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Transition metal derivatives of asymmetric pyrazolylgallate ligands Chong, Kenneth Samuel 1980

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TRANSITION METAL DERIVATIVES OF ASYMMETRIC PYRAZOLYLGALLATE LIGANDS by KENNETH SAMUEL CHONG B.Sc. (Honours) The U n i v e r s i t y o f B r i t i s h Columbia, 1976 A THESIS SUBMITTED IN PARTIAL FULFILMENT THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY i n THE FACULTY OF GRADUATE STUDIES (Department of Chemistry) We accept t h i s t h e s i s as conforming to the r e q u i r e d standard THE UNIVERSITY OF BRITISH COLUMBIA March 1980 © Kenneth Samuel Chong, 1980 In presenting th i s thes is in pa r t i a l fu l f i lment of the requirements for an advanced degree at the Univers i ty of B r i t i s h Columbia, I agree that the L ibrary shal l make it f ree ly ava i l ab le for reference and study. I fur ther agree that permission for extensive copying of th is thesis for scho lar ly purposes may be granted by the Head of my Department or by his representat ives. It is understood that copying or pub l i ca t ion of th is thesis for f inanc ia l gain sha l l not be allowed without my writ ten permission. Depa rtment The Univers i ty of B r i t i s h Columbia 2075 Wesbrook P l a c e Vancouver, Canada V6T 1W5 ABSTRACT The reaction of sodium pyrazolide or sodium 3,5-dimethyl-pyrazolide with trimethyl gallium followed by reaction of the resultant adduct with 'ethanolamine' produces novel asymmetric tridentate ligands which are capable of either meridional or f a c i a l coordination i n t r a n s i t i o n metal complexes. Na +('pz')" + Me3Ga _™ F_> Na +[Me 3Ga (' pz •) ] " Na +[Me 3Ga('pz*)]~ + R^NO^CH^H > Na +L~ + MeH With R' = H, these ligands react with divalent t r a n s i t i o n metal ions to give octahedral bis-ligand complexes. However with R* = Me, reaction with divalent t r a n s i t i o n metal ions pro-duced either t r i g o n a l bipyramidal (R = Me) or binuclear f i v e -coordinate (R = H) complexes. The asymmetric chelating g a l l a t e ligands reacted with Mn(CO) 5Br to give LMn(CO)3 and with appropriate Gp VI carbonyl derivatives to give LM(CO) 3 ( M = Cr, Mo, W). The carbonyl anions were found to be stereochemically non-rigid i n solution and a mechanism f o r the f l u x i o n a l process i s proposed. Reaction o f LM(CO) 3 (M = Mo, W) w i t h v a r i o u s t h r e e - e l e c t r o n l i g a n d s gave d e r i v a t i v e s o f the form, LM(CO) 2T (T = NO, N 2Ph, C 3 H 5 C 4H 7, C 7H ?, and CH 2SMe). A s i m i l a r f l u x i o n a l process (to t h a t found i n the c a r b o n y l anions) was found i n the complex, [Me 2Ga(pz)(OCH 2CH 2NH 2)] Mo(CO) 2(n -C^H^). In a d d i t i o n , the c y c l o h e p t a t r i e n y l d e r i v a t i v e s were found to be f l u x i o n a l as a r e s u l t o f a r a p i d l y r o t a t i n g C^Uj r i n g . Depending on the nature of T, the LM(CO) 2T d e r i v a t i v e s can e x h i b i t both p o s i t i o n a l and c o n f o r m a t i o n a l isomerism and t h i s s u b j e c t i s d i s c u s s e d i n d e t a i l . R eaction of Na +L~ (R = R'= Me) wi t h Ni(NO)I and Cu(PPh 3)Br gave LNi(NO) and LCu(PPh 3) r e s p e c t i v e l y . Both of these molecules were found to be f l u x i o n a l i n s o l u t i o n and a s i m i l a r mechanism to t h a t proposed f o r the Gp VI c a r b o n y l i o n s i s invoked t o ex-p l a i n these f l u x i o n a l p r o c e s s e s . The compounds, LMn(NO) 2 and LFe(NO) 2 (19-electron) were prepared by r e a c t i o n o f Na +L (R = R'= Me) wi t h a p p r o p r i a t e metal d i n i t r o s y l p r e c u r s o r s . a n d are the f i r s t of t h e i r type t o be s y n t h e s i z e d . F i n a l l y , r e a c t i o n o f Na +L~ (R = R'= Me) w i t h M o ( N O ) 2 C l 2 gave LMo(NO) 2Cl. In a d d i t o n t o s t u d i e s i n v o l v i n g the l i g a n d L, the p y r a -z o l y l b r i d g e d dimers [ N i ( ' p z 1 ) ( N O ) ] 2 , [ F e ( ' p z ' ) ( N O ) 2 1 2 and [ C o ( ' p z ' ) ( N O ) 2 ] 2 were prepared and t h e i r r e a c t i v i t y towards n u c l e o p h i l e s s t u d i e d . The i r - a l l y l compounds [Me 2Ga (pz" ) 2 ] M (C 3H 5) (M = N i or Pd) and [Ni (pz") (C 3H 5) ]"2 were a l s o prepared. A l l the prepared compounds were s y s t e m a t i c a l l y c h a r a c t e r -i z e d w i t h u v - v i s , i r and XH nmr spectroscopy as w e l l as mass