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The synthesis and characterization of tridentate polypyrazolylgallate and borate ligands and their transition… Breakell, Kenneth Ross 1978

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THE SYNTHESIS AND CHARACTERIZATION OF TRIDENTATE POLYPYRAZOLYLGALLATE AND BORATE LIGANDS AND THEIR TRANSITION METAL DERIVATIVES by KENNETH ROSS BREAKELL B . S c , U n i v e r s i t y of B r i t i s h Columbia, 1974 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 C h e m i s t r y ) We accept t h i s t h e s i s as conforming to the r e q u i r e d s t a n d a r d THE UNIVERSITY OF BRITISH COLUMBIA J u l y , 1978 (c) Kenneth Ross B r e a k e l l , 1978 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of Brit ish 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 representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department of Chemistry The University of Brit ish Columbia 2075 Wesbrook Place Vancouver, Canada V6T 1W5 i i ABSTRACT The a n i o n i c t r i d e n t a t e c h e l a t i n g l i g a n d s [MeGa(pz)^] > [MeGa(dmpz) ] , and [MeGa(mpz)^] have been s y n t h e s i z e d and t h e i r c o o r d i n a t i v e p r o p e r t i e s s t u d i e d . The [MeGa(pz)g] l i g a n d a c t s as a s i x - e l e c t r o n c h e l a t i n g l i g a n d to d i v a l e n t t r a n s i t i o n m e t a l i o n s g i v i n g com-p l e x e s of the type [MeGa(pz) ] 2M (M=Mn,Co,Ni,Cu,Zn), b e l i e v e d to possess an o c t a h e d r a l MN^ c o r e . The l i g a n d a l s o forms numerous c a r b o n y l complexes w i t h Mn, Mo and W. The t r i d e n t a t e c h e l a t i n g n a t u r e of t h i s new l i g a n d has been demonstrated through a c r y s t a l s t r u c t u r e d e t e r m i n a t i o n of the complex [ M e G a ( p z ) 3 ] M o ( C O ) 2 ( n 3 - C 3 H 5 ) . The [MeGa(dmpz)^] l i g a n d a l s o forms c a r b o n y l com-p l e x e s of Mn, Mo and W. ' The ready c o n v e r s i o n of t h i s l i g a n d to the l e s s s t e r i c a l l y demanding t r i s - c h e l a t i n g "hydroxy" l i g a n d [MeGa(dmpz) 2(OH)]"occurs i n the attempted s y n t h e s i s of " n 3 - a l l y l " complexes [MeGa (dmpz ) ]M (CO) 2 " r | 3 - a l l y l " (where M=Mo or W, " n 3 - a l l y l " = 1 3 - C 3 H 5 , n 3 - C 4 H 7 ) . The t r i d e n t a t e che-l a t i n g n a t u r e of t h i s "hydroxy" l i g a n d i s c o n c l u s i v e l y demon-s t r a t e d i n the c r y s t a l s t r u c t u r e d e t e r m i n a t i o n of the complex [MeGa (dmpz) 2 (OH) ]Mo ( C 0 ) 2 ( r i 3 - C ^ H ^ ) . The [MeGa(mpz)^] l i g a n d forms t r a n s i t i o n m e tal com-p l e x e s of the type [MeGa(mpz)^] 2M (M=Co,Ni) and a l s o c a r b o n y l complexes of Mo and W. Less d e f i n i t i v e r e s u l t s were o b t a i n e d w i t h t h i s l i g a n d , as c h a r a c t e r i z a t i o n of the r e s u l t i n g com-p l e x e s was c o m p l i c a t e d by the i n a b i l i t y to s e p a r a t e the isomers i i i p o s s i b l e f o r each complex The s y n t h e s i s of the [ R^B(OCH^CH^NR^) ( p z ) ] " (R=H, Me) l i g a n d s and t h e i r r e a c t i o n w i t h d i v a l e n t t r a n s i t i o n m e t a l i o n s i s a l s o d e s c r i b e d . In t h i s c a s e , the o n l y p r o d u c t s i s o -l a t e d were the p r e v i o u s l y c h a r a c t e r i z e d [B.^B(pz)^]^ and [ H B ( p z ) 3 ] 2 M (M=Co,Ni, Cu,Zn) complexes. F i n a l l y , d e t a i l s of the s y n t h e s i s and c h a r a c t e r i z a -t i o n of the [ R 2 G a ( C H 3 C 0 2 ) ] and [R 2Ga(C^HgNC0 2)] (R=Me,Et) compounds are g i v e n . The c r y s t a l s t r u c t u r e of the [Me 2Ga(C^ HgNC0 2)] d e r i v a t i v e c o n s i s t e d of monomeric u n i t s l i n k e d to two o t h e r s by weak Ga-0 bonds to form a c h a i n - l i k e p o l y m e r i c s t r u c t u r e . The g a l l i u m atom i n t h i s compound i s f i v e -c o o r d i n a t e and has d i s t o r t e d t r i g o n a l b i p y r a m i d a l geometry. i v TABLE OF CONTENTS T i t l e Page A b s t r a c t Table of Contents L i s t of Tables L i s t of F i g u r e s Acknowledgement A b b r e v i a t i o n s and Common Names CHAPTER I . INTRODUCTION CHAPTER I I . GENERAL TECHNIQUES AND STARTING MATERIALS A. G e n e r a l Techniques 2-1 H a n d l i n g of Reagents 2-2 S p e c t r a 2-3 A n a l y t i c a l Methods a. Carbon, Hydrogen and N i t r o g e n b. H y d r o l y s a b l e Hydrogen or Alkane c. G a l l i u m (aluminum) A n a l y s i s B. S t a r t i n g M a t e r i a l s 2-4 2-5 2-6 2-7 2-8 2-9 Commerical Prepa r e d P r e p a r a t i o n of D i b o r a n e , ^ H ^ P r e p a r a t i o n of T r i a c e t y l b o r a t e , ( C H 3 C 0 2 ) 3 B P r e p a r a t i o n of G a l l i u m T r i c h l o r i d e , GaCl„ P r e p a r a t i o n of the Sodium S a l t s of P y r a z o l e , 3 - m e t h y l p y r a z o l e and 3,5 d i m e t h y l p y r a z o l e 2-10 P r e p a r a t i o n of L i t h i u m G a l l i u m H y d r i d e , LiGaH^ 2-11 P r e p a r a t i o n of T r i m e t h y l a m i n e G a l l a n e , Me 3NGaH 3 2-12 P r e p a r a t i o n of Dihy d r o ( 1 - p y r a z o l y l ) g a l l a n e dimer, [H2Ga(pz)]2 2-13 P r e p a r a t i o n of T r i m e t h y l g a l l i u m , Me 3Ga 2-14 P r e p a r a t i o n of T r i e t h y l g a l l i u m , E t 3 G a 2—15 P r e p a r a t i o n of M e t h y I d i c h l o r o g a l l a n e , MeGaCl 2 PAGE i i i i v v i i i x x i i i x i v 1 33 33 33 36 37 37 37 37 38 38 40 40 41 41 44 44 46 47 47 50 52 V PAGE 2-16 • .'Preparation of Dimolybdenum ( I I ) 54 t e t r a a c e t a t e , Mo2(CH3C0 2)4 2-17 P r e p a r a t i o n of T r i c a r b o n y l t r i s ( a c e t o - 55 n i t r i l o ) molybdenum(o) and T r i -c a r b o n y l t r i s ( a c e t o n i t r i l o ) Tungsten ( o ) ; (CH 3CN)3 M 0(CO) 3 and ( C H 3CN)3 W(CO)3 CHAPTER I I I . THE [ M e G a ( p z ) j " LIGAND AND ITS 56 PYRAZOLYL SUBSTITUTED DERIVATIVES. THEIR COORDINATION COMPOUNDS A. R e s u l t s and D i s c u s s i o n 56 3-1. The [ M e G a ( p z ) 3 ] " L i g a n d .. 56 3-2. The [MeGa(dmpz)3]~ L i g a n d 85 3-3. The [MeGa(mpz)3]" L i g a n d 109 B. S y n t h e t i c D e t a i l s I 3 0 3-4. S y n t h e s i s of N a + [ M e G a ( p z ) 3 ] " and 130 i t s P y r a z o l y l S u b s t i t u t e d D e r i v a t i v e s 3-5. S y n t h e s i s of [MeGa(pz)3] 2M and R e l a t e d 131 Complexes a. [ M e G a ( p z ) 3 ] 2 M (M=Mn,Fe,Cu,Zn) 131 Complexes b. [MeGa(dmpz)3] 2M (M=Co,Ni) 1 3 2 Complexes c. [MeGa(mpz)3] 2M (M=Co,Ni) 1 3 3 Complexes 3-6. R e a c t i o n of T i C l ^ w i t h Na [MeGa(pz) 3] 1 3 4 3-7. R e a c t i o n of ( n 5 - C 5 H 5 ) Fe (C0)' 2I w i t h 134 N a + [ M e G a ( p z ) 3 ] ~ 3-8. R e a c t i o n of ( n 3 - C 3 H 5 ) N i B r w i t h Na [Me 135 G a ( p z ) 3 ] -3-9. R e a c t i o n of M o 2 ( C H 3 C 0 2 ) 4 w i t h Na [Me 135 G a ( p z ) 3 ] _ 3-10. S y n t h e s i s of [MeGa(pz)3]Mn(CO)3 136 3-11. S y n t h e s i s of [MeGa(dmpz)3]Mn(CO)3 136 3-12. Attempted S y n t h e s i s of [MeGa(dmpz)3]CuCO 137 3-13. S y n t h e s i s of Na+[MeGa(pz)3 M(CO)3]" 137 (M=Cr,Mo,W) Complexes and T h e i r P y r a z o l y l S u b s t i t u t e d D e r i v a t i v e s a. N a +[MeGa(pz) 3M(CO)3]" (M=Mo,W,Cr) 137 Complexes b. Na +(MeGa(dmpz) 3M(CO) 3]- 140 (M=Mo,W,Cr) Complexes c. Na [MeGa(mpz)3M(CO) 3]" 141 £M=Mo,w) Complexes 3-14. S y n t h e s i s of [MeGa(pz)3]M(CO) 2N0 142 (M=Cr,Mo,W) Complexes and T h e i r P y r a z o l y l S u b s t i t u t e d D e r i v a t i v e s v i a. [MeGa(pz) 3]M(CO) 2 N 0 (M=Mo,W,Cr) Complexes b. [MeGa(dmpz) 3]M(CO) 2NO ; (M=Mo,W,Cr) Complexe s c. [MeGa(mpz) 3]M(CO) 2NO (M=Mo,W) Complexes 3-15. R e a c t i o n of N a + [ M e G a ( p z ) 3 M 0 ( C O ) 3 ] " w i t h [ C 6 H 5 N 2 ] + B F 4 -3-16. S y n t h e s i s of the [MeGa ( p z ) 3 ] M ( C O ) 2 Cn 3-C 3H 4R) (M=Cr,Mo,W; R=H,Me) Complexes and T h e i r P y r a z o l y l S u b s t i t u t e d D e r i v a t i v e s a. [ M e G a ( p z ) 3 ] M ( C 0 ) 2 ( n 3 - C 3 H 4 R ) (M=Mo,W,Cr; R=H,Me) Complexes b. [MeGa(dmpz) 3]M(CO) 2(n 3-C 3H 4R) (M=Mo,W,Cr R=H,Me) Complexes c. [MeGa(mpz) 3]M(CO) 2(n 3-C 3H4R) (M=Mo,W; R=H,Me) Complexes 3-17. S y n t h e s i s of [ M e G a ( p z ) 3 ] M ( C O ) 2 ( n 3 - C 3 H 4 R ) (M=Mo,W; R=H,Me) Complexes and T h e i r P y r a z o l y l S u b s t i t u t e d D e r i v a t i v e s from (CH 3CN) 3M ( C 0 ) 3 a. [ M e G a ( p z ) 3 ] W ( C 0 ) 2 ( n 3 - C 3 H 4 R ) (R=H,Me) Complexes b. [ M e G a ( d m p z ) 2 ( 0 H ) ] M ( C 0 ) 2 ( n - C 3 H 4 R ) (M=Mo,W; R=H,Me) Complexes CHAPTER IV. THE ATTEMPTED SYNTHESIS OF [H 2B ( 0 C H 2CH 2 N M e 2 ) ( p z ) ] " AND RELATED LIGANDS AND THEIR COORDINATION COMPOUNDS. A. R e s u l t s and D i s c u s s i o n B. S y n t h e t i c D e t a i l s 4-1. S y n t h e s i s of [HoB ( 0 C H 2CH 2NMe 2] 4-2. " S y n t h e s i s of Na^[ H-jB (pz ) ] ~ 4-3. S y n t h e s i s of N a + [ H 2 B ( p z ) 2 ] ~ from N a + [ H 3 B ( p z ) ] " + 4-4. R e a c t i o n of Na [ H 3 B ( p z ) ] w i t h HOCH 2CH 2NMe 2 a. Attempted S y n t h e s i s of [ H 2 B ( 0 C H 2 CH 2NMe 2)(pz)] 2 M (M=Co,Ni) Complexes 4-5. Attempted S y n t h e s i s of N a + [ H 2 B ( 0 C H 2 C H 2 N M e 2 ) ( p z ) ] _ from BH 3•THF and Na(pz) a. Attempted S y n t h e s i s of [H 2B ( 0 C H 2CH 2 NMe2 )'(pz ) ] 2M (M=Co,Ni,Cu) Complexes v i i PAGE 4-6. Attempted S y n t h e s i s of 168 Na +[H 2B(OCH 2CH 2NMe 2) ( p z ) ] " from BH3•THF and Na(OCH 2CH 2NMe 2). a. Attempted S y n t h e s i s of 169 [H2B(0CH 2CH 2NMe 2) (pz) ] 2M (M=Co,Ni,Cu,Zn) Complexes 4-7. Attempted S y n t h e s i s of Na +[H 2B(OCH 2CH 2 169 N M e 2 ) ( p z ) ] " from B 2 H 6 and Na(OCH 2CH 2NMe 2) a. Attempted S y n t h e s i s of [H 2B(OCH 2CH 2 170 N M e 2 ) ( p z ) ] 2 M (M=Co,Ni) Complexes b. Attempted S y n t h e s i s of [H2B(OCH 2CH 2 170 N M e 2 ) ( p z ) ] M o ( C O ) 2 ( n 3 - C 3 H 4 R ) (R=H,Me) Complexes 4-8. Attempted S y n t h e s i s of N a + [ H 2 B ( E A ) ( p z ) ] ~ 171 from B2H6 and Na(pz) a. Attempted S y n t h e s i s of [ H 2 B ( E A ) ( p z ) ] 2 M 172 (M=Co,Ni,Cu,Zn) Complexes 4- 9. Attempted S y n t h e s i s of N a + [ H 2 B ( E A ) ( p z ) ] ~ 173 from B 2 H 6 and Na(EA) a. Attempted S y n t h e s i s of [H 2B(EA) ( p z ) ] 2 M 173 (M=Co,Ni,Cu) Complexes b. Attempted S y n t h e s i s of [H 2B(EA) (pz)]Mo 174 ( C O ) 2 ( n 3 - C 3 H 4 R ) (R=H,Me) Complexes c. Attempted S y n t h e s i s of [ H 2 B ( E A ) ( p z ) ] 175 Mo(C0) 2N0 CHAPTER V. INVESTIGATIONS OF POTENTIALLY FIVE- 177 COORDINATE GALLIUM SYSTEMS A. R e s u l t s and D i s c u s s i o n 177 B. S y n t h e t i c D e t a i l s 192 5- 1. Attempted S y n t h e s i s of [ H 2 G a ( C H 3 C 0 2 ) ] 192 5-2. S y n t h e s i s of [ R 2 G a ( C H 3 C 0 2 ) ] (R=Me, Et) 192 5-3. S y n t h e s i s of [R 2Ga(C 4HgNC0 2)] 193 (R=Me,Et) 5-4. R e a c t i o n of [ H 2 G a ( p z ) ] 2 w i t h P y r a z o l e 194 CHAPTER V I . SUMMARY AND SUGGESTIONS FOR FUTURE WORK REFERENCES 195 201 v i i i LIST OF TABLES PAGE I E l e c t r o n e g a t i v i t i e s ( A l l r e d - R o c h o w ) 2 I I Degree of A s s o c i a t i o n of G a l l i u m D e r i v a t i v e s 4 i n Benzene S o l u t i o n I I I A n a l y t i c a l Data f o r Complexes I n c o r p o r a t i n g 74 the [ M e G a ( p z ) 3 ] ~ L i g a n d IV V S e l e c t e d Metal-Carbony1 S t r e t c h i n g F r e q u e n c i e s 75 1H N.M.R. Data f o r " A l l y l " and N i t r o s y l Com- 76 p l e x e s of the [ M e G a ( p z ) 3 ] " L i g a n d i n C 6D 6 S o l v e n t VI Mass S p e c t r a l Data f o r [ M e G a ( p z ) 3 ] 2 Z n 77 VI I Mass S p e c t r a l Data f o r [MeGa(pz) 3]Mn(CO) 78 V I I I Mass S p e c t r a l Data f o r [MeGa(pz)JMo(CO) 79 ( n 3 - c 3H 5) IX Mass S p e c t r a l Data f o r [MeGa(pz) 3]W(C0) 2N0 81 X A n a l y t i c a l and S e l e c t e d I.R. Data f o r Complexes 104 I n c o r p o r a t i n g the [MeGa(dmpz) 3]~ L i g a n d and i t s . Hydroxy D e r i v a t i v e XI S e l e c t e d M e t a l - C a r b o n y l S t r e t c h i n g F r e q u e n c i e s 105 X I I Mass S p e c t r a l Data f o r [MeGa(dmpz)„(OH)]Mo 106 ( c o ) 2 ( n 3 - c 4 H y ) X I I I 1H N.M.R. Data f o r the " A l l y l " and N i t r o s y l 108 Complexes of the [MeGa(dmpz)^]" L i g a n d and i t s Hydroxy D e r i v a t i v e i n CgDg S o l v e n t XIV A n a l y t i c a l Data f o r Complexes I n c o r p o r a t i n g 126 the [MeGa(mpz) 3]~ L i g a n d XV I.R. Data f o r Group VIb N i t r o s y l Complexes 127 i n Nuj o1 XVI Mass S p e c t r a l Data f o r [MeGa(mpz) 3] 2Co 128 XVII 1H N.M.R. Data f o r C a r b o n y l Complexes 129 [MeGa(mpz) 3]X (a) " A l l y l " Complexes i n C.Dg S o l v e n t , (b) N i t r o s y l Complexes i n CDC1 3 S o l v e n t i x LIST OF TABLES (cont'd) PAGE X V I I I A n a l y t i c a l Data f o r F i v e - C o o r d i n a t e G a l l i u m 189 Compounds XIX H N.M.R. Data f o r F i v e - C o o r d i n a t e G a l l i u m 1 9 0 C omp o und s (a) [R„Ga(CH 3C0 2)] (R=Me,Et) i n C 6D 6 S o l v e n t (b) [R 2Ga(C 4H 8 N C 0 2 )] (R=Me,Et) i n CDCI3 191 So l v e n t X LIST OF FIGURES PAGE 1. S t e r e o s c o p i c View of [MeN (CH^CH^O) ^ GaH] 2 6 2. S t e r e o s c o p i c View of [Me 2NCH 2CH 2OGaH 2] 2 7 S t e r e o s c o p i c View of [Me 2NCH 2CH 20GaMe 2] 2 7 3. [R 2B (pz) 2-Z ] S t r u c t u r e • (Z = BR 2 ,M, or H) 8 4. [ R 2 B ( p z ) ] 2 S t r u c t u r e 9 5. [ H 2 B ( p z ) 2 ] 2 M S t r u c t u r e 13 6. {HB(pz) ] 2M s t r u c t u r e 14 7. [ R B ( p z ) 3 ] M ( C O ) 2 X S t r u c t u r e 15 8. M o l e c u l a r S t r u c t u r e of [ D 2 G a ( p z ) ] 2 17 9. A S t e r e o v i e w of [ M e 2 G a ( p z ) ] 2 18 A S t e r e o v i e w of [ M e 2 G a ( m p z ) j 2 19 A S t e r e o v i e w of [ M e 2 G a ( I n d a z o l y 1 ) ] 2 19 A S t e r e o v e i w o f [Me 2Ga(dmpz)] 2 20 10. A S t e r e o v i e w of [Me 2Ga(OH)(dmpz)GaMe 2•2Hdmpz] 21 11. A S t e r e o v i e w of [ E t 2 G a ( 2 - m e t h y l - i m i d a z o l y 1 ) ] ^ 22 12. A S t e r e o v i e w of [ M e 2 G a ( p z ) 2 ] 2 N i 24 13. A S t e r e o v i e w of [ M e 2 G a ( p z ) 2 ] 2 C u 27 A S t e r e o v i e w of [ M e 2 G a ( d m p z ) 2 ] 2 C u 27 14. A S t e r e o v i e w of [ M e 3 G a 2 ( m p z ) 3 C u O ] 2 28 15. A S t e r e o v i e w of [Me 2Ga(0CH 2CH 2NMe 2) ( p z ) 2 C u ] 2 29 16. A S t e r e o v i e w of s y m . - f a c . [ M e ? G a ( E A ) ( p z ) ] g N l 31 A S t e r e o v i e w of mer. [ M e 2 G a ( E A ) ( p z ) ] 2 N i 31 17. Vacuum L i n e , P a r t A 34 Vacuum L i n e , P a r t B 35 18. G a l l i u m T r i c h l o r i d e Apparatus 43 19. F i l t r a t i o n - R e a c t i o n Apparatus 48 20. Me 3NGaH 3 Sublimer 49 21. E t 3 G a D i s t i l l a t i o n Apparatus 51 x i LIST OF FIGURES (cont'd) PAGE 22. MeGaC± 2 Apparatus g 3 23. [ M e G a ( p z ) 3 ] 2 M M o i e t y 5 6 24. I n f r a r e d Spectrum of [ M e G a ( p z ) 3 ] 2 Z n i n N u j o l 66 25. 100 MHz F.T. 1H N.M.R. Spectrum of [MeGa(pz)„]Mo(CO)„(n 3-C,H_) i n C,D, S o l v e n t 3 I J 5 6 6 26 . 100 MHz F.T. 3"H N.M.R. Spectrum of [MeGa(pz) 3]Mo(CO) 2N0 i n CgDg S o l v e n t 27. A S t e r e o v i e w of [ M e G a ( p z ) 3 ] M o ( C O ) 2 ( n 3 - C 3 H 5 ) 7 2 32. 100 MHz F.T. 1H N.M..R. Spectrum of 3 4 , 37. Schematic 1 H N.M.R. S p e c t r a of the [MeGa(mpz) 3]M(C0) 2N0 Isomers 38. 270 MHz 1H N.M.R. Spectrum of [MeGa(mpz)_]W(CO) oN0 i n C,D, S o l v e n t 3 z 6 b 67 83 28. T h e o r e t i c a l D i s t r i b u t i o n s of G a l l i u m I s o t o p e s 29. T h e o r e t i c a l D i s t r i b u t i o n s of Zn-Ga I s o t o p e s 34 30. T h e o r e t i c a l D i s t r i b u t i o n s of Mo-Ga and W-Ga g 4 I s o t o p e s 31. [MeGa(dmpz),]M M o i e t y j j n a u i B L j i g g 96 [MeGa(dmpz) 0]W(C0)„N0 i n C,D, S o l v e n t 3 / 6 0 33. 100 MHz F.T. 1H N.M.R. Spectrum of 9 7 [MeGa (dmpz ) 2 (OH) ]Mo (CO) 2 ( n -C 4H 7) i n CfiD S o l v e n t 270 MHz F.T. H N.M.R. Spectrum of 9 8 [MeGa(dmpz) 2(OH)]Mo(CO) 2(n ~C 3H 5) i n CgDg S o l v e n t (a) Expansion of r\ - a l l y l Region 99 35. A S t e r e o v i e w of [MeGa(dmpz)~(OH)]Mo(CO)„ 1 0 3 ( n 3 _ c 4 H 7 ) 36. Isomers of the [MeGa(mpz) 3]M M o i e t y l i r j _ C 4 - 1 119 122 (a) Expansion 0-5T 2.23 (b) Expansion 5-10T 224 x i i LIST OF FIGURES (cont'd) PAGE 39. M u l t i p l e B r e a k - S e a l Apparatus 139 40. [Me 2Ga(OCH 2CH 2NR 2)(pz)]M (R=H,Me) M o i e t y 154 41. P o s s i b l e S t r u c t u r e s f o r [-R?Ga (CH,C0 2 ) ] 178 (R=Me,Et) 42. [ R 2 G a ( C 4 H g N C 0 2 ) ] (R=Me,Et) S t r u c t u r e 182 43. (a) A S t e r e o v i e w of [Me 2Ga(C.H NC0„)] 184 (b) C r y s t a l S t r u c t u r e of [ M e 2 G a ( C 4 H g N C 0 2 ) ] 184 Viewed down _c> 44. 100 MHz F.T. 1H N.M.R. Spectrum of 188 [ E t 2 G a ( C 4 H g N C 0 2 ) ] I n CDC1 3 S o l v e n t x i i i ACKNOWLEDGEMENT I would l i k e to g r a t e f u l l y thank. Dr. A. S t o r r f o r h i s g uidance, encouragement and p a t i e n c e which c o n t r i b u t e d so immeasurably t o the success of t h i s work. I am p a r t i c u l a r l y i n d e b t e d to Dr. S.J. R e t t i g f o r h i s c r y s t a l s t r u c t ure work, and Mr. K.S. Chong f o r h i s h e l p -f u l d i s c u s s i o n s and enthusiasm. I a l s o thank M i s s J . L o u i e who typed t h i s t h e s i s and the t e c h n i c a l s t a f f of t h i s department. x i v ABBREVIATIONS AND COMMON NAMES o A : angstrom b.p. : b o i l i n g p o i n t °C : degrees c e n t r i g r a d e cm ^ : wavenumber i n r e c i p r o c a l c e n t i m e t e r s cm Hg : c e n t i m e t e r s of mercury diglyme : b i s ( 2 - m e t h o x y e t h y l ) e t h e r dmpz : 3 , 5 - d i m e t h y l p y r a z o l y l EA : ethanolamino Et : e t h y l F.T. : F o u r i e r t r a n s f o r m Hdmpz : 3,5-dimethylpyrazol.e Hmpz : 3 - m e t h y l p y r a z o l e Hpz : p y r a z o l e Hz : Hertz, c y c l e s per second I . R . ( i . r . ) : i n f r a r e d J : n u c l e a r magnetic resonance c o u p l i n g c o n s t a n t i n He r t z Me : methyl m/e : mass to charge r a t i o ml : m i l l i l i t e r mmoles : m i l l i m o l e s m.p. : m e l t i n g p o i n t mpz : m e t h y l p y r a z o l y l N.M.R. : n u c l e a r magnetic resonance (n . m. r . ) XV ABBREVIATIONS AND COMMON NAMES (cont'd) pz : p y r a z o l y l THF : t e t r a h y d r o f u r a n xis : excess A : warm or r e f l u x 3 TI : t r x h a p t o n"' : pentahapto V : s t r e t c h i n g f r e q u e n c y n.m.r. c h e m i c a l s h i f t i n p a r t s per m i l l i o n - 1 -CHAPTER I INTRODUCTION Group I I I A a l k y l and h y d r i d o compounds are known to r e a c t w i t h l i g a n d s c o n t a i n i n g a c t i v e hydrogen to produce adducts which r e a d i l y e l i m i n a t e a l k a n e or hydrogen to produce c o o r d i n a t i v e l y u n s a t u r a t e d i n t e r m e d i a t e s . The e l i m i n a t i o n of hydrogen from amine'and phosphine adducts of g a l l i u m h y d r i d e has been d i s c u s s e d ( 1 , 2 ) , and compounds of the type 'Me2NGaH2' and 'MeNHGaH2' (Me = CH^) have been s y n t h e s i z e d and c h a r a c -t e r i z e d ( 2 ) . In both c a s e s , the monomeric u n i t s o l i g o m e r i z e d to produce c o o r d i n a t i v e l y s a t u r a t e d c y c l i c d e r i v a t i v e s , the (Me2NGaH2) n b e i n g d i m e r i c i n benzene s o l u t i o n . T h i s tendency to o l i g o m e r i z e i s not s u r p r i s i n g i n l i g h t of the f a c t t h a t B, A l and Ga can r a i s e t h e i r c o o r d i n a t i o n number from 3 to 4 to a c h i e v e c o o r d i n a t i v e s a t u r a t i o n ( 3 ) . The mechanism of hydrogen e l i m i n a t i o n from compounds of the type MeNH 2EH 3 (E = B, A l , or Ga) has been suggested to occur v i a the f o l l o w i n g scheme due to Stone ( 4 ) : 6* 6. H H H H I I U I I Me — N — » E — H — ^ Me — N —> E — H > Me — N —> E - — H • H2 I I I I I I H H H H H H (1) I II - 2 -The e l e c t r i c a l s t r a i n i n the i n t e r m e d i a t e ( I ) i s r e l i e v e d on e l i m i n a t i o n of m o l e c u l a r hydrogen to y i e l d the c o o r d i n a t i v e l y u n s a t u r a t e d s p e c i e s ( I I ) . T h i s scheme i s based on the All r e d - R o c h o w e l e c t r o n e g a t i v i t y v a l u e s g i v e n i n Table I . TABLE I : E l e c t r o n e g a t i v i t i e s ( Allred-Rochow) N 3.0 7 A l 1.4 7 H 2.20 Ga 1.82 B 2.01 In 1.49 Hydrogen has a h i g h e r e l e c t r o n e g a t i v i t y (2.20) than those of the Group IIIA elements, which range from 2.01 to 1.44 as one goes down the group. T h i s causes the Group I I I A m e t a l p r o t o n to become h y d r i d i c . N i t r o g e n , on the o t h e r hand, has a much h i g h e r e l e c t r o n e g a t i v i t y (3.07) than hydrogen, and t h i s can be used to e x p l a i n the more a c i d i c n a t u r e of the n i t r o g e n bound p r o t o n . The e l e c t r o n e g a t i v i t i e s of the f i r s t t h r e e elements E i n c r e a s e i n the o r d e r A l , Ga, B. Thus, bond | ^ p o l a r i t y of the type „ u , and hence the h y d r i d i c c h a r a c t e r l i — r i i n EH^ and the ease of e l i m i n a t i o n s h o u l d i n c r e a s e from B through Ga to A l . T h i s i s indeed the case. The borane com-pound, MeNH^BH^, i s q u i t e s t a b l e at room temperature w i t h r e s p e c t to hydrogen l o s s , and compounds of the type MeNHBH2 can be prepare d from the pa r e n t compounds o n l y at e l e v a t e d temperatures ( 5 ) . Hydrogen e l i m i n a t i o n from the c o r r e s p o n d i n g - 3 -g a l l i u m compound, MeNR^GaH^ , o c c u r r e d r e a d i l y , even below room temperature to g i v e the f i n a l p r o d u c t , 'MeNHGaH^' ( 2 ) . The c o r r e s p o n d i n g a l a n e d e r i v a t i v e , 'MeNHAlH^', has not been i s o l a t e d , but r e a d i l y e l i m i n a t e s a f u r t h e r m o l e c u l e of hydro-gen to g i v e the p o l y ( i m i n o a l a n e ) , ( MeNAlH) n > a w h i t e s o l i d which i s i n s o l u b l e i n benzene ( 6 ) . A f t e r e l i m i n a t i o n of m o l e c u l a r hydrogen., c o o r d i n a t i v e s a t u r a t i o n of ( I I ) o c c u r s e i t h e r by c y c l i z a t i o n or c h a i n p o l y -m e r i z a t i o n as i n R i H 1 1 -N — I 1 — E-i 1 H I H o r , a l t e r n a t i v e l y , by m u l t i p l e bond f o r m a t i o n as i n H \ N: H H - 4 -S t e r i c f a c t o r s appear to p l a y a major r o l e here i n d e t e r m i n i n g which r o u t e the c o o r d i n a t i v e l y u n s a t u r a t e d i n t e r -mediate f o l l o w s . However, v a l e n c y angle s t r a i n , e n t r o p y e f f e c t s , and the n a t u r e of the r e a c t i o n i n t e r m e d i a t e s i n v o l v e d must a l s o be c o n s i d e r e d ( 3 , 7 ) . In the m a j o r i t y of c a s e s , c y c l i z a t i o n of the monomer u n i t o c c u r s . S e v e r a l s t u d i e s have been r e p o r t e d which i n v o l v e d changing the s i z e of the group on the amine and on the Group I I I A m e t a l (2,8-11) i n or d e r t o i n v e s t i g a t e these f a c t o r s . The g a l l i u m compounds l i s t e d i n Table I I p r o v i d e a good case f o r study ( 2 ) . TABLE I I Degrees of a s s o c i a t i o n of g a l l i u m d e r i v a t i v e s i n benzene s o l u t i o n H^NGaH^ ( i n s o l u b l e i n benzene) Polymer MeNHGaH2 3 MeNHGaMe £ 3 Me 2NGaMe 2 2 Me 2NGaH 2 2 The f o r m a t i o n of a l i n e a r p o l y m e r i c a m i n o g a l l a n e , ( H 2 N G a H 2 ) n , i s f e a s i b l e because of the v e r y low s t e r i c i n t e r -a c t i o n of the hydrogen atoms on a d j a c e n t g a l l i u m and n i t r o g e n atoms. With the i n t r o d u c t i o n of a methyl group on n i t r o g e n , a l i n e a r polymer would e x h i b i t c o n s i d e r a b l e s t e r i c crowding and c y c l i z a t i o n o c c u r s to g i v e a six-membered (Ga-N)^ r i n g system. The most s t a b l e isomer was p r e d i c t e d to be i n the - 5 -c y c l o h e x a n e - t y p e c h a i r c o n f o r m a t i o n w i t h a l l the N-Me groups e q u a t o r i a l . With the i n t r o d u c t i o n of two methyl groups on the g a l l i u m atom, as i n (MeNHGaMe2), the t r i m e r , w i t h no v a l e n c y a n g l e s t r a i n but some s t e r i c i n t e r a c t i o n , i s f a v o r e d over the dimer. However, w i t h the s u b s t i t u t i o n of two methyl groups on n i t r o g e n , (Me2NGaMe 2)2 adopts a d i m e r i c s t r u c t u r e w i t h c o n s i d e r a b l e v a l e n c y a n g l e s t r a i n but l i t t l e s t e r i c c rowding. I t i s i n t e r e s t i n g i n t h i s r e s p e c t t h a t s i m i l a r o r g a n o m e t a l l i c systems c o n t a i n i n g the l a r g e r donor atoms phosphorus and a r s e n i c , w i t h the d i m e t h y l m o i e t i e s of aluminum, g a l l i u m and indium adopt t r i m e r i c s t r u c t u r e s of the type (Me2?GaMe2)^(12). A l e s s e n i n g of s t e r i c i n t e r a c t i o n s w i t h the s u b s t i t u t i o n of the l a r g e r phosphorus atom f o r the n i t r o g e n atom i s s u f f i c i e n t to l e a d to the f o r m a t i o n of a t r i m e r r a t h e r than the a n g u l a r l y s t r a i n e d dimer. Another i n d i c a t i o n of the c r i t i c a l i t y of the s i z e of the donor atom i s e v i d e n c e d by the d i m e r i c n a t u r e of d i m e t h y l a m i n o g a l l a n e , ( M e 2NGaH2) 2( 1)J """N which the n i t r o g e n has two methyl groups a t t a c h e d . T h i s type of e l i m i n a t i o n r e a c t i o n has been extended to i n c l u d e a m i n o a l c o h o l s where the a c t i v e hydrogen i s a t t a c h e d to oxygen and/or n i t r o g e n atoms. In one s t u d y , N - m e t h y l d i e -thanolamine was r e a c t e d i n a 1:1 r a t i o w i t h t r i m e t h y l a m i n e -g a l l a n e i n benzene s o l v e n t at room temperature ( 1 3 ) ; MeN(CH 2CH 2OH) 2 + Me^NGaH^ MeN (CH 2CH 20) 2GaH +Me3N + 2H 2 (2) - 6 -Removal of a l l v o l a t i l e s gave a w h i t e , a i r - s e n s i t i v e s o l i d . The g a l l i u m i s c o o r d i n a t e d to the n i t r o g e n and two oxygen atoms of the a m i n o a l c o h o l to form a monomeric u n i t which d i -m e r i z e s through b r i d g i n g oxygen atoms to g i v e a d i s t o r t e d t r i g o n a l b i p y r a m i d a l arrangement about each f i v e - c o o r d i n a t e g a l l i u m atom and a four-membered Ga^O^ r i n g as shown i n f i g u r e 1: F i g u r e 1 HCAI S t e r e o s c o p i c view of [MeN(CH 2CH 20) 2GaH] A l t h o u g h f i v e - c o o r d i n a t e compounds of aluminum t r i -a l k y l s and t r i a r y l s w i t h s i m i l a r l i g a n d s are known ( 1 4 ) , t h i s dimer, [MeN(CH 2CH 20) 2GaH] 2, p r o v i d e d the f i r s t c r y s t a l l o g r a p h i c example of a f i v e - c o o r d i n a t e g a l l i u m complex. I t was thus p o s t u l a t e d t h a t s i m i l a r d e r i v a t i v e s employing the N,N-dimethyl-e t h a n o l a m i n o , "Me 2NCH 2CH 20", moiety as a l i g a n d might a l s o p r o v i d e examples of f i v e - c o o r d i n a t e g a l l i u m atoms i n c r y s t a l l i n e samples ( 1 5 ) . Two such compounds were prepar e d and c h a r a c -t e r i z e d ; the N,N-dimethylethanolamino g a l l a n e dimer, [Me 2NCH CH- OGaH 2]- 2, and the N , N - d i m e t h y l e t h a n o l amino d i m e t h y l -- 7 -g a l l i u m dimer, [Me^NCH^CH^OGaMe^]^• I n both compounds, the four-membered Ga^O^ r i n g encountered i n the p r e v i o u s work (13) i s a g a i n the c e n t r a l f e a t u r e , and c o o r d i n a t i o n of the n i t r o g e n atom g i v e s the pred i c t e d f i v e — c o o r d i n a t e g a l l i u m atoms i n a d i s t o r t e d t r i g o n a l b i p y r a m i d a l environment. Both s t r u c t u r e s are shown i n f i g u r e 2. F i g u r e 2 S t e r e o s c o p i c view of [Me NCH CH OGaH ] S t e r e o s c o p i c view of [MeJCH CH OGaMeJ - 8 -W i t h i n the past decade, e l i m i n a t i o n r e a c t i o n s of t h i s type i n v o l v i n g p y r a z o l e and boranes or borane adducts have been i n v e s t i g a t e d ( 1 6 ) . In the r e s u l t i n g compounds, a BR 2 group forms an i n t e r m o l e c u l a r b r i d g e between two p y r a z o l y l m o i e t i e s as shown i n F i g u r e 3. The a t t r a c t i v e n e s s of p y r a z o l e i s t h a t i t s geometry i s known to f a v o r the f o r m a t i o n of hydro-gen bonded dimers and t h i s . h e t e r o c y c l i c m o l e c u l e has gr e a t h y d r o l y t i c and o x i d a t i v e s t a b i l i t y ( 1 7 ) . F i g u r e 3 I Z = B R 2 n Z = M III Z = H S e v e r a l c l a s s e s of compounds are then o b t a i n e d , depending on the n a t u r e of the second b r i d g i n g u n i t . When Z i s BR^, then the r e s u l t i n g s t r u c t u r e i s a p y r a z a b o l e ( I ) . When Z i s a metal M, the compound belongs to the c l a s s of p o l y p y r a z o l y l b o r a t e s ( I I ) . F i n a l l y , when Z i s a hydrogen b r i d g e , the r e s u l t i s the c o r r e s p o n d i n g f r e e a c i d ( I I I ) . - 9 -P y r a z a b o l e s ( I ) (see F i g u r e 4) are n e u t r a l and r a t h e r s t a b l e h e t e r o c y c l e s . The s t r u c t u r e of the dimer i s f a v o r e d f o r both e l e c t r o n i c and s t e r i c r e a s o n s , and i s sup-p o r t e d by n.m.r. s t u d i e s ( 1 7 ) . Numerous resonance s t r u c t u r e s can be drawn i n c o r p o r a t i n g a p l a n a r arrangement about the n i t r o g e n atoms, and these are u s u a l l y summarized as i n F i g u r e 4. Such a s t r u c t u r e g i v e s d e l o c a l i z a t i o n of the 6TT e l e c t r o n s i n each of the p y r a z o l e r i n g s and of n e c e s s i t y demands e i t h e r a p l a n a r or boat B-(N-N) 2~B six-membered r i n g . A c h a i r arrangement f o r t h i s c e n t r a l six-membered r i n g d e s t r o y s the p l a n a r i t y about the n i t r o g e n atoms w i t h concomitant l o s s of s t a b i l i z a t i o n energy. As w i t h numerous o t h e r boron com-pounds, a t e t r a h e d r a l arrangement of atoms around boron would be c o n s i d e r e d as the most l i k e l y , and t h i s arrangement was - 10 -c o n s i s t e n t w i t h the n.m.r. s t u d i e s done on these compounds. P y r a z a b o l e s may be s y n t h e s i z e d from a p o l y p y r a z o l y l -b o r a t e a n i o n and a borane s p e c i e s c o n t a i n i n g a l e a v i n g group (18) : By a s u i t a b l e c h o i c e of p o l y p y r a z o l y l b o r a t e and borane components, a s y m m e t r i c a l l y s u b s t i t u t e d p y r a z a b o l e s may be p r e p a r e d . P y r a z a b o l e s where R=R' are s y n t h e s i z e d more con-v e n i e n t l y from p y r a z o l e and a borane (1 7 ) . 2 been D i v e r s e l y s y n t h e s i z e d by s u b s t i t u t e d s y m m e t r i c a l p y r a z a b o l e s have an a p p r o p r i a t e c h o i c e of s u b s t i t u t e d - 11 -p y r a z o l e and borane components ( 1 9 ) . Owing to the grea t s t a b i l i t y of the p y r a z a b o l e r i n g system i t has been p o s s i b l e to e f f e c t v a r i o u s t r a n s f o r m a t i o n s on f u n c t i o n a l groups a t t a c h e d to the 4 p o s i t i o n on the p y r a z o l y l moiety (e.g.; C -NH2 CNHCOR) m a i n t a i n i n g the r i n g system i n t a c t . P o l y p y r a z o l y l b o r a t e s ( I I ) b e l o n g to a c l a s s of u n i -n e g a t i v e t e t r a s u b s t i t u t e d boron compounds of g e n e r a l f o r m u l a and n=0, 1 or 2 ) . T h e i r s y n t h e s i s was f i r s t r e p o r t e d by S. Trofimenko ( 2 0 ) . They were shown to have e x c e l l e n t c h e l a t i n g a b i l i t y w i t h t r a n s i t i o n m etals and, i n a d d i t i o n , e x c e l l e n t h y d r o l y t i c and o x i d a t i v e s t a b i l i t y . The parent l i g a n d s ; [ H 2 B ( p z ) 2 ] , [ H B ( p z ) 3 ] , and [ B ( p z ) ^ ] were s y n t h e s i z e d by adding an a l k a l i m e t al b o r o h y d r i d e s a l t to an excess q u a n t i t y of molten p y r a z o l e . The degree of s u b s t i t u t i o n was c o n t r o l l e d by a d j u s t i n g the temperature a c c o r d i n g to the f o l l o w i n g scheme ( 2 1 ) : C-Br -»- C - L i -> C-CHO (or C-COOH) ; C-CN + C-COOH; C - N 0 2 -> [ R n B ( p z ) 4-n (where R=H, a l k y l ; pz = p y r a z o l y l = (N C H„), ^102°C - ^180° [BH.] + 2 Hpz [ H 2 B ( p z ) 2 ] Hpz [ H B ( p z ) 3 ] ^220 o (5) Hp z [ B ( p z ) 4 ] By c o n t a i n i n g C a -u s i n g a p p r o p r i a t e l y s u b s t i t u t e d p y r a z o l e s , l i g a n d s s u b s t i t u e n t s may be s y n t h e s i z e d by the same - 12 -g e n e r a l procedure (2 2 ) . L i g a n d s i n c o r p o r a t i n g 3 , 5 - d i m e t h y l -p y r a z o l e and 3 , 4 , 5 - t r i m e t h y l p y r a z o l e have been made i n t h i s manner. However, when 3 , 5 - d i m e t h y l p y r a z o l e was r e a c t e d w i t h the [BH^] s a l t , the r e a c t i o n h a l t e d at the t r i s u b s t i t u t i o n s t a g e . T h i s was a t t r i b u t e d to the a d d i t i o n a l m e t h y l groups on the p y r a z o l e which i n t r o d u c e too much s t e r i c s t r a i n around the boron f o r t e t r a s u b s t i t u t i o n to o c c u r . Boron s u b s t i t u t e d l i g a n d s are s y n t h e s i z e d by s t a r t i n g w i t h the a p p r o p r i a t e R^B or RBX 2 (where X = halogen) i n s t e a d of [BH^] . The o r d e r of replacement by p y r a z o l e i s i n g e n e r a l : HALOGEN •> H > ALKYL > ARYL S t e r i c f a c t o r s seem to p l a y a major r o l e i n con-t r o l l i n g the degree of s u b s t i t u t i o n here a l s o . Thus, r e a c -t i o n of t r i a l k y l b o r o n or t r i a r y l b o r o n compounds w i t h the py . r a z o l i d e a n i o n f o l l o w e d by excess p y r a z o l e proceeds as f a r as the d i s u b s t i t u t i o n s t a g e , v i z ( 2 2 ) . R 3B + [:(.pz)] ^ [ R 3 B ( p z ) ] H p Z > [ R 2 B ( p z ) 2 ] " + RH (6) A l k y l t r i s ( 1 - p y r a z o l y l ) b o r a t e s , [ R B ( p z ) 3 ] , how-ev e r , may be s y n t h e s i z e d by a l t e r n a t e r o u t e s . Thus, u s i n g RBX 2 as a s t a r t i n g compound to r e a c t w i t h the p y r a z o l i d e i o n g i v e s the [ R B ( p z ) 3 ] s p e c i e s . - 13 -The p a r e n t b i d e n t a t e l i g a n d , [I^B'Cpz)] , forms monomeric b i d e n t a t e c h e l a t e s , [R^B(pz) ]2M> w i t h most d i v a l e n t f i r s t - r o w t r a n s i t i o n m e t al i o n s , as shown i n f i g u r e 5. o r g a n i c s o l v e n t s and are a i r - s t a b l e , except f o r the F e ( I I ) and M n ( I I ) d e r i v a t i v e s . The isomorphous N i and Cu c h e l a t e s have a square p l a n a r MN^ geometry w h i l e the c h e l a t e s of Mn, Fe, Co and Zn are MN^ t e t r a h e d r a l . These assignments r e s t on o p t i c a l s p e c t r a , magnetic and n.m.r. d a t a ( 2 3 ) , and an x-ray s t r u c t u r a l d e t e r m i n a t i o n i n the case of [ H 2B (pz ) 2] 2Co (24) . A l k y l groups s u b s t i t u t e d on boron or p y r a z o l e en-hance the s t a b i l i t y of t h e s e c h e l a t e s . For example,.the i n t r o d u c t i o n of such groups at the t h r e e p o s i t i o n of the p y r a z o l y l group causes the F e ( I I ) and M n ( I I ) to become a i r s t a b l e . T h i s i s not s u r p r i s i n g , however, s i n c e t h e s e groups are o r i e n t e d i n such a way as to s c r e e n the m e t a l from a t t a c k F i g u r e 5 These s u b l i m a b l e compounds are s o l u b l e i n common - 14 •--by a t m o s p h e r i c oxygen. L i g a n d s [RBCpz)^] form compact o c t a h e d r a l compounds w i t h d i v a l e n t t r a n s i t i o n m e t a l s , as. shown i n f i g u r e 6. F i g u r e 6 R = H, a l k y l , a r y l , pz When the R group i s another p y r a z o l y l group, the [ B ( p z ) ^ ] l i g a n d remains t r i d e n t a t e . The s i m p l e s t compounds i n v o l v i n g a t r i d e n t a t e l i g a n d are the paren t [HB (pz) ^] ^M- d e r i v a t i v e s . They are a i r s t a b l e , s u b l i m a b l e i n vacuo, and s o l u b l e i n common o r g a n i c s o l v e n t s . The o v e r a l l D^^ symmetry f o r the s e compounds i s supporte d :by s p e c t r a l and n.m.r. da t a and has been c o n f i r m e d by the x-ray s t r u c t u r a l . d e t e r m i n a t i o n of [ H B ( p z ) ^ ] ^ C o ( 2 5 ) . The same h o l d s t r u e f o r compounds d e r i v e d from s y m m e t r i c a l l y s u b s t i t u t e d l i g a n d s . Analogous boron s u b s t i t u t e d compounds were made by r e a c t i n g a l k y l t r i s ( 1 - p y r a z o l y l ) b o r a t e s or a r y l t r i s ( 1 - p y r a z o l y l ) b o r a t e s w i t h the a p p r o p r i a t e d i v a l e n t t r a n s i t i o n m e t a l i o n ( 2 2 ) . These s u b s t i t u t e d d e r i v a t i v e s are - 15 -u s u a l l y more t h e r m a l l y s t a b l e than the paren t compounds. The [RBCpz)^] l i g a n d a l s o r e a c t s r e a d i l y w i t h many o r g a n o m e t a l l i c compounds y i e l d i n g d e r i v a t i v e s as e x e m p l i f i e d i n f i g u r e 7 (26,27): F i g u r e 7 * (where M=Cr, Mo, W, R=H, a l k y l , pz, X = n i t r o s o , a l l y l i c , or a r y l a z o l i g a n d s ) These compounds are analogous to the " h a l f - s a n d w i c h e s " based on the c y c l o p e n t a d i e n i d e l i g a n d . T h i s i s i l l u s t r a t e d w e l l by compounds d e r i v e d from the Group VIb h e x a c a r b o n y I s , e x p e c i a l l y those of molybdenum. In g e n e r a l , [ R B ( p z ) ^ ] compounds e x h i b i t g r e a t e r t h e r m a l and c h e m i c a l s t a b i l i t y than t h e i r n^-C^H,.