UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

Pyrazolyl ligands in mixed metal complexes 1986

You don't seem to have a PDF reader installed, try download the pdf

Item Metadata

Download

Media
UBC_1986_A1 O59_4.pdf
UBC_1986_A1 O59_4.pdf [ 11.26MB ]
Metadata
JSON: 1.0060464.json
JSON-LD: 1.0060464+ld.json
RDF/XML (Pretty): 1.0060464.xml
RDF/JSON: 1.0060464+rdf.json
Turtle: 1.0060464+rdf-turtle.txt
N-Triples: 1.0060464+rdf-ntriples.txt
Citation
1.0060464.ris

Full Text

PYRAZOLYL LIGANDS IN MIXED METAL COMPLEXES By EMMANUEL C. ONYIRIUKA B.S., Adams State Colorado, 1980 M.S., University of C a l i f o r n i a , 1982 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY in THE FACULTY OF GRADUATE STUDIES (Department of Chemistry) We accept t h i s thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA September 1986 © Emmanuel C. Onyiriuka, 1986 In presenting t h i s thesis i n p a r t i a l f u l f i l m e n t of the requirements for an advanced degree at the University of B r i t i s h Columbia, I agree that the Library s h a l l make i t f r e e l y available for reference and study. I further agree that permission for extensive copying of t h i s thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. I t i s understood that copying or publication of t h i s thesis for f i n a n c i a l gain s h a l l not be allowed without my written permission. Department of tfE.Ml _T /&~ Y The University of B r i t i s h Columbia 1956 Main Mall Vancouver, Canada V6T 1Y3 Date Sifh /ai ̂ - 1 1 - ABSTRACT The anions LMo(C0) 3 (L = MeGapz^ or MeGa(3,5-Me 2pz) 3) have been i s o l a t e d as the Na +, Et^N + or HAsPh3 s a l t s and the solution structures of the Na + s a l t s in THF have been defined by analysis of the v C Q i r spectra. Ion-pair i n t e r a c t i o n of the LMo(C0) 3 anion with Na + cation in THF solution is apparent from the spectroscopic evidence obtained. The MeGapz 3Mo(C0) 3 anion reacted with HC1 or EtBr to give the seven-coordinate [MeGapzg]- Mo(C0) 3R (R = H or Et) complexes. However, with Mel or PhCOCl complexes of the type [MeGapz 3]Mo(CO) 2(ri 2-COR) (R = Me or Ph) were obtained. The reactions of the LMo(C0) 3 ions (L = MeGapz^, HBpz 3 or Me 2Gapz(0- CH 2CH 2NMe 2)) with a variety of t r a n s i t i o n metal halide species have y i e l d e d complexes with t r a n s i t i o n metal-transition metal bonds. The X-ray c r y s t a l structures of two such complexes [MeGapz 3]Mo(C0) 3Cu(PPh 3) and [MeGapz3]Mo- (C0) 3Rh(PPh 3) 2 have been determined. The former complex provides a rare example of a 3:3:1, or capped octahedral structure, with a short (mean) Mo-Cu distance of 2.513(9)A. The l a t t e r compound displays one terminal and two bridging CO ligands and a Mo-Rh distance of 2.6066(5)A. T r a n s i t i o n metal-group 14 ( S i , Ge or Sn) element bonded complexes of the type [MeGapz3]Mo(C0)3M'Y (Y = Me3 or Ph 3, M' = Ge or Sn; Y = Me3, M' = S i ; Y = Me 2Cl, M' = Sn) have been prepared from the reaction of the MeGapz 3Mo(C0) 3 anion with the appropriate organo-group 14 c h l o r i d e . In a l l the complexes, d i r e c t Mo-M' (M' = S i , Ge or Sn) single bonds are featured. The [MeGapz 3]Mo(C0) 3SnMe 2Cl complex shows an i n t e r e s t i n g solution behaviour in which a t r a n s i t i o n from a 3:4, or piano stool structure, to a 3:3:1, or capped octahedral arrangement, i s thought to occur. The 3:3:1 structure has been demonstrated in the s o l i d state for the [MeGapz 3]Mo(C0) 3SnPh 3 compound by means of a c r y s t a l structure determination. The 'Mo-SnPh^' and the 'Mo-Cu' compounds discussed in t h i s work are the f i r s t examples of such complexes incorporating either the MeGapz3, HBpz 3 or C 5H^ ligands in which the 3:3:1 arrangement has been demonstrated unequivocally. The novel tridentate unsymmetric ligands Me2GapzO(C5H3N)CH2NMe2 (L~) and Me2GapzO(CgHgN)" (_-) have been prepared and numerous t r a n s i t i o n metal compounds containing these ligands synthesized. The compounds L M(C0)o (M a o = Mn or Re) are the f i r s t examples of t r a n s i t i o n metal carbonyl complexes in which both the fac and mer arrangements of the unsymmetric ligand about the central metal have been found to co-exist in solu t i o n . The square planar rhodium(I) complex, L_Rh(C0) has been shown to add Mel o x i d a t i v e l y , followed by f a c i l e methyl migration reaction to produce the five-coordinate Rh(III) acetyl d e r i v a t i v e , L_Rh(C0Me)I. In contrast, the reaction of L Rh(CO) with Mel, led to the six-coordinate Rh(III) oxidative addition a product, L Rh(Me)(I)C0. a - i v - TABLE OF CONTENTS Page ABSTRACT i i TABLE OF CONTENTS iv LIST OF TABLES x LIST OF FIGURES x i i LIST OF ABBREVIATIONS . xv i i ACKNOWLEDGEMENT xxi CHAPTER I INTRODUCTION 1 1.1 General Introduct ion 1 1.2 General Techniques 14 1.2.1 Handling of Reagents 14 1.2.2 Star t ing Materials 15 i ) Preparation of Trimethylgall ium Me3Ga 15 i i ) Preparation of Gallium Tr ich lo r ide , GaCl 3 . . 16 i i i ) Preparation of Methyldichiorogallane, MeGaCl2 18 i v ) Preparation of the T r i ca rbony l t r i s - (acetonitri le)molybdenum(O), (MeCN)3Mo(C0)3 20 1.3 Physical Measurements 21 CHAPTER I I THE MOLYBDENUM TRICARBONYL ANION [MeGapz3]Mo(C0)§; SYNTHESIS AND CHARACTERIZATION OF ITS Na + . E t 4 N + AND HAsPhJ SALTS, AND INVESTIGATION OF THE REACTIVITY TOWARDS ALKYL HAL IDES, PROTONATING SPECIES AND HALOGENS. 23 2.1 Introduct ion 23 2.2 Experimental 26 - V - 2.2.1 St a r t i n g Materials 26 2.2.2 Preparation of Na +LMo(C0) 3 (L = MeGapz3, MeGa(3,5-Me 2pz) 3) 26 2.2.3 Preparation of [Et 4N] +[MeGapz 3Mo(C0) 3]' 27 2.2.4 Preparation of [HAsPh 3] +[LMo(C0) 3]" (L = MeGapz3, MeGa(3,5-Me 2pz) 3) 28 2.2.5 Attempted Preparation of [MeGapz 3]Mo(C0) 3H using Acetic Acid 29 2.2.6 Preparation of [MeGapz 3]Mo(C0) 3H using HCl 30 2.2.7 Preparation of [MeGapz 3]Mo(C0) 3D 31 2.2.8 Preparation of [MeGapz 3]Mo(C0) 2(Ti 2-C0Me) 32 2.2.9 Attempted Preparation of [MeGapz 3]Mo(C0) 2- (ri2-C0Ph) 33 2.2.10 Preparation of [MeGapz 3]Mo(C0) 3Et 34 2.2.11 Attempted Preparation of [MeGapzo]Mo(CO)oX (X = Br, I) : 7 35 2.3 Results and Discussion 36 2.3.1 M+LMo(C0)5 (L = MeGapz3, MeGa(3,5-Me 2pz) 3; M+ = Na +, E t 4 N + , HAsPh 3) Salts 36 2.3.2 [MeGapz 3]Mo(C0) 3H 45 2.3.3 [MeGapz3]Mo(C0)2(ri2-C0R) (R = Me, Ph) 49 2.3.4 [MeGapz 3]Mo(C0) 3Et 56 2.3.5 The [MeGapz 3]Mo(C0) 3X (X = Br, I) Complexes 63 2.4 Summary 63 - v i - CHAPTER III TRANSITION METAL-TRANSITION METAL BONDED COMPLEXES INCORPORATING PYRAZOLYL GAL LATE/BORATE LIGANDS 66 3.1 Introduction 66 3.2 Experimental 68 3.2.1 Starting Materials 68 3.2.2 Preparation of LMo(C0) 3Rh(PPh 3) 2 (where L = [MeGapz 3], [HBpz 3] or [Me 2Gapz(0CH 2CH 2NMe 2)])... 68 3.2.3 Preparation of [MeGapz 3]Mo(C0) 3Cu(PPh 3) 69 3.2.4 Preparation of [MeGapz 3]Mo(C0) 3Cu(C0) 70 3.2.5 Preparation of [MeGapz 3]Mo(C0) 3Pt(Me)(PPh 3) 70 3.2.6 Preparation of [MeGapZo]Mo(CO)oM'Clo (M1 = Zr or Hf) . T..... 71 3.2.7 Attempted Preparation of [MeGapz 3]Mo(C0) 3Co(N0) 2 73 3.2.8 Preparation of [MeGapz 3Mo(C0) 3] 2Hg 74 3.2.9 Attempted Reaction of [MeGapz 3Mo(C0) 3] 2Hg with S n C l 2 75 3.2.10 Attempted Desulf u r i z a t i o n of H2S by [MeGapz 3]Mo(C0) 3Rh(PPh 3) 2 76 3.2.11 Attempted Preparation of [MeGapz 3]Mo(C0) 3Mn(C0) 5 77 3.3 Results and Discussion 78 3.3.1 LMo(C0) 3Rh(PPh 3) 2 (where L = [MeGapz 3], [HBpz 3], or [Me 2Gapz(0CH 2CH 2NMe 2)]) 78 3.3.2 [MeGapz 3]Mo(C0) 3Cu(PPh 3) 83 3.3.3 [MeGapz 3]Mo(C0) 3Cu(C0) 92 3.3.4 [MeGapz 3]Mo(C0) 3Pt(Me)(PPh 3) 94 3.3.5 [MeGapz 3]Mo(C0) 3M'Cl 3 (M' = Zr or Hf) 96 3.3.6 [MeGapz 3Mo(C0) 3] 2Hg 99 3.3.7 The '[MeGapz 3]Mo(C0) 3Mn(C0) 5' Complex 101 3.4 Summary 102 - v i i - CHAPTER IV TRANSITION METAL-GROUP 14 ELEMENT BONDED COMPLEXES INCORPORATING POLY(l-PYRAZOLYL)GALLATE LIGANDS 104 4.1 Introduction 104 4.2 Experimental 105 4.2.1 St a r t i n g Materials 105 4.2.2 Preparation of [MeGapz 3]Mo(CO) 3SiMe 3 105 4.2.3 Preparation of [MeGapz 3]Mo(C0) 3GeR 3 (R = Me, Ph) 106 4.2.4 Preparation of [MeGapz 3]Mo(C0) 3SnMe 3 106 4.2.5 Preparation of [MeGapz 3]Mo(C0) 3SnMe 2Cl 107 4.2.6 Preparation of [MeGapz 3]Mo(C0) 3SnPh 3 107 4.2.7 Preparation of LSnMe3 (L = [MeGapz 3] or [MeGa(3,5-Me 2pz) 3]) 108 4.2.8 Preparation of [MeGapz 3]SnMe 2Cl 109 4.3 Results and Discussion 110 4.3.1 [MeGapz 3]Mo(C0) 3SiMe 3 I l l 4.3.2 [MeGapz 3]Mo(C0) 3GeR 3 (R = Me, Ph) 115 4.3.3. [MeGapz 3]Mo(C0) 3SnR 3 (R = Me, Ph) 117 4.3.4 [MeGapz 3]Mo(C0) 3SnMe 2Cl 122 4.3.5 LSnY (L = [MeGapz 3], [MeGa(3,5-Me 2pz) 3]", Y = Me3-, L = [MeGapz 3]-, Y = Me 2Cl) 129 4.4 Summary 130 CHAPTER V TRANSITION METAL DERIVATIVES OF THE UNSYMMETRIC TRIDENTATE PYRAZOLYLGALLATE LIGANDS [Me 2Gapz'0(C 5H 3N)- CH 2NMe 2] _ AND [Me 2GapzO(C 9H 6N)] _ 131 5.1 Introduction 131 - v i i i - 5.2 Experimental 133 5.2.1 Starting Materials 133 5.2.2 Preparation of [Me 2GaO(C 5H 3N)CH 2NMe 2] 133 5.2.3 Preparation of [Me 2GaO(C 9H 6N)] 2 136 5.2.4 Preparation of the ligand Na +[Me 2GapzO(C 5H 3N)- CH 2NMe 2]" (Na +L") 138 5.2.5 Preparation of the Ligand Na +[Me 2Gapz»0(C 9H 6N)]" (Na +L") 139 5.2.6 Preparation of L aRe(C0) 3 140 5.2.7 Preparation of L aMn(C0) 3 140 5.2.8 Preparation of L gNi (NO) 141 5.2.9 Preparation of L qRe(C0) 3 141 5.2.10 Preparation of L qMn(C0) 3 142 5.2.11 Attempted Preparation of L qNi(N0) 142 5.2.12 Preparation of Mo(MeCN) 2(ri 2-C 3H 5)(C0) 2Br 143 5.2.13 Preparation of L aMo(C0) 2(ri 2-C 3H 5) 143 5.2.14 Preparation of L qMo(C0) 2(ri 3-C 3H 5) 144 5.2.15 Preparation of L aRh(C0) 144 5.2.16 Preparation of L qRh(C0) 145 5.2.17 Reaction of L aRh(C0) with Mel 145 5.2.18 Reaction of L qRh(C0) with Mel 146 5.2.19 Reaction of L*Rh(C0) (L* = L a , L q) with I 2 147 5.3. Results and Discussion 148 5.3.1 [Me 2Ga0(C 5H 3N)CH 2NMe 2] 148 - i x - 5.3.2 [Me 2GaO(C 9H 6N)] 2 154 5.3.3 L aM(C0) 3 (M = Mn; Re) 159 5.3.4 L aNi(NO) 167 5.3.5 L qM(C0) 3 (M = Mn, Re) 172 5.3.6 L*Mo(C0) 2(n 3-C 3H 5) (L* = L a; L q ) 178 5.3.7 L*Rh(CO) (L* = L f l J L ) 182 5.3.8 Reac t i v i t y of L*Rh(C0) (L* = L,? L Q ) i ) With Mel ? 188 i i ) With I 2 195 5.4 Summary 197 CHAPTER VI CONCLUSION AND PERSPECTIVES 199 BIBLIOGRAPHY 203 APPENDIX I STEREO DIAGRAMS, BOND LENGTHS AND BOND ANGLES OF SOME OF THE PREPARED DERIVATIVES 214 APPENDIX II THEORETICAL INTENSITY PATTERNS FOR MASS SPECTROMETRIC ANALYSIS 230 - X - LIST OF TABLES Table Page I v C Q (cm - 1) Infrared data for M +LMo(C0) 3 (L = MeGapz3, MeGa(3,5-Me 2pz) 3, M+ = Na +, Et^N +, HAsPh* s a l t s ) 39 II Ir carbonyl stretching frequencies of some LMo(C0)3Me complexes (L = ^-CjjHtj, Ti-CgMe5, Tc-CgHy, HBpz 3 > MeGapz3) 51 III Physical data f o r the complexes LMo(C0)3MY 72 IV Physical data for [MeGapz3]Mo(CO)3M'Y (M* = S i , Ge, Sn) 114 V 400 MHz XH nmr data for HO(C 5H 3N)CH 2NMe 2 in C gD 6 solution 134 VI 400 MHz *H nmr data for Me 2GaO(C 5H 3N)CH 2NMe 2 in C gD g s o l u t i o n . 135 VII 400 MHz *H nmr data for H0(C gH 6N) in C gD g solution 137 VIII 400 MHz 1H nmr data for [Me 2GaO(C gH 6N)] 2 in C gD 6 solution 138 IX Mass spectral data of [Me 2GaO(C 5H 3N)CH 2NMe 2] 151 X Mass spectral data of '[Me 2GaO(CgH gN)]' 154 XI Comparison of Ga-N and Ga-0 bond lengths in four and f i v e coordinate gallium compounds 158 XII Physical data for the complexes LaMT (where L a = Me 2Gapz»0- (C 5H 3N)CH 2NMe 2) 161 XIII Mass spectral data of [Me 2GapzO(C 5H 3N)CH 2NMe 2]Mn(CO) 3 165 XIV Mass spectral data of [Me 2GapzO(C 5H 3N)CH 2NMe 2]Re(CO) 3 166 XV Comparison of v N Q values in selected four-coordinate {MNO}10 complexes 169 - xi - Table Page XVI Physical data for the complexes LqMT (where L = Meo6apz«0(CQHcN)) 174 q 2 9 b XVII Mass spectral data of [Me2Gapz«0(CgH6N)]Mn(C0)3 176 XVIII Mass spectral data of [Me 2Gapz*0(C 9H 6N)]Re(C0) 3 177 XIX Comparison of values in some LMo(C0)2(r) -C3Hg) complexes.. 178 XX Comparison of v C Q values in some LRh(CO) complexes 184 XXI Mass spectral data of [Me2Gapz«0(C9H6N)]Rh(C0) 187 XXII Mass spectral data of [Me2Gapz'0(CgH6N)]Rh(COMe)1 192 XXIII Mass spectral data of [Me2Gapz«0(CgH6N)]Rh(C0Me)I (Cont'd) 193 XXIV Comparison of v „ values in LRhI ?(C0) complexes 196 - x i i - LIST OF FIGURES Figure Page 1 Pyrazole 1 2 Deprotonation of pyrazole 2 3 Monodentate coordination of pyrazole 3 4 Coordination modes of the pyrazolide anion 3 5 Preparation of the P o l y d - p y r a z o l y l )borate ligand systems 6 6 Boat conformation of the b i s ( l - p y r a z o l y l ) b o r a t e bidentate metal complex 7 7 Preparation of Me^apz^ ligand 9 8 General representation for the unsymmetrical tridentate organogallate ligand 12 9 Apparatus for the preparation of GaCl^ 17 10 Apparatus for the preparation of MeGaCl 2 19 11 Ir spectrum of M +MeGapz 3Mo(C0) 3 s a l t s in the v C Q region. a. M+ = Na + in THF. b. M + = Na + in CH 2C1 2. c. M + = Et^N + in CH 2C1 2. d. M+ = HAsPh* in CH 2C1 2 38 12 Proposed structures for the interactions of MeGapz 3Mo(C0) 3 anion with Na + cation in THF solution, a. Unperturbed anion b. Perturbed anion 40 13 Proposed cation (Na +) i n t e r a c t i o n with MeGapz 3Mo(C0) 3 anion, external to the Mo coordination sphere in THF. a. M.O. description of CO electron density, b. Linear i n t e r a c t i o n . c. Non-linear in t e r a c t i o n 42 - x i i i - Figure Page 14 80 MHz lH spectrum of [HAsPh 3] +[MeGapz 3Mo(C0) 3_~ in dg-acetone 44 15 Ir spectra of the carbonyl stretching frequency region observed during the reaction of MeGapz 3Mo(C0) 3 with Mel 53 16 80 MHz 1H nmr spectrum of [MeGapz3]Mo(C0)2(ri2-C0Me) in dg-acetone s o l u t i o n 55 17 270 MHz *H nmr spectrum of [MeGapz 3]Mo(C0) 3Et in dg-acetone solution 60 18 Various isomers of the seven-coordinate [MeGapz 3]Mo(C0) 3Et.... 62 19 Room temperature 100 MHz *H nmr spectrum of [MeGapz 3]Mo(C0) 3Rh(PPh 3) 2 in CgDg solu t i o n 80 20 Molecular structure of [MeGapz 3]Mo(C0) 3Rh(PPh 3) 2 81 21 Proposed bonding scheme f o r [MeGapz 3]Mo(C0) 3Rh(PPh 3) 2 82 22 Possible structure of [MeGapz 3]Mo(C0) 3Cu(PPh 3) as suggested by the i r data 84 23 Molecular structures of [MeGapz 3]Mo(C0) 3Cu(PPh 3) 86 * 24 Possible i n t e r a c t i o n between the Mo-Cu % bond and the % o r b i t a l of the CO ligand i n the complex [MeGapz 3]Mo(C0) 3Cu(PPh 3) 88 25 The structure of a l i n e a r semi-bridging CO type bonding 89 26 Proposed bonding scheme f o r [MeGapz 3]Mo(C0) 3Pt(Me)(PPh 3) 95 27 80 MHz lW nmr spectrum of [MeGapz 3]Mo(C0) 3ZrCl 3 in CgDg sol u t i o n 97 28 Possible molecular arrangements f o r the [MeGapz 3]Mo(C0) 3M'Cl 3 (M' = Zr or Hf) complexes 98 - xiv - Figure Page 29 Ir spectrum of [MeGapz 3]Mo(C0) 3HfCl 3 in CH 2C1 2 solution 99 30 Possible molecular arrangement f o r the complex [MeGapz 3Mo(C0) 3] 2Hg 100 31 The VC0 ^ S ^ 0 1 1 °^ ̂ n e ^ r sP ectrum of [MeGapz 3]Mo(C0) 3SiMe 3 i n CH 2C1 2 s o l u t i o n 113 32 270 MHz lH nmr spectrum of [MeGapz 3]Mo(C0) 3GePh 3 in C gD 6 s o l u t i o n 116 33 Room temperature 80 MHz *H nmr spectrum of [MeGapz 3]- Mo(C0) 3SnMe 3 in dg-toluene 119 34 Molecular structure of [MeGapz 3]Mo(C0) 3SnPh 3 120 35 Room temperature 80 MHz *H nmr spectra of [MeGapz 3]Mo(C0) 3- SnMe 2Cl, showing the change with time 123 36 Possible molecular arrangements f o r the [MeGapz 3]Mo(C0) 3- SnMe 2Cl complex in solu t i o n 125 37 Temperature dependent 300 MHz 1H nmr spectrum of [MeGapz 3]Mo(C0) 3- SnMe 2Cl i n dg-toluene so l u t i o n 126 38 P a r t i a l mass spectrum of [MeGapz 3]Mo(C0) 3SnMe 2Cl 128 39 The unsymmetric organogallate ligands [Me 2Gapz*0(CgH 3N)- CH 2NMe 2]" (L~), and [Me^apz-OCCgHgN)] - (L~) 132 40 Molecular structure of [Me 2Ga»0(C 5H 3N)CH 2NMe 2] 149 41 Comparison of the Ga-N bond lengths i n the dimethyl gal 1ium compounds 150 42 80 MHz H nmr spectrum of H0(C(-H^N)CH?NMe? in CfiDfi s o l u t i o n . . . 152 - XV - Figure Page 43 400 MHz *H nmr spectrum of Me 2GaO(C 5H 3N)CH 2NMe 2 in C gD g solution 153 44 400 MHz *H nmr spectrum of H0(C 9H gN) in C gD g solution 155 45 80 MHz 1ti nmr spectrum of Me 2Ga0(C 9H 6N) in C gD g solution 156 46 Molecular structure of [Me 2Ga0(CgH gN)] 2 157 47 Ir spectrum in the v C Q region of [Me 2GapzO(C 5H 3N)CH 2NMe 2]Mn- (C0) 3 in cyclohexane solution 160 48 80 MHz *H nmr spectrum of [Me 2Gapz0(C 5H 3N)CH 2NMe 2]Re(C0) 3 in Ccdc solution 162 6 6 49 Proposed conformation of [Me 2GapzO(C 5H 3N)CH 2NMe 2]M(CO) 3 (M = Mn or Re) 163 50 80 MHz room temperature *H nmr spectrum of [Me 2GapzO(C 5H 3N)CH 2- NMe 2]Ni(N0) in CDC13 solution 168 51 Proposed mechanisms for the fluxional process observed for [Me 2Gapz0(C 5H 3N)CH 2NMe 2]Ni(N0) in CDC13 solution 171 52 Ir spectrum in the v C Q region of [Me 2Gapz0(CgH gN)]Mn(C0) 3 in cyclohexane solution 172 53 80 MHz *H nmr spectrum of [Me 2Gapz0(C 9H gN)]Re(C0) 3 in C gD g solution 175 54 80 MHz XH nmr spectrum of [Me 2Gapz0(C 9H gN)]Mo(C0 ) 2 (Ti 3-C 3H 5) in C gD g solution 180 55 Proposed reaction sequence for the formation of L Rh(C0) (L = L , L ) complexes 183 a q r - xvi - Figure Page 56 80 MHz :H nmr spectrum of [Me 2Gapz0(C gH 6N)]Rh(C0) in CgDg solution 186 57 Proposed reaction sequence for the formation of [Me2GapzO- (CgHgN)]Rh(C0Me)1 189 58 270 MHz lH nmr spectrum of [Me2Gapz0(CgHgN)]Rh(C0Me)I in CDCI3 solution 191 - x v i l - LIST OF ABBREVIATIONS The following abbreviations have been used throughout t h i s t h e s i s : A Angstrom amu atomic mass unit(s) Anal. Analysis bipy 2,2'-dipyridine, or bipyridine br broad °C degree Celsius Calcd. Calculated cf Latin confer (compare) cm""''' wave number (reciprocal centimeters) COD cycloocta-l,5-diene cont'd continued Cp cyclopentadienyl, CgHg d doublet dd doublet of doublets dec. decrease dppe l,2-bis(diphenylphosphino)ethane dppm bis(diphenylphosphino)methane e.g. Latin exempli gratis (for example) EHMO Extended Huckel Molecular Orbital E.I electron impact - x v m - ethyl Fast Atom Bombardment f a c i a l Figure(s) Fourier Transform gram(s) hour(s) proton Hertz (cycles per second) Latin i d est (that i s ) i ncrease i nf rared magnetic resonance coupling constant Me2GapzO(C5H3)CH2NMe2 Me 2GapzO(C gH 6N)" limited multiplet central (usually metal) atom in compound mass to charge ra t i o methyl 3,5-dimethylpyrazolyl, C^HyN2 meridional megahertz - xix - min minute(s) mL m i l l i l i t e r ( s ) mmol millimole(s) MS Mass Spectrometry n integer nmr nuclear magnetic resonance P parent Ph phenyl, C gH 5 pKa - l o g ^ K a (Ka=acid d i s s o c i a t i o n constant) ppm parts per m i l l i o n pz p y r a z o l y l , ̂ 3 ^ 2 s s i n g l e t sal en bi s-sal i c y l al dehy deethyl enedi i mi ne t t r i p l e t THF tetrahydrofuran tmed N,N,N',N'-tetramethylethyl enedi amine U.B.C. University of B r i t i s h Columbia UV u l t r a v i o l e t xs excess approximately > greater than or equal to A reflux TI Greek haptein (hapto = to fasten) T I ' monohapto - XX - dihapto trihapto pentahapto hexahapto nmr chemical s h i f t bridging IR stretching frequency - xx i - ACKNOWLEDGEMENT I wish to thank the facul t y and technical s t a f f of the Chemistry Department, e s p e c i a l l y to Dr. Steve Rettig (X-ray crystallography). I would also l i k e to acknowledge the members of my Steering Committee; Drs. B.R. James, D. Dolphin and M. Fryzuk for t h e i r very constructive suggestions during the preparation of t h i s t h e s i s . Financial assistance from the Chemistry Department, in the form of a Teaching Assistantship i s g r a t e f u l l y acknowledged. My most sincere thanks are also extended to my family, whose support and patience was a constant source of encouragement. This thesis i s dedicated to them. F i n a l l y , I wish to express my gratitude to my research supervisor. Dr. Alan Storr for his guidance and support during the course of th i s work. 1 CHAPTER 1 INTRODUCTION 1.1 GENERAL INTRODUCTION The five-membered diazole heterocyclic compound, pyrazole, was f i r s t prepared in the late nineteenth century [1]. By conventional heterocyclic nomenclature, numbering begins at the protonated nitrogen and proceeds in the dir e c t i o n of the second unprotonated nitrogen as shown in Figure 1. 4 Figure 1. Pyrazole. The three carbon atoms (C3, C4, C5) and N2 of the pyrazole nucleus contribute four T c-electrons, and Nl which is uninvolved in the double bond 2 formation, donates i t s electron pai r , thus creating an aromatic sextet of n-electrons. The c o l o r l e s s , sweetish smelling (unlike most amines), c r y s t a l l i n e s o l i d i s h y d r o l y t i c a l l y , o x i d a t i v e l y , and thermally stable, due partly to i t s aromatic character, since i t may be considered a Huckel '4n + 2' system (n = 1). The considerable aromatic character of the five-membered pyrazole ring has been borne out by molecular o r b i t a l c a l c u l a t i o n s by Kaufman et a l . [ 2]. Upon deprotonation of the a c i d i c hydrogen attached to Nl (pK = 2.53) [3] by appropriate bases, pyrazole becomes the resonance-stabilized pyrazolide anion (Figure 2). H N N «f NaH Figure 2. Deprotonation of pyrazole. As a ligand, pyrazole can act as a neutral, monodentate, two-electron donor ligand via the lone pair on N2 in a s i m i l a r manner to pyridine as shown in Figure 3. N N Figure 3. Monodentate coordination of pyrazole. With the pyrazolide anion, i n t e r a c t i o n with suitable metals can occur via one of three possible coordination modes - monodentate, 2 TI -endobidentate and exobidentate modes, respectively (Figure 4 ) . o o p (•) (b) (c) Figure 4. Coordination modes of the pyrazolide anion. 4 Rel a t i v e l y few examples of monodentate coordination of the pyrazolide anion to t r a n s i t i o n metals (Fig. 4(a)) have been reported e.g., [M(pz) 2(L-L)] (M = Pt, Pd; L-L = dppe, bipy, COD) [4] and (PPh 3) 2(C0)Ir- [3,5-(CF 3) 2pz] [5]. On the other hand, only one example of TI -endobi- dentate coordination of the pyrazolide anion (Fig. 4(b)), has been reported in the l i t e r a t u r e . This unusual bonding mode exhibited by the compound s t r u c t u r a l l y characterized as pzUCp 3 [6] was interpreted as being r e f l e c t i v e of i ) the i o n i c character of the uranium nitrogen bonds as compared to a _i-block t r a n s i t i o n element, and i i ) the larger atomic radius of uranium. The most commonly found coordination mode is where the pyrazolide anion acts as an 'exobidentate 1 bridge between two metals, which may be i d e n t i c a l or d i f f e r e n t (Fig. 4 ( c ) ) . Numerous examples of stable compounds containing such 'exobidentate' bridges have been reported in the l i t e r a t u r e (e.g., [7-11]). Upon coordination to certain main group elements, monodentate interactions (as depicted i n F i g . 4(a)) of the pyrazolide anion become more prevalent. For example, coordination to boron gives the poly(1-pyrazolyl )borates [12]; s i m i l a r l y to carbon, the p o l y ( l - p y r a z o l y l ) - alkanes [13], to gallium the p o l y ( l - p y r a z o l y l ) g a l l a t e s [14], and recently the t r i s ( l - p y r a z o l y l e t h y l )amine were obtained by coordination to nitrogen [15]. The most widely studied of these main group py razolyl ligand systems are the uninegative p o l y ( l - p y r a z o l y l )borates with the general formula [ R n B ( p z ) 4 _ n ] ~ (where R = H, a l k y l , a r y l , py r a z o l y l , N 2C 3H 3; and n = 0, 1, 2). These are a broad and v e r s a t i l e class of uninegative ligands whose coordinative a b i l i t y is a consequence of favourable 5 e l e c t r o n i c and geometric f a c t o r s . The combination of these factors has led to numerous metal complexes incorporating the p o l y d - p y r a z o l y l ) borate ligands, an area that has been the suject of a number of review a r t i c l e s [7,16,17]. These f a i r l y robust ligand systems are readily prepared by the reaction of an a l k a l i metal borohydride with pyrazole, the extent of the reaction being dependent on the reaction temperature as shown in Figure 5 [12,18]. Although the s a l t s of a l l three anions are a i r - s t a b l e and can be stored i n d e f i n i t e l y in the s o l i d state, the s t a b i l i t y of the p o l y d - p y r a z o l y l ) b o r a t e species in solution decreases as the number of hydrogens attached to boron i s increased. The uninegative bidentate bispyrazolylborate anion (n = 2), i s formally analogous to the 1,3-diketonate ion, both being uninegative four-electron donor ligands. A notable difference between both ligand systems i s that while various associative e q u i l i b r i a i . e . , monomer-dimer- trimer have been observed for the 1,3-diketonate metal complexes [19], the former reacts with metal ions to give monomeric bisbidentate complexes usually with the [B-(N-N)2-M] (M = t r a n s i t i o n metal) six-membered ring in a boat conformation as shown in Figure 6 (e.g., [20,21]). 6 Figure 5. Preparation of the poly(1-pyrazolyl)borate ligand systems. Of p a r t i c u l a r interest is the symmetrical uninegative, t r i d e n t a t e t r i s ( l - p y r a z o l y l )borate anion RBpz~ (n = 1), formally analogous to the 7 Figure 6. Boat conformation of the bis(1-pyrazolyl )borate bidentate metal complex. well known cyclopentadienide ion (Cp") - both being uninegative, s i x - electron donor ligands which are considered to occupy three mutually cis positions i n t h e i r octahedral metal d e r i v a t i v e s . The presence of RBpz^ i n place of Cp" ligand has been found to impart unusual s t a b i l i t y to the r e s u l t i n g metal d e r i v a t i v e s . For example, the compound [HBpz^DCuCO [22] is heat- and a i r - s t a b l e , while (r)-C5H5)CuC0 [23] is thermally unstable and a i r - s e n s i t i v e . In another example, Clark and Manzer have succeeded i n s t a b i l i z i n g a series of five-coordinate methyl platinum (Il)-acetylene, allene and o l e f i n complexes using the tridentate RBpzZ 8 (R = H, Me, py r a z o l y l , N 2C 3H 3) [24,25] ligands. Such five-coordinate platinum(II) complexes are rare [26-30]. The mode of r e a c t i v i t y of RBpz 3 ligand can be altered by the presence of alkyl substitutents at the C(3) and C(5) positions of each pz r i n g . For example, the reaction of [HBpz 3]Mo(C0) 3 with aryldiazonium cation ArNg, gave the substitution product [HBpz 3]Mo(C0) 2(N 2Ar) (Ar = m- or p- fluorophenyl) [31]. In contrast, the reaction of [HB(3,5-Me 2pz) 3]Mo(C0) 3 + 2 anion with aryldiazonium cation ArN 2, y i e l d e d the novel TI -aroyl complex [HB(3,5-Me 2pz) 3] Mo(CO) 2(n 2-C0Ar) in a c e t o n i t r i l e [32], and the chloromethylidene complex [HB(3,5-Me 2pz) 3]Mo(C0 ) 2 (V-CCl) in CH 2C1 2 [33], respectively. The c l o s e l y related dimethylbis(1-pyrazolyl)gal l a t e ligand i s prepared by the reaction of trimethylgallium with sodium pyrazolide followed by addition of pyrazole [14] as depicted in Figure 7. The m e t h y l t r i s - ( l - p y r a z o l y l ) g a l l a t e MeGapz3 ligand i s prepared by the reaction of methyldichlorogallium with sodium pyrazolide according to the equation below [34]. MeGaCl ? + 3Na +pz" ™ F > Na +[MeGapz.]" + 2NaCl c >7 days * A l k a l i metal s a l t s of the p o l y d - p y r a z o l y l ) g a l l a t e anions are hygroscopic, white s o l i d s quite unlike the po l y d - p y r a z o l y l ) b o r a t e s a l t s which are a i r - and moisture-stable s o l i d s . 9 Figure 7. Preparation of Me2Gapz2 ligand. Although the coordination chemistry of the po l y ( 1 - p y r a z o l y l ) g a l l a t e ligands p a r a l l e l s that of the boron systems, some important differences result from the introduction of gallium for boron in the ligand systems. 10 A more e l e c t r o n - r i c h t r a n s i t i o n metal center i s created in the gallium complexes [34], with a greater degree of s t e r i c protection afforded the chelated metal due to the longer Ga-N bond (-2.0A c f . -1.5A for B-N) [34]. The gallium-based ligands occasionally undergo chemical transformations unknown in the analogous boron systems. For example, the ligand [MeGa(3,5-Me 2pz) 3]~ r e a d i l y converts to the less 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' ligand [MeGa(3,5-Me 2pz) 2(0H)]~ in the attempted 3 3 syntheses of the 'TI - a l l y l ' complexes, [MeGa(3,5-Me 2pz) 3]M(C0 ) 2 ( r i - a l l y l ) (where M = Mo or W, ' ^ - a l l y l ' = TI 3-C_H 5 , * l 3-C 4H 7) [35]. The gallium-based ligand systems are s y n t h e t i c a l l y much easier to prepare since forcing-conditions ( i . e . , high temperatures) are generally unnecessary. Most importantly, the methyl groups on gallium appear as unique resonances at high f i e l d s (~9-ll"0 in the lH nmr spectrum. Not only can these resonances act as XH nmr probes but they also make spectral i n t e r p r e t a t i o n less complicated than in the boron systems. The RBpZg" and MeGapz^ ligand systems are unique in themselves, being the only trigonal t ridentate, uninegative six-electron donor ligands of approximate C 3 v symmetry. The t r i p o d - l i k e structure of these ligands i s i d e a l l y suited to occupy three mutually c i s positions in octahedral metal complexes. Crystal structure determinations of [ HBpz^Co [36], [HBpz 3]SnMe 3 [37], [HBpz 3]Mo(C0) 3« radical species [38], and [MeGapz^Ni [39] do a t t e s t to t h i s coordination geometry of the ligands about the metal centers in the above complexes. This uniqueness however poses the problem of finding appropriate known systems for d i r e c t comparison. The 11 various known tridentate donor tripod ligands of C 3 y symmetry such as the 1,l,l-tris(aminomethyl)ethane and i t s N-methyl-substituted derivatives with the general formula CH 3-C-(CH 2-Z) 3 (where Z = NH2, NHMe, NMe2) [40] are inappropriate, being uncharged and thus, incapable of forming neutral b i s - t r i d e n t a t e complexes analogous to the [RBpz 3]M compounds (where M = 2+ 2+ 2+ divalent t r a n s i t i o n metal e.g., Mn , Ni , Fe ). The uninegative, e l e c t r o n i c a l l y tridentate cyclopentadienyl ion (Cp"), even though i t forms TC- rather than a-bonded complexes t y p i c a l of the t r i s ( 1-pyrazolyl )borate/- gallate ligands, s t i l l provides the cl o s e s t approximation to the RBpz 3, and MeGapz3 ligands in terms of derivative chemistry. Hence the RBpz 3, MeGapz3 and Cp" ligands are likened to and compared to one another in several " i s o e l e c t r o n i c " complexes. A s l i g h t but s i g n i f i c a n t deviation from the RBpz 3 and MeGapz3 ligand systems came with the introduction of the novel unsymmetric, uninegative, tr i d e n t a t e , s i x - e l e c t r o n donor, gallium-containing ligand systems. These unsymmetric ligands incorporating a pyrazolyl moiety, in conjunction with a bifunctional donor group both being attached to a dimethyl gallium grouping [41] (Figure 8), have yet no counterparts in the related pyrazolylborate chemistry. 12 X = 0 . Y = N o r S . X = S. Y = N. Figure 8. General representation for the unsymmetrical t r i d e n t a t e organogal1 ate ligand. The ligand [HB(3,5-Me 2pz) 2(SAr)]" (Ar = CgH4-4-CH3) [42], reported recently, is the f i r s t and the only known example of a poly(1-pyrazolyl )- borate ligand in which an additional donor f u n c t i o n a l i t y apart from the pyrazolyl groups is attached to boron. The unsymmetric gal l a t e ligands are prepared by the reaction of an active hydrogen-containing polyfunctional donor compound with the sodium s a l t of trimethyl gal 1iurn pyrazolyl anion to eliminate methane gas according to the equation:- 13 Na+[Me-.Gapz]" + LH — > Na +[Me„GapzL]~ + MeH * A LH = a c t i v e hydrogen-containing compound In contrast to RBpz^, MeGapz^ or Cp" ligand systems which coordinate ex c l u s i v e l y f a c i a l to metals, the unsymmetric gallate ligands have the f l e x i b i l i t y to coordinate to metals in either a f a c i a l or meridional arrangement. Both of these geometries have been confirmed s t r u c t u r a l l y by X-ray c r y s t a l analyses of metal complexes incorporating the unsymmetric ga l l a t e ligands [43,44]. Chapter II of t h i s thesis reports on the synthesis and characterization of the molybdenum tricarbonyl anions LMo(C0) 3 (L = MeGapz.j, MeGa(3,5-Me 2pz) 3) as t h e i r sodium, tetraethylammonium, and triphenylarsonium s a l t s , and presents spectroscopic evidence for the i n t e r a c t i o n of the LMo(C0) 3 anion with the Na + cation in THF. The r e a c t i v i t y of the MeGapz 3Mo(C0) 3 anion toward alkyl hai ides, benzoyl c h l o r i d e , protonating species and halogens i s also explored in this Chapter. The r e a c t i v i t y of the LMo(C0) 3 anions (L = HBpz 3, MeGapz3, [Me 2Gapz(0CH 2CH 2NMe 2)]) toward Wilkinson's c a t a l y s t RhCl(PPh 3) 3 > and also the r e a c t i v i t y of the MeGapz3Mo(CO) 3 anion toward a variety of t r a n s i t i o n metal halide species are detailed in Chapter I I I . Complexes containing d i r e c t t r a n s i t i o n metal-transition metal bonds i s o l a t e d from the reactions are discussed, and X-ray structural data are presented for two of the complexes [MeGapzjMo(COkRh(PPhJ ? and [MeGapz-,]Mo(COLCu(PPh,). 14 Chapter IV explores the r e a c t i v i t y of the MeGapZgMo^O)^ anion toward Group 14 ( S i , Ge, Sn) alkyl or aryl halide species. Complexes featuring direct t r a n s i t i o n metal-group 14 element bonds are discussed and X-ray c r y s t a l l o g r a p h i c analysis of the compound [MeGapz2_.Mo(C0)3SnPh3 is presented. Compounds is o l a t e d from the d i r e c t reaction of [MeGapzg]" and [MeGa(3,5-Me2Pz) 3]~ ligands with organotin chlorides are also presented and discussed. The synthesis, characterization and X-ray crystal structural determinations of the coordination compounds [MegGaOfCgH^NjQ^NMeg]. arid [I^GaC^CgHgN).^, the syntheses of the two novel unsymmetric, t r i d e n t a t e p y r a z o l y l g a l l ate ligands, [ I ^ G a p z ' C K C g H g N j ^ N I ^ ] - , ( L ~ ) , and [Me 2Gapz*- O(CgHgN)]", (L~), and the r e a c t i v i t y of the ligands towards a variety of t r a n s i t i o n metal halide species are the subject of Chapter V. In the same Chapter, the r e a c t i v i t y of L Rh(CO) (L = L . L ) toward methyl iodide and a q molecular iodine is also discussed. 1.2 General Techniques 1.2.1 Handling of Reagents Since most of the materials were a i r - s e n s i t i v e , a l l manipulations were ca r r i e d out in a dry box (Vacuum/Atmospheres Corporation model DRI LAB HE-43-2), containing pr e - p u r i f i e d nitrogen (Linde USP, Union Carbide Canada), and f i t t e d with a D r i t r a i n (model HE 493), or on a high vacuum l i n e equipped with a duo-seal pump (Welch S c i e n t i f i c Company). Reactions 15 were carried out under an inert atmosphere in the dry box or in a nitrogen-blanketed atmosphere unless otherwise stated. AIT reaction solvents were routinely dried by refluxing under N 2, followed by d i s t i l l a t i o n according to l i t e r a t u r e methods [45,46]. The most frequently used solvents were dried as follows; THF over Na/benzophenone, and benzene over potassium by continuous refluxing i n 2 l i t e r s t i l l pots, collected prior to use or stored in the dry box under N 2. In the case of THF, the characteristic blue coloration of the benzophenone ketyl radical was taken as an indication of complete dryness. The less frequently used solvents CH 2C1 2, hexane and a c e t o n i t r i l e were dried by refluxing over CaH2, CaS0 4 and P2°5» respectively, followed by d i s t i l l a t i o n . 1.2.2 Starting Materials i ) Preparation of Trimethylgallium, Me3Ga [47] HgCl ? 3Me2Hg + 2Ga 2Me3Ga + 3Hg Trimethylgallium was prepared by the gallium metal-mercury alkyl exchange method. Typically, dimethylmercury (25 g, 108 mmol) was added to gallium metal (7.2 g, 103 mmol) and a c a t a l y t i c amount of mercuric chloride placed in a Carius tube. The tube and i t s contents were then frozen to l i q u i d nitrogen temperatures (—196°C). The tube was then evacuated, flame-sealed at the con s t r i c t i o n , and slowly warmed to room temperature. The tube was then stored for about one week at ~120°C in a metal bomb apparatus. At this stage, the product Me^Ga, which i s a 16 c o l o r l e s s l i q u i d , had separated from the mercury and excess gallium metal deposited at the bottom of the tube. The Me^Ga was then c a r e f u l l y i s o l a t e d and condensed into ampoules on the vacuum l i n e . Its purity was checked by *H nmr measurements. It was then used in subsequent reactions without further p u r i f i c a t i o n . i i ) Preparation of Gallium T r i c h l o r i d e , GaCl 3 [48] 2GaU) + 2Cl ?(g) > (Ga +) (GaCl~)U) A (Ga +)(GaCl 4 ) U ) + C l 2 ( g ) > G a 2 C l 6 Gallium t r i c h l o r i d e was prepared by d i r e c t reaction of the elements. Pure chlorine gas (Matheson) was dried by passing through concentrated s u l f u r i c acid in a gas bubbler, a f t e r which the gas was passed into the glass apparatus shown in Figure 9. The gallium metal, about 22 grams was placed in A. The apparatus was flushed with chlorine gas, and the gallium metal slowly warmed to melting (m.p. 29.78°C) using a bunsen flame. The molten gallium reacted with the c h l o r i n e , f i r s t giving a c o l o r l e s s l i q u i d , gallium t e t r a c h l o r o g a l l a t e , G a 2 C l 4 (m.p. 170.5°C). The l i q u i d GagCl^ disappeared upon addition of more ch l o r i n e , and f i n a l l y gave a v o l a t i l e white s o l i d , gallium t r i c h l o r i d e , G a C l 3 (m.p. 79°C). The rate of flow of the chlorine gas and the rate of heating the molten gallium were adjusted so that most of the v o l a t i l e GaCl 3 was deposited in the cooled receiver boat C. After a l l the gallium had reacted ( e s s e n t i a l l y 100%), any sublimate in A was driven into C by warming and flame-sealing the c o n s t r i c t i o n at B. The apparatus was then D > o o o E c igure 9. Apparatus for the preparation of GaCl 3. 