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UBC Theses and Dissertations

Pyrazolyl based ligands in transition metal complexes 1989

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PYRAZOLYL BASED LIGANDS IN TRANSITION METAL COMPLEXES by MICHAEL DAVID OLSON B.SC, UNIVERSITY OF BRITISH COLUMBIA, 1986 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENT FOR THE DEGREE OF MASTER OF SCIENCE i n THE FACULTY OF GRADUATE STUDIES DEPARTMENT OF CHEMISTRY We accept t h i s thesis as conforming to the required standard THE UNIVERSITY OF' BRITISH COLUMBIA SEPTEMBER, 1989 6 MICHAEL DAVID OLSON, 1989 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department The University of British Columbia Vancouver, Canada DE-6 (2/88) i l A b s t r a c t S e v e r a l u n i n e g a t i v e / m u l t i d e n t a t e p y r a z o l y l based l i g a n d s were s y n t h e s i z e d [eg. H B P Z 3 - , HBpz'^ -, MeGapz3~ / MeGapz'^ -, H2BpZ2~/ Me2Bpz2~/ Me2GapZ2~/ Me2Gapz"2~/ M e 2 G a p z ( O C H 2 C H 2 N H 2 ) M e 2 G a p z ( O C H 2 C H 2 C H = C H 2 ) " ; pz p y r a z o l y l / pz" = 3, 5 d i m e t h y l p y r a z o l y l ] . These l i g a n d s were r e a c t e d with the s t e r i c a l l y h i n d e r e d metal complex, H B p z*3MCl (M = Co, N i ; pz* = 3 - i P r - 4 - B r - p y r a z o l y l ) and the mixed-ligand t r a n s i t i o n metal complexes of g e n e r a l formulae, HBpz*3ML, were i s o l a t e d . The X-ray c r y s t a l s t r u c t u r e o f one such complex, H B p z*3Nipz"3BH was determined showing a near o c t a h e d r a l arrangement of l i g a n d s about the n i c k e l c e n t r e . The e l e c t r o n i c s p e c t r a of the n i c k e l complexes were recorded and compared t o p r e d i c t e d t r a n s i t i o n s . The e l e c t r o n i c s p e c t r a of the f o u r c o o r d i n a t e n i c k e l complex, H B p z * 3 N i C l , f i t a d 8 , t e t r a h e d r a l , l i g a n d f i e l d model. The s i x c o o r d i n a t e complexes, H B p z * 3 N i L (L = H B P Z 3 , H B p z " 3 , MeGapz3, MeGapz'^), f i t a d 8 , o c t a h e d r a l , l i g a n d f i e l d model. The unsymmetrical p y r a z o l y l g a l l a t e l i g a n d s were r e a c t e d with the rhodium dimer [ R h ( C O ) 2 C I ] 2 t o g i v e the square p l a n a r complexes, LRh(CO) [L = Me 2Gapz(OCH 2CH 2NH 2), M e 2 G a p z ( 0 C H 2 C H 2 C H = C H 2 ) ] . These rhodium[I] complexes appeared t o undergo o x i d a t i v e a d d i t i o n s of Mel, a l l y l b r o m i d e and I 2 . Furthermore these rhodium[I] complexes appeared t o b i n d the i l l s m a l l gas molecules, CO and ethene. A number of h e t e r o b i m e t a l l i c complexes, with d i r e c t metal-metal bonds, were prepared and i s o l a t e d from the r e a c t i o n o f the molybdenum anion, HBpz"3(CO)3M0 - with the t r a n s i t i o n metal h a l i d e s , [CuPPb^Cl],*,, SnF^Cl (R = Me, Ph) and GePh3Cl. i v Table of Contents Page A b s t r a c t i i Table of Contents i v L i s t of F i g u r e s x L i s t o f Tables v i i i L i s t of A b b r e v i a t i o n s x i Acknowledgement x i i i Chapter I P o l y p y r a z o l y l Based Ligands i n T r a n s i t i o n Metal Complexes 1.1 General I n t r o d u c t i o n 1 1.2 General Techniques 7 Chapter II Mixed-Ligand Metal Complexes 2.1 I n t r o d u c t i o n 10 2.2 Experimental 13 2.2.1 S t a r t i n g M a t e r i a l s 13 2.2.2 Syntheses of B i d e n t a t e Ligands a) P r e p a r a t i o n of K + [ H 2 B p z 2 ] ~ 14 b) P r e p a r a t i o n of N a + [ M e 2 B p z 2 ] ~ . 15 c) P r e p a r a t i o n of N a + [ M e 2 G a ( p z ) 2 ] ~ and N a + [ M e 2 G a ( p z " ) 2 ] " 15 2.2.3 Syntheses of Symmetrical T r i d e n t a t e Ligands a) P r e p a r a t i o n of K + [ H B p z 3 ] " and K +[HBpz"3]~ 16 V b) P r e p a r a t i o n of Na +[MeGapz3]~ and Na + [MeGapz" 3] ~ 16 2.2.4 Syntheses of Unsymmetrical G a l l a t e Ligands a) P r e p a r a t i o n of Na +[Me 2Gapz(OCH 2CH 2NH 2)]". 18 b) P r e p a r a t i o n of Na +[Me 2Gapz(OCH 2CH 2CH=CH 2)]~ 19 c) P r e p a r a t i o n o f Na +[Me 2Gapz"(OCH 2CH 2NH 2)]" 19 2.2.5 Syntheses of Mixed-Ligand Metal Complexes 20 2.3 C h a r a c t e r i z a t i o n of Mixed-Ligand Complexes 24 2.3.1 Mass Spectrometry 24 a) Mass Spectrum of HBpz*3CoCl 25 b) Mass Spectrum of HBpz*3Copz3BH 28 c) Mass Spectrum of HBpz*3Copz 2GaMe 2 30 2.3.2 X-ray C r y s t a l l o g r a p h y 32 a) The S o l i d S tate M o l e c u l a r S t r u c t u r e of HBpz* 3CoCl 33 b) The S o l i d S tate M o l e c u l a r S t r u c t u r e o f HBpz* 3Nipz"3BH 34 2.3.3 E l e c t r o n i c Spectroscopy 35 a) The T e t r a h e d a l Approximation of HBpz*3NiCl 37 b) The Octahedral Approximation of HBpz*3Nipz" 3BH 39 c) F i v e Coordinate N i c k e l [ I I ] Complexes 42 2.4 C o n c l u s i o n 44 Chapter I I I Rhodium[I] Complexes of Unsymmetrical P y r a z o l y l g a l l a t e Ligands 3.1 I n t r o d u c t i o n 48 v l 3.2 Experimental 51 3.2.1 P r e p a r a t i o n of Me 2Gapz (EA) Rh (CO) 52 3.2.2 P r e p a r a t i o n of Me 2Gapz (but) Rh (CO) 53 3.2.3 Attempted P r e p a r a t i o n of Me 2Gapz" (EA)Rh(CO) 53 3.2.4 Reactions of Rh[I] Complexes 54 a) O x i d a t i v e A d d i t i o n Reactions 54 b) A d d i t i o n Reactions 58 c) A c t i v a t i o n of Carbon-Hydrogen Bonds 59 d) Reactions of Me 2Gapz (but) Rh (CO) 61 3.3 Co n c l u s i o n s 61 Chapter IV H e t e r o b i m e t a l l i c Complexes I n c o r p o r a t i n g P y r a z o l y l b o r a t e Ligands 4.1 I n t r o d u c t i o n 64 4.2 Experimental 65 4.2.1 P r e p a r a t i o n of (MeCN) 3M0 (CO) 3 65 4.2.2 P r e p a r a t i o n of K +[(HBpz" 3)Mo(CO)3 ]" 66 4.2.3 P r e p a r a t i o n of H e t e r o b i m e t a l l i c Complexes 66 a) P r e p a r a t i o n of (HBpz" 3) (CO) 3M0CUPPI13 66 b) Attempted P r e p a r a t i o n of (HBpz" 3) (CO) 3M0CU (PPh 2) 2 C H 2 67 c) P r e p a r a t i o n of (HBpz'^) (CO)3MoSnMe3 68 d) P r e p a r a t i o n of (HBpz" 3) (CO) 3MoSnPh 3 68 e) P r e p a r a t i o n of (HBpz" 3) (CO) 3MoGePh 3 69 f) Attempted P r e p a r a t i o n of (HBpz" 3) (CO) 3MoNi (PPh 3) 2 70 v i i 4.3 D i s c u s s i o n 70 4.4 C o n c l u s i o n 74 Chapter V Summary 75 References 78 Appendix 1 C r y s t a l Grower 81 2 I s o t o p i c C l u s t e r s of B, Ga Br and C l 82 3.a X-ray S t r u c t u r a l Data of HBpz* 3CoCl 84 3.b X-ray S t r u c t u r a l Data of HBpz*3Copz3"BH.. 87 v i i i L i s t of Tables Table Page 2.1.a A n a l y t i c a l Data of HBpz*3ML (L = mono- and t r i s - c h e l a t i n g ligands) 22 2.1.b A n a l y t i c a l Data of HBpz*3ML (L = bis- c h e l a t i n g ligands) 23 2.2 Mass Spectral Assignments of HBpz* 3CoCl.... 27 2.3 Mass Spectral Assignments of HBpz* 3Copz 3BH. 29 2.4 Mass Spectral Assignments of HBpz* 3Copz 2GaMe 2 31 2.5.a UV/Vis Spectroscopic Data of Solvated HBpz* 3NiL (L = mono- and t r i s - c h e l a t i n g ligands) 36 2.5.a UV/Vis Spectroscopic Data of Solvated HBpz* 3NiL (L = bis-c h e l a t i n g ligands) 36 2.6 Calculated and Observed El e c t r o n i c Transition Energies of HBpz* 3NiCl 39 2.7 Calculated and Observed El e c t r o n i c Transitions Energies of HBpz* 3Nipz" 3BH 41 2.8 Calculated and Observed E l e c t r o n i c Transitions Energies of HBpz* 3Nipz 2BH 2 43 ix L i s t of F i g u r e s F i g u r e Page 1.1 P y r a z o l e 1 1.2 P o l y p y r a z o l y l b o r a t e Ligands 2 1.3 P o l y p y r a z o l y l g a l l a t e Ligands 9 2.1 T r i s - c h e l a t i n g P y r a z o l y l b o r a t e L i g a n d 11 2.2 HBpz*MCl 12 2.3 P r e p a r a t i o n of P o l y ( 1 - p y r a z o l y l ) Borate Ligands 14 2.4 IR Spec t r a of HOCH 2CH 2NH 2, Na +[Me 3Gapz]~ and Na +Me 3Gapz (OCH 2CH 2CH=CH 2) ] " 18 2.5 Mass Spectrum of HBpz* 3CoCl 26 2.6 S o l i d S t a t e M o l e c u l a r S t r u c t u r e of HBpz* 3CoCl 33 2.7 S o l i d S t a t e M o l e c u l a r S t r u c t u r e of HBpz* 3Nipz" 3BH 35 2.9 E l e c t r o n i c Spectrum of HBpz* 3NiCl 39 2.10 E l e c t r o n i c Spectrum of HBpz* 3Nipz" 3BH 41 2.11 UV/Vis Spe c t r a of HBpz* 3Nipz 2BH 2 i n Benzene and THF as Solv e n t s 44 3.0 O x i d a t i v e A d d i t i o n of Mel and Carbonyl I n s e r t i o n on Me 2Gapz(OCH 2CH 2NMe2)Rh(CO) 49 3.1 T r i s - C h e l a t i n g Unsymmetric P y r a z o l y l g a l l a t e Ligand 50 X 3 .2 IR Spe c t r a of [Rh(CO)2CI]2/ the r e a c t i o n mixture a f t e r a 3 hour r e f l u x and Me 2Gapz (EA)Rh(CO) 50 3.3.a P r e p a r a t i o n of Me 2Gapz(EA)Rh(CO) (Me) (I) 55 3.3.b P r e p a r a t i o n of Me 2Gapz (EA) Rh (CO) I 2 57 3.3 .C P r e p a r a t i o n of M e 2 G a p z ( E A ) R h ( C O ) ( a l l y l ) B r . . . . 57 3.3.d P r e p a r a t i o n of M e 2 G a p z ( E A ) R h ( n 3 - a l l y l ) B r 57 3.3.e Me 2Gapz (EA)Rh(CO) 2 58 3.3.f Me 2Gapz (EA)Rh(CO) (ethene) 59 3.4 Reactions of Me 2Gapz(but)Rh(CO) 4.0 3:3:1 S t r u c t u r e of MeGapz 3(CO) 3MoCuPPh 3 71 xi L i s t o f A b b r e v i a t i o n s 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 used i n t h i s t h e s i s . A Angstrom amu atomic mass u n i t B Racah parameter B.M. Bohr Magneton but but-3-enolate °C degree C e l s i u s c a l c . c a l c u l a t e d c f c o n f e r ( L a t i n : compare) cm~l r e c i p r o c a l c e n t i m e t e r s (wave numbers) Co. company C T . charge t r a n s f e r band EA ethanolamino F i g . f i g u r e g grams gr gerade Hpz p y r a z o l e i . e . i d e s t ( L a t i n : t h a t i s ) i P r i s o p r o p y l IR i n f r a r e d L p y r a z o l y l based l i g a n d M t r a n s i t i o n metal m/e mass t o charge r a t i o Me methyl xii ml m i l l i l i t r e s mmole m i l l i m o l e s nm nanometers No. number 0^ o c t a h e d r a l P parent (peak) Ph phenyl pz p y r a z o l y l pz" 3 / 5 - d i m e t h y l p y r a z o l y l pz* 3 - i s o p r o p y l - 4 - b r o m o - p y r a z o l y l t-bu t e r t i a r y b u t y l t e t r a h e d r a l 10 Dg c r y s t a l f i e l d s p l i t t i n g energy THF t e t r a h y d o f u r a n t r e n t r i e t h y l a m i n o amine u ungerade U.B.C. U n i v e r s i t y of B r i t i s h Columbia UV u l t r a v i o l e t V i s v i s i b l e V o l . Volume E e x t i n c t i o n c o e f f i c i e n t n hapto (Greek, h a p t e i n : t o fasten) n 3 t r i h a p t o n 5 pentahapto p i Ug magnetic moment $,A/#,@ foo t n o t e markers xlll Acknowledgement I would l i k e t o express my s i n c e r e thanks t o Dr. A l a n S t o r r f o r h i s guidance, wisdom and wit t h a t made t h i s p r o j e c t a s t i m u l a t i n g 2 years o f r e s e a r c h . I extend my thanks t o my very good ),£riends Tammy, Ma r t i n , Gord and Jane f o r t h e i r h e l p and t o l e r a n c e . My thanks t o the F a c u l t y and t e c h n i c a l s t a f f at U.B.C., i n p a r t i c u l a r P e t e r Borda and Steve R e t t i g f o r t h e i r d e d i c a t i o n t o e x c e l l e n c e . F i n a n c i a l support from U.B.C. Teaching A s s i s t a n t s h i p i s g r a t e f u l l y acknowledged. 1 Chapter I P o l y p y r a z o l y l Based Ligands i n T r a n s i t i o n Metal Complexes 1.1 General I n t r o d u c t i o n The v i a b i l i t y of the p o l y p y r a z o l y l b o r a t e s as a l i g a n d system began with t h e i r d i s c o v e r y i n 1966 by S. T r o f i m e n k o 1 . Since then s e v e r a l r e v i e w s 1 ' 2/3/4 a n c j ^he numerous p u b l i c a t i o n s r e f e r e n c e d t h e r e i n have demonstrated the unique c h a r a c t e r i s t i c s and v e r s a t i l i t y of these l i g a n d s . P y r a z o l e i s a f i v e membered h e t e r o c y c l i c compound ( F i g . 1.1) t h a t w i l l r e a c t with c e r t a i n compounds c o n t a i n i n g main group elements, forming m u l t i d e n t a t e , u n i n e g a t i v e l i g a n d s . H N H 2 F i g u r e 1.1 P y r a z o l e In p a r t i c u l a r the p o l y p y r a z o l y l b o r a t e l i g a n d s are of the g e n e r a l formula [ R n B p z 4 _ n ] ~ (pz = p y r a z o l y l ; n = 0-2; R = H, a l k y l , a r y l ) and can f u n c t i o n as b i d e n t a t e l i g a n d s (n = 0-2) or as t r i d e n t a t e l i g a n d s (n = 0,1) ( F i g . 1.2). F i g u r e 1.2 P o l y p y r a z o l y l b o r a t e Ligands S y m m e t r i c a l B i d e n t a t e N—N. N — N* P22 N — N* VS RoB 2 D P Z 2 S y m m e t r i c a l T r i d e n t a t e 3 These l i g a n d s g e n e r a l l y form b i s - l i g a n d complexes with f i r s t - r o w d i v a l e n t t r a n s i t i o n metals^/^. The t r i d e n t a t e l i g a n d s are u n i n e g a t i v e s i x e l e c t r o n donors and bond t o the metal through the t h r e e n i t r o g e n lone p a i r s i n a t r i p o d a l f a s h i o n . The b i d e n t a t e l i g a n d s are u n i n e g a t i v e f o u r e l e c t r o n donors t h a t form a s i x member r i n g on c o o r d i n a t i o n with the metal c e n t r e . A boat shaped (or planar) conformation i s f o r c e d on the s t r u c t u r e by the c o n s t r a i n t t h a t both the boron and metal must be simu l t a n e o u s l y coplanar with each p y r a z o l y l r i n g t o r e t a i n the resonance s t a b i l i z a t i o n energy i n each p y r a z o l y l r i n g ^ . The v e r s a t i l i t y of the l i g a n d system comes through the numerous s u b s t i t u t i o n a l p o s s i b i l i t i e s t h a t p r o v i d e means of impa r t i n g s t e r i c and e l e c t r o n i c c o n t r o l about the metal c e n t r e . S u b s t i t u t i o n s can be made on the p y r a z o l y l r i n g , the t e r m i n a l group on the boron atom can be a l t e r e d and the boron atom i t s e l f can be r e p l a c e d . An example i s a s t e r i c s t a b i l i z i n g e f f e c t brought about by methyl s u b s t i t u t i o n on the p y r a z o l y l r i n g 1 ' 7 . For example, (H2Bpz2)2 F e i s a i r - s e n s i t i v e but (H2Bpz"2)2 F e ( P z " = 3 , 5 - d i m e t h y l p y r a z o l y l ) i s a i r - s t a b l e . I t i s suggested t h a t the methyl group i n the 3 p o s i t i o n covers the metal center, p r o t e c t i n g i t from n u c l e o p h i l i c a t t a c k . B u l k i e r s u b s t i t u e n t s at the 3 p o s i t i o n of the p y r a z o l y l r i n g can l e a d t o the formation of mono-ligand complexes of the d i v a l e n t m e t a l s 8 . For example p l a c i n g a t e r t i a r y b u t y l 4 group i n the 3 p o s i t i o n g i v e s the mono-ligand c h l o r i d e complex, H B ( 3 - t - b u - p y r a z o l y l ) 3 M C I (M = C o ) 7 . Displacement of the h a l i d e from these mono l i g a n d complexes l e a v e s a s t e r i c a l l y and e l e c t r o n i c a l l y c o n t r o l l e d a c t i v e pocket. In chapter two of t h i s work the pocket of one such mono l i g a n d complex i s examined by r e a c t i o n s with l e s s s t e r i c a l l y demanding l i g a n d s and a mixed-ligand t r a n s i t i o n metal s e r i e s i s developed. E l e c t r o n i c e f f e c t s brought about by the l i g a n d systems have been demonstrated by s u b s t i t u t i o n s on the p y r a z o l y l r i n g or v a r y i n g the t e r m i n a l group. An example of t h i s e f f e c t i s seen i n the magnetic behaviour of a s e r i e s of i r o n [ I I ] complexes (at room t e m p e r a t u r e ) 2 . u B (B.M.) [pzBpz3]2Fe 0.0 diamagnetic [HBpZ3]2Fe 2.71 temperature dependent paramagnetism [HBpz"3] 2Fe 5.03 paramagnetic I r o n [ I I ] i n a d^ o c t a h e d r a l complex and would have f o u r f r e e e l e c t r o n s i n a h i g h s p i n s t r u c t u r e . A low s p i n s t r u c t u r e would have a l l e l e c t r o n s p a i r e d and t h e r e f o r e be diamagnetic. The magnetic behaviour o f these complexes i s a r e s u l t of s u b s t i t u t i o n s on the p y r a z o l y l l i g a n d . The [pzBpz3]~ l i g a n d i s a s t r o n g e r f i e l d l i g a n d than i s [HBpz3]~ as seen by the magnetic moments (u B) of t h e i r i r o n [ I I ] complexes. 