- c o u n t e r p a r t s . For example, the h i g h l y c r y s t a l s l i n e , w h i t e [HB(pz)^]CuC0 i s . s t a b l e : . i n a i r f o r weeks, and r e s i s t s h e a t i n g to over 100°C ( 2 8 ) , and thus c o n t r a s t s w i t h the l a b i l e c y c l o p e n t a d i e n y l complex (n^-C H_)CuC0 ( 2 9 ) , 5 5 which has not y e t been o b t a i n e d pure. i t ' s tetraethylammonium s a l t , i s m o d e r a t e l y a i r s t a b l e f o r R = H or pz. Not s u r p r i s i n g l y , the presence of a l k y l groups i n the 3 p o s i t i o n of p y r a z o l e , as i n [HB(dmpz) Mo(CO) ] The a n i o n [RB(pz)„Mo(CO) ] , i s o l a t e d u s u a l l y as - 16 -(where dmpz = 3 , 5 - d i m e t h y l p y r a z o l e = ( ^ C ^ H ^ ) ) , makes the s e s a l t s i n d e f i n i t e l y a i r s t a b l e . The r e a c t i o n of [RB(pz) 3Mo ( C 0 ) 3 ] w i t h a l l y l i c h a l i d e s (C^^R'X; where R' = H, a l k y l 3 or a r y l , X = halogen) produces the "ri - a l l y l " d e r i v a t i v e s 3 [RB (pz ) 3 ]Mo (CO) 2 (n -C 3H 5R-'), w i t h o u t the i s o l a t i o n of an i n t e r m e d i a t e a - a l l y l s p e c i e s . A l t h o u g h the a n i o n [HB(dmpz) 3 ~ 3 Mo(CO) 3] f a i l e d to r e a c t w i t h a l l y l i c h a l i d e s , the "h - a l l y l " d e r i v a t e s were prepar e d by an i n d i r e c t r o u t e ( 3 0 ) . Once p r e p a r e d , many of these compounds are t h e r m a l l y s t a b l e beyond 250°C, and are thus the most t h e r m a l l y s t a b l e " n ^ - a l l y l " compounds known. N i t r o s o and a r y l a z o groups c o u l d be r e a d i l y a t t a c h e d to molybdenum by t r e a t i n g the [RB(pz)^Mo(CO) ] a n i o n w i t h a source of N0 + or w i t h A r N 2 + (31). In t h i s f a s h i o n the d e r i v a t i v e s [RB(pz) ]Mo(CO) 2N0 and [RB(pz) 3]Mo(CO) 2N=NAr were produced. The c r y s t a l s t r u c t u r e of [HB(pz) ]Mo(CO) 2N=N C,HC has been r e p o r t e d ( 3 2 ) . While n i t r o s y l a t i o n proceeded o -> e q u a l l y w e l l f o r the p a r e n t a n i o n s , [ R B ( p z ) ^ M o ( C O ) 3 ] (R=H, p z ) , and f o r the 3-methylated a n a l o g u e s , o n l y the p a r e n t anions r e a c t e d n o r m a l l y w i t h a r y l d i a z o n i u m s a l t s . The s t e r i c a l l y h i n d e r e d a n i o n gave, i n e x p i c a b l y , a b l u e product thought to be [ H B ( dmpz) 3]Mo(CO) 3Ar(33). P y r a z o l y l compounds i n v o l v i n g both h y d r i d o and organo d e r i v a t i v e s of aluminum and g a l l i u m have a l s o been s y n t h e s i z e d ( 3 4 ) . They were prepar e d by r e a c t i n g benzene s o l u t i o n s of the a p p r o p r i a t e aluminum or g a l l i u m compound w i t h a s t o i c h i o m e t r i c amount of p y r a z o l e i n the same s o l v e n t - 17 -at room temperature. [ H 2 G a ( p z ) ] 2 + 2Me 3N + 2H 2 (7) 2Me„Ga + 2 Hpz [Me 2Ga(pz) ]'2 + 2 CH (8) In the m a j o r i t y of eases hydrogen or a l k a n e e l i m i n a -t i o n o c c u r r e d at room temperature but i f the r a t e of r e a c t i o n was slow at t h i s temperature the benzene s o l u t i o n was heated under r e f l u x f o r a few hours to complete the r e a c t i o n . The m i l d e r c o n d i t i o n s r e q u i r e d f o r the f o r m a t i o n of these c y c l i c aluminum and g a l l i u m compounds compared to those n e c e s s a r y to produce p y r a z a b o l e s f o l l o w s the expected p a t t e r n . In a d d i -t i o n , the expected boat c o n f o r m a t i o n of the . c e n t r a l M-(N-N)2M r i n g has been c o n f i r m e d i n the c r y s t a l s t r u c t u r e d e t e r m i n a t i o n of [ D 2 G a ( p z ) ] 2 ( 3 5 ) . The m o l e c u l a r s t r u c t u r e of t h i s compound i s shown i n F i g u r e 8. F i g u r e 8 Gad) Cflf CB) Ga(2) 02) M o l e c u l a r S t r u c t u r e of [D Ga(N C H )] - 18 -The m o l e c u l e i s V-shaped, the angle between the unique p o r -t i o n of the m o l e c u l e and i t s c r y s t a l l o g r a p h i c m i r r o r image b e i n g 128.4°. The geometry of the c e n t r a l s y m m e t r i c a l Ga-fN-N^Ga r i n g i n t h i s c l a s s of.compound can be a l t e r e d by v a r y i n g the s u b s t i t u e n t s b oth on the g a l l i u m atoms and on the p y r a z o l y l b r i d g i n g m o i e t i e s (36,37). Here i t i s found t h a t changing the d e u t e r i u m f o r methyl groups on the g a l l i u m atoms and i n t r o d u c i n g s u b s t i t u e n t s on the b r i d g i n g l i g a n d s . c a u s e a pronounced f l a t t e n i n g of the Ga-CN-N^Ga boat c o n f o r m a t i o n found i n the o r i g i n a l [D2Ga(pz)J2 dimer (35 ) . The d e v i a t i o n from a t o t a l l y p l a n a r c o n f i g u r a t i o n f o r these m o l e c u l e s , an arrangement which would a l l o w d e l o c a l i z a t i o n of the 6TT e l e c t r o n s i n each of the b r i d g i n g p y r a z o l y l m o i e t i e s by p r e -s e r v i n g p l a n a r i t y of the bonds about the f o u r n i t r o g e n atoms, i s i n d i c a t e d by the V-angles as g i v e n i n F i g u r e 9. F i g u r e 9 A s t e r e o v i e w of [Me 2Ga ( N ^ j H ^ ) ] V angle 131.5° - 19 -F i g u r e 9 (cont'd) A s t e r e o v i e w 6 f\ [Me^Ga (^C^H,. ) ] V angl e 139.5° A s t e r e o v i e w of [Me^Ga (^C^H,. ) ] V angle of 147.8° - 20 -F i g u r e 9 (cont'd) A s t e r e o v i e w of [Me^Ga(N^C^H^)] V-angle 180° The l a r g e r the V-angle observed f o r a p a r t i c u l a r compound the f l a t t e r the boat c o n f o r m a t i o n f o r the Ga-(N-N>2Ga r i n g , u n t i l at a V-angle of 180°, a p l a n a r arrangement i s a t t a i n e d . The l a t t e r dimer, [Me^Ga(dmpz)] , i s of course q u i t e s t e r i c a l l y s t r a i n e d . I t i s t h i s s t r a i n which l e a d s to the f o r m a t i o n of a hydr.oxy-bridged s p e c i e s [Me2 Ga (OH) (^C^H.^) GaMe„ • 2N 0C CH 0] by a t t a c k of m o i s t u r e on the [Me.Ga(dmpz)] 0 Z A D O Z ' Z dimer. S t e r i c i n t e r a c t i o n s i n t h i s dimer are reduced by the replacement of one of the b r i d g i n g 3 , 5 - d i m e t h y l p y r a z o l y l m o i e t i e s w i t h a b r i d g i n g hydroxy group. The m o l e c u l a r s t r u c t u r e i s shown i n F i g u r e 10. As an e x t e n t i o n to t h i s type of s t u d y , the 2-methyl-i m i d a z o l y l d e r i v a t i v e s of Group I I I A d i a l k y l s were s y n t h e s i z e d by r e a c t i n g the a p p r o p r i a t e GroupIIIA t r i a l k y l w i t h a s t o i -c h i o m e t r i c e q u i v a l e n t of 2 - m e t h y l i m i d a z o l e , (^C^H^) , :*.in x y l e n e s o l v e n t ( 3 8 ) . 4R 3M + 4 N 2 C 4 H 6 X y l A 6 n £ t [ R 2 M - N 2 C 4 H 6 ] 4 + 4RH (9) (R = Me, M = B, A l , Ga, I n ; R=Et=(C 2H') , M = Ga) R e f l u x c o n d i t i o n s were used f o r a l l r e a c t i o n s and when the c l e a r x y l e n e s o l u t i o n was c o o l e d the pr o d u c t was d e p o s i t e d as - 22 -n e e d l e - l i k e c r y s t a l s . Only the aluminum d e r i v a t i v e was a i r s e n s i t i v e . M o l e c u l a r model s t u d i e s i n d i c a t e d t h a t the o n l y u n s t r a i n e d o l i g o m e r which c o u l d be c o n s t r u c t e d from the mono-mer u n i t would be the c y c l i c t e t r a m e r , and t h i s was c o n f i r m e d by the m o l e c u l a r s t r u c t u r e of the [Et„Ga (N„C,H r)1, d e r i v a t i v e I 2 4 5 4 ( 3 8 ) , which i s shown i n F i g u r e 11. F i g u r e 11 A s t e r e o v i e w of [Et„Ga(N C H )] Complexes i n v o l v i n g p o l y p y r a z o l y l d e r i v a t i v e s of the h e a v i e r Group I I I A elements have a l s o been s y n t h e s i z e d ( 3 9 ) . A n i o n i c c h e l a t i n g l i g a n d s were s y n t h e s i z e d and a number of t h e i r t r a n s i t i o n m e t a l complexes were s t u d i e d . ' The o bserved s t a b i l i t y of the "Me^Ga" m o i e t y i n the dimer [Me^Ga(pz)]^ (34) prompted the s y n t h e s i s of the sodium - 23 " d i m e t h y l b i s ( 1 - p y r a z o l y l ) g a l l a t e s a l t as o u t l i n e d below: NaH + Hpz THF Na(pz) + H 2 (10) Na(pz) + Me.Ga THF Na[Me.Ga (pz) ] ( I D Na[Me Ga ( p z ) ] + Hpz Na[Me 2Ga(pz) ] + CH (12) A f t e r removal of s o l v e n t the product was i s o l a t e d as a s l i g h t l y h y g r o s c o p i c w h i t e s o l i d , i n c o r p o r a t i n g the a i r - s t a b l e "Me^Ga" moiety. Use of excess p y r a z o l e i n e q u a t i o n 12 d i d not cause f u r t h e r s u b s t i t u t i o n at the g a l l i u m atom and the sodium d i -m e t h y l b i s ( 1 - p y r a z o l y l ) g a l l a t e s a l t remained as the o n l y product a f t e r removal of the v o l a t i l e s . Sodium d i m e t h y l b i s ( 3 , 5 - d i m e t h y l p y r a z o l y l ) g a l l a t e was a l s o p r e p a r e d s i m i l a r l y . With aluminum t r i a l k y l s , excess p y r a z o l e i n s t e p 3 caused l o s s of a l l a l k y l groups from the aluminum atom and f o r m a t i o n of the t e t r a k i s ( 1 - p y r a z o l y l ) a l u m i n a t e a n i o n , [ A l ( p z ) , ] . 4 T r a n s i t i o n m e t a l complexes of the two g a l l i u m l i g a n d s and the [ M e 2 B ( p z ) 2 ] l i g a n d were p r e p a r e d by the r e a c t i o n of s u i t a b l e t r a n s i t i o n m e t a l s a l t s and the l i g a n d s , f o l l o w e d by e x t r a c t i o n and r e c r y s t a l l i z a t i o n p r o c e d u r e s . B i s [ d i m e t h y l b i s ( 1 - p y r a z o l y l ) g a l l a t o ] n i c k e l ( I I ) was prepar e d from N a + [ M e 2 G a ( p z ) 2 ] and N i C l 2 i n aqueous s o l u t i o n . The complex was e x t r a c t e d w i t h e t h e r and r e c r y s t a l l i z e d from x y l e n e to y i e l d a i r - s t a b l e , orange c r y s t a l s s u i t a b l e f o r x-ray study ( 4 0 ) . As shown i n - 24 -F i g u r e 12, the two six-membered Ga^N-N^Ni r i n g s are i n a boat c o n f o r m a t i o n w i t h a p l a n a r arrangement of f o u r n i t r o g e n atoms about the n i c k e l atom which l i e s on a c r y s t a l l o g r a p h i c c e n t r e of symmetry, g i v i n g the whole m o l e c u l e a pseudo c h a i r con-f o r m a t i o n . F i g u r e 12 A s t e r e o v i e w of [Me Ga(N C H ) ] N i The v a r i a b l e temperature 1 H n.m.r. of t h i s square p l a n a r n i c k e l complex has demonstrated t h a t the m o l e c u l e s are s t e r e o c h e m i c a l l y n o n - r i g i d i n s o l u t i o n ( 4 1 ) . In the g a l l i u m m ethyl r e g i o n , two s i g n a l s are f e a t u r e d , one at a p o s i t i o n t y p i c a l f o r n o n - t r a n s i t i o n m e t a l d e r i v a t i v e s , and the o t h e r at much lower - c T v a l u e s . The m o l e c u l a r s t r u c t u r e g i v e n i n f i g u r e 12 shows two g a l l i u m m e t h y l groups i n p o s i t i o n s above and below the n i c k e l atom i n the NiN^ p l a n e , and i t i s these groups which are b e l i e v e d to g i v e the a b n o r m a l l y l o w - f i e l d - 2 5 " g a l l i u m m e t h y l s i g n a l by i n t e r a c t i o n w i t h the t r a n s i t i o n m e t a l . The r e m a i n i n g two g a l l i u m methyl groups are p o s i t -ioned away from the n i c k e l environment and g i v e a n.m.r. s i g n a l i n the expected r e g i o n . T h i s argument i s s i m i l a r to t h a t which Trofimenko had p r e s e n t e d e a r l i e r to e x p l a i n a d o w n f i e l d s h i f t of h a l f the methylene p r o t o n s i n the "''H n.m.r. s p e c t r a of the boron d e r i v a t i v e s [ R 2 B ( p z ) 2 ] 2 N i (22) (where R = e t h y l or n - b u t y l ) . An i n t e r a c t i o n of these p r o t o n s w i t h the n i c k e l atom accounted f o r the d o w n f i e l d s h i f t . In d i r e c t c o n t r a s t to the s i t u a t i o n f o r the n i c k e l d e r i v a t i v e s , however, a pronounced u p f i e l d s h i f t f o r one of the methylene groups i n the molybdenum com-3 p l e x [ ( E t ) 2 B ( p z ) 2 ] M o ( C O ) 2 (n - 2 - p h e n y l a l l y l ) , i s observed i n i t s % n.m.r. spectrum ( 4 2 ) . A g a i n , a boat c o n f o r m a t i o n f o r the B-(N-N)"2Mo r i n g was p r e d i c t e d , and Trofimenko suggested a s t r o n g i n t e r a c t i o n between the methylene group i n v o l v e d and the molybdenum atom to e x p l a i n the analomous n.m.r. s i g n a l . As f u r t h e r e v i d e n c e of e l e c t r o n d r i f t towards these methylene p r o t o n s and towards the t r a n s i t i o n m e t a l he c i t e s the appearance of some a b n o r m a l l y low v(CH) s t r e t c h i n g f r e q u e n c i e s i n the i n f r a - r e d spectrum of the complex i n s o l u t i o n . Con-f o r m a t i o n of these p r e d i c t i o n s was g i v e n i n the c r y s t a l s t r u c t u r e d e t e r m i n a t i o n of the complex ( 4 3 ) , which demon-s t r a t e d the e x i s t e n c e of a n o v e l C ••• H ••• Mo 3c-2e bond. In s o l u t i o n the two methylene p r o t o n s i n c l o s e p r o x i m i t y to the molybdenum atom were p o s t u l a t e d to be i n v o l v e d i n a r a p i d - 26 ~ s i t e - e x c h a n g e to p l a c e them both at the same h i g h f i e l d p o s i -t i o n i n the n.m.r. spectrum. In the square p l a n a r n i c k e l d e r i v a t i v e s a s i m i l a r m u l t i c e n t r e bonding i s not to be expected and the presence of e l e c t r o n d e n s i t y i n the n i c k e l o r b i t a l s above and below the N i N ^ : p l a n e may i n f a c t cause e l e c t r o n d r i f t away from the C-H p r o t o n s towards the carbon atoms, and hence cause a d e s h i e l d i n g of these p r o t o n s and move the p e r t i n e n t 1H n.m.r. s i g n a l s to the observed low-f i e l d v a l u e s . The c r y s t a l s t r u c t u r e s of the copper d e r i v a t i v e s [ M e 2 G a ( p z ) 2 ] 2 C u an^ [ M e 2 G a ( d m p z ) 2 ] 2 C u have a l s o been r e p o r t e d (44). As shown i n F i g u r e 13, the copper d e r i v a t i v e [ M e 2 G a ( p z ) 2 ] i s s i m i l a r to the n i c k e l complex [ M e 2 G a(pz ) 2 ] N i ( 4 0 ) . However, s t e r i c r e q u i r e m e n t s of the l i g a n d s i n [ M e 2 G a(dmpz)2 ] 2 C u n e c e s s i t a t e a d o p t i o n of p s e u d o t e t r a h e d r a l geometry about the c e n t r a l copper atom, and an almost p l a n a r arrangement f o r the Ga-{N-N)-9Cu six^membered r i n g s . - 28 -The s t e r i c r e q u i r e m e n t s of the d i m e t h y l b i s (3-methyl p y r a z o l y l ) g a l l a t e l i g a n d , [Me^Ga(mpz) 2] (where mpz = 3-m e t h y l p y r a z o l y l ) , were a l s o i n v e s t i g a t e d ( 4 5 ) . The r e a c t i o n of the sodium s a l t of t h i s l i g a n d w i t h CuBr 2 i n THF d i d not y i e l d the expected b i s copper ( I I ) complex, [ M e ^ G a ( m p z ) 2 ] » but r a t h e r , a n o v e l b i n u c l e a r copper ( I I ) complex [Me 2Ga 2 (mpzJ^CuO]^* i n c o r p o r a t i n g t r i g o n a l p l a n a r oxygen atoms and "Me^GaCmpz)" and "MeGaCmpz)^" m o i e t i e s as shown i n F i g u r e 14. The copper atoms have d i s t o r t e d square p y r a m i d a l geometry b e i n g bonded to f o u r n i t r o g e n atoms and one oxygen atom. F i g u r e 14 A s t e r e o v i e w of [Me 3Ga 2(N^^W^) 3CuO] The l i g a n d s . [M^B (dmpz-) 2 ] , [ M e 2 A l ( p z ) 2 ] , [ A l ( p z ) 4 ] ,' [ H 2 G a ( p z ) 2 ] , and [ M e 2 I n ( p z ) 2 ] were a l l i n -v e s t i g a t e d for- t h e i r p o t e n t i a l c h e l a t i n g p r o p e r t i e s towards - 29 " t r a n s i t i o n m etals but no s i m p l e t r a n s i t i o n m e t a l complexes w e r e . i s o l a t e d ( 3 9 ) . R e c e n t l y , the s y n t h e s i s and c h a r a c t e r i z a t i o n of t r a n s i t i o n m e t a l d e r i v a t i v e s of the a n i o n i c t r i d e n t a t e l i g a n d d i m e t h y l (N,N-dimethylethanolamino) ( 1 - p y r a z o l y l ) g a l l a t e , [Me2:Ga (OGH 2CH 2NMe 2) (pz) ] , have been r e p o r t e d ( 4 6 ) . The r e a c t i o n of t h i s u n s y m m e t r i c a l l i g a n d w i t h the d i v a l e n t t r a n s i t i o n m e t a l i o n s Co ( I I ) , N i ( I I ) , C u ( I I ) , and Z n X l I ) r e s u l t e d i n b i n u c l e a r t r a n s i t i o n m e tal complexes i n s t e a d of the expected mononuclear complexes. The m o l e c u l a r s t r u c t u r e of the C u ( I I ) complex i s shown i n F i g u r e 15. F i g u r e 15 A s t e r e o v i e w of [ M e ^ a (OCH 2CH 2NMe 2 ) ( N ^ H ^ ) 2Cu] 2 - 30 -The s y n t h e s i s of the l e s s s t e r i c a l l y demanding a n i o n i c t r i d e n t a t e l i g a n d , d i m e t h y l ( ethano lamino )'(1-py r az o l y 1) g a l l a t e , [Me^Ga(OCH^CR^NH^)(pz)] , and i t s c o o r d i n a t i n g p r o -2+ p e r t i e s towards s e l e c t e d t r a n s i t i o n m e t a l i o n s , M (M = Mn, Fe, Co, N i , Cu or Zn) has a l s o been r e p o r t e d ( 4 7 ) . The .use of ethanolamine i n s t e a d of N, N - d i m e t h y l e t h a n o l a m i n e i n the l i g a n d s y n t h e s i s was prompted by a d e s i r e to reduce s t e r i c crowding around the amino n i t r o g e n atom. The i s o l a t i o n and c h a r a c t e r i z a t i o n of a number of o c t a h e d r a l complexes has demonstrated the c h e l a t i n g a b i l i t y of t h i s new l i g a n d and • a l s o i t s v e r s a t i l i t y i n t h a t i t i s c a pable of a c t i n g e i t h e r as a f a c i a l or m e r i d i o n a l l i g a n d . When the l i g a n d i s f a c i a l , the n o n - p o l a r sym ( a l l t r a n s ) i s o m e r . i s p r e f e r r e d f o r o c t a -h e d r a l complexes. The m o l e c u l a r s t r u c t u r e s of both the p u r p l e , c r y s t a l l i n e s y m - f a c - b i s [ d i m e t h y 1 ( e t h a n o l a m i n o ) ( 1 - p y r a z o l y l ) g a l l a t e ( N ( 2 ) , 0, N)] n i c k e l ( I I ) isomer and the b l u e c r y s t a l -l i n e m e r i d i o n a l isomer are shown i n F i g u r e 16. - 32 -The f i r s t p a r t of t h i s t h e s i s d e s c r i b e s the p r e ^ p a r a t i o n of the t h r e e n o v e l a n i o n i c p o l y p y r a z o l y l g a l l a t e l i g a n d s [MeGaCpz)^] , [MeGa(dmpz)^] , and [MeGaCmpz)^] , and an i n v e s t i g a t i o n of t h e i r c h e l a t i n g p r o p e r t i e s towards s e l e c t e d 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 m e t a l i o n s . The s y n t h e s i s and c h a r a c t e r i z a t i o n of chromium, molybdenum, t u n g s t e n and manganese c a r b o n y l d e r i v a t i v e s i n v o l v i n g these l i g a n d s i s a l s o d e s c r i b e d . The c r y s t a l s t r u c t u r e s of two 3 mo lybdenum c a r b o n y l d e r i v a t i v e s , [MeGa (pz ) ^  ]M6 (CO) 2 ,( n " ^ 3 ^ 5 ) 3 and [MeGa (dmpz ) 2 (OH) ]Mo (CO) 2 (n -C^H^ are i n c l u d e d . The second p a r t of t h i s i n v e s t i g a t i o n i n v o l v e d the s y n t h e s i s of the u n s y m m e t r i c a l boron l i g a n d s N a + [ H 2 B ( 0 C H 2 C H 2 N M e 2 ) ( p z ) ] ~ and Na +[H 2B(0CH 2CH 2NH 2) (pz) ] . Attempts to s y n t h e s i z e b i s t r a n s i t i o n m e tal complexes of these two l i g a n d s were f r u s t r a t e d by l i g a n d s c r a m b l i n g to g i v e the p r e v i o u s l y c h a r a c t e r i z e d [ H 2 B ( p z ) 2 ] 2 M and [ H B ( p z ) , j ] 2 M complexes. An attempt to prepare some molybdenum c a r b o n y l d e r i v a t i v e s of these l i g a n d s a l s o proved u n s u c c e s s f u l . The f i n a l p a r t of t h i s t h e s i s d e s c r i b e s the syn-t h e s i s and c h a r a c t e r i z a t i o n of the n e u t r a l g a l l i u m - a c e t a t e and g a l l i u m - p r o l i n a t e d e r i v a t i v e s [ R G a ( C H C O ) ] and [R 0Ga(C.H 0 A 5 A A A 4 o NC0 o)] (R=Me, E t ) . The c r y s t a l s t r u c t u r e of the [Me Ga(C.H 0 A XI A 4 o N C 0 2 ) ] n d e r i v a t i v e i s i n c l u d e d . Attempted s y n t h e s i s of the h y d r i d e compound, [H„Ga(CH C 0 o ) ] r e s u l t e d i n a l e s s t r a c t a b l e 2 3 2 p r o d u c t . - 33 -CHAPTER I I GENERAL TECHNIQUES AND STARTING MATERIALS A) G e n e r a l Techniques 2-1. H a n d l i n g of r e a g e n t s Most of the rea g e n t s employed, i n c l u d i n g h y d r i d e and a l k y l d e r i v a t i v e s of the elements of Group I I I A , were u s u a l l y extremely r e a c t i v e w i t h oxygen or water vapour, and c o n s e q u e n t l y were a l l p r e p a r e d and handled i n e i t h e r a h i g h -vacuum l i n e of c o n v e n t i o n a l d e s i g n as shown i n F i g u r e 17 or i n a glovebox under an atmosphere of o x y g e n - f r e e , dry n i t r o g e n . The vacuum-line was equipped w i t h a T o e p l e r pump (p a r t B of F i g u r e 17) which was used f o r measuring the volumes of gases e v o l v e d i n v a r i o u s r e a c t i o n s or i n measuring gas v o l u m e s ' i n a n a l y s i s . The glovebox (Vacuum/Atmospheres C o r p o r a t i o n ) had a s p e c i a l ante-chamber t h a t c o u l d be evacuated by a doub l e -stage r o t a r y pump and then f i l l e d w i t h dry n i t r o g e n (Canadian L i q u i d A i r , K-grade) to ensure the p u r i t y of the atmosphere i n the box. A l l r e a c t i o n s , u n l e s s o t h e r w i s e s p e c i f i e d , were done i n the glovebox or i n a n i t r o g e n - b l a n k e t e d a p p a r a t u s . A l l s o l v e n t s were d r i e d and d i s t i l l e d b e f o r e use, d i e t h y l e t h e r and t e t r a h y d r o f u r a n (THF) over l i t h i u m aluminum h y d r i d e , c y c l o h e x a n e , benzene, t o l u e n e and:, x y l e n e over molten p o t a s s i u m , dioxane and heptane over molten sodium, diglyme over c a l c i u m h y d r i d e and a c e t o n i t r i l e over phosphorus pent-o x i d e . to manometer FIGURE 17 Vacuum L i n e , P a r t A from P a r t A Vacuum L i n e , P a r t B - 36 -A l l g l a s s w a r e was washed w i t h a c e t o n e , oven d r i e d , evacuated and f i l l e d w i t h n i t r o g e n b e f o r e use. A l l n i t r o g e n used was Canadian L i q u i d A i r "K" grade, p u r i f i e d n i t r o g e n , 2-2 . S p e c t r a I n f r a r e d s p e c t r o s c o p y was used e x t e n s i v e l y t h r o u g h -out t h i s i n v e s t i g a t i o n f o r q u a l i t a t i v e a n a l y s i s of the v a r i o u s r e a c t i o n p r o d u c t s . I n f r a r e d s p e c t r a were r e c o r d e d on a P e r k i n Elmer 457 i n f r a r e d g r a t i n g s p e c t r o m e t e r (4000-250 cm "*"), Both N u j o l m u l l s and s o l u t i o n s p e c t r a i n benzene and cyc l o h e x a n e were employed. P r o t o n n.m.r. s p e c t r o s c o p y was performed by Ms. D. M i l l e r and by Dr. S.O. Chan, and was a l s o used e x t e n s i v e l y , not o n l y f o r i d e n t i f i c a t i o n of p r o d u c t s but a l s o f o r e l u c i d a -t i o n of m o l e c u l a r s t r u c t u r e and c o n f o r m a t i o n . The i n s t r u -ments used were the V a r i a n T-60, the HA 100 c o n t i n u o u s wave, the XL-100 F o u r i e r t r a n s f o r m (F.T.) and the 270 MHz n.m.r. s p e c t r o m e t e r s . D e u t e r a t e d benzene, d e u t e r a t e d c h l o r o f o r m and d e u t e r a t e d acetone were used as s o l v e n t s . T e t r a m e t h y l -s i l a n e , TMS, was used as an e x t e r n a l s t a n d a r d on most samples and i s d e f i n e d as xm>,„ = 10.000 ppm. TMS The n.m.r. sample tubes w e r e ^ s p e c i a l l y f i t t e d w i t h a f l a m e - s e a l c o n s t r i c t i o n and a B-10 q u i c k - f i t cone so t h a t the samples c o u l d be loaded and s e a l e d under an atmosphere of n i t r o g e n . Mass s p e c t r a were r e c o r d e d on the V a r i a n MAT CH4 - 37 -mass s p e c t r o m e t e r at 70 eV by Mr. J . N i p , Mr:; G. 0';: Gunn, and Dr. G. E i g e n d o r f . 2-3. A n a l y t i c a l Methods (a) Carbon, Hydrogen and N i t r o g e n C, H and N a n a l y s i s were performed by Mr. P. Borda of t h i s department. (b) H y d r o l y s a b l e hydrogen or methane A s m a l l amount of the compound to be a n a l y z e d was weighed i n t o a c o n i c a l f l a s k i n the glovebox and a tap adaptor was a t t a c h e d to the f l a s k . The f l a s k and i t s c o n t e n t s were then removed from the glovebox, f r o z e n i n l i q u i d n i t r o g e n , and the f l a s k was evacuated on the vacuum l i n e . An excess of degassed, c o n c e n t r a t e d n i t r i c a c i d was then condensed onto the s o l i d i n the f l a s k at -196°C. The m i x t u r e was then a l l o w e d to warm to room temperature and l e f t t o r e a c t u n t i l no more hydrogen or methane was e v o l v e d . The volume of gas, non-condensable at -196°C, was then measured u s i n g the T o e p l e r pump. A l l gas volumes were a d j u s t e d to S.T.P., assuming i d e a l gas b e h a v i o r . (c) G a l l i u m (aluminum) a n a l y s i s A p p r o x i m a t e l y 100 mg of compound to be a n a l y z e d was weighed a c c u r a t e l y i n t o a v i a l or s m a l l beaker. I t was then q u a n t i t a t i v e l y t r a n s f e r r e d w i t h d e i o n i z e d water i n t o a l a r g e beaker where i t was d i g e s t e d f o r one hour w i t h d i l u t e d n i t r i c a c i d . - 38 -The s o l u t i o n was then d i l u t e d w i t h d i s t i l l e d water and made b a s i c w i t h d i l u t e ammonia s o l u t i o n , then made s l i g h t l y a c i d i c , pH 5-7, u s i n g d i l u t e h y d r o c h l o r i c a c i d . Next, the s o l u t i o n was heated to about 80°C and a s l i g h t excess of a 5% s o l u t i o n of 8 - h y d r o x y q u i n o l i n e i n g l a c i a l a c e t i c a c i d was added (2.5 ml per every 10 mg of G a ( I I I ) ) f o l l o w e d by a s a t u r a t e d aqueous s o l u t i o n of ammonium a c e t a t e u n t i l the p r e c i p i t a t i o n of GaCCgHgNO)^ was complete. A f t e r d i g e s t i o n at 80°C f o r one hour, the y e l l o w p r e c i p i t a t e was c o l l e c t e d i n a f i l t r a t i o n c r u c i b l e and washed, f i r s t w i t h h o t , then c o l d water. The p r e c i p i t a t e was then d r i e d at 120°C f o r at l e a s t two h o u r s , weighed, and i t s g a l l i u m c o n t e n t c a l c u l a t e d from the f o r m u l a Ga(C nH,N0) o which i s 13.89% g a l l i u m by w e i g h t . T h i s method has been found to g i v e a c c u r a t e d e t e r m i n a t i o n s f o r a minimum c o n c e n t r a t i o n of 10 mg of g a l l i u m i n 50 ml of s o l u t i o n . The procedure f o r d e t e r m i n i n g aluminum c o n t e n t i n a compound was s l i g h t l y m o d i f i e d i n t h a t o n l y 1 ml of the 5% s o l u t i o n of 8 - h y d r o x y q u i n o l i n e i n g l a c i a l a c e t i c a c i d was r e q u i r e d f o r every 3 mg of aluminum i n the compound. The aluminum c o n t e n t was then c a l c u l a t e d from the f o r m u l a A l ( C g H 6 N O ) 3 > which i s 5.88% aluminum by w e i g h t . B) S t a r t i n g M a t e r i a l s 2-4. Commerical (a) A c e t i c a c i d ( A l l i e d Chemical L t d . ) was d r i e d by - 39 -r e f l u x i n g w i t h a c a l c u l a t e d t h r e e - f o l d excess of t r i a c e t y l -b o r a t e (48) f o r one hour and then d i s t i l l i n g . I t was s t o r e d i n evacuated ampoules. (b) 2-aminoethanol and 2 ^ d i m e t h y l a m i n o e t b a n o l (Eastman Kodak Co.) were both r e f l u x e d over CaSO^ and d i s t i l l e d under reduced p r e s s u r e b e f o r e use. They were b o t h s t o r e d i n evacuated ampoules. (c) 3-bromopropene ( F i s h e r S c i e n t i f i c Co.) and 3-c h l o r o - 2 - m e t h y l p r o p e n e "(Eastman Kodak Co.) were b o t h d i s t i l l e d p r i o r to use and s t o r e d i n evacuated ampoules. (d) Chromium h e x a c a r b o n y l and molybdenum h e x a c a r -b o n y l ( P r e s s u r e Chemicals I n c . ) and t u n g s t e n h e x a c a r b o n y l (Strem Chemicals Inc.) were a l l used as s u p p l i e d . (e) G a l l i u m metal ( P u r a t e k Chemicals L t d . ) was used as s u p p l i e d . ( f ) I s o a m y l n i t r i t e (Matheson, Coleman and B e l l ) was used as s u p p l i e d . (g) L - p r o l i n e (Sigma Chemical Co.) was used as s u p p l i e d . (h) P y r a z o l e and 3 , 5 - d i m e t h y l p y r a z o l e (K and K L a b o r a t o r i e s I n c . ) and 3 - m e t h y l p y r a z o l e ( A l d r i c h Chemical Co.) were a l l used as s u p p l i e d . ( i ) T e t r a m e t h y l s i l a n e ( A l f a - V e n t r o n Co.) was used as s u p p l i e d . ( j ) T i t a n i u m t e t r a c h l o r i d e ( B r i t i s h Drug House Chemicals L t d . ) was used as s u p p l i e d . - 40 -(k) T r i m e t h y l a m i n e h y d r o c h l o r i d e ( A l d r i c h Chemical Co.) was vacuum d r i e d and s u b l i m e d b e f o r e use. 2-5. P r e p a r e d F e C l 2 - 1 . 5 THF ( 4 9 ) , ( r ) 3 - C 3 H 5 ) N i B r ( 5 0 ) , Mn(C0) 5Br (5 1 ) , and ( n"' -C,_H,-)Fe (CO)^1 (51) were a l l p r e p a r e d by the methods d e s c r i b e d i n the r e f e r e n c e s and were a l r e a d y a v a i l -a b l e i n the l a b o r a t o r y . 2-6. P r e p a r a t i o n of d i b o r a n e ( 5 2 ) . d iglyme 2NaBH 4 + H g 2 C l 2 *- 2Hg + 2NaCl + H 2 + B 2 H & (13) Sodium b o r o h y d r i d e (3.000 grams, 79.30 mmoles) was weighed i n t o a 500 ml t h r e e - n e c k e d f l a s k equipped w i t h a magnetic s t i r r i n g b ar. The sodium b o r o h y d r i d e was q u a n t i t a -t i v e l y t r a n s f e r r e d by washing i t i n t o the f l a s k w i t h 100 ml of dry d i g l y m e . Mercurous c h l o r i d e (18.718 grams, 39.65 mmoles) was l o a d e d i n t o a t i p p e r tube and the tube was a t t a c h e d to one of the s i d e j o i n t s on the f l a s k . The o t h e r s i d e j o i n t was s t o p p e r e d and a tap adaptor was f i t t e d i n t o the c e n t r e j o i n t . The vacuum l i n e ( p a r t A, f i g u r e 17) was equipped w i t h t h r e e t r a p s i n s e r i e s ; f i r s t , a d r y ^ i c e c o o l e d acetone t r a p (-78°C) to condense s o l v e n t diglyme vapour, second, a - 41 -l i q u i d n i t r o g e n t r a p (-196°C) to condense the product d i -borane, and f i n a l l y a nother l i q u i d n i t r o g e n t r a p to p r o t e c t the vacuum pump. The r e a c t i o n f l a s k was a t t a c h e d to the vacuum l i n e v i a the tap adaptor and s l o w l y e vacuated. A d d i t i o n of the Hg^Cl^ to the s t i r r i n g NaBH^ s l u r r y i n diglyme was a c c o m p l i s h e d by s l o w l y r o t a t i n g the t i p p e r tube upwards. V i g o r o u s e v o l u t i o n of d i b o r a n e and hydrogen gas o c c u r r e d , even at room t e m p e r a t u r e , and c o n s e q u e n t l y c a r e had to be e x e r c i s e d i n not adding the Hg^Cl^ too q u i c k l y . The hydrogen gas, non-condensable at l i q u i d n i t r o g e n tempera-t u r e , was p e r i o d i c a l l y pumped away. The d i b o r a n e product which c o l l e c t e d i n the l i q u i d n i t r o g e n t r a p was condensed i n t o a f i v e l i t e r s t o r a g e bulb a t t a c h e d to the vacuum l i n e . 2-7. P r e p a r a t i o n of T r i a c e t y l b o r a t e ( d r y i n g agent f o r a c e t i c a c i d ) T r i a c e t y l b o r a t e was p r e p a r e d by h e a t i n g one p a r t by weight of b o r i c a c i d (H^BO^) w i t h f i v e p a r t s of a c e t i c a n h y d r i d e ([CH C 0 ] 2 0 ) to 60°C, the c r y s t a l s of product t h a t p r e c i p i t a t e on c o o l i n g were c o l l e c t e d . 2-8. P r e p a r a t i o n of G a l l i u m T r i c h l o r i d e ( 5 3 ) , G a C l 3 G a l l i u m t r i c h l o r i d e was p r e p a r e d by d i r e c t combina-t i o n of the elements. Pure c h l o r i n e gas (Matheson) was d r i e d by p a s s i n g through c o n c e n t r a t e d s u l f u r i c a c i d i n a b u b b l e r and was then passed i n t o the g l a s s apparatus shown i n F i g u r e - 42 -18. The g a l l i u m m e t a l , about 22 grams,was p l a c e d i n A. A f t e r the apparatus was f l u s h e d out w e l l w i t h c h l o r i n e gas the g a l l i u m m e tal was s l o w l y warmed to m e l t i n g (m.p. 29.78°C) w i t h a bunsen flame. The molten g a l l i u m r e a c t e d w i t h the c h l o r i n e , f i r s t to g i v e a c o l o r l e s s l i q u i d , g a l l i u m t e t r a -c h l o r o g a l l a t e , G a ^ C l ^ (m.p. 170.5°C). On adding more c h l o r i n e t h i s l i q u i d G a 2 C l 4 d i s a p p e a r e d as i t burned w i t h a g r e y - w h i t e flame g i v i n g a v o l a t i l e w h i t e s o l i d , g a l l i u m t r i -c h l o r i d e , G a C l 3 (m.p. 79°C): 2Ga(il) + 2 C l 2 ( g ) £-*-(Ga+) ( G a C l 4 ) (£) (14) (Ga +) ( G a C l 4 )(£) + C l 2 ( g ) • G a ^ l ^ s ) (15) The r a t e of f l o w of c h l o r i n e gas and r a t e of h e a t i n g the molten g a l l i u m were a d j u s t e d so t h a t most of the v o l a t i l e G aCl^ was d e p o s i t e d i n the c o o l e d r e c e i v e r boat C. A f t e r a l l the g a l l i u m had r e a c t e d ( e s s e n t i a l l y 100%), any s u b l i m a t e i n A was d r i v e n i n t o C by warming and flame s e a l i n g the c o n s t r i c -t i o n at B. The apparatus was then evacuated and flame s e a l e d at F. The crude h a l i d e was then r e s u b l i m e d i n t o the ampoules E and th e s e were s e a l e d at t h e i r c o n s t r i c t i o n s . Assuming a 100% y i e l d (55 grams), the weight of g a l l i u m t r i c h l o r i d e i n each ampoule c o u l d be e s t i m a t e d . The g a l l i u m t r i c h l o r i d e was found to remain s t a b l e i n d e f i n i t e l y when s t o r e d t h i s way. FIGURE 18 G a l l i u m T r i c h l o r i d e Apparatus - 44 -2-9. P r e p a r a t i o n of the sodium s a l t s of p y r a z o l e , 3-methyl-p y r a z o l e , and 3 , 5 - d i m e t h y l p y r a z o l e . + • NaH + Hpz : «- Na (pz) + H„ (16) THF 1 In a t y p i c a l p r e p a r a t i o n , a s l u r r y of sodium h y d r i d e (7.994 grams, 333.1 mmoles) i n THF was t r a n s f e r r e d to a t h r e e - n e c k e d f l a s k . The f l a s k was then equipped w i t h a magnetic s t i r r i n g bar and an a d d i t i o n f u n n e l c o n t a i n i n g p y r a z o l e (22.678 grams, 333.1 mmoles) d i s s o l v e d i n THF. The p y r a z o l e s o l u t i o n was added dropwise to the s t i r r i n g s l u r r y . Hydrogen gas was v i g o r o u s l y e v o l v e d at room temperature as the p y r a z o l e was added, and the r e a c t i o n m i x t u r e was s t i r r e d f o r 96 hours to complete the r e a c t i o n . At the end of t h i s p e r i o d , the s o l v e n t THF was removed l e a v i n g a w h i t e , h y g r o s c o p i c powder. T h i s powder was washed w i t h benzene and a l l o w e d to dry on a f i l t e r paper i n the g lovebox. The y i e l d was e s s e n t i a l l y q u a n t i t a t i v e . + Sodium 3 - m e t h y l p y r a z o l i d e , Na (mpz) ; and sodium + ( 3 , 5 - d i m e t h y l p y r a z o l i d e ) , Na (dmpz) , were pr e p a r e d i n e x a c t l y the same manner. 