18 evacuated and flame-sealed at F. The crude halide was then re-sublimed into the ampoules E, and each sealed at t h e i r respective 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 gallium t r i c h l o r i d e in each ampoule was then estimated. The gallium t r i c h l o r i d e was found to remain stable i n d e f i n i t e l y when stored in t h i s manner, i i i ) Preparation of methyldichlorogallane, MeGaCl 9 [49] GaCl 3 + xsMe 4Si > MeGaCl 2 + Me 3SiCl An ampoule containing a known quantity of GaCl 3 was cracked open in the glove box and loaded into the l e f t side-arm of the apparatus shown i n Figure 10. This side-arm was capped and a tap adapter f i t t e d onto the B24 j o i n t . The apparatus was then evacuated via the tap adapter on the vacuum l i n e , and bulb E was then frozen in l i q u i d nitrogen. The c o n s t r i c t i o n at A was flame-sealed and the GaCl 3 was melted by warming with a bunsen flame. The melted GaCl 3 was allowed to run down into bulb E, excess spectrograde tetramethylsilane was condensed into bulb E, and the apparatus flame-sealed at c o n s t r i c t i o n s B and C. The apparatus and i t s contents were slowly warmed to room temperature, followed by placing in a hot water bath for several days. On cooling, white c r y s t a l s of MeGaClg were deposited at the bottom of the f l a s k . The unreacted tetramethyl- si l a n e and the trimethylchiorosilane by-product were removed by rupturing the break-seal at D and condensing them into a l i q u i d nitrogen solvent trap. The white c r y s t a l s of MeGaCl 9 i s o l a t e d (~95% y i e l d ) were divided F igu re 10. Apparatus f o r the p repara t ion of MeGaCl 20 into smaller f r a c t i o n s and stored as THF solutions in sealed ampoules. The ampoules were cracked open and used for subsequent reactions when needed. iv) Preparation of the 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(O) (MeCN) 3Mo(C0) 3 [50] Mo(C0) c + 3MeCN M e C N v (MeCNkMofCOh + 3C0 6 ~3 days 3 3 In a typi c a l preparation, excess a c e t o n i t r i l e (~60 mL) was added to ~1 g Mo(C0) 6 in a 250 mL round-bottom f l a s k . The reaction mixture was then refluxed for ~3 days. The r e s u l t i n g yellow-green solution was cooled to room temperature and the solvent stripped o f f in vacuo. Yellow-green, a i r - s e n s i t i v e c r y s t a l s of (MeCN) 3Mo(C0) 3 ( v C Q : 1918(s), 1781(s) cm"1, Nujol; 1912(s), 1773(s) cm"1, THF) were recovered in almost quantitative y i e l d . The compound was then used in subsequent reactions no more than a few days a f t e r preparation since i t i s unstable even under i n e r t conditions. It i s recommended that the compound (MeCN) 3Mo(C0) 3 be prepared in small quantites at a time, since from our experience, several attempts at the preparation of larger quantities in a single preparation always resulted in a mixture of compounds. The compound (MeCN) 3Mo(C0) 3 i s preferred as the s t a r t i n g material in most of the reactions discussed in this thesis primarily because a c e t o n i t r i l e i s a ligand which has very l i t t l e prc-dTc bonding a b i l i t y [51]; therefore the molybdenum-acetonitrile bond in the (MeCN) 3Mo(C0) 3 complex i s weak, and the a c e t o n i t i l e ligand i s e a s i l y replaced from the complex [52], 21 1.3 Physical Measurements lH nmr spectra were recorded on a Bruker WP-80 instrument using Fourier Transform techniques. A Bruker WH-400 or a Nicolet-Oxford H-270 spectrometer was employed whenever a more detailed or enhanced resolution spectrum was desired. Samples were prepared by condensing the appropriate amount of deuterated solvent (CgDg, CDCI3 or dg-acetone, Merck Frost Canada Inc.; and dg-toluene, Merck Sharp and Dohme Canada Ltd.) onto the s o l i d material contained in an nmr tube. The nmr tube was subsequently flame-sealed under vacuum. Chemical s h i f t s were measured r e l a t i v e to the residual protons of the internal standard where tQ H = 2«84 ppm, ̂ C H C 1 = 6 6 3 2.73 ppm, r { C H ^ ^ Q = 7.89 ppm, and * T o l u e n e_Me = 7.91 ppm. Infrared spectra were recorded on a Perk in Elmer 598 double beam spectrometer. Samples were prepared as solutions, usually in dichloro- methane, cyclohexane or THF (KBr and Csl solution c e l l s ) , or as Nujol mulls (KBr p l a t e s ) . The spectra were c a l i b r a t e d with the 1601 cm - 1 band of polystyrene. Mass spectra were recorded on a Kratos AES MS 50 spectrometer equipped with a d i r e c t i n s e r t i o n probe and interfaced to a computer for higher molecular weight (>500 amu) compounds or a VARIAN MAT CH4 spectrometer for low molecular weight (<500) compounds. In general, in t e r p r e t a t i o n of fragmentation patterns was s i m p l i f i e d by d i r e c t comparison of the observed i n t e n s i t y patterns to the theoretical i n t e n s i t y patterns generated by computer simulation from the natural i s o t o p i c abundances of the elements. 22 Crystallographic determinations were conducted on single c r y s t a l s using graphite monochromated Mo-Ka radiation on an Enraf-Nonius CAD4-F diffractometer. This work was performed by Dr. S. Rettig of the U.B.C. Crystallography Laboratory. Stereodiagrams and related bond distances and angles are c o l l e c t e d in Appendix I . Elemental analyses were performed by Mr. P. Borda of the U.B.C. Microanalytical Laboratory. 23 C h a p t e r I I THE MOLYBDENUM TRICARBONYL ANION [MeGapz 3 ]Mo(C0) 3; SYNTHESIS AND CHARACTERIZATION OF THE N a + , E t ^ N + AND HAsPhJ SALTS, AND INVESTIGATION OF THE REACTIVITY TOWARDS ALKYL HALIDES, PROTONATING SPECIES AND HALOGENS. 2 . 1 INTRODUCTION The u n i n e g a t i v e , t r i d e n t a t e , s i x - e l e c t r o n d o n o r l i g a n d s RBpz^ (R = H, a l k y l , a r y l , p y r a z o l y l , N2C3H3), and MeGapz^ show many s i m i l a r i t i e s t o t h e ana logous c y c l o p e n t a d i e n y l (Cp~) l i g a n d . F o r example t h e RBpz 3 and MeGapz 3 l i g a n d s r e a c t w i t h molybdenum h e x a c a r b o n y l o r t r i s ( a c e t o n i t r i l e ) - molybdenum t r i c a r b o n y l y i e l d i n g a n i o n s of t h e t y p e LMo(C0) 3 (L = R B p z 3 , R B ( 3 , 5 - M e 2 P z ) 2 , MeGapz^) ana logous t o t h e CpMo(C0) 3 a n i o n , and i s o l a b l e as t h e t e t r a e t h y l a m m o n i u m s a l t s [ 5 3 , 5 4 ] . D i f f e r e n c e s i n b e h a v i o u r a re some- t i m e s o b s e r v e d . The r e a c t i o n o f LMo(C0) 3 [ L = RBpz 3 (R = H, p y r a z o l y l , N 2 C 3 H 3 ) [ 5 3 ] , MeGapz 3 [ 3 4 ] , and PhBpz 3 [ 5 4 ] ) ] a n i o n s w i t h a l l y l h a l i d e s g i v e s d i r e c t l y t h e n - a l l y l d e r i v a t i v e s w i t h l o s s of CO. I n c o n t r a s t , t h e CpMo(C0) 3 a n i o n r e a c t s w i t h a l l y l h a l i d e s t o g i v e t h e a - a l l y l complex C p M o(C0 ) 3 ( a - a l l y l ) , wh i ch d e c a r b o n y l a t e s o n l y upon UV i r r a d i a t i o n t o g i v e t h e n - a l l y l d e r i v a t i v e C p M o t C O ^ f t - a l l y l ) [ 5 5 , 5 6 ] . There i s , h o w e v e r , a n o t h e r n o t a b l e d i f f e r e n c e i n b e h a v i o u r : i n c o n t r a s t t o t h e numerous 24 seven-coordinate cyclopentadienyl complexes generally denoted as CpMl_4 [57], r e l a t i v e l y few of such derivatives are known f o r the p o l y ( l - pyrazolyl )borate complexes. The reported examples of seven-coordinate poly(l-pyrazolyl )borate complexes are [HBpz3]Mo(C0)3R (R = H, Me, Et) [53], [HBpz 3]W(C0) 2(CS)I [58], [RBpz 3]TaMe 3Cl (R = H or pz) [59], and most recently [HBpz3]Mo(C0)3X (X = H, Br, I) [60]. The electronic nature of the HBpz3 ligand has been shown to be considerably different from that of the Cp" ligand in that the former hybridizes the metal orbitals into an octahedral disposition much more e f f e c t i v e l y than does the Cp" ligand [36,60]. The propensity of the molybdenum tricarbonyl complexes incorporating the RBpz3 ligand to remain preferentially six-coordinate is manifested in the s t a b i l i t y of the radical species [HBpz 3]Mo(C0) 3* [38], in contrast, to the analogous CpMo(C0)3» [61], and (ri-CgMeg)Mo(C0)3# [62] radical species which are unstable with respect to t h e i r [CpMo(C0) 3] 2 and [(ri-CgMeg)Mo(C0) 3] 2 dimer precursor. Comparison of the chemistry of compounds incorporating the RBpz 3, MeGapz3 and Cp" ligand systems was therefore considered to be instructive especially where the coordination number about the central metal atom is greater than six. The 3:4 or "four-legged piano stoo l " structure is the paradigm f o r seven-coordinate CpMI_4 complexes of group 5 and 6 t r a n s i t i o n metals [63]. At the inception of this work, only one type of molybdenum TI -acyl complex incorporating the tridentate poly (1-pyrazolyl )borate ligand, [HB(3,5-Me 2pz) 3]Mo(C0) 2(n 2-C0R) (R = Ph, CgH4NMe2-p, C gH 4CF 3-p, CgH4Me-p, 25 C gH 1 1) [32] was known. The other examples are [HBpz 3]Mo(C0) 2 (Tf-C0R) (R = Me, Ph) [64,65] and t h e i r phosphine adducts reported during the course of t h i s work. In the l a t t e r examples, the authors concluded that the combination of the r e l i e f of s t e r i c congestion and o r b i t a l hybridiza- 2 t i o n favored the transformation of [HBpz 3]Mo(C0) 3R to the r\ -acyl complex [HBpz 3]Mo(C0) 2(T] -COR) [65]. We reasoned that the combination of both e f f e c t s ( r e l i e f of s t e r i c congestion and orb i t a l hybridization) could p o t e n t i a l l y s t a b i l i z e the i s o e l e c t r o n i c , i s o s t r u c t u r a l [MeGapz3]Mo- 2 (C0) 2(T ) -COR) (R = Me, Ph) complexes in a manner s i m i l a r to the boron system. The LMo(C0) 3 (L = MeGapz3, MeGa(3,5-Me 2pz) 3) anions have been is o l a t e d as t h e i r Na +, Et^N + and HAsPh 3 s a l t s . The LMo(C0) 3 anions in t e r a c t with the Na + cation in THF, and i r spectroscopic evidence f o r t h i s anion-cation i n t e r a c t i o n i n THF is presented and discussed. Thus, t h i s result constitutes the f i r s t reported observation of the involvement of the LMo(C0) 3 (L = RBpz 3 or MeGapz 3) anion in ion-pairing with cations i n basic and polar solvents such as THF. The general r e a c t i v i t y of the [MeGapz 3]Mo(C0) 3 anion toward alkyl halides, benzoyl chloride, protonating species and halogens has been investigated. The compounds [MeGapz3]Mo- (C0) 3R (R = H, Et) have been prepared and the hydride has been shown to exh i b i t d i s s o c i a t i v e phenomena in THF. The compound [MeGapz3]Mo- 2 (C0) 2(TI -COMe), a product of f a c i l e alkyl to CO migration reaction, i s presented and discussed. An X-ray crystal structural determination of the 26 [HAsPh 3] +[MeGa(3,5-Me 2pz) 3Mo(C0) 3]~ s a l t i s currently in progress. Parts of this chapter have been submitted for publication [66]. 2.2 EXPERIMENTAL 2.2.1 S t a r t i n g Materials Triphenylarsonium chloride (Strem Chemicals), tetraethylammonium chlo r i d e (Eastman Organic Chemicals), ethyl bromide ( A l l i e d Chemicals), HCl(g) (Matheson), DBr(g) (Merck Sharpe and Dohme), methanol and benzoyl chloride (Fisher S c i e n t i f i c ) were used as supplied. The sodium s a l t s of the methyltris(1-pyrazolyl)gal late Na +MeGapz 3 [34], and methyltris(3,5- d i m e t h y l - l - p y r a z o l y l ) g a l l a t e Na +[MeGa(3-5-Me 2pz) 3]~ [35] were prepared as described previously. Methyl iodide (Fisher S c i e n t i f i c ) was dried by d i s t i l l a t i o n over P 20g and stored over mercury droplets before use. G l a c i a l a c etic acid ( A l l i e d Chemicals) was dried according to l i t e r a t u r e methods [45], 2.2.2 Preparation of Na +LMo(C0) 3 (L = MeGapz3, MeGa(3,5-Me 2pz) 3) Na +L" + (MeCN) 3Mo(C0) 3 T H F > Na +LMo(C0)~ + 3MeCN A 30 ml ali q u o t of Na +MeGapz 3 (~0.51 mol) ligand solution in THF was added to a s t i r r e d solution of (MeCN) 3Mo(C0) 3 (0.154 g, 0.510 mmol) in the same solvent. The reaction mixture was s t i r r e d u n t i l the V ^ Q bands c h a r a c t e r i s t i c of the (MeCN) 3Mo(C0) 3 s t a r t i n g material had disappeared. 27 The solvents were then allowed to evaporate from the mixture to give an amber colored s o l i d product of the desired s a l t , Na +[MeGapz 3Mo(C0) 3]~. The s a l t Na +[MeGa(3,5-Me 2pz) 3Mo(C0) 3]~ was prepared by a s i m i l a r method. Both s a l t s were very a i r - s e n s i t i v e . The pronounced i n s t a b i i t y of these Na + s a l t s precluded s a t i s f a c t o r y analyses, however they were characterized by t h e i r solution i r and *H nmr spectra. For Na +[MeGapz 3Mo(CO) 3]": IR(THF) v C Q : 1895(s), 1775(s), 1720(s) cm"1; IR(CH 2C1 2) \>CQ: 1888(s), 1760(br) cm - 1. lH NMR (d g-acetone, 80 MHz): T ( C H 3 ) 2 C 0 = 7.89 ppm, 9.58s (Ga-Me); 3.83t (pz-H 4); 2.35d (pz-H 5); 3 2.00d (pz-H ). (^HCCH = ~ 2 ^ Z ^ 0 r ^ Z P r o t o n s * ) For Na +[MeGa(3,5-Me 2pz) 3Mo(C0) 3]": IR(THF) v C Q : 1890(s), 1765(s), 1710(s) cm"1; IR(CH 2C1 2) vQQ: 1885(s), 1745(br) cm"1. lH NMR (d 6-acetone, 80 MHz): x ( C H 3 ) 2 C 0 = 7.89 ppm, 9.54s (Ga-Me); 7.78s (pz-Me 5); 7.19s (pz-Me 3); 4.38s (pz-H 4). 2.2.3 Preparation of [Et 4N] +[MeGapz 3Mo(C0) 3]~ Na +MeGapz 3 + (MeCN) 3Mo(C0) 3 T H F > Na +MeGapz 3Mo(C0) 3 + 3MeCN Na +MeGapz 3Mo(C0) 3 + E t 4 N + C l " T H F > [Et 4N] +[MeGapz 3Mo(C0) 3]" + NaCl To a s t i r r e d THF solution of (MeCN) 3Mo(C0) 3 (0.309 g, 1.02 mmol) was added a 60 ml aliquot of the Na +MeGapz 3 (~1.20 mmol) ligand solution i n THF. The reaction mixture was s t i r r e d at room temperature overnight at which time the solution i r spectrum of the mixture indicated complete 28 formation of the Na+MeGapz3Mo(CO)~ ( v C Q 1895, 1775, 1720 cm - 1, THF) s a l t . An equimolar amount of Et_,N +Cl~ (0.169 g, 1.02 mmol) dissolved in ~5 ml MeOH was added to the carbonyl s a l t solution. The resulting cloudy yellow sol u t i o n was s t i r r e d f o r another hour. The yellow p r e c i p i t a t e was c o l l e c t e d by f i l t r a t i o n and dried in vacuo to give the desired product [Et 4N] +[MeGapz 3Mo(C0) 3_f i n ~40% y i e l d . This s a l t i s unstable in a i r and solutions deteriorate with time. IR(CH 2C1 2) v C Q : 1890(s), 1760(br) cm"1; IR(Nujol) v ^ : 1885(s), 1752(s), 1730(s) cm - 1. lH NMR (d g-acetone, 270 MHz): x(CH 3) 2C0 = 7.89 ppm, 9.57s (Ga-Me); 3.8H (pz-H 4); 2.27d (pz-H 5); 1.92d (pz-H 3); 8.57br (N-CH 2-CH 3); 6.41br (N-CH2-CH3) ( J H C C H = ~2 Hz f o r pz protons.) 2.2.4 Preparation of [HAsPh 3] +[LMo(C0) 3]" (L = MeGapz 3 > MeGa(3,5-Me 2pz) 3) Na +LMo(C0)~ + HAsPh 3Cl" T H F > [HAsPh 3] +[LMo(C0) 3]" + NaCl To the s t i r r e d THF s o l u t i o n of Na +MeGapz 3Mo(C0) 3 (~0.85 mmol) s a l t was added s o l i d HAsPh 3Cl~ (0.29 g 0.85 mmol). The resulting mixture was heated under nitrogen at reflux temperatures overnight a f t e r which the s o l u t i o n was cooled and the solvent removed in vacuo. The resulting yellow residue was extracted with benzene and f i l t e r e d . Upon evaporation of the benzene solvent containing the extracts, a yellow s o l i d was obtained. R e c r y s t a l l i z a t i o n from CH 2Cl 2/hexane (1:1) mixed solvents afforded golden yellow needles of the desired [HAsPh 3] +[MeGapz 3Mo(C0) 3]~ 29 s a l t i n -90% y i e l d . The s a l t [HAsPh 3 ] + [MeGa(3 ,5-Me 2 pz) 3 Mo(C0) 3 ] " was prepared v i a a s i m i l a r procedure except tha t the res idue was ex t r a c t ed w i th CH 2C1 2 and hexane was added to the CH 2C1 2 f i l t r a t e . Th is enabled the i s o l a t i o n of the product w i thout benzene s o l v a t i o n . Both of the above s a l t s are cons ide rab ly more s t ab l e e i t h e r as s o l i d s or i n s o l u t i o n than the corresponding Na + or E t ^ s a l t s r e s p e c t i v e l y . Ana l . Ca l c d . For [HAsPh3]+[MeGapz3Mo(C0)3]"« 0.75 CgHg: C, 51.26; H, 3.91; N, 10.11. Found: C, 51.41; H, 3.54; N, 9.94. IR(CH 2 C1 2) v C Q : 1890(s) , 1750(br) cm" 1 ; IR(THF) v C Q : 1890(s) , 1755(br) cm" 1 ; IR(Nujo l ) v C Q : 1885(s) , 1760(s) , 1735(s) c m " 1 . *H NMR (dg-acetone, 80 MHz): -u(CH 3) 2C0 = 7.89 ppm, 9.56s (Ga-Me); 3.83t ( p z -H 4 ) ; 2.35d ( p z -H 5 ) ; 1.98d ( p z -H 3 ) ; 2.05s (As-Ph); 2.58s (As-__). ( J H C C H = ~2 Hz fo r pz pro tons . ) A n a l . Ca l cd . For [HAsPh 3 ] + [MeGa(3 ,5-Me 2 pz) 3 Mo(C0) 3 ] " : C, 51.83; H, 4.67; N, 9 .81 . Found: C, 52.43; H, 4.80; N, 9 .22. IR(CH 2C1 2) vCQ: 1885(s) , 1740(br) cm" 1 ; IR(THF) vCQ: 1885(s) , 1750(br) c m " 1 . lH NMR (dg-acetone, 80 MHz): T ( C H 3 ) 2 C 0 = 7.89 ppm, 9.55s (Ga-Me); 7.80s (pz -Me 5 ) ; 7.21s (pz -Me 3 ) ; 4.38s ( p z - H 4 ) ; 2.09s (As-Ph); 2.61s (As-H). 2.2.5 Attempted P repa ra t i on of [MeGapz 3]Mo(C0) 3H us ing A ce t i c Ac id A THF s o l u t i o n of the Na + MeGapz 3Mo(C0) 3 s a l t was a c i d i f i e d wi th g l a c i a l a c e t i c a c i d . The reac t i on mixture was s t i r r e d ove rn igh t , and the so lven t removed under vacuum. The r e s u l t i n g res idue was ex t r a c t ed w i th benzene and f i l t e r e d . Orange-yel low s o l i d s were recovered upon evaporat ion of the benzene so l ven t con ta i n i ng the e x t r a c t s . Both the i r 30 and H nmr data for t h i s product indicated the presence of perhaps two compounds. IR(THF): 1960, 1930, 1910, 1810, 1895, 1775, 1725 cm'1. I R ( C g H 1 2 ) : 1950, 1935, 1912, 1810 cm"1. XH NMR (dg-acetone, 80 MHz): x(CH 3) 2C0 = 7.89 ppm, 10.14s, 9.63s (Ga-Me); 3.88t, 3.83t (pz-H 4); 2.40d, 2.33d (pz-H 5); 2.05d, 1.90d (pz-H 3). ( J H C C H = ~2 Hz for pz protons.) The i r bands at 1895, 1775, 1725 cm"1 in THF, and one set of signals in the *H nmr spectrum, compared quite well with those obtained for the Na +MeGapz 3Mo(C0) 3 s a l t s t a r t i n g material (see section 2.2.2). This is suggestive of incomplete protonation of the MeGapz 3Mo(C0) 3 anion by acetic acid; hence a stronger protonating species may be necessary to f u l l y protonate the anion. The reaction was then repeated using the strong acid HCl, as the protonating species. 2.2.6 Preparation of [MeGapz 3]Mo(C0) 3H using HCl Na +MeGapz 3Mo(C0) 3 + HCl (g) T H F > , MeGapz 3Mo(C0) 3H + NaCl An equimolar amount of HCl(g) (~0.5 mmol) was condensed into a THF solution containing the Na +MeGapz 3Mo(C0) 3 (~0.51 mmol) s a l t under vacuum. The reaction mixture was warmed up to room temperature and the re s u l t i n g orange solution was s t i r r e d for ~2 h. The solvent was then removed in vacuo, and the res u l t i n g residue extracted with hexane. Upon evaporation of the hexane f i l t r a t e containing the extracts, a i r - s e n s i t i v e orange sol i d s of the desired hydride species were obtained in ~60% y i e l d . Slow decomposition of th i s compound occurs in the basic and weakly polar 31 s o l v e n t , THF. F o r examp l e , t h e i r s pe c t r um of t h e h y d r i d e s p e c i e s i n THF showed t h e p r e s e n c e of t h e MeGapz^Mo(C0) 3 a n i o n p resumab ly emana t i ng f r om t h e a c i d - b a s e d i s s o c i a t i o n o f t h e Mo-H bond i n t h e MeGapz^Mo(CO^H comp l e x . A n a l . C a l c d . f o r MeGapz 3 Mo(CO) 3 H • 0 .5 C g H ^ : C, 3 7 . 6 7 ; H, 3 . 92 ; N, 1 6 . 4 8 . Found: C, 3 7 . 2 1 ; H, 3 . 62 ; N, 1 6 . 4 1 . I R ( C G H 1 4 ) : 1952 (w) , 1 9 2 8 ( s ) , 1 9 0 8 ( s ) , 1808(s) c m " 1 . l H NMR ( d g - a c e t o n e , 300 MHz): T ( C H 3 ) 2 C 0 = 7.89 ppm, 9.90s (Ga-Me); 3 .60 t ( p z - H 4 ) ; 2 .50d ( p z - H 5 ) ; 2 .16d ( p z - H 3 ) 18 .50s (Mo-IH). ( J HCCH = ~ 2 H z f o r p z P r o t o n s ' ) 2 . 2 . 7 P r e p a r a t i o n of [MeGap z 3 ]Mo (C0 ) 3 D [ H A s P h 3 ] + [ M e G a p z 3 M o ( C 0 ) 3 ] " + DB r ( g ) M e C N > MeGapz 3 Mo(C0 ) 3 D + H A s P h 3 B r " A s l i g h t e x c e s s o f D B r ( g ) was condensed i n t o a MeCN s o l u t i o n c o n t a i n i n g t h e M e G a p z 3 M o ( C 0 ) 3 a n i o n as i t s H A s P h 3 s a l t ( 0 . 50 g , 0 .66 mmol) under vacuum. The r e a c t i o n m i x t u r e was warmed t o room t e m p e r a t u r e and t hen s t i r r e d f o r ~2 h. Work-up of t h e dark orange r e a c t i o n m i x t u r e r e s u l t e d i n an o range s t i c k y s o l i d . T h i s p r odu c t i s ve ry a i r - s e n s i t i v e and s o l u t i o n s d e t e r i o r a t e i n a m a t t e r of m i n u t e s . The s o l u t i o n i r s p e c t r u m o f t h i s p r o d u c t i n C g H g i n d i c a t e d t h e f o r m a t i o n of t h e e x p e c t e d MeGapz 3 Mo(C0 ) 3 D d e u t e r i d e . However , i n THF s o l u t i o n , t h e i r s pe c t r um o f t h e p r o d u c t d i s p l a y e d bands c h a r a c t e r i s t i c of t h e M e G a p z 3 M o ( C 0 ) 3 a n i o n , i n a d d i t i o n t o t h o s e of t he d e u t e r i d e s p e c i e s . E v i d e n t l y , a c i d - b a s e d i s s o c i a t i o n o f t h e Mo-D bond i n t h e MeGapz 3 Mo(C0) 3 D complex s i m i l a r t o t h a t o b s e r v e d i n t h e h y d r i d e s p e c i e s ( S e c t i o n 2 . 2 . 6 ) i s 32 operative in THF s o l u t i o n . IR(C 6H g): 1935(s), 1910(s), 1845(w), 1380(w) cm"1. IR(CH 2C1 2): 1940(s), 1905(m), 1838(w) cm"1. IR(THF): 1940(s), 1905(s), 1830(m), 1380(w); 1885(s), 1770(br) cm"1. Persistent attempts at the c r y s t a l l i z a t i o n of t h i s product were unsuccessful; hence no fur t h e r characterization was performed. 2.2.8 Preparation of [MeGapz 3]Mo(C0) 2 (T] 2-C0Me) Na+MeGapz3Mo(C0)3 + Mel T H F > MeGapz 3Mo(C0) 2(n 2-C0Me) + Nal To a THF so l u t i o n containing the MeGapz 3Mo(C0) 3 (1.28 mmol) anion as i t s Na + s a l t was added excess Mel in the same solvent. The resu l t i n g dark orange-red reaction mixture was then s t i r r e d f o r about 2 days at which stage the i r spectrum of the mixture showed new bands in the V ^ Q region of the spectrum at ~1970, 1920 and 1855 cm"1, in addition to the V ^ Q bands c h a r a c t e r i s t i c of the MeGapz 3Mo(C0) 3 anion i n THF. A f t e r s t i r r i n g the mixture f o r another 2 days, a new weak absorption band appeared at ~1570 cm"1. The bands observed at 1970, 1920 and 1955 cm"1 presumably emanated from the presence of a transient a-methyl intermediate 'MeGapZg- Mo(C0)3Me' in s o l u t i o n . However, the presence of the bands due to the MeGapz 3Mo(C0) 3 anion in s o l u t i o n , even a f t e r s t i r r i n g f o r ~4 days, is probably i n d i c a t i v e of a low y i e l d of t h i s reaction in THF. The solvent and the unreacted Mel were then removed under vacuum. The resulting dark- red residue was extracted with CH 2C1 2 and f i l t e r e d . An equal amount of hexane was added to the CH 9C1 9 f i l t r a t e . Upon evaporation of the mixed 33 CHgClg/hexane solvents, a i r - s e n s i t i v e brick-red c r y s t a l s of the product were obtained in ~30% y i e l d . Anal. Calcd. For [MeGapz 3]Mo(C0 ) 2 (r i 2-C0Me): C, 34.95; H, 3.12; N, 17.48. Found: C, 35.10, H, 3.16 N, 17.15. IR(CH 2C1 2): 1980(s), 1855(s), 1570(w) cm"1. 1H NMR (dg-acetone, 80 MHz): T ( C H 3 ) 2 C 0 = 7.89 ppm, 9.30s (Ga-Me); 3.63t, 3.53t (pz-H 4); 2.46d, 2.24d (pz-H 5); 2.06d, 1.95d (pz-H 3); 6.60s (-COMe). ( J H C C H = ~2 Hz for pz protons.) Pyrazolyl ring protons appeared in a 2:1 r a t i o . MS: P +, P-Me+, P-C0+, P-C0-Me+, P-2C0 +, P-3C0+, and P-3C0-Me+ (P = parent) ion signals were displayed. 2.2.9 Attempted Preparation of [MeGapz 3]Mo(C0) 2(T) 2-C0Ph) + THF 9 Na MeGapz 3Mo(C0) 3 + PhCOCl — — — > [MeGapz 3]Mo(CO) 2(n -COPh) + NaCl ~*C 0 Excess benzoyl chloride in THF was added portion-wise to a THF solution of the Na +MeGapz 3Mo(C0) 3 (~0.35 mmol) s a l t . The reaction mixture was heated for ~2 h at which stage the i r spectrum of the dark solution indicated the complete consumption of the MeGapz 3Mo(C0) 3 anion. The solvent was then removed under vacuum. Hexane was added to the r e s u l t i n g dark o i l and slowly poured o f f . The dark s o l i d residue l e f t behind in the flas k was extracted with CH 2C1 2 and f i l t e r e d . Work-up of the CH 2C1 2 f i l t r a t e containing the extracts afforded dark blue c r y s t a l s of the product in very low y i e l d . The very low y i e l d (<5%) of t h i s product discouraged r e p e t i t i o n of t h i s experiment. However the y i e l d was s u f f i c i e n t for obtaining an i r spectrum. IR(CH 2C1 2): 1965(s), 1820(s), 1535(w) cm" 1 . 34 2.2.10 Preparation of [MeGapz 3]Mo(C0) 3Et Na MeGapz 3Mo(C0) 3 + EtBr — [ M e G a p z 3 ] M o ( C 0 ) 3 E t + NaBr A 50-fold excess of EtBr in THF was added dropwise to a solution of the Na +MeGapz 3Mo(C0) 3 (~0.68 mmol) s a l t in the same solvent. The mixture was s t i r r e d f o r ~1 day at room temperature followed by another day of s t i r r i n g at reflux temperatures, after which the solvent was removed in vacuo. The re s u l t i n g residue was extracted with benzene. Evaporation of the benzene solvent from the extracts resulted in a dark-brown sticky s o l i d . Recrystal1ization out of CH^Cl 2/hexane mixed-solvents afforded reddish-brown s o l i d s of the product in low y i e l d s . The compound i s unstable even under inert conditions either as a s o l i d or in s o l u t i o n . Anal. Calcd. For [MeGapz 3]Mo(C0) 3Et: C, 36.39; H, 3.44; N, 16.98. Found: C, 36.55, H, 3.28, N, 16.33. IR(CH2C1 2 ) : 1970(s), 1930(s), 1820(s) cm"1; 1890(s), 1755(br) cm"1. 1H NMR (d g-acetone, 270 MHz): (CH 3) 2C0 = 7.89 ppm; 9.53s (Ga-Me); 3.81 (pz-H 4); 2.36 (pz-H 5); 1.97 (pz-H 3) 8.15br (Mo-Et-C_H_3); 6.32br (Mo-Et-C_H_2). ( J H C C H - unresolved for pz protons.) Excessive fragmentation i n d i c a t i v e of thermal decomposition was observed in the mass spectrum of t h i s compound. However, weak signals corresponding to the P-3C0-Et + ion were observed. 35 2.2.11 Attempted Preparation of [MeGapz 3]Mo(C0) 3X (X = Br, I) Bromine (0.14 g, 1.7 mmol) in THF was reacted with Na +MeGapz 3Mo(C0) 3 (0.85 mmol) s a l t in THF. The reaction mixture was s t i r r e d overnight and the s o l u t i o n i r spectrum of the mixture at th i s stage showed three new V^Q _I bands at 2010, 1975, 1930 cm as expected f o r the product. Solvent removal in vacuo, extraction of the residue with Q-^C^ and recrystal 1 i z a t i o n from CH2C12/hexane mixed solvents gave a yellow s o l i d . The i r spectrum of the yellow s o l i d showed three bands (2010, 1980, 1900 cm"1, CH 2C1 2; 2010, 1975, 1930 cm"1, THF) in the v C Q region of the spectrum. The *H nmr spectrum of th i s yellow s o l i d product in both CDC1 ̂ and dg-acetone indicated decomposition of the expected [MeGapz 3]Mo(C0) 3Br compound. Repeated attempts at obtaining a n a l y t i c a l l y pure samples of the product were unsuccessful. S i m i l a r l y , reaction of iodine (0.108 g, 0.85 mmol) dissolved i n MeCN with an equimolar amount of Na +MeGapz 3Mo(C0) 3 s a l t in THF gave a dark red s o l i d . The i r spectrum of the s o l i d product showed three V^Q bands as expected f o r the product but repeated r e c r y s t a l 1 i z a t i o n out of CHgC^/hexane solvent mixtures did not y i e l d an a n a l y t i c a l l y pure compound. IR(THF): 2015, 1972, 1928 cm"1; IR(CH 2C1 2): 2015, 1978, 1925 cm"1. 1H NMR (dg-acetone, 80 MHz): T ( C H 3 ) 2 C 0 = 7.89 ppm, 9.59s (Ga-Me); 3.87br (pz-H 4); 2.38br (pz-H 5); 2.03br (pz-H 3). 36 2.3 Results and Discussion 2.3.1 M+LMo(C0)~ (L = MeGapz3, MeGa(3,5-Me 2pz) 3; M+ = Na +, E t 4 N + , HAsPh*) s a l t s The physical phenomenon of ion-pair interactions of group 1 and 2 cations with the carbonyl oxygen of t r a n s i t i o n metal carbonylates has been w e l l - documented. For example, the cr y s t a l structures of [CpMo(C0)3] 2Mg 2 +(C 5H 5N) 4 [67], and [(Co(salen)) 2Na +Co(CO)~THF] [68] have ?+ indicated interactions of the t r a n s i t i o n metal carbonylates with the Mg and Na + cations in the above complexes. A very common mode of preparation of t r a n s i t i o n metal carbonyl anions for further synthetic purposes i s by metal amalgam, or d i r e c t metal reductions of the metal carbonyl precursors in basic, low p o l a r i t y , donor solvents, t y p i c a l l y THF. Tran s i t i o n metal carbonylate anion/alkali or al k a l i n e earth cation interactions occur quite extensively in these systems. The f i r s t i r spectroscopic evidence for ion-pairing between alkali-metal cations and metal carbonyl anions in solvents of moderate p o l a r i t y was reported sometime ago by Edgell et a l . [69]. Since that o r i g i n a l report and subsequent work on the Na +Co(C0) 4 [70] s a l t , analyses of THF-solution V^Q i r spectra have been employed quite successfully to unravel alkali-metal cation interactions with CpFe(C0) 2 [71,72], and CpMo(CO)" (M = Cr, Mo, W) [73] anions. Infrared spectroscopy in the v r n region i s p a r t i c u l a r l y valuable in the study of 37 interactions involving d i r e c t contact of anion(s) and cation(s) e s p e c i a l l y where the geometry of the free carbonylate anion i s perturbed by the cation. The LMo(C0) 3 (L = MeGapz3, MeGa(3,5-Me 2pz) 3) anions have been prepared and i s o l a t e d as t h e i r sodium Na +, tetraethylammonium E t 4 N + , and triphenylarsonium HAsPh^ s a l t s . The i r spectra of the s a l t s in Ch^Clg solution displayed two strong bands in the V ^ Q region, consistent with a symmetrical C 3 y structure (A + E modes) as expected for the free anions. However, in THF solut i o n , three strong bands were observed f o r the Na + s a l t s . As an i l l u s t r a t i v e example, the solution i r spectra of the M +[MeGapz 3Mo(C0) 3]" (M + = Na +, E t 4 N + , HAsPhJ) sa l t s in the v C Q region are shown in figure 11. The presence of three bands in THF i s suggestive of C g symmetry for the anion of the Na +MeGapz 3Mo(C0) 3 s a l t in THF. Since for C s symmetry (2A 1 + A" modes), three bands are expected in the v C Q region of the spectrum, evidently the i n i t i a l C 3 v symmetry of the free MeGapz 3Mo(C0) 3 anion has been reduced to C g symmetry upon perturbation by the Na + cation in THF. A comparison of the V ^ Q values for the M +LMo(C0) 3 s a l t s (Table 1) shows the presence of a low frequency band for the Na +LMo(C0)Z s a l t s in THF. 38 Figure 11. Ir spectrum of M MeGapzoMofCO)? salts in the vCO region. a. M = Na+ in THF. b. M+ = Na+ in CH 2C1 2. c. M+ = Et 4N + in CH 2C1 2. d. M+ = HAsPhJ in CH 2C1 2. 39 Table I. v C Q (cm - 1) Infrared Data for M +LMo(C0) 3 (L = MeGapz3, MeGa(3,5-Me2pz) M+ = Na +, E t 4 N + , HAsPh* s a l t s ) . COMPOUND SOLVENT A' A l A" E A' (CO««-M +) Na +MeGapz 3Mo(C0) 3 THF CHgCl 2 1895 1888 1775 1760 1720 Na+MeGa(3,5-Me2 pz) 3Mo(CO) 3 THF CHgCi 2 1890 1885 1765 1745 1710 Et 4N +MeGapz 3Mo(C0) 3 THF CH 2C1 2 1890 1890 1765 1760 HAsPh 3MeGapz 3Mo(C0) 3 THF CH 2C1 2 1890 1890 1755 1750 HAsPh^MeGa(3,5-Me2pz)3- Mo(C0)~ THF CH 2 C 1 2 1885 1885 1750 1740 40 The low frequency band observed in THF i s i n d i c a t i v e of a carbonyl oxygen perturbed by the Na + cation in an int e r a c t i o n of the type Mo-C0"'Na +. Such an in t e r a c t i o n would lead to a collapse of the 'E' vib r a t i o n of the symmetry of the unperturbed anion (figure 12a) to give the 'A'" and A' contact modes of the Cs symmetry of the perturbed anion as shown in figure 12b. Me Me <0f)O> M o " AK <0(p> Mo Na '3v A, • E C R : A' • A* • A'lcontact) rigure 12. Proposed structures for the interactions of MeGapz-jMofCO)^ anion with Na cation i n THF solut i o n , a. Unperturbed anio b. Perturbed anion. n. In t h i s type of ion-pairing external to the carbonylate coordination sphere, substantial n-electron density i s expected to reside in the region 41 of the lone pa i r s on the oxygen i nvo l ved in the i n t e r a c t i o n [ 74 ] . A mo lecu la r o r b i t a l d e s c r i p t i o n of the CO e l e c t r on dens i ty in t h i s i n t e r a c t i o n i s shown i n f i g u r e 13a. In the p i c t u r e , the Na + c a t i on i s p o s i t i o ned f o r maximum i n t e r a c t i o n wi th the e l e c t r on dens i ty i n both the a and % o r b i t a l s . In any case, whether the arrangement i s of a l i n e a r type ( f i g u r e 13b), or non - l i nea r ( f i g u r e 13c ) , t h i s i n t e r a c t i o n would, of course , tend to inc rease the CO bond order i n the non - i n t e r a c t i ng Mo-CO groups wi th concomitant decrease in the CO bond order i n the Mo-C0*»#Na+ group. Th is p o l a r i z a t i o n of e l e c t r ons ( e l e c t r o n i c - d r i f t ) in the it-bonding mo lecu lar o r b i t a l , reg ion towards the Mo-C0*"Na + i n t e r a c t i o n s i t e , would * + r e i n f o r c e the dn;(Mo) ->• n (-C0**»Na ) backbonding component. The r e s u l t would be a decrease in the value f o r the CO group i nvo l ved in the ca t i on -an i on contac t i o n - p a i r i n g . A l t e r n a t i v e l y , the va lues f o r the CO groups not i nvo l ved in the i n t e r a c t i o n wi th the Na + c a t i on would be inc reased due to decreased compet i t i ve backbonding a b i l i t y by the CO groups f o r the Mo metal d e l e c t r o n s . The i r data f o r the Na +L .Mo(C0) 3 s a l t s i n THF (Table I) are in accord w i th t h i s ob se r va t i on . The s o l u t i o n i r spectrum of the [Et_,N] +[MeGapz 3Mo- (C0 ) 3 ]~ s a l t i n THF i s r a the r i n t e r e s t i n g s ince i t d i sp layed one st rong band a t ~1890 c m - 1 , and a second cont inuous broad band w i th two or more maxima centered at ~1765 c m - 1 . Th is observa t ion may be suggest ive of some pe r t u r ba t i on of the MeGapz^MofCO)^ anion C 3 v symmetry, emanating from some con tac t of the anion wi th the Et_jN+ c a t i o n i n THF s o l v en t . I t i s not c l e a r whether the Et^N + c a t i o n i n t e r a c t s w i th one or more carbonyl oxygens i n t h i s case . However, an X-ray c r y s t a l s t r u c t u r e study of the r e l a t e d 42 F i gu re 13. Proposed ca t i on (Na ) i n t e r a c t i o n wi th MeGapz3Mo(CO)o an ion , ex te rna l to the Mo coo rd i na t i on sphere in THF. a . M.O d e s c r i p t i o n of CO e l e c t r o n dens i t y , b. L inear i n t e r a c t i o n , c . Non- l i nea r i n t e r a c t i o n . [Me 4 N] + [CpCr(C0)3_" complex [75] has revea led some e l e c t r o s t a t i c i n t e r a c t i o n between the Me^N+ c a t i o n and the CpCrfCO)^ anion i n the above s a l t . The v. va lues f o r Na +MeGapzJto(CO); (1895, 1775, 1720 c m ' 1 , THF) 43 compare nicely with the V ^ Q values reported independently for the Na+CpMo- (CO)^ s a l t ( v C Q 1893, 1775, 1749 cm"1, pyridine) [67], and ( v C Q 1899, 1796, 1743 cm"1, THF) [73] respectively. Ion-pairing of t r a n s i t i o n metal carbonylates with cations in low p o l a r i t y solvents has been discussed i n recent review a r t i c l e s [76,77]. The 1H nmr spectrum of the [HAsPh 3] +[MeGapz 3Mo(C0) 3]~ s a l t in dg-acetone solution (figure 14) shows a l l the three pyrazolyl groups to be equivalent, displaying one signal for each of the pyrazolyl ring proton resonances. This i s i n d i c a t i v e of a symmetrical C 3 v structure f o r the anion in so l u t i o n . Similar *H nmr spectra were obtained for a l l the s a l t s studied in so l u t i o n . Detection of the asymmetry indicated by i r measurement of the perturbed anion (figure 12) in THF would be rather unlikely on the NMR time scale. Oxygen-17 and carbon-13 nmr spectral studies have indicated, however, that the l i f e t i m e of any one of the equally probable CpMo(C0) 2C0"»**Na + interactions in the Na +CpMo(C0) 3 s a l t solution i s shorter than the time scale of an observable event using nmr techniques (ca. 10 s) [77]. The lower l i m i t of the l i f e t i m e of a p a r t i c u l a r ion s i t e may be taken as the mean l i f e t i m e of a c o l l i s i o n p a i r , and i s on the order of 10" 1 1 s [78], obviously detectable by i r spectroscopy since the excited state l i f e t i m e of an i r experiment i s ~ 1 0 " U s [79].  