5 The f o u r t h p y r a z o l y l r i n g c o n t r i b u t e s e l e c t r o n d e n s i t y toward the metal bonding o r b i t a l s of the [pzBpz3]~ l i g a n d ( i n d u c t i v e e f f e c t ) . T h i s enhanced sigma donating a b i l i t y of the [pzBpz3]~ l i g a n d i s great enough t o f o r c e the p a i r i n g of a l l the i r o n [ I I ] e l e c t r o n s and thus form a low s p i n complex. The [HBpz3]~ l i g a n d i s a s t r o n g e r f i e l d l i g a n d than i s the [HBpz'^] - l i g a n d as seen above by the magnetic moments of t h e i r i r o n [II] complexes. T h i s i s an example of where e l e c t r o n i c e f f e c t s and s t e r i c e f f e c t s can be at odds with each other. Methyl s u b s t i t u t i o n on a p y r a z o l y l r i n g would make the r i n g more b a s i c by e l e c t r o n donation of the methyl groups ( i n d u c t i v e e f f e c t ) . The s u b s t i t u t e d r i n g would then become a b e t t e r sigma donor toward a metal c e n t r e and thus a s t r o n g e r f i e l d l i g a n d . The r e v e r s e e f f e c t i s seen i n comparing the magnetic moments of [HBpz3]2Fe and [HBpz" 3]2Fe. I t i s l i k e l y t h a t s t e r i c crowding of the methyl groups of the [HBpz'^] - l i g a n d causes the l i g a n d t o c o o r d i n a t e the i r o n c e n t r e at a g r e a t e r d i s t a n c e than the [HBpz3] - l i g a n d , thus forming the h i g h s p i n complex. T h i s makes the [HBpz'^] - l i g a n d a weaker f i e l d l i g a n d than [HBpz3]~ f o r s t e r i c reasons. A f u r t h e r example of t h i s c o n f l i c t of e l e c t r o n i c and s t e r i c f a c t o r s i s the r e a c t i o n of the [MeGapz'^] - l i g a n d (borate analogue) with d i v a l e n t t r a n s i t i o n metals. The enhanced sigma donating a b i l i t y brought about by the methyl s u b s t i t u e n t s i s sometimes outweighed by the s t e r i c i n t e r a c t i o n s of the methyl groups on attempted complexation. 6 Often the l i g a n d w i l l not form t r i s - c h e l a t e d complexes with the d i v a l e n t t r a n s i t i o n metals, i n s t e a d the l i g a n d fragments and forms a dimer complex where the s u b s t i t u t e d p y r a z o l y l r i n g s b r i d g e between metal atoms 9' 1 0. Analogues of the p y r a z o l y l b o r a t e s have been made by replacement of the boron atom with a g a l l i u m atom ( F i g . 1.3). The d i f f e r e n c e i n e l e c t r o n e g a t i v i t i e s (Allred-Rochow) of g a l l i u m (1.82) and. b^oron (2.01) make the g a l l a t e l i g a n d s b e t t e r sigma donors which i s evidenced by IR measurements of analogous c a r b o n y l complexes* 1. An unsymmetrical p y r a z o l y l g a l l a t e l i g a n d system has been r e c e n t l y developed ( F i g . 1.3) t h a t has demonstrated unique c o o r d i n a t i o n behaviour i n t h a t i t may c o o r d i n a t e t o a metal c e n t r e i n e i t h e r a f a c i a l or m e r i d i o n a l manner 1 2. Furthermore these l i g a n d s have shown some promise i n forming square p l a n a r rhodium[I] complexes t h a t may have c a t a l y t i c a c t i v i t y . These l i g a n d s and t h e i r rhodium[I] complexes are d e s c r i b e d i n chapter t h r e e . The r e a c t i v i t i e s of these complexes are a l s o d e s c r i b e d . The t r i s c h e l a t i n g p y r a z o l y l b o r a t e and p y r a z o l y l g a l l a t e l i g a n d s have been used t o form the a n i o n i c complex [LMo(CO)3]~ (L = MeGapz3, HBpz3, HBpz'^). These molybdenum a n i o n i c complexes have been r e a c t e d with t r a n s i t i o n - m e t a l h a l i d e s t o form h e t e r o b i m e t a l l i c compounds with d i r e c t metal-metal bonds. The f o u r t h chapter d e s c r i b e s the s y n t h e s i s of s e v e r a l new h e t e r o b i m e t a l l i c complexes i n c o r p o r a t i n g the molybdenum anion, [HBpz'^Mo(CO)3]~. 7 1.2 General Techniques A i r s e n s i t i v e m a t e r i a l s were handled i n a dry box (Vacuum Atmospheres C o r p o r a t i o n ) . Reactions where c a r r i e d out i n the dry box or under a n i t r o g e n atmosphere. The s o l v e n t s were d r i e d by r e f l u x i n g with an a p p r o p r i a t e d r y i n g agent and c o l l e c t e d by d i s t i l l a t i o n under a n i t r o g e n b l a n k e t . The s o l v e n t s THF and hexane were r e f l u x e d with sodium metal, u s i n g benzophenone as an i n d i c a t o r . Benzene was r e f l u x e d with potassium metal. Methylene c h l o r i d e was r e f l u x e d with c a l c i u m s u l p h a t e . Methylcyanide was r e f l u x e d with phosphorous pentoxide ( P 2 O 5 ) . The d i s t i l l e d s o l v e n t s were s t o r e d i n the dry box under n i t r o g e n . A vacuum l i n e f i t t e d with a Duo Seal Vacuum Pump was r o u t i n e l y used t o dry samples and when f i t t e d with a l i q u i d n i t r o g e n c o o l e d s o l v e n t t r a p was used t o remove s o l v e n t s from r e a c t i o n mixtures. I n f r a r e d s p e c t r a were recorded u s i n g a P e r k i n Elmer 598 spectrometer and were c a l i b r a t e d u s i n g the 1601 cm - 1 band of a p o l y s t y r e n e standard. I n f r a r e d s p e c t r a where recorded u s i n g KBr s o l u t i o n c e l l s with a r e f e r e n c e c e l l c o n t a i n i n g a s o l v e n t blank or u s i n g N u j o l mulls spread between KBr windows. Mic r o a n a l y s e s were performed by Mr. P e t e r Borda of the U.B.C. M i c r o a n a l y t i c a l S e r v i c e s u s i n g a C a r l o Erba Elemental A n a l y s e r . 8 Mass s p e c t r a were recorded by the U.B.C. Mass Spectrometry S e r v i c e s u s i n g a Kratos MS50 mass spectrometer. I o n i z a t i o n of compounds was done by e l e c t r o n impact. X-ray s t u c t u r e s were determined by Dr. S.J. R e t t i g of t h i s department u s i n g a Rigaku s i n g l e c r y s t a l X-ray d i f f r a c t o m e t e r . UV/Vis s p e c t r a were recorded with a Shimadzu UV-2100 spectrometer and n e a r - i n f r a r e d s p e c t r a w i t h a Cary 14 spectrometer. Figure 1.3 Polypyrazolylgallate Ligands 9 Symmetrical Bidentate Me 2 Ga / \ N-NP Me 2 Gapz 2 Symmetrical Tridentate Me—G Me 2 Ga / N-N' Me 2Gapz2 MeGapzg Unsymmetrical Tridentate MeGapzg Me2G Me2Gi 10 Chapter II Mixed Ligand Complexes 2.1 I n t r o d u c t i o n One of the b a s i c p r e c e p t s i n d e s i g n i n g a l i g a n d system i s t o impart s t e r i c and e l e c t r o n i c p r o p e r t i e s t o the r e a c t i v e s i t e of the t r a n s i t i o n metal such t h a t i t may produce s e l e c t i v e and c o n s i s t e n t r e a c t i v i t y . The u l t i m a t e m a n i f e s t a t i o n of t h i s p r i n c i p l e i s demonstrated t o us by the r e a c t i v e s i t e s on enzymes. These s i t e s are very n e a r l y p e r f e c t i n t h e i r s e l e c t i v i t y and r e a c t i v i t y t o a p a r t i c u l a r s u b s t r a t e . T h i s i s accomplished by the enzyme through i d e a l s t e r i c and n u c l e o p h i l i c c o n d i t i o n s and s u b t l e c o n f o r m a t i o n a l changes i n the surrounding organo-mass. Mimicking these s e l e c t i v e pockets i s one of the goals of o r g a n o m e t a l l i c chemistry. The d i s c o v e r y of new and more i n t r i c a t e t r i s - c h e l a t i n g p y r a z o l y l b o r a t e s i s p r o v i d i n g new inroads i n t o t h i s type of chemistry. In these l i g a n d systems the 3 p o s i t i o n on the p y r a z o l y l r i n g i s the most s t e r i c a l l y i n f l u e n t i a l s i t e about the metal c e n t e r ( F i g . 2.1). Ligands with H or Me i n t h i s p o s i t i o n r e a d i l y form b i s - l i g a n d complexes with d i v a l e n t t r a n s i t i o n metals. However, when a bulky group such as the t e r t i a r y 11 F i g u r e 2.1 T r i s - c h e l a t i n g P y r a z o l y l b o r a t e Ligand b u t y l group i s i n the 3 p o s i t i o n only the mono l i g a n d complex w i l l form. Presumably t h i s i s due t o s t e r i c hinderance by the t e r t i a r y b u t y l group around the m e t a l 1 3 . Trofimenko has designed, what he has c a l l e d , i n t e r m e d i a t e l i g a n d s by p l a c i n g an i s o p r o p y l group i n the 3 p o s i t i o n . These l i g a n d s are s t e r i c a l l y r e s t r i c t e d , but form a b i s - l i g a n d complex with a p e c u l i a r 1,2 b o r o t r o p i c s h i f t 1 4 . 2 H B ( 3 - i P r p z ) 3 ~ + C o 2 + — > [ H B ( 3 - i P r p z ) 2 ( 5 - i P r p z ) ] 2 C o T h i s rearrangement of the p y r a z o l y l r i n g s suggests t h a t the i n t e r m e d i a t e l i g a n d has c r e a t e d a s t e r i c a l l y c o n t r o l l e d a c t i v e pocket around the metal c e n t r e . In an e f f o r t t o examine the a c t i v e pocket c r e a t e d by 12 the i n t e r m e d i a t e l i g a n d [HBpz*3]~ (pz* = 3-iPr-4Br- p y r a z o l y l ) the complex HBpz*3 MCI ( F i g . 2.2) was r e a c t e d w i t h s t e r i c a l l y s m a l l e r p y r a z o l y l b o r a t e and p y r a z o l y l g a l l a t e l i g a n d s ( F i g . 1.2, 1.3) t o produce a s e r i e s o f mixed-ligand metal complexes. F i g u r e 2.2 HBpz* 3MCl (M = Co, Ni) In t h i s chapter the syntheses of the s m a l l e r p y r a z o l y l based l i g a n d s , the syntheses of the mix e d - l i g a n d metal complexes and the c h a r a c t e r i z a t i o n s o f these complexes i s d e s c r i b e d . The s e r i e s i n c l u d e s 4, 5 and 6 c o o r d i n a t e mixed- l i g a n d metal complexes and r e p r e s e n t a t i v e complexes from each c o o r d i n a t i o n mode are g i v e n as examples i n the c h a r a c t e r i z a t i o n s t u d i e s . The complete s e r i e s i s l i s t e d i n Tables 2 . 1 .a and 2.1.b on pages 22 and 23 . . A UV/Vis study was performed on the mixed-ligand n i c k e l s e r i e s t o f u r t h e r c h a r a c t e r i z e the complexes. The t r a n s i t i o n Br 13 e n e r g i e s c a l c u l a t e d from the recorded s p e c t r a were compared with p r e d i c t e d e n e r g i e s from h i g h symmetry models f o r each p a r t i c u l a r c o o r d i n a t i o n number. 2.2 Experimental 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 (Hpz) and 3,5-dimethylpyrazole (Hpz") were obt a i n e d from K and K L a b o r a t o r i e s and were used as s u p p l i e d without f u r t h e r p u r i f i c a t i o n . L i t e r a t u r e methods were used t o prepare Me3Ga 1^, M e G a C l 2 1 6 and N a p z 1 7 . The bulky l i g a n d metal complexes, HB(3-iPr-4Br- p y r a z o l y l ) 3 MCI (M = Ni,Co) were s u p p l i e d by S. Trofimenko. The complexes were prepared by r e a c t i n g an excess of the metal c h l o r i d e with the borate l i g a n d 1 4 . A c r y s t a l s t r u c t u r e of the c o b a l t complex was determined. 14 2.2.2 Syntheses of Bidentate Liaands 2.2.2a Preparation of K+fH 2BPz 2 1- 1 8 K +BH 4" + 2 Hpz > K + [ H 2 B p z 2 ] ~ + 2 H 2 102 °C This ligand was previously prepared by the above scheme. The extent of pyrazole incorporation i s dependent on the temperature of the reaction as seen below (Fig. 2.3.). The poly(1-pyrazolyl) borates are a l l a i r - s t a b l e and moisture-stable, white s o l i d s . BH 4" + 2pzH -2H : ~ 1 0 2 ° ' - 2 2 0 * X ~ieo-| P z H 1~H* Figure 2.3 Preparation of Poly(1-pyrazolyl) Borate Ligands 15 2,2.2b Preparation of Na+TMe2Bpz2l~ 6 Me3B + Napz > Na +[Me 3Bpz]~ Na +[Me 3Bpz]~ + Hpz > Na +[Me 2Bpz 2]" + MeH This compound had been previously prepared by the above scheme. Quantities required were weighed out and dissolved i n THF. 2.2.2c Preparation of Na+TMe2Ga (pz) 2"! ~ and Na + TMe 2Ga(PZ")ol~ 6 NaH + Hpz > Napz + H 2 Me 3Ga + Napz > Na + [Me 3Gapz]~ Na + [Me 3Gapz]" + Hpz ~ — > Na +[Me 2Gapz 2]~ + MeH To 150 ml of THF i n a round bottom f l a s k were added molar equivalents of GaMe3 (1.510 g; 13.17 mmole) and Napz (1.185 g; 13.17 mmole). The mixture was s t i r r e d overnight. The r e s u l t i n g solution was made up to a known volume with THF and stored under a nitrogen atmosphere. A 25 ml aliquot of the solution of Na +[Me 3Gapz]~ (2.63 mmole) was mixed with a 1:1 molar r a t i o of Hpz (0.179 g; 2.63 mmole) and refluxed under a nitrogen atmosphere. The 16 r e a c t i o n proceeded with the e v o l u t i o n of methane and was monitored by the disappearance of the p y r a z o l e N-H s t r e t c h at 3300 cm - 1 i n the IR spectrum. The mixture was then made up t o a known volume with THF. [Me2Gapz"2]~ was prepared i n a l i k e manner. An a l i q u o t of Na +[Me3Gapz"]~ was mixed with a 1:1 s t o i c h i o m e t r i c amount of 3,5-dimethyl p y r a z o l e (0.533 g; 5.55 mmole) and r e f l u x e d under n i t r o g e n . On completion of the r e a c t i o n the mixture was made up to a known volume with THF. 2.2.3 Syntheses of Symmetrical T r i d e n t a t e Ligands 2.2.3a P r e p a r a t i o n of K + r H B p z 3 l ~ and K + r H B p z " 3 l ~ 7 K + B H 4 " + 3 Hpz > K + [ H B p z 3 ] ~ + 3 H 2 180 °C T h i s l i g a n d and the t r i s ( 3 , 5-dimethylpyrazolyl) analog were p r e v i o u s l y prepared by the above scheme. The temperature of r e a c t i o n determines the number of p y r a z o l y l r i n g s bonding t o the boron atom ( F i g . 