2-10. P r e p a r a t i o n of L i t h i u m G a l l i u m H y d r i d e ( 5 4 ) , LiGaH^ E t 2 0 4LiH + G a C l 3 LiGaH^ + 3 L i C l (17) - 45 -Two ampoules of GaCl^ were weighed and broken open i n the g l o v e box and placed i n a c o n i c a l f l a s k . The g a l l i u m t r i c h l o r i d e was then d i s s o l v e d i n dry d i e t h y l e t h e r and the ampoules were washed s e v e r a l times to ensure a q u a n t i t a t i v e removal of GaCl^. The empty ampoules were reweighed and the weight of the GaCl^ d e t e r m i n e d . The e t h e r e a l s o l u t i o n of GaCl^ and a l l the washings were now added to the n i t r o g e n f i l l e d r e a c t i o n - f i l t r a t i o n apparatus (see f i g u r e 19) and the s o l u t i o n brought up to a p p r o x i m a t e l y 150 ml. From the weight of G a C l ^ c a l c u l a t e d (13.2 grams, 74.9 mmoles) the weight of about s i x t e e n molar e q u i v a l e n t s of f i n e l y ground l i t h i u m h y d r i d e (20.9 grams, 2629 mmoles), enough f o r at l e a s t a f o u r f o l d e x c e s s , was weighed out under n i t r o g e n i n t o the t i p p e r tube B. The r e a c t i o n f l a s k (A) was c o o l e d to -50°C i n a d r y -i c e c o o l e d acetone bath and the t i p p e r tube (B) r o t a t e d up-wards to p e r m i t the slow a d d i t i o n of L i H to the r e a c t i o n f l a s k over a p e r i o d of about 30 minutes. A b u b b l e r was a t t a c h e d to the apparatus so t h a t the r e a c t i o n c o u l d be c a r r i e d out under a c o n s t a n t p r e s s u r e of one atmosphere of n i t r o g e n . The f l a s k was then a l l o w e d to s l o w l y warm up to room temperature and the m i x t u r e was s t i r r e d (C) f o r about f i f t y hours to ensure complete r e a c t i o n . The r e s u l t i n g r e a c t i o n m i x t u r e was f i l t e r e d through the g l a s s s i n t e r e d d i s c (D) and a c l e a r , c o l o r l e s s f i l t r a t e r e s u l t e d i n the r e c e i v e r f l a s k ( E ) . The f l a s k was capped and - 46 -s t o r e d i n the f r e e z e r a t -15°C. 2-11. P r e p a r a t i o n of T r i m e t h y l a m i n e G a l l a n e ( 5 5 ) , Me^NGaH^, from LiGaH,. 4 Et 0 L i G a H 4 + Me 3NHCl >• Me ^ NGaH^ + L i C l + H 2 (18) A known amount of l i t h i u m g a l l i u m h y d r i d e (6.1 grams, 74.9 mmoles) i n d i e t h y l e t h e r s o l u t i o n was p l a c e d i n the r e a c -t i o n - f i l t r a t i o n a pparatus (see F i g u r e 19). Less than the s t o i c h i o m e t r i c amount of t r i m e t h y l a m i n e h y d r o c h l o r i d e , Me^NHCl (3.2 grams, 33.8 mmoles), d r i e d and p u r i f i e d by s u b l i m a t i o n , was p l a c e d i n the t i p p e r tube (B) of the apparatus which con-t a i n e d a n i t r o g e n atmosphere. The e t h e r s o l u t i o n of LiGaH, was f i r s t c o o l e d to 4 o -50 C i n a d r y - i c e c o o l e d acetone b a t h , as the t r i m e t h y l a m i n e h y d r o c h l o r i d e was added over a p e r i o d of about t en minut e s . The s o l u t i o n was s l o w l y warmed to room temperature and s t i r r e d f o r about f o u r hours to ensure complete r e a c t i o n . The s o l u t i o n was then f i l t e r e d t h r o ugh the g l a s s s i n t e r (D) and the r e c e i v e r f l a s k (E) c o n t a i n i n g the c l e a r e t h e r s o l u t i o n was a t t a c h e d t o the s u b l i m a t i o n apparatus as shown i n f i g u r e 20. T h i s apparatus was a t t a c h e d to the vacuum l i n e and the e t h e r was pumped o f f at ^50°C. When most of the e t h e r was removed, the r e c e i v e r f l a s k c o n t a i n i n g the re m a i n i n g r e s i d u e was warmed to 0°C w h i l e the s u b l i m a t i o n - 47 -a pparatus was immersed i n a d r y - i c e c o o l e d acetone b a t h . The pure t r i m e t h y l a m i n e g a l l a n e was vacuum sublimed as l o n g , n e e d l e - l i k e c r y s t a l s i n t o the s u b l i m a t i o n a p p a r a t u s . The y i e l d was 2.1 grams (15.7 mmoles) of t r i m e t h y l a m i n e g a l l a n e . The o v e r a l l y i e l d i n going from g a l l i u m t r i c h l o r i d e to t r i -methylamine g a l l a n e was about 21%. 2-12. P r e p a r a t i o n of [ H 2 G a ( p z ) ] (34) CfiH .2Me.3N.GaH3 + 2Hpz * [H^Ga (pz ) ] 2 + 2H 2 + 2Ke^ (19) T r i m e t h y l a m i n e g a l l a n e (1.037 grams, 7.867 mmoles) was d i s s o l v e d i n 50 ml of benzene and the r e s u l t a n t s o l u t i o n was s t i r r e d w h i l s t a benzene s o l u t i o n c o n t a i n i n g p y r a z o l e (0.536 grams, 7.873 mmoles) was added dropwise at room tem-p e r a t u r e . A gas, presumed to be hydrogen, was v i g o r o u s l y e v o l v e d and a f t e r l e a v i n g the r e a c t i o n m i x t u r e f o r about 1 hour a sample was taken f o r a s o l u t i o n i n f r a r e d spectrum. The spectrum showed the t o t a l absence of any band i n the N-H s t r e t c h i n g v i b r a t i o n r e g i o n and the r e a c t i o n was deemed com-p l e t e . A f t e r removal of s o l v e n t and t r i m e t h y l a m i n e from.the product a w h i t e s o l i d remained. T h i s was vacuum sublimed and the s u b l i m a t e was s t o r e d under n i t r o g e n at -15°C u n t i l used. 2-13. P r e p a r a t i o n of t r i m e t h y l g a l l i u m ( 5 6 ) , (Me) 3Ga HgCl 3(Me) 2Hg + 2Ga • 2 (Me) Ga + 3Hg (20) - 4 9 -- 50 -In a t y p i c a l - p r e p a r a t i o n , g a l l i u m m e t a l (7.2 grams, 103 mmoles) was p l a c e d i n a C a r i u s tube a l o n g w i t h a c a t a l y t i c amount of m e r c u r i c c h l o r i d e . Then 25 grams (108 mmoles) of d i m e t h y l m e r c u r y was added to the C a r i u s tube. The tube, capped with-.a tap a d a p t o r , and i t s - c o n t e n t s were f r o z e n to -196°C w i t h l i q u i d n i t r o g e n . The C a r i u s tube was then e v a c u a t e d , flame s e a l e d at i t s c o n s t r i c t i o n , and s l o w l y warmed to room temperature. F i n a l l y , i t was p l a c e d i n a m etal bomb where i t was kept f o r one week at 120°C. The r e s u l t i n g p r o d u c t , (Me)^Ga, was a c o l o r l e s s l i q u i d w i t h mercury and excess g a l l i u m m e t a l d e p o s i t e d i n the tube. The t h e o r e t i c a l y i e l d was 8.4 grams (73.0 mmoles). The product was condensed from the C a r i u s tube i n t o ampoules u s i n g the vacuum l i n e . I t was used w i t h o u t f u r t h e r p u r i f i c a t i o n . 2-14. P r e p a r a t i o n of t r i e t h y l g a l l i u m ( 5 7 ) , Et^Ga HgCl 3Et 2Hg + 2Ga ^ 2 E t 3 G a + 3Hg (21) U s i n g a procedure s i m i l a r to t h a t d e s c r i b e d above, g a l l i u m m etal (7 grams, 100 mmoles) was r e a c t e d w i t h d i e t h y l -mercury (25 grams, 87 mmoles) i n a C a r i u s tube f o r t h r e e weeks at 120°C. The r e s u l t i n g p r o d u c t , Et^Ga was a l i g h t y e l l o w l i q u i d w i t h mercury and excess g a l l i u m d e p o s i t e d i n the tube. The crude Et^Ga was t r a n s f e r r e d from the C a r i u s tube to p a r t B - 51 -E t 3 G a FIGURE 21 D i s t i l l a t i o n A p p a r a t u s - 52 -of the d i s t i l l a t i o n a p p a r a t u s i l l u s t r a t e d i n F i g u r e 21. The apparatus was capped at the B24 j o i n t and a tap adaptor was f i t t e d onto the B19 j o i n t , then the a p p a r a t u s and i t s c o n t e n t s were f r o z e n i n l i q u i d n i t r o g e n to -196°C. The ap p a r a t u s was evacuated v i a the tap adaptor and flame s e a l e d at A, then tube B, c o n t a i n i n g the crude Et^Ga, was s l o w l y warmed over a p e r i o d of t h r e e hours to 65°C c a u s i n g pure Et^Ga to c o l l e c t i n r e c e i v e r E. The apparatus was then c o o l e d t o -196° and s e a l e d at C and D, and the now c o l o r l e s s Et^Ga was s t o r e d under vacuum at room temperature i n r e c e i v e r E. 2-15. P r e p a r a t i o n of m e t h y l d i c h l o r o g a l l a n e (58) (Me)GaCl2 G a C l . + (Me) . S i - " — ^ M e G a C l 0 + ( M e ) 0 S i C l (22) 3 4 A 2 3 An ampoule c o n t a i n i n g a known amount of GaCl 3 >'(15 grams, 85 mmoles) was broken open i n the glovebox and loaded i n t o the s i d e a r m of the apparatus as shown i n F i g u r e 22. T h i s sidearm was capped and a tap adaptor was f i t t e d onto the B24 j o i n t above c o n s t r i c t i o n G. The apparatus was evacuated v i a the tap adaptor and b u l b E was then f r o z e n i n l i q u i d n i t r o g e n . The c o n s t r i c t i o n at A was flame s e a l e d and the G a C l ^ was warmed w i t h a bunsen flame u n t i l i t had a l l melted and run down.into the bulb E. Excess t e t r a m e t h y I s i l a n e (n.m.r. grade, ^30 ml ) was condensed i n t o b u l b E and the apparatus was flame s e a l e d at c o n s t r i c t i o n s B and C. The apparatus and i t s FIGURE 22 MeGaCl Apparatus - 54 -c o n t e n t s were s l o w l y warmed to room temperature and then p l a c e d i n a hot water bath f o r s e v e r a l h o u r s . On c o o l i n g , the w h i t e c r y s t a l s of MeGaCl 2 were d e p o s i t e d from the c l e a r s o l u t i o n . The excess t e t r a m e t h y l s i l a n e and the t r i m e t h y l -c h l o r o s i l a n e were removed by r u p t u r i n g the b r e a k - s e a l at D and condensing them i n t o a l i q u i d n i t r o g e n t r a p . The c r y s t a l s were weighed (11.2 grams, 72.0 mmoles) and d i s s o l v e d i n 250 ml of THF. T h i s s o l u t i o n c o u l d be s t o r e d i n the glovebox f o r an i n d e f i n i t e p e r i o d . The o v e r a l l y i e l d was 84%. 2-16. P r e p a r a t i o n of dimolybdenum ( I I ) t e t r a a c e t a t e , M o 2 ( C H 3 C 0 2 ) 4 ( 5 9 ) . 2Mo(C0) 6+ 4CH 3C00H f-Mo 2 (CH 3C0 2 ) 4 + 12C0 + 2H 2 (23) In a 100 ml s i n g l e - n e c k e d f l a s k , Mo(C0)g (6.0 grams, 23 mmoles) was d i s s o l v e d i n 60 mis of g l a c i a l a c e t i c a c i d con-t a i n i n g 6.0 mis of a c e t i c a n h y d r i d e , (CH 3CO) 20. The s o l u t i o n was r e f l u x e d f o r 24 hours under n i t r o g e n . The p r o d u c t was d e p o s i t e d from the r e s u l t i n g brown s o l u t i o n as a y e l l o w p r e -c i p i t a t e . C o o l i n g below room tem p e r a t u r e caused y e l l o w , n e e d l e - l i k e c r y s t a l s to grow. They were c o l l e c t e d by s u c t i o n f i l t r a t i o n and washed s e v e r a l times w i t h 100% e'thanol to remove any brown i m p u r i t i e s p r e s e n t . The c r y s t a l s were vacuum d r i e d - 55 -o v e r n i g h t . The y i e l d was about 3.3 grams (7;7 mmoles) or about 68%. 2-17. P r e p a r a t i o n of t r i c a r b o n y l t r i s ( a c e t o n i t r i l e ) molybdenum (0) and t r i c a r b o n y l t r i s ( a c e t o n i t r i l e ) t u n g s t e n ( 0 ) , (CH 3CN) 3Mo(C0) 3 and (CH CN) 3W(CO) ( 6 0 ) . CH CN M(C0), + 3CH 0CN (CH 0CN) ,M(C0) , + 3C0 (24) D J ^ 3 3 3 (where M = Mo, W) Mo(C0)g (5.0 grams, 19 mmoles) was t r a n s f e r r e d i n t o a 100 ml s i n g l e - n e c k e d f l a s k . Then 60 ml of dry a c e t o n i t r i l e was added t o the f l a s k and the r e s u l t i n g m i x t u r e was r e f l u x e d f o r f o u r h o u r s . T h i s r e s u l t e d i n a y e l l o w - g r e e n s o l u t i o n . The s o l v e n t was s t r i p p e d and a p p r o x i m a t e l y 4.8 grams (15.'8 mmoles) of (CH 3CN)^Mo(CO) 3 was r e c o v e r e d as a y e l l o w -green s o l i d . S i m i l a r l y , W(C0)^ a f t e r a f o r t y hour r e f l u x gave (CH 3CN) 3W(C0) as a b r i g h t y e l l o w s o l i d . T h i s compound had a somewhat g r e a t e r a i r s t a b i l i t y than (CH^CN) QMo(CO) 3• - 56 -CHAPTER I I I THE [ M e G a ( p z ) 3 ] ~ LIGAND AND ITS PYRAZOLE SUBSTITUTED DERI-VATIVES. THEIR COORDINATION COMPOUNDS. A. R e s u l t s , and D i s c u s s i o n 3-1. The [ M e G a ( p z ) 3 ] ~ L i g a n d Numerous r e p o r t s (39-41, 44, 45, 61) have d e s c r i b e d the s y n t h e s i s and c o o r d i n a t i o n c h e m i s t r y of b i d e n t a t e a n i o n i c l i g a n d s of the type [ M e 2 G a ( p z ) 2 ] (pz = ( N 2 C 3 H 3 ) ) . T h i s c h a p t e r d e t a i l s the s y n t h e s i s of the a n i o n i c t r i d e n t a t e c h e l a t i n g l i g a n d , m e t h y l t r i s ( 1 - p y r a z o l y l ) g a l l a t e , [ M eGa(pz) 3] , (see F i g u r e 23) and d e s c r i b e s i t s c o o r d i n a t i o n 2 + compounds w i t h t r a n s i t i o n m e t a l M i o n s (M=Mh, Fe, Co, N i , Cu or Zn) and a l s o d e s c r i b e s d e r i v a t i v e s formed by i n t e r -a c t i o n of the l i g a n d w i t h Mo, W, and Mn c a r b o n y l compounds. F i g u r e 23 Jy^ The f i r s t r e p o r t e d case of a compound c o n t a i n i n g the [MeGa(pz) 3] l i g a n d was the complex [MeGa(pz) ] 2 N i , which - 57 -was i s o l a t e d i n low y i e l d as a s i d e p r o duct of the r e a c t i o n (46) i n v o l v i n g the [Me 2Ga(OCH 2CH 2NMe 2) ( p z ) ] ~ l i g a n d w i t h n i c k e l ( I I ) . In or d e r to f u r t h e r study the c h e l a t i n g p r o -p e r t i e s of the [MeGa(pz)^] l i g a n d , i t was f i r s t n e c e s s a r y to f i n d a p r e p a r a t i v e r o u t e which would g i v e the l i g a n d i n good y i e l d . F o r m a t i o n of the l i g a n d d i r e c t l y from Me^Ga i s h i n d e r e d by the s t a b i l i t y of the "Me^Ga" moiety ( 3 ) , and the i n a b i l i t y of [ M e 2 G a ( p z ) 2 ] to undergo f u r t h e r s u b s t i t u -t i o n . analogous [ R B ( p z ) 3 ] l i g a n d (where R=H, a l k y l , a r y l , or p y r a z o l y l ) by s t a r t i n g w i t h a s p e c i e s c o n t a i n i n g good l e a v i n g groups, such as RBX 2 (where X = h a l o g e n ) , to f a c i l i t a t e s u b s t i t u t i o n by p y r a z o l y l . The analogous g a l l i u m compound, MeGaCl 2, was easy to s y n t h e s i z e i n h i g h y i e l d (58) by s i m p l y warming g a l l i u m t r i c h l o r i d e i n excess t e t r a m e t h y l s i l a n e . The methyl d i c h l o r o g a l l a n e was then r e a c t e d w i t h t h r e e molar e q u i v a l e n t s of sodium p y r a z o l i d e to form the d e s i r e d p r o d u c t , sodium m e t h y l t r i s ( 1 - p y r a z o l y l ) g a l l a t e , a c c o r d i n g to the f o l l o w i n g scheme: Trofimenko (22) had p r e v i o u s l y s y n t h e s i z e d the x s ( M e ) . S i + GaCl MeGaCl 2 + ( M e ) 3 S i C l (25) MeGaCl 2 + 3Na(pz) THF Na[MeGa(pz) 3] + 2NaCl (26) The l i g a n d was not i s o l a t e d from the THF s o l v e n t - 58 -because s i m i l a r l i g a n d s were found to e i t h e r decompose on s o l v e n t removal or be v e r y h y g r o s c o p i c making h a n d l i n g and c h a r a c t e r i z a t i o n d i f f i c u l t ( 46). The r e s u l t i n g l i g a n d s o l u t i o n was made up to s t a n d a r d volume w i t h THF and r e a c t e d i n measured a l i q u o t s . The n a t u r e of the r e s u l t i n g p r o d u c t s p r e p a r e d from t h i s l i g a n d s o l u t i o n i n d i c a t e d the d e s i r e d l i g a n d was indeed s y n t h e s i z e d . The b i s l i g a n d t r a n s i t i o n m e t a l complexes were pr e p a r e d by the r e a c t i o n of s t o i c h i o m e t r i c q u a n t i t i e s of the l i g a n d and a metal h a l i d e i n THF, v i z : MX 2 + 2Na[MeGa(pz) 3] T R F »[MeGa(pz) 3] £M + 2NaX (27) (where M= Mn, Fe, Co, N i , Cu or Zn; X = h a l i d e ) The a n a l y t i c a l d a t a f o r the complexes prepa r e d are l i s t e d i n T a b l e I I I . The N u j o l m u l l s p e c t r a of t h e [ M e G a ( p z ) 3 ] 2 M complexes l i s t e d i n T a b l e I I I were e s s e n t i a l l y i d e n t i c a l , i n d i c a t i n g a p r o b a b l e isomorphism i n the o c t a -h e d r a l complexes. The [MeGa (p z ) 3 LZn spectrum i s . shown i n f i g u r e 24. An x-ray s t r u c t u r a l study of the n i c k e l complex i s i n p r o g r e s s and s h o u l d c o n f i r m the p s e u d o - o c t a h e d r a l arrangement of the s i x l i g a t i n g n i t r o g e n atoms about the c e n t r a l n i c k e l atom. Such an arrangement has been demonstrated i n the c r y s t a l s t r u c t u r e d e t e r m i n a t i o n of the boron complex [ H B ( p z ) 3 ] 2 C o ( 2 5 ) . Two s h a r p , s t r o n g bands o c c u r r e d i n the r e g i o n WAVENUMBER (CM*1) F i g u r e 24 I n f r a r e d Spectrum of [MeGa(pz) ] Zn i n N u j o l - 60 -u s u a l l y a s s o c i a t e d w i t h the vGa-C s t r e t c h i n g v i b r a t i o n s , 628 and 595 cm , i n a l l of the s p e c t r a . The band at lower f r e q u e n c y i s p r o b a b l y the vGa-C s t r e t c h i n g v i b r a t i o n f o r the compounds and the one at 628 cm ^, a l i t t l e h i g h f o r a vGa-C s t r e t c h ( 5 6 ) , may be due to a p y r a z o l y l r i n g mode. The mass s p e c t r a of a l l s i x complexes l i s t e d i n t a b l e I I I were a l l very s i m i l a r . The p r i n c i p a l f e a t u r e s of the mass sp e c t r u m of [MeGa(pz)^] 2Zn a r e r e c o r d e d , t o g e t h e r w i t h t h e i r t e n t a t i v e a s s i g n m e n t s , i n Table V I . T h i s spectrum i s t y p i c a l of the o t h e r f i v e r e c o r d e d , d i s p l a y i n g s t r o n g s i g n a l s due to the paren t i o n s and a l s o s t r o n g s i g n a l s c o r r e -+ sponding to the [MeGa(pz)^]M i o n s . In a d d i t i o n to the o t h e r weak s i g n a l s a r i s i n g from mixed metal i o n s , two s t r o n g s i g n a l s o c c u r r e d i n a l l s i x s p e c t r a which were a s s i g n e d to i o n s con-t a i n i n g two g a l l i u m atoms, v i z [ M e G a ^ ( p z ) ^ ] + and [ M e 2 G a 2 ( p z ) ^ ] + . These i o n s must a r i s e , a f t e r e j e c t i o n of the t r a n s i t i o n m e t a l and p y r a z o l y l groups from the paren t s p e c i e s , by recombina-t i o n of "MeGa(pz) " fragments. I t i s noteworthy i n t h i s r e g a r d t h a t a s t r o n g s i g n a l due to the [ M e G a ( p z ) ] + i o n o c c u r s i n a l l of the s p e c t r a . Depending upon the number of g a l l i u m and z i n c atoms i n an i o n , a c h a r a c t e r i s t i c p a t t e r n of s i g n a l s was observed. The i n t e n s i t y r a t i o s w i t h i n each p a t t e r n agreed c l o s e l y w i t h those c a l c u l a t e d from the i s o t o p i c d i s t r i b u t i o n s of the metal atoms. The v a r i o u s p a t t e r n s , t o g e t h e r w i t h t h e i r r e l a t i v e i n t e n s i t y r a t i o s , are g i v e n i n f i g u r e s 28 and 29: - 61 -Attempts to o b t a i n the F o u r i e r t r a n s f o r m n.m.r. of the d i a m a g n e t i c [MeGa(pz) 0]„Zn complex i n C,D or (CD_) oC0 5 2. o o j Z s o l v e n t f a i l e d . The a n a l y t i c a l d ata f o r the m e t a l c a r b o n y l complexes prepare d are l i s t e d i n Table I I I . Attempted p r e p a r a t i o n of the chromium complexes proved u n s u c c e s s f u l . The molybdenum com-p l e x e s were prepar e d v i a a t h e r m a l method i n v o l v i n g the r e a c t i o n of Mo(CO)g w i t h the l i g a n d to g i v e the N a + [ M e G a ( p z ) 3 Mo(CO) 3] s a l t as an i n t e r m e d i a t e : (M=Mo) _ i _ — THF 4- ~~ M(CO) 6 + Na [MeGa(pz) 3] ~ • Na. [MeGa(pz) 3 M(CO) ] + 3C0 (28) (M=Mo,W) Th i s i n t e r m e d i a t e was not i s o l a t e d , but r e a c t e d i n s i t u w i t h an excess of the a p p r o p r i a t e a l l y l a t i n g or n i t r o s y l a t i n g agent to g i v e the d e s i r e d p r o d u c t s : N a + [ M e G a ( p z ) 3 M ( C 0 ) 3 ] ~ ' + xs.CH2 = CRCH 2X [M e G a ( p z ) 3 ] M (CO) 2 ( r ^ - C ^ R ) + CO + NaX (29) (where R = H, X = Br; or R = Me, X = C l ) N a + [ M e G a ( p z ) 3 M (CO) 3J + Cjfl 0N0 2-ILL [MeGa(pz) 3] M (CO) 2NO + CO + N a + ( C 5 H o) (30) A s i m i l a r p r e p a r a t i v e r o u t e i n v o l v i n g the s y n t h e s i s - 62 -+ - 3 of the Na [MeGa (pz) 3W (CO) 3 ] s a l t f a i l e d to g i v e the f) -C 3H 5 d e r i v a t i v e . A more e f f i c i e n t way to prepare the "n - a l l y l " compounds of t u n g s t e n used (CR^CN) 3W(CO) (60) as a s t a r t i n g m a t e r i a l : (CH 3CN) 3W(CO) 3 + xsCH 2 = CHCH 2Br ™ F » ( C H 3 C N ) 2 W ( C O ) 2 ( B r ) ( n 3 - C 3 H 5 ) + CR^CN + CO (31) ( C H 3 C N ) 2 W ( C O ) 2 ( B r ) ( n 3 - C 3 H 5 ) + Na +[MeGa(pz) ] " THF ^ ^[MeG a ( p z ) 3 ] W ( C O ) 2 ( n -C 3H 5) + 2CH 3CN + NaBr (32) T h i s method (30) was more advantageous i n t h a t p r o l o n g e d heat i n g of W(C0)^ w i t h the l i g a n d i n THF or dioxane s o l v e n t 3 was not r e q u i r e d . The [MeGa(pz) 3]W(CO) 2(n -C^H^) compound c o u l d a l s o be prepared by t h i s r o u t e but employing 3 - c h l o r o -2-methylpropene i n the f i r s t s t e p ( e q u a t i o n 31). The manganese c a r b o n y l compound, [M e G a ( p z ) 3 ] M n ( C O ) 3 , was prepar e d by s i m p l y r e f l u x i n g Mn(C0)^Br w i t h one e q u i v a l e n t of the l i g a n d i n THF: Mn(C0) 5Br + Na +[MeGa (pz ) 3 ] ^ — [ M e G a ( p z ) ]Mn (CO) 3 + 2C0 + NaBr (33) The metal c a r b o n y l complexes show i m p o r t a n t t r e n d s i n t h e i r i . r . s p e c t r a . The wave numbers of v v i b r a t i o n s f o r the complexes are l i s t e d i n Table IV t o g e t h e r w i t h - 63 -p e r t i n e n t v r n bands f o r comparable compounds ( 2 7 , 6 2 ) . , I t i s noteworthy t h a t the v v i b r a t i o n s f o r the g a l l i u m complexes are c o n s i s t e n t l y about 10 cm lower than those of the c o r r e -sponding boron complexes, s u g g e s t i n g a more e l e c t r o n - r i c h t r a n s i t i o n m e t a l c e n t r e w i t h the i n t r o d u c t i o n of the g a l l i u m l i g a n d w i t h consequent i n c r e a s e d back-bonding to the c a r b o n y l groups. The r e s u l t s a re e n t i r e l y i n agreement w i t h the bond 3 l e n g t h s i n [MeGa(pz) 3]Mo(CO) 2(n -C 3H 5) and [ H B ( p z ) 3 ] M o ( C O ) 2 3 (n -C^H^) (see c r y s t a l s t r u c t u r e d i s c u s s i o n ) . As w i t h the boron complexes ( 6 2 ) , the v Q Q v a l u e s f o r the g a l l i u m complexes decrease by about 10 cm ^ i n going from Mo to W. In the 3 5 analogous L M o ( C 0 ) 2 ( n -C-jH,.) s e r i e s (where L = n -C 5H , H B ( p z ) 3 , or MeGa(pz)^), the h i g h e s t VQQ v a l u e s o ccur when L = n^-C^H^, the lowe s t when L = M e G a ( p z ) y Another n o t e -worthy f e a t u r e i s t h a t o n l y i n the complex [MeGa(pz) 3]W(CO) 2 3 (ri -C H^ .) do f o u r VQQ bands become a p p a r e n t , a f e a t u r e pre'--5 3 v i o u s l y r e p o r t e d f o r the complex (n -C.-H,-)Mo (CO) 2 (n -C3H,.) ( 6 3 ) . T h i s suggests the occurence of two isomers i n the cyclohe x a n e s o l u t i o n of t h i s t u n g s t e n complex w i t h the a l l y l group i n one of the isomers r o t a t e d i n the o p p o s i t e d i r e c t i o n to t h a t d e p i c t e d i n the c r y s t a l s t r u c t u r e of the Mo d e r i v -a t i v e (see F i g u r e 2 7 ) . The i n t e n s i t i e s of the two s e t s of d o u b l e t s are i n a p p r o x i m a t e l y a 2:1 r a t i o s u g g e s t i n g one isomer b e i n g p r e f e r r e d over the o t h e r . From the c r y s t a l s t r u c t u r e data ( 6 4 ) of the [ M e G a ( p z ) 3 ] M o ( C O ) 2 ( n 3 - C 3 H ^ ) com-p l e x and t h a t of the s i m i l a r boron s t r u c t u r e ( 6 2 ) , i t i s apparent t h a t i t i s p r e f e r a b l e f o r the c e n t r a l atom of the 64 " a l l y l " group (whether i t bears a hydrogen atom or a methyl group) to o r i e n t i n t o the space between the two p y r a z o l y l . . 3 groups. Indeed the complex, [MeGa(pz) ]W(CO)^(n "C^H^), shows o n l y two V Q Q bands, s u g g e s t i n g t h a t the C-Me group p r o j e c t i n g towards the two CO groups i s not e n e r g e t i c a l l y f a v o r e d . The g a l l i u m complexes which d i s p l a y j u s t two bands are a l l thought to be s i m i l a r , w i t h r e s p e c t t o o r i e n t a t i o n of t h e i r a l l y l groups, to t h a t i l l u s t r a t e d f o r the [MeGa(pz)^] 3 M o ^ O ^ d n -C^H^) complex ( F i g u r e 27). The l a r g e r s i z e of the W atom over the Mo atom may be r e s p o n s i b l e f o r the o c c u r r e n c e of a s m a l l amount of the l e s s f a v o r e d isomer i n the c y c l o -3 hexane s o l u t i o n of the [MeGa(pz)^]W(CO)^(n " ^ 3 ^ 5 ) complex. The manganese t r i c a r b o n y l complex, [MeGa(pz) ]Mn (CO)^, showed the expected two V Q Q bands i n cyc l o h e x a n e and these o c c u r r e d at 10 cm ^ lower than the V Q Q v a l u e s r e p o r t e d f o r s i m i l a r boron complexes (see T a b l e I V ) , as e x p e c t e d . The N u j o l m u l l spectrum of t h i s complex, however, d i s p l a y e d a s p l i t asymmetric V ^ Q v i b r a t i o n and gave t h r e e bands i n the v r e g i o n at 2020, 1922 and 1890 cm" 1. U n f o r t u n a t e l y the two n i t r o s y l complexes, [MeGa (pz) 3]M(CO) 2NO (M=Mo, W), were not s u f f i c i e n t l y s o l u b l e to g i v e s p e c t r a i n cycloh e x a n e or i n d i c h l o r o m e t h a n e . The s p e c t r a r e c o r d e d i n Table IV were taken i n N u j o l . Four bands (two of s t r o n g and two of medium i n t e n s i t y ) were found i n the v r e g i o n of each complex and a complex band envelope was observed i n the v r e g i o n of the s p e c t r a at about - 65 -1650 cm ^. These s p l i t t i n g s c o u l d w e l l a r i s e from the n e c e s s i t y to use N u j o l m u l l samples, but i t i s c l e a r t h a t the t u n g s t e n complex a g a i n d i s p l a y s the lower V ^ Q f r e q u e n c i e s , a p p r o x i m a t e l y 20 cm ^ below those f o r the c o r r e s p o n d i n g moly-bdenum compound. 1 3 The H n.m.r. r e s u l t s f o r the "n - a l l y l " and n i t -1 r o s y l complexes of Mo and W are l i s t e d i n T a b l e V. The H 3 n.m.r. s p e c t r a of [ M e G a ( p z ) 3 ] M o ( C O ) 2 ( n -C^H ) and [MeGa(pz) 3] M o ^ O ^ N O are shown i n F i g u r e s 25 and 26 r e s p e c t i v e l y . A l l s i x s p e c t r a gave s i g n a l s f o r the p y r a z o l y l p r o t o n s which i n -d i c a t e t h a t two p y r a z o l y l groups are i n l i k e p o s i t i o n s w h i l s t the t h i r d p y r a z o l y l group i s unique. The assignment of the i n d i v i d u a l s i g n a l s to s p e c i f i c p y r a z o l y l p r o t o n s f o l l o w s by analogy w i t h the assignments of Meakin et a l f o r s i m i l a r boron compounds (6 5 ) . I t i s noteworthy t h a t the p y r a z o l y l p r o t o n s i n [ H B ( p z ) 3 ] M o ( C O ) 2 ( n - C 3 H 5 ) (52) do not approach the r e s o l u -t i o n of those i n the room temperature spectrum of [MeGa(pz)^] 3 M O ( C 0 ) 2 ( T I " ^ 3 ^ 5 ) u n t i l -45°C. In f a c t , at room t e m p e r a t u r e , due to a r a p i d r o t a t i o n of the [ H B ( p z ) 3 ] moiety about the B. ,-Mo :<axis, the t h r e e p y r a z o l y l groups appear e q u i v a l e n t . Less s e v e r e s t e r i c i n t e r a c t i o n s about the molybdenum atom i n the boron complex, due to s h o r t e r B-N d i s t a n c e s r e l a t i v e to Ga-N d i s t a n c e s , p r o b a b l y account f o r the observed d i f f e r e n c e i n the p r o t o n n.m.r. s p e c t r a . H i g her temperature s p e c t r a on the g a l l i u m complex may demonstrate a s i m i l a r a b i l i t y of the [MeGa(pz) 3] moiety to r o t a t e about the Ga...Mo a x i s . - 68 -Comparison of the s p e c t r a of the n i t r o s y l compounds w i t h 3 those of the "n - a l l y l " compounds r e v e a l s a s i g n i f i c a n t up-f i e l d s h i f t of the s i g n a l due t o the 3-H p r o t o n of the unique p y r a z o l y l group i n the n i t r o s y l compounds. The s i g n a l s due the the 3-H p r o t o n s of the two s i m i l a r l y p o s i t i o n e d p y r a z o l y l groups do not change s i g n i f i c a n t l y on changing a l l y l f o r n i t r o s y l i n the compounds. Both the "n - a l l y l " groups and the n i t r o s y l groups are t r a n s to the 3-H p r o t o n of the unique p y r a z o l y l group i n the p s e u d o - o c t a h e d r a l complexes (see F i g u r e 27) and i t seems p o s s i b l e t h a t some type of t r a n s e f f e c t i s r e s p o n s i b l e f o r the observed s h i f t . Another f e a t u r e of note 3 i s t h a t the s i g n a l s due to the p y r a z o l y l p r o t o n s of the n -se i n 2 - m e t h a l l y l complexes are not as w e l l r e s o l v e d as tho 3 the c o r r e s p o n d i n g n - a l l y l complexes. A v a r i a b l e temperature "*"H n.m.r. study i s b e i n g undertaken on these complexes i n an attempt t o e x p l a i n these o b s e r v a t i o n s . The a l l y l p r o t o n s gave c l e a r l y r e s o l v e d s i g n a l s 3 except f o r the unique p r o t o n of the ri -C^H,. group. The s i g n a l s are a s s i g n e d i n Table V f o l l o w i n g assignments f o r the compar-a b l e " a l l y l " complexes ( n 5 " C ^ )Mo (CO ) 2 ( n 3 - C ^ ) (66 ,67) and 5 3 (n -C,.H,_)Mo (CO) 2 (n -C^B.^) (67) and a l s o u s i n g the assignments g i v e n i n r e f e r e n c e ( 6 8 ) . A g a i n a v a r i a b l e temperature ~^H n.m.r. study would be u s e f u l on these complexes i n the " a l l y l " r e g i o n of the s p e c t r a t o determine i f r o t a t i o n of the " a l l y l " groups i s p o s s i b l e or whether s t e r i c i n t e r a c t i o n s r e s t r i c t the m o l e c u l a r arrangement of these groups to one or the o t h e r of the two p o s s i b l e isomers d i s c u s s e d above. A s t e r e o c h e m i c a l l y - 69 -r i g i d system might w e l l be c o n f i r m e d f o r the g a l l i u m complexes on the n.m.r. time s c a l e w i t h i n the e x p e r i m e n t a l l y a c c e s s i b l e temperature range. I t i s i n t e r e s t i n g to note t h a t the room temperature ~*"H n.m.r. spectrum of the complex [MeGaCpz)^] 3 W(C0) 2(n -C^H^) i n CgDg d i d not i n d i c a t e the presence of two isomers as suggested by the i . r . spectrum i n c y c l o h e x a n e s o l v e n t . However i t i s w e l l documented t h a t changing the s o l v e n t can r a d i c a l l y a l t e r the d i s t r i b u t i o n of isomers i n t h i s type of system ( 6 9 ) . The i . r . spectrum of t h i s complex inbenzene d i s p l a y e d but two peaks i n the V r r i r e g i o n of the spectrum. The mass s p e c t r a of a l l seven c a r b o n y l compounds l i s t e d i n T a b l e I I I d i s p l a y e d s i g n a l s due to p a r e n t i o n s . The p r i n c i p l e f e a t u r e s of the mass s p e c t r a of [MeGa(pz) 3]Mn ( C 0 ) 3 , [ M e G a ( p z ) 3 ] M o ( C 0 ) 2 ( n 3 - C 3 H 5 ) , and [MeGa(pz) ]W(CO) 2N0 are r e c o r d e d , t o g e t h e r w i t h t h e i r t e n t a t i v e a s s i g n m e n t s , i n T a b l e s V I I , V I I I and I X , r e s p e c t i v e l y . The t h e o r e t i c a l i n -t e n s i t y p a t t e r n s f o r Ga and Mo-Ga, W-Ga are shown i n F i g u r e s 28 and 30 r e s p e c t i v e l y . In the mass spectrum of the manganese complex, [MeGa(pz) ]Mn(CO) • (Table V I I ) , a l l the s i g n a l s were weak compared to the v e r y s t r o n g s i g n a l a t t r i b u t a b l e to the [ M e G a ( p z ) 3 ] M n + i o n . The mass s p e c t r a of the t h r e e molybdenum d e r i v a t i v e s , i n c l u d i n g [MeGa (pz ) 3 ]Mo (CO) 2 ( r , 3 - C ^ ) (Table V I I I ) , gave w e l l -d e f i n e d 9 - l i n e p a t t e r n s , of c l o s e to the t h e o r e t i c a l i n t e n s i t y - 70 -r a t i o , f o r a l l i o n s c o n t a i n i n g b oth a g a l l i u m and a molybdenum atom. The s p e c t r a a l l d i s p l a y e d as t h e i r most i n t e n s e s i g n a l the one a r i s i n g from the p a r e n t i o n minus two CO groups. The p a r e n t i o n s themselves gave s i g n a l s about o n e - f i f t h as i n -tense as the above s i g n a l s . The mass s p e c t r a of the t u n g s t e n d e r i v a t i v e s gave w e l l - d e f i n e d 6 - l i n e p a t t e r n s of expected i n t e n s i t y r a t i o f o r a l l i o n s c o n t a i n i n g both a Ga and a W atom. The spectrum of the n i t r o s y l d e r i v a t i v e , [MeGa(pz) ]W(CO) 2N0 (Table I X ) , d i s p l a y e d as i t s most i n t e n s e s i g n a l t h a t c o r r e s p o n d i n g to p a r e n t i o n s t r i p p e d of two CO groups and a m e t h y l group. The s p e c t r a of the t u n g s t e n a l l y l compounds d i s p l a y e d as t h e i r most i n t e n s e s i g n a l s those a r i s i n g from pa r e n t i o n s minus two CO groups. In a l l t h r e e t u n g s t e n compounds the p a r e n t i o n s i g n a l s themselves were about t w o - f i f t h s as i n t e n s e as the s t r o n g e s t s i g n a l s i n the s p e c t r a . In a l l s i x s p e c t r a s t r o n g s i g n a l s a r i s i n g from the [MeGa(pz)^]M + i o n (M=Mo or W) were a g a i n observed. In summary, a l l t h i r t e e n complexes l i s t e d i n T able I I I are s u f f i c i e n t l y v o l a t i l e and s t a b l e to g i v e r e a d i l y o b s e r v a b l e p a r e n t i o n s i g n a l s i n t h e i r mass s p e c t r a . The appearance of s i g n a l s due to o t h e r i o n s i n d i c a t e s fragmenta-t i o n p a t t e r n s which are p r e d i c t a b l e f o r these complexes. The i n t e n s i t y r a t i o s f o r the i n d i v i d u a l peaks i n m u l t i - p e a k , s i g n a l s agree c l o s e l y w i t h t h e o r e t i c a l p r e d i c t i o n s based on the p ercentage i s o t o p e c o m p o s i t i o n s of the c o n t r i b u t i n g m e t a l at oms. - 71 -3 The m o l e c u l a r s t r u c t u r e of [MeGa(pz)^]Mo(CO)^(n -C^H^) ( 6 4 ) , shown i n F i g u r e 27, c o n f i r m s u n e q u i v o c a l l y the t r i d e n t a t e c h e l a t i n g c h a r a c t e r of the new l i g a n d , [MeGa(pz)^] , and w a r r a n t s c l o s e comparison w i t h the s t r u c t u r e r e p o r t e d f o r 3 the s i m i l a r boron complex, [HB(pz) 3]Mo(CO) (n -C^H^) (62). D i f f e r e n c e s i n p r o p e r t i e s of the compounds are to be e x p e c t e d , due p r i m a r i l y to the much l o n g e r mean Ga-N bond d i s t a n c e o o (1.926(8) A) compared w i t h the mean B-N d i s t a n c e of 1.545 A. T h i s d i f f e r e n c e l e a d s to a g r e a t e r s t e r i c crowding about the Mo atom i n the g a l l i u m complex .since the 3-H atoms of the p y r a z o l y l groups are f o r c e d i n t o c l o s e r p r o x i m i t y to the Mo atom than i n the boron compound. In both s t r u c t u r e s the M-(N-N) jMo (M=B or Ga) boat h a v i n g the a l l y l group p r o j e c t i n g towards i t i s f l a t t e n e d compared to the o t h e r two such boats h a v i n g CO groups i n c l o s e p r o x i m i t y (mean magnitudes of the N-[Mo-N}N d i h e d r a l a n g l e s i n the p r e s e n t s t r u c t u r e are 22.5° f o r the unique r i n g and 52.4° f o r the o t h e r r i n g s ) . The d i f f e r e n c e i s more pronounced i n the case of g a l l i u m as a r e s u l t of the g r e a t e r s t e r i c crowding mentioned above. Another n o t i c e a b l e e f f e c t of the b u l k y a l l y l s u b s t i t u e n t i s t h a t i n both s t r u c t u r e s the s h o r t e s t Mo-N bond d i s t a n c e s are t r a n s to the a l l y l group (2.232(3) v e r s u s 2.309(3) and 2.328(3) A f o r the g a l l i u m complex and 2.207 v e r s u s 2.312 X f o r the boron complex). Comparison of the Mo-CO and CO bond d i s t a n c e s r e -v e a l s t h a t the C-0 bonds are l o n g e r and the Mo-CO bonds - 72 -F i g u r e 27 A S t e r e o v i e w of [MeGa (pz ) ]Mo(CO) (n -C H ) s i g n i f i c a n t l y s h o r t e r i n the g a l l i u m compound than i n the boron compound. T h i s r e f l e c t s the more e l e c t r o n r i c h Mo c e n t r e i n the g a l l i u m complex which may r e s u l t from an i n c r e a s e i n donor s t r e n g t h (or a decrease i n a c c e p t o r a b i l i t y ) of the g a l l i u m l i g a n d over the boron l i g a n d . The bond l e n g t h s do r e f l e c t an i n c r e a s e i n d TT - TT * back-bonding to the CO groups i n the g a l l i u m complex w i t h concomitant decrease i n Mo-CO d i s t a n c e s and i n -c r e a s e s i n C-0 bond l e n g t h s (Mo-CO = 1.959 and 1.958 0 A f o r B, 1.936(5) and 1.948(5) A f o r Ga; C- 0 = 1.151 and 1.150 0 A f o r B, 1.162(6) and 1.166(6) A f o r Ga). The e f f e c t i s a J. s o r e f l e c t e d i n the v C Q v i b r a t i o n s i n the I . r . s p e c t r a of the two c omp1exe s where the g a l l i u m complex e x h i b i t s v bands 10 cm ^ Li U lower than i n the boron compound (see Table I V ) . The M-C-0 groupings show a s l i g h t d e v i a t i o n from l i n e a r i t y (177.2(5) and 176.5(5)°) which most p r o b a b l y r e s u l t s from l o c a l p a c k i n g f o r c e s . The geometry about the Mo atom i s 3 d i s t o r t e d o c t a h e d r a l w i t h the n - a l l y l group o c c u p y i n g one of - 73 -the o c t a h e d r a l p o s i t i o n s as a TT d o n a t i n g l i g a n d (Mo-C -o 2.228(5), 2.338(5) and 2.360(5) A ) . The g a l l i u m atom i s i n a d i s t o r t e d t e t r a h e d r a l environment w i t h normal Ga-N and Ga-C bond d i s t a n c e s (15, 35-37, 41, 45-47). Other bond l e n g t h s and a n g l e s i n the m o l e c u l e are as e x p e c t e d . I t i s i n t e r e s t i n g to note t h a t i n the boron s t r u c t u r e (62) and the g a l l i u m s t r u c t u r e the t h r e e a l l y l carbons i n t e r a c t i n g w i t h the Mo atom occupy the same r e l a t i v e p o s i t i o n s , even though i n the boron compound the c e n t r a l " a l l y l " carbon atom bears a methyl group i n s t e a d of a hydrogen atom as i n the g a l l i u m complex. S t e r i c crowding about the Mo atom r e s u l t s i n t o r s i -o n a l t w i s t s about the p y r a z o l y l N-N bonds, p a r t i c u l a r l y those c i s to the a l l y l group. The Mo-[N-N]-Ga t o r s i o n .angles ( i d e a l l y = 0°) are 1 8 . 