45 2.3.2 [MeGapz 3]Mo(C0) 3H It was reported o r i g i n a l l y that a c i d i f i c a t i o n of [RBpz 3]Mo(C0) 3 (R = H, or py r a z o l y l , N 2C 3H 3) anions with acetic acid y i e l d e d the corresponding [RBpz 3]Mo(C0) 3H [53] acids. S i m i l a r l y , the weak acid CpMo(C0)3H i s readi l y obtained by protonation of the corresponding base CpMo(C0) 3 anion with acetic acid [55]. The preparation of [MeGapz 3]Mo(C0) 3H was attempted i n i t i a l l y by a c i d i f i c a t i o n of the Na +MeGapz 3Mo(C0) 3 s a l t solution with g l a c i a l a c e tic acid. Both the solution i r and *H nmr spectra of the yellow powdery s o l i d i s o l a t e d from the reaction indicated the presence of two compounds in solution in ~2:1 r a t i o (two Ga-Me signals were observed in the *H nmr spectrum in a 2:1 r a t i o ) . An incomplete protonation of the MeGapz 3Mo(C0) 3 anion was therefore suspected. A comparison of the i r and *H nmr data for the mixture, with those obtained for the Na +MeGapz 3Mo(C0) 3 s a l t (section 2.2.2), confirmed that the species responsible for the weaker set of signals emanated from the unreacted Na +MeGapz 3Mo(CO) 3 s a l t . The stronger set of signals was suspected to have arisen from the expected [MeGapz 3]Mo(C0) 3H hydride species. I f true, then the suggestion would be that the MeGapz 3Mo(C0) 3 anion is perhaps a weaker base than the analogous CpMo(C0) 3 anion, the implication being that under conditions where acetic acid s u f f i c e s to protonate the CpMo(C0) 3 anion, a stronger acid would be required to f u l l y protonate the MeGapz 3Mo(CO) 3 anion. To t e s t t h i s hypothesis, the reaction was repeated using the stronger ac i d , HCl(g), for a c i d i f i c a t i o n . An orange-yellow a i r - s e n s i t i v e s o l i d of 46 the desired complex, [MeGapz 3]Mo(C0) 3H, was obtained i n good y i e l d s . This compound displayed three strong bands and one weak band (1952, 1928, 1908, 1808 cm"1, hexane), in the /hydride region of the i r spectrum. These bands were close to those observed f o r one of the species suspected to be the hydride in the product mixture from the acetic acid reaction (1950, 1935, 1912, 1810 cm"1, CgH^; section 2.2.5). For a 7-coordinate compound such as [MeGapz 3]Mo(C0) 3H, three bands are expected i n the i r as b e f i t s a complex possessing C symmetry (2A1 + A"), consistent with a s 3:4 or 'four-legged piano s t o o l ' structure. The closely related CpMo(C0) 3H (2030, 1949, 1913 cm"1, CS 2) [55], and [HBpz 3]Mo(C0) 3H (2000, 1905, 1880 cm"1, Nujol) [53] compounds have been shown to display three v^g bands i n t h e i r i r spectra, without accompanying V M q ̂  bands in each case. Thus, one of the four bands observed f o r the [MeGapz 3]Mo(C0) 3H complex must be due to the Mo-H stretching v i b r a t i o n i n the molecule. The replacement of hydrogen by deuterium is a well-known technique f o r studying vibrations involving hydrogen. For a pure (where 'pure' implies that v i r t u a l l y a l l the potential energy involved in the corresponding normal mode is associated with the M-H bond stretching) stretching mode, sub s t i t u t i o n of deuterium f o r hydrogen attached to a metal results i n a s h i f t i n frequency by a f a c t o r of /2 or 1.414 ( i . e . , v (M-H)/v(M-D) ~ /2 Harmonic o s c i l l a t o r approximation) [80]. To es t a b l i s h which of the four bands observed f o r the [MeGapz 3]Mo(C0) 3H is due to the Mo-H stretching v i b r a t i o n , the deuteride species [MeGapz 3]Mo(C0) 3D was prepared and i t s solution i r obtained. The solution i r spectrum of the 47 molybdenum deuteride showed three bands (1935, 1910, 1845 cm" , CgHg) i n the v C Q region, and a weak band at ~1380 cm"1. Evidently, the band at ~1952 cm"1 in the [MeGapz 3]Mo(C0) 3H compound had s h i f t e d to lower wave- numbers by a factor of ~/2 j u s t by su b s t i t u t i o n of deuterium for hydrogen in the molybdenum hydride complex. Based on t h i s observation, the bands at 1952 cm"1 in the hydride complex, and 1380 cm"1 in the deuteride compound were assigned to Mo-H and Mo-D stretching vibrations r e s p e c t i v e l y . The i r spectrum of the [MeGapz 3]Mo(C0) 3H or [MeGapz 3]Mo(C0) 3D in THF solution i s i n t e r e s t i n g in that the bands of the MeGapz 3Mo(C0) 3 anion are also displayed. This i s thought to arise from the acid-base d i s s o c i a t i o n of the Mo-H or Mo-D bond in the polar and weakly basic THF solvent. This l a t t e r observation, in conjunction with the requirement of a strong acid to f u l l y protonate the MeGapz 3Mo(C0) 3 anion, suggests that [MeGapz 3]Mo(C0) 3H i s more protonic and les s hydridic than the analogous CpMo(C0) 3H. This conclusion i s at odds with the trend established e a r l i e r , i . e . , that MeGapz3 and HBpz 3 ligands are better electron-donors than the Cp" ligand as judged from the higher V^Q values for CpMo(C0) 3 anion compared to ei t h e r HBpz 3Mo(C0) 3 [53] or MeGapz 3Mo(C0) 3 [34] anions r e s p e c t i v e l y . If t h i s argument holds, then the only l o g i c a l conclusion i s that the six-coordinate MeGapz 3Mo(C0) 3 anion i s more stable with respect to i t s seven-coordinate hydride than i s the case in the analogous cyclopentadienyl system. Similar observations on the [HBpz 3]Mo(C0) 3H [60] compound were reported during the course of t h i s work. 48 The H nmr spectrum of the [MeGapz 3]Mo(C0) 3H in dg-acetone solution displayed one set of signals for the pyrazolyl ring protons, i n d i c a t i n g equivalent pyrazolyl rings in the above complex, and a Mo-H_ resonance at 18.5 T. It is evident, however, that the pz groups are inequivalent in the above complex ( i r showed three bands, consistent with a C $ symmetry for the complex). Since seven-coordinate complexes of this type are known for t h e i r f l u x i o n a l behaviour in solution, i t i s probable that the present compound i s stereochemically non-rigid in s o l u t i o n . Thus, interconversion of the CO ligands and the H ligand in the basal plane of the 3:4 structure of [MeGapz 3]Mo(C0) 3H, s i m i l a r to that observed for [HBpz 3]Mo(C0) 3X (X = H, Br, I) [60] must be operative in s o l u t i o n . Such interconversion of ligands in the basal plane of the 3:4 structure would at some stage place the H ligand along the Ga*»*Mo axis, giving a symmetrical 3:3:1 or 'capped-octahedral 1 structure, leading to the equalization of the environments of the pz rings; hence, one sees in the *H nmr experiment a dynamic C 3 v structure in s o l u t i o n . A l t e r n a t i v e l y , and perhaps less l i k e l y , i s a rapid rotation of the 'MeGapz3' moiety about the Ga«»»Mo axis, r e s u l t i n g in the equalization of the chemical environments of the pz groups. The Mo-]_ resonance for [MeGapz 3]Mo(C0) 3H appeared at 18.5 x , a considerably higher f i e l d p o s i t ion than those reported for CpMo(C0)3H (Mo-H -12.8 T) [55] and [HBpz 3]Mo(C0) 3H (Mo-H -13.3 x [53]; 13.02 T [60]), respectively. It i s d i f f i c u l t to r a t i o n a l i z e the large Mo-H chemical s h i f t difference between the [MeGapz 3]Mo(C0) 3H and the analogous CpMo(C0)3H and [HBpz 3]Mo(C0) 3H hydride species. It i s reasonable to speculate however, that since the MeGapz3 ligand i s a better electron-donor than the HBpzZ ligand [34], the proton in the present 49 [MeGapz-jlMofCCO^H compound most l i k e l y experiences greater shi e l d i n g e f f e c t from the e l e c t r o n - r i c h Mo center in the complex. It i s noteworthy that the cr y s t a l structure of the analogous (r]-C5Me5)Mo(C0)3H [81] compound has recently been reported by Leoni et a l . According to the authors, even though the H atom was not located, i t s position was i n f e r r e d from the geometry of the remainder of the molecule. The authors concluded that the geometrical facts obtained for the molecule were c h a r a c t e r i s t i c of a 'four-legged piano s t o o l ' geometry, and the 'hole' in the Mo atom coordination sphere at a basal vertex of the square pyramid was interpreted to be the r e s u l t of the 'missing' H atom. 2.2.3 [MeGapz 3]Mo(C0) 2(n 2-C0R) (R = Me, Ph) In an e a r l i e r report, i t was stated that the reaction of the HBpz 3Mo(C0) 3 anion with Mel gave the a-methyl complex, HBpz3Mo(CO)3Me [53]. Recently, Curtis et a l . communicated that the product of the above 2 2 reaction was in f a c t an TI -acyl complex [HBpz-^MofCO^Ti -COMe), no detectable quantities of the a-methyl complex being observed in s o l u t i o n . The i r and nmr for the complex were corroborated d e f i n i t i v e l y by an 2 X-ray structure determination showing the presence of an TI -acyl geometry in the s o l i d state [64]. In an attempt to c l a r i f y the above observations [53,64], the reaction of the i s o e l e c t r o n i c , i s o s t r u c t u r a l MeGapz 3Mo(CO) 3 anion with Mel was investigated. Of p a r t i c u l a r i n t e r e s t to us was the actual pathway of such a reaction. Is the a-methyl complex '[MeGapz 3]Mo(C0) 3Me' formed at some stage, and rearranged to give the 2 2 TI -acyl complex [MeGapz-,]Mo(CO)?(ii -COMe)? In order to observe t h i s 50 a-methyl i n t e rmed ia te , i f formed at a l l , the r ea c t i on was c a r r i e d out i n THF and monitored at room temperature by s o l u t i o n i r spect roscopy. The r e s u l t s obta ined i n d i c a t e t ha t the a-methyl complex i s formed but 2 rearranges to g ive the TI -acy l complex as the f i n a l product accord ing to the equat ions below:- Me6apz 3Mo(C0)3 + xsMel " * " > [MeGapz 3Mo(C0) 3Me] THF THF Y 2 [MeGapz 3 ]Mo (CO) 2 ( TI -COMe) Thus, a f t e r s t i r r i n g the r ea c t i on mixture a t room temperature f o r ~2 days, the i r spectrum of the s o l u t i o n showed three new bands at 1970, 1920 and 1855 c m " 1 . The three bands i n t e n s i f i e d a f t e r s t i r r i n g the r e a c t i o n mixture f o r another 2 days, a f t e r which add i t i o na l s t i r r i n g produced no change in the i r spectrum. The presence of the bands c h a r a c t e r i s t i c of the unreacted MeGapz 3Mo(C0) 3 an ion , even a f t e r s t i r r i n g the r e a c t i o n mixture f o r 4 days, i s i n d i c a t i v e of the low y i e l d of t h i s r e a c t i o n in THF at room temperature. The i r spectrum of the b r i c k - r e d c r y s t a l s i s o l a t e d from t h i s r ea c t i on showed two strong bands a t 1980, 1855 c m " 1 , and a weak band at 1570 c m " 1 . The v C Q bands a t 1970, 1920 and 1855 cm" 1 observed dur ing the r eac t i on are thought to have emanated from the presence of a t r a n s i e n t a-methyl 'MeGapz 3Mo(C0) 3Me' in te rmed ia te in s o l u t i o n . Th is pa t te rn i s c h a r a c t e r i s t i c of C g symmetry M(C0) 3X groups 51 which t y p i c a l l y show three V^Q bands in t h e i r i r consistent with the three (2A1 + A") modes expected. These v C Q values for 'MeGapz3Mo(C0)3Me' are compared with bands reported for related a-methyl complexes in Table II below. The presence of only two bands instead of the expected three bands in the (ii-CgHg)Mo(CO)3Me compound was interpreted as being due to the coincidence of two bands [55]. Table I I . Ir carbonyl stretching frequencies of some LMo(C0)3Me complexes (L = T) -CgHg, TI -CgNteg, T t - C g H 7 , HBpz 3, MeGapz 3). COMPOUND v c o ( c m - 1 ) Reference (Ti-C 5H 5)Mo(C0) 3Me 2020,1937 (CC* 4) 55 (Ti-C 5Me 5)Mo(C0) 3Me 2014,1929 (CgH 1 2) 82 (Tt-C 9H 7)Mo(C0) 3Me 2024,1945,1911 83 [HBpz 3]Mo(C0) 3Me 1985,1970,1948 1848,1830,1800 (Nujol) 53 [MeGapz 3]Mo(C0) 3Me 1970,1920,1855 (THF) This work The presence of two sharp bands at 1980 and 1855 cm - 1, and a weak band at 1570 cm"1 in the i r spectrum of the brick-red c r y s t a l s i s o l a t e d from the reaction of MeGapz 3Mo(C0) 3 with Mel, suggested that the present o compound i s indeed the TI -acyl compound with the formulation [MeGapz3]Mo- 2 2 (C0) 2(TI -COMe). Complexes are described as T) -acyl compounds eit h e r from 2 -1 structural determination or from i r spectra [VQ=Q (TI -acyl) < 1600 cm ] [84,85]. The metal-bonded T^-acetyl groups (TI1 M-C(O)R) usually absorbed at higher frequencies in the i r (>1600 cm"1) [85,86]. An X-ray st r u c t u r a l 52 determination of the i s o e l e c t r o n i c , i s o s t r u c t u r a l [HBpz 3]Mo(C0) 2(TI -COMe) has indeed revealed that this i s an TI -acyl complex [64]. The bands at 1983, 1856, 1570 cm"1 observed for t h i s complex are in close agreement with those observed for the present [MeGapz 3]Mo(C0) 2(Ti 2-C0Me) (1980, 1855, 1570 cm"1, CH^C^) complex. A plausible reaction sequence for the 2 formation of the present r\ -acyl complex i s shown in figure 15. In t h i s reaction sequence, CO migration with subsequent i n s e r t i o n into the Mo-Me bond of the a-methyl intermediate 'MeGapz3Mo(C0)3Me' would give the f i n a l 2 2 TI -acyl complex [MeGapz 3]Mo(C0) 2(n -COMe). Methyl migration onto the coordinated CO ligand i s equally v i a b l e . I t i s d i f f i c u l t to discuss which of the above routes is operative solely on the results obtained from t h i s experiment. Mechanistic studies on the c l a s s i c carbonylation of a l k y l - (pentacarbonyl)manganese by Calderazzo [85], have shown, that i t i s a c t u a l l y the a l k y l group that migrates and subsequently bonds to the carbon of a coordinated CO group. It i s cle a r , however, that a decarbonylation step was involved in the reaction of the HBpz 3Mo(C0) 3 anion with PhCOBr. By use of 1 3 C - l a b e l l e d PhC*0Br as the s t a r t i n g halide 2 2 species in t h e i r preparation of the TI -benzoyl [HBpz 3]Mo(C0 ) 2 (Ti -COPh) compound, Curtis et a l . [65] c l e a r l y established that the CO i n i t i a l l y on the metal i s l o s t in a decarbonylation process. In t h i s same paper, using the Extended Huckel Molecular Orbital (EHMO) treatment, the authors showed that there i s substantial double-bond character in the Mo=C(acyl) bond but a very weak Mo-0 bond; hence they suggested that the compounds [HBpz 3]Mo(C0) 2 (Ti 2-C0R) (R = Me, Ph) could be regarded as s t a b i l i z e d 16-electron Mo complexes. 53 1855 2000 i8oo 1600 (crrf1) Figure 15. Ir spectra of the carbonyl stretching frequency region observed during the reaction of MeGapz,Mo(CO); with Mel. 54 The H nmr spectrum of the present [MeGapz 3]Mo(C0 ) 2 (Ti -COMe) compound in dg-acetone solution (figure 16) i s consistent with the formulation as 2 an TI -acyl complex. The pyrazolyl protons of the ligand appear in a 2:1 pattern i n d i c a t i n g that two of the pyrazolyl groups are equivalent with one pyrazolyl ring being d i f f e r e n t . This i s suggestive of a stereochem- i c a l l y r i g i d structure in so l u t i o n . The acetyl COMe signal i s also displayed at 6.60 x . Much current i n t e r e s t has been directed towards the preparation and 2 chemical r e a c t i v i t y of the TI -acyl metal complexes partly due to the possible role of these species in the metal-catalyzed hydrogenation of carbon monoxide [87,88,89]. The f a c i l e alkyl to CO migration observed i n 2 the formation of the present [MeGapz 3]Mo(CO) 2 (Ti -COMe) compound and the 2 analogous [HBpz 3]Mo(CO ) 2 (Ti -COMe) [64] complex are unprecedented in ei t h e r CpMo(C0) 3R or CpMo(C0)3(a-C0R) chemistry. In fac t to our knowledge, the 2 hypothetical CpMo(C0) 2 (Ti -COR) (R = Me, Ph) complexes have never been 2 reported. However, a related tungsten complex, CpW(CO)(HCCH)(ri -COMe) [90] has been reported but no d e f i n i t i v e structural data are a v a i l a b l e . 2 Mass spectral data for the present [MeGapz 3]Mo(C0 ) 2 (Ti -COMe) complex displayed signals a t t r i b u t a b l e to the P +, P-Me+, P-C0 +, P-C0Me+, P-2C0 +, P-C0-C0Me+, P-3C0 + and P-2C0-C0Me+ (P = parent) ions r e s p e c t i v e l y . I n t e r e s t i n g l y , the above mass spectral data are in perfect agreement with 2 those reported for the i s o s t r u c t u r a l [HBpz 3]Mo(C0 ) 2 (T) -COMe) compound [65]. S i m i l a r l y , reaction of the MeGapz,Mo(CO)Z anion with PhCOCl gave a  56 dark blue product, a l b e i t in very low y i e l d , and characterized s o l e l y by i t s i r spectrum (1965, 1820 and 1535 cm - 1, CHgCl 2) as the T) 2-benzoyl product, [MeGapz 3]Mo(C0 ) 2 ( r ] -COPh). The i r data for t h i s compound compare well with that obtained for the complex s t r u c t u r a l l y characterized as [HBpz 3]Mo(C0 ) 2 ( r i 2-C0Ph) (1965, 1852, 1490 cm"1, CH 2C1 2) [65]. Thus, i t appears that the tendency of the a-donor electrons l o c a l i z e d at the nitrogen donor s i t e s of the ligands MeGapz^ and HBpz^, to promote octahedral coordination about the metal center and the s t e r i c bulk of the ligands favor the transformation of the seven-coordinate 3:4 structure of the LMofCO-jR (L = MeGapz^, HBpz^) species to the quasi-six-coordinate LMO(C0) 2(TI -COR) arrangement. In fa c t the HBpz^ ligand has been shown to promote six-coordination over seven-coordination in the successful i s o l a t i o n of the paramagnetic radical species, HBpz 3Mo(C0) 3* [38], and also in the HBpz 3Mo(C0) 3Br compound, where the four "legs" of the piano stool structure of the l a t t e r compound were found to be compressed together [60], Similar reasoning was invoked by Curtis et a l . [65] in r a t i o n a l i z i n g the transformation of [HBpz 3]Mo(C0) 3R to [HBpz3]Mo- (C0) 2(TI 2-C0R) (R = Me, Ph) complexes. 2.3.4 [MeGapz 3]Mo(C0) 3Et The reaction of the MeGapz 3Mo(C0) 3 anion with ethyl bromide afforded the metal-alkyl bonded [MeGapz 3]Mo(C0) 3Et de r i v a t i v e . The red-brown compound i s unstable and decomposes on storage after a few days even under i n e r t conditions. However, the decomposition i s much more rapid in so l u t i o n , the i r spectrum of solutions of t h i s ethyl derivative c l e a r l y 57 showing the presence of the anion MeGapz 3Mo(C0) 3. The solution i r spectrum of the ethyl compound in CHgCl 2 shows v C Q bands at 1970, 1930, 1820 cm'1, in addition to two v C Q bands at 1890 and 1755 cm - 1 respect- i v e l y . The l a t t e r two bands are c h a r a c t e r i s t i c of the MeGapz 3Mo(C0) 3 anion, presumably due to slow decomposition of the [MeGapz 3]Mo(C0) 3Et compound in solution probably by p-elimination (see scheme below). In the scheme, the decomposition of the Mo-Et bond involves a f a c i l e P-hydride migration to form the hydride [MeGapz 3]Mo(C0) 3H species with expulsion of ethylene. Dissociation of the Mo-H bond in the above hydride species ( s i m i l a r to that discussed in section 2.3.2, p 45) would then explain the presence of the MeGapz 3Mo(C0) 3 anion in the solution i r spectrum of the present [MeGapz 3]Mo(C0) 3Et compound. 58 It Is i n t e r e s t i n g that the i r spectrum of the c l o s e l y related [HBpz 3]Mo(C0) 3Et complex, reported e a r l i e r by Trofimenko, displayed f i v e v C Q bands (1980, 1960, 1850, 1835, 1816 cm"1, Nujol) [53], perhaps i n d i c a t i n g a s i m i l a r tendency to decomposition for the boron compound. The i r spectra of related cyclopentadienyl analogues are i n t e r e s t i n g in that they display only two strong bands. For example, two bands were observed for the CpMo(C0) 3Et (2016, 1932 cm"1, CC1 4) [55] and CpCr(C0) 3Et (2012, 1933 cm"1, pentane) [91] complexes respectively. The appearance of only two v C Q bands for the above cyclopentadienyl ethyl d erivatives may r e s u l t from the coincidence of two bands with s i m i l a r energies. The three bands observed in the region of the i r spectrum for the present [MeGapz 3]Mo(C0) 3Et compound are consistent with a C g symmetry (2A 1 + A"), and again suggestive of a 3:4 or 'four-legged piano s t o o l ' structure for the complex. The room temperature *H nmr spectrum of [MeGapz 3]Mo(C0) 3Et in dg-acetone solution (figure 17), displayed one set of signals for the pz protons, i n d i c a t i n g equivalent pz rings in the complex. The methyl and methylene protons of the ethyl group appeared as unresolved broad resonances centered at 8.15 x and 6.32 x respectively. The nmr spectrum of the present complex i s d i f f e r e n t from that reported for the analogous 59 [HBpz 3]Mo(C0) 3Et [53] complex. Although the methyl and methylene peaks of the l a t t e r complex appeared at 8.60 T and 6.38 x , respectively, the pz protons of the ligand appeared in a 2:1 pattern. This observation was interpreted by the author as i n d i c a t i v e of a stereochemically r i g i d structure with the ethyl group probably equidistant from two of the pz groups. There are perhaps three possible interpretations of the *H nmr results f o r the [MeGapz 3]Mo(C0) 3Et complex. F i r s t l y , a r i g i d 3:3:1 or "capped octahedral" structure with the Et group l y i n g along the p r i n c i p a l axis of the molecule. Such a symmetrical structure would give equivalent pz groups hence one set of signals are displayed f o r the pz protons. Secondly, a r i g i d 3:4 or 'four-legged piano s t o o l ' structure in which case rapid rotation of the 'MeGapz^' moiety about the Ga #»«Mo axis would lead to equivalent set of signals f o r the pz proton resonances. T h i r d l y , interconversions between the various isomers of the 3:4 structure of the [MeGapZgJ^COJgEt complex as shown i n figure 18, with an average 3:3:1 or C 3 v structure predominating due to a fluxional process in so l u t i o n . The f i r s t p o s s i b i l t y can be disregarded based on the i r data (three bands were observed in the i r; a r i g i d 3:3:1 structure i n s o l u t i o n would show only two bands). It is d i f f i c u l t , however, to discount e i t h e r the second or the t h i r d p o s s i b i l i t y since both are equally probable. However, from our experience with the related compound [MeGapz 3]Mo(C0) 3SnMe 2Cl [92], a complex which showed a t r a n s i t i o n from a 3:4 to a 3:3:1 arrangement in solu t i o n , the second p o s s i b l i t y most l i k e l y accounts f o r the observed *H nmr results in the present Mo-Et complex. In Figure 17. 270 MHz H nmr spectrum of [MeGapz 3]Mo(CO) 3Et in dg-acetone s o l u t i o n . 61 the Mo-Sn complex, the observed equivalence of the pz groups in the 3:3:1 arrangement was ra t i o n a l i z e d by a rotation of the 'MeGapz3' moiety about the Ga»**Mo axis. It is worthy of mention that Curtis and Shiu reported one set of equivalent pz rings and one set of equivalent CO groups in the lH and 1 3 C nmr spectra f o r the [HBpz 3]Mo(C0) 3X (X = H, Br, I) complexes in solu t i o n from room temperature to -80°C [60]. This observation was interpreted by the authors as being i n d i c a t i v e of dynamic C 3 y symmetry f o r the complexes in s o l u t i o n . A 3:4 structure f o r the boron complexes in the s o l i d state has been confirmed by a single crystal X-ray structural determination of the [HBpz 3]Mo(C0) 3Br compound by the same authors [60]. It is noteworthy that i n the CpMo(C0) 3Et compound the methyl and methylene group signals were unresolved, apppearing at 6.0 % [55], but i n the valence i s o e l e c t r o n i c CpCr(C0) 3Et complex [91], the methyl and methylene group signals were resolved, appearing at 8.89 % and 6.39 % respectively. The crystal structure of the CpMo(C0) 3Et complex has been determined, and is in accord with a 3:4 structure f o r t h i s complex in the s o l i d state [93]. The mass spectrum of [MeGapz 3]Mo(C0) 3Et was characterized by excessive fragmentation, i n d i c a t i v e of thermal i n s t a b i l i t y of the compound under the mass spectrometric conditions. The highest mass observed corresponded to trace signals a t t r i b u t a b l e to the P-3C0-Et + ion. A recent thermodynamic study of the CO-insertion into the Mo-R bond in the CpMo(C0)3R (R = H, Me, Et) compounds [94], has concluded that the Mo-Et bond is weaker than the Mo-Me bond (CO i n s e r t i o n into the Mo-Et bond is ~3 62 Mo o° Co E t C s b c d C Figure 18. Various isomers of the seven-coordinate [MeGapz 3]Mo(CO) 3Et. 63 kcal/mol more favourable than into the Mo-Me bond). However, methyl transition-metal derivatives which lack P-hydrogen atoms are k i n e t i c a l l y more stable than the ethyl compounds having p-hydrogen atoms. The combination of these factors i s probably responsible for the i n a b i l i t y to 2 form the r\ - COEt derivative as well as the excessive fragmentation pattern observed for the present [MeGapz 3]Mo(C0) 3Et compound in the mass spectrometer under electron impact conditions. 2.3.5 The [MeGapz 3]Mo(C0) 3X (X = Br, I) complexes The reaction of the molybdenum tricarbonyl anion with halogens, as shown below, MeGapz 3Mo(C0) 3 + X 2 T H F > MeGapz 3Mo(C0) 3X + X" X = B r 2 , I 2 was used in an attempt to prepare the [MeGapz 3]Mo(C0) 3X (X = Br, I) complexes. Yellow (X = Br) and dark red (X = I) s o l i d s , sparingly soluble in most organic solvents, were i s o l a t e d from these reactions. However, persistent attempts at obtaining a n a l y t i c a l l y pure products were consi s t e n t l y unsuccessful. This was very discouraging since both the *H nmr and i r spectra of the reaction products indicated the presence of the expected halide species. In contrast, the i s o e l e c t r o n i c , i s o s t r u c t u r a l [HBpz 3]Mo(C0) 3X (X = Br, I) compounds have been prepared and one of them (X = Br) s t r u c t u r a l l y characterized [60]. 2.4 Summary The LMo(C0) 3 (L = MeGapz 3 > MeGa(3,5-Me 2pz) 3) anions have been i s o l a t e d and characterized as t h e i r Na +, E t A N + and HAsPht s a l t s . Anion- 64 cation i n t e r a c t i o n of the MeGapz 3Mo(C0) 3 anion and the Na + cation in THF has been described and supported by i r spectroscopic evidence. This study represents the f i r s t i s o l a t i o n of the M +MeGapz 3Mo(C0) 3 s a l t s and, most importantly, the f i r s t reported evidence for the involvement of the LMo(C0) 3 anions in ion-pair interactions with the Na +cation in polar but weakly basic solvents such as THF. The hydride complex [MeGapz 3]Mo(C0) 3H has been prepared and characterized. It was found that a strong acid such as HCl i s required to protonate f u l l y the MeGapz 3Mo(C0) 3 anion under conditions where acetic acid s u f f i c e s to f u l l y protonate the analogous CpMo(C0) 3 anion. The Mo-H bond of the hydride species [MeGapz 3]Mo(C0) 3H dissociates in the polar but weakly basic solvent, THF. These re s u l t s taken together indicate the seven-coordinate [MeGapz 3]Mo(C0) 3H compound i s more d e s t a b i l i z e d with respect to i t s six-coordinated anion MeGapz 3Mo(CO) 3, than i s the case i n the analogous cyclopentadienyl system. The reaction of MeGapz 3Mo(CO) 3 anion with Mel was found to proceed p via a a-methyl 'MeGapz3Mo(C0)3Me' intermediate to give the TI -acyl 2 compound [MeGapz 3]Mo(C0) 2 (Ti -COMe) as the f i n a l product. The use of the poorly-coordinating solvent, THF as the reaction medium may have retarded the rate of the migratory CO i n s e r t i o n step in the above reaction, thereby allowing spectroscopic detection of the a-methyl intermediate. Migratory CO i n s e r t i o n reactions have been shown to be 'solvent-catalyzed' by Wax and Bergman [95]. The use of the polar, highly coordinating, acetoni- t r i l e , the reaction medium used by Curtis et a l . , may have catalyzed the 65 transformation of the 'HBpz3Mo(C0)3Me' a-methyl intermediate to [HBpz 3]Mo- (CO) 2(T I -COMe) [17] preventing d i r e c t observation of th i s intermediate. The transformation of the a-methyl 'MeGapz3Mo(C0)3Me' intermediate to 2 2 the TI -acyl derivative [MeGapz-^MofCO^Ti -COMe) i s believed to be favoured by a combination of the r e l i e f of s t e r i c congestion and the a b i l i t y of the a-donor electrons l o c a l i z e d on the nitrogens of the MeGapz3 ligand to promote octahedral coordination. The reaction of the MeGapz 3Mo(C0) 3 anion with EtBr y i e l d e d the seven-coordinate [MeGapz 3]Mo(C0) 3Et a-ethyl compound. No evidence for the 2 migratory CO in s e r t i o n into the Mo-Et to form an TI -COEt product was observed in t h i s reaction. I t i s not clear at th i s stage why an acyl complex was obtained with Mel but not with EtBr. The difference in r e a c t i v i t y between both of these alkyl haiides i s probably related to the Mo-R and Mo-CO bond strengths in the [MeGapz 3]Mo(C0) 3R (R = Me, Et) compounds. The rate of alkyl to acyl formation reaction i s known to be dependent on the strengths of the M-C (alkyl) and M-CO bonds in the st a r t i n g a l k y l complex [96]. It is worthy of mention, however, that the CpMo(C0)3R (R = Me, Et) compounds have been shown to react with phosphines and phosphites to af f o r d the stable c r y s t a l l i n e acyl complexes CpMo(C0) 2(DC0R (L = phosphines, phosphites) via CO ins e r t i o n reactions [97]. The preparation of the compounds [MeGapz 3]Mo(C0) 3X (X = Br, I) was attempted and spectroscopic evidence was gathered to support t h e i r formation. However, a l l attempts at obtaining a n a l y t i c a l l y pure products were unsuccessful. 66 CHAPTER III TRANSITION METAL - TRANSITION METAL BONDED COMPLEXES INCORPORATING PYRAZOLYL GALLATE/BORATE LIGANDS 3.1. Introduction The uninegative, t r i d e n t a t e , chelating RB(pz) 3 (R = H, a l k y l , a r y l , p y r a z o l y l ) , MeGapz^ and [Me 2Gapz(0CH 2CH 2NR 2)]~ (R = H, Me) ligand systems, being six- e l e c t r o n donors, are formally analogous to the cyclopentadienyl ion (Cp"). The r e a c t i v i t y of the LMo(C0) 3 anions of the above ligand systems toward a number of three electron donor ligands has been well documented [34,98-100]. Differences are sometimes observed between these ligand systems. While the compounds [MeGapz 3] 2Rh 2(n-C0) 3 [101], [HBpz 3] 2Rh 2(C0) 3 [102], and (r)-C 5H 5) 2Rh 2(^-C0)(C0) 2 [103] have s i m i l a r formulation, they display markedly d i f f e r e n t geometry. One obvious difference between the cyclopentadienyl and t r i s ( 1 - p y r a - z o l y l )borate/gal 1 ate ligands i s that while the former i s found in an extensive array of heterobimetallic complexes (compounds having metal-metal bonds between two d i s s i m i l a r metals), no such complexes are known for the tridentate polypyrazolylborate/gallate ligands. Much current research has been directed towards heterobimetallic complexes with t r a n s i t i o n metal-transition metal bonds, partly since i t i s reasoned that cooperative e f f e c t s between the d i f f e r e n t metal centers may influence the r e a c t i v i t y of such complexes [104-113]. For example, incorporation of both early and l a t e t r a n s i t i o n metals into the same 67 dinuclear compound might lead to systems capable of a c t i v a t i n g and p o l a r i z i n g substrates such as CO [114-118]. It i s also argued that studies of simple binuclear species may well provide useful clues in the design and synthesis of larger heterometallic c l u s t e r species with potential c a t a l y t i c applications [107,119,120]. The present study was undertaken with the primary objective of i s o l a t i n g heteronuclear (or mixed-metal) compounds incorporating the HBpz^, MeGapz^, and [Me 2Gapz(OCH 2CH 2NMe 2)]~ ligand systems in which d i r e c t t r a n s i t i o n metal-transition metal bonds are featured. The evidence for the presence of a metal-metal bond between the d i f f e r e n t metals i s based on the generally accepted c r i t e r i a for such bonds. That i s , a metal-metal distance close to the sum of the van der Waals r a d i i of the two metals as revealed by X-ray studies, spectroscopic evidence and/or the necessity of a metal-metal bond to provide each metal with a reasonable number of valence electrons (generally 16 or 18) [114]. A number of t r a n s i t i o n metal-transition metal bonded complexes has been prepared by the reaction of LMo(C0) 3 (L = HBpz 3, MeGapz3, Me,,Gapz- (0CH 2CH 2NMe 2)]~) anions with a variety of t r a n s i t i o n metal halide species. Results of the analyses confirm the presence of d i r e c t metal-metal bonds in these compounds in addition to carbonyl groups in a number of d i f f e r e n t bonding environments [76,121-123], Thus, these compounds constitute the f i r s t examples of heterobimetallie t r a n s i t i o n metal-transition metal bonded complexes incorporating the tridentate pyrazolylborate/gallate ligands. The Mo-Cu bonded complex provides a rare example of a 3:3:1 or 'capped octahedral 1 structure. 68 The [MeGapz 3]Mo(C0) 3Rh(PPh 3) 2 complex prepared and discussed in t h i s chapter, was tested as a potential reagent f o r the desulfurization of h^S at ambient temperatures, but no noticeable a c t i v i t y was observed. Parts of t h i s chapter have been published elsewhere [124]. 3.2 Experimental 3.2.1 Starting Materials The ligand Na+[Me2Gapz(0CH2CH2NMe2)]~ was prepared as a THF solution as described elsewhere [41]. K+HBpz~ [125], [CuCl (PPh 3)] 4 [126], PtCl(Me)(COD) [127], Co(N0) 2I [128], and Mn(C0) 5Br [129] were prepared by l i t e r a t u r e methods. RhCl(PPh 3) 3 (Strem chemicals), CuCl, HgCl 2 (M&B Chemicals), CO (Linde Union Carbide), ZrCl^, HfCl^ (Merck-Schuchardt) and H2S (Matheson), were used as supplied. 3.2.2 Preparation of LMo(C0) 3Rh(PPh 3) 2 (where L = [MeGapz3], [HBpz 3] or [Me2Gapz(0CH2CH2NMe2)]) Na +LMo(C0) 3 + RhCl(PPh 3) 3 T H F > LMo(C0) 3Rh(PPh 3) 2 + PPh 3 + NaCl The Na+L~ ligand solution (-0.40 mmol in 100 ml THF) was added to a s t i r r e d solution of an equimolar amount of (MeCN)3Mo(C0)3(~0.10 g, 0.40 mmol) in the same solvent. The i n i t i a l yellow coloration of the molybdenum complex in THF changed to an amber color on addition of the ligand solution. The reaction mixture was s t i r r e d f o r ~2 days during which time the amber color i n t e n s i f i e d . The resulting solution of Na +LMo(C0) 3 was reacted d i r e c t l y with RhCl(PPh 3) 3 (0.37 g, 0.40 mmol), 69 added as a slu r r y i n ~100 ml THF.. The dark red reaction mixture was s t i r r e d for a further 2 days and then the solvent was removed in vacuo to afford a dark red-black residue. The residue was extracted with benzene and the solution f i l t e r e d . Evaporation of the solvent from the f i l t r a t e gave an o i l y red-black material which was r e c r y s t a l l i z e d from CH 2C1 2/- hexane to give a i r - s t a b l e dark-red c r y s t a l s of the desired product in approximately 60% y i e l d . Physical data for these complexes are c o l l e c t e d in Table I I I . The mass spectrum of the complex [MeGapz 3]Mo(C0) 3- Rh(PPh 3) 2 displayed signals due to the P-PPh 3 ion (P + = parent ion) at -890 (based on 6 9Ga and 9 8Mo). In the preparation of the complexes LMo(C0) 3Rh(PPh 3) 2 (where L = [HBpz 3] or [MeGapz 3]), yellow c r y s t a l l i n e samples of the complex RhCl(C0)(PPh 3) 2 (Calcd.: C, 64.31; H, 4.34. Found: C, 63.73; H, 4.27; v C Q : 1980 cm"1 (CHgClg)) were also i s o l a t e d in -5% y i e l d . 3.2.3 Preparation of [MeGapz 3]Mo(C0) 3Cu(PPh 3) 4Na +[MeGapz 3]Mo(C0) 3 + [CuCl(PPh 3 ) ] 4 T H F > 4[MeGapz 3]Mo(C0) 3Cu(PPh 3) + 4NaCl A solution of the Na +[MeGapz 3]Mo(C0) 3 s a l t (1.7 mmol) in THF was prepared as described above (section 3.2.2). A one-quarter molar amount of [ C u C l ( P P h 3 ) ] 4 (0.61 g, 0.43 mmol) was added to the reaction mixture and produced an immediate rusty-orange color. This reaction mixture was s t i r r e d for approximately one day before the removal of solvent under vacuum. The r e s u l t i n g orange residue was extracted with CH 9C1 ? and the 70 mixture f i l t e r e d . Hexane was added to the f i l t r a t e and the mixed solvents allowed to evaporate slowly. Golden-yellow a i r - s t a b l e crystals of the product, [MeGapz 3]Mo(C0) 3Cu(PPh 3), were produced from the concentrated solutions in approximately 60% y i e l d . Pertinent physical data are included i n Table III f o r the complex. 3.2.4 Preparation of [MeGapz 3]Mo(C0) 3Cu(C0) Na +[MeGapz 3]Mo(C0) 3 + CuCl C Q^ 9^> [MeGapz 3]Mo(C0) 3Cu(C0) + NaCl THF A suspension of CuCl (0.08 g, 0.85 mmol) in THF was added to a so l u t i o n of Na +[MeGapz 3]Mo(C0) 3 s a l t (0.85 mmol) in THF and produced an immediate rusty-brown color. The reaction mixture was s t i r r e d f o r ~4 h. C0(g) was bubbled through the mixture f o r another 2 h at which stage the brown color had i n t e n s i f i e d . The solvent was then removed under vacuum and the residue extracted with benzene. Slow evaporation of the benzene f i l t r a t e , afforded the product, [MeGapz 3]Mo(C0) 3Cu(C0), as a yellow a i r - s t a b l e s o l i d i n low y i e l d s (~20%). Solutions of t h i s compound deteriorate slowly with time. Physical data f o r the complex are given i n Table III. 3.2.5 Preparation of [MeGapz 3]Mo(C0) 3Pt(Me)(PPh 3) Na +[MeGapz 3]Mo(C0) 3 + PtCl(Me)(COD) PPh 3 > -COD THF [MeGapz 3]Mo(C0) 3Pt(Me)(PPh 3) + NaCl 71 To a s t i r r e d solution of Na +[MeGapz 3]Mo(C0) 3 s a l t (0.350 mmol) in THF, was added PtCl(Me)(COD) (0.123 g, 0.350 mmol) dissolved i n THF. The reaction mixture was s t i r r e d f o r ~1 h, a f t e r which the s t a b i l i z i n g ligand PPh-j (0.091 g, 0.350 mmol) dissolved i n THF was added slowly to the mixture. The solution was then s t i r r e d f o r ~4 days. At t h i s stage, the so l u t i o n i r spectrum of the mixture indicated completion of the reaction. The solvent was then removed i n vacuo and the resulting brown residue extracted with CH 2C1 2. Hexane was added to the CH 2C1 2 f i l t r a t e (1:1), and evaporation of the CH2C12/hexane mixed solvents afforded dark brown cry s t a l s of the product in ~50% y i e l d . Elemental analysis and *H nmr data indicated a methylene chloride solvated complex as the product. The complex is stable as a s o l i d but unstable in solu t i o n . Anal. Calcd. For [MeGapz 3]Mo(C0) 3Pt(Me)(PPh 3)'CH 2Cl 2: C, 38.72; H, 3.13; N, 8.21. Found: C, 38.05; H, 2.90; N, 8.57. IR(CH 2C1 2) v C Q : 1900s, 1815s, 1785s cm"1. XH NMR (d g-acetone, 80 MHz): x ( C H 3 ) 2 C 0 = 7.89 ppm, 9.50s (Ga-Me); 4.18t (pz-H 4); 2.35d (pz-H 5); pz-H 3 obscured by PPh-; 9.45s (Pt-Me, J 1 Q , - 72 Hz); 2.13m, 2.50m (PPh,). J i y 5Pt-Me J 3.2.6 Preparation of [MeGapz 3]Mo(C0) 3M'Cl 3 (M1 = Zr or Hf) Na +[MeGapz 3]Mo(C0) 3 + M'C14 T H F > [MeGapz 3]Mo(C0) 3M'Cl 3 + NaCl An equimolar amount of M'Cl^ dissolved i n THF was added to a s t i r r e d s o l u t i o n of Na +[MeGapz 3]Mo(C0) 3 in the same solvent. The resulting cloudy Table III. Physical Data for the Complexes LMo(C0),MY. L M Y ANALYSIS CALCD/FOUND -1 vco(cm ) CH2C12 (Nujol) 1 a H nmr C H N GaMe pz-H3 pz-H4 pz-H5 PPh3 Other MeGapz3 Rh (PPh3)2 53.82 3.88 7.67 54.04 4.07 7.58 1873,1772,1758 (1897,1763,1744) b10.00s 2.70d 4.06t 2.89d 2.05m - 3.04m - cHBpz3 Rh 1.0 CH2C12 (PPh3)2 53.23 3.80 7.60 53.49 3.83 7.73 1871,1772,1757 (1863,1772,1766) b - 2.71d 4.24t 2.96d 2.09m 5.71s 3.04m CH2C12 solvate Me2Gapz(OCH2- CH2NMe2) Rh (PPh3)2 54.26 4.65 3.96 54.52 4.72 3.83 1852,1762,1737 e10.42s 2.32d 3.69t obscurred 2.60m 8.07s 10.29s by PPh3 7.09s signals NMe2 MeGapz3 Cu PPh3 46.96 3.41 10.61 46.91 3.43 10.54 1898,1798 (1890,1805,1780) e9.42s 2.02d 3.69t 2.19d 2.45m MeGapz3 Cu CO 30.15 2.15 15.08 30.78 2.85 15.45 2010,1955,1810 (1898,1880, 1772,1745sh) e9.45s 1.71d 3.66t 2.20d MeGapz3 Zr C l 3 29.64 2.34 29.00 2.87 2015,1920,1895 b10.10s 2.19d 4.18t 3.08d MeGapz3 Hf 1,5 C 6H 1 4 " 3 30.01 3.75 9.55 29.80 3.65 9.51 2015,1915,1895 b10.07s 2.15d 4.18t 3.09d a s=singlet, d=doublet, m=multiplet, sh=shoulder and t=triplet. b CgDg solution, TCgH6=2.84 ppm, JHCCH=2Hz for pz protons, c v B H = 2483 cm"1, e (CD3)2C0 solution, T(CH 3) 2C0 = 7.89 ppm, JHCCH=2Hz for pz protons. 73 reaction mixture was s t i r r e d f o r ~ 1 day a f t e r which the solvent was removed under vacuum. The residue was extracted with benzene (M1 = Zr), CH 2C1 2 (M1 = Hf) and the solu t i o n f i l t e r e d . Hexane was added to the CH 2C1 2 f i l t r a t e . Evaporation of the solvents afforded yellow s o l i d s of the products in ~60% y i e l d . The complexes are unstable as sol i d s and solutions deteriorate with time even under inert conditions, turning v i s i b l y from bright yellow to dark green. The complexes were i s o l a t e d as benzene (M' = Zr ) , and hexane (M1 = Hf) solvates respectively. Physical data f o r the complexes are compiled in Table II I . S a t i s f a c t o r y analysis f o r C and H were obtained f o r the Mo-Zr complex but the N analyses were inconsistent each time the sample was analyzed. 3.2.7 Attempted Preparation of [MeGapz 3]Mo(C0) 3Co(N0) 2 Equimolar amounts of Na +[MeGapz 3]Mo(C0) 3 s a l t solution and Co(N0) 2I were reacted i n THF. A f t e r s t i r r i n g the reaction mixture overnight, the solvent was removed under vacuum. Work-up of the resulting residue y i e l d e d orange crystals (~60% y i e l d ) . A n a l y t i c a l , i r and *H nmr data f o r th i s product were in perfect agreement with that of the compound [MeGapz 3]Mo(C0) 2N0 reported previously [34]. Anal. Calcd. For [MeGapz 3]Mo(C0) 2N0: C, 30.79; H, 2.57; N, 20.96. Found: C, 30.74; H, 2.65; N, 20.85. IR(CH 2C1 2) v C Q : 2020s, 1930s cm"1; v N Q : 1665s cm"1. lH NMR (CgDg, 80 MHz): xCgHg = 2.84 ppm, 10.03s (Ga-Me); 4.28t, 4.10t (pz-H 4); 3.10d, 2.95d (pz-H 5); 2.63d, 2.23d (pz-H 3). (JHCCH = ~ 2 , 0 H z f o r p z P r o t o n s - ) ( T n e Pyrazolyl protons appeared i n a 2:1 rat i o . ) 74 The mass spectrum of this compound displayed signals corresponding to the parent (P +) ion at -469, in addition to P-C0 +, P-2C0+, P-2C0-N0+ ion signals at 441, 413, and 383 mass units (based on ^ 9Ga and 9 8Mo), re s p e c t i v e l y . In order to obtain additional evidence as to the ide n t i t y of t h i s product, the reaction was repeated, t h i s time employing the Na+[MeGa(3,5- Me 2pz) 3]Mo(C0) 3 s a l t as the s t a r t i n g material. Again, orange c r y s t a l s were i s o l a t e d as the product of the reaction. Both the i r and *H nmr data for this compound were consistent with the formulation [MeGa(3,5-Me 2pz) 3]- Mo(C0) 2N0. IR(CH 2C1 2) v C Q : 2020s, 1920s; v N Q : 1650 cm - 1. *H NMR (CgDg, 80 MHz): xCgHg = 2.84 ppm, 9.75s (Ga-Me); 8.20s, 7.60s (pz-Me 5); 8.09s, 3 4 7.35s (pz-H ); 4.58s, 4.40s (pz-H ). (The pz proton and methyl resonances appeared in a 2:1 r a t i o . ) Thus, i t appears that the Co(N0) 2I reagent i s acting primarily as a n i t r o s y l a t i n g agent in these reactions. 