spectrometry. In a d d i t i o n , x-ray s t u d i e s were c a r r i e d out (by - i v -D r . S. R e t t i g ) on s e v e r a l of the p r e p a r e d compounds and these d a t a are c o r r e l a t e d w i t h o t h e r p h y s i c a l measurements. - v -TABLE OF CONTENTS Page ABSTRACT i i TABLE OF CONTENTS V LIST OF TABLES . . x i LIST OF FIGURES x i i LIST OF ABBREVIATIONS xvi ACKNOWLEDGEMENT x v i i i CHAPTER I INTRODUCTION 1 1.1 General Introduction 1 1.2 General Techniques 4 1.3 Physical Measurements 5 CHAPTER II COORDINATION COMPOUNDS 7 2.1 Introduction 7 2.2 Experimental 8 2.2.1 Starting Materials 8 2.2.2 Preparation of H 2NCH 2CH 20«GaMe 2 8 2.2.3 Preparation of Sodium Pyrazolide and Sodium 3,5-Dimethylpyrazolide 9 2.2.4 Preparation of the Ligands, Na +[Me 2Ga (C 3HN 2R 2)(OCH 2CH 2NR' 2)] (R,R'=H,Mef 9 2.2.5 Preparation of Transition Metal Derivatives 10 - v i -Page 2.3 Results and Discussion 11 2.3.1 H2NCH2CH20-GaMe2 11 2.3.2 The Octahedral Complexes, [Me 2Ga(C3HN2R2)(OCH 2 CH2NH 2 )I2M (R=H ,Me) 15 2.3.3 The Five Coordinate Complexes, "Me2Ga(pz")(OCH2CH2NMe2)]M ; (pz") 2GaMe 2] 24 2.4 Summary 33 CHAPTER III CARBONYL DERIVATIVES OF Mn,Cr,Mo and W 33 3.1 Introduction 33 3.2 Experimental 34 3.2.1 Starting Materials 34 3.2.2 Preparation of LMn (CO) 3 3 5 3.2.3 Preparation of Na +LM(CO) 3~ 3 5 3.2.4 Preparation of [Me2Ga(pz") (OCH 2CH 2NMe 2)]M(CO) 3" M=(Cr,Mo,W) 38 3.2.5 Preparation of LM(CO)2NO (M=Mo,W) 38 3.2.6 Preparation of LM(CO) y(N„Ph) (M=Mo,W) 40 3.2.7 Preparation of LM(CO),('allyl') (M=Mo,W) 4 0 3.2.8 Preparation of LM(CO) 2(C 7H 7) (M=Mo,W) .. 45 3.2.9 Reaction of [Me 2Ga(pz")(OCH 2CH 2NMe 2)] Mo(CO) 2(n 3-C 7H 7) with Fe(CO) 5 45 3.2.10 Preparation of LM(CO)2(CH2SMe) (M-Mo,W) 4 7 3.2.11 Preparation of [MeGa(pz)3]Mo(CH2SMe) ... 48 3.2.12 Reactions of the Chromium Carbonyl Anions . . . . ; 4 8 - v i i -Page 3.3 R e s u l t s and D i s c u s s i o n 50 3.3.1 LMn(CO) 3 5 0 3.3.2 LM(CO) 3~ (M=Cr,Mo,W) 55 3.3.3 LM(CO) 2T (M=Mo,W) 59 3.3.3.1 N i t r o s y l D e r i v a t i v e s (T=NO) ... 60 3.3.3.2 A r y l d i a z o D e r i v a t i v e s (T=N 2Ar) 64 3.3.3.3 ' A l l y l ' D e r i v a t i v e s (T= n3-C 3H 5 o r n 3 _ c 4 H 7 ) 69 3.3.3.4 C y c l o h e p t a t r i e n y l D e r i v a t i v e s (T=n3-C7H7) 78 3.3.3.5 Thiomethoxymethyl D e r i v a t i v e s (T=n2-CH2SMe) 89 3.3.3.6 Trends i n LM(CO) 2T D e r i v a t i v e s . 96 3.4 Summary 99 CHAPTER IV PYRAZOLYL DERIVATIVES OF METAL NITROSYLS 103 4.1 I n t r o d u c t i o n ... 103 4.2 Experimental 103 4.2.1 S t a r t i n g M a t e r i a l s 103 4.2.2 Rea c t i o n of Ni(NO)I wi t h Sodium ' P y r a z o l i d e ' 104 4.2.3 P r e p a r a t i o n of [Co (pz") ( N O ) 2 ] 2 104 4.2.4 P r e p a r a t i o n o f [ F e ( p z " ) ( N O ) 2 1 2 105 4.2.5 Reaction of [ N i ( ' p z ' ) ] w i t h N u c l e o p h i l e s 105 4.2.6 Reaction of [M(pz")(NO)„] 9 (M=Co,Fe) wi t h PPh 3 7.7 108 4.2.7 P r e p a r a t i o n of E t 4 N + [ ( O N ) N i ( p z " ) 2 ( I ) N i (NO) ] ~ 108 4.2.8 P r e p a r a t i o n of E t 4 N + [ ( O N ) N i ( p z " ) 2 ( C l ) Ni (NO) ] ~ 110 - v i i i -Page 4.2.9 Preparation of Na +[(ON)Ni(pz") 3 Ni (NO) ]~ 7... 110 4.2.10 Reaction of [Fe(pz")(NO) 2] 2 with ± 2 111 4.3 Results and Discussion I l l 4.3.1 Pyrazolyl Bridged Metal N i t r o s y l s I l l 4.3.2 Reaction of Nucleophiles with Pyrazolyl Bridged Dimers 120 4.4 Summary 124 CHAPTER V METAL NITROSYL DERIVATIVES OF PYRAZOLYLGALLATE LIGANDS 126 5.1 Introduction 12 6 5.2 Experimental 127 5.2.1 Starting Materials 127 5.2.2 Preparation of [Me2Ga(pz") (OCH2CH2NMe2)]Ni(NO) 127 5.2.3 Preparation of [Me2Ga(pz") (OCH 2CH 2NMe 2)]Ni(pz") 2Ni(NO) 127 5.2.4 Preparation of [MeGa(pz") 3]Ni(NO) 128 5.2.5 Preparation of [MeGa(pz) 3]Ni(NO) 129 5.2.6 Reaction of Ni(NO)I with_ __ • Na +[Me 2Ga(pz) 2]~ and Na +[Me 2Ga(pz") 2]~.. 129 5.2.7 Reaction of Ni(NO)I with 'Et4N + [Me 2Ga(pz") 2]-' 130 5.2.8 Preparation of (pz"H) 2Ni(NO)I 130 5.2.9 Preparation of [Me2Ga(pz") (OCH2CH2NMe2)]Mo(NO)2C1 131 5.2.10 Preparation of [Me 2Ga(pz") (OCH2CH2NMe2)]Mn (NO) 2 131 5.2.11 Preparation of [Me 2Ga(pz") (OCH0CH0NMe:))]Fe(NO) 9 132 - i x -Page 5.2.12 Reaction of Fe(NO) 2I with [MeGa(pz) 3]" and [MeGa(pz") 3] 133 5.2.13 Reaction of Co(NO) 2I with Na+[Me 2Ga(pz")(OCH 2CH 2NMe 2)]~ 134 5.3 Results and Discussion ' 135 5.3.1 Nickel N i t r o s y l Derivatives 135 5.3.2 [Me 2Ga(pz")(OCH 2CH 2NMe 2)]Mo(NO) 2Cl 140 5.3.3 D i n i t r o s y l Derivatives of Manganese and Iron 142 5.4 Summary 146 CHAPTER VI FURTHER INVESTIGATIONS 148 6.1 Introduction 148 6.2 Experimental 14 8 6.2.1 Starting Materials 148 6.2.2 Preparation of [Me 2Ga(pz") 2]Pd'allyl' .. 