2.3) 17 2.2.3b P r e p a r a t i o n of Na +rMeGapz 3l~ and Na + r M e G a p z " 3 l " 1 1 MeGaCl 2 + 3 Napz > Na +[MeGapz 3]" + 2 NaCl A molar e q u i v a l e n t of MeGaCl2 (2.28 mmole) i n THF, was added t o a 3 molar e q u i v a l e n t of Napz (1.85 g; 6.85 mmole) d i s s o l v e d i n 30 ml of THF. The r e a c t i o n mixture was s t i r r e d f o r one week under a n i t r o g e n atmosphere. The r e s u l t i n g s o l u t i o n was made up t o a known volume by a d d i t i o n of THF. The 3 , 5 - d i m e t h y l p y r a z o l y l analog was prepared i n a s i m i l a r manner by the r e a c t i o n of t h r e e molar e q u i v a l e n t s of Napz" (0.971 g; 2.74 mmole) with a molar e q u i v a l e n t of MeGaCl2 (0.913 mmole). Both l i g a n d s were s t o r e d as s o l u t i o n s under a n i t r o g e n atmosphere. The a l k a l i metal s a l t s of the p o l y ( 1 - p y r a z o l y l ) g a l l a t e anions can be i s o l a t e d as white s o l i d s but are hyg r o s c o p i c ( u n l i k e the bora t e analogues). 18 2.2.4 Syntheses of Unsymmetrical G a l l a t e Ligands 2.2.4a P r e p a r a t i o n of Na+ TMe2Gapz ( O C H o C ^ N r ^ ) 1 " 1 2 Na +[Me 3Gapz]" + HOCH 2CH 2NH 2 — > Na +[Me 2Gapz(OCH 2CH 2NH 2)]~ r e f l u x + MeH To a THF s o l u t i o n o f Na +[Me 3Gapz]~ (5.10 mmole) was added a molar e q u i v a l e n t of ethanolamine (0.311 g; 5.10 mmole). The mixture was r e f l u x e d f o r 40 hours u n t i l the O-H s t r e t c h of the a l c o h o l at 3480 cm - 1 i n the IR spectrum disappeared. A peak at 570 cm - 1 which grew d u r i n g the course of the r e a c t i o n was a t t r i b u t e d t o a Ga-0 s t r e t c h and p r o v i d e d a good monitor f o r the r e a c t i o n p r o g r e s s as w e l l ( F i g . 2 . 4 ) . The r e s u l t a n t mixture was then made up t o a known volume by a d d i t i o n of THF and s t o r e d under a n i t r o g e n b l a n k e t . 4 0 0 0 {cm'1) 5 0 0 F i g u r e 2 . 4 IR S p e c t r a of HOCH 2CH 2NH 2 / Na +[Me 3Gapz]" and Na +Me 2Gapz(OCH 2CH 2NH 2)~ 19 2.2.4b P r e p a r a t i o n of Na+FMe?Gapz(OCH?CH?CH=CH?)1 - 19 Na +[Me 3Gapz]" > Na +[Me 2Gapz(OCH 2CH 2CH=CH2)]" + HOCH 2CH 2CH=CH 2 r e f l u x + MeH To a THF s o l u t i o n of N a + [Me 3Gapz] ~ (5.10 nunoles) was added a molar e q u i v a l e n t of but-3-enol (0.368 g; 5.10 mmoles) and the mixture was r e f l u x e d f o r 40 hours. The r e a c t i o n was complete when the O-H s t r e t c h of the a l c o h o l at 3470 cm - 1 i n the IR spectrum disappeared. The s o l u t i o n was then made up to a known volume with THF and s t o r e d under a n i t r o g e n b l a n k e t . 2.2.4c P r e p a r a t i o n of Na +fMe 2Gapz"(OCH 2CH 2NH 2)1~ Me 3Ga + Napz" > Na +[Me 3Gapz"]~ N a + [ M e 3 G a p z n ] " + HOCH 2CH 2NH 2 > Na +[Me 2Gapz"(OCH 2CH 2NH 2)]" r e f l u x + MeH To a THF s o l u t i o n of Me 3Ga (27.8 mmole) was added a molar e q u i v a l e n t of Napz" (3.28 g; 27.8 mmole). T h i s mixture was s t i r r e d o v e r n i g h t and then made up t o a known volume by the a d d i t i o n of THF. A 50 ml a l i q u o t of t h i s s o l u t i o n was r e a c t e d with a molar e q u i v a l e n t of ethanolamine and r e f l u x e d f o r 24 hours. The l o s s of the O-H band of the a l c o h o l i n the IR spectrum 20 s i g n a l l e d the completion of the r e a c t i o n . T h i s mixture was then made up to a known volume with THF. 2.2.5 Syntheses of Mixed-Ligand Metal Complexes HBpz* 3MCl + NaL > HBpz* 3ML + NaCl (M = N i , Co; pz* = 3 - i P r - 4 B r - p y r a z o l y l ) [L = HBpz 3, HBpz" 3, MeGapz 3, MeGapz" 3, H 2 B P Z 2 / M e 2 B p z 2 / Me 2Gapz 2, Me 2Gapz" 2/ Me 2Gapz(OCH 2CH 2 N H 2 ) , Me 2Gapz(OCH 2CH 2CH=CH 2)] The g e n e r a l r e a c t i o n procedure was t o p l a c e an a l i q u o t of a THF s o l u t i o n of the l e s s s t e r i c a l l y bulky l i g a n d (NaL) i n t o a round bottom f l a s k and begin s t i r r i n g . A molar e q u i v a l e n t of the bulky l i g a n d metal c h l o r i d e complex (HBpz* 3MCl) d i s s o l v e d i n THF was then added dropwise. The s o l u t i o n was s t i r r e d f o r a minimum of 24 hours under a n i t r o g e n atmosphere. The r e a c t i o n s o l v e n t (THF) was then removed under vacuum t o a c o l d t r a p . The f o l l o w i n g procedures were used u n t i l a s a t i s f a c t o r y m i c r o a n a l y s i s was obtained. 1) The r e a c t i o n product was r e d i s s o l v e d i n benzene and the mixture f i l t e r e d . The benzene was allowed t o evaporate slo w l y t o promote c r y s t a l growth. 2) The r e a c t i o n product was r e d i s s o l v e d i n 30 ml methylene c h l o r i d e , f i l t e r e d and 15 ml of hexane was added. The 21 s o l v e n t was evaporated s l o w l y t o promote c r y s t a l growth. 3) The r e a c t i o n product was d r i e d under vacuum at 70 °C. 4) The r e a c t i o n product was sublimed. Most complexes appeared t o be q u i t e robust and sublimed at 220-250 °C under vacuum, but t h e r e were i m p u r i t i e s t h a t a l s o sublimed. 5) A s o l v e n t e x t r a c t i o n with 50:50 methylene c h l o r i d e / w a t e r was performed on the r e a c t i o n product. Three washings would be done and the compound would then be d r i e d on the vacuum l i n e at 7 0 °C. T h i s method seemed to g i v e the most s a t i s f a c t o r y r e s u l t s and i t i s recommended f o r f u t u r e work t h a t t h i s be the f i r s t method t r i e d . 6) The r e a c t i o n product was p l a c e d i n a c r y s t a l grower. The c r y s t a l grower i s shown i n appendix 1. The compound was p l a c e d i n one of the tubes and the apparatus a t t a c h e d t o the vacuum l i n e . The grower was evacuated and methylene c h l o r i d e (or any other s u i t a b l e solvent) was condensed i n t o the tube. The tube was then flame s e a l e d at the c o n s t r i c t i o n n e a r e s t the vacuum l i n e attachment thus making a s e a l e d c r y s t a l growth environment. The c o n c e n t r a t i o n of s o l u t e c o u l d be c o n t r o l l e d by condensing s o l v e n t i n t o the other f i n g e r . I f c r y s t a l s grew the s o l v e n t would be decanted i n t o t h i s same f i n g e r . The c r y s t a l s would be removed by f r e e z i n g the s o l v e n t , flame s e a l i n g at the next c o n s t r i c t i o n and removal t o the glove box. P e r t i n e n t data of the m i x e d - l i g a n d metal complexes i s c o l l e c t e d i n Tables 2.1.a and 2.1.b and the p u r i f i c a t i o n method t h a t gave s a t i s f a c t o r y a n a l y s i s i s i n d i c a t e d . 22 Table 2.1.a A n a l y t i c a l Data of HBpz*3ML ( L = mono- and t r i s - c h e l a t i n g l i g a n d s ) L Metal C o l o r Mass$ Mic r o a n a l y s e s P u r i f i c a t i o n (amu) C H N Method* CI N i Co HBpz 3 N i Co HBpz"3 N i Co MeGapz3 Ni Co MeGapz"3 N i •1.0 CH 2C1 2 CO 671 r e d 670 blue 671 848 p u r p l e 847 orange 84 8 932 p u r p l e 931 orange 932 921 b l u e 920 orange 921 1005 green 1004 orange 1005 32.26 3 .76 32.20 3.81 32.48 3.83 38.26 4 .16 38.54 4.17 38.50 4.18 42.53 5.08 43.10 5.15 42.54 5.20 36.53 4 .05 36.94 4.07 36.39 4.16 40.64 4 .91 41.00 5.09 38.56 4 .71 38.36 4.67 12.54* 12.43 12.55 19.83 20.02 5 20.18 5 18.04 17.89 1 18.04 4 18.26 18.50 1 18.05 2 16.73 16.61 5 15.42 15.24 5 # Numbers i n b o l d type are expected v a l u e s . Cobalt and n i c k e l atomic weights d i f f e r by only 0.22 g/mole t h e r e f o r e t h e i r expected microanalyses are very n e a r l y i d e n t i c a l . $ Expected mass was c a l c u l a t e d from average molecular weights ( n a t u r a l i s o t o p e abundance). The one mass u n i t d i f f e r e n c e observed i n the s p e c t r a i s due t o the most abundant n i c k e l i s o t o p e at mass 58 (68%) c f . c o b a l t at mass 59 (100 % ) . * Refer t o pages 20-21. 23 Table 2.1.b A n a l y t i c a l Data of HBpz*3ML ( L = b i s - c h e l a t i n g l i g a n d s ) L Metal C o l o r Mass$ Mi c r o a n a l y s e s P u r i f i c a t i o n (amu) C H N Method H2BPZ2 782 36 .88 4 .26 17 .92* N i b l u e 780 36 .83 4 .25 17 .70 5 Co p u r p l e 781 37 .18 4 .22 17 .75 5 Me2Bpz2 810 38 .57 4 .61 17 .30 N i r e d 794 38 .89 4 .57 16 .98 1 •0.5 CH 2C1 2 37 .20 4 .49 16 .41 Co p u r p l e 795 37 .37 4 .37 15 .62 Me2Gapz2 869 35 .95 4 .29 16 .13 Ni b l u e 853 36 .01 4 .20 16 .16 3 Co re d 854 36 .28 4 .20 15 .45 5 Me 2Gapz "2 * 0.5 CH 2C1 2 925 37 .87 4 .79 14 .48 N i green 909 38 .16 4 .83 14 .20 3 Co p u r p l e 910 37 . 60 4 . 69 14 .88 5 Me2Gapz(EA) 862 34 .84 4 .68 14 .63 N i b l u e 34 .60 4 .26 14 .10 3 Co r e d 34 .96 4 .28 14 .10 3 Me 2Gapz"(EA) 890 36 .44 4 .98 14 .17 N i green 874 34 .88 4 .99 13 .61 Co p u r p l e 875 36 .61 4 .98 13 .93 3 # Numbers i n b o l d type are expected v a l u e s . Cobalt and n i c k e l atomic weights d i f f e r by only 0.22 g/mole t h e r e f o r e t h e i r expected microanalyses are very n e a r l y i d e n t i c a l . $ Expected mass was c a l c u l a t e d from average molecular weights ( n a t u r a l i s o t o p e abundance). The one mass u n i t d i f f e r e n c e observed i n the s p e c t r a i s due t o the most abundant n i c k e l i s o t o p e at mass 58 (68%) c f . c o b a l t at mass 59 (100 % ) . 24 2.3 C h a r a c t e r i z a t i o n of Mixed Ligand Complexes 2.3.1 Mass Spectrometry Mass spectrometry was used t o c o n f i r m the molecular weight of each compound. A l l samples were a n a l y t i c a l l y pure and were i o n i z e d by e l e c t r o n impact. In most cases parent peaks [ P ] + were observed. Complexes with t e r m i n a l methyl v groups on the boron or g a l l i u m atom e a s i l y l o s t a methyl group and peaks at [P-15] + were observed. I s o t o p i c p a t t e r n s were used t o i d e n t i f y a l a r g e number of fragments. The numbers r e p o r t e d always r e f e r t o the most i n t e n s e mass to charge r a t i o (m/e) peak i n any g i v e n i s o t o p i c p a t t e r n . T h i s peak r e s u l t s from the most probable combination of i s o t o p e s i n t h a t p a r t i c u l a r fragment. These fragments c o n t a i n e d at l e a s t one of boron, g a l l i u m , bromine or c h l o r i n e , a l l of which have n a t u r a l i s o t o p e s . The i s o t o p i c p a t t e r n s of these atoms and s e v e r a l combinations of them are shown i n appendix 2. The s p e c t r a of the c o b a l t complexes were s e l e c t e d as examples because c o b a l t has only one n a t u r a l i s o t o p e [58 (100%)] where n i c k e l has f i v e [ 58 (67.9%), 60 (26.2%), 61 (1.2%), 62 (3.7%) and 64 ( 1 . 1 % ) ] . The i s o t o p i c p a t t e r n s of the c o b a l t complexes were l e s s c omplicated and t h e r e f o r e e a s i e r t o r e c o n c i l e . The mass spectrum of HBpz*3CoCl i s g i v e n as an example i n F i g u r e 2.5. 25 2.3.1a Mass Spectrum of HBpz*3CoCl The HBpz 3 C 0 C I parent peak was seen at mass/charge (m/e) 671 ( F i g . 2.5). Loss of HC1 gave the most i n t e n s e peak at m/e 633. There was an i n t e r e s t i n g recombination corre s p o n d i n g t o the exchange of a bromide l i g a n d with a c h l o r i d e l i g a n d on the parent molecule t h a t gave the i o n [HBpz* 3CoBr] + at m/e 715. Loss of Hpz* from the d e - c h l o r i n a t e d parent molecule gave [Bpz*2Co] + at m/e 445. T h i s peak and the peak at m/e 633 were seen i n the s p e c t r a of most of the mixed-ligand metal complexes. I t seemed l i k e l y another pz* moiety would have s t r i p p e d o f f but t h i s was not observed. Doubly charged s p e c i e s of the m/e 633 and 446 fragments were seen at m/e 317 and 223 , r e s p e c t i v e l y . S i n g l e i s o p r o p y l groups and s i n g l e bromides were removed from [ B p z * 3 C o ] + g i v i n g fragments at m/e 592 and 553, and [Bpz*2Co] + g i v i n g fragments at m/e 404 and 366. Other important fragments were the [Hpz*B] + at m/e 199, [ H p z * ] + at m/e 188, [Hpz*-Me] + at m/e 173, [ p z ] + at m/e 66 and [ i - P r ] + at m/e 43. Some fragments under m/e 200 were due t o r i n g opening of [ p z * B ] + . There are e x t e n s i v e rearrangement p o s s i b i l i t i e s o f borate and g a l l a t e complexes 2^ which accounted f o r the l a r g e number of peaks i n t h i s r e g i o n . Assignments of the other peaks are shown i n t a b l e 2.2. 26 Mass Spectrum of HBpz*3CoCl 27 Table 2.2 Mass S p e c t r a l Assignments of HBpz* 3CoCl m/e I n t e n s i t y Assignment 715 50 [HBpz* 3CoBr] + 671 35 [ H B p z * 3 C o C l ] + 633 100 [ B p z * 3 C o ] + 592 <5 [HBpz* 2Co(4-Br-pz)] + 589 10 [ H B p z * 2 C o ( 3 - i P r - p z ) C l ] + 553 15 [ B p z * 2 C o ( 3 - i P r - p z ) ] + 526 15 [ B p z * 2 C o B r ] + 482 20 [ B p z * 2 C o C l ] + 445 100 [ B p z * 2 C o ] + 404 15 [HBpz*Co(4-Br-pz)] + 366 15 [HBpz*Co ( 3 - i P r - p z ) ] + 317 10 m = 633/ e = 2 223 10 m = 446; e = 2 199 10 [Hpz*B] + 188 10 [ H p z * ] + 173 5 [Hpz* - M e ] + 158 <5 [Hpz* - M e 2 ] + 132 5 [BrCCCHN] + 119 5 [ ( 3 - i P r p z ) B ] + 92 10 [ p z C C H 3 ] + 80 5 [ p z C H 3 ] + 66 5 [ H p z ] + 55 5 [ i P r C ] + 43 15 [ i P r ] + 28 2.3.1b Mass Spectrum of HBpz*3Copz 3BH The mass spectrum of HBpz*3Copz3BH showed a low i n t e n s i t y parent peak at m/e 848. The peaks at m/e 633 and 445 corresponding t o the [HBpz*3Co] + and [HBpz*2Co] + fragments (as seen i n the p r e v i o u s spectrum) were not seen at a l l . Low i n t e n s i t y peaks were seen f o r fragments corresponding t o the l o s s of pz and pz* from the parent at m/e 780 and 659 r e s p e c t i v e l y . A fragment corresponding t o the l o s s of both pz and pz* from the parent molecule was seen at m/e 580. The major peak observed was the [BPZ3C0] + fragment at m/e 271. T h i s i n d i c a t e d t h a t the [HBpz3]~ l i g a n d formed the s t u r d i e r bond t o the c o b a l t c e n t r e than d i d the [HBpz*3]~ l i g a n d . Loss of pz from [Bpz3Co] + gave the [Bpz2Co] + fragment at m/e 203. There were recombinations of [BPZ3C0] and [BPZ2C0] with the l i g a n d fragments [HBPZ3] and [Bpz2l• The ions produced were of r e l a t i v e l y h i g h i n t e n s i t y c o r r e s p o n d i n g t o [HBPZ3C0PZ3B]+ at m/e 484/ [HBPZ3C0PZ2B]+ at m/e 417 and [(Bpz2)2^o] + at m/e 348. T h i s same phenomenon was observed i n the mass s p e c t r a of the HBpz*3Copz"3BH and HBpz*3Copz3GaMe complexes. A l l of the other complexes l i s t e d i n t a b l e s 2.1.a and 2.1.b d i s p l a y e d mass s p e c t r a more s i m i l a r t o t h a t of the s t a r t i n g compound, HBpz*3CoCl/ su g g e s t i n g the HBpz*3 l i g a n d formed the s t u r d i e r bond t o the c o b a l t c e n t r e i n those complexes. Table 2.3 Mass S p e c t r a l Assignments of HBpz*3Copz3BH m/e I n t e n s i t y Assignment 848 <5 [HBpz* 3Copz 3BH] + 780 <5 [HBpz* 3Copz 2B] + 659 <5 [Bpz* 2Copz 3BH] + 580 <5 [ B p z * 2 C o p z 2 ] + 484 70 [HB p z 3 C o p z 3 B ] + 417 65 [HB p z 3 C o p z 2 B ] + 348 25 [ ( B p z 2 ) 2 C o ] + 271 100 [ B p z 3 C o ] + 262 30 [MeCopz*H] + 203 80 [ B p z 2 C o ] + 188 25 [ p z * ] + 173 85 [pz*-Me] + 94 95 m = 188, e = 2 78 30 [HpzC] + 68 45 [H p z ] + 43 45 [ i P r ] + 41 45 [NNCH] + 30 2.3.1c Mass Spectrum of HBpz*3Cop_z2GaMe2 The parent peak of HBpz*3Copz2GaMe2 was seen as a t r a c e i n the spectrum at m/e 869. The major peak was observed at m/e 854 c o r r e s p o n d i n g t o the l o s s of a methyl group from the parent molecule. T h i s was observed i n a l l of the complexes i n c o r p o r a t i n g the dimethyl b i s - c h e l a t i n g l i g a n d s . The mass spectrum of HBpz*3Cop'Z2GaMe2 has a s i m i l a r fragmention p a t t e r n as t h a t seen i n mass spectrum of the s t a r t i n g compound, HBpz 3C0CI. In p a r t i c u l a r the peaks at m/e 633 and 445 c o r r e s p o n d i n g t o the fragments [Bpz*3Co] + and [ C o p z * 2 B H ] + r e s p e c t i v e l y were of h i g h i n t e n s i t y i n both s p e c t r a . These peaks were absent i n the mass spectrum of HBpz*3Copz3BH. The i n t r o d u c t i o n of g a l l i u m i n t o the complexes produced new i s o t o p i c p a t t e r n s t h a t helped t o i d e n t i f y the fragments. The fragment assignments are made i n t a b l e 2.4. Of p a r t i c u l a r i n t e r e s t were the recombinations at h i g h molecular weights. The complex at m/e 854, c o r r e s p o n d i n g t o the fragment, [HBpz*3Copz2GaMe] + p i c k e d up a pz moiety t h a t gave the t r i s - c h e l a t e d [HBpz*3Copz3GaMe] + i o n at m/e 921. Another recombination was seen at m/e 974 which was a t t r i b u t e d t o the replacement of pz by pz* i n the fragment, [HBpz*3Copz2GaMe] + t o g i v e the i o n [HBpz*3Copz(pz*)GaMe] +. There appears t o be d i m e r i z a t i o n of some of the sma l l m olecular weight g a l l i u m fragments. For example the peak at m/e 251 i s c o n s i s t e n t with [Me2GapzGaMe] +. 