3.2.8 Preparation of [MeGapz 3Mo(C0) 3] 2Hg 2Na +[MeGapz 3]Mo(C0) 3 + HgCl 2 T H F > [MeGapz 3Mo(C0) 3] 2Hg + 2NaCl One-half molar amount of HgCl 2 (0.115 g, 0.425 mmol) was added to a THF solution of the Na +[MeGapz 3]Mo(C0) 3 s a l t . An almost immediate cloudiness resulted i n d i c a t i n g p r e c i p i t a t i o n of NaCl. The yellow brown cloudy solution was s t i r r e d overnight and the solvent then removed in vacuo. The residue was extracted with benzene. The benzene f i l t r a t e was 75 concentrated and supernatant l i q u i d slowly poured o f f , leaving behind a i r - s e n s i t i v e off-yellow c r y s t a l s of the desired product in ~60% y i e l d . Anal. Calcd. For [MeGapz 3Mo(C0) 3] 2Hg: C, 27.56; H, 2.12; N, 14.84. Found: C, 28.05; H, 2.33; N, 14.99. IR(CH 2C1 2) v C Q : 2020m, 1985m, 1952m, 1890s cm"1. The *H nmr spectrum of the compound showed the presence of the Ga-Me signal but signals due to the pz protons were not observed in either CCUC or d..-acetone sol u t i o n . 6 6 6 3.2.9 Attempted Reaction of [MeGapz 3Mo(C0) 3] 2Hg with SnCl 2 [MeGapz 3Mo(C0) 3] 2Hg + Sn C l 2 T H F > [MeGapz 3Mo(CO) 3l 2SnCl 2 + Hg(s) Reaction of [MeGapz 3Mo(C0) 3] 2Hg (0.602 g, 0.530 mmol) with an equimolar amount of S n C l 2 in THF did not r e s u l t in the expected replacement reaction product [MeGapz 3Mo(C0) 3] 2SnCl 2. The solution i r spectrum of the dark orange brown s o l i d obtained from t h i s reaction was devoid of absorption bands in the region of the spectrum. Repeated r e c r y s t a l l i z a t i o n attempts with a variety of solvents f a i l e d to give the pure product, hence no further characterization was attempted. Although SnCl 2 i s known to i n s e r t into the M-M bonds in the dimers [CpFe(C0) 2] 2 and [CpMo(C0) 3] 2 [130], and the fac t that both Hg and Sn form strong covalent bonds with t r a n s i t i o n metals [131], the Mo-Hg-Mo bond in the present compound [MeGapz 3](C0) 3Mo-Hg-Mo(C0) 3[pz 3GaMe] may be too strong, thereby preventing the replacement of Hg with S n C l 2 in the complex. 76 3.2.10 Attempted d e s u l f u r i z a t i o n of H 2S by [MeGapz 3 ]Mo(C0) 3 Rh(PPh 3 ) 2 During the course of t h i s work, the f i r s t q u a n t i t a t i v e format ion of mo lecu la r hydrogen H 2 v i a ab s t r a c t i o n of s u l f u r from H 2 S by the dimer [ Pd 2 X 2 (n -dppm) 2 ] (X = C l , B r , I; dppm = b is(d iphenylphosphino)methane) [132] was communicated in p r e l im ina ry form. I t was the re fo re of i n t e r e s t to us to see i f the h e t e r o b i m e t a l l i c complex [MeGapz 3 ]Mo(C0) 3 Rh(PPh 3 ) 2 would e f f e c t a s i m i l a r t r ans fo rmat i on of H 2S i n t o molecu lar hydrogen H 2 accord ing to the scheme shown below. 77 A or E H 2 S low T. • LM • H 2 However, the r ea c t i on of the Mo-Rh complex w i th H 2S in CH 2 C1 2 a t ambient temperatures r e su l t e d i n a b lack s o l i d . The s o l u t i o n i r spectrum of the black s o l i d i n d i c a t ed a non-carbonyl con ta i n i ng compound as the product , wh i l e the *H nmr spectrum in CgDg or dg-acetone d i sp l ayed a sharp Ga-Me s igna l i n the ga l l i um a l k y l reg ion but there was no evidence of the p y r a z o l y l r i n g proton resonances in the spectrum. Attempts at the p u r i f i c a t i o n of t h i s product were unsuc ce s s f u l . 3.2.11 Attempted P repa ra t i on of [MeGapz 3 ]Mo(C0) 3 Mn(C0) 5 The MeGapz 3Mo(C0) 3 (0.51 mmol) anion was reacted wi th Mn(C0)gBr (0.154 g, 0.510 mmol) i n THF. The r eac t i on mixture was s t i r r e d fo r ~2 days, a f t e r which the so l ven t was removed under vacuum and the r e s u l t i n g res idue ex t r a c t ed wi th benzene. Evaporat ion of the benzene f i l t r a t e con ta i n i ng the e x t r a c t s gave a dark s t i c k y s o l i d . Th is dark s o l i d was 78 washed with hexane and the hexane-washings discarded leaving behind a dark s o l i d product. IR(C gH 1 2) v C Q : 2045, 2035, 2015, 2000, 1980, 1930, 1900, 1875 cm"1. *H nmr (C gD 6, 80 MHz): xCgHg = 2.84 ppm, 10.03 (Ga-Me); 4.05br (pz-H 4); 2.14br (pz-H ). The pz-H resonance was obscured by the solvent peak. A n a l y t i c a l l y pure samples of the product could not be obtained. 3.3 Results and Discussion 3.3.1 LMo(C0) 3Rh(PPh 3) 2 (where L = [MeGapz3], [HBpzg], or [Me 2Gapz(0CH 2CH 2NMe 2)]) The reactions of the anionic ligands [MeGapz 3]Mo(C0) 3, [HBpz 3]Mo(C0) 3, and [Me 2Gapz(0CH 2CH 2NMe 2)]Mo(C0) 3 with Wilkinson's c a t a l y s t , RhCl(PPh 3) 3, in THF resulted in the displacement of the chloro ligand, the formation of molybdenum-rhodium bonds, and the loss of triphenylphosphine from the rhodium coordination sphere. The c r y s t a l l i n e products are a i r - s t a b l e but solutions of the complexes decompose on exposure to a i r . In the experiment (using e i t h e r the [HBpz 3]Mo(C0) 3 or [MeGapz 3]Mo(C0) 3 anion) a small amount of the yellow c r y s t a l l i n e material RhCl(C0)(PPh 3) 2 was i s o l a t e d , presumably being produced via displacement of a triphenylphosphine from RhCl(PPh 3) 3 by a CO ligand of the molybdenum tricarbonyl anion s t a r t i n g material. Physical data for the complexes are l i s t e d in Table III p. 72. The i r v r n frequencies indicate the presence of both terminal and bridging 79 carbonyl groups i n the compounds. The room temperature H nmr data f o r the complexes containing the 'MeGapz^' and 'HBpz^' ligands suggest equivalence of the three pyrazolyl rings since only one set of signals i s observed f o r the ring protons (see figure 19). Low temperature spectra, although showing sharpening of these proton s i g n a l s , did not dis t i n g u i s h c l e a r l y any difference between the three pyrazolyl rings. The room temperature lti nmr spectrum of the [Me 2Gapz(OCH 2CH 2NMe 2)]Mo(C0) 3Rh(PPh 3) 2 complex is consistent with a f a c i a l coordination of the unsymmetric gallate ligand about the molybdenum center, with two Ga-Me and two N-Me signals being recorded. A complicated spectral pattern was observed f o r the -CH 2CH 2- group, lending f u r t h e r support f o r a f a c i a l organogal 1 ate ligand in t h i s complex. A meridional coordination of the unsymmetric ligand would give an A 2 X 2 pattern (two t r i p l e t s ) f o r the -CH2CH2~ group. The crystal structure of the [MeGapz 3]Mo(C0) 3Rh(PPh 3) 2 complex i s shown i n figure 20, and consists of discrete molecules separated by normal van der Waals distances. The structure c l e a r l y shows the presence of a terminal Mo-C(l)-0(l) unit, which, although s i g n i f i c a n t l y non-linear (173.9(5)A), is too f a r removed from the Rh center ( R h * " C ( l ) , 2.845(5)A) to suggest any bridging i n t e r a c t i o n . This CO ligand presumably accounts f o r the highest V^Q value recorded at 1879 cm - 1 (Nujol). The two remaining Mo-CO units, although d i f f e r e n t , are both c l e a r l y in bridging range of the Rh center with Mo-C-0 angles of 167.4(4) and 153.2(4)° and Rh«««C distances of 2.334(5) and 2.079(5)A respectively ( v C Q values 1758, 1772 cm' 1). The Ga»"Mo-Rh unit i s s i g n i f i c a n t l y non-linear i n t h i s structure with an angle of 161.59(3)° at Mo.  81 F i g u r e 20. M o l e c u l a r s t r u c t u r e o f [ M e G a p z 3 ] M o ( C 0 ) 3 R h ( P P h 3 ) 2 I t i s a l s o e v i d e n t t h a t t h e p y r a z o l y l r i n g s a r e n o n - e q u i v a l e n t i n t h e s o l i d s t a t e and t o e x p l a i n t h e s o l u t i o n *H nmr da t a i t i s n e c e s s a r y t o p o s t u l a t e t h a t a r a p i d f l u x i o n a l p r o c e s s i s t a k i n g p l a c e i n s o l u t i o n . Two such p r o c e s s e s may be e n v i s a g e d , one i n wh i ch t h e r e i s a r a p i d r o t a t i o n o f t he ' M e G a p z 3 ' U g a n d abou t t h e Ga-**Mo a x i s , and a n o t h e r , pe rhaps more l i k e l y , i n wh i ch t h e r e i s r a p i d i n t e r c h a n g e o f the d i f f e r e n t r o l e s o f the t h r e e CO l i g a n d s , w i t h c o n c o m i t a n t e q u a l i z a t i o n o f t he e n v i r o n m e n t s o f t he t h r e e p y r a z o l y l r i n g s . 82 The rhodium complex reported here is very similar to the one reported earlier by Carlton et a l . [104], These authors reported the structure of substitutes the 'MeGapz3' ligand of the present complex. The similarity of the two complexes illustrates once more the interchangeable ity of the 'n-CgHg' and 'MeGapz-j' ligand systems [34]. The Mo-Rh bond distance of 2.6066(5)A (cf. 2.588(1 )A in the Ti-CgHg complex) in the present compound is well below the estimated single bond distance of 2.8-3.OA and suggests some multiple bond character between the two transition metals. A bonding scheme similar to that proposed by Carlton et a l . would give an 18-electron count to the Mo atom and a 16-electron count to the Rh center. In this picture (figure 21), in addition to two bridging CO o Figure 21. Proposed bonding scheme for [MeGapz~]Mo(CO).,Rh(PPh.,) 83 groups, a double bond between the two t r a n s i t i o n metals, with one component being a Rh+Mo dative l i n k , constitutes an integral part of the overall molecular framework, and i s consistent with the observed Mo-Rh bond length in the present complex. Such dative interactions between metals have been proposed for a number of heterobimetallic complexes [107,133,134]. In keeping with the d i f f e r e n t roles of the carbonyl ligands, the C-0 bond lengths involving the 'bridging' ligands (1.190(5) and 1.175(6)A) are s i g n i f i c a n t l y longer than that of the unique terminal CO ligand (1.154(6)A). The Rh(p.-C0)2Mo framework possesses a b u t t e r f l y arrangement as seen in the analogous T)-CgHg complex [104] with the Rh-C-Mo dihedral angle of 156° compared with 161° in the Ti-CgHg compound. 3.3.2 [MeGapz 3]Mo(C0) 3Cu(PPh 3) The reaction of the [MeGapz 3]Mo(C0) 3 anion with the tetramer [ C u C l ( P P h 3 ) ] 4 in THF led to the i s o l a t i o n of a yellow c r y s t a l l i n e product which resulted from the displacement of the chloro ligand by the molybdenum tricarbonyl anion. The s o l i d material i s a i r - s t a b l e but solutions of the complex decompose rapidly on air-exposure. The physical data for the complex are compiled in Table III p. 72. The solution i r spectrum for t h i s complex shows two bands suggestive of a symmetrical C 3 v (A + E modes) structure for the complex. The positions of these bands (1898 and 1798 cm - 1, CH 2C1 2 solution) are s l i g h t l y higher than those observed for the uncomplexed anion [MeGapz3]Mo- (C0) 3 ( E t 4 N + s a l t ) (1890 and 1760 cm"1, CH 2C1 2 solution) and [MeGapz3]Mo- (C0) 3(HAsPh 3 s a l t ) (1890 and 1750 cm"1, CH 2C1 2 s o l u t i o n ) . These r e s u l t s are close in value to the v v i b r a t i o n s , recorded some time e a r l i e r by 84 (1897 and 1761 cm" , MeCN s o l u t i o n ) . In the s o l i d s ta te the Cu complex d i s p l a y s three bands i n the v C Q reg ion of the spectrum (1890, 1805 and 1780 c m " 1 , N u j o l ) . These cou ld a r i s e e i t h e r from a s p l i t t i n g of the ' E ' mode observed i n the s o l u t i o n spectrum, or from s l i g h t l y d i f f e r e n t pack ing environments f o r the two independent mo lecu les . From the c r y s t a l s t r u c t u r e data d i scussed below, one of the carbonyl groups of the unprimed molecule i s i nvo l ved i n a po s s i b l e C-H»»*0 i n t e r a c t i o n . The s o l i d s ta te i r spectrum of the uncomplexed carbonyl anion i n the s a l t [E t 4 N] + [MeGapz 3 Mo(C0) 3 ] d i sp l ayed two v C Q bands (1885 and 1730 c m " 1 , Nu jo l ) as expected from i t s C 3 y symmetry. These values again compare c l o s e l y w i th those repor ted f o r the analogous boron spec ies i n the s a l t [ E t 4 N ] + [ H B p z 3 M o ( C 0 ) 3 ] " (1890 and 1750 c m " 1 , KBr d i s c ) [ 60 ] . A s t r u c t u r e c o n s i s t e n t w i th the i r data of the Mo-Cu complex i s shown below. c o F igu re 22. P o s s i b l e s t r u c t u r e of the [MeGapz 3 ]Mo(C0) 3 Cu(PPh 3 ) complex as suggested by the i r da ta . 85 In the scheme, the Mo center retains an 18-electron count i f i t i s assumed that the CO groups of the molybdenum tricarbonyl anion retain t h e i r terminal character to the molybdenum atom. The single donor bond, Mo+Cu, between the two t r a n s i t i o n metals gives the Cu of the C u I ( P P h 3 ) + moiety a 14-electron count. The nmr data of [MeGapz 3]Mo(C0) 3Cu(PPh 3) in CgDg solution at room temperature are consistent with a symmetrical structure for the complex in sol u t i o n , being s i m i l a r to the nmr spectrum obtained for the uncomplexed anion [MeGapz 3]Mo(CO) 3 (HAsPh 3 s a l t ) (figure 14, section 2.3.1 p. 44) except for the presence of the PPh 3 ligand. Only one set of signals i s displayed for the pyrazolyl protons, i n d i c a t i n g equivalent pyrazolyl groups in the complex. The chemical s h i f t data from the *H nmr r e s u l t s compare quite well with those measured for the uncomplexed anion [MeGapz 3]Mo(C0) 3 (HAsPh 3 s a l t ) (see section 2.2.4 p. 29). The cry s t a l structure of the [MeGapz 3]Mo(C0) 3Cu(PPh 3) complex i s shown in fig u r e 23 and again consists of discrete molecules separated by normal van der Waals distances. The only intermolecular contact of any possible s i g n i f i c a n c e i s a C-H-'-O in t e r a c t i o n associating pairs of unprimed molecules about the inversion center at (0,0,1/2) [C(30)-H(30)-"0(2) (-x, -y, £-z), C«««0 = 3.424(9), H " » 0 = 2.55A, C-H«-«0 = 151°]. Apart from several small but s t a t i s t i c a l l y s i g n i f i c a n t differences between the corresponding bond lengths and angles (Appendix I ) , the most notable difference between the two c r y s t a l l o g r a p h i c independent molecules of [MeGapz 3]Mo(C0) 3Cu(PPh 3) i s 86 Figure 23. Molecular structures of [MeGapz3]Mo(C0)3Cu(PPh3). in the orientation of the PPh3 ligand. The conformation about the Cu-P in the molecule denoted by unprimed atom labels is about 4° from staggered compared with a value of 26° in the second molecule. The complex [MeGapz3]Mo(C0)3Cu(PPh3) is valence isoelectronic with the Rh compound, [MeGapz3]Mo(C0)3Rh(PPh3)2 discussed in section 3.3.1. However, the Cu complex is of much higher symmetry, possessing an approximate 3-fold axis along the near-linear C(4)-Ga»*»Mo-Cu-P atomic arrangement (mean angles: C-Ga«««Mo = 178.0(3), Ga»"Mo-Cu = 175.2(6), and Mo-Cu-P = 176.1(9)°). In this solid state structure the three pyrazolyl rings are equivalent, this being consistent with the *H nmr results already discussed above. The three CO ligands are essentially symmetrically placed with mean bond angles Mo-C-0 of 170.1(5), 170.7(1), and 172.1(6)A, Cu-C-0 of 87 117.0(1), 117.5(3) and 118.5(1)°, and mean bond lengths Mo-C of 1.973(7), 1.964(6) and 1.966(6)A, Cu« " C of 2.247(13), 2.298(23) and 2.415(5)A. These X-ray data, however, do suggest some in t e r a c t i o n between the Cu center and the carbonyl groups, although the exact nature of t h i s i n t e r a c t i o n is not cl e a r . Obviously the i n t e r a c t i o n is of a semi-bridging type since the Mo-C-0 angles are not f a r removed from l i n e a r . Numerous recent publications have documented and discussed d i f f e r e n t types of bridging CO interactions in heterobi metal l i e t r a n s i t i o n metal complexes [76,121-123,135 and references t h e r e i n ] . The present Cu compound does not appear to f i t into the category of a d i s t a l e l e c t r o n - r i c h metal center (the Cu center has a 14-electron count) * donating excessive charge into the CO TC o r b i t a l s [123]. Although, i f dTc-dTc bonding occurs between the Cu and the Mo centers, then an in t e r a c t i o n with the CO groups s i m i l a r to that postulated f o r the complex (ri-CgHg)2Mo2(C0)4 [76,136] may be possible. Such an in t e r a c t i o n between a * Mo-Cu rc-bond and the TC o r b i t a l of a CO ligand is shown schematically in figure 24 (p. 88). This type of i n t e r a c t i o n would, of course, tend to lengthen the C-O bond, and, with a mean C-O bond distance of 1.164A, the carbonyl ligands do display s l i g h t l y longer bonds than usually found f o r terminal CO ligands. The present structure does not meet the requirements f o r n-CO type bonding (figure 25 p. 89). These requirements were recently reviewed by Horwitz and Shriver [76]. Thus, the Cu-0 distances (2.945(5) - 3.143(5)A) are much longer than the Cu-C distances (2.234(6)-2.419(6)A), leading to Q values of approximately 2.14 - 2.16 (where Q = exp[D(Cu-C)/D(Cu-0)], D = distance). * F igure 24. P o s s i b l e i n t e r a c t i o n between the Mo-Cu n bond and the n o r b i t a l of the CO l i gand in the complex [MeGapz 3 ]Mo(C0) 3 Cu(PPh 3 ) . These Q va lues prov ide a measure of the extent of i n t e r a c t i o n of Cu w i th the C and 0 ends of the CO l i g a n d s , but are much lower than expected f o r a s t rong n-CO type i n t e r a c t i o n [ 7 6 ] . In a d d i t i o n , the f requenc ies observed f o r the complex are a l l much h igher than the expected value of ~1650 c m - 1 f o r a n-CO group. 89 M - M n - c o 0 = 2 2 - 3-3 fi= e x p [ D ( M - C ) / D ( M'-0)] (where D = distance) Figure 25. The structure of a l i n e a r semi-bridging CO type bonding. Perhaps the bonding in the present complex i s more subtle. In t h i s regard recent M.O. c a l c u l a t i o n s [105] on the complex (Ti-CgHg)(CO)Cr- (n-C0) 2Rh(C0 ) (T)-CgH 5), a complex o r i g i n a l l y postulated to contain a Cr+Rh donor bond in addition to semi-bridging CO interactions [107], suggest a strong i n t e r a c t i o n between the d i s t a l Rh center and the bridging CO ligands (Cr-CO (bridge), 1.902(7)A, Rh-CO (bridge), 2.200(7)A), with a net bond order close to zero between the metal atoms (Rh»--Cr, 2.757(2)A). Similar c a l c u l a t i o n s on the present system may well be invaluable in determining the major bonding int e r a c t i o n s responsible for the short Mo-Cu separation. 90 I t i s again interesting to compare similar complexes in this area. Carlton et a l . [104] have provided structural data on two different forms of the complex (ri-CgHgMCO^CufPPh-^, and suggest some semi-bridging interactions involving the two metals and two of the CO ligands. Three important differences occur with the [MeGapz3]Mo(C0)3Cu(PPh3) complex. F i r s t , only one PPh 3 ligand i s attached to the Cu center, making the molecule valence isoelectronic with the [MeGapz3]Mo(C0)3Rh(PPh3)2 compound (see section 3.3.1). Second, the present structure has three roughly equivalent CO groups, whereas in Carlton's tungsten compounds one of the three CO groups i s clea r l y terminal to tungsten. Third, the mean Mo-Cu distance of 2.513(9)A i s considerably shorter than either of the W-Cu distances of 2.771(1) and 2.721(1)A reported by Carlton et a l . Given that the r a d i i for Mo and W are very similar at ~1.61A (the M-M distances in (TI-C 5H 5)(C0) 3M-M(C0) 3(TI-C 5H 5) are 3.222(5)A for M = Mo [137] and 3.24(1) A for M = W [138]), these differences in bond lengths suggest a much stronger Mo-Cu interaction in the present complex. Indeed, the observed Mo-Cu distance i s s i g n i f i c a n t l y shorter than the estimated single Mo-Cu bond length of ~2.7 — 2.8A. Another noticeable difference occurs in the Cu-P distances in the two complexes. Thus the compound reported here displays a mean Cu-P distance of 2.196(3)A, somewhat shorter than the corresponding mean distance of 2.299(12)A reported for the two c r y s t a l l i n e forms of (Ti-C 5H 5)W(C0) 3Cu(PPh 3) 2. Recently, structural data were provided for the (ri-C5H5)Mo(C0)3Cu(tmed) (tmed = N, N, N', N'-tetramethylethylene- diamine, Me?NCH9CH?NMe?) compound by Doyle et a l . [139]. Even though 91 d i f f e r e n t metals were involved and the ligands on the Cu were quite d i s s i m i l a r both s t e r i c a l l y and e l e c t r o n i c a l l y , the overall geometry of the l a t t e r molecule i s s u r p r i s i n g l y s i m i l a r to that of one of the ( r i -Cr jHgMCO^CufPPh.^ isomers reported by Carlton. Both the Mo complex reported by Doyle and the W complexes reported by Carlton have 'four-legged piano s t o o l ' configurations about the Mo or W atoms in addition to a Cu-M (M = Mo or W) bond with a single terminal and two semi-bridging CO groups respectively. The Mo-Cu distance in the present [MeGapz 3]Mo(C0) 3Cu(PPh 3) complex i s comparable (2.513(9)A vs. 2.592A) to that of the (T)-C 5 H 5)Mo(C0) 3Cu(tmed) compound. The structures of the (ri-C 5H 5)W(C0) 3Au(PPh 3) [140] and [HBpz 3]Mo- (C0) 3Br [60] complexes are worthy of comparison with the [MeGapz3]Mo- (C0) 3Cu(PPh 3) structure. The W-Au compound displays an arrangement very d i f f e r e n t from that found for Mo-Cu complex. Thus, instead of a symmetrical structure analogous to that depicted in figure 23, with the 'ri-CgHg' ligand replacing the 'MeGapz3' ligand and the Au atom replacing the Cu atom the arrangement adopted i s that of a 'four-legged piano s t o o l ' , or a d i s t o r t e d square-pyramid with the (ri-CgHg)W unit at the apex and the three CO ligands and the Au(PPh 3) grouping occupying the basal p o s i t i o n s . A s i m i l a r structure, described as a 3:4 piano s t o o l , has been reported recently by Curtis and Shiu for [HBpz 3]Mo(C0) 3Br. These authors [60] mentioned that one of the i n t e r e s t i n g aspects which prompted t h e i r study, was the p o s s i b i l i t y of observing a capped octahedral (3:3:1) structure, since c a l c u l a t i o n s by Kubacek et a l . [141] had shown that t h i s arrangement represents a minimum in the potential energy surface for 92 analogous (T)-C 5H 5)MI_ 4 complexes whose global minimum (ground state) i s always the 'four-legged piano s t o o l ' , or 3:4 structure. It appears that the present copper complex [MeGapz 3]Mo(C0) 3Cu(PPh 3) c l o s e l y approaches t h i s 3:3:1 capped octahedral arrangement. F i n a l l y , the structure of the complex, ( r]-C 3H 5)Fe(CO) 3Au(PPh 3) [142] has many features s i m i l a r to those of the Mo-Cu complex presented here. It has been proposed that the bonding in t h i s iron complex re s u l t s from the Lewis base ( r)-C 3H 5)Fe(C0) 3 donating a pair of electrons to the Lewis acid Au(PPh 3) +, and does not necessarily involve any d i r e c t i n t e r a c t i o n between the Au atom and the CO ligand, the geometry of the complex being dictated by t r a n s i t i o n metal b a s i c i t y . If t h i s reasoning i s correct then the Au center attains a 14-electron count and the Fe-Au separation of 2.519(1)A results e n t i r e l y from the Fe+Au dative bond. 3.3.3 [Me6apz 3]Mo(C0) 3Cu(C0) The introduction of the HBpz 3 ligand in place of the CgHg ligand i s often known to have a s t a b i l i z i n g e f f e c t on the re s u l t i n g complex. For example, while the compound (T)-C 5H 5 )CUC0 [23] decomposes rapidly at room temperature even under i n e r t conditions, the analogous [HBpz 3]CuC0 [143] is a white, c r y s t a l l i n e a i r - and heat-stable s o l i d . Even though previous attempts at the i s o l a t i o n of the analogous [MeGa(3,5-Me2pz)3]CuC0 were unsuccessful [144], i t was open to speculation as to whether the 'MeGapz3 ligand would s t a b i l i z e the compound [MeGapz 3]Mo(C0) 3Cu(C0), e s p e c i a l l y with the re-acceptor CO ligand attached to the already e l e c t r o n - d e f i c i e n t Cu metal center (assuming the Cu has a 14-electron count s i m i l a r to that in the 'PPhJ derivative discussed in section 3.3.2). 93 Reaction of the [MeGapz 3]Mo(C0) 3 anion with CuCl in the presence of CO resulted in the yellow [MeGapz 3]Mo(C0) 3Cu(C0) compound as expected. A n a l y t i c a l , i r and *H nmr data for t h i s compound are c o l l e c t e d in Table III p. 72. The solution i r spectrum of t h i s compound showed three bands in the v C Q region of the spectrum (2020, 1955, 1810 cm"1, CH 2C1 2). Since the Cu metal would not be expected to donate electron density e f f i c i e n t l y * to the TC system of i t s CO ligand, the backbonding present in the Cu-CO li n k i s r e l a t i v e l y weak and consequently t h i s CO ligand probably accounts for the highest v C Q value at 2010 cm - 1. The two other bands at 1955 and 1810 cm~1must be due to the three symmetrically placed CO ligands on the Mo atom (assuming a complex i s o s t r u c t u r a l to [MeGapz 3]Mo(C0) 3Cu(PPh 3) which i s discussed in section 3.3.2). The s l i g h t l y higher v C Q values obtained for the present complex compared to those recorded for [MeGapz 3]Mo(C0) 3Cu(PPh 3) (1898 and 1798 cm"1, CHgCI 2), are presumably due to greater withdrawal of electron density from the Mo atom to the Cu atom in the [MeGapz 3]Mo(C0) 3Cu(C0) complex. The nmr data for t h i s Cu-CO complex are consistent with a symmetrical C 3 v structure in solution, and display one set of resonances for the pyrazolyl protons, being i n d i c a t i v e of equivalent pyrazolyl groups. These nmr data compare quite well with those recorded for the [MeGapz 3]Mo(C0) 3Cu(PPh 3) compound, and suggest t h i s complex may indeed be i s o s t r u c t u r a l to the 'Cu(CO)' de r i v a t i v e . Supportive evidence comes from the f a c i l e replacement of the CO ligand of the complex [MeGapz3]Mo- (COKCu(CO) by PPh-, ligand to give the [MeGapz,jMo(COkCu(PPh.J compound. 94 3.3.4 [MeGapz3]Mo(C0)3Pt(Me)(PPh3) The PtCl (Me)(COD) (COD = 1,5-cyclo-octadiene, TC-1 ,5-CgH^) complex, previously reported as unreactive toward RBpz3 l igand unless the very t ight ly-bonded COD ligand is f i r s t act ivated by a strong oxidant such as AgPFg via halogen abstraction [24,145], was recently shown to be reactive toward Me2Gapz2 l igand in the absence of a strong oxidant [146]. S imi lar ly the [MeGapz3]Mo(C0)3 anion reacted with PtCl(Me)(C0D) without the AgPFg, but in the presence of the s t a b i l i z i n g PPh3 l igand, to form the complex [MeGapz3]Mo(C0)3Pt(Me)(PPh3) with the el iminat ion of the chloro and COD l igands. Ana ly t i ca l , i r and *H nmr data for th is complex are l i s t e d in section 3.2.5 (p. 71). The i r spectrum of the [MeGapz3]Mo(CO)3Pt(Me)(PPh3) compound showed three strong bands (1900, 1815, 1785 c m - 1 , CH2C12) in the v C Q region. I f one terminal and two bridging CO groups are assumed to be present in th i s compound as suggested by the i r data, then a bonding scheme between the Mo atom and the Pt metal center can be proposed. Such a bonding scheme is shown in f igure 26. In th is bonding scheme, the Mo atom is provided with an 18-electron environment with the Pt having a 16-electron count i f a double Mo=Pt bond exists in the complex. This is not unusual, since 18-electron environments are common for Mo in low oxidation states, and s im i la r l y 16-electron states are not exceptional for P t ( I I ) complexes. The V^Q values recorded for the present Mo-Pt complex are in good agreement with those reported for the closely related compound s t ruc tu ra l l y characterized as (ri-C 5 H 5 )Mo(CO) 3 Pt(H)(PPh 3 ) 2 ( v C Q : 1916, 1828, 1797 cm" 1 , KBr disc) [112]. According to the X-ray structural 95 Figure 26. Proposed bonding scheme for [MeGapz 3]Mo(C0) 3Pt(Me)(PPh 3). analysis, the usual square-planar environment found for Pt(II) compounds i s strongly d i s t o r t e d in the l a t t e r complex. This arrangement was r a t i o n a l i z e d by the authors as being due to minimization of s t e r i c repulsions between the bulky phosphine groups in the complex. The room temperature *H nmr spectrum of the [MeGapz 3]Mo(C0) 3Pt(Me)- (PPh 3) complex in dg-acetone solution indicated equivalent pz groups i n the compound. A rapid rotation of the 'MeGapz3' moiety about the Ga*"Mo axis might explain the observed equivalence of the pz groups in so l u t i o n . The Pt-Me signal was also displayed in the spectrum at ~9.45-c with the 195 accompanying P t - s a t e l l i t e s ( J 1 Q c * 72 Hz). i y oPt-Me Unfortunately, the actual structure of the present Mo-Pt complex could not be confirmed since attempts to obtain c r y s t a l s suitable for X-ray structural studies were unsuccessful. 96 3.3.5 [MeGapz 3]Mo(C0) 3M'Cl 3 (M' = Zr or Hf) The reaction of [MeGapz 3]Mo(C0) 3 anion and M'Cl^ resulted in the mixed t r a n s i t i o n metal [MeGapz 3]Mo(C0) 3M'Cl 3 complexes. The compounds have been characterized by the usual physical methods (Table III p. 72) and are reasonably stable as s o l i d s under inert conditions, but decompose quite readily in s o l u t i o n . For example, a CgDg yellow solution of the Mo-Zr complex in a flame-sealed nmr tube turned dark green i n 3 days. The room temperature *H nmr spectra of the complexes indicated the presence of equivalent pz groups in s o l u t i o n . The *H nmr spectrum f o r the Mo-Zr complex in CgDg solution is shown in figure 27. Interestingly, the Mo-Hf complex had a *H nmr spectrum almost superimposable to that of the Mo-Zr compound, suggesting i d e n t i c a l structures f o r both complexes. A r i g i d symmetrical 3:3:1 structure (figure 28a) f o r the complexes in s o l u t i o n would be consistent with the observed equivalence of the pz groups indicated by the *H nmr spectrum. A l t e r n a t i v e l y , the *H nmr results can also be explained by a 3:4 structure (figure 28b) in which a rapid rotation of the 'MeGapz3' moiety about the Ga»**Mo axis might equalize the environments of the pz rings i n the complexes. As in the *H nmr results discussed above, the i r spectra of both the MorZr and Mo-Hf compounds were almost i d e n t i c a l , providing additional evidence f o r the s i m i l a r i t y in the structures of both compounds. The i r  98 3 : 3 : 1 3 : 4 Figure 28. Possible molecular arrangements for the [MeGapz3]Mo(C0)3M'Cl3 (M1 = Zr or Hf) complexes. spectra of the [MeGapz 3]Mo(C0) 3M'Cl 3(M' = Zr or Hf) complexes displayed three strong bands in the V ^ Q region. This i s suggestive of C g symmetry for the complexes in s o l u t i o n . A t y p i c a l i r spectrum for the [MeGapz3]Mo- ( C 0 ) 3 H f C l 3 complex i s shown in fig u r e 29. 99 1 2 2 0 0 2000 1900 1800 1700 1600 ( C T 1 ) Figure 29. Ir spectrum of [MeGapz 3]Mo(CO) 3HfCl 3 in CHgCl 2 s o l u t i o n . The presence of only terminal V ^ Q bands in the i r spectra of the complexes i s i n d i c a t i v e of d i r e c t Mo-M' (M' = Zr or Hf) interactions with no accompanying bridging CO ligands. However, a l l attempts at i s o l a t i n g c r y s t a l s suitable for X-ray c r y s t a l structure analyses were unsuccessful. This was rather discouraging e s p e c i a l l y since r e l a t i v e l y few derivatives of the titanium group metals with M-M' (M = Cr, Mo or W; M1 = T i , Zr or Hf) bonds have been reported in the l i t e r a t u r e [114]. 3.3.6 [MeGapz 3Mo(C0) 3] 2Hg An extensive array of metal-metal bonded dimers and c l u s t e r s are known in cyclopentadienyl chemistry. In contrast, only one such dimer, [HBpz Mo(CO) ] [38] i s known with the tridentate poly(1-pyrazolylJborate 3 2 2 100 ligand coordinated on more than one metal. Even more i n t e r e s t i n g i s the fact that X-ray structural analysis of th i s complex showed the presence of a Mo=Mo t r i p l e bond, rather than the expected Mo-Mo single bond in the elusive [HBpz-jMofCO^l, compound. Metatheticai reaction of the Na +MeGapz 3Mo(C0) 3 s a l t with HgCI 2 in THF resulted in the off-yellow, a i r - s e n s i t i v e compound [MeGapz 3Mo(C0) 3] 2Hg i n good y i e l d . The solution i r spectrum of th i s product showed four bands (2020, 1985, 1952, 1890 cm'1, CHgClg) in the terminal v C Q region. The above i r data are in good agreement to those reported for the [(ri-CgH,-)Mo(C0) 3] 2Hg compound by the two independent groups of Fischer and Noack [147], and by Burl i t c h and Fe r r a r i [148]. These authors interpreted t h e i r spectra in terms of a sing l e isomer with a skew configuration of the MO(C0) 3(TI-C 5H 5) groups about the Mo-Hg-Mo system in the [(n-C 5H 5)Mo- (C0) 3] 2Hg complex. The i r r e s u l t for the present [MeGapz 3Mo(C0) 3] 2Hg complex i s perhaps suggestive of the adoption of a 3:3:1 array for the MeGapz 3Mo(C0) 3 groups about a l i n e a r Mo-Hg-Mo backbone in the compound as shown below (fig u r e 30). 101 The mass spectrum of the compound [MeGapz3Mo(C0)3]2Hg was characterized by extensive low fragment ions, usually ind icat ive of thermal decomposition of the sample under electron impact (E. I ) condi t ions. However, the monomeric MeGapz3Mo(C0)3 ion fragment was observed at -467, in addit ion to MeGapz3Mo(C0)2, MeGapz3Mo(C0) +, and + 69 MeGapz3Mo fragment ions at 439, 411 and 383 mass units (based on Ga, go Mo), respect ively. The most intense signals in the spectrum were those a t t r ibu tab le to the MeGapz3Mo(C0)3Mo + fragment ion at -565. In te res t ing ly , a s imi lar fragmentation pattern has been observed in the mass spectrum of the compund [ (TI-C 5H 5 )MO (C0 ) 3 ] 2 by King [149] . The *H nmr spectrum of the [MeGapz3Mo(C0)3]2Hg complex is rather strange, in that a sharp Ga-Me signal was displayed in the gall ium alky l region but the pz proton resonances were not observed in ei ther dg-toluene, CgDg or dg-acetone so lu t ion . Attempts to obtain sui table c rys ta ls for X-ray crystal structure analyses were unsuccessful. 3.3.7 The '[MeGapz3]Mo(C0)3Mn(C0)5' Complex The preparation of the compound [MeGapz3]Mo(C0)3Mn(C0)g was attempted by the reaction of the MeGapz3Mo(C0)3 anion with Mn(C0)gBr. Spectral data obtained on the black so l id isolated from the reaction indicated the desired compound to be present in the product mixture. The solut ion i r spectrum of the black so l id in cyclohexane showed v C Q bands at 2045, 2035, 2015, 2000, 1980, 1930, 1900 and 1875 cm" 1 , ind icat ive of terminal ly bound CO groups. This v C Q pattern observed compares quite well to the bands reported for the analogous (r)-CcH,-)Mo(C0) ?Mn(C0) q complex [150,151]. 102 Unfortunately a l l attempts to i s o l a t e an a n a l y t i c a l l y pure sample of [MeGapz 3]Mo(C0) 3Mn(C0)g were unsuccessful and further investigations were not undertaken. It i s probable that the compound [MeGapz 3]Mo(C0) 3Mn(C0) 5 would adopt a capped octahedral arrangement, since severe s t e r i c i n t e r a c t i o n s between the pz rings and the CO groups attached to the Mn atom would most l i k e l y preclude the adoption of a 'four-legged piano s t o o l ' geometry of the (ri-C 5H 5)Mo(C0) 3Mn(C0) 5 complex [152]. 3.4 Summary The mixed t r a n s i t i o n metal complexes LMo(C0) 3Rh(PPh 3) 2 (L = [MeGapz-j], [HBpz 3], or [Me 2Gapz(OCH 2CH 2NMe 2)]) have been prepared and characterized. One of the above formally unsaturated b i m e t a l l i c complexes, [MeGapz 3]Mo(C0) 3Rh(PPh 3) 2, has been s t r u c t u r a l l y characterized, and displays one terminal and two bridging CO ligands. Double bonding between the Rh and Mo i s proposed with one of the bonds being a dative l i n k ( R h = ± M o ) . The heterobimetallic complexes [MeGapz 3]Mo(C0) 3CuY (where Y = PPh 3 or CO) featuring Mo-Cu bonds have also been prepared. The structure of the compound [MeGapz 3]Mo(C0) 3Cu(PPh 3) has been determined by X-ray cry s t a l structure a n a l y s i s . The three CO ligands are e s s e n t i a l l y terminally bound to Mo, with the p o s s i b i l i t y of some weak semi-bridging interactions with the Cu center. This Mo-Cu complex provides a rare example of a 3:3:1, or capped octahedral structure. The MeGapz 3Mo(C0) 3 anion reacted with PtCl(Me)(C0D) in the presence of the s t a b i l i z i n g PPh, ligand, eliminating the chloro and COD ligands to 103 give the heterobimetallic compound [MeGapz 3]Mo(C0) 3Pt(Me)(PPh 3), in which Mo-Pt bonding i s featured. Unfortunately the actual structure of t h i s complex could not be confirmed due to the lack of success in obtaining suitable c r y s t a l s for X-ray structural analysis. The complexes [MeGapz 3]Mo(C0) 3M'Cl 3 (M' = Zr or Hf) have been prepared from the reaction of the MeGapz 3Mo(C0) 3 anion and the M'Cl^ s t a r t i n g halide species. The presence of only terminally-bonded CO ligands i s i n d i c a t i v e of d i r e c t Mo-M' (M' = Zr or Hf) interactions in the complexes without accompanying bridging CO ligands. 104 CHAPTER IV TRANSITION METAL-GROUP 14 ELEMENT BONDED COMPLEXES INCORPORATING POLY(1-PYRAZOLYL)GALLATE LIGANDS 4.1 Introduction The r e a c t i v i t y of the tricarbonyl anions LMo(C0) 3 (L = [MeGapz^], [HBpz-j], or [Me2Gapz(0CH2CH2NMe2)]) toward a variety of t r a n s i t i o n metal halide species to produce novel t r a n s i t i o n metal-transition metal bonded compounds was explored i n Chapter III. As part of an on-going in v e s t i g a t i o n into the s i m i l a r i t y of the MeGapz 3Mo(C0) 3 anion and the analogous CpMo(C0) 3 anion, the behaviour of the MeGapz 3Mo(C0) 3 anion toward a number of group 14 ( S i , Ge, Sn) element organo halides has been studied; and the results from the study w i l l be discussed i n the present Chapter. Complexes containing d i r e c t t r a n s i t i o n metal-group 14 element single bonds have been i s o l a t e d , and confirmed s t r u c t u r a l l y f o r the complex [MeGapz 3]Mo(C0) 3SnPh 3 by means of a crystal structure determination in the s o l i d state. The complex [MeGapz-^MotCO^SnMegCl was shown to be non-rigid i n solution by a variable temperature *H nmr experiment. The 3:3:1 or capped octahedral arrangement has been demonstrated f o r the compound s t r u c t u r a l l y characterized as [MeGapz 3]Mo(C0) 3SnPh 3 in the s o l i d state. Thus, the above compound constitutes the f i r s t reported structure f o r complexes of the type LM(C0) 3M'R 3 (where L = ( T ) - C 5 H 5 ) , [HBpz 3], or [MeGapz 3]; M = Cr, Mo, or W; M' = S i , Ge, or Sn; R = alkyl or a r y l ) . 105 The preparation and characterization of the six-coordinate t r i - organotin complexes LSnMe^ (L = [MeGapz^], [MeGa(3,5-Me 2pz) 3]), and the [MeGapz3]SnMe2C1 compound are also described in this chapter. Parts of t h i s chapter have been published elsewhere [92]. 4.2 Experimental 4.2.1 S t a r t i n g materials Me-jSiCl, Me 3GeCl, Ph 3GeCl (Strem Chemicals), Me 3SnCl (Aldrich Chemicals), Ph 3SnCl (Alpha Chemicals) and Me 2SnCl 2 (PCA Chemicals) were used as supplied. 