2 ( 2 ) , -18.2(2) and 5.5(2)° r e s p e c t i v e l y f o r the N ( l ) , N(3) and N(5) p y r a z o l y l r i n g s . One of the p y r a z o l y l groups ( t h a t c o n t a i n i n g N ( l ) ) i s s i g n i f i c a n t l y non-2 p l a n a r (x =9.5) w h i l e the o t h e r two are p l a n a r w i t h i n e x p e r i -mental e r r o r . The Ga and Mo atoms are s i g n i f i c a n t l y d i s p l a c e d from a l l t h r e e . p y r a z o l y l r i n g mean p l a n e s . The c r y s t a l s t r u c t u r e c o n s i s t s of w e l l - s e p a r a t e d m o l e c u l e s of [MeGa(pz)^] 3 MoXCO^Cn " ^ 3 ^ 5 ) ' t n e s h o r t e s t i n t e r m o l e c u l a r d i s t a n c e s c o r r e -s p o nding to normal Van der Waals i n t e r a c t i o n s . - 74 -Table I I I A n a l y t i c a l Data f o r Complexes I n c o r p o r a t i n g the [MeGa(pz) 3] L i g a n d [MeGa(pz)^] 2M Compounds C o l o r T r a n s i t i o n m e t a l P r e c u r s o r A n a l y s i s Found % Cone % C H N C H N Mn w h i t e MnCl, Fe p a l e y e l l o w Co be i g e CoCl, N i l i l a c N i B r , Cu b l u e CuBr, Zn w h i t e ZnCl, 38.5 4.0 2 6.9 F e C l 2 - 1 . 5 THF 38.8 3.9 26.6 37.9 3.7 26.7 38.3 3.8 26.8 37.5 4.0 24.3 37.9 3.7 26.5 38.3 3.9 26.8 38.3 3.9 26.8 38.1 3.8 26.7 38.1 3.8 26.7 37.8 3.8 26.5 37.7 3.8 26.4 C a r b o n y l Compounds, [MeGa(pz)~]X A n a l y s i s Found % Cone % X C o l o r C H N C H N M o ( c o ) 2 ( n 3 - c 3 H 5 ) y e l l o w 37 . 7 3.6 17 . 3 37 . 6 3.5 17 . 5 M o ( c o ) 2 ( r , 3 - c 4 H 7 ) y e l l o w 38 . 8 4 . 0 17 . 0 39 . 0 3.9 17 . 0 Mo(CO) 2N0 orange 25.8 2.1 17 . 4 25. 9 2 . 2 17 . 6 w(co) 2(n 3-c 3H 5) y e l l o w 32 . 1 3 . 0 15.0 31. 8 3 . 0 14 . 8 w(co) 2( n 3-c 4H 7) y e l l o w 34 . 7 3.3 14. 2 33 . 1 3.3 14 . 5 W(C0) 2N0 orange 30 . 6 2.4 21.1 30. 8 2 . 6 21. 0 Mn(C0) 3 p a l e y e l l o w 36 . 8 2.7 20.0 36 . 8 2.8 19. 8 - 75 -Table IV S e l e c t e d M e t a l C a r b o n y l S t r e t c h i n g F r e q u e n c i e s Compound v (cm ) Refe-rence co ( n 5 - C 5 H 5 ) M o ( C O ) 2 ( n 3 - C 3 H 5 ) 19 7 0,1963,1903,1889 27 H B ( N 2 C 3 H 3 ) 3 M o ( C 0 ) 2 ( n 3 - C 3 H 5 ) 1959,1874 62 BuB(N 2C 3H 3) 3Mo(CO) 2 ( n 3 - C 3 H 5 ) 1955 , 1872 62 M e G a ( N 2 C 3 H 3 ) 3 M o ( C O ) 2 ( n 3 - C 3 H 5 ) 1948,1860 t h i s work H B ( N 2 C 3 H 3 ) 3 W ( C 0 ) 2 ( n 3 - C 3 H 3 ) 1949,1862 62 M e G a ( N C H ) w ( C 0 ) „ ( n 3 - C H ) 1940,(1904), . , 2 3 3 3 2 3 5 1 8 5 0 > ( 1 8 1 4 ) t h i s work H B ( N 2 C 3 H 3 ) 3 M o ( C 0 ) 2 ( n 3 - C 4 H 7 ) 1958,1874 62 M e G a ( N 2 C 3 H 3 ) 3 M o ( C 0 ) 2 ( n 3 - C 4 B 7 ) 1949,1863 t h i s work H B ( N 2 C 3 H 3 ) 3 W ( C 0 ) 2 ( n 3 - C 4 H ? ) 1950,1861 62 M e G a ( N 2 C 3 H 3 ) 3 W ( C 0 ) 2 ( n 3 - C 4 H ? ) 1940,1850 t h i s work H B ( N 2 C 3 H 3 ) 3 M n ( C O ) 3 2041,1941 62 M e G a ( N 2 C 3 H 3 ) 3 M n ( C 0 ) 3 2030,1930 t h i s work MeGa(N C H ) Mo(CO) N0 b 2018s,1915s, 1998s ,1896s MeGa(N C H ) W(C0) N0 b 1995s,1895s 1980s,1870s t h i s work t h i s work a c y c l o h e x a n e , ^ N u j o l Table V H N.M.R. Data f o r the " A l l y l " and N i t r o s y l Complexes i n C^Dg S o l v e n t * Me—Sa, Me—Ga, A l l y l Compounds N i t r o s y l Compounds PPM M= R= Mo H W H Mo Me W Me Mo 3-H 1. 2. 1 7 d a ( l ) 21d (2) 1. 2. 1 7 d a ( l ) 0 5 d a (2) 1. 2 . 32br (1) 07br (2) 1. 1. 32br (1) 97br (2) 2 2 .22d a (2) . 6 0 d a ( l ) 4-H 4. 4. 0 6 t a ( 2 ) 1 5 t a ( l ) 4. 4 . 1 5 t a ( 2 ) 2 7 t a ( l ) 4. 4. 07br (2) 17br (1) 4 . 4 . 15br (2) 32br (1) 4 4 . 0 9 t a ( 2 ) . 2 6 t a (1) 5-H 2. 3 . 9 1 d a (2) 20 d a (1) 2. 3 . 98 da(2) 3 2 d a (1) 2. 3. 88br (2) 24br (1) 2. 3 . 96br (2) 36br(1) 2 3 . 94d a (2) .08d a(1) H syn 6 . 5 6 d b (2) 6. 76d b (2) 6 . 63s (2) 6 . 86s (2) H «. • ant 1 8. 4 8 d c (2) 8. 1 7 d c (2) 8. 51s (2) 8 . l i s (2) --R 6. 53br(1) 7 . 18br (1) 8. 68s (3) 8 . 51s(3) --Ga-Me 10 . 08s (3) 10. 14s (3) 10. 08s(3) 10. 14s (3) 10 .04s (3) w 2 . l i d (2) 2 . 5 0 d a ( l ) 4 . 1 5 t a ( 2 ) 4 . 3 3 t a ( l ) 3.02d a (2) 3 . 1 8 d a ( l ) 10.08s (3) *T'(TMS) =10 . 00 ppm, x ( ' C 6D 6 ' )=2 . 84 ppm. R e l a t i v e i n t e n s i t i e s of s i g n a l s g i v e n i n p a r e n t h e s e s , s = s i n g l e t , d=doublet, t = t r i p l e t , br=broad aJ=2 Hz, b J - 7 Hz, CJ=9 Hz. - 77 -Table VI Mass S p e c t r a l Data f o r [MeGa(pz) ]„Zn m / e I n t e n s i t y Assignment 642 7.8 640 24.2 638 44.2 Z n G a 0 ( p z ) , ( M e ) o + 636 50.9 2 6 2 634 26.4 627 7.8 625 16.9 623 30.0 ZnGa„(pz),(Me) 621 33.1 619 20.0 575 573 7.0 571 10.2 ZnGa„(pz).(Me)_ 569 11.7 567 8.6 560 13.6 558 42.7 556 80.6 ZnGa 9(pz),(Me) 554 100.0 552 53.9 507 8.9 505 18.9 503 31.7 ZnGa,(pz),(Me), 501 37.0 499 22.7 425 23.6 423 63.8 Ga (pz),Me 421 48.3 373 30.2 371 78.6 Ga„(pz) (Me) 369 59.7 355 16.4 3 5 1 4 7 > 7 ZnGa(pz) 3(Me) 349 37.0 - 78 -Table VI (cont'd) m/e Int ens i t y Assignment 153 151 71 69 20 . 8 32 . 5 14. 8 21. 3 Ga(pz)Me + G a + Mass Table S p e c t r a l Data f o r V I I [ M e G a ( p z ) 3 ] M n ( C 0 ) 3 m/ e I n t e n s i t y As s i gnment 426 424 3.4 4.4 [ M e G a ( p z ) 3 ] M n ( C 0 ) 3 411 409 1 1 [ G a ( p z ) 3 ] M n ( C O ) 3 + 370 368 2.0 2.4 [MeGa(pz) ] M n ( C 0 )+ 342 340 71.6 100 . 0 [MeGa(pz) ]Mn + 327 325 1.0 2.4 [ M e G a ( p z ) 3 ]+ 153 151 5. 9 8.1 [ M e G a ( p z ) ]+ 138 136 4.6 6.9 [ G a ( p z ) ]+ 71 69 13.1 20.1 G a+ - 79 -Table V I I I Mass S p e c t r a l Data f o r [MeGa (pz ) 3 ]Mo (CO) 2 (n 3-'0 3H ) m/e I n t e n s i t y Assignment 484 6.4 483 482 13.6 481 7.9 480 19.8 479 12.4 [MeGa(pz) ]Mo(C0) (C H,) 478 11.8 477 10.4 476 10.2 475 474 9.3 456 4.0 455 454 5.8 453 4.6 452 8.6 451 7.1 [MeGa(pz),]Mo(CO)(C,H ) 450 7.2 449 4.4 448 5.9 447 446 4.8 428 18.1 427 . -426 75.7 425 32.7 424 100.0 [MeGa(pz) ]Mo(C H ) 423 64.2 J 3 422 70.6 421 53.6 420 50.7 419 . -418 37.9 - 80 -Table V I I I ( cont'd) m/e I n t e n s i t y Assignment 387 16.4 386 385 55.4 384 26.0 383 78.5 [MeGa(pz) ]Mo 382 46.0 381 50.8 380 40.8 379 42.7 378 377 32.6 372 10.1 371 -370 13.7 369 11.3 368 10.1 [Ga(pz) ]Mo 367 10.1 366 9.6 365 4.0 364 6.3 363 362 9.6 71 69 35 . 5 48 . 5 - 81 -Table IX Mass S p e c t r a l Data f o r [MeGa(pz) 3]W(CO) 2N0 m/ e I n t e n s i t y Assignment 559 12 . 5 558 -557 35 . 3 556 12 . 7 555 35 . 6 554 15. 6 553 17 . 0 531 19 . 1 530 -529 45. 5 528 17 . 7 527 47 . 8 526 17 . 7 525 26.0 503 12.1 502 — 501 31. 0 500 15 . 2 499 32. 6 498 11. 4 497 19.1 488 39 . 7 487 -486 98. 8 485 34 . 1 484 100 . 0 483 34.9 482 52.8 473 14.1 472 -471 32 . 2 470 12 . 5 469 32 . 8 468 12. 7 467 18.1 [MeGa(pz) 3]W(C0) 2(NO) + [MeGa(pz) 3]W(C0)(NO) + [Ga(pz) 3]W(N0) + [MeGa(pz) 3]W + - 82 -Table IX (cont'd) m/e I n t e n s i t y Assignment 436 25.4 435 434 66.7 433 23.7 [MeGa(pz) 2]W(NO) 432 69.6 431 35.6 430 35.6 71 50.3 + 69 36.6 ^ a T h e o r e t i c a l F i g u r e 28 D i s t r i b u t i o n s of G a l l i u m I s o t o p e s •100.0 Ga 65.6 69 70 71 mass number G a 2 100,0 76.3 32.8 138 139 U0 H1 U2 relative intensity r Ga 3 100.0 656 S0.8 r relative intensity 207 208 209 210 211 212 213 mass number Ga^ 100.0 38.1 96 4 4 3.0 7.0 -L mass number 276 277 278 279 280 281 282 283 284 mass number T h e o r e t i c a l D i s t r i b u t i o n s of Mixed M e t a l I s o t o p e s F i g u r e 29 F i g u r e 30 relative intensity relative intensity Z n - Ga 100.0 81.7 6.9 61.5 4.51 21.3 0.7 133 134 135 136 137 138 139 140 141 mass number Z n - G a , 100.0 53.2 82.7 45 40.2 53 9.6 0.3 202 203 204 205 206 207 206 209 210 211 212 moss number relative intensity relative intensity M o - G a 1000 64.B 56.1 45B 45.4 57.1 72.9 17.9 18.2 161 162 163 164 165 166 167 168 169 1 70 171 mass number W - G a 54.7 0.3 98.9 29.7 19.5 100.0 38.4 249 250 251 252 253 254 255 256 257 moss number OO - P -- 85 -3-2. The [MeGa(dmpz) 3] L i g a n d T h i s c h a p t e r d e s c r i b e s the s y n t h e s i s of the v e r y s t e r i c a l l y demanding g a l l i u m l i g a n d , m e t h y l t r i s ( 3 , 5 - d i m e t h y l -p y r a z o l y l ) g a l l a t e , [MeGa(dmpz)^] (dmpz=(^C^H^), and an i n v e s t i g a t i o n of i t s c o o r d i n a t i n g a b i l i t y w i t h t r a n s i t i o n 2 + metal M i o n s (M=Co,Ni) and a l s o d e s c r i b e s d e r i v a t i v e s formed by the i n t e r a c t i o n of the l i g a n d w i t h Mn, Mo and W c a r b o n y l compounds. The i n t r o d u c t i o n of methyl groups i n the 3 and 5 p o s i t i o n s of the p y r a z o l y l r i n g s i n the analogous boron l i g a n d [HB(dmpz) 3] l e d to g r e a t e r t h e r m a l s t a b i l i t y of the r e s u l t i n g t r a n s i t i o n m e tal complexes [HB(dmpz) 3] 2M (M=Mn,Fe,Co,Ni,Cu,Zn) (22) compared to the [ H B ( p z ) 3 ] 2 M complexes ( 2 1 ) . In c a r b o n y l complexes such as [HB(dmpz)^Mo(CO)^] , the presence of a l k y l s u b s t i t u e n t s i n the 3 p o s i t i o n s r e s u l t e d i n an i n c r e a s e i n e l e c t r o n d e n s i t y on the Mo atom and, i n a d d i t i o n , r e s t r i c t e d a ccess to the m e t a l by p r o s p e c t i v e r e a c t a n t s . The r e s u l t was i n c r e a s e d s t a b i l i t y of t h i s d e r i -v a t i v e . N i t r o s y l a t i o n of the p a r e n t a n i o n [HB(pz)^Mo(CO)^] and the m e t h y l a t e d d e r i v a t i v e [HB(dmpz)^Mo(CO)^] was found to proceed e q u a l l y w e l l ( 3 3 ) . However, the r e a c t i o n of 3-bromopropene w i t h the [HB(dmpz)^Mo(CO) 3] i o n does not occur under c o n d i t i o n s where the pare n t i o n r e a c t s r a p i d l y . The o [ H B ( d m p z ) 3 ] M o ( C 0 ) 2 ( n J _ C 3 H 5 ) compl ex has been p r e p a r e d i n -d i r e c t l y (30) and i s q u i t e s t a b l e . Some analomous r e a c t i o n s were noted w i t h the - 86 -[HB(dmpz) 3Mo(CO) ] ~ a n i o n (33). T h i s s t e r i c a l l y h i n d e r e d a n i o n r e a c t s w i t h ArSO^Cl (Ar = p h e n y l , p - t o l y l , p - c h l o r o , p-bromo) to y i e l d the s t a b l e , monomeric red d e r i v a t i v e s [HB(dmpz) 3]Mo(CO)^SAr. The a r y l m e r c a p t o s t r u c t u r e was un-e x p e c t e d , s i n c e a s u l f i n a t e or s u l f o n e product would be a n t i -c i p a t e d . Another p o s s a b i l i t y would be e x t r u s i o n of SO2 to g i v e an M-Ar s p e c i e s . The [HB(dmpz)^Mo(CO) ] a n i o n a l s o r e a c t e d anomalously w i t h a r y l d i a z o n i u m i o n s , Ar^"*" (Ar = p h e n y l , or p - n i t r o p h e n y l ) to y i e l d the b l u e d e r i v a t i v e s [HB(dmpz) 3] Mo(CO) 3Ar (3 3 ) . The c o r r e s p o n d i n g g a l l i u m l i g a n d , [MeGa(dmpz) 3] , i s expected to be even more s t e r i c a l l y demanding than the boron l i g a n d , as Ga-N bond d i s t a n c e s , t y p i c a l l y about 1.99 A (3 6 ) , are s i g n i f i c a n t l y l o n g e r than B-N bond d i s t a n c e s , which o are about 1.54 A (25,62). T h i s would cause the 3-methyl groups of each 3 , 5 - d i m e t h y l p y r a z o l y l moiety (see F i g u r e 31) to move c l o s e r to the c e n t r a l m e t a l M, i n c r e a s i n g s t e r i c crowding around the m e t a l . F i g u r e 31 X . - 87 -The l i g a n d was s y n t h e s i z e d and handled i n e x a c t l y the same manner as the [MeGaCpz)^] l i g a n d , by r e a c t i n g t h r e e molar e q u i v a l e n t s of sodium ( 3 , 5 - d i m e t h y l p y r a z o l i d e ) w i t h m e t h y l d i c h l o r o g a l l a n e i n THF s o l v e n t to g i v e the d e s i r e d p r o d u c t , Na +[MeGa(dmpz)^J , which was not i s o l a t e d as a s o l i d but r e a c t e d i n measured a l i q u o t s i n the THF s o l v e n t . T H F H- — MeGaCl + 3Na(dmpz) — •Na [MeGa(dmpz) ] (34) + 2NaCl Attempted p r e p a r a t i o n of the b i s l i g a n d t r a n s i t i o n m etal complexes by the r e a c t i o n of s t o i c h i o m e t r i c q u a n t i t i e s of the l i g a n d w i t h a metal h a l i d e i n THF s o l v e n t caused the p r e c i p i t a t i o n of a s m a l l amount of sodium h a l i d e and c o l o r a -t i o n changes i n the s o l u t i o n , however, no s i m p l e complexes of the type [MeGa(dmpz) ] 2M c o u l d be i s o l a t e d : MX 2 + 2 N a + [ M e G a ( d m p z ) 3 ] ~ — T R F » [MeGa(dmpz) ] 2M + 2NaX (where M = Co, N i , X = h a l i d e ) - (35) T h i s r e s u l t r e f l e c t s the g r e a t e r s t e r i c crowding of the 3-methyl groups on each 3 , 5 - d i m e t h y l p y r a z o l y l moiety around the c e n t r a l t r a n s i t i o n m e tal M, which p r e v e n t s these complexes f o r m i n g . The r e s u l t i n g p r o d u c t s were i s o l a t e d as i n t r a c t a b l e powders. The s y n t h e s i s of [MeGa(dmpz)^]CuCO was a l s o attempted to see i f the [MeGa(dmpz)^] l i g a n d c o u l d form a s t a b l e Cu(I) - 88 -c a r b o n y l complex. R e a c t i o n of the l i g a n d w i t h one e q u i v a l e n t of CuCl i n THF s o l v e n t , f o l l o w e d by tr e a t m e n t of the i s o l a t e d s o l u t i o n w i t h excess CO gas r e s u l t e d , a f t e r p r o d u c t work-up, i n an i n t r a c t a b l e b l u e s o l i d : + - rn CuCl + Na [MeGa(dmpz)„] — I , " » [MeGa(dmpz),]CuCO + NaCl (36) The c o r r e s p o n d i n g boron compound, [HB(pz) 3]CuCO ( 2 8 ) , i s an a i r and heat s t a b l e complex, r e s i s t i n g h e a t i n g to over 100°C. The a n a l y t i c a l d ata f o r the metal c a r b o n y l complexes pr e p a r e d are l i s t e d i n Table X. The [MeGa(dmpz) 3]M(C0) 2N0 (M=Mo,W) complexes were prepared by t r e a t i n g the [MeGa(dmpz)^M(CO)^] i n t e r m e d i a t e s a l t w i t h an excess of i s o a m y l n i t r i t e i n the f o l l o w i n g scheme: _ l _ _ T" IJ 7? - f -M ( C 0 ) 6 + Na [MeGa (dmpz) 3 ] —-r—»~Na [MeGa (dmpz ) 3M (CO) ] + 3C0 (37) Na +[MeGa(dmpz) 3M(CO) 3]" + C H^ONO T H F » [MeGa (dmpz) ] M(C0) 2N0 + CO + N a + ( C 5 H 1 ; L 0 ) ~ (38) (M=Mo, W) The t u n g s t e n r e a c t i o n s , however, r e q u i r e d more f o r c i n g c o n d i -t i o n s than the molybdenum r e a c t i o n s . Attempted s y n t h e s i s of the [MeGa(dmpz) 3]M(CO) 2 3 ( i i -C 3H^R) d e r i v a t i v e s by r e a c t i o n of the [MeGa (dmpz) (CO) 3 ] 89 -i n t e r m e d i a t e ( e q u a t i o n 39) w i t h C^H^RX (R=H, X=Br, R=Me, X=C1) f a i l e d t o g i v e the expected p r o d u c t s . I n s t e a d , the o n l y product i s o l a t e d was the y e l l o w c r y s t a l l i n e hydroxy s p e c i e s [ M e G a ( d m p z ) 2 ( O H ) ] M o ( C O ) 2 ( n 3 - ^ . , ) . ~i~ — T "H V Na [MeGa(dmpz)_M(CO)_] + CH =CRCH„X [MeGa(dmpz) 3]M(CO) 2(n 3-C 3H 4R) + CO + NaX (39) (M=Mo,W, and R=H, X=Br; R=Me, X=C1) The a l t e r n a t e r o u t e (30) u s i n g (CH CN.) 3M (CO) 3 (M=Mo, W) (60) as a s t a r t i n g m a t e r i a l a g a i n proved to be a more 3 e f f i c i e n t way to s y n t h e s i z e " n - a l l y l " d e r i v a t i v e s of Mo and W, however, the p r o d u c t s i s o l a t e d were not the expected 3 [MeGa(dmpz) 3]M(C0) 2(n -C 3H 4R) d e r i v a t i v e s ( e q u a t i o n s 40-41), but a g a i n the hydroxy compounds [MeGa(dmpz) (OH)]Mo(C0) ( n 3 - C 3 H 5 ) , [ M e G a ( d m p z ) 2 ( O H ) ] M o ( C O ) 2 ( n 3 - C 4 H 7 ) , and [MeGa(dmpz) 2 ( O H ) ] w ( c o ) 2 ( n 3 - c 4 H 7 ) . THF (CH 3CN) 3M(CO) 3 + xs CH 2 = CRCH 2X » (CH^N) 2M (CO) (X) ( n 3-C 3H 4R) + 2CH 3CN + CO (40) O _L T U T ? ( C H C N ) 2 M ( C O ) 2 ( X ) ( n - C H 4R) + N a [MeGa(dmpz) ] » [MeGa(dmpz) 3]M(CO) 2(n 3-C 3H 4R) + 2CH 3CN + NaX (41) (where M=Mo, W, and R=H, X=Br; R=Me, X=C1) - 90 -The f o r m a t i o n of the t u n g s t e n compound r e q u i r e d warming of the THF s o l v e n t i n the f i r s t s t e p . Attempted s y n t h e s i s of 3 the [MeGa (dmpz ) 2 (OH) ]W(C0) 2 (n -C H 5) d e r i v a t i v e v i a t h i s r o u t e f a i l e d , as the o n l y product was a yellow-brown g l u e . The manganese c a r b o n y l compound was p r e p a r e d by r e f l u x i n g Mn(C0),-Br w i t h one e q u i v a l e n t of the l i g a n d i n THF s o l v e n t . _ i _ _ T H F Mn(C0) 5Br + Na [MeGa(dmpz) 3] ^ * [MeGa(dmpz) 3]Mn(CO) 3 + 2C0 + NaBr (42) The i n t e g r i t y of the t r i s - c h e l a t i n g l i g a n d [MeGa ( d m p z ) h a s been proven by the i s o l a t i o n of the above man-ganese t r i c a r b o n y l compound and the two n i t r o s y l complexes l i s t e d i n T able X. In a l l t h r e e of these compounds the s t e r i c a l l y demanding g a l l i u m l i g a n d has the r e q u i r e d space to occupy the t h r e e f a c i a l p o s i t i o n s demanded by i t s geometry i n the o c t a h e d r a l complexes.. Attempted i n t r o d u c t i o n of l a r g e r s u b s t i t u e n t s i n t o the [MeGa(dmpz) 3M(CO) 3] i o n s (M=Mo, W) does not y i e l d the expected complexes but i n s t e a d the observed hydroxy s p e c i e s , or i n t r a c t a b l e p r o d u c t s . The o r i g i n of the 'OH' group i n t h e s e complexes i s p u z z l i n g s i n c e a l l s o l v e n t s were d r i e d and the y i e l d s of 'OH' p r o d u c t s were r e l a t i v e l y h i g h and uncontaminated w i t h the expected t r i s - c h e l a t e com-p l e x e s . I t i s t e m p t i n g to s p e c u l a t e a b s t r a c t i o n of the 'OH' from the THF s o l v e n t , but f u r t h e r s t u d i e s w i l l be n e c e s s a r y to e s t a b l i s h t h i s as i t s o r i g i n . Perhaps more r i g o r o u s d r y i n g - 91 -of the THF w i t h Na/benzophenone i s r e q u i r e d . The i n f r a r e d data f o r the c a r b o n y l complexes are a l s o g i v e n i n Table X. The n i t r o s y l complexes showed two v bands and a s i n g l e v band i n t h e i r CH2CI2 s o l u t i o n i n f r a r e d s p e c t r a . T h i s p a t t e r n i s expected f o r an o c t a h e d r a l complexes i n which the t h r e e 3 , 5 - d i m e t h y l p y r a z o l y l groups occupy t h r e e f a c i a l p o s i t i o n s (70). The spectrum i n N u j o l of the t u n g s t e n d e r i -v a t i v e showed a s p l i t band which presumably a r i s e s from s o l i d s t a t e e f f e c t s . A l l the bands f o r the t u n g s t e n compound are somewhat lower i n frequ e n c y than the bands f o r the moly-bdenum compound. T h i s e f f e c t has been noted i n s e v e r a l o t h e r s t u d i e s (2 7,33,64). The manganese t r i c a r b o n y l compound i n N u j o l gave the two w e l l d e f i n e d v r n bands expected f o r an o c t a h e d r a l complex w i t h a s y m m e t r i c a l t r i s - c h e l a t i n g f a c i a l l i g a n d o c c u p y i n g the t h r e e r e m a i n i n g c o o r d i n a t i o n p o s i t i o n s . The lower f r e q u e n c y e mode band was much broader and of s l i g h t l y g r e a t e r i n t e n s i t y than the s h a r p , h i g h e r f r e q u e n c y a^ mode band, a f e a t u r e t y p i c a l l y found i n t h i s type of complex (7 0 ) . The i n f r a r e d s p e c t r a of a l l t h r e e hydroxy, d e r i v a t i v e s were r e c o r d e d i n both N u j o l and c y c l o h e x a n e . The f i r s t i n d i c a -t i o n of the t r u e n a t u r e of these complexes was the appearance of a s t r e t c h i n g v i b r a t i o n i n the 3550-3630 cm ^ r e g i o n of the i n f r a r e d s p e c t r a i n N u j o l . The expected s h a r p , e q u a l i n -t e n s i t y symmetric and asymmetric v s t r e t c h e s were observed - - 92 -i n the cycl o h e x a n e s o l u t i o n i n f r a r e d s p e c t r a of a l l t h r e e compounds. Aga i n the bands f o r the t u n g s t e n compound were at lower f r e q u e n c i e s than the bands f o r the two molybdenum 3 compounds. Comparison of the v p n f r e q u e n c i e s f o r the "n -a l l y l " complexes w i t h the v p n f r e q u e n c i e s of s i m i l a r complexes b e a r i n g d i f f e r e n t u n i n e g a t i v e s i x - e l e c t r o n l i g a n d s , as g i v e n i n T a b l e X I , i n d i c a t e s t h a t the p r e s e n t l i g a n d s c r e a t e a more e l e c t r o n r i c h t r a n s i t i o n m e t a l c e n t r e w i t h consequent l o w e r i n g of the VQQ f r e q u e n c i e s . The bond l e n g t h d a t a found i n the c r y s t a l s t r u c t u r e d e t e r m i n a t i o n of the [MeGa(dmpz)^(OH)]Mo(CO)^ 3 (n -C^Hj.) d e r i v a t i v e i s c o n s i s t e n t w i t h these o b s e r v a t i o n s . The mass s p e c t r a of a l l s i x c a r b o n y l compounds l i s t e d i n Table X d i s p l a y p a r e n t i o n s i g n a l s . The r e s u l t s i n d i c a t e the same monomeric n a t u r e f o r the p r o d u c t s i n the gas phase as i s suggested by o t h e r evidence f o r the compounds i n s o l u -t i o n . The s o l i d s t a t e x-ray s t r u c t u r a l d e t e r m i n a t i o n of the 3 [MeGa(dmpz) 2(OH)]Mo(CO) 2 ( n -C^H^ complex demonstrates t h i s c o n c l u s i v e l y (71) (see F i g u r e 35). The mass s p e c t r a of the molybdenum compounds gave w e l l - d e f i n e d 9 - l i n e p a t t e r n s of c l o s e to the t h e o r e t i c a l i n -t e n s i t y r a t i o p r e d i c t e d f o r a l l i o n s c o n t a i n i n g both a Mo and a Ga atom (see F i g u r e 30). S i m i l a r l y , the mass s p e c t r a of the t u n g s t e n compounds gave c h a r a c t e r i s t i c 6 - l i n e p a t t e r n s which xvere close to the t h e o r e t i c a l i n t e n s i t y r a t i o p r e d i c t e d f o r a l l i o n s c o n t a i n i n g both a W and a Ga atom (see F i g u r e 30). The s t r o n g e s t s i g n a l i n the spectrum of the moly-- 93 -bdenum n i t r o s y l complex was t h a t c o r r e s p o n d i n g to the p a r e n t i o n minus two CO groups, w i t h the s i g n a l from the p a r e n t i o n minus two CO groups and the NO group b e i n g almost as i n t e n s e . The p a r e n t i o n i t s e l f was r o u g h l y o n e - t e n t h as s t r o n g as these two s i g n a l s . For the t u n g s t e n compound, the two s t r o n g e s t s i g n a l s were due to the parent i o n minus one CO group and the parent i o n minus two CO groups. S i g n a l s due to the paren t i o n , the p a r e n t minus two CO groups and a Me group, and the pa r e n t minus two CO groups and the NO group were about one-h a l f as i n t e n s e as the s t r o n g e s t s i g n a l s . The p r i n c i p a l f e a t u r e s of the mass spectrum of [MeGa(dmpz) 2(OH)]Mo(CO) 2(n 3-C 4H 7) are r e c o r d e d , t o g e t h e r w i t h t h e i r t e n t a t i v e a s s i g n m e n t s , i n Table X I I . The mass s p e c t r a of a l l the hydroxy d e r i v a t i v e s d i s p l a y e d v e r y s t r o n g s i g n a l s due to the i o n o b t a i n e d by e j e c t i o n of two CO groups and a 3 , 5 - d i m e t h y l p y r a z o l e group from the p a r e n t i o n , v i z [MeGa.^_^/-M-n - a l l y l ] , I n d i c a t i n g a g a i n (72) the i n t r i n s i c s t a b i l i t y of the five-membered r i n g system, Ga^^^.M. Step-wise l o s s of CO groups, the " a l l y l " group, and a Me group were a l s o i n d i c a t e d by s t r o n g s i g n a l s due to the a p p r o p r i a t e i o n s . The p a r e n t i o n s themselves gave s i g n a l s about o n e - f i f t h the i n t e n s i t y of the s t r o n g e s t s i g n a l s i n the two Mo s p e c t r a , whereas i n the W spectrum the paren t i o n s i g n a l was o n e - h a l f the i n t e n s i t y of the s t r o n g e s t s i g n a l . The mass spectrum of the manganese t r i c a r b o n y l com-p l e x was dominated by the v e r y s t r o n g s i g n a l due to the paren t - 94 -i o n minus t h r e e CO groups. A l l o t h e r s i g n a l s were weak by comparison, but the parent i o n s i g n a l was r e a d i l y d e t e c t e d . The ''"H n.m.r. s p e c t r a f o r the two n i t r o s y l compounds are r e p o r t e d i n Table X I I I . The '''H n.m.r. spectrum of the [MeGa(dmpz)^]W(CO) 2N0 complex i n C^D^ i s shown i n f i g u r e 32. In these complexes the t h r e e 3 , 5 - d i m e t h y l p y r a z o l y l groups occupy two s e t s of p o s i t i o n s . Two of these groupings are i d e n t i c a l whereas the t h i r d , t r a n s to the NO group, i s unique. T h i s l e a d s to the observed s p e c t r a where the 4-H p r o t o n and the 3-Me and 5-Me p r o t o n s g i v e two s i g n a l s each i n a 2:1 r a t i o . The Ga-Me s i g n a l o c c u r s as a s h a r p , h i g h f i e l d s i n g l e t i n both s p e c t r a . The "*"H n.m.r. s p e c t r a of the t h r e e hydroxy compounds are more c o m p l i c a t e d than those of the above n i t r o s y l d e r i v a -t i v e s but the m a j o r i t y of the f e a t u r e s r e c o r d e d are r e a d i l y e x p l i c a b l e i n terms of the o c t a h e d r a l s t r u c t u r e demonstrated 3 f o r [MeGa(dmpz) 2(OH)]Mo(CO) 2(n - C 4 H ? ) i n the s o l i d s t a t e , (see f i g u r e 33). In t h i s complex the n - 2 - m e t h a l l y l group i s p o s i t i o n e d t r a n s to one of the 3 , 5 - d i m e t h y l p y r a z o l y 1 groups and c i s to both the second 3 , 5 - d i m e t h y l p y r a z o l y l group and to the OH group. The 1H n.m.r. r e s u l t s s i s t e n t w i t h t h i s same s t r u c t u r e f o r a l l t h r e e hydroxy compounds i n C^D^ s o l u t i o n . Thus, the two 3 , 5 - d i m e t h y l -p y r a z o l y l groups are d i f f e r e n t and g i v e two s e t s of s i g n a l s f o r the 4-H, 3-Me and 5-Me p r o t o n s i n a l l t h r e e s p e c t r a :s are con-- 95 -i n the expected 1:1 r a t i o (see Table X I I I ) . The s i g n a l s due 3 3 to the pr o t o n s on the n ~C.jH and n -C^H^ groups have been a s s i g n e d by comparison w i t h analogous complexes (66,67), and a l s o u s i n g the assignments g i v e n i n r e f e r e n c e 68. The 1H n.m.r. spectrum of the [MeGa(dmpz) (OH)]Mo 3 (CO)„(n -C.H ) complex i n C rD i s shown i n f i g u r e 33. The z H I D 6 3 s p e c t r a of the two n -C^H^ c o n t a i n i n g complexes were s i m i l a r and, as e x p e c t e d , the two d i f f e r e n t p r o t o n s gave two s e p a r a t e s i n g l e t s at h i g h e r f i e l d than the two H g y n p r o t o n s i g n a l s . The l a t t e r , however, were not the expected s i n g l e t s but r a t h e r o c c u r r e d as d o u b l e t s (J=4.5 Hz) w i t h one of these d o u b l e t s b e i n g f u r t h e r ; s p l i t ( J = 2Hz). The o r i g i n of these c o u p l i n g s i s not r e a d i l y : i d e n t i f i e d . b u t the s i z e of the major c o u p l i n g i s probably too l a r g e to be the r e s u l t of H -H r ° r J b syn antx geminal c o u p l i n g , which i s n o r m a l l y l e s s than 1 Hz (68 ) . The 3 2-Me group on n shows the expected s i n g l e t of the c o r r e c t i n t e n s i t y i n b o t h s p e c t r a . The "^H n.m.r. spectrum of the [MeGa (dmpz) (OH) ]Mo 3 (CO) 2 ( n _ C 3 H 5 ) complex at 270 MHz (see F i g u r e 34) gave a 3 r e a d i l y i n t e r p r e t a b l e s e t of n -C^H^ p r o t o n s i g n a l s . The unique p r o t o n s i g n a l appeared as a t r i p l e t of t r i p l e t s due to c o u p l i n g to b o t h H . . and H p r o t o n s (see e x p a n s i o n , a n t i syn r ' F i g u r e 34a). A l l f o u r syn and a n t i p r o t o n s i g n a l s appeared as d o u b l e t s due to c o u p l i n g w i t h the unique p r o t o n and, i n a d d i t i o n , some s m a l l e r c o u p l i n g (J=2Hz) was e v i d e n t i n the s i g n a l s due to the syn p r o t o n s . "I—I—' L-.J—J—I 1—I—1—I—I—l—1—|—| | t I . i l • l ! , , , j 1 I II I I 1 1 • 1 I ' l l I ^ l ' ' v ' ' i r ' ' ' ' ' ' ' ' ' ' M ' ' ' ' ; i ' ' V " M looa I 10 I U L 1 I I I ' I I I I I I | I I I I | | l I I I | I I | I | | | | , | | | 1 1 1 1 1 1 I ' ' I I I I I ' I I I I ,1 I | I I I I | , VD F i g u r e 32 100 MHz F.T. H N.M.R. Spectrum of [MeGa(dmpz)„]W(C0)„N0 i n C,D, 3 2 6 6 F i g u r e 33 1 100 MHz F.T. H N.M.R. Spectrum of [MeGa (dmpz) 2 (OH) ]Mo (CO) 2 (n - C ^ ) i n C^D, 6 o VO 00 F i g u r e 34 270 MHz F.T. 1H N.M.R. Spectrum of [MeGa(dmpz) 2(OH)]Mo(CO) 2 ( n ~C 3H 5) i n C ^ VO VO F i g u r e 34a 270 MHz F.T. 1H N.M.R. Spectrum of [MeGa(dmpz) 2(OH)]Mo(CO) 2(n -CgHg) i n CgDg. Expansion of n 3 - a l l y l Region (Sweep Width 870 Hz; 3.00 ppm) - 100 -3 A l l t h r e e s p e c t r a c l e a r l y i n d i c a t e t h a t the "n -a l l y l " groups are not undergoing r a p i d r o t a t i o n about the M-3 n - a l l y l a x i s i n s o l u t i o n , a p r o c e s s which would make both syn p r o t o n s e q u i v a l e n t and both a n t i p r o t o n s e q u i v a l e n t . In a l l t h r e e s p e c t r a the OH and Ga-Me s i g n a l s o c c u r r e d at h i g h f i e l d as s i n g l e t s i n the expected i n t e n s i t y r a t i o of 1:3. The c r y s t a l l o g r a p h i c a n a l y s i s of the d i c a r b o n y l [ m e t h y l b i s (3,5-dimethy1 ( 1 - p y r a z o l y l ) h y d r o x y g a l l a t o ( N ( 2 ) , 3 N_(_2 ) ' , 0_) ] (n - 2 - m e t h a l l y l ) molybdenum complex, [MeGa(dmpz)2 3 (OH) ]Mo (CO) 2 (n -C^H.,), (83) c o n f i r m s the t r i d e n t a t e c h e l a t i n g n a t u r e of the [MeGa(dmpz)^(OH)] l i g a n d . M o l e c u l a r models i n d i c a t e t h a t the s t e r i c crowding i n h e r e n t i n the [MeGa(dmpz)^] 3 MoCCO^di "C^H-/) mo l e c u l e i s d r a s t i c a l l y reduced i n the hydroxy complex [ M e G a ( d m p z ) 2 ( O H ) ] M o ( C 0 ) 2 ( n ^ - c 4 H 7 ) (see F i g u r e 35). A s i m i l a r phenomenon was p r e v i o u s l y noted w i t h the [Me2Ga(dmpz)]^ dimer ( 3 7 ) , where the a t t a c k of m o i s t u r e on the dimer l e d to the f o r m a t i o n of the h y d roxy-br idged s p e c i e s [Me2Ga (^C^-H.,) (OH) G a M e „ • 2 ( N C H ) ] (see F i g u r e 1 0 ) , t h e r e b y r e l i e v i n g s t e r i c / 2 -> o s t r a i n i n h e r e n t i n the p l a n a r dimer (see F i g u r e 9) between the m e t h y l groups on the g a l l i u m atoms and on the b r i d g i n g 3 , 5 - d i m e t h y l p y r a z o l y l m o i e t i e s . In the p r e s e n t compound, the Ga...Mo d i s t a n c e of ° o 3.329(1)A i s c o n s i d e r a b l y s h o r t e r than the d i s t a n c e of 3.67A found f o r [MeGa(pz)^ ]Mo (CO) 2 (n^-C^H,.) (64). The h y d r o x y l b r i d g e e f f e c t i v e l y p u l l s back the Mo atom c r e a t i n g much more - 101 -space i n p o s i t i o n s t r a n s to the 3 , 5 - d i m e t h y l p y r a z o l y l groups i n o c t a h e d r a l complexes. The Mo atom has d i s t o r t e d o c t a h e d r a l 3 c o o r d i n a t i o n geometry w i t h the n -C H groups o c c u p y i n g an 4 ' o c t a h e d r a l c o o r d i n a t i o n s i t e t r a n s to a p y r a z o l y l . n i t r o g e n atom and a c t i n g as a T T - d o n a t i n g l i g a n d (Mo-C 2 . 334 ( 6 ) , 2.263(5) and 2.359(6)1). The Mo-N d i s t a n c e s (2.283(4) and o 2.242(4)A) are s i g n i f i c a n t l y d i f f e r e n t , the bond t r a n s to the 3 n -C^H^ group b e i n g s h o r t e r as expected. There i s a s m a l l (1.7a) d i f f e r e n c e between the two Mo-C(O) d i s t a n c e s (1.920(5) o and 1.933(6)A), the s h o r t e r b e i n g t r a n s to the OH b r i d g e . The o Mo-0 bond l e n g t h of 2.272(4)A i s r a t h e r l o n g f o r s t e r i c r e a s o n s . S t e r i c e f f e c t s are the dominant f a c t o r i n the bond l e n g t h i n e q u a l i t i e s mentioned above as w e l l as i n the f o l l o w i n g n o t a b l e f e a t u r e s of the pr e s e n t s t r u c t u r e . The 3 , 5 ~ d i m e t h y l -2 p y r a z o l y l r i n g t r a n s to the " a l l y l " group i s p l a n a r (x =2.5) w i t h both methyl carbon atoms and both m e t a l atoms s i g n i f i c a n t l y d i s p l a c e d from the mean plan e (Mo, 0.0499(4), Ga, -0.0993(6), C ( 1 3 ) , -0 . 063 ( 8 ) , and C ( 1 4 ) , -0 .035 (9)1). The o t h e r 3 , 5 - d i -m e t h y l p y r a z o l y l group, c i s to the 2 - m e t h a l l y l , i s s e v e r e l y d i s t o r t e d . The five-membered r i n g i s s i g n i f i c a n t l y n o n-planar 2 (x =16.8) and bo t h atoms are c o n s i d e r a b l y d i s p l a c e d from the mean plan e (Mo, -0.2097(4), Ga, 0.6670(5)1) w h i l e o n l y one of the methyl carbons i s out of the plane ( C ( 1 6 ) , 0.071(8)1). The t o r s i o n a n g l e Ga[N(3)-N(4)]Mo, i d e a l l y z e r o , i s 26.9(3)°, and G a [ N ( l ) - N ( 2 ) ] M o i s 5.2(3)°. R e l a t i v e to the s t r u c t u r e of [MeGa(pz)^]Mo(CO) 0 - 102 -3 (n -C^H^) (see f i g u r e 2 7 ) , t h e r e are s e v e r a l n o t a b l e d i f f e r e n -ces. The Mo-N d i s t a n c e s i n [MeGa(dmpz) (OH)]Mo(CO) ( n 3 - C 4 H 7 ) 3 l i e between those found i n [MeGa(pz) 3]Mo(CO) 2(n -C 3H 5) ( c i s 2.328(3) and 2.309(3), t r a n s , 2.232(3) A ) . S u b s t i t u t i o n of a l l y l by 2 - m e t h a l l y l i n c r e a s e s the c e n t r a l M o - C ( a l l y l ) d i s -o tances from 2.228(5) to 2.263(5)A w i t h o u t changing the o t h e r two M o - C ( a l l y l ) d i s t a n c e s . A l l of the M o - " a l l y l " d i s t a n c e s i n the p r e s e n t s t r u c t u r e a re i n good agreement w i t h those 3 found f o r the r e l a t e d boron complex [HB(pz) ]Mo(CO) 2(n -C^H^) (62). The Mo-C(O) bonds i n the hydroxy compound are about 3 2a s h o r t e r than those found i n [ M e G a ( p z ) 3 ] M o ( C O ) 2 ( n -C H 5) o (1.936(5) and 1.948(5)A) and s i g n i f i c a n t l y s h o r t e r than those i n the boron complex (1.958(5) and 1. 9 5 9 ( 5 ) ! ) . At the same ti m e , the C-0 d i s t a n c e s are l o n g e r (mean v a l u e s 1.176(2), 1.162(2), and 1.151(1)A) r e s p e c t i v e l y f o r the hydroxy compound, 3 the [ M e G a ( p z ) 3 ] M o ( C O ) 2 ( n -C3H,.) complex, and the boron complex. These data are c o n s i s t e n t w i t h the v r n i n f r a r e d v a l u e s (see Tables X and X I ) , and suggest a more e l e c t r o n r i c h Mo c e n t r e i s c r e a t e d by the hydroxy l i g a n d . The Mo-C-0 gro u p i n g s are s i g n i f i c a n t l y more bent (173.5(5)° and 173.7(5)°) than i n the [MeGa(pz) 3]Mo ( C 0 ) 2 ( n 3-C 3H 5) complex (177.2(5)° and 176.5(5)° and the OC-Mo-CO angle i s reduced from 81.2(2)° to 75.7(2)°. The c o o r d i n a t i o n about the g a l l i u m atom i s d i s t o r t e d t e t r a h e d r a l . The two Ga-N bond l e n g t h s are s i g n i f i c a n t l y d i f f e r e n t (1.962(4) and 1.943(4)1), the l o n g e r one b e i n g a s s o c i a t e d w i t h the t r a n s 3 , 5 - d i m e t h y l p y r a z o l y l group which - 103 -has the s h o r t e r Mo-N bond. Both Ga-N bonds are s i g n i f i c a n t l y 3 longer than t h e i r c o u n t e r p a r t s i n [MeGa(pz)^]Mo(CO)^(n ~ C 3 H 5 ) ( 1 . 