n g g r a p h i t e mono-chiromated Mo-K r a d i a t i o n on an E n r a f - N o n i u s CAD4-F d i f f r a c t o -m e t e r . S t e r e o , d i a g r a m s and r e l a t e d bond d i s t a n c e s and a n g l e s a r e i n A p p e n d i x I I . - 15 -CHAPTER I I RHENIUM CARBONYL DERIVATIVES OF BIDENTATE PYRAZOLYLGALLATE LIGANDS 2.1 I n t r o d u c t i o n E a r l i e r r e p o r t s h a v e d e s c r i b e d c o m p l e x e s r e s u l t i n g f r o m t h e r e a c t i o n o f t h e b i d e n t a t e a n i o n i c d i m e t h y I b i s ( 1 - p y r a z o l y l ) -g a l l a t e l i g a n d , [ M e 2 G a ( p z ) 2 ] , w i t h d i v a l e n t t r a n s i t i o n m e t a l i o n s ( 1 6 , 2 7 - 2 9 ) , N i and Pd a l l y l h a l i d e s ( 3 2 ) , and Mn, Mo a n d W c a r b o n y l d e r i v a t i v e s ( 3 3 ) . T h i s l i g a n d h a s b e e n c o m p a r e d t o s i m i l a r i s o e l e c t r o n i c c h e l a t i n g l i g a n d s , n a m e l y t h e d i h y d r o -b i s ( 1 - p y r a z o l y l ) b o r a t e a n d 1 , 3 - d i k e t o n a t e a n i o n s . Me / N-N-(a) H B N-(b) (c) F i g u r e 6 (a) D i m e t h y l b i s ( 1 - p y r a z o l y l ) g a l l a t e a n i o n (b) D i h y d r o b i s ( 1 - p y r a z o l y l ) b o r a t e a n i o n (c) 1 , 3 - d i k e t o n a t e a n i o n E a c h o f t h e s e b i d e n t a t e l i g a n d s a r e u n i n e g a t i v e , f o u r e l e c t r o n d o n o r s . However i m p o r t a n t d i f f e r e n c e s h a v e b e e n f o u n d t o e x i s t b e t w e e n t h e t h r e e c h e l a t e s . F o r e x a m p l e , w h i l e v a r i o u s - 16 -a s s o c i a t i v e e q u i l i b r i a c a n o c c u r i n c o m p l e x e s c o n t a i n i n g t h e 1 , 3 - d i k e t o n a t e g r o u p ( 4 9 ) , c o r r e s p o n d i n g p y r a z o l y l g a l l a t e and p y r a z o l y l b o r a t e compounds a r e a l w a y s monomeric. T h i s r e s u l t s f r o m a c o m b i n a t i o n o f t h e c o o r d i n a t i o n g e o m e t r y o f t h e p y r a z o l y l l i g a n d s and a l a c k o f a v a i l a b l e e l e c t r o n p a i r s a b l e t o t a k e p a r t i n f u r t h e r bond f o r m a t i o n ( 3 ) . D i f f e r e n c e s a l s o e x i s t between t h e c h e l a t e d b i s ( 1 - p y r a z o -l y l ) b o r a t e and c o r r e s p o n d i n g g a l l a t e a n i o n s . X - r a y s t r u c t u r e a n a l y s e s have c o n f i r m e d t h a t b o t h b i d e n t a t e l i g a n d s g e n e r a l l y c o o r d i n a t e s u c h t h a t t h e fM-(N-N) 2~M'f (M=B o r Ga, M' = t r a n s i t i o n m e t a l ) s i x membered r i n g f o r m s a w e l l d e f i n e d b o a t . I n a n a l o g o u s m o l e c u l e s t h e 'Ga-N' bonds (-2.0 i£) a r e l o n g e r t h a n t h e r e l a t e d 'B-N' (-1.5 X) s e p a r a t i o n s . The r e s u l t o f t h i s i s a n e a r s y m m e t r i c b o a t f o r t h e c a s e when M=Ga ( F i g . 7a) and an un s y m m e t r i c b o a t when M=B ( F i g . 7 b ) . F i g u r e 7. R e l a t i v e bond d i s t a n c e s i n fM-(N-N) 2~M'} when M=Ga (a) and B ( b ) . The l o n g e r 'Ga-N' bonds i n c r e a s e s t e r i c c r o w d i n g a r o u n d t h e t r a n s i t i o n m e t a l and i n c e r t a i n c a s e s t h i s a d d i t i o n a l s t e r i c p r o t e c t i o n o f M' i s b e l i e v e d t o s t a b i l i z e m o l e c u l e s i n c o r p o r a t -i n g t h e b i s ( 1 - p y r a z o l y l ) g a l l a t e l i g a n d . I n a d d i t i o n , p y r a z o -l y l g a l l a t e l i g a n d s a r e b e t t e r e l e c t r o n d o n o r s t h a n t h e i r b o r o n - 17 -c o u n t e r p a r t s , g a l l i u m (1.82) b e i n g l e s s e l e c t r o n e g a t i v e t h a n b o r o n (2.01) [ ( ) = A l l r e d - R o c h o w e l e c t r o n e g a t i v i t y ] . N a + [ M e 2 G a ( p z ) 2 ] ~ r e a c t e d w i t h [ R e ( C O ) 4 C l ] 2 t o f o r m t h e u n s t a b l e t e t r a c a r b o n y l c o m p l e x , [ M e 2 G a ( p z ) 2 ] R e ( C O ) 4 . S u c h t e t r a c a r b o n y l s p e c i e s w e r e n o t o b s e r v e d when t h i s same l i g a n d was r e a c t e d w i t h M n ( C O ) ^ B r (33) o r i n s i m i l a r p y r a z o l y l b o r a t e s y s t e m s ( 5 0 ) . [ M e 2 G a ( p z ) 2 ] R e ( C O ) 4 r e a c t e d r e a d i l y w i t h t r i p h e n y l p h o s -p h i n e o r p y r a z o l e , y i e l d i n g a i r s t a b l e p r o d u c t s o f t h e f o r m [ M e 2 G a ( p z ) 2 ] R e ( C O ) 3 X ( X = P P h 3 o r p z H ) . When t h e a b o v e r e a c t i o n s w e r e c a r r i e d o u t w i t h t h e more s t e r i c a l l y d e m a n d i n g [ M e 2 G a ( p z " ) 2 ] l i g a n d , d i f f i c u l t y was e n -c o u n t e r e d i n i s o l a t i n g p u r e p r o d u c t s . I t i s p r o p o s e d t h a t i n t e r -f e r e n c e b e t w e e n t h e m e t h y l s u b s t i t u e n t s a t t h e C ( 3 ) p o s i t i o n s o f th e . p y r a z o l y l g r o u p s a n d t h e 'X' m o i e t y d e s t a b i l i z e t h e [ M e 2 G a ( p z " ) 2 ] R e ( C O ) 3 X (X=PPh 3 o r pzH) c o m p l e x e s . N o v e l u n s y m m e t r i c b i d e n t a t e m o n o ( 1 - p y r a z o l y l ) g a l l a t e l i g a n d s , w h i c h h a v e no c o u n t e r p a r t i n p y r a z o l y l b o r a t e c h e m i s t r y , w e r e p r e p a r e d by t h e r e a c t i o n o f s o d i u m p y r a z o l i d e o r s o d i u m 3,5 d i m e t h y l p y r a z o l i d e and d i m e t h y l g a l l i u m h y d r o x i d e as f o l l o w s ; r "1 TH F 4Na+(C3HN2R2)- + |Me2Ga(OH)J4 > 4Na+ R = H or Me - 18 -These bidentate l i g a n d s reacted w i t h [ R e ( C O ) 4 C l ] 2 and octahedral rhenium t e t r a c a r b o n y l complexes have been i s o l a t e d . In these species i t was again found t h a t one CO group was extremely l a b i l e and s t a b l e products could be obtained by d i s p l a c i n g t h i s l a b i l e CO group with"PPh^. Molecules i n c o r p o r a t i n g the [Me 2Ga(C 3HN 2R 2)(OH)]~ (R~H or Me) l i g a n d s , u n l i k e those c o n t a i n i n g b i s p y r a z o l y l g a l l a t e c h e l a t e s , are not constra i n e d to a boat conformation i n the s o l i d s t a t e . "*"H nmr data i n s t e a d i n d i c a t e t h a t these unsymmetric l i g a n d s remain approximately planar when coordinated to a Re(I) c e n t r e . Thus the b r i d g i n g p y r a z o l y l g r o u p . l i e s i n the plane formed by the f Ga- (N-N) -Re-Oj- f ive-membered r i n g as shown below. Me,Ga I \ 1 / (M = Re) Figur e 8. Coordination geometry of the unsymmetric [Me 2Ga(C 3HN 2R 2)(OH)] l i g a n d s . By u t i l i z i n g a s i m i l a r type of r e a c t i o n sequence to tha t used f o r the pr e p a r a t i o n of the mono (1-pyrazolyl) hydroxo.gallate l i g a n d s , an unsymmetric bidentate phosphino l i g a n d has been synthesized and reacted w i t h [Re(CO) 4C1] 2. The product, [Me2Ga (pz) (PPh 2)]Re(CO) 4, d i d not r e a c t smoothly w i t h PPh 3. I t i s proposed t h a t t h i s i s a d i r e c t consequence of the s i z e of the phosphino bri d g e . P a r t s of t h i s chapter have been p r e v i o u s l y described (51). - 19 -2.2 E x p e r i m e n t a l 2.2.1 S t a r t i n g M a t e r i a l s P y r a z o l e and 3,5 d i m e t h y l p y r a z o l e (K andi\K) , t r i p h e n y l p h o s -p h i n e (MCB) and d i p h e n y l p h o s p h i n e (Strem) were u s e d as s u p p l i e d . The b i d e n t a t e l i g a n d s N a + [ M e 2 G a ( C 3 H N 2 R 2 ) 2 ] ~ (R=H o r Me) were p r e p a r e d as d e s c r i b e d i n t h e l i t e r a t u r e ( 1 6 ) . O c t a c a r b o n y l -d i - p - c h l o r o d i r h e n i u m was p r e p a r e d f r o m d e c a c a r b o n y l d i r h e n i u m (Strem) and c h l o r i n e gas (Matheson) ( 5 2 ) . 2.2.2 P r e p a r a t i o n o f [ M e 2 G a ( C 3 H N 2 R 2 ) 2 ] R e ( C O ) . (R=H o r Me) I n a t y p i c a l p r e p a r a t i o n two m o l a r e q u i v a l e n t s o f l i g a n d were added t o [ R e ( C O ) 4 C 1 ] 2 (1.00 g) d i s s o l v e d i n 100 ml THF. The r e s u l t i n g r e a c t i o n m i x t u r e was s t i r r e d o v e r n i g h t and t h e THF s u b s e q u e n t l y removed i n vwcuo. The r e m a i n i n g o f f - w h i t e r e s i d u e was e x t r a c t e d i n t o b e n z e n e and f i l t e r e d . E v a p o r a t i o n o f b e n z e n e r e s u l t e d i n a t a c k y , a i r s e n s i t i v e , p a l e y e l l o w s o l i d w h i c h c o u l d o n l y be s o l i d i f i e d by pumping £n •vmQU.Q. f o r s e v e r a l d a y s . Y i e l d 60-70%. S e l e c t e d p h y s i c a l d a t a a r e summarized i n T a b l e I . 2.2.3 P r e p a r a t i o n o f [Me G a ( e ? H N R ) ] R e ( C O ) ? X N 2 R 2 ) 2 ] + [ R e ( C O ) 4 C l ] 2 2 [ M e 2 G a ( C 3 H N 2 R 2 ) 2 ] R e ( C O ) 4 + THF 2NaCl (R=H o r Me; X^PPh-, o r pzH) [Me 2Ga ( C 3 H N 2 R 2 ) 2*]iRe (CO) 4 + •X THF [ M e 2 G a ( C 3 H N 2 R 2 ) 2 ] R e ( C O ) 3 X + CO F o r t h e s e r e a c t i o n s [Me„Ga(C HN R_) ] R e ( C O ) . was n o t Table -I. P h y s i c a l Data f o r x0>n? Ga Re' Me' \ / | \ R An a l y s i s Found (%)/Cal'd(%) H N v c o ( c m _ 1 ) cyclohexane (Nujol) H nmr i n C^Dg x(ppm) -GaMe, R H H C O 28 .48 o i. .90 10 .98 2028,1933,1919,1905 10.02s 2 .10d 3 .83t 27 .86 2 .43 10.32+ (2028,1911br) b 10.04s 2 .53d H PPh-, 45 .16 3 .71 7.17 2031,1937,1908 9 .87s 2 .60d 4 .27t 2 .88m j 45 .44 3 .53 7.31 (2022,1900br) 9 .89s 2 .69d 3 .07m H pzH 29 .35 2 .79 14 .52 2030,1926,1912 9.70s 2.56dd 4 .05t 3 .10m 29 .38 2 .80 14 .69 (2022,1915br ,v M 1 I3378) 9.94s 2.65dd 4 ,33m IN r l 4.71m 1.81br(N Me C O 31 .29 3 .82 9 .21 a 2026,1922,1910,1906 sample unstable i n s o l u t i o n 32 .66 3 .40 9.53 (2018 ,1910br,1893br) Me P P h 0 47 .32 4 .14 5.95 2021,1911,1899 10.06s 8 .03s 4 .30s 2 .69m 48 .18 4 .26 6 .81 (2021,1924br,1901br) 10.10s 8 .37s 3 .01m Me pzH 33 .69 3 .71 13.22 2024,1920,1908,1902 see d i s c u s s i o n 34 .40 3 .82 13.38 (202 0br,1916br,1900br v N R 3 3 7 5 ) + a t C 6 H 6 2.84 ppm; s = s i n g l e t , d = d o u b l e t ( J ^ 2Hz) , t = t r i p l e t ( J ^ 2Hz) , dd = d o u b l e t o f d o u b l e t s , m = m u l t i p l e t c a l c ' d w i t h .15 THF sample a p p e a r e d t o be decomposing b r = b r o a d - 21 -i s o l a t e d b u t was i n s t e a d p r e p a r e d in s i t u as d e s c r i b e d i n s e c t i o n 2.2.2. A s s u m i n g a 100% y i e l d , one m o l a r e q u i v a l e n t o f 'X' d i s s o l v e d i n THF was added and t h e r e s u l t a n t s o l u t i o n s t i r r e d f o r 12 h. THF was t h e n removed in vacuo and t h e r e m a i n i n g r e s i d u e e x t r a c t e d i n t o b e n z e n e and f i l t e r e d . E v a p o r a t i o n o f b e n z e n e y i e l d e d a s t i c k y s o l i d f r o m w h i c h e x c e s s 'X' was removed by s u b l i m a t i o n in vacuo. F o r t h e c a s e where (R=H, X = P P h 3 ) , t h e p r o d u c t was r e e r y s t a l l i z e d f r o m h e p t a n e / b e n z e n e as a i r s t a b l e , c o l o u r l e s s p r i s m s i n q u a n t i t a t i v e y i e l d . When (R=H, X=pzH) a t t e m p t s a t c r y s t a l l i z a t i o n were n o t s u c c e s s f u l and t h e p r o d u c t was i s o l a t e d as an a i r s t a b l e , w h i t e powder i n q u a n t i t a t i v e y i e l d . However, t h e p r o d u c t s where (R=Me, X=PPh 3 o r pzH) c o u l d o n l y be s o l i d i f i e d by d r y i n g in vacuo f o r s e v e r a l d a y s a t 5 0 ° . A l t h o u g h m o d e r a t e l y a i r s t a b l e as s o l i d s , t h e y q u i c k l y decom-p o s e d i n s o l u t i o n on e x p o s u r e t o a i r . P h y s i c a l d a t a f o r t h e s e c o m p l e x e s a r e i n c l u d e d i n T a b l e I . 2.2.4 P r e p a r a t i o n o f t h e L i g a n d s N a + [ M e » G a ( C 0 H N _ R _ ) ( O H ) ] ~ ,—^ J zJ—zJ (R=H o r Me) ~0° i ) 4Me 3Ga + e x H 2 0 E t 0 ' [ M e 2 G a ( O H ) ] 4 + 4CH 4 i i ) [ M e 2 G a ( O H ) ] 4 + 4 N a + ( C 3 H N 2 R 2 ) " — T H F > 4 N a + [ M e 2 G a ( C ^ H N ^ ) ' (OH)' ] ~ I n a t y p i c a l p r e p a r a t i o n t r i m e t h y l g a l l i u m (3.24 g, 28.2 mmol) i n ~20 ml d i e t h y l e t h e r was added d r o p w i s e t o 100 ml o f H 2 0 h e l d a t 0 ° , r e s u l t i n g i n t h e i m m e d i a t e p r e c i p i t a t i o n o f a w h i t e s o l i d . The r e a c t i o n m i x t u r e was s t i r r e d f o r 15 min and t h e n e x t r a c t e d f i v e t i m e s w i t h d i e t h y l e t h e r . The e t h e r e x t r a c -t i o n s were combined and t h e e t h e r removed in vacuo l e a v i n g a - 22 -w h i t e , sweet s m e l l i n g s o l i d (2.53 g, 78% y i e l d ) . T h i s s o l i d , [ M e 2 G a ( O H ) ] 4 , was r e c r y s t a l l i z e d f r o m p e t r o l e u m e t h e r and d r i e d in vacuo f o r 24 h. [ M e 2 G a ( O H ) ] 4 (.905 g, 1.938 mmol) d i s s o l v e d i n 50 ml THF, and s o d i u m p y r a z o l i d e (.698 g, 7.755 mmol) d i s s o l v e d i n t h e same s o l v e n t , were combined and s t i r r e d t o g e t h e r o v e r n i g h t . [ R e f l u x t e m p e r a t u r e s r e s u l t i n t h e p r e c i p i t a t i o n o f t h e i n s o l u b l e p o l y m e r (MeGaO) ].'. The c l e a r , c o l o u r l e s s s o l u t i o n was d i l u t e d t o 250.0 ml THF i n a v o l u m e t r i c f l a s k . 2.2.5 . P r e p a r a t i o n " o f " [\Me2Ga4G3HN^R2))n((OH), ] RelftCO) ^  (R=H o r Me) N a + [ M e 2 G a ( C 3 H N 2 R 2 ) ( O H ) ] ~ + h[Re(CO)4C1] T H F > [Me 2Ga ( C 3 H N 2 R 2 ) (OH) ]Re (CO) [ 4 + N a C l Two m o l a r e q u i v a l e n t s o f t h e a p p r o p r i a t e l i g a n d were added t o [ R e ( C O ) 4 C l ] 2 d i s s o l v e d i n THF and t h e r e s u l t a n t r e a c t i o n m i x t u r e s t i r r e d o v e r n i g h t . The THF was removed in vacuo and t h e r e m a i n i n g r e s i d u e r e d i s s o l v e d i n C H 2 C 1 2 and f i l t e r e d . E v a p o r a t i o n o f t h e s o l v e n t r e s u l t e d i n s l i g h t l y s t i c k y , a i r s e n s i t i v e , o f f -w h i t e s o l i d s . P h y s i c a l d a t a a r e t a b u l a t e d i n T a b l e I I . 2.2.6 P r e p a r a t i o n o f [Me 2Ga (C-^H^Rp) (OH) ] Re (CO) 3 (PPh-,) (R=H o r Me) [Me 2Ga ( C 3 H N 2 R 2 ) (OH) ]Re (CO) 4 + P P h 3 —^L*. [Me 2Ga ( C 3 H N 2 R 2 ) (OH) ]Re (CO) 3 (PPh 3) + CO To a s u s p e n s i o n o f [ M e 2 G a ( C 3 H N 2 R 2 ) ( O H ) ] R e ( C O ) 4 i n THF, one m o l a r e q u i v a l e n t o f P P h 3 d i s s o l v e d i n THF was added and t h e r e s u l t i n g m i x t u r e r e f l u x e d o v e r n i g h t . Removal o f t h e s o l v e n t T a b l e I I . P h y s i c a l D a t a f o r M e R<0> N K Ga R 0 Re' CO M e H R X A n a l y s i s F o u n d ( % ) / C a l ' d ( % ) H N v c o ( c m 1 ) c y c l o h e x a n e ( N u j o l ) vOH (cm-1) N u j o l "H nmr , x (ppm) -GaMe. R H OH H CO 22 .40 2 .25 6 .01 2037,1930,1920,1912 n o t s o l u b l e 22.41 2 .08 5 .81 ( 2 0 1 0 b r , 1 8 7 0 b r ) a 3570 H PPh-, 43.23 3 .31 3 .28 2030,1934,1899 10. l i s u n d e r 4 . l i t 10 * . 29s j 43.58 3 .49 3 .91 ( 2 0 2 5 , 1 9 3 2 b r , 1 8 9 5 b r ) 3600 10. 60s P P h 3 Me CO 27.79 3 .44 5 .87 2030,1917,1904 10. 39s 7.14s 4.00s 9 . 5 3 s + + 27 .27 3 .03 5 . 30+ ( 2 0 0 0 b r , 1 8 7 5 b r ) 3580 7.68s Me PPh-, 45.63 3 .69 3 .17 2028,1932,1894 3595 10 . 07s 7.98s 4.42s 10 * .29s 45.17 3 .90 3 .76 ( 2 0 2 8 , 1 9 3 0 b r , 1 8 9 2 b r ) 10. 60s 8 ,15s m e a s u r e d i n C^Dg, TC^E^ = 2.84 ppm; s = s i n g l e t , t = t r i p l e t ( J ^  2Hz) m e a s u r e d i n ( C D 3 ) 2 C O , T ( C H 3 ) 2 C O = 7.89 ppm c a l ' d w i t h .25 T H F b r = b r o a d - 24 -in vacuo l e f t a p a l e y e l l o w r e s i d u e . The p r o d u c t s were s o l i d i f i e d by pumping in vacuo f o r 15 h. Y i e l d s ~50-60%. P h y s i c a l d a t a a r e i n c l u d e d i n T a b l e I I . 2.2.7 P r e p a r a t i o n o f [Me^Ga(pz) (PPh,,)]Re(CO)^ THF i ) Me 3Ga + P h 2 P H — — • M e 3 G a : P h 2 P H i i ) Me 3Ga-Ph 2PH + Napz — ™ F > N a + [ M e 2 G a (pz))i,(PPh^) ] " + C H 4 i i i ) 2Na +[Me 2Ga(pzi)i.(PPh 2) ] " ' + [ R e ( C O ) 4 C l ] 2 : — 2 [Me 2Ga (pzJ)i.(PPh 2) ]Re (CO) 4 + 2NaCl D i p h e n y l p h o s p h i n e (.228 g,,1.22 mmol) i n THF was a d d e d d r o p w i s e t o a - s t i r r e d / s o l u t i o n o f t r i m e t h y l g a l l i u m (.141 g, 1.23 mmol) a l s o i n THF. A f t e r s t i r r i n g f o r 1 h s o d i u m p y r a z o l i d e (.110 g, 1.22 mmol); d i s s o l v e d i n THF was added and t h e r e s u l t a n t s o l u t i o n r e f l u x e d f o r 2 h. T o t a l volume -125 m l . [ R e ( C O ) 4 C l ] 2 (.409 g, .612 mmol) d i s s o l v e d i n THF was added and t h e r e a c t i o n m i x t u r e s t i r r e d f o r an a d d i t i o n a l 12 h. The THF was removed in vacuo and t h e r e m a i n i n g r e s i d u e e x t r a c t e d i n t o a minimum amount o f b e n z e n e . E v a p o r a t i o n o f s o l v e n t f r o m t h e f i l t e r e d e x t r a c t s r e s u l t e d i n a p a l e y e l l o w g l a s s t h a t c o u l d be s c r a p e d i n t o a powder. A n a l . C a l c d . f o r [ M e 2 G a ( p z ) ( P P h 2 ) ] R e ( C O ) 4 : C,38.75; H,2.95; N,4.31. F o u n d : C,37.98; H,2.91; N,4.10. v c o ( c m - 1 ) : 2010 b r , 1932 b r , 1903 b r ( C H 2 C 1 2 ) . 1 H nmr ( T , C 6 D 6 ) : -GaMe 2 , 9 . 97s ; p z - 4 H , 3 . 9 7 1 ( J ~ 2 H z ) ; p z - 3 H , p z - 5 H , "PPh 2,-2.11-3.15m. - 25 -2 . 3 R e s u l t s and D i s c u s s i o n 2.3.1 [ Me 2Ga ( C 3 H N 2 R 2 ) J Re (CO) ^  (R=H o r Me) The d i m e t h y l b i s ( 1 - p y r a z o l y l ) g a l l a t e b i d e n t a t e l i g a n d s r e a c t e d w i t h [ R e ( C O ) 4 C l ] 2 f o r m i n g u n s t a b l e c i s t e t r a c a r b o n y l c o m p l e x e s . The monomeric n a t u r e o f t h e R=H p r o d u c t was c o n f i r m e d by mass s p e c t r a l a n a l y s i s . The l a r g e s t m/e s i g n a l ( T a b l e I I I ) was a t t r i b u t a b l e t o t h e p a r e n t i o n , [Me,,Ga (pz) 2 ] R e (CO) 4 + , minus one c a r b o n y l and a s i n g l e m e t h y l g r o u p . L a r g e s i g n a l s were a l s o a s s i g n a b l e c o r r e s p o n d i n g t o t h e s u c c e s s i v e l o s s o f f o u r c a r b o n y l s f r o m e i t h e r t h e p a r e n t i o n o r t h e p a r e n t i o n minus one m e t h y l . I n a d d i t i o n t o t h e d e s i r e d p r o d u c t , t h e mass s p e c t r u m i n d i c a t e d t h e p r e s e n c e o f [ M e G a ( p z ) 3 ] R e ( C O ) 3 as a m i n o r p r o d u c t . The o c c u r r e n c e o f [ M e G a ( p z ) 3 ] R e ( C O ) 3 ( l a t e r s y n t h e s i z e d by a more d i r e c t r o u t e , s e e s e c t i o n 3.2.2) as a m i n o r p r o d u c t was n o t e n t i r e l y u n e x p e c t e d a s s i m i l a r r e s u l t s have b e e n o b s e r v e d i n a n a l o g o u s ' s y s t e m s . When t h e d i h y d r o b i s ( 1 - p y r a z o l y l ) b o r a t e a n i o n , [H. B ( p z ) 2 ] ~ , was r e a c t e d w i t h M ( C O ) 5 B r (M=Mn o r Re) a t room t e m p e r a t u r e , none o f t h e e x p e c t e d t e t r a c a r b o n y l p r o d u c t was o b s e r v e d . I n s t e a d [ H 2 B ( p z ) 2 ] M ( C O ) 3 ( p z H ) (M=Mn o r Re) was i s o -l a t e d i n -35% y i e l d s a l o n g w i t h t h e c o r r e s p o n d i n g c a r b o n y l M 2 ( C O ) 1 0 . F u r t h e r m o r e when [ H 2 B ( p z ) 2 ] M n ( C O ) 3 ( p z H ) w a s . r e f l u x e d i n THF f o r 24 h an i n t e r n a l c o n d e n s a t i o n r e a c t i o n t o o k p l a c e , r e s u l t i n g d n [ H B ( p z ) 3 ] M n ( C O ) 3 ( 5 0 ) . A l s o when [ M e 2 G a ( p z ) 2 J was s t i r r e d w i t h Mn(CO)^Br i n t h e a b s e n c e o f p y r a z o l e , [ M e 2 G a ( p z ) 2 ] M n ( C O ) 3 ( p z H ) was i s o l a t e d i n low y i e l d . A g a i n no e v i d e n c e o f a manganese t e t r a c a r b o n y l p r o d u c t was o b s e r v e d ( 3 3 ) . - 26 -T a b l e i l l . Mass S p e c t r a l D a t a o f [Me 2Ga (pz) 2 ] Re (CO) 4 = P m/e A s s i g n m e n t I n t e n s i t y 556 [ M e G a ( p z ) 3 ] R e ( C O ) 3 + 9.3 530 P + 2.5 528 [ M e G a ( p z ) 3 ] R e ( C O ) 2 + 4.2 504 P - C 0 + 33.9 500 [ M e G a ( p z ) 3 ] R e ( C 0 ) + 3.8 489 P-C0-Me + 100.0 472 [ M e G a ( p z ) 3 ] R e + 19.1 461 P-2CO-Me + 8.1 433 P-3CO-Me + 47.9 420 P-4CO + 27.5 405 P-4CO-Me + 35.2 319 [ M e 2 G a ( p z ) ] 2 - M e + 89.5 J99 M e 2 G a + 62.0 69 G a + 99.1 ,.68 p z H + 40.7 c a l c u l a t e d w i t h Ga and Re - 27 -The i n c l u s i o n o f m e t h y l g r o u p s a t t h e C(3) and C(5) p o s i t i o n s o f t h e p y r a z o l y l r i n g s d i d n o t n o t i c e a b l y s t a b i l i z e t h e r h e n i u m t e t r a c a r b o n y l c o m p l e x as h o p e d . I n s t e a d an e x t r e m e l y a i r s e n s i -t i v e p r o d u c t was i s o l a t e d whose mass s p e c t r u m d i s p l a y e d many weak p e a k s w h i c h c o u l d n o t be a s s i g n e d . However t i t h e s s t r o n g e s t m/e s i g n a l s were a t t r i b u t a b l e t o i o n s r e s u l t i n g f r o m t h e s u c c e s -s i v e l o s s o f c a r b o n y l g r o u p s f r o m t h e d e s i r e d p r o d u c t , The s o l u t i o n IR s p e c t r a o f t h e t e t r a c a r b o n y l c o m p l e x e s d i s p l a y e d f o u r bands between -1900-2030 cm ( s e e T a b l e I) , i n a g r e e m e n t w i t h t h e s p e c t r u m e x p e c t e d f o r a m o l e c u l e c o n t a i n i n g a b i d e n t a t e l i g a n d ( 5 3 ) . I t has p r e v i o u s l y been m e n t i o n e d t h a t t r a n s i t i o n m e t a l com-p l e x e s c o n t a i n i n g b i s p y r a z o l y l g a l l a t e l i g a n d s p r e f e r t o c r y s t a l -l i z e i n a b o a t f o r m as a r e s u l t o f a c o m b i n a t i o n o f e l e c t r o n i c and s t e r i c f a c t o r s . S u ch a c o n f o r m a t i o n p l a c e s t h e two g a l l i u m m e t h y l s u b s t i t u e n t s on t h e p r e s e n t m o l e c u l e s i n i n e q u i v a l e n t s t r u c t u r a l e n v i r o n m e n t s . [ M e 2 G a ( p z " ) 2 ] R e ( C O ) F i g u r e 9. B o a t c o n f o r m a t i o n o f [Me 2Ga (pz), 2 ] Re (CO) - 28 -Thus t h e H nmr s p e c t r u m o f [ M e 2 G a ( p z ) 2 ] R e ( C O ) 4 c o n t a i n s two s i n g l e t s o f e q u a l i n t e n s i t y i n t h e 'GaMe' r e g i o n ( T a b l e 1 ) . Note t h a t i n a p l a n a r -pGa- (N-N) 2 - R e ^ " a r r a n g e m e n t t h e Ga-Me 2 g r o u p s a r e s t r u c t u r a l l y e q u i v a l e n t . I t was n o t p o s s i b l e t o o b t a i n a c l e a n nmr s p e c t r u m o f [ M e 2 G a ( p z " ) 2 ] R e ( C O ) 4 as t h e complex was u n s t a b l e i n s o l u t i o n . F r e s h l y p r e p a r e d s o l u t i o n s o f t h i s compound c o n t a i n e d s m a l l "^H nmr s i g n a l s a s s i g n a b l e t o t h e known s t a b l e d i m e r [Me,,Ga ( y - p z " ) ] 2 ( 2 9 ) . As t h i s sample was a l l o w e d t o s i t a t room t e m p e r a t u r e t h e s i g n a l s due t o t h e g a l l i u m d i m e r g r a d u a l l y i n c r e a s e d i n i n t e n s i t y w h i l e t h o s e due t o t h e r h e n i u m complex d e c r e a s e d , i n d i c a t i n g t h a t d i s p r o p o r t i o n a t i o n o f [ M e 2 G a ( p z " ) 2 ] R e ( C O ) 4 was o c c u r r i n g i n s o l u t i o n . 2.3.2 [ M e 2 G a ( C 3 H N 2 R 2 ) 2 ] R e (CO) X (R=H o r Me; X^PPhu o r D i m e t h y l b i s ( 1 - p y r a z o l y l ) g a l l a t e r h e n i u m t e t r a c a r b o n y l r e a c t e d r e a d i l y with.'PPh^ o r p y r a z o l e d i s p l a c i n g one c a r b o n y l g r o u p . The a i r s t a b l e s u b s t i t u t e d p r o d u c t s f o r m e d i n h i g h y i e l d . The s o l u t i o n IR s p e c t r a o f t h e s e c o m p l e x e s c o n t a i n e d t h r e e s h a r p bands i n t h e c a r b o n y l r e g i o n , i n d i c a t i v e o f f a c i a l c o o r d i -n a t i o n o f t h e t h r e e r e m a i n i n g c a r b o n y l g r o u p s . [ M e r i d i o n a l c o o r d i n a t i o n o f t h e CO l i g a n d s w o u l d e x h i b i t two weak and one s t r o n g vCO bands. (53)'..']'. The N u j o l s p e c t r u m and CO s o l u t i o n s e g -mentenfOvG' t h e complex where R=H, X=pzH a r e shown i n F i g . 10. I n t h e N u j o l s p e c t r u m t h e 'N-H' band o f t h e s i n g l e t e r m i n a l l y c o o r d i n a t e d p y r a z o l e g r o u p i s c l e a r l y v i s i b l e a t 3378 cm ^. A l s o i d e n t i f i a b l e a r e weak bands c h a r a c t e r i s t i c o f vGa-C s t r e t c h i n g - 30 -v i b r a t i o n s between -500-600 cm and weak bands -600 w h i c h a r e a s s o c i a t e d w i t h p y r a z o l y l r i n g modes ( 5 4 ) . To r e t a i n f a c i a l o r i e n t a t i o n o f t h e c a r b o n y l g r o u p s s u b -s t i t u t i o n must o c c u r a t one o f t h e a x i a l p o s i t i o n s on t h e r h e n i u m , ji.fe. ( a ) o o r (d)) i n F i g . 9. I n f a c t f r o m t r a n s e f f e c t a r g u m e n t s a h e a r b o h y i h y l i g a n d p t r a n s t o a n o t h e r c a r b o n y l w o u l d be e x p e c t e d t o be more l a b i l e t h a n one o p p o s i t e a p y r a z o l y l n i t r o g e n , as p y r a z o l e i s a weak i r - a c c e p t o r compared t o c a r b o n monoxide. hmrudatau-are' i n ; a g r e e m e n t w i t h a f a c i a l c a r b o n y l a r r a n g e r , ment. I f s u b s t i t u t i o n were t o o c c u r a t one o f t h e p o s i t i o n s t r a n s t o a r i n g n i t r o g e n , t h e two p y r a z o l y l g r o u p s w o u l d become s t r u c t u r a l l y i n e q u i v a l e n t . The "*"H nmr s p e c t r a o f [ M e 2 G a ( p z ) 2 ] R e ( C O ) 3 ( X ) (X=PPh 3 o r pzH) e x h i b i t o n l y one s e t o f r e s o n a n c e s a t t r i b u t a b l e t o t h e p y r a z o l y l b r i d g e s [ F i g s . 12, 1 3 ( a ) ] . I n a d d i t i o n b o t h s p e c t r a d i s p l a y two g a l l i u m m e t h y l s i n g l e t s o f a p p r o x i m a t e l y e q u a l i n t e n s i t y , c o n s i s t e n t w i t h a b o a t c o n f o r m a -t i o n and r u l i n g o u t t h e p o s s i b i l i t y o f a . p l a n a r b i s p y r a z o l y l g a l -l a t e l i g a n d i n s o l u t i o n . -800 cm , 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 o f [ M e 2 G a ( p z ) 2 ] R e ( C O ) 3 (PPh 3) has c o n f i r m e d t h e s t e r e o c h e m i s t r y as s u g g e s t e d by s p e c t r a l d a t a . The P P h 3 i s c o o r d i n a t e d i n t h e a x i a l p o s i t i o n , on t h e same s i d e o f t h e r h e n i u m as t h e 'bottom o f t h e b o a t ' . M o l e c u l a r m o d e l s s u g g e s t t h a t i f t h i s b u l k y p h o s p h i n e were, t o c o o r d i n a t e i n t h e a l t e r n a t i v e a x i a l p o s i t i o n , i n t e r a c t i o n w i t h - 31 -Figurezll. t h e p s e u d o a x i a l m e t h y l g r o u p on t h e g a l l i u m atom w o u l d o c c u r . I n F i g . II t h e f a c i a l a r r a n g e m e n t o f t h e t h r e e r e m a i n i n g c o o r d i -n a t e d c a r b o n y l s i s c l e a r l y e v i d e n t . I n t h e "'"H nmr s p e c t r u m o f [Me 2Ga (pz) 2 ] Re (CO) ^ (pzH) , t h e b r i d g i n g p y r a z o l y l g r o u p s and t e r m i n a l p y r a z o l e show a d d i t i o n a l c o u p l i n g above t h e e x p e c t e d J ^ ^ ^ i n t e r a c t i o n . F i g . 13(b) i s t h e e x panded p y r a z o l y l / p y r a z o l e r e g i o n (~T2.4-4.8) o f t h e '''H nmr s p e c t r u m o f t h i s compound. F i g . 1 3 ( c ) i s a n e a r i d e n t i c a l c o mputer s i m u l a t e d s p e c t r u m b a s e d upon t h e p a r a m e t e r s g i v e n i n T a b l e IV. I n e a c h o f t h e p y r a z o l y l and p y r a z o l e groups c r o s s r i n g c o u p l i n g , n o t r u s u a l l y d e t e c t a b l e , i s o c c u r r i n g between t h e h y d r o g e n s l o c a t e d a t t h e C(3) and C(5) r i n g p o s i t i o n s . W i t h i n t h e t e r m i n a l l y c o o r d i n a t e d p y r a z o l e an a d d i t i o n a l weak c o u p l i n g b etween t h e t h r e e r i n g p r o t o n s and t h e 1N-H' p r o t o n i s o b s e r v e d . 1,1,1,1,1,1 I . I , i, u t i i i i i x , ! .i.i.i.i.i.i.i.i, i, u 1111 n J ,i ,i .I.I.I.I.I, i, i, u i i i n i i i M i ,1.1.1.1,1.1.1. m i n i ) ) 1,1,1,111 U i, 2 3 4 5 6 7 8 9 10 T F i g u r e 12. Room t e m p e r a t u r e 100 MHz ''"H nmr s p e c t r u m o f [ M e 2 G a ( p z ) 2 ] R e ( C O ) 3 ( P P h 3 ) i n CgDg. I I I I I I I I I I I I I I I I n i I i i I i i i i I i i i i I i i i i I i i i i i i i . i I i t i i i t i • . ^ n F f f t i • i i « i i • t «.« 1 1 1 I f f f f-J.'.'.V1 2 3 4 5 6 7 I J 9 10 F i g u r e 13 (a) . Room t e m p e r a t u r e 100 MHz ''"H nmr s p e c t r u m o f [ M e 0 G a ( p z ) - ] R e ( C O ) ^ ( p z H ) i n C , D f i . - 34 -(b) J V. (c) F i g u r e 13(b) E x p anded p y r a z o l y l / p y r a z o l e r e g i o n o f t h e s p e c t r u m shown i n F i g . 1 3 ( a ) . F i g u r e 13(c) Computer s i m u l a t i o n o f F i g . 13(b) u s i n g t h e d a t a g i v e n i n T a b l e IV. - 35 -H. H H 2.56 4 .05 2.65 4.33 4.71 3 .10 J 3 4 = 2 . 1 , J 3 5 = 0 . 5 J 4 3 = J 4 5 = 2 - 1 J 5 3 = 0 . 5 , J 5 4 = 2 . 1 J a b = 2 ' 4 ' J a c = 0 - 6 ' J a x = L 5 J, =2.4, J, =J. =2.3 ba bc bx J =0.6, J ,=J =2.3 c a c b c x H (1.81) m e a s u r e d i n C,D, s o l u t i o n a t room t e m p e r a t u r e b b TCgHg = 2.84 ppm n o t i n c l u d e d i n F i g u r e s 13(b) and ( c ) . - 36 -[ M e 2 G a ( p z " ) 2 ] R e ( C O ) 3 ( P P h 3 ) was i s o l a t e d as a p a l e y e l l o w , s t i c k y s o l i d i n low y i e l d . I t i s c o n j e c t u r e d t h a t s t e r i c f a c t o r s c o u l d be an i m p o r t a n t c o n t r i b u t i o n t o t h e o b s e r v e d i n s t a b i l i t y o f t h i s compound. "'"H nmr and IR s p e c t r a l d a t a s u p -p o r t t h e h y p o t h e s e s t h a t t h e p h o s p h i n e i s c o o r d i n a t i n g a t an a x i a l p o s i t i o n o f [ M e 2 G a ( p z " ) 2 ] R e ( C O ) 4 , [ i . e . (a) o r (d) i n F i g . 9, s e e T a b l e I ] . I n a r i g i d m o l e c u l e t h e m e t h y l g r o u p s a t t h e C(3) p o s i t i o n s o f t h e p y r a z o l y l b r i d g e s may p r e v e n t t h e P P h 3 f r o m a p p r o a c h i n g t h e r h e n i u m a t p o s i t i o n (c(a) . I n a d d i t i o n , o nce t h e m e t a t h e s i s r e a c t i o n i s c o m p l e t e , s t e r i c i n t e r f e r e n c e between a h b u l k y P P ^ 3 a t s i t e (a) and t h e s e p y r a z o l y l m e t h y l s u b s t i t u e n t s w i l l c o n t i n u e t o have a d e s t a b i l i z i n g e f f e c t on t h e p r o d u c t . The r e a c t i o n o f [Me 2Ga ( p z " )) 2 ] Re (CO) 4 w i t h pzH r e s u l t e d i n a s o l i d w h i c h a n a l y z e d c o r r e c t l y f o r t h e d e s i r e d s p e c i e s , [ M e 2 G a ( p z " ) 2 ] R e ( C O ) 3 ( p z H ) . However t h e CO bands i n t h e N u j o l IR s p e c t r u m o f t h i s compound a p p e a r e d t o be b r o a d e n e d and i n C_H b LZ an e x t r a CO band a t 1908 cm was e v i d e n t . The "*"H nmr s p e c t r u m o f t h e same r e a c t i o n p r o d u c t was i n i -t i a l l y n o t e a s i l y i n t e r p r e t a b l e , c o n t a i n i n g more, s i g n a l s t h a n e x p e c t e d f o r a s i m p l e f a c i a l l y c o o r d i n a t e d t r i c a r b o n y l m o l e c u l e . However t h e m a i n s i g n a l s c o u l d be a s s i g n e d t o t h e m o l e c u l a r a r r a n g e m e n t s shown i n F i g . 14. Thus t h e '''H nmr s p e c t r u m c o n -t a i n e d f o u r s h a r p s i n g l e t s i n the. rGaMe^ r e g i o n afed9.ilI.^> 9.18; •9d.64-i.and 9.v<7>3 T . I n a d d i t i o n two NH s i g n a l s a t 1.53 and 2.14 x 4 and c o m p l i c a t e d p a t t e r n s i n t h e p z - H and pz-Me r e g i o n s o f t h e s p e c t r u m were o b s e r v e d . - 37 -F i g u r e 14. P r o p o s e d p r o d u c t s i n t h e p r e p a r a t i o n o f [ M e 2Ga(pz") 2 ] R e (CO) 3 (pzH) . To e x p l a i n t h e p r e s e n c e o f an u n s u b s t i t u t e d p y r a z o l y l g r o u p i n a b r i d g i n g p o s i t i o n , a p r e m i s e s u p p o r t e d by b o t h IR and nmr d a t a , i t i s p r o p o s e d t h a t s c r a m b l i n g between t h e b r i d g i n g p y r a z o l y l and t e r m i n a l p y r a z o l e r i n g s i s t a k i n g p l a c e i n s o l u t i o n . A p o s s i b l e mechanism f o r t h i s e x c h a n g e i s i l l u s t r a t e d b e l o w : F i g u r e 15. P r o p o s e d mechanism f o r t h e exchange o f b r i d g i n g p y r a z o l y l and t e r m i n a l p y r a z o l e g r o u p s i n s o l u t i o n . I n t h i s scheme t h e t e r m i n a l p y r a z o l e l i g a n d i s shown i n t h e a x i a l (d) p o s i t i o n ( F i g . 9 ) , an a r r a n g e m e n t w h i c h may be p r e -38 -f e r r e d f o r t h i s l i g a n d o r c o u l d a r i s e v i a a s i m p l e f G a - (N-N) 2 - R e " 3 ' b o a t f l i p i f t h e p y r a z o l e o r i g i n a t e d i n t h e o t h e r a x i a l p o s i t i o n . A m i g r a t i o n o f t h e 'N-H' p r o t o n a l t e r n a t e s t h e p y r a z o l e and 3,5 d i m e t h y l p y r a z o l e g r o u p s as t e r m i n a l l i g a n d s . A l t h o u g h s u c h i n t e r c h a n g e has n o t been p r e v i o u s l y o b s e r v e d i n o v e r a l l n e u t r a l m o l e c u l e s , p y r a z o l y l - p y r a z o l e s c r a m b l i n g i s n o t unknown. Thus t h e "'"H nmr s p e c t r a o f t h e a n i o n i c s p e c i e s [ M e 2 G a ( p z ) 2 ] M ( C O ) 3 ( p z H ) ~ (M=Mo o r W) d i s p l a y e d o n l y one s e t o f s i g n a l s f o r b o t h t h e t e r m i n a l p y r a z o l e and b r i d g i n g p y r a z o l y l g r o u p s a t room, t e m p e r a t u r e . A c r y s t a l s t r u c t u r e a n a l y s i s o f t h e a n i o n where M=Mo c l e a r l y shows c i s c o o r d i n a t i o n o f t h e b i d e n t a t e l i g a n d , w i t h one p y r a z o l e t e r m i n a l l y bonded t o t h e Mo i n an a x i a l p o s i t i o n . ( 3 3 ) . U n f o r t u n a t e l y v a r i a b l e t e m p e r a t u r e ~*"H nmr s t u d i e s on [ M e 2 G a ( p z " ) 2 ] R e ( C O ) 3 ( p z H ) c o u l d n o t be u s e d t o c o n f i r m t h e p r o p o s e d mechanism o u t l i n e d i n F i g . 15. However h e a t i n g a b e n -zene s o l u t i o n o f t h i s c omplex t o -70° r e s u l t e d i n t h e f o r m a t i o n o f a new s p e c i e s , [ M e G a ( p z ) ( p z " ) 2 ] R e ( C O ) 3 . I n t h e dy n a m i c s o l u t i o n mechanism p r o p o s e d i t c a n be s e e n t h a t t h e ' m o b i l e ' h y d r o g e n i s b r o u g h t w i t h i n c l o s e r a n g e o f a m e t h y l g r o u p on t h e g a l l i u m atom, making a methane e l i m i n a t i o n r e a c t i o n c e r t a i n l y f e a s i b l e ( c f . r e f . 5 0 ) . The mass s p e c t r u m o f [ M e 2 G a ( p z " ) 2 ] R e ( C O ) 3 ( p z H ) c o n t a i n e d a s m a l l m/e s i g n a l f o r t h e p a r e n t i o n , P + ( 3 . 0 % ) . M a j o r p e a k s were a s s i g n a b l e t o t h e i o n s P-Me + ( 4 1 . 0 % ) , P-Me-CO + ( 9 1 . 7 % ) , P-Me-pzH + ( 3 4 . 8 % ) , P-Me-C0-pzH + ( 1 0 0 . 0 % ) , P-Me-2CO-pzH + (28.2%) andPP-Me-3CO-pzH + ( 2 0 . 