4.2.2 Preparation of [MeGapz 3]Mo(C0) 3SiMe 3 Na +MeGapz 3Mo(C0) 3 + Me 3SiCl T H F > [MeGapz 3]Mo(C0) 3SiMe 3 + NaCl To the molybdenum tricarbonyl anion MeGapz 3Mo(C0) 3 (0.35 mmol) in THF was added Me 3SiCl (0.038 g, 0.350 mmol) in the same solvent. The r e s u l t i n g reaction mixture was s t i r r e d overnight a f t e r which the solvent was removed in vacuo. The residue was extracted with benzene and f i l t e r e d . Evaporation of the benzene solvent from the f i l t r a t e containing the extract afforded yellow s o l i d s of the desired product in moderate y i e l d . This compound i s unstable as a s o l i d and in solution even under i n e r t conditions i f l e f t for a few days. Pertinent physical data for t h i s compound are l i s t e d in Table IV. 106 4.2.3 Preparation of [MeGapz 3]Mo(C0) 3GeR 3 (R = Me, Ph) Na +MeGapz 3Mo(C0) 3 + R 3GeCl T H F > [MeGapz 3]Mo(C0) 3GeR 3 + NaCl Me 3GeCl (0.13 g, 0.85 mmol) was added to a s t i r r e d solution of the Na +MeGapz 3Mo(C0) 3 (0.85 mmol) s a l t in THF. The reaction mixture was s t i r r e d overnight a f t e r which the solvent was removed under vacuum. The resulti n g orange residue was extracted with benzene and f i l t e r e d . The benzene solution containing the extracts was then concentrated to give orange needles of the desired product [MeGapz 3]Mo(C0) 3GeMe 3 in moderate y i e l d . The compound [MeGapz 3]Mo(C0) 3GePh 3 was prepared s i m i l a r l y using Ph 3GeCl as the s t a r t i n g material. Orange crystals of this product were i s o l a t e d in approximately the same y i e l d . Both of the above Mo-Ge complexes are a i r - s e n s i t i v e solids and deter i o r a t i o n of the compounds occurs slowly in so l u t i o n . Physical data f o r the complexes are coll e c t e d in Table IV. 4.2.4 Preparation of [MeGapz 3]Mo(C0) 3SnMe 3 Na +MeGapz 3Mo(C0) 3 + Me 3SnCl T H F > [MeGapz 3]Mo(C0) 3SnMe 3 + NaCl The Na +MeGapz 3Mo(C0) 3 (0.353 mmol) s a l t solution in THF was reacted with an equimolar amount of Me 3SnCl (0.070 g, 0.353 mmol) in the same solvent. The cloudy, dark orange, reaction mixture produced was s t i r r e d f o r ~2 days a f t e r which the solvent was removed i n vacuo to afford a dark 107 orange-brown o i l y residue. This residue was extracted with n-hexane and f i l t e r e d . Upon slow evaporation of the solvent from the f i l t r a t e , dark orange c r y s t a l s of the desired product were recovered i n ~70% y i e l d . The compound is stable under nitrogen but decomposes slowly on exposure to a i r . A n a l y t i c a l , i r and *H nmr data f o r the complex are compiled in Table IV. 4.2.5 Preparation of [MeGapz 3]Mo(C0) 3SnMe 2Cl Na +MeGapz 3Mo(C0) 3 + Me 2SnCl 2 T H F > [MeGapz 3]Mo(C0) 3SnMe 2Cl + NaCl An equimolar amount of Me 2SnCl 2 (0.193 g, 0.880 mmol) dissolved i n THF, was slowly added to a THF solu t i o n of the Na +MeGapz 3Mo(C0) 3 (0.880 mmol) s a l t . The i n i t i a l amber-yellow color of the s t a r t i n g molybdenum tri c a r b o n y l anion darkened s l i g h t l y during the reaction. The reaction mixture was s t i r r e d overnight a f t e r which the solvent was removed in vacuo. The result i n g orange residue was extracted with benzene and f i l - tered. Slow evaporation of the solvent from the f i l t r a t e y i e l d e d yellow c r y s t a l s of the desired product from concentrated solution i n ~50% y i e l d . Pertinent physical data f o r t h i s complex are included i n Table IV. 4.2.6 Preparation of [MeGapz 3]Mo(C0) 3SnPh 3 Na +MeGapz 3Mo(C0) 3 + Ph 3SnCl T H F > [MeGapz 3]Mo(C0) 3SnPh 3 + NaCl To a s t i r r e d THF solu t i o n of the Na +MeGapz 3Mo(C0) 3 (0.353 mmol) s a l t was added an equimolar amount of Ph 3SnCl (0.136 g, 0.353 mmol) dissolved 108 in the same solvent. The r e s u l t i n g cloudy reaction mixture was s t i r r e d for 2 days a f t e r which the solvent was removed in vacuo. The dark yellow residue remaining was extracted with CH 2C1 2 and f i l t e r e d . An equal amount of hexane was added to the f i l t r a t e and the mixed solvents were allowed to evaporate slowly. A chocolate-brown sticky s o l i d with some v i s i b l e tinge of yellow was l e f t behind. This mixture was washed with CHgCI 2 and the l i q u i d decanted o f f slowly to leave behind bright-yellow a i r - s t a b l e c r y s t a l s of the desired product [MeGapz 3]Mo(C0) 3SnPh 3 in approximately 40% y i e l d . Pertinent physical data for this complex are presented in Table IV. 4.2.7 Preparation of LSnMe3 (L = [MeGapz 3] or [MeGa(3,5-Me 2pz) 3]) Na +L~ + Me 3SnCl T H F > LSnMe3 + NaCl Na +MeGapz 3 (0.88 mmol) was reacted with Me 3SnCl (0.18 g, 0.90 mmol) in THF. The r e s u l t i n g cloudy solution was s t i r r e d overnight a f t e r which the solvent was removed under vacuum. The residue was then extracted with benzene and f i l t e r e d . Slow evaporation of the benzene solvent containing the extracts afforded c o l o r l e s s , a i r - s e n s i t i v e c r y s t a l s of the desired [MeGapz 3]SnMe 3 compound in ~50% y i e l d . The compound [MeGa(3,5-Me 2pz) 3]SnMe 3 was prepared in s i m i l a r y i e l d by an i d e n t i c a l procedure s t a r t i n g with the [MeGa(3,5-Me 2pz) 3]~ ligand. Solutions of the above complexes are unstable e s p e c i a l l y in chlorinated solvents (CH^CI 2, CHC13) and also in acetone. Anal. Calcd. For [MeGapz 3]SnMe 3: C, 34.71; H, 4.67. Found: C, 109 34.93; H, 4 .19 . lH NMR (CgDg, 270 MHz): xCgHg = 2.84 ppm, 10.45s (Ga-Me); 9.81s (Sn-Me 3 ); 4 .00t ( p z - H 4 ) ; 3.29d ( p z - H 5 ) ; p z -H 3 obscured by so l ven t peak. ( J u r r u ~ 2 Hz f o r pz p ro tons . ) ( J 1 1 Q , J 1 1 7 =50 M U t M i i y S n - M e A A / Sn-Me Hz.) Ana l . Ca l c d . For [MeGa(3,5-Me2pz)3]SnMe3»0.5 C g H 6 : C, 46.12; H, 6.29. Found: C, 46.34; H, 6.35. AH NMR (CgDg, 80 MHz): xCgHg = 2.84 ppm, 10.41s (Ga-Me); 9.83s (Sn-Me 3 ); 7.93s (pz -Me 3 ) ; 7.71s (pz -Me 5 ) ; 4.38s ( p z - H 4 ) . ( J 1 1 Q , J 1 1 7 = 50 Hz.) i i y S n - M e ^ 'Sn-Me S a t i s f a c t o r y ana l y s i s was obta ined f o r C and H in both complexes but the N analyses were i n c on s i s t e n t each time the compounds were ana lyzed . 4 .2 .8 P repara t i on of [MeGapz 3]SnMe 2Cl Na+MeGapz~ + Me 2 SnC l 2 T H F > [MeGapz 3]SnMe 2Cl + NaCl To M e 2 S n C l 2 (0.193 g, 0.880 mmol) d i s so l ved i n THF, was added a 50 ml a l i q u o t of the Na +MeGapz 3 (0.88 mmol) s a l t s o l u t i o n i n the same s o l v en t . The r e s u l t i n g r ea c t i on mixture turned c loudy as NaCl p r e c i p i t a t e d . To ensure complete p r e c i p i t a t i o n , the r eac t i on mixture was s t i r r e d overn igh t a f t e r which the so l ven t was removed under vacuum and the res idue ex t rac ted wi th C H 2 C 1 2 . Slow evapor t ion of the C H 2 C l 2 so lvent con ta i n i ng the e x t r a c t s , gave c o l o r l e s s f l a k y c r y s t a l s of the des i red [MeGapz 3]SnMe 2Cl compound i n ~50% y i e l d . Th is compound i s unstab le i n a i r and s low ly decomposes i n s o l u t i o n . 110 Anal. Calcd. For [MeGapz 3]SnMe 2Cl«0.5 CH 2C1 2: C, 29.27; H, 3.71; N, 16.39. Found: C. 29.51; H, 3.97; N, 15.87. AH NMR (CgDg, 80 MHz): xCgHg = 2.84 ppm. 9.95s (Ga-Me); 9.15s (Sn-Me 2); 3.98t (pz-H 4); 3.08d (pz-H 5); 2.43d (pz-H 3). ( J H C C H = 2 Hz f o r pz protons.) ( J n g Sn-Me J 1 1 7 = 50 Hz.) i A /Sn-Me 4.3 Results and Discussion Continued interest in the chemistry of compounds featuring group 14-transition metal bonds stems partly from the hope of fi n d i n g useful c a t a l y t i c systems and also from in t e r e s t in the s t r u c t u r a l , spectroscopic and bonding properties of th i s class of compounds [153,154]. The chemistry of the cyclopentadienyl compounds of group 14 elements has been studied quite extensively. In contrast, the use of poly(1-pyrazolyl )borate/gallate ligands in group 14 chemistry is v i r t u a l l y unexplored. Recently, the compound [HBpz 3]SnMe 3 was reported by Nicholson as the f i r s t s t r u c t u r a l l y characterized six-coordinate t r i a l k y l t i n complex [37]. The present work was therefore designed to extend the chemistry of the MeGapz3 ligand to include group 14 elements and furthermore to explore the r e a c t i v i t y of the MeGapz 3Mo(C0) 3 anion toward a variety of group 14 element halide species with the hope of i s o l a t i n g complexes featuring d i r e c t t r a n s i t i o n metal-group 14 element covalent bonds. The basis f o r th i s expectation is two-fold: f i r s t l y , the valence o r b i t a l s of group 14 2 3 3 elements are known to be e n e r g e t i c a l l y compatible with the d sp , dsp and dsp o r b i t a l s of t r a n s i t i o n metals and hence stable a-bonds are readily I l l formed between these elements and t r a n s i t i o n metal species [155]; and secondly the proposition that metals capable of forming c-bonded organometallic compounds would also be capable of forming covalent bonds to other metals [156,157]. Thus, 1:1 reactions of MeGapz 3Mo(C0) 3 anion with a variety of group 14 element organo halide species have y i e l d e d yellow-orange c r y s t a l l i n e products in which d i r e c t molybdenum-group 14 element covalent bonds are featured. The complexes are moderately a i r - s t a b l e s o l i d s , except for the Mo-Si and Mo-Ge derivatives which are unstable to a i r . Solutions of a l l the complexes deteriorate slowly with time. The presence of a d i r e c t single covalent bond between the molybdenum atom and the appropriate group 14 element ( S i , Ge, or Sn) i n question has been demonstrated unequivocally by the crystal structure determination of one of the complexes, [MeGapz 3]Mo(C0) 3SnPh 3. This l a t t e r compound represents the f i r s t s t r u c t u r a l l y characterized complex of the type LM(C0)3M'R 3 (where L = (i-CgHg), [HBpz 3], or [MeGapz 3]; M = Cr, Mo, or W; M' = S i , Ge, or Sn; R = Me or Ph), and also provides a rare example of a 3:3:1, or capped octahedral structure. 4.3.1 [MeGapz 3]Mo(C0) 3SiMe 3 The (ri-CgHg)(Mo(C0) 3SiR 3 (R = alkyl or aryl) complexes have been reported as being obtainable via s a l t elimination reaction of the (T)-C 5H 5)MO(C0) 3 anion with the alkyl or aryl s i l y l halide only in non-basic solvents such as cyclohexane [154]. An e a r l i e r attempt at obtaining these Mo-silyl derivatives by the same s a l t elimination route in basic solvents such as THF, proved unsuccessful [157]. However, these derivatives were obtained via an amine elimination reaction between 112 (TI-C 5H 5)MO(C0) 3H and Me 3Si-NMe 2in THF under CO pressure [158], and also from the reaction of K + ( T I - C 5 H 5 ) M O ( C 0 ) 3 and H 3SiBr in the absence of solvent [159]. The l a t t e r report attributed the unsuccessful metathetical reaction of (T)-C 5H 5)MO(C0) 3 anion and R^SiCl in THF to competition between the nucleophilic halide ion and the molybdenum tricarbonyl anion in t h i s solvent. Judicious s e l e c t i o n of solvents has been emphasized in the preparation of molybdenum-silicon compounds since polar solvents have the tendency to cleave the Mo-Si bond in the complexes [160,161,162]. The reaction of the MeGapz 3Mo(C0) 3 anion with Me 3SiCl in THF has y i e l d e d the yellow, a i r - s e n s i t i v e [MeGapz 3]Mo(C0) 3SiMe 3 complex. A n a l y t i c a l , i r and *H nmr data for t h i s compound are c o l l e c t e d in Table IV, p. 114. The i r spectrum of the [MeGapz 3]Mo(C0) 3SiMe 3 in CH 2C1 2 solution (figure 31), shows the presence of three strong terminal bands, suggesting a C g symmetry (2A' + A" modes) for the complex in s o l u t i o n . In t h i s regard, the present complex resembles the halogen derivatives (TI-C 5H 5)MO(C0) 3X (X = C l , Br or I) [55], and [HBpz 3]Mo(C0) 3X (X = Br or I) [60], but d i f f e r s from the methyl and ethyl derivatives (rt-C,-H5)Mo(C0)3R (R = Me, Et) [55], which show only two bands. The v C Q bands observed for the present [MeGapz 3]Mo(C0) 3SiMe 3 (2015, 1920, 1895 cm"1, CH 2C1 2) complex are in good agreement with those reported for the analogous (ri-CgHg)Mo- (C0) 3SiMe 3 (1974, 1955, 1890 cm"1, Nujol) [158] compound. The terminally bonded CO groups suggested by the i r data of the complex are i n d i c a t i v e of the presence of a d i r e c t single covalent bond between the Mo and Si atoms in the present [MeGapz 3]Mo(C0) 3SiMe 3 compound. 113 2000 1§feo 1600 ĉTn"1) F igure 31 . The v C Q reg ion of the i r spectrum of [MeGapz 3 ]Mo(CO) 3 SiMe 3 i n CH 2 C1 2 s o l u t i o n . The A H nmr spectrum of the present Mo-Si complex i n d i c a t ed equ i va l en t py r a zo l y l groups and hence i s suggest ive of a 3:3:1 symmetrical s t r u c t u r e f o r the complex i n s o l u t i o n , cont ra ry to the C g symmetry i nd i c a t ed by the i r r e s u l t s . There are two po s s i b l e exp lana t i ons f o r the *H nmr r e s u l t s : f i r s t l y , a symmetrical 3:3:1 arrangement i n s o l u t i o n would g ive equ i va l en t environments f o r the pz groups. Secondly, a 3:4 s t r u c t u r e i n which there i s r ap id r o t a t i o n of the 'MeGapz 3 ' grouping about the Ga»»»Mo ax i s would a l s o be c on s i s t en t w i th the observed equ iva len t environments f o r the pz groups i n s o l u t i o n . The l a t t e r p o s s i b i l i t y i s f u r t h e r supported by the i r r e s u l t s d i scussed above. Table IV. Phys ica l Data for [MeGapz,]Mo(C0),M'Y (M' = S I , Ge, Sn) . M' Y ANALYSIS CALCD/FOUND v ( c n f 1 ) CH.CI- (Nujol) *H nmr C H N GaMe M'Me p z - H 4 p z - H 5 p z - H 3 P h 3 SI Me 3 •0.17 C 6 H 6 36.97 3.99 15.22 37.15 4.00 14.80 2015,1920,1895 b 9 . 9 5 10.08s 4 .15t 3.05d 2.14d Ge Me 3 •1.0 C 6 H 6 39.92 4.08 39.78 3.84 2015,1920,1892 b 9 . 8 8 s 9.43s 4 .19t 3.08d 2.14d Ge P h 3 •2.0 C 6 H 6 55.76 4.22 . 9.08 55.07 4.28 9.63 2015,1922,1898 b 1 0 . 1 0 s 4 .15t 3.04d 2.13d 2.38m 2.93m Sn M e 3 30.51 3.34 13.35 31.13 3.45 13.65 2020,1970,1870 a 9 . 8 6 s 9.01s 4 .09t 2.91d 2.36d J 1 i q , J 1 1 7 => 50 Hz l i 3 S n - M e 1 A ' S n - M e Sn Me 2 Cl 27.70 2.77 12.93 27.72 2.74 13.00 2018,1912,1890 (1989,1905,1880) A a 9 .93s 8.73s 4 .12t 2.95d 2.40d J 1 1 0 « 52 Hz, J 1 1 7 = 50 Hz i i ; , S n - M e 1 A , S n - M e BIO.00s 8.96s 4.19t 3.07d 2.17d 9.11s Sn P h 3 45.62 3.31 10.50 44.98 3.32 10.42 (1990,1900,1875) 1.86d b 9 . 9 8 s 4 .14t 2.73d 2.12d 2.65m 2.93m a In <L-toluene ( t M = 7.91 ppm) J u r r M * ^.0 H z ^ o r P z P r o t o n s - b In CgDg s o l u t i o n ( T c h = 2.84 ppm) s = s i n g l e t , d • doub let , t = t r i p l e t , m = m u l t l p l e t A 3:3:1 s t r u c t u r e . B 3:4* s t ructure ( F i g . 36) 115 4 .3 .2 [MeGapz 3]Mo(C0) 3GeR 3 (R = Me, Ph) The r ea c t i on of the anion MeGapz 3Mo(C0) 3 wi th R 3GeCl (R = Me, Ph) ha l i d e spec ies a f fo rded the [MeGapz 3]Mo(C0) 3GeR 3 complexes as y e l l o w - orange, a i r - s e n s i t i v e s o l i d s . A n a l y t i c a l and spec t roscop i c data f o r the complexes are given in Table IV, p. 114. The s o l u t i o n i r spect ra of the complexes d i sp l ayed three s t rong v C Q bands suggest ive of C g symmetry (2A 1 + A") f o r the complexes i n s o l u t i o n . The bands observed f o r the present [MeGapz 3]Mo(C0) 3GeMe 3 (2015, 1920, 1892 cm" 1 , C H 2C1 £ ) and [MeGapz 3 ]Mo(C0) 3 GePh 3 (2015, 1922, 1898 cm" 1 , C H 2 C 1 2 ) complexes are i n good agreement w i th those repor ted f o r the analogous ( r i -C 5 H,-)Mo{C0) 3 GeMe 3 (1999, 1929, 1905 c m " 1 , CgHg) [163] and ( r i - C 5 H 5 ) M o ( C 0 ) 3 G e P h 3 (2008, 1925, 1918 c m " 1 , CCl^) [157] compounds, r e s p e c t i v e l y . For a l l of the above cyc l open tad ieny l Mo-Ge d e r i v a t i v e s , the authors concluded tha t there i s a d i r e c t cova len t bond between the Mo and Ge centers w i th no i n t e r a c t i o n s of the CO l i gands wi th the Ge atom. I t appears, l i k e l y tha t a s i m i l a r bonding arrangement i s ope ra t i ve in the present [MeGapz 3]Mo(C0) 3GeR 3 complexes based on the i r data obta ined f o r the compounds. The room temperature nmr spectrum of the [MeGapz 3]Mo(C0) 3GePh 3 i n CgDg s o l u t i o n i s shown in f i g u r e 32. Aga in , one set of s i g na l s was d i s p l ayed f o r the py r a zo l y l protons suggest ing equ i va l en t environments f o r the pz r i n g s . E v i d e n t l y , s i m i l a r r o t a t i o n of the 'MeGapz 3 ' moiety about the Ga*"Mo ax i s (see Sec t i on 4.3.1) might a f f o r d a r a t i o n a l e f o r the observed 1 H nmr r e s u l t s . A s i m i l a r ^ti nmr spectrum was obta ined f o r the [MeGapz 3]Mo(C0) 3GeMe 3 complex. These compounds [MeGapz 3]Mo(C0) 3GeR 3 (R = Me or Ph) p e r s i s t i n s o l u t i o n f o r only a few days. For example, the room 116 117 temperature H nmr spectrum of the same [MeGapz 3]Mo(C0) 3GePh 3 compound i n CgDg so l u t i o n , in a flame sealed nmr tube, showed new signals d i f f e r e n t from those displayed in the i n i t i a l spectrum a f t e r 5 days. These new signals are presumably due to peaks a r i s i n g from the decomposition of the sample in s o l u t i o n . Attempts to obtain c r y s t a l s suitable for X-ray cr y s t a l structure determinations were unsuccessful. 4.3.3. [MeGapz 3]Mo(C0) 3SnR 3 (R = Me, Ph) The reaction of the MeGapz 3Mo(C0) 3 anion with Me 3SnCl and PhgSnCl y i e l d e d yellow-orange c r y s t a l l i n e products of the Mo-Sn bonded species [MeGapz 3]Mo(C0) 3SnR 3. The complexes are moderately a i r - s t a b l e in the s o l i d state but solutions deteriorate on exposure to a i r . Ana l y t i c a l and spectroscopic data for these complexes are presented in Table IV p. 114. I t i s i n t e r e s t i n g to compare the compounds with those reported by P a t i l and Graham in which the MeGapz3 ligand i s replaced by the Cp~group [157]. In both series of compounds only terminal v C Q bands are displayed in the i r spectra, i n d i c a t i v e of d i r e c t Mo-Sn int e r a c t i o n without accompanying bridging CO ligands. In the case of the cyclopentadienyl complexes, three strong terminal CO bands were observed in each case whereas the two compounds reported here show d i f f e r e n t patterns. Thus, the 'SnPh3' complex gives one weak and two strong V^Q vibrations, whereas the 'SnMe3' complex displays one strong and two weak V^Q bands. The nmr data for the 'SnPh 3' and 'SnMe3' complexes show a l l three pyrazolyl groupings to be equivalent in solution, displaying only one set of signals for the pyrazolyl rings protons, and are hence i n d i c a t i v e of a symmetrical structure for the complexes. The room temperature *H nmr 118 spectrum of the [MeGapz 3]Mo(C0) 3SnMe 3 complex in dg-toluene solution i s shown in figure 33. The mass spectrum of the [MeGapz 3]Mo(C0) 3SnMe 3 compound displayed signals due to the P-3C0 + ion at m/e ~ 544, but signals due to the parent ion P + were not observed. In contrast, the mass spectrum of the [MeGapz 3]Mo(C0) 3SnPh 3 complex displayed the parent ion s i g n a l , P +, at m/e ~ 816, together with prominent signals due to the ions P-C0 +, P-2C0+, P-3C0 +, and P-3C0-Me+. Perhaps these variations r e f l e c t the greater thermal s t a b i l i t y of the 'SnPh3' compound over the 'SnMe3' deri v a t i v e under electron impact conditions. The chemistry of M-M' bonded derivatives (where M1 = Ge or Sn; M = Mo or W) has been studied quite extensively but, rather s u r p r i s i n g l y , no X-ray structural data have been reported for complexes of the type (r)-CgHg)M(C0) 3M'R 3 (where R = alkyl or a r y l ) , the molecular arrangements proposed for these species being based primarily on i r and *H nmr data [154]. The X-ray c r y s t a l structure of the complex [MeGapz 3]Mo(C0) 3SnPh 3 presented here represents what we believe to be the f i r s t reported structure of t h i s type, in which the [MeGapz 3] moiety replaces the ^-CgHg ligand in the general formulation given above. The X-ray structure analysis confirms the 3:3:1 arrangement predicted on the basis of the nmr data. The molecule, which has approximate £ 3 symmetry, i s shown in figure 34.  120 The structure i s s i m i l a r to that recently reported for the compound [MeGapz 3]Mo(C0) 3Cu(PPh 3) [124] (see also section 3.3.2 p. 86) but i s d i f f e r e n t from the 3:4 or 'four-legged piano stool 1 structures of the related molecules (n-C 5H 5)Mo(CO) 3Sn(Cl ) [ ( r i-C 5H 5)Fe(C0) 2] 2 [164], [HBpz 3]Mo(C0) 3Br [60], and (ri-C 5H 5)Mo(C0) 3Et [93]. The multi-metal species with the T)-C 5H 5 replacing MeGapz3 on Mo, and the [ ( r)-C 5H 5)Fe(C0) 2] groupings replacing the Me groups on Sn, may well be incapable of adopting a 3:3:1 structure due to the bulky Fe-containing substituents. The structure of the [MeGapz 3]Mo(C0) 3SnPh 3 complex c l e a r l y shows the presence of three terminal carbonyl groups with bond angles of 169.7(3), 172.1(3), and 172.7(3)° for the Mo-C-0 units, the s l i g h t deviations from 121 l i n e a r i t y being directed away from the Sn center and probably caused by the proximity of the phenyl groups on the Sn atom. The C-O bond distances of 1.154(4), 1.139(3), and 1.141(3)A are also in the range expected for terminal carbonyl groups and the Mo-C distances of 1.967(3), 2.000(3), and 1.994(3)A are consistent with a terminal CO bonding arrangement. The above parameters show that one of the carbonyl groups d i f f e r s s i g n i f i - cantly from the other two. This represents the most s i g n i f i c a n t departure from o v e r a l l C^ molecular symmetry and can be ascribed to a weak C -HvO hydrogen bond [C(10)-H(10) •••0(1) (x, 1/2-y, z-1/2), H---0 = 2.39, C««»0 = 3.326(4)A, C-H---0 = 162°, C-0--H = 156°] l i n k i n g molecules in i n f i n i t e chains extending along the b axis. A l l other intermolecular distances are greater than the sums of van der Waals r a d i i . The Ga««»Mo-Sn unit with an angle of 178.49(1)° i s e s s e n t i a l l y l i n e a r and as expected the planar pyrazolyl groups, whilst e c l i p s i n g the distant phenyl groups on Sn, are staggered with respect to the three CO ligands on the Mo center. The Mo-Sn distance of 2.8579(3)A observed for the present complex i s considerably shorter than the expected distance of 3.00A based on the sum of the covalent r a d i i (1.39 + 1.61 A) for the two atoms [93,137,165,166]. The distance i s , however, comparable to the f i r s t Mo-Sn distance reported (2.891(5)A) for the complex [(t)-C 5H 5)Mo(CO) 3]Sn(Cl)- [ ( r i-C 5H 5)Fe(C0) 2]2 [164]. As in the structure described herein, the Sn atom in t h i s multi-metal complex i s in a pseudotetrahedral environment. Cameron and Prout [167] have reported a Mo-Sn distance of 2.691(4)A for the complex ( r i-CgHg^MofSnBrgjBr in which the Sn atom i s in a d i s t o r t e d trigonal bipyramidal environment with a fourth, long, Sn»»»Br in t e r a c t i o n of 3.411A. A s i m i l a r environment for the Sn atom has been reported for 122 the complex (b ipy) (Cl )Mo(C0) 3 (SnMeC l 2 ) , i n which the Mo-Sn d i s tance of 2.753(3)A was i n t ep re t ed as i n d i c a t i v e of some m u l t i p l e bond cha ra c t e r [168] . The same authors reported the s t r u c tu r e of the t ungs ten - t i n complex (MeS(CH 2 ) 2 SMe)(C l )W(C0) 3 (SnMeCl 2 ) i n which the W-Sn d i s tance of 2.759(3) was argued to r e f l e c t the s i m i l a r i t y of the W and Mo cova l en t r a d i i [169] . In both of these s t r u c tu r e s there i s a b r i dg i ng Cl l i g and between the metal c en t e r s , w i th a long Sn-Cl d i s t an ce . 4 .3 .4 [MeGapz 3]Mo(C0) 3SnMe 2Cl The 1:1 r e a c t i o n of MeGapz 3Mo(C0) 3 anion and Me 2 SnC l 2 r e s u l t e d in the y e l l ow c r y s t a l l i n e product [MeGapz 3 ]Mo(C0) 3 SnMe 2 Cl. Th is complex i s a i r - s t a b l e in the s o l i d s ta te but s o l u t i on s de t e r i o r a t e s low ly w i th t ime. The s o l u t i o n i r spectrum of t h i s compound d i s p l a y s one weak and two s t rong v C Q v i b r a t i o n s (2018, 1912, 1890 cm" 1 , C H 2 C 1 2 ) . These v C Q va lues compare qu i t e we l l w i th those reported f o r the analogous ( r i - C 5 H 5 ) M o ( C 0 ) 3 S n M e 2 C l compound by P a t i l and Graham [157] . The presence of only te rmina l bands in the i r spectrum of the present [MeGapz 3]Mo(C0) 3SnMe 2Cl compound i s i n d i c a t i v e of d i r e c t Mo-Sn i n t e r a c t i o n wi thout accompanying b r i dg i ng CO l i g a n d s . However, the presence of three bands in the i r spectrum of the present complex i s suggest ive of a C g symmetry f o r the compound i n s o l u t i o n . The room temperature *H nmr spectrum of [MeGapz 3]Mo(C0) 3SnMe 2Cl i s i n t e r e s t i n g s ince i t changes wi th time and so l v en t . (F igure 35 shows the change, wi th t ime, i n the spectrum of the complex in dg- to luene . A s i m i l a r e f f e c t was observed us ing C f i D f i or CDClo as s o l v e n t s ) . Thus, 123 B JJ u r f 1 3 Figure 35, T T T lb r(ppm) Room temperature 80 MHz H nmr spectra of [MeGapz 3]Mo(C0) 3SnMe 2Cl, showing the change with time: i n i t i a l spectrum (top), a f t e r 1 day (middle), and a f t e r 5 days (bottom). (A) 3:3:1 structure, (B) 3:4 structure. 124 i n i t i a l l y the spectrum shows two 'sets' of signals. The most intense set of signals i s consistent with a symmetrical 3:3:1 or capped-octahedral structure as shown in figure 36A, s i m i l a r to that established for the 'SnPh3' derivative (see section 4.3.3, p. 117). In t h i s arrangement free r o t a t i o n about the Mo-Sn bond in solution would give the observed pattern of equivalent pyrazolyl signals and a s i n g l e t for the 'SnMe2' grouping. In the second 'set' of signals the two Sn-Me groups are non-equivalent and yet the pyrazolyl groups seemingly remain equivalent. This pattern i s d i f f i c u l t to r a t i o n a l i z e since even a s t a t i c 3:4, or 'four-legged piano s t o o l ' arrangement (figure 36B) would be expected to give inequivalent pyrazolyl groups, as well as possibly distinguishing between the two Me groups on the Sn atom. A rotation of the MeGapz^ moiety about the Ga»»*Mo axis might afford a rationale for the observed equivalence of the pyrazolyl groups in t h i s second arrangement. A s i m i l a r rotation of the HBpz 3 grouping in the complexes [HBpz 3]Mo(C0 ) 2 (T i -C 3H 5) [170] and Cp 2MoH 2^-Cu[HBpz 3] 2 [171] has been invoked to explain the equivalence of the pyrazolyl groups in the room temperature *H nmr spectra of these compounds. In any event, with time, the species responsible for the weaker set of signals gradually disappears and there remains only one set of signals, explicable in terms of a 3:3:1 structure. The proposed intramolecular rearrangement process i s further supported by the temperature dependent 300 MHz *H nmr spectrum of the [MeGapz 3]Mo(C0) 3SnMe 2Cl compound in dg-toluene shown in figure 37. In t h i s spectrum, as the solution i s warmed up to ~80°C, the set of signals consistent with the 3:3:1 structure predominates since the rate of the 125 Figure 36. Possible molecular arrangements for the [MeGapz3]Mo(CO)oSnMe2Cl complex in solu t i o n : (A) 3:3:1 structure, (B) 3:4 structure. rearrangement process would be more rapid at high temperatures. As the solution i s cooled down, the set of signals explicable in terms of the 3:3:1 structure decrease in i n t e n s i t y with concomitant increase in i n t e n s i t y for the signals a t t r i b u t a b l e to the 3:4 structure, u n t i l at ~ -80°C, the system shows only one set of signals consistent with the 3:4 126 A 80*c B - 8 0 c I ' I 1 1 1  11 0 2 4 6 8 10 r (ppm) Figure 37. Temperature dependent 300 MHz AH nmr spectrum of [MeGapz 3]Mo(C0) 3SnMe 2Cl in dg-toluene s o l u t i o n . 127 s t r u c t u r e . The above behaviour i s not s u r p r i s i n g s ince the 3:4 or ' f ou r - l egged piano s t o o l ' s t r u c t u r e has been shown to be the most s t ab l e po i n t (ground s t a t e ) i n the po t en t i a l energy sur face fo r ( r i -C 5 H 5 )ML 4 complexes [141] . I n t e r e s t i n g l y , P a t i l and Graham [157] repor t a s i n g l e t f o r the 'SnMe 2 ' protons in t h e i r CpMo(C0) 3SnMe 2Cl complex f o r which they specu la te a 3:4 o r piano s too l s t r u c t u r e , s i m i l a r to tha t demonstrated fo r the complexes ( r i -C 5 H 5 )Mo(C0) 3 Et [ 93 ] , and (T ) -C 5 H 5 )Mo(C0) 3 Mn(C0) 5 [152] , r e s p e c t i v e l y . The mass spectrum of the present [MeGapz 3]Mo(C0) 3SnMe 2Cl complex d i sp l ayed a s t rong parent i o n , P + , s igna l at m/e ~ 650. In a d d i t i o n s i g na l s due to the P-C0 + , P-2C0 + , P-3C0-Me + and P-3C0 + ions were a l s o observed, the l a t t e r being the s t ronges t i n the spectrum. The r e l a t i v e i n t e n s i t i e s of the l i n e s in these s i gna l s agreed we l l w i th a computer-generated p r o f i l e , t ak ing i n t o account the r e l a t i v e abundances of the n a t u r a l l y o c cu r r i ng i so topes of Mo, Ga, Sn, and Cl (see f i g u r e 38 ) . I f f Sf 6f 4f 2f f r o co I | I I I I I I I I I | I 52f 64f 68f Figure 38. Partial mass spectrum of [MeGapz 3]Mo(CO) 3SnMepCl. Inset: computer generated p r o f i l e of signal for ions containing Ga, Mo, Sn, and Cl atoms. 129 4.3.5 LSnY (L = [MeGapz 3]", [MeGa(3,5-Me 2pz) 3]", Y = Me3; L = [MeGapz 3]", Y = MepCl) The complexes LSnY were prepared by the reaction of the appropriate ligand with e i t h e r Me 3SnCl or Me^SnC^ s t a r t i n g materials, respectively. The compounds were is o l a t e d as c o l o r l e s s , flaky, a i r - s e n s i t i v e c r y s t a l s . Solutions of the complexes were unstable even under inert conditions. The LSnMe3 (L = [MeGapz 3], [MeGa(3,5-Me 2pz) 3]) complexes consistently gave s a t i s f a c t o r y analyses f o r C, and H; however, the N content was d i f f e r e n t each time. The reason f o r t h i s discrepancy is not clear. The AH nmr spectra of the complexes showed a l l three of the pyrazolyl groups in each compound to be equivalent, suggesting tridentate coordination of the ligand to the Sn atom. The seemingly equivalent pyrazolyl groups indicated by the *H nmr of the compound [MeGapz 3]SnMe 2Cl may be r a t i o n a l i z e d by a rapid rotation of the 'MeGapz3' moiety about the Ga**»Sn axis in s o l u t i o n . However, attempts to i s o l a t e suitable c r y s t a l s f o r X-ray structural determination proved unsuccessful. An X-ray structure determination of the analogous compound [HBpz 3]SnMe 3 was reported recently by Nicholson [37], and confirms the presence of a six-coordinate t i n bonded to three methyl groups and to three pyrazolyl groups. 130 4.4 Summary The reaction of the molybdenum tricarbonyl anion, [MeGapz 3]Mo(C0) 3 with a variety of group 14 ( S i , Ge, Sn) organohalides has yie l d e d a series of complexes in which d i r e c t Mo-M' (M1 = S i , Ge, Sn) single covalent bonds are featured. The [MeGapz 3]Mo(C0) 3SnMe 2Cl complex shows an i n t e r e s t i n g solution behaviour in which a t r a n s i t i o n from a 3:4, or piano stool structure, to a 3:3:1, or capped-octahedral arrangement, i s thought to occur. The stereochemical n o n - r i g i d i t y of the above 'SnMe^Cl' der i v a t i v e in solution was demonstrated by a variable temperature *H nmr experiment. The 3:3:1 structure has been demonstrated in the s o l i d state for the [MeGapz 3]Mo(C0) 3SnPh 3 compound by means of a cry s t a l structure determination. The ligands [MeGapZg] and MeGa(3,5-Me 2pz) 3] have been used in t h i s study to form the elusive six-coordinate organotin complexes, LSnMe3 (L = [MeGapz 3] or [MeGa(3,5-Me 2pz) 3]) and [MeGapz 3]SnMe 2Cl. 131 CHAPTER V TRANSITION METAL DERIVATIVES OF THE UNSYMMETRIC TRIDENTATE PYRAZOLYLGALLATE LIGANDS [Me 2Gapz'0(C 5H 3N)CH 2NMe 2]~ AND [Me 2Gapz'0(C 9H 6N)]~ 5.1 Introduction The f i r s t of a new class of unsymmetric tridentate chelating organogallate ligands was introduced sometime ago [41]. These ligand systems, containing a pyrazolyl group, together with a A f u n c t i o n a l donor moiety, both attached to a dimethyl gallium unit, have been shown to coordinate f a c i a l l y in a variety of octahedral t r a n s i t i o n metal carbonyl compounds [172,173,174]. Meridional coordination of the above ligand systems to the metal center has been demonstrated for four-coordinate square-planar Rh(I) species [175,176], and the novel five-coordinate iron d i n i t r o s y l complex [Me 2Ga(3,5-Me 2pz)(0CH 2CH 2NMe 2)]Fe(N0) 2 [44]. Both the fac and mer isomers have been s t r u c t u r a l l y characterized for the coordination compound [Me 2Gapz(0CH 2CH 2NH 2)] 2Ni [43]. Metal derivatives of multidentate ligand systems incorporating both the pyrazolyl and pyridyl functional groups have been the subject of recent publications [177,178]. It has been in f e r r e d that although pyrazole has stronger a-donor properties than pyridine [177], the former has weaker rt-acceptor c a p a b i l i t y [179]. The many novel aspects displayed by the compounds 132 incorporating t h i s class of ligand prompted further i n v e s t i g a t i o n into the general area of unsymmetrical uninegative organogallate ligands to include an amino-pyridyl moiety as well as a fused quinolyl 'aromatic' unit in the ligand system. This chapter describes the synthesis of the ligands L~, a and L~ derived from 2-(dimethylaminomethyl)-3-hydroxypyridine, and 8-hydroxyquinoline respectively, and d e t a i l s t h e i r r e a c t i v i t y toward a variety of t r a n s i t i o n metal halide species. Figure 39. The unsymmetric organogallate ligands [Me^apz-CKCgH^N)- CH 2NMe 2]" (L~), and [Me 2Gapz-0(C gH 6N)]" ( L ~ ) . Thus, reactions of the new ligands L~, L~ with a variety of t r a n s i - tion metal halide species y i e l d e d a diverse range of compounds which have been characterized by the usual physical methods. The r e a c t i v i t y of the 133 complexes L Rh(CO), L Rh(CO) toward methyl iodide and molecular iodine i s a q also described and an X-ray crystal structural study of what is thought to be a methyl iodide oxidative addition product D^Gapz'OtCgH-jNjQ^NMe^Rh- (Me)(I)C0 is i n progress. The preparation, properties, crystal and molecular structures of the [Me^a'O^H-jNjCH^Me,,], and [Me 2Ga*0(CgHgN)] 2coordination compounds are also presented. Parts of t h i s work have been submitted f o r publication [180,181]. 5.2 Experimental 5.2.1 S t a r t i n g Materials Sodium pyrazolide was prepared by reacting sodium hydride (Alfa) with pyrazole (K and K laboratories) in THF. Nickel n i t r o s y l iodide [128], manganese pentacarbonyl bromide [182], rhenium tetracarbonyl chloride dimer [183], and Mo(MeCN) 2(r) 3-C 3H 5)(C0) 2Br [184] were prepared according to l i t e r a t u r e methods. Rhodium dicarbonyl chloride dimer, molybdenum hexacarbonyl (Strem Chemicals), iodine, 2-(dimethylaminomethy 1)-3-hydroxy- pyridine ( A l d r i c h ) , 8-hydroxyquinoline (Eastman Organic Chemicals) were used as supplied. Methyl iodide (Fisher S c i e n t i f i c ) was dried by d i s t i l l a t i o n from phosphorus pentoxide and stored over a few mercury droplets. A l l y l bromide (Eastman Kodak Co.) was d i s t i l l e d before use. 5.2.2 Preparation of [Me 2GaO(C 5H 3N)CH 2NMe 2] Me3Ga + H0(C 5H 3N)CH 2NMe 2 — — > [Me 2GaO(C 5H 3N)CH 2NMe 2] + MeH 134 To a THF s o l u t i o n of 2 - (d ime thy l am inome thy l ) - 3 -hyd roxypy r i d i ne (1.34 g, 8.8 mmol) was added t r i m e t h y l g a l l i u m (1.01 g, 8.8 mmol) i n the same s o l v en t . The r ea c t i on mixture was r e f l u xed under N 2 u n t i l c e s sa t i on of methane gas (-2 days ) . The s o l u t i o n was then coo led to room temperature and the so lvent removed under vacuum. The r e s u l t i n g res idue was ex t r a c t ed w i th benzene, and f i l t e r e d . Slow evaporat ion of the benzene so l ven t c on t a i n i ng the e x t r a c t s a f fo rded a i r - and mo i s t u r e - s en s i t i v e pale ye l l ow c r y s t a l s of the des i r ed produc t . Y i e l d -80%. Mp 62°C. A n a l . Ca l cd . f o r Me 2 Ga0(C 5 H 3 N)CH 2 NMe 2 : C, 47.85; H, 6.83; N, 11.16. Found: C, 48.05; H, 6.76; N, 10.96. The NMR data f o r t h i s complex and the hydroxy s t a r t i n g mate r i a l are compi led i n Tables V and VI (see a l so f i g u r e s 42 and 43; pp. 152 and 153), r e s p e c t i v e l y . Table V 400 MHz *H NMR Data f o r H0(C 5H 3N)CH 2NMe 2 i n C g D 6 s o l u t i o n . 135 * t x(ppm) J ( H z ) A s s i g n m e n t 8 . 1 5 ( s ) - H b 6 . 3 3 ( s ) - H c 3 . 2 0 ( d d ) 4 . 0 ( 8 . 0 ) 2 . 8 6 ( d d ) 2 . 0 ( 8 . 0 ) 1 . 85 (dd ) 2 . 0 ( 6 . 0 ) - 1 . 4 5 ( s ) - * xCgHg = 2 .84 ppm; s = s i n g l e t ; dd = d o u b l e t o f d o u b l e t s . * R i n g p r o t o n s a r e u n a s s i g n e d . T a b l e VI 400 MHz A H NMR Data f o r M e 2 G a O ( C 5 H 3 N ) C H 2 N M e 2 i n CgDg s o l u t i o n . a H 2 Me 2 c b 136 * t x(ppm) J(Hz) Assignment 10.29(s) - H a 8.39(s) - H b 6.40(s) - H 3.14(dd) 4.0(8.0) 2.74(d) 8.0 1.99(dd) 2.0(4.0) * xCgHg = 2.84 ppm; s = s i n g l e t ; d = doublet; dd = doublet of doublets Ring protons are unassigned. 5.2.3 Preparation of [Me 9Ga0(C QH f iN)] 9 Me3Ga + H0(C gH 6N) — — — > [Me 2GaO(C gH 6N)] + MeH The coordination compound [Me 2Ga0(C gHgN)] was prepared by the method described above (section 5.2.2), using 8-hydroxyquinoline as s t a r t i n g material. The a i r - s e n s i t i v e lemon yellow product was is o l a t e d in ~85% y i e l d . Mp 63°C. Anal. Calcd. for [Me 2GaO(C gHgN)]: C, 54.16; H, 4.92; N, 5.74. Found: C, 54.58; H, 4.61; N, 5.97. The NMR data for t h i s compound and the hydroxy s t a r t i n g material are compiled in Tables VII and VIII (see also figures 44 and 45, pp. 155 and 156). 137 Table VII 400 MHz lH NMR Data fo r H0(C gH 6N) in C g D 6 s o l u t i o n . x(ppm) J (Hz) Assignment 3.24(dd) 3.00(dd) 2.81(m) 2.47(dd) 1.60(dd) 1.46(s) 4 .0 (8 .0) 2 .0(8 .0) 8 .0(32.0) 2 .0(8 .0) 2 .0(4 .0) * -cCgHg = 2.84 ppm; s = s i n g l e t , dd = doublet of doub le ts ; m = m u l t i p l e t . * Ring protons are unass igned. 138 Table V I I I 400 MHz  lH NMR Data f o r [Me 2 GaO(C 9 HgN)] 2 i n CgDg s o l u t i o n . x(ppm) J (Hz) Assignment 9.90(s) 3.58(dd) 3.31(dd) 2.71(m) 2.61(dd) 2.57(dd) 4 .0 (8 .0) 2 .0(8 .0) 2 .0(4 .0) 2 .0(8.0) tCgHg = 2.84 ppm; s = s i n g l e t ; dd = doublet of doub le ts ; m = m u l t i p l e t . Ring protons are unass igned. 5.2.4 P repa ra t i on of the l i g and Na [Me2Gapz«0(C5H3N)CH2NMe2]~ (Na L a ) Me 3Ga + Na pz + - ~ T H F > Na + [Me 3 Gapz]" 139 Na +[Me 3Gapz]" + H0(C 5H 3N)CH 2NMe 2 T H F > Na +[Me 2Gapz«0(C 5H 3N)CH 2NMe 2]" + MeH Trimethylgallium (6.20 g, 54.0 mmol) in ~50 ml THF was added to sodium pyrazolide (4.86 g, 54.0 mmol) dissolved in ~50 ml THF. The reaction mixture was s t i r r e d f or ~4 h. The solution was then dilu t e d with THF to 500 ml in a volumetric f l a s k . An aliquot of t h i s standard Na +Me 3Gapz~ (12.96 mmol) ligand solution in THF was added to a s t i r r e d s olution of 2-(dimethylaminomethyl)-3-hydroxypyridine (1.973 g, 12.96 mmol) in the same solvent. The reaction mixture was refluxed under N 2 u n t i l the evolution of methane gas had ceased completely (~2 days). The cooled solution was then d i l u t e d with THF to 250 ml in a volumetric f l a s k . Aliquots of t h i s standard solution were used in subsequent reactions with t r a n s i t i o n metal halide species. 