148 6.2.3 Preparation of [Me2Ga (pz") 2J*Ni (C 3H 5) ... 149 6.2.4 Reaction of Na +L"with [ ( C 3 H 5 ) N i B r ] 2 .... 150 6.2.5 Preparation of [ N i ( p z " ) ( C 3 H 5 ) ] 2 151 6.2.6 Preparation of [Me2Ga(pz") (OCH 2CH 2NMe 2)]Cu(PPh 3) 151 6.2.7 Attempted Preparation of LCu(CO) (R=R'=Me) 152 6.2.8* Reaction of Na +L~ with F e 3 ( C O ) 1 2 153 6.2.9 Reaction of Na +L~ (R=R'=Me) with ,Co(CO) 4I' 153 6.3 Results and Discussion 154 6.3.1 A l l y l i c Derivatives of Nickel and Palladium 154 6.3.2 Cu(I) Derivatives 158 - x -Page 6.3.3 Reactions of Na +L~ (R=R'=Me) wi t h Iron and C o b a l t 'Carbonyls' 6.3.4 Re l a t e d T r i d e n t a t e Ligands 163 6.4 C o n c l u s i o n s and P e r s p e c t i v e s 164 BIBLIOGRAPHY 165 APPENDIX I THEORETICAL INTENSITY PATTERNS FOR MASS SPECTROSCOPIC ANALYSIS 171 APPENDIX I I STEREO DIAGRAMS OF SOME OF THE PREPARED DERIVATIVES 174 - x i -LIST OF TABLES Table Page I A n a l y t i c a l Data of [Me2Ga (C-jHN^) (OCH2CH2NH2) ] 2M 12 II A n a l y t i c a l Data of [Me0Ga(pz")(OCH-CH-NMe,)]M C(pz") 2GaMe 2] .A J.A..A 13 III Mass Spectrum of [Me 2Ga(pz)(OCH 2CH 2NH 2] 2Co 17 IV Some Structural Parameters of sym-fac and mer [Me 2Ga(pz)(OCH 2CH 2NH 2] 2Ni 18 V El e c t r o n i c Spectra of [Me,Ga (C-.HN^PO (OCH2CH2NH2) J 2M ..AA.. 25 VI El e c t r o n i c Spectra of [Me,Ga(pzM)(0CH9CH-NMe,)}M [(pz") 2GaMe 2J ......A 26 VII Some Structural Parameters of [Me?Ga(pz") (OCH 2CH 2NMe 2)]M[(pz") 2GaMe 2] 7 31 VIII Physical Data for LMn(CO) 3 36 IX Physical Data for Et 4 +LM(CO) 3~ (R=R1=Me) 39 X A n a l y t i c a l and IR Data for LM(CO)2NO 41 XI A n a l y t i c a l and IR Data for LM (CO) 2 (N2Ph) 42 XII A n a l y t i c a l and IR Data for LM(CO) 2'allyl' 44 XIII A n a l y t i c a l and IR Data for LM(CO)2(C^H^) 46 XIV A n a l y t i c a l and IR Data for LM(CO)2CH2SMe 4 9 XV Mass Spectrum of [Me 2Ga(pz)(OCH 2CH 2NH 2)]Mn(CO) 3 . 51 XVI v C Q of DMn (CO) 3 Compounds 53 XVII 1H nmr Data for LM(CO)2NO 62 XVIII XH nmr Data for LM (CO) 2 (N2Ph). 65 XIX 1H nmr Data for LM (CO) 2 ' a l l y l 1 71 XX 1H nmr Data for LM (CO) 2 (C 7H 7) 82 XXI Low Temperature "^H nmr Data for the C 7H ? Ring in [Me 2Ga(pz)(OCH 2CH 2NMe 2)]W(CO) 2(n 3~C 7H 7) 88 - x i i -Table Page XXII XH nmr Data f o r LM(CO) 2 (CH^SMe) 91 XXIII Mass S p e c t r a l Data of [Me ?Ga(pz") (OCH CH NMeJ] Mo(CO) 2T .. ... 97 XXIV Mass S p e c t r a l Data of [Me^Ga(pz")(OCH^CH^NMe-)] W(CO) 2T : . . f 98 XXV Carbonyl S t r e t c h i n g ' Frequencies f o r Some DMo(CO) 2T Complexes 100 XXVI P h y s i c a l Data f o r [BM (' pz •) (NO) ] 109 XXVII P h y s i c a l Data f o r M + [ ( O N ) N i ( ' p z 1 ) 2 ( X ) N i ( N O ) ] ~ ... 1 1 2 XXVIII Mass S p e c t r a l Data f o r [M (pz") (NO) ] „ 117 V - x i i i -LIST OF FIGURES Figure Page 1 Bispyrazolylborate and trispyrazolylborate anions 1 2 Dimethyl(N,N-dimethylethanolamino)(1-pyrazolyl) ga l l a t e . . . 3 3 Molecular Structure of [Me„Ga(pz)„(0CH oCH oNMe.) c u ] 2 ? 2.....2...2......... 4 4 Molecular Structure of [Me 2NCH 2CH 20-GaMe 2] 2 11 5 Molecular Structure of H2NCH2CH20-GaMe2 15 6 Molecular Structure of sym-fac and mer [Me2Ga(pz) (OCH 2CH 2NH 2)]^Nl ' 16 7 Infrared Spectra of sym-fac and mer [Me_Ga(pz) (OCH 2CH 2NH 2)] 2Ni 7 20 8 Electr o n i c Spectra of sym-fac and mer [Me2Ga(pz) (OCH 2CH 2NH 2)J 2Ni 22 9 Electr o n i c Spectra of [Me9Ga(pz") (OCH CH NMej] M[ (pz") 2GaMe 2] 27 10 IR Spectra of [Me~Ga(pz")(OCH^CH.NMe.)]M [ (pz") 2GaMe 2] 29 11 . Molecular Structure of. [Me„Ga(pz") (OCH^CH-NMeO ]Ni ' [ (pz") 2GaMe 2] 7 30 12 IR Spectrum of [Me 2Ga(pz)(OCH 2CH 2NH 2)]Mn(CO) 3 52 13 100 MHz 1H nmr Spectrum of [Me.Ga(pz)(0CH-CH-NH9)] Mn(CO)3 54 14 100 MHz-1!! nmr Spectrum of Et.N +[Me 2Ga (pz") (OCH2CH2NMe2) ]W(CO) 3 57 15 Temperature Dependent nmr Spectrum of Et.N + [Me2Ga(pz") (OCH 2CH 2NMe 2)]Cr(CO) 3~ 7 58 16 Suggested Mechanism for the Observed Fluxional Process i n the LM(CO) 3~ Ions 59 17 100 MHz 1H nmr Spectrum of [Me-Ga(pz")(OCH-CH-NMe.)] W(CO)2NO 7 63 18 Isolated Isomers of LM(C0)oN0 61 - x i v -F i g u r e Page 19 Bonding Conformations of the 'ArN 2' Ligand 66 20 IR Spectrum of [Me 9Ga(pz")(OCH^CH-NMe )]Mo(CO) 9 (N 2Ph) \ . 