9 3 8 ( 4 ) , 1.922(4) and 1.917(3 )1 ) . Other bond l e n g t h s i n the m o l e c u l e are as exp e c t e d . The t r i v a l e n t oxygen atom has p y r a m i d a l c o o r d i n a t i o n (mean angle at 0(1) i s 110.5°). The f o u r carbon atoms of the 3 2 n -C^H^ group are c o p l a n a r (x =1.3) but t h r e e of the f o u r methylene hydrogen atoms are s i g n i f i c a n t l y d i s p l a c e d from the mean p l a n e ( H ( 8 a ) , 0.18 ( 5 ) , H(8b) , - 0 . 4 0 ( 6 ) , H(10a), - 0 . 3 9 ( 5 ) , H(10b), 0.11(6), Mo 2.0126(4 )1 ) . The c r y s t a l s t r u c t u r e con-s i s t s of d i s c r e t e m o l e c u l e s , t h e s h o r t e s t non-bonded d i s t a n c e between the mo l e c u l e s b e i n g Ga...0)3), 3.222(4 )1 . F i g u r e 35 A S t e r e o v i e w of [MeGa (dmpz) (OH)]Mo(CO)„(n3-C H ) A 2 4 7 Table X Analytical And Selected I.R. Data for Complexes Incorporating the »3]" Liga Analysis [MeGa(dmpz)3 nd and its Hydroxy Derivatives Found % C H N v c o ( c m ) Calc % C H N Nujol CH2C12 Cyclohexane Nujol CH2C12 Nujol [MeGa(N2C5H7)3]Mo(CO)2NO 39.3 4.4 18.0 39.2 4.4 17. [MeGa(N2C5H7)3]W(CO)2NO 34.1 3.8 14.8 33.8 3.8 15. [MeGa(N2C5H7)3]Mn(CO)3 44.7 4.9 16.4 44.8 4.8 16. [MeGa(N2C5H7)2(OH)]Mo(CO)2(n3-CAH?) 41.2 5.0 11.5 40.9 5.1 11. [MeGa(N C H ),(0H)]W(C0)?(n3-C,H ) 35.0 4.2 9.4 34.8 4.3 9.5 1905 1 5 ' 1 * 1790 [MeGa(N C H ) (0H)]Mo(C0) (n3-C,H ) 40.3 4.8 11.4 39.6 4.7 11.6 1922 13 11 l <t l g 2 5 2010 1905 2007 1914 1990 1880 1995 1891 2022 1910 1910 1815 1795 1940 1850 1905 1790 1930 1837 19218  1940 1850 1665 1650 1640 1634 1620 3630 3550 3660 o -p-- 105 -Table XI S e l e c t e d M e t a l C a r b o n y l S t r e t c h i n g F r e q u e n c i e s 3 Compound v^Ccm"1) Refere n c e ( n 5 - C 5 H 5 ) M o ( C 0 ) 2 ( n 3 - C 3 H 5 ) 1970,1963, 1903,1889 27 [ H B ( N 2 C 3 H 3 ) 3 ] M o ( C 0 ) 2 ( n 3 - C 3 H 5 ) 1959,1874 62 [MeGa(N 2C 3H 3) 3]Mo (CO) 2 (n 3-C 3H,_ ) 1948,1860 T h i s work. [ M e G a ( N 2 C 3 H 3 ) 3 ] M o ( C O ) 2 ( n 3 - C 4 H y ) 1949,1863 T h i s work. [MeGa(N 2C 5H y) 2(OH) ]Mo (CO) . (n 3-C H^) 1940,1850 T h i s work. [ M e G a ( N 2 C 5 H 7 ) 2 ( O H ) ] W ( C O ) 2 ( n 3 - C ^ ) 1930,1837 T h i s work. [ M e G a ( N 2 C 5 H 7 ) 2 (OH) ]W(CO) 2 (n 3-C 4H 7); 1930,1837 T h i s work. cycloh e x a n e s o l u t i o n s - 106 -Table X I I Mass S p e c t r a l Data f o r [MeGa (dmpz ) (0H)-]Mo (CO) „ ( n 3 - C . H ) ra/e I n t e n s i t y Assignment •504 6 .1 502 14.1 501 9.1 500 16.2 499 12.7 [MeGa(dmpz)„(OH)]Mo(CO) ?(C,H 7) 49 8 13.5 i ^ l 497 11.7 496 9.4 494 7.6 476 7.1 474 14.8 473 9.4 472 ' 18.9 471 15.5 [MeGa(dmpz) (OH)]Mo(CO)(C.H ) 470 14.6 1 4 ' 469 10.6 468 12.1 466 11.5 448 13.9 446 41.2 445 23.2 444 57.4 443 38.6 [MeGa(dmpz)„(OH)]Mo(C,H ) + 442 39.2 ' 4 * 441 30.9 440 39.9 438 24.7 392 7.0 390 17.1 389 19.4 388 23.0 387 19.2 [MeGa(dmpz) 9(0)]Mo 386 19.4 385 17.6 384 12.7 382 10.5 - 107 -Table X I I (cont'd) m/ e '. In tens i t y As s ignment 352 350 349 348 347 346 345 344 342 337 335 334 3 33 332 331 330 329 327 96 95 71 69 18 . 6 67 . 1 32 . 6 100 . 0 63.9 64 . 1 50.2 53 . 0 44. 2 7 . 9 20 . 0 12. 3 26 , 18 22, 15. 15 , 11.8 44.8 36 . 4 27 . 7 42.4 [MeGa(dmpz)(0)]Mo(C 4H y) + [Ga(.dmpz) (0) ]Mo ( C 4 H ? ) + [H(dmpz)] (dmpz) + G a + + Table XIII H N.M.R. Data for the " A l l y l " and N i t r o s y l Complexes of the [MeGa(dmpz)„] Ligand i n C,Dr Solvent* t J 6 6 M e — G a M e — G a M e -TPPM M= Mo R= Me A l l y l Compounds W Me Mo H Ni t r o s y l Compounds M= Mo W R= -4-H 4.41s(1) 4.54s(l) 4.46s(l) 4.57s(l) 4.43s(l) 4.53s(l) 4.38s(2) 4.56s(l) 4.43s(2) 4.61s(l) 3-Me, 5-Me 6.85s(3),8.19s(3) 7.64s(3),8.28s(3) 6.83s(3),8.24s(3) 7.63s(3),8.34s(3) 6.82s(3),8.18s(3) 7.58s(3),8.28s(3) 7.34s(5),8.08s(6) 7.59s(3) ,8.18s(3) 7.27s(6),8.11s(6) 7.52s(3),8.24s(3) H syn 6.66d a(l) 7.25dd b(l) 6.86d a(l) 7.36dd b(l) 6.31dd b(l) 7.00mC(l) H ant i 8.47s(l) 8.72s(l) 8.06s(l) 8.31s(l) 8.20djl(l) 8.70d (1) R 8.44s(3) 8.31s(3) 6.48tt e(l) OH 10.18s(1) 9.83s(l) 10.56s(l) Ga-Me 10.09s(3) 10.12s(3) 10.10s(3) 9.75s(3) 9.78s(3) *i(TMS) = 10 PPM xC 6H 6 =2.84 PPM) s=singlet d=doublet t=triplet Hz for major doublet Fine structure on doublet aT-4.5 Hz C j - 4.5 Hz for major doublet dd=doublet of doublets t t = t r i p l e t of t r i p l e t s bj=4.5 Hz, 2Hz ea=4.5 Hz and 8 Hz f j = 8 Hz - 109 -3-3. The [MeGa(mpz) 3]~ l i g a n d . The f i n a l p a r t of t h i s c h a p t e r d e t a i l s the syn-t h e s i s of the a n i o n i c t r i d e n t a t e c h e l a t i n g l i g a n d m e t h y l t r i s ( 3 - m e t h y l p y r a z o l y l ) g a l l a t e , [MeGa(mpz) 3] (mpz= (l^C^H,.) ) . A p r e l i m i n a r y i n v e s t i g a t i o n i n t o the c h e l a t i n g p r o p e r t i e s 2 + of t h i s l i g a n d w i t h t r a n s i t i o n m e t a l M (M=Co or N i ) i o n s and w i t h Mo or W c a r b o n y l compounds i s a l s o d e s c r i b e d . A p r e v i o u s r e p o r t (45) had d e s c r i b e d the s y n t h e s i s of the d i m e t h y l b i s ( 3 - m e t h y l p y r a z o l y l ) g a l l a t e l i g a n d , [Me 2Ga(mpz) ] . The r e a c t i o n of the sodium s a l t of t h i s l i g a n d w i t h CuBr^ i n THF s o l v e n t d i d not y i e l d the expected b i s copper ( I I ) complex, [ M e 2 G a ( m p z ) 2 ] 2 C u , but r a t h e r , a n o v e l b i n u c l e a r copper ( I I ) complex, [Me^Ga^(mpz)^CuO] 2 ( F i g u r e 14). T h i s s u r p r i s i n g b e h a v i o r was p o s t u l a t e d to be a d i r e c t r e s u l t of the a t t a c k of water on the i n i t i a l l y formed b i s c h e l a t e complex, [ M e 2 G a ( m p z ) 2 ] 2 C u , and s c r a m b l i n g of the u n s y m m e t r i c a l l y s u b s t i t u t e d m e t h y l p y r a z o l y l m o i e t i e s i n the l i g a n d which causes the methyl group on each m e t h y l -p y r a z o l y l moiety to be o r i e n t e d e i t h e r towards or away from the g a l l i u m atoms i n the b i n u c l e a r complex. In the same manner, the methyl group on each m e t h y l -p y r a z o l y l moiety i n the [MeGa(mpz) 3] l i g n d may be o r i e n t e d e i t h e r way, r e s u l t i n g i n f o u r p o s s i b l e isomers as shown i n F i g u r e 36. - 110 -F i g u r e 36 4 The l i g a n d was s y n t h e s i z e d and handled i n e x a c t l y the same manner as the [MeGa(pz)^] l i g a n d ; by r e a c t i n g t h r e e molar e q u i v a l e n t s of sodium ( 3 - m e t h y l p y r a z o l i d e ) w i t h m e t h y l d i c h l o r o g a l l a n e i n THF s o l v e n t to g i v e the d e s i r e d + _ p r o d u c t , Na [MeGa(mpz) 3] , which was not i s o l a t e d as a s o l i d but r e a c t e d i n measured a l i q u o t s i n the THF s o l v e n t . THF + — MeGaCl 2 + 3Na(mpz) •Na [MeGa(mpz) 3] + 2NaCl (43) The b i s l i g a n d t r a n s i t i o n m e t al complexes were prepar e d by the r e a c t i o n of s t o i c h i o m e t r i c q u a n t i t i e s of the l i g a n d and a m e t a l h a l i d e i n THF s o l v e n t , v i z : A - I l l -MX 2 + 2Na +[MeGa(mpz) 3]~ T H F * [MeGa(mpz) ] 2M + 2NaX (where M=Co,Ni; X = h a l l d e ) (44) Attempted r e c r y s t a l l i z a t i o n of the above two com-p l e x e s r e s u l t e d i n n o n - c r y s t a l l i n e s o l i d s which d i d not a n a l y s e as expected (see T a b l e XIV f o r r e s u l t s ) . T h i s i s p r o b a b l y a r e s u l t of the a b i l i t y of t h i s l i g a n d to scramble which c o u l d l e a d to s e v e r a l d i f f e r e n t p r o d u c t s . In a d d i t i o n to the 10 isomers p o s s i b l e f o r the [MeGa(mpz)^] 2M complex, l i g a n d s c r a m b l i n g c o u l d a l s o l e a d to compounds of d i f f e r e n t m o l e c u l a r w e i g h t s , such as the b i n u c l e a r copper ( I I ) complex [Me 3Ga 2(mpz)^CuO] a l r e a d y found w i t h the [Me^Ga(mpz) 2] l i g a n d . Thus, f u r t h e r s t u d i e s of these compounds w i l l r e -q u i r e a method of s e p a r a t i n g the isomers produced, h o p e f u l l y as pure c r y s t a l l i n e compounds. The N u j o l m u l l s p e c t r a of the [MeGa(mpz) ] 2M com-p l e x e s l i s t e d i n Table XIV were e s s e n t i a l l y i d e n t i c a l , i n -d i c a t i n g a p r o b a b l e isomorphism i n the two complexes. A s h a r p , medium i n t e n s i t y bond o c c u r r e d at 580 cm i n both s p e c t r a , which i s a s s i g n e d to the Ga-C s t r e t c h i n g v i b r a t i o n f o r the complexes. The mass s p e c t r a of both complexes l i s t e d i n Table XIV are v e r y s i m i l a r . The p r i n c i p a l f e a t u r e s of the mass spectrum of [MeGa(mpz)^] 2Co are r e c o r d e d , t o g e t h e r w i t h t h e i r t e n t a t i v e a s s i g n m e n t s , i n Table XVI. Depending on the - 112 -6 7 71 number of g a l l i u m atoms i n an i o n (Ga , 60.4%, Ga 39.6%, 5 9 Co 100.0%), a c h a r a c t e r i s t i c p a t t e r n of s i g n a l s was observed. The i n t e n s i t y r a t i o s w i t h i n each p a t t e r n agreed c l o s e l y w i t h those c a l c u l a t e d from the i s o t o p i c d i s t r i b u t i o n s of the g a l l i u m atoms. The v a r i o u s p a t t e r n s , t o g e t h e r w i t h t h e i r r e l a t i v e i n t e n s i t y r a t i o s , are g i v e n i n f i g u r e 28. The i n t e n s i t y p a t t e r n s of the i o n s i n the mass spectrum of the [ M e G a ( m p z ) 3 ] 2 N i complex a l s o agreed w e l l w i t h those c a l c u l a t e d from t h e o r y . Both s p e c t r a d i s p l a y t h e i r s t r o n g e s t s i g n a l s due to the p a r e n t i o n s , [MGa„(mpz),(Me)„] +, the p a r e n t i o n minus z o z two m e t h y l p y r a z o l y l m o i e t i e s , [MGa 2(mpz)^(Me) 2] +> and the par e n t i o n minus a l i g a n d , [MGa(mpz)^(Me)] +. Other weaker s i g n a l s which a r i s e from mixed m e t a l i o n s are [MGa„(mpz), z o ( M e ) ] + , [ M G a 2 ( m p z ) 5 ( M e ) 2 ] + , and [MGa 2(mpz) ( M e ) ] + . Two s t r o n g s i g n a l s o c c u r r e d i n both s p e c t r a which were a s s i g n e d to i o n s c o n t a i n i n g two g a l l i u m atoms, v i z : [ G a ^ ( m p z ) ^ ( M e ) ] + and [ G a 2 ( m p z ) 3 ( M e ) 2 ] + . A s l i g h t l y weaker s i g n a l a r i s i n g from the [ G a ( m p z ) ( M e ) ] + i o n a l s o o c c u r r e d i n both s p e c t r a . Ions of t h i s type have been noted p r e v i o u s l y i n the mass s p e c t r a of the [MeGa(pz)^] 2M complexes. The c a r b o n y l complexes were prepa r e d v i a a t h e r m a l method; the r e a c t i o n of the a p p r o p r i a t e Group VIb h e x a c a r -b o n y l M ( C 0 ) 6 w i t h the l i g a n d i n THF s o l v e n t a t 60°C to g i v e the Na +[MeGa(mpz)^M(CO) 3] s a l t as an i n t e r m e d i a t e , which was r e a c t e d i n s i t u w i t h an excess q u a n t i t y of the a p p r o p r i a t e - 113 -a l l y l i c h a l i d e or n i t r o s y l a t i n g agent to g i v e the d e s i r e d p r o d u c t s : M(CO) 6 + H a + [ M e G a ( m p z ) 3 l " T H F > Na +[MeGa(mpz) M ( C 0 ) 3 ] ' + 3C0 (45) (where M=Mo or W) Na [MeGa(mpz),M(CO)„] + CH„ = CRCH„X > J J Z JL fa [MeGa(mpz) 3]M(CO ) 2 ( n 3-C 3H 4R) + CO + NaX (46) (whereR=H, X=Br; or R=Me , X=C1) •f" T H V Na [MeGa(mpz),M(CO ) J + C^H^ONO ' ^ I . J . ^ V V - ' / ^ J 1 VJ ^ 11 ^ -j^  V IN V ^ ~~ [MeGa (mpz) 3 ]M(C0) 2N0 + CO + N a + ( C ^ ^ O ) ~ (47) While the [MeGa(mpz) 3]W(CO) 2N0 d e r i v a t i v e was 3 s u c c e s s f u l l y p r e p a r e d , attempts t o pre p a r e the "n - a l l y l " complexes of t u n g s t e n i n good y i e l d f a i l e d u s i n g t h i s r o u t e , as the main product r e c o v e r e d was found to be u n r e a c t e d 3 W(CO)g. The "n - a l l y l " d e r i v a t i v e s c o u l d p r o b a b l y be p r e -pared by employing (CH^CN) 3W(CO) 3 as a s t a r t i n g m a t e r i a l , however, time d i d not a l l o w t h i s p o s s i b l i t y to be i n v e s t i -gated. 3 While the "n - a l l y l " d e r i v a t i v e s of Mo a n a l y z e d p o o r l y , the data f o r both n i t r o s y l d e r i v a t i v e s were q u i t e a c c e p t a b l e . These r e s u l t s c o u l d be a t t r i b u t a b l e to g r e a t e r - 114 -s t e r i c crowding around the c e n t r a l molybdenum atom i n the 3 " n - a l l y l " d e r i v a t i v e s r e s u l t i n g i n unexpected p r o d u c t s , such as the h y d r o x y - b r i d g e d s p e c i e s found w i t h the [MeGa (dmpz)^] l i g a n d (see F i g u r e 35). A l t h o u g h t h e r e are s i x isomers p o s s i b l e f o r each n i t r o s y l d e r i v a t i v e (see F i g u r e 3 7 ) , they would a l l g i v e the same a n a l y s i s . The i n f r a r e d s p e c t r a l d a t a f o r a l l the n i t r o s y l complexes i n N u j o l are summarized i n Table XV f o r c o m p a r a t i v e purposes . I t i s noteworthy t h a t the s t r e t c h i n g v i b r a t i o n s f o r the [MeGa (mp z) ^  ] M (CO) 2N0 complexes are 5-10 cm lower than those of the c o r r e s p o n d i n g [MeGa(pz)^]M(C0) 2N0 complexes, s u g g e s t i n g a more e l e c t r o n r i c h t r a n s i t i o n m e t a l c e n t r e w i t h the i n t r o d u c t i o n of an e l e c t r o n - d o n a t i n g methyl group on each p y r a z o l y l moiety i n the l i g a n d . T h i s would i n c r e a s e back-bonding from the metal atom dir o r b i t a l s to the TT* a n t i b o n d i n g o r b i t a l of the C-0 bond, d e c r e a s i n g the v s t r e t c h i n g Li U f r e q u e n c y . With the i n t r o d u c t i o n of a second e l e c t r o n - d o n a t i n g methyl group on each p y r a z o l y l moiety as i n [MeGa(dmpz)^]M (C0) 2N0, t h i s s y n e r g i c e f f e c t would be expected to decrease the s t r e t c h i n g f r e q u e n c i e s even f u r t h e r . In f a c t , the VQQ s t r e t c h i n g f r e q u e n c i e s remain about the same as the [MeGa(mpz)^]Mo(CO) 2N0 complexes. T h i s may be a t t r i b u t a b l e to g r e a t e r s t e r i c crowding around the c e n t r a l m e t a l atom caused by the methyl groups i n the 3 - p o s i t i o n on p y r a z o l y l . - 115 -T h i s would tend to l e n g t h e n the m e t a l - p y r a z o l y l n i t r o g e n bond d i s t a n c e and c o n s e q u e n t l y o f f s e t the i n c r e a s e i n o d o n a t i n g s t r e n g t h caused by the a d d i t i o n a l m e t h y l group on p y r a z o l y l . Thus the expected a d d i t i o n a l b u i l d up of e l e c t r o n d e n s i t y on Mo would not occur and i n c r e a s e d d i r - i r * back bonding to the CO l i g a n d s i s not r e f l e c t e d to the CO v a l u e s . Mass s p e c t r a l a n a l y s i s of the product from the 3 attempted s y n t h e s i s of [MeGa(mp z ) 3 ] M o ( C O ) ^ ( n -C^H^R) (R=H,Me) gave w e l l d e f i n e d n i n e - l i n e p a t t e r n s of expected i n t e n s i t y r a t i o c a l c u l a t e d f o r i o n s c o n t a i n i n g both a Mo and a Ga atom, as shown i n F i g u r e 30. The p a r e n t i o n s i g n a l s were not ob s e r v e d , as the h i g h e s t mass peaks corresponded t o the hydroxy d e r i v a t i v e [ M e G a ( m p z ) 2 ( O H ) ] M o ( C O ) 2 ( C 3 H 4 R ) + . A s i g n a l of equal i n -t e n s i t y appeared at [MeGa(mpz) 2 (OH) ]Mo (CO) (C^H^R)"1", c o r r e -sponding to the l o s s of a c a r b o n y l . These two s i g n a l s were about h a l f as i n t e n s e as the f o u r s t r o n g e s t s i g n a l s common i n both s p e c t r a , which were a s s i g n e d to the i o n s [MeGa(mpz) 2 (OH)]Mo(C 3H 4R) + , [MeGa(mpz) 2 (0) ]Mo +, [MeGa (mp z ) (0 ) ] Mo (C ^ R ) + , and Ga +. Other s i g n a l s common i n both s p e c t r a were a s s i g n e d to the [ H ( m p z ) ] + i o n and a weaker s i g n a l c o r r e s p o n d i n g to the [MeGa(mpz)] + Ion. I t i s a l s o noteworthy t h a t the s t r o n g e s t 3 s i g n a l i n the n d e r i v a t i v e i s due to the l o s s of two c a r b o n y l s and a m e t h y l p y r a z o l e m o l e c u l e , [MeGa(mpz)(0)]Mo (C^H-j) + . U s u a l l y the s t r o n g e s t s i g n a l i s due to the l o s s of two c a r b o n y l s o n l y from the h i g h e s t mass peak, as was found 3 w i t h the n -C3H,- d e r i v a t i v e . - 116 -The mass spectrum of the n i t r o s y l d e r i v a t i v e , [MeGa(mpz)3]Mo(CO) 2N0, showed i t s s t r o n g e s t peak at parent minus two c a r b o n y l s , [MeGa(mpz) 3]Mo(N0) +, and another s t r o n g peak due to the [MeGa(mpz) 3]Mo i o n . The peaks a s s i g n e d to [MeGa(mpz)^]Mo(NO) , [H(mpz)] and Ga were of medium i n -t e n s i t y , w h i l e those of the paren t i o n [MeGa(mpz) 3]Mo(C0)^ ( N 0 ) + , and the [MeGa(mpz) 3]Mo(CO)(N0) +and [MeGa(mpz)] + i o n s were of much weaker i n t e n s i t y . The mass spectrum of the t u n g s t e n n i t r o s y l d e r i v a -t i v e , [MeGa(mpz) 3]W(CO)2(NO), gave w e l l d e f i n e d s i x - l i n e p a t t e r n s of the expected i n t e n s i t y r a t i o f o r a l l i o n s con-t a i n i n g b o t h a W and a Ga atom, as shown i n F i g u r e 30. The most i n t e n s e peak corresponded to the p a r e n t i o n s t r i p p e d of two c a r b o n y l groups and a m e t h y l p y r a z o l y l m o i e t y , [MeGatmpz^] W(N0) +. Other s t r o n g s i g n a l s were due to the paren t i o n , [MeGa(mpz) 3]W(C0) 2(N0) + , and [MeGa(mpz) 3]W(C0) (NO) + , [MeGa (mpz) 3]W(N0) +, [Ga(mpz) 3]W(N0) + and G a + i o n s . Peaks of l e s s e r i n t e n s i t y were a s s i g n e d to [MeGa(mpz) ]W +, [MeGa(mpz)] +, and [H(mpz)]" 1 i o n s . Mass s p e c t r a l a n a l y s i s of the pr o d u c t from the 3 attempted [MeGa (mpz ) 3 ] W (CO ) 2 (n -C-jHj.) s y n t h e s i s i n d i c a t e d t h a t i t c o n t a i n e d m o s t l y W(CO)^.. When the compound was heated to 220°C, s t r o n g peaks due to the p a r e n t i o n [MeGa(mpz) 3]W ( C 0 ) 2 ( C 3 H 5 ) + , and [ M e G a ( m p z ) 3 ] W ( C O ) ( C H ) + , [MeGa(mpz) 3]W ( C 3 H 5 ) + , [MeGa (mpz) 3 ]W + and [MeGa (mp z ) 2 ] W ( C ^ ) + i o n s were a l s o p r e s e n t , a l o n g w i t h a few u n i d e n t i f i e d s i g n a l s at m/e - 117 -r a t i o h i g h e r than t h a t of the p a r e n t i o n . T h i s showed t h a t some product had i n f a c t formed. Mass s p e c t r a l a n a l y s i s of the product from the 3 attempted [MeGa(mpz) 3]W(CO) 2(h -C^H^) s y n t h e s i s , on the o t h e r hand, showed o n l y peaks which were due to i o n s w i t h one or two g a l l i u m atoms i n them, even though the compound was heated to over 350°C. The s i g n a l s were a s s i g n e d to [ M e 3 G a 2 ( m p z ) 2 ] + , [ M e 3 G a 2 ( m p z ) ] + , [MeGa(mpz)] +, [ M e 2 G a ] + and + + Ga i o n s . In a d d i t i o n , a peak due to the [H(mpz)] i o n was a l s o p r e s e n t . 1 3 The H n.m.r. data f o r the "n - a l l y l " and n i t r o s y l complexes of Mo and W are l i s t e d i n Table X V I I . The 270 MHz n.m.r. spectrum of the [MeGa(mpz) 3] W(C0) 2N0 complex i s shown i n F i g u r e 38, a l o n g w i t h the 0-5T and the 5-10T r e g i o n s expanded i n F i g u r e s 38a and 38b r e s p e c t i v e l y . As w i t h the c a r b o n y l complexes of the [MeGa(pz)^] l i g a n d , the m e t h y l p y r a z o l y l p r o t o n s i g n a l s 4-H, 3-H and/or 5-H and the p y r a z o l y l methyl p r o t o n s i g n a l s are a l l w e l l - r e s o l v e d i n the s p e c t r a . T h i s means t h a t r o t a t i o n of the l i g a n d about the Ga-M (where M=Mo or W) a x i s i s r e s t r i c t e d at l e a s t at room temperature. T h i s , coupled w i t h the f a c t t h a t t h e r e are f o u r p o s s i b l e o r i e n t a t i o n s of the m e t h y l p y r a -z o l y l m o i e t i e s i n the l i g a n d and the f a c t t h a t the m e t h y l -p y r a z o l y l moiety o p p o s i t e the n i t r o s y l i s always going to be u n i que, l e d to the s i x p o s s i b l e isomers f o r the [MeGa(mpz) 3J M(C0) 2N0 complexes as shown i n F i g u r e 37. The schematic "'"H - 118 -n.m.r. of each Isomer i s a l s o shown. The "*"H n.m.r. spectrum of the W n i t r o s y l d e r i v a t i v e ( F i g u r e 38) shows t h a t t h e r e are at l e a s t two of the p o s s i b l e s i x isomers p r e s e n t i n the CDCl^ s o l u t i o n of the compound. However, i t i s d i f f i c u l t t o t e l l w h ich of the p o s s i b l e i s o -mers i s p r e s e n t i n the "*"H n.m.r. sample, even a f t e r expanding the 0-5T and 5-10T r e g i o n s of the spectrum ( F i g u r e s 38a and 38b r e s p e c t i v e l y ) . An attempt t o f i n d out e x a c t l y which of these p o s s i b l e isomers i s p r e s e n t i n CDCl^ s o l u t i o n would i n v o l v e a s e p a r a t i o n t e c h n i q u e and then a measurement of the '''H n.m.r. of each isomer p r e s e n t . S e p a r a t i o n of the isomers i n compounds of t h i s type c o n t a i n i n g g a l l i u m by column chromatography has been attempted but so f a r has met w i t h l i t t l e s u c c e s s . T h i s p o s s i b i l i t y w i l l have to be i n v e s t i g a t e d more e x t e n s i v e l y . P r e v i o u s l y , d i f f e r e n t isomers of these compounds have s e p a r a t e d from each o t h e r d u r i n g the c r y s t a l -l i z a t i o n process.. However, t h i s method has proven to be f o r t u i t o u s . T h i s i s demonstrated w e l l by these compounds where the p r o d u c t s were s e m i c r y s t a l l i n e powders c o n t a i n i n g more than one isomer. 1 3 3 The H n.m.r. s p e c t r a of the n - a l l y l and n -2-m e t h a l l y l d e r i v a t i v e s p r o v i d e even l e s s c o n c l u s i v e r e s u l t s . From the data i n Table XVII i t appears t h a t t h e r e i s o n l y 3 one isomer of the [MeGa (mpz ) 3 ]Mo (CO) 2 (n -C^^R) (where R=H or Me) complex p r e s e n t i n benzene s o l u t i o n . The 3 [MeGa(mpz)2(OH)]Mo(CO)2(n -C^H^R) d e r i v a t i v e , whose presence - 119 -F i g u r e 37 Schematic "*"H n.m.r. S p e c t r a of [MeGa(mpz),]M(CO)„N0 Isomers - 120 -F i g u r e 37 (cont'd) C ° M e — G a , M e Me H/ 1 .JiL 2: 1 3 - M e 5 -Me G a - M e 6 : 3 - 121 -F i g u r e 37 (cont'd) Me -s—~ H-H5' J L MH/ 2:1 5 - M e 3'- Me 6 : 3 F i g u r e 38 270 MHz F.T. 1H N.M.R. Spectrum of [MeGa(mpz) 3]W(CO) 2N0 i n C,.D~ . 7*0 I >"H> | 0 CPS to F i g u r e 38a 270 MHz F.T. 1H N.M.R. Spectrum of [MeGa(mpz) 3]W(GO) 2N0 i n C,D, 6 6 Expansion 0-5T > - « » i o cn F i g u r e 38b 270 MHz F.T. H N.M.R. Spectrum of [MeGa(mpz) ]W(CO) 2N0 Expansion 5-10T . i n C,D, 6 6 - 12 5 -was found i n the mass spectrum of the same sample, was not observed i n the "'"H n.m.r. In a d d i t i o n , the 3-H and/or 5-H p r o t o n s i g a n l s of the m e t h y l p y r a z o l y l moiety are not observed i n e i t h e r n.m.r. spectrum, a l t h o u g h they c o u l d be observed by the ' c g ^ g ' s i g n a l s i n c e they both occur i n the same a r e a . However, the 4-H p r o t o n s i g n a l s i n both [MeGa(mpz)^]Mo(CO)^ 3 (n -C^H^R) complexes are observed and, as w i t h the 3 [MeGa (pz ) 3 ]M (CO) 2 (n -C^^R) (where M=Mo or W) an a l o g u e s , the 3 4-Hproton s i g n a l s i n the n - a l l y l d e r i v a t i v e are b e t t e r 3 r e s o l v e d than i n the n - 2 - m e t h a l l y l d e r i v a t i v e . - 126 -Table XIV A n a l y t i c a l Data f o r Complexes I n c o r p o r a t i n g the [MeGa(mpz)„ ] M Compounds [MeGa ('mp'sL) ] 2 M Compounds T r a n s i t i o n A n a l y s i s M C o l o r m e t a l Found C a l c u l a t e d p r e c u r s o r C H N C H N Co brown C o C l 2 40.86 5.00 21.31 43.67 5.08 23.51 N i l i l a c N i B r 2 40.66 4.71 20.73 43.69 5.08 23.51 Ca r b o n y l Compounds [MeGa(mpz)3]X A n a l y s i s X C o l o r Found C a l c u l a t e d C H N C H N Mo(CO) 2 ( n 3-C 3H 5) y e l l o w 39.69 4.47 14.96 41.49 4.45 16.13 M o ( C O ) 2 ( l 3 - C 4 H 7 ) y e l l o w 40.70 5.79 11.88 42.65 4.71 15.71 Mo(CO) 0NO brown- 3 5 3 3 3. 5 6 1 9 > 2 2 35.41 3.62 18 . 89 2 orange W(C0) 2N0 orange 30.26 3.14 16.10 30.13 3.03 16.40 Table XV. I.R. Data f o r Group VIb N i t r o s y l Complexes i n N u j o l [X]Mo(CO) 2N0 [X]W(CO) 2N0 [X] CO NO Ga-C CO NO V Ga-C [MeGa(pz)3] 2018(s) 1998(m) 1995(s) 1896(m) 1635-1685(s) (multiplet) 590(w) 1995(s) 1985(s) 1980(m) 1870(m) 1615-1655(s) (multiplet) 595 (s) [MeGa(mpz)3] 2010(s) 1905(s) 1650(s) 595(w) 1990(s) 1880(s) 1635(s) 598(w) [ « . ( d ^ ) 3 ] 2010(s) 1905(s) 1655(3, 595(w) " ' " f t ^ Sletf ™M - 128 -Table XVI Mass S p e c t r a l Data f o r [MeGa(mpz) 3] 2Co m/e I n t e n s i t y Assignment 717 45.0 715 100.0 713 75.1 702 3.0 700 4.9 698 3.8 636 2.4 634 3 . 4 632 2.8 621 7.1 619 15 . 0 617 11. 7 555 9.6 553 21.2 551 15. 0 540 4.4 538 5 . 0 536 3 . 5 481 5 . 7 479 16 . 1 477 11.5 415 13.0 413 35 . 6 411 27 . 9 388 24.6 386 31. 9 167 7 . 1 165 10.4 82 39 . 3 71 7.3 69 11. 1 C o G a 2 ( m p z ) 6 ( M e ) 2 + C o G a 2 ( m p z ) 6 ( M e ) + C o G a 2 ( m p z ) t - ( M e ) 2 + C o G a 2 ( m p z ) 5 ( M e ) + C o G a 2 ( m p z ) 4 ( M e ) 2 + C o G a 2 ( m p z ) 4 ( M e ) + G a 2 ( m p z ) ^ ( M e ) 2 + G a 2 ( m p z ) 3 ( M e ) 2 + CoGa (mpz) 3(Me) + Ga(mp z) (Me) + H(mp z ) + Ga+ - 129 -Table X V I I I 1H N.M..R. Data f o r C a r b o n y l Complexes ; [MeGa(mpz) ]X (a) A l l y l Complexes i n C^D^ S o l v e n t Mo(co) 2 ( n 3-c 3H 5) Mo(CO) 2( n 3-C 4H 7) 3-H/ a a 5-H a a 4-H 4 . 1 6 s ( l ) , 4.328(2) 4.34s(3) H syn 6.85br (1) 6.90br (2) H - • ant 1 8.52d b 8 . 2 7 s ( l ) , 8 . 5 1 s ( l ) R 6.60br 8.60s(3) 3-Me/ 5-Me 8. 0 4 s ( 3 ) , 8.24s(6) 8 . 2 2 s ( 6 ) , 8.48s(3) Ga-Me 10.11s(3) 10.08s (3) a 3-H and/or 5-H obscured by a b s o r p t i o n . = 8 C,D s o l v e n t 6 6 Hz . (b) N i t r o s y l Complexes i n CDC1„ S o l v e n t Mo(CO) 2NO(100 MHz) W(C0) 2NO(270 MHz) 3-H 2 .'31da, 2.49u, 2.66u, 2 . 19d, 2.35d, 2 . 38d 5-H 2 .68d a (25) 2. 40d , 2.60d, 2 . 62d 2 . 66d (16) 4-H 3 .95d a, 4.03s, 4.12d a 3. 91d , 3.92d, 4 . Old (25) 4. lOd (15) 3-Me/ 7 . 51s, 7.53s, 7.76s, 7 . 47s , 7.49s, 7 .74s 5-Me 7 .81s (71) 7 . 78s , 7.79s, 7 .81s Ga-Me 9 •57s, 9.65s (23) 9 . 53s , 9 . 61s (15) J=2Hz; x(TMS)=10.00 ppm, T ( 'CDC1 ')=2.84 ppm, R e l a t i v e I n -n s i t i e s of s e t s of s i g n a l s g i v e n i n p a r e n t h e s i s . s = s i n g l e t , d=doublet, u=unresolved d o u b l e t s . - 130 -B. SYNTHETIC DETAILS 3-4. S y n t h e s i s of Na +[MeGa(pz)^ ] and i t s P y r a z o l y l Sub-s t i t u t e d D e r i v a t i v e s . In a t y p i c a l p r e p a r a t i o n , MeGaC^ (5.50 grams, 35.3 mmoles) d i s s o l v e d i n THF was t r a n s f e r r e d i n t o a c o n i c a l f l a s k . Then t h r e e molar e q u i v a l e n t s of Na(pz) (9.55 grams, 106.0 mmoles) were washed i n t o the f l a s k w i t h the same s o l v e n t . The r e a c t i o n m i x t u r e was s t i r r e d f o r 72 hours and the w h i t e p r e c i p i t a t e of NaCl which formed ( e q u a t i o n 26) was f i l t e r e d o f f and washed w i t h THF. The f i l t r a t e and washings were com-b i n e d and made up to 500 ml i n a v o l u m e t r i c f l a s k w i t h THF. Measured a l i q u o t s of the r e s u l t i n g s o l u t i o n were employed i n subsequent r e a c t i o n s . Assuming a 100% y i e l d , 10.8 grams (35.3 mmoles) of l i g a n d was produced. In the same manner, MeGaC^ (4.51 grams, 29.00 mmoles) was r e a c t e d w i t h t h r e e molar e q u i v a l e n t s of Na(dmpz) (10.25 grams, 86.78 mmoles) to produce a l i g a n d s o l u t i o n c o n t a i n i n g Na +[MeGa(dmpz)^] (11.36 grams, 28.93 mmoles) i n 500 ml of THF ( e q u a t i o n 34). S i m i l a r l y , MeGaCl^ (5.50 grams, 35.3 mmoles) was r e a c t e d w i t h t h r e e molar e q u i v a l e n t s of Na(mpz) (11.0 grams, 106.0 mmoles) to produce a l i g a n d s o l u t i o n c o n t a i n i n g Na+[MeG'a (mpz) 3 ]~ (12.4 grams, 35.3 mmoles) i n 500 ml of THF ( e q u a t i o n 43). - 131 -3.5. S y n t h e s i s of [MeGa(pz) ] 2M and R e l a t e d Complexes, (a) [ M e G a ( p z ) 3 ] 2 M (M=Mn, Fe, Cu, Zn) Complexes The [MeGa(pz)^] 2M (M=Co,Ni) complexes were p r e -v i o u s l y s y n t h e s i z e d by Mr. D. S i n g b e i l ( 64). The procedure was s i m i l a r f o r each experiment and may be I l l u s t r a t e d by d e s c r i b i n g the p r e p a r a t i o n of the [MeGa(pz)^] 2Mn complex. One 50 ml a l i q u o t of l i g a n d s o l u t i o n c o n t a i n i n g Na +[MeGa(pz) ] (1.09 grams, 3.53 mmoles) was p i p e t t e d i n t o a c o n i c a l f l a s k . Then anhydrous M n C l 2 (0.223 grams, 1.77 mmoles)' was washed i n t o the f l a s k w i t h THF. The r e s u l t i n g r e a c t i o n m i x t u r e was s t i r r e d f o r s e v e r a l hours r e s u l t i n g i n an amber-c o l o r e d s o l u t i o n and a w h i t e p r e c i p i t a t e ( e q u a t i o n 27, M=Mn, X=C1). The p r e c i p i t a t e was a l l o w e d to s e t t l e and the c l e a r a mber-colored s o l u t i o n was i s o l a t e d . The s o l v e n t THF was removed under vacuum from the. i s o l a t e d s o l u t i o n l e a v i n g a brown s o l i d , which was s o l u b l e i n benzene. R e c r y s t a l l i z a t i o n by slow e v a p o r a t i o n of the benzene gave p i n k , t r a n s p a r e n t c r y s t a l s of [MeGa(pz)^] 2Mn and a s t i c k y brown g l u e . The c r y s t a l s were washed w i t h heptane and d r i e d . S i m i l a r l y , r e a c t i o n of F e C l 2 * 1 . 5 THF (0.202 grams, 0.882 mmoles) w i t h one 25 ml a l i q u o t of l i g a n d s o l u t i o n c o n t a i n i n g Na +[MeGa(pz) ] (0.55 grams, 1.77 mmoles) i n THF s o l v e n t gave a brown s o l u t i o n and a w h i t e p r e c i p i t a t e . S o l v e n t THF removal from the i s o l a t e d s o l u t i o n gave a brown s o l i d . - 132 -R e c r y s t a l l i z a t i o n from benzene gave a s m a l l amount of orange, s e m i c r y s t a l l i n e [ M e G a ( p z ) 3 ] 2 F e a n c^ a l a r g e r amount of brown r e s i d u e . R e a c t i o n of anhydrous CuBr^ (0.398 grams, 1.77 mmoles) w i t h one 50 ml a l i q u o t of l i g a n d s o l u t i o n c o n t a i n i n g Na +[MeGa;(pz) 3]~ (1.09 grams, 3.53 mmoles) i n THF s o l v e n t gave a deep l i m e - g r e e n s o l u t i o n and a w h i t e p r e c i p i t a t e . S o l v e n t THF removal from the i s o l a t e d s o l u t i o n gave a b l u e -green s o l i d . R e c r y s t a l l i z a t i o n from benzene-heptane gave b l u e c r y s t a l s of [MeGa(pz)• ]^Cu and a green r e s i d u e . R e a c t i o n of anhydrous Z n C l 2 (0.241 grams, 1.77 mmoles) and one 50 ml a l i q u o t of l i g a n d s o l u t i o n c o n t a i n i n g N a + [ M e G a ( p z ) 3 ] ~ (1.09 grams, 3.53 mmoles) i n THF s o l v e n t gave a c o l o r l e s s s o l u t i o n and a w h i t e p r e c i p i t a t e . S o l v e n t removal from the i s o l a t e d s o l u t i o n l e f t a w h i t e s o l i d . Re-c r y s t a l l i z a t i o n from benzene gave l a r g e , c o l o r l e s s c r y s t a l s o f . [ M e G a ( p z ) 3 ] 2 Z n -(b) [MeGa(dmpz) 3] 2M (M=Co,Ni) Complexes R e a c t i o n of anhydrous C o C l 2 (0.147 grams, 1.13 mmoles) w i t h one 50 ml a l i q u o t of l i g a n d s o l u t i o n c o n t a i n i n g Na +[MeGa(dmpz) 3]~ (0.888 grams, 2.26 mmoles) i n THF s o l v e n t gave, a f t e r 10 days, an i n d i g o s o l u t i o n , a b l u e p r e c i p i t a t e and a w h i t e p r e c i p i t a t e ( e q u a t i o n 35, M=Co, X=C1). S o l v e n t THF removal from the i s o l a t e d s o l u t i o n gave an i n d i g o s o l i d . Attempted r e c r y s t a l l i z a t i o n from benzene gave an i n t r a c t a b l e - 133 -m i x t u r e of b l u e and p u r p l e s o l i d s . S i m i l a r l y , r e a c t i o n of anhydrous N i B r 2 (0.247 grams, 1.13 mmoles) w i t h one 50 ml a l i q u o t of l i g a n d s o l u t i o n con-t a i n i n g Na +[MeGa(dmpz) ]~ (0.888 grams, 2.26 mmoles) i n THF s o l v e n t gave a b u r g a n d y - c o l o r e d s o l u t i o n , a yellow-brown p r e c i p i t a t e and a w h i t e p r e c i p i t a t e . S o l v e n t THF removal from the i s o l a t e d s o l u t i o n gave an i n d i g o s o l i d . Attempted r e c r y s t a l l i z a t i o n from benzene gave an i n t r a c t a b l e m i x t u r e of green, p u r p l e and b l u e s o l i d s . (c) [MeGa(mpz) 3] 2M (M=Co,Ni) Complexes R e a c t i o n of anhydrous C o C l 2 (0.230 grams, 1.77 mmoles) w i t h one 50 ml a l i q u o t of l i g a n d s o l u t i o n c o n t a i n i n g Na +[MeGa(mpz) ] (1.24 grams, 3.53 mmoles) i n THF s o l v e n t gave, a f t e r s e v e r a l days, a p u r p l e s o l u t i o n , a b l u e p r e c i p i t a t e and a w h i t e p r e c i p i t a t e . S o l v e n t THF removal from the i s o l a t e d s o l u t i o n gave a p u r p l e s o l i d , which p a r t i a l l y d i s s o l v e d i n benzene to g i v e a p u r p l e s o l u t i o n and a w h i t e p r e c i p i t a t e ( e q u a t i o n 44, M-Co, X=C1). The s o l u t i o n was i s o l a t e d from the p r e c i p i t a t e . The w h i t e p r e c i p i t a t e was e x t r a c t e d w i t h d i c h l o r o m e t h a n e r e s u l t i n g i n a brown s o l u t i o n . Attempted r e c r y s t a l l i z a t i o n from d i c h l o r o m e t h a n e gave a brown, semi-c r y s t a l l i n e s o l i d which was found to be impure [MeGa(mpz)^] 2Co. Slow e v a p o r a t i o n of the p u r p l e benzene s o l u t i o n r e s u l t e d i n c o n v e r s i o n of the p u r p l e s o l i d to a brown s o l i d c o n t a i n i n g [MeGa(mpz)^] 2Co. - 134 -R e a c t i o n of anhydrous N i B r 2 (0.385 grams, 1.76 mmoles) w i t h one 50 ml a l i q u o t of l i g a n d s o l u t i o n c o n t a i n i n g Na +[MeGa(mpz)^] (1.24 grams, 3.53 mmoles) i n THF s o l v e n t gave, a f t e r s e v e r a l 'days, a p a l e l i l a c s o l u t i o n , a y e l l o w p r e c i p i t a t e , and a w h i t e p r e c i p i t a t e . S o l v e n t THF removal from the i s o l a t e d s o l u t i o n gave a p a l e l i l a c s o l i d . Attempted r e c r y s t a l l i z a t i o n from d i c h l o r o m e t h a n e gave an impure, p a l e l i l a c s o l i d c o n t a i n i n g [MeGa(mpz)^] 2Ni. 3-6. R e a c t i o n of T i C l ^ w i t h N a + [ M e G a ( p z ) 3 ] ~ R e a c t i o n of T i C l ^ (0.6 grams, 3.2 mmoles) w i t h one 50 ml a l i q u o t of l i g a n d s o l u t i o n c o n t a i n i n g Na +[MeGa(pz)^] (0.889 grams, 2.88 mmoles) i n THF s o l v e n t gave a c h e r r y - r e d s o l u t i o n . The r e a c t i o n m i x t u r e was s t i r r e d f o r 72 hours r e s u l t i n g i n a y e l l o w - o r a n g e s o l u t i o n and a w h i t e p r e c i p i t a t e . S o l v e n t removal from the i s o l a t e d s o l u t i o n gave a y e l l o w -orange s o l i d . Attempted r e c r y s t a l l i z a t i o n from THF or benzene gave an i n t r a c t a b l e , c o l o r l e s s g l a s s . 3-7. R e a c t i o n of ( n^-C,-H,.)Fe(C0) 2I w i t h Na +[MeGa(pz) ]~ ( n 5 - C 5 H 5 ) F e ( C O ) 2 I (1.717 grams, 5.632 mmoles) and one 100 ml a l i q u o t of l i g a n d s o l u t i o n c o n t a i n i n g Na +[MeGa ( p z ) ^ ] (1.75 grams, 5.63 mmoles) i n THF were t r a n s f e r r e d i n t o a s i n g l e - n e c k e d f l a s k r e s u l t i n g i n a b l a c k s o l u t i o n . The r e a c t i o n m i x t u r e was g e n t l y r e f l u x e d f o r 15 hours g i v i n g a brown s o l u t i o n and a brown p r e c i p i t a t e . CO gas was e v o l v e d - 135 -d u r i n g t h i s p e r i o d - Slow e v a p o r a t i o n of the THF s o l v e n t from the i s o l a t e d s o l u t i o n gave a s m a l l amount of y e l l o w , diamond-shaped [ M e G a ( p z ) 3 ] 2 F e c r y s t a l s . 3 + 3-8. R e a c t i o n of (n - c 3 H 5 ) N i B r w i t h Na [MeGa(pz> 3] I n t o a c o n i c a l f l a s k was t r a n s f e r r e d an excess 3 amount of (n - C 3 H ^ ) N i B r and one 100 ml a l i q u o t of l i g a n d s o l u t i o n c o n t a i n i n g N a + [ M e G a ( p z ) 3 ] (1.78 grams, 5.76 mmoles), both d i s s o l v e d i n THF s o l v e n t . The r e a c t i o n m i x t u r e changed i n c o l o r from brown-red to s t r a w . The r e a c t i o n m i x t u r e was then s t i r r e d f o r 24 hours r e s u l t i n g i n an amber s o l u t i o n and a green p r e c i p i t a t e . S o l v e n t THF removal from the i s o l a t e d s o l u t i o n gave a brown s o l i d . R e c r y s t a l l i z a t i o n from benzene gave l i l a c - c o l o r e d c r y s t a l s of [ M e G a ( p z ) 3 ] 2 N i and a brown r e s i d u e . R e c r y s t a l l i z a t i o n of t h i s r e s i d u e from d i c h l o r o -methane gave the p r e v i o u s l y c h a r a c t e r i z e d [ M e G a ( p z ) 2 ] 2 N i complex (40,41) as orange c r y s t a l s . 