7 % ) . - 39 -2.3.3 [Me^Ga (C-,HN nRj (OH) ] Re (CO)-,X (R=H o r Me; X=CO o r P P h 3 ) N o v e l u n s y m m e t r i c mono} ( 1 - p y r a z o l y l ) g a l l a t e b i d e n t a t e l i g a n d s have b e e n p r e p a r e d in s i t u f r o m t h e r e a c t i o n o f s o d i u m p y r a z o -l i d e and d i m e t h y l g a l l i u m h y d r o x i d e . When s t i r r e d w i t h [ R e ( C O ) 4 C l ] 2 t h e s e l i g a n d s were f o u n d t o c o o r d i n a t e i n a c h e l a t -i n g c i s manner, t h e Ga and Re atoms b e i n g b r i d g e d by a s i n g l e e x o b i d e n t a t e p y r a z o l y l r i n g and an 'OH'. As i n t h e i s o e l e c t r o n i c [Me 2Ga (C 3HN-,R 2) 2 ] R e (CO) 4 (R=H o r Me) s p e c i e s d e s c r i b e d i n - t h e p r e v i o u s s e c t i o n , one CO l i g a n d was o b s e r v e d t o be l a b i l e and e a s i l y s u b s t i t u t e d by P P h 3 . The m e t a t h e s i s p r o d u c t s , [ M e 2 G a ( C 3 H N 2 R 2 ) ( O H ) ] R e ( C O ) 3 ( P P h 3 ) (R=H o r Me), a r e a i r s t a b l e s o l i d s . The f o l l o w i n g s e q u e n c e o f r e a c t i o n s i s u s e d t o p r e p a r e t h e b i s p y r a z o l y l g a l l a t e l i g a n d s ( 1 6 ) ; i ) Me 3Ga + Napz > N a + [Me 3Ga (pz) ] ~ i i ) N a + [ M e 3 G a (pz) ] ~ + pzH • N a + [ M e 2 G a ( p z ) 2 ] ~ + C H 4 A s i m i l a r o r d e r o f r e a c t i o n s c a n n o t be u s e d t o p r e p a r e t h e p r e s e n t h y d r o x o l i g a n d s as H 2 0 i s u s e d as t h e 'OH' s o u r c e . N a + [ M e 3 G a ( p z ) ] r e a c t s r e a d i l y w i t h H2'0 t o y i e l d , p y r a z o l e . The h y d r o x o g a l l a t e l i g a n d s c o u l d be p r e p a r e d v i a a r e v e r s e s e q u e n c e , i ) 4Me 3Ga + 4H0H y [ M e 2 G a ( O H ) ] 4 + 4CH 4 i i ) [ M e 2 G a ( O H ) ] 4 + 4Napz *• 4Na +[;Me 2Ga (pz) (OH)"' ] T h i s r e a c t i o n s e q u e n c e c a n n o t be u s e d t o p r e p a r e b i s p y r a z o l y l -g a l l a t e l i g a n d s due t o t h e marked s t a b i l i t y o f t h e p y r a z o l y l - 40 -b r i d g e d g a l l i u m d i m e r , [ M e 2 G a ( y - p z ) ] 2 , w h i c h w o u l d i n i t i a l l y f o r m . To d a t e n o t b r i d g e c l e a v a g e r e a c t i o n s o f t h i s d i m e r have b e e n r e p o r t e d . The s y n t h e s e s o f t h e n o v e l [ M e 2 G a ( C 3 H N 2 R 2 ) ( O H ) ] ~ (R=Ho o r Me) l i g a n d s a r e made p o s s i b l e by t h e r e l a t i v e l y w e a k l y a s s o -c i a t e d t e t r a m e r i c [Me 2Ga (OH). ] 4 m o l e c u l e . I n confer.asfettoothe u n r e a c t i v i t y o f [ M e 2 G a ( y - p z ) ] 2 , d i s s o c i a t i o n o f [ M e 2 G a ( O H ) ] 4 i n t o monomeric u n i t s i s known.,.^..... A c r y s t a l s t r u c t u r e o f t h e m o l e c u l e has shown i t t o be a c y c l i c t e t r a m e r w i t h b r i d g i n g h y d r o x y l g r o u p s (55) . From bond l e n g t h c o m p a r i s o n s i t has b e en s p e c u l a t e d t h a t w h i l e t h e Ga-Me bonds a r e s t r o n g , t h e h y d r o x y l g r o u p s f o r m r e l a t i v e l y weak r i n g b o n d s . Thus t h e t e t r a m e r r e a d i l y d i s s o l v e s i n o r g a n i c s o l v e n t s and r e a c t s w i t h b o t h a c i d s and b a s e s W i t h o u t r u p t u r e o f t h e g a l l i u m - c a r b o n bonds ( 5 6 ) . I n a d d i t i o n [ M e 2 G a ( O H ) ] 4 r e a c t s q u i c k l y w i t h a c e t y l a c e t o n e t o g i v e a q u a n t i t a t i v e y i e l d o f M e 2 G a ( C 5 H 7 0 2 ) ( 5 7 ) . Mass s p e c t r a o f t h e t e t r a c a r b o n y l c o m p l e x e s [ M e 2 G a ( C 3 H N 2 R 2 ) ( O H ) ] R e ( C O ) 4 (R=H o r Me) c o u l d n o t be o b t a i n e d due t o i n v o l a -t i l i t y a t room t e m p e r a t u r e and d e c o m p o s i t i o n a t e l e v a t e d temp-e r a t u r e s . However a d e q u a t e e l e m e n t a l a n a l y s e s were o b t a i n e d and i n f r a r e d d a t a were as e x p e c t e d f o r a t e t r a c a r b o n y l m o l e c u l e c o n t a i n i n g a c i s c h e l a t i n g l i g a n d (see T a b l e I I ) . I t was d i f f i c u l t t o o b t a i n a ''"H nmr s p e c t r u m o f [ M e 2Ga(pz) (OH) J'Re (CO) 4 due t o sample i n s o l u b i l i t y , however t h e i n t r o d u c t i o n o f m e t h y l g r o u p s a t t h e C(3) and C(5) p o s i t i o n s o f t h e p y r a z o l y l g r o u p i m p r o v e d t h e s o l u b i l i t y o f t h e t e t r a c a r b o n y l i n d , - a c e t o n e . - 41 -I n c o m p l e x e s c o n t a i n i n g a m o n o ( 1 - p y r a z o l y l ) g a l l a t e l i g a n d , s t e r i c and e l e c t r o n i c c o n s i d e r a t i o n s no l o n g e r r e s u l t i n t h e b o a t c o n f o r m a t i o n b e i n g a f a v o u r e d m o l e c u l a r g e o m e t r y . 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 o f a r h e n i u m t r i c a r b o n y l complex i n c o r p o r a t i n g t h e t r i d e n t a t e [ M e 2 G a ( p z " ) ( 0 C H 2 C H 2 N M e 2 ) ] l i g a n d [ s e e s e c . 3 . 3 . 1 ( b ) ] shows f a c 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 , w i t h t h e i n t e r n a l fGa-(N-N)-Re-O-t f i v e - membered r i n g b e i n g a p p r o x i -m a t e l y p l a n a r . ( F i g . 1 6 a ) . I t seems l i k e l y t h a t t h e h y d r o x o b r i d g i n g b i d e n t a t e l i g a n d w o u l d c o o r d i n a t e i n - a n a n a l o g o u s f a s h i o n , a s shown i n F i g . 16b. Such a p l a n a r l i g a n d g e o m e t r y r e s u l t s i n two s t r u c t u r a l l y e q u i v a l e n t g a l l i u m m e t h y l g r o u p s i n t h e t e t r a c a r b o n y l m o l e c u l e s . T h i s i s c o n s i s t e n t w i t h t h e s i n g l e t o b s e r v e d f o r t h e 'Ga-Me 2' p r o t o n s i n t h e "*"H nmr s p e c t r u m o f [ M e 2 G a ( p z " ) ( O H ) ] R e ( C O ) 4 ( F i g . 1 7 ) . I n t h i s s p e c t r u m i t i s n o t e d t h a t t h e b r i d g i n g h y d r o x o p r o t o n i s a t v e r y h i g h f i e l d (9.53 x) , i n d i c a t i v e o f s u b s t a n t i a l s h i e l d i n g a f f e c t i n g t h i s p r o t o n . O t h e r H r e p o r t e d compounds c o n t a i n i n g a Ga—0-—M (M=Mo o r W) b r i d g e show a h y d r o x o p r o t o n r e s o n a n c e i n t h e i r "'"H nmr s p e c t r a between 9.83-10.56 x ( 5 8 ) . R e s e m b l i n g t h e b e h a v i o u r o f t h e u n s t a b l e b i s ( 1 - p y r a z o l y l ) -g a l l a t e r h e n i u m t e t r a c a r b o n y l c o m p l e x e s , t h e c o r r e s p o n d i n g mono-( 1 - p y r a z o l y l ) h y d r o x o t e t r a c a r b o n y l s r e a d i l y r e a c t e d w i t h PPh^. Two g a l l i u m m e t h y l s i n g l e t s i n t h e "''H nmr s p e c t r a o f t h e p h o s -p h i n e s u b s t i t u t i o n p r o d u c t s (see T a b l e I I ) i n d i c a t e d t h e p h o s p h i n e t o be c o o r d i n a t i n g a t a p o s i t i o n m u t u a l l y c i s t o b o t h d o n o r atoms o f t h e c h e l a t i n g g a l l a t e l i g a n d , r e s u l t i n g i n s t r u c t u r a l l y n o n - e q u i v a l e n t Ga-Me g r o u p s ( F i g . 1 8 ) . I f s u b s t i -- 42 -F i g u r e 16. (a) C o n f o r m a t i o n o f fiv e - m e m b e r e d £ G a - ( N - N ) - R e - O f r i n g i n t t h e complex [ M e 2 G a ( p z " )(OCH 2CH 2 N M e 2X ] R e(CO) 3, (b) P r o p o s e d c o n f o r m a t i o n o f f i v e -membered f Ga- (N-N) -Re-O-J r i n g s i n t h e co m p l e x e s [Me 2Ga ( C 3 H N 2 R 2 ) (OH) ] Re (CO). 4 . t u t i o n were t o o c c u r a t t h e a l t e r n a t i v e CO p o s i t i o n s , t h e g a l l i u m m e t h y l g r o u p s would r e m a i n i n e q u i v a l e n t e n v i r o n m e n t s . I n t h e 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 e h y d r o x o p r o t o n s move t o e v e n h i g h e r f i e l d i n t h e "^H nmr, a r e s u l t o f t h e weaker i T - a c c e p t i n g a b i l i t y o f P P h 3 compared t o CO ( 6 8 ) . The IR s p e c t r a o f t h e [ M e 2 G a ( C 3 H N 2 R 2 ) ( O H ) ] R e ( C O ) 3 ( P P h 3 ) (R=H o r Me) c o m p l e x e s s u p p o r t f a c i a l c o o r d i n a t i o n o f t h e r e m a i n -i n g t h r e e c a r b o n y l g r o u p s (see T a b l e I I ) . I n t h e N i i j o l s p e c t r a t h e b r i d g i n g 'OH' v i b r a t i o n r e m a i n s c o n s t a n t a t -3600 cm . The mass s p e c t r a o f t h e P P h 3 c o m p l e x e s were o b t a i n e d w i t h a p r o b e t e m p e r a t u r e o f -120°., When R=H t h e l a r g e s t m/e s i g n a l was due t o t h e p a r e n t i o n minus on e ^ . c a r b o n y l . The c o m p l e t e a s s i g n -y N Me 2 G a I -O '.»: m i m f r ' • " 1 1 1 1 ' ' ' ' ' 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 J ,i 11 u i 2 3 4 5 6 7 o j # i u « -F i g u r e 17. Room t e m p e r a t u r e 100 MHz H nmr s p e c t r u m f o r [Me 2Ga(pz") (OH) ] R e ( C O ) 4 - . 1 5 T H F i n ( C D ^ C O . Me Cd Me 0.^ y H ,0 Re — C O PPh /I 3 C o CO 1 I I I I •,. • 1 I • 1,1 n , ^  M f f ; . » . . . . • . , . . I I .... I .... I I • • I I I I 1,1 I I II I I I I 2 3 4 5 6 7 8 9 10 T 3  F i g u r e 18 Room t e m p e r a t u r e 100 MHz H nmr s p e c t r u m f o r [ M e „ G a ( p z ) ( O H ) ] R e ( C O ) _ ( P P h ~ ) i n C C D „ . J. 5 5 b b - 45 -ment o f t h i s mass s p e c t r u m i s t a b u l a t e d i n T a b l e V. When R=Me no p a r e n t i o n was v i s i b l e b u t p e a k s a t t r i b u t a b l e t o t h e e x p e c t e d f r a g m e n t a t i o n o f t h e m o l e c u l a r i o n were a s s i g n a b l e . 2.3.4 [ M e 2 G a ( p z ) (PPh-J ] Re (CO) 4 A t t e m p t s t o p r e p a r e t h e d i m e t h y l ( 1 - p y r a z o l y l ) ( p h o s p h i n o ) -g a l l a t e l i g a n d v i a t h e f o l l o w i n g r e a c t i o n s e q u e n c e were un-s u c c e s s f u l (59) ; i ) Me 3Ga + L i P P h 2 T H F > L i + [ M e 3 G a ( P P h 2 ) ] " i i ) L i + [ M e 3 G a ( P P h 2 ) ] " + pzH ™ F > L i + [ M e 2 G a ( p z ) ( P P h 2 ) ] " + C H 4 However u s i n g a r e v e r s e r e a c t i o n s e q u e n c e ( i . e . as d e s c r i b e d i n t h e p r e v i o u s s e c t i o n f o r t h e s y n t h e s e s o f t h e p y r a z o l y l -h y d r o x o g a l l a t e a n i o n s ) t h e d e s i r e d l i g a n d c o u l d be p r e p a r e d in s i t u . THF s o l u t i o n s o f t h i s l i g a n d were u n s t a b l e , c o m p l e t e -l y d i s p r o p o r t i o n a t i n g when a l l o w e d t o s t a n d a t room t e m p e r a t u r e f o r s e v e r a l d a y s , v i a 2 N a + [ M e 2 G a (pz) (PPh 2) ] " >- [Me 2Ga (y-pz) ] 2 + N a P P h 2 F r e s h l y p r e p a r e d l i g a n d was s t i r r e d d i r e c t l y w i t h [ R e ( C O ) 4 C 1 ] 2 , r e s u l t i n g i n t h e i s o l a t i o n o f [ M e 2 G a ( p z ) ( P P h 2 ) ] Re (CO) 4 . The "*"H nmr s p e c t r u m o f t h i s s p e c i e s c o n t a i n e d one s i n g l e t i n t h e g a l l i u m m e t h y l r e g i o n , a g a i n s u g g e s t i n g a p l a n a r g e o m e t r y f o r t h e c o o r d i n a t e d b i d e n t a t e l i g a n d i n s t e a d o f a b o a t c o n f o r m a t i o n . - 4 6 -T a b l e V. Mass S p e c t r a l D a t a o f [ M e 2 G a ( p z ) ( O H ) ] R e ( C O ) 3 ( P P h 3 ) = P m/e* A s s i g n m e n t I n t e n s i t y 716 P + .9 701 P-Me 37.0 688 P-CO + 100.0 673 P-Me-CO + 26.9 620 P-CO-pz-H + 76.7 561 ( p z ) ( O H ) R e ( C O ) ( P P h 3 ) + 39 . 2 533 Re (CO) 3 (PPh 3) + 15.7 449 R e ( P P h 3 ) + 32.2 383 P-Me-2CO-PPh 3 + 8.9 355 P-Me-3CO-PPh 3 + 3.3 262 P P h 3 + 92.7 185 P P h 2 + 7.0 183 P P h 2 - 2 H + 45.7 108 P P h + 22.3 99 + Me 2Ga 12.7 78 C 6 H 6 + 5.7 69 G a + 15.7 C a l c u l a t e d w i t h Ga and Re - 47 -The l a r g e s t m/e s i g n a l i n t h e mass s p e c t r u m o f t h e p h o s -p h i n e b r i d g e d complex was due t o G a + ( 1 0 0 . 0 % ) . S i g n a l s c o r r e -s p o n d i n g t o t h e p a r e n t i o n , P + (7.3%)', P-Me + ( 9 3 . 1 % ) , P-Me-CO + ( 7 5 . 6 % ) , P-Me-2CO + ( 3 6 . 6 % ) , P-Me-3CO + (71.3%) and P-Me-4CO) + (32.3%) were a l s o a s s i g n a b l e . I n a d d i t i o n t o t h e d e s i r e d p r o d u c t , t h e mass s p e c t r u m c o n t a i n e d s i g n a l s a t t r i b u t a b l e t o R e 2 ( C O ) g ( P P h 2 ) ( p z ) + (7.1%) and i o n s r e s u l t i n g f r o m t h e s u c c e s -s i v e l o s s o f c a r b o n y l s f r o m t h i s r h e n i u m d i m e r . The r e a c t i o n o f [ M e 2 G a ( p z ) ( P P h 2 ) ] R e ( C O ) 4 w i t h P P h 3 d i d n o t y i e l d t h e e x p e c t e d CO d i s p l a c e m e n t p r o d u c t as o b s e r v e d w i t h r e l a t e d r h e n i u m t e t r a c a r b o n y l s p e c i e s d e s c r i b e d p r e v i o u s l y . S t e r i c f a c t o r s may d i s c o u r a g e s u c h a r e a c t i o n f r o m o c c u r r i n g . The p r o p o s e d g e o m e t r y o f t h e p h o s p h i n o b r i d g e d m o l e c u l e i s shown be l o w : . . . M e G a ' N 0 ( b ) ?a) ° 0 = C 6 H 5 F i g u r e 19. P r o p o s e d c o n f o r m a t i o n o f t h e f i v e -membered -E-Ga- (N-N) -Re-P} r i n g i n [ M e 2 G a ( p z ) ( P P h 2 ) ] R e ( C O ) 4 . I n r e l a t e d r h e n i u m t e t r a c a r b o n y l c o m p l e x e s CO s u b s t i t u -t i o n has b e e n shown t o t a k e p l a c e a t a p o s i t i o n m u t u a l l y c i s t o b o t h d o n o r s i t e s o f t h e c h e l a t i n g l i g a n d [ i . e . (a) o r ( b ) ] . I n t h e p r e s e n t m o l e c u l e t h e p h e n y l g r o u p s i n t h e b r i d g i n g p o s i t i o n s i n t e r a c t w i t h e a c h o f t h e s e two s i t e s e q u a l l y . The b u l k i n e s s o f t h e 'PPh 2' b r i d g e may be a c o n t r i b u t i n g f a c t o r t o t h e o b s e r v e d - 48 -f a i l u r e o f [ M e 2 G a ( p z ) ( P P h , , ) ] R e ( C O ) ^ t o u n d e r g o t h e e x p e c t e d CO s u b s t i t u t i o n r e a c t i o n . 2.4 Summary Rhenium (I) t e t r a c a r b o n y l s p e c i e s have been p r e p a r e d c o n -t a i n i n g t h e s y m m e t r i c b i s p y r a z o l y l g a l l a t e l i g a n d s . Manganese a n a l o g u e s o f t h e s e t e t r a c a r b o n y l c o m p l e x e s a r e n o t known, a l t h o u g h s u c h s p e c i e s a r e p r e s u m a b l y u n s t a b l e r e a c t i o n i n t e r m e d i a t e s i n s e v e r a l r e p o r t e d p r e p a r a t i o n s ( i . e . 3 3 , 5 0 ) . N o t u n e x p e c t e d l y , one CO g r o u p was f o u n d t o be v e r y l a b i l e i n t h e r h e n i u m t e t r a -c a r b o n y l s p e c i e s . i s o l a t e d , and e x c h a n g e o f t h i s CO w i t h e i t h e r PPh-j o r p y r a z o l e . - l e d t o an a i r s t a b l e , f a c i a l l y c o o r d i n a t e d t r i c a r b o n y l p r o d u c t . Rhenium m o l e c u l e s c o n t a i n i n g t h e [Me2Ga(C^HN-jR,,)23 (R=H o r Me) l i g a n d s a d o p t e d a b o a t c o n f o r m a t i o n . T h i s c o n f o r m -a t i o n o c c u r s a l m o s t e x c l u s i v e l y i n t r a n s i t i o n m e t a l c o m p l e x e s c o n t a i n i n g t h e s e and t h e c o r r e s p o n d i n g - b o r a t e b i d e n t a t e l i g a n d s . U n u s u a l u n s y m m e t r i c d i m e t h y l m o n o ( 1 - p y r a z o l y l ) g a l l a t e c h e -l a t i n g l i g a n d s have been p r e p a r e d c o n t a i n i n g an 'OH' o r a 'PPh 2' m o i e t y as one o f t h e l i g a n d d o n o r s i t e s . I t i s p r o p o s e d t h a t t h e s e l i g a n d s r e t a i n a p l a n a r g e o m e t r y upon c o o r d i n a t i o n t o t h e t r a n s i t i o n m e t a l c e n t r e , a h y p o t h e s i s s u p p o r t e d by ~*"H nmr d a t a . The s y n t h e s e s o f n o v e l m o n o ( 1 - p y r a z o l y l ) g a l l a t e l i g a n d s , by t h e u s e o f a r e v e r s e r e a c t i o n s e q u e n c e t o t h a t employed f o r t h e p r e p a r a t i o n o f t h e b i s p y r a z o l y l g a l l a t e a n i o n s , s u g g e s t s t h a t s u c h a s e q u e n c e may be a g e n e r a l r o u t e t o w a r d s t h e f o r m a t i o n o f u n s y m m e t r i c b i d e n t a t e g a l l a t e l i g a n d s . - 4 9 -CHAPTER I I I RHENIUM AND MANGANESE CARBONYL DERIVATIVES OF TRIDENTATE PYRAZOLYLGALLATE LIGANDS 3 .1 I n t r o d u c t i o n The t r i d e n t a t e p o l y p y r a z o l y l b o r a t e and c o r r e s p o n d i n g g a l l a t e a n i o n s c o n s t i t u t e a c l a s s o f u n i q u e m u l t i d e n t a t e l i g a n d s o f symmetry. T h e i r c o o r d i n a t i o n p r o p e r t i e s a r e p e r h a p s b e s t com-p a r e d t o t h o s e o f t h e n 5 - c y c l o p e n t a d i e n y l g r o u p , as e a c h a r e u n i n e g a t i v e , s i x e l e c t r o n d o n o r s . I n a d d i t i o n , a l t h o u g h i n t e r -a c t i o n s between t h e c y c l o p e n t a d i e n y l r i n g and s u i t a b l e t r a n s i t i o n m e t a l s o c c u r s v i a i r-bond f o r m a t i o n , w h i l e c o o r d i n a t i o n o f t h e p y r a z o l y l a n i o n s t a k e s p l a c e v i a t h r e e a-bonds, e a c h o f t h e s e l i g a n d s f o r m a l l y o c c u p y t h r e e c o o r d i n a t i o n s i t e s when bonded t o a t r a n s i t i o n m e t a l . The h y d r o t r i s ( 1 - p y r a z o l y l ) b o r a t e a n i o n has p r e v i o u s l y b e e n o b s e r v e d t o p o s s e s s c e r t a i n s t a b i l i z i n g p r o p e r t i e s . F o r example, w h i l e a t t e m p t s t o p r e p a r e ( n 5 - C ^ H ^ ) C u ( C O ) have n o t b e e n s u c c e s s -f u l ( 6 0 ) , t h e c o r r e s p o n d i n g complex [ H B ( p z ) 3 ] C u ( C O ) (61) i s a c r y s t a l l i n e , w h i t e , a i r s t a b l e s o l i d . A l s o , i t i s known t h a t f i v e - c o o r d i n a t e a c e t y l e n e c o m p l e x e s o f P t ( I I ) a r e g e n e r a l l y u n s t a b l e w i t h r e s p e c t t o i n s e r t i o n and d i s s o c i a t i o n . However f i v e - c o o r d i n a t e m e t h y l p l a t i n u m ( I I ) a c e t y l e n e s p e c i e s c o n t a i n i n g [ H B ( p z ) 3 ] ~ c a n be r e a d i l y p r e p a r e d and h a n d l e d 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 ( 6 2 ) . The t r i s p y r a z o l ' y l ' b o r a t e x l ' i g a r i d s a r e b b e t t e r e e l - e e t r o n d o n a t i n g g r o u p s t h a n t h e c y c l o p e n t a d i e n y l s p e c i e s and t h i s - 50 -p r o p e r t y v e r y l i k e l y a c c o u n t s f o r t h e s t a b i l i z i n g e f f e c t o f t h e b o r a t e a n i o n s . A c o m p a r i s o n o f vCO v a l u e s i n r e l a t e d t r a n s i t i o n m e t a l c a r b o n y l c o m p l e x e s c o n t a i n i n g e i t h e r p y r a z o l y l b o r a t e o r p y r a z o l y l g a l l a t e t r i d e n t a t e l i g a n d s , i n d i c a t e t h a t t h e g a l l a t e s a r e m a r k e d l y b e t t e r e l e c t r o n d o n a t i n g l i g a n d s t h a n t h e i r b o r o n c o u n t e r p a r t s ( 6 3 ) . Thus, b a s e d upon e l e c t r o n i c c o n s i d e r a t i o n s , p y r a z o l y l g a l l a t e l i g a n d s c o u l d p o t e n t i a l l y s t a b i l i z e compounds f o r w h i c h t h e p y r a z o l y l b o r a t e o r c y c l o p e n t a d i e n y l a n a l o g u e s a r e u n s t a b l e o r n o t known. A number o f Mn(I) and R e ( I ) t r i c a r b o n y l c o m p l e x e s have been p r e p a r e d c o n t a i n i n g s y m m e t r i c o r u n s y m m e t r i c p y r a z o l y l g a l l a t e t r i d e n t a t e l i g a n d s . I n e a c h o f t h e s e c o m p l e x e s , g e n e r a l l y r e f e r r e d t o as ' L M ( C 0 ) 3 ' (M=Mn o r Re; L=a g e n e r i c t r i d e n t a t e p y r a z o l y l g a l l a t e a n i o n i c l i g a n d ) , t h e t r a n s i t i o n m e t a l r e s i d e s i n t h e c e n t r e o f an o c t a h e d r a l e n v i r o n m e n t and t h e l i g a n d c o o r d i n a t e s i n a f a c i a l a r r a n g e m e n t . The e f f e c t s on L M ( C O ) 3 by i n t r o d u c i n g v a r i a t i o n s i n t h e l i g a n d L have been s t u d i e d . T h ese v a r i a t i o n s a l t e r i ) t h e e l e c t r o n d o n a t i n g a b i l i t y , i i ) t h e s p a c e r e q u i r e m e n t a n d / o r i i i ) t h e r e s u l t i n g s t e r e o -c h e m i s t r y o f L. The r e a c t i v i t i e s o f t h e r h e n i u m c o m p l e x e s p r e p a r e d have been e x a m i n e d and compared t o t h e v a l e n c e i s o e l e c t r o n i c and pseudo 5 i s o s t r u c t u r a l compound (n "C^H..) Re (CO) ^ . The LRe (CO) ^ c o m p l e x e s b e h a v e d s u r p r i s i n g l y d i f f e r e n t l y f r o m t h e c y c l o p e n t a d i e n y l a n a l o g u n d e r s i m i l a r r e a c t i o n c o n d i t i o n s . - 51 -3 . 2 E x p e r i m e n t a l 3.2.1 S t a r t i n g M a t e r i a l s N a + [ M e G a ( p z ) 3 ] ~ (31) and N a + [ M e G a ( p z " ) 3 ] " (58) were p r e -p a r e d a s d e s c r i b e d i n t h e l i t e r a t u r e . Mn (CO) .B^ Br (((6$) , [ R e C l 2 ( N O ) ( C O ) 2 ] 2 ( 6 5 ) , p h e n y l - 2 - h y d r o x y e t h y l s u l f i d e ( 6 6 ) , and e t h y l - 2 - h y d r o x y e t h y l s u l f i d e (67) were p r e p a r e d by l i t e r a t u r e m e thods. 2 - a m i n o e t h a n o l ( A l d r i c h ) and 2 - N , N - d i m e t h y l a m i n o e t h a n o l ( A l d r i c h ) were r e f l u x e d o v e r C a S 0 4 and d i s t i l l e d b e f o r e u s e . 2 - a m i n o e t h a n e t h i o l h y d r o c h l o r i d e ( A l d r i c h ) , 2 - d i m e t h y l a m i n o e t h a n e -t h i o l h y d r o c h l o r i d e ( P f a l t z and B a u e r ) , 1 , 2 - e t h a n e d i t h i o l ( A l d r i c h ) , L - 2 - a m i n o - l - p r o p a n o l ( A l d r i c h ) , d - 2 - a m i n o - l - b u t a n o l ( A l d r i c h ) , 1 - 2 - a m i n o - l - b u t a n o l ( A l d r i c h ) , n i t r y l h e x a f l a o r o -p h o s p h a t e ( A l f a ) and n i t r o s y l t e t r a f l u o r o b o r a t e ( A l d r i c h ) , w e r e u s e d as r e c e i v e d . N i t r o s y l h e x a f l u o r o p h o s p h a t e ( A l f a ) was d r i e d o v e r p h o s p h o r o u s p e n t o x i d e p r i o r t o u s e . I o d o s o b e n z e n e (ICN) was c h e c k e d f o r p u r i t y by c a r b o n and h y d r o g e n a n a l y s i s and u s e d as s u p p l i e d . T r i e t h y l a m i n e was d i s t i l l e d f r o m p o t a s s i u m h y d r o x i d e p e l l e t s and s t o r e d o v e r m o l e c u l a r s i e v e s . L i t h i u m t r i e t h y l -b o r o h y d r i d e ( S u p e r - H y d r i d e ) and p o t a s s i u m t r i - s e c - b u t y l b o r o h y d r i d e ( K - S e l e c t r i d e ) were p u r c h a s e d as 1M s o l u t i o n s i n THF ( A l d r i c h ) and were u s e d as s u p p l i e d . Sodium h y d r i d e ( A l f a ) was a l s o u s e d as r e c e i v e d . - 52 -3,2.2 P r e p a r a t i o n o f [ M e G a ( p z ) , ] R e ( C O ) 3 2 N a + [ M e G a ( p z ) 3 ] ~ + [ R e ( C O ) 4 C l ] 2 — ™ F > 2 [ M e G a ( p z ) 3 ] R e ( C O ) 3 + 2NaCl + 2C0 Two m o l a r e q u i v a l e n t s o f N a + [ M e G a ( p z ) 3 ] were added t o [ R e ( C O ) 4 C l ] 2 (.482 g, .722 mmol) d i s s o l v e d i n THF and t h e s o l u -t i o n r e f l u x e d o v e r n i g h t . The THF was removed in vacuo and t h e r e m a i n i n g o f f - w h i t e r e s i d u e d i s s o l v e d i n be n z e n e and f i l t e r e d . Slow e v a p o r a t i o n o f t h e b e n z e n e p r o d u c e d l a r g e , c o l o u r l e s s c u b i c c r y s t a l s (.321 g, 40% y i e l d ) and a r e s i d u e o f t h e d e s i r e d p r o d u c t w h i c h c o u l d be s c r a p e d i n t o a powder. I t was n e c e s s a r y t o d r y t h e g r o u n d p r o d u c t in vacuo a t 50° f o r 2 d a y s t o remove a l l t r a c e s o f b e n z e n e . T o t a l y i e l d -8 0%. A n a l . C a l ' d f o r [ M e G a ( p z ) 3 ] R e ( C O ) 3 : C, 28.06; H, 2.16; N, 15.11. Found: C, 27.95; H, 2.13; N, 14.90. v C 0 ( c m _ 1 ) : 2028, 1918 ( C , H 1 0 ) . 3.2.3 A t t e m p t e d P r e p a r a t i o n o f [ M e G a ( p z " ) 3 ] R e ( C O ) 3 A t t e m p t s t o p r e p a r e t h e 3,5 d i m e t h y l p y r a z o l y l r h e n i u m t r i c a r b o n y l complex u s i n g t h e a p p r o p r i a t e l i g a n d and a p r o c e d u r e s i m i l a r t o t h a t d e s c r i b e d i n s e c . 3.2.2, r e s u l t e d i n a m i x t u r e o f p r o d u c t s . S p e c t r a l d a t a i n d i c a t e d t h e d e s i r e d compound t o be among t h e p r o d u c t s f o r m e d . 3.2.4 P r e p a r a t i o n o f HSCH 2CH 2NH 2 H S C H „ C H „ N H „ - H C 1 + NaOH — > 2 2 2 A HSCH 2CH 2NH 2 + N a C l + H 2 0 - 53 -2 - a m i n o e t h a n e t h i o l h y d r o c h l o r i d e (10.00 g, 88.02 mmol) and sodium h y d r o x i d e (3.520 g, 88.01 mmol) were r e f l u x e d g e n t l y i n 200 ml EtOH o v e r n i g h t . A p p r o x i m a t e l y 10 g o f a n h y d r o u s c a l c i u m s u l f a t e powder was added and t h e m i x t u r e s t i r r e d f o r 24 h. The i n s o l u b l e m a t e r i a l was a l l o w e d t o s e t t l e o u t o f t h i s s o l u t i o n and t h e l i q u i d was t h e n d e c a n t e d o f f t h e c o o l e d r e a c t i o n m i x t u r e . The d e c a n t e d l i q u i d was f i l t e r e d and t h e EtOH removed in vacuo. The r e m a i n i n g w h i t e s o l i d was d r i e d a t -35° in vacuo. P u r e p r o d u c t was s u b l i m e d a t -150° o n t o a w a t e r c o o l e d p r o b e . The p u r i t y o f t h i s w h i t e , a i r s e n s i t i v e powder was c h e c k e d by "*"H nmr and e l e m e n t a l a n a l y s i s . Y i e l d -80%. 3.2.5 P r e p a r a t i o n o f HSCH2,CH 2NMe 2_ EtOH H S C H „ C H » N M e „ - H C I + NaOH 2 2 2 a HSCH 2CH 2NMe 2 + N a C l + H 2 0 2 - d i m e t h y l a m i n o e t h a n e t h i o l was p r e p a r e d by t h e method d e s c r i b e d i n 3.2.4 e x c e p t t h a t as t h i s t h i o l i s a l i q u i d , i t was p u r i f i e d by vacuum d i s t i l l a t i o n . T h i s e x t r e m e l y a i r s e n s i t i v e p r o d u c t was i s o l a t e d a s a c o l o u r l e s s , c l e a r l i q u i d . Y i e l d -35%. 3.2.6 P r e p a r a t i o n o f t h e L i g a n d s N a + [ M e 2 G a ( C Q H N 2 R 2 ) < ( X C H 2 C H 2 N R ' 2 ) ] ~ (R, R'=H o r Me; X=0 o r S) i ) N a + [ C 3 H N 2 R 2 ] ~ + Me 3Ga T H F > NaatM'e-^Gaj(.G'3'HN2R2) ] " i i ) N a + [ M e 3 G a ( C 3 H N 2 R 2 ) ] ~ + HXCH 2CH 2NR' 2 T ^ F — » • N a + [ M e „ G a (C-,HN„R„)(XCH„CH„NR• ) ] % CH, 2. i 2. z z z z 4 - 54 -The e i g h t l i g a n d s were p r e p a r e d by an i d e n t i c a l method. A t y p i c a l p r e p a r a t i o n f o r t h e c a s e where (R=R'=H, X=0) w i l l be d e s c r i b e d . T r i m e t h y 1 g a l l i u m (2.562 g, 22.31 mmol) i n 20 ml THF was added t o sodium p y r a z o l i d e d i s s o l v e d i n t h e same s o l v e n t . (2.009 g, 22.31 mmol) and t h e r e s u l t a n t s o l u t i o n was s t i r r e d f o r 20 m i n . A THF s o l u t i o n o f 2 - a m i n o e t h a n o l (1.363 g, 22.31 mmol) was t h e n added and t h e c l e a r , c o l o u r l e s s s o l u t i o n r e f l u x e d f o r 24 h. The c o o l e d s o l u t i o n was d i l u t e d w i t h THF t o 250.0 ml i n a v o l u m e t r i c f l a s k and a l i q u o t s o f t h i s s t a n d a r d s o l u t i o n were u s e d i n s u b s e q u e n t r e a c t i o n s . 3.2.7 A l t e r n a t e P r e p a r a t i o n o f t h e L i g a n d N a + [ M e 2 G a ( p z ) ( S C H 2 C H 2 N M e 2 ) ] " i ) HSCH 2CH 2NMe 2-HC1 + 2NaH — T H F • N a + [ S C H 2 C H 2 N M e 2 ] " + 2H 2 + N a C l i i ) N a + [ S C H 2 C H 2 N M e 2 ] ~ + Me 3Ga T H F > . . N a + [ M e 3 G a ( S C H 2 C H 2 N M e 2 ) ] " i i i ) N a + [ M e 3 G a ( S C H 2 C H 2 N M e 2 ) ] ~ + pzH — ' — • • N a + [ M e 2 G a ( p z ) ( S C H 2 C H 2 N M e 2 ) ] ~ + C H 4 2 - d i m e t h y l a m i n o e t h a n e t h i o l h y d r o c h l o r i d e (4.012 g, 28.32 mmol) i n THF was added t o a s l u r r y o f NaH (1.359 g, 56.63 mmol) a l s o i n THF. A f t e r s t i r r i n g f o r 2 d a y s , t r i m e t h y l g a l l i u m (3.252 g, .28.32 mmol) i n THF was added and t h e s o l u t i o n s t i r r e d f o r 20 m i n . P y r a z o l e (1.928 g, 28.32 mmol) d i s s o l v e d i n THF was t h e n added and t h e r e a c t i o n m i x t u r e r e f l u x e d f o r 24 h. T o t a l volume 350 m l . The c o o l e d s o l u t i o n was f i l t e r e d and d i l u t e d t o - 55 -500.0 ml i n a v o l u m e t r i c f l a s k . 3.2.8 P r e p a r a t i o n o f t h e Complexes [Me^Ga (C 3HN^R^) ( X C H 2 C H 2 N R ' 2 ) ] R e ( C O ) 3 (R, R'=H o r Me; X=0 o r S) 2 N a + [ M e 2 G a ( C 3 H N 2 R 2 ) (XCH 2CH 2NR' 2) ] ~ + [ R e ( C 0 ) 4 C l ] 2 ™ F > 2 [ M e 2 G a ( C 3 H N 2 R 2 ) ( X C H 2 C H 2 N R ' 2 ) ] R e ( C O ) 3 + 2NaCl + 2CO The e i g h t c o m p l e x e s were p r e p a r e d by p r o c e d u r e s i d e n t i c a l t o t h a t d e s c r i b e d i n s e c t i o n 3.2.2 u s i n g t h e a p p r o p r i a t e l i g -a nds as p r e p a r e d i n s e c t i o n s 3.2.6 and 3.2.7. When (R=H o r Me; X=0) t h e p r o d u c t s were r e c r y s t a l l i z e d f r o m b e n z e n e o r h e x a n e . A l l o f t h e s e compounds were i s o l a t e d a s e i t h e r w h i t e o r c o l o u r l e s s a i r s t a b l e c r y s t a l s i n -70-80% y i e l d s . When (R=H o r Me; X=S) t h e p r o d u c t s were i s o l a t e d a s o f f -w h i t e o r p a l e brown powders f r o m b e n z e n e . None o f t h e s e com-pounds c o u l d be i n d u c e d t o f o r m c r y s t a l s . When (R=H) t h e compounds a r e s l i g h t l y a i r s e n s i t i v e , when (R=Me) t h e p r o d u c t s a r e a i r s t a b l e . E x t e n d e d d r y i n g in vacuo was r e q u i r e d t o remove t r a c e s o f r e s i d u a l s o l v e n t s i n a l l c a s e s . Y i e l d s -55-65%. S e l e c t e d p h y s i c a l d a t a f o r t h e s e c o m p l e x e s a r e summarized i n T a b l e V I . 3.2.9 P r e p a r a t i o n o f t h e Complexes [ M e 2 G a ( C 3 H N 2 R 2 ) ( S C H 2 C H 2 N R ' 2 ) ] M n ( C O ) , (R, R'=H o r Me) Na [ M e 2 G a ( C 3 H N 2 R 2 ) ( S C H 2 C H 2 N R ' 2 ) ] + M n ( C O ) 5 B r l [ M e 2 G a ( C 3 H N 2 R 2 ) ( S C H 2 C H 2 N R ' 2 ) ] M n ( C O ) 3 + NaBr + 2C0 I n a t y p i c a l p r e p a r a t i o n one m o l a r . e q u i v a l e n t Table V I . C a l c u l a t e d ( % ) Found(%) v C Q ( c m ) M R R' X mp(°C) C H N C H N C,H. Mn H H S * 31 .44 3 . 9 3 11 .00 31 . 2 0 4 . 00 11 . 1 5 2 0 3 1 , 1 9 4 0 , 1 9 1 9 Mn H Me S * 35 . 1 5 4 .64 10 . 2 5 35 . 56 4 . 67 10 . 7 9 2 0 3 0 , 1 9 3 8 , 1 9 1 5 Mn Me H S * 35 . 15 4 . 64 10 .25 35 . 4 5 4 . 68 9 . 9 1 2028 , 1 9 3 8 , 1914 Mn Me Me S * 36 .84 5 . 48 8 .92+ 36 . 57 5 . 40 8 . 9 2 2 0 3 0 , 1 9 3 5 , 1 9 0 7 Re H H 0 1 5 9 - 1 6 0 24 . 15 3 .02 8 .45 24 . 02 2 . 9 9 8 . 2 3 2 0 3 0 , 1 9 2 0 , 1 9 0 0 Re H Me 0 1 2 3 - 1 2 5 27 . 43 3 .62 8 .00 27 . 48 3 . 5 9 7 . 88 2 0 1 5 , 1 9 2 6 , 1 9 0 5 Re Me H 0 1 7 2 - 1 7 4 27 . 43 3 .62 8 .00 27 . 6 9 3 . 6 3 7 . 6 7 2 0 2 5 , 1 9 2 0 , 1 8 9 8 Re Me Me 0 1 5 8 - 1 5 9 30 . 39 4 .16 7 .60 30 . 5 0 4 . 2 8 7 . 54 2 0 2 8 , 1 9 1 7 , 1 8 9 1 Re H H S * 23 .40 2 . 92 8 .19 23 . 98 3 . 0 8 7 • 98 2 0 2 9 , 1 9 2 6 , 1 9 0 8 Re H Me S * 26 . 62 3 . 5 1 7 .76 26 . 9 6 3 . 7 1 7 . 98 2 0 3 1 , 1 9 2 6 , 1 9 0 5 Re Me H S 1 6 0 - 1 6 3 26 . 62 3 . 5 1 7 .76 26 . 4 0 3 . 74 7 . 4 6 2 0 3 1 , 1 9 2 6 , 1 9 0 4 Re Me Me s 1 0 9 - 1 1 2 29 . 5 3 4 .04 7 . 38 29 . 6 1 4 . 28 7 . 09 2 0 2 7 , 1 9 2 5 , 1 9 0 0 * decomposes before m e l t i n g + c a l c u l a t e d f o r [Me 2Ga(pz" ) ( s C H 2 C H 2NMe 2)]Mn ( C O ) 3-H 20 - 57 -o f t h e a p p r o p r i a t e l i g a n d was added t o Mn(CO)^Br (.300 g, 1.091 mmol) d i s s o l v e d i n 100 ml THF. A f t e r r e f l u x i n g t h i s s o l -u t i o n o v e r n i g h t , t h e THF was removed in vacuo and t h e r e m a i n i n g r e s i d u e e x t r a c t e d i n t o C ^ C ^ - The C ^ C ^ e x t r a c t s were f i l -t e r e d and t h e s o l v e n t s u b s e q u e n t l y removed in vacuo. A l l o f t h e manganese s p e c i e s d e s c r i b e d h e r e were o r a n g e s o l i d s w h i c h decomposed when l e f t i n s o l u t i o n o r benzene) f o r e x t e n d e d p e r i o d s o f t i m e . P h y s i c a l d a t a a r e i n c l u d e d i n T a b l e V I . The compound where (R, R'=H) was o b t a i n e d i n ~55% y i e l d as a v e r y a i r s e n s i t i v e powder. When (R=Me, R'=H) t h e p r o d u c t was m o d e r a t e l y a i r s t a b l e , d a r k e n i n g i n c o l o u r a f t e r e x p o s u r e t o a i r f o r s e v e r a l weeks. Y i e l d -75%. When (R, R'=Me) t h e complex was p r e p a r e d as d e s c r i b e d a b o v e , e x c e p t t h a t t h e r e a c t i o n m i x t u r e was s t i r r e d f o r 10 h, r e f l u x t e m p e r a t u r e s r e s u l t i n g i n e x t e n s i v e d e c o m p o s i t i o n . The p r o d u c t f o r m e d i n ~35% y i e l d and was i s o l a t e d as a waxy s o l i d . I t p r o v e d d i f f i c u l t t o i s o l a t e a manganese t r i c a r b o n y l p r o -d u c t f r e e f r o m w a t e r f o r t h e c a s e where (R=H, R'=Me). T h i s w a t e r p r e s u m a b l y o r i g i n a t e d f r o m i n c o m p l e t e d r y i n g o f t h e 2 - d i m e t h y l -a m i n o e t h a n e t h i o l ( s e c . 3.2.5) u s e d i n t h e l i g a n d s y n t h e s i s . To e l i m i n a t e t h e o c c u r r e n c e o f H 2 0 as a b y p r o d u c t i n t h e p r e p a r a -t i o n o f t h e 2 - d i m e t h y l a m i n o e t h a n e t h i o l , an a l t e r n a t e s y n t h e s i s o f t h e l i g a n d was d e s i g n e d ( s e c . 3 . 2 . 5 ) . An a l i q u o t o f t h e l i g s and was t h e n r e a c t e d w i t h Mn(CO),-Br as d e s c r i b e d a b o v e . The o r e s u l t i n g p r o d u c t was i s o l a t e d as an a i r s e n s i t i v e powder i n -65% y i e l d . - 58 -3.2.10 P r e p a r a t i o n o f t h e Complexes [ M e 2 G a ( p z " ) ( O C H 2 C H 2 S R ' ) ] R e ( C O ) 3 (R'=Ph o r E t ) The- a p p r o p r i a t e l i g a n d s were p r e p a r e d f r o m p h e n y l - 2 -h y d r o x y e t h y l s u l f i d e , HOCH 2CH 2SPh, o r e t h y l - 2 - h y d r o x y e t h y l -s u l f i d e , H OCH 2CH 2SEt, by t h e method d e s c r i b e d i n s e c t i o n 3.2.6 and r e a c t e d w i t h [ R e ( C O ) 4 C l l 2 . The d e s i r e d p r o d u c t s were r e -c r y s t a l l i z e d f r o m b e n z e n e and were i s o l a t e d as l a r g e , c o l o u r l e s s p r i s m s , i n -80% y i e l d s . P h y s i c a l d a t a f o r t h e s e c o m p l e x e s a r e summarized i n T a b l e V I I . 3.2.11 N i t r o s y l a t i o n o f LRe (CO) 3 (L= a u n i n e g a t i v e , t r i d e n t a t e p y r a z o l y l g a l l a t e l i g a n d ) LRe (CO) 3 + N 0 2 P F 6 »- LRe (CO) 2 ( N O ) + P F 6 ~ + C 0 2 The f o l l o w i n g g e n e r a l p r o c e d u r e was u s e d ; A s l i g h t e x c e s s o f N 0 2 P F g d i s s o l v e d i n C H 2 C 1 2 / a c e t o n i t r i l e was added d r o p w i s e t o L R e ( C O ) 3 d i s s o l v e d i n C H 2 C 1 2 . The a d d i -t i o n c a u s e d t h e s o l u t i o n t o b u b b l e v i g o r o u s l y and c hange f r o m c o l o u r l e s s t o brown. A f t e r s t i r r i n g t h e r e a c t i o n m i x t u r e f o r 5 min -200 ml o f d i e t h y l e t h e r was added, r e s u l t i n g i n t h e imme-d i a t e p r e c i p i t a t i o n o f a d a r k o r a n g e - b r o w n s o l i d . The e t h e r was d e c a n t e d o f f and t h e s o l i d d r i e d f o r ~-12 h in vacuo a t 50 °. P h y s -i c a l d a t a f o r t h e i s o l a t e d n i t r o s y l c a t i o n s , as w e l l as t h e s t a r t i n g t r i c a r b o n y l c o m p l e x e s , f o r c o m p a r a t i v e p u r p o s e s , a r e t a b u l a t e d i n T a b l e V I I I . NOPFg and NOBF^ were a l s o u s e d as n i t r o s y l a t i n g a g e n t s . However w i t h t h e s e n i t r o s o n i u m s a l t s r e a c t i o n t i m e s had t o be i n c r e a s e d t o ~8 h and, a l t h o u g h n i t r o s y l a t e d p r o d u c t s c o u l d , be T a b l e V I I . P h y s i c a l D a t a f o r I 0 M CO R* C O l * -1 A n a l y s i s H nmr i n C g D g , T (ppm) I R m C g H ^ f c m ) F o u n d ( % ) / C a l c ' d ( % )  R' m p ( ° C ) C H N Ga-Me p z - M e H 4 O ^ C H 2 - C H 2 - S 0-CH 2-_CH 2-S R' v c o P h 1 7 0 - 1 7 2 3 4 . 