67 21 100 MHz 1 H nmr Spectrum of [Me_Ga(pz") (OCH 2CH 2NMe 2) ]Mo(CO) 2(N 2Ph) 68 22a 100 MHz 1H nmr Spectrum of [Me 2Ga(pz") (OCH 2CH 2NH 2)]Mo(CO) 2(n 3"C 3E 5) 72 22b Expansion of 6-7.5 T 73 23 1H nmr and IR S p e c t r a of [Me_Ga(pz)(OCH CH^NH-)] w(co) 2(n 3 -c 4H 7) 75 24 Temperature Dependent 100 MHz nmr Spectrum of [Me 2Ga(pz)(OCH 2CH 2NMe 2)]Mo(CO ) 2 ( n 3-C 4H 7) 76 25 Suggested Mechanism f o r the F l u x i o n a l Process Observed i n [Me 9Ga(pz)(0CH_CH 9NMe 9)]Mo(CO)_ (n 3-C 4H ?) 2. 2. 77 26 M o l e c u l a r S t r u c t u r e of [Me Ga(pz")(OCH 9CH„NH„)] Mo (CO) 2 ( n 3 - C 4 H 7 ) f, 77 27 100 MHz 1H nmr Spectrum of [ C 7 H ? F e ( C O ) 3 ] 2 80 28 100 MHz 1H nmr Spectrum of [Me»Ga(pz)(OCH^CH-NMe-)] Mo(CO) 2(n 3-C 7H 7) \ 83 29 100 MHz 1H nmr and IR Sp e c t r a of [Me„Ga(pz) (OCH 2CH 2NH 2)]Mo(CO) 2(n 3-C 7H 7) 84 30 Temperature Dependent 100 MHz 1H nmr Spectrum of [Me 2Ga(pz)(OCH 2CH 2NMe 2 ) ] w(CO) 2(n 3-C ?H 7) 86 31 Low Temperature Spectrum of [Me 9Ga(pz)(OCH_CH 2NMe 2)] w(co) 2(n 3 -c 7H 7) \ 87 32 Bonding Conformations of the CH2-SMe Ligand 90' 33 IR Spectrum of [Me_Ga(pz")(0CH_CH 9NMe_)]Mo(CO)„ (n 2-CH 2SMe) . 90 34 100 MHz 1 H nmr Spectrum of [Me 2Ga(pz)(OCH 2CH 2NH 2)] Mo(CO) 2 (n 2-CH 2SMe) \ * 93 35 M o l e c u l a r S t r u c t u r e s of [Me ?Ga(pz)(OCH-CH-NMe ?)] Mo(CO)_(n 2-CH_SMe) and [Me.Ga(pz n)(OCH^CH^NMe^)] Mo (CO) ^  (n 2-CH 2SMe) 95 - X V -Figure Page 36 Molecular Structure of [Ni(pz")(NO)] 2 114 37 Molecular Structure of [ ( O N ) N i ( p z " ) 2 ] 2 N i 1 1 5 38 Molecular Structure of [M(pz") (NO) 2] 2, M=Co,Fe . . . 118 39 Molecular Structure of Et.N +[(ON)Ni(pz")„(I) Ni (NO) ]~ . . 122 40 . Molecular Structure of [Na•2THF] +[(ON)Ni(pz")_ Ni(NO)]" . ... 123 41 100 MHz H nmr Spectrum of [Me?Ga(pz") (OCH2CH2NMe2)]Ni(NO) 137 42 Proposed Mechanism for the Fluxional Process Observed i n [Me 2Ga(pz")(OCH 2CH 2NMe 2)]Ni(NO) 138 43 Molecular Structure of [Me,Ga(pz")(OCH CH NMe )] Ni (NO) . 13 8 44 100 MHz 1H nmr Spectrum of [Me„Ga(pz") (OCH2CH2NMe2) ]Mo (NO) 2C1 141 45 100 MHz 1H nmr Spectrum of [Me_Ga(pz") (OCH2CH2NMe2)]Mn(NO)2 144 46 Molecular Structure of [Me~Ga(pz")(OCH_CH_NMe_)] Fe(NO) 2 146 47 100 MHz 1H nmr Spectrum of [Me2Ga(pz") ]Pd(C 3H 5) . 156 48 Proposed Mechanism for the Fluxional Process Observed i n [Me 2Ga(pz") 2]Ni(C 3H 5) 157 49 100 MHz 1H nmr Spectrum of [Me2Ga(pz") (OCH 2CH 2NMe 2)]Cu(PPh 3) 159 50 Proposed Mechanism for the Fluxional Process Observed i n [Me 2Ga(pz")(OCH 2CH 2NMe 2)]Cu(PPh 3) ... 160 51 Possible Structure of [Me-Ga(pz")(OCH^CH^NMe )] c o 2 ( i ) 2 ( P z " H ) 2 1 6 2 - x v i -LIST OF ABBREVIATIONS The f o l l o w i n g a b b r e v i a t i o n s have been used throughout t h i s t h e s i s o A A n a l . atm °C c a l c d . -1 cm Cp Dq, B e E t F i g . h Hz i r J Angstrom A n a l y s i s atmosphere(s) degrees C e l s i u s c a l c u l a t e d wave numbers i n r e c i p r o c a l c e n t imeters n 5 - C 5 H 5 e l e c t r o n i c s p e c t r a l parameter: e x t i n c t i o n c o e f f i c i e n t e t h y l F i g u r e ( s ) hour(s) Hertz, c y c l e s per second i n f r a r e d magnetic resonance c o u p l i n g c o nstant MejGa R,R1 = H or Me - x v i i -m/e Me min ml mmol mol nmr P Ph ppm py pz pz" pzH pz"H r e f . r t THF uv v i s 1 n T V kK mass to charge r a t i o methyl minute(s) m i l l i l i t e r ( s ) m i l l i m o l e ( s ) mole (s) n u c l e a r magnetic resonance parent phenyl p a r t s per m i l l i o n p y r i d i n e p y r a z o l y l , C^H^N,, 3,5 d i m e t h y l p y r a z o l y l , C^H^N^ p y r a z o l e , C^H^^ 3,5 d i m e t h y l p y r a z o l e , C 5HgN 2 r e f e r e n c e (s) •a room temperature t e t r a h y d r o f u r a n u l t r a v i o l e t v i s i b l e monohapto di h a p t o t r i h a p t o pentahapto heptahapto nmr chemical s h i f t i r s t r e t c h i n g frequency k i l o K a i s e r s (1000 cm - 1) - x v i i i -ACKNOWLEDGEMENT I would l i k e t o thank my s u p e r v i s o r Dr. Alan S t o r r whose enthusiasm and w i t were a constant source of encouragement throughout the course of t h i s work. In p a r t i c u l a r , I would l i k e t o thank him f o r h i s guidance when i t was needed and h i s s i l e n c e when t h a t was needed. I would a l s o l i k e to thank my co-workers both p a s t and presen t whose companionship made the l a b o r a t o r y both a p l a c e o f p l e a s u r e as w e l l as a p l a c e of work. I extend my g r a t i t u d e to the t e c h n i c a l s t a f f of t h i s department and i n p a r t i c u l a r to Mr. Joe Nip (mass spe c t r o m e t r y ) , Ms. M. Tracey (nmr