3-9. R e a c t i o n of M o ? ( C H ^ C 0 9 ) A w i t h N a + [ M e G a ( p z ) Q ] " I n t o a c o n i c a l f l a s k was added a s l u r r y of M o 2(CH 3  C 0 2 ^ 4 (°- 753 grams, 1.76 mmoles) i n THF and one 50 ml a l i q u o t of l i g a n d s o l u t i o n c o n t a i n i n g Na +[MeGa(pz)„]~ (1.09 grams, Mo 2'.(CH 3C0 2) 4 + 2Na [MeGa(pz) 3] THF (48) - 136 -3.53 mmoles) i n THF. A f t e r s t i r r i n g f o r s e v e r a l m i n u t e s , the i n i t i a l l y orange r e a c t i o n m i x t u r e became a dark w i n e - r e d s o l u t i o n . Slow e v a p o r a t i o n of the THF s o l v e n t from t h i s s o l u t i o n gave a t a c k y p u r p l e s o l i d and numerous red-orange c r y s t a l s , which were found to be v e r y a i r - s e n s i t i v e , t u r n i n g brown q u i c k l y on a i r exposure. C h a r a c t e r i z a t i o n proved d i f f i c u l t , and a c r y s t a l s t r u c t u r e i s p r e s e n t l y i n p r o g r e s s . 3-10. S y n t h e s i s of [MeGa(pz> 3]Mn(CO) In t o a s i n g l e - n e c k e d f l a s k was added Mn(C0)^Br (0.774 grams, 2.81 mmoles) and one 50 ml a l i q u o t of l i g a n d s o l u t i o n c o n t a i n i n g N a + [ M e G a ( p z ) 3 ] (0.874 grams, 2.83 mmoles both d i s s o l v e d i n THF. Upon r e f l u x , CO gas was e v o l v e d . R e f l u x i n g was c o n t i n u e d f o r 15 hours r e s u l t i n g i n a y e l l o w s o l u t i o n and a w h i t e p r e c i p i t a t e ( e q u a t i o n 33). S o l v e n t THF removal from the i s o l a t e d s o l u t i o n gave a p a l e y e l l o w s o l i d . R e c r y s t a l l i z a t i o n from benzene-heptane gave p a l e y e l l o w , a i r -s e n s i t i v e c r y s t a l s of [MeGa(pz) 3]Mn(CO) . 3-11. S y n t h e s i s of [MeGa(dmpz) 3]Mn(CO) 3 Mn(C0) 5Br (1.243 grams, 4.523 mmoles) and one 100 ml a l i q u o t of l i g a n d s o l u t i o n c o n t a i n i n g Na +[MeGa(dmpz)^] (1.78 grams, 4.52 mmoles) i n THF s o l v e n t were r e f l u x e d f o r 72 hours r e s u l t i n g i n a lemon-yellow s o l u t i o n and a w h i t e p r e c i p i t a t e . CO gas was e v o l v e d d u r i n g t h i s p e r i o d ( e q u a t i o n 42). S o l v e n t THF removal from the i s o l a t e d s o l u t i o n gave a - 137 -p a l e y e l l o w s o l i d . R e c r y s t a l l i z a t i o n from benzene-heptane gave l a r g e , p a l e y e l l o w c r y s t a l s of [MeGa(dmpz) 3]Mn(CO) . These c r y s t a l s were s o l v e n t s e n s i t i v e , t u r n i n g brown i n c o l o r on p r o l o n g e d s t a n d i n g i n benzene. Vacuum d r y i n g of these c r y s t a l s gave a c h a l k y , w h i t e s o l i d . 3-12. Attempted s y n t h e s i s of [MeGa(dmpz) 3]CuCO In a procedure s i m i l a r to t h a t i n s e c t i o n ( 3 - 5 ) , CuCl (0.364 grams, 3.68 mmoles) was r e a c t e d w i t h one 50 ml a l i q u o t of l i g a n d s o l u t i o n c o n t a i n i n g Na +[MeGa(dmpz) ] i n THF. The r e a c t i o n m i x t u r e was s t i r r e d f o r s e v e r a l h o u r s , r e s u l t i n g i n a p a l e b l u e s o l u t i o n and a w h i t e p r e c i p i t a t e . The i s o l a t e d s o l u t i o n was then t r a n s f e r r e d to a thr e e - n e c k e d f l a s k , which was equipped w i t h a r e f l u x condenser and a gas i n l e t tube. CO gas was bubbled through the s o l u t i o n f o r two hou r s , r e s u l t i n g i n a dark b l u e s o l u t i o n ( e q u a t i o n 36). S o l v e n t THF removal from t h i s s o l u t i o n gave an i n t r a c t a b l e , b l u e s o l i d . 3-13. S y n t h e s i s of Na + [ M e G a ( p z ) 3 M ( C O ) 3 ] (M=Cr,Mo,W) Com-p l e x e s and t h e i r P y r a z o l y l S u b s t i t u t e d D e r i v a t i v e s (a) Na +[MeGa(pz) ,M(C0) , M M T T _ . _ . 3 3 (M=Mo,W,Cr) Complexes The procedure was s i m i l a r f o r each experiment and may be i l l u s t r a t e d by d e s c r i b i n g the p r e p a r a t i o n of the Mo d e r i v a t i v e . I n t o the side- a r m of the m u l t i p l e b r e a k - s e a l - 138- -apparatus shown i n F i g u r e 39 was t r a n s f e r r e d Mo(CO)g (1.196 grams, 4.532 mmoles). Then one 100 ml a l i q u o t of l i g a n d s o l u -t i o n c o n t a i n i n g Na +[MeGa(pz)^] (1.75 grams, 5.66 mmoles) i n THF was p i p e t t e d i n t o the 1 - l i t e r b u l b . The s i d e - a r m was capped and a tap adaptor was f i t t e d onto the main stem. The apparatus was then immersed i n l i q u i d n i t r o g e n and evacuated, f l a m e - s e a l e d at c o n s t r i c t i o n s A and B, and was a l l o w e d to s l o w l y warm to room temperature. The Mo(C0)g was washed i n t o the l i g a n d s o l u t i o n c a u s i n g t r a c e s of y e l l o w c o l o r a t i o n to i m m e d i a t e l y appear. The r e a c t i o n m i x t u r e was warmed at 60°C f o r s e v e r a l hours c a u s i n g the y e l l o w c o l o r a t i o n to i n c r e a s e i n i n t e n s i t y ( e q u a t i o n 28, M=Mo). The CO gas e v o l v e d was measured u s i n g the T o e p l e r pump (see F i g u r e 17, p a r t B ) ( c a l c u l a t e d 304.7 ml, found 285.2 m l ) . The r e a c t i o n was deemed as com p l e t e , and the r e s u l t i n g c l e a r , y e l l o w s o l u t i o n of Na +[MeGa(pz)^Mo(CO)^] was d i v i d e d i n t o two e q u a l a l i q u o t s (1.2 grams, 2.2 mmoles) and r e a c t e d as d e s c r i b e d i n s e c t i o n s ( 3 - 1 4 ( a ) ) and ( 3 - 1 5 ) . S i m i l a r l y , r e a c t i o n of W(C0) 6 (1.592 grams, 4.523 mmoles) and one 100 ml a l i q u o t of l i g a n d s o l u t i o n c o n t a i n i n g Na +[MeGa(pz) ] (1.75 grams, 5.66 mmoles) i n THF s o l v e n t gave, a f t e r t h r e e weeks at 60°C, o n l y a s m a l l amount of CO gas ( c a l c u l a t e d 304.3 ml, found 32.5 m l ) . The r e a c t i o n s o l v e n t was thus changed from THF to dioxane (b.p. 101°C) and the r e s u l t i n g r e a c t i o n m i x t u r e was r e f l u x e d f o r s e v e r a l days i n a s i n g l e - n e c k e d f l a s k . CO - 139 -M u l t i p l e F i g u r e 39 B r e a k - S e a l Apparatus - 140 -e v o l u t i o n was slow d u r i n g t h i s p e r i o d . The r e s u l t was a c l e a r y e l l o w s o l u t i o n of N a + [ M e G a ( p z ) ( C O ) 3 ] which was d i v i d e d i n t o t h r e e e q u a l a l i q u o t s and r e a c t e d as d e s c r i b e d i n s e c t i o n s (3-14(a)) and ( 3 - 1 6 ( a ) ) . R e a c t i o n of Cr(CO)^ (0.996 grams, 4.53 mmoles) w i t h one 100 ml a l i q u o t of l i g a n d s o l u t i o n c o n t a i n i n g Na +[MeGa (pz)-j] (1:75 grams, 5.66 mmoles) i n THF gave, a f t e r t h r e e weeks at 60°C, an o r a n g e - y e l l o w s o l u t i o n . S e v e r a l measure-ments of CO e v o l u t i o n taken d u r i n g t h i s p e r i o d r e v e a l e d t h a t the r e a c t i o n was p r o c e e d i n g s l o w l y ( c a l c u l a t e d 304.6 ml, found 92.6 m l ) . The s o l v e n t was changed from THF to dioxane and the r e s u l t i n g r e a c t i o n m i x t u r e was warmed at 80°C f o r an a d d i -t i o n a l two weeks. The CO gas e v o l v e d was then measured and added to the p r e v i o u s r e s u l t ( c a l c u l a t e d 304.6, found 176.4 m l ) . The r e s u l t i n g brown-orange r e a c t i o n m i x t u r e was r e f l u x e d i n dioxane f o r one week, g i v i n g a red-brown s o l u t i o n . The product was d i v i d e d i n t o t h r e e e q u a l a l i q u o t s and r e a c t e d as d e s c r i b e d i n s e c t i o n s (3-14 (a-) ) and ( 3 ^ 1 6 ( a ) ) . (b) N a +[MeGa(dmpz) 3M(C0) 3]~ (M=Mo,W,Cr) Complexes R e a c t i o n of Mo( C 0 ) 6 (1.35 grams, 4.297 mmoles) w i t h one 100 ml a l i q u o t of l i g a n d s o l u t i o n c o n t a i n i n g Na +[MeGa (dmpz) 3J (2.27 grams, 5.79 mmoles) i n THF gave, a f t e r f o u r days at 60°C, a yellow-brown s o l u t i o n . The CO gas e v o l v e d ( e q u a t i o n 37, M=Mo) was measured u s i n g the T o e p l e r pump ( c a l -c u l a t e d 289.0 ml, found 294.0 m l ) . The s o l u t i o n was d i v i d e d - 141 -i n t o t h r e e e q u a l a l i q u o t s (0.8 grams, 1.4 mmoles) and r e a c t e d as d e s c r i b e d i n s e c t i o n s ( 3 - 1 4 ( b ) ) and ( 3 - 1 6 ( b ) ) . I n t o a s i n g l e - n e c k e d f l a s k was t r a n s f e r r e d a s l u r r y of W(CO)^ (1.589 grams, 4.515 mmoles) i n d i o x a n e . Then one 100 ml a l i q u o t of l i g a n d s o l u t i o n c o n t a i n i n g Na +[MeGa(dmpz) 3] (1.77 grams, 4.52 mmoles) i n THF was p i p e t t e d i n t o the f l a s k . The r e a c t i o n m i x t u r e became s l i g h t l y green i n c o l o r . The r e a c t i o n m i x t u r e was r e f l u x e d f o r t h r e e weeks and a gas, presumed to be CO, was s l o w l y e v o l v e d . The r e s u l t i n g y e l l o w -green s o l u t i o n was d i v i d e d i n t o t h r e e e q u a l a l i q u o t s and r e a c t e d as d e s c r i b e d i n s e c t i o n s (3-14(b)) and ( 3 - 1 6 ( b ) ) . I n t o a s i n g l e - n e c k e d f l a s k was t r a n s f e r r e d a s l u r r y of C r ( C 0 ) g (0.993 grams, 4.51 mmoles) i n dio x a n e . Then one 100 ml a l i q u o t of l i g a n d s o l u t i o n c o n t a i n i n g Na +[MeGa(dmpz)^] (1.78 grams, 4.52 mmoles) i n THF was p i p e t t e d i n t o the f l a s k . The r e a c t i o n m i x t u r e became s l i g h t l y green i n c o l o r . The r e a c t i o n was then r e f l u x e d f o r two weeks and a gas, presumed to be CO, was s l o w l y e v o l v e d . The r e s u l t i n g brown-orange s o l u t i o n was d i v i d e d i n t o t h r e e e q u a l a l i q u o t s and r e a c t e d as d e s c r i b e d i n s e c t i o n s (3-14(b)) and ( 3 - 1 6 ( b ) ) . (c) Na +[MeGa(mpz) 3M(CO) 3]" (M=Mo, W) Complexes In a procedure i d e n t i c a l w i t h those d e s c r i b e d i n s e c t i o n 3-13(a), Mo(CO). (1.493 grams, 5.654 mmoles) was r e a c t e d w i t h one 100 ml a l i q u o t of l i g a n d s o l u t i o n c o n t a i n i n g N a +[MeGa(mpz) 3]~ (2.48 grams, 7.07 mmoles) i n THF. The bul b and i t s c o n t e n t s were warmed at 60°C f o r 24 ho u r s . The CO - 142 -ev o l v e d ( e q u a t i o n 45, M=Mo) was measured w i t h the T o e p l e r pump ( c a l c u l a t e d 380.2 ml, found 372.8 m l ) . The r e s u l t i n g lemon-yellow s o l u t i o n was d i v i d e d i n t o t h r e e e q u a l a l i q u o t s (0.97 grams, 1.8 mmoles) and r e a c t e d as d e s c r i b e d i n s e c t i o n s (3-14(c>) and ( 3 - 1 6 ( c ) ) . I n t o a s i n g l e - n e c k e d f l a s k was t r a n s f e r r e d a s l u r r y of W(C0)g (1.988 grams, 5.649 mmoles) i n dio x a n e . Then one 100 ml a l i q u o t of l i g a n d s o l u t i o n c o n t a i n i n g Na +[MeGa(mpz) 3] (2.48 grams, 7.07 mmoles) was p i p e t t e d i n t o the f l a s k and the r e s u l t i n g r e a c t i o n m i x t u r e was r e f l u x e d f o r t h r e e weeks. A gas, presumed to be CO, was s l o w l y e v o l v e d . The r e s u l t i n g lemon-yellow s o l u t i o n was d i v i d e d i n t o t h r e e e q u a l a l i q u o t s and r e a c t e d as d e s c r i b e d i n s e c t i o n s ( 3 - 1 4 ( c ) ) and ( 3 - 1 6 ( c ) ) . 3-14. S y n t h e s i s of [.MeGa (pz) ]M (CO) 2N0 (M=Cr,Mo,W) Complexes and T h e i r P y r a z o l y l S u b s t i t u t e d D e r i v a t i v e s (a) [MeGa(pz) 3]M(C0) 2N0 (M=Mo,W,Cr) Complexes The procedure i s i d e n t i c a l f o r each experiment and may be i l l u s t r a t e d by d e s c r i b i n g the p r e p a r a t i o n of the [MeGa (pz ) 3]Mo(C0) 2N0 complex ( e q u a t i o n 30, M=Mo). Into a th r e e - n e c k e d f l a s k was added one a l i q u o t of the s o l u t i o n from s e c t i o n ( 3 - 1 3 ( a ) ) c o n t a i n i n g N a + [ M e G a ( p z ) 3 Mo(C0) 3] (1.2 grams, 2.2 mmoles). The volume of the s o l u t i o n was made up to a p p r o x i m a t e l y 100 ml w i t h THF. The f l a s k was sto p p e r e d and removed from the glovebox. The f l a s k was then equipped w i t h a magnetic s t i r r i n g bar and a r e f l u x condenser, and .excess i s o a m y l n i t r i t e (2 ml) was added to the f l a s k . The - 143 -i n i t i a l l y y e l l o w r e a c t i o n m i x t u r e s l o w l y became b r i g h t orange and a w h i t e s o l i d p r e c i p i t a t e d . The r e a c t i o n m i x t u r e was s t i r r e d f o r an hour and a gas, presumed to be CO was e v o l v e d d u r i n g t h i s p e r i o d . S o l v e n t THF removal from the i s o l a t e d s o l u t i o n gave an orange s o l i d . R e c r y s t a l l i z a t i o n from benzene gave orange c r y s t a l s of [MeGa(pz) 3]Mo(CO) 2N0. S i m i l a r l y , w a r m i n g one a l i q u o t of the N a + [ M e G a ( p z ) 3 W(C0) 3] s o l u t i o n from s e c t i o n ( 3 - 1 3 ( a)) w i t h excess i s o a m y l -n i t r i t e caused a c o l o r change from y e l l o w t o orange and a wh i t e s o l i d p r e c i p i t a t e d . A gas, presumed to be CO, was e v o l v e d . S o l v e n t dioxane/THF removal from the i s o l a t e d s o l u -t i o n gave an orange s o l i d . R e c r y s t a l l i z a t i o n from acetone gave orange c r y s t a l s of [MeGa(pz) ]W(CO)^NO. One a l i q u o t of the N a + [ M e G a ( p z ) ^ C r ( C O ) 3 ] ~ s o l u t i o n from ( 3 -13(a)) was r e f l u x e d w i t h excess i s o a m y l n i t r i t e i n d i -oxane/THF s o l v e n t g i v i n g a red-orange s o l u t i o n and a w h i t e p r e c i p i t a t e . A gas, presumed to be CO, was e v o l v e d d u r i n g t h i s p e r i o d . S o l v e n t dioxane/THF removal from the s o l u t i o n gave a red-brown o i l . Attempted r e c r y s t a l l i z a t i o n from benzene gave a red-brown o i l . (b) [MeGa(dmpz) 3]M(CO) 2NO (M=Mo,W,Cr) Complexes. Warming one a l i q u o t of the s o l u t i o n from s e c t i o n ( 3 -13(b)) c o n t a i n i n g Na +[MeGa(dmpz) 3Mo(CO) ]~ (0.8 grams, 1.4 mmoles) w i t h excess i s o a m y l n i t r i t e i n THF s o l v e n t caused the r e a c t i o n m i x t u r e to change i n c o l o r from yellow-brown to orange, and a w h i t e s o l i d p r e c i p i t a t e . A f t e r two hours at 60°C, CO gas evolution ceased ( e q u a t i o n 38, M=Mo). S o l v e n t THF removal from the i s o l a t e d s o l u t i o n gave an orange s o l i d . - 144 -R e c r y s t a l l i z a t i o n from benzene gave orange c r y s t a l s of [MeGa(dmpz) 3]W(CO) 2NO. S i m i l a r l y , the N a + [ M e G a ( d m p z ) ( C O ) ^ ] s o l u t i o n from (3-13(b)) was r e f l u x e d w i t h excess i s o a m y l n i t r i t e f o r two hours i n dioxane/THF s o l v e n t . The r e a c t i o n m i x t u r e changed i n c o l o r from y e l l o w to orange and a w h i t e s o l i d . p r e c i p i a t e d . A gas, presumed to be CO, was e v o l v e d d u r i n g t h i s p e r i o d . S o l v e n t dioxane/THF removal from the i s o l a t e d s o l u t i o n gave an orange s o l i d . R e c r y s t a l l i z a t i o n from benzene-heptane gave l a r g e , orange c r y s t a l s of [MeGa(dmpz) 3]W(CO) 2N0. The Na +[MeGa(dmpz)^Cr(CO) 3] s o l u t i o n from s e c t i o n (3-13(b)) was r e f l u x e d w i t h excess i s o a m y l n i t r i t e f o r t h r e e hours i n dioxane/THF s o l v e n t . The r e a c t i o n m i x t u r e changed i n c o l o r from brown-orange to o l i v e - g r e e n , and a w h i t e s o l i d p r e c i p i t a t e d . S o l v e n t dioxane/THF removal from the i s o l a t e d s o l u t i o n gave an o l i v e s o l i d . Attempted r e c r y s t a l l i z a t i o n from benzene gave an i n t r a c t a b l e , green s o l i d . (c) [MeGa(mpz) 3]M(C0) 2N0 (M=Mo,W) Complexes R e a c t i o n of the s o l u t i o n from s e c t i o n (3-13(c)) con-t a i n i n g Na +[MeGa(mpz) 3Mo(CO) 3] (0.97 grams, 1.8 mmoles) w i t h excess i s o a m y l n i t r i t e f o r two hours i n THF s o l v e n t caused the r e a c t i o n m i x t u r e to change i n c o l o r from y e l l o w to orange and a w h i t e s o l i d p r e c i p i t a t e d . A gas, presumed to be CO, was e v o l v e d ( e q u a t i o n 47, M=Mo). S o l v e n t THF removal gave an orange o i l . T h i s o i l was washed w i t h benzene r e s u l t i n g i n an orange powder, [MeGa(mpz)^]Mo(CO) 9N0. - 145 -One a l i q u o t of the Na +[MeGa(mpz) 3W(CO) 3] s o l u t i o n from ( 3 - 1 3 ( c ) ) was r e f l u x e d w i t h excess i s o a m y l n i t r i t e f o r 45 minutes i n dioxane/THF s o l v e n t . The r e a c t i o n m i x t u r e changed i n c o l o r from lemon-yellow to orange and a w h i t e s o l i d p r e c i p i t a t e d . A gas, presumed to be CO, was e v o l v e d d u r i n g t h i s p e r i o d . S o l v e n t THF removal from the i s o l a t e d s o l u t i o n gave an orange s o l i d . R e c r y s t a l l i z a t i o n from THF gave orange, s e m i c r y s t a l l i n e n o dules of [MeGa(mpz) ]W(CO) 2N0, 3-15. R e a c t i o n of Na +[ MeGa (p z ) 3Mo (CO ) 3 ] w i t h [ C g H ^ ] + B F 4 ' + _ _i_ „ T T-T Na [MeGa(pz),Mo(C0)„] + [ C, H N ] BF — — J 3 o 5 I 4 A •[MeGa(pz) 3]Mo(C0) 2N=NC 6H 5 + CO + NaBF^ (49) U s i n g a procedure i d e n t i c a l to t h a t d e s c r i b e d i n s e c t i o n (3-13 ( a ) ) , p h e n y l d i a z o n i u m t e t r a f l u o r o b o r a t e (0.436 grams, 2.27 mmoles) was r e a c t e d w i t h one 100 ml a l i q u o t of the s o l u t i o n from s e c t i o n (3-13(a) ) c o n t a i n i n g N a + [ M e G a ( p z ) 3 Mo(C0) 3] (1.2 grams, 2.3 mmoles) i n THF s o l v e n t . The r e a c t i o n m i x t u r e was warmed f o r s e v e r a l hours r e s u l t i n g i n a yellow-brown r e a c t i o n m i x t u r e . The CO gas e v o l v e d ( e q u a t i o n 49) was measured w i t h the T o e p l e r pump ( c a l c u l a t e d 50.9 ml, found 44.4 m l ) . The s o l v e n t THF x^as removed from the r e a c t i o n m i x t u r e to g i v e a yellow-brown s o l i d , which was d i s s o l v e d i n benzene and f i l t e r e d . Attempted r e c r y s t a l l i z a t i o n from benzene gave an i n t r a c t a b l e , brown s o l i d . - 146 -3-16. S y n t h e s i s of the [ MeGa (p z ) ] M (CO) ( r,3-C 3H 4R) (M= Cr , Mo,W, and R=H,Me) Complexes and T h e i r P y r a z o l y l Sub-s t i t u t e d D e r i v a t i v e s . (a) [MeGa(pz) 3]M(CO) 2( n 3-C 3H 4R)(M=Mo,¥,Cr, and R=H,Me) Complexes. The [MeGa(pz) 3]Mo(CO) 2(n 3-C 3H 4R)(R=H,Me) complexes were p r e v i o u s l y s y n t h e s i z e d by Mr. D. S i n g b e i l ( 6 4 ) . The procedure was s i m i l a r f o r each experiment and may be i l l u s -t r a t e d by d e s c r i b i n g the p r e p a r a t i o n of the [MeGa(pz) 3]W(CO) 2 ( n 3-C 3H 5) complex ( e q u a t i o n 29, M=W, R=H). In t o a th r e e - n e c k e d f l a s k was added one a l i q u o t of + -the Na [MeGa(pz) 3W(CO) 3] s o l u t i o n from s e c t i o n (3-13 (a)) . The volume was made up to a p p r o x i m a t e l y 100 ml w i t h THF. The f l a s k was s t o p p e r e d and removed from the glovebox. The f l a s k was then equipped w i t h a magnetic s t i r r i n g bar and a r e f l u x conderis er ,.:: and excess 3-bromopropene (2 ml) was added to the f l a s k . The r e a c t i o n m i x t u r e was r e f l u x e d f o r 15 hours and a gas, presumed to be CO, was e v o l v e d . T h i s r e s u l t e d i n a brown s o l u t i o n and a w h i t e p r e c i p i t a t e . S o l v e n t dioxane/THF removal from the: i s o l a t e d s o l u t i o n gave a yellow-brown s o l i d . Attempted r e c r y s t a l l i z a t i o n from benzene gave an i n t r a c t a b l e , y e l l o w -brown s o l i d . S i m i l a r l y one a l i q u o t of the Na +[MeGa(pz) 3W(CO) 3] s o l u t i o n from s e c t i o n ( 3 - 1 3 (a)) was r e f l u x e d w i t h excess 3-chl o r o - 2 - m e t h y l p r o p e n e (2 ml) f o r 15 hours i n dioxane/THF s o l v e n t . A gas, presumed to be CO, was s l o w l y e v o l v e d . T h i s -• 147 -r e s u l t e d i n a y e l l o w - g r e e n s o l u t i o n and a w h i t e p r e c i p i t a t e . S o l v e n t dioxane/THF removal from the i s o l a t e d s o l u t i o n gave a y e l l o w - g r e e n s o l i d . R e c r y s t a l l i z a t i o n from benzene-heptane 3 gave l a r g e y e l l o w c r y s t a l s of [MeGaCpz^jWCCO^Cl -C^H^). One a l i q u o t of the Na +[MeGa(pz)^Cr(CO) ] s o l u t i o n from s e c t i o n ( 3 - 1 3 ( a ) ) was r e f l u x e d w i t h excess 3-bromopro-pene f o r one hour i n dioxane/THF s o l v e n t r e s u l t i n g i n a sa l m o n - c o l o r e d s o l u t i o n and a w h i t e p r e c i p i t a t e . S o l v e n t dioxane/THF removal from the s o l u t i o n gave a red o i l . Attempted r e c r y s t a l l i z a t i o n from benzene gave a red o i l . S i m i l a r l y , one a l i q u o t of the Na +[MeGa(pz) 3Cr(CO) ] s o l u t i o n from s e c t i o n ( 3 - 1 3 ( a)) was r e f l u x e d w i t h excess 3-ch l o r o - 2 - m e t h y l p r o p e n e i n dioxane/THF, r e s u l t i n g i n a p i n k s o l u t i o n and a w h i t e p r e c i p i t a t e . S o l v e n t dioxane/THF removal from the i s o l a t e d s o l u t i o n gave a red o i l . Attempted r e c r y -s t a l l i z a t i o n from benzene gave an i n t r a c t a b l e , red-brown s o l i d , (b) [MeGa (dmpz) 3 ]M (CO) 2 (n 3 i-C 3H 4R) (M=Mo,W,Cr, and R=H , Me ) Complexes. One a l i q u o t of the s o l u t i o n from s e c t i o n (3-13(b)) c o n t a i n i n g Na +[MeGa(dmpz)^Mo(CO) 3] (0.8 grams, 1.4 mmoles) was r e a c t e d w i t h excess 3-bromopropene f o r 15 hou r s . A gas, presumed to be CO, was e v o l v e d ; ( e q u a t i o n 39, M=Mo, R=H, X=Br). T h i s r e s u l t e d i n an orange s o l u t i o n and a w h i t e p r e c i p i t a t e . S o l v e n t THF removal from t h e i s o l a t e d s o l u t i o n gave an orange s o l i d . Attempted r e c r y s t a l l i z a t i o n from benzene gave a y e l l o w -brown g l u e . - 148 -S i m i l a r l y , one a l i q u o t of the s o l u t i o n from s e c t i o n (3-13(b)) c o n t a i n i n g N a +[MeGa(dmpz) 3Mo(C0) 3]~ (0.8 grams, 1.4 mmoles) was r e f l u x e d w i t h excess 3-chloro-^2-methylpropene f o r o n e - h a l f hour. T h i s r e s u l t e d i n an orange s o l u t i o n and a w h i t e p r e c i p i t a t e . S o l v e n t THF removal f rom the i s o l a t e d s o l u t i o n gave a yellow-brown s o l i d . R e c r y s t a l l i z a t i o n from benzene gave l a r g e , y e l l o w c r y s t a l s of [MeGa(dmpz) 2(OH)]Mo ( C 0 ) 2 ( n 3 - C 4 H ? ) . An a l i q u o t of the Na +[MeGa(dmpz) 3W(CO) ] s o l u t i o n from s e c t i o n (3-13(b)) was r e f l u x e d f o r 5 hours w i t h excess 3-bromopropene i n dioxane/THF s o l v e n t . A gas, presumed to be CO, was e v o l v e d . T h i s r e s u l t e d i n a lemon-yellow s o l u t i o n and a w h i t e p r e c i p i t a t e . S o l v e n t dioxane removal from the i s o l a t e d s o l u t i o n gave a y e l l o w - g r e e n s o l i d and a brown s o l i d . R e c r y s t a l l i z a t i o n of t h i s m i x t u r e from benzene gave some un-i d e n t i f i e d , s h e e t - l i k e c r y s t a l s . S i m i l a r l y , one a l i q u o t of the Na +[MeGa(dmpz) 3W(CO) 3] s o l u t i o n from s e c t i o n ( 3-13(b)) was r e f l u x e d f o r 15 hours w i t h excess.'. 3-chloro-2-methylpropene i n dioxane/THF s o l v e n t . A gas, presumed to be CO, was s l o w l y e v o l v e d . T h i s r e s u l t e d i n a lemon-yellow s o l u t i o n and a w h i t e p r e c i p i t a t e . S o l v e n t dioxane/THF removal gave a y e l l o w s o l i d . R e c r y s t a l l i z a t i o n from benzene gave some u n i d e n t i f i e d , s h e e t - l i k e c r y s t a l s . One a l i q u o t of the Na +[MeGa(dmpz)^Cr(CO) 3]~ s o l u t i o n from s e c t i o n (3-13(b)) was r e f l u x e d f o r 2 hours w i t h excess 3-bromopropene i n dioxane/THF s o l v e n t . A gas, presumed to be - 149 -CO, was e v o l v e d . T h i s r e s u l t e d i n an o l i v e - g r e e n s o l u t i o n and a w h i t e p r e c i p i t a t e . S o l v e n t dioxane/THF removal from the i s o l a t e d s o l u t i o n gave an o l i v e - c o l o r e d s o l i d . Attempted r e c r y s t a l l i z a t i o n from benzene gave an i n t r a c t a b l e , b e i g e s o l i d . S i m i l a r l y , one a l i q u o t of the Na +[MeGa(dmpz)^Cr (Cp)^] s o l u t i o n from (3-13(b)) was r e f l u x e d f o r 7 -hours w i t h excess 3-chloro^2-methylpropene i n dioxane/THF s o l v e n t . A gas, presumed to be CO, was s l o w l y e v o l v e d . T h i s r e s u l t e d i n a red-brown s o l u t i o n and a w h i t e p r e c i p i t a t e . S o l v e n t dioxane /THF removal from the i s o l a t e d s o l u t i o n gave a green-brown s o l i d . Attempted r e c r y s t a l l i z a t i o n from benzene gave an i n -t r a c t a b l e , green-brown s o l i d . (c) [ MeGa(mpz) 3]M(CO) 2(n 3-C 3H 4R) (M=Mo,W, and R=H,Me) Complexes. One a l i q u o t of the s o l u t i o n from s e c t i o n ( 3 - 1 3 ( c ) ) c o n t a i n i n g Na +[MeGa(mpz)^Mo(CO) 3] (0.97 grams, 1.8 mmoles) was r e f l u x e d f o r 4 hours w i t h excess 3-bromopropene i n THF s o l v e n t . A gas, presumed to be CO, was e v o l v e d . T h i s r e s u l t e d i n a y e l l o w s o l u t i o n and a w h i t e p r e c i p i t a t e (equa-t i o n 46, M=Mo, R=H, X=Br). S o l v e n t THF removal from the i s o l a t e d s o l u t i o n gave a yellow-brown s o l i d . R e c r y s t a l l i z a -t i o n from benzene gave y e l l o w c r y s t a l s c o n t a i n i n g both [ M e Ga(mpz) 3]Mo(CO) 2(n 3-C 3H 5) and [MeGa(mpz) £(OH)]Mo(CO) ( n 3 - c 3 H 5 ) . S i m i l a r l y , one a l i q u o t of the s o l u t i o n from s e c t i o n - 150 -( 3 - 1 3 ( c ) ) c o n t a i n i n g Na +[MeGa(mpz) 3Mo(CO) ]~ (0.97 grams, 1.8 mmoles) was r e f l u x e d f o r s e v e r a l hours w i t h excess 3-c h l o r o - 2 - m e t h y l p r o p e n e i n THF s o l v e n t . A gas, presumed to be CO, was s l o w l y e v o l v e d . T h i s r e s u l t e d i n an orange s o l u -t i o n and a w h i t e p r e c i p i t a t e . S o l v e n t THF removal from the i s o l a t e d s o l u t i o n gave a yellow-brown o i l . R e c r y s t a l l i z a t i o n from heptane gave a s m a l l amount of y e l l o w c r y s t a l l i n e s o l i d 3 which c o n t a i n s both [MeGa (mp z ) ]Mo (CO ) 2 ( n -C^H^ and [MeGa ( m p z ) 2 ( O H ) ] M o ( C 0 ) 2 ( n 3 - C 4 H 7 ) . One a l i q u o t of the N a + [ M e G a ( m p z ) ( C O ) 3 ] s o l u t i o n from s e c t i o n ( 3 - 1 3 ( c ) ) was r e f l u x e d f o r o n e - h a l f hour w i t h excess 3-bromopropene i n dioxane/THF s o l v e n t . Gas e v o l u t i o n was n e g l i g i b l e . T h i s r e s u l t e d i n a y e l l o w - o r a n g e s o l u t i o n and a w h i t e p r e c i p i t a t e . S o l v e n t dioxane/THF removal from the i s o l a t e d s o l u t i o n gave a brown-orange s o l i d . R e c r y s t a l l i z a -t i o n from benzene gave p a l e y e l l o w , s h e e t - l i k e c r y s t a l s con-s i s t i n g l a r g e l y of W(C0)^ w i t h a s m a l l amount of [MeGa(mpz) 3] w(co) 2(n 3-c 3H 5). S i m i l a r l y , one a l i q u o t of the Na +[MeGa(mpz) W(CO) 3] s o l u t i o n from ( 3 - 1 3 ( c ) ) was r e f l u x e d f o r 15 hours w i t h excess 3-chloro-2-methylpropene i n dioxane/THF s o l v e n t . Gas e v o l u -t i o n was n e g l i g i b l e . T h i s r e s u l t e d i n a p a l e y e l l o w s o l u t i o n and a w h i t e p r e c i p i t a t e . S o l v e n t dioxane/THF removal from the i s o l a t e d s o l u t i o n gave a y e l l o w , o i l y s o l i d . R e c y r s t a l l i -z a t i o n from benzene gave p a l e y e l l o w , s h e e t - l i k e c r y s t a l s of u n r e a c t e d W(CO),,. - 151 -3-17. S y n t h e s i s of [MeGa(pz)• ] M ( C O ) 2 ( n 3 - C H 5 R ) (M=W,Mo, and R=H,Me) Complexes and T h e i r P y r a z o l y l S u b s t i t u t e d D e r i v a t i v e s from (CH^CN)^M(CO) . (a) [MeGa(pz) 3]W(CO) 2 ( n 3-C 3H 4R)(R=H,Me) Complexes The procedure was s i m i l a r f o r each experiment and may be i l l u s t r a t e d by d e s c r i b i n g the p r e p a r a t i o n of the [MeGa(pz) 3]W(CO) 2(n 3-C H 5> complex. I n t o a t h r e e - n e c k e d f l a s k was added a y e l l o w s l u r r y of (CH 3CN) 3W(CO) 3 (1.381 grams, 3.534 mmoles) i n THF. The flas k was s t o p p e r e d and removed from the glovebox. The f l a s k was then equipped w i t h a magnetic s t i r r i n g bar and a r e f l u x condenser, and excess 3-bromopropene (2 ml) was added to the f l a s k . The r e a c t i o n m i x t u r e s l o w l y developed i n t o a w i n e - r e d s o l u t i o n over a p e r i o d of s e v e r a l m i n u t e s , and a gas, presumed to be CO, was e v o l v e d {.equation 31, R=H) . Then one 50 ml a l i q u o t of l i g a n d s o l u t i o n c o n t a i n i n g Na +[MeGa(pz) ] (1.09 grams, 3.53 mmoles) i n THF was added to the s t i r r i n g s o l u t i o n . The r e a c t i o n m i x t u r e was warmed to r e f l u x , r e s u l t i n g i n an orange s o l u t i o n and a w h i t e p r e c i p i t a t e ( e q u a t i o n 32, R=H). S o l v e n t THF removal from the i s o l a t e d s o l u t i o n gave a brown, o i l y s o l i d . R e c r y s t a l l i z a t i o n from benzene gave yellow-brown c r y s t a l s of [MeGa(pz)„]W(CO)_(n 3-CH). 3 z 3 5 S i m i l a r l y , a y e l l o w s l u r r y of (CH 3CN) 3W(CO) (1.25 grams, 2.878 mmoles) was r e f l u x e d w i t h excess 3 - c h l o r o - 2 -methylpropene f o r one h a l f hour i n THF s o l v e n t , r e s u l t i n g i n a dark red-brown s o l u t i o n . A gas, presumed to be CO, was - 152 -ev o l v e d . A d d i t i o n of one 50 ml a l i q u o t of l i g a n d s o l u t i o n 4- -c o n t a i n i n g Na [MeGaCpz)^] (0.890 grams, 2.88 mmoles) to the warm r e a c t i o n m i x t u r e caused i t to change i n c o l o r to y e l l o w -brown. The r e a c t i o n m i x t u r e was then r e f l u x e d f o r s e v e r a l minutes r e s u l t i n g i n a brown s o l u t i o n and a w h i t e p r e c i p i t a t e . S o l v e n t THF removal from the i s o l a t e d s o l u t i o n gave a y e l l o w -brown s o l i d . R e c r y s t a l l i z a t i o n from benzene gave s m a l l , 3 y e l l o w c r y s t a l s of [MeGa(pz) ]W(CO) 2(n -C^R^). (b) [ M e G a ( d m p z ) 2 ( O H ) ] M ( C 0 ) 2 ( n 3 - C 3 H 5 R ) (M=Mo,W, R=H,Me) Complexes. (CH 3CN) 3Mo(CO) (0.872 grams, 2.88 mmoles) was r e a c t e d w i t h excess 3-bromopropene i n THF s o l v e n t . A gas presumed t o be CO, was e v o l v e d ( e q u a t i o n 40, M=Mo, R=H, X=Br). A f t e r s e v e r a l minutes the r e a c t i o n m i x t u r e darkened to a wine-red s o l u t i o n . Then one 50 ml a l i q u o t of l i g a n d s o l u t i o n c o n t a i n i n g Na +[MeGa(dmpz) 3] (1.13 grams, 2.88 mmoles) i n THF was added to the s o l u t i o n , r e s u l t i n g i n a lemon-yellow S O I U T t i o n and a w h i t e p r e c i p i t a t e ( e q u a t i o n 41, M=Mo, R=H, X=Br). S o l v e n t THF removal from the i s o l a t e d s o l u t i o n gave a y e l l o w s o l i d . R e c r y s t a l l i z a t i o n from benzene gave y e l l o w c r y s t a l s of [ M e G a ( d m p z ) 2 ( O H ) ] M o ( C O ) 2 ( n 3 - C H ) . S i m i l a r l y , (CH^N) 3Mo (CO) (0. 873 grams, 2.88 mmoles) was r e f l u x e d f o r two hours w i t h excess 3 - c h l o r o - 2 - m e t h y l p r o -pene i n THF s o l v e n t . A gas, presumed to be CO, was e v o l v e d . The r e s u l t i n g s o l u t i o n was y e l l o w - o r a n g e i n c o l o r . Then one 50 ml a l i q u o t of l i g a n d s o l u t i o n c o n t a i n i n g Na +[MeGa (dmp z ),, ] - 153 -(1.13 grams, 2.88 mmoles) i n THF was added to the s t i r r i n g s o l u t i o n ; T h i s r e s u l t e d i n a y e l l o w - o r a n g e s o l u t i o n and a w h i t e p r e c i p i t a t e . S o l v e n t THF removal from the i s o l a t e d s o l u t i o n gave a ye l l o w - b r o w n , o i l y s o l i d . R e c r y s t a l l i z a t i o n from benzene gave s m a l l y e l l o w c r y s t a l s of [MeGa(dmpz) 2(OH)] Mo(CO) ( n 3 - c 4 H 7 ) . A s l u r r y of ( C H ^ C N ) ( C O ) ^ (1.26 grams, 2.880 mmoles) was r e a c t e d w i t h excess 3-bromopropene f o r 20 m i n u t e s ) . A gas, presumed to be GO, was e v o l v e d . T h i s r e s u l t e d i n a deep c h e r r y - r e d s o l u t i o n . Then one 50 ml a l i q u o t of l i g a n d s o l u -t i o n c o n t a i n i n g Na +[MeGa(dmpz)^] (1.13 grams, 2.88 mmoles) i n THF was added to the s t i r r i n g s o l u t i o n , r e s u l t i n g i n an orange s o l u t i o n and a w h i t e p r e c i p i t a t e . S o l v e n t THF removal from the i s o l a t e d s o l u t i o n gave an orange o i l . Attempted r e -c r y s t a l l i z a t i o n from benzene gave a brown g l u e . S i m i l a r l y , a s l u r r y of ( C H ^ C N ) ( C O ) ^ (1.25 grams, 2.876 mmoles) was r e a c t e d w i t h excess 3 - c h l o r o - 2 - m e t h y l p r o -pene i n THF s o l v e n t . The i n i t i a l l y orange r e a c t i o n m i x t u r e s l o w l y developed i n t o a red-brown s o l u t i o n on warming to r e r f l u x t e m p e r a t u r e . A gas, presumed to be CO, was e v o l v e d . Then one 50 ml a l i q u o t of l i g a n d s o l u t i o n c o n t a i n i n g Na +[Me Ga(dmpz)^] (1.13 grams, 2.88 mmoles) i n THF was added to the s t i r r i n g s o l u t i o n , r e s u l t i n g i n a yellow-brown s o l u t i o n and a w h i t e p r e c i p i t a t e . S o l v e n t THF removal from the i s o l a t e d s o l u t i o n gave a y e l l o w s o l i d . R e c r y s t a l l i z a t i o n from benzene gave y e l l o w c r y s t a l s of [ M e G a ( d m p z ) 2 ( O H ) ] W ( C O ) 2 ( n 3 - C 4 H y ) . - 154 -CHAPTER IV THE ATTEMPTED SYNTHESIS OF [ H 2 B ( O C H 2 G H 2 N M e 2 ) ( p z ) ] " AND RE-LATED LIGANDS AND THEIR COORDINATION COMPOUNDS A. R e s u l t s and D i s c u s s i o n . In p r e v i o u s s t u d i e s ( 3 9 ) , symmetric a n i o n i c l i g a n d s of the type [Me^Gafpz)^] have been s y n t h e s i z e d and t h e i r c h e l a t i n g p r o p e r t i e s towards t r a n s i t i o n m etals s t u d i e d . Sub-s t i t u t i o n of one of the two p y r a z o l y l groups by a d i f f e r e n t a c t i v e hydrogen compound has l e d to a wide v a r i e t y of asym-m e t r i c l i g a n d s of p o t e n t i a l l y h i g h e r d e n t i c i t y . Two r e c e n t papers (46,47) have d e s c r i b e d the syn-t h e s i s of the t r i d e n t a t e c h e l a t i n g l i g a n d s Na +[Me 2Ga(OCH 2CH 2 N H 2 ) ( N 2 C 3 H 3 ) ] ~ and N a + [ M e G a ( O C H 2 C H 2 N M e 2 ) ( N 2 C H 3 ) ] ~ and the c h a r a c t e r i z a t i o n of t h e i r t r a n s i t i o n metal complexes. These two l i g a n d s i n t e r a c t w i t h t r a n s i t i o n m etals i n the manner shown i n F i g u r e 40: F i g u r e 40 ( D (II) The c h e l a t i n g a b i l i t y of [ M e ^ a (OCH 2CH 2NH 2 ) (pz ) ] - 155 -X I ) was demonstrated by the i s o l a t i o n and c h a r a c t e r i z a t i o n of a number of o c t a h e d r a l complexes ^ a (Q^B.