5.2.5 Preparation of the ligand Na +[Me 2Gapz«0(CgH 6N)] _ (Na +L~) Na +[Me 3Gapz]" + HOfCgHgN) T H F > Na +[Me 2Gapz'0(CgHgN)r + MeH The ligand Na +L~ was prepard by a method id e n t i c a l to that described i n section 5.2.4, using 8-hydroxyquinoline as the s t a r t i n g material. Aliquots of the r e s u l t i n g yellow Na +L~ standard solution were then used in subsequent reactions with metal halide species. 140 5.2.6 Preparation of L Re(CO)., a o 2NaV + [Re(C0).Cl] o T H F > 2L Re(CO), + 2C0 + 2NaCl a 4 c ^ ^ a o A 40.0 ml aliquot of the ligand solution Na +L~ (0.64 mmol) was added a slowly to [ R e ( C 0 ) 4 C l ] 2 (0.216 g, 0.324 mmol) dissolved in -30 ml THF. The reaction mixture turned cloudy almost immediately. The reaction mixture was refluxed f o r -24 h during which time the cloudiness increased and the yellow c o l o r a t i o n i n t e n s i f i e d . The solution was cooled to room temperature, and the solvent removed under vacuum. The r e s u l t i n g residue was extracted with benzene and f i l t e r e d . Evaporation of the benzene solvent containing the extracts afforded pale yellow c r y s t a l l i n e needles of the desired rhenium tricarbonyl complex in -80% y i e l d . This compound is stable to oxidation but solutions deteriorate a f t e r prolonged periods even under an i n e r t atmosphere. Physical data for th i s complex are given in Table XII, p. 161. 5.2.7 Preparation of L Mn(CO)., a o N a V + Mn(C0) cBr T H F > L aMn(C0), + 2C0 + NaBr a o A To a s t i r r e d THF solution of Mn(C0)gBr (0.421 g, 1.53 mmol) was added a 30 ml aliqu o t of the Na +L~ (1.53 mmol) ligand solution in the same a solvent. The reaction mixture immediately turned a cloudy orange color. The mixture was refluxed overnight, a f t e r which the solvent was removed i n vacuo, and the r e s u l t i n g orange residue extracted with benzene. 141 Evaporation of the benzene from the f i l t r a t e resulted in an orange o i l . T r i t u r a t i o n of the sticky orange o i l eventually y i e l d e d an a i r - s e n s i t i v e orange powder as the product in -75% y i e l d . Physical data for the complex are l i s t e d in Table XII, p. 161. 5.2.8 Preparation of LNi(NO) a N a V + Ni(N0)I T H F > LNi(NO) + Nal a a Ni(N0)I (0.33 g, 1.5 mol) was dissolved in -50 ml THF. A solution of Na +L~ (1.5 mmol) in the same solvent was added to the s t i r r e d solution of a the n i t r o s y l . The re s u l t i n g dark blue solution was s t i r r e d overnight. The solvent was removed under vacuum, and the dark blue residue extracted with benzene. The benzene f i l t r a t e containing the extracts was concen- trated and, upon evaporation of the solvent, flaky blue c r y s t a l s of the product were recovered in -60% y i e l d . Analytical and spectroscopic data for t h i s complex are c o l l e c t e d in Table XII, p. 161. 5.2.9 Preparation of L Re(CO)^ 2Na +L" + [ R e f C O L C l L T H F > 2L Re(C0h + 2C0 + 2NaCl q A ^ Two molar equivalents of Na +L^ were added to [Re(C0) 4Cl]2 (0.18 g, 0.27 mmol) dissolved in -30 ml THF, and the re s u l t i n g solution was refluxed overnight. The solvent was then removed from the reaction mixture under vacuum. The residue was extracted with benzene. Evapora- tio n of solvent from the f i l t e r e d extract resulted in a yellow cake. 142 R e c r y s t a l l i z a t i o n of the yellow cake from CH^C^/hexane (1:1) afforded stable yellow c r y s t a l s of the desired product in ~80% y i e l d . Selected physical data for t h i s complex are summarized in Table XVI, p. 174. 5.2.10 Preparation of LMn(CO), N a V + Mn(C0),Br T H F > L Mn(C0)-> + 2C0 + NaBr q b A q 3 An equimolar amount of Na +L~ ligand in THF, was added to Mn(C0),-Br q o (0.19 g, 0.68 mmol) dissolved in the same solvent. After r e f l u x i n g the reaction mixture overnight, the solvent was removed from the cloudy orange solution in vacuo. Work-up of the r e s u l t i n g residue, using benzene as the extracting solvent, gave orange c r y s t a l s of the product in ~80% y i e l d . This complex i s stable under i n e r t conditions but darkens in color on exposure to a i r . Solutions of the complex (in acetone or benzene), deteriorate with time. Physical data for t h i s compound are presented in Table XVI, p. 174. 5.2.11 Attempted preparation of L^Ni(NO) A 1:1 reaction of Ni(N0)I and Na +L~ ligand in THF was c a r r i e d out both at room and reflux temperatures. In both reactions, the reaction mixture turned blue/green and a f t e r work-up, blue/green s o l i d s were obtained. The solution i r spectrum of either the reaction mixture or the f i n a l blue/green s o l i d showed no noticeable evidence of absorption bands in the n i t r o s y l stretching frequency region of the spectrum. The *H nmr and mass spectral data of the s o l i d i s o l a t e d were consistent with those expected for an octahedral Ni (II) complex formulated as [Me,,GapzO- (CgH6N)]2Ni. However, repeated attempts at obtaining a n a l y t i c a l l y pure 143 samples, or i s o l a t i n g suitable c r y s t a l s for X-ray structural determination, were unsuccessful. 5.2.12 Preparation of Mo(MeCN) 2 (r) 3-C 3H 5)(C0) 2Br Mo(C0) 6 + C 3H 5Br M e C N > Mo(MeCN ) 2 ( r i 3-C 3H 5)(C0) 2Br + 4C0 Excess a l l y l bromide was refluxed with Mo(C0) 6 (2.04 g, 7.70 mmol) in ~60 ml a c e t o n i t r i l e f o r 2 days. The cooled yellow solution was l e f t to stand in an i n e r t atmosphere for another 2 days, at which stage a yellow c r y s t a l l i n e p r e c i p i t a t e had formed. The yellow s o l i d was then c o l l e c t e d and dried in vacuo to give a i r - s e n s i t i v e yellow c r y s t a l s of the product in ~80% y i e l d . This compound exhibits two strong bands in the CO stretching frequency region of the i r spectrum ( v C Q : 1945, 1860 cm - 1 CH 2C1 2). [ I t i s recommended that t h i s compound be prepared immediately p r i o r to further use since i t decomposes r e a d i l y on standing.] A l t e r n a t i v e l y , the compound can be prepared via a two-step process- oxidative addition of a l l y l bromide to the l a b i l e (MeCN) 3Mo(C0) 3 generated from Mo(C0) 6 as c i t e d in the l i t e r a t u r e by Hayter [184]. 5.2.13 Preparation of L aMo(C0) 2(T] 3-C 3H 5) Na +L~ + Mo(MeCN) 2(ri 3-C 3H 5)(CO) 2Br T H F > l_ aMo(C0 ) 2 ( r i 3-C 3H 5) + 2MeCN + NaBr Equimolar amounts of the ligand Na +L~ and Mo(MeCN) 2 (r) 3-C 3H 5)(C0) 2Br 144 were reacted in THF. An immediate cloudiness was observed upon mixing the reagents, i n d i c a t i n g p r e c i p i t a t i o n of NaBr s a l t . The reaction mixture was s t i r r e d overnight followed by solvent removal under vacuum. The r e s u l t i n g residue was extracted with benzene and f i l t e r e d . Evaporation of the benzene solvent from the s o l u t i o n containing the extracts afforded orange c r y s t a l s of the desired product in ~70% y i e l d . This compound i s stable under inert conditions but solutions deteriorate with time. Pertinent physical data are c o l l e c t e d in Table XII, p. 161. 5.2.14 Preparation of L qMo(C0 ) 2 ( T i 3-C 3H 5) 3 The compound LqMo(C0) 2(r) -C3H5) was prepared by a procedure i d e n t i c a l t o that described in section 5.2.13. Work-up of the residue r e s u l t i n g from t h i s reaction, using hexane as the extracting solvent, afforded shiny red-orange crystals of the product in ~70% y i e l d . A n a l y t i c a l and spectrosocpic data f o r the complex are l i s t e d i n Table XVI, p. 174. 5.2.15 Preparation of L Rh(CO) a 2 N a V + [ R h ( C 0 % C l ] 9 T H F > 2L Rh(CO) + 2C0 + 2NaCl a <L <L A a Two molar equivalents of the ligand Na +L~ were added to [ R h ( C 0 ) 2 C l ] 2 (0.30 g, 0.77 mmol) dissolved in ~40 ml THF. The reaction mixture was refluxed under nitrogen u n t i l the disappearance of the [ R h ( C 0 ) 2 C l ] 2 dimer ( V ^ Q : 2068, 1989 cm"1 THF) was indicated by i r measurements. At t h i s juncture, three new bands had appeared in the V ^ Q region of the spectrum at 2085, 2025 and 1970 cm"1, respectively. The reaction mixture was 145 cooled, and the solvent removed in vacuo. The residue was washed with hexane followed by extraction with benzene. Evaporation of the benzene solvent from the f i l t r a t e containing the extracts afforded orange c r y s t a l s of the product in ~60% y i e l d . The compound is moderately stable but solutions decompose with time. Physical data are summarized in Table XII, p. 161. 5.2.16 Preparation of L qRh(CQ) Preparation of the compound L Rh(CO) was accomplished by a procedure s i m i l a r to the one described in section 5.2.15. New V C Q bands at 2080, 2020, and 1965 cm"1 in THF were indicated by i r sampling of the reaction mixture p r i o r to solvent removal in vacuo. A f t e r work-up, yellow-orange c r y s t a l s of the product were i s o l a t e d i n ~65% y i e l d . A n a l y t i c a l , i r and *H nmr data are c o l l e c t e d i n Table XVI, p. 174. 5.2.17 Reaction of L Rh(CO) with Mel d CH ?C1 ? L Rh(CO) + Mel c C > L Rh (Me) (I)CO a a A s l i g h t excess of methyl iodide in CH 2C1 2 was added dropwise to a s t i r r e d s o l u t i o n of L Rh(CO) (0.30 g, 0.70 mmol) in the same solvent. a A f t e r s t i r r i n g the reaction mixture at room temperature f o r about 18 h, the i n i t i a l orange so l u t i o n had turned deep red-orange. The i r spectrum of the solution at t h i s stage revealed the presence of a new band at ~2060 cm"•''and the complete disappearance of the band at 1970 cm"1', att r i b u t a b l e to the URh(CO) s t a r t i n g material. Removal of the solvent i n vacuo, extraction of the residue in benzene, followed by r e c r y s t a l l i z a t i o n 146 from CH 2C1 2» afforded red c r y s t a l s of the product i n almost quantitative y i e l d . This compound c r y s t a l l i z e d as a benzene solvate which remained a f t e r several days of pumping under vacuum. Anal. Calcd. For [Me 2Gapz»0(C 5H 3N)CH 2NMe 2]Rh(Me)(I)C0'0.5 C gH 6: C, 34.31, H, 4.13; N, 8.89. Found: C, 33.93, H, 4.06; N, 8.55. IR(CH 2 C1 2 ) v C Q : 2060 cm"1; IR(Nujol) v ^ : 2055 cm"1. lH NMR (270 MHz, CDC1 3): xCHCl^ = 2.73 ppm, 10.34s, 10.12s (-GaMe2); 8.85s, 7.63s (-NMe2); 6.15s (-CH2); 3.71t (pz-H 4); 2.43d (pz-H 3); 2.98d (pz-H 5); 9.25s (Rh-Me). ^HCCH = ~ 2 ^ Z ^ o r ^ Z P r o t o n s ' ) Positive Ion Fast Atom Bombardment Mass Spectrometry (FABMS) in thio g l y c e r o l matrix: [P+H] +, [P-H] +, and [P-Me] + ( P + = parent ion) ion signals were observed at 591, 589 and 575 mass 69 un i t s , (based on Ga) respectively. 5.2.18 Reaction of L qRh(C0) with Mel CH ? C1 ? L qRh(C0) + Mel > L qRh(C0Me)I To a solution of L qRh(C0) (0.40 g, 0.91 mmol) i n -35 ml CH 2 C1 2 was added one molar equivalent of Mel in the same solvent. The mixture was s t i r r e d f o r about 1-1/2 h, at which stage i r evidence indicated the presence of two new bands in the v ^ r e g i o n of the spectrum at -2070 and 1700 cm"1, respectively with no trace of the v^band due to the L qRh(C0) s t a r t i n g material. The solvent was then allowed to evaporate from the solu t i o n . The dark orange s o l i d obtained was washed in hexane followed by benzene to give small dark orange crystals i n low y i e l d (-35%). 147 Ana l . Ca l cd . f o r [Me2Gapz'0(CgHgN)]Rh(C0Me)I: C, 32.90; H, 3.08; N, 7.20. Found: C, 33.00, H, 3.04; N, 6.90. IR(CH 2 C1 2 ) v ^ ; 2070, 1700 cm" 1 . IR(Nujo l ) v „ : 1710 cm" 1 . lH NMR (270 MHz, CDC1,): T CHC1 2.73 ppm, 10.08s, 9.89s (-GaMe 2); 7.58s (-COMe); 3.71t ( p z - H 4 ) ; 2.29d 3 5 ' (pz-H ); pz-H obscured by the qu i no l y l r i ng proton resonances. MS: P , P-Me +, P-Me-C0 +, P-Me-I + and P-2Me-I + ( P + = parent ion) ion s i gna l s were observed. 5.2.19 React ion of L*Rh(C0) (L* = L f l , L q ) w i th I g L*Rh(C0) + I 2 C H 2 C l 2 > L*RhI 2(C0) To a CH 2 C1 2 s o l u t i o n of L Rh(C0) was added a s l i g h t excess of the d iha logen I 2 i n the same so l ven t . An immediate c o l o r change from orange t o red was observed on mix ing the reagents. A f t e r s t i r r i n g the mixture f o r a few hours, an i r spectrum i nd i c a t ed complete disappearance of the V^Q band of the rhodium(I) monocarbonyl s t a r t i n g m a t e r i a l , and the -1 -1 * appearance of a new band at ~2090 cm (L = L ), and ~2085 cm (L = L Q ) . The s i n g l e V^Q band p e r s i s t e d i n s o l u t i o n a f t e r s t i r r i n g the r eac t i on mixture overn igh t . Although the i r spect ra of the reac t i on mixtures suggested the presence of s i x - c oo rd i na t e Rh ( I I I ) monocarbonyl spec ies i n s o l u t i o n , a n a l y t i c a l l y pure compounds of the expected * d i i o d i d e s , L Rh I 2 (C0 ) , could not be i s o l a t e d from the black s o l i d mater ia l obta ined a f t e r removal of s o l ven t . 148 5.3 Results and Discussion 5.3.1 [Me 2GaO(C 5H 3N)CH 2NMe 2] A general reaction of Group 13 (B, A l , Ga, In) alkyls toward active hydrogen-containing ligands is the elimination of alkanes. For example, a compound s t r u c t u r a l l y characterized by X-ray crystallography as [Me 2NCH 2CH 20GaMe 2] 2 was i s o l a t e d as the product of the reaction of trimethyl gallium with N,N-dimethylethanolamine [185]. With the notable exception of H2NCH2CH20GaMe2, the structure of which consists of monomeric molecules containing t e t r a h e d r a l l y coordinated gallium atoms [186], monomer units of s i m i l a r dimethyl gallium systems have been shown by X-ray str u c t u r a l analyses to dimerize via four-membered [-Ga-0-] 2 rings giving a d i s t o r t e d bipyramidal arrangement about each five-coordinate gallium atom [173,185]. The reaction of 2-(dimethylaminomethyl )-3-hydroxypyridine with trimethyl gallium y i e l d e d the compound [Me 2Ga'0(C 5H 3N)CH 2NMe 2], the c r y s t a l structure (figure 40) of which consists of discrete monomeric molecules which display the gallium atoms in distorted tetrahedral arrangements rather than a d i s t o r t e d t r i g o n a l bipyramidal geometry expected f o r a five-coordinate gallium dimeric species. It is i n t e r e s t i n g to compare the Ga-N bond length i n t h i s complex to those reported f o r s i m i l a r dimethyl- gallium systems (figure 41, see also Table XI, p. 158). The Ga-N bond length of 2.135A in the present [Me 2Ga*0(C 5H 3N)CH 2NMe 2] complex is considerably shorter than that of the dimer [Me 2GaOCH 2CH 2NMe 2] 2 (Ga-N = 2.471A) [185], but longer than 2.056A and 2.072A reported f o r the two independent molecules of the [Me GaOCH CH NH ] monomeric species [186]. Figure 40. Molecular structure of [Me 2Ga-0(C 5H 3N)CH 2NMe 2] The shorter Ga-N bond length of 2.135A in the present [Me 2Ga»0(C 5H 3N)CH 2- NMe2] complex compared with the 2.471A above is suggestive of less s t e r i c i n t e ractions. In the [Me2GaOCH2CH2NMe2] complex, severe s t e r i c i n t e r - actions led to bond lengthening. The monomeric nature of the present [Me 2GaO(CgH 3N)CH 2NMe 2] compound is probably related to the s t e r i c con- s t r a i n t s imposed by the unsaturation of the pyridine ring. Since the pyridine substituent atoms 0 and C(6) are constrained to l i e approximately in the plane of the pyridine ring, four atoms of the six-membered chelate must be roughly coplanar. In order to minimize angular s t r a i n , the che- late ring adopts a steep and s l i g h t l y twisted boat conformation in which the NMe2 and GaMe2 groups are nearly ecl i p s e d . The p a r t i a l staggering about the Ga-N bond which would be required f o r dimerization most l i k e l y results i n too high a degree of ring s t r a i n . It is noteworthy that in the related compound [Me 2GaOCH 2CH 2NH 2] [186] , an extensive network of N-H«««0 hydrogen bonding present in the compound prevented dimerization of the monomer units. N O Ga ,Ga 0 [Me ̂GaOCĤ CH ̂NH ̂ ] [Me2Ga.0(C5H3N)CH2NMe2] ^GaOCH^NMe,,] 2 Figure 41 Comparison of the Ga-N bond lengths in the dimethylgall ium compounds, 151 The mass spectrum of the compound [Me 2GaO(CgH 3N)CH 2NMe 2] displayed as i t s highest mass peaks, a moderately strong parent ion (P +) signal as well as a very strong P-Me+ s i g n a l , confirming the monomeric nature of the compound in the gas phase. The most intense signals were those corre- sponding to loss of the 'CH2NMe2' moiety from the monomer species. The mass spectral data f o r t h i s compound are collected in Table IX below. Table IX. +Mass Spectral Data of [Me 2GaO(C 5H 3N)CH 2NMe 2] * m/e Assignment Intensity 250 [Me 2Ga'0(C 5H 3N)CH 2NMe 2] + 19.3 235 [MeGa*0(C 5H 3N)CH 2NMe 2] + 85.3 192 [Me 2Ga*0(C 5H 3N)] + 100.0 177 [MeGa*0(C 5H 3N)] + 14.5 151 [0(C 5H 3N)CH 2NMe 2] + 5.0 109 [H0(C 5H 3N)CH 3] + 58.5 99 [Me 2Ga] + 15.2 80 C 5 H 6 N + 8 ' 2 69 Ga + 35.2 58 [-CH 2NMe 2] + 43.2 44 [NMe 2] + 18.6 At 68°C. * 69 Based on Ga. The 1H nmr spectra of the hydroxy s t a r t i n g material, H0(Cr )H3N)CH2NMe2 in CgDg s o l u t i o n , and of the complex Me 2Ga0(CgH3N)CH 2NMe 2 in CgDg sol u t i o n , are shown in figures 42 and 43, respectively. The A H nmr spectrum of Me2GaO(CgH3N)CH2NMe2 complex is consistent with an overall planar structure f o r th i s species in solution, with the two methyl groups b  154 on gallium, and the two methyl groups on nitrogen, as well as the two methylene protons l y i n g above and below t h i s plane; t h i s leads to sharp s i n g l e t s f o r the -GaMe2, -NMe2 and -CH2- groupings. 5.3.2 [Me 2GaO(C gH 6N)] 2 The reaction of 8-hydroxyquinoline with t r i methyl gal lium afforded the coordination compound ' [Me 2Ga0(C gHgN)]' which has been shown to be monomeric in the gas phase. The mass spectrum of t h i s compound displayed prominent signals due to the parent ion P +, P-Me+ and P-2Me+, the l a t t e r being the most intense in the spectrum (see Table X below). Table X. " W s Spectral Data of '[Me 2GaO(C gH 6N)]' * m/e Assignment Intensity 243 [Me 2GaO(C gH 6N)] + 12.0 228 [MeGaO(C gH 6N)] + 100.0 213 [GaO(C gH 6N)] + 28.0 145 [H0(C gH 6N)] + 5.9 115 [Me 2GaO] + 6.2 99 [Me 2Ga] + 2.3 84 [MeGa] + 50.7 69 Ga + 50.7 + At 180°C * 69 Based on Ga. The XH nmr spectra of the hydroxy s t a r t i n g material H0(CgHgN), and the quinolinolato complex Me2Ga0(CgHgN) in CgDg solutions are shown i n figures 44 and 45, respectively. The AH nmr spectrum of the q u i n o l i n o l a t o 155 156 157 complex is in accord with an overall planar structure f o r the complex in sol u t i o n . In this structure, the two methyl groups on gallium l i e above and below the plane, hence a sharp singlet is observed f o r the 'GaMe2' protons. The X-ray crystal structure of the [Me 2GaO(CgHgN)] 2 complex is shown in figur e 46. This structure revealed the dimerization of the monomer units via the formation of a four-membered [-Ga-0-] 2 ring to form a nearly planar (to within 0.053(5)A) cent rosy mmetric molecule consisting of a system of seven fused rings. The coordination geometry about each gallium atom i n the above ring system is di s t o r t e d trigonal bipyramidal primarily due to the s t e r i c requirements imposed by the existence of the fused ring system. The Ga-N bond length of 2.211A f o r the present q u i n o l i n o l a t o complex is shorter than those reported f o r the related [MeoGaOCH-CrLNMe?]? Figure 46. Molecular structure of [Me GaO(C H N)] . 158 (Ga-N = 2.471A) [185], and [Me 2GaO(C 5H 4N)] 2 (Ga-N = 2.276A) [173] dimers (see Table XI below). Thus s t e r i c interactions are l i k e l y less severe i n the present [Me 2GaO(C 9H 6N)] 2 complex compared with the [Me 2GaOCH 2CH 2NMe 2] 2 and [Me 2Ga»0(C 5H 4N)] 2 complexes above. The Ga-N bond length of 2.211A of the present quinolinolato compound i s , however, longer than that reported for 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 trigonal bipyramidal, f i v e - coordinate gallium complex, GaCl[0C 1 0H gN] 2 (Ga-N = 2.109A), 2.105A) reported e a r l i e r by Dymock and Palenik [187]. Table XI. Comparison of Ga-N and Ga-0 Bond Lengths in Four and Five Coordinate Gallium Compounds. Gallium Bond Distances (A) Coordination Compound Number Ga-N Ga-0 Reference [Me 2NCH 2CH 2OGaMe 2] 2 5 2.471 2,078,1.913 185 [Me 2NCH 2CH 20GaH 2] 2 5 2.279 2.053,1.911 185 [Me 2Ga«0CH 2(C 5H 4N)] 2 5 2.276 1.939-2.086 173 [Me 2Ga«0(C gH 6N)] 2 5 2.211 1.937 This work [MeN(CH 2CH 20) 2GaH] 2 5 2.193 1.843-2.019 188 Me 2Ga«0(C 5H 3N)CH 2NMe 2 4 2.135 1.897 This work Me ?GaOCrLCrLNH ? 4 2.056,2.072 1.917 186 159 5.3.3 L aM(C0) 3 (M = Mn, Re) The f i r s t of this class of unsymmetric tridentate ligands, Me 2Gapz(0- CHgCH^NRg)" (R = H or Me), has been shown to be capable of either f a c i a l or meridional coordination in t r a n s i t i o n metal complexes [43]. However, in a l l octahedral t r a n s i t i o n metal tricarbonyl compounds studied thus f a r , coordination of the unsymmetrical pyrazolylgal l a t e ligand has been found to be e x c l u s i v e l y f a c i a l [173,174]. The present manganese and rhenium tricarbonyl compounds, incorporating the ligand Me2GapzO(CgH3N)CH2NMe2 (L ~ ) , therefore represent the f i r s t and the only examples of such a complexes in which both fac and mer isomers co-exist in s o l u t i o n . Evidence for the presence of both isomers in solution i s based sol e l y on i r and *H nmr data, since persistent attempts at i s o l a t i n g c r y s t a l s suitable for X-ray cry s t a l structure determination were unsuccessful. Infrared measurements in cyclohexane showed six bands (four strong, two weak) in the region of the spectrum. A typi c a l example of the spectra obtained for both complexes i s shown in figure 47. Three strong bands were assigned to the fac isomer, while one strong and two weak bands were assigned to the mer isomer. Thus, for octahedral t r a n s i t i o n metal tricarbonyl complexes, a fac arrangement of the tridentate ligand would give three strong bands while for a mer arrangement one would expect to see one strong and two weak bands [51,80]. A comparison of the v C Q values obtained for both compounds (Table XII, p. 161), indicates that Re donates more electron density to the CO ligands than does Mn. This results in a lowering of the values due to increased M-CO backbonding, and hence implies a stronger 'M-CO' bond [189]. 160 1933 2400 2000 1800 1600 (cm") Figure 47. Ir spectrum in the v C Q region of [Me 2Gapz»0(C 5H 3N)CH 2NMe 2] Mn(C0) 3 in cyclohexane s o l u t i o n . A fac isomer; B mer isomer. Further support for the proposed fac and mer isomers in solution i s provided by the room temperature AH nmr spectra of the complexes. As a representative example, the AH nmr spectrum of the rhenium complex [Me 2Gapz»0(C 5H 3N)CH 2NMe 2]Re(C0) 3 in CgDg solution i s shown in figure 48. In the spectrum two sets of signals were displayed. In one set the GaMe2, NMe2 and the CH 2 methylene groups appeared as sharp s i n g l e t s consistent with a mer structure (figure 49B, p. 163), and a second set consisting of Table X I I . Phys i ca l Data for the Complexes L f lMT (where L f l » Me 2 Gapz'0(C 5 H 3 N)CH 2 NMe 2 ) M T ANALYSIS CALCD/F0UND v C 0 ' v N 0 ( c m " 1 ) , C 6 H 1 2 (CH 2 CT 2 ) *H nmr C H N GaMe NMe CH 2 H 4 H 5 H 3 Re (co)3 33.95 3.49 9.32 A 2035.1920,1900 b 1 0 . 5 3 s 8.21s 4 .19t 3.29d 2.41d •0 .17C 6 H 6 9.83s 7.68s 34.08 3.98 9.44 B 2022,2015,1910 10.25s 8.39s 6.40s 3.96t 3.08d 2.21d Mn (CO), 42.05 4.41 12.26 A 2040,1943,1915 a 1 0 . 6 5 s 7.58s 6.73br 3.54t 3.00d 2.51d o 10.05s 7.24s 42.47 4.56 12.32 B 2030,2020,1933 10.31s 7.41s 6.00s 3.36t 2.85d 2.12d Mo (co)2 42.30 4.90 1950,1805 c 1 0 . 2 7 s 7.43s 5.95s 3.56t 2.85d 2.30d 8 .57d ,8 .67H A 42.06 4.97 (1925,1825) 10.09s (J * 9.0 Hz) 7.36 br H $ 6.68 br Hy Nl NO 45.17 5.27 15.06 1770 (THF) c 1 0 . 3 9 s 7.63s 6.16s 4.13t 3.35d 2.66d •0.75CgH 6 44.86 5.79 14.51 (1775) b 1 0 . 2 0 s 8.35s 6.38s 3.98t 2.68d 2.33d Rh CO 40.23 5.17 11.73 b 10 .27s 8.40s 6.41s 4.01t 2.76d 2.38d • 0 . 3 3 C 6 H 1 4 40.32 5.07 11.52 (1970) A = fac Isomer; B = mer Isomer a ( C D 3 ) 2 C 0 ; x(CH 3 ) 2 C0 = 7.89 ppm; J H C C H * 2.0 Hz for pz protons. b CgD,; xCgH, * 2.84 ppm; J H C C L | " 2.0 HZ for pz protons. C CDC1 3; xCHC? 3 = 2 . 7 3 ppm; J H C C L ) " " " " 2.0 Hz for pz protons. s = s i n g l e t d = doublet t = t r i p l e t q = quar te t br = broad Figure 48. 80 MHz ]H nmr spectrum of [Me 2Gapz0(C 5H 3N)CH 2NMe 2]Re(C0) 3 in C gD 6 s o l u t i o n . A fac isomer; B mer isomer. 163 164 two s i n g l e t s each of the 'GaMe2' and 'NMe2' moieties suggesting inequivalence of the methyl groups on gallium and nitrogen as expected for a f a c i a l l y coordinated ligand (figure 49A, p. 163). The absence of the c l e a r l y defined AB pattern expected for the methylene group of the fac isomer i s somewhat puzzling however. The pz proton resonances appeared as two sets for each proton, adding further credence for the co-existence of both the fac and mer isomers of the complexes in s o l u t i o n . These r e s u l t s , the i r data discussed above, together with results from related complexes [173,174], strongly support the presence of both isomers in solution f o r the present [Me 2Gapz0(C 5H 3N)CH 2NMe 2]M(C0) 3 (M = Mn, Re) complexes. Mass spectral data obtained for both the Mn and Re complexes (Tables XIII and XIV) revealed some i n t e r e s t i n g differences between the two com- pounds. For example, while the Re species displayed signals corresponding to the parent, P +, P-Me+, and P-2Me-2H+ ions, the highest mass fragment observed for the Mn species was a t t r i b u t a b l e to the P-3C0+ ion. The reluctance to lose the CO ligands exhibited by the Re species i s r e f l e c t i v e of the comparatively stronger 'M-CO' bonds in t h i s complex than in the valence i s o e l e c t r o n i c Mn compound. 165 Table XIII. Mass Spectral Data of [Me 2Gapz0(C 5H 3N)CH 2NMe 2]Mn(C0) * m/e Assignment Intensity 372 [Me2Gapz* 0(C 5H 3N)CH 2NMe 2Mn] + 12.7 342 [Gapz'0(C 5H 3N)CH 2NMe 2Mn] + 27.2 340 [Gapz-0(C 5H 3N)CNMe 2Mn] + 46.0 319 [(Me 2Gapz) 2 - Me + 2H] + 100.0 272 [Ga«0(C 5H 3N)CNMe 2Mn - H ] + 15.1 251 [(Me 2Gapz) 2 - Me - pz + H ] + 39.1 235 [MeGaO(C 5H 3N)CH 2NMe 2] + 60.9 192 [Me 2Ga»0(C 5H 3 N ) ] + 73.6 177 [MeGa*0(C 5H 3N)] + 15.0 151 [0(C 5H 3 N)CH 2NMe 2] + 21.4 99 [Me 2Ga] + 24.2 69 Ga + 26.2 58 [-CH 2NMe 2] + 20.0 At 120°C. 69 Based on Ga. 166 Table XIV. fMass Spectral Data of [Me 2Gapz0(C 5H 3N)CH 2NMe 2]Re(C0) • m/e Assignment Intensity 588 [Me 2Gapz«0(C 5H 3N)CH 2NMe 2Re(C0) 3] + 10.2 573 [MeGapz«0(C 5H 3N)CH 2NMe 2Re(C0) 3] + 40.7 556 [Gapz'0(C 5H 3 N)CNMe 2Re(C0) 3] + 16.8 528 [Gapz«0(C 5H 3N)CNMe 2Re(C0) 2] + 10.9 500 [Gapz-0(C 5H 3N)CNMe 2Re(CO)] + 10.6 472 [Gapz«0(C 5H 3 N)CNMe 2Re] + 42.2 319 [(Me 2Gapz) 2 - Me + 2H] + 24.8 251 C(Me 2Gapz) 2 - Me - pz + H ] + 24.9 235 [MeGa-0(C 5H 3N)CH 2NMe 2] + 94.8 192 [Me 2Ga«0(C 5H 3 N ) ] + 100.0 177 [MeGa»0(C 5H 3N)] + 16.5 151 [0(C 5H 3 N)CH 2NMe 2] + 8.4 99 [Me 2Ga] + 28.0 69 Ga + 46.5 58 [-CH 2NMe 2] + 38.0 ' At 120°C. * 69 187 Based on o yGa ad i 0 / R e . 167 5.3.4 L Ni(NO) a Infrared measurements of the L Ni(NO) complex in solution indicated a the presence of a coordinated NO group ( V N Q : 1770 cm"1 THF; 1775 cm"1 CH 2C1 2) c l e a r l y in the n i t r o s y l stretching frequency region (~1500-2000 cm"1) typ i c a l of metal n i t r o s y l complexes [190]. The value observed for t h i s complex i s i n d i c a t i v e of a considerably weakened N-0 bond i n comparison to that of free NO which absorbs in the range 1840-1833 cm - 1 [189,191]. The room temperature AH nmr spectrum of th i s compound in CDCl-j solution i s i n t e r e s t i n g in that i t displays sharp s i n g l e t s for the 'GaMe2', 'NMe2' and CH 2 groups respectively (figure 50). This i s suggestive of a square planar arrangement about the Ni center with a pseudo-meridionally coordinated organogallate ligand. However, the unlikelihood of such an arrangement for t h i s complex in l i g h t of previous studies which have shown that square planar {MNO}1^ ( i . e . , 10 d electrons on the metal M, when the n i t r o s y l ligand i s formally considered to be bound as N0 +), complexes should have an M-N-0 bond angle of 120° [192,193] (contrary to the l i n e a r M-N-0 grouping suggested by the observed i r r e s u l t s ) ; l e d us to suspect that a fluxional process was probably responsible for the observed room temperature AH nmr spectrum. The cl o s e l y related [Me 2Ga(3,5-Me 2pz)(0CH 2CH 2NMe 2)]Ni(NO) has been shown to be st e r e o c h e m i c a l ^ non-rigid at room temperature in solution and to possess a tetrahedral conformation about the Ni center in the s o l i d state [194]. A variable temperature XH nmr in both dg-acetone and toluene-dg did indeed reveal a flu x i o n a l process to be operative in so l u t i o n . In t h i s experiment the sharp -GaMe signal was monitored. As the solution was  169 cooled, marked broadening of the -GaMe2 signal was observed. At -85°C (the lowest temperature a t t a i n a b l e ) , i t was s t i l l not possible to collapse the o r i g i n a l signal and observe new signals in th i s region. Evidently, at these lower temperatures, the tetrahedral conformation was becoming established due to a slowing down of the fluxional process. Unfortunately, instrumental l i m i t a t i o n s precluded the attainment of temperatures low enough to observe s p l i t t i n g of the signals. The i r r e s u l t , together with i r data reported for some {MNO}10 complexes (see Table XV below), as well as the AH nmr res u l t s discussed above, led to the conclusion of a f a c i a l l y coordinated L, ligand in the a present L Ni(NO) complex with the coordination geometry about Ni being a te t r a h e d r a l . Table XV. Comparison of v Values in Selected Four-coordinate {MNO}10 Complexes. Compound Reference [Me 2Gapz«0(C 5H 3N)CH 2NMe 2]Ni(NO) [Me 2Ga(3,5-Me 2pz)(0CH 2CH 2NMe 2)]Ni(N0) [MeGa(3,5-Me 2pz) 3]Ni(N0) [MeGapz 3]Ni(N0) [Me 2Ga(3,5-Me 2pz)»0CH 2(C 5H 4N)]Ni(N0) (n-C 5H 5)Ni(N0) [Ni(CH 3C(CH 2PPh 2) 3)N0] +BF4 1775 (CH 2C1 2) 1770 (C gH 1 2) 1785 (C 6H 1 2) 1786 (C gH 1 2) 1783 (C gH 1 2) 1833 1750 (Nujol) This work 194 194 173 194 196 195 170 Possible mechanisms for the proposed fluxional process are shown in fi g u r e 51. Two p o s s i b i l i t i e s may be envisaged. F i r s t , a trigonal planar intermediate (A) i s formed by breaking the Ni-N(amino) bond, followed by inversion at the pyramidal oxygen and reformation of the Ni-N(amino) bond. A second a l t e r n a t i v e i s via a square-planar intermediate (B) with inversion at the Ni center through the plane. Figure 51. Proposed mechanisms for the fluxional process observed for [Me 2GapzO(C 5H 3N)CH 2NMe 2]Ni(NO) in CDC13 s o l u t i o n . A = trigonal planar; B = square planar. 172 5.3.5 L M(CO)o (M = Mn, Re) 9 _~ Bo th o f t h e s e t r i c a r b o n y l comp lexes gave t h r e e s t r o n g bands i n t h e i r r e s p e c t i v e i r s p e c t r a , i n d i c a t i v e o f a f a c i a l a r r angemen t o f t h e t r i d e n t a t e l i g a n d (see F i g u r e 52). 2006" ieoo ( CM-1 F i g u r e 52. I r s pe c t r um i n t h e v C Q r e g i o n o f [Me 2 Gapz'0 (C g HgN)]Mn(C0) 3 i n c y c l o h e x a n e s o l u t i o n . 173 As evident from Table XVI, p. 174, the values for the Re species are consistently lower than those of the Mn complex, again a reflection of the * stronger 'M-CO' dit-Tt backbonding component in the Re species compared to the valence-isoelectronic Mn compound. Further confirmation of a facial tridentate organogallate ligand in these L M(C0)o compounds is provided by the *H nmr results. A typical q o spectrum is shown for the [Me2Gapz*0(CgHgN)]Re(C0)2 species in figure 53. Of significance in the spectrum is the gallium alkyl region (~9-ll x ) , where two sharp singlets were observed for the 'GaMe2' moiety as expected for inequivalent methyl groups on gallium in a facial arrangement of the ligand. A meridionally coordinated ligand, on the other hand, would lead to equivalent Ga-Me groups, and therefore a singlet in this region of the spectrum. The mass spectral data for both the Mn and Re species are listed in Tables XVII, p. 176 and XVIII, p. 177, respectively. In both compounds, the most intense signals were those attributable to the [MeGa0(CgHgN)]+ ion fragment. While the mass spectrum of the Re species displayed + + prominent parent (P ), and P-Me ion signals, the strongest signals observed for the Mn species were those corresponding to the P-3C0+ ion fragment. This observation lends further support for a stronger 'M-CO' it-backbonding component in the Re compound than in the Mn analog as expected when comparing valence isoelectronic f i r s t and third row transition metal carbonyl compounds in the same group. Table XVI. Phys ica l Data for the Complexes LqMT (where L q • Me 2 Gapz'0(C g HgN)) M T ANALYSIS CALCD/F0UND v co ( c n f l ) (Nujol? *H nmr C H N GaMe2 H 4 H 5 H 3 ' ^ " ^ V Re (co)3 36.36 2.69 7.07 36.21 2.93 7.06 2025,1927,1901 2030,1925,1900 (CC1 4 ) (2025,1915,1895) a 1 0 . 3 3 s 4 .05t 3.19d 2.23d 9.48s Mn (co)3 45.37 3.34 9.34 46.05 3.55 8.86 2040,1950,1920 2035,1948,1915 (THF) a 1 0 . 3 5 s 3.86t 3.13d 2.14d 9.46s Mo (co)2 45.27 3.97 8.34 46.03 3.91 8.33 1955,1863 1950,1858 (CC1 4 ) a 10 .28s 3.85t 3.16d 1.66d 8 .41d,8 .31dH. 9.46s (J = 9.0 Hz) 7.06 br H $ 6.50 br Hy Rh •33C 6 H 6 CO 43.62 3.64 8.98 43.22 3.63 9.34 (1968) a 9 . 8 0 s 3.84t 2.69d 2.28d a C g D 6 ; "tCgHg = 2.84 ppm; J H C C H = 2.0 Hz fo r pz protons . s = s i n g l e t , d = doub let , t = t r i p l e t , br= broad, dd • doublet of doub le ts . 175 176 XVII. fMass Spectral Data of [Me 2Gapz-0(CgH 6N)]Mn(C0) 3 m/e Assignment Intensity 419 [Gapz-0(C 9H 6N)Mn(C0) 3] + 0.1 378 [MeGapz'0(C 9H 6N)Mn(C0) 2] + 0.4 365 [Me 2Gapz-0(C 9H 6N)Mn] + 22.4 335 [Gapz*0(C 9H 6N)Mn] + 2.4 319 [(Me 2Gapz) 2 - Me] + 5.4 251 [(Me 2Gapz) 2 - Me - pzH] + 7.9 243 [Me 2Ga«0(C 9H 6N)] + 6.5 228 [MeGa-0(C gH 6N)] + 100.0 213 [Ga-0(C gH 6N)] + 0.1 199 [0-(C gH 6N)Mn] + 18.3 151 [pzHMn(C0)] + 3.0 99 [Me 2Ga] + 13.8 84 [MeGa] + 1.8 69 Ga + 64.5 At 180°C. 69 Based on Ga. 177 Table XVIII. Mass Spectral Data of [Me 2Gapz'0(C 9H 6N)]Re(C0) m/e Assignment Intensity 581 [Me 2Gapz»0(C 9H 6N)Re(CO) 3] + 17.3 566 [MeGapz'0(C 9H 6N)Re(C0) 3] + 48.4 553 [Me 2Gapz.0(C 9H 6N)Re(C0) 2] + 9.5 510 [MeGapz'0(C gH 6N)Re(C0)] + 5.8 497 [Me 2Gapz.0(C gH 6N)Re] + 33.5 482 [MeGapz'0(C 9H 6N)Re] + 12.3 467 [Gapz'0(C gH 6N)Re] + 6.9 331 [0-(C 9H 6N)Re] + 3.4 228 [MeGa*0(C 9H 6N)] + 100.0 213 [Ga'0(C 9H 6N)] + 14.5 99 [Me 2Ga] + 3.5 78 C 6 H 6 + 2.4 69 Ga + 25.1 1 At 80°C. * 69 187 Based on o yGa and i 0 / R e . 178 5.3.6 L*Mo(C0) 2(n 3-C 3H 5) ( L * = l&, L Q ) * 3 The LMO(C0)2(T] -C3Hg) compounds displayed two strong v C Q bands in t h e i r i r spectra, s i m i l a r to those reported for related molybdenum 3 dicarbonyl 'TI -CgHg' complexes (see Table XIX below), and t h i s i s i n d i c a t i v e of a cis-arrangement of the CO ligands about the Mo atom. 3 Table XIX. Comparison of values in some LMO(C0)2(T) -^5 ) complexes. v C 0 ( c m " 1 ) i n C6 H12 Reference [Me 2GapzO(C 5H 3N)CH 2NMe 2J 1950,1805 This work [Me 2Gapz*0(C 9H 6N)] 1955,1863 This work [Me 2GapzOCH 2(C 5H 4N)] 1942,1855 173 [Me 2Gapz*(0CH 2CH 2NMe 2)] 1934,1848 197 [MeGapz3] 1948, 1860 34 [HBpz 3] 1958,1874 53 E (T)-C 5H 5)] *1970,1963,1903,1889 198 Interpreted as i n d i c a t i v e of the presence of two d i f f e r e n t species in sol u t i o n . * The higher v C Q values observed when L = L Q (see Table XVI, p. 174) i s suggestive of weaker backbonding to the a n c i l l a r y ligand in t h i s complex due to competitive backbonding to the Tt-system of the pyridyl ring in the 179 L" ligand. The i r data recorded f o r the present complexes, together with 3 results from related molybdenum di carbonyl 'TI -^Hg 1 complexes tabulated above, in addition to the AH nmr results discussed below, provide strong evidence f o r f a c i a l l y coordinated tridentate organogallate ligands in the * 3 present L MO(C0) 2(T) -C3Hg) complexes. 1 * 3 The s o l u t i o n H nmr spectra of the L MO(C0) 2(TI -C3Hg) complexes 3 t y p i f i e d by the spectrum of [Me 2Gapz*0(C gHgN)]Mo(C0) 2(T) ^ H g ) complex i n CgDg solu t i o n (figure 54), c l e a r l y show the methyl groups on gallium to be inequivalent, thereby providing more supportive evidence f o r a f a c i a l unsymmetric tridentate organogallate ligand in these complexes. A mer conformation of the unsymmetric tridentate ligand would render the methyl groups on gallium equivalent and hence a s i n g l e t would be observed f o r the '-GaMe2' grouping. Positional isomerism cannot be ruled out in the above 3 complexes, since s u b s t i t u t i o n of the T) -CgHg group f o r a CO in the * * L Mo(CO), (L = L , L ) precursor could p o t e n t i a l l y occur at any one of o a q three positions. It is c l e a r , however, from the nmr spectrum, that 3 s u b s t i t u t i o n of the 'TI -^Hg 1 group occurs excl u s i v e l y at one p o s i t i o n . S u b s t i t u t i o n of t h i s group in more than one position would lead to more than one set of Ga-Me signals in the spectra. Molecular models indicate that s u b s t i t u t i o n opposite the "pyrazolyl" moiety is most favored s t e r i c a l l y , a p o s i t i o n confirmed by X-ray structural determination f o r the related complex [Me 2Ga(3,5-Me 2pz(0CH 2CH 2NH 2)]Mo(C0) 2(Ti 3-C 4H 7) [ 9 8 ] . It i s noteworthy, however, that in the related [Me ?Ga(3,5-Me ?pz)(0CH ?CH ?NH ?)]- CCD, solution. 