spectroscopy) and Mr. Pe t e r Borda (micro-a n a l y s i s ) whose d e d i c a t i o n to t h e i r work c o u l d not be surpassed. A s p e c i a l thanks t o Dr. S. R e t t i g whose x-ray s t u d i e s added con-s i d e r a b l y t o the success of t h i s work and to Drs. F. Aubke and R.C. Thompson f o r h e l p f u l d i s c u s s i o n (although not always about c h e m i s t r y ) . I would a l s o l i k e to thank Miss Debbie Shunamon who typed t h i s t h e s i s and Mr. Mic h a e l Chong who helped to pr o o f -read i t . F i n a l l y , I am indebted t o the N a t u r a l S c i e n c e s and Engin-e e r i n g C o u n c i l Canada f o r f i n a n c i a l support (1978-1980). - 1 -CHAPTER I INTRODUCTION 1.1 General I n t r o d u c t i o n In r e c e n t y e a r s , there has been a g r e a t d e a l o f a t t e n t i o n focused on the chemistry of p y r a z o l e and i t s t r a n s i t i o n metal d e r i v a t i v e s (1,2,3). For example, a n i o n i c p y r a z o l y l b o r a t e l i g -ands have been the s u b j e c t o f s e v e r a l r e c e n t reviews (4,5,6). These are l i g a n d s o f the general formula [ R n B ( p z ) ^ _ n ] (R = H, a l k y l , a r y l ; n = 0-2; pz = p y r a z o l y l , C^H.^^) - T n e b i s p y r a z o l y l -b orate anion (n = 2) resembles the 1,3-diketonate i o n and forms b i s - b i d e n t a t e c h e l a t e s w i t h the f i r s t row t r a n s i t i o n metal i o n s . However, i n c o n t r a s t to the 1,3-diketonate d e r i v a t i v e s where v a r i o u s a s s o c i a t i v e e q u i l i b r i a have been observed (7), p y r a z o l y l -borate d e r i v a t i v e s are always monomeric. I I F i g u r e 1. B i s p y r a z o l y l b o r a t e (II) anions. (I) and t r i s p y r a z o l y l b o r a t e - 2 -The trispyrazolylborate anion (n = 1) i s formally analo-gous to the well studied cyclopentadienyl ligand - both are uninegative, donate s i x electrons to the central metal and are considered to occupy three coordination s i t e s . However, trans-i t i o n metal derivatives of the trispyrazolylborate ligands are usually more stable than t h e i r cyclopentadienyl analogues. Consequently, several novel systems have been characterized using pyrazolylborates for which the analogous cyclopentadienyl system i s unknown or unstable. For example, the complex [HB (pz) 1^ Cu (CO) i s stable i n a i r for several weeks (8) while CpCu(CO) could not be p u r i f i e d (9). Analogous pyrazolyl ligands involving heavier Gp III metals have received comparatively l i t t l e attention. Almost a l l the work i n t h i s area has involved gallium. The b i s p y r a z o l y l -g a l l a t e anion was prepared by the following route (10) : NaH + p z H — »Na (pz) + H 2 (1) + — THF 1 + — Na (pz) + GaMe 3— >Na [Me3Ga(pz)] (2) Na+[Me^Ga (pz)] ~ + pzH T H F >Na+[Me.Ga (pz) ]" + MeH (3) J reflux ^ In contrast to the analogous boron system, addition of excess pyrazole i n step (3) did not r e s u l t i n the formation of the tridentate anion. However, the t r i s p y r a z o l y l g a l l a t e anion was e a s i l y prepared by the following route (11): MeGaCl 2 + 3Na (pz) — »Na [MeGa (pz) 3] + 2NaCl (4) In general, the chemistry of these ligands p a r a l l e l s that of t h e i r boron analogues. However, the substitution of gallium - 3 -for boron leads to some important differences. The longer Ga-N o o bond (3:2.0 A c f . =1.5 A for B-N) increases s t e r i c crowding around the coordinated metal. The gallium ligands provide more electron density to the central metal. In addition, c e r t a i n t r a n s i t i o n metal derivatives of the gallium ligands undergo chemical transformations not observed i n analogous boron systems (12) . A s i g n i f i c a n t deviation from t h i s type of symmetric ligand can be made by replacing pzH i n equation (3) with a d i f f e r e n t 'active hydrogen' molecule. If N,N-dimethylethanolamine i s used, a p o t e n t i a l l y tridentate asymmetric ligand i s produced (Fig. 2). Figure 2. Dimethyl (N,N-dimethylethanolamino) (1-pyrazolyl)gallate anion. To date, t h i s type of ligand has not been reported i n boron systems. In i n i t i a l studies, t h i s ligand was found to act as a tridentate ligand towards the l a t e r f i r s t row t r a n s i t i o n metal ions (13,14). However, instead of the expected monomeric octa-hedral bis-ligand complexes, binuclear complexes of the general formula, [Me 2Ga(pz) 2(OCH 2CH 2NMe 2)M] 2 (M = Co, Ni, Cu, Zn), were is o l a t e d . The c r y s t a l structure of the copper complex i s shown - 4 -i n F i g . 