^CH^NR^ ) (pz ) ] (M=Mn, Fe,Co,Ni,Cu,Zn). In a d d i t i o n , i t was found t h a t the l i g a n d was ca p a b l e of g i v i n g e i t h e r f a c i a l or m e r i d i o n a l i s o m e r s . T h i s was demonstrated through the c r y s t a l s t r u c t u r e , d e t e r m i n a t i o n of the two n i c k e l isomers (see F i g u r e 16). The [Me 2Ga (OCH 2CH 2NMe 2) (pz) ]~ (II)... l i g a n d , on the ot h e r hand, was found to be s t e r i c a l l y more demanding, as the r e s u l t i n g t r a n s i t i o n m e t a l complexes were b i n u c l e a r [Me^Ga (OCH 2CH 2NMe 2);(pz ) J 2M 2(pz) 2 (M=Co , N i , Cu , Zn) , h a v i n g d i s t o r t e d square p y r a m i d a l c o o r d i n a t i o n geometry about the t r a n s i t i o n m e t al atoms. These metal atoms were b r i d g e d by two p y r a z o l y l groups and end-capped w i t h t r i d e n t a t e l i g a n d s . The m o l e c u l a r s t r u c t u r e of the copper complex i s shown:,in F i g u r e 15. The f o r m a t i o n of these compounds must i n v o l v e d e c o m p o s i t i o n of the l i g a n d as t h i s i s the o n l y source of p y r a z o l y l m o i e t i e s . I t i s p o s s i b l e t h a t once the l i g a n d has been accomodated, a second l i g a n d l i n k e d to the t r a n s i t i o n m e t a l v i a i t s p y r a z o -l y l n i t r o g e n atom i s unable to c o o r d i n a t e f u r t h e r and l o s e s 'Me 2Ga(OCH 2CH 2NMe 2)' which i m m e d i a t e l y forms the known dimer [Me 2Ga(OCH 2CH 2NMe 2)] 2 ( 1 5 ) . T h i s product o c c u r r e d as a w h i t e r e s i d u e o b t a i n e d d u r i n g r e c r y s t a l l i z a t i o n p r o c edures and was i d e n t i f i e d by i t s c h a r a c t e r i s t i c mass spectrum. These r e s u l t s l e d to the attempted s y n t h e s i s of the c o r r e s p o n d i n g boron l i g a n d s [H 2B(OCH 2CH 2NH 2) ( p z ) ] ~ and [H^B (OCH„CH NMe„)(pz)] , and an i n v e s t i g a t i o n of t h e i r c h e l a t i n g - 156 -p r o p e r t i e s towards v a r i o u s t r a n s i t i o n m e t a l s . I t i s w e l l documented (3) t h a t boron h y d r i d e s and and a l k y l s r e q u i r e h i g h e r r e a c t i o n temperatures when r e a c t e d w i t h a c t i v e hydrogen compounds i n o r d e r to e l i m i n a t e hydrogen or a l k a n e than do the c o r r e s p o n d i n g g a l l i u m compounds. The r e a c t i o n of p o t a s s i u m b o r o h y d r i d e w i t h an excess amount of molten p y r a z o l e r e q u i r e s a p y r o l y s i s temperature of 90°-120°C to e l i m i n a t e two moles of hydrogen i n the f o l l o w i n g scheme (21) : Q n ° _ i I A ° KBH 4 + 2Hpz — — <• K [ H 2 B ( p z ) 2 ] + 2H 2 (50) In c o n t r a s t , the r e a c t i o n of Na[Me^Ga(pz)] and p y r a z o l e r e q u i r e d o n l y t h a t the two r e a c t a n t s be b r i e f l y r e -f l u x e d i n THF s o l v e n t (b. p. 65°C) to e l i m i n a t e methane. T H T*1 Na[Me Ga(pz)] + Hpz •Na[Me„Ga(pz)J + CH. (51) -> ^ Z z 4 T h i s i s f u r t h e r r e f l e c t e d i n the s y n t h e s i s of the [H 2B(OCH 2 CH 2NMe 2]] monomer. The r e a c t i o n of d i b o r a n e and N,N—dimethy-l e t h a n o l a m i n e was slow at 25°C, however, when the r e a c t a n t s were warmed to 60°C, the r e a c t i o n went to c o m p l e t i o n : B2H6;(g) + 2HOCH 2CH 2NMe 2 — 2 [H^B'CO.C^ CH 2NMe 2 ) ] + 2H 2 (52) The mass spectrum of t h i s compound showed peaks due to the monomer u n i t , [ H 2B(0CH 2CH 2NMe 2)], and the monomer p l u s - 157 -one and two p r o t o n s . T h i s b e h a v i o r has been noted p r e v i o u s l y f o r boron compounds ( 7 3 ) . No h i g h e r mass peaks were observed. In a d d i t i o n , peaks due to [Me 2NCH 2CH 2OH] +, [Me 2NCH 2CH 20] +, [ M e 2 C H 2 C H 2 ] + , [ M e 2 N C H 2 ] + , and [ M e 2 N ] + w e r e observed. The "^H n.m.r. spectrum of the compound i n benzene showed t r i p l e t s c e n t r e d at 6.00T, 6.27T, 7.29T and 7.70x, which were due to the methylene p r o t o n s of the a m i n o a l c o h o l . Two n i t r o g e n methyl p r o t o n resonances were found at 7.70x and 7.96 T. The boron p r o t o n resonances were not d e t e c t e d , even i n the spectrum of the neat compound. The i n f r a r e d spectrum of the neat compound showed -1 VB-H s t r e t c h i n g f r e q u e n c i e s at 2380 ( s ) , 2320 (s) and 2275 (s),cm , however, no f u r t h e r assignments were attempted. In summary, two main p o i n t s must be c o n s i d e r e d i n any attempt to s y n t h e s i z e the [H 2B(0CH 2CH 2NR 2) ( p z ) ] ~ l i g a n d s (R=H or Me). F i r s t , boron h y d r i d e s r e q u i r e a h i g h e r p y r o l y s i s temperature than the c o r r e s p o n d i n g g a l l i u m compounds, which may l e a d to l i g a n d s c r a m b l i n g d u r i n g the l i g a n d s y n t h e s i s . S e condly, the p o l y p y r a z o l y l b o r a t e s s y n t h e s i z e d by Trofimenko are e x t r e m e l y s t a b l e e l e c t r o n i c a l l y , h y d r o l y t i c a l l y , and o x i d a t i v e l y , and any d e c o m p o s i t i o n of the u n s y m m e t r i c a l l i g a n d [H 2B(OCH 2CH 2NR 2) (pz) ] may l e a d to t h e i r f o r m a t i o n . The i n i t i a l attempt was to f i r s t s y n t h e s i z e Na [H^B (p z ) ] and use t h i s as a s t a r t i n g m a t e r i a l to p r e p a r e .the p r e -v i o u s l y c h a r a c t e r i z e d Na +-(H 2B (pz ) 2,] " l i g a n d . The s t a r t i n g m a t e r i a l was s y n t h e s i z e d by warming eq u i m o l a r amounts of NaBH, - 158 -and p y r a z o l e i n diglyme s o l v e n t at 130°C, and i s o l a t i n g the r e s u l t i n g p r o duct as an e x t r e m e l y h y g r o s c o p i c , w h i t e s o l i d . NaBH + Hpz d ± ^ m & » N a + [ H 3 B ( p z ) ] + H o (53) 130 °C Then, the i s o l a t e d s o l i d was r e a c t e d w i t h e i t h e r p y r a z o l e or N,N-dimethylethanolamine i n a b r e a k - s e a l b u l b at 120°C as o u t l i n e d below: 0 Na [ H 3 B ( p z ) ] _ + Hpz 1 2 Q O c » N a + [ H 2 B ( p z ) 2 ] " + H 2 (54) N a + [ H 3 B ( p z ) ] + H0CH 2CH 2NMe 2 1 2 0 ° ' Na +[H 2B(0CH 2CH 2NMe 2) ( p z ) ] " + H 2 (55) The Na"*" [H 2B (pz ) 2 ] s a l t was s y n t h e s i z e d i n or d e r to i n v e s t i g a t e the f e a s a b i l i t y of u s i n g N a + [ H 3 B ( p z ) ] as a s t a r t i n g m a t e r i a l and employing t h i s p r e p a r a t i v e r o u t e . S i n c e c h a r a c t e r i z a t i o n of thes e l i g a n d s i s d i f f i c u l t , the [ H 2 B ( p z ) 2 ] 2 N i (21) complex was prepare d by m e t a t h e s i s . C h a r a c t e r i z a t i o n of t h i s complex was e a s i l y a c c o m p l i s h e d by m i c r o - a n a l y s i s and mass s p e c t r o s c o p y . The mass spectrum showed t h a t a s m a l l amount of [ H B ( p z ) 3 ] 2 N i was a l s o p r e s e n t i n the orange c r y s t a l s of [ H 2 B ( p z ) 2 ] 2 N i , so N a + [ H 2 B ( p z ) 2 ] ~ may not have been formed e x c l u s i v e l y i n r e a c t i o n 54. Thus the s t a r t i n g m a t e r i a l , Na [ H 3 B ( p z ) ] , may have a l r e a d y c o n t a i n e d some N a + [ H 2 B ( p z ) 2 ] , which r e a c t e d w i t h the p y r a z o l e to g i v e N a + [ H B ( p z ) 3 ] ~ . - 159 -+ The Na" [H B(OCH 2CH 2N-Me 2) (pz) ] s y n t h e s i s seemed to work q u i t e w e l l , as the c o r r e c t amount of hydrogen gas was ev o l v e d ( c a l c u l a t e d 233.9 ml found 236.1 m l ) . When the r e s u l t i n g w h i t e powder was r e a c t e d w i t h s t o i c h i o m e t r i c amounts 2 + of t r a n s i t i o n metal i o n M (M=Co,Ni), impure powders were o b t a i n e d . Mass s p e c t r a l a n a l y s i s of these powders showed t h a t they c o n t a i n e d [ H B ( p z ) 3 l 2 M i n s t e a d of the expected [ H 2 B ( O C H 2 C H 2 N M e 2 ) ( p z ) ] 2 M complexes. Assuming t h a t the l i g a n d formed, t h i s r e s u l t must be a t t r i b u t e d to d e c o m p o s i t i o n of [H 2B(OCH 2CH 2NMe 2) ( p z ) ] , p r o b a b l y on r e a c t i o n w i t h the t r a n -2 + s i t i o n m e t al i o n M , as was found i n the cas e.:of . the g a l l i u m analogue (46). The l i g a n d s y n t h e s i s was r e p e a t e d u s i n g the two p r e p a r a t i v e r o u t e s o u t l i n e d below i n which the BH^•THF adduct was the s t a r t i n g m a t e r i a l : HOCH„CH NMe„ BH 3-THF + Na(pz) ^ R F - Na [ H 3 B ( p z ) ] A , THF N a + [ H ? B ( O C H 2 C H 2 N M e 2 ) ( p z ) ] ~ + H 2 (56) BH 3-THF + Na(OCH 2CH 2NMe 2) - Na +[H 3B(OCH 2CH 2NMe 2) ] H p Z Na +[H B(OCH CH NMe ) ( p z ) ] " + H„ (57) A,THF Z L 1 1 In the f i r s t r o u t e , r e a c t i o n of the i n t e r m e d i a t e s a l t N a + [ H 3 B ( p z ) ] w i t h N,N-dimethylethanolamine i n THF s o l v e n t was ve r y d o u b t f u l , as H gas e v o l u t i o n was n e g l i g i b l e even at - 160 -r e f l u x t e mperature. T h i s i s not unr e a s o n a b l e i n l i g h t of the f a c t t h a t the e l i m i n a t i o n r e a c t i o n of N a + [ H j B ( p z ) ] and N,N-di-m e t h y l e t h a n o l a m i n e to g i v e Na +[H 2B(OGH^^NMep (pz) ] and hydrogen gas r e q u i r e d a p y r o l y s i s temperature of 120°C to complete the r e a c t i o n ( e q u a t i o n 5 5 ) , w h i l e the r e f l u x temperature of THF i s o n l y 65-66°C. In a d d i t i o n , the r e a c t i o n of the r e s u l t i n g 2 + l i g a n d s o l u t i o n w i t h t r a n s i t i o n m e tal i o n s M (M=Cd,Ni,Cu) gave no t r a c t a b l e p r o d u c t s . The a l t e r n a t e r o u t e s t i l l employed BH^-THF as a s t a r t i n g m a t e r i a l , but i n s t e a d of r e a c t i n g i t w i t h sodium p y r a z o l i d e , i t was f i r s t r e a c t e d w i t h the sodium s a l t of the N,N-dimethylethanolamine to form the i n t e r m e d i a t e s a l t Na +[H^B(OCH 2CH 2NMe2)] , f o l l o w e d by an e l i m i n a t i o n r e a c t i o n w i t h p y r a z o l e i n r e f l u x i n g THF to g i v e , h o p e f u l l y , Na^tH^B (OCH 2CH 2NMe2) ( p z ) ] and hydrogen gas. Gas e v o l u t i o n i n t h i s case was v e r y slow. A p o r t i o n of the l i g a n d s a l t was i s o l a t e d from THF r e s u l t i n g i n c r y s t a l l i n e s o l i d which a n a l y s e d f a i r l y w e l l (see s y n t h e t i c d e t a i l s , page 168). R e a c t i o n of the l i g a n d 2 + s o l u t i o n w i t h t r a n s i t i o n metal M i o n s (M=Co, N i , Cu, Zn) ag a i n gave impure powders. Mass s p e c t r a l a n a l y s i s showed t h a t these s o l i d s c o n t a i n e d .[ H 2 B (pz ) 2 ] 2M and [ H B ( p z ) 3 ] 2 M complexes. These r e s u l t s are e s s e n t i a l l y i d e n t i c a l w i t h those found e a r l i e r i n the i n i t i a l e xperiments w i t h t h i s l i g a n d . The f i n a l attempt to s y n t h e s i z e t h i s l i g a n d employed dib o r a n e gas as a s t a r t i n g m a t e r i a l i n the f o l l o w i n g scheme; - 161 -THF Na [H 3B(OCH 2CH 2NMe 2)] Hpz - Na [H 2B(OCH 2CH 2NMe 2)(pz)] + H £ (58) THF , A Hydrogen e v o l u t i o n i n the f i n a l step was v e r y slow a g a i n . The r e s u l t i n g l i g a n d s o l u t i o n was r e a c t e d w i t h t r a n -2 + s i t i o n m e t a l M i o n s (M=Co,Ni) as b e f o r e . The c o b a l t r e a c t i o n gave a p u r p l e s o l i d whose mass spectrum showed i t to c o n t a i n [ H 2 B ( p z ) 2 ] 2 C o a n d [H 2B(pz)] 2« The n i c k e l r e a c t i o n gave an impure o l i v e - g r e e n s o l i d . Mass s p e c t r a l a n a l y s i s of t h i s s o l i d showed t h a t i t c o n t a i n e d the b i n u c l e a r complex [H 2B(OCH 2 CH 2NMe 2) (pz) ] 2 N i 2 ( p z ) 2 , a l t h o u g h the i s o t o p i c p a t t e r n s found i n the spectrum f o r N i 2 B 2 agreed p o o r l y w i t h those c a l c u l a t e d from t h e o r y . T h i s i s not unusual f o r boron c o n t a i n i n g com-pounds , as f r e q u e n t l y t h e r e i s an o v e r l a p of i s o t o p i c p a t t e r n s due to i o n s which have an m/e r a t i o of one mass u n i t d i f f e r e n c e . T h i s i s due, as mentioned b e f o r e , to the ready l o s s or g a i n of a H" moiety i n these compounds. In a d d i t i o n , the r e l a t i v e i n t e n s i t i e s of these p a t t e r n s cannot be p r e d i c t e d ( 7 3 ) . T h i s was the f i r s t r e s u l t t h a t p a r a l l e l l e d what was found i n the g a l l i u m system, a l t h o u g h the compound c o u l d not be o b t a i n e d i n pure form. T h i s problem seemed to plague the boron system, as the p r o d u c t s formed d i d not s e p a r a t e and c r y s t a l l i z e from the b y - p r o d u c t s to g i v e pure compounds as they d i d w i t h the g a l l i u m system. T h i s made c h a r a c t e r i z a t i o n of the boron com-pounds d i f f i c u l t . - 162 The attempted s y n t h e s i s of [H 2B(OCH 2CH 2NMe 2)(pz)] 3 Mo(CO) 2(n -C^H^R)(R=H,Me) a l s o proved f r u i t l e s s , both p r o d u c t s b e i n g i n t r a c t a b l e , o r a n g e - y e l l o w o i l s . Two s y n t h e t i c r o u t e s were attempted i n orde r to s y n t h e s i z e the N a + [ H 2 B ( E A ) ( p z ) ] ~ s a l t (EA=OCH 2CH 2NH 2), both u s i n g d i b o r a n e gas as a s t a r t i n g m a t e r i a l : _ HOCH CH NH %B 2H 6 + Na(pz) T R F » Na [ H 3 B ( p z ) ] THF , N a + [ H 2 B ( E A ) (pz) ] " + H 2 (59) %B 2H 6 + Na(EA) T R F » Na +[H^B(EA) ] H p Z THF, A N a + [ H 2 B ( E A ) (pz) ] + H 2 (60) In the f i r s t r o u t e , d i b o r a n e gas was r e a c t e d w i t h sodium p y r a z o l i d e r e s u l t i n g i n a c l e a r , c o l o r l e s s THF s o l u t i o n , a d d i t i o n of ethanolamine caused no change, and the r e a c t i o n m i x t u r e had to be r e f l u x e d . f o r H 2 e v o l u t i o n to o c c u r . T h i s r e s u l t e d i n a c l e a r , c o l o r l e s s l i g a n d s o l u t i on, The r e a c t i o n of t h i s l i g a n d s o l u t i o n w i t h s t o i c h i o -2 + m e t r i c q u a n t i t i e s of t r a n s i t i o n metal M i o n s (M=Co,Ni,Cu,Zn) gave impure s o l i d s . Mass s p e c t r a l a n a l y s i s of these s o l i d s showed t h a t the Co, N i , and Cu s o l i d s c o n t a i n e d [ H B ( p z ) 3 l 2 M w h i l e the z i n c s o l i d c o n t a i n e d [ H 2 B ( p z ) ] Zn. A g a i n , l i g a n d d e c o m p o s i t i o n to g i v e the more s t a b l e p o l y p y r a z o l y l b o r a t e com-pounds i s the dominate f a c t o r , even though the [ H 2 B ( E A ) ( p z ) ] - 163 -l i g a n d s h o u l d be s t e r i c a l l y l e s s demanding than the [R^B (OCH 2CH NMe 2) ( P z ) ] l i g a n d , as was demonstrated by the an-alogous g a l l i u m l i g a n d s . In the a l t e r n a t e r o u t e , d i b o r a n e gas was f i r s t r e a c t e d w i t h the sodium s a l t of ethanolamine to g i v e a c l e a r , p a l e y e l l o w s o l u t i o n . A d d i t i o n of p y r a z o l e to t h i s i n t e r -mediate N a + [ B ( E A ) ] s a l t r e s u l t e d i n hydrogen e v o l u t i o n at room t e m p e r a t u r e , and the r e a c t i o n m i x t u r e was then r e f l u x e d i n THF s o l v e n t to ensure a complete r e a c t i o n . The r e s u l t i n g c l e a r , c o l o r l e s s l i g a n d s o l u t i o n was 2 + then r e a c t e d w i t h t r a n s i t i o n m e t a l M i o n s (M=Co,Ni,Cu). The c o b a l t r e a c t i o n gave an i n t r a c t a b l e , brown s o l i d . The n i c k e l r e a c t i o n gave an impure, l i l a c s o l i d . Mass s p e c t r a l a n a l y s i s showed t h a t i t c o n t a i n e d [ H B ( p z ) ^ ] 2 N i • The copper r e a c t i o n gave an impure, b l u e s o l i d . Mass s p e c t r a l a n a l y s i s of t h i s s o l i d showed t h a t i t c o n t a i n e d a b i n u c l e a r complex, as the h i g h e s t mass i o n showed a CU2B2 i s o t o p i c p a t t e r n c l o s e to t h a t c a l c u l a t e d from t h e o r y . However, the spectrum c o u l d not be a s s i g n e d w i t h c e r t a i n t y . 3 The attempted s y n t h e s i s of [H 2B(EA) (pz)]Mo(CO) (n -C 3 H/ + R) (R=H ,Me) •-via the. t h e r m a l r o u t e gave impure, brown s o l i d s . Mass s p e c t r a l a n a l y s i s of these s o l i d s showed t h a t they con-t a i n e d [ H B ( E A ) ( p z ) 2 ] M o ( C O ) 2 ( n 3 - C 3 H 4 R ) ( R = H , M e ) . The i s o t o p i c p a t t e r n s found f o r Mo-B o n l y agreed r o u g h l y w i t h those c a l -c u l a t e d from t h e o r y . In summary, the main o b s t a c l e i n the r e a c t i o n of the - 164 -un s y m m e t r i c a l boron l i g a n d s [H B(OCH 2CH 2NR 2) (pz ) ] (R=H,Me) and t r a n s i t i o n metals was the f a i l u r e of the r e s u l t i n g p r o d u c t s to s e p a r a t e from each o t h e r and form pure c r y s t a l l i n e s o l i d s , which are u s u a l l y e a s i e r to c h a r a c t e r i z e than the impure powders o b t a i n e d . The c o r r e s p o n d i n g g a l l i u m l i g a n d s [Me 2Ga(OCH CH NR )(pz)]~(R=H,Me), on the o t h e r hand, tended to g i v e pure c r y s t a l l i n e p r o d u c t s . In a d d i t i o n , t h i s work shows t h a t the [ H B ( p z ) 3 ] 2 M and [ H 2 B ( p z ) 2 ] 2 M ( M = t r a n s i t i o n m e tal) complexes p r e v i o u s l y c h a r a c t e r i z e d by Trofimenko (15) are f a v o r e d over the [ H 2 B ( O C H 2 C H 2 N R 2 ) ( p z ) ] 2 M (R=H,Me) complexes, as no evidence f o r the f o r m a t i o n of the l a t t e r complexes was found. Based on p r e v i o u s e v i d e n c e , the most o b v i o u s mechanism f o r the f o r m a t i o n of these p o l y p y r a z o l y l b o r a t e complexes i s l i g a n d s c r a m b l i n g , a l t h o u g h no proof of t h i s was found. - 165 -B. S y n t h e t i c D e t a i l s 4-1. S y n t h e s i s of, [R^B (OCH 2CH 2NMe 2 ) ] Diborane gas (106.8 ml, 4.77 mmoles) was condensed onto a f r o z e n THF s o l u t i o n of H0CH 2CH 2NMe 2 (0.85 grams, 9.5 mmoles) i n a b r e a k - s e a l b u l b . R e a c t i o n took p l a c e w e l l below room temperature as a gas, presumed to be hydrogen, was ev o l v e d ( e q u a t i o n 52). The r e a c t i o n m i x t u r e was warmed to 60°C f o r 48 hours. T h i s r e s u l t e d i n a c l e a r , c o l o r l e s s s o l u t i o n . The hydrogen gas e v o l v e d was measured w i t h the T o e p l e r pump ( C a l c u l a t e d 213.5 ml, found 247.6 m l ) . S o l v e n t THF removal gave a c o l o r l e s s o i l . 4-2. S y n t h e s i s of N a + [ H ^ B ( p z ) ] ~ NaBH^ (3.41 grams, 90.0 mmoles) a n d . p y r a z o l e (6.13 grams, 90.0 mmoles) were r e a c t e d i n diglyme s o l v e n t at 130°C u n t i l hydrogen e v o l u t i o n had ceased ( e q u a t i o n 53). S o l v e n t diglyme removal by vacuum d i s t i l l a t i o n gave an e x t r e m e l y h y g r o s c o p i c , w h i t e s o l i d , which was vacuum d r i e d between 60-145°C f o r t h r e e hours. A n a l y t i c a l d a t a f o r Na[H B(N 2C )] ( c a l c u l a t e d 0:34.68, H:5.82, N:26.96 , found C : 37 . 12 , H-.6.11, N:24.74). 4-3. S y n t h e s i s of N a + [ H 2 B ( p z ) 2 ] ~ (21) from N a + [ H ^ B ( p z ) ] ~ N a + [ H 3 B ( p z ) ] ~ (1.083 grams, 9.99 mmoles) and p y r a -z o l e (0.681 grams, 10.00 mmoles) were r e a c t e d i n a b r e a k - s e a l b u l b at 100°C f o r 15 hours ( e q u a t i o n 54). The amount of hydrogen gas e v o l v e d was measured w i t h the T o e p l e r pump - 166 -( c a l c u l a t e d 224.1 ml, found 112.1 m l ) . The r e s u l t i n g w h i t e s o l i d was washed w i t h t o l u e n e and d r i e d i n the glovebox. A n a l y t i c a l d a t a f o r N a + [H^B (N 2C R-j ) 2 ] ~ ( c a l c u l a t e d C-.42.09 , H;4.71, N:32.72, found C:37.39, H:4.79, N:29.75). S t o i c h i o m e t r i c amounts of the l i g a n d and N i ( B F 4 ) 2 ' 6H 20 were r e a c t e d as d e s c r i b e d i n r e f e r e n c e (21) to g i v e orange c r y s t a l s of [ H 2 B ( p z ) 2 ] 2 N i . A n a l y t i c a l data f o r [ H 2 B ( N 2 C 3 H 3 ) 2 ] 2 N i ( c a l c u l a t e d C:40.8, H:4.54, N:31.7, found C : 41.6, H:4.58, N:32.2). 4-4. R e a c t i o n of N a + [ H ^ B ( p z ) ] ~ w i t h HOCH 2CH 2NMe 2 N a + [ H 3 B ( p z ) ] " (1.084 grams, 10.43 mmoles) and HOCH 2CH 2NMe 2 (0.930 grams, 10.43 mmoles) were r e a c t e d as i n s e c t i o n (4-3) at 60°C f o r t h r e e days ( e q u a t i o n 55). The amount of hydrogen gas e v o l v e d was measured w i t h the T o e p l e r pump ( c a l c u l a t e d 233.9 ml, found 62.3 m l ) . The r e a c t a n t s were r e a c t e d f o r s e v e r a l more hours at 120°C, and the hydro-gen gas e v o l v e d was remeasured ( c a l c u l a t e d 233.9 ml, found 236.1 m l ) . The r e s u l t i n g product was a c o l o r l e s s o i l w hich, when washed w i t h benzene, gave a w h i t e s o l i d . (a) Attempted S y n t h e s i s of [H 2 B ( O C H 2 C H 2 N M e 2 ) ( p z ) ] 2 M (M=Co, Ni) Complexes C o C l 2 * 6 H 2 0 (0.082 grams, 0.343 mmoles) and the w h i t e s o l i d Na +[H 2B(OCH 2CH 2NMe 2) ( p z ) ] " (0. 234 grams, 1.22 mmoles) were r e a c t e d f o r s e v e r a l hours i n THF s o l v e n t as d e s c r i b e d i n s e c t i o n ( 3 - 5 ) . T h i s gave a p u r p l e s o l u t i o n and a w h i t e - 167 -p r e c i p i t a t e . The s o l v e n t THF was removed under vacuum from the i s o l a t e d s o l u t i o n g i v i n g a p u r p l e powder. Attempted r e c r y s t a l l i z a t i o n from benzene gave an a i r - s e n s i t i v e , p u r p l e s o l i d which c o n t a i n s [ H B ( p z ) ^ ] 2 C o • R e a c t i o n of s t o i c h i o m e t r i c q u a n t i t i e s of N i ( B F 4 ) 2 * 6H 20 and the l i g a n d gave, a f t e r p r o d uct work-up, a b l u e s o l i d which c o n t a i n s [ H B ( p z ) ^ ] 2 N i . 4 r 5 . Attempted S y n t h e s i s of Na +[H 2B(OCH 2CH 2NMe 2) (pz ) ] ~ from BH 3 * THF and Na ( p z ) . Na(pz) (2.254 grams, 25.03 mmoles) and one 25.0 ml a l i q u o t of 1.0 M BH^•THF (25.0 mmoles) were r e a c t e d at room temperature i n a 3-necked f l a s k ( e q u a t i o n 56). Then a s o l u -t i o n c o n t a i n i n g HOCH 2CH 2NMe 2 (2.230 grams, 25.00 mmoles) d i s s o l v e d i n THF was added dropwise to the f l a s k , and the r e s u l t i n g r e a c t i o n m i x t u r e was r e f l u x e d f o r 15 h o u r s . Hydro-gen gas e v o l u t i o n was n e g l i g i b l e ( e q u a t i o n 56). The c l e a r , c o l o r l e s s l i g a n d s o l u t i o n was made up to 500 ml w i t h THF and r e a c t e d i n measured a l i q u o t s . Assuming a 100% y i e l d , 4.8 grams (25.0 mmoles) of l i g a n d was produced. (a) Attempted S y n t h e s i s of [ H 2 B ( 0 C H 2 C H 2 N M e 2 ) ( p z ) ] 2 M (M=Co, Ni,Cu) Complexes. C o C l 2 * 6 H 2 0 (0.325 grams, 1.48 mmoles) was r e a c t e d w i t h one 100 ml a l i q u o t of the l i g a n d s o l u t i o n from s e c t i o n (4-5) c o n t a i n i n g N a + [ H 2 B ( 0 C H 2 C H 2 N M e 2 ) ( p z ) ] " (0.96 grams, 5.0 mmoles) i n a manner s i m i l a r to t h a t d e s c r i b e d i n s e c t i o n ( 3 - 5 ) . The r e s u l t i n g p u r p l e s o l u t i o n was worked-up to g i v e an a i r -- 168 -s e n s i t i v e , p u r p l e s o l i d . The analogous r e a c t i o n of the l i g a n d s o l u t i o n w i t h N i (BF^)^'6H2O gave, a f t e r work-up,ian i n t r a c t a b l e o l i v e - g r e e n s o l i d . S i m i l a r l y , r e a c t i o n w i t h anhydrous C u B r 2 gave an i n -t r a c t a b l e , b l u e g l a s s . 4-6. Attempted S y n t h e s i s of N a + [ H ^ B ( O C H 2 C H 2 N M e 2 ) ( p z ) ] ~ from BH 3'THF and Na(OCH 2CH 2NMe 2). Us i n g a procedure s i m i l a r to t h a t d e s c r i b e d i n s e c t i o n ( 4 - 5 ) , a s l u r r y of NaH (1.003 grams, 41.78 mmoles) was r e a c t e d f o r s e v e r a l hours w i t h H0CH 2CH 2NMe 2 (3.722 grams, 41.76 mmoles) i n THF s o l v e n t , r e s u l t i n g i n hydrogen e v o l u t i o n . The r e s u l t i n g Na +(0CH 2CH 2NMe 2) s o l u t i o n was c l e a r and c o l o r -l e s s . A d d i t i o n of 40.0 ml of 1.0 M BH^•THF (40.0 mmoles) to the s o l u t i o n caused no c o l o r change ( e q u a t i o n 57). F i n a l l y , a s o l u t i o n c o n t a i n i n g p y r a z o l e (2.837 grams, 41.67 mmoles) was added dropwise to the r e a c t i o n m i x t u r e , which was then r e -f l u x e d f o r s e v e r a l hours. Hydrogen e v o l u t i o n d u r i n g t h i s p e r i o d was v e r y slow ( e q u a t i o n 57). The c l e a r , c o l o r l e s s l i g a n d s o l u t i o n was made up to 500 ml w i t h THF and reacted:'in measured a l i q u o t s . Assuming a 100% y i e l d , 7.5 grams (40.0 mmoles) of l i g a n d was produced. A s m a l l p o r t i o n of the product was i s o l a t e d from the THF s o l v e n t to g i v e a h y g r o s c o p i c , w h i t e powder which was d r i e d i n vacao f o r s e v e r a l hours at 80°C. A n a l y t i c a l data f o r N a + [ H 2 B (0CH 2CH 2NMe 2) ( N 2 C 3 H 3 ) ] " ( c a l c u l a t e d C:44.02 , H:7.92, N-.21.99 found C:44.79, H:8.30, N:19.69). - 169 -(a) Attempted S y n t h e s i s of [ H 2 B ( O C H 2 C H 2 N M e 2 ) ( p z ) ] 2 M (M=Co, Ni,Cu,Zn) Complexes. In a procedure i d e n t i c a l to t h a t d e s c r i b e d i n section ( 3 - 5 ) , a s t o i c h i o m e t r i c q u a n t i t y of the a p p r o p r i a t e t r a n s i t i o n m e t a l s a l t was r e a c t e d w i t h one 100 ml a l i q u o t of the l i g a n d s o l u t i o n c o n t a i n i n g N a + [ H 2 B (0CH 2 CH2N.Me2 ) (p z ) ] (1.5 grams, 8.0 mmoles) i n THF. R e a c t i o n w i t h C o C l 2 ' 6 H 2 0 gave, a f t e r work-up,' an a i r - s e n s i t i v e p u r p l e s o l i d c o n t a i n i n g [ HB (p z ) 3 ] 2 C o . A n a l y t i c a l d ata f o r [ HB ( I S ^ C ^ ^ ^ C o ( c a l c u l a t e d C:42.57 , H:7.66, N:21.28, found C:38.21, H:6.11, N:15.12). R e a c t i o n w i t h N i ( B F ^ ) 2 • 6 H 2 0 gave an o l i v e - g r e e n , i n t r a c t a b l e s o l i d . R e a c t i o n w i t h anhydrous CuBr 2 gave a b l u e s o l i d which c o n t a i n s [ H 2 B ( p z ) 2 ] ^ C u . R e a c t i o n w i t h anhydrous Z n C l 2 gave a w h i t e s o l i d which c o n t a i n s [ H B ( p z ) 3 l 2 Zn. A n a l y t i c a l d a t a f o r [ H B ( N 2 C 3 H 3 ) 3 1 Zn ( c a l c u l a t e d C:41.89, H:7.53, N:20.94 , found C:39.50, .. H: 5.91, N:15.71). 4-7. Attempted S y n t h e s i s of Na +[H 2B(0CH 2CH 2NMe 2) (pz) ] ~ from B H and Na +(OCH CH„NMe„)~ 2 6 2 2 2 Diborane gas (468.2 ml, 20.91 mmoles) was condensed onto a f r o z e n s l u r r y of Na +(0CH 2CH 2NMe 2)~ (4.627 mmoles, 41.64 mmoles) i n THF. The r e a c t i o n m i x t u r e was warmed to room temp e r a t u r e , r e s u l t i n g i n a c l e a r , c o l o r l e s s s o l u t i o n . Then a s o l u t i o n c o n t a i n i n g p y r a z o l e (2.837 grams, 41.67 mmoles) was - 170 -added dropwise to the r e a c t i o n m i x t u r e , which was then r e -f l u x e d f o r 60 hours ( e q u a t i o n 58). Hydrogen e v o l u t i o n was n e g l i g i b l e d u r i n g t h i s p e r i o d . The r e s u l t i n g c l e a r , c o l o r l e s s s o l u t i o n was made up to 500 ml w i t h THF and r e a c t e d i n measured a l i q u o t s . Assuming a 100% y i e l d , 7.95 grams (41.64 mmoles) of l i g a n d was produced. (a) Attempted S y n t h e s i s of [ H 2 B ( O C H 2 C H 2 N M e 2 ) ( p z ) ] 2 M (M=Co, N i ) Complexes In a pro c e d u r e i d e n t i c a l w i t h t h a t d e s c r i b e d i n s e c t i o n ( 3 - 5 ) , one 100 ml a l i q u o t of the above l i g a n d s o l u t i o n c o n t a i n i n g Na +[H 2B(0CH 2CH 2NMe 2) ( p z ) ] ~ (1.59 grams, 8.33 mmoles) was r e a c t e d w i t h anhydrous C o C l 2 (0.541 grams, 4.18 mmoles) i n T H F , s o l v e n t . The r e a c t i o n m i x t u r e gave, a f t e r work up, an a i r - s e n s i t i v e p u r p l e s o l i d which c o n t a i n e d [ H 2 B ( p z ) 2 ] 2 C o and [ H 2 B ( p z ) ] 2 . S i m i l a r l y , r e a c t i o n w i t h anhydrous N i B r 2 gave, a f t e r work-up, an o l i v e - g r e e n s o l i d which c o n t a i n s the b i n u c l e a r complex [H 2B(0CH 2CH 2NMe 2) (pz) } N i ( p z ) 2 . A n a l y t i c a l data f o r [H 2B(OCH 2CH 2NMe 2) ( N 2 C ^ ) ] 2 N i 2 ( N 2 C H ^ ( c a l c u l a t e d C:40.88, H:6.18, N:23.84, found C:42.52, H:6.26, N:20.55). (b) Attempted S y n t h e s i s of [ H 2 B ( 0 C H 2 C H 2 N M e 2 ) ( p z ) ] M o ( C O ) 2 (n 3-C 3H 4R)(R=H,Me) Complexes. U s i n g a procedure i d e n t i c a l to t h a t d e s c r i b e d i n s e c t i o n ( 3 - 1 3 ) , Mo.(C0)g (0.748 grams, 2.83 mmoles) was r e a c t e d at 60°C f o r 48 hours w i t h one 100 ml a l i q u o t of the l i g a n d s o l u t i o n c o n t a i n i n g Na +[H 2B(0CH 2CH 2NMe 2) (pz) ] ~ (1.59 grams, - 171 -8.33 mmoles). The CO gas e v o l v e d was measured w i t h the T o e p l e r pump ( c a l c u l a t e d 508.2 ml, found 341.5 m l ) . T h i s r e s u l t e d i n a red-brown THF s o l u t i o n , which was d i v i d e d i n t o two e q u a l a l i q u o t s and r e a c t e d as d e s c r i b e d below. U s i n g a procedure i d e n t i c a l w i t h t h a t d e s c r i b e d i n s e c t i o n (3-16) o n e - h a l f of the above s o l u t i o n was r e a c t e d f o r 15 hours w i t h excess 3-bromopropene (2 m l ) . A gas, presumed to be CO, was e v o l v e d . T h i s r e s u l t e d i n a yellow-brown s o l u -t i o n and a w h i t e p r e c i p i t a t e . S o l v e n t THF removal from the i s o l a t e d s o l u t i o n gave a y e l l o w - o r a n g e o i l . Attempted r e -c r y s t a l l i z a t i o n from benzene gave a y e l l o w - o r a n g e g l u e . S i m i l a r l y , o n e - h a l f of the s o l u t i o n was r e f l u x e d f o r two hours w i t h excess 3 - c h l o r o - 2 - m e t h y l p r o p e n e . A gas, presumed to be CO, was e v o l v e d . T h i s r e s u l t e d i n a y e l l o w -orange s o l u t i o n and a w h i t e p r e c i p i t a t e . S o l v e n t THF removal from the i s o l a t e d s o l u t i o n gave a y e l l o w - o r a n g e o i l . Attempted r e c r y s t a l l i z a t i o n from benzene gave a y e l l o w - o r a n g e o i l . 4-8. Attempted S y n t h e s i s of Na +[H B(EA) (pz ) ] ~ from B„H. and I lb Na ( p z ) . Diborane gas (502.1 ml. 22.40 mmoles) was condensed onto a f r o z e n s l u r r y of Na(pz) (4.053 grams, 45.00 mmoles) i n THF. The r e a c t i o n m i x t u r e was warmed to room t e m p e r a t u r e , r e s u l t i n g i n a c l e a r , c o l o r l e s s s o l u t i o n . Then a s o l u t i o n c o n t a i n i n g 2-aminoethanol (2.734 grams, 44.82 mmoles) i n THF was added dropwise to the r e a c t i o n m i x t u r e , which was then r e -f l u x e d f o r 48 hours ( e q u a t i o n 59). A gas, presumed to be - 172 -hydrogen, was e v o l v e d . The r e s u l t i n g c l e a r , c o l o r l e s s solu^t t i o n was made up to 500 ml w i t h THF and r e a c t e d i n measured a l i q u o t s . Assuming a 100% y i e l d , 7.30 grams (44.82 mmoles)' of l i g a n d was produced. (a) Attempted S y n t h e s i s of [H 2B(EA) ( p z ) ] 2 M (M=Co,Ni,Cu, and Zn) Complexes. In a p r o c e d u r e i d e n t i c a l t o t h a t d e s c r i b e d i n s e c -t i o n ( 3 - 5 ) , a s t o i c h i o m e t r i c q u a n t i t y of the a p p r o p r i a t e t r a n s i t i o n m e t a l s a l t was r e a c t e d w i t h one 100 ml a l i q u o t of the l i g a n d s o l u t i o n c o n t a i n i n g N a + [ H 2 B ( E A ) ( p z ) ] (1.46 grams, 8.96 mmoles) i n THF s o l v e n t . R e a c t i o n w i t h C o C l 2 ' 6 H 2 0 gave a p u r p l e s o l u t i o n and a w h i t e p r e c i p i t a t e . S o l v e n t THF removal from the i s o l a t e d s o l u t i o n gave an a i r - s e n s i t i v e , p u r p l e s o l i d . A t t e m p t e d r r e -c r y s t a l l i z a t i o n from benzene gave a red-brown s o l i d c o n t a i n i n g [ H B ( p z ) 3 ] 2 C o . R e a c t i o n w i t h N i ( B F ^ ) 2 • 6 H 2 0 gave an o l i v e - g r e e n s o l u t i o n and a brown p r e c i p i t a t e . In a d d i t i o n , a s m a l l q u a n t i t y of gas was e v o l v e d . S o l v e n t THF removal from the i s o l a t e d s o l u t i o n gave an o l i v e - g r e e n s o l i d . Attempted r e -c r y s t a l l i z a t i o n from benzene gave a brown s o l i d which c o n t a i n e d [ H 2 B ( p z ) 2 ] 2 N i . R e a c t i o n w i t h anhydrous CuBr^ gave an i n i t i a l l y b l u e s o l u t i o n which then became c o l o r l e s s as a dark brown s o l i d p r e c i p i t a t e d . S o l v e n t THF removal from the i s o l a t e d s o l u t i o n gave.a s m a l l q u a n t i t y of b l u e o i l . Attempted r e c r y s t a l l i z a t i o n - 17 3 -from benzene gave a b l u e , g l u e y s o l i d which c o n t a i n e d [ H B ( p z ) 3 l 2 C u . R e a c t i o n w i t h anhydrous ZnCl,., gave a c l e a r s o l u t i o n and a w h i t e p r e c i p i t a t e . S o l v e n t THF removal from the i s o -l a t e d s o l u t i o n gave a w h i t e , c r y s t a l l i n e s o l i d . R e c r y s t a l l i -z a t i o n from benzene gave c o l o r l e s s c r y s t a l s of [ H 2 B ( p z ) 2 ] 2 Z n and an i n t r a c t a b l e , w h i t e s o l i d . A n a l y t i c a l d ata f o r [ H 2 B ( N 2 C 3 H 3 ) 2 ] 2 Z n ( c a l c u l a t e d C:40.11, H:4.49, N:31.19, found C:40.30, H:4.58, N:30.65);. 4-9. Attempted S y n t h e s i s of Na [H„B(EA) (pz) ] from B.H, and z z o Na (EA) . Diborane gas (466.2 ml', 20.80 mmoles) was condensed onto a f r o z e n s l u r r y of Na(EA) (3.456 grams, 41.60 mmoles) (prepared as d e s c r i b e d i n s e c t i o n ( 4 - 6 ) ) . The r e a c t i o n mix-t u r e was warmed to room t e m p e r a t u r e , r e s u l t i n g i n a p a l e y e l l o w s o l u t i o n . Then a s o l u t i o n c o n t a i n i n g p y r a z o l e (4.031 grams, 41.60 mmoles) i n THF was added dropwise to the r e a c t i o n m i x t u r e . A gas, presumed to be hydrogen, was e v o l v e d ( e q u a t i o n 60). The r e a c t i o n m i x t u r e was r e f l u x e d f o r 40 hours. The r e s u l t i n g c l e a r , c o l o r l e s s s o l u t i o n was made up to 500 ml w i t h THF and r e a c t e d i n measured a l i q u o t s . Assuming a 100% y i e l d , 6.80 grams, (41.60 mmoles) of l i g a n d was produced. (a) Attempted S y n t h e s i s of [ H 2 B ( E A ) ( p z ) ] 2 M (M=Co,Ni,Cu) Complexes. In a p r o c e d u r e i d e n t i c a l t o t h a t d e s c r i b e d i n s e c t i o n ( 3 - 5 ) , a s t o i c h i o m e t r i c q u a n t i t y of the a p p r o p r i a t e - 174 -t r a n s i t i o n metal s a l t was r e a c t e d w i t h one 100 ml a l i q u o t of the above l i g a n d s o l u t i o n c o n t a i n i n g N a + [ B ( E A ) ( p z ) ] (1.36 grams, 8.32 mmoles) i n THF s o l v e n t . R e a c t i o n w i t h C o C l 2 * 6 H 2 0 gave a p u r p l e s o l u t i o n and a w h i t e p r e c i p i t a t e . S o l v e n t THF removal from the i s o l a t e d s o l u t i o n gave a p u r p l e o i l . Attempted r e c r y s t a l l i z a t i o n from benzene gave a p u r p l e o i l . Repeated attempts gave an i n -t r a c t a b l e , brown s o l i d . R e a c t i o n w i t h anhydrous N i B r 2 gave a l i l a c s o l u t i o n and a b l a c k p r e c i p i t a t e . S o l v e n t THF removal from the i s o -l a t e d s o l u t i o n gave a l i l a c - c o l o r e d o i l . Attempted r e c r y s s t a l l i z a t i o n from benzene gave a l i l a c s o l i d which c o n t a i n e d [ H B ( p z ) 3 ] 2 N i . A n a l y t i c a l d a t a f o r [ H B ( N £ C 3 H 3 ) 3 ] 2 N i ( c a l -c u l a t e d C : 44.59 , H:4.16, N:34. 