181 Mo(C0) 2(n 3-C 7H 7) C199], and [Me 2Ga(3,5-Me 2pz)(0CH 2CH 2SEt)]Mo(C0) 2(Ti 3-C 7H 7) 3 [200], the T) -ZJH-J moiety occupies a position opposite the amino nitrogen and the alkyl s u l f u r donor atoms, respectively. This positional 3 preference of the TI -C-,H-, ligand was r a t i o n a l i z e d using structural trans 3 e f f e c t arguments i . e . , an TI -Ĉ H-, group occupying a position trans to the pyrazolyl nitrogen would r e s u l t in close contacts with the amino group or alkyl s u l f i d o group in the l a t t e r complexes. In the *H nmr spectrum of 3 the l_aMo(C0)2(T) -C3Hg) complex in CDCI3, even though two sharp s i n g l e t s were observed for the GaMe2 moiety i n d i c a t i n g inequivalent methyl groups on gallium, the methyl groups of the NMe2 moiety seemingly remained equivalent displaying only one sharp s i n g l e t . This unusual behaviour i s d i f f i c u l t to r a t i o n a l i z e . The presence of only two bands in CH 2C1 2 or cyclohexane for this species indicates the presence of only one isomer, fac, in s o l u t i o n . Apparently some sort of configurational change involving the amino pyridyl moiety of the ligand L~must be operative to a explain the nmr r e s u l t . The two anti protons (H^) for the C^H^ group appeared as two doublets, while the syn protons (H<0 collapsed into a broad unresolved s i n g l e t rather than the expected doublet of doublets f o r a syn proton coupled to two d i f f e r e n t protons, the anti (H A) and the unique proton (Hy). The unique proton (ti^) appeared as a broad unresolved t r i p l e t rather than the more complicated t r i p l e t of t r i p l e t s expected f o r 3 an 'TI -COH,-' group in an unsymmetrical environment. 182 5.3.7 L*Rh(CO) (L* = L , L J . a q The uninegative, e l e c t r o n i c a l l y tridentate cyclopentadienyl, CgHjI, and the analogous s i x - e l e c t r o n donor ligand HB(3,5-Me 2pz) 3, are known to react with [ R h ( C 0 ) 2 C l ] 2 to give the ( r i-C 5H 5)Rh(C0) 2 [201], and [HB(3,5- Me 2pz) 3]Rh(C0) 2 [202,203] complexes respectively. However the introduction of the s i m i l a r HBpz^ and MeGapz^ ligand systems led to the di nuclear rhodium species [HBpz 3] 2Rh 2(p.-C0) 3 [102], and [MeGapz 3] 2Rh 2( u.- C0) 3 [101]. Recently, attempts at i s o l a t i n g rhodium dicarbonyl complexes incorporating the uninegative, unsymmetrical, tridentate [Me2Gapz- (0CH 2CH 2NR 2)]" (R = H, Me), and the [Me 2Gapz'0CH 2(C 5H 4N)]~ ligand systems resulted in the i s o l a t i o n of stable, four-coordinate, square-planar Rh(I) monocarbonyl complexes. In the complexes, s t r u c t u r a l l y characterized by X-ray crystallography as [Me 2Gapz(0CH 2CH 2NH 2)]Rh(C0) [175], and [Me 2Gapz«- 0CH 2(C 5H 4N)]Rh(C0) [176], the coordination mode of the tridentate organogallate ligands about the Rh(I) center was unequivocally demonstrated to be meridional. The reaction of the s t e r i c a l l y more bulky L~ and L~ ligands with a q [ R h ( C 0 ) 2 C l ] 2 dimeric species afforded orange to dark orange c r y s t a l s of ic Rh(I) monocarbonyl compounds via transient dicarbonyl species L Rh(C0) 2 as evident from i r monitoring of the reaction mixture during the course of * the reactions. A proposed sequence for the formation of the L Rh(C0) complexes i s shown in figure 55. The values obtained for the present complexes compare quite well with those reported for related Rh(I) mono- carbonyl complexes (Table XX). 183 2Na*L* L A (A) L P ( B ) [RhCCO)̂ !], VCQ: 2068,1989 (cm"') THF, I reflux O Rh- N N 2085,2025 ( c m - , ) ( A ) i 2 0 8 0 , 2 0 2 0 (B) P 0 Rh CO v • co • 1970 (cm~1)(A) (B) 1968 Figure 55. Proposed reaction sequence for the formation of L Rh(CO) (L* = L g , Lq) complexes. (Note: For c l a r i t y , only the donor s i t e s of the ligands are shown). 184 Table XX. Comparison of values in some LRh(CO) complexes. _ i v C 0 ^ c m ^ 1'n C H 2 C 1 2 Reference [Me 2Gapz*0(C 5H 3N)CH 2NMe 2] 1970 This work [Me 2Gapz«0(C 9H 6N)] 1968 This work [Me 2Gapz(OCH 2CH 2NR 2)] 1957 (R = Me) 175 1955 (R = H) 175 [Me 2Gapz'0CH 2(C 5H 4N)] 1962 176 [Me(Cl)Gapz«0CH 2(C 5H 4N)] 1968 176 The higher v C Q value observed for [Me 2Gapz'0(C gHgN)]Rh(C0) (1968 cm" 1), i n comparison to those observed for [Me 2Gapz(0CH 2CH 2NR 2)]Rh(C0) (1957 cm"1, R = Me; 1955 cm"1, R = H), may well r e s u l t from the n - a c i d i t y of the pyridyl ring in the [Me 2Gapz*0(C gHgN)]~ ligand. The s l i g h t l y higher v C Q value recorded for [Me 2Gapz»0(C 5H 3N)CH 2NMe 2]Rh(C0) (1970 cm"1) may be r e f l e c t i v e of the poor electron-donating a b i l i t y of the [Me 2Gapz»0(CgH 3N)CH 2NMe 2]" ligand. The nmr spectrum of the L qRh(C0) complex in CgDg solution shown in fi g u r e 56 c l e a r l y established the presence of a square planar Rh(I) species in solution for t h i s complex. The sharp s i n g l e t observed for the -GaMe2 group i s consistent with a meridionally coordinated organogallate ligand in the complex. S i m i l a r l y , with the L aRh(C0) compound, sharp s i n g l e t s were displayed for the '-GaMe2', '-NMe2' and '-CH2-' moieties i n 185 conformity with a mer configuration of the ligand i n t h i s square-planar Rh(I) monocarbonyl compound. The mass spectrum of the L Rh(CO) species showed trace signals a (<0.5%) att r i b u t a b l e to the P-3Me+ and P-2Me-C0+ ions. The parent (P +) ion was not observed and the most intense signal in the spectrum was assigned to the C^H^N* ion fragments. In contrast, the mass spectrum of the LqRh(CO) species displayed prominent signals due to the parent (P +) ion, i n addition to signals corresponding to the P-Me+, P-C0+, and P-Me-C0+ ions. The mass spectral data f o r the [Me 2Gapz0(C gH 6N)]Rh(C0) complex are compiled i n Table XXI on p. 187. It is i n t e r e s t i n g to note that signals were displayed at ~172 i n the mass spectrum, suggesting the presence of GaRh + ions.  187 Table XXI. "'"Mass Spectral Data of [Me 9Gapz'0(C qH f iN)]Rh(CO) m/e Assignment Intensity 441 [Me 2Gapz'0(C QH 6N)Rh(C0)] + 16.0 426 [MeGapz'0(C gH 6N)Rh(C0)] + 28.9 413 [Me 2Gapz-0(C 9H 6N)Rh] + 22.2 398 [MeGapz.0(C gH 6N)Rh] + 100.0 383 [Gapz'0(C QH 6N)Rh] + 5.7 316 [Ga'0(C 9H 6N)Rh] + 16.0 228 [MeGa'0(C 9H 6N)] + 68.0 213 [Ga.0(C gH 6N)] + 34.3 199 [pzHRh(C0)] + 10.6 172 [GaRh] + 11.0 145 [H0(C gH 6N)] + 8.3 115 [Me 2Ga«0] + 2.5 103 Rh + 12.4 78 C 6 H 6 + 92.4 69 Ga + 69.9 f At 120°C. * 69 Based on Ga. 188 5.3.8 Reactivity of L*Rh(C0) (L* = L , L ) a H i ) With Mel: The reaction of LqRh(C0) with methyl iodide resulted in the i s o l a t i o n of a five-coordinate Rh(III) acetyl complex [Me2GapzO(C9HgN)]Rh(COMe)I, presumably via a six-coordinate Rh(III) oxidative addition intermediate. Thus, the band of the Rh(I) monocarbonyl s t a r t i n g material at 1968 cm - 1 slowly disappeared upon addition of Mel, and was gradually replaced by two new bands at 2070 and 1700 cm"1 which i n t e n s i f i e d with time. Attempts at i s o l a t i n g the species responsible for the band at 2070 cm"1 f a i l e d , and instead c r y s t a l s of the Rh(III) acetyl complex LqRhfCOMen ( v c o : 1 7 1 0 c m _ 1 > Nujol) were obtained. A proposed reaction sequence for the formation of the Rh(III) acetyl species i s shown in figur e 57. It i s postulated that the band at 2070 cm"1, observed i n solution during the reaction in the above sequence, i s probably due to the presence of a l a b i l e six-coordinate Rh(III) product. Thus, alkyl haiides o are generally known to oxidatively add to square-planar d Rh(I) and Ir ( I ) centers v ia th i s mode [204,205]. This six-coordinate Rh(III) intermediate subsequently undergoes a methyl migration reaction to form the five-coordinate Rh(III) complex L qRh(C0Me)I, containing a terminal acetyl group. The solution i r spectrum of the Rh(III) acetyl product i s o l a t e d i s i n t e r e s t i n g in that i t shows two bands at ~2070 cm"1 and 1700 cm"1 in CH 2C1 2, but in Nujol mull, only one strong v C Q band was observed at ~1710 cm"1. This observation reveals the presence of both the six-coordinate Rh(III), and the five-coordinate Rh(III) acetyl species in so l u t i o n . A  190 s i m i l a r observation has been reported for the compound [Ru(ri -COMe)I(CO)- 2 ( P M e ^ L an TI -acyl complex which exists in equilibrium with i t s carbonyl a - a l k y l isomer, [Ru(CO) 2(Me)I(PMe 3) 2], in solution [206]. The nmr spectrum of the present L Rh(C0Me)I complex in CDCU q o solution ( f i g u r e 58) i s consistent with a square pyramidal arrangement about the Rh center, since such a non-planar arrangement would render the methyl groups on gallium inequivalent. The presence of two sharp s i n g l e t s for the 'GaMe2' moiety in the spectrum i s in agreement with the above arrangement. The position of the COMe signal (7.58x, CDCl-j) compares nic e l y with those reported for s i m i l a r rhodium acetyl compounds [17,176,207]; and the square pyramidal arrangement proposed has been established by X-ray crystallography for the c l o s e l y related [Me 2Gapz(0CH 2CH 2NMe 2)]Rh(C0Me)I complex [175]. The mass spectral data for the [Me2Gapz*0(CQHgN)]Rh(COMe)I complex are c o l l e c t e d in Table XXII, p. 192. Signals corresponding to the parent, P +, P-Me+, P-Me-I+, P-2Me-I+, and P-Me-C0+ ions were observed in the mass spectrum of t h i s compound, but no P-C0 + signals were observed. Signals a r i s i n g from the l a t t e r ion are usually c h a r a c t e r i s t i c of t r a n s i t i o n metal carbonyl compounds containing terminally bound CO groups. 191 192 Table XXII. +Mass Spectral Data of [Me 2Gapz*0(C gH 6N)]Rh(C0Me)I m/e Assignment Intensity 583 [Me 2Gapz»0(C 9H 6N)Rh(C0Me)I] + 1.3 568 [MeGapz•0(CgH gN)Rh(COMe)I] + 15.2 553 [Gapz«0(C 9H 6N)Rh(C0Me)I] + 0.9 540 [MeGapz'0(C gH 6N)RhMeI] + 4.5 525 [Gapz'0(C gH 6N)RhMeI] + 9.8 510 [Gapz'0(C gH 6N)RhI] + 4.9 456 Cpz0(C gH 6N)RhMeI] + 8.5 441 [Me 2Gapz»0(C gH 6N)Rh(C0)] + 8.0 426 [MeGapz*0(C gH 6N)Rh(C0)] + 14.3 413 [Me 2Gapz«0(C gH 6N)Rh] + 12.1 398 [MeGapz»0(C gH 6N)Rh] + 100.0 383 [Gapz»0(C gH 6N)Rh + 4.9 316 [Ga«0(C gH 6N)Rh] + 14.7 288 [ { 0 ( C g H 6 N ) } 2 ] + 8.0 247 [0(C gH 6N)Rh] + 6.7 228 [MeGa»0(C gH 6N)] + 77.2 213 [Ga»0(C gH 6N)] + 38.4 199 [pzHRh(C0)] + 9.8 142 [ M e l ] + 21.9 193 Table XXIII. +Mass Spectral Data of [Me 2Gapz»0(C QH 6N)]Rh(C0Me)I (Cont'd) * m/e Assignment Intensity 127 I + 8.0 115 [Me 2Ga*0] + 4.5 103 Rh + 11.6 84 [MeGa] + 31.7 78 C g H 6 + 22.3 69 Ga + 55.8 58 Me 2C0 + 72.3 51 t At 150°C. * 69 Based on Ga. In contrast to the mode of r e a c t i v i t y discussed above for the L^Rh- (C0) complex, the reaction of the L aRh(C0) monocarbonyl complex with Mel a proceeds d i r e c t l y to the formation of what i s thought to be a s i x - coordinate Rh(III) oxidative trans-addition product L Rh(Me)(I)C0. Quite a i n t e r e s t i n g l y , such six-coordinate addition products containing a-bonded methyl groups have not been observed either as intermediates or as the net reaction products in the analogous reaction of the related cyclopenta- dienyl rhodium carbonyl compounds with Mel. For example, reaction of ( r i-C 5Me 5)Rh(C0) 2 with Mel proceeds d i r e c t l y to the (ri-C 5Me 5)Rh(C0)(COMe)I acetyl complex at 50°C [208]. Thus, the diagnostic terminal v r n band at 194 2060 cm" , observed dur ing the r eac t i on of L Rh(CO) w i th Me l , prov ided a s t rong evidence f o r the presence of a s i x - c oo rd i na t e Rh(111) spec ies i n s o l u t i o n . The on ly c r y s t a l l i n e product i s o l a t e d from the r eac t i on of L Rh(CO) a wi th Mel was i d e n t i f i e d as the s i x - c oo rd i na t e t r a n s - add i t i o n Rh ( I I I ) d e r i v a t i v e , s ince only a s i n g l e band was observed i n the carbonyl s t r e t c h i n g frequency r eg i on , and no band was seen i n the ace ty l s t r e t c h i n g frequency reg ions of the spectrum ( V C Q : 2060 c m - 1 , CH 2 C1 2 ; 2055 c m - 1 , N u j o l ) . These i r r e s u l t s are c on s i s t en t w i th a s i x - c oo rd i na t e Rh ( I I I ) spec ies formulated as [Me 2 Gapz'0(C 5 H 3 N)CH 2 NMe 2 ]Rh(Me)(I)CO. The room temperature X H nmr data f o r the present L,Rh(Me)(I)C0 a compound d i s p l a y i n g two sharp s i n g l e t s f o r the 'GaMe 2 ' and 'NMe 2 ' groupings were c on s i s t en t w i th a f a c i a l coo rd ina t i on of the o rganoga l l a te l i g a n d . A sharp s i n g l e t was observed f o r the Rh-Me resonance at ~9.3x; s i gna l s a t t r i b u t a b l e to a -COMe resonance were not observed i n the spectrum. A mass spec t r a l study of the L .RMMeHDCO complex under e l e c t r on a impact (EI) c ond i t i on s d id not g ive a spectrum of any worth probably due to thermal l a b i l i t y or n o n - v o l a t i l i t y of the compound. However, w i th the Fas t Atom Bombardment (FAB) techn ique, s i gna l s corresponding to the [ P -Me ] + , [P+H] + and [ P - H ] + ions were observed. The [P+H] + and [ P - H ] + ions are gene ra l l y c h a r a c t e r i s t i c f o r molecules i on i z ed by the FAB technique [209] . The presence of s i g na l s corresponding to the [P+H] + , and [ P - H ] + 195 ions in the mass spectrum is an i n d i r e c t confirmation of the molecular weight of t h i s compound at ~590, and the formulation is f u r t h e r supported by elemental analyses data (see section 5.2.17, p. 146). It is noteworthy however, that the FAB technique was recently used successfully to determine the molecular weight of the s i l y l rhodium species, (ri-C 5H 5)RhC0DSi (CH 2) 3(MeO) 3 [210], an organometallic compound that is highly i n t r a c t a b l e , o i l y , thermally l a b i l e , and moisture-sensitive. In order to e s t a b l i s h the correct structure of the present complex unequivocally, c r y s t a l s of the [Me 2Gapz*0(C 5H 3N)CH 2NMe 2]Rh(Me)(I)C0 compound have been submitted f o r X-ray crystal structure determination which is currently in progress, i i ) With I 2 : Addition of molecular iodine to a CH 2C1 2 solution of L Rh(CO) (L = L g , L q ) resulted in the immediate disappearance of the band att r i b u t a b l e to the appropriate Rh(I) monocarbonyl s t a r t i n g material with -1 * concomitant appearance of a new V ^ Q band at 2090 cm (L = L f l ) , or 2085 -1 * cm (L = Lq). The new bands suggest a weakly-bound CO ligand to the Rh o metal center i n the products. Oxidation of the rhodium center (Rh(I)(d ) •*• Rh(III)(d^)) would lead to weaker backbonding contribution from the metal, a strengthening of the C-0 bond and consequently an increased V ^ Q value. Based on t h i s observation, i t does appear that a six-coordinate * Rh(III) diiodide species L RhI 2(C0) had formed, although a n a l y t i c a l l y pure samples of the product could not be i s o l a t e d . The V ^ Q values of the * present L RhI 2(C0) species are in good agreement with those reported f o r sane related Rh(III) diiodides (see Table XXIV below). 196 Table XXIV. Comparison of v r n values in LRhI ?(C0) complexes. L v c o ( c m - 1 ) in CH^Cl 2 Reference [Me 2Gapz'0(C 5H 3N)CH 2NMe 2] 2090 This work [Me 2Gapz«0(C gH 6N)] 2085 This work [Me 2Gapz(0CH 2CH 2NR 2)] (R = H, Me) 2090 175 [Me 2Gapz'0CH 2(C 5H 4N)] 2095 176 [HB(3,5-Me 2pz) 3] 2090 203 [HBpz 3] 2112 102 CBpz 4] 2100 102 [(n-C 5H 5)] 2065 (Nujol) 211 [(n-C 5Me 5)] 2035 212 It i s i n t e r e s t i n g , however, that the values for the pyrazolyl g a l l ate/- borate-containing species are consistently higher than the values reported for the analogous cyclopentadienyl-containing rhodium diiodide species. This i s rather unusual since they oppose the trend previously established for complexes incorporating these ligands [34,53]. That i s , p y r a z o l y l - g a l l a t e t r i dentate ligands, and the related i s o e l e c t r o n i c tridentate pyrazolylborate anions, are generally stronger net electron donors compared to the tridentate cyclopentadienyl ligand and give r i s e to lower v „ n values in analogous t r a n s i t i o n metal carbonyl complexes. 197 5.4 Summary The coordination compounds [Me 2GaO(C 5H 3N)CH 2NMe 2], and [Me 2Ga»0- (CgHgN)] 2 have been i s o l a t e d and s t r u c t u r a l l y characterized by X-ray c r y s t a l structure analyses. The l a t t e r compound i s dimeric with each gallium atom assuming a d i s t o r t e d trigonal bipyramidal geometry. S t e r i c constraints prevented dimerization of the '[Me 2GaO(C 5H 3N)CH 2NMe 2]' compound, which consists of monomeric units containing t e t r a h e d r a l l y coordinated gallium atoms. Facial coordination of the [Me 2Gapz»0(CgH 6N)]~ (L~) ligand has been demonstrated for a variety of t r a n s i t i o n metal complexes. The v e r s a t i l i t y of the [Me 2Gapz'0(C 5H 3N)CH 2NMe 2]" (L~) ligand has been demonstrated by the successful i s o l a t i o n of the L,M(C0)o (M = Mn, Re) octahedral complexes a o which e x i s t in both fac and mer conformations in s o l u t i o n . The l a t t e r complexes represent the f i r s t and the only t r a n s i t i o n metal carbonyl complexes in which both the fac and mer isomers, incorporating the t r i d e n - tate ligand, have been shown to co-exist in solution. The four-coordinate nickel n i t r o s y l complex L Ni(NO) i s believed to possess a tetrahedral a t r a n s i t i o n metal center, although stereochemical nonrigidity of the complex in solution must be operative to explain the square-planar arrangement suggested by the room temperature *H nmr spectral data. Meridional coordination has also been demonstrated for the L", and L~ a q ligands in the formation of the four-coordinate square-planar Rh(I) •k ic monocarbonyl species, L Rh(CO) (L = L , L ). These compounds undergo a q f a c i l e oxidative addition reaction with molecular iodine to give Rh(III) 198 * di iodide L RhI 2(C0) species. However, with methyl iodide, LqRh(C0) undergoes f a c i l e oxidative addition, followed by methyl migration to give a five-coordinate Rh(III) acetyl species LqRh(C0Me)I. In contrast, LqRh(C0) oxi d a t i v e l y adds methyl iodide to give what i s thought to be a six-coordinate Rh(III) trans-addition species L Rh(Me)(I)C0 as the net a reaction product. 199 CHAPTER VI CONCLUSION AND PERSPECTIVES The MeGapZg" and HBpz 3 ligands can, on the one hand, successfully mimic the behaviour of the ri-C^Hg ligand system but, more importantly, on the other hand they can display s i g n i f i c a n t l y d i f f e r e n t behaviour. This v e r s a t i l i t y has been demonstrated in the present work by exploring the r e a c t i v i t y of the LMo(C0) 3 anions towards (i) alkyl haiides and protonating species (L = MeGapz 3), ( i i ) a variety of t r a n s i t i o n metal halide species (L = MeGapz^ or HBpz-j) and ( i i i ) group 14 ( S i , Ge, Sn) alkyl or aryl halide species (L = MeGapz^). The successful i s o l a t i o n of the M +MeGapz 3Mo(C0) 3 (M + = Na +, Et^N +, HAsPh 3) s a l t s , the requirement of a strong acid to f u l l y protonate the MeGapz 3Mo(C0) 3 anion, the d i s s o c i a t i o n of the Mo-H bond in the hydride [MeGapz 3]Mo(C0) 3H, and the transformation of the '[MeGapz 3]Mo(C0) 3Me 1 2 a-methyl complex to the quasi-six-coordinate [MeGapz3]Mo(C0)2 (TI -COMe) taken together suggests a strong preference f o r six-coordination by the Mo centre in complexes containing the MeGapz3 ligand. The transformation of the [MeGapz 3]Mo(C0) 3R species and the related [HBpz 3]Mo(C0) 3R (R = Me, Ph) compounds to the LMO(C0) 2(T) -COR) complexes (L = MeGapz3 or HBpz 3; R = Me or Ph) has never been duplicated in the chemistry of the analogous 200 (TI-C 5H 5)MO(C0) 3R or (t)-C 5Me 5)Mo(C0) 3R complexes. However, the lack of 2 success in forming an rj -COEt product in the present study is probably related to the i n s t a b i l i t y of the a-ethyl [MeGapz 3]Mo(C0) 3Et precursor and i t s tendency to decompose. In f a c t , the pronounced i n s t a b i l i t y , d i f f i c u l t y in p u r i f i c a t i o n , and decomposition accompanied by the formation of ethylene has been noted previously by McCleverty and Wilkinson f o r the analogous (t)-C 5H 5)Mo(C0) 3Et compound [213]. S i m i l a r d i f f i c u l t y may have been encountered by Curtis et a l . who provided structural information f o r the [HBpz 3]Mo(C0) 2(ii 2-C0R) (R = Me, Ph) compounds [65] with no data f o r 2 the corresponding TI -COEt de r i v a t i v e . In any event, mechanistic studies 2 as well as thermodynamic data f o r these LMO(C0) 2(T) -COR) (L = MeGapz3 or HBpz 3; R = alkyl or aryl) complexes should provide some clues as to the 2 factors governing the s t a b i l i t y of the above TI -acyl compounds over the seven-coordinate LMo(C0) 3R precursors. Such information may provide useful insights into the p o s s i b i l i t y of promoting hydride migration from a metal hydride to a coordinated CO group in the same metal to form an 2 TI -formyl complex. The above reaction has never been d i r e c t l y observed but the reverse reaction is well established [96]. One of the primary objectives of t h i s work was to develop a synthetic route to heterobi metal l i e complexes incorporating the tridentate pyrazolyl gal late/borate ligands in which direct metal-metal bonds are featured and to provide insights into the s t r u c t u r a l , spectroscopic and bonding properties of these compounds. This objective has largely been f u l f i l l e d . The 3:3:1 structure demonstrated f o r the [MeGapz 3]Mo(C0) 3X (X = CuPPh 3 or SnPho) complexes represents the f i r s t and the only known examples of t h i s 201 geometry f o r LMo(C0) 3X (L = r)-C 5H 5, HBpz 3 or MeGapz3; X = two electron donor ligand) type complexes. It appears from this study, that the 3:3:1 structure is most favoured by a substituent pattern which include an a n c i l l a r y ligand with low energy vacant o r b i t a l s of appropriate symmetry, and a single substituent that is both a good a donor and a good n donor, yet small in s i z e , occupying the axial p o s i t i o n . The above factors are i n accord with the t h e o r e t i c a l predictions of Kubacek et a l . [141], and Hoffmann et a l . [214]. As noted by the former authors, an axial halide (even though a good it donor), d e s t a b i l i z e s the 3:3:1 structure. This is borne out by the adoption of a 3:4 structure by Curtis 'bromo' derivative HBpz 3Mo(C0) 3Br [60], and also the f l u x i o n a l behaviour of the 'SnMe 2Cl' de r i v a t i v e discussed in Chapter IV. The s i m i l a r i t y in spectroscopic properties of the Mo-M1 (M1 = Zr or Hf) compounds to those of the Mo-M1 (M1 = S i , Ge or Sn) complexes is a r e f l e c t i o n of the tendency of highly electron d e f i c i e n t t r a n s i t i o n metals in high oxidation states to behave l i k e main group elements (Lewis acids). The general chemical r e a c t i v i t y of the heterobimetal 1 i c compounds reported in t h i s thesis needs furt h e r investigation. Preliminary studies in t h i s regard, indicated the formation of unidentified mixture of compounds. It may well be that the s t e r i c bulk of the tridentate pyrazolyl gallate/borate ligand is an i n h i b i t i n g f a c t o r in the r e a c t i v i t y of these compounds. In fact the related homobi metal l i e [HBpz 3] 2Mo 2(C0) 4 (Mo^Mo) dimer has been reported as unreactive toward acetylenes, Ph 2CN 2, CH 2N 2, P(0Me) 3 and CO by Curtis et a l . [38]. Further studies into the c a t a l y t i c potential of these heterobimetal l i e complexes is needed e s p e c i a l l y f o r complexes of the type LMM' (where L = MeGapz , or HBpz ; 202 M = Ti-Hf or V-Ta; and M1 = Ru, Rh, Ir, Pd or Pt) . One obvious problem i n t h i s regard, i s to ensure that the i n i t i a l complex remains i n t a c t during the c a t a l y t i c c y c l e . In Chapter V, the ligand L~ gave the dimer [Me 2GaO(C 9H 6N)] 2, and the fac L M(CO) 0 (M = Mn or Re) complexes. In contrast, the L a ligand y i e l d e d q o a the monomer Me 2GaO(C 5H 3N)CH 2NMe 2 and both the fac and mer isomers of L M(CO).j (M = Mn or Re) complexes. The l a t t e r octahedral tricarbonyl a o complexes are the only examples of such complexes incorporating the unsymmetric tridentate ligand in both the fac and mer conformations. It i s d i f f i c u l t to r a t i o n a l i z e the difference in r e a c t i v i t y toward Mel observed for the L Rh(CO) and L Rh(CO) complexes. It i s probable, a q however, that the Rh-Me bond i s stronger in the L Rh(Me)(I)CO species a compared to the LqRh(Me)(I)CO species, hence methyl migration i s discouraged in the former compound. These observations i l l u s t r a t e how a s l i g h t change in the design of the unsymmetric ligands can lead to s i g n i f i c a n t l y d i f f e r e n t behaviour. 203 References 1. E. Buchner, Ber. 22, 842 (1889). 2. J . J . Kaufman, H.J.T. Preston, E. Kernman and C.L. Cusachs, Int. J . Quantum Chem., Symp 7, 249 (1973). 3. G. Dedichen, Ber. 39, 1831 (1906). 4. G. Minghetti, G. B a n d i t e l l i and F. Bonati, J . Chem. S o c , Dalton Trans., 1851 (1979). 5. A.L. Bandini, G. B a n d i t e l l i , F. Bonati, F. Demartin, M. Manassero and G. Minghetti, J . Organomet. Chem. 238, C9 (1982). 6. C.W. Eignbrot, J r . and K.N. Raymond, Inorg. Chem. 20, 1553 (1981). 7. S. Trofimenko, Chem. Rev. 72, 497 (1972). 8. R.B. King and A. Bond, J . Organomet. Chem. 73, 115 (1974). 9. K.S. Chong, S.J. Rett i g , A. S t o r r and J . Trotter, Can. J . Chem. 57, 3090 (1979). 10. R. Us6n, L.A. Oro, M.A. Ciriano, M.T. P i n i l l o s , A. T i r i p i c c h i o and M, T i r i p i c c h i o Camellini, J . Organomet. Chem. 205, 247 (1981). 11. K.A. Beveridge, G.W. Bushnell and S.R. Stobart, Organometallics 2, 1447 (1983). 12. S. Trofimenko, J . Am. Chem. Soc. 89, 3170 (1967). 13. S. Trofimenko, J . Am. Chem. Soc. 92, 5118 (1970). 14. K.R. Breakell, D.J. Patmore and A. Storr, J . Chem. S o c , Dalton Trans. 749 (1975). 15. M. DiVaira and F. Mani, Inorg. Chim. Acta 70, 99 (1983). 16. S. Trofimenko, Accts. Chem. Res. 4_, 17 (1971). 17. A. Shaver, J . Organomet. Chem. L i b r . 3_, 157 (1977). 18. S. Trofimenko, Inorg. Synth. 12, 99 (1970). 19. CA. Kosky, P. Ganis and G. A v i t a b i l e , Acta Cryst. Sect. B 27, 1859 (1971). 20. G.J. Bullen, R. Mason and P. Pauling, Inorg. Chem. 4, 456 (1965), and references therein. 204 21. F.A. Cotton, M. Jeremic and A. Shaver, Inorg. Chim. Acta 6̂, 543 (1972). 22. M.I. Bruce and A.P.P. Ostazewski, J . Chem. S o c , Chem. Commun., 1124 (1972). 23. F.A. Cotton and T.J. Marks, J . Am. Chem. Soc. 92, 5114 (1970). 24. H.C. Clark and L.E. Manzer, Inorg. Chem. 13, 1291 (1974). 25. H.C. Clark and L.E. Manzer, J . Am. Chem. Soc. 95, 3812 (1973). 26. P.M. T r e i c h e l , W.J. Knebel and R.W. Hess, J . Am. Chem. Soc. 93, 5424 (1971). 27. A.D. Westland, J . Chem. S o c , 3060 (1965). 28. D.H. Gerlack, A.R. Kane, G.W. Pars h a l l , J.P. Jesson and E.L. Muetterties, J . Am. Chem. S o c 93, 3543 (1971). 29. G.A. Larkin, R. Mason and M.G.H. Wallbridge, J. Chem. S o c (D), 1054 (1971). 30. H.C. Clark and R.J. Puddephatt, Inorg. Chem. 10, 18 (1971). 31. S. Trofimenko, Inorg. Chem. 8, 2675 (1969). 32. T. Desmond, F.J. Lai or, G. Ferguson, B. Ruhl and M. Parvez, J . Chem S o c , Chem. Commun., 55 (1983). 33. T. Desmond, F.J. Lai or, G. Ferguson and M. Parvez, J . Chem. S o c , Chem. Commun., 457 (1983). 34. K.R. Breakell, S.J. Rett i g , D.L. S i n g b e i l , A. Stor r and J . T r o t t e r , Can. J . Chem. 56, 2099 (1978). 35. K.R. Breakell, S.J. Rett i g , A. Stor r and J . Tro t t e r , Can. J . Chem. 57, 139 (1979). 36. M.R. C h u r c h i l l , K. Gold and C.E. Maw, J r . , Inorg. Chem. 9, 1597 (1970). 37. B.K. Nicholson, J . Organomet. Chem. 265, 153 (1984). 38. M.D. C u r t i s , K. Shui, W.M. Butler and J.C. Huffman, J . Am. Chem. Soc. 108, 3335 (1986). 39. S.J. Rettig, A. Stor r and J . Tro t t e r , Can. J . Chem. 57̂ , 1823 (1979). 40. W.J. Kasowski and J.C. B a i l a r , J r . , J . Am. Chem. S o c 91, 3212 (1969). 205 41. K.S. Chong, S.J. Rett i g , A. St o r r and J. Trotter, Can. J . Chem. 5_5, 4166 (1977). 42. J.S. Thompson, J.L. Zitzman, T.J. Marks and J.A. Ibers, Inorg. Chim. Acta 46, L101 (1980). 43. K.S. Chong, S.J. Rett i g , A. S t o r r and J . Trotter, Can. J . Chem. 56, 1212 (1978). 44. K.S. Chong, S.J. Rett i g , A. Stor r and J . Trotter, Can. J . Chem. 57, 1335; 3113 (1979). 45. W.L. J o l l y , The Synthesis and Characterization of Inorganic Compounds, Pre n t i c e - H a l l , Inc., New Jersey (1970). 46. J.A. Riddick and W.B. Burger, Organic Solvents, Physical Properties and Methods of P u r i f i c a t i o n , 3rd, e d i t i o n , Techniques of Chemistry Vol. II, John Wiley and Sons, Inc., New York (1970). 47. A. S t o r r and B.S. Thomas, Can. J . Chem. 48, 3667 (1970). 48. N.N. Greenwood and K. Wade, J . Chem. S o c , 1527 (1956). 49. H.Schmidbaur and W. Findeiss, Angew. Chem., Int. Ed. 3, 696 (1964). 50. D.P. Tate, W.R. Knipple and J.M. Augl, Inorg. Chem. ̂ 1, 433 (1962). 51. F.A. Cotton, Inorg. Chem. _3, 702 (1964). 52. K.F. Purcell and J.C. Kotz, Inorganic Chemistry, W.B. Saunders Company, Philadelphia (1977). 53. S. Trofimenko, J . Am. Chem. Soc. 91_, 588 (1969). 54. F.A. Cotton, CA. M u r i l l o and B.R. S t u l t s , Inorg. Chim. Acta 22, 75 (1977). 55. T.S. Piper and G. Wilkinson, J . Inorg. Nucl. Chem. 3_, 104 (1956). 56. M. Cousins and M.L.H. Green, J . Chem. S o c , 889 (1963). 57. R. Davis and L.A.P. Kane-Magui re. In Comprehensive Organometallic Chemistry, Vol 3; Pergamon Press; Oxford, England (1982). 58. W.W. Greaves ad R.J. A n g e l i c i , J . Organomet. Chem. 191, 49 (1980). 59. D.L. Reger, CA. Swift and L. Lebioda, Inorg. Chem. 23, 349 (1984). 60. M.D. Curti s and K. Shiu, Inorg. Chem. 24, 1213 (1985). 61. M.D. Curtis and R.J. K l i n g l e r , J . Organomet. Chem. 161, 23 (1978). 206 62. D.S. Ginley, CR. Bock and M.S. Wrighton, Inorg. Chim. Acta 23, 85 (1977). 63. K.W. Barnett, D.W. Slocum, J . Organomet. Chem. 44, 1 (1972). 64. M.D. C u r t i s , K. Shiu and W.M. Butler, Organometallics 2, 1475 (1983). 65. M.D. C u r t i s , K. Shiu and W.M. Butler, J . Am. Chem. Soc. 108, 1550 (1986). 66. E.C. Onyiriuka and A. Storr, Can. J . Chem., submitted. 67. S.W. Ulmer, P.M. Skarstad, J.M. Burl itch and R.E. Hughes, J. Am. Chem. Soc. 95, 4469 (1973). 68. G. F a c h i n e t t i , C. F l o r i a n i , P.F. Zanazzi and A.R. Zanazari, Inorg. Chem. 17, 3002 (1978). 69. W.F. Edgell, M.T. Yang and N. Koizumi, J . Am. Chem. Soc. 87, 2563 (1965). 70. W.F. Edgell and J . Lyford, J . Am. Chem. Soc. 93, 6407 (1971). 71. K.H. Pannel and D. Jackson, J . Am. Chem. Soc. 98, 4443 (1976). 72. M. Nitay and M. Rosenblum, J . Organomet. Chem. 136, C23 (1977). 73. M.Y. Darensbourg, P. Jimenez, J.R. Sackett, J.M. Hanckell and R.L. Kump, J . Am. Chem. Soc. 104, 1521 (1982). 74. P. P o l i t z e r and P.H. Reggio, J . Am. Chem. Soc. 94, 8308 (1972). 75. V.R. Feld, E. Hellner, A. Klopch and K. Dehnicke, Z. Anorg. A l l g . Chem. 442, 173 (1978). 76. C.P. Horwitz and D.F. Shriver, Adv. Organomet. Chem. 23, 219 (1984). 77. M.Y. Darensbourg, Prog. Inorg.Chem. 33, 221 (1985). 78. S.W. Benson. The Foundations of Chemical K i n e t i c s , McGraw-Hill; New York (1960) pp. 495, 496. 79. R.S. Drago. Physical Methods i n Chemistry, W.B. Saunders Company; Philadelphia (1977). 80. D.M. Adams. Metal-ligand and Related Vibrations, Edward Arnold (Publishers) Ltd., London (1967). 81. P. Leoni, E. G r i l l i , M. Pasquali and M. Tomassini, J . Chem. S o c , Dalton Trans., 1041 (1986). 207 82. R.B. King and M.B. Bisnette, J . Organomet. Chem. 8, 287 (1967). 83. R.B. King and M.B. Bisnette, Inorg. Chem. 4, 475 (1965). 84. F. Calderazzo, Angew. Chem. 89, 305 (1977). 85. F. Calderazzo, Angew. Chem., Int. Ed. Engl. 16, 299 (1977). 86. CR. Jablonski and Y. Wang, Inorg. Chem. 21̂ , 4037 (1982). 87. C. Masters, Adv. Organomet. Chem. 1_7, 61 (1979). 88. CK. Rofer-De Poorter, Chem. Rev. 81, 447 (1981). 89. W.A. Herrman, Angew. Chem., Int. Ed. Eng. 21. 117 (1982). 90. H.G. A l t , J . Organomet. Chem. 127, 349 (1977). 91. R.M. Medina and J.R. Masaguer, J . Organomet. Chem. 299, 341 (1986). 92. E.C Onyiriuka, S.J. Rettig and A. Storr, Can. J . Chem. 64, 321 (1986). 93. M.J. Bennett and R. Mason, Proc. Chem. S o c , 273 (1963). 94. S.P. Nolan, R. Lopez de l a Vega, S.L. Mukerjee and CD. Hoff, Inorg. Chem. 25, 1160 (1986). 95. M.J. Wax and R.G. Bergman, J . Am. Chem. Soc. 103, 7028 (1981). 96. J.P. Collman and L.S. Hegedus. P r i n c i p l e s and Applications of Organotransition Metal Chemistry, University Science Books; M i l l Valley, C a l i f o r n i a (1980). 97. P.J. Craig and M. Green, J . Chem. Soc. (A), 1978 (1968). 98. K.S. Chong, S.J. Rett i g , A. S t o r r and J . Tro t t e r , Can. J . Chem. 57, 1335 (1979). 99. K.S. Chong and A. Storr, Can. J . Chem. 58, 2278 (1980). 100. K.S. Chong, S.J. Rett i g , A. S t o r r and J . Trotter, Can. J . Chem. 5_9, 2391 (1981). 101. B.M. Louie, S.J. Rett i g , A. S t o r r and J . Tro t t e r , Can. J . Chem. 62, 633 (1984). 102. M. Cocivera, T.J. Desmond, G. Ferguson, B. Kaitner, F.J. La l o r and D.J. O'Sullivan, Organometallics 1, 1125 (1982). 208 103. O.S. M i l l s and J.P. Nice, J . Organomet. Chem. 10, 337 (1967). 104. L. Carlton, W.E. L i n d s e l l , K.J. McCullough and P.N. Preston, J . Chem. S o c , Dalton Trans., 1693 (1984). 105. R.D. Barr, T.B. Marder, A.G. Orpen and l.D. Williams, J . Chem. S o c , Chem. Commun., 112 (1984). 106. M. Green, J.A.K. Howard, A.P. James, CM. Nunn and F.G.A. Stone, J . Chem. S o c , Chem. Commun., 1113 (1984). 107. R.D. Barr, M. Green, K. Marsden, F.G.A. Stone and P. Woodward, J . Chem. S o c , Dalton Trans., 507 (1983). 108. L.J. Farraguia, A.D. Miles and F.G.A. Stone, J . Chem. S o c , Dalton Trans., 2415 (1984). 109. R.D. Barr, M. Green, J.A.K. Howard, T.B. Marder, A.G. Orpen and F.G.A. Stone, J . Chem. S o c , Dalton Trans., 2757 (1984). 110. C.P. Casey, R.M. Bullock and F. Nief, J . Am. Chem. Soc. 105, 7574 (1983). 111. R.G. Finke, G. Gaughan, C. Pierpont and M.E. Cass, J . Am. Chem. Soc. 103, 1394 (1981). 112. 0. Bars and P. Braunstein, Angew Chem. Int. Ed. Engl. 21, 308 (1982). 113. D.A. Roberts, W.C Mercer, S.M. Zahurak, G.L. Geoffroy, C.W. DeBrosse, M.E. Cass and CG. Pierpont, J . Am. Chem. Soc. 104, 910 (1982). 114. D.A. Roberts and G.L. Geoffroy, In Comprehensive Organometallic Chemistry, Vol. 6, G. Wilkinson, F.G.A. Stone and E.W. Abel Eds. Pergamon Press, Oxford, England (1982) p. 763. 115. G.S. White and D.W. Stephan, Inorg. Chem. 24, 1499 (1985). 116. 0. S t e l z e r and E. Linger, Chem. Ber. 110, 3430, 3438 (1977). 117. T.S. Targos, R.P. Rosen, R.R. Whittle and G.L. Geoffroy, Inorg. Chem. 24, 1375 (1985). 118. R.T. Baker, T.H. Tu l i p and S.S. Wreford, Inorg, Chem. 24, 1379 (1985). 119. G.L. Geoffroy, Acc. Chem. Res. 13, 469 (1980). 120. W.L. G l a d f e l t e r and G.L. Geoffroy, Adv. Organomet. Chem. 18, 207 (1980). 209 121. F.A. Cotton, Prog. Inorg. Chem. n, 1 (1976). 122. R. Colton and M.J. McContiick, Coord. Chem. Rev. 31_, 1 (1980). 123. A. Bino, F.A. Cotton, P. Lahuerta, P. Puebla and R. Uson, Inorg. Chem. 19, 2357 (1980). 124. G.A. Banta, B.M. Louie, E. Onyiriuka, S.J. Rettig and A. Storr, Can. J. Chem. 64, 373 (1986). 125. S. Trofimenko, Inorg. Synth. .12, 102 (1970). 126. G. Costa, E. Reisenhofer and L. Stefani, J . Inorg. Nucl. Chem. 27, 2581 (1965). 127. H.C. Clark and L. Manzer, J . Organomet. Chem. 59, 411 (1973). 128. B. Haymore and R.D. Feltham, Inorg. Synth. 14, 81 (1973). 129. M.H. Quick and R.J. A n g e l i c i , Inorg. Synth. 19, 160 (1979). 130. F. Bonati and G. Wilkinson, J . Chem. S o c , 179 (1964). 131. D.J. Patmore and W.A.G. Graham, Inorg. Chem. 5_, 1405 (1966). 132. C. Lee, G. Besenyei, B.R. James, D.A. Nelson and M.A. L i l g a , J . Chem. S o c , Chem. Commun., 1175 (1985). 133. R.G. Finke, G. Gaughan, C. Pierpont and J.H. Noordik, Organometallics 2, 1481 (1983). 134. M.L. Aldridge, M. Green, J.A.K. Howard, G.N. Pain, S.J. Porter, F.G.A. Stone and P. Woodward, J . Chem. S o c , Dalton Trans., 1333 (1982). 135. R.H. Crabtree and M. Lavin, Inorg. Chem. 25, 805 (1986). 136. R.J. Klinger, W.M. Butler and M.D. Cu r t i s , J . Am. Chem. Soc. 100, 5034 (1978). 137. F.C. Wilson and D.P. Shoemaker, J . Chem. Phys. 27, 809 (1957). 138. F.C. Wilson and D.P. Shoemaker, Naturwiss 43, 57 (1956). 139. G. Doyle, K.A. Eriksen and D. Van Engen, Organometallics £, 2201 (1985). 140. J.B. Wilford and H.M. Powell, J . Chem. Soc. (A), 8 (1969). 141. P. Kubacek, R. Hoffmann and Z. Havlas, Organometallics l_, 180 (1982). 210 142. F.E. Simon and J.W. Lauher, Inorg. Chem. 19, 2338 (1980). 143. M.I. Bruce and A.P.P. Ostazewski, J . Chem. S o c , Dalton Trans., 2433 (1973). 144. K.R. Breakell, M.Sc Thesis, U.B.C., (1978) p. 137 145. H.C. Clark and K. von Werner, J . Organomet. Chem. 101_, 347 (1975). 146. S. Nussbaum and A. Storr, Can. J . Chem. 63, 2550 (1985). 147. R.D. Fischer and K. Noack, J . Organomet. Chem. 16, 125 (1969). 148. J.M. B u r l i t c h and A. F e r r a r i , Inorg. Chem. 9, 563 (1970). 149. R.B. King, J . Am. Chem. Soc. 88, 2075 (1966). 150. M.S. Wrighton and D.S. Ginley, J . Am. Chem. S o c 97, 4246 (1975). 151. A.N. Nesmeyanov, K.N. Anisimov, N.E. Kolobova and A.S. Beschastnov, Dokl. Akad. Nauk. SSSR, 159, 377 (1964). 152. B.P. Bir'yukov, Y.T. Struchkov, K.N. Anisimov, N.E. Kolobova and A.S. Beschastnov, J . Chem. S o c , Chem. Commun., 667 (1968). 153. E.H. Brooks and R.J. Cross, Organomet. Chem. Rev. Sect. A, 6̂  227 (1970). 154. K.M. Mackay and B.K. Nicholson, In Comprehensive Organometal 1 i c Chemistry, G. Wilkinson, F.G.A. Stone and E.W. Abel Eds. Vol. 6, Pergamon Press, Oxford, England (1982) p. 1043. 155. E.W. Abel and F.G.A. Stone, Quart, Rev. 24, 498 (1970). 156. J . Chatt, Proc. Chem. S o c , 318 (1962). 157. H.R.H. P a t i l and W.A.G. Graham, Inorg. Chem. 5_, 1401 (1966). 158. D.J. Cardin, S.A. Keppie, B.M. Kingston and M.F. Lappert, J . Chem. S o c , Chem. Commun., 1035 (1967). 159. D.J. Cardin, S.A. Keppie and M.F. Lappert, J . Chem. Soc. (A), 2594 (1970). 160. W. Malisch, H. Schmidbaur and M. Kuhn, Angew. Chem. 84, 538 (1972). 161. W. Malisch, J . Organomet. Chem. 39, C28 (1972). 162. F. Hofler, Top. Curr. Chem. 50, 129 (1974). 163. A. Carrick and F. Glockling, J . Chem. Soc. (A), 913 (1968). 211 164. J.E. O'Connor and E.R. Corey, J . Am. Chem. Soc. 89, 3930 (1967). 165. R.J. Doedens and L.F. Dahl, J . Am. Chem. Soc. 87, 2576 (1965). 166. D.H. Olsen and R.E. Rundle, Inorg. Chem. Z, 1310 (1963). 167. T.S. Cameron and CK. Prout, J . Chem. S o c , Dalton Trans., 1447 (1972). 168. M. Elder and D. H a l l , Inorg. Chem. 8, 1268 (1969). 169. M. Elder and D. H a l l , Inorg. Chem. 8, 1273 (1969). 170. P. Meakin, S. Trofimenko and J.P. Jesson, J . Am. Chem. Soc. 94, 5677 (1972). 171. O.M.A. Salah and M.I. Bruce, Aust. J . Chem. 30, 2292 (1977). 172. K.S. Chong and A. Storr, Can. J . Chem. 59, 1331 (1981). 173. S.J. Rettig, A. Storr, J . T r o t t e r and K. Uhrich, Can. J . Chem. 62, 2783 (1984). 174. B.M. Louie, S.J. Rettig, A. S t o r r and J . Trotter, Can. J . Chem. 63, 2261 (1985). 175. B.M. Louie, S.J. Rett i g , A. S t o r r and J . Tr o t t e r , Can. J . Chem. 63, 3019 (1985). 176. D.A. Cooper, S.J. Rett i g , A. S t o r r and J . Trotter, Can. J . Chem. 64, 566 (1986). 177. A.J. Canty and C.V. Lee, Organometal 1 ics 1, 1063 (1982). 178. P.J. S t e e l , F. Lahouse, D. Lerner and C Martin, Inorg. Chem. 22, 1488 (1983). 