31 Table 2.4 Mass S p e c t r a l Assignments of HBpz*3Copz2GaMe2 m/e I n t e n s i t y Assignment 974 20 [HBpz* 3Copz 2pz*GaMe 2] + 921 5 [HBpz* 3Copz 3GaMe] + 869 <5 [HBpz* 3Copz 2GaMe 2] + 854 45 [HBpz* 3Copz 2GaMe] + 786 25 [Bpz* 3CopzGaMe] + 715 5 [Bpz* 3Copz 2Me] + 680 15 [Bpz*2Copz 2GaMe 2] + 664 100 [Bpz* 2Copz 2GaMe] + 633 25 [ B p z * 3 C o ] + 620 5 [Bpz*(4-Br-pz)Copz2GaMe] + 586 20 [ p z * 2 C o P z G a M e ] + 514 20 [HBpz* 2Copz] + 466 30 [pz*Copz2GaMe] + 445 30 [Copz* 2BH] + 419 15 [HBpz*pz 2GaMe] + 392 20 [pz*pz2Ga] + 358 20 [BrCopz 2GaMe] + 332 25 m = 664 e = 2 251 10 [MeGapzGaMe 2] + 205 10 [ G a p z 2 ] + 190 5 [Hpz*B] + 188 5 [H p z * ] + continued 32 Table 2.4 continued 173 10 [Hpz*-Me] + 151 10 [MeGapz] + 99 15 [GaMe 2] + 94 10 m = 188 e 79/81 <5 [Br] + 78 5 [ B p z ] + 69/71 15 [Ga] + 68 20 [H p z ] + 55 10 [ i P r C ] + 43 10 [i P r ] + 41 15 [NNCH] + 2.3.2 X-ray C r y s t a l l o g r a p h y S e v e r a l c r y s t a l growth techniques were attempted as d e s c r i b e d i n the experimental s e c t i o n of t h i s chapter. The f o u r c o o r d i n a t e s t a r t i n g compounds were r e c r y s t a l l i z e d from benzene. A s u i t a b l e s i n g l e c r y s t a l o f HBpz*3CoCl was grown and the X-ray c r y s t a l s t r u c t u r e was determined. The f i v e c o o r d i n a t e complexes i n i t i a l l y gave a v i s c o u s m a t e r i a l t h a t c o u l d be d r i e d by h e a t i n g t o 70 °C under vacuum. These d r i e d compounds were not h y g r o s c o p i c but would r a p i d l y p i c k up o r g a n i c s o l v e n t s from the glove box atmosphere t o become v i s c o u s a g a i n . S e v e r a l of the s i x c o o r d i n a t e complexes 33 e f f l o r e s c e d once the s o l v e n t had been removed. Presumably the s o l v e n t was i n t r i n s i c t o the c r y s t a l l a t t i c e but was weakly bound. A s u i t a b l e s i n g l e c r y s t a l of HBpz*3Nipz"3BH was grown from CH2CI2 i n the c r y s t a l growing apparatus and the X-ray c r y s t a l s t r u c t u r e was determined. 2.3.2a The S o l i d S t a t e M o l e c u l a r S t r u c t u r e o f HBpz*3CoCl The c o b a l t [ I I ] c e n t r e i n HBpz* 3CoCl ( F i g . 2.6) i s c o o r d i n a t e d by t h r e e p y r a z o l y l n i t r o g e n s from the t r i s - c h e l a t i n g l i g a n d and one c h l o r i d e l i g a n d . The mean Co-N bond l e n g t h i s 2.045(7) A and the average N-Co-N bond angle i s 94.4(3)°. Comparing these data w i t h the Co-Cl bond d i s t a n c e of 2.207(3) A and average N-Co-Cl bond angle of 122.1(3)°, i t i s c l e a r t h a t the t h r e e n i t r o g e n s form the base of a t r i g o n a l pyramidal s t r u c t u r e with the c h l o r i d e at the apex. F i g u r e 2.6 S o l i d S t a t e M o l e c u l a r S t r u c t u r e of HBpz* 3CoCl 34 T h i s s t r u c t u r e then has C 3 V symmetry with the 3 - f o l d a x i s along the Co-Cl bond. The i s o p r o p y l groups at the 3 p o s i t i o n are arranged such t h a t the two methyl groups are bent toward the metal c e n t r e . A s t e r e o s c o p i c view of the s t r u c t u r e , c r y s t a l l o g r a p h i c parameters and bond le n g t h s and angles are i n appendix 3.a. 2.3.2b The S o l i d S t a t e M o l e c u l a r S t r u c t u r e of H B P Z * 3 N J P Z " 3 B H The n i c k e l [ I I ] c e n t r e o f HBpz* 3Nipz" 3BH ( F i g . 2.7) i s c o o r d i n a t e d by s i x p y r a z o l y l n i t r o g e n s . The t h r e e n i t r o g e n s c o o r d i n a t i n g the n i c k e l from the HBpz" 3 l i g a n d have mean N i - N bond l e n g t h s of 2.07(1) A and average N-Ni-N bond angles of 88.9(5)°. The t h r e e c o o r d i n a t i n g n i t r o g e n s from the HBpz* 3 l i g a n d have mean N-Ni bond lengths of 2.15(1) A and average N-Ni-N bond angles of 89.0(5)°. In the s t r u c t u r e the t r a n s - n i t r o g e n s are at a mean angle of 179.4(5)° and so the s i x n i t r o g e n metal bonds l i e on C a r t e s i a n axes with n i c k e l at the o r i g i n . The molecule has C 3 v symmetry along the B-Ni-B a x i s . A c o n f o r m a t i o n a l change has been brought about by the c o o r d i n a t i o n of the t r i s ( 3 , 5 - d i m e t h y l p y r a z o l y l ) b o r a t e l i g a n d . The i s o p r o p y l methyl groups are now p o i n t i n g away from the metal c e n t r e (cf HBpz* 3CoCl). A s t e r e o s c o p i c view of the s t r u c t u r e , c r y s t a l l o g r a p h i c parameters and bond le n g t h s and angles are l i s t e d i n appendix 3.b. 35 F i g u r e 2.7 S o l i d State M o l e c u l a r S t r u c t u r e of HBpz*3Nipz"3BH 2.3.3 E l e c t r o n i c Spectroscopy The e l e c t r o n i c t r a n s i t i o n s of the s o l v a t e d , mixed- l i g a n d complexes were i n v e s t i g a t e d by r e c o r d i n g a b s o r p t i o n s p e c t r a from the near i n f r a r e d t o the u l t r a - v i o l e t r e g i o n (4,000 cm" 1 t o 40,000 c m - 1 ) . The s e r i e s i n c l u d e d f o u r , f i v e and s i x c o o r d i n a t e complexes (Tables 2.5.a and 2.5.b, page 36) . A l l s p e c t r a were done wi t h a n a l y t i c a l l y pure samples d i s s o l v e d i n benzene, a g a i n s t a benzene r e f e r e n c e . 36 Table 2.5.a UV/Vis S p e c t r o s c o p i c Data of HBpz* 3NiL & ( L = mono- and t r i s - c h e l a t i n g l i g a n d s ) L Dq B A b s o r p t i o n Peaks ( c m - 1 ) * (cm - 1) (cm""1)® Extinction Coefficients(Lmol~1cm~1) CI 680 1030 36000 20800 17900 12400 10900 6060 970 500 100 92 440 130 HBpz 3 1140 823 36000 28900 18100 11400 100 17 7 4 HBpz" 3 1090 720 36000 26500 17400 10900 330 28 8 8 MeGapz 3 1080 740 36000 26800 17200 10800 80 11 5 6 MeGapz" 3 924 740 36000 24300 14900 1800 30 10 Table 2.5.b UV/Vis S p e c t r o s c o p i c Data of HBpz* 3NiL ( L = b i s c h e l a t e l i g a n d s ) L A b s o r p t i o n P e a k s . ( c m - 1 ) * E x t i n c t i o n Coefficients(Lmol-1cm-1) H 2 B p z 2 36000 32900 26700 17400 11700 6900 700 230 100 22 28 170 Me 2Bpz 2 36000 32300 27000 18200 11500 6540 550 200 220 140 1 9 Me 2Gapz 2 36000 32700 26500 16800 11400 6710 600 220 100 17 30 272 Me 2Gapz" 2 36000 31700 25700 15900 11200 6620 440 293 80 11 70 460 & D i s s o l v e d i n benzene. * E r r o r s i n a b s o r p t i o n peak p o s i t i o n s were determined by s u c c e s s i v e measurements and were of the order of 1-2%. @ N i c k e l f r e e i o n Racah parameter B° = 1080 cm - 1 37 One method of i n t e r p r e t i n g e l e c t r o n i c s p e c t r a i s t o assume a h i g h e r symmetry of the complex than i s a c t u a l l y p r e s e n t . The e l e c t r o n i c s p e c t r a of n i c k e l [ I I ] complexes i n p a r t i c u l a r have been w e l l i n t e r p r e t e d i n t h i s way 21,22,23 # The method assumes t h a t the l i g a n d s are e q u i v a l e n t p o i n t d i p o l e s and are arranged i n the h i g h e s t r e a l i s t i c symmetry. For example the s i x c o o r d i n a t e complexes can be assumed t o be of o c t a h e d r a l (0^) symmetry. T h i s method i s only an approximation and d e v i a t i o n s from the h i g h e r symmetries w i l l cause s p l i t t i n g of degenerate e l e c t r o n i c l e v e l s . Broad bands are expected and observed i n these s p e c t r a . In a s e r i e s of compounds with s i m i l a r symmetries and c o o r d i n a t i o n numbers i t would be expected t h a t s h i f t s i n the a b s o r p t i o n peaks r e f l e c t the l i g a n d f i e l d s t r e n g t h s . Both the c r y s t a l f i e l d s p l i t t i n g energy (10 Dq) and the Racah parameter (B) are c a l c u l a t e d f o r each complex and comparisons of the l i g a n d f i e l d s t r e n g t h s are made. E l e c t r o n i c t r a n s i t i o n s are not allowed between s t a t e s of l i k e p a r i t i e s (Laporte f o r b i d d e n ) . These p a r i t i e s are symmetry elements t h a t a r i s e from a c e n t r e of i n v e r s i o n and are e i t h e r odd (u) or even (g) . The d o r b i t a l s have g symmetry so d -> d t r a n s i t i o n s (g -> g) are f o r b i d d e n and s m a l l e x t i n c t i o n c o e f f i c i e n t s are expected. Octahedral complexes have l i g a n d s arranged such t h a t the t r a n s i t i o n metal i s a c e n t r e of i n v e r s i o n . The o c t a h e d r a l l i g a n d f i e l d then does not d i s t u r b the p a r i t y of the d o r b i t a l s . However the t e t r a h e d r a l l i g a n d f i e l d does not have an i n v e r s i o n 38 centre and d i s t o r t s the g symmetry of the d o r b i t a l s . The re s u l t i s that the forbiddeness of d -> d t r a n s i t i o n s i n tetrahedral complexes i s relaxed. Higher extinction c o e f f i c i e n t s are expected i n the e l e c t r o n i c t r a n s i t i o n s of tetrahedral complexes than of octahedral complexes. A comparison of the extinction c o e f f i c i e n t s i n Tables 2.5.a and 2.5.b shows t h i s trend. The macroscopic e f f e c t of t h i s i s seen i n the darker colors of the four coordinate complexes compared with the paler colors of the six coordinate complexes. 2.3.3a The Tetrahedal Approximation of HBpz*3NiCl A tetrahedral ligand f i e l d model i s used to predict the allowed e l e c t r o n i c t r a n s i t i o n energies of HBpz*3NiCl. The t r a n s i t i o n s for a d 8, tetrahedral complex are: 3T]_ > 3 T 2 v1 -> 3 A 2 v 2 •> 3Ti(P) v 3 •> 1E(D) spin forbidden •> *T 2 (G) spin forbidden There are three spin allowed and two spin forbidden t r a n s i t i o n s . The observed peaks are compared with a calculated f i t from Tanabe-Sugano diagrams for a d 8 tetrahedral ligand environment (Fig. 2 . 9 , Table 2 . 6 ) . (nm) F i g u r e 2.9 E l e c t r o n i c Spectrum of HBpz*3NiCl Table 2.6 C a l c u l a t e d and Observed E l e c t r o n i c T r a n s i t i o n E n e r g i e s of HBpz*3NiCl Observed (cm - 1) C a l c u l a t e d (cm" 1) Assignment 6060 (130)* 5790 vx 10900 (440) 1E(D) 12400 (92) 12400 v 2 17900 (100) 1 T 2 ( G ) 20800 (500) 20300 v3 36000 (970) C.T. e @ Charge t r a n s f e r band # E x t i n c t i o n c o e f f i c i e n t s The Dq and B v a l u e s c a l c u l a t e d are : D q = 680 cm" 1; B = 1030 cm" 1. 40 The calculated and observed spin allowed t r a n s i t i o n s energies f i t within 3 %. The close f i t supports the assignment of near tetrahedral symmetry to the four coordinate complex i n solution. The spin forbidden t r a n s i t i o n s from the t r i p l e t ground state to the singlet excited states are assigned to the bands at 17,900 cm - 1 ( 3A 2-> 1T 2) and 10,870 cm - 1 < 3A 2-> 1E). A descent of symmetry to a t r i g o n a l pyramidal (C3V) geometry would cause s p l i t t i n g of the t r i p l e t terms and band broadening. 2.3.3b The Octahedral Approximation of HBpz*3Nipz"3BH The c r y s t a l structure of HBpz*3Nipz"3BH showed a very nearly octahedral structure so an octahedral ligand f i e l d model might be expected to be a good approximation. The expected t r a n s i t i o n s for a d^ octahedral are: 3 A 2 g •> 3 T 2 g vl -> 3 T l g v2 •> 3 T l g ( P ) v3 -> ^ g W spin -> (D) spin There are three spin allowed and two spin forbidden t r a n s i t i o n s . The observed peaks are compared with a 41 c a l c u l a t e d f i t from Tanabe-Sugano diagrams f o r a d 8 o c t a h e d r a l l i g a n d environment ( F i g . 2.10/ Table 2.7). O I o " m 190 1000 2000 (nm) F i g u r e 2.10 E l e c t r o n i c Spectrum of HBpz*3Nipz"3BH Table 2.7 C a l c u l a t e d and Observed E l e c t r o n i c T r a n s i t i o n E n e r g i e s of HBpz 3Nipz 3BH Observed (cm" 1) C a l c u l a t e d (cm - 1) Assignment 10900 (8) 10900 V]_ 17400 (8) 17000 v 2 26500 (28) 26500 v 3 36000 (330) C.T. The Dq and B values calculated are : Dq = 720 cm"1; B = 1090 cm"1. The calcul a t e d and observed t r a n s i t i o n energies f i t within 3 %. The close f i t supports the assignment of near octahedral symmetry to the s i x coordinate complex i n sol u t i o n . 42 A descent of symmetry would cause a s p l i t t i n g of the t r i p l e t s t a t e terms and the broadening of bands. A comparison of the c r y s t a l f i e l d s p l i t t i n g s (10 Dq) of the n i c k e l o c t a h e d r a l complexes (Table 2.5.a) showed t h a t when complexed with HBpz*3NiCl the l i g a n d s were ordered, from s t r o n g f i e l d l i g a n d t o weak f i e l d l i g a n d as HBPZ3 > HBpz"3 ~ MeGapz3 > MeGapz"3. A s t r o n g e r f i e l d l i g a n d would be expected t o be e i t h e r a s t r o n g base t h a t would b i n d t i g h t l y t o the metal c e n t r e or s t e r i c a l l y s m a l l so t h a t i t can p h y s i c a l l y approach the metal more c l o s e l y . I f e l e c t r o n i c e f f e c t s were dominant then the h i g h e r e l e c t r o n e g a t i v i t y of boron would make the p y r a z o l y l r i n g more a c i d i c and so a weaker f i e l d l i g a n d than the g a l l i u m analog. However, j u s t the r e v e r s e i s seen. Methyl s u b s t i t u t i o n s at the 3 and 5 p o s i t i o n s on the p y r a z o l y l r i n g would make the r i n g more b a s i c ( i n d u c t i v e e f f e c t ) and so a s t r o n g e r f i e l d l i g a n d , but again the opp o s i t e i s observed. The l i g a n d f i e l d s t r e n g t h i s not an e l e c t r o n i c e f f e c t . S t e r i c c o n d i t i o n s imposed by the bulky l i g a n d , [HB(3-iPr - 4-Br-pz) 3 ]~ around the metal c e n t r e has determined the l i g a n d f i e l d s t r e n g t h of t h i s s e r i e s . 