9 6 3.63 4.53 9 . 7 9 s 7 . 7 4 s 4 . 3 4 s 5 . 8 8 d d 8 . 1 9 t d 3.10m 2 0 2 8 3 4 . 9 5 3.56 4.53 1 0 . 2 7 s 8 . 0 2 s 6 . 7 5 t d 8 . 7 1 d d 1 9 4 0 1 9 1 6 E t 1 3 6 - 1 3 8 2 9 . 3 2 4.77 3.75 4 . 7 7 s 7 . 6 2 s 4 . 3 4 s 5 . 9 6 d d o,8.71td %7.62m 2 0 3 0 2 9 . 4 7 4 . 9 1 3.86 1 0 . 3 0 s 8 . 0 4 s 6 . 9 2 t d ^ 8 . 8 8 d d ^7.84m 1 9 2 5 9 . 2 3 t 1 9 0 1 * T C , H , = 2 . 8 4 ppm; s = s i n g l e t , t = t r i p l e t , m = m u l t i p l e t , d d = d o u b l e t o f d o u b l e t s t d = t r i p l e t o f d o u b l e t s T a b l e V I I I . IR and. 1 H nmr D a t a f o r LRe (CO) _ >- LRe (CO) - (NO) + P F / J 2 6 R e a c t a n t P r o d u c t I R ( c m ) V N 0 V P F C Ga-Me H nmr i n (CD-.)2CO, T (ppm) pz-rT p z - R -NMe, MeGa(pz) 3, R = H Reactant: 2028,1910 Product: 2038,1921 9 .32s 1827 a 830 a 10.01s 3.52t 1.83d,2.05d 3.28t 1.79d,2.10d Me-,Ga(pz) (OCH-,CH2NMe2) , R = H Reactant: 2020,1898,1873 Product: 2040,1930 10.19s,10.28s 3.50t 2.06d,2.16d 6.73s,7.51s 1815 b 833 b 9.98s 2.87 + 1.33 +,1.79 + 6.74s,6.78s Me 2Ga(pz 1 ]-) (OCH 2CH 2NMe 2) , b R = Me Reactant: 2015,1894,1869 Product: 2035,1920 1816 b 830 b 10.03s 10.17s,10.31s 3.95s 6.74s,7.52s 7.46s,7.73s 2.57s 6.79s,7.89s 6.76s MeCN + N u j o l T ( C H 3 ) 2 C O = 7.89 ppm; s = s i n g l e t , d = doublet ( J ^  2Hz), t = t r i p l e t ( J ^  2Hz) poor r e s o l u t i o n - 61 -i s o l a t e d , y i e l d s t e n d e d t o be l o w e r t h a n when NO„PF_ was u s e d . 2 6 (a) L = [ M e G a ( p z ) 3 ] ~ The c o r r e s p o n d i n g n i t r o s y l c a t i o n was v e r y a i r s e n s i t i v e , f o r m i n g i n -20% y i e l d . IR s p e c t r a i n d i c a t e d t h e s t a r t i n g r h e n i u m t r i c a r b o n y l t o be t o t a l l y consumed d u r i n g t h e c o u r s e o f t h e r e a c t i o n . (b) L= [Me 2Ga ( C 3 H N 2 R 2 ) (OCH 2CH 2NMe 2)-}~ (R=H o r Me) The c o r r e s p o n d i n g n i t r o s y l c a t i o n s were a g a i n v e r y a i r s e n s i t i v e and r e a c t i o n y i e l d s f l u c t u a t e d f r o m t r i a l t o t r i a l . E x t e n d e d d r y i n g in vacuo was r e q u i r e d t o remove s o l v a t e d E t 2 0 . (c) • L = [ M e 2 G a ( C 3 H N 2 R 2 ) ( S C H 2 C H 2 N R ' 2 ) ] " (R, R'=H o r Me) The s e n i t r o s y l c a t i o n s were d e t e c t e d s p e c t r o s c o p i c a l l y b u t c o u l d n o t be i s o l a t e d . D e c o m p o s i t i o n o f t h e d e s i r e d p r o -d u c t s o c c u r r e d r a p i d l y w h i l e a t t e m p t i n g t o i s o l a t e a s o l i d s p e c i e s . Mass s p e c t r a o f t h e i s o l a t e d n i t r o s y l c a t i o n s c o u l d n o t be o b t a i n e d due t o t h e i r i n v o l a t i l i t y . 3.2.12 R e a c t i o n s o f [ R e ( C O ) 2 ( N O ) C l 2 ] 2 i ) A f t e r r e f l u x i n g a THF s o l u t i o n o f [Re(CO) ( N O ) C l 2 ] 2 (.232 g, .411 mmol) and two m o l a r e q u i v a l e n t s o f N a + [ M e G a ( p z ) 3 ] f o r 3 h, a m i x t u r e o f p r o d u c t s was i s o l a t e d . A t t e m p t s t o s e p a r a t e t h i s m i x t u r e by c o l u m n c h r o m a t o g r a p h y r e s u l t e d i n t h e i s o l a t i o n o f o n l y two components w h i c h c o u l d be i d e n t i f i e d , - 62 -t h e s t a r t i n g d i m e r [ R e ( C O ) 2 ( N O ) C l 2 ] 2 and [Re(CO) ( N O ) C l 2 ( p z H ) ] . i i ) [ R e ( C O ) 2 ( N 0 ) C 1 2 1 2 (.730 g, 1.061 mmol) and P P h 3 (.558 g, 2.130 mmol) were s t i r r e d t o g e t h e r i n 100 ml THF o v e r -n i g h t . The r e a c t i o n m i x t u r e was t h e n c o n c e n t r a t e d down t o ~15 ml and 10 ml o f p e n t a n e a d d e d . T h i s m i x t u r e was p l a c e d i n t h e f r e e z e r f o r 48 h, a f t e r w h i c h t i m e y e l l o w c r y s t a l s o f [ R e ( C O ) 2 ( N O ) C l 2 ( P P h 3 ) ] h h a d s e p a r a t e d . T h e s e c r y s t a l s were c o l -l e c t e d and washed w i t h hexane i n t h e a i r . Y i e l d -64%. [ R e ( C O ) 2 ( N O ) C l 2 ( P P h 3 ) ] (.250 g, .413 mmol) was d i s s o l v e d i n 75 ml THF and one m o l a r e q u i v a l e n t o f N a + L (L= [ M e G a ( p z ) 3 ] o r [ M e 2 G a ( p z ) ( O C H 2 C H 2 N M e 2 ) ] } s u b s e q u e n t l y a d d e d . The r e a c t i o n s o l u t i o n was s t i r r e d f o r 24 h and t h e s o l v e n t removed in vacuo. The r e m a i n i n g y e l l o w r e s i d u e was e x t r a c t e d i n t o b e n z e n e and t h e e x t r a c t s f i l t e r e d . E v a p o r a t i o n o f t h e b e n z e n e ; l e f t a powder w h i c h c o n t a i n e d u n r e a c t e d [ R e ( C O ) 2 ( N O ) C l 2 ( P P h 3 ) ] and [ M e 9 G a ( M - p z ) ] 9 . 3.2.13 A t t e m p t e d H y d r i d e R e d u c t i o n o f a C o o r d i n a t e d C a r b o n y l LRe (CO) ( N O ) + + 'H~' T H F-> LRe (CO) (NO) (CHO) {L = [ M e G a ( p z ) 3 ] - o r [ M e 2 G a ( C 3 H N 2 R 2 ) ( O C H 2 C H 2 N M e 2 ) ] (R=H o r Me)} I n a t y p i c a l r e a c t i o n a s l i g h t e x c e s s o f a h y d r i d e s o u r c e i n THF { L i E t 3 B H o r L i [ C H ( C H 3 ) C 2 H 5 ] 3 B H } was s l o w l y added t o a s u s -p e n s i o n o f L R e ( C O ) 2 ( N O ) + i n t h e same s o l v e n t a t - 7 8 ° . The r e a c t i o n s o l u t i o n was s t i r r e d a t t h i s t e m p e r a t u r e f o r one h o u r and t h e volume r e d u c e d t o -5 m l . The r e a c t i o n f l a s k was t h e n - 63 -s e a l e d u n d e r N 2 and a l l o w e d t o s i t a t ~-10° f o r one week, a f t e r w h i c h t i m e no c r y s t a l s had f o r m e d i n t h e o r a n g e s o l u t i o n . Removal o f t h e s o l v e n t in vaouo l e f t a s t i c k y r e s i d u e w h i c h con-, t a i n e d no s p e c t r a l e v i d e n c e f o r a m e t a l f o r m y l o r a m e t a l h y d r i d e s p e c i e s . F o l l o w i n g a s l i g h t l y d i f f e r e n t p r o c e d u r e , t h e r e a c t i o n s o l u t i o n was a l l o w e d t o warm s l o w l y t o room t e m p e r a t u r e w i t h s t i r r i n g , f o l l o w i n g t h e a d d i t i o n o f 'H 1 a t - 7 8 ° . R e g u l a r IR s a m p l i n g w i t h a s y r i n g e d u r i n g t h i s t i m e gave no e v i d e n c e o f any. m e t a l - f o r m y l f o r m a t i o n . Removal o f t h e s o l v e n t in vaouo l e f t a complex m i x t u r e w h i c h c o n t a i n e d no "''H nmr o r IR e v i d e n c e f o r t h e p r e s e n c e o f a r e d u c e d m e t a l c a r b o n y l o r a met-a l h y d r i d e p r o d u c t . I n a d d i t i o n , no CO r e d u c t i o n was o b s e r v e d when t h e c o r r e -s p o n d i n g n e u t r a l p y r a z o l y l g a l l a t e s p e c i e s [i. ie. LRe (CO) ^] were e x p o s e d t o a h y d r i d e s o u r c e , u s i n g a s i m i l a r p r o c e d u r e t o t h a t j u s t d e s c r i b e d . 3.2.14 A t t e m p t e d P r e p a r a t i o n o f i ) L R e ( C O ) 2 ( P P h 3 ) { L = [ M e G a ( p z ) 3 ] " o r [ M e 2 G a j C 3 H N 2 R 2 M O C H 2 C H 2 N M e 2 ) ] " (R=H o r Me)} i i ) { [ M e 2 G a ( p z " ) ( O C H 2 C H 2 N M e 2 ) ] R e ( C O ) ( N O ) ( P P h 2 ) } + P F c " i ) R e f l u x i n g two m o l a r e q u i v a l e n t s e a c h o f t h e a p p r o p r i a t e l i g a n d , N a + L , and P P h 3 w i t h one m o l a r e q u i v a l e n t o f - 6 4 -[ R e ( C O ) 4 C l ] 2 o v e r n i g h t i n THF r e s u l t e d i n L R e ( C O ) 3 and f r e e P P h 3 . I r r a d i a t i o n o f L R e ( C O ) 3 and P P h 3 i n e i t h e r THF o r n-hexane was c a r r i e d o u t i n a w a t e r c o o l e d q u a r t z v e s s e l u s i n g a 4 5 0 w a t t H a n o v i a u l t r a v i o l e t lamp. The r e a c t i o n s o l u t i o n was k e p t u n d e r a N 2 a t m o s p h e r e . A f t e r 2 h t h e r e a c t i o n s o l u t i o n had cha n g e d f r o m c o l o u r l e s s t o y e l l o w , b u t IR s a m p l i n g i n d i c a t e d no f o r m a t i o n o f t h e d e s i r e d p r o d u c t . L o n g e r e x p o s u r e t o t h e u l t r a v i o l e t r a d i a t i o n p r o d u c e d a f u r t h e r d a r k e n i n g o f t h e r e a c -t i o n s o l u t i o n , b u t a g a i n no e v i d e n c e o f t h e d e s i r e d p r o d u c t . Removal o f t h e s o l v e n t l e f t a d a r k y e l l o w r e s i d u e f r o m w h i c h p u r e L R e ( C O ) 3 c o u l d be s u b l i m e d o u t . ( A f t e r 6 h e x p o s u r e , - 5 0 % L R e ( C O ) 3 was r e c o v e r e d ! ) i i ) When { [ M e 2 G a ( p z " ) ( O C H 2 C H 2 N M e 2 ) ] R e ( C O ) 2 ( N O ) } + P F 6 ~ was s u b -j e c t e d t o t h e same r e f l u x o r i r r a d i a t i o n c o n d i t i o n s as d e s -c r i b e d i n p a r t i ) , no p h o s p h i n e s u b s t i t u t i o n p r o d u c t s were ob-s e r v e d . A f t e r 3 h o f i r r a d i a t i o n , IR s a m p l i n g i n d i c a t e d t h a t no c a r b o n y l o r n i t r o s y l c o n t a i n i n g c o m p l e x e s r e m a i n e d i n t h e r e a c t i o n s o l u t i o n . Removal o f t h e s o l v e n t in vacuo l e f t a b l a c k s o l i d w h i c h was n o t f u r t h e r i d e n t i f i e d . F u r t h e r m o r e u s e o f e i t h e r x o d o s o b e n z e n e / a c e t o n r t r i l e o r t r i -e t h y l a m i n e / a c e t o n e vwas- n o t s u c c e s s f u l i n i n i t i a t i n g a p h o s p h i n e s u b s t i t u t i o n r e a c t i o n i n t h e n i t r o s y l c a t i o n ( 7 0 , 8 1 ) . 3-.2 . 1 5 , P r e p a r a t i o n o f Complexes I n c o r p o r a t i n g a C h i r a l L i g a n d , [ M e 2 G a ( p z " ) ( O C H 2 C * H R - N H 2 ) ] R e ( C O ) 3 (R=Me o r E t ) - 65 -The g a l l i u m l i g a n d s were p r e p a r e d as d e s c r i b e d i n s e c t i o n 3.2.6 f r o m t h e a p p r o p r i a t e c h i r a l a m i n o a l c o h o l and r e a c t e d w i t h [ R e ( C O ) 4 C l ] 2 as d e s c r i b e d i n s e c t i o n 3.2.2. R e c r y s t a l l i z a t i o n o f t h e c o m p l e x e s i n b e n z e n e r e s u l t e d i n w h i t e n e e d l e s o r powders o f t h e d e s i r e d p r o d u c t s i n -65-80% y i e l d s . S e l e c t e d p h y s i c a l d a t a f o r t h e s e c o m p l e x e s a r e t a b u l a t e d i n T a b l e IX. 3 . 3 R e s u l t s and D i s c u s s i o n 3.3.1 LM(CO) , (a) M = Re; L = [MeGa ( C ^ H N ^ ) ] " (R=H o r Me) (b) M = , Re; L = [Me 2Ga ( C ^ N ^ ) (OCH 2CH 2NR' ) ] " (R, R'=H o r Me) (c) M = Mn o r Re; L = . [Me 2Ga ( C 3 H N 2 R 2 ) (SO^CH^NR' 2 ) ] " (R, R'=H o r Me) (d) M = Re; L = [ M e 2 G a ( C 3 H N 2 R 2 ) ( O C H 2 C H 2 S R ' ) ] " (R=Me, R'=Et o r Ph) Ca) [ M e G a ( C 3 H N 2 R 2 ) 3 ] R e ( C O ) 3 (R=H o r Me) The s y m m e t r i c m e t h y l t r i s ( 1 - p y r a z o l y l ) g a l l a t e l i g a n d r e a c t e d w i t h [ R e ( C O ) 4 C l ] 2 f o r m i n g t h e o c t a h e d r a l , f a c i a l l y c o o r d i n a t e d s p e c i e s , [ M e G a ( p z ) 3 ] R e ( C O ) 3 . The c o o r d i n a t i o n g e o m e t r y o f t h e p r o d u c t was c o n f i r m e d by IR s p e c t r a l d a t a where two b a n d s , t h e a-^ and e modes,, were v i s i b l e i n t h e c a r b o n y l r e g i o n i n t h e ex-p e c t e d i n t e n s i t i e s f o r a f a c i a l , o c t a h e d r a l complex ( 5 3 ) . The "^H nmr s p e c t r u m o f t h e p r o d u c t was e a s i l y i n t e r p r e t a -b l e , s h o w i n g t h r e e e q u i v a l e n t p y r a z o l y l g r o u p s i n CgDg ( F i g . 2 0 ) . The p a r e n t peak i n t h e mass s p e c t r u m was a t t r i b u t a b l e t o Me H 4 T a b l e I X . S e l e c t e d P h y s i c a l D a t a f o r A n a l y s i s I R i n C 6 H 1 2 ( c m ) CD i n MeCN(M cm ) S t a r t i n g Amino F o u n d ( % ) / C a l ' d ( % )  R A l c o h o l * C H N v A e u u (262 nm)  Me L-2A1P 28.96 4.07 7.69 2 0 2 9 , 1 9 1 8 , 1 8 9 5 (+)3.24 28.95 3.90 7.79 E t d-2ALB 30.33 4.23 7.36 202 7,1920,1898 (+)2.92 30.39 4.19 7.59 E t £-2AlB 30.28 4.11 7.40 2025,1920,189 8 (-)5.14 30.39 4.19 7.59 2A1P = 2 - a m i n o - l - p r o p a n o l , 2A1B = 2 - a m i n o - l - b u t a n o l N o t e : t h e d e s i g n a t i o n o f c h i r a l i t y i s r e p o r t e d as t h e a l c o h o l s w e r e r e c e i v e d f r o m A l d r i c h C h e m i c a l Co. F i g u r e 20. Room t e m p e r a t u r e 27 0 MHz H nmr o f [ M e G a ( p z ) 3 ] R e ( C O ) 3 i n CgDg. - 68 -[ M e G a ( p z ) 3 ] R e ( C O ) 3 + ( 5 0 . 0 % ) . O t h e r s i g n a l s p r e s e n t c o r r e -sponded t o ( P - M e ) + ( 1 . 7 % ) , ( P - C O ) + ( 2 6 . 7 % ) , ( P - 2 C O ) + ( 2 4 . 1 % ) , ( P - 3 C O ) + ( 1 0 0 . 0 % ) , (P-Me-3CO) + (8.9%) and G a + ( 2 9 . 6 % ) . [ M e G a ( p z ) 3 ] R e ( C O ) ^ c r y s t a l l i z e d as l a r g e c u b i c , c o l o u r l e s s c r y s t a l s f r o m b e n z e n e . Once fo r m e d t h e s e a i r s t a b l e c r y s t a l s were o n l y s l i g h t l y s o l u b l e i n b e n z e n e and v e r y s o l u b l e i n THF and CH2CI2. An X - r a y s t r u c t u r e d e t e r m i n a t i o n on a s i n g l e c r y s t a l c o n f i r m e d t h e monomeric n a t u r e o f t h e p r o d u c t and t h e f a c 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 and t h e t h r e e t e r m i n a l CO g r o u p s . F i g u r e 21. M o l e c u l a r s t r u c t u r e o f [ M e G a ( p z ) 3 ] R e ( C O ) 3 . The r e a c t i o n o f t h e much more s t e r i c a l l ' y demanding l i g a n d [ M e G a ( p z " ) 3 ] ~ w i t h [ R e ( C O ) 4 C l ] 2 f a i l e d t o p r o d u c e d e f i n i t i v e r e s u l t s . A l t h o u g h s t a b l e c o m p l e x e s have p r e v i o u s l y b e en r e p o r t e d i n c o r p o r a t i n g t h i s t r i s ( 3 , 5 d i m e t h y l p y r a z o l y l ) g a l l a t e l i g a n d , i t has b e en n o t e d t h a t t h e l i g a n d o f t e n e x h i b i t s u n u s u a l b e h a v i o u r , p r e f e r r i n g t o c o n v e r t t o t h e l e s s s t e r i c a l l y d emanding [MeGa(pz") (QH)] t r i d e n t a t e l i g a n d when p o s s i b l e ( 5 8 ) . - 69 -Mass s p e c t r a l d a t a i n d i c a t e d t h e p r e s e n c e o f t h e d e s i r e d complex, [MeGa ( p z " ) 3 ] Re (CO)-j, among t h e r e a c t i o n p r o d u c t s f o r m e d . However, t h e "^ H nmr s p e c t r u m o f t h e o f f - w h i t e powder i s o l a t e d f r o m t h i s r e a c t i o n c o n t a i n e d a l a r g e number o f r e s o n a n c e s w h i c h c o u l d n o t be a s s i g n e d . The IR s p e c t r a o f t h i s same powder d i s p l a y e d numerous c a r b o n y l s t r e t c h e s , most o f w h i c h c o u l d be a s s i g n e d t o Re 2(CO)-^Q and Re(CO)-.Cl. A t t e m p t s a t s e p a r a t i n g t h e m i x t u r e o f p r o d u c t s were n o t s u c c e s s f u l and an a n a l y t i c a l l y p u r e sample o f [ M e G a ( p z " ) 3 ] R e ( C O ) 3 c o u l d n o t be o b t a i n e d . (b) [ M e 2 G a ( C 3 H N 2 R 2 ) ( O C H 2 C H 2 N R ' 2 ) ] R e ( C O ) 3 (R, R'=H o r Me) Unsymmetric t r i d e n t a t e p y r a z o l y l g a l l a t e l i g a n d s were f i r s t p r e p a r e d f r o m t h e r e a c t i o n o f N a + [ M e 3 G a ( p z ) ] and e t h a n o l a m i n e ( 3 4 ) . S t a b l e Mn, Mo, Cr and W (36) c a r b o n y l d e r i v a t i v e s have s i n c e b e e n r e p o r t e d i n c o r p o r a t i n g s u c h l i g a n d s y s t e m s . I t was n o t s u r p r i s i n g t o f i n d t h a t s i m i l a r u n s y m m e t r i c p y r a z o l y l -g a l l a t e l i g a n d s r e a c t e d r e a d i l y w i t h [ R e ( C O ) ^ C l ] 2 . f o r m i n g a s e r i e s o f s t a b l e , f u l l y c h a r a c t e r i z a b l e p r o d u c t s . U n l i k e [ M e G a ( p z ) 3 ] , t h e u n s y m m e t r i c l i g a n d s c a n p o t e n t i a l l y c o o r d i n a t e i n e i t h e r a f a c i a l o r m e r i d i o n a l f a s h i o n ( F i g . 2 2 ) . However m e r i d i o n a l c o o r d i n a t i o n o f these; l i g a n d s has n e v e r been o b s e r v e d i n p r e v i o u s l y p r e p a r e d t r a n s i t i o n m e t a l c a r b o n y l com-pounds. A g a i n , i n t h e r h e n i u m c o m p l e x e s d e s c r i b e d h e r e , f a c i a l a r r a n g e m e n t o n l y o f t h e l i g a n d was o b s e r v e d . E a c h o f t h e f o u r c o m p l e x e s d i s c u s s e d h e r e e x h i b i t e d t h r e e s h a r p bands i n t h e i r c a r b o n y l IR s p e c t r a , i n d i c a t i v e o f f a c i a l o r i e n t a t i o n o f t h e t h r e e c o o r d i n a t e d c a r b o n y l g r o u p s (53) ( T a b l e 70 -F i g u r e 22. P o s s i b l e m e r i d i o n a l (a) and f a c i a l (b) c o o r d i n a t i o n modes o f t h e u n s y m m e t r i c p y r a z o l y l g a l l a t e t r i d e n t a t e l i g a n d s . V I ) . A l s o i n t h e nmr s p e c t r a o f t h e s e compounds, two s h a r p s i n g l e t s i n t h e g a l l i u m a l k y l r e g i o n show t h a t t h e two m e t h y l g r o u p s on t h e g a l l i u m r e s i d e i n i n e q u i v a l e n t s t r u c t u r a l e n v i r o n -ments. T h i s i s i n a g r e e m e n t w i t h a f a c i a l l y c o o r d i n a t e d t r i -d e n t a t e l i g a n d as m e r i d i o n a l c o o r d i n a t i o n w o u l d r e s u l t i n s t r u c t u r a l l y e q u i v a l e n t GaMe 2 s u b s t i t u e n t s . "*"H nmr d a t a a r e summarized i n T a b l e X. The c a r b o n y l segment o f t h e IR s p e c t r u m and t h e "'"H nmr s p e c t r u m o f [ M e 2 G a ( p z ) ( O C H 2 C H 2 N M e 2 ) ] R e ( C O ) 3 a r e shown i n F i g u r e s 23 and 24 r e s p e c t i v e l y . These f i g u r e s a r e shown as t y p i c a l examples o f t h e s p e c t r a w h i c h were o b t a i n e d f o r e a c h o f t h e f o u r s p e c i e s d i s c u s s e d h e r e . A c r y s t a l s t r u c t u r e a n a l y s i s p e r f o r m e d on [Me^jGa (pz ") ( O C H 2 C H 2 N M e 2 ) ] R e ( C O ) ^ c o n f i r m e d t h e s t e r e o c h e m i s t r y o f t h i s m o l e c u l e as s u g g e s t e d by s p e c t r a l d a t a . I n F i g u r e 25 T a b l e X. u H nmr d a t a ...for T (ppm) i n C V D M R R' X Ga-Me H 4 R R' Mn H H S 9 . 8 3 s , 1 0 . l i s 3.87t 2.49d,2.68d Mn H Me S 9.92s,10.09s 3.86t 2 .24d,2.65d 8.08s,8.59s Mn Me H S 9.75s,,.10.11s 4 ,27s 7.88s ,7.94s Mn Me Me S 9.98s,10.03s 4.25s 7 .58s,7 .92s 8 .03s,8.60s Re H H 0 9.88s,10.33s 3.95t 2.49d,2.85d Re H Me 0 9.92s,10.26s 3.97t 2.43d,2.83d 7.76s,8.44s Re Me H 0 9.80s,10.28s 4.34s 7.80s,8.04s R e Me Me 0 9. 9.23,1a.2 0s 4 .32s 7.70s,8 .03s 7.70s,8.32s Re H H S 9.87s,10.14s 4 .04t 2.47d,2.83d Re H Me S 9.91s,10.06s 4 . O l t 2.40d,2.83d 7.91s,8.33s Re Me H S 9.76s,10.09s 4 .39s 7.87s,7.99s Re Me He S 10.01s,10.07s 4 .37s 7.66s,7.83s 7 .98s,8.41s * T C , - H , = 2.84 ppm; s = s i n g l e t , d = d o u b l e t ( J ^ 2Hz) , t = t r i p l e t ( J ^ 2Hz) - 72 -2100 2 0 0 0 1900 1800 cm F i g u r e 23. C a r b o n y l r e g i o n o f t h e C g H 1 2 s o l u t i o n IR s p e c t r u m o f [Me 2Ga(pz)• (OCH|GH 2NMe 2)]Re(CO) . t h e fGa-(N-N)-Re-Of f i v e " membered r i n g , f o r m e d upon c o o r d i n a t i o n o f t h e l i g a n d t o t h e r h e n i u m atom, c a n be s e e n t o l i e a p p r o x i -m a t e l y i n t h e p l a n e f o r m e d by t h e 3,5 d i m e t h y l p y r a z o l y l g r o u p . The t r i d e n t a t e l i g a n d and t h e t h r e e t e r m i n a l l y c o o r d i n a t e d CO g r o u p s a r e e a c h f a c i a l l y o r i e n t a t e d a r o u n d t h e o c t a h e d r a l r h e n i u m c e n t r e . Mass s p e c t r a were o b t a i n e d f o r t h e f o u r c o m p l e x e s d i s -c u s s e d h e r e and e a c h showed s i m i l a r f r a g m e n t a t i o n p a t t e r n s . A t y p i c a l a s s i g n m e n t i s t a b u l a t e d i n T a b l e X I , c o l u m n ( i ) . I n t h e mass s p e c t r a t h e p a r e n t i o n s i g n a l c o r r e s p o n d e d t o t h e m o l e c u l a r w e i g h t o f t h e e x p e c t e d monomeric s p e c i e s and t h e h i g h -e s t i n t e n s i t y m/e s i g n a l was a t t r i b u t a b l e t o t h e p a r e n t i o n minus a s i n g l e m e t h y l , i . e . "3P-rMe+.. f i g u r e 24. Room t e m p e r a t u r e 100 MHz H nmr s p e c t r u m o f [ M e 2 G a ( p z ) ( O C H 2 C H 2 N M e 2 ) ] R e ( C O ) 3 i n CgDg. - 74 -T a b l e XI Mass S p e c t r a l D a t a o f G a M CO = P C/i N M e a g \ R e l a t i v e I n t e n s i t i e s ( i ) ( i i ) ( i i i ) \. M Re Re Mn \ X 0 S S A s s i g n m e n t P + 25 .0 18.0 5.6 P-Me + 100.0 100.0 2.6 P-CO + 2.3 0.0 0.0 P-Me-CO + .9 1.4 t r a c e * P - 2 C 0 + 2.0 0.0 0.0 P-Me-2C0 + 4.4 7.3 3.9 P - 3 C 0 + t r a c e 2.4 100.0 P-Me-3C0 + 1.4 3.1 8.7 P-2Me-3CO + t r a c e 1.5 2.2 P-Me-3C0-pz + t r a c e 73.0 81.8 M + t r a c e t r a c e 4.0 M e 2 G a + 10.5 30.3 16 .1 G a + 11.1 24 .4 38 .2 p z H + 1.7 3.6 4.7 t r a c e = <.5 I F i g u r e 25. M o l e c u l a r s t r u c t u r e o f [ M e 2 G a ( p z " ) (OCH 2CH 2NMe 2)] Re (CO) 3 . (c) [ M e 2 G a ( C 3 H N 2 R 2 ) ( S C H 2 C H 2 N R 1 ) ] M ( C O ) 3 (R, R'=H o r Me; M=Mn o r Re) A s e r i e s o f f o u r new s u l f u r c o n t a i n i n g l i g a n d s were p r e p a r e d and r e a c t e d w i t h . [ R e ( C O ) 4 C 1 ] 2 and M n ( C O ) 5 B r . T h e s e l i g a n d s a r e v a l e n c e i s o e l e c t r o n i c t o t h o s e d i s c u s s e d i n p a r t ( b ) , t h e two s e r i e s d i f f e r i n g i n t h a t s u l f u r r e p l a c e s t h e p o s i t i o n p r e v i o u s l y o c c u p i e d by o x y g e n . I n g e n e r a l t h e t h i o a m i n o l i g a n d s r e a c t e d r e a d i l y w i t h t h e Mn and Re c a r b o n y l h a l i d e s . The e i g h t p r o d u c t s i s o l a t e d e a c h c o n t a i n a f a c i a l l y c o o r d i n a t e d t r i d e n t a t e l i g a n d and t h r e e m u t u a l l y c i s c a r b o n y l g r o u p s i n an o v e r a l l o c t a h e d r a l a r r a n g e -ment. The c o m p l e x e s were c h a r a c t e r i z e d by e l e m e n t a l a n a l y s e s , mass' s p e c t r o s c o p y , and IR and ' ^"H nmr d a t a as d e c r i b e d i n t h e p r e v i o u s s e c t i o n . I n t h e mass s p e c t r a o f t h e p r e s e n t t h i o a m i n o r h e n i u m com-- 76 -p l e x e s t h e f r a g m e n t a t i o n p a t t e r n s were a l m o s t i d e n t i c a l t o t h e a n a l o g o u s o x y g e n c o n t a i n i n g p r o d u c t s [ T a b l e X I , column ( i i ) ] . I n a d d i t i o n , t h e r e l a t i v e i n t e n s i t i e s were s i m i l a r w i t h t h e l a r g e s t m/e s i g n a l c o r r e s p o n d i n g t o t h e P-Me + i o n . A l t h o u g h t h e c o r r e s p o n d i n g manganese c o m p l e x e s a g a i n e x h i b i t e d s i m i l a r f r a g -m e n t a t i o n s , t h e r e l a t i v e i n t e n s i t i e s o f t h e i o n s were c o n s i s -t e n t l y d i f f e r e n t . A t y p i c a l a s s i g n m e n t i s i n c l u d e d i n T a b l e X I , c o l u m n ( i i i ) . I t i s o f i n t e r e s t t o n o t e t h a t w h i l e s m a l l s i g n a l s a r e a p p a r e n t f o r t h e P-Me + i o n when M=Mn, t h e l a r g e s t m/e s i g n a l i s a t t r i b u t a b l e t o P - 3 C 0 + . Thus t h e 'Mn-CO' bonds a r e weaker t h a n t h e 'Re-CO' b o n d s , i n agreement w i t h e x p e c t e d b e h a v i o u r when c o m p a r i n g i s o e l e c t r o n i c f i r s t and t h i r d row c a r b o n y l c o m p l e x e s o f t h e same g r o u p . A c o m p a r i s o n o f IR c a r b o n y l s t r e t c h i n g f r e q u e n c i e s ( T a b l e VI) r e i t e r a t e s what has b een c o n c l u d e d f r o m mass s p e c t r a l d a t a . R e p e a t e d l y l o w e r vCO v a l u e s f o r t h e r h e n i u m c o m p l e x e s o v e r t h e manganese s e r i e s i n d i c a t e s t h a t r h e n i u m i s c a p a b l e o f d o n a t i n g more e l e c t r o n d e n s i t y t o t h e c a r b o n y l l i g a n d s . T h i s r e s u l t s i n a l o w e r i n g o f t h e vCO v a l u e s due t o i n c r e a s e d M-CO b a c k b o n d i n g and i m p l i e s a s t r o n g e r 'M-CO' bond ( 6 8 ) . Some q u a l i t a t i v e o b s e r v a t i o n s c a n be made f r o m a c o m p a r i s o n o f t h e d a t a c o l l e c t e d on t h e c o m p l e x e s d e p i c t e d i n F i g u r e 26. I n g e n e r a l , w h i l e a l l c o m p l e x e s where (X=0) were a i r s t a b l e , t h e a n a l o g o u s c o m p l e x e s where (X=S) t e n d e d t o be a i r s e n s i t i v e . W i t h i n t h e s e r i e s where (X=S), r h e n i u m c o m p l e x e s were more s t a b l e i ) M=Re; X=0 o r S; R, R'=H o r Me R ( t h i s work) i i ) M=Mn; X=0; R, R'=H o r Me (36) R i i i ) M=Mn; X=S; R, R'=H o r Me ( t h i s work) X M CO C / i *• 8 F i g u r e 26. M e „ G a ( C Q H N „ R « ) ( X C H „ C H 0 N R ' „ ) M(CO) t h a n t h e c o r r e s p o n d i n g manganese a n a l o g s - t h e a i r s e n s i t i v e Re co m p l e x e s decomposed a f t e r s i t t i n g i n t h e a i r f o r 1-7 d a y s , w h i l e t h e most s e n s i t i v e Mn compounds decomposed i m m e d i a t e l y upon ex-p o s u r e t o a i r . I t has a l r e a d y b een n o t e d t h a t t h e c o m p l e x e s where (M=Re) h a v e e c o n s i s t e n t l y l o w e r vCO v a l u e s t h a n c o r r e s p o n d -i n g s p e c i e s where (M=Mn). O t h e r s u b s t i t u t i o n s a l s o a f f e c t e d t h e CO f r e q u e n c i e s . I n a n a l o g o u s c o m p l e x e s c h a n g i n g f r o m (X=S) t o (X=0) r e s u l t e d i n a d e c r e a s e i n vCO v a l u e s . I n a d d i t i o n t h e p r e s e n c e o f an a l k y l g r o u p a t t h e 'R' and 'R'" p o s i t i o n s o f t h e l i g a n d a l s o s h i f t e d t h e CO f r e q u e n c i e s t o l o w e r v a l u e s . T h i s l a t t e r p o i n t has been o b s e r v e d i n o t h e r t r i d e n t a t e p y r a z o l y l -g a l l a t e c o m p l e x e s ( 6 3 ) . Unsymmetric t r i d e n t a t e p y r a z o l y l g a l l a t e l i g a n d s o f f e r a p o t e n t i a l l y v e r s a t i l e s y s t e m f o r p r o b i n g t h e c o o r d i n a t i o n p r o -- 78 -p e r t i e s and b e h a v i o u r o f t r a n s i t i o n m e t a l s . B o t h t h e s t e r i c r e q u i r e m e n t and t h e e l e c t r o n d o n a t i n g s t r e n g t h o f t h e l i g a n d c a n be a l t e r e d by t h e i n c l u s i o n o f a l k y l s u b s t i t u e n t s i n t h e l i g a n d . T h i s has b e e n i l l u s t r a t e d by i n t r o d u c i n g m e t h y l g r o u p s a t p y r a z o l y l r i n g p o s i t i o n s a n d / o r one o f t h e l i g a n d d o n o r s i t e s ( i . e . t h e amino f u n c t i o n a l i t y ) . I n a d d i t i o n , t h e a f f e c t s o f i n t e r c h a n g i n g o x y g e n and s u l f u r as one o f t h e d o n o r s i t e s a t a p o s i t i o n a d j a c e n t t o t h e g a l l i u m atom has b e en d i s c u s s e d . I n t h e f o l l o w i n g s e c t i o n s i m i l a r t r i d e n t a t e l i g a n d s , m o d i f i e d a t t h e d o n o r s i t e r e m o t e f r o m t h e g a l l i u m atom, a r e c o n s i d e r e d . (d) [ M e 2 G a ( p z " ) ( O C H 2 C H 2 S R ' ) ] R e ( C O ) 3 (R'=Ph o r E t ) The s y n t h e s e s o f t h e t r i d e n t a t e 'SR'' l i g a n d s , and t h e i r c o m p l e x a t i o n t o v a r i o u s t r a n s i t i o n m e t a l s have b e e n d e t a i l e d ( 4 4 ) . These a n i o n i c l i g a n d s r e a c t e d r e a d i l y w i t h [ R e ( C O ) ^ C l ] 2 , f o r m i n g f a c i a l l y a r r a n g e d r h e n i u m t r i c a r b o n y l p r o d u c t s . T h e s e monomeric c o m p l e x e s were c h a r a c t e r i z e d by 1 H nmr and IR d a t a , e l e m e n t a l a n a l y s e s and mass s p e c t r a l d a t a as d e s c r i b e d i n e a r l i e r s e c t i o n s f o r s i m i l a r compounds. The mass s p e c t r a o f b o t h t h e r h e n i u m 'SPh' and ' S E t ' c o m p l e x e s were d o m i n a t e d by a m/e s i g n a l a t t r i b u t a b l e t o t h e p a r e n t i o n minus a s i n g l e m e t h y l ( 1 0 0 . 0 % ) . The h i g h e s t mass pe a k s v i s i b l e c o r r e s p o n d e d t o t h e p a r e n t i o n s , t h e i r i n t e n s i t i e s -20% o f t h e s t r o n g e s t p e a k s . S i g n a l s due t o t h e s u c c e s s i v e l o s s o f CO were v e r y weak and i n b o t h c a s e s t h e P - 3 C O + i o n was <3%. - 79 -A l t h o u g h numerous c o m p l e x e s have been r e p o r t e d c o n t a i n i n g t h e ' S E t ' l i g a n d o n l y one compound has p r e v i o u s l y b e en p r e p a r e d i n c o r p o r a t i n g t h e 'SPh' l i g a n d , t h a t i s [ M e 2 G a ( p z " ) (OCH 2CH 2SPh)] Mn(CO)..,. A t t e m p t s h a ve b e e n made t o c o o r d i n a t e N a + [ M e 2 G a ( p z " ) ( O CH 2CH 2SPh)] t o v a r i o u s t r a n s i t i o n m e t a l s , however t h i s 'SPh' l i g a n d r e f u s e s t o r e a c t i n t h e g e n e r a l manner d i s p l a y e d by t h e ' S E t ' l i g a n d . T h i s r e l u c t a n c e t o f o r m s t a b l e c o m p l e x e s has b e en a t t r i b u t e d t o t h e s i z e o f t h e 'SPh' m o i e t y i n c o m p a r i s o n t o t h e s t e r i c r e q u i r e m e n t o f t h e ' S E t ' g r o u p ( 4 4 ) . The 'SPh' l i g a n d r e a c t e d s m o o t h l y w i t h [ R e ( C O ) ^ C l ] 2 , t h e t r i c a r b o n y l p r o d u c t c r y s t a l l i z i n g a s l a r g e , c o l o u r l e s s a i r s t a b l e p r i s m s . An X - r a y c r y s t a l s t r u c t u r e a n a l y s i s on t h i s p r o d u c t was u n d e r t a k e n t o d e t e r m i n e t h e e n v i r o n m e n t a r o u n d t h e s u l f u r atom. I n F i g u r e 27 i t c a n be s e e n t h a t t h e s u l f u r s i t s a t t h e apex o f a p y r a m i d and the:, p h e n y l g r o u p i s o r i e n t a t e d i n s u c h a way t h a t i t has no c l o s e c o n t a c t w i t h a n y ' o t h e r p a r t o f t h e m o l e c u l e . I f t h i s i s t h e n o r m a l c o o r d i n a t i o n g e o m e t r y o f t h e l i g a n d [a s i m i l a r s t r u c t u r e has b e en d e t e r m i n e d f o r t h e a n a l o g o u s Mn compound (46)] , t h e n s t e r i c i n t e r f e r e n c e o f t h e p h e n y l g r o u p w o u l d n o t a p p e a r t o be a l o g i c a l e x p l a n a t i o n f o r t h e o b s e r v e d f a i l u r e t o f o r m 'SPh' a n a l o g s o f t h e s t a b l e ' S E t ' c o m p l e x e s . A l t h o u g h s t e r i c i n t e r f e r e n c e i n s o l u t i o n c a n n o t be r u l e d o u t , i t seems more l i k e l y t h a t d i f f e r e n c e s i n t h e e l e c t r o n i c p r o p e r t i e s o f t h e e t h y l and t h e p h e n y l s u b s t i t u e n t a c c o u n t f o r t h e ob-s e r v e d d i f f e r e n c e s i n t h e r e a c t i v i t i e s o f t h e two l i g a n d s . - 80 -F i g u r e 27. M o l e c u l a r s t r u c t u r e o f [ M e 2 G a ( p z " ) ( O C H 2 C H 2 S P h ) ] R e ( C O ) . A c o m p a r i s o n o f t h e "*"H nmr d a t a i n T a b l e V I I s u g g e s t s t h a t c h a n g i n g t h e R'' g r o u p does n o t s i g n i f i c a n t l y a f f e c t , t h e e l e c -t r o n i c e n v i r o n m e n t s o f t h e p r o t o n s i n t h e p y r a z o l y l g a l l a t e l i g a n d . Not u n e x p e c t e d l y t h e R 1 g r o u p p r i m a r i l y a f f e c t s , t h e '-O-CfL) -CH2~SR.' ' p r o t o n s , t h e p h e n y l g r o u p h a v i n g a s l i g h t d e s h i e l d i n g e f f e c t r e l a t i v e t o t h e c a s e where R'=Et. The c o n -s i s t e n t l y l o w e r vCO v a l u e s f o r t h e 'SEt' complex i n d i c a t e t h a t t h i s l i g a n d i s a b e t t e r e l e c t r o n d o n a t i n g g r o u p t h a n t h e 1 S P h 1 l i g a n d . I t may be t h i s s l i g h t d i f f e r e n c e i n e l e c t r o n d o n a t i n g a b i l i t y t h a t i s r e s p o n s i b l e f o r t h e g r e a t e r number o f 'SEt' c o m p l e x e s i s o l a t e d . - 81 -3.3.2 R e a c t i v i t y o f L ' R e ( C O ) 3 { L 1 = [ M e G a ( p z ) 3 ] o r [ M e 2 G a ( C 3 H N 2 R 2 ) ( O C H 2 C H 2 N M e 2 ) ] ~ (R=H o r Me)} (a) N i t r o s y l a t i o n o f L ' R e ( C O ) 3 (b) A t t e m p t e d r e d u c t i o n o f a c o o r d i n a t e d CO i n [ M e 2 G a ( C 3 H N 2 R 2 ) ( O C H 2 C H 2 N M e 2 ) ] R e ( C O ) 2 ( N O ) + (R=H o r Me) (c) A t t e m p t e d p r e p a r a t i o n o f L ' R e ( C O ) 2 ( P R ' 3 ) and [ M e 2 G a ( C 3 H N 2 R 2 ) (OCH 2CH 2NMe 2) ]Re(CO) (NO) ( P P h 3 ) + (R=H o r Me; R'=Ph, OPh o r OMe) A number o f r e p o r t s i n t h e l a s t few y e a r s have drawn a t t e n -t i o n t o t h e a b i l i t y o f t h e 1 (n 5-C-.H-.) Re (CO) (NO) 1 m o i e t y t o f o r m c o m p l e x e s o f uncommonly h i g h s t a b i l i t y w i t h o r g a n i c f u n c t i o n a l g r o u p s ( 6 9 - 7 2 ) . These n o v e l s p e c i e s a r e r e c o g n i z e d as p o t e n t i a l m odel compounds f o r t h e s t e p - b y - s t e p r e d u c t i o n o f c a r b o n mono-x i d e i n F i s c h e r - T r o p s c h t y p e p r o c e s s e s . The r e a c t i o n o f h y d r i d e w i t h (n 5-C-.H5) Re (CO) 2 (NO) + r e s u l t s i n a s e r i e s o f r e l a t i v e l y s t a b l e , n e u t r a l c o m p l e x e s ( 7 2 ) ; L"Re-CO*' >- L"Re-CHO >- L"Re-CH 2OH >- L"Re-CH 3 L" = ( n 5 - C 5 H 5 ) ( C O ) ( N O ) F o l l o w i n g t h e i s o l a t i o n o f e a c h o f t h e s e s p e c i e s , i t was s u b s e q u e n t l y q u e s t i o n e d w h e t h e r t h e (n5-C_.H_.) l i g a n d o r t h e Re m e t a l c e n t r e s e r v e t o s t a b i l i z e s u c h m o l e c u l e s . C o n s i d e r i n g t h e l i m i t e d number o f l i g a n d s y s t e m s f o r m a l l y a n a l o g o u s t o t h e c y c l o p e n t a d i e n y l g r o u p , i t seemed l i k e l y t h a t t h e t r i d e n t a t e p y r a z o l y l g a l l a t e a n i o n s m i g h t be f a v o u r a b l y s u i t e d t o t e s t i f t h e ( n 5 - C _ H ) g r o u p p l a y s a n e c e s s a r y r o l e i n t h e s t a b i l i z a t i o n o f 5 5 r e d u c e d c a r b o n y l r h e n i u m s y s t e m s . - 82 -From s t u d i e s on ( n 5 - C ^ H 5 ) R e ( C O ) 2 ( N O ) and r e l a t e d s p e c i e s t h e f o l l o w i n g o b s e r v a t i o n s h a v e been made; i ) r e d u c e d c a r b o n y l c o m p l e x e s o f t h e t h i r d row t r a n -s i t i o n m e t a l s t e n d t o be more s t a b l e t h a n t h o s e o f t h e f i r s t row, i i ) t h e s u b s t i t u t i o n o f a d o n o r l i g a n d s u c h a s 'PPh^ 1 f o r a 'CO' s t a b i l i z e s t h e r e d u c e d s p e c i e s [ i . e . ( n 5 - C 5 H 5 ) R e ( P P h 3 ) ( N O ) ( C H O ) i s s t a b l e a t room temp-e r a t u r e w hereas (ti5-C[-HI-) Re (CO) (NO) (CHO) has a h a l f -l i f e o f -3-10.h a t 25° ( 7 0 ) ] , i i i ) t h e s u b s t i t u t i o n o f t h e c y c l o p e n t a d i e n y l g r o u p i n ( n 5 - C 5 H 5 ) R e ( C O ) 2 ( N O ) + f o r a b e t t e r e l e c t r o n d o n o r s t a b i l i z e s t h e r e d u c e d s p e c i e s [ i . e . o r a n g e c r y s t a l s o f ( n 5 - C 5 M e 5 ) R e ( C O ) ( N O ) ( C H O ) a r e a i r s t a b l e t o 69° ( 7 2 ) ] and i v ) d e c o m p o s i t i o n o f t h e r e d u c e d CO s p e c i e s may . p r o c e e d v i a t h e d i s s o c i a t i o n o f a l a b i l e l i g a n d on t h e t r a n s i t i o n m e t a l c e n t r e [I..e. (n 5-C r-H r) Re (CO) (NO)H i s e x c e p t i o n a l l y s t a b l e compared t o o t h e r m e t a l h y d r i d e s . D e c o m p o s i t i o n o f t h i s h y -d r i d e d o e s n o t r e s u l t f r o m M-H h o m o l y s i s b u t i n -s t e a d t h r o u g h CO d i s s o c i a t i o n ] . T h ese f o u r p o i n t s i m p l y t h a t h y d r i d e r e d u c e d c a r b o n y l c o m p l e x e s c a n be s t a b i l i z e d by i n c r e a s i n g t h e e l e c t r o n - d e n s i t y on t h e t r a n s i t i o n m e t a l c e n t r e . A c o m p a r i s o n o f CO s t r e t c h i n g f r e q u e n c i e s o f t h e p r e s e n t p y r a z o l y l g a l l a t e c o m p l e x e s w i t h t h o s e o f s t r u c t u r a l l y s i m i l a r compounds i n d i c a t e s t h a t p y r a z o l y l g a l l a t e l i g a n d s a r e b e t t e r e l e c t r o n d o n a t i n g g r o u p s t h a n e i t h e r t h e c y c l o p e n t a d i e n y l r i n g o r - 83 -t h e p r e v i o u s l y s t u d i e d [ R B ( p z ) 3 ] .