3. The formation of these complexes was thought to arise as a consequence of the bulky methyl groups on the amino nitrogen atom of the g a l l a t e ligand. Figure 3. Molecular structure of [Me 2Ga(pz) 2 (OCH 2CH 2NMe 2)Cu] 2. This thesis describes the preparation of related asym-metric ligands and a general investigation of t h e i r r e a c t i v i t y . towards a variety of transition'metal species. 1.2 General Techniques A i r sensitive materials were handled i n a dry box (Vacuum/ Atmospheres Corporation model DRI LAB HE-43-2) containing pre-p u r i f i e d nitrogen (Canadian Liquid A i r , K grade) and f i t t e d with a model HE 493 D r i t r a i n , or on a high vacuum l i n e . The vacuum l i n e was equipped with a Toepler pump which was used routinely for measurement of gas volumes. Reactions, unless otherwise - 5 -stated, were car r i e d out i n the glove box or i n a nitrogen-blanketed apparatus. A l l solvents were dried using l i t e r a t u r e methods (15) and d i s t i l l e d under N 2 before use. The most frequently used solvents were available i n 2 £ s t i l l p o t s (diethyl ether and THF over Na/ benzophenone, benzene over K). These solvents were refluxed continuously and c o l l e c t e d just p r i o r to use or stored under N 2 after d i s t i l l a t i o n . 1.3 Physical Measurements Infrared studies were car r i e d out on a Perkin Elmer 457 spectrophotometer and the spectra were calibr a t e d with the 16 01 cm x band of polystyrene. Samples were prepared either as Nujol mulls between KBr plates or as solutions i n cyclohexane or methylene chloride. These measurements were useful not only i n i d e n t i f y i n g products but also in assigning stereochemistry. In those compounds containing carbonyl (or n i t r o s y l ) groups, the number and i n t e n s i t y of the observed bands could be used to d i f f e r e n t i a t e between various geometric isomers. "^H nmr studies were c a r r i e d out on a Varian XL-100 or on a 270 MHz spectrometer. Samples were prepared by condensing the required amount of solvent (CgDg or d^-acetone; Sharp and Dohme of Canada Ltd.) onto the s o l i d material contained i n a nmr tube f i t t e d with a tap adapter. The nmr tube was subsequently flame sealed. In addition to stereochemical assignments, i t was possible to use t h i s technique to quantify isomer r a t i o s i n those compounds containing more than one isomer. Variable - 6 -temperature studies (XL-100) were carried out on those compounds which showed evidence of stereochemical n o n r i g i d i t y i n solution at r t . Mass spectra were recorded on a VARIAN/MAT CH4B spectro-meter as s o l i d probes using the d i r e c t i n s e r t i o n method and were used i n conjunction with infrared and "^H nmr to i d e n t i f y products. Since the parent mass was observed i n most cases, molecular weight information was e a s i l y obtained. The i d e n t i f i c a t i o n of fragments was s i m p l i f i e d by comparison of the observed i n t e n s i t y patterns with t h e o r e t i c a l i n t e n s i t y patterns generated from natural isotopic abundances of each element. Some of these patterns are presented i n Appendix I. The ligand f i e l d properties of coordination complexes were probed using u v - v i s i b l e spectroscopy. Samples were prepared as solutions under N 2- Experiments were carr i e d out on a CARY 14 spectrophotometer. Where appropriate, x-ray structures were obtained on s u i t -able c r y s t a l s . This work was carried out by Dr. S. Rettig. D e f i n i t i v e bonding parameters could be obtained and these were correlated with other physical measurements. In addition to the diagrams i n the main body of the the s i s , stereo diagrams of the various structures described are compiled i n Appendix I I . - 7 -CHAPTER II COORDINATION COMPOUNDS 2.1 Introduction The tridentate ligands, [RB(pz) 3] (Fig. 1, p. 1) and [MeGa(pz) 3] , form octahedral coordination compounds with d i -valent t r a n s i t i o n metal ions (11,17). In contrast, reaction of the ligand, [Me2Ga(pz) (OCH2CH2NMe2)] ~ (Fig. 2, p. 3 ) , with d i -valent t r a n s i t i o n metal ions led to the formation of binuclear f i v e coordinate complexes (13,14). This 'rearrangement' i s believed to occur as a d i r e c