43 2.3.3c F i v e Coordinate N i c k e l r i l l Complexes There are c r y s t a l f i e l d models t h a t have been proposed f o r h i g h s p i n n i c k e l [ I I ] complexes i n both t r i g o n a l b i p y r a m i d a l (°3h) a n c * square pyramidal (C4 V) c o n f i g u r a t i o n s 2 2 . An attempt was made t o f i t the e l e c t r o n i c spectrum of HBpz*3Nipz2BH2 t o these models (Table 2.8). Table 2.8 C a l c u l a t e d and Observed E l e c t r o n i c T r a n s i t i o n E n e r g i e s of HBpz 3Nipz2BH2 Observed (cm - 1) C a l c u l a t e d (cm - 1) C a l c u l a t e d (cm - 1) C a l c u l a t e d (cm" 1) 6900 (170) 11700 (28) 17400 (22) 26700 (100) 32500 (230) 36000 (700) D 3 h 6900 13500 14600 22500 26400 C T . c 4 v 6900 9320 14100 23200 39300 C T , Oh 11700 17500 27200 C T . C T , I t i s c l e a r t h a t n e i t h e r model f i t s the observed spectrum so HBpz*3Nipz2BH2 possess n e i t h e r of these symmetries. There are a few examples of f i v e c o o r d i n a t e n i c k e l [ I I ] complexes whose e l e c t r o n i c t r a n s i t i o n e n e r g i e s f i t the t r i g o n a l b i p y r a m i d a l m o d e l 2 4 J 2 5 # c r y s t a l s t r u c t u r e of 4 4 one such complex, Me2Gapz"(OCH2CH2NMe2)Nipz"2GaMe2/ showed a d i s t o r t e d t r i g o n a l bipyramidal stucture. The c r y s t a l structure also showed the unsymmetrical 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 ligand, [Me2Gapz"(OCH2CH2NMe2)]~ coordinated i n a meridonal fashion, which may be instrumental i n the s t u c t u r a l symmetry. The [HBpz*3]~ ligand used i n the mixed-ligand complex series w i l l only coordinate i n a f a c i a l manner. The UV/Vis spectra of the f i v e coordinate complexes showed an additional band at 32,500 cm""1 (as a shoulder) that i s not seen i n the spectra of the four or six coordinate complexes (cf. F i g . 2.10 and F i g . 2.11). The ex t i n c t i o n c o e f f i c i e n t of t h i s band i s not large (200-410 Lmol - 1cm - 1) and i n i t i a l l y i t seemed the band could be » 0 400 (n«) 190 « 0 0 (nm) Figure 2 .11 UV/Vis Spectra of HBpz*3Nipz2BH2 i n Benzene and THF as Solvents assigned as a charge tr a n s f e r r e s u l t i n g from a coordinated benzene molecule. However a comparison of the e l e c t r o n i c spectra of HBpz* 3Nipz 2BH 2 recorded with d i f f e r e n t solvents 45 (benzene and THF) showed only a s l i g h t s h i f t i n bands. I f a benzene molecule had been c o o r d i n a t e d t h e r e should have been a l o s s of a charge t r a n s f e r band. The appearance of a new band at 41,500 cm - 1 ( F i g . 2.11) suggested t h a t a THF molecule had c o o r d i n a t e d . In a n t i c i p a t i o n of an o c t a h e d r a l complex a f i t to an o c t a h e d r a l symmetry was c a l c u l a t e d (Table 2.8) and the f i t was reasonably good. The h i g h band at 32,500 cm - 1 c o u l d be assign e d t o a charge t r a n s f e r but the low band at 6090 cm" 1 c o u l d not be assig n e d t h e r e f o r e making the 0^ model i n a p p r o p r i a t e . 2.4 C o n c l u s i o n The syntheses and p u r i f i c a t i o n s of the mixed l i g a n d compounds were r e f i n e d t o g i v e good y i e l d s (60-90%) of a n a l y t i c a l l y pure products. The mass s p e c t r a l evidence showed t h a t the HBpz3~, HBpz"3~ and MeGapz3~ l i g a n d s bound more t i g h t l y t o the metal c e n t e r than any of the other l i g a n d s i n the s e r i e s as evidenced by the appearance of i n t e n s e peaks at masses corresponding t o the ions [HBpZ3M] +, [HBpz'^M]"1" and [MeGapz3M] +, r e s p e c t i v e l y (M = Ni,Co). Numerous c r y s t a l growth techniques were attempted but c r y s t a l s of only two compounds, HBpz*3CoCl and HBpz*3Nipz"3BH, s u i t a b l e f o r X-ray c r y s t a l l o g r a p h y were produced. 46 T h e c r y s t a l s t r u c t u r e o f t h e s t a r t i n g m a t e r i a l , H B p z*3CoCl d e t e r m i n e d t h a t t h e s o l i d s t a t e s t r u c t u r e o f t h e c o m p l e x w a s f o u r c o o r d i n a t e a n d o f s y m m e t r y . T h e t h r e e p y r a z o l y l n i t r o g e n s c o o r d i n a t i n g t h e m e t a l f o r m e d t h e b a s e o f a t r i g o n a l p y r a m i d a l s t r u c t u r e w i t h t h e c h l o r i n e l i g a n d a t t h e a p e x . T h e c r y s t a l s t r u c t u r e o f HBpz*3Nipz"3BH s h o w e d t h a t t h e s o l i d s t a t e s t r u c t u r e o f t h e c o m p l e x w a s s i x c o o r d i n a t e a n d v e r y n e a r l y o c t a h e d r a l i n t h e a r r a n g e m e n t o f t h e t w o t r i s c h e l a t i n g l i g a n d s . T h e s t r u c t u r e a l s o s h o w e d a c o n f o r m a t i o n a l c h a n g e t h a t w a s i m p a r t e d t o t h e [ H B p z * 3 N i ] + c o m p l e x o n c o o r d i n a t i o n o f t h e H B p z " 3 ~ l i g a n d b y r o t a t i o n o f t h e i s o p r o p y l g r o u p i n t h e 3 p o s i t i o n o f t h e p z * r i n g . T h e e l e c t r o n i c s p e c t r a l e v i d e n c e d s h o w e d t h e g e o m e t r y o f t h e f o u r c o o r d i n a t e c o m p l e x , H B p z*3NiCl w a s a p p r o x i m a t e d b y a t e t r a h e d r a l s y m m e t r y . S i m i l a r l y t h e s i x c o o r d i n a t e c o m p l e x g e o m e t r y w a s a p p r o x i m a t e d b y a n o c t a h e d r a l s y m m e t r y . A c o m p a r i s o n o f t h e c r y s t a l f i e l d s p l i t t i n g e n e r g i e s o f t h e o c t a h e d r a l c o m p l e x e s g a v e a l i g a n d f i e l d s t r e n g t h o r d e r o f H B p z 3 > H B p z " 3 ~ MeGapz3 > M e G a p z " 3 w h e n c o m p l e x e d w i t h H B p z * 3 N i C l . T h i s o r d e r w a s a s a r e s u l t o f t h e s t e r i c c o n t r o l o f t h e a c t i v e p o c k e t b y t h e i n t e r m e d i a t e l i g a n d [ H B p z * 3 ] ~ . T h e f i v e c o o r d i n a t e c o m p l e x e s f i t n e i t h e r a t r i g o n a l b i p y r a m i d a l (03^) n o r s q u a r e p y r a m i d a l (C4V) m o d e l . T h e a t t e m p t t o f i t a n o c t a h e d r a l s y m m e t r y w a s a l s o u n s u c c e s s f u l b e c a u s e o f a n u n a s s i g n a b l e b a n d a t 6 9 0 0 c m - 1 . F u r t h e r w o r k 47 needs t o be done t o e l u c i d a t e the s t r u c t u r e s of these complexes. The a c t i v e pocket c r e a t e d by Trofimenko's i n t e r m e d i a t e l i g a n d i n the complexes [HBpz*3]MCl have been probed by the c h a r a c t e r i z a t i o n of the s e r i e s of mixed-ligand complexes. The s e r i e s demonstrated p r e f e r e n t i a l b i n d i n g of some l i g a n d s , s t e r i c c o n t r o l of s u b s t r a t e l i g a n d s and c o n f o r m a t i o n a l changes i n the metal complexes on c o o r d i n a t i o n of a s u b s t r a t e l i g a n d . 48 Chapter I I I Rhodium[I] Complexes of Unsymmetrical P y r a z o l y l g a l l a t e Ligands and T h e i r R e a c t i v i t y 3.1 I n t r o d u c t i o n There are a number of f o u r c o o r d i n a t e rhodium[I] complexes t h a t have been r e p o r t e d t o show c a t a l y t i c a c t i v i t y . These complexes are s i x t e e n e l e c t r o n s p e c i e s and are expected t o r e a d i l y undergo o x i d a t i v e a d d i t i o n s . T h i s i s an important step i n c a t a l y t i c a c t i v i t y . O x i d a t i v e a d d i t i o n t o a rhodium[I] complex produces a s i x c o o r d i n a t e , rhodium[III] complex. The r e v e r s e r e a c t i o n , r e d u c t i v e e l i m i n a t i o n of a rhodium[III] complex, must a l s o take p l a c e t o complete a c a t a l y t i c c y c l e , r e g e n e r a t i n g a f o u r c o o r d i n a t e rhodium[I] complex. A square p l a n a r , rhodium[I] complex i s a l s o c o o r d i n a t i v e l y unsaturated, p r o v i d i n g empty c o o r d i n a t i o n s i t e s f o r incoming s u b s t r a t e s , another important f e a t u r e of a c a t a l y t i c reagent. When l o o k i n g f o r c a t a l y t i c a c t i v i t y i n a new s p e c i e s i t i s important t o look at the i n t e r m e d i a t e steps i n s u c c e s s f u l l y c a t a l y s e d r e a c t i o n s . W i l k i n s o n ' s c a t a l y s t , Rh(PPh3)3Cl, i s perhaps the most known f o r i t s c a t a l y t i c hydrogenation of a l k e n e s 2 ^ . The c a t a l y t i c steps i n c l u d e o x i d a t i v e a d d i t i o n of H2 and ft bonding o f an alkene. Another important rhodium[I] c a t a l y t i c reagent i s 49 RhH (CO) (PPh.3) 2/ used i n the h y d r o f o r m y l a t i o n o f a l k e n e s 2 7 . The c a t a l y t i c steps i n c l u d e o x i d a t i v e a d d i t i o n o f E2, TZ bonding o f an alkene and a d d i t i o n and i n s e r t i o n of carbon monoxide. The Monsanto reagent, Rh(C0)2l2' ^ s u s e c * a s a c a t a l y s t i n the s y n t h e s i s of a c e t i c a c i d 2 8 , important s t e p s i n t h i s r e a c t i o n a re the o x i d a t i v e a d d i t i o n o f CH3I and a d d i t i o n and i n s e r t i o n o f carbon monoxide. Another important r e a c t i o n t h a t has c a t a l y t i c s i g n i f i c a n c e i s t h e a c t i v a t i o n of carbon-hydrogen bonds ( i e . o x i d a t i v e a d d i t i o n o f R-H). A number of f i v e c o o r d i n a t e rhodium[I] complexes have been r e p o r t e d t h a t show t h i s type o f a c t i v i t y 2 ^ / 3 0 t I n t e r e s t i n the 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 i n c a t a l y s i s arose w i t h r e p o r t s t h a t complexes of formula LRh(CO) (L = Me2Gapz(OCH2CH2NMe2)31, Me 2Gapz(OC 9H 6N) 3 2, Me2Gapz(OCH 2(C5H4N) 3 3) have shown o x i d a t i v e a d d i t i o n o f Mel and the subsequent i n s e r t i o n o f a ca r b o n y l i n t o the rhodium-methyl bond ( F i g . 3.0). VC0 : 1»55 ( C H , C l t ) V C O t 2 0 6 3 ( C H 2 C I 2 ) vCO»1720 (CH^CI,) F i g u r e 3.0 O x i d a t i v e A d d i t i o n o f Mel and Carbonyl I n s e r t i o n on Me 2Gapz(OCH2CH 2NMe 2)Rh(CO) 50 This a c t i v i t y prompted further investigations of sim i l a r rhodium[I] complexes and the res u l t s are reported i n t h i s chapter. The unsymmetric, tridentate p y r a z o l y l g a l l a t e ligands are derived from the [Me2Gapz2]~ ligand by replacement of one of the pyra z o l y l rings with a b i f u n c t i o n a l moiety (Fig 3.1). T r i s chelation can take place through the electron lone p a i r s on the nitrogen of the pyrazolyl r i n g and the donor atoms (X and Y) of the bi f u n c t i o n a l moiety. The donor atoms may be varied and substituents may be added to the pyrazolyl r i n g providing s t e r i c and el e c t r o n i c control. The carbon fragment of the bi f u n c t i o n a l moiety may be varied and through adroit substitutions can control the coordination mode of the ligand. These ligands have been shown to be able to coordinate to t r a n s i t i o n metals i n either a f a c i a l or meridional f a s h i o n 2 4 . The coordination mode of the ligand may be important i n binding a substrate to the metal centre. Figure 3.1 Tris-Chelating Unsymmetric Pyr a z o l y l g a l l a t e Ligand 51 A common c a t a l y t i c step i s the l o s s of a l i g a n d t o f r e e a c o o r d i n a t i o n s i t e f o r s u b s t r a t e b i n d i n g . The subsequent reattachment of the l i g a n d t o complete the c a t a l y t i c c y c l e suggested the use of a m u l t i d e n t a t e l i g a n d . The reas o n i n g i s t h a t i f the d i s p l a c e d l i g a n d were an arm on a m u l t i d e n t a t e l i g a n d , i t would be h e l d nearby f o r a more expedient r e - attachment. The unsymmetric p y r a z o l y l g a l l a t e s l i g a n d s seemed t o o f f e r t h i s p o t e n t i a l . In t h i s chapter the p r e p a r a t i o n s and r e a c t i v i t i e s of two rhodium[I] complexes, i n c o r p o r a t i n g the unsymmetric p y r a z o l y l g a l l a t e s l i g a n d s , are d e s c r i b e d . The two l i g a n d s used were prepared by v a r y i n g only the Y group. The p y r a z o l y l . r i n g was u n s u b s t i t u t e d , the X donor was oxygen and the carbon c h a i n was - C H 2 - C H 2 - . The Y donor groups were -NH2 and -CH=CH2 and were a b b r e v i a t e d (EA) f o r ethanolamino and (but) f o r bu t - 3 - e n o l a t e . 3.2 Experimental The syntheses of N a + [ M e 2 G a p z ( E A ) ] ~ and N a + [ M e 2 G a p z ( b u t ) ] ~ are r e p o r t e d i n chapter 2. A l l r e a c t i o n s were c a r r i e d out under a n i t r o g e n atmosphere. Sol v e n t s were p u r i f i e d by the methods d e s c r i b e d i n chapter 2. Mic r o a n a l y s e s were attempted on a l l compounds and those t h a t gave s a t i s f a c t o r y r e s u l t s are r e p o r t e d . 52 3.2.1 Preparation of Me?Gaoz(EA)Rh(CO) Na +[Me 2Gapz(EA)]" > Me2Gapz (EA)Rh(CO) + r e f l u x l / 2 [ R h ( C 0 ) 2 C l ] 2 + CO + NaCl Two molar equivalents of Na +[Me 2Gapz(EA)]~ (1.02 mmole) i n THF were added to a molar equivalent of rhodium dimer (0.198 g; 0.510 mmole) dissolved i n 150 ml of THF. The mixture was refluxed under a nitrogen atmosphere for 16 hours. The disappearance of the rhodium dimer carbonyl stretches at 2070 and 1985 cm - 1 (THF) i n the IR spectrum and the appearance of the product monocarbonyl str e t c h at 1945 cm - 1 (THF) monitored the progress of the reaction (Fig. 3.2). The mixture was made up to a known volume with THF and stored under nitrogen. 2000 2000 2000 c a [Rh(CO) 2Cl] 2 3 hour r e f l u x Me2Gapz(EA)Rh(CO) Figure 3.2 IR Spectra of [Rh(CO) 2C1] 2 / the reaction mixture a f t e r a 3 hour r e f l u x and Me2Gapz(EA)Rh(CO) 53 3.2.2 Preparation of Me2Gapz(but)Rh(CO) Na +[Me 2Gapz(but)]" > Me2Gapz(but)Rh(CO) + reflux 1/2 [Rh(CO) 2Cl] 2 + CO + NaCl Two molar equivalents of Na +[Me 2Gapz(but)]~ (2.77 mmole) i n THF were added to a molar equivalent of rhodium dimer (0.538 g; 1.38 miftole) dissolved i n 150 ml of THF. The mixture was refluxed under a nitrogen atmosphere for 18 hours. The disappearance of the rhodium dimer carbonyl stretches at 2070 and 1985 cm - 1 (THF) i n the IR spectrum and the appearance of the monocarbonyl stretch at 1995 cm - 1 (THF) monitored the progress of the reaction. The mixture was made up to a known volume with THF and stored under a nitrogen atmosphere. 