(R=H o r a l k y l ) l i g a n d s ( 6 3 ) . F o r t h i s r e a s o n i t was i n i t i a l l y b e l i e v e d t h a t L R e ( C O ) 3 s p e c i e s m i g h t a l s o s t a b i l i z e h y d r i d e r e d u c e d c o o r d i n a t e d c a r b o n y l m o i e -t i e s . T h e r e have been r e l a t i v e l y few n e u t r a l m e t a l l o - f o r m y l com-pounds p r e p a r e d , compared t o r t h e numerous a n i o n i c f o r m y l com-p l e x e s - k n o w n ( i . e . 7 3 and r e f e r e n c e s t h e r e i n ) . N e u t r a l r e d u c t i o n p r o d u c t s a p p e a r t o be more r e p r e s e n t a t i v e o f t h e i n t e r m e d i a t e s i n v o l v e d i n t h e F i s c h e r - T r o p s c h p r o c e s s . F o r t h i s r e a s o n o u r s t u d y b e g an w i t h t h e t r a n s f o r m a t i o n o f s t a b l e LRe (CO) 3 c o m p l e x e s i n t o c a t i o n i c s p e c i e s . (a) N i t r o s y l a t i o n o f L ' R e ( C O ) 3 { L' = [ M e G a ( p z ) 3 ] ~ o r [ M e 2 G a ( C 3 H N 2 R 2 ) ( O C H 2 C H 2 N M e 2 ) ] " (R=H o r Me)} ( n 5 - C ^ H ^ ) R e ( C O ) 3 c a n be r e a d i l y n i t r o s y l a t e d i n n e a r q u a n t i -t a t i v e y i e l d w i t h e i t h e r NOX (74) o r N O „ X f ( 7 5 ) (X=PF/_ o r B F . ) , r e s u l t i n g i n a y e l l o w , a i r s t a b l e p r o d u c t , (n 5-C,-H,-)Re(CO) 2(NO) + X . When a s i m i l a r n i t r o s y l a t i o n p r o c e d u r e was u s e d on L ' R e ( C O ) 3 e x t r e m e l y a i r s e n s i t i v e o r a n g e - b r o w n powders were i s o l a t e d i n v a r i a b l e y i e l d s . B a s e d upon s o l u b i l i t y p r o p e r t i e s , nmr d a t a and IR s p e c t r a t h e s e powders were i d e n t i f i e d t o be t h e d e s i r e d c a t i o n s , L 1 Re(CO) ( N O ) + P F g ~ ( T a b l e V I I I ) . A d e q u a t e e l e m e n t a l a n a l y s e s c o u l d n o t be c o n s i s t e n t l y o b t a i n e d due t o sample d e c o m p o s i t i o n and d i f f i c u l t y e n c o u n t e r e d i n r e m o v i n g t r a c e s o f r e s i d u a l s o l v e n t s , p r i m a r i l y E t ~ 0 , f r o m t h e p r o d u c t s . When L 1 = [MeGa(pz)-.] , n i t r o s y l a t i o n t h e o r e t i c a l l y c a n - 84 -o c c u r a t any one o f t h e t h r e e c a r b o n y l s i t e s on t h e r e a c t a n t and t h e same p r o d u c t w i l l r e s u l t . I n t h i s way [ M e G a ( p z ) ^ ] R e ( C O ) ^ i s s i m i l a r t o ( n 5 - C c H c ) Re (CO) _ . However, u n l i k e (n 5-C-.H-.) Re (CO) t h e m e t a t h e s i s o f a s i n g l e c a r b o n y l g r o u p f o r a d i s s i m i l a r l i g -and s h o u l d d e s t r o y t h e symmetry o f t h e c o o r d i n a t e d p y r a z o l y l -g a l l a t e l i g a n d ( F i g . 28) and i n e q u i v a l e n t p y r a z o l y l r i n g s s h o u l d be e v i d e n t i n t h e ''"H nmr s p e c t r u m i n a r a t i o o f 2:1. F i g u r e 28. The H nmr s p e c t r u m o f [ M e G a ( p z ) ^ ] R e ( C O ) 2 ( N O ) d i s p l a y e d o n l y one s e t o f p y r a z o l y l r e s o n a n c e s i n {CD^)^CO ( F i g . 2 9 ) . S p e c t r a r u n a t -50° and -70° show a s u b s t a n t i a l b r o a d e n i n g o f t h e s e r e s o n a n c e s , s u g g e s t i n g t h a t t h e c a t i o n i c n i t r o s y l s p e c i e s i s s t e r e o c h e m i c a l l y n o n r i g i d i n s o l u t i o n . A mechanism s i m i l a r t o t h e one d i s c u s s e d i n C h a p t e r I I ( F i g . 15) c o u l d a c c o u n t f o r t h e a p p e a r a n c e o f e q u i v a l e n t p y r a z o l y l r i n g s i n s o l u t i o n . I n t h i s c a s e t h e [MeGa(pz)^] l i g a n d w o u l d r e a r r a n g e v i a an i n t e r m e d i a t e s p e c i e s i n w h i c h t h i s l i g a n d i s c o o r d i n a t e d i n - 8 5 -a b i d e n t a t e manner { i . e . [(Me) (pz) Ga (pz) ^ ] }. 111 • 1 1 • i • •' i • | • < • • i • • • • | • • • • i • • \ • i • i ' 1 1 1 » i 1 2 3 4 T F i g u r e 29. V a r i a b l e t e m p e r a t u r e H nmr s p e c t r a o f t h e p y r a z o l y l r e g i o n (-1-4 x) o f [MeGa (pz) 3 ] R e (CO) 2 (NO) i n ( C D ^ C O . F l u x i o n a l i t y i n a m o l e c u l e i n c o r p o r a t i n g t h e [ M e G a ( p z ) 3 ] l i g a n d has n o t been p r e v i o u s l y o b s e r v e d . However, i t has r e -c e n t l y b e en r e p o r t e d t h a t r h o d i u m c o m p l e x e s c o n t a i n i n g t h e i s o -e l e c t r o n i c t r i d e n t a t e [ B ( p z ) 4 _ l i g a n d r e a r r a n g e i n s o l u t i o n a t e l e v a t e d t e m p e r a t u r e s . Thus t h e "*"H nmr s p e c t r a o f [ B ( p z ) ^ ] R h ( d i e n e ) X d i e n e = d u r o q u i n o n e , dq) c o n t a i n s o n l y one s e t o f p y r a z o l y l r e s o n a n c e s ( l e e . f o u r e q u i v a l e n t p y r a z o l y l g r o u p s ) a t 6 0 ° . However a c r y s t a l s t r u c t u r e a n a l y s i s on t h i s same r h o d i u m c o m p l e x i n d i c a t e s t h e p r e s e n c e o f a t r i d e n t a t e [ B ( p z ) ^ ] l i g a n d w i t h one p y r a z o l y l g r o u p t e r m i n a l l y c o o r d i n a t e d t o t h e b o r o n - 86 -atom. A low t e m p e r a t u r e H nmr s p e c t r u m o f [B (pz) ^ ] Rh (dq) d o e s c o n t a i n two s e t s o f p y r a z o l y l r e s o n a n c e s i n a r a t i o o f 3:1, c o n s i s t e n t w i t h t h e s o l i d s t a t e s t r u c t u r e (76, 7 7 ) . I n t h e p r e s e n t p y r a z o l y l g a l l a t e c a t i o n i t i s p o s s i b l e t h a t t h e n i t r o s y l g r o u p may be t o o s i m i l a r t o t h e c a r b o n y l g r o u p t o n o t i c e a b l y a l t e r t h e p y r a z o l y l r e s o n a n c e s i n t h e '''H nmr s p e c -t r a , t h e o b s e r v e d peak b r o a d e n i n g a t low t e m p e r a t u r e s a r i s i n g f r o m d e c r e a s e d sample s o l u b i l i t y . However, t h e "*"H nmr s p e c t r a o f t h e r e l a t e d n e u t r a l s p e c i e s , [ M e G a ( p z ) 3 ] M ( C O ) 2 ( N O ) (M=Mo o r W), c o n t a i n two s e t s o f r e s o n a n c e s a t t r i b u t a b l e t o two d i f f e r e n t t y p e s o f p y r a z o l y l p r o t o n s , i n t h e e x p e c t e d r a t i o o f 2:1 ( 3 1 ) . T h e r e f o r e , i t seems more l i k e l y t h a t t h e p r e s e n t c a t i o n i s i n d e e d s t e r e o c h e m i c a l l y n o n r i g i d i n s o l u t i o n . I n c o n t r a s t t o t h e s i n g l e n i t r o s y l a t e d L 1 R e ( C O ) 2 ( N O ) + p r o d u c t p o s s i b l e when L 1 i s a s y m m e t r i c t r i d e n t a t e l i g a n d , a number o f i s o m e r s c a n r e s u l t when L' i s an u n s y m m e t r i c p y r a -z o l y l g a l l a t e t r i d e n t a t e l i g a n d . T h e o r e t i c a l l y n i t r o s y l a t i o n o f [ M e 2 G a ( C 3 H N 2 R 2 ) ( O C H 2 C H 2 N M e 2 ) ] R e ( C O ) 3 (R=H o r Me) c o u l d t a k e p l a c e a t one o f t h r e e p o s s i b l e s i t e s , as shown i n F i g u r e 30. S u b s t i t u t i o n o f a CO g r o u p a t any one. o f t h e s e p o s i t i o n s would r e t a i n two u n i q u e g a l l i u m m e t h y l s u b s t i t u e n t s . T h e r e f o r e i n t h e g a l l i u m m e t h y l r e g i o n o f t h e "*"H nmr s p e c t r a one w o u l d e x p e c t a p o t e n t i a l maximum o f s i x s i n g l e t s , i f n i t r o s y l a t i o n i s o c c u r r i n g a t a l l t h r e e p o s i t i o n s , o r a min-imum o f two s i n g l e t s i f one s u b s t i t u t i o n i s f a v o u r e d . - 87 -M e , Z i ) t r a n s t o t h e e t h a n o l -amino o x y g e n , (X) i i ) t r a n s t o t h e e t h a n o l -amino n i t r o g e n , (Y) i i i ) t r a n s t o t h e p y r a -z o l y l n i t r o g e n , (Z) F i g u r e 30. CO s u b s t i t u t i o n s i t e s i n [ M e 2 G a ( C 3 H N 2 R 2 ) ( O C H 2 C H 2 N M e 2 ) ] R e ( C O ) 3 (R=H o r Me) The "*"H nmr s p e c t r a o f b o t h u n s y m m e t r i c n i t r o s y l a t e d p r o -d u c t s r e p o r t e d -here c o n t a i n one s i n g l e t o n l y ' f o r t h e i r g a l l i u m m e t h y l g r o u p s ( i n t e g r a t i o n s i x p r o t o n s ) i n ( C D 3 ) 2 C O a t room t e m p e r a t u r e . I n a d d i t i o n f o r t h e c a s e where (R=Me), t h e 'N-Me 2' r e s o n a n c e i s a l s o a s i n g l e t ( i n t e g r a t i o n s i x p r o t o n s ) i n s t e a d o f t h e e x p e c t e d p a i r o f s i n g l e t s . T h i s w o u l d s u g g e s t t h a t t h e s e n i t r o s y l c a t i o n s a r e a l s o f l u x i o n a l i n s o l u t i o n . To c o n f i r m t h i s p r o p o s a l a low t e m p e r a t u r e "^ H nmr s p e c t r u m o f liMe 2Ga(pz") (OCH 2CH 2NMe 2) ] R e ( C O ) 2 ( N O ) + P F 6 ~ was o b t a i n e d . A t -7 0° b o t h t h e g a l l i u m m e t h y l s i n g l e t and t h e e t h a n o l -amino m e t h y l s i n g l e t a p p e a r e d t o be c o l l a p s i n g . However t h e t e m p e r a t u r e c o u l d n o t be l o w e r e d enough t o r e s o l v e two p a i r s o f s i n g l e t s as wo u l d be e x p e c t e d f o r a r i g i d m o l e c u l e . The r e l a t e d a n i o n i c s p e c i e s [ Me 2Ga (pz ") (OCH 2CH 2NMe 2) ].M (CO) ^  (M=Cr, Mo o r W) have a l s o b e en o b s e r v e d t o be s t e r e o c h e m i c a l l y - 8 8 -n o n r i g i d i n s o l u t i o n ( 6 3 ) . A mechanism has b e e n p r o p o s e d whereby a b r e a k i n g o f t h e 'N-Me2' bond o c c u r s , f o l l o w e d by r e a r r a n g e m e n t o f t h e r e s u l t i n g 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 and r e f o r m i n g o f t h e 'M-NMe2' bond. T h i s mechanism r e s u l t s i n t h e a p p e a r a n c e o f one s i n g l e t e a c h f o r t h e two g a l l i u m m e t h y l s and t h e two e t h a n o l a m i n o m e t h y l s i n t h e "^H nmr s p e c t r u m i f a ' f a s t ' e q u i l i b r i u m . . i s t a k i n g p l a c e . I f i t i s assumed t h a t a s i m i l a r mechanism i s o c c u r r i n g i n t h e p r e s e n t n i t r o s y l c a t i o n s , n i t r o s y l a t i o n c a n o n l y be t a k i n g p l a c e i n t h e Z p o s i t i o n , t r a n s t o t h e p y r a z o l y l n i t r o g e n . I f n i t r o s y l a t i o n were t o o c c u r a t e i t h e r t h e X o r Y p o s i t i o n s , s u c h a f l u x i o n a l mechanism w o u l d r e s u l t i n d i a s t e r e o m e r s . An example o f t h i s i s i l l u s t r a t e d i n F i g u r e 31. T h e r e was no e v i d e n c e f o r d i a s t e r e o m e r s i n t h e "'"H nmr s p e c t r a r e c o r d e d . F i g u r e 31. D i a s t e r e o m e r s (a) and (b) r e s u l t i n g i f n i t r o s y l a t i o n were t o o c c u r a t t h e X p o s i t i o n . - 8 9 -E x a m i n a t i o n o f t h e c r y s t a l s t r u c t u r e o f [Me 2Ga(pz") ( O C H 2 C H 2 N M e 2 ) ] R e ( C O ) 3 ( F i g . 2 5 ) , t o g e t h e r w i t h m o l e c u l a r m o d e l s , i n d i c a t e t h e Z p o s i t i o n t o be t h e s t e r i c a l l y f a v o u r e d p o s i t i o n f o r b u l k y s u b s t i t u e n t s . S t e r i c f a c t o r s have p r e v i o u s l y b e en r e p o r t e d t o p l a y a m a j o r r o l e i n t h e r e s u l t i n g s t e r e o c h e m i s t r y o f r e l a t e d c o m p l e x e s , c f . L M o ( C O ) 2 ( n 3 - C 4 H 7 ) (37) and L M o ( C O ) 2 ( n 3 - c 7 H 7 ) ( 4 5 ) . (b) ^-Attempted H y d r i d e R e d u c t i o n o f [Me 2Ga ( C 3 H N 2 R 2 ) ( O C H 2 C H 2 N M e 2 ) ] R e ( C O ) 2 ( N O ) + P F 6 ~ (R—H o r Me) R e a c t i o n o f t h e p y r a z o l y l g a l l a t e r h e n i u m n i t r o s y l c a t i o n s w i t h e i t h e r L i E t 3 B H o r L i B [ C H 2 ( C H 3 ) C 2Hj- ] 3 H r e s u l t e d i n complex m i x t u r e s o f d e c o m p o s i t i o n p r o d u c t s w h i c h were n o t s e p a r a t e d . —H-nmr-and" IR - s p e c t r a "of' t h e + r e a c t i o n p r o d u c t s d i d ' - •- ~ h o t - i n d i c a t e t h e p r e s e n c e o f any m e t a l fbrmy-1 o r m e t a l h y d r i d e s p e c i e s . I n t h e '''H nmr s p e c t r a o f t h e r e a c t i o n s o l u t i o n s , t h e g a l l i u m m e t h y l r e s o n a n c e s had d i s a p p e a r e d and new r e s o n a n c e s c h a r a c t e r i s t i c o f f r e e p y r a z o l e [i...e., C 3 H 2 N 2 R 2 (R=H o r Me)'] c o u l d be i d e n t i f i e d , i n d i c a t i n g t h a t t h e p y r a z o l y l g a l l a t e l i g a n d i t s e l f was u n s t a b l e i n t h e r e a c t i o n c o n d i t i o n s u s e d . From t h e s e a t t e m p t e d h y d r i d e r e a c t i o n s i t became a p p a r e n t t h a t t h e same p r o p e r t i e s w h i c h make t h e p y r a z o l y l g a l l a t e l i g a n d s u n i q u e h i n d e r t h e i r u s e f u l n e s s as g e n e r a l c o m p a r a t i v e m o d e ls f o r c y c l o p e n t a d i e n y l c h e m i s t r y . \En t h e u-bonded c y c l o -p e n t a d i e n y l complex, r a p i d r o t a t i o n o f t h e On ^ F.CwHjL) -group '•makes e a c h 'CH' s e c t i o n o f t h e r i n g e q u i v a l e n t i n s o l u t i o n and c o n s e -- 90 -q u e n t l y any n e t c h a r g e p r e s e n t i s d i s t r i b u t e d e q u a l l y a r o u n d t h e r i n g . I n c o n t r a s t t h e a-bonded p y r a z o l y l g a l l a t e l i g a n d s bond t o t h e t r a n s i t i o n m e t a l v i a t h r e e c o o r d i n a t e bonds and t h e d i s t r i b u t i o n o f c h a r g e i s u n e v e n t h r o u g h o u t t h e l i g a n d . T h e r e f o r e , w h i l e t h e s u p e r i o r e l e c t r o n d o n a t i n g a b i l i t y o f t h e p y r a z o l y l g a l l a t e l i g a n d s may t h e o r e t i c a l l y s t a b i l i z e h y d r i d e r e d u c e d c o o r d i n a t e d CO g r o u p s , t h e h y d r i d e s o u r c e s a l s o a p p e a r t o be r e a c t i v e t o w a r d s t h e t r i d e n t a t e l i g a n d , r e s u l t i n g i n de-c o m p o s i t i o n o f t h e i n i t i a l r h e n i u m s t a r t i n g m a t e r i a l . The r e a c t i v i t y o f p y r a z o l y l l i g a n d s has b e e n p r e v i o u s l y r e p o r t e d . F o r example, a l t h o u g h (n 5-C-.H-.) Re (CO) c a n be b r o m i -CR=H o r Me, R'=H o r Me) F i g u r e 32. T T - b o n d e d (n 5-C 5H-.) and a-bonded [Me 2Ga ( C 3 H N 2 R 2 ) (OCH 2CH 2NR' ! 2) ] " l i g a n d s i n 'Re(CO) 1 c o m p l e x e s . - 91 -n a t e d , y i e l d i n g ( n 5 - C 5 H 5 ) R e ( C O ) 2 B r 2 {Eq. [5]} ( 7 8 ) , b r o m i n a t i o n o f t h e r e l a t e d i s o s t r u c t u r a l c omplex, [ HB (pz") ... ] Re (CO) 3 , r e -s u l t e d i n none o f t h e e x p e c t e d d i c a r b o n y l p r o d u c t . I n s t e a d b r o m i n a t i o n a t t h e C(4) p o s i t i o n s o f t h e p y r a z o l y l r i n g s was o b s e r v e d , as shown i n e q u a t i o n [6] ( 7 9 ) . Br The h y d r i d e r e d u c t i o n s d i s c u s s e d i n t h i s s e c t i o n were a t t e m p t e d on t h e p r e m i s e t h a t i n c r e a s i n g t h e e l e c t r o n d e n s i t y a t t h e r h e n i u m atom w o u l d e f f e c t i v e l y s t a b i l i z e m o l e c u l e s c o n t a i n -i n g r e d u c e d CO f u n c t i o n a l g r o u p s . However i n c r e a s i n g t h e e l e c t r o n - 92 -d e n s i t y on t h e m e t a l c e n t r e a l s o r e s u l t s i n i n c r e a s i n g t h e d e g r e e o f b a c k b o n d i n g t o t h e c a r b o n y l l i g a n d s c o o r d i n a t e d t o t h i s m e t a l . B e c a u s e t e r m i n a l CO g r o u p s p o s s e s s an o v e r a l l c h a r g e s e p a r a t i o n ( F i g . 3 3 ) , t h i s i n c r e a s e d b a c k b o n d i n g l e a d s t o a d e c r e a s e i n t h e p a r t i a l p o s i t i v e c h a r g e r e s i d i n g ; o n . ' t h e c a r b o n . A d e c r e a s e d p o s i t i v e c h a r g e c a n r e s u l t i n t h e c a r b o n o f t h e c o o r d i n a t e d CO g r o u p n o t b e i n g s u f f i c i e n t l y a c t i v a t e d f o r n u c l e o p h i l i c a t t a c k t o t a k e p l a c e . T h i s may be a c o n t r i -b u t i n g f a c t o r f o r t h e l a c k o f h y d r i d e r e d u c e d c o o r d i n a t e d CO p r o d u c t s r e s u l t i n g f r o m t h e p r e s e n t p y r a z o l y l g a l l a t e m o l e c u l e s . <T+ a-L — M — C = 0 F i g u r e 33. (c) A t t e m p t e d P r e p a r a t i o n o f L 1 R e ( C O ) 2 ( P R 1 3 ) {L 1 = [ M e G a ( p z ) 3 ] ~ o r [ M e 2 G a ( C 3 H N 2 R 2 ) ( O C H 2 C H 2 N M e 2 ) ] ~ ; R=H o r Me; R'=Ph, OPh o r OMe } and [ M e 2 G a ( C 3 H N 2 R 2 ) ( O C H 2 C H 2 N M e 2 ) ] R e ( C O ) ( N O ) ( P P h 3 ) + (R=H o r Me) ( n 5 - C 5 H 5 ) R e ( C O ) 2 ( P P h 3 ) has b een p r e p a r e d by t h e i r r a d i a t i o n o f (n 5-C_.Hj-) Re (CO) 3 and P P h 3 i n THF ( 8 0 ) . T h e c o r r e s p o n d i n g c a t -i o n ( n 5 - C 5 H 5 ) R e ( C O ) ( N O ) ( P P h 3 ) + c a n be q u a n t i t a t i v e l y p r e -p a r e d by r e f l u x i n g (n 5-C^Hj-) R e ( C O ) 2 ( N O ) + and P P h 3 i n t h e p r e s e n c e o f E t 3 N (81) o r i o d o s o b e n z e n e ( 7 0 ) . I n c o n t r a s t t o t h e s e r e s u l t s i t was f o u n d t h a t t h e c a r b o n y l g r o u p s i n b o t h L ' R e ( C O ) 3 and [ M e 2 G a ( C 3 H N 2 R 2 ) ( O C H 2 C H 2 N M e 2 ) ] R e ( C O ) 2 ( N O ) + (R=H o r Me) were i n e r t t o w a r d s s u b s t i t u t i o n . - 93 -When t h e L ' R e ( C O ) 3 c o m p l e x e s were r e f l u x e d i n THF w i t h a s u i t a b l e t e r t i a r y p h o s p h i n e , o n l y t h e s t a r t i n g r h e n i u m compound and f r e e p h o s p h i n e c o u l d be i s o l a t e d . I r r a d i a t i o n o f t h e same r e a c t i o n m i x t u r e w i t h u l t r a v i o l e t l i g h t d i d n o t i n i t i a t e a s u b s t i t u t i o n r e a c t i o n . The i r r a d i a t i o n o f t h e n i t r o s y l c a t i o n s , [ M e 2 G a ( C ^ N ^ ) ( O C H 2 C H 2 N M e 2 ) ] R e ( C O ) ( N O ) + , w i t h PPh^ r e s u l t e d i n e x t e n s i v e d e c o m p o s i t i o n as e v i d e n c e d by t h e t o t a l l o s s o f a l l c a r b o n y l and n i t r o s y l s t r e t c h e s i n t h e IR o f t h e r e a c t i o n s o l u t i o n . The a d d i t i o n o f E t ^ N o r i o d o s o b e n z e n e d i d n o t change t h e outcome o f . t h i s r e a c t i o n . Good e v i d e n c e has r e c e n t l y been p r e s e n t e d i n s u p p o r t o f an a s s o c i a t i v e mechanism f o r p h o s p h i n e s u b s t i t u t i o n r e a c t i o n s o f ( n 5 - C ^ H ^ ) R e ( C O ) 3 ( 8 2 ) . I n t e r m e d i a t e c o m p l e x e s have been i s o -l a t e d w h i c h d e m o n s t r a t e t h e a b i l i t y o f t h e c y c l o p e n t a d i e n y l r i n g t o ' s l i p 1 , t h u s a l l o w i n g t h e p h o s p h i n e t o bond t o t h e now 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 m e t a l c e n t r e . The l a c k o f an open c o o r d i n a t i o n s i t e c a n n o t be r u l e d o u t as F i g u r e 34. A s s o c i a t i v e p h o s p h i n e s u b s t i t u t i o n o f ( n 5 - C 5 H 5 ) R e (CO) 3 . - 94 -a p o s s i b l e e x p l a n a t i o n t o a c c o u n t f o r t h e o b s e r v e d u n r e a c t i v i t y o f t h e p r e s e n t p y r a z o l y l g a l l a t e r h e n i u m c o m p l e x e s w i t h r e g a r d t o p h o s p h i n e s u b s t i t u t i o n . However, w h i l e t h e p y r a z o l y l g a l l a t e l i g a n d s do n o t p o s s e s s t h e p o t e n t i a l f o r ' s l i p p a g e ' , i t has a l r e a d y been shown t h a t t h e t r i d e n t a t e l i g a n d s a r e o f t e n f l u x i o n -a l i n s o l u t i o n . The mechanism p r o p o s e d i n v o l v e s a b r e a k i n g o f t h e 'M-NMe2' bond ( i . e . . as in- F i g . 31) and t h i s - i m p l i e s t h a t a 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 r h e n i u m s p e c i e s e x i s t s a s an i n t e r -m e d i a t e . The f a c i l e b r e a k a g e o f t h i s bond w o u l d p r o v i d e a r o u t e f o r p h o s p h i n e s u b s t i t u t i o n v i a an a s s o c i a t i v e mechanism, b u t . o n l y i f a 'M-CO' bond c a n be s u b s e q u e n t l y b r o k e n . The o b s e r v e d n o n l a b i l i t y o f t h e t e r m i n a l l y c o o r d i n a t e d CO l i g a n d s i n t h e p r e s e n t p y r a z o l y l g a l l a t e r h e n i u m c o m p l e x e s a g a i n r e f l e c t s t h e s u p e r i o r e l e c t r o n d o n a t i n g s t r e n g t h o f t h e g a l l a t e t r i d e n t a t e l i g a n d s compared t o t h e c y c l o p e n t a d i e n y l g r o u p . R e a c t i o n s o f [Re(CO) ( N O ) C l 2 ] 2 and [Re(CO) ( N O ) C l 2 ( P P h 3 ) ] w i t h N a + L ~ {L = [ M e G a ( p z ) 3 ] o r [ M e 2 G a ( p z ) ( O C H 2 C H 2 N M e 2 ) ] } were u n d e r t a k e n i n an a t t e m p t t o i n t r o d u c e e i t h e r a p h o s p h i n e o r a n i t r o s y l l i g a n d i n t o a p y r a z o l y l g a l l a t e r h e n i u m complex v i a a d i f f e r e n t r o u t e t h a n t h o s e a l r e a d y d i s c u s s e d . No new p y r a z o l y l g a l l a t e r h e n i u m s p e c i e s were i s o l a t e d f r o m t h e s e r e a c t i o n s . - 95 -3.3.3 L Re (CO)-, L = [ Me,,Ga (pz " ) •(OCHyC H R - N H j ] " (R=Me o r E t ) A c h i r a l c a r b o n c e n t r e was i n c o r p o r a t e d i n t o u n s y m m e t r i c m o n o ( 1 - p y r a z o l y l ) g a l l a t e l i g a n d s by t h e r e a c t i o n o f a p p r o p r i a t e c h i r a l a m i n o a l c o h o l s w i t h N a + [ M e ^ G a ( p z " ) ] . N o v e l s t e r e o c h e m -i c a l a r r a n g e m e n t s r e s u l t e d upon t h e c o m p l e x a t i o n o f t h e s e l i g a n d s t o a r h e n i u m c e n t r e . I t i s p r o p o s e d t h a t s t e r i c c o n s i d e r a -t i o n s a r e a m a j o r f a c t o r i n f l u e n c i n g w h i c h d i a s t e r e o m e r i s t h e d o m i n a n t i s o m e r f o r m e d . T h r e e t r i d e n t a t e a n i o n i c l i g a n d s were p r e p a r e d f r o m com-m e r c i a l l y a v a i l a b l e c h i r a l a m i n o a l c o h o l s . T h e s e l i g a n d s r e a d i l y r e a c t e d w i t h [ R e ( C O ) 4 C l ] 2 f o r m i n g a i r s t a b l e , monomeric, f a c i a l l y c o o r d i n a t e d t r i c a r b o n y l p r o d u c t s . These c o m p l e x e s were f u l l y c h a r a c t e r i z a b l e by e l e m e n t a l a n a l y s e s and IR s p e c t r o -s c o p y ( T a b l e I X ) , and mass s p e c t r a l a n a l y s e s as d e s c r i b e d f o r s i m i l a r compounds i n p r e v i o u s s e c t i o n s . The c i r c u l a r d i c h r o i s m (CD) s p e c t r a o f t h e o p t i c a l l y a c t i v e p y r a z o l y l g a l l a t e compounds were o b t a i n e d and t h e d i f -f e r e n c e i n e x t i n c t i o n c o e f f i c i e n t s , A e ( T a b l e I X ) , d e t e r m i n e d by u s e o f t h e f o l l o w i n g e q u a t i o n a t 262 nm; s i g n a l h e i g h t (cm) s c a l e (deg/cm) c o n s t a n t ( a b s o r b a n c e u n i t s / d e g ) sample c o n c e n t r a t i o n (M) p a t h l e n g t h o f sample c e l l (cm) Ae = e T - e_ =. w where H L R cZ g K c I - 96 -T r i c a r b o n y l r h e n i u m c o m p l e x e s i n c o r p o r a t i n g a f a c i a l l y c o o r d i n a t e d p y r a z o l y l g a l l a t e l i g a n d c o n t a i n i n g a c h i r a l c a r b o n may be one o f two p o s s i b l e d i a s t e r e o m e r s . T h e s e d i a s t e r e o m e r s have been d e s i g n a t e d ' c i s ' when t h e R g r o u p i s on t h e same s i d e o f t h e t r a n s i t i o n m e t a l a s t h e p y r a z o l y l g r o u p and ' t r a n s ' when t h e R g r o u p i s on t h e o p p o s i t e s i d e o f t h e t r a n s i t i o n m e t a l as t h e p y r a z o l y l g r o u p . B o t h d i a s t e r e o m e r s have a n o n s u p e r -i m p o s a b l e m i r r o r image, t h e r e f o r e i n t h e o r y f o u r s t e r e o i s o m e r s a r e p o s s i b l e h a v i n g t h e f o r m u l a t i o n [ M e 2 G a ( p z " ) ( O C H 2 C * H R - N H 2 ) ] Re (CO)..., a s shown i n F i g u r e 35. The 1 H nmr s p e c t r u m o f ( + ) ^ £ [Me-,Ga (pz") (2A1P) ]Re (CO) 3 ( i . e . 2A1P when R=Me, 2A1B when R=Et) i s shown i n F i g u r e 36 ( i ) . The a s s i g n m e n t o f t h e a m i n o a l c o h o l r i n g p r o t o n s was c o n f i r m e d by d o u b l e r e s o n a n c e e x p e r i m e n t s , F i g s . 3 6 ( i i ) - ( v i i ) . I n t h e s e s p e c t r a two s e t s o f s i g n a l s a r e v i s i b l e f o r e a c h u n i q u e p r o t o n i n a r a t i o o f a p p r o x i m a t e l y 3:1, c o r r e s p o n d i n g t o t h e t r a n s and c i s d i a s t e r e o m e r s r e s p e c t i v e l y . From s t e r i c a rguments t h e t r a n s i s o m e r w o u l d be e x p e c t e d t o be t h e more f a v o u r a b l e p r o d u c t , as i n t e r a c t i o n between t h e R s u b s t i t u e n t . a n d t h e p y r a z o l y l m o i e t y r e s u l t s when t h e R g r o u p i s i n t h e c i s p o s i t i o n . Thus i n C r D r t h e t r a n s i s o m e r i s p r e s e n t i n a b o u t a t h r e e - f o l d e x c e s s o v e r t h e c i s i s o m e r . I t i s o f i n t e r e s t t o n o t e t h a t when t h e "*"H nmr s p e c t r u m o f t h e same complex was r e c o r d e d i n (CD.-,)2CO t h e t r a n s : c i s r a t i o i n c r e a s e d t o 10:1. S i m i l a r "*"H nmr be h a -v i o u r was o b s e r v e d f o r e a c h o f t h e comp l e x e s l i s t e d i n T a b l e IX - one d i a s t e r e o m e r ( p r e s u m a b l y t h e t r a n s ) a l w a y s e x i s t i n g as t h e m a j o r i s o m e r i n s o l u t i o n . C o m p l e t e "*"H nmr a s s i g n m e n t s a r e t a b u l a t e d i n T a b l e X I I . - 9 7 -Figure 3 5 . P o s s i b l e stereoisomers f o r [Me 2Ga(pz")(OCH 2C*HR-NH 2)3Re(C0) - 98 -(i) (ii) ( i i i ) T 7 - T " 8 •nr-io Figure 36. (i) Room temperature 4 00 MHz H nmr spectrum of [Me2Ga(pz")(2A1P)]Re(CO)3 xn C6 D6 (pz-H proton is omitted) ( i i ) - ( v i i ) Effect of double resonance experiments on the proton signals in spectrum ( i ) . The positions of the irradiated protons (*) are in Table XII. Spectra (iv)-(vii) are continued on the following page. - 99 -( i v ) J - - J - ..Oil > l (v) ( v i ) JL_ ( v i i ) JI 6 T" 7 T" 8 JU i 10 T Approximate Predicted x(ppm) i n CgDg Isomer P o s i t i o n R Ratio of R+ Ga-Me pz-Me H 4 Ha Hb He R N-H Me 2 3 trans 9.76s,10.22s 7 .69s,7.99s 4.30s 6.34dd + + 7.12t^ 8.43m^ 10.Old 8.58m,8.93m 1 c i s 9.60s,10.08s 7.77s,7.99s 4.30s 6.74dd + + 7.45t^ ** 10.13d ** Et 3 trans 9 . 74 s , 10. 20s 7 .67s , 8 .00s 4.31s 6 .18dd + + 7.10^ 8.42m 9 . 81t ^ 8.51m , 8.75m ^9.65m 9.58s,10.09s 7.76s,8.00s 4.31s 6.61dd + + 7.29t T ** 9.83t ** 2 ^^9 .65m rCgHg = 2.84 ppm; s = s i n g l e t , d = doublet, t = t r i p l e t , dd = doublet of doublets, m = m u l t i p l e t + trans = p o s i t i o n on opposite side of jrietal as p y r a z o l y l group, c i s = p o s i t i o n on same side of metal as p y r a z o l y l group + + J , = 11.2 Hz, J = 4.0 Hz ab ' ac ^ J b a = 11.2 Hz, J b c = 11.2 Hz ^ J = 4.0 Hz, J . = 11.2 Hz, J „ T T ^4 Hz, J „ = 7.2 Hz ca ' cb ' C - N H 2 c-Me ** not d i s c e r n i b l e - 101 -The r h e n i u m p r o d u c t s c r y s t a l l i z e d as w h i t e n e e d l e s f r o m b e n z e n e . A c r y s t a l s t r u c t u r e a n a l y s i s o f ( t r a n s ) ( + )^ [Me2Ga(pz") ( 2 A 1 B ) ] R e ( C O ) 3 was u n d e r t a k e n t o d e t e r m i n e t h e a b s o l u t e c o n -f i g u r a t i o n o f t h i s s p e c i e s i n t h e s o l i d s t a t e . The c o m p l e t e d s t r u c t u r e i s shown below. F i g u r e 3 7 . M o l e c u l a r s t r u c t u r e o f ( t r a n s ) ( + ) A (R) [ M e 2 G a ( p z " ) ( 2 A 1 B ) ] R e ( C O ) 3 . Due t o s t e r i c f a c t o r s t h e t r a n s i s o m e r i s f a v o u r e d o v e r t h e c i s i s o m e r i n t h e s o l i d s t a t e . However i n t e r -c o n v e r s i o n between t h e t r a n s and c i s d i a s t e r e o m e r s has b een o b s e r v e d t o t a k e p l a c e i n s o l u t i o n . I t has p r e v i o u s l y b e en r e p o r t e d t h a t i n c o m p l e x e s c o n t a i n i n g s i m i l a r u n s y m m e t r i c mono-. f ( l - p y r a z o l y l ) g a l l a t e l i g a n d s , t h e a m i n o n i t r o g e n i s w e a k l y c o o r -d i n a t e d t o t h e t r a n s i t i o n m e t a l c e n t r e . I f t h i s i s a g a i n t h e c a s e i n t h e p r e s e n t . c h i r a l r h e n i u m m o l e c u l e s , t h e f o l l o w i n g - 102 -s t e p s c a n be p o s t u l a t e d t o be t a k i n g p l a c e i n s o l u t i o n . S u ch a mechanism would a c c o u n t f o r t h e d i f f e r e n t r a t i o o f t r a n s t o c i s i s o m e r s o b s e r v e d i n t h e "*"H nmr s p e c t r a r e c o r d e d i n C D b b and ( C D 3 ) 2 C O . i ) b r e a k i n g o f t h e Re-NH 2 bond i i ) r o t a t i o n a b o u t t h e CH 2~C*HR s i n g l e bond i i i ) r e f o r m i n g o f t h e Re-NH 2 bond A "^H nmr s p e c t r u m o b t a i n e d on c r y s t a l s o f ( t r a n s ) (+) . (R) A e [Me 2Ga(pz") (2A1B)]Re ( C O ) 3 a l s o c o n t a i n e d r e s o n a n c e s a t t r i b u t a -b l e t o b o t h t h e c i s and t r a n s i s o m e r s , l e n d i n g s u p p o r t t o t h e p r o p o s e d s o l u t i o n b e h a v i o u r o f t h e s e m o l e c u l e s . 3 . 4 Summary Numerous examples o f f a c i a l l y c o o r d i n a t e d manganese and r h e n i u m t r i c a r b o n y l c o m p l e x e s o f t h e t y p e L M ( C O ) 3 have b e e n p r e p a r e d . The g e n e r a l v e r s t i l i t y and e x c e l l e n t c h e l a t i n g a b i l -i t i e s o f t h e g a l l a t e l i g a n d s have been d e m o n s t r a t e d . The unsym-m e t r i c m o n o ( 1 - p y r a z o l y l ) g a l l a t e t r i d e n t a t e l i g a n d s c a n be e a s i l y m o d i f i e d a t a d o n o r s i t e o t h e r t h a n t h e p y r a z o l y l r i n g n i t r o g e n . The e f f e c t o f t h e s e m o d i f i c a t i o n s on t h e e l e c t r o n d o n a t i n g c a p a b i l i t y o f t h e c h e l a t i n g l i g a n d c a n be m o n i t o r e d by m e a s u r i n g t h e vCO v a l u e s o f t h e t h r e e t e r m i n a l c a r b o n y l g r o u p s bonded t o - 103 -t h e t r a n s i t i o n m e t a l c e n t r e . S e l e c t e d p y r a z o l y l g a l l a t e r h e n i u m t r i c a r b o n y l s p e c i e s have been n i t r o s y l a t e d , t h e e x t r e m e l y a i r s e n s i t i v e L ' R e ( C O ) 2 ( N O ) + c o m p l e x e s f o r m i n g i n low y i e l d s . I n t h e s e n i t r o s y l c a t i o n s t h e t r i d e n t a t e g a l l a t e l i g a n d s were o b s e r v e d t o be s t e r e o c h e m i c a l l y n o n r i g i d i n s o l u t i o n . D i f f e r e n t f l u x i o n a l mechanisms a r e p r o -p o s e d f o r t h e c o m p l e x e s where i ) L 1 = [ M e G a ( p z ) 3 _ o r , i i ) L' = [ M e 2 G a ( C 3 H N 2 R 2 ) ( O C H 2 C H 2 N M e 2 ) ] ~ (R=H o r Me). No p y r a z o l y l g a l l a t e r h e n i u m c o m p l e x e s c o n t a i n i n g h y d r i d e r e d u c e d c o o r d i n a t e d c a r b o n y l m o i e t i e s were o b s e r v e d when t h e L ' R e ( C O ) 2 ( N O ) + c a t i o n s were e x p o s e d t o H . I n s t e a d e x t e n s i v e d e c o m p o s i t i o n o f t h e p y r a z o l y l g a l l a t e n i t r o s y l c a t i o n s o c c u r r e d . The a t t e m p t e d r e d u c t i o n s / e m p h a s i z e d an i m p o r t a n t d i f f e r e n c e between t h e t r i d e n t a t e p y r a z o l y l g a l l a t e l i g a n d s and t h e r e l a t e d c y c l o p e n t a d i e n y l g r o u p . The g a l l a t e l i g a n d s t h e m s e l v e s may be s u s c e p t i b l e t o a t t a c k by r e a c t a n t s w h i c h do n o t e f f e c t t h e c y c l o p e n t a d i e n y l g r o u p u n d e r i d e n t i c a l r e a c t i o n c o n d i t i o n s . S e l e c t e d LRe (CO) 3 c o m p l e x e s and [Me 2Ga ( C 3 H N 2 R 2 ) (OCf_ 2CH 2NMe 2) ] R e ( C O ) 2 ( N O ) + were f o u n d t o be i n e r t w i t h r e g a r d s t o CO m e t a t h e s i s r e a c t i o n s . The n o n l a b i l e c a r b o n y l l i g a n d s a r e p r o p o s e d t o r e -s u l t f r o m t h e good e l e c t r o n d o n a t i n g s t r e n g t h o f t h e p y r a z o l y l -g a l l a t e t r i d e n t a t e l i g a n d s . 104 -CHAPTER IV RHODIUM DERIVATIVES OF BIDENTATE BISPYRAZOLYLGALLATE LIGANDS 4 .1 I n t r o d u c t i o n The s y n t h e s e s o f t h e b i d e n t a t e c h e l a t i n g l i g a n d s , [Me 2Ga (C-jH^R.-.) 2 ] (R=H o r Me), and t h e i r r e a c t i o n s w i t h [ R e ( C O ) ^ C l ] 2 have been d e s c r i b e d i n C h a p t e r I I . I n t h e p r e s e n t c h a p t e r t h e b e h a v i o u r o f t h e s e b i s ( 1 - p y r a z o l y l ) g a l l a t e l i g a n d s t o w a r d s s e l e c t e d R h ( I ) c o m p l e x e s w i l l be d i s c u s s e d . When R=H s q u a r e p l a n a r r h o d i u m compounds o f t h e t y p e [ M e 2 G a ( p z ) 2 ] R h ( X ) ( Y ) [(X) = CO o r P P h 3 , (Y) = CO o r P P h 3 ; (X) ( Y ) = 1 , 5 - c y c l o o c t a -d i e n e , COD] have been p r e p a r e d . A l l f o u r o f t h e s e c o m p l e x e s were shown t o be n o n r i g i d i n s o l u t i o n by v a r i a b l e t e m p e r a t u r e "^H nmr e x p e r i m e n t s . An X - r a y s t r u c t u r e d e t e r m i n a t i o n o f [ M e 2 G a ( p z ) 2 ] R h ( C O D ) c o n f i r m e d t h e b o a t c o n f o r m a t i o n f o r t h e f G a - ( N - N ) 2 - R h i s i x membered r i n g i n t h i s c o m p l e x i n t h e s o l i d s t a t e . A t t e m p t s t o p r e p a r e t h e a n a l o g o u s d i c a r b o n y l and COD com-p l e x e s c o n t a i n i n g t h e b i d e n t a t e l i g a n d where R=Me r e s u l t e d i n t h e f a c i l e f o r m a t i o n o f t h e 3,5 d i m e t h y l p y r a z o l y l b r i d g e d r h o d i u m d i m e r s [ ( y - p z " ) R h ( C O ) 2 ] 2 a n d [ ( y - p z " ) R h ( C O D ) ] ^ / t o g e t h e r w i t h [ M e 2 G a ( y - p z " ) ] 2 • However one s t a b l e complex i n c o r p o r a t i n g t h i s s t e r i c a l l y more demanding l i g a n d c o u l d be c r y s t a l l i z e d i n low y i e l d , namely [Me„Ga (p z " ) „ ] Rh (CO) (PPh-.) . T h i s m o l e c u l e d i d n o t - 105 -e x h i b i t f l u x i o n a l b e h a v i o u r i n s o l u t i o n a t room, t e m p e r a t u r e . The s o l i d s t a t e s t r u c t u r e o f [ M e 2 G a ( p z " ) 2 ] R h ( C O ) ( P P h 3 ) has b een d e t e r m i n e d by X - r a y d i f f r a c t i o n . The b i s p y r a z o l y l g a l l a t e r h o d i u m c o m p l e x e s were f o u n d t o be i n e f f e c t i v e as 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 1-hexene o r c y c l o h e x e n e . C r y s t a l s t r u c t u r e s o f two d i m e r i c s p e c i e s a r e i n c l u d e d , [ (yr?pz") Rh (CO) 2 ] 2 and [ ( y - p z " ) R h ( C O D ) ] 2 • T h e s e s t r u c t u r e s have b e e n compared t o r e l a t e d s t r u c t u r e s r e p o r t e d i n t h e l i t e r a t u r e . P a r t s o f t h i s c h a p t e r have been s u b m i t t e d f o r f u t u r e p u b l i c a t i o n ( 8 3 ) . 