67 , found C:42.70, H:5.33, N:7.46) . R e a c t i o n w i t h anhydrous CuBr^ f o r s e v e r a l hours gave a b l u e s o l u t i o n and a w h i t e p r e c i p i t a t e . Copper m e t a l was a l s o p l a t e d on the i n s i d e w a l l of the r e a c t i o n f l a s k . S o l v e n t THF removal from the i s o l a t e d s o l u t i o n gave a b l u e s o l i d . Attempted r e c r y s t a l l i z a t i o n from benzene gave a b l u e , a i r - s e n s i t i v e s o l i d which c o n t a i n e d a b i n u c l e a r C u 2 B 2 complex. (b) Attempted S y n t h e s i s of [ H 2 B (EA) (pz) ]Mo ( C 0 ) 2 (n^-C^H^R) (R=H,Me) Complexes. U s i n g a procedure i d e n t i c a l to t h a t d e s c r i b e d i n s e c t i o n ( 3 - 1 3 ) , M o ( C 0 ) 6 (1.753 grams, 6.640 mmoles) was r e a c t e d at 60°C f o r 24 hours w i t h one 100 ml a l i q u o t of l i g a n d s o l u t i o n - 175 -+ c o n t a i n i n g N a + [ B ( E A ) (pz) ] (1.36 grams, 8.32 mmoles). The CO gas e v o l v e d was measured w i t h the T o e p l e r pump ( c a l c u l a t e d 446.5 ml, found 522.8 m l ) . The r e s u l t i n g o l i v e - g r e e n THF s o l u t i o n was d i v i d e d i n t o t h r e e e q u a l a l i q u o t s and r e a c t e d as d e s c r i b e d below. U s i n g a procedure i d e n t i c a l to t h a t d e s c r i b e d i n s e c t i o n ( 3 - 1 6 ) , o n e - t h i r d of the above s o l u t i o n was r e a c t e d f o r s e v e r a l hours w i t h excess 3-bromopropene. A gas, presumed to be CO, was e v o l v e d . T h i s r e s u l t e d i n a brown-green s o l u -t i o n and a w h i t e p r e c i p i t a t e . S o l v e n t THF removal from the i s o l a t e d s o l u t i o n gave a brown-green s o l i d . Attempted r e -c r y s t a l l i z a t i o n from benzene gave a brown o i l . Attempted r e c r y s t a l l i z a t i o n of t h i s o i l from heptane gave a yellow-brown 3 s o l i d which c o n t a i n e d [ H B ( E A ) ( p z ) 2 ] M o ( C O ) 2 ( n - C . ^ ) . S i m i l a r l y , o n e - t h i r d of the Na +[H 2B(EA)(pz)Mo(CO) ]~ s o l u t i o n was r e f l u x e d f o r 2 hours w i t h 3 - c h l o r o - 2 - m e t h y l p r o -pene. A gas, presumed to be CO, was e v o l v e d . T h i s r e s u l t e d i n a brown-green s o l u t i o n and a w h i t e p r e c i p i t a t e . S o l v e n t THF removal from the i s o l a t e d s o l u t i o n gave a brown-green s o l i d . Attempted r e c r y s t a l l i z a t i o n from benzene gave a brown, 3 g l a s s y s o l i d which c o n t a i n e d [ H B ( E A ) ( p z ) 2 ] M o ( C 0 ) 2 ( n - C ^ H ^ ) . (c) Attempted S y n t h e s i s of [H 2B(EA) (pz)]Mo(CO) 2N0 In a procedure i d e n t i c a l to t h a t d e s c r i b e d i n s e c t i o n ( 3 - 1 4 ) , o n e - t h i r d of the above Na +[H 2B(EA)(pz)Mo(CO) ]~ s o l u t i o n was r e a c t e d w i t h excess i s o a m y l n i t r i t e (2 m l ) . A gas, presumed to be CO, was e v o l v e d . T h i s r e s u l t e d i n a - 176 -yellow-brown s o l u t i o n and a w h i t e p r e c i p i t a t e . S o l v e n t THF removal from the i s o l a t e d s o l u t i o n gave a yellow-brown s o l i d . Attempted r e c r y s t a l l i z a t i o n from benzene gave an i n t r a c t a b l e , brown s o l i d . - 177 -CHAPTER V INVESTIGATIONS OF POTENTIALLY FIVE-COORDINATE GALLIUM SYSTEMS A. R e s u l t s and D i s c u s s i o n I t i s well-known t h a t g a l l i u m a l k y l s r e a c t r e a d i l y w i t h compounds c o n t a i n i n g " a c t i v e hydrogen", e l i m i n a t i n g a l -kane to y i e l d p r o d u c t s c o n t a i n i n g f o u r - c o o r d i n a t e g a l l i u m atoms (11,34-37,74). These p r o d u c t s are o f t e n a s s o c i a t e d and f r e q u e n t l y occur as dimers. E a r l i e r i t was shown t h a t di-^ m e t h y l g a l l i u m a c e t a t e , [ M e 2 G a ( C H ^ C 0 2 ) ] 2 , was d i m e r i c i n both the gas phase and i n acetone s o l v e n t ( 7 5 ) . T h i s compound was s y n t h e s i z e d by s i m p l y r e f l u x i n g e q u imolar amounts of t r i m e t h y l g a l l i u m and a c e t i c a c i d i n benzene s o l v e n t a c c o r d i n g to the f o l l o w i n g scheme (R=Me): CfiH R„Ga + CH-COOH . » [R„Ga(CH oC0 o)] + RH (61) 3 o A z j z When methane e v o l u t i o n had ceased, s i g n a l l i n g the c o m p l e t i o n of the r e a c t i o n , the benzene s o l u t i o n was s l o w l y c o o l e d y i e l d i n g a w h i t e , c r y s t a l l i n e s o l i d w h i ch, on s o l v e n t removal, gave a f i n e , w h i t e powder. The t h r e e proposed s t r u c t u r e s f o r t h i s compound' are shown below i n F i g u r e 41. The f i r s t two s t r u c t u r e s , I and I I , were proposed e a r l i e r (75) and i n v o l v e f o u r - c o o r d i n a t e g a l l i u m atoms. I n -f r a r e d e v idence (75) su p p o r t e d the presence of b r i d g i n g a c e t a t e groups, as i n s t r u c t u r e ( I I ) . The v^, s t r e t c h i n g f r e -q u e n c i e s of compounds c o n t a i n i n g b r i d g i n g a c e t a t e s were known to be s i m i l a r t o those of i o n i c a c e t a t e s , b o t h c l a s s e s commonly - 178 --1 h a v i n g two s t r o n g a b s o r p t i o n s i n the range 1400-1480 cm and 1570-1620 cm r e s p e c t i v e l y ( 7 5 ) . D i m e t h y l g a l l i u m a c e t a t e -1 -1 has s t r o n g a b s o r p t i o n s at 1471 cm and 1534 cm i n t e t r a -c h l o r o e t h y l e n e s o l v e n t . The a l t e r n a t i v e s t r u c t u r e I i n v o l -v i n g f o u r - c o o r d i n a t e g a l l i u m atoms would r e s u l t i n a s t r o n g a b s o r p t i o n i n the 1700-1750 cm ^ r e g i o n . C r y s t a l s t r u c t u r e a n a l y s i s of s e v e r a l compounds con-t a i n i n g a c e t a t e groups, such as the r e c e n t work on M02(CH^ COg)^ ( 7 6 ) , has proven the presence of b r i d g i n g a c e t a t e groups. S t r u c t u r e I I , on the o t h e r hand, i n v o l v e s an eight-membered r i n g system. Eight-membered r i n g systems are f a i r l y s t r a i n e d ( 7 7 ) . evidence of compounds c o n t a i n i n g f i v e - c o o r d i n a t e g a l l i u m atoms has appeared (13,15,78-81), w i t h d i m e r i z a t i o n of the monomer u n i t o c c u r r i n g v i a a four-membered ^Ga-O}^ r l n g , s i m i l a r to t h a t shown i n s t r u c t u r e I I I , an a l t e r n a t e a r r a n g e -ment f o r the d i m e r i c a c e t a t e . F i g u r e 41 W i t h i n the past s e v e r a l y e a r s , c r y s t a l l o g r a p h i c Me - 179 -However, attempts to grow c r y s t a l s of t h i s compound by slow vacuum s u b l i m a t i o n which would be s u i t a b l e f o r x-ray study have so f a r f a i l e d , thus the proposed s t r u c t u r e I I I cannot be c o n f i r m e d . For t h i s r e a s o n , the d i e t h y l d e r i v a t i v e , [Et^Ga(CH^CO^)], was s y n t h e s i z e d and c h a r a c t e r i z e d i n the hope t h a t i t would p r o v i d e c r y s t a l s s u i t a b l e f o r x-ray a n a l y -s i s . Slow s u b l i m a t i o n of the r e s u l t i n g w h i t e powder gave f i n e , n e e d l e - l i k e c r y s t a l s , however, th e s e may be too s m a l l f o r a c r y s t a l s t r u c t u r e to be attempted. The i n f r a r e d spectrum of d i e t h y l g a l l i u m a c e t a t e shows a complete absence of any a b s o r p t i o n s i n the 1700-1750 cm ^ r e g i o n , i n d i c a t i n g t h a t a l l the CO groups i n the m o l e c u l e are i n v o l v e d i n b r i d g i n g . A l s o , t h e r e i s a s t r o n g a b s o r p t i o n at 1530 cm ^ as i s common i n m o l e c u l e s w i t h b r i d g i n g a c e t a t e groups, however, the a b s o r p t i o n i n the 1400-1470 cm ^ range i s obscured by the broad N u j o l peak c e n t e r e d at 1465 cm \ A s h o u l d e r at 1420 cm i s p r e s e n t on t h i s broad N u j o l peak. The a n a l y t i c a l data f o r both a c e t a t e compounds are g i v e n i n Table X V I I I . The mass spectrum of [Me^Ga(CH^CO^)]^ shows i t s s t r o n g e s t s i g n a l c o r r e s p o n d i n g to the monomer u n i t minus a methyl group [MeGa(CH^C0 2)] +• By comparison, the peak c o r r e -sponding to the monomer u n i t , [Me^Ga(CH^CO,^)] +, i s much weaker (<2%) w h i l e that of the dimer u n i t i s b a r e l y d i s c e r n a b l e . The absence or low i n t e n s i t y of p a r e n t s i g n a l s has p r e v i o u s l y been shown to be q u i t e common i n t h i s type of o r g a n o - g a l l i u m com-p o u n d ^ ) . Another f a i r l y s t r o n g s i g n a l i s found at [ P a 0 9 ] + , - 180 -a l o n g w i t h s i g n a l s of weaker i n t e n s i t i e s c o r r e s p o n d i n g to [ ( M e ) 4 G a 2 ( C H 3 C 0 2 ) ] + , [ ( M e ) 3 G a 2 ( C H 3 C 0 2 ) ] + , [ G a ( C H 3 C 0 2 ) ] + , [ G a C 2 0 2 ] + , G a + , and [CH 3C00H] +. The r e l a t i v e i n t e n s i t y p a t t e r n s f o l l o w e d t h a t p r e d i c t e d from the number of g a l l i u m atoms i n each i o n fragment (see F i g u r e 28). The mass spectrum of [ E t 2 G a ( C H 3 C 0 2 ) ] shows i t s s t r o n g e s t peak at [ E t G a ( C H 3 C 0 2 ) ] + , c o r r e s p o n d i n g t o the mono-mer u n i t minus an e t h y l group. As w i t h the methyl d e r i v a t i v e , the peak c o r r e s p o n d i n g to the monomer u n i t i s much weaker (^8%). There i s a l s o e v i d e n c e i n the spectrum of v e r y weak peaks c o r r e s p o n d i n g to the d i m e r i c and t r i m e r i c u n i t s , as h i g h e r mass peaks w i t h the Ga 3 g r o u p i n g were d e t e c t e d i n the spectrum (see F i g u r e 28). Other peaks of weak i n t e n s i t y i n -c l u d e d [ E t 3 G a 2 ( C H 3 C 0 2 ) ] + , [ E t 2 G a ] + , [ G a ( C H 3 C 0 2 ) ] + , [ E t G a ( 0 H ) ] + , G a + and [CH 3C00H] +. The "^H n.m.r. data f o r these two compounds i n C,D, b o are g i v e n i n Table X I X ( a ) . From the m o l e c u l a r s t r u c t u r e of the methyl d e r i v a t i v e , [ M e ^ G a ( C H 3 C 0 2 ) ] 2 (see F i g u r e 4 1 ) , we would expect two p r o t o n r e s o n a n c e s , the g a l l i u m methyl p r o t o n s and the a c e t a t e methyl p r o t o n s i n a 2:1 i n t e n s i t y r a t i o . T h i s i s indeed observed. The 1H n.m.r. data f o r [ E t 2 G a ( C H 3 C 0 2 ) ] i s a g a i n c o n s i s t e n t w i t h the same type of s t r u c t u r e shown i n f i g u r e 41, o n l y i n t h i s case we ••.have e t h y l groups i n s t e a d of m e t h y l groups bonded to the g a l l i u m atom. The t h r e e p r o t o n s i g n a l s o bserved; Ga-C-CH 3, Ga-CH 2~C, and a c e t a t e methyl p r o t o n s were observed i n the expected 6:4:3 i n t e n s i t y r a t i o . In a d d i t i o n , - 181 -the s p i n - s p i n c o u p l i n g of the m e t h y l and methylene p r o t o n s of the e t h y l group bound to g a l l i u m i s a l s o observed. The methylene p r o t o n s d i s p l a y the expected q u a r t e t w h i l e the methyl p r o t o n s d i s p l a y a t r i p l e t p a t t e r n . The p a t t e r n observed f o r the Ga-Et group i s t y p i c a l and d i s p l a y s the expected " i n -v e r t e d e t h y l s i g n a l s " w i t h the s i g n a l a r i s i n g from the methy-lene p r o t o n s at a h i g h e r f i e l d than f o r the methyl p r o t o n s (82)'. The attempted s y n t h e s i s of the analogous [H^GaCCH^ C 0 2 ) ] 2 dimer from Me^NGaH^ and CR^COOH r e s u l t e d i n a w h i t e s o l i d p r o d u c t . As w i t h most g a l l i u m h y d r i d e s , c h a r a c t e r i z a t i o n proved d i f f i c u l t , as these compounds tend to decompose at room temperature. The r e a c t i o n of another a c t i v e hydrogen compound c o n t a i n i n g a c a r b o x y l i c group, L - p r o l i n e , C.H oNC0„H, w i t h t r i -H o z m e t h y l - or t r i e t h y l g a l l i u m was a l s o i n v e s t i g a t e d . The L-p r o l i n a t o d i a l k y l g a l l i u m compounds, [R„Ga(C.H NC0 o)](R=Me,Et), z 4 o z were s y n t h e s i z e d by s i m p l y r e f l u x i n g e q uimolar amounts of L-p r o l i n e w i t h t r i m e t h y l g a l l i u m or t r i e t h y l g a l l i u m i n benzene s o l v e n t u n t i l the e v o l u t i o n of a l k a n e had ceased. C H R 3Ga + C 4H gNC0 2H ft 6 », [R^a(C 4H gNC0 2) ] + RH (62) (where R=Me,Et) The r e s u l t i n g benzene s o l u t i o n s were s l o w l y c o o l e d to room temperature y i e l d i n g l a r g e , c o l o r l e s s c r y s t a l s of the d e s i r e d p r o d u c t s , [R^aXC^H NC0 2 ) ] , whose monomeric u n i t i s d e p i c t e d i n F i g u r e 42. - 182 -F i g u r e 42-The c r y s t a l s t r u c t u r e of one of the p r o d u c t s , L-p r o l i n a t o - d i m e t h y l g a l l i u m (R=Me) has been determined ( 8 3 ) . F i g u r e 43(a) shows a g e n e r a l view of the unique p a r t of the s t r u c t u r e w i t h the c r y s t a l l o g r a p h i c numbering scheme and f i g u r e 43(b) shows the c r y s t a l s t r u c t u r e viewed down the c r y s t a l l o -g r a p h i c c a x i s . The c r y s t a l s t r u c t u r e of L - p r o l i n a t o d i m e t h y l g a l l i u m ( F i g u r e 4 3 ( b ) ) f e a t u r e s an un u s u a l c h a i n - l i k e a s s o c i a t i o n of monomer u n i t s e x t e n d i n g a l o n g the b a x i s . Each m o l e c u l a r u n i t i s l i n k e d to two o t h e r s ( r e l a t e d by the screw a x i s p a r a l l e l t o b) by two weak Ga-0 bonds (2.695(3)A) and two N-H ...0(1) hydrogen bonds (N...0=2.901(4),H...0=2.27(5)A, N-H...0=137(4)°) to form a l i n e a r polymer which c o n t a i n s f i v e - c o o r d i n a t e g a l l i u m atoms. Non-bonded d i s t a n c e s between the p a r a l l e l c h a i n s c o r r e -spond to normal Van der Waals i n t e r a c t i o n s . . Other f i v e - c o o r d i -nate g a l l i u m s p e c i e s c o n s i s t of d i s c r e t e m o l e c u l a r u n i t s ; f o u r of which are b i n u c l e a r (13,15,79), w h i l e one i s p o l y n u c l e a r (78) and one i s mononuclear (80,81). The Ga-0(1) and Ga-C bond l e n g t h s are c o n s i s t e n t - 183 -w i t h c o r r e s p o n d i n g d i s t a n c e s i n the o t h e r f i v e - c o o r d i n a t e g a l l i u m s t r u c t u r e s ( a l l of which have t r i g o n a l b i p y r a m i d a l c o o r d i n a t i o n geometry). The e q u a t o r i a l Ga-N bond (2.035(3)A) i s l o n g e r than those i n c 2 4 H 7 2 G a 8 N 1 2 ° 2 ( 7 7 ) ( 1 • 9 4 9 ( 3 ) a n d I - 9 9 9 (3)1) and the a x i a l Ga-0(2)' d i s t a n c e (2.695(3 )1) i s the l o n g e s t Ga-0 bond y e t d i s c o v e r e d . In most of the oth e r f i v e -c o o r d i n a t e g a l l i u m s t r u c t u r e s s t u d i e d one of the a x i a l bonds i s r e l a t i v e l y l o n g , f o r example: Ga-0=2.469(3)A i n the s a l i -c y l a l d e h y d a t o g a l l i u m dimer (79) and Ga-N=2.779(3)1 i n the p o l y c y c l i c cage compound C„.H Ga QN 0 ( 7 7 ) . The c o n f o r m a t i o n of the c h e l a t e r i n g i s q u a l i t a t i v e l y e q u i v a l e n t to t h a t i n the r e l a t e d m o l e c u l e L - p r o l i n a t o - d i p h e n y l boron ( 8 4 ) , the mean d e v i a t i o n between c o r r e s p o n d i n g t o r s i o n a n g l e s b e i n g 3.3°. The s t e r i c and e l e c t r o n i c d i f f e r e n c e s be-tween t e t r a h e d r a l boron and t r i g o n a l b i p y r a m i d a l g a l l i u m com-p l e x e s l e a d to s m a l l , but p o s s i b l y s i g n i f i c a n t , g e o m e t r i c a l d i f f e r e n c e s i n the L - p r o l i n e m o i e t i e s . The C ( l ) - 0 ( 1 ) and C ( l ) -0(2) d i s t a n c e s i n the two complexes ( 1 . 3 0 0 ( 3 ) ! and 1.219(3 )1 f o r the boron and 1.283(5) and 1.232(5 )1 f o r the g a l l i u m com-p l e x ) r e f l e c t the r e l a t i v e weakness of the a x i a l Ga-0(1) bond w i t h r e s p e c t to the B-0(1) bond as w e l l as the e f f e c t of weak c o o r d i n a t i o n of the c a r b o n y l oxgyen atom, 0 ( 2 ) , to the g a l l i u m atom. The a n a l y t i c a l data f o r the two [R nGa(C.H oNC0 o)] A 4 8 2 (R=Me,Et) compounds i s g i v e n i n Table X V I I I . The i n f r a r e d ' s p e c t r a of these two complexes i n N u j o l show symmetric and asymmetric vGa-C s t r e t c h i n g v i b r a t i o n s i n - 184 -F i g u r e 43 (a) A S t e r e o v i e w of [Me Ga(C.H NCO )] (b) C r y s t a l S t r u c t u r e of [Me„Ga(C.H oNC0 o)] viewed down _c. F i n e l i n e s r e p r e s e n t hydrogen bonds. - 185 -the 500-600 cm r e g i o n of the spectrum. In the d i m e t h y l -g a l l i u m compound these occur at 546 and 597 cm . . r e s p e c t i v e l y , and i n the d i e t h y l g a l l i u m compound they are s h i f t e d to 516 and 563 cm ^, r e s p e c t i v e l y . The v s t r e t c h i n g f r e q u e n c y expected at 1700-1750 cm ^ f o r the c a r b o n y l group i n the monomeric u n i t shown i n f i g u r e 42 i s absent i n the i n f r a r e d . spectrum of both compounds. I n s t e a d , an i n t e n s e , broad band at lower energy which was p r e v i o u s l y a s s i g n e d to the v s t r e t c h i n g f r e q u e n c y of a b r i d g e d c a r b o n y l group i n r e l a t e d compounds (7) i s obs e r v e d . I t i s c e n t r e d at 1635 cm f o r the d i m e t h y l g a l l i u m compound and at 1600 cm' f o r the d i e t h y l g a l l i u m compound. The a s s o c i a t e d v s t r e t c h i n g f r e q u e n c y n o r m a l l y found between 1400-1480 cm ^ i n these compounds i s obscured by the broad N u j o l peak c e n t r e d at 1465 cm ^. These r e s u l t s are e n t i r e l y i n agreement w i t h the c r y s t a l s t r u c t u r e r e s u l t , the p o l y m e r i z a t i o n of the monomeric u n i t through a Ga-O-C b r i d g e . In a d d i t i o n , the vN-H s t r e t c h i n g f r e q u e n c i e s f o r the two compounds are a l s o at f a i r l y low e n e r g i e s ; 3190 cm ^ f o r the d i m e t h y l g a l l i u m d e r i v a t i v e and 3130 cm ^ f o r the d i e t h y l g a l l i u m d e r i v a t i v e . T h i s r e f l e c t s the c o n s i d e r a b l e amount of i n t e r m o l e c u l a r hydrogen bonding which was found between the monomeric u n i t s i n the c r y s t a l s t r u c t u r e . The s t r o n g e s t s i g n a l s i n the mass s p e c t r a of the two L - p r o l i n a t o d i a l k y l g a l l i u m compounds were due to the paren t i o n minus one a l k y l group. No s i g n a l s w i t h h i g h e r mass than - 186 -the p a r e n t monomer were observed. In view of the weak a s s o c i a -t i o n of the monomer u n i t s i n the s o l i d ( f o r the methyl d e r i v a -t i v e ) the monomeric c o n s t i t u t i o n i n the gas phase i s not sur-^ p r i s i n g . S a l i c y l a l d e h y d a t o d i m e t h y l g a l l i u m was found to be monomeric i n the gas phase but i n the s o l i d d i m e r i z e s through the f o r m a t i o n of two weak Ga-Q bonds (7 9 ) . The p a r e n t monomer was o n l y observed f o r the d i e t h y l g a l l i u m d e r i v a t i v e , and then o n l y about 2% of the i n t e n s i t y of the s t r o n g e s t peak i n the spectrum. A g a i n , t h i s i s c o n s i s t e n t w i t h the f a c t t h a t the absence or low i n t e n s i t y of the p a r e n t i o n s i g n a l s i s common i n t h i s type of o r g a n o g a l l i u m compound (34). Other s t r o n g s i g n a l s i n the mass spectrum were due to [R Ga(C.H N ) ] + , z 4 o + + + + [RGa(C.H DN)] , [ R„ Ga] , Ga and [ C . H N ] i o n s . The r e l a t i v e H O z H O i n t e n s i t i e s of the peaks i n the d o u b l e t s i g n a l s of g a l l i u m c o n t a i n i n g i o n s agreed w e l l w i t h those p r e d i c t e d from the i s o t o p i c d i s t r i b u t i o n of the m e t a l atoms (see f i g u r e 28). The "^H n.m.r. data f o r the two complexes i s g i v e n i n Table XIX. The s p e c t r a of the two complexes i n CDCl^ s o l u t i o n showed s i m i l a r p a t t e r n s w i t h the a l k y l groups on g a l l i u m at h i g h f i e l d and s i x broad s i g n a l s due to the p r o t o n s of the L-p r o l i n a t o moiety at lower f i e l d . The spectrum of L - p r o l i n a t o -d i m e t h y l g a l l i u m d i s p l a y e d the Ga-Me resonance as a sharp s i n g l e t at x=10.48, w h i l e the L - p r o l i n a t o d i e t h y l g a l l i u m spectrum d i s p l a y e d a sharp t r i p l e t - q u a r t e t p a t t e r n c e n t r e d at 9.17 and 9.76x r e s p e c t i v e l y (see F i g u r e 44). These o b s e r v a t i o n s are somewhat s u r p r i s i n g c o n s i d e r i n g the d i f f e r e n t environments - 187 -of the two methyl groups on g a l l i u m t h a t were found i n the s o l i d s t a t e s t r u c t u r e of L - p r o l i n a t o d i m e t h y l g a l l i u m . E v i -d e n t l y , a r a p i d r i n g f l i p p i n g of the m o l e c u l e i n s o l u t i o n to g i v e e q u i v a l e n c e to the two m e t h y l groups (or e t h y l groups) i s t a k i n g p l a c e on the n.m.r. time s c a l e . Of the s i x broad s i g n a l s due to the pr o t o n s on the L - p r o l i n a t o m o i e t y , o n l y the pr o t o n s H . (see diagram, Table XIX) o c c u r r e d as a p a r t i a l l y r e s o l v e d m u l t i p l e t , w h i l e H, , H and H. remained as br o a d , low b e d i n t e n s i t y bumps i n the spectrum. F i n a l l y , the r e a c t i o n of the [ H ^ G a ^ z ) ^ dimer w i t h two molar e q u i v a l e n t s of p y r a z o l e caused a w h i t e s o l i d to p r e c i p i t a t e from the benzene s o l v e n t . C h a r a c t e r i z a t i o n of t h i s s o l i d l e d to the most l i k e l y m o l e c u l a r f o r m u l a [ G a ( p z ) 3 ] , i n which the g a l l i u m atom may be s i x - c o o r d i n a t e i n a c r o s s - l i n k e d polymer. F i g u r e 44 100 MHz F.T. 1H N.M.R. of [ Et 2Ga (C^HgNC^) ] i n CDC1 3 S o l v e n t - 189 -Table X V I I I A n a l y t i c a l Data f o r F i v e - C o o r d i n a t e G a l l i u m Compounds Compound Ana l y s i s C Found % H N C a l c . % C H N [Me 2Ga(CH 3C0 2) ] 2. 30 .48 5 . 90 3 0.25 5.67 -.[Et 2Ga(CH 3C0. 2) ] 2 38 .21 7 . 14 - 38 .56 7 . 01 -[Me 2Ga(C 4H gNC0 2 )] 39 . 65 6 . 80 6 .37 39 . 31 6 . 60 6.55 [ E t 2 G a ( C 4 H g N C 0 2 )] 44 . 66 7 . 58 5 . 88 4 4.67 7 . 50 5.79 - 190 -Tab l e XIX "*"H N.M.R. Data f o r F i v e - C o o r d i n a t e G a l l i u m Compounds (a) [R ?Ga(CH^C0 ?)] (R=Me,Et) Compounds i n C cD t S o l v e n t Compound T P P M [Me 2Ga(CH 3C0 2)] [Et,Ga(CH 3C0 2] A c e t a t e methyl 8.39 s (1) 8.73 s (3) -Ga-CH 2-C - 9.64 q (4) -Ga-C-CH 3 10.07 s (2) 9.18 t (6) - 191 -Table XIX (cont'd) (b) [ R 2 G a ( C 4 H g N C 0 2 ) ] (R=Me,Et) Compounds i n CDC1 S o l v e n t . c H — C N*-H d Compound TPPM . [Me 2.Ga(C 4H gNC0 2) ] [ E t 2 G a ( C 4 H g N C 0 2 ) ] Ga-Ga-H -. H a a 7.95 8.36 m (4) m 7 .93 8.39 m m (4) H b 7 .38 6.95 lV (2) b r . 7. 38 6 . 95 br br (2) H c 6 . 14 br (1) 6.14 br (1) H d 3 . 84 br (1) 3.78 br (1) CH 2-C - - 9 . 76 q (4) C-CH 3 10.4 8 s (6) 9.17 t (6) T(TMS) = 1Q.Q0Q ppm, T ( 'C &D g')=2.84 ppm, T ( ' C D C I ' )=2.84 p R e l a t i v e i n t e n s i t i e s of s i g n a l s g i v e n i n p a r e n t h e s i s , s - s i n g l e t , d=doublet, t = t r i p l e t , q = quartet, m = m u l t i p l e t br=broad. - 192 -B. S y n t h e t i c D e t a i l s 5-1. Attempted S y n t h e s i s of [ H^Ga(CH C 0 2 ) ] C,H Me 3NGaH 3 + CH3COOH • Tl^Ga ( C H 3 C 0 2 ) ] + ^ 2 + Me 3N (63) Me 3NGaH 3 (0.501 grams, 3.80 mmoles) and a c e t i c a c i d (0.232 grams, 3.86 mmoles) were both d i s s o l v e d i n benzene and r e a c t e d i n an evacuated t i p p e r tube ap p a r a t u s at room tem-p e r a t u r e . A gas, presumed to be hydrogen, was e v o l v e d ( c a l -c u l a t e d 85.2 ml, found 84.7 m l ) . T h i s r e s u l t e d i n a c l e a r , c o l o r l e s s s o l u t i o n . S o l v e n t benzene removal gave a c o l o r l e s s o i l a l o n g w i t h a s m a l l amount of w h i t e s o l i d . C h a r a c t e r i z a -t i o n was d i f f i c u l t as the p r o d u c t was a i r - s e n s i t i v e and de-composed at room tem p e r a t u r e . The w h i t e s o l i d a n a l y s e d as [ H G a ( C H 3 C 0 2 ) 2 ] ( c a l c u l a t e d C:25.45, H:3.74, Ga:36.93, found C:27.31, H:5.86, Ga:37.38). The mass spectrum showed v e r y weak peaks c o r r e s p o n d i n g to the [H^Ga(CH 3C0 2)] i o n . An i . r . s o l u t i o n spectrum i n benzene showed a vGa-H at 1905 cm (m) and a vH-Ga-H d e f o r m a t i o n mode at 745 cm " ' " ( l ) . 5-2. S y n t h e s i s of [R^Ga(CH 3C0 2)] (R=Me,Et) The procedure i s i d e n t i c a l f o r e i t h e r compound and may be i l l u s t r a t e d by d e s c r i b i n g the s y n t h e s i s of the e t h y l d e r i v a t i v e . An ampoule c o n t a i n i n g E t 3 G a ( 2 . 3 6 5 grams, 15.07 mmoles) - 193 -was broken open and i t s c o n t e n t s were added to a s i n g l e -necked f l a s k . The Et^Ga was then d i s s o l v e d i n a s m a l l amount of benzene. A weighed q u a n t i t y of a c e t i c a c i d (0.905 grams, 15.07 mmoles) was d i s s o l v e d i n benzene and the r e s u l t i n g s o l u -t i o n was added dropwise to the f l a s k c o n t a i n i n g the Et^Ga. Ethane e v o l u t i o n was slow at room t e m p e r a t u r e , so the r e a c t i o n m i x t u r e was r e f l u x e d f o r 20 hours ( e q u a t i o n 61, R=Et). Slow c o o l i n g of the r e s u l t i n g s o l u t i o n gave s m a l l , c o l o r l e s s c r y s t a l s . The benzene s o l v e n t was decanted from the c r y s t a l s , which were l e f t to dry i n the glovebox. T h i s r e s u l t e d i n a w h i t e powder. T h i s powder was sublimed i n an evacuated am-poule at 120°C f o r s e v e r a l days, r e s u l t i n g i n f i n e , n e e d l e -l i k e c r y s t a l s . 5-3. S y n t h e s i s of [ R 2 G a ( C 4 H g N C 0 2 ) ] (R=Me,Et) An ampoule c o n t a i n i n g Me.jGa(1.657 grams, 14.43 mmoles) was broken open and i t s c o n t e n t s were added to a s i n g l e -necked f l a s k . The Me^Ga was the d i s s o l v e d i n a s m a l l amount of benzene s o l v e n t . A weighed q u a n t i t y of L - p r o l i n e (1.610 grams, 14.00 mmoles) was q u a n t i t a t i v e l y t r a n s f e r r e d to the f l a s k c o n t a i n i n g the Me^Ga s o l u t i o n . V i g o r o u s methane e v o l u -t i o n o c c u r r e d at room temperature and the r e a c t i o n was s t i r r e d f o r 15 h o u r s . At the end of t h i s p e r i o d , an i c y - l o o k i n g cake had formed on the i n s i d e w a l l of the f l a s k , so the r e a c t i o n was r e f l u x e d f o r 4 hours r e s u l t i n g i n a c l e a r , c o l o r l e s s benzene s o l u t i o n ( e q u a t i o n 62, R=Me). Slow c o o l i n g of the r e s u l t i n g s o l u t i o n gave l a r g e , c o l o r l e s s c r y s t a l s of [Me ?Ga (C, H QNC0 o) ] .' - 194 -t These c r y s t a l s were c o l l e c t e d and d r i e d . S i m i l a r l y , Et^Ga (2.541 grams, 16.19 mmoles) was r e f l u x e d f o r 15 hours w i t h L - p r o l i n e (1.864 grams, 16.19 mmoles) i n benzene s o l v e n t . A gas, presumed to be ethane, was e v o l v e d ( e q u a t i o n 62, R=Et). T h i s r e s u l t e d i n a c l e a r , c o l o r l e s s s o l u t i o n . Slow c o o l i n g of t h i s s o l u t i o n gave l a r g e , c o l o r l e s s c r y s t a l s of [Et^Ga(C^HgNCO,.,)]. These c r y s t a l s were c o l l e c t e d and d r i e d . 5-4. R e a c t i o n of [ H 2 G a ( p z ) ] 2 w i t h P y r a z o l e C 6 H 6 [ H 2 G a ( p z ) ] 2 + 2Hpz — — [ HGa (pz ) 2 ] 2 + 2H 2 (64) In a procedure i d e n t i c a l to t h a t d e s c r i b e d i n s e c t i o n ( 5 - 1 ) , [ H 2 G a ( p z ) ] 2 (0.197 grams, 0.710 mmoles) was r e a c t e d w i t h p y r a z o l e (0.0945 grams, 1.390 mmoles) i n benzene s o l v e n t . A gas, presumed to be hydrogen, was v i g o r o u s l y e v o l v e d at room temperature ( c a l c u l a t e d 31.1 ml, found 31.8 ml) and a w h i t e s o l i d p r e c i p i t a t e d from s o l u t i o n . T h i s s o l i d was i s o l a t e d and vacuum d r i e d at 25°C f o r one hour. An i . r . spectrum of t h i s s o l i d i n N u j o l showed the t o t a l absence of any b a n d - i n the vGa-H s t r e t c h i n g r e g i o n around 1900 cm . The o n l y i d e n t i f i -a b l e peak i n the mass spectrum was due to p y r a z o l e . The com-pound a n a l y s e d as [Ga(pz) ] q . A n a l y t i c a l f o r G a ( N 2 C 3 H 3 ) 3 ( c a l c u l a t e d C:39.90, H:3.35, N:31.02, Ga:25.73, found C:38.16, H:3.42, N:28.40, Ga:25.26). - 195 -CHAPTER VI SUMMARY AND SUGGESTIONS FOR FUTURE WORK I t i s n a t u r a l to compare 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 [H^BCpz)^^] (n=0,l,2) and t h e i r c o o r d i n a t i o n com-pounds, p r e v i o u s l y s y n t h e s i z e d and c h a r a c t e r i z e d by T r o f i -menko, w i t h the analogous g a l l i u m systems based on the [ M e ^ G a ( p z ) ] (n=l,2) l i g a n d s . The g a l l i u m systems have s e v e r a l advantages over the boron systems. F i r s t , g a l l i u m l i g a n d s r e q u i r e l e s s f o r c i n g c o n d i t i o n s i n t h e i r s y n t h e s i s than the c o r r e s p o n d i n g boron l i g a n d s , a p r o p e r t y which i s not s u r p r i s i n g i n l i g h t of the p r e v i o u s l y known c h e m i s t r y of the compounds of each element. S e c o n d l y , both mass s p e c t r a l arid "'"H n.m.r. a n a l y s i s of the [Me Ga ( p z ) . ] d e r i v a t i v e s are n 4-n e a s i e r to i n t e r p r e t than t h e i r boron c o u n t e r p a r t s . The mass s p e c t r a of the g a l l i u m compounds g i v e the expected i s o t o p i c p a t t e r n s c a l c u l a t e d from the n a t u r a l i s o -t o p i c abundancies of the m e t a l atoms i n each i o n fragment of the compound. The analogous boron i s o t o p i c p a t t e r n s , on the o t h e r hand, are not so w e l l d e f i n e d , due m a i n l y to the ready l o s s or g a i n of one or two p r o t o n s from the main i o n frag m e n t s , g i v i n g o v e r l a p p a t t e r n s which are d i f f i c u l t to a n a l y s e . T h i s p a r t i c u l a r d i f f i c u l t y was e v i d e n t i n the mass s p e c t r a l a n a l y s i s of compounds i n v o l v i n g the [ B.^ B (OCH^CH^NR^) (p z ) ] (R=H,Me) l i g a n d s , where the i s o t o p i c p a t t e r n s agreed p o o r l y w i t h those c a l c u l a t e d from t h e o r y . The '"*"H n.m.r. s p e c t r a of Ga-Me c o n t a i n i n g compounds - 196 -are p a r t i c u l a r l y easy to st u d y . The Ga-Me p r o t o n s i g n a l , b e i n g at h i g h f i e l d , i s f a r removed from the more r e v e a l i n g i p a r t s of the spectrum and hence does not i n t e r f e r e w i t h the study of these r e g i o n s . In a d d i t i o n , the number of Ga-Me s i g n a l s i s a good i n d i c a t i o n of the number of isomers p r e s e n t i n the [MeGaCpz)^] complexes. The attempted s y n t h e s i s of the [ H 2 B (OCH 2 CH 2NR 2 )(pz) ] 2M (R=H,Me; M=Co,Ni,Cu,Zn) complexes was u n s u c c e s s f u l and gave i n s t e a d impure s o l i d s which c o n t a i n e d the p r e v i o u s l y c h a r a c -t e r i z e d p o l y p y r a z o l y l b o r a t e complexes [ H 2 B ( p z ) 2 J 2 M and [ H B ( p z ) 3 ] 2 M (which are ve r y s t a b l e compounds), but showed l i t t l e e v i d e n c e of a m i n o a l c o h o l b e a r i n g m a t e r i a l s . C o n v e r s e l y , the analogous g a l l i u m system based on the [Me 2Ga(OCH 2CH 2NR 2)(pz)] (R=H,Me) l i g a n d gave more e a s i l y c h a r a c t e r i z e d , c r y s t a l l i n e p r o d u c t s c o n t a i n i n g the expected mixed l i g a n d (46,47). The [MeGa(pz)^] l i g a n d was found to possess a co o r -d i n a t i v e a b i l i t y w i t h d i v a l e n t t r a n s i t i o n m etals which p a r a l l e l l e d t h a t of the analogous boron l i g a n d [ H B ( p z ) 3 ] . The c r y s t a l s t r u c t u r e of [MeGa (p z ) ^  ] ,>N i i s p r e s e n t l y i n p r o g r e s s and s h o u l d c o n f i r m the p s e u d o - o c t a h e d r a l arrangement of the s i x l i g a t i n g n i t r o g e n atoms around the n i c k e l atom. The 3 c r y s t a l s t r u c t u r e of the [MeGa(pz)^]Mo(CO) 2(n -C^H,.) complex c o n f i r m e d t h a t the [MeGa(pz)^] l i g a n d was more s t e r i c a l l y demanding than the boron l i g a n d s due m a i n l y to the l o n g e r Ga-N bond d i s t a n c e compared to the B-N d i s t a n c e . T h i s f o r c e s the 3-H p r o t o n s on each p y r a z o l y l r i n g i n t o c l o s e r p r o x i m i t y - 197 -to the c e n t r a l t r a n s i t i o n m e tal atom which i n c r e a s e s s t e r i c crowding around t h i s atom. The '[MeG'a (pz).^ ] l i g a n d a l s o g i v e s a more e l e c t r o n r i c h t r a n s i t i o n m e tal c e n t r e which may r e s u l t from an i n c r e a s e i n a-donor s t r e n g t h of the g a l l i u m l i g a n d over the boron l i g a n d . I n f r a r e d e v i d e n c e i n d i c a t e d t h a t the s u b s t i t u t i o n of one or two methyl groups onto each p y r a z o l y l r i n g i n the [MeGaCpz)^] l i g a n d to g i v e [MeGa(mpz)^] or [MeGa(dmpz)^] I n c r e a s e d the a-donor s t r e n g t h of the l i g a n d even f u r t h e r , as e x p e c t e d . Much work remains to be done w i t h the [MeGaCpz)^] l i g a n d and i t s p y r a z o l e s u b s t i t u t e d d e r i v a t i v e s , as no com-p l e x e s w i t h the e a r l i e r t r a n s i t i o n m e t a l elements have been i s o l a t e d . Another u s e f u l p r o j e c t would be a v a r i a b l e tem-1 3 p e r a t u r e H n.m.r. study on the [MeGa(pz)^]Mo(CO)^(n - C 3 H 4 R ) (R=H,Me) complexes. The p y r a z o l y l p r o t o n s i n these complexes were found to be w e l l r e s o l v e d at room t e m p e r a t u r e , b e i n g i n a 2:1 r a t i o , whereas the p y r a z o l y l p r o t o n s i n the c o r r e s p o n d i n g 3 bor on complex [HB(pz ) 2]Mo(CO ) 2 ( 1 1 — ^3^5^ were a l l found to be e q u i v a l e n t u n t i l -45°C (52 ) . I t would be i n t e r e s t i n g to see i f the [MeGa(pz)j] moiety r o t a t e s about the Mo...Ga a x i s at 3 h i g h e r t e m p e r a t u r e s . The c r y s t a l s t r u c t u r e of the n -C^H,. 1 3 d e r i v a t i v e and H n.m.r. e v i d e n c e of both "n - a l l y l " d e r i v a t i v e s 3 i n d i c a t e s t h a t the "n - a l l y l " groups are s t a t i c and p o i n t between two of the p y r a z o l y l groups, thus r o t a t i o n of the 3 [MeGa(pz)^] moiety i n the n ~ e 4 H 7 d e r i v a t i v e s h o u l d even be 3 more r e s t r i c t e d than i n the n " C 3 H 5 d e r i v a t i v e . I t seems odd - 198 -3 then t h a t s i g n a l s due to the p y r a z o l y l p r o t o n s of the ri .-C^H^ complex are not as w e l l r e s o l v e d as those i n :the c o r r e s p o n d i n g 3 1 D -C^H^ complex. A v a r i a b l e temperature .H n.m.r. study might h e l p e x p l a i n t h i s o b s e r v a t i o n a l s o . An i n t e r e s t i n g p r o j e c t c u r r e n t l y i n p r o g r e s s i s the c r y s t a l s t r u c t u r e of the orange c r y s t a l s o b t a i n e d from the r e a c t i o n of Md^CCH^CO^)^ w i t h two e q u i v a l e n t s of the [MeGaCpz)^] l i g a n d . C h a r a c t e r i z a t i o n of these c r y s t a l s by the u s u a l methods gave inconclusive r e s u l t s , but p r e l i m i n a r y c r y s t a l s t r u c t u r e work l o o k s very p r o m i s i n g . The [MeGa(dmpz)^] l i g a n d gave some anomalous r e s u l t s i n i t s r e a c t i o n s . The b i s l i g a n d t r a n s i t i o n m e t a l complexes d i d not form due to the gr e a t s t e r i c crowding caused by s i x methy l groups around the t r a n s i t i o n m e t a l . T h i s s t e r i c crow-d i n g was a l s o r e f l e c t e d i n the attempted s y n t h e s i s of the 3 [MeGa(dmpz) 3]M(CO) 2(n -C 3H R)(R=H,Me) complexes, where the on l y p r o d u c t s i s o l a t e d were the hydroxy d e r i v a t i v e s [MeGa(dmpz) 2(OH)]M(CO) 2(n 3-C 3H 4R) (M=Mo,R=H,Me; M=W, R=Me). In t h i s case, s t e r i c crowding around the t r a n s i t i o n m e t a l atom i s r e l i e v e d by the replacement of one 3 , 5 - d i m e t h y l p y r a z o l y l moiety by a h y d r o x y l group. The c r y s t a l s t r u c t u r e of the 3 [MeGa (dmpz) 2 (OH) ]Mo ( C 0 ) 2 (n -C^H ) complex showed t h a t even i n t h i s m o l e c u l e , one of the two r e m a i n i n g 3 , 5 - d i m e t h y l p y r a z o l y l m o i e t i e s i s s e v e r e l y d i s t o r t e d due to the s t e r i c demands of the new l i g a n d [MeGa(dmpz) (OH)] . T h i s type of complex has not been found w i t h any of 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 , - 199 -i n c l u d i n g [HBCdmpz)^] . A l s o , i t would be i n t e r e s t i n g to i n -v e s t i g a t e the o r i g i n of the 'OH' group i n these m o l e c u l e s , as the THF s o l v e n t was d r i e d p r i o r to use. 1 In the H n.m.r. of the [MeGa(dmpz) 2(OH)]Mo(CO) 3 (n -C.H ) complex i n C D , t h e r e are some anomalous s p l i t t i n g s 4 / 6 6 3 of the syn p r o t o n s of the n -C^H^ group. These are too l a r g e to be a t t r i b u t e d to geminal s p l i t t i n g s , and t h e i r o r i g i n i s as yet a mystery. In o r d e r to f u r t h e r study the t r a n s i t i o n m e t a l com-p l e x e s of the [MeGa (mp z) .j ] l i g a n d , a method of s e p a r a t i n g the v a r i o u s i s o m e r i c p r o d u c t s must be d eveloped. Trofimenko had p r e v i o u s l y p u r i f i e d s e v e r a 1 [ H B ( p z ) 3 ] M ( C O ) 2 ( r i 3 - C 3 H 4 R ) (M=Cr ,Mo, W; R=H,Me) and [HB(pz) ]M(CO) 2N0 d e r i v a t i v e s (27,31) by column chromatography on alumina u s i n g d i c h l o r o m e t h a n e as an e l u e n t . Whether t h i s i s p r a c t i c a l f o r the c o r r e s p o n d i n g [MeGa(mpz)^] d e r i v a t i v e s has yet to be e x p l o r e d . I t would be i n t e r e s t i n g to see the r e l a t i v e q u a n t i t i e s of the p o s s i b l e isomers p r e s e n t . Compounds which c o n t a i n f i v e - c o o r d i n a t e g a l l i u m atoms are now well-documented. In a l l c a s e s , the g a l l i u m atom was found to have t r i g o n a l b i p y r a m i d a l c o o r d i n a t i o n geometry. Another example of t h i s was p r o v i d e d by the c r y s t a l s t r u c t u r e of the [Me„Ga(C,H oNC0„)] polymer. 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