3.2.3 Attempted Preparation of Me2Gapz"(EA)Rh(CO) Na + [Me2Gapz" (EA) ] ~ — X — > Me2Gapz" (EA) Rh (CO) + reflux 1/2 [Rh(CO) 2Cl] 2 + CO + NaCl The reaction was ca r r i e d out i n a s i m i l a r fashion as the above reactions. The reaction mixture was refluxed for 18 hours under a nitrogen atmosphere. The rhodium dimer carbonyl stretches i n the IR spectrum at 2070 and 1985 cm - 1 (THF) were replaced by carbonyl stretches at 2098, 2075 and 2020 cm - 1 (THF). The solvent was stripped o f f under vacuum 54 l e a v i n g a brown s o l i d . T h i s s o l i d was r e d i s s o l v e d i n C H 2 C I 2 and the mixture was f i l t e r e d . The s o l v e n t was allowed t o evaporate s l o w l y t o promote c r y s t a l growth. The i s o l a t e d compound ana l y s e d f o r C7H7N202Rh, as the probable dimer [ R h ( C O ) 2 p z " ] 2 . M i c r o a n a l y s i s : [Rh(CO)2P Z"]2 C a l c . C 33.08 H 2.76 N 11.03 Found C 33.31 H 3.02 N 10.80 3.2.4 Reactions of R h f l l Complexes O x i d a t i v e a d d i t i o n , a d d i t i o n and carbon-hydrogen bond a c t i v a t i o n r e a c t i o n s were attempted with both Me 2Gapz(EA)Rh(CO) and Me 2Gapz(but)Rh(CO). Reactions were monitored by changes i n the IR spectrum of the c a r b o n y l r e g i o n . The a b i l i t y of the rhodium c e n t r e t o back bond t o the c a r b o n y l a n t i b o n d i n g o r b i t a l s w i l l be a f f e c t e d by the o x i d a t i o n s t a t e of the metal and the e l e c t r o n donating a b i l i t y of the l i g a n d s . The more e l e c t r o n d e n s i t y about the metal c e n t e r , the weaker the c a r b o n y l s t r e t c h . 3.2.4a O x i d a t i v e A d d i t i o n Reactions An excess of Mel was added t o a s t i r r e d THF s o l u t i o n of Me2Gapz(EA)Rh(CO) and the mixture was r e f l u x e d f o r one hour. 55 The carbonyl stretching frequencies i n the IR spectrum s h i f t e d from 1945 cm'1 (THF) to 2030 cm"1 (THF). The higher C-0 stretch of the product was consistent with a higher oxidation state of the rhodium centre. Oxidative addition of Mel to the rhodium[I] complex would produce the s i x coordinate rhodium[III] adduct, Me2Gapz(EA)Rh(CO)(Me)I (Fig 3 . 3 . a ) . The solvent was removed under vacuum leaving a dark red s o l i d . This s o l i d was redissolved i n CH2CI2 and the mixture was f i l t e r e d . The solvent was allowed to evaporate slowly to promote c r y s t a l growth. The i s o l a t e d compound was un i d e n t i f i a b l e by microanalysis. A carbonyl i n s e r t i o n into the newly formed rhodium- methyl bond was anticipated but there was no evidence of an acetyl group i n the IR spectrum of the product. Figure 3 . 3 . a Preparation of Me2Gapz(EA)Rh(CO)(Me)(I) In a subsequent reaction the mixture was refluxed f o r 4 days. The carbonyl st r e t c h s h i f t e d from 2030 cm"1 (THF) to 2060 cm"1 (THF). The solvent was removed under vacuum leaving a dark red s o l i d . This s o l i d was redissolved i n 56 C H 2 C I 2 and the mixture f i l t e r e d . The slow e v a p o r a t i o n of s o l v e n t l e f t a s o l i d t h a t a nalysed as CcjHis^C^T^Rh' M i c r o a n a l y s i s : M e 2 G a p z(EA)Rh(CO)(Me)I2 C a l c . C 17.24 H 2.89 N 6.71 Found C 17.62 H 2.97 N 6.81 T h i s compound was the net a d d i t i o n of M e l 2 t o Me 2Gapz(EA)Rh(CO) t o g i v e Me 2Gapz(EA)Rh(CO)(Me)I 2• The way i n which the M e l 2 was i n c o r p o r a t e d i n t o the s t r u c t u r e i s not c l e a r . I t i s u n l i k e l y the second i o d i d e was bonded t o the rhodium c e n t r e because t h a t would have produced a rhodium[IV] complex. The complex may have been an iodo s a l t of a rhodium[III] c a t i o n i c complex which a c o n d u c t i v i t y measure would have e s t a b l i s h e d as a p o s s i b i l i t y . An excess of I2 was added t o a THF s o l u t i o n of Me 2Gapz(EA)Rh(CO) and the mixture r e f l u x e d f o r 2 hours. The c a r b o n y l s t r e t c h i n the IR spectrum s h i f t e d from 1945 cm - 1 (THF) t o 2095 cm - 1 (THF) . The s h i f t was c o n s i s t e n t with an o x i d a t i v e a d d i t i o n of I2 t o produce the complex M e 2 G a p z(EA)Rh(CO) I 2 ( F i g . 3 . 3 . b ) . The s o l v e n t was removed under vacuum l e a v i n g a reddish-brown s o l i d . T h i s s o l i d was r e d i s s o l v e d i n C H 2 C I 2 and the mixture f i l t e r e d . The s o l v e n t was allowed t o evaporate s l o w l y . The i s o l a t e d s o l i d was u n i d e n t i f i a b l e . 57 »-co: 1945 (THF) rCO: 2095 (THF) F i g u r e 3.3.b P r e p a r a t i o n of Me 2Gapz(EA)Rh(CO)I 2 An excess of a l l y l bromide was added t o a s o l u t i o n of Me 2Gapz (EA) Rh (CO) i n THF and s t i r r e d f o r one hour. The ca r b o n y l s t r e t c h i n the IR spectrum s h i f t e d from 1945 cm - 1 (THF) t o 2065 cm" 1 (THF) which was c o n s i s t e n t w i t h an o x i d a t i v e a d d i t i o n of a l l y l bromide ( F i g . 3.3.C) t o produce the complex, M e 2 G a p z ( E A ) R h ( C O ) ( a l l y l ) B r . When the r e a c t i o n mixture was r e f l u x e d f o r one hour, the c a r b o n y l band i n the IR spectrum d i s a p p e a r e d . Presumably the rx a l l y l complex, F i g u r e s 3.3.C M e 2 G a p z ( E A ) R h ( C O ) ( a l l y l ) B r 3.3.d M e 2 G a p z ( E A ) R h ( n 3 - a l l y l ) B r 58 M e 2 G a p z ( E A ) R h ( n ^ - a l l y l ) B r was produced through l o s s of a c a r b o n y l l i g a n d ( F i g . 3.3.d). N e i t h e r product was s u c c e s s f u l l y i s o l a t e d . 3.2.4b A d d i t i o n R e a c t i o n s Carbon monoxide was bubbled through a c o l d (0°C) THF s o l u t i o n of M e 2 G a p z(EA) fch (CO) f o r one hour. The 1945 cm""1 c a r b o n y l s t r e t c h was r e p l a c e d by bands at 2075 and 2015 cm - 1 which i s c o n s i s t e n t with the d i c a r b o n y l s p e c i e s , M e 2 G a p z(EA)Rh(CO)2 ( F i g . 3.3.e). The compound was not s u c c e s s f u l l y i s o l a t e d . F i g u r e s 3.3.e Me2Gapz(EA)Rh(CO)2 Ethene was bubbled through a c o l d (0°C) THF s o l u t i o n o f Me2Gapz (EA)Rh(CO) f o r one hour. The 1945 cm" 1 c a r b o n y l s t r e t c h was r e p l a c e d by two bands a t 2075 and 2005 c m - 1 s u g g e s t i n g the fo r m a t i o n o f isomers of the ethene adduct ( F i g . 3.3.f). T h i s compound was r e c r y s t a l l i z e d from 5 9 methylene chloride and analysed as Me2Gapz(EA)Rh(CO)(ethene) • 0.5 CH 2C1 2. Microanalysis: Me 2Gapz(EA)Rh(CO)(ethene)•0.5 CH 2Cl2 Calc. C 29.30 H 4.70 N 9.79 Found C 29.01 H 4.61 N 9.70 Figures 3.3.f Me 2Gapz(EA)Rh(CO)(ethene) 3.2.4c A c t i v a t i o n of Carbon-Hydrogen Bonds There are a few tripodal ligand systems reported that activate carbon-hydrogen bonds2**'30. T^e pyrazolyl based complex/ HBpz^Rh (CO) 2 / reported by Graham et a l . / photochemically activates aromatic and saturated hydrocarbons. For example/ when a benzene solution of HBpz*3Rh(CO)2 i s irradiated for 5 minutes with a mercury lamp there i s complete conversion to HBpz^RMCO) ( C 5 H 5 ) (H) . The success of HBpz^RhtCO) 2 as a carbon-hydrogen bond activator prompted the investigation of the unsymmetrical 60 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 rhodium[I] c a r b o n y l complexes, LRh(CO) (L = Me 2Gapz(0CH 2CH 2NH 2),Me 2Gapz(OCH 2CH 2CH=CH 2)) f o r t h i s type of behaviour. A d d i t i o n a l l y , both of these complexes r e a d i l y added a c a r b o n y l forming the f i v e c o o r d i n a t e , d i c a r b o n y l adduct, LRh(C0) 2, t h a t was analogous t o the HBpz'^Rh(CO) 2 complex r e p o r t e d by Graham. An attempt was made t o a c t i v a t e the carbon-hydrogen bond of benzene with Me 2Gapz(EA)Rh(CO) 2. The monocarbonyl complex, Me 2Gapz(EA)Rh(CO) was d i s s o l v e d i n benzene and p l a c e d i n an i r r a d i a t i o n tube. The tube was immersed i n an i c e bath and carbon monoxide was bubbled through the s o l u t i o n f o r one hour. The IR s p e c t r a r e c o r d e d the appearance of c a r b o n y l bands at 2095 and 2030 cm - 1 (benzene) t h a t were c o n s i s t e n t with the d i c a r b o n y l complex, Me 2Gapz(EA)Rh(CO) 2. The s o l u t i o n was i r r a d i a t e d f o r s i x hours by a mercury lamp. There was no change i n the IR spectrum so i t was concluded t h a t no a c t i v a t i o n had taken p l a c e . The f i v e c o o r d i n a t e ethene adduct, Me 2Gapz(EA)Rh- (CO)(ethene) ( F i g . 3 . 3 . f ) , was prepared by b u b b l i n g a stream of ethene through a c o l d benzene s o l u t i o n of Me 2Gapz(EA)Rh(CO). In an attempt t o a c t i v a t e a carbon hydrogen bond of benzene t h i s s o l u t i o n was i r r a d i a t e d f o r s e v e r a l hours. No a c t i v a t i o n was observed. 61 3.2.4d Reactions of Me 2Gapz(but)Rh(CO) The r e a c t i v i t y o f Me 2Gapz(but)Rh(CO) was t e s t e d by r e a c t i o n with the same reagents. I n f r a r e d evidence suggested o x i d a t i v e a d d i t i o n s of Mel, I 2 and a l l y l bromide, as w e l l as a d d i t i o n s of c a r b o n y l and ethene l i g a n d s had taken p l a c e . The d i c a r b o n y l and ethene adducts were t e s t e d f o r C-H bond a c t i v a t i o n but no r e a c t i v i t y was observed. A synopsis of the r e a c t i o n s , with r e l e v a n t IR s t r e t c h e s i s shown i n f i g u r e 3.4 3.3 Co n c l u s i o n s The rhodium[I] monocarbonyl p y r a z o l y l g a l l a t e complexes appearred t o take p a r t i n o x i d a t i v e a d d i t i o n s and a d d i t i o n r e a c t i o n s but no f u r t h e r a c t i v i t y was observed. The v e r s a t i l i t y of these l i g a n d s l i e s i n the numerous s u b s t i t u t i o n a l p o s s i b i l i t i e s . The s u b t l e t y of s u b s t i t u t i o n s on the unsymmetrical p y r a z o l y l g a l l a t e l i g a n d s was demonstrated by the the f a c t t h a t the complex Me 2Gapz(OCH 2CH 2NMe 2)Rh(CO) had shown a ca r b o n y l i n s e r t i o n a f t e r o x i d a t i v e a d d i t i o n of Mel ( F i g . 3.0) where the complex Me 2Gapz(OCH 2CH 2NH 2)Rh(CO) d i d not. The complexes d i f f e r only i n t h a t the donor n i t r o g e n group of the b i f u n c t i o n a l moiety on the former i s methyl s u b s t i t u t e d . F i g u r e 3 . 4 R e a c t i o n s of Me2Gapz(but)Rh(CO)  64 Chapter IV H e t e r o b i m e t a l l i c Complexes I n c o r p o r a t i n g P y r a z o l y l b o r a t e Ligands 4.1 I n t r o d u c t i o n I t i s thought t h a t the study of simple metal-metal bonds and the c o o p e r a t i v e e f f e c t s between d i f f e r e n t metal c e n t e r s i n h e t e r o b i m e t a l l i c complexes w i l l l e a d t o an understanding of high e r order metal c l u s t e r s , with a p a r t i c u l a r r e f e r e n c e t o c a t a l y s i s 3 4 . In a c o n t i n u i n g e f f o r t t o form metal-metal bonds the r e a c t i o n s of the molybdenum anions, [LMo ( C 0 ) 3 ] ~ (L = M e G a p z 3 , HBpz3, HBpz'^) with a v a r i e t y of t r a n s i t i o n metal h a l i d e s have been c a r r i e d out. Complexes with d i r e c t Mo-Rh, Mo-Cu and Mo-Sn bonds have been prepared and f u l l y c h a r a c t e r i z e d 3 5 ' 3 6 ' 3 7 . T h i s present chapter d e t a i l s the r e a c t i v i t y of K +[HBpz" 3Mo(CO)3 ]~ towards SnMe 3Cl, SnPh 3Cl, the tetramer [CuPPh 3Cl]4, GePh 3Cl and N i ( P P h 3 ) 2 C l 2 and the r e s u l t s are d i s c u s s e d . 65 4.2 Experimental The s y n t h e s i s of the t r i d e n t a t e l i g a n d , K +[HBpz " 3 ] ~ , i s d e s c r i b e d i n chapter 2. The tetramer [ C u P P h 3 C l]4 was prepared by a l i t e r a t u r e method 3 8. S n M e 3 C l was obtained from A l d r i c h Chemicals, SnPh 3Cl, GePh 3Cl and N i ( P P h 3 ) 2 C l 2 were obt a i n e d from A l f a Chemicals and were used without further- p u r i f i c a t i o n . 4.2.1 P r e p a r a t i o n of (MeCN)3M0(CO)3 Mo (CO) 6 + 3 MeCN > (MeCN) 3 M 0 (CO) 3 + 3 CO r e f l u x A round bottom f l a s k was charged with 120 ml of MeCN and one gram of Mo(CO)g. The c o l o r l e s s s o l u t i o n t u r n e d a ye l l o w i s h - g r e e n c o l o r d u r i n g a s i x t y hour r e f l u x under a n i t r o g e n atmosphere. The s o l v e n t was removed, under vacuum, l e a v i n g y e l l o w i s h - g r e e n , a i r - s e n s i t i v e c r y s t a l s . I t was important t h a t the MeCN be f r e s h l y d r i e d and d i s t i l l e d as the q u a l i t y of the product was otherwise i n f e r i o r . The compound, (MeCN) 3M0 (CO) 3 , has been found t o be a p r e f e r r e d s t a r t i n g m a t e r i a l f o r the p r e p a r a t i o n of the p y r a z o l y l complex anion, [ (HBpz'^) (CO) 3M0] ~ 39.40# T h e a c e t o n i t r i l e l i g a n d s are e a s i l y removed a l l o w i n g almost q u a n t i t a t i v e y i e l d s of p r o d u c t s . 66 The IR spectrum of (MeCN)3M0(CO) 3 showed c a r b o n y l s t r e t c h e s at 1912 and 1773 cm - 1 ( T H F ) 4 1 . 4.2.2 P r e p a r a t i o n of K+HHBpz" 3) Mo (CO) 31 ~ K + [ H B p z " 3 ] " + (MeCN)3M0(CO)3 > K +[(HBpz" 3)(CO)3M0]~ r e f l u x + 3 MeCN A molar e q u i v a l e n t of K + [ H B p z " 3 ] - (1.22 g; 3.63 mmole), d i s s o l v e d i n 50 ml of THF, was added t o a THF s o l u t i o n of (MeCN)3M0(CO)3 (1.10 g; 3.63 mmole). The mixture was s t i r r e d o v e r n i g h t and a c o l o r change from l i g h t green t o dark green was observed. The c a r b o n y l s t r e t c h e s i n the i n f r a r e d spectrum s h i f t e d from 1912 and 1773 cm - 1 (THF) t o 1885,1760 and 1720 cm" 1 (THF) s i g n a l l i n g the completion of the r e a c t i o n . The s o l u t i o n was then made up t o a known volume with THF and s t o r e d under a n i t r o g e n atmosphere. 4.2.3 P r e p a r a t i o n of H e t e r o b i m e t a l l i c Complexes 4.2.3a P r e p a r a t i o n of (HBpz"3 )(CO)3 M o C u P P h 3 A q u a r t e r molar e q u i v a l e n t of the tetramer, [CuPPh3Cl]4 (0.174 g; 0.482 mmole) d i s s o l v e d i n 50 ml of THF, was added t o a THF s o l u t i o n of K +[(HBpz"3)(CO)3M0]~ (1.93 mmole). The r e a c t i o n mixture was s c i r r e d over n i g h t and a c o l o r change from dark green t o dark brown was observed. The s o l v e n t was 67 removed under vacuum l e a v i n g a brown s o l i d . T h i s s o l i d was r e d i s s o l v e d i n C H 2 C I 2 and the mixture was f i l t e r e d . An equal p o r t i o n of hexane was added and the s o l v e n t mixture allowed t o evaporate s l o w l y . A n a l y t i c a l l y pure samples were f i n a l l y o b t a i n e d by r e c r y s t a l l i z a t i o n from benzene. The c a r b o n y l s t r e t c h e s i n the IR spectrum were seen at 1 8 8 5 and 1 7 8 0 cm - 1 ( N u j o l ) . M i c r o a n a l y s i s : (HBpz'^)(CO)3MoCuPPh3 C a l c . C 5 3 . 