4 . 2 E x p e r i m e n t a l 4.2.1 S t a r t i n g M a t e r i a l s [ R h ( C O ) 2 C l ] 2 (Strem) was s u b l i m e d in vacuo b e f o r e u s e . [ R h ( C O D ) C l ] 2 and R h ( P P h 3 ) 3 C l (Strem) were u s e d as s u p p l i e d . I o d i n e ( A l d r i c h ) was r e s u b l i m e d b e f o r e u s e . 4.2.2 P r e p a r a t i o n o f [ M e 2 G a ( p z ) ] R h ( C O ) 2 _ 2 N a + [ M e 2 G a ( p z ) 2 ] " + [ R h ( C O ) 2 C l ] 2 —™L>. 2 [ M e 2 G a ( p z ) 2 ] R h ( C O ) 2 + 2NaCl Two m o l a r e q u i v a l e n t s o f N a + [ M e 2 G a ( p z ) 2 ] ~ i n THF were added d r o p w i s e t o a s t i r r e d s o l u t i o n o f [Rh(CO). 2Cl] 2 (.330 g, .849 mmol) d i s s o l v e d i n THF a t 0° C. T o t a l volume -75 m l . The s o l u t i o n was g r a d u a l l y warmed t o room t e m p e r a t u r e and s t i r r e d - 106 -o v e r n i g h t . The r e a c t i o n m i x t u r e was t h e n f i l t e r e d and t h e s o l -v e n t removed in vacuo l e a v i n g an o r a n g e o i l . A t t e m p t e d c r y -s t a l l i z a t i o n o f t h e p r o d u c t f r o m m e t h y l e n e c h l o r i d e o r / a n d b e n z e n e , r e s u l t e d i n an o r a n g e o i l o n l y w h i c h d a r k e n e d i n c o l o u r upon e x p o s u r e t o a i r . S e l e c t e d p h y s i c a l d a t a a r e summarized i n T a b l e X I I I . 4.2.3 P r e p a r a t i o n o f [Me 2 Ga (pz) 2 ]Rh,(CO) (PPhp1 [ M e 2 G a ( p z ) 2 ] R h ( C 0 ) 2 + P P h 3 — ° 6 H 6 > [ M e 2 G a ( p z ) 2 ] R h ( C O ) ( P P h 3 ) + CO T r i p h e n y l p h o s p h i n e (.175 g, .668 mmol) d i s s o l v e d i n 25 ml b e n z e n e was added t o an o r a n g e - b r o w n s o l u t i o n o f [ M e 2 G a ( p z ) 2 ] R h ( C O ) 2 ( .25 g> .636 mmol) i n 25 ml o f t h e same s o l v e n t . The r e a c t i o n s o l u t i o n began b u b b l i n g i m m e d i a t e l y and l i g h t e n e d c o n -s i d e r a b l y i n c o l o u r . A f t e r s t i r r i n g f o r 5 m i n t h e s o l v e n t was removed in vacuo . The r e m a i n i n g o r a n g e - y e l l o w r e s i d u e was r e c r y s t a l l i z e d f r o m m e t h y l e n e c h l o r i d e / b e n z e n e . Y i e l d >90%. S e l e c t e d p h y s i c a l d a t a a r e summarized i n T a b l e X I I I . 4.2.4 P r e p a r a t i o n o f [Me 2Ga (pz) 2 ] Rh ( P P h 3 )_2_ N a + [ M e 2 G a ( p z ) 2 ] " + R h ( P P h 3 ) 3 C l — ™ F > 6 6 [ M e 2 G a ( p z ) 2 ] R h ( P P h 3 ) 2 + N a C l + P P h 3 R h ( P P h 3 ) 3C1 (.379 g, .410 mmol) was s t i r r e d i n -75 ml ben-zene f o r 1 h. An e q u i m o l a r amount o f l i g a n d d i s s o l v e d i n 10 ml THF was t h e n added and t h e r e s u l t a n t s o l u t i o n s t i r r e d f o r t h r e e d a y s . E v a p o r a t i o n o f t h e s o l v e n t s f r o m t h e f i l t e r e d r e a c -- 107 -t i o n m i x t u r e l e f t a y e l l o w powder f r o m w h i c h f r e e PPh-j was removed-by s u b l i m a t i o n in vacuo. Y i e l d 93%. S e l e c t e d p h y s i c a l d a t a a r e i n c l u d e d i n T a b l e X I I I . 4.2.5 P r e p a r a t i o n o f [ M e ^ G a ( p z ) 2 ] R h ( C O D ) 2Na +[Me^Ga (pz) ] ~ + [ R h ( C O D ) C l ] 2 — — „ 2 [ M e 2 G a ( p z ) 2 ] R h ( C O D ) + 2NaCl Two m o l a r e q u i v a l e n t s o f N a + [ M e 2 G a ( p z ) 2 ] were added t o [ R h ( C O D ) C l ] 2 (.314 g, .637 mmol) d i s s o l v e d i n 75 ml THF. Upon a d d i t i o n o f t h e l i g a n d t h e i n i t i a l l y o r a n g e s o l u t i o n i m m e d i a t e l y t u r n e d lemon y e l l o w i n c o l o u r . The r e a c t i o n s o l u t i o n was s t i r r e d a t room t e m p e r a t u r e f o r 6 h and t h e s o l v e n t removed in vacuo. The r e m a i n i n g y e l l o w - o r a n g e r e s i d u e was d i s s o l v e d i n a minimum amount o f b e n z e n e and f i l t e r e d . Slow e v a p o r a t i o n o f t h e b e n z e n e gave t h e i n i t i a l f o r m a t i o n o f o r a n g e c r y s t a l s o f [ ( y - p z ) R h ( C O D ) ] 2 . Removal o f t h e s e c r y s t a l s l e f t -10 ml o f y e l l o w b e n z e n e f i l t r a t e f r o m w h i c h lemon y e l l o w c r y s t a l s o f t h e d e s i r e d p r o d u c t s l o w l y f o r m e d . T h e s e c r y s t a l s were p i c k e d o u t o f s o l u t i o n as t h e y f o r m e d and washed s p a r i n g l y w i t h n-hexane. Y i e l d ~40%. S e l e c t e d p h y s i c a l d a t a a r e g i v e n i n T a b l e X I I I . The r e s i d u e r e m a i n i n g i n t h e r e a c t i o n b e a k e r a f t e r t h e d e s i r e d p r o d u c t had b e en s e p a r a t e d was i d e n t i f i e d t o c o n t a i n p r i m a r i l y [ M e 2 G a ( y - p z ) ] 2 . 4.2.6 R e a c t i o n s o f [ M e 2 G a ( p z ) 2 ] R h ( C O ) 2 _ (a) A t t e m p t e d S u b s t i t u t i o n of. GO. .withsrpzH o r Et-^N C a r b o n y l " s u b s t i t u t i o n w i t h p y r a z o l e o r t r ' l e t h y l a m i n e was T a b l e X I I I . P h y s i c a l D a t a f o r A n a l y s i s F o u n d ( % ) / C a l ' d ( % ) H nmr i n CgDg, x(ppm) Ga-Me H 3 H 4 IR(cm x) "CO Comments CO CO 9.73s 2.68d 4.01t 2.71d 2088,2020 c orange l i q u i d 2085,2018 b a i r s e n s i t i v e CO PPh-, 51.27 4 .34 9. 10 51.72 4.31 8.94 9.53s 2.16d 3.88t c 1995 c 4.32t 1993 1 y e l l o w orange s o l i d a i r s t a b l e PPh 3 PPh 3 61.35 4.91 6.50 61.00 4.93 6.28 8,75s,br 2 5 6 d 9.73s,br 4.40t 2.95d y e l l o w s o l i d a i r s t a b l e 43.11 5.39 12.51 COD 43.18 5.40 12.59 9.50s 2.56d 9.72s 2.33d 9.46br,s 2.16d 10.03br,s 3 .96t 3.73t 3.69t 2 .72d 2.38d 2 .29d ++ y e l l o w c r y s t a l s a i r s t a b l e measured as CgH^ 2 s o l u t i o n s k measured as N u j o l mulls obscured by PPh-. resonances a t 2.51m, 2.99m TCgHg = 2.84 ppm; s = s i n g l e t , d = doublet (J 2Hz) , t = t r i p l e t (J ^  2Hz) , br = broad measured i n dg-acetone s o l u t i o n a t room tem-p e r a t u r e , T ( C H 3 ) 2 C O =7.89 ppm measured i n dg-acetone s o l u t i o n at --80°C - 109 -a t t e m p t e d u s i n g a s i m i l a r p r o c e d u r e t o t h a t , d e s c r i b e d i n s e c t i o n 4.2.3. E v e n w i t h p r o l o n g e d r e a c t i o n t i m e s and e l e v a t e d r e a c t i o n t e m p e r a t u r e s , none o f t h e d e s i r e d p r o d u c t s c o u l d be d e t e c t e d . S l i g h t d i s p r o p o r t i o n a t i o n o f t h e s t a r t i n g r h o d i u m d i c a r b o n y l was o b s e r v e d , r e s u l t i n g i n t h e i s o l a t i o n o f s m a l l amounts o f t h e known p y r a z o l y l b r i d g e d d i m e r s , [ ( y - p z ) R h ( C O ) 2 ] 2 , and [ M e 2 G a ( y - p z ) ] . (b) A t t e m p t e d o x i d a t i o n w i t h I 2 D r o p w i s e a d d i t i o n o f i o d i n e (.200 g, .788 mmol) d i s s o l v e d i n 25 ml E t 2 0 t o [ M e 2 G a ( p z ) 2 ] R h ( C O ) 2 ( .30 g, .76 mmol), . d i s s o l v e d i n b e n z e n e , r e s u l t e d i n a d a r k r e d s o l u t i o n . A f t e r s t i r r i n g o v e r n i g h t t h i s r e a c t i o n m i x t u r e had l i g h t e n e d i n c o l o u r . However r e m o v a l o f t h e s o l v e n t s in vacuo l e f t u n r e a c t e d s t a r t i n g m a t e r i a l s and t r a c e s o f t h e d i m e r s [ ( y - p z ) R h ( C O ) 2 ] 2 and [ M e 2 G a ( y - p z ) ] 2 > R e f l u x i n g t h e above r e a c t a n t s f o r 24 h p r e c i p i t a t e d a d a r k r e d - b r o w n s o l i d . T h e r e were no p r o t o n r e s o n a n c e s v i s i b l e i n t h e nmr s p e c t r u m o f t h i s c o m p l e x . T h i s s o l i d p o s s e s s e d no c a r -b o n y l s t r e t c h e s i n t h e a p p r o p r i a t e IR r e g i o n and was i n s o l u b l e i n o r g a n i c s o l i d s . 4.2.7 R e a c t i o n o f N a + [ M e 2 G a ( p z " ) 2 ] ~ w i t h [ R h ( C O ) 2 C l ] 2 o r [ R h ( C O D ) C l ] 2 A d d i t i o n o f t h e b i d e n t a t e l i g a n d [ M e 2 G a ( p z " ) 2 ] t o e i t h e r [ R h ( C O ) 2 C l ] 2 o r [ R h ( C O D ) C l ] 2 r e s u l t e d i n t h e i s o l a t i o n o f t h e two known 3,5 d i m e t h y l p y r a z o l y l b r i d g e d d i m e r s [ (y-p.z") Rh (CO) 2 ] 2 and [ ( y - p z " ) R h ( C O D ) ] „ r e s p e c t i v e l y . I n b o t h c a s e s t h e s e d i m e r s - 110 -formed r e a d i l y w h e t h e r t h e l i g a n d a d d i t i o n was c a r r i e d o u t a t 0° o r r e f l u x t e m p e r a t u r e s . S e l e c t e d p h y s i c a l d a t a f o r t h e r h o d i u m d i m e r s a r e summarized i n T a b l e XIV. 4.2.8 P r e p a r a t i o n o f [Me 2 Ga (pz") 2 ]Rh(CO) (PPh.,)_ [ R h ( C O ) 2 C l ] 2 + 2 P P h 3 T H F > "[Rh(CO) ( P P h 3 ) C l ] 2 " + 2CO " [Rh(CO) ( P P h 3 ) C l ] 2 " + 2 N a + [ M e 2 G a ( p z " ) 2 ] " T H F >• 2 [ M e 2 G a ( p z " ) 2 ] R h ( C O ) (PPh 3)|] + 2NaCl [ R h ( C O ) 2 C l ] 2 (.183 g , .471 mmol) and P P h 3 (.247 g, .943 mmol) were d i s s o l v e d t o g e t h e r i n -100 ml THF and N a + [ M e 2 G a ( p z " ) 2 ] (.941 mmol i n 50 ml THF) was added d r o p w i s e a t - 7 8 ° . A f t e r c o m p l e t e a d d i t i o n o f t h e l i g a n d , t h e r e a c t i o n s o l u t i o n was a l l o w e d t o warm s l o w l y t o room t e m p e r a t u r e . -100 ml o f n-hexane was added t o t h e m i x t u r e and t h e lemon y e l l o w s o l u t i o n s u b s e q u e n t l y f i l t e r e d . E v a p o r a t i o n o f t h e s o l v e n t s l e f t a y e l l o w - o r a n g e r e s i d u e . A "'"H nmr s p e c t r u m o f t h i s r e s i d u e i n d i c a t e d -75% o f t h e d e s i r e d p r o d u c t t o g e t h e r w i t h a b o u t -25% o f t h e r h o d i u m d i m e r , [ ( p - p z " ) R h ( C O ) ( P P h 3 ) ] 2 • C r y s t a l l i z a t i o n o f t h e d e s i r e d p r o d u c t was a t t e m p t e d u s i n g C H 2 C l 2 / n - h e x a n e . However i n c o n c e n t r a t e d s o l u t i o n s , n e e d l e s o f t h e r h o d i u m d i m e r formed p r e f e r e n t i a l l y . After." ~. 14 g o f t h i s d i -mer was r e m o v e d " f r o m t h e c o n c e n t r a t e d r e a c t i o n s o l u t i o n , lemon y e l l o w p r i s m s o f [ M e 2 G a ( p z " ) 2 ] R h ( C O ) ( P P h 3 ) (.103 g, 32% y i e l d ) . f o r m e d . P h y s i c a l d a t a f o r t h i s p y r a z o l y l g a l l a t e t h o d i u m complex a r e g i v e n i n T a b l e XV. T a b l e XIV. y-3,5 d i m e t h y l p y r a z o l y l Rhodium D i m e r s X IR •H nmr ( T r C , D r ) ^ 6 t> v c o ( c m 1 , C 6 H 1 2 ) pz-Me H O t h e r Comments CO CO 2088s,2072s,2020vs 7 .80s 4 .33s a i r s t a b l e y e l l o w n e e d l e s CO PPh, 1980 v s 7.40s 8.16s 4,45s i , 2 . 31m ^ 2 .96m a i r s t a b l e y e l l o w powder COD 7,53s 4.42s ^ 5 .46m ^ 7.19m ^ 8.08m a i r s t a b l e o r a n g e n e e d l e s xCgHg = 2.84 ppm; s = s i n g l e t , m = m u l t i p l e t s = s t r o n g , v s = v e r y - s t r o n g T a b l e XV. P h y s i c a l D a t a f o r A n a l y s i s F o u n d ( % ) / C a l ' d ( % ) H N IR(cm ) C 6 H 1 2 vCO 1 * H nmr i n C r D r , T(ppm) b b Ga-Me pz-Me H PPh, 54.43 54.50 5.10 5.16 8.19 8 . 20 1985s 9.28s 9.73s 7.35s 7.85s 7 .86s 8.14s 4 .24s 4.71s 2 .42m 3.01m * T C , H , = 2.84 ppm; s = s i n g l e t , m = m u l t i p l e t - 113 -4 . 3 R e s u l t s and D i s c u s s i o n 4.3.1 [ M e 2 G a ( p z ) 2 ] R h ( X ) ( Y ) [(X) = CO o r P P h 3 , (Y) = CO o r P P h 3 ; (X)(Y) = COD] When [ R h ( C O ) 2 C l ] 2 was s t i r r e d w i t h [ M e 2 G a ( p z ) 2 ] ~ a t room t e m p e r a t u r e , c r y s t a l s o f t h e known r h o d i u m d i m e r s [ ( y - p z ) R h ( C O ) 2 ] 2 (9) and [ M e 2 G a ( y - p z ) ] 2 (84) were t h e o n l y i d e n t i f i a b l e p r o d u c t s f o r m e d . The d e s i r e d c o m p l ex, [ M e 2 G a ( p z ) 2 ] R h ( C O ) 2 , c o u l d be o b t a i n e d i f t h e r e a c t i o n was c a r r i e d o u t a t low t e m p e r a t u r e s . T h i s monomeric d i c a r b o n y l s p e c i e s was i s o l a t e d as an o r a n g e l i -q u i d w h i c h d a r k e n e d i n c o l o u r upon e x p o s u r e t o a i r . The IR s p e c t r u m o f t h i s l i q u i d c o n t a i n e d two s t r o n g vCO bands i n t h e t e r m i n a l CO r e g i o n a t wavenumbers s i m i l a r t o t h o s e r e p o r t e d f o r r e l a t e d b o r o n compounds. T a b l e X V I . C o m p a r i s o n o f vCO v a l u e s i n L R h ( C O ) 2 c o m p l e x e s . L vCO i n N u j o l ( c m - 1 ) R e f . E t 2 B ( p z ) 2 2080, 2020 (85) H 2 B ( p z ) 2 2083, 2020 (86) M e 2 G a ( p z ) 2 2085, 2018 ( t h i s work) Mass s p e c t r a l d a t a f o r [ M e 2 G a ( p z ) 2 ] R h ( C O ) 2 , and r e l a t e d p y r a z o l y l g a l l a t e r h o d i u m compounds t o be d i s c u s s e d i n t h i s s e c -t i o n , a r e t a b u l a t e d i n T a b l e X V I I . I n e a c h o f t h e s e s p e c t r a t h e p a r e n t i o n was t h e h i g h e s t m o l e c u l a r i o n s i g n a l o b s e r v e d , c o n f i r m i n g t h e monomeric n a t u r e o f t h e p r o d u c t s . - 114 -R e l a t i v e I n t e n s i t i e s \ (X) \ ( Y ) (CO) (CO) (CO) (PPh 3) (PPh 3) (PPh 3) (COD) A s s i g n m e n t \ P + 1.0 .7 4.0 10.7 P-Me + 100.0 22.4 1.0 100.0 P - M e - ( X ) + 49.5 17 .5 17 .0 P - M e - ( X ) - ( Y ) + 53 .1 4.6 P - M e - p z - ( X ) - H + 22.3 9.7 P P h 3 + 100.0 100.0 M e G a ( p z ) R h + 15.3 8.2 G a ( p z ) R h + 18 .9 9.7 MeGa (pz) + 15.4 M e 2 G a + 16.7 6.5 G a + 13.6 p z H + 13 .7 13 .7 14 .8 4.8 - 115 -B o t h [ M e 2 G a ( p z ) 2 ] R h ( C O ) 2 and t h e v a l e n c e i s o e l e c t r o n i c b o r o n complex, [ E t 2 B ( p z ) 2 ] R h ( C O ) 2 , a r e a i r s e n s i t i v e l i q u i d s a t room t e m p e r a t u r e . [ E t 2 B ( p z ) 2 ] R h ( C O ) 2 r e p o r t e d l y d o e s n o t r e a c t w i t h a v a r i e t y o f p o t e n t i a l d o n o r l i g a n d s , i n c l u d i n g P P h 3 ( 8 5 ) . The r e a c t i v i t y o f [ M e 2 G a ( p z ) 2 ] R h ( C O ) 2 t o w a r d s PPh^ more resem-b l e d t h a t o f [ H 2 B ( p z ) 2 ] R h ( C O ) 2 (8 6) and c o r r e s p o n d i n g c o m p l e x e s c o n t a i n i n g t h e B - d i k e t o n a t e l i g a n d (87, 8 8 ) . I n e a c h o f t h e s e l a t t e r d i c a r b o n y l s p e c i e s f a c i l e d i s p l a c e m e n t o f one CO o c c u r s w i t h P P h 3 , y i e l d i n g an a i r s t a b l e p r o d u c t . [ M e 2 G a ( p z ) 2 ] R h ( C O ) 2 a l s o r e a c t e d r e a d i l y w i t h PPh^, t h e r e s u l t i n g p r o d u c t [ M e 2 G a ( p z ) 2 ] R h ( C O ) ( P P h 3 ) f o r m i n g i n h i g h y i e l d . T h i s p h o s p h i n e complex was f u l l y c h a r a c t e r i z a b l e by t h e c o n v e n t i o n a l methods a l r e a d y d e s c r i b e d i n e a r l i e r c h a p t e r s . Rhodium p y r a z o l y l b o r a t e s o f t h e t y p e [ E t 2 B ( p z ) 2 ] R h ( C N R ) 2 ( w h e r e R = p - C H 3 C g H 4 , t - C 4 H g o r p - C H 3 C 6 H 4 S 0 2 C H 2 ) u n d e r g o 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 w i t h i o d i n e , y i e l d i n g r h o d i u m ( I I I ) c o m p l e x e s ( 8 5 ) . I n c o n t r a s t t o t h i s b e h a v i o u r , no i d e n t i f i a b l e p r o d u c t s w o u l d be i s o l a t e d f r o m t h e r e a c t i o n o f [ M e 2 G a ( p z ) 2 ] R h ( C O ) 2 and 1^. A t r e f l u x t e m p e r a t u r e s c o m p l e t e d e c o m p o s i t i o n o f t h e s t a r t i n g p y r a z o l y l g a l l a t e r h o d i u m d i c a r b o n y l o c c u r r e d . [ M e 2 G a ( p z ) 2 ] R h ( C O D ) was p r e p a r e d f r o m t h e r e a c t i o n o f [ M e 2 G a ( p z ) 2 ] ~ w i t h [ R h ( C O D ) C l ] 2 • T h i s compound f o r m e d i n low y i e l d , p r e s u m a b l y h i n d e r e d by t h e f o r m a t i o n o f t h e s t a b l e p y r a z o l y l b r i d g e d d i m e r [ ( y - p z ) R h ( C O D ) ] 2 • T h i s c o m p e t i n g s i d e r e a c t i o n w i l l be d i s c u s s e d f u r t h e r I n t h e f o l l o w i n g s e c t i o n . - 1 1 6 -[ M e 2 G a ( p z ) 2 1 R h ( C O D ) was c h a r a c t e r i z e d by e l e m e n t a l a n a l y s i s , "^H nmr and mass s p e c t r o m e t r y . I n t e r e s t i n g l y t h e 'Me 2Ga' m o i e t y i n t h e t h r e e c o m p l e x e s [ M e 2 G a ( p z ) 2 ] R h ( X ) (Y) [ (X) (Y) = (CO) 2 , (CO) ( P P h 3 ) o r (COD)] c o n t r i b u t e o n l y one s h a r p s i n g l e t ( i n t e g r a t i o n s i x p r o t o n s ) t o t h e i r "^H nmr s p e c t r a a t room t e m p e r a t u r e ( T a b l e X I I I ) . T h i s w o u l d s u g g e s t e i t h e r a p l a n a r g e o m e t r y f o r t h e f G a - (N-N) 2 - Rh'-" s i x membered r i n g i n e a c h o f t h e s e compounds, o r a r a p i d l y i n v e r t i n g b o a t c o n f o r m a t i o n as i l l u s t r a t e d b e l o w : F i g u r e 38. P r o p o s e d d y n amic s o l u t i o n b e h a v i o u r o f t h e [ M e 2 G a ( p z ) 2 ] R h ( X ) ( Y ) c o m p l e x e s . P r e v i o u s d i s c u s s i o n on t h e c o o r d i n a t i o n g e o m e t r y o f [ M e 2 G a ( p z ) 2 ] ~ i n C h a p t e r I I s u g g e s t e d t h a t c o m p l e x e s i n c o r p o r a t -i n g t h i s and s i m i l a r p y r a z o l y l l i g a n d s p r e f e r t o a d o p t a p u c k e r e d b o a t c o n f o r m a t i o n o v e r a p l a n a r a r r a n g e m e n t due t o a c o m b i n a t i o n o f s t e r i c and e l e c t r o n i c , f a c t o r s . To f u r t h e r p r o b e - 117 -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 p r e s e n t r h o d i u m c o m p l e x e s , low t e m p e r a t u r e "^ H nmr s t u d i e s were c o n d u c t e d on [ M e 2 G a ( p z ) 2 ] R h (CO) (PPh 3) and [Me 2Ga (pz) 2 ] R h (COD) i n ( C D ^ C O . The 'GaMe 2' s i n g l e t o b s e r v e d a t room t e m p e r a t u r e f o r b o t h o f t h e s e compounds c o l l a p s e d as t h e t e m p e r a t u r e was l o w e r e d , e v e n t u a l l y r e a p p e a r i n g as two s i n g l e t s . T h i s c hange was accom-p a n i e d b y . a n e x p e c t e d s h i f t i n t h e r e s o n a n c e s a t t r i b u t a b l e t o t h e p y r a z o l y l p r o t o n s . B o t h o f t h e s e f e a t u r e s a r e c l e a r l y v i s -i b l e i n t h e v a r i a b l e t e m p e r a t u r e ^H nmr s p e c t r a o f [ M e 2 G a ( p z ) 2 ] R h ( C O ) ( P P h 3 ) , shown i n F i g u r e 39. I n a d d i t i o n , t h e low temp-e r a t u r e s p e c t r a o f t h e COD complex ( F i g . 40) d i s p l a y a s p l i t -t i n g o f t h e s i g n a l s due t o t h e p r o t o n s on t h e COD l i g a n d . T h i s i s p a r t i c u l a r l y n o t i c e a b l e f o r t h e o l e f i n i c p r o t o n s c l o s e s t t o t h e r h o d i u m atom a t ~5.8T. The low t e m p e r a t u r e "^ H nmr s p e c t r a a r e c o n s i s t e n t w i t h t h e dynamic s o l u t i o n b e h a v i o u r i l l u s t r a t e d i n F i g u r e 38. Thus a t room t e m p e r a t u r e i n v e r s i o n o f t h e p y r a z o l y l b o a t i s f a s t enough t o a l l o w t h e m o l e c u l e s t o a p p e a r t o p o s s e s s p l a n a r f G a - ( N - N ) 2 ~ R h } i n t e r n a l s i x membered r i n g s on an nmr t i m e s c a l e . L o w e r i n g t h e t e m p e r a t u r e s l o w s down t h e f l u x i o n a l p r o c e s s s u f f i c i e n t l y so t h a t t h e l i m i t i n g e x p e c t e d s p e c t r a o f t h e b o a t c o n f o r m a t i o n c a n be r e c o r d e d . T h e s e "^ H nmr s t u d i e s c a n be compared t o nmr e x p e r i m e n t s c o n -d u c t e d on r e l a t e d p y r a z o l y l b o r a t e c o m p l e x e s . The ''"H nmr s p e c t r u m o f [ E t 2 B ( p z ) 2 ] R h ( C O ) 2 a l s o c o n t a i n s o n l y one s e t o f ' E t 2 B ' r e s o n a n c e s a t room t e m p e r a t u r e . However l o w e r i n g t h e t e m p e r a -t u r e t o -90° d i d n o t r e s u l t i n any n o t i c e a b l e - b r o a d e n i n g o r - 118 -M e 2 G a ( p z ) 2 ] R h ( c o ) ( p P h 3 ) 2 3 4 5 6 7 8 9 10 T F i g u r e 39. V a r i a b l e t e m p e r a t u r e 100 MHz "^H nmr s p e c t r a f o r [ M e 2 G a ( p z ) 2 ] R h ( C 0 ) ( P P h 3 ) i n ( C D 3 ) 2 C O . - 119 -M e 2 G a ( p z ) 2 Rh (cOD - 120 -s p l i t t i n g o f t h i s s i n g l e s e t o f r e s o n a n c e s a t t r i b u t e d t o e q u i v a l e n t e t h y l s u b s t i t u e n t s . , (85) . [H 2B (pz) 2 ]Rh (CO) 2 was n o t s u b j e c t e d t o v a r i a b l e ''"H nmr t r e a t m e n t , due t o t h e i n a b i l i t y t o d e t e c t t h e 'H 2B' s i g n a l s a t room t e m p e r a t u r e ( 8 6 ) . Of i n t e r e s t i s t h e r e c e n t l y r e p o r t e d c o m p l e x [ B ( p z ) 4 ] R h ( C O D ) (76, 7 7 ) . A t room t e m p e r a t u r e t h e nmr s p e c t r u m o f t h i s m o l e c u l e c o n t a i n e d o n l y one s e t o f p y r a z o l y l r e s o n a n c e s , i n d i c a t i n g f o u r e q u i v a -l e n t p y r a z o l y l g r o u p s i n s o l u t i o n . On l o w e r i n g t h e t e m p e r a t u r e two s e t s o f p y r a z o l y l r e s o n a n c e s a p p e a r e d i n t h e nmr s p e c -trum, b u t i n a r a t i o o f 3:1. F u r t h e r m o r e a c r y s t a l s t r u c t u r e o f t h i s t e t r a ( 1 - p y r a z o l y l ) b o r a t e complex showed a s q u a r e p l a n a r Rh(I) c e n t r e w i t h two p y r a z o l y l g r o u p s b r i d g i n g t h e b o r o n and r h o d i u m atoms and two p y r a z o l y l r i n g s o c c u p y i n g t h e r e m a i n i n g t e t r a h e d r a l s i t e s a r o u n d t h e b o r o n . From t h e s e o b s e r v a t i o n s a mechanism was s u b s e q u e n t l y p r o p o s e d whereby a l l f o u r p y r a z o l y l g r o u p s i n t e r c h a n g e v i a a p e n t a c o o r d i n a t e t r i s ( 1 - p y r a z o l y l ) b o r a t e i n t e r m e d i a t e a t room t e m p e r a t u r e i n s o l u t i o n . S uch a dynamic p r o c e s s as t h i s i s n o t f e a s i b l e i n t h e p r e s e n t p y r a z o l y l g a l l a t e c o m p l e x e s as t h e a l k y l g r o u p s on t h e g a l l i u m atom c o n t a i n no p o t e n t i a l d o n o r s i t e s f o r f u r t h e r c o o r d i n a t i o n t o t h e r h o d i u m . The p u c k e r e d n a t u r e o f t h e p y r a z o l y l g a l l a t e r h o d i u m m o l e -c u l e s has b een d e m o n s t r a t e d by 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 o f t h e c o m p l e x [ M e 2 G a ( p z ) 2 ] R h ( C O D ) ( F i g . 4 1 ) . From measured bond a n g l e s and bond d i s t a n c e s ( A p p e n d i x I I ) i t c a n be a s c e r -t a i n e d t h a t t h e r h o d i u m atom l i e s i n a s l i g h t l y d i s t o r t e d s q u a r e p l a n a r e n v i r o n m e n t and t h e p y r a z o l y l r i n g s a r e b o t h p l a n a r w i t h i n - 121 -F i g u r e 41. M o l e c u l a r s t r u c t u r e o f [ M e 2 G a ( p z ) 2 ] R h ( C O D ) . e x p e r i m e n t a l e r r o r . The m o l e c u l e p o s s e s s e s e x a c t C ( m i r r o r ) s symmetry and f o l d i n g o f t h e c e n t r a l f G a - ( N - N ) 2 ~ R h t r i n g a p p e a r s t o r e s u l t p r i m a r i l y f r o m s t e r i c i n t e r a c t i o n between t h e p y r a z o l y l and COD m o i e t i e s . The d e g r e e o f f o l d i n g i s g r e a t e r t h a n t h a t o b s e r v e d i n t h e r e l a t e d compounds, [ B ( p z ) 4 ] R h ( C O D ) and [ B ( p z ) 4 ] R h ( N B D ) (NBD = n o r b o r n a d i e n e ) (76) i n w h i c h r i n g f o l d i n g i n h i n d e r e d by s t e r i c i n t e r a c t i o n o f t h e c o o r d i n a t e d d i o l e f i n w i t h t h e t e r m i n a l pseudo a x i a l p y r a z o l y l g r o u p on t h e b o r o n atom. [ M e 2 G a ( p z ) 2 ] R h ( P P h ^ ) 2 was p r e p a r e d by t h e r e a c t i o n o f t h e [ M e 2 G a ( p z ) 2 ] ~ l i g a n d w i t h W i l k i n s o n ' s c a t a l y s t , R h ( P P h 3 ) 3 C l . The room t e m p e r a t u r e "^H nmr s p e c t r u m o f t h i s c omplex, i n e i t h e r CgDg o r ( C D 3 ) 2 C O , c o n t a i n e d two b r o a d s i g n a l s i n t h e 'Me-^Ga' r e g i o n . Thus t h e f l u x i o n a l p r o c e s s a l r e a d y d e s c r i b e d f o r t h e p r e c e d i n g t h r e e p y r a z o l y l g a l l a t e r h o d i u m c o m p l e x e s a p p e a r s t o be l e s s f a c i l e f o r t h e b i s ( t r i p h e n y l p h o s p h i n e ) . compounds. - Most - 122 -l i k e l y t h e p r e s e n c e o f t h e two b u l k y t r i p h e n y l p h o s p h i n e l i g a n d s on t h e r h o d i u m atom slows'down t h e r a t e o f t h e f l u x i o n a l p r o c e s s p r o p o s e d f o r t h e s e c o m p l e x e s . V a r y i n g t h e t e m p e r a t u r e d i d l e a d t o t h e e x p e c t e d c h a n g e s i n t h e "'"H nmr s p e c t r a o f [ M e 2 G a ( p z ) 2 ] R h ( P P h 3 ) 2 as s e e n i n t h e 'GaMe 2' r e g i o n i n F i g u r e 42. Thus warming t h e sample s o l u t i o n b r o a d e n e d t h e two g a l l i u m m e t h y l s i n g l e t s , w h i l e c o o l i n g t h e s o l u t i o n t o - 8 0 ° c o n s i d e r a b l y s h a r p e n e d t h e s e s i n g l e t s . E a c h o f t h e n o v e l p y r a z o l y l g a l l a t e R h ( I ) c o m p l e x e s p r e -p a r e d were t e s t e d as p o t e n t i a l 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 e i t h e r 1-hexene o r c y c l o h e x e n e , u s i n g a gas u p t a k e a p p a r a t u s as d e s c r i b e d i n A p p e n d i x I . No h y d r o g e n u p t a k e by t h e o l e f i n s was o b s e r v e d i n e x p e r i m e n t s c o n d u c t e d a t t e m p e r a t u r e s r a n g i n g f r o m 25° t o 4 5 ° . 4.3.2 A t t e m p t e d P r e p a r a t i o n o f [ M e 2 G a ( p z " ) 2 ] R h ( X ) ( Y ) [ (X) (Y) = (CO) (CO) o r (COD) ] A t t e m p t s , t o p r e p a r e t h e d i c a r b o n y l and COD R h ( I ) c o m p l e x e s c o n t a i n i n g t h e s t e r i c a l l y more demanding [ M e 2 G a ( p z " ) 2 ] ~ l i g a n d were u n s u c c e s s f u l due t o t h e f a c i l e f o r m a t i o n o f t h e known d i m e r i c s p e c i e s , [ ( y - p z " ) R h ( C O ) 2 ] 2 and [ ( y - p z " ) R h ( C O D ) ] 2 ( 7 ) . D i s p r o p o r t i o n a t i o n o f t h e g a l l a t e l i g a n d was o c c u r r i n g , most l i k e l y e n h a n c e d by t h e r e a d y i n c o r p o r a t i o n o f t h e r e s u l t i n g 3,5 d i m e t h y l p y r a z o l y l m o i e t i e s i n t o t h e e x c e p t i o n a l l y s t a b l e b r i d g e d r h o d i u m d i n u c l e a r s p e c i e s , i . e . 124 -2 N a + [ M e 2 G a ( p z " ) 2 ] ~ [ M e 2 G a ( u - p z " ) ] 2 + + [ R h ( C O D ) C l ] 2 » [ ( y - p z " ) R h ( C O D ) ] 2 + 2NaCl C o r r o b o r a t i v e e v i d e n c e f o r t h i s p r o p o s a l was t h e i s o l a t i o n o f t h e 3,5 d i m e t h y l p y r a z o l y l b r i d g e d g a l l i u m d i m e r among t h e r e a c t i o n p r o d u c t s . U n t i l v e r y r e c e n t l y o n l y one s t r u c t u r e d e t e r m i n a t i o n o f a p y r a z o l y l b r i d g e d Rh(I) d i m e r , { ( y - p z ) R h ( C O ) [ P ( O P h ) 3 ] } 2 , had a p p e a r e d i n t h e l i t e r a t u r e ( 9 ) . To f u r t h e r p r o b e t h e s o l i d s t a t e p r o p e r t i e s o f s u c h d i m e r s , 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 s o f [ ( y - p z " ) R h ( C O ) 2 ] 2 and [ ( y - p z " ) R h ( C O D ) ] 2 were o b t a i n e d . F o l l o w -i n g t h e c o m p l e t i o n o f t h e s e two s t r u c t u r e s , a p a p e r d e s c r i b i n g t h e c r y s t a l and m o l e c u l a r s t r u c t u r e o f t h e r e l a t e d complex [ ( y - p z ) R h ( C O D ) ] 2 a p p e a r e d i n t h e l i t e r a t u r e ( 1 0 ) . I n e a c h o f t h e s t r u c t u r e s d e s c r i b e d h e r e ( F i g s . 43 and 44) t h e r h o d i u m atoms a r e i n d i s t o r t e d s q u a r e p l a n a r e n v i r o n m e n t s . B o t h o f t h e s e m o l e c u l e s d i s p l a y a p p r o x i m a t e C 2 v symmetry i n t h e s o l i d s t a t e . The c e n t r a l f e a t u r e o f t h e two s t r u c t u r e s i s t h e b o a t c o n f o r m a t i o n o f t h e s i x membered f R h - ( N - N ) 2 ~ R h i r i n g . The Rh-N d i s t a n c e s i n t h e COD complex [2.084(1) A] a r e s i g n i f i c a n t l y l o n g e r t h a n t h o s e i n t h e c a r b o n y l complex [2.063(6) A ] , p r e s u m a b l y due t o g r e a t e r s t e r i c i n t e r a c t i o n be-tween t h e p y r a z o l y l m e t h y l s and t h e COD l i g a n d . The s t e r i c i n t e r -f e r e n c e between t h e b r i d g i n g p y r a z o l y l s and t h e t e r m i n a l l i g a n d s r e s u l t s i n a f o l d i n g o f t h e fRh(N-N) -Rh} r i n g s , t h e COD com-- 125 -F i g u r e 43. M o l e c u l a r s t r u c t u r e o f [(y-pz")Rh(CO)„] F i g u r e 44. M o l e c u l a r s t r u c t u r e o f [ (y-pz ") Rh (COD) ] p l e x b e i n g more s t r a i n e d . The mean Rh**'Rh c r o s s - r i n g d i s t a n c e s [3.262(4) & f o r t h e c a r b o n y l and 3.1538(3) A f o r t h e COD complex] a r e c o n s i d e r a b l y s h o r t e r t h a n t h e 3.568 A R h * • « R h s e p a r a t i o n r e p o r t e d f o r { (y-pz) Rh (CO) [P (OPh) ] > 2 (9) and s i m i l a r t o .'the 3^:267 (2) A Rh* •• R h ^ d i s t a n c e 7 o i n , [' (y-pz) Rh (.COD) ] 2 (10).. ' A l t h o u g h t h e m e t a l - m e t a l d i s t a n c e s a r e s h o r t i n t h e p r e s e n t d i m e r i c s p e c i e s , t h e y a r e n o t s u p p o r t i v e o f any d i r e c t b o n d i n g i n t e r a c -- 126 -t i o n s between t h e two r h o d i u m c e n t r e s ( 8 9 ) . The d i h e d r a l a n g l e s between t h e two i n d e p e n d e n t s q u a r e p l a n a r Rh e n v i r o n m e n t s o f 0 o 7 8.7 f o r t h e c a r b o n y l complex and 71.7 f o r t h e COD complex a r e t h e s m a l l e s t r e p o r t e d f o r t h i s t y p e o f r h o d i u m d i m e r . T h i s same a n g l e f o r t h e [ ( y - p z ) R h ( C O D ) ] 2 complex i s 80.7° ( 1 0 ) . Thus, a l t h o u g h t h e o v e r a l l s t r u c t u r a l f e a t u r e s o f t h e d i n u c l e a r Rh s p e c i e s a r e s i m i l a r , s t e r i c i n t e r a c t i o n s between t h e b r i d g i n g p y r a z o l y l g r o u p s and t h e t e r m i n a l r h o d i u m l i g a n d s s i g n i f i c a n t l y e f f e c t t h e d e g r e e o f d e v i a t i o n f r o m p l a n a r i t y o f t h e f R h - ( N - N ) 2 ~ R n ^ c e n t r a l framework. T a b l e s o f c o m p l e t e bond d i s t a n c e s and bond a n g l e s f o r [ ( y - p z " ) Rh (CO) 2 ] 2 and [ ( y - p z " ) R h ( C O D ) ] 2 a r e i n c l u d e d i n A p p e n d i x I I . 4.3.3 [Me 2 G a ( p z " ) 2 ]Rh(CO) (PPh 3)_ D i s p r o p o r t i o n a t i o n o f , t h e [ M e 2 G a ( p z " ) 2 ] ~ l i g a n d t h w a r t e d e f f o r t s t o p r e p a r e b o t h t h e d i c a r b o n y l and COD R h ( I ) f o u r c o o r d i n a t e s p e c i e s c o n t a i n i n g t h i s b i d e n t a t e l i g a n d . A n o t h e r g r o u p has r e p o r t e d d i f f i c u l t i e s e n c o u n t e r e d w i t h t h e r e l a t e d "boron l i g a n d , [H 2B ( p z " ) 2 ] ~ . An ' u n i d e n t i f i e d b l a c k p r e c i p i t a t e ' was o b t a i n e d f r o m t h e r e a c t i o n o f [ H 2 B ( p z " ) 2 ] ~ w i t h [ R h ( C O ) 2 C l ] 2 ( 9 0 ) . However one p a p e r has d e s c r i b e d t h e i s o l a t i o n o f an a i r s e n s i t i v e s p e c i e s , [ H 2 B ( p z " ) 2 ] R h ( C O ) , f r o m t h e same r e a c t a n t s (86) . D u r i n g t h e p r e p a r a t i o n o f r h o d i u m c o m p l e x e s c o n t a i n i n g t h e [ M e 2 G a ( p z ) 2 ] ~ l i g a n d i t was o b s e r v e d t h a t t h e d i c a r b o n y l s p e c i e s was u n s t a b l e and c o u l d be s t a b i l i z e d by t h e s u b s t i t u t i o n - 127 -o f one CO g r o u p f o r PPh^. F o r t h i s r e a s o n t h e p r e p a r a t i o n o f [ M e 2 G a ( p z " ) 2 ] R h ( C O ) ( P P h 3 ) was u n d e r t a k e n . The "^H nmr s p e c t r u m o f t h e r e s i d u e r e m a i n i n g a f t e r t h e r e m o v a l o f THF f o l l o w i n g t h e a d d i t i o n o f [ M e 2 G a ( p z " ) 2 ] ~ t o [ R h ( C O ) 2 C l ] 2 and P P h 3 d i s s o l v e d t o g e t h e r i n THF, i n d i c a t e d t h e f o r m a t i o n o f ~75% o f t h e d e s i r e d p r o d u c t r e l a t i v e t o -25% t ( y - p z " ) R h ( C O ) ( P P h 3 ) ] 2 ( 9 1 ) . A t t e m p t e d s e p a r a t i o n o f t h e s e two r h o d i u m s p e c i e s by r e c r y s t a l l i z a t i o n r e s u l t e d i n t h e p r e f e r e n -t i a l p r e c i p i t a t i o n o f y e l l o w - o r a n g e n e e d l e s o f t h e d i m e r f r o m c o n c e n t r a t e d C H 2 C l 2 / n - h e x a n e s o l u t i o n s . The f i n a l p r o p o r t i o n s o f p u r e p r o d u c t s o b t a i n e d were a l m o s t r e v e r s e d f r o m t h e i n i t i a l s p e c t r o s c o p i c y i e l d s , t h e y i e l d o f [ M e 2 G a ( p z " ) 2 ] R h ( C O ) ( P P h 3 ) b e i n g -32% b a s e d upon t h e f o l l o w i n g p r o p o s e d r e a c t i o n ; 4 N a + [ M e 2 G a ( p z " ) 2 ] ~ + 2 [ R h ( C O ) 2 C 1 ] 2 + 4 P P h 3 • 2 [ M e 2 G a ( p z " ) 2 J R h ( C O ) ( P P h 3 ) + [ ( y - p z " ) R h ( C O ) ( P P h 3 ) ] 2 + [ M e 2 G a ( y - p z " ) ] 2 + 4NaCl + 4C0 The complex, [ M e 2 G a ( p z " ) 2 ] R h ( C O ) ( P P h 3 ) , was i s o l a t e d as l e -mon y e l l o w , a i r s t a b l e c r y s t a l s . The IR s p e c t r u m o f t h i s com-pound c o n t a i n e d a s i n g l e s t r o n g c a r b o n y l s t r e t c h a t 1985 cm ^. T h i s s t r e t c h i n g f r e q u e n c y c a n be compared t o t h a t p r e v i o u s l y o b s e r v e d f o r [ M e 2 G a ( p z ) 2 ] R h ( C O ) ( P P h 3 ) (1995 c m " 1 ) . I n a g r e e m e n t w i t h e a r l i e r r e p o r t e d b e h a v i o u r , t h e a l k y l s u b s t i t u e n t s on t h e p y r a z o l y l r i n g s i n c r e a s e t h e e l e c t r o n d o n a t i n g a b i l i t y o f t h e l i g a n d , c o n s e q u e n t l y l o w e r i n g t h e vCO v a l u e s . - 128 -The mass s p e c t r u m o f [ M e 2 G a ( p z " ) 2 ] R h ( C O ) ( P P h ^ ) c o n t a i n e d s i g n a l s a t t r i b u t a b l e t o i o n s a r i s i n g f r o m t h e e x p e c t e d f r a g -m e n t a t i o n o f t h i s m o l e c u l e . B e s i d e s a s m a l l s i g n a l due t o t h e p a r e n t i o n ( . 