t consequence of the s t e r i c bulk of the asymmetric ligand. S p e c i f i c a l l y , the accommodation of two ligands around a single metal atom i s prevented by mutual s t e r i c i n t e r a c t i o n between the methyl groups on the amino nitrogen atoms. This chapter describes the preparation of the less s t e r i c a l l y demanding ligands, [Me2Ga (pz) (OCH2CH2NH2)] and [Me2Ga(pz") (OCH2CH2NH2) ]~ (pz" = 3,5 dimethylpyrazolyl, C 5H 7N 2) ,. as well as the more s t e r i c a l l y demanding ligand,[Me 2Ga(pz")(OCH 2CH 2NMe 2)]" and d e t a i l s t h e i r reactions with divalent t r a n s i t i o n metal ions. The preparation and properties of the complex, H2NCH2CH20-GaMe2 are also described. Parts of thi s work have been described previously (18,19). - 8 -2.2 Experimental 2.2.1 Starting Materials Pyrazole and 3,5-dimethylpyrazole (K and K Laboratories Inc.) were used as supplied. 2-aminoethanol and 2-N,N-dimethyl-aminoethanol (Aldrich Chemical,Co.) were refluxed over CaSO^ and d i s t i l l e d before use. NaH, NiBr 2 , CoCl 2, CuBr 2 and N i ( B F 4 ) 2 -6H20 (Alfa Inorganics) were used as supplied. FeCl 2'1.5 THF was prepared from hydrochloric acid and iron metal i n THF (2 0). Me^Ga was prepared as described i n the l i t e r a t u r e (21) and i t s purity checked by "'"H nmr spectroscopy. 2.2.2 Preparation of H2NCH2CH2O^GaMe C H H J C H CH OH + GaMe — > H.NCH CH O-GaMe, + MeH (5) reflux A solution of ethanolamine (0.771 g; 12.64 mmol) i n benzene was added to a solution of trimethyl gallium (1.451 g; 12.64 mmol) i n the same solvent. The clear solution was refluxed u n t i l evolution of methane ceased (overnight). Solvent was removed i n vacuo and the remaining s o l i d p u r i f i e d by sublimation at 80°C. The i s o l a t e d colourless c r y s t a l s were extremely sensitive to oxygen and water. Anal. Calcd. for H2NCH2CH20-GaMe2: C, 30.1; H, 7.5; N, 8.8. Found: C, 29.9; H, 7.0; N, 8.5. XH nmr (T, C gD 6): -CH 2CH 2- f 6.66 (t ( J z 5Hz), 2H) > 7.83 (t ( J z 5Hz), 2H); -NH2, 9.09 (br, 2H); -GaMe2, 10.13 (s,6H). - 9 -2.2.3 P r e p a r a t i o n of Sodium P y r a z o l i d e and Sodium 3,5-dimethyl  p y r a z o l i d e NaH + p z H — N a (pz) + H 2 (6) A THF s o l u t i o n of p y r a z o l e (13.40 g; 0.20 mol) was added dropwise t o a s t i r r e d s l u r r y o f NaH (4.80 g; 0.20 mol) i n the same s o l v e n t ( t o t a l volume - 200 ml) and the mixture s t i r r e d o v e r n i g h t to produce a c l e a r c o l o u r l e s s s o l u t i o n . At t h i s time, e v o l u t i o n o f hydrogen had ceased and s o l v e n t was removed i n vacuo. The extremely h y g r o s c o p i c s a l t was washed with benzene and d r i e d i n vacuo. Y i e l d was q u a n t i t a t i v e . Sodium 3,5 - d i m e t h y l p y r a z o l i d e was prepared by a s i m i l a r method and again the y i e l d was q u a n t i -t a t i v e . 2.2.4 P r e p a r a t i o n o f the l i g a n d s , Na +[Me 2Ga (C 3HN 2R 2)_ (OCH 2CH 2NR' 2)] ~ R,R' = H, Me N a + [ C 3 H N 2 R 2 ] ~ + G a M e 3 — T H F > N a + [ M e 3 G a ( C 3 H N 2 R 2 ) ] " Na [Me GafCjHN.RJ] + R'2NCH CH2OH — > CH 4 + Na L r e f l u x (7) (8) L = Mefia \ O \ / N R ; For the purposes of t h i s t h e s i s , L s h a l l always r e f e r t o t h i s l i g a n d . - 10 -A l l four ligands were prepared by the same general route and the following i s a t y p i c a l preparation of one of these (R = H, R1 = Me): Trimethyl gallium (4.28 g; 37.3 mmol) i n THF was added to sodium pyrazolide (3.36 g; 37.3 mmol) i n the same solvent and the suspension was s t i r r e d u n t i l a clear solution was obtained ( = 15 min). A THF solution of N,N-dimethylethanol-amine (3.32 g; 37.3 mmol) was added to the solution and on re-flux i n g , slow evolution of methane occurred. The reaction was complete aft e r 24 h (ascertained by cessation of methane evolu-t i o n and by "^H nmr spectroscopy) . Solutions of ligands were di l u t e d to standard volumes (usually 250 ml) and stored at 5°C. Aliquots of these solutions were used i n subsequent reactions. 