8 5 H 4 . 6 4 N 1 0 . 4 7 Found C 5 4 . 1 3 H 4 . 8 5 N 1 0 . 5 0 4 . 2 . 3 b Attempted P r e p a r a t i o n of (HBpz"3) (CO) 3 M 0 C U ( P P h o ) A molar e q u i v a l e n t of Cul ( 0 . 1 6 8 g; 0 . 8 8 0 mmoles) and a molar e q u i v a l e n t of P h 2 P C H 2 P P h 2 ( 0 . 3 3 6 g; 0 . 8 8 0 mmoles) were added t o a THF s o l u t i o n of K +[(HBpz" 3 )(CO) 3 M 0 ] ~ ( 0 . 8 8 0 mmoles). The mixture was s t i r r e d o v e r n i g h t . The s o l v e n t was removed under vacuum l e a v i n g a green s o l i d . T h i s s o l i d was r e d i s s o l v e d i n CH2CI2 and the mixture was f i l t e r e d . An equal p o r t i o n of hexane was added and the s o l v e n t mixture was allowed t o evaporate s l o w l y . No a n a l y t i c a l l y pure samples were ob t a i n e d . 68 4.2.3c P r e p a r a t i o n of (HBpz"3)(CO)3MoSnMe 3 A molar e q u i v a l e n t of SnMe3Cl (0.332 g; 1.67 mmole), d i s s o l v e d i n 50 ml of THF, was added t o a THF s o l u t i o n of K +[(HBpz'^)(CO)3M0]~ (1.67 mmole). The mixture was s t i r r e d o v e r n i g h t and a c o l o r change from dark green t o brown was observed. The s o l v e n t was removed under vacuum l e a v i n g a yellowish-brown s o l i d . T h i s s o l i d was r e d i s s o l v e d i n CH2CI2 and the mixture was f i l t e r e d . An equal p o r t i o n of hexane was added and the s o l v e n t mixture was allowed t o evaporate s l o w l y . M i c r o a n a l y s i s : (HBpz'^)(CO)3MoSnMe3 C a l c d . C 39.35 H 13.11 N 4.88 Found C 39.44 H 13.30 N 5.03 4.2.3d P r e p a r a t i o n of (HBpz"3)(CO) 3MoSnPh3 A molar e q u i v a l e n t of SnPt^Cl (0.643 g; 1.67 mmole), d i s s o l v e d i n 50 ml of THF, was added t o a THF s o l u t i o n of K +[(HBpz"3)(CO)3M0]~ (1.67 mmole). The mixture was s t i r r e d o v e r n i g h t and a c o l o r change from dark green t o yel l o w was observed. The s o l v e n t was removed under vacuum l e a v i n g a yell o w s o l i d . T h i s s o l i d was r e d i s s o l v e d i n CH2CI2 and the mixture f i l t e r e d . An equal p o r t i o n of hexane was added and the s o l v e n t mixture was allowed t o evaporate s l o w l y . 69 The c a r b o n y l s t r e t c h e s i n the IR spectrum were seen at 1955 and 1865 cm - 1 ( N u j o l ) . M i c r o a n a l y s i s : (HBpz'^) (CO)3MoSnPh3 C a l c d . C 52.22 H 4.59 N 10.15 Found C 51.85 H 4.49 N 9.95 4.2.3e P r e p a r a t i o n of (HBPZ" 3)(CO)3MoGePh 3 A molar e q u i v a l e n t of GePh 3Cl (0.101 g; 0.298 mmole), d i s s o l v e d i n 50 ml of THF, was added to a THF s o l u t i o n of K + [ (HBpz"3) (CO)3M0]~ (0.298 mmole). The mixture was s t i r r e d o v e r n i g h t and a c o l o r change from dark green t o orange was observed. The s o l v e n t was removed under vacuum l e a v i n g an orange s o l i d . T h i s s o l i d was r e d i s s o l v e d i n C H 2 C I 2 and the mixture was f i l t e r e d . An equal p o r t i o n of hexane was added and the s o l v e n t mixture was allowed t o evaporate s l o w l y . The c a r b o n y l s t r e t c h e s i n the IR spectrum were seen at 2000 and 1915 cm - 1 (THF). M i c r o a n a l y s i s : (HBpz'^)(CO)3MoGePh3 C a l c d . C 55.36 H 4.78 N 10.76 Found C 55.24 H 5.00 N 11.00 70 4.2.3f Attempted P r e p a r a t i o n of (HBpz"3 )(CO) 3MoNi(PPh 3)0 A molar e q u i v a l e n t of N i ( P P h 3 ) 2 C 1 2 (0.195 g; 0.298 mmole), d i s s o l v e d i n 50 ml THF, was added t o a THF s o l u t i o n of K +[(HBpz" 3) (CO) 3Mo]" (0.298 mmole). The mixture was s t i r r e d o v e r n i g h t with no apparent c o l o r change. The s o l v e n t was removed under vacuum l e a v i n g a dark green s o l i d . T h i s s o l i d was r e d i s s o l v e d i n C H 2 C I 2 and the mixture was f i l t e r e d . An equal p o r t i o n of hexane was added and the s o l v e n t mixture was allowed t o evaporate s l o w l y . The i s o l a t e d product was not i d e n t i f i a b l e by m i c r o a n a l y s i s . The c a r b o n y l s t r e t c h e s i n the IR spectrum were seen at 1995,1935 and 1910 cm - 1 (THF). 4.3 D i s c u s s i o n The r e a c t i o n s of the t r a n s i t i o n metal anion, [ (HBpz" 3) (CO) 3Mo]~ with o r g a n o m e t a l l i c h a l i d e s l e d t o the s u c c e s s f u l s y n t h e s i s of s e v e r a l new h e t e r o b i m e t a l l i c complexes. The r e a c t i o n of [(HBpz" 3)(CO) 3Mo]" w i t h [ C u P P h 3 C l ] 4 gave a brown compound t h a t a n a l y s e d as (HBpz" 3)(CO) 3MoCuPPh 3. A c r y s t a l s t r u c t u r e of t h i s complex was not o b t a i n e d but i n f e r e n c e s were made by the examination of the s t r u c t u r e of an analogous compound. The compound (MeGapz 3)(CO) 3MoCuPPh 3 has been made and an X-ray c r y s t a l 71 s t r u c t u r e has been d e t e r m i n e d 3 ^ . The c r y s t a l s t r u c t u r e showed t h a t the molecule had a capped o c t a h e d r a l (3:3:1) geometry about the molybdenum c e n t r e with an approximate 3- f o l d a x i s along the n e a r l y l i n e a r Ga**Mo—Cu atomic arrangement ( F i g . 4.0.) . The t h r e e CO l i g a n d s were e s s e n t i a l l y symmetric about t h i s a x i s . The s o l u t i o n IR spectrum of the Cu complex showed two c a r b o n y l bands at 1898 and 1798 c m - 1 (CH2Cl2)'v which were c o n s i s t e n t w i t h a C 3 V symmetry (a and e modes). The X-ray data suggested t h e r e were i n t e r a c t i o n s between the Cu c e n t r e and the c a r b o n y l carbons (the Cu-C d i s t a n c e s were 2.259(6), 2.274(7) and 2.419(6) A ) . The mean Mo-C-0 bond angles were near l i n e a r which i m p l i e d the i n t e r a c t i o n s were of the s e m i - b r i d g i n g type. The i n t e r a c t i o n Me r i p Ph Ph F i g u r e 4.0 3:3:1 S t r u c t u r e o f (MeGapz 3)(CO) 3MoCuPPh 3 72 between the Cu and Mo m o i e t i e s c o n s i s t e d of a d i r e c t Cu-Mo bond (2.5041(8) A) and some type of s e m i - b r i d g i n g c a r b o n y l i n t e r a c t i o n . The IR s p e c t r a of (HBpz" 3) (CO) 3M0CUPPI13 showed two c a r b o n y l s t r e t c h e s at 1885 and 1780 cm - 1 (THF) . The s i m i l a r i t y of the s p e c t r a of (MeGapz3) (CO) 3M0CUPPI13 and (HBpz'^) (CO) 3M0CUPPI13 suggested the p o s s i b i l i t y of s i m i l a r s t r u c t u r e s , t h a t was a 3:3:1 capped o c t a h e d r a l s t r u c t u r e with e q u i v a l e n t , s e m i - b r i d g i n g c a r b o n y l l i g a n d s . The r e a c t i o n of [ (HBpz"3) (CO^Mo]" with SnPh 3Cl gave a y e l l o w compound t h a t analysed as (HBpz"3)(CO)3MoSnPh3. A c r y s t a l s t r u c t u r e was not determined but i n f e r e n c e s were made by the examination of the X-ray c r y s t a l s t r u c t u r e of the analogous complex, (MeGapz3> (CO)3MoSnPh33^. The c r y s t a l s t r u c t u r e showed a capped o c t a h e d r a l (3:3:1) geometry about the Mo c e n t r e . An approximate C3 a x i s e x i s t e d along the Ga**Mo—Sn atomic arrangement with the CO l i g a n d s arranged symme t r i c a l l y about i t . The s o l i d s t a t e IR spectrum of t h i s complex showed t h r e e bands (1990, 1900 and 1875 cm - 1 ( N u j o l ) ) , which were c o n s i s t e n t with t e r m i n a l c a r b o n y l s . The C-0 bond lengths were w i t h i n the expected range f o r t e r m i n a l c a r b o n y l s (1.154(4), 1.139(3) and 1.141(3) A ) . The X-ray s t r u c t u r e showed t h a t one of the c a r b o n y l groups was s i g n i f i c a n t l y d i f f e r e n t from the other two due t o weak i n t e r m o l e c u l a r hydrogen bonding. T h i s would have brought about a departure from C3 symmetry i n the s o l i d s t a t e and caused s p l i t t i n g of the e mode thus e x p l a i n i n g the t h r e e 73 bands that were seen i n the IR spectrum. The inte r a c t i o n between the Mo and Sn moieties consisted s o l e l y of a d i r e c t Mo-Sn bond (2.8579(3) A). The solution IR spectrum of (HBpz'^) (CO) 3MoSnPh3 showed two carbonyl stretches at 1955 and 1865 cm - 1 (THF). The two carbonyl bands i n the IR spectra indicated a C 3 V symmetry and the carbonyl band positions suggested terminal carbonyl ligands. A 3:3:1 capped octahedral structure with three equivalent terminal carbonyl ligands was surmised. The reaction of [(HBpz"3) (CO)3M0]~ with SnMe 3Cl gave a yellowish-brown compound that analysed as (HBpz'^)(CO)3M0- S n M e 3 - The Ga analog of t h i s complex was made but an X-ray c r y s t a l structure has not been determined. The solution IR spectra of the two complexes were sim i l a r and showed three terminal carbonyls. This suggested structures s i m i l a r to (MeGapz 3)(CO) 3 MoSnPh3. The reaction of [ (HBpz"3) (CO^Mo] - with GePh 3Cl gave an orange compound that analysed as (HBpz'^)(CO)3MoGePh3. The solution IR spectrum of t h i s compound showed two carbonyl stretches at 2000 and 1915 cm - 1 (THF) . The two carbonyl bands i n the IR spectra indicated a C 3 V symmetry and the carbonyl band positions suggested terminal carbonyl ligands. A 3:3:1 capped octahedral structure with three equivalent terminal carbonyl ligands was surmised. 74 4.4 C o n c l u s i o n S e v e r a l new h e t e r o b i m e t a l l i c complexes i n c o r p o r a t i n g the p y r a z o l y l based molybdenum anion, [ (HBpz"3) (CO^Mo] - have been s y n t h e s i s e d . Inferences about t h e i r s t r u c t u r e s have been made by comparing IR s p e c t r a with the [(MeGapz3)(CO)3M0]~ analogs, f o r which the c r y s t a l s t r u c t u r e s are known. The s t r u c t u r e s appeared t o be a l l capped o c t a h e d r a l s t r u c t u r e s (3:3:1) c e n t r e d about molybdenum. The Mo-Cu complex had s e m i - b r i d g i n g i n t e r a c t i o n s of the c a r b o n y l l i g a n d s with the two metals where the Mo-Sn and Mo-Ge complexes showed only t e r m i n a l c a r b o n y l l i g a n d s . 75 Chapter V Summary The v e r s a t i l i t y of the p y r a z o l y l based l i g a n d systems has been demonstrated by the t h r e e d i f f e r e n t s t u d i e s p r e s e n t e d i n t h i s t h e s i s . In chapter 2 the r e a c t i v e pocket of a t r a n s i t i o n metal complex i n c o r p o r a t i n g an i n t e r m e d i a t e , s t e r i c a l l y h i n d e r e d p y r a z o l y l b o r a t e l i g a n d was probed by p r e p a r i n g a s e r i e s of compounds with l e s s s t e r i c a l l y h i n d e r e d l i g a n d s . These mixed-ligand metal complexes were c h a r a c t e r i s e d by m i c r o a n a l y s i s , mass spectrometry, X-ray c r y s t a l l o g r a p h y and e l e c t r o n i c spectroscopy. The mass spectrometry study showed t h a t the l i g a n d s [HBpz^] -, [HBpz'^] - and [MeGapz3]~ formed s t r o n g e r bonds t o n i c k e l and c o b a l t than d i d the s t e r i c a l l y h i n d e r e d [HBpz*3]~ l i g a n d . The e l e c t r o n i c spectroscopy study showed the s t e r i c bulk of the s u b s t r a t e t r i d e n t a t e l i g a n d s determined the s t r e n g t h of bonding t o the metal c e n t r e . The c r y s t a l s t r u c t u r e of the f o u r c o o r d i n a t e s t a r t i n g compound, HBpz*3CoCl showed a t r i g o n a l pyramidal s t u c t u r e . The t r a n s i t i o n e n e r g i e s d e r i v e d from the e l e c t r o n i c spectrum of the n i c k e l analog, HBpz*3NiCl compared f a v o r a b l y with the p r e d i c t e d t r a n s i t i o n s f o r a t e t r a h e d r a l l i g a n d f i e l d model. The c r y s t a l s t r u c t u r e o f the s i x c o o r d i n a t e complex, HBpz*3Nipz"3BH showed a near o c t a h e d r a l arrangement of the two t r i s - c h e l a t i n g p y r a z o l y l l i g a n d s . The c r y s t a l s t r u c t u r e 76 a l s o showed a c o n f o r m a t i o n a l change i n the bulky l i g a n d brought about by complexation of a s u b s t r a t e l i g a n d . The t r a n s i t i o n e n e r g i e s d e r i v e d from the e l e c t r o n i c spectrum of the n i c k e l complex, HBpz*3Nipz"3BH compared f a v o r a b l y with the p r e d i c t e d t r a n s i t i o n s f o r an o c t a h e d r a l l i g a n d f i e l d model. The s t u c t u r e of the f i v e c o o r d i n a t e s p e c i e s was not determined and needs f u r t h e r study. The numerous s u b s t i t u t i o n a l p o s s i b i l i t i e s w i l l p r o v i d e many more in t e r m e d i a t e l i g a n d metal complexes f o r f u t u r e s t u d i e s . The square p l a n a r rhodium[I] complexes, Me2Gapz(EA)Rh(CO) and Me2Gapz(but)Rh(CO) underwent o x i d a t i v e a d d i t i o n s of Mel, I2 and a l l y l bromide. These complexes a l s o underwent a d d i t i o n r e a c t i o n s with ethene and carbon monoxide. The complexes were t e s t e d f o r C-H bond a c t i v a t i o n but no a c t i v i t y was observed. The s u b t l e t y of s u b s t i t u t i o n s on the l i g a n d systems and t h e i r subsequent e f f e c t on r e a c t i v i t y was demonstrated by comparing the o x i d a t i v e a d d i t i o n of Mel t o the complexes, Me 2Gapz(OCH 2CH 2NH2)Rh(CO) and Me2Gapz(0CH 2CH2NMe2)Rh(CO). The l a t t e r underwent a c a r b o n y l i n s e r t i o n and d i f f e r s from the former only i n t h a t the n i t r o g e n donor group was methyl s u b s t i t u t e d . Again the s u b s t i t u t i o n a l p o s s i b i l i t i e s on the l i g a n d system w i l l p r o v i d e many more compounds t o be t e s t e d f o r c a t a l y t i c a c t i v i t y . In the f o u r t h chapter s e v e r a l new compounds were s y n t h e s i z e d with d i r e c t metal-metal bonds. One of the metal m o i e t i e s was the molybdenum anion, [HBpz"3(CO)3M0]~, 77 i n c o r p o r a t i n g the t r 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 . R e a c t i o n with t r a n s i t i o n metal h a l i d e s produced complexes wit h Mo-Cu, Mo-Sn and Mo-Ge bonds. The s t r u c t u r e s were surmised by comparisons of IR s p e c t r a w i t h complexes of known s t r u c t u r e s . The s t r u c t u r e s seemed t o be capped octahedrons (3:3:1) about the molybdenum c e n t r e . The HBpz"3(CO)3MoCuPPh3 complex had s e m i - b r i d g i n g i n t e r a c t i o n s of the c a r b o n y l l i g a i j d s between both metals while the complexes HBpz" 3(CO) 3MoGePh3 and HBpz" 3(CO)3MoSnR 3 (R = Me, Ph) had only t e r m i n a l c a r b o n y l s . Future s t u d i e s w i l l most c e r t a i n l y i n v o l v e other t r a n s i t i o n metals and s u b s t i t u t e d p y r a z o l y l based l i g a n d s . 78 References 1 S. Trofimenko, A c c t s . Chem. Res. 4., 17 (1971). 2 S. Trofimenko, Chem. Rev. 22, 497 (1972). 