179. P. S u l l i v a n , D.J. Salmon, T.J. Meyer and J . Peedin, Inorg. Chem. 1J3, 3369 (1979). 180. E.C Onyiriuka and A. Storr, Can. J . Chem., Submitted. 181. E.C. Onyiriuka, S.J. Rett i g , A. S t o r r and J . Tr o t t e r , Can. J . Chem., Submitted. 182. R.B. King, In Organometal 1 i c Synthesis, Vol 1, Academic Press, New York (1965) p. 174. 183. G. Dolcetti and G.R. Norton, Inorg. Synth. lj>, 35 (1976). 184. R.G. Hayter, J . Organomet. Chem. 13, P1-P3 (1968). 212 185. S.J. Re t t i g , A. S t o r r and J . Tro t t e r , Can. J . Chem. 53, 58 (1975). 186. K.S. Chong, S.J. Rett i g , A. Stor r and J . Tro t t e r , Can. J . Chem. 5_7, 586 (1979). 187. K. Dymock and G.J. Palenik, J. Chem. S o c , Chem. Commun., 884 (1973). 188. S.J. Rett i g , A. S t o r r and J . Tr o t t e r , Can. J . Chem. 52, 2206 (1974). 189. F.A. Cotton and G. Wilkinson, Advanced Inorgnic Chemistry, 4th ed., John Wiley and Sons Inc., New York (1980). 190. R.D. Feltham and J.H. Enemark, In Topics i n Stereochemistry, G. Geoffroy, Ed., Vol 12, John Wiley and Sons, New York (1981) p. 155. 191. W.G. Fateley, H.A. Bent and B.L. Crawford, J . Chem. Phys. 31, 204 (1959). 192. K.J. Hal l e r and J.H. Enemark, Inorg. Chem. 1_7, 3552 (1978). 193. J.H. Enemark and R.D. Feltham, Coord. Chem. Rev. _13, 339 (1974). 194. K.S. Chong, S.J. Rett i g , A. S t o r r and J . Tro t t e r , Can. J . Chem. 5_7, 3107 (1979). 195. D. Berglund and D.W. Meek, Inorg. Chem. U, 1493 (1972). 196. R.B. King, In Organometal1ic Sunthesis, Vol 1, Academic Press, New York (1965) p. 169. 197. K.S. Chong and A. Storr, Can. J . Chem. 57, 167 (1979). 198. R.B. King, Inorg. Chem. 5, 2242 (1966). 199. K.S. Chong, S.J. Rett i g , A. S t o r r and J . Tro t t e r , Can. J . Chem. 59, 1665 (1981). 200. S.J. Rett i g , A. S t o r r and J . Tro t t e r , Can. J . Chem. 59, 2391 (1981). 201. E.O. Fischer and K. B i t t l e r , Z. Naturforsch 16b, 225 (1961). 202. S. Trofimenko, Inorg. Chem. 10, 1372 (1971). 203. S. May, P. Reinsalu and J . Powell, Inorg. Chem. 19, 1582 (1980). 204. I.C. Douek and G. Wilkinson, J . Chem. S o c (A), 2605 (1969). 205. P. Uguagliati, A. P a l a z z i , G. Deganello and U. Belluco, Inorg. Chem. 9, 724 (1970). 213 206. W.R. Roper, 6.E. Taylor, J.M. Waters and L.J. Wright, J . Organomet. Chem. 182, C46 (1979). 207. M.C. Baird, J.T. Mague, J.A. Osborn and G. Wilkinson, J . Chem. Soc. (A), 1347 (1967). 208. J.W. Kang and P.M. M a i t l i s , J . Organomet. Chem. 26, 393 (1971). 209. M. Barber, R.S. Bordoli, R.D. Sedgwick, A.N. T y l e r and E.T. Whalley, Biomed. Mass Spectrom. 8, 337 (1981). 210. M. Barber, R.S. Bordoli, R.D. Sedgwick and A.N. Tyler, Nature 293, 270 (1981). 211. R.B. King, Inorg. Chem. J5, 82 (1966). 212. J.W. Kang, K. Moseley and P.M. M a i t l i s , J . Am. Chem. Soc. 91, 5972 (1969). 213. J.A. McCleverty and G. Wilkinson, J . Chem. S o c , 4096 (1963). 214. R. Hoffmann, B.F. Beier, E.L. Muetterties and A.R. Rossi, Inorg. Chem. 16, 511 (1977). 214 APPENDIX I STEREO DIAGRAMS, BOND LENGTHS AND BOND ANGLES OF SOME OF THE PREPARED DERIVATIVES Me 2GaO(C 5H 3N)CH 2NMe 2 I n t r a - a n n u l a r t o r s i o n a n g l e s (c leg) s t a n d a r d d e v i a t i o n s i n p a r e n t h e s e s A t o m s V a l u e ( d e g ) N ( 2 ) - G a - 0 - C ( 2 ) 4 1 . 7 ( 3 ) Ga - 0 - C ( 2 ) - C ( 1 ) - 4 9 . 5 ( 5 ) C ( 6 ) - C ( 1 ) - C ( 2 ) - 0 - 5 . 0 ( 7 ) C ( 2 ) - C ( 1 ) - C ( 6 ) - N ( 2 ) 6 4 . 9 ( 6 ) Ga - N ( 2 ) - C ( 6 ) - C ( 1 ) - 5 6 . 1 ( 5 ) 0 -Ga - N ( 2 ) - C ( 6 ) 9 . 8 ( 3 ) 215 Me 2GaO(C 5H 3N)CH 2NMe 2, cont'd B o n d l e n g t h s (A) w i t h e s t i m a t e d s t a n d a r d d e v i a t i o n s i n p a r e n t h e s e s Bond u n c o r r . c o r r . Bond u n c o r r . c o r r . Ga - 0 1 . 8 9 2 ( 3 ) 1.897 N ( 2 ) - C ( 9 ) 1 . 4 7 7 ( 6 ) 1 .481 Ga - N ( 2 ) 2 . 1 2 7 ( 4 ) 2 . 1 3 5 N ( 2 ) - C ( 1 0 ) 1 . 4 8 0 ( 6 ) 1 . 4 8 0 Ga - C ( 7 ) 1 . 9 5 0 ( 5 ) 1 . 9 5 6 C ( 1 ) - C ( 2 ) 1 . 4 1 5 ( 6 ) 1 . 4 2 0 Ga - C ( 8 ) 1 . 9 3 9 ( 6 ) 1 . 9 4 7 C ( 1 ) - C ( 6 ) 1 . 4 9 6 ( 7 ) 1 . 5 0 3 0 - C ( 2 ) 1 . 3 2 8 ( 5 ) 1 . 3 3 2 C ( 2 ) - C ( 3 ) 1 . 3 8 9 ( 6 ) 1 . 3 9 3 N ( 1 ) - C ( 1 ) 1 . 3 2 5 ( 7 ) 1 . 3 2 9 C ( 3 ) - C ( 4 ) 1 . 4 2 3 ( 1 4 ) 1 . 4 2 7 N ( 1 ) - C ( 5 ) 1 . 3 2 4 ( 1 3 ) 1 . 3 2 7 C ( 4 ) - C ( 5 ) 1 . 3 5 3 ( 1 5 ) 1 . 3 5 8 N ( 2 ) - C ( 6 ) 1 . 4 9 2 ( 6 ) 1 . 4 9 6 B o n d a n g l e s ( d e g ) w i t h e s t i m a t e d s t a n d a r d d e v i a t i o n s i n p a r e n t h e s e s B o n d s A n g l e ( d e g ) B o n d s A n g l e ( d e g ) 0 - G a - K ( 2 ) 9 5 . 2 4 ( 1 5 ) C ( 6 ) - N ( 2 ) - C O O ) 107 . 8 ( 4 ) 0 - G a - C ( 7 ) 1 1 0 . 3 ( 2 ) C ( 9 ) - N ( 2 ) - C O O ) 107 . 7 ( 4 ) 0 - G a - C ( 8 ) 1 0 8 . 3 ( 2 ) N O ) - C ( 1 ) - C ( 2 ) 124 . 2 ( 5 ) N ( 2 ) - G a - C ( 7 ) 1 0 7 . 3 ( 2 ) N O ) - C O ) - C ( 6 ) 1 17 . 2 ( 6 ) N ( 2 ) - G a - C ( 8 ) 1 0 7 . 4 ( 2 ) C ( 2 ) - C O ) - C ( 6 ) 1 16 . 6 ( 5 ) C ( 7 ) - G a - C ( 8 ) 1 2 4 . 3 ( 3 ) O - C ( 2 ) - C O ) 120 . 3 ( 4 ) Ga - 0 - C ( 2 ) 116. 8 ( 3 ) 0 - C ( 2 ) - C ( 3 ) 122 . 2 ( 5 ) C(1 ) - N ( 1 ) - C ( 5 ) 1 1 6 . 5 ( 7 ) C ( 1 ) - C ( 2 ) - C ( 3 ) 1 17 . 4 ( 5 ) Ga - N ( 2 ) - C ( 6 ) 1 0 7 . 6(3) C ( 2 ) - C ( 3 ) - C ( 4 ) 1 17 . 8 ( 7 ) Ga - N ( 2 ) - C ( 9 ) 1 1 2 . 4 ( 3 ) C ( 3 ) - C ( 4 ) - C ( 5 ) 1 16 . 2 ( 1 2 ) Ga - N ( 2 ) - C ( 1 0 ) 1 1 1 . 1 ( 3 ) N O ) - C ( 5 ) - C ( 4 ) 125 . 7 ( 1 3 ) C ( 6 ) - N ( 2 ) - C ( 9 ) 1 0 9 . 8 ( 4 ) N ( 2 ) - C ( 6 ) - C O ) 1 1 3 . 0 ( 4 ) 216 [Me2GaO(C9H6N)]2 Bond l e n g t h s (A) w i t h e s t i m a t e d s t a n d a r d d e v i a t i o n s i n p a r e n t h e s e s * Bond Length(A) Bond Length(A) Ga - 0 1 . 9 3 7 ( 3 ) C ( 2 ) - C ( 3 ) 1 . 3 5 6 ( 7 ) Ga - N 2 . 2 1 1 ( 3 ) C ( 3 ) - C ( 4 ) 1 . 4 1 1 ( 6 ) Ga - C ( 1 0 ) 1 . 9 4 8 ( 6 ) C ( 4 ) - C ( 5 ) 1 . 4 0 0 ( 6 ) Ga - C ( 1 1 ) 1 . 9 4 5 ( 5 ) C ( 4 ) - C ( 9 ) 1 . 4 1 9 ( 5 ) Ga - 0 ' 2 . 2 9 7 ( 3 ) C ( 5 ) - C ( 6 ) 1 . 3 6 7 ( 7 ) 0 - C < 8 ) 1 . 3 3 6 ( 5 ) C ( 6 ) - C ( 7 ) 1 . 4 0 3 ( 6 ) N - C ( 1 ) 1 . 3 1 9 ( 5 ) C ( 7 ) - C ( 8 ) 1 . 3 6 9 ( 5 ) N - C ( 9 ) 1 . 3 6 2 ( 5 ) C ( 8 ) - C ( 9 ) 1 . 4 1 5 ( 5 ) C ( 1 ) - C ( 2 ) 1 . 3 9 7 ( 7 ) *Primed atoms r e l a t e d by i n v e r s i o n through the c e n t r e a t ( 1 / 2 , 1 / 2 , 1 / 2 ) . 217 [Me 2GaO(C gH 6N)] 2, cont'd Bond a n g l e s ( d e g ) w i t h e s t i m a t e d s t a n d a r d d e v i a t i o n s i n p a r e n t h e s e s B o n d s A n g l e ( d e g ) B o n d s A n g l e ( d e g ) 0 - G a - N 7 8 . 3 7 ( 1 1 ) N - C ( 1 ) - C ( 2 ) 1 2 2 . 4 ( 5 ) 0 - G a - C ( 1 0 ) 1 1 4 . 0 ( 2 ) C O ) - C ( 2 ) - C ( 3 ) 1 1 9 . 6 ( 4 ) 0 - G a - C < 1 1 ) 1 1 3 . 6 ( 2 ) C ( 2 ) - C ( 3 ) - C ( 4 ) 1 2 0 . 7 ( 4 ) 0 - G a - 0 ' 7 1 . 2 9 ( 1 2 ) C ( 3 ) - C ( 4 ) - C ( 5 ) 1 2 5 . 5 ( 4 ) N - G a - C ( 1 0 ) 1 0 0 . 1 ( 2 ) C ( 3 ) - C ( 4 ) - C ( 9 ) 1 1 5 . 9 ( 4 ) N - G a - C ( 11 ) 9 8 . 2 ( 2 ) C ( 5 ) - C ( 4 ) - C ( 9 ) 1 1 8 . 5 ( 4 ) N - G a - 0 ' 1 4 9 . 6 5 ( 1 1 ) C ( 4 ) - C ( 5 ) - C ( 6 ) 1 1 9 . 7 ( 4 ) C( 1 0 ) - G a -c(11) 1 3 1 . 5 ( 3 ) . C ( 5 ) - C ( 6 ) - C ( 7 ) 1 2 1 . 7 ( 4 ) C( 1 0 ) - G a - 0 ' 9 2 . 9 ( 2 ) C ( 6 ) - C ( 7 ) - C ( 8 ) 1 2 0 . 6 ( 4 ) C ( 1 1 ) - G a - 0 " 9 3 . 2 ( 2 ) 0 - C ( 8 ) - C ( 7 ) 1 2 4 . 4 ( 4 ) Ga - 0 - C ( 8 ) 1 1 8 . 9 ( 2 ) 0 - C ( 8 ) - C ( 9 ) 117.2(3) Ga - 0 - G a ' 1 0 8 . 7 1 ( 1 2 ) C ( 7 ) - C ( 8 ) - C ( 9 ) 118 .3(4) C ( 8 ) - 0 - G a ' 1 3 2 . 3 ( 2 ) N - C ( 9 ) - C ( 4 ) 122.6(3) Ga - N - C O ) 1 3 2 . 0 ( 3 ) N - C ( 9 ) - C ( 8 ) 116.3(3) Ga - N - C ( 9 ) 1 0 9 . 1 ( 2 ) C ( 4 ) - C ( 9 ) - C ( 8 ) 121.1(3) C( 1 ) -N - C ( 9 ) 1 1 8 . 9 ( 4 ) B o n d l e n g t h s i n v o l v i n g h y d r o g e n a t o m s (A) w i t h e s t i m a t e d s t a n d a r d d e v i a t i o n s i n p a r e n t h e s e s B o n d L e n g t h ( A ) Bond L e n g t h ( A ) C O ) - H ( 1 ) 0 . 81(5) C ( 1 0 ) - H ( 1 0 a ) 0 . 7 6 ( 1 1 ) C ( 2 ) - H ( 2 ) 0 . 8 9 ( 7 ) C( 1 0 ) - H ( 1 0 b ) 0 . 9 2 ( 7 ) C ( 3 ) - H ( 3 ) 0 . 8 9 ( 5 ) C( 1 0 ) - H ( 1 0 c ) 0 . 6 5 ( 6 ) C ( 5 ) - H ( 5 ) 0 . 8 8 ( 5 ) C O 1 ) -H( 1 l a ) 0 . 9 7 ( 7 ) C ( 6 ) - H ( 6 ) 0 . 91 (6) C O 1 ) - H ( l i b ) 0 . 7 7 ( 8 ) C ( 7 ) - H ( 7 ) 0 . 9 2 ( 5 ) C( 1 1 ) - H ( 1 I c ) 1 . 0 0 ( 1 2 ) B o n d a n g l e s i n v o l v i n g h y d r o g e n a t o m s ( d e g ) w i t h e s t i m a t e d s t a n d a r d d e v i a t i o n s i n p a r e n t h e s e s B o n d s A n g l e ( d e g ) N - C O ) - H O ) 1 1 5 ( 3 ) C ( 2 ) - C O ) - H O ) 1 2 3 ( 3 ) C O ) - C ( 2 ) - H ( 2 ) 1 1 2 ( 5 ) C ( 3 ) - C ( 2 ) - H ( 2 ) 1 2 8 ( 5 ) C ( 2 ) - C ( 3 ) - H ( 3 ) 1 2 2 ( 3 ) C ( 4 ) - C ( 3 ) - H ( 3 ) 1 1 7 ( 3 ) C ( 4 ) - C ( 5 ) - H ( 5 ) 1 2 2 ( 4 ) C ( 6 ) - C ( 5 ) - H ( 5 ) 1 1 7 ( 4 ) C ( 5 ) - C ( 6 ) - H ( 6 ) 1 1 8 ( 4 ) C ( 7 ) - C ( 6 ) - H ( 6 ) 1 2 0 ( 4 ) C ( 6 ) - C ( 7 ) - H ( 7 ) 1 1 6 ( 4 ) C ( 8 ) - C ( 7 ) - H ( 7 ) 1 2 3 ( 4 ) B o n d s A n g l e ( d e g ) Ga - C O O ) - H ( l O a ) 1 1 3 ( 7 ) Ga - C ( I O ) - H O O b ) 1 0 5 ( 4 ) Ga - C O O ) - H ( l O c ) 9 7 ( 4 ) H O 0 a ) - C ( 1 0 ) - H ( 1 0 b ) 1 0 4 ( 8 ) H O O a ) - C ( l O ) - H O O c ) 1 0 9 ( 8 ) H ( l O b ) - C O O ) - H O O c ) 1 2 8 ( 6 ) Ga - C O D - H O l a ) 1 1 7 ( 4 ) Ga - C O D - H O i b ) 1 0 8 ( 7 ) Ga - C O 1 ) - H ( 1 i c ) 1 2 2 ( 6 ) H( 1 1 a ) - C ( 1 1 ) - H O l b ) 1 0 6 ( 7 ) H ( 1 1 a ) - C ( 1 1 ) - H ( 1 1 c ) 8 6 ( 6 ) H ( 1 1 b ) - C ( 1 1 ) - H ( 1 1 c ) 1 1 6 ( 9 ) 218 [MeGapz 3]Mo(C0) 3Rh(PPh 3) 219 [MeGapz 3]Mo(C0) 3Rh(PPh 3) 2, cont'd Bond l e n g t h s (A) w i t h e s t i m a t e d s t a n d a r d d e v i a t i o n s i n p a r e n t h e s e s Bond L e n g t h ( A ) Bond L e n g t h ( A ) ( M e G a p z j ) M o ( C O ) 3 R h ( P P h 3 ) 2 Rh -Mo 2 . 6 0 6 6 ( 5 ) C( 1 1 - C ( 1 2 ) 1 . 3 6 3 ( 7 ) Rh - P ( 1 ) 2 . 2 4 9 1 ( 1 3 ) C( 12) - C ( 1 3 ) 1 . 3 5 7 ( 7 ) Rh - P ( 2 ) 2 . 2 B 3 6 ( 1 2 ) C( 14 - C ( 1 5 ) 1 . 3 8 3 ( 7 ) Rh - C ( 1 ) 2 . 8 4 5 ( 5 ) C ( 14 - C ( 1 9 ) 1 . 3 7 4 ( 7 ) Rh - C ( 2 ) 2 . 3 3 4 ( 5 ) C ( 1 5 - C ( 1 6 ) 1 . 4 1 1 ( 6 ) Rh - C ( 3 ) 2 . 0 7 9 ( 5 ) C( 16 - C ( 1 7 ) 1 . 3 5 5 ( 9 ) Mo - N ( 1 ) 2 . 2 4 9 ( 4 ) C( 17 - C ( 1 8 ) 1 . 3 7 7 ( 9 ) Mo - N ( 3 ) 2 . 2 7 3 ( 4 ) C( 16 - C ( 1 9 ) 1 . 3 9 6 ( 6 ) Mo - N ( 5 ) 2 . 2 4 7 ( 4 ) C ( 2 0 - C ( 2 1 ) 1 . 3 8 3 ( 7 ) Mo - C ( 1 ) 1 . 9 8 2 ( 5 ) C ( 2 0 - C ( 2 5 ) 1 . 3 6 6 ( 7 ) Mo - C ( 2 ) 1 . 9 7 1 ( 6 ) C ( 2 1 - C ( 2 2 ) 1 . 3 9 7 ( 6 ) Mo - C ( 3 ) 2 . 0 3 4 ( 5 ) C ( 2 2 - C ( 2 3 ) 1 . 3 4 6 ( 1 0 ) Ga - N ( 2 ) 1 . 9 1 5 ( 4 ) C ( 2 3 - C ( 2 4 ) 1 . 3 6 4 ( 1 1 ) Ga - N ( 4 ) 1 . 9 2 4 ( 4 ) C ( 2 4 - C ( 2 5 ) 1 . 3 B B ( 9 ) Ga - N ( 6 ) 1 . 9 2 7 ( 4 ) C ( 2 6 - C ( 2 7 ) 1 . 3 7 7 ( 7 ) Ga - C ( 4 ) 1 . 9 3 1 ( 5 ) C ( 2 6 - C ( 3 1 ) 1 . 3 9 3 ( 7 ) P ( l - C ( 1 4 ) 1 . 6 4 0 ( 5 ) C ( 2 7 - C ( 2 8 ) 1 . 3 9 9 ( 8 ) P(1 - C ( 2 0 ) 1 . 6 3 4 ( 5 ) . C ( 2 8 - C ( 2 9 ) 1 . 344 (9) P ( i - C ( 2 6 ) 1 . 6 3 9 ( 5 ) C ( 2 9 - C ( 3 0 ) 1 . 3 6 8 ( 9 ) P ( 2 - C ( 3 2 ) 1 . 6 3 7 ( 5 ) C (30 - C ( 3 1 ) 1 . 3 8 0 ( 8 ) P ( 2 - C O B ) 1 . 6 3 6 ( 5 ) C ( 3 2 - C ( 3 3 ) 1 . 3 6 1 ( 7 ) P ( 2 - C ( 4 4 ) 1 . 8 4 8 ( 5 ) C ( 3 2 - C ( 3 7 ) 1 . 4 0 0 ( 7 ) 0 ( 1 - C ( 1 ) 1 . 1 5 4 ( 6 ) C ( 3 3 - C ( 3 4 ) 1 . 3 8 5 ( 7 ) 0 ( 2 - C ( 2 ) 1 . 1 7 5 ( 6 ) C ( 3 4 - C ( 3 5 ) 1 . 3 5 3 ( 9 ) 0 ( 3 - C ( 3 ) 1 . 1 9 0 ( 5 ) C ( 3 5 - C ( 3 6 ) 1 . 3 7 6 ( 9 ) N(1 - N ( 2 ) 1 . 3 6 7 ( 5 ) C ( 3 6 - C ( 3 7 ) 1 . 3 7 6 ( B ) N(1 - C ( 5 ) 1 . 3 2 7 ( 6 ) C ( 3 8 - C ( 3 9 ) 1 . 3 6 6 ( 7 ) N ( 2 - C ( 7 ) 1 . 3 4 4 ( 6 ) C ( 3 8 - C ( 4 3 ) 1 . 3 9 6 ( 7 ) N ( 3 - N ( 4 ) 1 . 3 6 4 ( 5 ) C ( 3 9 - C ( 4 0 ) 1 . 3 8 5 ( 7 ) N ( 3 - C ( 8 ) 1 . 3 2 8 ( 6 ) C ( 4 0 - C ( 4 1 ) 1 . 3 6 9 ( 8 ) N(4 - C ( 1 0 ) 1 . 3 3 7 ( 6 ) C (4 1 - C ( 4 2 ) 1 . 3 6 9 ( 9 ) N ( 5 - N ( 6 ) 1 . 3 6 9 ( 5 ) C ( 4 2 - C ( 4 3 ) 1 . 3 8 2 ( 8 ) N ( 5 - C ( 1 1 ) 1 . 3 2 6 ( 6 ) C ( 4 4 - C ( 4 5 ) 1 . 3 8 3 ( 7 ) N ( 6 - C ( 1 3 ) 1 . 3 4 4 ( 6 ) C ( 4 4 - C ( 4 9 ) 1 . 3 8 3 ( 7 ) C ( 5 - C ( 6 ) 1 . 3 7 6 ( 7 ) C ( 4 5 - C ( 4 6 ) 1 . 3 8 7 ( 7 ) C<6 - C ( 7 ) 1 . 3 5 5 ( B ) C ( 4 6 - C ( 4 7 ) 1 . 3 6 5 ( 9 ) C ( B - C ( 9 ) 1 . 3 8 3 ( 7 ) C ( 4 7 - C ( 4 B ) 1 . 3 6 4 ( 8 ) C ( 9 - C ( 1 0 ) 1 . 3 4 7 ( 7 ) C ( 4 8 - C ( 4 9 ) 1 . 3 9 0 ( 6 ) 220 [MeGapz 3]Mo(C0) 3Rh(PPh3)2, cont'd Bond angles (deg) with estimated standard deviations in parentheses B o n d s A n g l e ( d e g ) B o n d s A n g l e ( d e g ) ( M e G a p Z j ) M o ( C O ) j R h ( P P h 3 ) 2 Mo - R h - P 1 ) 135 . 8 0 ( 4 ) Ga - N ( 6 ) - N ( 5 ) 1 2 0 . 5(3 Mo - R h - P 2) 12B . 7 0 ( 4 ) Ga - N ( 6 ) - C ( 1 3 ) 1 3 0 . 8(3 Mo - R h -c 1 ) 42 . 3 5 ( 0) N ( 5 ) - N ( 6 ) - C ( 1 3 ) 1 0 B . B(4 Mo - R h -c 2) 46 .61 ( 3) Rh - C ( l ) - M o 6 2 . 37( Mo - R h -c 3) 49 .91 ( 4) Rh - C ( 1 ) - 0 ( 1 ) 1 2 2 . 5(4 P ( 1 ) - R h - P 2) 95 . 2 7 ( 5 ) Mo - C ( 1 ) - 0 ( 1 ) 1 7 3 . 9(5 P( 1 ) - R h -c 1 ) 172 . 1 7 ( 2) Rh - C ( 2 ) - M o 7 4 . 0 ( 2 P(1 ) - R h -c 2) 110 . 9 7 ( 4) Rh - C ( 2 ) - 0 ( 2 ) 1 1 7 . 9(4 P( 1 ) - R h - C 3) 110 . 9 0 ( 4) Mo - C ( 2 ) - 0 ( 2 ) 1 6 7 . 4 (4 P ( 2 ) - R h -c 1 ) 87 . 6 4 ( 1 ) Rh - C ( 3 ) - M o 7 8 . 6 ( 2 P ( 2 ) - R h -c 2) 130 . 2 0 ( 3) Rh - C ( 3 ) - 0 ( 3 ) 1 2 8 . 1(4 P ( 2 ) - R h -c 3) 116 . 6 4 ( 4) Mo - C ( 3 ) - 0 ( 3 ) 1 5 3 . 2 (4 C O ) - R h -c 2) 61 . 9 ( 2 N( 1 ) - C ( 5 ) - C ( 6 ) 1 1 0 . 6 ( 5 C( 1 ) - R h -c 3) 73 . 8 ( 2 C ( 5 ) - C ( 6 ) - C ( 7 ) 1 0 5 . 5 ( 5 C ( 2 ) - R h -c 3) 93 . 1(2 N ( 2 ) - C ( 7 ) - C ( 6 ) 1 0 8 . 8 ( 5 Rh -Mo - N 1 ) 1 11 . 6 4 ( 1 ) N ( 3 ) - C ( 8 ) - C ( 9 ) 1 1 0 . 6 ( 5 Rh -Mo - N 3) 128 . 3 B ( 0) C ( 8 ) - C ( 9 ) - C ( 1 0 ) 1 0 5 . 1(5 Rh -Mo - N 5) 142 , 5 0 ( 0) N ( 4 ) - C ( 1 0 ) - C ( 9 ) 1 0 9 . 3 ( 5 Rh -Mo -c 1 ) 75 . 2 7 ( 4) N ( 5 ) - C ( 1 1 ) - C ( 1 2 ) 1 1 1 . 4 (4 Rh -Mo -c 2) 59 • 40( 4) C( 1 1 ) - C ( 1 2 ) - C ( 1 3 ) 1 0 4 . 4 (4 Rh -Mo -c 3) 51 . 4 5 ( 3) N ( 6 ) - C ( 1 3 ) - C ( 1 2 ) 1 0 9 . 5(4 N( 1 ) -Mo - N 3) 86 . 9 2 ( 4) P ( 1 ) - C ( 1 4 ) - C ( 1 5 ) 1 1 5 . 7 (4 N( 1 ) -Mo - N 5) 85 . 6 9 ( 4) P( 1 ) - C ( 1 4 ) - C ( 1 9 ) 1 2 5 . 3 ( 4 N( 1 ) -Mo -c 1 ) 172 . 9 ( 2 C ( 1 5 ) - C ( 1 4 ) - C ( 1 9 ) 1 I B . 8(5 N( 1 ) -Mo -c 2) 96 . 1 ( 2 C ( 1 4 ) - C ( 1 5 ) - C ( 1 6 ) 1 2 0 . 5 ( 5 N ( 1 ) -Mo -c 3) 68 . 2 ( 2 C ( 1 5 ) - C ( 1 6 ) - C ( 1 7 ) 1 2 0 . 0 ( 6 N ( 3 ) -Mo - N 5) 63 • 74( 4) C ( 1 6 ) - C ( 1 7 ) - C ( 1 B ) 1 1 9 . 7 ( 6 N ( 3 ) -Mo -c 1 ) 69 . 7 ( 2 C ( 1 7 ) - C ( 1 B ) - C ( 1 9 ) 1 2 0 . 7 ( 6 N ( 3 ) -Mo -c 2) 169 . 7 ( 2 C ( 1 4 ) - C ( 1 9 ) - C ( I B ) 1 2 0 . 2 ( 5 N ( 3 ) -Mo -c 3) 63 . 3 ( 2 P( 1 ) - C ( 2 0 ) - C ( 2 1 ) 1 1 7 . 7 (4 N ( 5 ) -Mo -c 1 ) 6 7 . 8 ( 2 P(1 ) - C ( 2 0 ) - C ( 2 5 ) 1 2 2 . 9 (4 N ( 5 ) -Mo -c 2) 66 . 7 ( 2 C ( 2 1 ) - C ( 2 0 ) - C ( 2 5 ) 1 1 9 . 2 ( 5 N ( 5 ) -Mo -c 3) 166 . 0 ( 2 C ( 2 0 ) - C ( 2 1 ) - C ( 2 2 ) 1 1 9 . 8 ( 6 C ( 1 ) -Mo -c 2) 86 . 1 ( 2 C ( 2 1 ) - C ( 2 2 ) - C ( 2 3 ) 1 2 0 . 3(7 C ( 1 ) -Mo -c 3) 97 . 5 ( 2 C ( 2 2 ) - C ( 2 3 ) - C ( 2 4 ) 1 2 0 . 0 ( 6 C ( 2 ) -Mo -c 3) 106 . 5 ( 2 C ( 2 3 ) - C ( 2 4 ) - C ( 2 5 ) 1 2 0 . 5(7 N ( 2 ) - G a - N 4 ) 103 . 0 ( 2 C ( 2 0 ) - C ( 2 5 ) - C ( 2 4 ) 1 2 0 . 0(6 N ( 2 ) - G a - N 6) 100 . 5 ( 2 P ( 1 ) - C ( 2 6 ) - C ( 2 7 ) 1 2 5 . 4(4 N ( 2 ) - G a -c 4 ) 116 . 3 ( 2 P ( 1 ) - C ( 2 6 ) - C ( 3 1 ) 1 1 7 . 3(4 N ( 4 ) - G a - N 6) 9B . 0 ( 2 C ( 2 7 ) - C ( 2 6 ) - C ( 3 1 ) 1 1 7 . 3(5 N(4 ) - G a -c 4 ) 116 . 5 ( 2 C ( 2 6 ) - C ( 2 7 ) - C ( 2 6 ) 121 . 1(6 N ( 6 ) - G a -c 4 ) 119 . 4 ( 2 C ( 2 7 ) - C ( 2 B ) - C ( 2 9 ) 1 2 0 . 8(6 Rh - P ( 1 ) -c 14) 114 . 8 ( 2 C ( 2 B ) - C ( 2 9 ) - C ( 3 0 ) 1 1 9 . 0(6 Rh - P ( 1 ) -c 20) 1 18 . 9 ( 2 C ( 2 9 ) - C ( 3 0 ) - C ( 3 1 ) 121 . 4 ( 6 cont i nued••• 221 [MeGapz 3]Mo(C0) 3Rh(PPh 3) 2, cont'd Rh - P O ) - C ( 2 6 ) 113. 5(2) C ( 2 6 ) - C O D - C O O ) 1 2 0 . 4(5) C O O - P O ) - C ( 2 0 ) 1 0 6 . 5(2) P(2)-C ( 3 2 ) - C(33) 120 . 0(4) C ( 1 4 ) - P O ) - C ( 2 6 ) 1 0 3 . 3(2) P(2)-C ( 3 2 ) - C ( 3 7 ) 121 . 5(4 ) C ( 2 0 ) - P ( l ) - C ( 2 6 ) 9 7 . 5(2) C(33) - C ( 3 2 ) - C ( 3 7 ) 1 1 8 . 5(5) Rh - P(2)- C ( 3 2 ) 112. 6(2) C ( 3 2 ) -C(33) - C ( 3 4 ) 1 2 0 . 3(5) Rh - P(2)- C O B ) 126 . 2(2) C(33) - C ( 3 4 ) - C ( 3 5 ) 1 2 0 . 7 ( 6 ) Rh - P(2)- C ( 4 4 ) 1 0 7 . 4 1 ( 1 5 ) C ( 3 4 ) - C ( 3 5 ) - C ( 3 6 ) 120 . 3(5) C ( 3 2 ) - P ( 2 ) - C O B ) 101 . 1(2) C(35) - C ( 3 6 ) - C ( 3 7 ) 1 2 0 . 0 ( 6 ) C ( 3 2 ) - P ( 2 ) -C(44 ) 104 . 5(2) C ( 3 2 ) - C ( 3 7 ) - C ( 3 6 ) 120 . 2(6) C O B ) - P ( 2 ) -C(44 ) 1 0 2 . 9(2) P(2)- C ( 3 8 ) - C ( 3 9 ) 122 . 5(4 ) Mo - N O ) - N O ) 1 2 5 . 6(3) P(2)- C ( 3 8 ) - C ( 4 3 ) 1 19. 6(4 ) Mo - N( 1 ) -C(5) 128 . 1 ( 3 ) C ( 3 9 ) - C O B ) - C ( 4 3 ) 1 1 7 . B(4 ) N(2)-N O ) - C O ) 1 0 6 . 3(4 ) C O S ) - C ( 3 9 ) - C ( 4 0 ) 120 . 7 ( 5 ) Ga -N(2)-N O ) 1 2 0 . 4(3) C ( 3 9 ) - C ( 4 0 ) - C ( 4 1 ) 1 2 0 . 6(5) Ga -N(2)- C O ) 1 3 0 . 6(4) C ( 4 0 ) - C ( 4 1 ) - C ( 4 2 ) 1 19. 6(5) N O ) -N(2)- C O ) 1 0 8 . 9(4) C(41 ) - C ( 4 2 ) - C ( 4 3 ) 1 2 0 . 4 ( 6 ) Mo " N(3)-N ( 4 ) 1 2 6 . 5(3) C O B ) - C ( 4 3 ) - C ( 4 2 ) 120 . 7(5) Mo -N(3)-C O ) 1 2 7 . 5(3) P(2)-C ( 4 4 ) - C ( 4 5 ) 1 1 8 . 2(4) N ( 4 ) - N(3)-C O ) 1 0 6 . 0 ( 4 ) P(2)-C ( 4 4 ) - C ( 4 9 ) 1 2 2 . 2(4) Ga -N ( 4 ) - N O ) 1 1 8 . 9(3) C ( 4 5 ) - C ( 4 4 ) - C ( 4 9 ) 1 19. 5(5) Ga -N ( 4 > - C O O ) 1 3 2 . 0(3) C ( 4 4 ) - C ( 4 5 ) - C ( 4 6 ) 1 2 0 . 0(5) N(3)-N ( 4 ) - C O O ) 1 0 9 . 1 (4) C ( 4 5 ) - C ( 4 6 ) - C ( 4 7 ) 1 2 0 . 0(5) Mo -N(5)-N ( 6 ) 1 2 5 . 3(3) C ( 4 6 ) - C ( 4 7 ) - C ( 4 8 ) 120 . 1(5) Mo -N(5)- C O D 1 2 8 . 7(3) C ( 4 7 ) - C ( 4 8 ) - C ( 4 9 ) 1 2 0 . 2(6) N ( 6 ) - N ( 5 ) - C O D 1 0 5 . 9(4) C ( 4 4 ) - C ( 4 9 ) - C U B ) 120 . 2(5) I n t r a - a n n u l a r t o r s i o n a n g l e s ( d e g ) s t a n d a r d d e v i a t i o n s i n p a r e n t h e s e s A t o m s V a l u e ( d e g ) ( M e G a p z , ) M o ( C O ) , R h ( P P h 3 ) 2 N O ) -Mo - N O ) - N ( 2 ) - 3 8 . 5 ( 4 ) Mo - N O ) - N O ) -Ga - 3 . 9 ( 5 ) N ( 4 ) - G a - N O ) - N O ) 5 2 . 3 ( 4 ) N ( 2 ) - G a - N ( 4 ) - N O ) - 4 7 . 4 ( 4 ) MO - N O ) - N ( 4 ) - G a - 3 . 8 ( 5 ) N O ) -Mo - N O ) - N ( 4 ) 4 3 . 3 ( 4 ) N ( 5 ) -Mo - N O ) - N O ) 4 5 . 4 ( 4 ) Mo - N O ) - N O ) - G a - 3 . 9 ( 5 ) N ( 6 ) - G a - N O ) - N O ) - 4 8 . 6 ( 4 ) N ( 2 ) - G a - N ( 6 ) - N ( 5 ) 5 2 . 1 ( 4 ) MO - N ( 5 ) - N ( 6 ) - G a - 2 . 2 ( 5 ) N O ) -Mo - N ( 5 ) - N ( 6 ) -41 . 7 ( 4 ) N ( 5 ) -MO - N O ) - N ( 4 ) - 4 2 . 7 ( 4 ) MO - N O ) - N ( 4 ) - G a - 3 . 8 ( 5 ) N ( 6 ) - G a - N ( 4 ) - N O ) 5 5 . 4 ( 4 ) N ( 4 ) - G a - N ( 6 ) - N ( 5 ) - 5 2 . 8 ( 4 ) Mo - N ( 5 ) - N ( 6 ) - G a - 2 . 2 ( 5 ) N O ) -Mo - N ( 5 ) - N ( 6 ) 4 5 . 7 ( 4 ) 222 [MeGapz 3]Mo(C0) 3Cii(PPh 3) 223 [MeGapz,]Mo(CO),Cu(PPM 224 [MeGapz3]Mo(C0)3Cu(PPh3), cont'd Bond l e n g t h s (A) w i t h e s t i m a t e d s t a n d a r d d e v i a t i o n s i n p a r e n t h e s e s Bond L e n g t h ( A ) Bond L e n g t h ( A ) ( M e G a p z j ) M o ( C O ) 3 C u ( P P h j ) Mo - C u 2 . 5 0 4 1 ( B ) N 3' ) - N ( 4 ' ) 1 . 3 5 8 (6) Mo - N ( 1 ) 2 . 2 5 4 ( 5 ) N 3' ) - C ( 8 ' ) 1 . 3 2 3 (7) Mo - N O ) 2 . 2 5 7 ( 4 ) N 4' ) - C ( 1 0 ' ) 1 . 3 4 8 (7) Mo - N ( 5 ) 2 . 2 4 6 ( 4 ) N 5' ) - N ( 6 ' ) 1 . 3 6 6 (6) Mo - C ( 1 ) 1 . 9 6 6 ( 7 ) N 5' ) - C ( 1 1 ' ) 1 . 3 3 6 (7) Mo - C ( 2 ) 1 . 9 5 8 ( 7 ) N 6 ' ) - C ( 1 3 ' ) 1 . 3 3 9 (7) Mo - C ( 3 ) 1 . 9 7 1 ( 7 ) C 5 ) - C ( 6 ) 1 . 3 7 5 (9) Mo' - C u ' 2 . 5 2 1 6 ( 8 ) C 6 ) - C ( 7 ) 1 . 3 6 6 (9) Mo' -N(1') 2 . 2 5 3 ( 5 ) C 8 ) - C ( 9 ) 1 . 3 6 7 B) Mo' - N ( 3 ' ) 2 . 2 7 3 ( 5 ) C 9 ) - C(10) 1 .361 8) Mo' - N ( 5 ' ) 2 . 2 5 7 ( 5 ) C 11 ) - C ( 1 2 ) 1 .385 B) Mo ' - C(1' ) 1 . 9 5 8 ( 7 ) C 12) - C ( 1 3 ) 1 .353 8) Mo' - C ( 2 ' ) 1 . 9 7 0 ( 7 ) C 14) - C ( 1 5 ) 1 .383 7) Mo ' - C ( 3 ' ) 1 . 9 8 0 ( 7 ) C 14 ) -C(19) 1.372 7) Ga - N O ) 1 . 9 2 2 ( 5 ) C 15) -C(16) 1 .379 8) Ga - N ( 4 ) 1 . 9 2 9 ( 5 ) C 16) - C ( 1 7 ) 1 .378 9) Ga -N(6) 1 . 9 1 7 ( 5 ) C 17) - C ( 1 8 ) 1.361 8) Ga - C ( 4 ) 1 . 9 4 3 ( 6 ) c 18) -C(19) 1 . 3 7 6 B) G a ' - N ( 2 ' ) 1 . 9 2 4 ( 5 ) c 20) - C ( 2 1 ) 1 . 3 7 8 7) G a ' - N ( 4 ' ) 1 . 9 2 6 ( 5 ) c 20) - C ( 2 5 ) 1 .378 7) G a ' -N(6') 1 . 9 2 B ( 5 ) c 21 ) - C ( 2 2 ) 1 . 3 7 5 B) Ga" - C ( 4 ' ) 1 . 9 3 5 ( 6 ) c 22) - C ( 2 3 ) 1 . 3 7 4 9) Cu - P 2 . 1 9 3 ( 2 ) c 23) - C ( 2 4 ) 1 . 3 B 3 9) Cu - C ( 1 ) 2 . 2 5 9 ( 6 ) c 24) - C ( 2 5 ) 1 . 3 8 3 9) Cu - C ( 2 ) 2 . 2 7 4 ( 7 ) c 26) - C ( 2 7 ) 1 . 3 8 3 8) Cu - C ( 3 ) 2 . 4 1 9 ( 6 ) c 26) - C O D 1 . 3 6 5 8) C u ' - P ' 2 .199(2) c 27) - C ( 2 8 ) 1 .371 9) C u ' - C ( 1 ' ) 2 . 4 1 0 ( 6 ) c 28) - C ( 2 9 ) 1 .371 10) C u ' - C ( 2 ' ) 2 . 3 2 2 ( 6 ) c 29) - C O O ) 1 .341 10) C u ' - C ( 3 ' ) 2 . 2 3 4 ( 6 ) c 30) - C O D 1 .378 9) P - C ( 1 4 ) 1 . 8 1 9 ( 6 ) c< 5' ) - C ( 6 ' ) 1 .361 8) P - C ( 2 0 ) 1 . 8 2 6 ( 6 ) c< 6 ' ) - C ( 7 ' ) 1 . 3 7 5 8) P - C ( 2 6 ) 1 . 6 3 3 ( 6 ) ci 8 ' ) - C O ' ) 1 . 3 9 5 8) P' - C ( 1 4 ' ) 1.811(6) c( 9 ' ) - C O O ' ) 1 .347 8) P ' - C ( 2 0 ' ) 1 . 8 1 2 ( 6 ) c 11 ' ) - C ( 1 2 ' ) 1 . 3 6 6 9) P' - C ( 2 6 ' ) 1 . 8 1 7 ( 6 ) c< 12 ' ) - C ( 1 3 ' ) 1 . 3 4 6 9) 0(1 ) -C(1 ) 1 . 1 6 0 ( 7 ) c< 14' ) - C ( 1 5 ' ) 1 .38B B) 0 ( 2 ) - C ( 2 ) 1 . 1 7 4 ( 7 ) c< 14' ) - C ( l 9 ' ) 1 . 374 7) 0 ( 3 ) - C ( 3 ) 1 . 1 5 9 ( 6 ) C( 15* ) - C ( 1 6 ' ) 1 .381 8) 0( 1 ' )-c(r) 1.169(6) c< 16' ) - C ( 1 7 ' ) 1 . 3 7 5 B) 0 ( 2 ' ) - C ( 2 ' ) 1 . 1 6 4 ( 7 ) c< 17 ' ) - C O B ' ) 1 . 3 5 9 6) 0 ( 3 ' ) - C ( 3 ' ) 1 . 1 5 5 ( 6 ) c< 16' ) - C ( 1 9 ' ) 1 . 3 8 6 6) N(1 ) - N O ) 1 . 3 7 3 ( 6 ) c 2 0 ' ) - C ( 2 T ) 1 . 3 7 4 B) N(1 ) - C ( 5 ) 1 . 3 3 2 ( 7 ) c 2 0 ' ) - C ( 2 5 ' ) 1 . 3 6 4 8) N ( 2 ) - C ( 7 ) 1 . 3 4 7 ( 7 ) c 21 ' ) - C ( 2 2 ' ) 1 . 3 9 2 8) N ( 3 ) - N ( 4 ) 1 . 3 6 7 ( 6 ) c 2 2 ' ) - C ( 2 3 ' ) 1 . 3 5 4 9) N ( 3 ) - C ( B ) 1 . 3 4 5 ( 7 ) c 2 3 ' ) - C ( 2 4 ' ) 1 .361 10) N(4 ) - C ( 1 0 ) 1 . 3 4 7 ( 7 ) c 24 ' ) - C ( 2 5 ' ) 1 .391 9) c o n t i n u e d /. 225 N ( 5 ) - N ( 6 ) N ( 5 ) - C ( 1 1 ) N ( 6 ) - C ( 1 3 ) N ( 1 ' ) - N ( 2 ' ) N ( 1 ' ) - C ( 5 ' ) N ( 2 ' ) - C ( 7 ' ) [MeGapz 3]Mo(C0) 3Cu(PPh 3), cont'd 1 . 3 7 1 ( 6 ) 1 . 334 (7 ) 1 . 3 4 3 ( 7 ) 1 . 3 6 4 ( 6 ) 1 . 3 2 3 ( 7 ) 1 . 3 1 6 ( 7 ) C ( 2 6 ' ) - C ( 2 7 ' ) 1 . 3 6 5 ( 7 ) C ( 2 6 ' ) - C ( 3 D 1 . 3 8 5 ( B ) C ( 2 7 ' ) - C ( 2 B ' ) 1 . 3 8 4 ( 8 ) C ( 2 B * ) - C ( 2 9 " ) 1 . 3 5 8 ( 8 ) C ( 2 9 ' ) - C ( 3 0 ' ) 1 . 3 6 5 ( 9 ) C ( 3 0 ' ) - C ( 3 1 ' ) 1 . 364 (6 ) Bond a n g l e s ( d e g ) w i t h e s t i m a t e d s t a n d a r d d e v i a t i o n s i n p a r e n t h e s e s B o n d s A n g l e ( d e g ) B o n d s A n g l e ( d e g ) (MeGapz j ) M o ( C O ) 3 C u ( P P h j ) Cu -Mo - N O ) 1 3 0 . 5 2 0 2) N ( 5 ) - N ( 6 ) - C ( 1 3 ) 10B. 5 ( 5 ) Cu -Mo - N ( 3 ) 131 . 46( 2) Mo' - N O ' ) - N ( 2 ' ) 126 . 4 ( 3 ) Cu -Mo - N ( 5 ) 1 2 3 . 5 5 0 2) Mo' - N O ' ) - C ( 5 ' ) 128 . 3 ( 4 ) Cu -Mo - C O ) 5 9 . 3 ( 2 N ( 2 ' ) - N ( 1 ' ) - C ( 5 ' ) 1 0 5 . 3 ( 5 ) Cu -Mo - C ( 2 ) 5 9 . 8 ( 2 G a ' - N ( 2 ' ) - N ( 1 ' ) 1 2 0 . 0 ( 4 ) Cu -Mo - C ( 3 ) 6 4 . 1 (2 G a ' - N ( 2 ' ) - C ( 7 ' ) 1 3 0 . 7 ( 4 ) N( 1 ) -Mo - N ( 3 ) 8 4 . 1(2 N O ' ) - N ( 2 ' ) - C ( 7 ' ) 1 0 9 . 3 ( 5 ) N( 1 ) -Mo - N ( 5 ) 8 6 . 4 ( 2 Mo' - N ( 3 ' ) - N ( 4 ' ) 1 2 6 . 0 ( 4 ) N O ) -Mo - C O ) 1 7 0 . 0 ( 2 Mo' - N ( 3 ' ) - C ( 8 ' ) 1 2 7 . 4 ( 4 ) N O ) -Mo - C ( 2 ) 8 6 . 6 ( 2 N ( 4 ' ) - N ( 3 ' ) - C ( 8 ' ) 1 0 6 . 5 ( 5 ) N O ) -Mo - C ( 3 ) 8 6 . 7 ( 2 ] G a ' - N ( 4 ' ) - N ( 3 * ) 1 2 0 . 1 (4) N ( 3 ) -Mo - N ( 5 ) 6 5 . 3 ( 2 G a ' - N ( 4 * ) - C O 0 ' ) 131 . 3 ( 5 ) N ( 3 ) -Mo - C O ) 8 7 . 0 ( 2 N ( 3 ' ) - N ( 4 ' ) - C O 0 ' ) 1 0 8 . 3 ( 5 ) N ( 3 ) -Mo - C ( 2 ) 1 6 8 . 5 ( 2 Mo' - N ( 5 ' ) - N ( 6 * ) 1 2 7 . 0 ( 4 ) N ( 3 ) -Mo - C ( 3 ) 9 0 . 2 ( 2 Mo* - N ( 5 * ) - C ( 1 1 *) 1 2 7 . 6 ( 4 ) N ( 5 ) -Mo - C O ) 8 6 . 4 ( 2 N ( 6 * ) - N ( 5 * ) - C ( 1 1 * ) 1 0 5 . 4 ( 5 ) N ( 5 ) -Mo - C ( 2 ) 8 5 . 4 ( 2 G a ' - N ( 6 ' ) - N ( 5 ' ) 1 1 9 . 2 ( 4 ) N ( 5 ) -Mo - C ( 3 ) 1 7 2 . 1 ( 2 G a ' - N ( 6 ' ) - C ( 1 3 ' ) 132 . 0 ( 5 ) C O ) -Mo - C ( 2 ) 9 9 . 4 ( 3 N ( 5 ' ) - N ( 6 ' ) - C ( 1 3 ' ) 1 0 8 . 7 ( 5 ) C O ) -Mo - C ( 3 ) 9 7 . 6 ( 3 Mo - C ( D - C u 7 2 . 3 ( 2 ) C ( 2 ) -Mo - C ( 3 ) 9 8 . 3 ( 3 Mo - C ( I ) - O O ) 1 7 0 . 6 ( 5 ) C u ' - M o ' - N O " ) 1 2 5 . 14( 1 ) Cu - C O ) - O ( I ) 1 1 6 . 9 ( 4 ) C u ' - M o ' - N ( 3 ' ) 1 2 6 . 3 6 ( 1 2) Mo - C ( 2 ) - C u 7 2 . 1 (2) C u ' - M o ' - N ( 5 * ) 1 3 2 . 6 6 ( 1 3) Mo - C ( 2 ) - 0 ( 2 ) 1 7 0 . 6 ( 6 ) C u ' -Mo* - C O ' ) 6 3 . 7 ( 2 Cu - C ( 2 ) - 0 ( 2 ) 1 1 7 . 2 ( 5 ) Cu* - M o ' - C ( 2 * ) 6 0 . 6 ( 2 Mo - C ( 3 ) - C u 6 8 . 7 ( 2 ) C u ' - M o ' - C ( 3 ' ) 5 6 . 0 ( 2 Mo - C ( 3 ) - 0 ( 3 ) 1 7 2 . 6 ( 6 ) N O ' ) - M o ' - N ( 3 ' ) 8 4 . 5 ( 2 Cu - C ( 3 ) - 0 ( 3 ) 1 1 8 . 6 ( 5 ) N O ' ) - M o ' - N ( 5 ' ) 6 5 . 2 ( 2 N O ) - C ( 5 ) - C ( 6 ) 1 1 1 . 8 ( 6 ) N O ' ) - M 0 ' - C O * ) 171 . 1 (2 C ( 5 ) - C ( 6 ) - C ( 7 ) 1 0 4 . 4 ( 6 ) N O ' ) - M 0 ' - C ( 2 * ) 6 9 . 1 (2 N ( 2 ) - C ( 7 ) - C ( 6 ) 1 0 9 . 4 ( 6 ) N O ' ) - M o ' - C ( 3 ' ) 8 7 . 2 ( 2 N ( 3 ) - C ( 8 ) - C ( 9 ) 1 1 0 . 9 ( 6 ) N ( 3 ' ) - M o ' - N ( 5 ' ) 6 5 . 0 ( 2 C ( 6 ) - C ( 9 ) - C O 0 ) 104 . 9 ( 5 ) N ( 3 ' ) - M 0 ' - C O ' ) 9 0 . 4 ( 2 N ( 4 ) - C ( 1 0 ) - C ( 9 ) 1 0 9 . 8 ( 5 ) N ( 3 ' ) - M o ' - C ( 2 ' ) 1 7 0 . 8 ( 2 N ( 5 ) - C ( 1 1 ) - C ( 1 2 ) 1 1 1 . 7 ( 6 ) N ( 3 ' ) - M o ' - C ( 3 * ) 8 6 . 8 ( 2 C O 1 ) - C 0 2 ) - C 0 3 ) 1 0 3 . 7 ( 5 ) N ( 5 ' ) - M o ' - C O ' ) 6 7 . 1 (2 N ( 6 ) - C ( 1 3 ) - C ( 1 2 ) 1 1 0 . 5 ( 5 ) N ( 5 ' ) - M o ' - C ( 2 ' ) 8 8 . 0 ( 2 P - C ( 1 4 ) - C 0 5 ) 1 1 9 . 2 ( 5 ) N ( 5 ' ) - M o ' - C ( 3 ' ) 1 6 9 . 3 ( 2 P - C ( 1 4 ) - C ( 1 9 ) 121 . 9 ( 4 ) C O ' ) - M o ' - C ( 2 ' ) 9 5 . 1 (2 C ( 1 5 ) - C ( 1 4 ) - C 0 9 ) 1 1 8 . 9 ( 6 ) C O ' ) - M o ' - C ( 3 ' ) 9 9 . 8 ( 2 C( 1 4 ) - C ( 1 5 ) - C ( 1 6 ) 1 1 9 . 1 (6) C ( 2 ' ) - M 0 ' - C ( 3 * ) 9 9 . 4 ( 2 C ( 1 5 ) - C ( 1 6 ) - C ( 17) 121 . 1 (6) N ( 2 ) - G a - N ( 4 ) 1 0 0 . 2 ( 2 C 0 6 ) - C 0 7 ) - C ( 1 8 ) 1 1 9 . 7 ( 6 ) c o n t i n u e d / . 226 [MeGapz 3]Mo(C0) 3Cu(PPh 3), cont'd N ( 2 ) - G a - N ( 6 ) 101 . 7 ( 2 ) C ( 1 7 ) - C(18 ) - C(19) 1 1 9 . 4 6 N ( 2 ) - G a - C ( 4 ) 1 1 6 . 7 ( 3 ) C ( 1 4 ) - C ( 1 9 ) - C ( 1 8 ) 121 . 8 6 N(4 ) -Ga - N ( 6 ) 1 0 0 . 3 ( 2 ) P - C ( 2 0 ) - C ( 2 1 ) 1 2 3 . 6 4 N(4 )-Ga - C ( 4 ) 1 1 5 . 7 ( 3 ) P - C ( 2 0 ) - C ( 2 5 ) 116. 7 5 N ( 6 ) - G a -C(4) 119. 1 ( 3 ) C(21 ) - C ( 2 0 ) - C ( 2 5 ) 119. 6 6 N(2' ) -Ga* -N(4') 1 0 0 . 0 ( 2 ) C ( 2 0 ) - C ( 2 1 ) - C ( 2 2 ) 1 2 0 . 6 6 N ( 2 ' ) - G a ' - N ( 6 ' ) 101 . 3 ( 2 ) C ( 2 1 ) - C ( 2 2 ) - C ( 2 3 ) 1 1 9 . B 6 N(2' ) -Ga * - C ( 4 ' ) 1 1 7 . 1 ( 3 ) C ( 2 2 ) - C ( 2 3 ) - C ( 2 4 ) 1 2 0 . 0 6 N ( 4 ' ) - G a ' - N ( 6 ' ) 9 9 . 7 ( 2 ) C ( 2 3 ) - C ( 2 4 ) - C ( 2 5 ) 1 2 0 . 0 6 N(4') -Ga* - C ( 4 ' ) 116. 4 ( 3 ) C ( 2 0 ) - C ( 2 5 ) - C ( 2 4 ) 119. 9 6 N ( 6 ' ) - G a ' - C ( 4 ' ) 1 1 9 . 1(3) P - C ( 2 6 ) - C ( 2 7 ) 1 16. 5 5 Mo - C u - P 177 . 0 2 ( 6 ) P - C ( 2 6 ) - C ( 3 D 1 2 3 . 3 5 Mo - C u - C O ) 4 8 . 4 ( 2 ) C ( 2 7 ) - C ( 2 6 ) - C ( 3 D 118. 2 6 Mo - C u - C ( 2 ) 4 6 . 1(2) C ( 2 6 ) - C ( 2 7 ) - C ( 2 6 ) 1 2 0 . 6 6 Mo - C u - C ( 3 ) 4 7 . 2 ( 2 ) C ( 2 7 ) - C ( 2 6 ) - C ( 2 9 ) 1 2 0 . 7 7 P - C u - C ( 1 ) 1 3 2 . 7 ( 2 ) C ( 2 8 ) - C ( 2 9 ) - C ( 3 0 ) 1 1 8 . 2 7 P - C u - C ( 2 ) 1 2 9 . 0 ( 2 ) C ( 2 9 ) - C ( 3 0 ) - C ( 3 1 ) 1 2 2 . 3 7 P - C u - C ( 3 ) 1 3 4 . 7 ( 2 ) C ( 2 6 ) - C ( 3 1 ) - C ( 3 0 ) 1 1 9 . 9 6 C(1 ) - C u - C ( 2 ) 8 2 . 6 ( 2 ) M o ' - C O ' ) -Cu* 6 9 . 6 2 C( 1 H C u - C ( 3 ) 7 8 . 6 ( 2 ) M o ' - C O ' ) - 0 O ' ) 171 . 5 5 C ( 2 ) - C u - C ( 3 ) 7 B . 5 ( 2 ) C u ' - C O * ) - 0 O ' ) 118. 4 4 Mo' - C u * - P ' 1 7 5 . 1 7 ( 6 ) M o ' - C ( 2 ' ) - C u * 71 . 4 2 Mo' - C u ' - C O ' ) 4 6 . 72(15) Mo' - C ( 2 ' ) - 0 ( 2 * ) 1 7 0 . 7 5 Mo ' - C u ' - C ( 2 ' ) 4 7 . 8 ( 2 ) Cu* - C ( 2 ' ) - 0 ( 2 ' ) 1 1 7 . 6 5 Mo' - C u ' - C ( 3 ' ) 4 8 . 8 ( 2 ) Mo* - C ( 3 * ) - C u * 7 3 . 2 2 P' - C u ' - C O ' ) 1 2 8 . 8 ( 2 ) M o ' - C ( 3 * ) - 0 ( 3 * ) 1 6 9 . 6 5 P' - C u ' - C ( 2 * ) 1 3 2 . 0 ( 2 ) Cu* - C ( 3 ' ) - 0 ( 3 * ) 1 1 7 . 1 4 P' - C u ' - C ( 3 ' ) 1 3 5 . 2 ( 2 ) N( 1 * ) - C ( 5 ' ) - C ( 6 * ) 1 1 2 . 3 5 C( 1 ' ) - C u ' - C ( 2 ' ) 7 5 . 5 ( 2 ) C ( 5 * ) - C ( 6 ' ) - C ( 7 * ) 1 0 3 . 5 5 C( 1 ' ) - C u ' - C ( 3 * ) 8 0 . B ( 2 ) N ( 2 ' ) - C ( 7 * ) - C ( 6 ' ) 1 0 9 . 7 6 C ( 2 ' ) - C u ' - C ( 3 ' ) 8 2 . 8 ( 2 ) N ( 3 ' ) - C ( B ' ) - C ( 9 ' ) 1 1 1 . 0 6 Cu - P - C 0 4 ) 1 1 3 . 0 ( 2 ) C ( 6 ' ) - C ( 9 ' ) - C O 0 ' ) 1 0 3 . 6 5 Cu - P - C ( 2 0 ) 1 1 4 . 9 ( 2 ) N ( 4 ' ) - C O 0 ' ) - C ( 9 ' ) 1 1 0 . 2 6 Cu - P - C ( 2 6 ) 1 1 3 . 3 ( 2 ) N ( 5 ' ) - C ( 1 1 ' ) - C ( 1 2 ' ) 1 1 1 . 4 6 C ( 1 4 ) - P - C ( 2 0 ) 1 0 2 . 7 ( 2 ) C O T ) - C ( 12 ' ) - C ( l 3 ' ) 104 . 7 6 C (14 ) - P - C ( 2 6 ) 1 0 7 . 3 ( 3 ) N ( 6 ' ) - C ( l 3 ' ) - C ( 1 2 * ) 1 0 9 . 8 6 C ( 2 0 ) - P - C ( 2 6 ) 1 0 4 . 7 ( 3 ) P* - C ( 1 4 * ) - C ( 1 5 ' ) 1 1 9 . 4 5 C u ' - P ' - C O 4 ' ) 119. 1 ( 2 ) P ' - C ( 1 4 ' ) - C ( 1 9 ' ) 121 . 7 5 Cu* - P ' - C ( 2 0 ' ) 1 1 1 . 3 ( 2 ) C(15' ) - C d 4 ' ) - C ( l 9 ' ) 1 1 B . 9 5 C u ' - P * - C ( 2 6 ' ) 1 1 1 . 1 ( 2 ) C ( 1 4 ' ) - C ( 1 5 ' ) - C ( l 6 ' ) 1 2 0 . 3 6 C ( 1 4 ' ) - P * - C ( 2 0 ' ) 1 0 4 . 3 ( 3 ) C ( 1 5 ' ) - C ( 1 6 ' ) - C 0 7 * ) 1 1 9 . 7 6 C ( 1 4 * ) - P ' - C ( 2 6 ' ) 1 0 4 . 6 ( 3 ) C ( 1 6 * ) - C ( 1 7 * ) - C ( l 6 * ) 1 2 0 . 7 6 C ( 2 0 ' ) - P ' - C ( 2 6 * ) 1 0 5 . 5 ( 3 ) C ( 1 7 * ) - C O B * ) - C ( l 9 ' ) 1 1 9 . 7 6 Mo - N O ) - N ( 2 ) 1 2 5 . 9 ( 3 ) C ( 1 4 * ) - C(19' ) - C(l6') 1 2 0 . 7 6 Mo - N O ) - C ( 5 ) 1 2 8 . 3 ( 4 ) P ' - C ( 2 0 * ) - C ( 2 T ) 1 1 9 . 0 5 N ( 2 ) - N O ) - C ( 5 ) 1 0 5 . 7 ( 5 ) P' - C ( 2 0 * ) - C ( 2 5 * ) 1 2 2 . 1 5 Ga - N ( 2 ) - N O ) 119. 7 ( 4 ) C ( 2 1 * ) - C ( 2 0 ' ) - C ( 2 5 * ) 1 I B . 9 6 Ga - N ( 2 ) - C ( 7 ) 131 . 5 ( 5 ) C ( 2 0 ' ) - C ( 2 l ' ) - C ( 2 2 * ) 121 . 3 6 N(1 ) - N ( 2 ) - C ( 7 ) 1 0 8 . 7 ( 5 ) C ( 2 1 ' ) - C ( 2 2 ' ) - C ( 2 3 * ) 1 1 8 . 4 6 Mo - N ( 3 ) - N ( 4 ) 1 2 5 . 9 ( 3 ) C ( 2 2 * ) - C ( 2 3 ' ) - C ( 2 4 * ) 1 2 2 . 0 7 Mo - N ( 3 ) - C ( B ) 1 2 7 . 8 ( 4 ) C ( 2 3 * ) - C ( 2 4 * ) - C ( 2 5 ' ) 119. 5 7 N ( 4 ) - N ( 3 ) - C ( 6 ) 1 0 6 . 2 ( 4 ) C ( 2 0 * ) - C ( 2 5 * ) - C ( 2 4 ' ) 119. 8 6 Ga - N ( 4 ) - N ( 3 ) 119. 5 ( 3 ) P ' - C ( 2 6 * ) - C ( 2 7 * ) 1 2 3 . 8 5 Ga - N ( 4 ) - C O O ) 1 3 2 . 2 ( 4 ) P* - C ( 2 6 ' ) - C ( 3 l ' ) 1 1 7 . 8 5 N ( 3 ) - N ( 4 ) - C O O ) 1 0 6 . 2 ( 5 ) C ( 2 7 ' ) - C ( 2 6 ' ) - C ( 3 l ' ) 1 I B . 4 5 Mo - N ( 5 ) - N ( 6 ) 1 2 7 . 1 ( 3 ) C ( 2 6 ' ) - C ( 2 7 ' ) - C ( 2 8 ' ) 1 2 0 . 4 5 Mo - N ( 5 ) - c o n 1 2 7 . 2 ( 4 ) C ( 2 7 ' ) - C ( 2 8 * ) - C ( 2 9 ' ) 1 2 0 . 5 6 N ( 6 ) - N ( 5 ) - C O D 1 0 5 . 6 ( 4 ) C ( 2 B ' ) - C ( 2 9 ' ) - C ( 3 0 ' ) 1 2 0 . 0 6 Ga - N ( 6 ) - N ( 5 ) 1 1 8 . 6 ( 3 ) C ( 2 9 " ) - C ( 3 0 * ) - C ( 3 1 * ) 1 2 0 . 3 6 Ga - N ( 6 ) - C 0 3 ) 1 3 2 . 9(4) C ( 2 6 " ) - C ( 3 l ' ) - C ( 3 0 ' ) 1 2 0 . 3 6 227 [MeGapz 3]Mo(CO) 3Cu(PPh 3), cont'd I n t r a - a n n u l a r t o r s i o n a n g l e s ( d e g ) s t a n d a r d d e v i a t i o n s i n p a r e n t h e s e s A toms V a l u e ( d e g ) ( M e G a p z j ) M o ( C O ) 3 C u ( P P h , ) N ( 3 ) -Mo - N( 1 ) -N ( 2 ) 4 2 . 9 ( 4 ) Mo -N ( 1 )-N ( 2 > - Ga 2. 6 ( 5 ) N(4 ) - G a -N ( 2 ) - N(1 ) - 5 3 . 3 ( 4 ) N ( 2 ) - G a -N ( 4 ) - N ( 3 ) 4 7 . 5 ( 4 ) Mo - N ( 3 ) - N(4 ) - Ga 7 . 9 ( 6 ) N(1 ) -Mo -N ( 3 ) - N ( 4 ) - 4 9 . 1 ( 4 ) N ( 5 ) -Mo -N(1 ) -N ( 2 ) - 4 2 . 7 ( 4 ) Mo - N ( 1 ) - N ( 2 ) ~ Ga 2. 6 ( 5 ) N ( 6 ) - G a -N ( 2 ) - N( 1 ) 4 9 . 6 ( 4 ) N ( 2 ) - G a -N ( 6 ) - N ( 5 ) - 5 3 . 9 ( 4 ) Mo - N ( 5 ) - N ( 6 ) - Ga 5 . 4 ( 5 ) N( 1 ) -Mo -N ( 5 ) - N ( 6 ) 3 8 . 4 ( 4 ) N ( 5 ) -Mo -N ( 3 ) - N ( 4 ) 3 7 . 7 ( 4 ) Mo - N ( 5 ) - N ( 6 ) - Ga 5 . 4 ( 5 ) N ( 6 ) - G a -N(4 ) -N ( 3 ) - 5 6 . 6 ( 4 ) N ( 4 ) - G a -N ( 6 ) - N ( 5 ) 4 8 . 9 ( 4 ) Mo - N ( 3 ) - N(4 ) -Ga 7 . 9 ( 6 ) N ( 3 ) -Mo -N ( 5 ) - N ( 6 ) - 4 6 . 0 ( 4 ) N ( 3 ' ) - M o ' - N ( 1 * ) - N ( 2 ' ) 41 . 0 ( 4 ) Mo ' - N ( 3 ' ) - N ( 4 ' ) - G a ' 5 . 3 ( 6 ) N ( 4 ' ) - G a ' - N ( 2 ' ) - N ( 1 ' ) - 5 3 . 6 ( 4 ) N ( 2 ' ) - G a ' - N ( 4 ' ) - N ( 3 ' ) 4 8 . 3 ( 4 ) Mo ' - N ( T ) - N ( 2 ' ) - G a ' 3 . 8 ( 6 ) N O ' ) -Mo ' - N ( 3 ' ) - N ( 4 ' ) - 4 6 . 3 ( 4 ) N ( 5 ' ) -Mo ' - N ( 1 ' ) - N ( 2 ' ) - 4 4 . 4 ( 4 ) Mo ' - N ( 5 * ) - N ( 6 ' ) - G a ' 1 . 7 ( 6 ) N ( 6 ' ) - G a ' - N ( 2 ' ) - N ( 1 ' ) 4 8 . 5 ( 4 ) N ( 2 ' ) - G a ' - N ( 6 ' ) - N ( 5 ' ) -51 . 3 ( 4 ) Mo ' - N ( 1 ' ) - N ( 2 * ) - G a ' 3 . 8 ( 6 ) N O ' ) -Mo ' - N ( 5 * ) - N ( 6 ' ) 41 . 4 ( 4 ) N ( 5 ' ) -Mo ' - N ( 3 * ) - N ( 4 ' ) 3 9 . 3 ( 4 ) Mo ' - N ( 5 ' ) - N ( 6 ' ) - G a ' 1 . 7 ( 6 ) N ( 6 ' ) - G a ' - N ( 4 * ) - N ( 3 ' ) - 5 5 . 1 ( 4 ) N(4 ' ) - G a ' - N ( 6 ' ) - N ( 5 ' ) 51. 0 ( 4 ) Mo ' - N ( 3 ' ) - N ( 4 ' ) - G a ' 5 . 3 ( 6 ) N ( 3 ' ) - M o ' - N ( 5 ' ) - N ( 6 ' ) - 4 3 . 5 ( 4 ) 228 [MeGapz,]Mo(CO),SnPh Bond l e n g t h s (A) w i t h e s t i m a t e d s t a n d a r d d e v i a t i o n s i n p a r e n t h e s e s Bond L e n g t h ( A ) B o n d L e n g t h U ) Sn -Mo 2.B579(3) N ( 6 ) - C ( 1 3 ) 1 .346(4) Sn - C ( 1 4 ) 2.157(3) C ( 5 ) - C ( 6 ) 1 . 377( 5) Sn - C ( 2 0 ) 2.166(3) C ( 6 ) - C ( 7 ) 1 . 370(6) Sn - C ( 2 6 ) 2 .151(3) C ( B ) - C ( 9 ) 1 . 360(5) Mo - N O ) 2 .244(2) C ( 9 ) - C ( 10 ) 1 .356(5) Mo -N(3) 2 .239(2) C( 1 1 )-C(12) 1 .380(5) Mo -N(5) 2 .244(2) C( 12 ) - C ( 1 3 ) 1 .362(6) Mo - C ( 1 ) 1 .967(3) C ( 1 4 ) - C ( 1 5 ) 1 .364(5) Mo -C(2) 2.000(3) C( 14)-C(19) 1 .365(4) Mo -C(3) 1.994(3) C( 15 ) - C ( 1 6 ) 1 .386(5) Ga -N(2) 1 .923(3) C( 1 6 ) - C ( 1 7 ) 1 .362(6) Ga -N(4) 1 .920(3) C( 1 7 ) - C ( I B ) 1 .379(6) Ga - N ( 6 ) 1.931(3) C( 18)-C(19) l .382(5) Ga -C(4) 1.943(4) C(20)-C(21) 1 .372(5) 0( 1 ) - C ( 1 ) 1 .154(4) C ( 2 0 ) - C ( 2 5 ) 1 .380(5) 0(2) -C(2) 1.139(3) C(21)-C(22) 1 .364(5) 0(3) -C(3) 1.14K3) C ( 2 2 ) - C ( 2 3 ) 1.386(6) N O ) -N(2) 1 . 367 (3) C ( 2 3 ) - C ( 2 4 ) 1 .351(6) N( 1 ) -C(5) 1 . 327(4 ) C ( 2 4 ) - C ( 2 5 ) 1 .390(5) N(2) -C(7) 1 .343(4 ) C ( 2 6 ) - C ( 2 7 ) 1 .380(5) N(3) -N(4) 1 .364(3) C ( 2 6 ) - C ( 3 1 ) 1 . 3 8 8 ( 4 ) N(3) - C ( B ) 1 .331(4) C ( 2 7 ) - C(2B) 1 . 376(5) N(4) - C ( 1 0 ) 1 .343(4 ) C ( 2 B ) - C ( 2 9 ) 1 .384(5) N ( 5 ) - N ( 6 ) 1 .356(3) C ( 2 9 ) - C ( 3 0 ) 1 .372(5) N ( 5 ) -C(11) 1.344(4) C ( 3 0 ) - C ( 3 1 ) 1 .386(5) 229 [MeGapZo]Mo(CO)oSnPho, cont'd Bond a n g l e s ( d e g ) w i t h e s t i m a t e d s t a n d a r d d e v i a t i o n s i n p a r e n t h e s e s B o n d s A n g l e ( d e g ) Mo - S n - C ( 1 4 ) 1 1 2 . 50 ( 8 ) Mo - S n - C ( 2 0 ) 1 1 3 . 6 9 ( B ) Mo - S n - C ( 2 6 ) 1 1 3 . 00 ( 8 ) C( 1 4 ) - S n - C ( 2 0 ) 1 0 5 . 57 ( 1 1 ) C( 1 4 ) - S n - C ( 2 6 ) 1 0 6 . 01 ( 1 1 ) C ( 2 0 ) - S n - C ( 2 6 ) 1 0 5 . 3 8 ( 1 1 ) Sn -Mo - N ( 1 ) 1 2 9 . 32 ( 6 ) Sn - M o - N ( 3 ) 1 2 7 . 95 ( 6 ) Sn -Mo - N ( 5 ) 1 2 6 . 8 3 ( 7 ) Sn -Mo - C ( 1 ) 6 7 . 2 2 ( 9 ) Sn -Mo - C ( 2 ) 6 7 . 5 7 ( 6 ) Sn -Mo - C ( 3 ) 6 7 . 8 2 ( B ) N ( 1 ) - M o - N ( 3 ) 8 5 . 61 ( 9) N ( 1 ) - M o - N ( 5 ) 8 6 . 0 2 ( 9 ) N ( 1 ) - M o - C ( 1 ) 1 6 3 . 4 6 ( 1 1 ) N ( 1 ) - M o - C ( 2 ) 8 2 . 7 2 ( 10) N ( 1 ) - M o - C ( 3 ) 8 3 . 3 8 ( 10) N ( 3 ) - M o - N ( 5 ) 8 6 . 42 ( 9 ) N ( 3 ) - M o - C ( 1 ) 8 2 . 32 ( 10) N ( 3 ) - M o - C ( 2 ) 1 64 . 47( 10) N ( 3 ) - M o - C ( 3 ) 8 2 . 7 2 ( 10) N ( 5 ) - M o - C ( 1 ) 81 . 98( 1 1 ) N ( 5 ) - M o - C ( 2 ) 8 2 . 59 ( 10) N ( 5 ) - M o - C ( 3 ) 1 6 5 . 35( 10) C ( 1 ) - M o - C ( 2 ) 1 0 6 . 8 4 ( 12) C ( 1 ) - M o - C ( 3 ) 1 0 6 . 1 5( 12) C ( 2 ) - M o - C ( 3 ) 1 0 5 . 9 7 ( 12) N ( 2 ) - G a - N ( 4 ) 9 9 . 9 9 ( 1 1 ) N ( 2 ) - G a - N ( 6 ) 9 9 . 47 { 1 1 ) N ( 2 ) - G a - C ( 4 ) 1 1 7 . 9 ( 2 N ( 4 ) - G a - N ( 6 ) 1 0 0 . 0 0 ( 1 1 ) N ( 4 ) - G a - C ( 4 ) 1 1 7 . 8 ( 2 N ( 6 ) - G a - C ( 4 ) 1 1 8 . 1 ( 2 Mo - N ( 1 ) - N ( 2 ) 1 2 5 . 0 ( 2 Mo - N ( 1 ) - C ( 5 ) 1 2 8 . 4 ( 2 N ( 2 ) - N ( 1 ) - C ( 5 ) 1 0 6 . 5 ( 2 Ga - N ( 2 ) - N ( 1 ) 1 2 0 . 7 ( 2 Ga - N ( 2 ) - C ( 7 ) 1 3 0 . 6 ( 2 N ( 1 ) - N ( 2 ) - C ( 7 ) 1 0 8 . 6 ( 3 Mo - N ( 3 ) - N ( 4 ) 1 2 5 . 0 ( 2 Mo - N ( 3 ) - C ( 8 ) 1 2 8 . 3 ( 2 N ( 4 ) - N ( 3 ) - C ( 8 ) 1 0 6 . 7 ( 2 Ga - N ( 4 ) - N ( 3 ) 1 2 0 . 8 ( 2 Ga - N ( 4 ) - C ( 1 0 ) 1 3 1 . 0 ( 2 Bonds A n g l e ( d e g ) N ( 3 ) - N ( 4 ) - C ( 1 0 ) 107 . 9 3 Mo -N ( 5 ) - N ( 6 ) 125 . 4 2 Mo - N ( 5 ) - C ( 1 1 ) 127. 9 2 N ( 6 ) - N ( 5 ) - C ( 1 1 ) 106 . 6 2 Ga -N ( 6 ) - N ( 5 ) 120 . 5 2 Ga -N ( 6 ) - C ( 1 3 ) 130 . 7 2 N ( 5 ) - N ( 6 ) - C ( 1 3 ) 106 . 9 3 Mo - C ( 1 ) - 0 ( 1 ) 169. 7 3 Mo - C ( 2 ) - 0 ( 2 ) 172 . 1 3 Mo - C ( 3 ) - 0 ( 3 ) 172 . 7 3 N( 1 ) -C ( 5 ) - C ( 6 ) 1 1 1 . 1 3 C ( 5 ) - C ( 6 ) - C ( 7 ) 104 . 6 3 N ( 2 ) - C ( 7 ) - C ( 6 ) 109 . 2 3 N ( 3 ) - C ( B ) - C ( 9 ) 110. 9 3 C ( 8 ) - C ( 9 ) - C ( 1 0 ) 104 . 2 3 N ( 4 ) - C ( 1 0 ) - C ( 9 ) 110 . 3 3 N ( 5 ) - C ( 1 1 ) - C ( 1 2 ) 110 . 3 3 C( 1 1 ) - C ( 1 2 ) - C ( 1 3 ) 104 . 9 3 N ( 6 ) - C( 1 3 ) - C ( 1 2 ) 109 . 4 3 Sn - C ( 1 4 ) - C ( 1 5 ) 12 1. 9 2 Sn - C ( 1 4 ) - C ( 1 9 ) 120 . 2 2 C( 15) - C ( 1 4 ) - C ( 1 9 ) 117. 8 3 C( 14) - C ( 1 5 ) - C ( 1 6 ) 120 . 9 3 C( 15) - C ( 1 6 ) - C ( 1 7 ) 120. 5 4 C( 1 6 ) - C ( 1 7 ) - C ( 1 B ) 119. 6 3 C( 17) - C ( 1 8 ) - C ( 1 9 ) 120 . 0 3 C ( 1 4 ) - C ( 1 9 ) - C ( 1 8 ) 1 2 1 . 1 3 Sn - C ( 2 0 ) - C ( 2 1 ) 122 . 7 2 Sn - C ( 2 0 ) - C ( 2 5 ) 119. 6 2 C ( 2 1 ) - C ( 2 0 ) - C ( 2 5 ) 117 . 6 3 C ( 2 0 ) - C ( 2 1 ) - C ( 2 2 ) 122 . 2 4 C ( 2 1 ) - C ( 2 2 ) - C ( 2 3 ) 119. 0 4 C ( 2 2 ) - C ( 2 3 ) - C ( 2 4 ) 1 19 . 7 3 C ( 2 3 ) - C ( 2 4 ) - C ( 2 5 ) 1 2 0 . 8 4 C ( 2 0 ) - C ( 2 5 ) - C ( 2 4 ) 120 . 7 4 Sn - C ( 2 6 ) - C ( 2 7 ) 123 . 0 2 Sn - C ( 2 6 ) - C ( 3 1 ) 1 2 0 . 1 2 C ( 2 7 ) - C ( 2 6 ) - C ( 3 1 ) 116 . 9 3 C ( 2 6 ) - C ( 2 7 ) - C ( 2 8 ) 1 2 2 . 2 3 C ( 2 7 ) - C ( 2 8 ) - C ( 2 9 ) 1 2 0 . 2 3 C ( 2 8 ) - C ( 2 9 ) - C ( 3 0 ) 118. 7 3 C ( 2 9 ) - C ( 3 0 ) - C ( 3 1 ) 1 2 0 . 6 3 C ( 2 6 ) - C ( 3 1 ) - C ( 3 0 ) 121 . 4 3 230 APPENDIX II THEORETICAL INTENSITY PATTERNS FOR MASS SPECTROMETRY ANALYSIS G a 2 Mo 138 140 142 92 94 95 B6 97 9B 100 Ga G a - M o 6 9 71 161 163 164 165 166 167 168 169 171

Cite

Citation Scheme:

    

Usage Statistics

Country Views Downloads
China 4 42
United States 3 0
City Views Downloads
Beijing 4 0
Ashburn 3 0

{[{ mDataHeader[type] }]} {[{ month[type] }]} {[{ tData[type] }]}

Share

Share to:

Comment

Related Items