8 % ) , m a j o r s i g n a l s c o r r e s p o n d i n g t o P-Me + ( 9 2 . 6 % ) , P-Me-CO + (34.3%) and P-Me-CO-pz"-H + (100.0%) were a s s i g n a b l e . I t i s o f i n t e r e s t t o compare t h e room t e m p e r a t u r e "*"H nmr s p e c t r a o f [ M e 2 G a ( p z " ) 2 ] R h ( C O ) ( P P h 3 ) ( F i g . 45) and [ M e 2 G a ( p z ) 2 ] R h ( C O ) ( P P h 3 ) ( F i g . 3 9 ) . The f o r m e r complex d i s p l a y s two w e l l d e f i n e d s i n g l e t s i n t h e 'GaMe 2' r e g i o n and f o u r s h a r p s i n g l e t s i n t h e 'pzMe' r e g i o n o f t h e "'"H nmr s p e c t r u m . Thus t h e f l u x i o n a l p r o c e s s p r o p o s e d f o r t h e c o m p l e x e s i n c o r p o r a t i n g t h e [Me G a ( p z ) J l i g a n d i n S e c t i o n 4.3.1 i s c o n s i d e r a b l y l e s s f a c i l e 2 ^ 0 f o r t h e p r e s e n t m o l e c u l e d e s c r i b e d h e r e . T h i s c o u l d be a s t e r i c e f f e c t , t h e p y r a z o l y l m e t h y l s u b s t i t u e n t s d i s c o u r a g i n g r a p i d i n v e r s i o n o f t h e b o a t . c o n f o r m a t i o n , o r p o s s i b l y an e l e c t r o n i c e f f e c t r e s u l t i n g f r o m t h e i n c r e a s e d e l e c t r o n d e n s i t y r e s i d i n g on t h e r h o d i u m atom. 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 on a s i n g l e c r y s t a l o f [ M e 2 G a ( p z " ) 2 ] R h ( C O ) ( P P h 3 ) ( F i g . 46) c o n f i r m e d t h e b o a t c o n f o r m -a t i o n o f t h i s m o l e c u l e i n t h e s o l i d s t a t e . The complex i s r e l a t i v e l y s t r a i n e d and f o r t h e f Ga (N-N) 2~Rh-j s i x membered r i n g t o i n v e r t s u b s t a n t i a l i n t e r f e r e n c e between t h e p P h 3 s u b s t i t u e n t and t h e m e t h y l g r o u p a t t h e C(3) p o s i t i o n o f t h e p y r a z o l y l r i n g t r a n s t o t h e t e r m i n a l CO l i g a n d w o u l d have t o be o v e r c o m e . I t i s m ost l i k e l y t h i s i n t e r a c t i o n t h a t f o r c e s t h e m o l e c u l e t o r e m a i n r i g i d i n s o l u t i o n a t room t e m p e r a t u r e . " : ' l . ' . ' . n i I I l I l ) ' 1 ' " " " 1 1 1 1 1 1 I 1 " 1 " " • 1 1 1 1 " 1 " I " I i i i i i i i i i l i i i i l i i I i l . i I I l l I 2 3 4 5 6 7 8 9 10 X Figure 45. Room temperature 100 MHz H nmr spectrum of [Me_Ga (pz"). o]Rh(C0) (.PPh-) i n C r D , . 2 2. j 6 6 130 -F i g u r e 46. M o l e c u l a r s t r u c t u r e o f [ M e 2 G a ( p z " ) 2 ] R h ( C O ) ( P P h 3 ) . 4 . 4 Summary The s y n t h e s i s and c h a r a c t e r i z a t i o n o f t h e c o m p l e x e s [ M e 2 G a ( p z ) 2 ] R h ( X ) ( Y ) [(X) = CO o r P P h 3 , (Y) = CO o r P P h 3 ; (X ) ( Y ) = COD] h a v e been d e s c r i b e d . N o n r i g i d i t y i n s o l u t i o n has b een d e m o n s t r a t e d f o r t h e s e c o m p l e x e s by a s e r i e s o f v a r i a b l e temper-a t u r e "*"H nmr e x p e r i m e n t s . The r a t e o f t h e d y n amic s o l u t i o n mechanism p r o p o s e d i s d e p e n d e n t on t h e s i z e o f t h e (X) and (Y) s u b s t i t u e n t s . 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 o f t h e COD com-p l e x c o n f i r m e d t h e b o a t c o n f o r m a t i o n f o r t h e f G a - (N-N) 2 - R n ^ s^- x membered r i n g i n t h i s m o l e c u l e i n t h e s o l i d s t a t e . One r e l a t e d c o m p l e x i n c o r p o r a t i n g t h e b i d e n t a t e [ M e 2 G a ( p z " ) 2 ] l i g a n d has b een p r e p a r e d and compared t o i t s u n -s u b s t i t u t e d p y r a z o l y l a n a l o g . A g a i n s t e r i c f a c t o r s a f f e c t t h e s o l u t i o n b e h a v i o u r o f t h i s m o l e c u l e , t h a t i s , [ M e 2 G a ( p z " ) ^ ] R n ( C O ) ( P P h 3 ) was f o u n d t o be r i g i d i n s o l u t i o n a t room t e m p e r a t u r e . 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 o f t h i s c o m p l e x was i n a g r e e -ment w i t h t h e m o l e c u l a r s t r u c t u r e s u g g e s t e d by s p e c t r a l d a t a . - 131 -CHAPTER V RHODIUM DERIVATIVES OF TRIDENTATE PYRAZOLYLGALLATE LIGANDS 5 .1 I n t r o d u c t i o n I n 1961 E.O. F i s c h e r and K. B i t t l e r r e p o r t e d t h e s y n t h e -s i s o f (n 5-C^Hi-) Rh (CO) 2 f r o m s o d i u m c y c l o p e n t a d i e n i d e and [ R h ( C O ) 2 C l ] 2 ( 9 2 ) . A m i n o r c o n t r o v e r s y a r o s e o v e r t h e i r s u b -s e q u e n t f i n d i n g t h a t ( n 5 - C 5 H ^ ) R h ( C O ) 2 d i m e r i z e d t o f o r m [ (n 5-C^Hj.) Rh (CO) 2 ] 2 upon e x p o s u r e t o a i r ( 9 3 ) . T h i s d i m e r s u p p o s e d l y c o n t a i n e d two b r i d g i n g CO g r o u p s b u t no f o r m a l Rh—Rh'^bond, an u n p r e c e d e n t e d e x c e p t i o n t o t h e g e n e r a l i z a t i o n t h a t b r i d g e d c a r b o n y l g r o u p s do n o t o c c u r u n l e s s t h e b r i d g e d m e t a l atoms a r e f o r m a l l y bonded t o e a c h o t h e r (68) . However i t has s i n c e b een f o u n d t h a t t h e s p e c i e s , ' [ ( n 5 - C ^ H 5 ) R h ( C O ) 2 ] 2 ' n e v e r i n f a c t e x i s t e d , t h e c o r r e c t i d e n t i f i c a t i o n o f t h i s compound b e i n g ( n 5 - C 5 H 5 ) 2 R h 2 ( P ~ C O ) ( C O ) 2 (94, 9 5 ) , a d i m e r w h i c h does c o n t a i n a R h — R h s i n g l e bond as w e l l as one b r i d g i n g CO l i n k a g e . The monomeric p y r a z o l y l g a l l a t e complex [ M e G a ( p z ) ^ ] R h ( C O ) ^ has n o t been p r e p a r e d t o d a t e . However t h e r e a c t i o n o f t h e [ M e G a ( p z ) 3 ] ~ l i g a n d w i t h [ R h ( C O ) 2 C l ] 2 r e s u l t e d i n t h e n o v e l t r i p l y c a r b o n y l b r i d g e d d i m e r [ M e G a ( p z ) 3 ] 2 R n 2 ( U _ C 0 ) 3 , a com-pound w i t h t h e same f o r m u l a t i o n as t h e c y c l o p e n t a d i e n y l a n a l o g (n 5-C rH r.) _Rh» (y-CO) (CO) „ . 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 o f 3 O 2 2. 2. [MeGa (pz) _.] ~ Rh 9 (y-CO) _ i n d i c a t e d t h a t a l l t h r e e c a r b o n y l g r o u p s - 132 -o c c u p y b r i d g i n g p o s i t i o n s . I n a d d i t i o n t h e R h — R h s e p a r a t i o n i n t h i s m o l e c u l e o f 2.5818(8) i l i s among t h e s h o r t e s t s u c h s i n g l e bond d i s t a n c e s e v e r r e p o r t e d . A c o m p a r i s o n o f t h e p r o p e r t i e s o f t h i s u n u s u a l d i m e r w i t h t h o s e o f r e l a t e d c y c l o -p e n t a d i e n y l and p y r a z o l y l b o r a t e s p e c i e s i s d i s c u s s e d i n d e t a i l . The u n s y m m e t r i c m o n o ( 1 - p y r a z o l y l ) g a l l a t e t r i d e n t a t e l i g a n d [Me 2Ga (pz). (OCH 2CH 2NMe 2) ] " r e a c t e d w i t h [ R h ( C O ) 2 C l ] 2 t o y i e l d a m i x t u r e o f [ M e 2 G a ( p z ) ( O C H 2 C H 2 N M e 2 ) ] R h ( C O ) (n=l and 2 ) . I n t h e s e c o m p l e x e s t h e t r i d e n t a t e l i g a n d i s c o o r d i n a t e d i n a m e r i d i o n a l manner, t h u s t h e s e compounds c o n -s t i t u t e t h e f i r s t e xamples o f t r a n s i t i o n m e t a l c a r b o n y l s p e c i e s c o n t a i n i n g a m e r i d i o n a l u n s y m m e t r i c t r i d e n t a t e p y r a z o l y l g a l l a t e l i g a n d . D i f f i c u l t y was e n c o u n t e r e d i n s e p a r a t i n g t h e mono-c a r b o n y l and b i s c a r b o n y l c o m p l e x e s , however s p e c t r o s c o p i c e v i -d e n c e i s p r e s e n t e d i n s u p p o r t o f t h e i r e x i s t e n c e . A THF s o l u t i o n c o n t a i n i n g [ M e 2 G a ( p z ) ( O C H 2 C H 2 N M e 2 ) ] R h ( C O ) n (n=l and 2) r e a c t e d w i t h PPh^ g i v i n g a q u a n t i t a t i v e y i e l d o f t h e s t a b l e r h o d i u m d i m e r [ ( y - p z ) R h ( C O ) ( P P h ^ ) ] 2 • The f i r s t example o f a p y r a z o l y l g a l l a t e compound c o n -t a i n i n g two d i f f e r e n t t r a n s i t i o n m e t a l s has b e en p r e p a r e d , namely [ M e G a ( p z ) ^ ] M o R h ( u - C O ) 2 ( C O ) ( P P h ^ ) 2 . T h i s c o m p l ex, i s o -l a t e d f r o m t h e r e a c t i o n o f W i l k i n s o n ' s c a t a l y s t and [MeGa(pz) ]Mo(CO)^ , i s p r o p o s e d t o c o n t a i n m u l t i p l e bond c h a r a c t e r , . a c o n d i t i o n n e c e s s a r y t o s a t i s f y an a c c e p t a b l e e l e c -t r o n c o u n t a b o u t b o t h t r a n s i t i o n m e t a l s . - 133 -E a c h o f t h e p y r a z o l y l g a l l a t e r h o d i u m c o m p l e x e s p r e p a r e d and d i s c u s s e d i n t h i s c h a p t e r were t e s t e d as p o t e n t i a l 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 1-hexene o r c y c l o h e x e n e . A t t e m p e r a -t u r e s r a n g i n g between 30° and 50° no c a t a l y t i c a c t i v i t y was o b s e r v e d . P a r t s o f t h i s c h a p t e r have been s u b m i t t e d f o r f u t u r e p u b l i c a t i o n (96) . . .- - ~" . ... -_• ••' 5. 2 E x p e r i m e n t a l 5.2.1 S t a r t i n g M a t e r i a l s I o d i n e and b r o m i n e ( A l d r i c h ) were u s e d as s u p p l i e d 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 . A s t a n d a r d s o l u t i o n o f [ M e G a ( p z ) 3 ] Mo(CO)^ i n THF was p r e p a r e d as d e s c r i b e d i n t h e l i t e r a t u r e (31, 58) . 5.2.2 P r e p a r a t i o n o f T r i ( u - c a r b o n y l ) b i s [ m e t h y l t r i s -( 1 - p y r a z o l y l ) g a l l a t o ] d i r h o d i u m 2 N a + [ M e G a ( p z ) 3 ] ~ + [ R h ( C O ) 2 C l ] 2 ™ F > [ M e G a ( p z ) 3 ] 2 R h 2 ( y - C O ) 3 + 2NaCl + CO Two m o l a r e q u i v a l e n t s o f t h e a p p r o p r i a t e l i g a n d i n 100 ml THF were added t o • [ R h ( C O ) 2 C 1 ] 2 (.348 g, .895 mmol) d i s s o l v e d i n 20 ml THF. The r e s u l t i n g m i x t u r e was r e f l u x e d f o r 8 h d u r i n g w h i c h t i m e t h e i n i t i a l l y o r a n g e c o l o u r e d s o l u t i o n t u r n e d lemon y e l l o w . The r e a c t i o n m i x t u r e was c o o l e d , f i l t e r e d and t h e s o l v e n t . a l l o w e d t o e v a p o r a t e o f f s l o w l y . The r e m a i n i n g y e l l o w r e s i d u e was r e c r y s t a l l i z e d f r o m C H 2 C l 2 / b e n z e n e , r e s u l t i n g i n lemon y e l l o w n e e d l e s . T h e s e c r y s t a l s a n a l y z e d c o r r e c t l y f o r a - 134 -1:1 b e n z e n e s o l v a t e c o m p l e x, i . e . [ M e G a ( p z ) 3 ] 2 R n 2 ( u - c ° ) 3 * C 6 H 6 " To remove t h e be n z e n e i t was s u f f i c i e n t t o f i n e l y g r i n d t h e p r o d u c t and d r y i t in vacuo f o r ~36 h a t 4 5 ° . Y i e l d ~83%. A n a l . C a l ' d . f o r [ M e G a ( p z ) 3 ] 2 R h 2 ( y - C O ) 3 : C 32.05, H 2.79, N 19.51; F o u n d : C 31.75, H 2.90, N 19.20. v C O ( c m _ 1 ) : 1825 v s ( N u j o l ) ; 1827 v s ( C H 2 C 1 2 ) . 1 H nmr ( T , C 6 D 6 , F i g . 4 7 ) : -GaMe, 9.83s; p z - 4 H , 3.88t; p z - 5 H , 2.78d; p z - 3 H , 1.93d; J„„„„ = ~2 Hz f o r pz p r o t o n s . 5.2.3 R e a c t i o n s o f [ M e G a ( p z ) 3 ] 2 R h 2 ( y - C O ) 3 i ) p p h 3 : w h e n [ M e G a ( p z ) 3 ] 2 R h 2 ( y - C O ) 3 (.074 g, .086 mmol) and P P h 3 (.045 g, .172 mmol) were d i s s o l v e d i n 30 ml THF and s t i r r e d o v e r n i g h t , IR s p e c t r a o f t h e s o l u t i o n i n d i c a t e d t h e p r e s e n c e o f o r i g i n a l s t a r t i n g m a t e r i a l s o n l y . However when t h e same r e a c t i o n s o l u t i o n was r e f l u x e d f o r 2 h t h e o n l y r h o d i u m p r o d u c t r e m a i n i n g was [ (y-pz)Rh(CO) ( P P h 3 ) ] 2 . i i ) B r 2 : [MeGa(pz) ] 2 R h 2 ( y - C O ) 3 (.052 g, .060 mmol) was d i s s o l v e d i n 30 ml C H 2 C 1 2 and B r 2 (.019 g, .119 mmol) added dropwise by s y r i n g e . The s o l u t i o n was s t i r r e d f o r 1 h a f t e r which time IR sampling i n d i c a t e d the complete disappearance of the s t a r t i n g rhodium c a r b o n y l s p e c i e s . A s i n g l e metal c a r b o n y l band remained [ v C O ( c m _ 1 ) : 2125 ( C H 2 C 1 2 ) ] , a t t r i b u t a b l e to [MeGa(pz) 3]Rh(CO)Br 2. This Rh(III) product was i s o l a t e d as an a i r s t a b l e orange s o l i d i n ~75% y i e l d . i i i ) I 2 : The r e a c t i o n w i t h i o d i n e was c a r r i e d o u t i n a - 135 -s i m i l a r manner t o t h a t d e s c r i b e d i n i i ) f o r t h e a n a l o g o u s b r o m i n e c a s e w i t h t h e e x c e p t i o n t h a t I 2 was added as an e t h e r e a l s o l u t i o n . A b l a c k s o l i d was i s o l a t e d i n -95% y i e l d . T h i s s o l i d was f i n e l y g r o u n d and d r i e d f o r 24 h in vaouo a t 5 0 ° . D u r i n g t h i s t i m e no f r e e 1^ s u b l i m e d o u t o f t h e r e a c t i o n p r o d u c t . The IR s p e c t r u m o f t h e s o l i d c o n t a i n e d a s i n g l e band i n t h e c a r b o n y l r e g i o n [ v C O ( c m - 1 ) : 2100 ( C H 2 C 1 2 ) ] . 5.2.4 R e a c t i o n o f [MeGa(pz") ] " and [ R h ( C O ) 2 C l ] 2 The l i g a n d [ M e G a ( p z " ) 3 ] ~ was r e a c t e d w i t h [ R h ( C O ) 2 C l ] 2 u s i n g a s i m i l a r p r o c e d u r e t o t h a t d e s c r i b e d i n s e c t i o n 5.2.2. The o n l y r h o d i u m c o n t a i n i n g p r o d u c t i s o l a t e d was [ ( y - p z " ) R h ( co ) 2 ] 2 . 5.2.5 R e a c t i o n o f [ M e G a ( p z ) 3 ] ~ and [ R h ( C O D ) C l ] 2 Two m o l a r e q u i v a l e n t s o f t h e a p p r o p r i a t e g a l l a t e l i g a n d were added t o [ R h ( C O D ) C l ] 2 (.297 g, .603 mmol) d i s s o l v e d i n 25 ml THF. The c l e a r y e l l o w s o l u t i o n i m m e d i a t e l y t u r n e d c l o u d y . A f t e r s t i r r i n g f o r 20 h t h e THF was removed in vaouo and t h e r e m a i n i n g r e s i d u e r e d i s s o l v e d i n b e nzene and f i l t e r e d . The s l o w e v a p o r a t i o n o f b e nzene l e f t l a r g e , c u b i c o r a n g e c r y s t a l s o f [ (u-pz)Rh(COD) ) 2 . 5.2.6 P r e p a r a t i o n o f [ M e 2 G a ( p z ) (OCH 2CH 2NMe 2)]Rh(CO) (n = 1 and 2) Two m o l a r e q u i v a l e n t s o f N a + [ M e 2 G a ( p z ) ( O C H 2 C H 2 N M e 2 ) ] ~ i n - 136 -THF were added d r o p w i s e t o [ R h ( C O ) 2 C l ] 2 (.317 g, .815 mmol) d i s s o l v e d i n ~25 ml THF a t - 7 8 ° . A f t e r t h e a d d i t i o n o f t h e l i g a n d (~.5 h) t h e r e a c t i o n m i x t u r e was a lemon y e l l o w c o l o u r . However as t h e r e a c t i o n s o l u t i o n warmed t o room, t e m p e r a t u r e t h e c o l o u r g r a d u a l l y c h a n g e d t o d a r k brown. The s o l u t i o n was f i l t e r e d and t h e s o l v e n t removed in vacuo, y i e l d i n g a d a r k brown s o l i d . F o l l o w i n g t h e same p r o c e d u r e as d e s c r i b e d a bove, b u t n o t a l l o w i n g t h e r e a c t i o n s o l u t i o n t o warm above 0 ° , r e s u l t e d i n t h e i s o l a t i o n o f t h e same d a r k brown s o l i d . T h i s s o l i d was shown t o c o n t a i n b o t h [ M e 2 G a ( p z ) ( O C H 2 C H 2 N M e 2 ) ] R h ( C O ) (n = 1 and 2 ) . A n a l y t i c a l l y p u r e samples o f t h e s e two components c o u l d n o t be s e p a r a t e d . 5.2.7 R e a c t i o n o f [ M e 2 G a ( p z ) ( O C H 2 C H 2 N M e J ] R h ( C O ) (n = 1 and 2) w i t h PPh-, [ M e 2 G a ( p z ) ( O C H 2 C H 2 N M e 2 ) ] R h ( C O ) n (n = 1 and 2) (.242 g, -.605 mmol) were d i s s o l v e d i n 100 ml THF. Upon t h e a d d i t i o n o f one m o l a r e q u i v a l e n t o f P P h 3 , t h e d a r k brown r e a c t i o n s o l u t i o n i m m e d i a t e l y l i g h t e n e d i n c o l o u r . A f t e r s t i r r i n g f o r 8 h a t room t e m p e r a t u r e , t h e THF was removed in vacuo l e a v i n g a y e l l o w - o r a n g e r e s i d u e c o n t a i n i n g a m i x t u r e o f [ ( y - p z ) R h ( C O ) ( P P h 3 ) ] 2 and [ M e 2 G a ( O C H 2 C H 2 N M e 2 ) ] 2 . The g a l l i u m d i m e r was removed in vacuo, l e a v i n g an a n a l y t i c a l l y p u r e sam-p l e o f [ ( y - p z ) R h ( C O ) ( P P h 3 ) ] 2 . - 137 -5.2.8 P r e p a r a t i o n o f [MeGa (pz) 3 ]MoRh (y-CO) 2 (CO) (PPh-,) 2 - T H F [MeGa (pz) 3JMo (CO) 3 + R h ( P P h 3 ) 3 C l — — — » -[ M e G a ( p z ) 3 ] M o R h ( y - C O ) 2 ( C O ) ( P P h 3 ) 2 + P P h 3 + C l " One m o l a r e q u i v a l e n t o f [ M e G a ( p z ) 3 ] M o ( C O ) 3 d i s s o l v e d i n 15.0 ml THF was added d r o p w i s e t o R h ( P P h 3 ) 3 C l (.397 g, .429 mmol) d i s s o l v e d i n 100 ml THF a t 0 ° . The d a r k r e d r e a c t i o n m i x t u r e was a l l o w e d t o warm s l o w l y t o room t e m p e r a t u r e . A f t e r s t i r r i n g f o r -15 h t h e s o l u t i o n was f i l t e r e d and t h e s o l v e n t removed lin-.vacuo l e a v i n g a r e d brown r e s i d u e . T h i s r e s i d u e was s c r a p e d i n t o a powder and t h e f r e e P P h 3 removed by s u b l i m a t i o n in vacuo a t ~ 7 0 ° . A n a l . C a l ' d . f o r [ M e G a ( p z ) 3 ] M o R h ( y - C O ) 2 ( C O ) ( P P h 3 ) 2 : C 53.83, H 3.87, N 7.68; Found: C 54.16, H 3.56, N 7.36. v C O ( c m - 1 ) : 1870 br,med; 1754 b r , s t • ( C H 2 C 1 2 ) . 1 H nmr ( T , C g D 6 ) : -GaMe, 9.99s; p z - 4 H , 4.05t; p z - 3 H o r p z - 5 H , 2.69d; -PPh.,, 2.99m, 2.11m; J = 2 Hz f o r pz p r o t o n s . 5 . 3 R e s u l t s and D i s c u s s i o n 5.3.1 [MeGa(pz) 3 J _ 2 R h 2 (y-CO) 3 _ The r e a c t i o n o f N a + [ M e G a ( p z ) 3 ] ~ and [ R h ( C O ) 2 C l ] 2 r e s u l t e d i n t h e u n u s u a l t r i p l y c a r b o n y l b r i d g e d d i r h o d i u m complex, [ M e G a ( p z ) 3 ] 2 R h 2 ( y - C O ) 3 . T h i s p r o d u c t c r y s t a l l i z e d as lemon y e l l o w n e e d l e s w h i c h d a r k e n e d i n c o l o u r a t -240° when h e a t e d . The ''"H nmr s p e c t r u m o f t h i s compound ( F i g . 47) i n d i c a t e d t h e p r e s e n c e o f e q u i v a l e n t p y r a z o l y l r i n g s i n s o l u t i o n . T h i s s p e c -trum r e m a i n e d v i r t u a l l y t h e same when o b t a i n e d a t e i t h e r room F i g u r e 47. Room t e m p e r a t u r e 27 0 MHz H nmr s p e c t r u m f o r [ M e G a ( p z l 3 ] 2 R h 2 C P - C O ) 3 i n CgDg. - 139 -t e m p e r a t u r e o r -7 0° i n ( C D 3 ) 2 C O . From t h e m e a s u r e d i n t e g r a -t i o n t h e r a t i o o f p y r a z o l y l g r o u p s t o 1Ga-Me' s u b s t i t u e n t s c a n be e a s i l y c a l c u l a t e d t o be 3:1. The IR s p e c t r u m o f t h e above complex c o n t a i n e d one s t r o n g band i n t h e b r i d g i n g c a r b o n y l r e g i o n and was v o i d o f any s i g -n a l s i n t h e t e r m i n a l c a r b o n y l r e g i o n . From t h e IR and "^H nmr s p e c t r a l e v i d e n c e a h i g h l y s y m m e t r i c d i m e r i c m o l e c u l e was p o s t -u l a t e d i n w h i c h b r i d g i n g CO g r o u p s l i n k t h e two r h o d i u m atoms. 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 c o n f i r m e d t h i s p r e d i c t i o n . F i g u r e 48. M o l e c u l a r s t r u c t u r e o f [ M e G a ( p z ) 3 ] 2 R h 2 ( y - C O ) 3 . The c r y s t a l s t r u c t u r e o f [ M e G a ( p z ) _ ] „ R h 9 ( y - C O ) _ * C f i H f i c o n -- 140 -s i s t s o f w e l l s e p a r a t e d complex and benzene s o l v a t e m o l e c u l e s . The r h o d i u m m o l e c u l e has a p p r o x i m a t e symmetry i n t h e s o l i d s t a t e , i n agreement w i t h t h e e v i d e n c e d i s c u s s e d p r e v i o u s l y f o r t h e complex i n s o l u t i o n . The c r y s t a l p o s s e s s e s f a c e - s h a r e d b i o c t a h e d r a l g e o m e t r y , t h e R h — R h bond r e s u l t i n g i n a s e v e n -c o o r d i n a t e c a p p e d o c t a h e d r a l a r r a n g e m e n t a b o u t e a c h r h o d i u m c e n t r e . The b e n z e n e s o l v a t e m o l e c u l e s c o u l d be removed f r o m t h e c r y s t a l l a t t i c e by f i n e l y g r i n d i n g t h e s o l i d and d r y i n g t h e r e s u l t i n g powder in vaouo w i t h s l i g h t h e a t i n g f o r s e v e r a l d a y s . I n t h i s way an a n a l y t i c a l l y p u r e , s o l v a t e f r e e sample was o b t a i n e d . The mass s p e c t r u m o f t h e b e n z e n e f r e e p r o d u c t c l e a r l y showed t h e p a r e n t i o n , P + ( 2 8 . 0 % ) , and a s t r o n g s i g n a l a t t r i b u -t a b l e t o t h e P-2CO-2Me + i o n (91.2%) r e l a t i v e t o t h e h i g h e s t i n t e n s i t y i o n , p z H + ( 1 0 0 . 0 % ) . I t i s o f i n t e r e s t t o compare [ M e G a ( p z ) ^ ] 2 R ^ 2 ( ^ " C O ) 3 t o r e l a t e d compounds c o n t a i n i n g e i t h e r t h e c y c l o p e n t a d i e n y l o r t h e t r i s ( 1 - p y r a z o l y l ) b o r a t e l i g a n d s . B o t h t h e monomeric c y c l o p e n t a -d i e n y l r h o d i u m d i c a r b o n y l complex, (r\5-C^H^)Rh(CO)2 ( 9 2 ) , and t h e 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 a n a l o g , (n 5-C,-Me,-)Rh(CO) 2 ( 9 7 ) , a r e s t a b l e e n t i t i e s a t room t e m p e r a t u r e . However a t t e m p t s t o p r e p a r e t h e c o r r e s p o n d i n g monomer, [ M e G a ( p z ) ^ ] R h ( C O ) 2 * have so f a r been u n s u c c e s s f u l . The e l u s i v e n a t u r e o f t h i s p y r a z o l y l g a l -l a t e compound r e s e m b l e s t h e r e p o r t e d i n a b i l i t y t o s y n t h e s i z e t h e - 1 4 1 -r e l a t e d b o r o n a n a l o g , [ H B ( p z ) 3 ] R h ( C O ) 2 (98, 9 9 ) . However [HB (pz" ) 3 ]Rh (CO) 2 r c o n t r a r y , t o two r e p o r t s (90, 9 8 ) , c a n a p p a r -e n t l y be i s o l a t e d as y e l l o w c r y s t a l s i n h i g h y i e l d (7, 1 0 0 ) . Our a t t e m p t s t o p r e p a r e a g a l l i u m a n a l o g o f t h i s s p e c i e s , i . e . [ M e G a ( p z " ) 3 ] R h ( C O ) 2 r have r e s u l t e d i n t h e i s o l a t i o n o f t h e d i m e r [ ( y - p z " ) R h ( C O ) 2 ] 2 a s t n e o n l y r h o d i u m c o n t a i n i n g p r o d u c t . The c y c l o p e n t a d i e n y l r h o d i u m c o m p l e x e s ( n 5-C j-R,-) Rh (CO) 2 (R=H o r Me) c a n be c o n v e r t e d i n t o a v a r i e t y o f a s s o c i a t e d r h o d i u m s p e c i e s (95, 101-104). Of p a r t i c u l a r i n t e r e s t i s t h e p h o t o l y s i s o f ( n 5 - C ^ H ^ ) R h ( C O ) ^ i r e s u l t i n g i n t h e f o r m a t i o n o f ( n 5 - C 5 H 5 ) 2 R h 2 ( P - C O ) ( C O ) 2 , a compound w i t h t h e same f o r m u l a t i o n as t h e p r e s e n t p y r a z o l y l g a l l a t e c omplex. T h i s c y c l o p e n t a d i e n y l m o l e c u l e has a l s o b e en s t r u c t u r a l l y c h a r a c t e r i z e d ( 9 5 ) . I t d i s p l a y s a m a r k e d l y d i f f e r e n t g e o m e t r y f r o m t h a t o f [ M e G a ( p z ) 3 ] 2 R h 2 ( y - C O ) 3 as o n l y one b r i d g i n g CO g r o u p i s p r e s e n t , t h e o t h e r two c a r b o n y l s a p p e a r i n g as t e r m i n a l CO l i g a n d s . I t i s c o n -j e c t u r e d t h a t t h e s t e r i c r e q u i r e m e n t o f t h e b u l k y [ M e G a ( p z ) 3 ] l i g a n d v e r s e s t h e ( n 5 - C 5 H , - ) l i g a n d f o r c e s a ( y - C O ) ^ a r r a n g e m e n t i n t h e p y r a z o l y l g a l l a t e m o l e c u l e . B o t h t h e [ M e G a ( p z ) 3 ] 2 R h 2 ( y - C O ) 3 [2.5818(8) K] and t h e ( n 5 - C 5 H 5 ) 2 R h 2 ( y - C O ) ( C O ) 2 [2.681(2) A] c o m p l e x e s c o n t a i n a R h — R h s i n g l e bond, t h e m e t a l -m e t a l s e p a r a t i o n b e i n g c o n s i d e r a b l y s h o r t e r i n t h e t r i p l y b r i d g e d g a l l a t e m o l e c u l e . R e c e n t l y s t a b l e s o l i d s , a n a l y z i n g c o r r e c t l y f o r t h e f o r m u l a t i o n { [ R B ( p z ) 3 ] 2 R h 2 ( C O ) 3 > n (R=H o r pz) ( 9 9 ) , have been - 142 -p r e p a r e d f r o m t h e r e a c t i o n o f CO w i t h e i t h e r [ R B ( p z ) 3 ] R h ( C 2 H 4 ) 2 o r [RB(pz)^]Rh(COD) . The h y d r o t r i s ( 1 - p y r a z o l y l ) b o r a t e r h o d i u m s p e c i e s ( i . e . R=H) was a l s o p r e p a r e d by t h e a d d i t i o n o f [ H B ( p z ) 3 ] ~ t o [ R h ( C O ) 2 C l ] 2 i n C H 2 C 1 2 and m e t h a n o l . These two p y r a z o l y l b o r a t e c o m p l e x e s were f o u n d t o be i n s o l u b l e i n o r g a n i c s o l v e n t s and c o n s e q u e n t l y "^ H nmr d a t a were n o t o b t a i n a b l e . B a s e d upon t h i s l i m i t e d s o l u b i l i t y t h e p o s s i b l e e x i s t e n c e o f p o l y m e r i c s t r u c t u r e s w i t h p o l y ( 1 - p y r a z o l y l ) b o r a t e l i g a n d s l i n k i n g [ R h 2 ( C O ) 3 ] u n i t s were i n i t i a l l y p o s t u l a t e d . However IR s p e c t r a l d a t a f o r t h e s e same two compounds s u g g e s t e d a d i m e r i c s p e c i e s w i t h t h r e e b r i d g i n g c a r b o n y l l i g a n d s . {Both c o m p l e x e s i n KBr d i s p l a y e d one vCO band a t 1845 cm 1 (R=H) and 1839 cm 1 (R=pz).} B a s e d upon t h e c h a r a c t e r i z a t i o n o f [ M e G a ( p z ) 3 ] 2 R h 2 ( y - C O ) 3 i t now seems h i g h l y l i k e l y t h a t t h e s e p y r a z o l y l b o r a t e s p e c i e s a r e i n f a c t s t r u c t u r a l i s o m e r s o f t h e t r i p l y c a r b o n y l b r i d g e d p y r a z o l y l g a l l a t e d i m e r , i . e . [ R B ( p z ) 3 ] 2 R h 2 ( y - C O ) 3 . Compared t o t h e o b s e r v e d i n s o l u b i l i t y o f [ R B ( p z ) 3 ] 2 R h 2 ( y - C O ) 3 , c r y s t a l s o f [ MeGa (pz) 3 ] 2 Rh 2 (y -CO) 3 were s l i g h t l y s o l u b l e i n n o n p o l a r s o l v e n t s s u c h as b e n z e n e and hexane and v e r y s o l u b l e i n C H 2 C 1 2 and a c e t o n e . The 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 [ MeGa ( p z ) ^ ] 2 R n 2 ^ y ~ C 0 ^ 3 ^ a s i n d i c a t e d t h e p r e s e n c e o f w e l l s e p a -r a t e d m o l e c u l a r u n i t s , r u l i n g o u t t h e p o s s i b i l i t y o f any s t r o n g i n t e r m o l e c u l a r b o n d i n g . Due t o t h e i n a b i l i t y t o grow c r y s t a l s o f t h e p y r a z o l y l b o r a t e a n a l o g s 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 on t h e s e compounds has n o t b e en p o s s i b l e . Thus t h e p r e s e n c e o f some d e g r e e o f i n t e r m o l e c u l a r b o n d i n g may a c c o u n t f o r t h e - 143 -o b s e r v e d i n s o l u b i l i t y o f t h e b o r a t e c o m p l e x e s . D e c a r b o n y l a t i o n o f ( n 5 - C ^ M e ^ ) R h ( C O ) 2 c a n l e a d t o t h e d i -r h o d i u m complex ( n 5 - C ^ M e ^ ) 2 R n 2 ( U - C 0 ) 2 i a m o l e c u l e p o s s e s s i n g two b r i d g i n g c a r b o n y l g r o u p s and a f o r m a l d o u b l e bond between t h e r h o d i u m c e n t r e s (103, 1 0 4 ) . The a d d i t i o n o f d i a z o a l k a n e s t o t h i s d i m e r has l e d t o p r o d u c t s o f two s t r u c t u r a l t y p e s , d e p e n d -i n g on t h e R g r o u p s a t t a c h e d t o t h e b r i d g i n g c a r b e n e m o i e t y . I n t h e f i r s t t y p e t h e a r r a n g e m e n t i s s i m i l a r t o t h a t o f ( n 5 - c ^ H , - ) 2 R h 2 ( y - C O ) ( C O ) 2 , t h e two CO g r o u p s becoming t e r m i n a l l y c o o r d i -n a t e d w h i l e t h e c a r b e n e o c c u p i e s a b r i d g i n g p o s i t i o n . The s e c o n d t y p e i s s t r u c t u r a l l y s i m i l a r t o t h e t r i p l y b r i d g e d p y r a z o l y l g a l l a t e m o l e c u l e d i s c u s s e d i n t h i s s e c t i o n . I n t h i s a r r a n g e m e n t t h e b r i d g i n g c a r b e n e d o e s n o t a l l o w t h e (n 5-C 5Me^) g r o u p s t o t i l t f r o m t h e i r p o s i t i o n s a t r i g h t a n g l e s t o t h e R h — R h bond a x i s , c o n s e q u e n t l y a t r i p l y b r i d g e d s y s t e m i s ob-s e r v e d , v i z . ( n 5 - C 5 M e 5 ) 2 R h 2 ( y - C O ) 2 ( y - C R 2 ) ( 1 0 4 ) . The R h — R h bond d i s t a n c e i n t h i s y - c a r b e n e complex (where CR 2 = t e t r a -b r o m o c y c l o p e n t a d i e n y l i d e n e ) has been d e t e r m i n e d t o be 2.612(2) A. T h i s d i s t a n c e , a l t h o u g h s h o r t e r t h a n t h e l o w e s t l i m i t q u o t e d by Cowie and Dwight as a r a n g e f o r R h — R h s i n g l e bond d i s t a n c e s (2.617-2.8415 A) ( 8 9 ) , i s c o n s i d e r a b l y l o n g e r t h a n t h e R h — R h s e p a r a t i o n o b s e r v e d i n t h e p r e s e n t p y r a z o l y l g a l l a t e m o l e c u l e . R e c e n t l y a c o m m u n i c a t i o n has a p p e a r e d d e s c r i b i n g t h e o n l y o t h e r t r i p l y c a r b o n y l b r i d g e d R h — R h s p e c i e s r e p o r t e d t o d a t e + 2 (1 0 5 ) . The m o l e c u l e c o n s i s t s o f a [Rh(y-CO)-Rh] u n i t h e l d - 144 -i n s i d e t h e c a v i t y o f a h e x a d e n t a t e c r y p t a t e - l i k e c y c l i c l i g a n d . F i g u r e 49. { [ H N C C H 2 C H 2 N H C H 2 C H 2 ) 2 0 ] 2 R h 2 ( y - C O ) } + 2 T h i s c a t i o n has s t r i k i n g s i m i l a r i t i e s t o [ M e G a ( p z ) 3 ] 2 R h 2 ( y - C O ) as e a c h r h o d i u m atom i s bonded t o t h r e e b r i d g i n g c a r b o n y l s and t h r e e a m i n e - l i k e n i t r o g e n s . I n a d d i t i o n c r y s t a l d a t a a v a i l a b l e on t h e r h o d i u m c a r b o n y l c r y p t a t e m o l e c u l e d e s c r i b e s a R h — R h d i s t a n c e o f 2.58 K, v i r t u a l l y i d e n t i c a l t o t h e R h — R h s e p a r a t i o n o f 2.5818(8) i f o u n d i n [ M e G a ( p z ) 3 ] 2 R h 2 ( y - C O ) 3 . These d i s t a n c e s a r e t h e s h o r t e s t R h — R h s i n g l e bond l e n g t h s e v e r r e p o r t e d . [ M e G a ( p z ) 3 ] 2 R h 2 ( y - C O ) 3 c a n a l s o be compared t o o t h e r •M ( y - C O ) 3 ' s y s t e m s s u c h as ( n 5 - C 5 M e 5 ) 2 R e 2 ( y - C O ) 3 ( 1 0 6 ) , ( n 4 - C 4 R 4 ) 2 F e 2 ( y - C O ) 3 (107) and ( n 6 - C 6 H 6 ) 2 C r 2 ( y - C O ) 3 ( 1 0 8 ) . However, r a t h e r t h a n a M—M s i n g l e bond, t h e s e t h r e e examples e a c h r e q u i r e a f o r m a l M=M t r i p l e bond t o s a t i s f y an e i g h t e e n e l e c t r o n c o u n t a b o u t e a c h t r a n s i t i o n m e t a l c e n t r e . - 145 -5.3.2 R e a c t i o n s o f [MeGa(pz)-,J_ 2 Rh 2 ( U ~ C Q ) 3_ [ M e G a ( p z ) 3 ] 2 R h 2 ( y - C O ) 3 r e m a i n e d u nchanged when s t i r r e d i n THF o r b e n z e n e o v e r n i g h t . However when t h i s r h o d i u m d i m e r was l e f t a t r e f l u x t e m p e r a t u r e s i n b e n z e n e f o r f i v e d a y s , t h e b r i d g i n g CO c h a r a c t e r was c o m p l e t e l y d e s t r o y e d and [ ( y - p z ) R h ( C O ) 2 ^ w a s i s o l a t e d i n low y i e l d . S i m i l a r l y s t i r r i n g [ M e G a ( p z ) ^ ] 2 R h 2 ( y C O ) ^ w i t h P P h 3 i n b e n z e n e o v e r n i g h t e f f e c t e d no change i n t h e s t a r t i n g m a t e r i a l s , b u t r e f l u x i n g t h e same r e a c t i o n m i x t u r e f o r 8 h p r o d u c e d >90% y i e l d o f t h e d i m e r [ ( y - p z ) R h ( C O ) ( P P h 3 ) ] 2 ' a compound t h a t c a n be q u a n t i t a t i v e l y p r e p a r e d by t h e a d d i t i o n o f P P h 3 t o [ ( y - p z ) R h ( C O ) 2 ] 2 ( 9 ) . T h i s b e h a v i o u r c a n be c o n t r a s t e d w i t h t h a t o f [ H B ( p z ) 3 ] 2 R h 2 ( C O ) 3 w h i c h d i d n o t r e a c t w i t h P P h 3 u n d e r r e f l u x c o n d i t i o n s i n ben-zene (99) . The a d d i t i o n o f d i h a l o g e n s t o [ M e G a ( p z ) 3 ] 2 R h 2 ( p - C O ) 3 r e -s u l t e d i n t h e d i s p l a c e m e n t o f CO, p r o d u c i n g t h e R h ( I I I ) o x i d a -t i o n p r o d u c t s [ M e G a ( p z ) 3 ] R h ( C O ) ( X ) 2 (X = Br o r I ) . These o r a n g e (X = Br) and b l a c k (X = I) s o l i d s were m o d e r a t e l y s o l u b l e i n b e n z e n e and n-hexane and v e r y s o l u b l e i n C H 2 C 1 2 . B o t h p r o d u c t s had s i n g l e vCO bands i n t h e i r IR s p e c t r a a t f r e q u e n c i e s much h i g h e r (~270 cm "*") t h a n t h e i r c a r b o n y l b r i d g e d p r e c u r s o r . T h e s e s i n g l e bands ( a t 2125 cm 1 and 2100 cm 1 i n C H 2 C 1 2 when X = B r and I r e s p e c t i v e l y ) a r e w i t h i n 5 cm 1 o f t h o s e f r e q u e n c i e s r e p o r t e d f o r t h e r e l a t e d b o r a t e s , [ R B ( p z ) 3 ] Rh(CO)(X) (R=H, X=I; R=pz, X=I o r Br) ( 9 9 ) . C o c i v e r a e t a l - 146 -have commented t h a t t h e s e c a r b o n y l s t r e t c h i n g f r e q u e n c i e s a r e 30-60 cm h i g h e r t h a n t h o s e r e p o r t e d i n t h e r e l a t e d c y c l o -p e n t a d i e n y l c o m p l e x e s ( n 5 - C 5 H 5 ) R h ( C O ) ( I ) 2 (109) and ( n 5 - C 5 M e 5 ) R h ( C O ) ( I ) 2 ( 1 1 0 ) . I t has a l r e a d y been s t a t e d t h a t t h e u n i -n e g a t i v e t r i d e n t a t e p y r a z o l y l g a l l a t e and p y r a z o l y l b o r a t e l i g a n d s a r e b e t t e r e l e c t r o n d o n a t i n g g r o u p s t h a n t h e c o r r e s p o n d i n g c y c l o p e n t a d i e n y l l i g a n d . T h e r e f o r e t h i s marked d i f f e r e n c e b e -tween vCO v a l u e s i n t h e R h ( I I I ) d i h a l o g e n c o m p l e x e s i s somewhat s u r p r i s i n g as i t i s t h e r e v e r s e o f t h e p r e d i c t e d t r e n d . The two c o m p l e x e s [ M e G a ( p z ) 3 ] R h ( C O ) ( X ) 2 (X = I o r Br) were i d e n t i f i e d s o l e l y by IR s p e c t r o s c o p y . "'"H nmr s p e c t r a o f t h e s e two compounds were 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 u n i d e n t i f i a b l e b r o a d p e a k s . I n t e r e s t i n g l y ''"H nmr s p e c t r a c o u l d a l s o n o t be o b t a i n e d f o r [ (pz) B (pz) 3 ] Rh (CO) (Br) 2 and a r e l a t e d i o d i n e s p e c i e s , t h i s b e i n g a t t r i b u t e d t o t h e p o s s i b l e p r e s e n c e o f p a r a m a g n e t i c i m p u r i t i e s ( 9 9 ) . E l e m e n t a l a n a l y s e s , a l t h o u g h c l o s e t o t h e e x p e c t e d v a l u e s , were n o t a c c u r a t e enough t o be c o n s i d e r e d as s u p p o r t i n g d a t a . A t t e m p t s a t p u r i f i c a t i o n o f t h e c o m p l e x e s were n o t s u c c e s s f u l . 5.3.3 [ M e 2 G a ( p z ) ( O C H 2 C H 2 N M e 2 ) ] R h ( C O ) n (n = 1 and 2) The r e a c t i o n o f t h e u n s y m m e t r i c t r i d e n t a t e l i g a n d [ M e 2 G a ( p z ) ( O C H 2 C H 2 N M e 2 ) ] " w i t h [ R h ( C O ) 2 C l ] 2 was v i e w e d w i t h c o n -s i d e r a b l e i n t e r e s t due t o t h e u n u s u a l p r o d u c t r e s u l t i n g f r o m t h e a d d i t i o n o f t h e s y m m e t r i c a n a l o g [MeGa(pz)^] t o t h e same c a r -b o n y l h a l i d e . I n c o n t r a s t t o t h e d i m e r i c s p e c i e s d i s c u s s e d - 147 -i n s e c t i o n 5.3.1, monomeric p r o d u c t s o n l y were o b s e r v e d i n -c o r p o r a t i n g t h e u n s y m m e t r i c m o n o ( 1 - p y r a z o l y l ) g a l l a t e l i g a n d . The IR s p e c t r u m o f [ R h ( C O ) 2 C l ] 2 i n THF c o n t a i n s two s t r o n g bands i n t h e t e r m i n a l CO r e g i o n a t 2068 and 1989 cm ( F i g . 