3 A. Shaver, J . Organomet. Chem. L i b r . 3, 157 (1977). 4 S. Trofimenko, Inorg. Chem. 3_4, 115 (1986) . 5 S. Trofimenko, J . Amer. Chem. Soc. 89./ 6288 (1967) . 6 S. Trofimenko, Inorg. Synth. 12., 99 (1970). 7 S. Trofimenko, J . Amer. Chem. Soc. 89, 3170 (1967). 8 J.C. Calabrese, S. Trofimenko and J.S. Thompson, J . Chem. Soc. Chem. Commun., 1122 (1986). 9 S. Nussbaum, S.J. R e t t i g , A. S t o r r and J . T r o t t e r , Can. J . Chem. 61, 692 (1984). 10 B.M. Louie, S.J. R e t t i g , A. S t o r r and J . T r o t t e r , Can. J . Chem. 62, 1057 (1984). 11 K.R. B r e a k e l l , S.J. R e t t i g , D.L. S i n g b e i l , A. S t o r r and J . T r o t t e r , Can. J . Chem. 56/ 2099 (1978). 12 K.S. Chong, S.J. R e t t i g , A. S t o r r and J . T r o t t e r , Can. J . Chem. 56, 1212 (1978). 13 S. Trofimenko, J.C. Calabrese and J.S. Thompson, Inorg. Chem. 26, 1507 (1987). 14 S. Trofimenko, J.C. Calabrese, P.J. Domaille and J.S. Thompson, Inorg. Chem. 28, 1091 (1989). 15 A. S t o r r and B.S. Thomas, Can. J . Chem. 48, 3667 (1970). 16 H. Schmidbauer and W. F i n d e i s s , Angew. Chem. I n t . Ed. 3, 696 (1964). 17 G.Dedichen, Ber. 39, 1831 (1906). 79 18 S. Trofimenko, J . Amer. Chem. Soc. 92., 5118 (1970). 19 D.A. Cooper, Molybdenum, Rhenium and Rhodium Complexes of P y r a z o l y l g a l l a t e Ligands. MSc T h e s i s , U.B.C. (1985). 20 M.R. Litzow and T.R. Spalding, Mass Spectrometry of Inorganic and Organometallic Compounds, American E l s e v i e r P u b l i s h i n g Co. Inc., New York (1973). 21 A.B.P. Lever, Inorganic E l e c t r o n i c Spectroscopy Ed.), E l s e v i e r Science P u b l i s h i n g Co. Inc., New York (1986). 22 M. C i a m p o l i n i , Inorg. Chem. 5, No. 1 (1965). 23 L. Sacconi, P. P a o l e t t i and M. C i a m p o l i n i , J . Amer. Soc. 85, 411 (1963). 24 K.S. Chong, T r a n s i t i o n Metal D e r i v a t i v e s of Asymmetric P y r a z o l y l g a l l a t e Ligands, Ph.D. T h e s i s , U.B.C. (1980) . 25 I. B e r t i n i , M. C i a m p o l i n i , P. Dapporto and D. G a t t e s c h i , Inorg. Chem. 11, No. 9, 2254 (1972) . 26 B.R. James, Homogeneous Hydrogenation, Wiley (1973). 27 I. Wender and P. Pino, Eds., Organic S y n t h e s i s v i a Metal Carbonyls. 1 (1968); 2 (1976), Wiley. 28 B. C r i s t e n s e n and M.S. S c u r r e l e , J . Chem. Soc. Faraday, 2036 (1977) . 29 C.K. Gosh and W.A.G. Graham, J . Amer. Chem. Soc. 109. 4726 (1987). 30 C. B i a n c h i n i , D. Masi, A. M e l i , M. P e r u z z i n i and F. Zanob i n i , J . Amer. Chem. Soc. 110, 6411 (1988). 31 B.M. Louie, S.J. R e t t i g , A. S t o r r and J . T r o t t e r , Can. J . Chem. 63, 3019 (1985). 32 E. O n y i r i u k a and A. S t o r r , Can. J . Chem. 65, 1367 (1987). 33 D.A. Cooper, S.J. R e t t i g and A. S t o r r , Can. J . Chem. 64/ 566 (1986). 80 34 L. Carlton, W.E. L i n d s e l l , K.J. McCullough and P.N. Preston, J. Chem. Soc. Dalton Trans. 1693 (1984). 35 G.A. Banta, B.M. Louie, E.C. Onyiriuka, S.J. Rettig and A. Storr, Can. J. Chem. 64/ 373 (1986). 36 E.C. Onyiriuka, S.J. Rettig and A Storr, Can. J. Chem. 64/ 321 (1986). 37 Y.Y. Liu, A.Mar, S.J. Rettig, A Storr and J. Trotter, Can. J. Chem 66./ 1997 (1988) . 38 G. Costa, E. Reisenhofer and L. Stefani, J. Inorg. Nucl. Chem. 27, 2581 (1965). 39 F.A. Cotton, Inorg. Chem. 3, 702 (1964). 40 K.F. Pu r c e l l and J.C. Kotz, Inorganic Chemistry, W.B. Saunders Company, P h i l i d e l p h i a (1977) . 41 E.C. Onyiriuka, Pyrazolyl Ligands i n Mixed Metal Complexes, Ph. D. Thesis, U.B.C. (1986). 42 L. Carlton, W.E. L i n d s e l l , K.J. McCullough and P.N. Preston, Organomet. 4, 1138 (1985). 43 J.A. Riddick and W.B. Burger, Organic Solvents, Physical Properties and Methods of P u r i f i c a t i o n , 3rd ed.. Techniques of Chemistry Vol. II, Wiley (1970). 81 Appendix 1 C r y s t a l Grower c 82 11 Appendix 2 I s o t o p i c C l u s t e r s of B, Ga Br and CI 68 7 9 BA 22 10 201 B 71 37 CI Ga B r 261 182 B r 3 B 2 B r 2 B s 171 00 Br 2 B B r B m / e I s o t o p i c C l u s t e r s of B, Ga Br and C l 331 267 250 Br4B Br3BCI Br3B m/e 400 321 2*0 161 •iHllllil.i •HHlll.i JliuL Jl i_ B r 4 G a B B r , G a B B r 2 G a B B r G a B  85 B o n d 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 B o n d L e n g t h ( A ) B o n d L e n g t h ( A ) B r ( 1 ) - C ( 2 ) 1 . 8 7 4 ( 1 0 ) N ( 3 ) - B 1 . 5 4 0 ( 8 ) B r ( 2 ) - C ( 5 ) 1 . 8 7 6 ( 7 ) N ( 4 ) - C ( 6 ) 1 . 3 4 7 ( 9 ) C o - C l 2 . 2 0 7 ( 3 ) C ( 1 ) - C ( 2 ) 1 . 3 5 2 ( 1 5 ) C o - N ( 2 ) 2 . 0 5 7 ( 9 ) C ( 2 ) - C ( 3 ) 1 . 3 9 7 ( 13) C o - N U ) 2 . 0 3 9 ( 6 ) C ( 3 ) - C ( 7 ) 1 . 5 2 ( 2 ) N O ) - N ( 2 ) 1 . 3 8 5 ( 1 1 ) C ( 4 ) - C ( 5 ) 1 . 3 6 0 ( 1 0 ) N O ) - C ( l ) 1 . 3 5 8 ( 1 2 ) C ( 5 ) - C ( 6 ) 1 . 3 8 1 ( 1 1 ) N( 1 ) - B 1 . 5 1 4 ( 1 3 ) C ( 6 ) - C ( 9 ) 1 . 5 1 0 ( 1 0 ) N ( 2 ) - C ( 3 ) 1 . 3 0 9 ( 13) C ( 7 ) - C ( 8 ) 1 . 5 1 3 ( 1 1 ) N ( 3 ) - N ( 4 ) 1 . 3 8 3 ( 8 ) C ( 9 ) - C ( 1 0 ) 1 . 544 ( 1 4 ) N ( 3 ) - C ( 4 ) 1 . 3 3 2 ( 8 ) C ( 9 ) - C ( 1 1 ) 1 . 5 2 5 ( 1 5 ) B o n d a n g l e s ( d e g ) 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 B o n d s A n g l e ( d e g ) B o n d s A n g l e ( d e g ) C l - C o -N(2) 1 2 2 . 7 ( 3 ) CO ) - C ( 2 ) - C ( 3 ) 1 0 6 . 8 ( 9 ) C l - C o -N(4) 1 2 1 . 8 ( 2 ) N ( 2 ) - C ( 3 ) - C ( 2 ) 1 0 8 . 9 ( 9 ) C l - C o - N ( 4 ) ' 1 2 1 . 8 ( 2 ) N ( 2 ) - C ( 3 ) - C ( 7 ) 1 2 2 . 8 ( 9 ) N ( 2 ) - C o -N(4) 9 4 . 1 ( 2 ) C ( 2 ) - C ( 3 ) - C ( 7 ) 1 2 8 . 3 ( 9 ) N ( 2 ) - C o - N U ) ' 9 4 . 1 ( 2 ) N(3)-CU)-C(5) 1 0 8 . 3 ( 6 ) N ( 4 ) - C o - N ( 4 ) ' 9 4 . 9 ( 3 ) Br(2) -C(5) -CU) 126 .5 (6 ) N(2)-N(1] -CO) 107 .5 (9 ) B r ( 2 ) - C ( 5 ) - C ( 6 ) 126.3(5) N(2)-N(1] i - B 121.9(7) C(4)-C(5)-C(6) 107 .2 (6 ) CO ) - N ( l ] • -B 130.6(9) N(4)-C(6)-C(5) 108.7(6) CO -N(2] l-NO) 109.3(6) N(4)-C(6)-C(9) 122.7(7) Co -N(2] l-C(3) 142.3(7) C(5)-C(6)-C(9) 126.6(7) N( 1)-N(2l >-C(3) 108.4(8) C(3)-C(7)-C(8) 111.6(6) N(4)-N(3 >-C(4) 109.3(5) C(3)-C(7)-C(8)' 111.6(6) N(4)-N(3 l-B 120.5(6) C(8)-C(7)-C(8)' 110.900) C(4)-N(3 l-B 130.2(6) C(6)-C(9)-CO0) 109.8(8) Co -W(4 |-N(3) 110.6(4) C(6)-C(9)-C(11) 112.7(8) Co -N(4] l-C(6) 142.8(5) C(10)-C(9)-COD 110.9(8) N(3)-N(4' •-C(6) 106.5(6) NO)-B -N(3) 110.2(5) NO ) - C ( 1 )-C(2) 108.4(9) N(1)-B -N(3)' 110.2(5) BrO ) - C ( 2 ) - C ( 1) 125.9(7) N(3)-B -N(3)* 109.2(7) BrO ) - C ( 2 ) - C ( 3 ) 127.3(8) 86 F i n a l p o s i t i o n a l ( f r a c t i o n a l x 10*; Br, Co, CI x 10 s) and i s o t r o p i c thermal parameters (U x 10 3 A 2) with estimated standard deviations i n parentheses Atom X y z U eg Br ( D 0 56130(10) 33034 45 Br(2) 32108( 5) -2959( 9) -27(10) 57 Co 0 1747(13) 2422503) 30 CI 0 -1 1245(23) 35014(18) 43 N( 1 ) 0 2622( 7) 1 794 ( 5) 32 N(2) 0 2056( 8) 2583( 6) 37 N(3) 861 ( 4) 1070( 5) 927( 4) 33 N(4) 1031 ( 4) 196( 5) 1 546( 4) 36 C O ) 0 3858( 9) 1 927 ( 7) 33 C(2) 0 4065( 8) 2774( 7) 26 C(3) 0 291 2 ( 8) 31 69( 7) 32 C(4) 1 535 ( 5) 1 046 ( 7) 355( 5) 35 C(5) 2138( 5) 148( 7) 581 ( 5) 35 C(6) 1821 ( 5) -365( 7) 1328( 5) 37 C(7) 0 2621(10) 4115( 8) 44 C(8) 855( 7) 1926( 8) 4375( 5) 59 C(9) 2249( 6) -1374( 8) 1857( 6) 61 COO) 1 623 ( 8) -2522( 8) 1852( 7) 78 C O D 2455( 7) -964(11) 2765( 7) 76 B 0 1889( 9) 975( 7) 29 87 68 E m p i r i c a l Formula Formula Weight C r y s t a l System L a t t i c e P a r a m e t e r s : Space Group Z v a l u e D c a l c F000 mu(Mo K-alpha) Di f f T a c t o m e t e r R a d i a t i o n Temperature 2-theta(max) No. O b s e r v a t i o n s (I>2.00(sig(I))) No. V a r i a b l e s R e s i d u a l s : R; Rw Goodness o f F i t I n d i c a t o r Maximum S h i f t i n F i n a l Cycle L a r g e s t Peak i n F i n a l D i f f . Map C(33)H(47)B(2)Br(3)N(12)Ni(l) 931.85 Orthorhombic a - 20.65 (1) angstroms b « 29.158 (3) angstroms c - 13.306 (2) angstroms V - 8011 (4) angstroms**3 Pbca (#61) 8 1.55 g/cm**3 3776 34.90 cm**-l Rigaku AFC6 Mo K-alpha (lambda- 0.71069) Graphite-monochromated 21 degrees Cent. 50.0 degrees 1976 460 0.054; 0.048 1.37 0.09 0.50 e/angstrom**3 I n t r a m o l e c u l a r D i s t a n c e s I n v o l v i n g t h e N o n h y d r o g e n A t o m s a t o m a t o m d i s t a n c e a t o m a t o m d i s t a n c e B r ( l ) C ( 2 ) 1.89(1) N(9) N ( 1 0 ) 1.37(2) B r ( 2 ) C ( 5 ) 1.90(1) N ( 9 ) B ( 2 ) 1 . 4 9 ( 2 ) B r ( 3 ) C ( 6 ) 1.86(1) N ( 1 0 ) C(15) 1 . 3 3 ( 2 ) N i N(12) 2.05(1) N ( l l ) C(16) 1 .34(2) . N i N ( 8 ) 2.07(1) N ( l l ) N(12) 1.36(1) N i N ( 1 0 ) 2.08(1) N ( l l ) B(2) 1.54(2) N i N ( 4 ) 2.13(1); N(12) C(18) 1.34(2) N i N ( 2 ) 2.15(1 ) v C ( l ) C(2) 1 . 3 5 ( 2 ) N i N ( 6 ) 2 . 1 6 ( 1 ) C ( 2 ) C ( 3 ) 1 . 3 9 ( 2 ) N ( l ) . N ( 2 ) 1 . 3 5 ( 1 ) C ( 3 ) C(19) 1 . 5 2 ( 2 ) N ( l ) C ( l ) 1 . 3 5 ( 1 ) C ( 4 ) C ( 5 ) 1 . 3 5 ( 2 ) N ( l ) B ( l ) 1 . 5 3 ( 2 ) C ( 5 ) C ( 6 ) 1 . 3 5 ( 2 ) N(2 ) C ( 3 ) 1 . 3 4 ( 2 ) C ( 6 ) C ( 2 2 ) 1 . 5 1 ( 2 ) N ( 3 ) C ( 4 ) 1 . 3 2 ( 1 ) C ( 7 ) C ( 8 ) 1 . 3 7 ( 2 ) N( 3) N( 4 ) 1 . 3 7 ( 1 ) C ( 8 ) C ( 9 ) 1 . 3 9 ( 2 ) N ( 3 ) B ( l ) 1 . 5 4 ( 2 ) C ( 9 ) C ( 2 5 ) 1 . 5 5 ( 2 ) N ( 4 ) C ( 6 ) 1 . 38 (2 ) C ( 1 0 ) C ( l l ) 1 . 3 3 ( 2 ) N ( 5 ) C ( 7 ) 1 . 3 4 ( 1 ) C ( 1 0 ) C(28) 1.51(2) N ( 5 ) N ( 6 ) 1.38(1) C ( l l ) C(12) 1.41(2) N(5) B ( l ) 1.51(2) C(12) C(29) 1.52(2) N(6) C(9) 1.32(2) C(13) C(14) 1.34(2) N(7) C(10) 1.35(2) C(13) C(30) 1.49(2) NO) N(8) 1.37(1) C(14) C(15) 1.42(2) N(7) B(2) 1.53(2) C(15) C(31) 1.50(2) N(8) C(12) 1.30(2) C(16) C(17) 1.35(2) N(9) C(13) 1.36(2) C(16) C(32) 1.52(2) Distances are i n angstroms. Estimated standard d e v i a t i o n s i n the l e a s t s i g n i f i c a n t f i g u r e are given i n parentheses. I n t r a m o l e c u l a r Distances I n v o l v i n g the Nonhydrogen Atoms 9 0 atom atom d i s t a n c e atom atom d i s t a n c e C ( 1 7 ) C ( 1 8 ) 1 . 3 8 ( 2 ) C ( 1 8 ) C ( 3 3 ) 1 . 5 1 ( 2 ) C ( 1 9 ) C ( 2 1 ) 1 - 5 2 ( 2 ) C ( 1 9 ) C ( 2 0 ) 1 . 5 4 ( 2 ) C ( 2 2 ) C ( 2 3 ) 1 . 5 0 ( 2 ) C ( 2 2 ) C ( 2 4 ) 1 . 5 6 ( 2 ) C ( 2 5 ) C ( 2 6 ) 1 . 5 1 ( 2 ) C ( 2 5 ) C ( 2 7 ) 1 . 5 3 ( 2 ) Distances are i n angstroms. Estimated standard d e v i a t i o n s i n the l e a s t s i g n i f i c a n t f i g u r e are given i n parentheses. I n t r a m o l e c u l a r B o n d A n g l e s I n v o l v i n g t h e N o n h y d r o g e n Atomt, a t o m a t o m a t o m a n g l e a t o m a t o m a t o m a n g l e N ( 1 2 ) N i N ( 8 ) 88 . 3 ( 5 ) C ( 6 ) N( 4 ) N i 1 4 0 ( 1 ) N{12) N i N ( 1 0 ) 89 . 7 ( 5 ) C ( 7 ) N ( 5 ) N ( 6 ) 1 0 8 ( 1 ) N ( 1 2 ) N i N (4 ) 89.8 (5 ) C ( 7 ) N ( 5 ) B ( l ) 1 3 0 ( 1 ) N ( 1 2 ) N i N ( 2 ) 9 1.6 ( 5 ) N(6) N ( 5 ) B ( l ) 1 2 2 ( 1 ) N ( 1 2 ) N i N ( 6 ) 179 . 2 ( 4 ) C (9 ) N(6) N ( 5 ) 1 0 7 ( 1 ) N ( 8 ) N i N ( 1 0 ) 88.7 (5 ) C (9 ) N(6) N i 1 4 0 ( 1 ) N(6) N i N ( 4 ) 9 1.8 ( 5 ) N ( 5 ) N(6) N i 1 1 3 ( 1 ) N ( 8 ) N i N ( 2 ) 1 7 9 . 7 ( 7 ) C ( 1 0 ) N ( 7 ) N ( 8 ) 1 0 9 ( 1 ) N ( 8 ) N i N ( 6 ) 9 1 . 1 ( 5 ) C ( 1 0 ) N ( 7 ) B ( 2 ) 1 3 4 ( 1 ) N (10 ) N i N ( 4 ) 1 7 9 . 3 ( 5 ) N ( 8 ) N ( 7 ) B ( 2 ) 1 1 7 ( 1 ) N ( 1 0 ) N i N ( 2 ) 9 1 . 0 ( 5 ) C ( 1 2 ) N ( 8 ) N ( 7 ) 1 0 7 ( 1 ) N ( 1 0 ) N i N ( 6 ) 9 0 . 8 ( 5 ) C ( 1 2 ) N ( 8 ) N i 1 3 6 ( 1 ) N<4 ) N i N ( 2 ) 8 8 . 4 ( 5 ) N'.7 ) N ( 8 ) N i 1 1 7 ( 1 ) N(4 ) N i N ( 6 ) 8 9 . 7 ( 4 ) C ( 1 3 ) N(9) N ( 1 0 ) 1 0 7 ( 1 ) N ( 2 ) N i N ( 6 ) 8 8 . 9 ( 5 ) C ( 1 3 ) N(9 ) B ( 2 ) 1 3 4 ( 2 ) N ( 2 ) N ( l ) C ( l ) 1 1 1 ( 1 ) N ( 1 0 ) N(9) B ( 2 ) 1 1 9 ( 1 ) N ( 2 ) N ( l ) B ( l ) 1 2 3 ( 1 ) C ( 1 5 ) N ( 1 0 ) N(9) 1 1 0 ( 1 ) C ( l ) N ( l ) B ( l ) 1 2 7 ( 1 ) C ( 1 5 ) N ( 1 0 ) N i 1 3 5 ( 1 ) C (3 ) N ( 2 ) N ( l ) 1 0 7 ( 1 ) N ( 9 ) N ( 1 0 ) N i 1 1 5 ( 1 ) C(3) N(2) N i 141(1) C(16) N ( l l ) N ( 1 2 ) 1 1 0 ( 1 ) M(l) N ( 2 ) N i 112.8(8) C(16) N ( l l ) B ( 2 ) 132 ( 2 ) C(4) N ( 3 ) H(4) 111(1) N ( 1 2 ) N ( l l ) B(2) 117 ( 1 ) C(4) N ( 3 ) B ( l ) 129(1) C(18) M(12) N ( l l ) 105 ( 1 ) M(4) N(3) B ( l ) 120(1) C(18) M(12) N i 137 ( 1 ) M(3) N<4) C(6) 105(1) N ( l l ) N(12) N i 117 ( 1 ) N(3) N ( 4 ) N i 115(1) C (2 ) C ( l ) N ( l ) 1 0 7 ( 1 ) Angles are i n degrees. Estimated standard d e v i a t i o n s i n the l e a s t s i g n i f i c a n t f i g u r e are giv e n i n parentheses. I n t r a m o l e c u l a r B o n d A n g l e s I n v o l v i n g t h e N o n h y d r o g e n A t o m s a t o m a t o m a t o m a n g l e a t o m a t o m a t o m a n g l e C ( l ) C ( 2 ) C ( 3 ) 1 0 7 ( 1 ) C ( l l ) C ( 1 2 ) C ( 2 9 ) 1 2 6 ( 2 ) C ( l ) C ( 2 ) B r ( l ) 1 2 5 ( 1 ) C ( 1 4 ) C ( 1 3 ) N ( 9 ) 1 0 9 ( 2 ) C ( 3 ) C ( 2 ) B r ( l ) 128 (1 ) C ( 1 4 ) C ( 1 3 ) C ( 3 0 ) 1 3 0 ( 2 ) N ( 2 ) C ( 3 ) C ( 2 ) 1 0 9 ( 1 ) N ( 9 ) C ( 1 3 ) C ( 3 0 ) 1 2 1 ( 2 ) N ( 2 ) C ( 3 ) C ( 1 9 ) 1 2 1 ( 1 ) C ( 1 3 ) C ( 1 4 ) C ( 1 5 ) 1 0 7 ( 1 ) C ( 2 ) C ( 3 ) C ( 1 9 ) 1 3 0 ( 1 ) N ( 1 0 ) C ( 1 5 ) C ( 1 4 ) 1 0 6 ( 2 ) N ( 3 ) C ( 4 ) C(5) 108 (1 ) N ( 1 0 ) C ( 1 5 ) C ( 3 1 ) 1 2 5 ( 2 ) C ( 6 ) C ( 5 ) C ( 4 ) 1 0 6 ( 1 ) C ( 1 4 ) C ( 1 5 ) C ( 3 1 ) 1 2 9 ( 2 ) C ( 6 ) C ( 5 ) B r ( 2 ) 1 2 9 ( 1 ) N ( l l ) C ( 1 6 ) C ( 1 7 ) 1 0 9 ( 2 ) C ( 4 ) ' C ( S ) B r ( 2 ) 1 2 3 ( 1 ) N ( l l ) C ( 1 6 ) C ( 3 2 ) 1 2 3 ( 2 ) C ( 5 ) C ( 6 ) N ( 4 ) 1 0 8 ( 1 ) C ( 1 7 ) C ( 1 6 ) C ( 3 2 ) 1 2 9 ( 2 ) C ( 5 ) C ( 6 ) C ( 2 2 ) 1 2 9 ( 1 ) C ( 1 6 ) C ( 1 7 ) C ( 1 8 ) 1 0 5 ( 1 ) N ( 4 ) C ( 6 ) C ( 2 2 ) 1 2 2 ( 1 ) N ( 1 2 ) C ( 1 8 ) C ( 1 7 ) 1 1 1 ( 2 ) N ( 5 ) C(7) C ( 8 ) 1 0 9 ( 1 ) N ( 1 2 ) C ( 1 8 ) C ( 3 3 ) 1 2 2 ( 2 ) C ( 7 ) C(8) C ( 9 ) 1 0 5 ( 1 ) C ( 1 7 ) C ( 1 8 ) C ( 3 3 ) 1 2 8 ( 2 ) C ( 7 ) C ( 8 ) B r ( 3 ) 1 2 4 ( 1 ) C ( 3 ) C ( 1 9 ) C ( 2 1 ) 1 1 3 ( 2 ) C ( 9 ) C ( 8 ) B r ( 3 ) 1 3 1 ( 1 ) C ( 3 ) C ( 1 9 ) C ( 2 0 ) 1 1 2 ( 2 ) N ( 6 ) C ( 9 ) C ( 8 ) 1 1 0 ( 1 ) C ( 2 1 ) C ( 1 9 ) C ( 2 0 ) 1 0 7 ( 1 ) N ( 6 ) C ( 9 ) C ( 2 5 ) 1 2 4 ( 2 ) C ( 2 3 ) C ( 2 2 ) C ( 6 ) 1 1 3 ( 1 ) C(8) C(9) C(25) 126(1) C(23) C(22) C(24) 1 0 8 ( 1 ) C ( l l ) C(10) H(7) 108(1) C(6) C(22) C(24) 111 ( 1 ) C ( l l ) C(10) C(26) 131(1) C(26) C(25) C(27) 111 (1 ) H(7) C(10) C(28) 121(1) C(26) C(25) C(9) 113(1) C(10) C ( l l ) C(12) 106(1) C(27) C(25) C(9) 110 (1 ) M(8) C(12) C ( l l ) 109(1) W(5) B ( l ) N ( l ) 1 1 0 ( 1 ) N(8) C(12) C(29) 125(1) H(5) B ( l ) N ( 3 ) 1 1 0 ( 1 ) Angles are i n degrees. Estimated standard d e v i a t i o n s i n the l e a s t s i g n i f i c a n t f i g u r e are gi v e n i n parentheses. I n t r a m o l e c u l a r Bond A n g l e s I n v o l v i n g the Nonhydrogen Atoms 9 3 atom atom atom a n g l e atom atom atom a n g l e N ( l ) B ( l ) N(3) 109(1) N(9) B(2) N(7) 111(1) N(9) B(2) N ( l l ) 110(1) N(7) B(2) N(1D 110(1) 0 Angles are i n degrees. Estimated standard d e v i a t i o n s i n the l e a s t s i g n i f i c a n t f i g u r e are gi v e n i n parentheses.

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