50) . Upon t h e a d d i t i o n o f two m o l a r e q u i v a l e n t s o f N a + [ M e 2 G a ( p z ) (OCH 2CH 2NMe 2)] a t -7 8 ° , t h e s e bands i m m e d i a t e l y d i s a p p e a r and two new bands r e p l a c e them a t 2075 and 2015 cm ^. These bands have been a s s i g n e d t o a new r h o d i u m s p e c i e s i n w h i c h t h e l i g a n d i s m e r i d i o n a l l y c o o r d i n a t e d and two c a r b o n y l g r o u p s o c c u p y e q u a t o r i a l p o s i t i o n s i n a t r i g o n a l b i p y r a m i d a l a r r a n g e m e n t , i . e . ( A ) i n F i g . 50. F o l l o w i n g t h e r e m o v a l o f t h e s o l v e n t f r o m t h e f i l t e r e d r e a c t i o n s o l u t i o n , a brown s o l i d r e m a i n e d w h i c h was composed o f a m i x t u r e o f two c o m p l e x e s , i . e . [ M e 2 G a ( p z ) ( O C H 2 C H 2 N M e 2 ) ] R h ( C O ) 2 and [ M e 2 G a ( p z ) ( O C H 2 C H 2 N M e 2 ) ] R h ( C O ) ( @ i n F i g . 5 0 ) . The m o n o c a r b o n y l s p e c i e s had a s i n g l e , s t r o n g c a r b o n y l s t r e t c h i n g f r e q u e n c y a t 1945 cm 1 i n THF. B o t h ( A and ( B ) a p p e a r e d t o be s t a b l e i n t h e s o l i d s t a t e and i n s o l u t i o n when k e p t u n d e r N 2 . However when e i t h e r a THF o r a c y c l o h e x a n e s o l u t i o n o f t h e same m i x t u r e was l e f t i n t h e a i r o v e r n i g h t t h e s i n g l e b and a t t r i b u t e d t o t h e r h o d i u m m o n o c a r b o n y l c o m p l e t e l y d i s a p p e a r e d , l e a v i n g as t h e o n l y m e t a l c a r b o n y l s p e c i e s l e f t i n s o l u t i o n . Thus w h i l e ( B ) i s a i r s e n s i t i v e i n s o l u t i o n , ( A ) a p p e a r e d t o be a i r s t a b l e b o t h i n s o l u t i o n and i n t h e s o l i d s t a t e . However a t t e m p t s t o i s o l a t e an a n a l y t i c a l l y p u r e sample o f [ M e 2 G a ( p z ) ( O C H 2 C H 2 N M e 2 ) ] R h ( C O ) 2 were n o t s u c c e s s f u l - r e c r y -s t a l l i z a t i o n u n d e r N 2 r e p e a t e d l y gave a m i x t u r e o f ( A ) and ( B ) - 148 -[Me 2Ga(pz)(OCH 2CH 2Me 2)]" + 5[Rh(CO) 2 Cl] THF, -78 vCO: 2068,1989 2200 2000 1900 cm 1 N Rh N TO vCO: 2075, 2015 Warm t o Room T e m p e r a t u r e N E v a p o r a t e t o D r y n e s s Rh N Rh CO 2200 2000 1900 cm 1 2200 2000 1900 cm 1 F i g u r e 50 [ M e 2 G a ( p z ) ( O C H 2 C H 2 N M e 2 ) ] " and [ R h ( C O ) 2 C 1 ] 2 (Note: f o r c l a r i t y o n l y t h e d o n o r s i t e s o f t h e t r i d e n t a t e p y r a z o l y l g a l l a t e l i g a n d a r e shown) - 149 -w h i l e r e c r y s t a l l i z a t i o n i n t h e a i r r e s u l t e d i n d e c o m p o s i t i o n p r o d u c t s w h i c h c o u l d n o t be s e p a r a t e d . R e f l u x i n g an a c e t o n i t r i l e s o l u t i o n o f [ M e 2 G a ( p z ) ( O C H 2 C H 2 N M e 2 ) ] Rh(CO) (n = 1 and 2) f o r 12 h r e s u l t e d i n >85% c o n v e r s i o n n ( e s t i m a t e d f r o m r e l a t i v e IR i n t e n s i t i e s ) o f t h e d i c a r b o n y l i n t o t h e m o n o c a r b o n y l complex. Removal o f t h e s o l v e n t in vacuo y i e l d e d a d a r k brown s o l i d . The nmr s p e c t r a o f t h i s s p e c i e s i n e i t h e r C^Dg o r (CD ^ ^ C O ( F i g . 51) c o n t a i n e d one s t r o n g s i n g l e t i n t h e g a l l i u m m e t h y l r e g i o n i n agreement w i t h t h e s q u a r e p l a n a r r h o d i u m a r r a n g e m e n t d e p i c t e d f o r t h e m o n o c a r b o n y l compound i n F i g u r e 50. The mass s p e c t r u m o f [ M e 2 G a ( p z ) ( O C H 2 C H 2 N M e 2 ) ] R h ( C O ) d i s -p l a y e d a s i g n a l c o r r e s p o n d i n g t o t h e p a r e n t i o n , P + ( 2 8 . 4 % ) . I o n s i g n a l s a t t r i b u t a b l e t o P-Me + ( 1 0 0 . 0 % ) , P-CO + (5.5%) and P-Me-CO + (26.6%) were a l s o a s s i g n a b l e . P r e v i o u s t o t h i s work o n l y f a c i a l c o o r d i n a t i o n o f t h e un-s y m m e t r i c p y r a z o l y l g a l l a t e l i g a n d s had been o b s e r v e d i n m e t a l c a r b o n y l c o m p l e x e s c o n t a i n i n g t h e s e l i g a n d s . A l t h o u g h t h i s i s t h e most commonly o c c u r r i n g mode o f b o n d i n g , m e r i d i o n a l c o o r d i n a t i o n o f t h e t r i d e n t a t e p y r a z o l y l g a l l a t e l i g a n d s i s n o t unknown (35, 3 9 ) . I t has now been p r o p o s e d t h a t t h e p y r a z o l y l -g a l l a t e l i g a n d c o o r d i n a t e s m e r i d i o n a l l y i n [Me 2Ga(pz) (OCH 2CH 2NMe 2)]Rh(CO) - i n t h i s way a s q u a r e p l a n a r Rh(I) c e n t r e i s p r e s e r v e d . F o r t h e f i v e - c o o r d i n a t e r h o d i u m d i c a r b o n y l s p e c i e s a t l e a s t s i x d i f f e r e n t s t e r e o c h e m i c a l a r r a n g e m e n t s a r e p o s s i b l e - 151 -as shown be l o w [two a d d i t i o n a l a r r a n g e m e n t s a r i s e i f t h e d o n o r s i t e s o f t h e t r i d e n t a t e l i g a n d a r e i n t e r c h a n g e d i n s t r u c t u r e s (b) and ( e ) ] . On e x a m i n a t i o n o f t h e s e s t r u c t u r e s n o t a l l a r e e q u a l l y p r o b a b l e . 0 O (a) (b) (c) / I .NMe 2 O C - / — R h - — C O 1/ N (d) F i g u r e 52 (e) CO ( f ) S t e r e o c h e m i c a l a r r a n g e m e n t s f o r [ M e 2 G a ( p z ) ( O C H 2 C H 2 N M e 2 ) ] R h ( C O ) 2 . (Note: f o r c l a r i t y o n l y t h e d o n o r s i t e s o f t h e t r i d e n t a t e p y r a z o l y l g a l l a t e l i g a n d a r e shown) g I t i s known t h a t i n d s y s t e m s good i r - a c c e p t i n g l i g a n d s s u c h as CO p r e f e r t o o c c u p y t h e e q u a t o r i a l s i t e s i n t r i g o n a l b i p y r a m i d a l g e o m e t r i e s ( 1 1 1 ) . On t h i s b a s i s s t r u c t u r e (a) i s t h e most f a v o u r e d among t h e t r i g o n a l b i p y r a m i d a l p o s s i b i l i t i e s - 152 -shown i n F i g u r e 52. S u p p o r t i v 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 t h i s s t r u c t u r e comes f r o m t h e (CD^) 2 C 0 "*"H nmr s p e c t r u m f o r t h e b l a c k s o l i d c o n t a i n i n g b o t h [ M e 2 G a ( p z ) ( O C H 2 C H 2 N M e 2 ) ] R h ( C O ) (n = 1 and 2 ) . I n t h e g a l l i u m m e t h y l r e g i o n o f t h i s s p e c t r u m two s i n g l e t s were v i s i b l e a t T10.30 and T 9 . 8 9 . The h i g h e r f i e l d s i n g l e t has a l r e a d y b e en a t t r i b u t e d t o t h e m o n o c a r b o n y l complex, t h e r e f o r e t h e s i n g l e t a t x9.89 p r e s u m a b l y b e l o n g s t o t h e d i -c a r b o n y l s p e c i e s . A s t r u c t u r e as shown i n F i g u r e 52(a) w o u l d g i v e r i s e t o one s i n g l e t f o r t h e g a l l i u m m e t h y l s u b s t i t u e n t s . g F u r t h e r m o r e , i n s q u a r e p y r a m i d a l d s y s t e m s good d o n o r l i g a n d s p r e f e r t o o c c u p y t h e b a s a l p o s i t i o n s , w h i l e e l e c t r o n e g a t i v e g r o u p s p r e f e r t h e a p i c a l s i t e , i . e . ( f ) i n F i g u r e 52. However, w i t h a r i g i d m o l e c u l e , a "*"H nmr s p e c t r u m f o r a complex o f s t r u c t u r e ( f ) s h o u l d d i s p l a y two g a l l i u m m e t h y l s i n g l e t s . Un-f o r t u n a t e l y c r y s t a l s o f [ M e 2 G a ( p z ) ( O C H 2 C H 2 N M e 2 ) ] R h ( C O ) 2 c o u l d n o t be o b t a i n e d , t h e r e f o r e t h e s o l i d s t a t e g e o m e t r y c o u l d n o t be c o n f i r m e d . [ M e 2 G a ( p z ) ( O C H 2 C H 2 N M e 2 ) ] R h ( C O ) 2 i s r e l a t e d t o t h e c y c l o -p e n t a d i e n y l d e r i v a t i v e (n 5-C,-H,-)Rh(CO) 2 as b o t h a r e f o r m a l l y 18 e l e c t r o n Rh(I) d i c a r b o n y l s p e c i e s . I t has p r e v i o u s l y b e en s t a t e d t h a t ( n 5 - C ^ H ^ ) R h ( C O ) 2 i s an a i r s e n s i t i v e o r a n g e l i q u i d t h a t d i m e r i s e s t o f o r m (n 5-Cj-H,_) 2 R h 2 ( y - C O ) ( C O ) 2 upon e x p o s u r e t o a i r (94, 9 5 ) . I n a d d i t i o n r e f l u x i n g ( n 5 - C ^ H ^ ) R h ( C O ) 2 w i t h PPh i n hexane f o r 12 h r e s u l t e d i n an 80% y i e l d o f (n 5-C,-Hj-)Rh(CO) ( P P h 3 ) ( 1 1 2 ) . When P P h 0 was added t o a b l a c k s o l u t i o n o f - 153 -[ M e 2 G a ( p z ) ( O C H 2 C H 2 N M e 2 ) ] R h ( C O ) n (n = 1 and 2) i n THF a t - 7 8 ° , t h e r e a c t i o n s o l u t i o n l i g h t e n e d c o n s i d e r a b l y i n c o l o u r . T h i s s o l u t i o n was a l l o w e d t o warm g r a d u a l l y t o room t e m p e r a t u r e w i t h c o n t i n u a l s t i r r i n g . An IR s p e c t r u m o 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 r e s u l t i n g c o n t a i n e d o n l y one band i n t h e c a r b o n y l r e g i o n a t 1983 cm ^. Removal o f t h e THF in vacuo l e f t a y e l l o w s o l i d w h i c h a n a l y z e d c o r r e c t l y f o r [ ( y - p z ) Rh (CO) (PPh^)],,. Thus t h e f o l l o w i n g 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 had o c c u r r e d : THF [ M e 2 G a ( p z ) ( O C H 2 C H 2 N M e 2 ) ] R h ( C O ) n + P P h 3 — — • hi(y-pz)Rh(CO)(PPh3)]2 + h[Me2Ga(OCH2CH2NMe2)]2 + (n-1)CO The v o l a t i l e g a l l i u m d i m e r has b e en p r e v i o u s l y c h a r a c t e r i z e d (113) . A t t e m p t s t o p r e p a r e a n a l o g o u s c a r b o n y l and p h o s p h i n e com-p l e x e s t o t h o s e d e s c r i b e d i n t h i s s e c t i o n c o n t a i n i n g an. unsym-m e t r i c mono(3,5 d i m e t h y l p y r a z o l y l ) g a l l a t e l i g a n d { i . e . [ M e 2 G a ( p z " ) ( O C H 2 C H 2 N M e 2 ) ] " } were t h w a r t e d due t o t h e f a c i l e f o r m -a t i o n o f t h e s t a b l e d i m e r s [ ( y - p z " ) R h ( C O ) 2 ] 2 and [ ( y - p z " ) R h ( C O ) ( P P h 3 ) ] 2 . 5.3.4 [MeGa(pz),, ]MoRh(y-CO) 2 (CO) (PPh-, )_2 _ The f i r s t example o f a p y r a z o l y l g a l l a t e compound c o n t a i n i n g two d i f f e r e n t t r a n s i t i o n m e t a l s has been p r e p a r e d f r o m t h e - 154 -r e a c t i o n between R h ( P P h 3 ) 3 C l and [ M e G a ( p z ) 3 ] M o ( C O ) . The p r o d u c t , [ M e G a ( p z ) 3 ] M o R h ( y - C O ) 2 ( C O ) ( P P h 3 ) 2 , p r o v e d d i f f i c u l t t o i s o l a t e , c r y s t a l l i z i n g t o g e t h e r w i t h b i p r o d u c t s i n c l u d i n g t h e , y e l l o w r h o d i u m d i m e r , [ ( y - p z ) R h ( C O ) ( P P h 3 ) ] 2 « However c r y -s t a l s o f t h e d e s i r e d p r o d u c t c o u l d be h a n d p i c k e d f r o m t h e r e a c -t i o n r e s i d u e as t h e y f o r m e d d i s t i n c t d a r k r e d f l a k e s . An X - r a y c r y s t a l s t r u c t u r e o f t h e r e l a t e d c y c l o p e n t a d i e n y l compound ( n 5 - C ^ H ^ ) M o R h ( y - C O ) 2 ( C O ) ( P P h 3 ) 2 has a p p e a r e d r e c e n t l y i n t h e l i t e r a t u r e ( 1 1 4 ) . T h i s c r y s t a l s t r u c t u r e u n a m b i q u o u s l y shows t h e p r e s e n c e o f two b r i d g i n g c a r b o n y l g r o u p s l i n k i n g t h e Mo and Rh atoms and one t e r m i n a l CO l i g a n d c o o r d i n a t e d t o t h e Mo. I t was f e l t t h a t t h e s t e r i c b u l k o f t h e p y r a z o l y l g a l l a t e m o i e t y m i g h t a c t t o p u s h t h e l o n e t e r m i n a l c a r b o n y l g r o u p i n t o a b r i d g i n g p o s i t i o n , m a k i n g t h e t h r e e CO l i g a n d s e q u i v a l e n t . However t h i s was n o t f o u n d t o be t h e c a s e as t h e IR s p e c t r u m f o r t h i s c o m p l e x c o n t a i n e d two bands i n c l o s e a g r e e m e n t t o t h o s e r e p o r t e d f o r t h e c y c l o p e n t a d i e n y l a n a l o g (see s e c . 5 . 2 . 8 ) . Thus i t a p p e a r s t h a t t h e two compounds, L M o R h ( y - C O ) 2 ( C O ) ( P P h 3 ) 2 , {L = [ M e G a ( p z ) 3 ] ~ o r ( r i 5 - C ^ H ^ ) }, a r e s t r u c t u r a l i s o m e r s . I n t h e p a p e r d e s c r i b i n g t h e c y c l o p e n t a d i e n y l complex (114) i t has been m e n t i o n e d t h a t a s i n g l e M o — R h bond p l a c e s b o t h t h e Mo and Rh atoms i n 16 e l e c t r o n e n v i r o n m e n t s , an u n l i k e l y c o n -f i g u r a t i o n f o r M o ( I ) . An 18 e l e c t r o n c o n f i g u r a t i o n a b o u t b o t h m e t a l c e n t r e s c a n be o b t a i n e d i f a t r i p l e bond ( i . e . Mo=Rh) i s - 155 -invoked. However, t a k i n g i n t o c o n s i d e r a t i o n the Mo«**Rh s e p a r a t i o n of 2.588 (1) 7A and the tendency f o r rhodium to aq u i r e a 16 e l e c t r o n c o n f i g u r a t i o n , the bonding has been r a t i o n -a l i z e d as shown below. o [MeGa(pz)] or ( n 5 - C 5 H 5 ) F i g u r e 53. LMoRh(p-CO) 2(CO)(PPh 3) . In t h i s scheme a d a t i v e bond from Rh to Mo i s proposed, the rhodium atom a c t i n g as a Lewis base. I n t e r e s t i n g l y , although i n i t i a l s t u d i e s have shown the complex where L = (n 5-C 5H<.) to d i s p l a y some a c t i v i t y as a hy-drogenation c a t a l y s t , the p y r a z o l y l g a l l a t e analog was i n e f f e c t i v e i n c a t a l y z i n g the hydrogenation of al k e n e s . S t e r i c e f f e c t s are probably unimportant s i n c e any c a t a l y t i c a c t i v i t y most l i k e l y occurs a t the rhodium metal c e n t r e w e l l removed from L. Per-haps d i f f e r e n t e l e c t r o n i c e f f e c t s c r e a t e d by the ' t r i d e n t a t e ' l i g a n d s are the o v e r r i d i n g i n f l u e n c e on the c a t a l y t i c a c t i v i t y d i s p l a y e d by these complexes. - 156 -5 . 4 Summary [MeGa (pz) ^ ] (y-CO) ^  has been p r e p a r e d f r o m t h e r e a c t i o n o f [ M e G a ( p z ) 3 ] and [ R h ( C O ) 2 C 1 ] 2 • A l t h o u g h i t seems p r o b a b l e t h a t t h e s p e c i e s 1 [ MeGa (pz) ^ ] Rh (CO) 2 ' forms i n i t i a l l y i n t h i s r e a c t i o n , s u c h a monomer c o u l d n o t be d e t e c t e d u n d e r t h e r e a c t i o n c o n d i t i o n s e m p l o y e d . C o n s e q u e n t l y 1 [ M e G a ( p z ) ^ ] R h ( C 0 ) 2 ' a p p e a r s t o be h i g h l y s u s c e p t i b l e t o d i m e r i z a t i o n , t h e t r i p l y c a r b o n y l b r i d g e d r h o d i u m d i m e r f o r m i n g i n h i g h y i e l d . A l t h o u g h i t i s n o t o b v i o u s why r a p i d d i m e r i z a t i o n o f ' [ M e G a ( p z ) ^ ] R h ( C O ) 2 1 s h o u l d o c c u r , a p o s s i b l e m o t i v e c a n be p o s t u l a t e d b a s e d upon t h e o b s e r v e d b e h a v i o u r o f [Me2Ga(pz) ( O C H 2 C H 2 N M e 2 ) 1 R h ( C O ) n (n=l and 2 ) . I n t h e s e c o m p l e x e s t h e u n s y m m e t r i c p y r a z o l y l g a l l a t e t r i d e n t a t e l i g a n d c a n c o o r d i n a t e i n e i t h e r a m e r i d i o n a l o r f a c i a l manner. T h i s o p t i o n i s n o t a v a i l a b l e t o t h e [ M e G a ( p z ) 3 J a n i o n , g e o m e t r i c f a c t o r s l i m i t t h e s y m m e t r i c l i g a n d t o c o o r d i n a t i n g i n a f a c i a l a r r a n g e m e n t . I n t h i s c h a p t e r i t has been shown t h a t [Me2Ga(pz)(OCH2CH2NMe2)] R h ( C 0 ) 2 c a n be i n d u c e d t o d e c a r b o n y l a t e , f o r m i n g t h e monocar-b o n y l s p e c i e s , [ M e 2 G a ( p z ) ( O C H 2 C H 2 N M e 2 ) ] R h ( C O ) , a complex w h i c h s a t i s f i e s t h e p r e f e r e n c e s o f R h ( I ) t o r e s i d e i n a 1 6 - e l e c t r o n s q u a r e p l a n a r e n v i r o n m e n t ( 1 1 5 ) . I t i s e m p h a s i z e d t h a t t h i s c a n o c c u r o n l y b e c a u s e t h e u n s y m m e t r i c p y r a z o l y l g a l l a t e l i g a n d i s m e r i d i o n a l l y c o o r d i n a t e d i n t h e m o n o c a r b o n y l monomer. D e c a r b o n y l a t i o n o f t h e e l u s i v e 1 [ M e G a ( p z ) , ] R h ( C O ) 9 ' s p e c i e s - 157 -w o u l d a l s o r e s u l t i n a 1 6 - e l e c t r o n Rh(I) complex. However t h e f a c i a l l y c o o r d i n a t e d t r i d e n t a t e [ M e G a ( p z ) 3 ] l i g a n d w o u l d now h o l d t h e r h o d i u m atom i n a p s e u d o t e t r a h e d r a l a r r a n g e -ment, an uncommon g e o m e t r y f o r R h ( I ) ( 1 1 6 ) . I f d i m e r i z a t i o n immedi-a t e l y f o l l o w s t h e d e c a r b o n y l a t i o n o f one 1 [ M e G a ( p z ) 3 ] R h ( C O ) 2 1 , a b i o c t a h e d r a l m o l e c u l e r e s u l t s . As p r e v i o u s l y m e n t i o n e d , t h e s t e r i c b u l k o f t h e p y r a z o l y l g a l l a t e l i g a n d s most l i k e l y f o r c e t h e t h r e e c a r b o n y l g r o u p s i n t o b r i d g i n g p o s i t i o n s . The r e s u l t i n g s t a b l e d i m e r , [ M e G a ( p z ) 3 ] 2 R h 2 ( p - C O ) 3 has b e en s t r u c t u r a l l y c h a r a c t e r i z e d . [ M e G a ( p z ) ^ ] 2 R h 2 ( p - C O ) 3 r e a c t e d w i t h bromine and i o d i n e , forming the o x i d a t i v e a d d i t i o n p r o d u c t s , [MeGa(pz) 3]Rh (CO)(X) (X = Br or I ) . These Rh(III) compounds were c h a r a c t e r i z e d by IR spectroscopy and have been compared to the r e l a t e d pyrazo-l y l b o r a t e and c y c l o p e n t a d i e n y l analogs. The mixed t r a n s i t i o n metal complex [MeGa(pz) 3]MoRh (p -CO) ( C O ) ( P P h 3 ) 2 has been prepared and c h a r a c t e r i z e d . In t h i s molecule the s t e r i c bulk of the [MeGa(pz) 3] l i g a n d d i d not f o r c e a t r i p l y c a r b o n y l b r i d g e d arrangement, a c o n f i g u r a t i o n which would leave the molybdenum atom e l e c t r o n d e f i c i e n t . - 158 -CHAPTER V I CONCLUSION AND PERSPECTIVES Compared t o l i g a n d s s u c h as t h e w e l l s t u d i e d g - d i k e -t o n a t e and c y c l o p e n t a d i e n y l a n i o n s , t h e p y r a z o l y l g a l l a t e s y s t e m s may i n i t i a l l y a p p e a r t o be somewhat ' e x o t i c ' i n n a t u r e t o t h o s e u n f a m i l i a r w i t h them. However t h e y have b e e n f o u n d t o be v e r s a t i l e l i g a n d s p o s s e s s i n g e x c e l l e n t c h e l a t i n g a b i l i -t i e s . T h i s has been d e m o n s t r a t e d i n t h e p r e s e n t work by s t u d y i n g t h e c o o r d i n a t i o n b e h a v i o u r o f p y r a z o l y l g a l l a t e b i d e n -t a t e and t r i d e n t a t e l i g a n d s t o w a r d s r h e n i u m and r h o d i u m , and t o a l e s s e r e x t e n t , manganese. A number o f o c t a h e d r a l r h e n i u m c a r b o n y l c o m p l e x e s have been p r e p a r e d , c o n t a i n i n g a b i d e n t a t e p y r a z o l y l g a l l a t e l i g a n d c o o r -d i n a t e d i n a c i s c h e l a t i n g manner. The f i r s t e xamples o f compounds c o n t a i n i n g u n s y m m e t r i c m o n o ( 1 - p y r a z o l y l ) g a l l a t e b i d e n -t a t e l i g a n d s have been d i s c u s s e d i n s e c t i o n 2.3.3. The two d o n o r s i t e s o f t h e s e l i g a n d s c o n s i s t o f one p y r a z o l y l r i n g n i t r o g e n and e i t h e r o x y g e n o r p h o s p h o r u s . O t h e r d o n o r moie-t i e s s u c h as 'OR, SR o r P R ^ ( R = a l k y l o r a r y l group) c o u l d c o n -c e i v a b l y o c c u p y t h e n o n p y r a z o l y l b r i d g i n g p o s i t i o n and t h i s r e m a i n s an a r e a t o be f u r t h e r i n v e s t i g a t e d . The r e a c t i o n s between t r i d e n t a t e a n i o n i c p y r a z o l y l g a l l a t e l i g a n d s and e i t h e r [ R e ( C O ) , C l ] ~ o r Mn(CO) c ;Br e x c l u s i v e l y - 159 -y i e l d e d monomeric, f a c i a l l y c o o r d i n a t e d , t r i c a r b o n y l , o c t a h e -d r a l p r o d u c t s . I n t h e c a s e o f r h e n i u m t h e e a s e o f f o r m a t i o n and r e l a t i v e s t a b i l i t y o f t h e t r i c a r b o n y l p r o d u c t s s y n t h e s i z e d s u g g e s t s t h a t r h e n i u m i s a good m e t a l f o r t e s t i n g t h e c o o r d i -n a t i o n b e h a v i o u r o f new p y r a z o l y l g a l l a t e t r i d e n t a t e l i g a n d s . The r h e n i u m m e t a l c e n t r e s e r v e d t o s t a b i l i z e t h e p y r a z o l y l g a l -l a t e t r i c a r b o n y l c o m p l e x e s , t o s u c h an e x t e n t t h a t t h e ob-s e r v e d r e a c t i v i t y o f t h e s e compounds was l i m i t e d . The p r o d u c t s r e s u l t i n g f r o m t h e r e a c t i o n s between t h e p y r a z o l y l g a l l a t e l i g a n d s and v a r i o u s r h o d i u m ( I ) p r e c u r s o r s were l e s s p r e d i c t a b l e . T h i s was p a r t i a l l y a t t r i b u t a b l e t o t h e a b i -l i t y o f Rh(I) t o e x i s t i n e i t h e r a 16 o r 18 e l e c t r o n e n v i r o n -ment. U n f o r t u n a t e l y p r e l i m i n a r y i n v e s t i g a t i o n s c o n c e r n i n g t h e c a t a l y t i c b e h a v i o u r o f t h e n o v e l R h ( I ) p y r a z o l y l g a l l a t e com-p l e x e s p r e p a r e d y i e l d e d d i s a p p o i n t i n g r e s u l t s . T h i s a r e a i s c u r r e n t l y b e i n g s t u d i e d more t h o r o u g h l y i n o u r l a b o r a t o r y . I n a d d i t i o n t h e r e a c t i o n s o f p y r a z o l y l g a l l a t e l i g a n d s w i t h i r i d i u m a r e b e i n g i n v e s t i g a t e d and t h e p o s s i b i l i t y o f p y r a z o l y l g a l l a t e i r i d i u m c o m p l e x e s f u n c t i o n i n g as h y d r o g e n a -t i o n c a t a l y s t s i s b e i n g p r o b e d . I n i t i a l s t u d i e s i n d i c a t e t h a t t h e i r i d i u m compounds a r e more r e a c t i v e t h a n t h e i r r h o d i u m a n a l o g s . T h i s r e a c t i v i t y s u g g e s t s more p r o m i s i n g r e s u l t s f o r t h e c a t a l y t i c p o t e n t i a l o f s e l e c t e d p y r a z o l y l g a l l a t e i r i d i u m s p e c i e s . The r o l e o f t h e p y r a z o l y l r i n g i n t h e p y r a z o l y l g a l l a t e - 160 -l i g a n d s i s n o t f u l l y u n d e r s t o o d . I n i t i a l l y t h i s r i n g was c h o s e n b e c a u s e o f i t s o x i d a t i v e s t a b i l i t y and f a v o u r a b l e geo-m e t r y t o s e r v e as a b r i d g i n g g r o u p . However t h e e f f e c t s o f s u b s t i t u t i n g t h e p y r a z o l y l g r o u p f o r h y d r a z i n e , o r a h y d r a z i n e r e l a t e d m o i e t y , may be a n o t h e r a r e a w o r t h i n v e s t i g a t i n g . The s u b s t i t u t i o n o f t h e p y r a z o l y l r i n g f o r t h e r e l a t e d i m i d a z o l y l g r o u p c o u l d a l s o l e a d t o some i n t e r e s t i n g c o m p l e x e s . 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 t h e s p e c i e s [ ( p - E ) R h ( C O ) ] n has shown a t e t r a m e r i c m o l e c u l e ( i . e . n=4) when E i s t h e i m i d a z o l y l g r o u p ( 1 1 7 ) , i n c o n t r a s t t o t h e d i m e r f o r m e d ( i . e . n=2) when E i s t h e p y r a z o l y l r i n g . I t i s p o s -s i b l e t h a t i m i d a z o l y l g a l l a t e l i g a n d s c o u l d l e a d t o c o m p l e x e s w i t h t h e same f o r m u l a t i o n a s t h e i r p y r a z o l y l g a l l a t e a n a l o g s , however be o f l a r g e r r i n g s i z e . M o s t o f t h e p y r a z o l y l g a l l a t e l i g a n d s y s t e m s s t u d i e d t o d a t e c o n t a i n m e t h y l s u b s t i t u e n t s a t t a c h e d t o t h e g a l l i u m a t t h e p o s i t i o n s n o t i n v o l v e d i n c o o r d i n a t i o n t o t h e t r a n s i t i o n m e t a l . These m e t h y l g r o u p s a r e o f t e n u s e f u l , p a r t i c u l a r l y i n t h e i n -t e r p r e t a t i o n o f ^H nmr s p e c t r a . The c h e m i c a l s h i f t o f t h e 'GaMe' p r o t o n s o c c u r s a t r e l a t i v e l y h i g h f i e l d (~10x) and t h u s t h e g a l l i u m m e t h y l r e s o n a n c e s do n o t u s u a l l y c o m p l i c a t e o t h e r p r o t o n r e s o n a n c e s i g n a l s p r e s e n t . I n a d d i t i o n t h e g a l l i u m m e t h y l s i n g l e t s a r e o f t e n v a l u a b l e i n d i c a t o r s f o r d e t e r m i n i n g t h e p u r i t y o r s t r u c t u r e o f p y r a z o l y l g a l l a t e t r a n s i t i o n m e t a l com-p l e x e s . However t h e e f f e c t s o f i n c o r p o r a t i n g a l k y l o r a r y l - 161 -g r o u p s i n p l a c e o f t h e m e t h y l s u b s t i t u e n t s r e m a i n s an a r e a d e s e r v i n g f u r t h e r i n v e s t i g a t i o n . 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Chem. 224, 207 (1982). - 169 -APPENDICES APPENDIX Page I GAS UPTAKE APPARATUS 17 0 I I STEREO DIAGRAMS, BOND LENGTHS AND BOND ANGLES OF SOME OF THE PREPARED DERIVATIVES ... 173 [Me 2Ga(pz) 2 ] R e ( C O ) (PPh 3) 17 3 [MeGa (pz) 3 ] R e (CO) 3 176 [Me 2Ga (pz") (.OCH 2CH 2NMe 2) ]Re (CO) 178 [Me 2Ga(.pz") COCH 2CH 2SPh). ]ReCCO). 3 181 [Me„Ga(pz") (OCH C*HR-NH ) ]ReCCO) CR=Et). 18 3 [Me 2Ga (pzl 2]Rh(.COD) 18 5 [ tu-pz"lRh.CCO). 2] 2 > 187 [ Cy-pz"lRh(COD) 189 [Me 2Ga (pz " ) 2 ] Rh (CO) (PPh 3) 191 [ M e G a ( p z ) 3 R h ] 2 ( y - C O ) 3 193 I I I THEORETICAL INTENSITY PATTERNS FOR MASS SPECTROSCOPIC ANALYSIS 195 - 170 -APPENDIX I GAS UPTAKE APPARATUS Key P a r t s o f t h e A p p a r a t u s : ( F i g . 54) A 25 ml r o u n d b o t t o m f l a s k w i t h d i m p l e d s u r f a c e E P y r e x b u c k e t s u s p e n d e d on p y r e x hook 0 I n l e t t o H 2 ( N 2 , e t c . ) S C a p i l l a r y manometer - h a l f f i l l e d w i t h p o t a s s i u m h y d r o g e n p h t h l a t e T Hg r e s e v o i r and g r a d u a t e d arm (±.05 c c ) U Hg manometer W T h e r m o s t a t e d o i l b a t h X I n s u l a t e d H 2 0 b a t h Y M e c h a n i c a l s h a k e r F i g u r e 54. Gas u p t a k e a p p a r a t u s . - 172 -G e n e r a l P r o c e d u r e f o r M e a s u r i n g Gas U p t a k e : 1. P l a c e s o l v e n t and s u b s t r a t e i n f l a s k 1A' 2. P l a c e c a t a l y s t i n b u c k e t 'E' 3. C o n n e c t f l a s k and s p i r a l a t t a p ' F 1 t o 'Q' 4. W i t h 'K' c l o s e d d e g a s c o n t e n t s o f f l a s k by 1 f r e e z e - p u m p - t h a w ' c y c l e s u n t i l no b u b b l e s a r e v i s i b l e i n t h a w i n g s o l u t i o n (-10 c y c l e s ) 5. C l o s e 'N', open 'M' and 'F'. I n t r o d u c e H 2 t h r o u g h '0' t o -720 t o r r p r e s s u r e 6. C l o s e 'M' and " F 1 , d i s c o n n e c t s p i r a l , c o n n e c t t o ' R ' w i t h f l a s k now i n " b a t h 'W' 7. Open 'G, H, J , K and N 1 and e v a c u a t e s e c t i o n t o i p i 8. C l o s e 1 N 1 and a d m i t H 2 t h r o u g h 'O' t o -7 20 t o r r p r e s s u r e 9. Open 'F' and a d j u s t p r e s s u r e t o d e s i r e d l e v e l 10. C l o s e 'H, J and K'. T h r o u g h '0' r a i s e p r e s s u r e i n s e c t i o n r i g h t o f 1 K 1 t o ~900 t o r r 11. S t a r t s h a k e r and add c a t a l y s t by r o t a t i n g 'D' 12. Read Hg l e v e l i n l e f t s i d e o f 'T' and s t a r t t i m e r 13. I f r e a c j t a n t s t a k e up H 2 , l e f t s i d e o f S w i l l r i s e . A t a p p r o p r i a t e t i m e s open 'K' t o e q u a l i z e l e v e l s i n 'S'. Read Hg l e v e l i n l e f t arm o f 1 T ' . - 173 -APPENDIX I I STEREO DIAGRAMS, BOND LENGTHS AND BOND ANGLES OF.SOME OF THE PREPARED DERIVATIVES T M e 2 G a ( p z ) 2 l R e ( C O ) (PPh 3) cm - 174 -[ M e 2 G a ( p z ) 2 ] R e C C O ) 3 ( P P h 3 ) , c o n t ' d Bond lengths wi th est imated standard d e v i a t i o n s in parentheses Bond Length(A) Bond Length(A) Re - P 2 . 5 3 4 ( 2 ) C ( 6 ) - C ( 7 ) 1 . 3 6 1 ( 9 ) Re - N O ) 2 . 2 0 2 ( 5 ) C ( 7 ) - C ( 8 ) 1 . 3 6 3 ( 1 0 ) Re - N ( 3 ) 2 . 2 0 4 ( 5 ) C ( 9 ) - • C O O ) 1 . 3 5 3 ( 9 ) Re - C O ) 1 . 9 3 1 ( 7 ) C O O ) - C O D 1 . 3 6 9 0 1 ) Re - C ( 2 ) 1 . 9 0 7 ( 7 ) C ( 1 2 ] - C ( 1 3 ) 1 . 3 8 3 ( 1 0 ) Re - C ( 3 ) 1 . 9 0 9 ( 7 ) C ( 1 2 ) - C ( 1 7 ) 1 . 3 8 9 ( 9 ) Re' - P ' 2 . 5 4 1 ( 2 ) C ( 1 3 ] - C ( 1 4 ) 1 . 3 7 8 ( 1 0 ) Re" - N O ' ) 2 . 2 0 3 ( 5 ) C ( 1 4 ] - C ( 1 5 ) 1 . 3 5 6 ( 1 1 ) Re' - N ( 3 ' ) 2 . 1 9 3 ( 5 ) C ( 1 5 - C ( 1 6 ) 1 . 3 7 6 ( 1 1 ) Re' - C O ' ) 1 . 9 3 1 ( B ) C ( 1 6 - C ( 1 7 ) 1 . 3 9 3 ( 1 0 ) Re' - C ( 2 ' ) 1 . 9 0 9 ( 8 ) C(18 - C ( 1 9 ) 1 . 4 1 7 ( 9 ) Re' - C ( 3 * ) 1 . 9 2 7 ( 7 ) C ( 1 8 - C ( 2 3 ) 1 . 3 7 9 ( 9 ) Ga - N ( 2 ) 1 . 9 7 7 ( 6 ) C(19 - C ( 2 0 ) 1 . 3 7 1 ( 1 1 ) Ga - N ( 4 ) 1 . 9 8 2 ( 6 ) C ( 2 0 - C ( 2 1 ) 1 . 3 7 4 ( 1 2 ) Ga - C ( 4 ) 1 . 9 5 1 ( 7 ) C(21 - C ( 2 2 ) 1 . 3 6 1 ( 1 2 ) Ga - C ( 5 ) 1 . 9 6 1 ( 9 ) C ( 2 2 - C ( 2 3 ) 1 . 4 1 1 ( 1 1 ) Ga' - N ( 2 ' ) 1 . 9 8 9 ( 5 ) C ( 2 4 - C ( 2 5 ) 1 . 3 8 2 ( 9 ) Ga' - N ( 4 ' ) 1 . 9 8 7 ( 6 ) C ( 2 4 - C ( 2 9 ) 1 . 4 0 2 ( 9 ) Ga' - C ( 4 ' ) 1 . 9 6 3 ( 7 ) C ( 2 5 - C ( 2 6 ) 1 . 3 7 0 ( 1 0 ) Ga' - C ( 5 ' ) 1 . 9 5 8 ( 7 ) C ( 2 6 - C ( 2 7 ) 1 . 3 9 7 ( 1 1 ) P - C ( 1 2 ) 1 . 8 2 9 ( 7 ) C ( 2 7 - C ( 2 8 ) 1 . 3 7 9 ( 1 1 ) P - C O B ) 1 . 8 2 5 ( 7 ) C ( 2 8 - C ( 2 9 ) 1 . 3 8 6 0 0 ) P - C ( 2 4 ) 1 . 8 2 5 ( 6 ) C ( 6 ' - C ( 7 ' ) 1 .389(9) P* - C ( 1 2 ' ) 1 . 8 3 0 ( 6 ) C ( 7 ' - C ( 8 ' ) 1 . 3 B 5 ( 1 1 ) P ' - C O B ' ) 1 . 8 1 2 ( 7 ) C ( 9 ' - C O O ' ) 1 . 3 6 4 ( 1 0 ) P ' - C ( 2 4 ' ) 1 . 8 4 6 ( 6 ) C O O ) - C O 1' ) 1 . 3 6 3 ( 1 1 ) 0 ( 1 I - C O ) 1 . 1 4 8 ( 8 ) C( 12 ) - C 0 3 ' ) 1 .374(9) 0 ( 2 l - C ( 2 ) 1 . 1 5 5 ( 8 ) C(12 ) - C ( l 7 ' ) 1 .389(9) 0 ( 3 >-C(3) 1 . 1 5 4 ( 8 ) C(13 ) - C ( 1 4 ' ) 1 .392(10) 0 ( 1 ) - C O ' ) 1 . 1 4 5 ( 8 ) C ( 1 4 ) - C 0 5 ' ) 1 . 3 7 8 ( 1 1 ) 0 ( 2 ) - C ( 2 ' ) 1 . 1 5 6 ( 8 ) C ( 1 5 ) - C ( l 6 ' ) 1 . 3 5 0 ( 1 1 ) 0 ( 3 ) - C ( 3 ' ) 1 . 1 4 4 ( B ) C ( 1 6 ) - C ( 1 7 ' ) ' 1 . 3 8 5 ( 1 0 ) N O >-N(2) 1 . 3 6 4 ( 7 ) C O B ) - C 0 9 ' ) 1 . 3 7 8 ( 9 ) N O >-C(6) 1 . 3 3 2 ( 9 ) C O B ) - C ( 2 3 ' ) 1 . 3 8 5 0 0 ) N ( 2 - C ( 8 ) 1 . 3 5 6 ( 9 ) C(19 ) - C ( 2 0 ' ) 1 . 3 8 0 ( 1 3 ) N ( 3 l - N ( 4 ) 1 . 3 5 1 ( 7 ) C ( 2 0 ) - C ( 2 1 ' ) 1 . 3 7 1 ( 1 4 ) N ( 3 • - C O ) 1 . 3 4 1 ( 9 ) C(21 ) - C ( 2 2 ' ) 1 . 3 6 2 ( 1 4 ) N U • - C ( I I ) 1 . 3 5 4 ( 9 ) C ( 2 2 ) - C ( 2 3 ' ) 1 . 3 7 7 ( 1 2 ) N O ) - N ( 2 * ) 1 . 3 5 9 ( 7 ) C ( 2 4 ) - C ( 2 5 ' ) 1 . 3 9 0 ( 9 ) N O ) - C ( 6 ' ) 1 . 3 4 4 ( 9 ) C ( 2 4 ) - C ( 2 9 ' ) 1 . 3 7 6 ( 1 0 ) N ( 2 ) - C ( B ' ) 1 . 3 2 5 ( 9 ) C ( 2 5 ) - C ( 2 6 ' ) 1 . 3 8 2 ( 1 0 ) N ( 3 ) - N ( 4 ' ) 1 . 3 5 7 ( 7 ) . C ( 2 6 ) - C ( 2 7 ' ) 1 . 3 8 5 ( 1 3 ) N ( 3 ) - C ( 9 ' ) 1 . 3 3 3 ( 9 ) C ( 2 7 ) - C ( 2 8 ' ) 1 . 3 2 4 ( 1 2 ) N U ) - c o r ) 1 . 3 5 5 ( 9 ) C ( 2 8 ) - C ( 2 9 ' ) 1 . 3 7 9 ( 1 1 ) Bond ang les (deg) with es t imated standard d e v i a t i o n s in parentheses Bonds Angle(deg) Bond6 Angle(deg) p -Re - N O ) 8 7 . 8 1 ( 1 4 ) Re' - N ( 3 ' ) - N ( 4 ' ) 1 2 6 . 6 ( 4 ) p -Re - N ( 3 ) 8 9 . 1 6 ( 1 5 ) Re' - N ( 3 ' ) - C ( 9 ' ) 1 2 6 . 1 ( 4 ) p -Re - C O ) 1 7 8 . 1 ( 2 ) N ( 4 ' ) - N ( 3 ' ) - C ( 9 ' ) 1 0 6 . 8 ( 5 ) p -Re - C ( 2 ) 9 3 . 0 ( 2 ) Ga ' - N ( 4 ' ) - N ( 3 ' ) . 1 2 5 . 9 ( 4 ) p -Re - C ( 3 ) 9 3 . 9 ( 2 ) Ga' - N ( 4 ' ) - C ( 1 1 ' ) 1 2 3 . 4 ( 5 ) N O ) -Re - N ( 3 ) 9 1 . 6 ( 2 ) N ( 3 ' ) - N ( 4 ' ) - C ( 1 1 ' ) 1 0 8 . 7 ( 6 ) N O ) -Re - C O ) 9 3 . 2 ( 2 ) Re - C ( I ) - O O ) 1 7 5 . 3 ( 6 ) cont inued / . . . - 175 -lMe 2 GaCpz ) . 2 ]Re (C0 ) 3 ( PPh 3 ) , c o n t ' d Bonds Angle(deg) Bonds Angle(deg) N ( 1 ) - R e - C ( 2 ) 178.61 2) Re - C ( 2 ) - 0 ( 2 ) 1 7 5 . 1 ( 6) N ( 1 ) - R e - C ( 3 ) 8 9 . 9 1 2) Re - C ( 3 ) - 0 ( 3 ) 1 7 8 . 0 ( 6) N ( 3 ) - R e - C ( 1 ) 8 9 . 2 1 2) N ( 1 ) - C ( 6 ) - C ( 7 ) 1 1 1 , 3 ( 6) K ( 3 ) - R e - C ( 2 ) 89 .51 2) . C ( 6 ) - C ( 7 ) - C ( 8 ) 104.81 6) N ( 3 ) - R e - C ( 3 ) 176.6< 2) N ( 2 ) - C ( 8 ) - C ( 7 ) 109.51 6) C ( 1 ) - R e - C ( 2 ) 8 6 . 0 ( 3) N ( 3 ) - C ( 9 ) - C ( 1 0 ) 111.1 < 6) C ( 1 ) - R e - C ( 3 ) 87.7< 3) C ( 9 ) - C ( 1 0 ) - C ( 1 1 ) 1 0 4 . B ( 7) C ( 2 ) - R e - C ( 3 ) 8 6 . 8 1 3) N ( 4 ) - C ( 1 1 ) - C ( 1 0 ) 1 0 9 . 3 ( 6) P ' - R e ' -H ( l ' ) 8 7 . 7 6 ( 1 4 ) P - C ( 1 2 ) - C ( 1 3 ) 120.61 5) P ' - R e " - N ( 3 ' ) 8 4 . 4 6 ( 1 4 ) P - C ( 1 2 ) - C ( 1 7 ) 122.01 5) P ' - R e ' - C ( 1 ' ) • 1 7 9 . 5 ( 2) C ( 1 3 ) - C ( 1 2 ) - C ( 1 7 ) 117.21 6) P ' - R e ' - C ( 2 ' ) 95.9< 2) C ( 1 2 ) - C ( 1 3 ) - C ( 1 4 ) 121.81 7) P ' - R e ' - C ( 3 ' ) 93 .31 2) C ( 1 3 ) - C ( 1 4 ) - C ( 1 5 ) 1 2 0 . 9 8) N( 1 ' ) - R e ' - N ( 3 ' ) 91 .3 2) C ( 1 4 ) - C ( 1 5 ) - C ( 1 6 ) 118.8 7) N O ' ) - R e ' - C ( l ' ) 9 2 . 5 2) C ( 1 5 ) - C ( 1 6 ) - C ( 1 7 ) 1 2 0 . 9 7) N ( 1 ' ) - R e " - C ( 2 " ) 1 7 5 . 4 2) C ( 1 2 ) - C ( 1 7 ) - C ( 1 6 ) 1 2 0 . 3 7) N ( i ' ) - R e ' - C ( 3 ' ) 8 6 . 9 2) P - C ( 1 8 ) - C ( 1 9 ) 1 1 8 . 3 5 N ( 3 * ) - R e ' - C ( 1 ' ) 9 5 . 0 2) P - C ( 1 8 ) - C ( 2 3 ) 1 2 3 . 2 5 N ( 3 ' ) - R e ' - C ( 2 ' ) 91 . 9 3) C ( 1 9 ) - C ( 1 8 ) - C ( 2 3 ) 1 1 8 . 3 7] N ( 3 " ) - R e ' - C ( 3 ' ) 1 7 7 . 2 2) C ( 1 8 ) - C ( 1 9 ) - C ( 2 0 ) 121 . 3 7 C ( l ' ) - R e ' - C ( 2 ' ) 8 3 . 9 3) C ( 1 9 ) - C ( 2 0 ) - C ( 2 1 ) 1 1 9 . 2 8 C ( 1 ' ) - R e ' - C ( 3 ' ) 8 7 . 2 3) C ( 2 0 ) - C ( 2 1 ) - C ( 2 2 ) 1 2 1 . 3 8 C ( 2 ' ) - R e ' - C ( 3 ' ) 9 0 . 0 3) C ( 2 1 ) - C ( 2 2 ) - C ( 2 3 ) 120 .1 8 N ( 2 ) - G a -N (4) 9 6 . 0 2) C ( 1 8 ) - C ( 2 3 ) - C ( 2 2 ) 1 1 9 . 7 (7 N ( 2 ) - G a - C ( 4 ) 1 0 7 . 3 3) P - C ( 2 4 ) - C ( 2 5 ) 1 1 8 . 2 5 N ( 2 ) - G a - C ( 5 ) 1 0 9 . 3 3) P - C ( 2 4 ) - C ( 2 9 ) 1 2 3 . 2 [5 N ( 4 ) - G a - C ( 4 ) 1 0 5 . 4 3) C ( 2 5 ) - C ( 2 4 ) - C ( 2 9 ) 1 1 8 . 5 [6 N ( 4 ) - G a - C ( 5 ) 1 1 2 . 9 3) C ( 2 4 ) - C ( 2 5 ) - C ( 2 6 ) 121 .1 (7 C ( 4 ) - G a - C ( 5 ) 1 2 1 . 4 4) C ( 2 5 ) - C ( 2 6 ) - C ( 2 7 ) 1 2 0 . 4 (7 N ( 2 ' ) - G a ' - N ( 4 ' ) 9 6 . 7 2) C ( 2 6 ) - C ( 2 7 ) - C ( 2 8 ) 1 1 9 . 3 (7 N ( 2 ' ) - G a ' - C ( 4 ' ) 1 0 6 . 8 3) C ( 2 7 ) - C ( 2 8 ) - C ( 2 9 ) 120 .1 (8 N ( 2 ' ) - G a * - C ( 5 ' ) 115.1 3) C ( 2 4 ) - C ( 2 9 ) - C ( 2 B ) 1 2 0 . 6 (7 N ( 4 ' ) - G a ' - C ( 4 ' ) 1 0 7 . 3 3) Re" - C ( l ' ) - O d ' ) 1 7 4 . 5 (6 N ( 4 ' ) - G a ' - C ( 5 ' ) 1 0 7 . 3 3) R e ' - C ( 2 ' ) - 0 ( 2 * ) 1 7 5 . 3 (6 C ( 4 ' ) - G a ' - C ( 5 ' ) 1 2 0 . 6 3) R e ' - C ( 3 ' ) - 0 ( 3 ' ) 1 7 8 . 4 (6 Re - P - C ( 1 2 ) 117.21 2) N(1* ) - C ( 6 ' ) - C ( 7 ' ) 1 1 0 . 8 (7 Re - P - C ( 1 8 ) 1 1 2 . 8 2) C ( 6 ' ) - C ( 7 ' ) - C ( 8 ' ) 1 0 3 . 3 (7 Re - P - C ( 2 4 ) 1 1 2 . 8 (2) N ( 2 ' ) - C ( 8 ' ) - C ( 7 ' ) 1 1 0 . 3 (6 C ( 1 2 ) - P - C ( 1 B ) 1 0 4 . 3 (3) N ( 3 ' ) - C ( 9 ' ) - C ( 1 0 ' ) 1 1 0 . 5 (7 C ( 1 2 ) - P - C ( 2 4 ) 1 0 4 . 0 (3) C ( 9 ' ) - C ( 1 0 ' ) - C ( 1 1 ' ) 1 0 5 . 8 (7 C ( 1 8 ) - P - C ( 2 4 ) 1 0 4 . 3 (3) N ( 4 ' ) - C ( 1 1 ' ) - C ( l 0 ' ) 1 0 8 . 2 (7 R e ' - P * - C ( 1 2 ' ) 1 1 9 . 6 (2) P ' - C ( 1 2 ' ) - C ( 1 3 ' ) 1 2 3 . 7 (5 R e ' - P * - C ( 1 B ' ) 1 1 3 . 5 (2) P ' - C ( 1 2 ' ) - C ( 1 7 ' ) 119.4 (5 Re* - P ' - C ( 2 4 ' ) 1 1 4 . 7 (2) C ( 1 3 ' ) - C ( 1 2 ' ) - C ( 1 7 ' ) 1 1 6 . 8 (6 C ( 1 2 ' ) - P ' - C ( 1 8 ' ) 9 9 . 3 (3) C ( 1 2 ' ) - C ( 1 3 ' ) - C ( 1 4 ' ) 1 2 2 . 4 (7 C ( 1 2 ' ) - P ' - C ( 2 4 ' ) 1 0 2 . 7 (3) C ( 1 3 ' ) - C ( 1 4 ' ) ~ C ( 1 5 ' ) 1 1 9 . 0 (7 C ( 1 8 ' ) - P ' - C ( 2 4 ' ) 1 0 4 . 9 (3) C ( 1 4 ' ) - C ( 1 5 " ) - C ( 1 6 ' ) 1 1 9 . 8 [7 Re -N (1) -N (2) 1 2 6 . 7 (4) C ( 1 5 ' ) - C d 6 ' ) - C ( 1 7 ' ) 1 2 1 . 0 (8 Re -N (1) - C ( 6 ) 1 2 6 . 5 (4) C ( 1 2 ' ) - C ( 1 7 ' ) - C ( 1 6 ' ) 1 2 1 . 0 (7 N ( 2 ) - N ( 1 ) - C ( 6 ) 1 0 6 . 7 (5) P" - C ( 1 8 ' ) - C ( l 9 ' ) 1 2 3 . 5 (6 Ga -N(2 ) -N(1) 1 2 8 . 6 (4) P ' - C ( 1 8 ' ) - C ( 2 3 ' ) 1 1 8 . 7 (5 Ga -N (2) - C ( 8 ) 123 .1 (5) C ( 1 9 " ) - C ( l 8 ' ) - C ( 2 3 " ) 1 1 7 . 8 (7 N ( 1)-N ( 2 ) - C ( 8 ) 1 0 7 . 7 (5) C ( 1 8 ' ) - C ( l 9 ' ) - C ( 2 0 ' ) 1 2 0 . 8 (8 Re -N (3) -N (4) 1 2 6 . 6 14) C ( 1 9 ' ) - C ( 2 0 ' ) - C ( 2 1 ' ) 1 1 9 . 2 (9 Re -N (3) - C O ) 1 2 6 . 2 (4) C ( 2 0 " ) - C ( 2 1 ' ) - C ( 2 2 ' ) 1 2 1 . 8 (9 N ( 4 ) - N ( 3 ) - C ( 9 ) 1 0 6 . 9 (5) C ( 2 1 ' ) - C ( 2 2 ' ) - C ( 2 3 ' ) 1 1 7 . 9 (9 Ga -N (4) -N (3) 1 2 9 . 6 (4) C ( 1 8 ' ) - C ( 2 3 ' ) - C ( 2 2 ' ) 1 2 2 . 4 (8 Ga -N (4) - C ( 1 1 ) 1 2 2 . 5 (5) P ' - C ( 2 4 ' ) - C ( 2 5 ' ) 119.2 [5 N ( 3)-N ( 4 ) - C < 1 1 ) 1 0 7 . 9 (6) P' - C ( 2 4 ' ) - C ( 2 9 ' ) 1 2 2 . 0 (5 R e ' -N ( 1 ' )-N ( 2 ' ) 1 2 7 . 9 (4) C ( 2 5 ' ) - C ( 2 4 ' ) - C ( 2 9 " ) 1 1 8 . B [6 R e ' - N ( 1 ' ) - C ( 6 ' ) 125„5 [4) C ( 2 4 ' ) - C ( 2 5 ' ) - C ( 2 6 ' ) 120 .1 (8 N ( 2 ' ) - N ( 1 * ) - C ( 6 ' ) 1 0 6 . 6 5) C ( 2 5 ' ) - C ( 2 6 ' ) - C ( 2 7 * ) 1 2 0 . 0 8 <5a' -N ( 2 ' )-N(1«) 1 2 6 . 4 [4) C ( 2 6 ' ) - C ( 2 7 ' ) - C ( 2 8 ' ) 1 1 B . 8 (8 G a ' TN ( 2 ' ) - C ( 8 ' ) 1 2 4 . 5 (5) C ( 2 7 ' ) - C ( 2 B ' ) - C ( 2 9 ' ) 123.1 (8 N ( l ' ) - N ( 2 ' ) - C ( 8 ' ) 109 .1 (6) C ( 2 4 * ) - C ( 2 9 ' ) - C ( 2 8 ' ) 119 .1 [7 - 176 -[MeGa(pz ) 3 ]Re (CO) 3 Bond lengths (A) w i t h estimated standard d e v i a t i o n s i n parentheses Bond Length(A) Bond Length(A) Re -N(2) 2 .17002) NO )-C(5) 1 .33(2) Re -N(4) 2 .157(15) N(2)-C(7) 1 .35(2) Re -N(6) 2 .169(15) N(3)-N(4) 1 .37(2) Re -CO ) 1 .92(2) N(3)-C(8) 1 .36(2) Re -C(2) 1 .93(2) N(4)-C(10) 1 .32(2) Re -C(3) 1 .96(2) N(5)-N(6) 1 .37(2) Ga -NO ) 1 .936(15) N(5)-C(11) 1 .39(2) Ga -N(3) 1 .95(2) N(6)-C(13) 1 .32(2) Ga -N(5) 1 .91(2) C(5)-C(6) 1 .36(3) Ga -C(4) 1 .95(2) C(6)-C(7) 1 .36(3) 0( 1 ) -CO) 1 .16(2) C(8)-C(9) 1 .34(3) 0(2) -C(2) 1 .15(3) C(9)-C(10) 1 .35(3) 0(3) -C(3) 1 .11(2) CO 1 )-C(12) 1 .45(4) NO) -N(2) 1 .37(2) C(12)-C(13) 1 .31(3) - 177 -[MeGa(pz) 3 ]Re(CO) , c o n t ' d Bond angles (deg) with estimated standard d e v i a t i o n s i n parentheses Bonds Angle(deg) Bonds Angle(deg) N(2) -Re -N(4) 87. 1 (5) NO) -N(2 -C(7) 105.7(14) N(2) -Re -N(6) 89. 3(5) Ga -N(3 -N(4) 120.602) N(2) -Re -CO) 177. 4(7) Ga -N(3 -C(8) 130.005) N(2) -Re -C(2) 92. 6(7) N(4) -N(3 -C(8) 109(2) N(2) -Re -C(3) 92. 9(7) Re -N(4 -N(3) 124.5(12) N(4) -Re -N(6) 88.3(6) Re -N(4 -COO) 132.2(13) N(4) -Re -CO) 90. 4(7) N(3) -N(4 -COO) 103(2) N(4) -Re -C(2) 178. 3(8) Ga -N(5 -N(6) 123.2(12) N(4) -Re -C(3) 93. 0(7) Ga -N(5 - C O D 129.1(14) N(6) -Re -CO) 89. 8(8) N(6) -N(5 - C O D 108(2) N(6) -Re -C(2) 90. 0(8) Re -N(6 -N(5) 122.6(11) N(6) -Re -C(3) 177. 6(7) Re -N(6 -C(13) 129.6(15) CO ) -Re -C(2) 89. 8(9) N(5) -N(6 -CO 3) 108(2) CO ) -Re -C(3) 88. 1(10) Re -CO -0(1) 174(2) C(2) -Re -C(3) 88. 7(10) Re -C(2 -0(2) 176(2) NO) -Ga -N(3) 98. 1 (6) Re -C(3 -0(3) 177(2) NO ) -Ga -N(5) 98. 2(7) NO ) -C(5 -C(6) 112(2) NO) -Ga -C(4) 122. 5(9) C(5) -C(6 -C(7) 102(2) N(3) -Ga -N(5) 99. 0(7) N(2) -C(7 -C(6) 112(2) N(3) -Ga -C(4) 118. 4(8) N(3) -C(8 -C(9) 108(2) N(5) -Ga -C(4) 116. 1(10) C(8) -C(9 -COO) 104.4(15) Ga -NO) -N(2) 119. 4(11) N(4) -C(10)-C(9) 114(2) Ga -NO) -C(5) 132. 8(13) N(5) -CO )-C(12) 106(2) N(2) -NO) -C(5) 107. 8(15) C( 1 1 )-C( 2)-C(13) 104(2) Re -N(2) -NO) 126. 0(10) N(6) -C(13)-C(12) 114(2) Re -N(2) -cm 128. 3(12) I n t r a - a n n u l a r t o r s i o n angles (deg) standard d e v i a t i o n s i n parentheses Atoms Value(deg) N(4) -Re -N(2 -NO) 47.5(13) Ga -NO) -N(2 -Re -3(2) N(3) -Ga -NO -N(2) -48.7(13) NO) -Ga -N(3 -N(4) 52.0(11) Ga -N(3) -N(4 -Re -1.6(15) N(2) -Re -N(4 -N(3) -43.7(1 1) N(6) -Re -N(2 -NO ) -40.8(14) Ga -NO) -N(2 -Re -3(2) N(5) -Ga -N( 1 -N(2) 51 .7(13) NO) -Ga -N(5 -N(6) -53(2) Ga -N(5) -N(6 -Re 4(2) N(2) -Re -N(6 -N(5) 39.9(15) N(6) -Re -N(3 -N(4) -131.9(12) Re -N(3) -N(4 -Ga 1.6(15) N(5) -Ga -N(4 -N(3) 132.6(12) N(4) -Ga -N(5 -N(6) 28.7(15) Ga -N(5) -N(6 -Re 4(2) N(3) -Re -N(6 -N(5) -31.8(14) - 178 -[ M e 2 G a ( p z " ) ( O C H 2 C H 2 N M e 2 ) ] R e ( C O ) Bond l e n g t h s (A) with estimated standard d e v i a t i o n s i n parentheses Bond Length(A) Bond Length(A) Re -0(4) 2 . 158(9) 0(4)-C(9) 1 .44(2) Re -N(2) 2 .179(7) NO )-N(2) 1 .339(11) Re -N(3) 2 .254(11) NO )-C(6) 1 .375(13) Re -C(1 ) 1 .864(14) N(2)-C(8) 1 .374(14) Re -C(2) 1 .88002) N(3)-C(10) 1 .58(3) Re -C(3) 1 .860(13) C(6)-C(7) 1 .39(2) Ga -0(4) 1 .921(8) C(6)-C(13) 1 .54(2) Ga -NO) 1 .989(9) C(7)-C(8) 1 .37(2) Ga -C(4) 2 .00(2) C(8)-C(14) 1 .53(2) Ga -C(5) 1 .970(14) C(9)-C(10) 1 .48(3) 0(1 ) -CO ) 1 .15(2) CO0)-C( 1 1 ) 1 .72(4) 0(2) -C(2) 1 .17(2) C( 1 1 )-C(12) 1 .17(6) 0(3) -C(3) 1 .188(15) - 179 -[ M e 2 G a ( p z " ) ( O C H 2 C H 2 N M e 2 ) ] R e ( C O ) 3 , c o n t ' d Bond angles (deg) w i t h estimated standard d e v i a t i o n s i n parentheses Bonds Angle(deg) Bonds Angle(deg) 0(4) -Re -N(2) 82.1(3) Ga -0(4)-C(9) 119.5(9) 0(4) -Re -N(3) 77.3(4) Ga -N(1)-N(2) 120.5(6) 0(4) -Re -co) 174.0(6) Ga -N(1)-C(6) 130.1(8) 0(4 -Re -C(2) 92.0(6) N(2)-N(1)-C(6) 109.4(9) 0(4 -Re -C(3) 98.8(5) Re -N(2)-N(1) 120.1(6) N(2 -Re -N(3) 82.8(3) Re -N(2)-C(8) 132.6(7) N(2 -Re -CO ) 96.6(6) NO )-N(2)-C(8) 107.1(8) N(2 -Re -C(2) 173.0(7) Re -N(3)-C(10) 110.2(10) N(2 -Re -C(3) • 95.3(5) Re -CO)-0(1) 172(2) N(3 -Re -CO) 96.8(7) Re -C(2)-0(2) 174(2) N(3 -Re -C(2) 92.2(7) Re -C(3)-0(3) 173.8(14) N(3 -Re -C(3) 175.8(6) NO )-C(6)-C(7) 108.1(10) C(1 -Re -C(2) 88.9(8) NO )-C(6)-C(13) 122.5(12) C(1 >-Re -C(3) 87.1(7) C(7)-C(6)-C(13) 1 2 9 . 3 ( 1 1 ) C(2 -Re -C(3) 89.3(8) C(6)-C(7)-C(B) 105.4(10) 0(4 -Ga -N( 1 ) 89.6(3) N(2)-C(8)-C(7) 1 1 0 . 1 ( 1 1 ) 0(4 )-Ga -C(4) 108.5(5) N(2)-C(8)-C(14) 122.000) 0(4 )-Ga -C(5) 106.9(5) C(7)-C(8)-C(14) 128.0(12) NO )-Ga -C(4) 112.6(6) 0(4)-C(9)-COO) 111.3(14) NO )-Ga -C(5) 109.6(5) N(3)-C(10)-C(9) 105(2) C(4 )-Ga -C(5) 124.0(7) N(3)-CO0)-C(1 1 ) 110(2) Re -0(4) -Ga 115.8(4) C(9)-C(10)-C(11) 102(2) Re -0(4) -C(9) 109.8(10) CO0)-CO 1 )-C(12) 96(3) - 180 -[ M e 2 G a ( p z " ) ( O C H 2 C H 2 N M e 2 ) ] R e ( C O ) 3 , c o n t ' d I n t r a - a n n u l a r t o r s i o n angles (deg) standard d e v i a t i o n s i n parentheses Atoms Value(deg) NO) -Re -0(4)-Ga -31 .5(3) N(2) -Ga -0(4)-Re 34 .5(3) 0(4) -Ga -N(2)-N(1) -24 .0(6) Re -NO ) -N(2)-Ga 4 .8(8) 0(4) -Re -N(1)-N(2) 15 .3(5) N(3) -Re -0(4)-C(9) 19 .7(6) Re -0(4) -C(9)-C(10) -46 .9(9) 0(4) -C(9) -C(10)-N(3) 58 .5(10) Re -N(3) -C(10)-C(9) -38 .1(9) 0(4) -Re -N(3)-C(10) 10 .6(6) - 181 -[Me2Ga(pz") (OCH2CH2SPh) ]Re(CO)-, Bond lengths (A) w i t h estimated standard d e v i a t i o n s i n parentheses Bond uncorr. c o r r . Bond uncorr. c o r r . Re - s 2 . 5 0 9 1 ( 1 4 ) 2 . 5 1 4 0 ( 4 ) - C ( 9 ) 1 . 4 3 0 ( 6 ) 1 . 4 3 3 Re - 0 ( 4 ) 2 . 1 5 2 ( 3 ) 2 . 1 58 N O ) - N ( 2 ) 1 . 3 9 2 ( 6 ) 1 . 3 9 5 Re - N ( 1 ) 2 . 1 8 3 ( 4 ) 2 . 1 8 6 N O ) - C ( 6 ) i . 3 4 4 ( 6 ) 1 . 3 4 6 Re - C O ) 1 . 9 0 8 ( 6 ) 1.911 N ( 2 ) - C ( 8 ) 1 • 3 2 B ( 7 ) 1 . 3 2 8 Re - C ( 2 ) 1 . 9 0 7 ( 6 ) 1 . 9 1 1 C ( 6 ) - C ( 7 ) 1 . 3 8 4 ( 9 ) 1 . 3 8 5 Re - C ( 3 ) 1 . 9 1 5 ( 6 ) 1 . 9 1 6 C ( 6 ) - C ( 1 7 ) 1 . 5 0 5 ( 9 ) 1 . 5 0 7 Ga - 0 ( 4 ) 1 . 9 3 1 ( 4 ) 1 . 9 3 4 C ( 7 ) - C ( 8 ) 1 . 3 9 8 ( 9 ) 1 . 4 0 1 Ga - N ( 2 ) 1 . 9 8 2 / 5 ) 1 . 9 8 5 C ( 8 ) - C ( 1 8 ) 1 . 4 8 1 ( 1 0 ) 1 . 4 8 2 Ga - C ( 4 ) 1 . 9 4 1 ( 7 ) 1 . 9 4 2 C ( 9 ) - C ( 1 0 ) i . 4 9 9 ( 8 ) 1 . 5 0 1 Ga - C ( 5 ) 1 . 9 9 6 ( 6 ) 1 . 9 9 8 C O D - C O 2 ) 1 . 3 7 3 ( 8 ) 1 . 3 8 5 S - C O O ) 1 . 8 1 4 ( 6 ) 1 . 8 1 8 C O D - C O 6 ) 1 . 3 8 4 ( 8 ) 1 . 3 9 4 S - C O D 1 . 7 8 3 ( 6 ) 1 . 7 8 8 C ( 1 2 ) - C ( 1 3 ) 1 . 3 9 3 ( 9 ) 1 . 3 9 9 0 ( 1 ) - C O ) 1 . 1 6 2 ( 8 ) 1 . 1 6 2 C ( 1 3 ) - C ( 1 4 ) 1 . 3 6 3 ( 1 2 ) 1 . 3 7 4 0 ( 2 ) - C ( 2 ) 1 . 1 4 8 ( 7 ) 1 . 1 4 9 C ( 1 4 ) - C ( 1 5 ) 1 . 3 7 6 ( 1 3 ) 1 . 3 8 7 0 ( 3 ) - C ( 3 ) 1 . 1 4 7 ( 7 ) 1 .1 4 8 C ( 1 5 ) - C ( 1 6 ) 1 . 3 6 3 ( 1 0 ) 1 . 3 6 8 - 182 -[ M e 2 G a ( p z " ) ( O C H 2 C H 2 S P h ) ] R e ( C O ) 3 , c o n t ' d Bond angles (deg) w i t h estimated standard d e v i a t i o n s i n parentheses Bonds Angle(deg) Bonds Angle(deg) s -Re - 0 ( 4 ) 8 0 . 2 4 0 0 ) Re - N O ) - N ( 2 ) 1 1 7 . 3 ( 3 ) s -Re - N O ) 8 3 . 4 6 ( 1 2 ) Re - N O ) - C ( 6 ) 1 3 5 . 4 ( 4 ) s -Re - C O ) 1 7 5 . 4 ( 2 ) N ( 2 ) - N ( 1 ) - C ( 6 ) 1 0 6 . 2 ( 4 ) s -Re - C ( 2 ) 9 4 . 5 ( 2 ) Ga - N ( 2 ) - N O ) 1 2 0 . 6 ( 3 ) s -Re - C ( 3 ) 9 5 . 3 ( 2 ) Ga - N ( 2 ) - C ( 8 ) 1 2 8 . 7 ( 4 ) 0 ( 4 -Re - N O ) 81 . 3 8 ( 1 4 ) N ( 1 ) - N ( 2 - C ( 8 ) 1 0 9 . 8 ( 5 ) 0 ( 4 -Re - C O ) 9 5 . 7 ( 2 ) Re - C O - 0 ( 1 ) 1 7 6 . 4 ( 6 ) 0 ( 4 -Re - C ( 2 ) 174 . 5 ( 2 ) Re - C ( 2 ) - 0 ( 2 ) 1 7 7 . 7 ( 6 ) 0 ( 4 -Re - C ( 3 ) 9 3 . 1 ( 2 ) Re - C ( 3 - 0 ( 3 ) 1 7 8 . 6 ( 5 ) N O -Re - C O ) 9 3 . 8 ( 2 ) N O ) - C ( 6 - C ( 7 ) 1 1 0 . 1 ( 5 ) N ( 1 -Re - C ( 2 ) 9 6 . 3 ( 2 ) N O ) - C ( 6 - C ( 1 7 ) 1 2 2 . 6 ( 5 ) N O -Re - C ( 3 ) 174 . 5 ( 2 ) C ( 7 ) - C ( 6 - C ( 1 7 ) 1 2 7 . 4 ( 5 ) C O -Re - C ( 2 ) 8 9 . 4 ( 3 ) C ( 6 ) - C ( 7 ] - C ( 8 ) 1 0 5 . 7 ( 5 ) C O -Re - C ( 3 ) 8 7 . 1 ( 2 ) N ( 2 ) - C ( 8 - C ( 7 ) 1 0 8 . 2 ( 5 ) C ( 2 -Re - C ( 3 ) 8 9 . 2 ( 2 ) N ( 2 ) - C ( 8 - C O B ) 121 . 7 ( 6 ) 0 ( 4 -Ga - N ( 2 ) 91 . 2 ( 2 ) C ( 7 ) - C ( 8 - C ( 1 8 ) 1 3 0 . 1 ( 6 ) 0 ( 4 -Ga - C ( 4 ) 1 0 9 . 8 ( 3 ) 0 ( 4 ) - C ( 9 - C O O ) 1 1 0 . 0 ( 4 ) 0 ( 4 -Ga - C ( 5 ) 1 0 9 . 5 ( 2 ) S - C O 0 ) - C ( 9 ) 1 1 1 . 3 ( 4 ) N ( 2 -Ga - C ( 4 ) 1 1 0 . 2 ( 3 ) S - C ( 1 ) - C ( 1 2 ) 1 2 3 . 9 ( 5 ) N ( 2 -Ga - C ( 5 ) 1 0 8 . 6 ( 3 ) S - C O ) - C ( 1 6 ) 1 1 6 . 2 ( 5 ) C ( 4 -Ga - C ( 5 ) 1 2 2 . 9 ( 3 ) C ( 1 2 ) - C ( D - C ( 1 6 ) 1 1 9 . 8 ( 6 ) Re -S - C O O ) 97 . 4 ( 2 ) C O 1 ) - C ( 2 ) - C ( 1 3 ) 1 1 8 . 9 ( 7 ) Re - S - C O D 1 0 8 . 4 ( 2 ) C ( 1 2 ) - C ( 3 ) - C ( 1 4 ) 121 . 0 ( 7 ) C O 0 ) - S - C O D 1 0 5 . 7 ( 3 ) C ( 1 3 ) - C ( 4 ) - C ( 1 5 ) 1 1 9 . 6 ( 7 ) Re - 0 ( 4 ) -Ga 1 16 . 7 ( 2 ) C ( 1 4 ) - C ( 5 ) - C ( 1 6 ) 1 2 0 . 1 ( 7 ) Re - 0 ( 4 ) - C ( 9 ) 114 . 3 ( 3 ) C ( 1 1 ) - C ( 6 ) - C O 5 ) 1 2 0 . 6 ( 7 ) Ga - 0 ( 4 ) - C ( 9 ) 1 1 9 . 8 ( 3 ) I n t r a - a n n u l a r t o r s i o n angles (deg) standard d e v i a t i o n s i n parentheses Atoms Value(deg) NO) -Re -0(4)-Ga -33. 4(2) N(2) -Ga -0(4)-Re 27. 4(2) 0(4) -Ga -N(2)-N(1) -3. 1(4) Re -NO ) -N(2)-Ga -21 . 9(5) 0(4) -Re -N(1)-N(2) 31 . 5(3) S -Re -0(4)-C(9) 28. 6(3) Re -0(4) -C(9)-C(10) -56. 2(4) 0(4) -C(9) -CO0)-S 55. 4(5) Re -S -CO0)-C(9) -28. 1 (4) 0(4) -Re -S -COO) 0. 8(2) - 183 -Bond lengths (A) w i t h estimated standard d e v i a t i o n s i n parentheses Bond uncorr. c o r r . Bond uncorr. c o r r . Re -0(4) 2.153(6) 2 .157 0(4) -C(9) 1 .41900) 1 .421 Re -N(1) 2.189(7) 2 .195 NO) -N(2) 1 .372(9) 1 .375 Re -N(3) 2.300(7) 2 .306 NO ) -C(6) 1 .358(11) 1 .359 Re -CO ) 1.907(10) 1 .909 N(2) -C(8) 1 .352(11) 1 .355 Re -C(2) 1.910(10) 1 .915 N(3) -COO) 1 .488(14) 1 .490 Re -C(3) 1 .89900) 1 .904 N(3) -C(13) 1 .483(13) 1 .484 Ga -0(4) 1.933(6) 1 .938 N(3) -C(14) 1 .485(14) 1 .486 Ga -N(2) 2.000(7) 2 .006 C(6) -C(7) 1 .394(13) 1 .397 Ga -C(4) 1 .940{11 ) 1 .949 C(6) - C O D 1 .494(14) 1 .494 Ga -C(5) 1.955(12) 1 .961 C(7) -C(8) 1 .36804) 1 .370 0(1 ) -CO) 1.146(11 ) 1 .146 C(8) -C(12) 1 .490(14) 1 .492 0(2) -C(2) 1.151(11) 1 .152 C(9) -COO) 1 .51005) 1 .512 0(3) -C(3) 1.158(11 ) 1 .158 - 184 -[ M e 2 G a ( p z " ) ( O C H 2 C H - N H 2 ) ] R e ( C O ) 3 , c o n t ' d E t Bond angles (deg) w i t h estimated standard d e v i a t i o n s i n parentheses Bonds Angle(deg) Bonds Angle(deg) 0(4 -Re -NO ) 82.8(2) Re -N(1)-N(2) 119.0(5) 0(4 -Re -N(3) 78.6(3) Re -N(1)-C(6) 133.9(6) 0(4 -Re -CO ) 175.8(4) N(2)-N(1)-C(6) 107.1(7) 0(4 -Re -C(2) 92.5(3) Ga -N(2)-N(1) 120.7(5) 0(4 -Re -C(3) 97.6(3) Ga -N(2)-C(8) 129.7(6) NO -Re -N(3) 87.2(3) N( 1 )-N(2)-C(8) 109.3(7) NO -Re -CO ) 98.7(3) Re -N(3)-C(10) 105.2(6) NO -Re -C(2) 175.0(3) Re -N(3)-C(13) 111.1(6) NO -Re -C(3) 92.3(3) Re -N(3)-C(14) 114.3(6) N(3 -Re -CO ) 97.5(4) C(10)-N(3)-C(13) 110.5(8) N(3 -Re -C(2) 93.2(4) C(10)-N(3)-C(14) 107.7(9) N(3 -Re -C(3) 176.2(3) C(13)-N(3)-C(14) 108.0(8) CO -Re -C(2) 86.1(4) Re -CO)-0(1) 176.9(9) CO -Re -C(3) 86.3(4) Re -C(2)-0(2) 177.1(9) C(2 -Re -C(3) 86.9(4) Re -C(3)-0(3) 176.4(8) 0(4 -Ga -N(2) 90.0(3) NO )-C(6)-C(7) 108.5(8) 0(4 -Ga -C(4) 107.7(4) N(1)-C(6)-C(11) 124.7(9) 0(4 -Ga -C(5) 111.1(4) C(7)-C(6)-C(11) 126.8(8) N(2 -Ga -C(4) 109.7(4) C(6)-C(7)-C(8) 106.9(8) N(2 -Ga -C(5) 110.5(4) N(2)-C(8)-C(7) 108.2(8) C(4 -Ga -C(5) 122.9(5) N(2)-C(8)-C(12) 121.7(9) Re -0(4) -Ga 115.7(3) C(7)-C(8)-C(12) 130.2(9) Re -0(4) -C(9) 110.6(5) 0(4)-C(9)-COO) 109.0(7) Ga -0(4) -C(9) 119.4(5) N(3)-C(10)-C(9) 110.2(8) I n t r a - a n n u l a r t o r s i o n angles (deg) standard d e v i a t i o n s i n parentheses Atoms Value(deg) N(2) -Re -0(4)-Ga 29.9(4) 0(4) -Re -N(2)-N(1) -11.6(7) NO ) -Ga -0(4)-Re -34.5(5) 0(4) -Ga -NO )-N(2) 27.1(8) Ga -NO ) -N(2)-Re -9.6(10) N(3) -Re -0(4)-C(9) -24.9(10) 0(4) -Re -N(3)-C(10) -4.2(11) Re -0(4) -C(9)-C(10) 54(2) Re -N(3) -CO0)-C(9) 31(2) 0(4) -C(9) -CO0)-N(3) -55(2) - 185 -[Me 2Ga(pz) 2]Rh(COD) Bond lengths (A) w i t h estimated standard d e v i a t i o n s i n parentheses Bond uncorr. c o r r . Bond uncorr. c o r r . Rh -NO ) 2.087(2) 2 .090 N(2) -C(9) 1 .340(3) 1 .342 Rh -CU) 2.131(3) 2 .146 C(3) -C(4) 1 .502(5) 1.516 Rh -C(5) 2.127(3) 2 .140 C(3) -C(3)' 1 .417(7) 1 .423 Ga -N(2) 1.991(2) 1 .996 C(4) -C(5) 1 .379(4) 1 .395 Ga -CO ) 1.955(4) 1 .963 C(5) -C(6) 1 .500(4) 1.511 Ga -C(2) 1.971(4) 1 .978 C(6) -C(6)' 1 .435(8) 1 .441 N(1) -N(2) 1.369(3) 1 .371 C(7) -C(8) 1 .384(4) 1 .386 NO) -C(7) 1.337(3) 1 .339 C(8) -C(9) 1 .358(4) 1 .360 Bond angles (deg) w i t h estimated standard d e v i a t i o n s i n parentheses Bonds Angle(deg) Bonds Angle(deg) NO) -Rh -C(4) 91 .4600) NO) -Rh -C(5) 91 .08(10) NO ) -Rh -NO )' 90.11(12) NO) -Rh -C(4)' 161.72(11) NO ) -Rh -C(5)' 160.38(11) C(4) -Rh -C(5) 37.8002) C(4) -Rh -C(4)' 81.5(2) C(4) -Rh -C(5)' 93.51(11) C(5) -Rh -C(5)' 81.4(2) N(2) -Ga -CO ) 109.35( 1 1 ) N(2) -Ga -C(2) 106.580 2) N(2) -Ga -N(2)' 94.09(14) CO ) -Ga -C(2) 126.1(2) Rh -NO) -N(2) 122.2(2) Rh -NO ) -C(7) 131.1(2) N(2) -NO) -C(7) 106. 7(2) Ga -N(2) -NO ) 122. 5(2) Ga -N(2) -C(9) 129. 3(2) NO) -N(2) -C(9) 108. 2(2) Rh -C(4) -C(3) 110. 9(2) Rh -C(4) -C(5) 70. 9(2) C(3) -C(4) -C(5) 124. 5(3) Rh -C(5) -C(4) 71 . 3(2) Rh -C(5) -C(6) 111. 5(2) C(4) -C(5) -C(6) 124. 8(3) C(5) -C(6) -C(6)' 116. 5(2) NO) -C(7) -C(8) 110. 4(3) C(7) -C(8) -C(9) 104. 7(3) N(2) -C(9) -C(8) 1 10. 1(2) - 186 -I n t r a - a n n u l a r t o r s i o n a n g l e s ( d e g ) s t a n d a r d d e v i a t i o n s i n p a r e n t h e s e s Atoms V a l u e ( d e g ) [Me 2Ga(pz) 2]Rh(COD)* N ( 1 ) ' - R h - N ( 1 ) - N ( 2 ) 4 9 . 1 ( 2 ) Rh - N ( 1 ) - N ( 2 ) - G a - 1 . 4 ( 3 ) N ( 2 ) ' - G a - N ( 2 ) - N ( 1 ) - 4 8 . 7 ( 2 ) C ( 4 ) - C ( 3 ) - C ( 3 ) ' - C ( 4 ) ' 0 C ( 3 ) * - C ( 3 ) - C ( 4 ) - C ( 5 ) 6 9 . 2 ( 3 ) C ( 3 ) - C ( 4 ) - C ( 5 ) - C ( 6 ) 0 . 9 ( 5 ) C ( 4 ) - C ( 5 ) - C ( 6 ) - C ( 6 ) ' - 7 0 . 0 ( 3 ) C ( 5 ) - C ( 6 ) - C ( 6 ) ' - C ( 5 ) ' 0 [(u-pz")Rh(CO) 2] 2 N ( 3 ) - R h ( 1 ) - N ( l ) - N ( 2 ) - 5 6 . 8 ( 3 ) R h ( 1 ) - N ( 1 ) - N ( 2 ) - R h ( 2 ) - 4 . 8 ( 3 ) N ( 4 ) - R h ( 2 ) - N ( 2 ) - N ( 1 ) 6 3 . 3 ( 3 ) N ( 2 ) - R h ( 2 ) - N ( 4 ) - N ( 3 ) - 5 7 . 3 ( 3 ) R h ( 1 ) - N ( 3 ) - N ( 4 ) - R h ( 2 ) - 4 . 6 ( 4 ) N ( 1 ) - R h ( 1 ) - N ( 3 ) - N ( 4 ) 6 3 . 0 ( 3 ) N ( 7 ) - R h ( 3 ) - N ( 5 ) - N ( 6 ) 5 8 . 8 ( 3 ) R h ( 3 ) - N ( 5 ) - N ( 6 ) - R h ( 4 ) 2 . 3 ( 4 ) N ( 8 ) - R h ( 4 ) - N ( 6 ) - N ( 5 ) - 6 2 . 4 ( 3 ) N ( 6 ) - R h ( 4 ) - N ( 8 ) - N ( 7 ) 5 9 . 8 ( 3 ) R h ( 3 ) - N ( 7 ) - N ( 8 ) - R h ( 4 ) 0 . 8 ( 4 ) N ( 5 ) - R h ( 3 ) - N ( 7 ) - N ( 8 ) - 6 1 . 2 ( 3 ) [ (y-pz")Rn(COD)] 2 N ( 3 ) - R h ( 1 ) - N ( D - N ( 2 ) 6 7 . 2 ( 2 ) R h ( 1 ) - N ( 1 ) - N ( 2 ) - R h ( 2 ) - 3 . 2 ( 2 ) N ( 4 ) - R h ( 2 ) - N ( 2 ) - N ( l ) - 6 2 . 1 ( 2 ) N ( 2 ) - R h ( 2 ) - N ( 4 ) - N ( 3 ) 6 8 . 0 ( 2 ) R h ( l ) - N ( 3 ) - N ( 4 ) - R h ( 2 ) - 4 . 3 ( 3 ) N ( 1 ) - R h ( 1 ) - N ( 3 ) - N ( 4 ) - 6 1 . 5 ( 2 ) C ( 1 8 ) - C ( 1 1 ) - C ( 1 2 ) - C ( 1 3 ) - 1 . 4 ( 6 ) C ( 1 1 ) - C ( 1 2 ) - C ( 1 3 ) - C ( 1 4 ) - 8 2 . 9 ( 6 ) C ( 1 2 ) - C ( 1 3 ) - C ( 1 4 ) - C ( 1 5 ) 1 9 . 3 ( 7 ) C ( 1 3 ) - C ( 1 4 ) - C ( 1 5 ) - C ( 1 6 ) 5 4 . 9 ( 7 ) C ( 1 4 ) - C ( 1 5 ) - C ( 1 6 ) - C ( 1 7 ) 3 . 0 ( 6 ) C ( 1 5 ) - C ( 1 6 ) - C ( 1 7 ) - C ( 1 8 ) - 8 3 . 8 ( 5 ) C ( 1 6 ) - C ( 1 7 ) - C ( 1 8 ) - C ( 1 1 ) 1 7 . 0 ( 6 ) C ( 1 2 ) - C ( 1 1 ) - C ( 1 8 ) - C ( 1 7 ) 5 9 . 0 ( 6 ) C ( 2 6 ) - C ( 1 9 ) - C ( 2 0 ) - C ( 2 1 ) 1 . 3 ( 6 ) C ( 1 9 ) - C ( 2 0 ) - C ( 2 1 ) - C ( 2 2 ) - 8 1 . 6 ( 7 ) C ( 2 0 ) - C ( 2 1 ) - C ( 2 2 ) - C ( 2 3 ) 1 4 . 7 ( 8 ) C ( 2 1 ) - C ( 2 2 ) - C ( 2 3 ) - C ( 2 4 ) 5 9 . 4 ( 7 ) C ( 2 2 ) - C ( 2 3 ) - C ( 2 4 ) - C ( 2 5 ) 1 . 1 ( 6 ) C ( 2 3 ) - C ( 2 4 ) - C ( 2 5 ) - C ( 2 6 ) - 8 1 . 1 ( 5 ) C ( 2 4 ) - C ( 2 5 ) - C ( 2 6 ) - C ( 1 9 ) 1 4 . 7 ( 7 ) C ( 2 0 ) - C ( 1 9 ) - C ( 2 6 ) - C ( 2 5 ) 5 9 . 7 ( 6 ) * m i r r o r - r e l a t e d t o r s i o n a n g l e s h a v e t h e o p p o s i t e s i g n - 187 -[ ( u - p z " ) R h ( C O ) 2 ] Bond l e n g t h s (A) w i t h e s t i m a t e d s t a n d a r d d e v i a t i o n s i n p a r e n t h e s e s Bond u n c o r r . c o r r . Bond u n c o r r . c o r r . Rh( 1 ) - N ( 1 ) 2 .065(3) 2 -o .071 C ( 5 ) - C ( 6 ) 1 .377(7) 1 .384 Rh( 1 )-N(3) 2 .064(3) 2 .070 C ( 5 ) - C ( 1 1 ) 1 .494(7) 1 .500 Rh( 1 ) - C ( l ) 1 .872(5) 1 .876 C ( 6 ) - C ( 7 ) 1 .366(7) 1 .374 Rh( 1 )-C(2) 1 .847(5) 1 .851 C ( 7 ) - C ( 1 2 ) 1.500(7) 1 .505 Rh(2 )-N(2) 2 .054(3) 2 .060 C ( 8 ) - C ( 9 ) 1 . 3 8 1 ( 7 ) 1 .390 Rh(2 )-N(4) 2 .057(3) 2 .063 C ( 8 ) - C ( 1 3 ) 1.483(7) 1 .489 Rh(2 )-C(3) 1 .851(5) 1 .853 C ( 9 ) - C ( 1 0 ) 1 . 3 6 5 ( 6 ) 1 .374 Rh(2 )-C(4) 1 .850(5) 1 .853 C( 1 0 ) - C ( 1 4 ) 1 . 5 0 3 ( 7 ) 1 .509 Rh(3 )-N(5) 2 •P64(3) 2 .069 0 ( 5 ) - C ( 1 5 ) 1 . 1 3 2 ( 6 ) 1 . 1 34 Rh(3 )-N(7) 2 .071(3) 2 .076 0 ( 6 ) - C ( 1 6 ) 1 .136(5) 1 . 138 Rh(3 )-C(15) 1 .850(5) 1 .854 0( 7 ) - C ( 1 7 ) 1 . 1 3 5 ( 5 ) 1 . 1 3 8 Rh(3 )-C(16) 1 .842(5) 1 .846 0 ( 8 ) - C < 1 8 ) 1.124(5) 1 . 1 28 Rh(4 )-N(6) 2 .059(3) 2 .065 N ( 5 ) - N ( 6 ) 1 .367(4) 1 .374 Rh(4 )-N(8) 2 .066(3) 2 .073 N ( 5 ) - C ( 1 9 ) 1.339(5) 1 .349 Rh(4 ) - C ( l 7 ) - 1 .846(5) 1 .848 N ( 6 ) - C ( 2 1 )- 1 .346(5) 1 .356 Rh(4 )-C(18) 1 .855(5) 1 .857 N ( 7 ) - N ( 8 ) " 1 .365(4) 1 .371 0 ( 1 ) - C ( 1 ) 1 .122(5) 1 .123 N ( 7 ) - C ( 2 2 ) 1 .335(5) 1 .342 0 ( 2 ) - C(2) 1 .122(5) 1 .123 N ( 8 ) - C ( 2 4 ) 1 .337(5-) 1 .344 0 ( 3 ) - C(3) 1 .135(5) 1 .139 C ( 1 9 ) - C ( 2 0 ) 1.370(6) 1 .378 0 ( 4 ) - C ( 4 ) 1 .132(6) 1 .136 C ( 1 9 ) - C ( 2 5 ) 1.505(6) 1.511 N(1) -N(2) 1 .381(5) 1 .389 C ( 2 0 ) - C ( 2 1 ) 1.382(6) 1 .391 N(1) -C(5) 1 .337(5) 1 .346 C ( 2 1 ) - C ( 2 6 ) 1.486(6) 1 .491 N(2) -C(7) 1 .342(5) 1 .350 C ( 2 2 ) - C ( 2 3 ) 1.375(6) 1 .382 N(3) -N(4) 1 .369(5) 1 .377 C ( 2 2 ) - C ( 2 7 ) 1.502(6) 1 .507 N(3) -C(8) 1 .348(5) 1 .359 C ( 2 3 ) - C ( 2 4 ) 1.388(6) 1 .395 N(4) -C(10) 1 .346(5) 1 .358 C ( 2 4 ) - C ( 2 8 ) 1.504(6) 1 .509 - 188 -[ ( p-pz")Rh ( CO) 23 2, cont'd Bond angles (deg) with estimated standard d e v i a t i o n s in parentheses Bonds Angle(deg) Bonds Angle(deg) N (D-Rh(1)-N(3) 87.79(13) C(6)-C(5)-C(1 1 ) 129. 1 4) N ( l ) - R h ( U - C ( l ) 92.6(2) C(5)-C(6)-C(7) 106. 9 4) N(1)-Rh(1)-C(2) 177.3(2) N(2)-C(7)-C(6) 108. 8 4) N(3)-Rh(1)-C(1) 179.0(2) N(2)-C(7)-C(12) 120. 1 4) N(3)-Rh(1)-C(2) 90.0(2) C(6)-C(7)-C(12) 131. 1 5) C (D-Rh (D-C(2) 89.6(2) N(3)-C(8)-C (9) 108. 3 4) N(2)-Rh(2)-N(4) 88.07(13) N(3)-C(8)-C(13) 120. 9 4) N(2)-Rh(2)-C(3) 89 .8(2) C(9)-C(8)-C(13) 130. 8 4) N(2)-Rh(2)-C(4) 178.2(2) C(8)-C (9)-C(10) 106. 9 4) N(4)-Rh(2)-C(3) 177 .9(2) N(4)-C(10)-C (9) 108. 6 4) N(4)-Rh(2)-C<4) 91.3(2) N(4)-C(10)-C(14) 121 . 0 4) C(3)-Rh(2)-C(4) 90 .8(2) C(9)-C(10)-C(14) 130. 4 4) N(5)-Rh(3)-N(7) 87.63(12) Rh(3)-N(5)-N(6) 116. 2 2) N(5)-Rh(3)-C(15) 91.5(2) Rh(3)-N(5)-C(l9) 135. 6 3) N(5)-Rh(3)-C(16) 177.8(2) N(6)-N(5)-C(19) 108. 0 3) N(7)-Rh(3)-C(15) 178.9(2) Rh(4)-N(6)-N(5) 118. 4 2) N(7)-Rh(3)-C(16) 90.4(2) Rh(4)-N(6)-C(21 ) 132. 8 3) C(l5)-Rh(3)-C(16) 90.5(2) N(5)-N(6)-C(21) 108. 3 3) N(6)-Rh(4)-N(8) 86.97(12) Rh(3)-N(7)-N(8) 117. 6 2) N(6)-Rh(4)-C(17) 90.5(2) Rh(3)-N(7)-C(22) 133. 8 3) N(6)-Rh(4)-C ( l8) 178.5(2) N(8)-N(7)-C(22) 108. 5 3) N(8)-Rh(4)-C(l7) 176.96(15) Rh(4)-N(8)-N(7) 116. 8 2) N(8)-Rh(4)-C(18) 92 .9(2) Rh(4)-N(8)-C(24) 135.1 3) C(17)-Rh(4)-C(l8) 89.7(2) N(7)-N(8)-C(24) 108. 0 3) Rh (D-N (D-N(2) U6.9(2) Rh(3)-C(15)-0(5) 178.8 4) Rh(1)-N(1)-C(5) 134 .8(3) Rh(3)-C(l6)-0(6) 178. 8 5) N(2)-N(1)-C(5) 108.1(3) Rh(4)-C(17)-0(7) 178. 6 4) Rh(2)-N(2)-N(1) 117.4(2) R h ( 4 ) - C ( l 8 ) - 0 ( 8 ) 178. 2 5) Rh(2)-N(2)-C(7) 134.2(3) N(5)-C(19)-C(20) 109. 2 4) N( 1)-N(2)-C(7) 107.6(3) N(5)-C(19)-C(25) 121 . 6 4) Rh(1)-N(3)-N(4) 117.7(2) C(20)-C(19)-C(25) 129. 2 4) Rh(1)-N(3)-C(8) 134.1(3) C(19)-C(20)-C(21) 106. 3 4) N(4)-N(3)-C(8) 107 .9(3) N(6)-C(21)-C(20) 108. 3 4) Rh(2)-N(4)-N(3) 117.0(2) N(6)-C(21)-C(26) 121 . 4 4) Rh(2)-N(4)-C(10) 134.7(3) C(20)-C(21)-C(26) 130. 3 4) N(3)-N(4)-C(10) 108.3(3) N(7)-C(22)-C(23) 109. 0 4) Rh(1)-C(1)-0(1) 178.7(4) N(7)-C(22)-C(27) 121 . 1 4) Rh(1)-C(2)-0(2) 179.5(4) C(23)-C(22)-C(27) 129. 8 4) Rh(2)-C(3)-0(3) 179.2(5) C(22)-C(23)-C(24) 105. 7 4) Rh(2)-C(4)-0(4) 178.1(4) N(8)-C(24)-C(23) 108. 8 4) N(1)-C(5)-C(6) 108.4(4) N(8)-C(24)-C(28) 121 . 1 4) N(1)-C(5)-C(11) 122.4(4) C(23)-C(24)-C(28) 130. 1 4) - 189 -[ (,u-pz")Rh(.COD) ] Bond l e n g t h s (A) wi t h estimated standard d e v i a t i o n s i n parentheses Bond uncorr. c o r r . Bond uncorr. c o r r . Rh(1)-N(1) 2 .084(3) 2 .087 C(3)-C(8) 1.495(5) 1 .496 Rh(»)-N(3) 2 .083(2) 2 .086 C(4)-C(5) 1.382(5) 1 .384 Rh(1)-C(11) 2 .135(3) 2 .136 C(4)-C(9) 1.495(5) 1 .495 Rh(1)-C(12) 2 .133(3) 2 .134 C(5)-C(6) 1.385(5) 1 .387 Rh(1)-C(15) 2 .122(3) 2 . 123 C(6)-C(10) 1 .488(5) 1 .489 Rh(1)-C(16) 2 .136(3) 2 .138 C(11)-C(12) 1 .397(5) 1 .408 Rh(2)-N(2) 2 .084(2) 2 .087 C(11)-C(18) 1.489(5) 1 .502 Rh ( 2)-N(4 ) 2 .085(2) 2 .088 C(12)-C(13) 1.521(6) 1 .534 Rh(2)-C(19) 2 .132(3) 2 . 134 C(13)-C(14) 1 .458(8) 1 .466 Rh(2)-C(20) 2 .123(4) 2 .124 C(14)-C(15) 1.518(6) 1 .530 Rh(2)-C(23) 2 .123(3) 2 .124 C(15)-C(16) 1.391(5) 1 .404 Rh(2)-C(24) 2 .139(3) 2 .141 C(16)-C(17) 1.533(6) 1 .545 N(1)-N(2) 1 .373(3) 1 .376 C(17)-C(18) 1.481(7) 1 .489 N(1 ) - C ( D 1 .342(4) 1 .344 C(19)-C(20) 1.355(6) 1 .365 N(2)-C(3) 1 .339(4) 1 .341 C(19)-C(26) 1.502(6) 1.510 N(3)-N(4) 1 .368(3) 1 .371 C(20)-C(21) 1.511(7) 1.519 N(3)-C(4) 1 .345(4) 1 .347 C(21)-C(22) 1 .483(8) 1 .490 N(4)-C(6) 1 .345(4) 1 .347 C(22)-C(23) 1.499(6) 1.513 C(1)-C(2) 1 .389(5) 1 .391 C(23)-C(24) 1.376(6) 1 .386 C(1)-C(7) 1 .499(5) 1 .499 C(24)-C(25) 1 .518(6) 1 .530 C(2)-C(3) 1 .384(5) 1 .386 C(25)-C(26) 1 .474(7) 1 .480 - 1 9 0 -[ (y-pz")Rh(COD)] , cont'd Bond angles (deg) wi th es t imated standard d e v i a t i o n s in parentheses Bonds Angle(deg) Bonds Angle(deg) N(1)-Rh(1)-N(3) 84. 45( 0) C(2) -CO )-C(7) 129.1(3) N(1)-Rh(1)-C(11) 163. 86( 2) C O ) -C(2)-C(3) 105.6(3) N(1)-Rh(1)-C(12) 157. 85( 2) N(2) -C(3)-C(2) 109.0(3) N(1)-Rh(1)-C(15) 90. 70( 2) N(2) -C(3)-C(8) 122.9(3) N(1)-Rh(1)-C(16) 95. 34( 3) C(2) -C(3)-C(8) 128.1(3) N(3)-Rh(1)-C(11) 93. 55( 2) N(3) -C(4)-C(5) 109.1(3) N(3)-Rh(1)-C(12) 94. 74( 2) N(3) -C(4)-C(9) 122.1(3) N(3)-Rh(1)-C(15) 160. 08( 2) C(5) -C(4)-C(9) 128.8(3) N(3)-Rh(l)-C(16) 161 . 51 ( 3) C(4) -C(5)-C(6) 105.9(3) C(11)-Rh(1)-C(12) 38. 21 ( 4) N(4) -C(6)-C(5) 108.7(3) C ( 1 1 ) - R h ( D - C ( l 5 ) 96. 27( 4) N(4) -C(6)-C(10) 122.5(3) C(11)-Rh(l)-C(16) 81 . 52( 5) C(5) -C(6)-C(10) 128.7(3) C ( l 2 ) - R h ( l ) - C ( 1 5 ) 82. 56( 4) RhO )-C(11)-C(12) 70.8(2) C(12)-Rh(1)-C(16) 92. 30( 5) RhO )-C(11)-C0 8) 112.2(3) C(15)-Rh(1)-C(l6) 38. 1 4( 5) C( 12 )-C(11 )-C08) 124.5(4) N(2)-Rh(2)-N(4) 83. 87( 0) Rh( 1 )-C(12)-C(11) 71.0(2) N(2)-Rh(2)-C(19) 94. 04( 3) Rh( 1 )-C(12)-C(l3) 110.8(3) N(2)-Rh(2)-C(20) 94. 1 1 ( 4) CO 1 )-C(12)-C(l3) 123.5(4) N(2)-Rh(2)-C(23) 159. 05( 4) C(12 )-C(13)-C(14) 116.1(4) N(2)-Rh(2)-C(24) 163. 12( 3) C(13 )-C(14)-C(15) 115.1(4) N(4)-Rh(2)-C(19) 162. 40( 3) Rh( 1 )-C(15)-C(14) 109.9(3) N(4)-Rh(2)-C(20) 160. 28( 4) Rh( 1 )-C(15)-C(16) 71.5(2) N(4)-Rh(2)-C(23) 92. 66( 3) C(14 )-C(15)-C(16) 125.9(4) N(4)-Rh(2)-C(24) 95. 35( 3) RhO )-C(16)-C(l5) 70.4(2) C(l9)-Rh(2)-C(20) 37. 1(2 Rh( 1 )-C(16)-C(17) 112.4(3) C(19)-Rh(2)-C(23) 95. 2(2 C(15 )-C(16)-C(17) 122.8(4) C(19)-Rh(2)-C(24) 81 . 6(2 C(16 )-C(17)-C(l8) 114.4(3) C(20)-Rh(2)-C(23) 82. 2(2 C( 1 1 )-C(l8)-C(17) 115.6(3) C(20)-Rh(2)-C(24) 92. 2(2 Rh(2 )-CO9)-C(20) 71.0(2) C(23)-Rh(2)-C(24) 37. 7(2 Rh(2 )-C(l9)-C(26) 111.6(3) Rh(1)-N(1)-N(2) 116. 0(2 C(20 )-C(l9)-C(26) 125.2(4) R h ( l ) - N ( l ) - C ( l ) 135. 2(2 Rh(2 )-C(20)-CO9) 71.8(2) N(2)-N(1)-C(1) 107. 8(2 Rh(2 )-C(20)-C(21) 112.0(3) Rh(2)-N(2)-N(1) 114. 5(2 C(19 )-C(20)-C(21) 123.5(5) Rh(2)-N(2)-C(3) 135. 0(2 C(20 )-C(21)-C(22) 115.3(4) N(1)-N(2)-C(3) 108. 5(2 C(21 )-C(22)-C(23) 115.3(4) Rh(1)-N(3)-N(4) 114. 1(2 Rh(2 )-C(23)-C(22) 111.0(3) Rh(1)-N(3)-C(4) 134. 9(2 Rh(2 )-C(23)-C(24) 71.8(2) N(4)-N(3)-C(4) 108. 0(2 C(22 )-C(23)-C(24) 125.1(4) Rh(2)-N(4)-N(3) 116. 5(2 Rh(2 )-C(24)-C(23) 70.5(2) Rh(2)-N(4)-C(6) 133. 4(2 Rh(2 )-C(24)-C(25) 112.3(3) N(3)-N(4)-C(6) 108. 4(2 C(23 )-C(24)-C(25) 123.2(4) N(1)-C(1)-C(2) 109. 1(3 C(24 )-C(25)-C(26) 115.2(3) N(1)-C(1)-C(7) 121. 6(3 C(19 )-C(26)-C(25) 115.6(4) - 191 -[ M e 2 G a ( p z " ) 2 ] R h ( C O ) (PPh.,) Bond lengths (A) w i t h estimated standard d e v i a t i o n s i n parentheses Bond uncorr. c o r r . Bond uncorr. c o r r . Rh -P 2 .2686(8) 2 .2700 C(14) -C(15) 1.393(5) 1 .400 Rh -NO) 2 .088(3) 2 .090 C(14) -C(19) 1.392(5) 1 .397 Rh -N(3) 2 .093(2) 2 .097 -C(15] -C(16) 1.393(5) 1 .396 Rh -CO) .812(4) 1 .815 C( 16 -C(17) 1.371(6) 1 .376 Ga -N(2) .999(3) 2 .006 C(17 -C(18) 1.364(6) 1 .371 Ga -NU) .991(3) 1 .997 COB -C(19) 1.375(5) 1 .378 Ga -C(2) .978(4) 1 .984 C(20 -C(21) 1.396(5) 1 .403 Ga -C(3) .957(4) 1 .963 C(20] -C<25) 1.384(5) 1 .393 P -C(14) .828(3) 1 .831 C(21 ] -C(22) 1.378(5) 1 .383 P -C(20) .825(3) 1 .830 C(22) -C(23) 1.364(7) 1 .373 P -C(26) .844(3) 1 .848 C(23] -C(24) 1.358(7) 1 .364 0 -CO) .144(5) 1 .145 C(24 -C(25) 1.394(6) 1 .399 NO ) -N(2) .379(4) 1 .385 C(26 -C(27) 1.388(5) 1 .401 NO ) -CU) .346(4) 1 .358 C(26 -C(31 ) 1.364(5) 1 .374 N(2) -C(6) .350(4) 1 .361 C(27 -C(28) 1.386(5) 1 .390 N(3) -N(4) .380(3) 1 .385 C(28 -C(29) 1.359(6) 1 .369 N(3) -C(7) .333(4) 1 .341 C(29 -COO) 1.355(6) 1 .368 N U ) -C(9) .353(4) 1 .361 C(30 - C O D 1.399(5) 1 .402 C U ) -C(5) .362(6) 1 .370 C(32 -C(33) 1.35(2) C U ) -COO) .493(6) 1 .498 C(32 -C(37) 1.46(2) C(5) -C(6) .376(6) 1 .385 C(32 -C(38) 1.281(14) C(6) - C O D .493(5) 1 .498 C(33 -C(34) 1.22(2) C(7) -C(8) .388(5) 1 .395 C(34 -C(35) 1.32(3) C(7) -C(12) .488(5) 1 .493 C(35 -C(36) 1.39(3) C(8) -C(9) .381(5) 1 .388 C(36 -C(37) 1.37(2) C(9) - C 0 3 ) .489(5) 1 .493 - 19 2 -[Me 2 Ga (pz " ) 2 ]Rh(CO) (PPh.3) , c o n t ' d Bonds Angle(deg) Bonds Angle(deg) p -Rh -NO) 179.49(B) N(3)-C(7)-C(12) 122.4(3) p -Rh -N(3) 95.08(7) C(8)-C(7)-C(12) 128.3(3) p -Rh -CO) 88.90(13) C(7)-C(8)-CO) 105.9(3) NO) -Rh -N(3) 84.44(10) N(4)-CO)-C(8) 108.8(3) NO) -Rh -CO) 91.57(14) N(4)-CO)-C(13) 123.2(4) N(3) -Rh -CO) 175.52(15) C(8)-CO)-C(13) 128.0(3) N(2) -Ga -N(4) 95.71(11) P -C(14)-C(15) 120.6(3) N(2) -Ga -C(2) 110.16(15) P -C(14)-C(19) 121.4(3) N(2) -Ga -C(3) 110.9(2) C(15)-C(14)-C(19) 117.9(3) N(4) -Ga -C(2) 109.56(14) C(14)-C(15)-C(16) 119.9(3) N(4) -Ga -C(3) 112.0(2) C(15)-C(16)-C(17) 120.6(4) C(2) -Ga -C(3) 116.6(2) C(16)-C(17)-C(18) 119.9(4) Rh -P -C(14) 117.94(11) C(17)-C(18)-C(19) 120.3(4) Rh -P -C(20) 116.06(11) C ( 1 4 ) - C 0 9 ) - C 0 8 ) 121.3(4) Rh -P -C(26) 111.73(12) P -C(20)-C(21) 117.2(3) C(14)-P -C(20) 100.93(15) P -C(20)-C(25) 124.1(3) C(14)-P -C(26) 103.37(14) C(21)-C(20)-C(25) 11B.7(3) C(20)-P -C(26) 105.17(15) C(20)-C(21)-C(22) 120.2(4) Rh -NO -N(2) 121.1(2) C(21)-C(22)-C(23) 120.4(4) Rh -NO -C(4) 131.1(2) C(22)-C(23)-C(24) 120.5(4) N(2) -NO -C(4) 107.8(3) C(23)-C(24)-C(25) 120.3(4) Ga -N(2 -NO) 117.5(2) C(20)-C(25)-C(24) 119.9(4) Ga -N(2 -C(6) 134.4(2) P -C(26)-C(27) 117.9(3) NO ) -N(2 -C(6) 107.8(3) P -C(26)-C(31) 123.3(3) Rh -N(3 -N(4) 119.6(2) C(27)-C(26)-C(31) 118.8(3) Rh -N(3 -C(7) 132.1(2) C(26)-C(27)-C(28) 120.4(4) N(4) -N(3 -C(7) 108.3(3) C(27)-C(28)-C(29) 120.2(4) Ga -N(4 -N(3) 117.3(2) C(28)-C(29)-C(30) 119.9(4) Ga -N(4 -CO) 132.5(2) C(29)-C(30)-C(31) 120.6(4) N(3) -N(4 -CO) 107.8(3) C(26)-C(31)-C(30) 120.1(4) Rh -co -0 178.3(4) C(33)-C(32)-C(37) 124.2(13) NO ) -C(4 -C(5) 109.0(3) C(33)-C(32)-C(38) 121(2) NO ) -C(4 -COO) 121.1(4) C(37)-C(32)-C(38) 114(2) C(5) -C(4 -COO) 129.8(4) C(32)-C(33)-C(34) 109(2) C(4) -C(5 -C(6) 107.0(3) C(33)-C(34)-C(35) 141(3) N(2) -C(6 -C(5) 108.4(3) C(34)-C(35)-C(36) 109.5(15) N(2) -C(6 - C O D 123.9(4) C(35)-C(36)-C(37) 122(2) C(5) -C(6 l - C ( l l ) 127.7(4) C(32)-C(37)-C(36) 114(2) N(3) -C(7 -CO) 109.2(3) I n t r a - a n n u l a r t o r s i o n angles (deg) standard d e v i a t i o n s i n parentheses Atoms Value(deg) NO) -Rh -N(1)-N(2) 58.1(2) Rh -NO) -N(2)-Ga -3.3(3) N U ) -Ga -N(2)-N(1) -52.7(2) N(2) -Ga rN(4)-N(3) 43.3(2) Rh -NO) -N(4)-Ga 19.5(3) NO) -Rh -N(3)-N(4) -68.2(2) - 193 -[ M e G a ( p z ) 3 R h J 2 ( u - C O ) 3 Bond lengths (A) with estimated standard d e v i a t i o n s i n parentheses Bond Length(A) Bond Length(A) RhO )-NO ) 2 .168(7) N(3)-C(9) 1 .36003) RhO )-N(3) 2 .182(7) N(4)-C(11) 1.344(14) Rh( 1 >-N(5) 2 .1B8(7) N(5)-N(6) 1 .36600) Rh( 1 l-CO ) 2 .015(9) N(5)-C(12) 1 .279( 12) Rh( 1 >-C(2) 2 .000(9) N(6)-C(14) 1.318(12) RhO )-C(3) 2 .014(8) N(7)-N(8) 1 .37600) Rh(2 »-N(7) 2 .172(7) N(7)-C(15) 1.302(12) Rh(2 )-N(9) 2 .169(7) N(8)-C(17) 1.331(12) Rh(2 )-NO 1 ) 2 .205(7) N(9)-N(10) 1 .369( 1 1 ) Rh(2 l-CO ) 1 .997(9) N(9)-C(18) 1 .304(12) Rh(2 )-C(2) 1 .997(8) N O 0)-C ( 2 0 ) 1.335(12) Rh(2 )-C(3) .018(9) N O D - N O 2) 1.36300) GaO >-N<2) 1 .921(8) NO 1)-C ( 2 D 1.321 O D G a d >-N(4) 1 .938(9) N(12)-C(23) 1.375(11) GaO )-N(6) 1 .952(8) C(6)-C(7) 1 .40205) GaO >-C<4) 1 .939(12) C(7)-C(B) 1.364(15) Ga(2 )-N(B) 1 .898(8) C(9)-C(10) 1.38(2) Ga(2 >-NO0) 1 .919(8) C(10)-C(11) 1.37(2) Ga(2 )-N(12) 1 .915(8) C(12)-C(13) 1.412(14) Ga(2 )-C(5) 1 .954(13) C(13)-C(14) 1.35(2) 0(1)--CO) 1 .146(9) C(15)-C(16) 1.398(15) 0(2)--C(2) 1 .169(10) C(16)-C(17) 1.35(2) 0(3)--C(3) 1 .151(9) C(18)-C(19) 1.39(2) NO )• -N(2) 1 .366(11) C O 9)-C ( 2 0 ) 1.308(15) NO)- -C(6) 1 .343( 1 1 ) C(21)-C(22) 1.368(14) N(2)--C(8) t .356(12) C(22)-C(23) 1.331(14) N(3)--N(4) 1 .361(11) Rh(1)-Rh(2) 2.5618(8) - 194 -[ M e G a ( p z ) 3 R h ] 2 ( y - C O ) , c o n t ' d Bond angles (deg) with es t imated s tandard d e v i a t i o n s in parentheses Bonds Angle(deg) Bonds Angle(deg) N ( 1 ) - R h ( l ) - N ( 3 ) 9 0 . 5 ( 3 ) N ( 3 ) - N ( 4 ) - C ( 1 1 ) 107.31 9) N ( 1 ) - R h d ) - N ( 5 ) 9 1 . 2 ( 3 ) Rh( 1) - N ( 5 ) - N ( 6 ) 121.01 6) N ( 1 ) - R h ( 1 ) - C ( 1 ) 9 2 . 9 ( 3 ) Rh( 1) - N ( 5 ) - C ( 1 2 ) 1 3 0 . 8 7) N ( 1 ) - R h ( l ) - C ( 2 ) 9 3 . 1 ( 3 ) N ( 6 ) - N ( 5 ) - C ( 1 2 ) 1 0 8 . 1 ( 8) N ( 1 ) - R h ( l ) - C ( 3 ) 1 7 4 . 7 ( 3 ) Ga( 1) - N ( 6 ) - N ( 5 ) 120.61 6) N ( 3 ) - R h ( l ) - N ( 5 ) 8 9 . 8 ( 3 ) Ga( 1) - N ( 6 ) - C ( 1 4 ) 1 3 1 . 0 7) N ( 3 ) - R h ( l ) - C ( 1 ) 1 7 5 . 6 ( 3 ) N ( 5 ) - N ( 6 ) - C ( 1 4 ) 1 0 8 . 3 8) N ( 3 ) - R h ( l ) - C ( 2 ) 9 4 . 3 ( 3 ) R h ( 2 ) - N ( 7 ) - N ( B ) 1 2 1 . 7 5) N ( 3 ) - R h ( l ) - C < 3 ) 9 2 . 6 ( 3 ) R h ( 2 ) - N ( 7 ) - C ( 1 5 ) 1 3 1 . 9 7) N ( 5 ) - R h ( 1 ) - C ( 1 ) 9 3 . 0 ( 3 ) N ( 8 ) - N ( 7 ) - C ( 1 5 ) 1 0 6 . 2 8) N ( 5 ) - R h ( l ) - C ( 2 ) 1 7 4 . 0 ( 3 ) G a ( 2 ) - N ( 8 ) - N ( 7 ) 1 1 9 . 7 6) N ( 5 ) - R h ( l ) - C ( 3 ) 9 3 . 1 ( 3 ) G a ( 2 ) - N ( 8 ) - C ( 1 7 ) 131 .1 7) C ( 1 ) - R h ( l ) - C ( 2 ) 8 2 . 6 ( 3 ) N ( 7 ) - N ( 8 ) - C ( 1 7 ) 1 0 8 . 8 8) C ( 1 ) - R h d ) - C ( 3 ) 8 3 . 8 ( 3 ) R h ( 2 ) - N ( 9 ) - N ( 1 0 ) 1 2 2 . 6 6) C ( 2 ) - R h ( 1 ) - C ( 3 ) 8 2 . 3 ( 3 ) R h ( 2 ) - N ( 9 ) - C ( 1 8 ) 1 3 1 . 5 7) N ( 7 ) - R h ( 2 ) - N ( 9 ) 9 0 . 1 ( 3 ) N ( 1 0 ) - N ( 9 ) - C ( 1 8 ) 1 0 5 . 9 8) N ( 7 ) - R h ( 2 ) - N ( 1 1 ) 9 1 . 0 ( 3 ) G a ( 2 ) - N ( 1 0 ) - N ( 9 ) 1 1 9 . 2 6) N ( 7 ) - R h ( 2 ) - C ( 1 ) 9 2 . 7 ( 3 ) G a ( 2 ) - N ( 1 0 ) - C ( 2 0 ) 1 3 2 . 5 7) N ( 7 ) - R h ( 2 ) - C ( 2 ) 9 2 . 5 ( 3 ) N ( 9 ) - N( 1 0 ) - C ( 2 0 ) 1 0 8 . 3 8) N ( 7 ) - R h ( 2 ) - C ( 3 ) 1 7 4 . 2 ( 3 ) R h ( 2 ) - N ( 1 1 ) - N ( 1 2 ) 1 2 1 . 7 5) N ( 9 ) - R h ( 2 ) - N ( 1 1 ) B 9 . 0 ( 3 ) R h ( 2 ) - N ( 1 1 ) - C ( 2 1 ) 1 3 1 . 0 6) N ( 9 ) - R h ( 2 ) - C ( 1 ) 1 7 4 . 4 ( 3 ) N ( 1 2 ) - N ( 1 1 ) - C ( 2 1 ) 1 0 7 . 3 B) N ( 9 ) - R h ( 2 ) - C ( 2 ) 9 1 . 9 ( 3 ) G a ( 2 ) - N ( 1 2 ) - N ( 1 1 ) 1 1 9 . 7 5) N ( 9 ) - R h ( 2 ) - C ( 3 ) 9 2 . 5 ( 3 ) G a ( 2 ) - N ( 1 2 ) - C ( 2 3 ) 1 3 3 . 5 (7) N ( 1 1 ) - R h ( 2 ) - C < 1 ) 9 5 . 7 ( 3 ) N( 1 1 ) - N ( 1 2 ) - C ( 2 3 ) 1 0 6 . 8 [7) N ( 1 1 ) - R h ( 2 ) - C ( 2 ) 1 7 6 . 3 ( 3 ) Rh( 1) - C O ) - R h ( 2 ) 8 0 . 1 13) N(1 1 ) - R h ( 2 ) - C ( 3 ) 9 4 . 1 ( 3 ) R h ( 1 ) - C ( D - O O ) 1 3 9 . 3 (8) C ( D - R h ( 2 ) - C ( 2 ) 8 3 . 2 ( 4 ) R h ( 2 ) - C ( I ) - O O ) 1 4 0 . 5 (8) C ( 1 ) - R h ( 2 ) - C ( 3 ) B 4 . 2 ( 3 ) Rh( 1) - C ( 2 ) - R h ( 2 ) 8 0 . 5 (3) C ( 2 ) - R h ( 2 ) - C ( 3 ) 8 2 . 3 ( 3 ) Rh(1) - C ( 2 ) - 0 ( 2 ) 1 4 0 . 7 [7) N ( 2 ) - G a ( l ) - N ( 4 ) 9 9 . 0 ( 3 ) R h ( 2 ) - C ( 2 ) - 0 ( 2 ) 1 3 8 . 9 [7) N ( 2 ) - G a ( l ) - N ( 6 ) 1 0 1 . 7 ( 3 ) R h ( 1 ) - C ( 3 ) - R h ( 2 ) 7 9 . 6 (3) N ( 2 ) - G a ( l ) - C ( 4 ) 1 2 0 . 0 ( 5 ) Rh( 1) - C ( 3 ) - 0 ( 3 ) 1 4 0 . 4 (7) N ( 4 ) - G a ( l ) - N ( 6 ) 1 0 0 . 7 ( 3 ) R h ( 2 ) - C ( 3 ) - 0 ( 3 ) 1 4 0 . 0 (7) N ( 4 ) - G a ( l ) - C ( 4 ) 1 1 7 . 3 ( 6 ) N( 1 ) -C ( 6 ) - C ( 7 ) 1 0 9 . 6 [8) N ( 6 ) - G a ( l ) - C ( 4 ) 1 1 5 . 0 ( 5 ) C ( 6 ) - C ( 7 ) - C ( 8 ) 1 0 5 . 5 8) N ( 8 ) - G a ( 2 ) - N ( 1 0 ) 1 0 4 . 1 ( 3 ) N ( 2 ) - C ( 8 ) - C ( 7 ) 1 0 8 . 8 9) N ( 8 ) - G a ( 2 ) - N ( 1 2 ) 1 0 1 . 0 ( 3 ) N ( 3 ) - C ( 9 ) - C O 0 ) 1 0 8 . 5 11) N ( 8 ) - G a ( 2 ) - C ( 5 ) 1 1 4 . 3 ( 4 ) C ( 9 ) - C O 0 ) - C O 1) 1 0 5 . 5 10) N ( l 0 ) - G a ( 2 ) - N ( 1 2 ) 9 9 . 3 ( 3 ) N ( 4 ) - C ( n ) - C O O ) 1 1 0 . 2 10) N ( 1 0 ) - G a ( 2 ) - C ( 5 ) 1 1 5 . 3 ( 4 ) N ( 5 ) - C ( 1 2 ) - C ( 1 3 ) 1 1 0 . I l 9) N ( 1 2 ) - G a ( 2 ) - C ( 5 ) 1 2 0 . 3 ( 4 ) C ( 1 2 ) - C ( 1 3 ) - C ( 1 4 ) 103.81 9) R h ( 1 ) - N ( l ) - N ( 2 ) 1 2 2 . 5 ( 5 ) N ( 6 ) - C ( 1 4 ) - C ( 1 3 ) 109.71 9) R h ( 1 ) - N ( l ) - C ( 6 ) 1 3 0 . 5 ( 6 ) N ( 7 ) - C ( 1 5 ) - C ( 1 6 ) 111.21 10) N ( 2 ) - N ( 1 ) - C ( 6 ) 1 0 6 . 9 ( 7 ) C ( 1 5 ) - C ( 1 6 ) - C ( 1 7 ) 104.11 9) G a ( 1 ) - N ( 2 ) - N ( 1 ) 1 2 0 . 1 ( 6 ) N ( 8 ) - C ( 1 7 ) - C ( 1 6 ) 109.71 10) G a ( 1 ) - N ( 2 ) - C ( B ) 1 3 0 . 7 ( 7 ) N ( 9 ) - C ( 1 8 ) - C ( 1 9 ) 110.51 11) N ( 1 ) - N ( 2 ) - C ( 8 ) 1 0 9 . 1 ( 8 ) C(18) - C ( 1 9 ) - C ( 2 0 ) 1 0 5 . 4 9) R h ( 1 ) - N ( 3 ) - N ( 4 ) 1 2 2 . 1 ( 6 ) N ( 1 0 ) - C ( 2 0 ) - C ( 1 9 ) 1 0 9 . 9 9) R h ( 1 ) - N ( 3 ) - C ( 9 ) 1 2 9 . 4 ( 7 ) N(11) - C ( 2 1 ) - C ( 2 2 ) 1 1 0 . 6 [9) N ( 4 ) - N ( 3 ) - C ( 9 ) 1 0 8 . 5 ( 8 ) C ( 2 1 ) - C ( 2 2 ) - C ( 2 3 ) 1 0 5 . 9 [8) G a ( 1 ) - N ( 4 ) - N ( 3 ) 1 1 9 . 6 ( 6 ) N ( 1 2 ) - C ( 2 3 ) - C ( 2 2 ) 1 0 9 . 3 [9) G a d ) - N ( « ) - C ( 1 1 ) 1 3 2 . 7 ( 8 ) - 195 -APPENDIX I I I THEORETICAL INTENSITY PATTERNS FOR MASS SPECTROSCOPIC ANALYSIS 69 71 m / e 138 140 142 'm/e 185 187 m / e Ga Ga„ Re 370 372 374 m/e Re„ 254 256 258 m/e Ga^Re 

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