2.2.5 Preparation of Transition Metal Derivatives The preparations of the t r a n s i t i o n metal derivatives are a l l very similar and can be summarized by the following procedure. To one equivalent of a s t i r r e d solution or suspension of the t r a n s i t i o n metal s a l t i n THF was added two^ " equivalents of ligand i n the same solvent. After s t i r r i n g overnight, the mix-ture was allowed to stand u n t i l the fine s o l i d had s e t t l e d . The clear solution was isola t e d using a pipet. (This procedure was necessary since the fine p r e c i p i t a t e could not be removed by f i l t r a t i o n ) . The THF solvent was removed i n vacuo and the residue 1 I n the reaction of 0le2Ga (pe") (OCH2CH2NMe2)] with CuBr 2, a 3:1 ligand to metal r a t i o was necessary, as a 2:1 r a t i o produced only intractable o i l s . - 11 -r e c r y s t a l l i z e d from xylene or benzene. The t r a n s i t i o n metal s t a r t i n g materials for a l l the preparations are given i n Table I and I I , together with physical data for the i s o l a t e d complexes. Estimated y i e l d s were ~ 50%. 2.3 Results and Discussion 2.3.1 H2NCH2CHO-GaMe2 Gallium a l k y l s are known to react with compounds containing a c i d i c hydrogen(s) to eliminate alkane. For example, trimethyl gallium reacts with N,N-dimethylethanolamine to produce the complex, [Me2NCH2CH20-GaMe2] 2 (22). The molecular structure of this compound i s shown i n Figure 4. Figure 4. Molecular structure of [ Me_NCH~CH_0•GaMe»] T a b l e I . A n a l y t i c a l Data of Me,G« M Colour T r a n s i t i o n Metal Precursor A n a l y s i s Isomer Found (%)/Calcd.(%) Comments H Mn white MnCl H Co magenta CoCl-H Ni blue NiBr„ H Ni purple NiBr, H Cu blue CuBr-i H Zn white ZnCl-Me Fe orange FeCl-Me Co magenta CoCl-Me N i A blue NiBr-Me N i z turquoise NiBr-C H N mer 33.1 33.1 6.1 5.9 16.3 16.5 a i r s e n s i t i v e mer 33.9 33.0 6.0 5.9 16.8 16.5 a i r s e n s i t i v e mer 32.9 32.8 5.9 5.9 16.3 16.4 s o l u t i o n a i r s e n s i t i v e mer 32.9 32.8 5.8 5.9 16.6 16.4 a i r stable fac 32.9 32.8 6.0 5.9 16.6 16.4 a i r stable f ac 33.9 32.5 4.9 5.8 18.1 16.3 a i r s e n s i t i v e fac 32.7 32.4 5.9 5.8 16.7 16.2 a i r s e n s i t i v e mer 39.3 38.2 7.1 6.8 14.5 14.8 extremely moisture and a i r s e n s i t i v e mer 38.5 38.0 6.9 6.7 14.2 14.8 s o l u t i o n a i r stable mer 44.8 44.6 6.9 6.9 13.0 13.0 a i r stable mer 40.6 40.2 7.2 7.1 13.4 13.4 a i r stable I r e c r y s t a l l i z e d with 1 mole of benzene 2 r e c r y s t a l l i z e d with 1 mole of acetone Table II. A n a l y t i c a l Data of MeyG !GaMe, Analysis Found(%)/Calcd(%) M Colour Transition Metal Precursor Comments c H N 41. 5 6.9 14. 2 extremely a i r 43. 9 6.9 15. 6 43. 6 6.9 15. 8 a i r stable 43. 7 6.9 15. 5 43. 8 6.7 15. 6 a i r stable 43. 7 6.9 15. 5 43. 2 6.8 15. 3 a i r stable 43. 4 6.8 15. 4 42. 7 6.4 16. 0 a i r sensitive 43. 3 6.8 15. 4 Fe Co Ni Cu Zn pale yellow FeCl 2'1.5 THF dark purple CoCl 2 I emerald green blue-green white Ni(BF.4) 2-6H 20 CuBr, ZnCl, - 14 -The monomeric u n i t s d i m e r i z e v i a a four membered -GaOGaO- r i n g and each g a l l i u m atom i s c o o r d i n a t e d i n a d i s t o r t e d t r i g o n a l b i p y r a m i d a l geometry. The importance o f the bulky methyl groups on the amino n i t r o g e n i s e x e m p l i f i e d by the r a t h e r long Ga-N o bond l e n g t h of 2.471 A. In the analogous g a l l a n e d e r i v a t i v e , [Me2GaCH2CH20'GaH_2] 2 f s t e r i c i n t e r a c t i o n s are much l e s s severe o and the Ga-N bond l e n g t h i s reduced c o n s i d e r a b l y t o 2.279 A (22). The r e a c t i o n of ethanolamine w i t h t r i m e t h y l g a l l i u m pro-duced a monomeric complex i n c o r p o r a t i n g a t e t r a h e d r a l l y c o o r d i n -ated g a l l i u m atom r a t h e r than a dimer i n c o r p o r a t i n g two f i v e c o o r d i n a t e g a l l i u m atoms. More i m p o r t a n t l y , the h y d r o x y l group was found to r e a c t p r e f e r e n t i a l l y , l e a v i n g the amino group i n t a c t . T h i s was not s u r p r i s i n g s i n c e N-H groups c o o r d i n a t e d t o g a l l i u m a l k y l s r e q u i r e e l e v a t e d temperatures t o e l i m i n a t e alkane whereas 0-H groups c o o r d i n a t e d t o g a l l i u m a l k y l s e l i m i n a t e alkane much more r a p i d l y a t lower temperatures (23). T h i s s e l e c t i v i t y paved the way f o r the s y n t h e s i s of c h e l a t i n g a n i o n i c g a l l a t e l i g a n d s i n c o r p o r a t i n g the u n s u b s t i t u t e d ethanolamino moiety. The c r y s t a l s t r u c t u r e of H2NCH 2CH 2 0 *GaMe2 i s shown i n F i g u r e 5 . The i n d i v i d u a l monomeric u n i t s are each l i n k e d t o four others" by an e x t e n s i v e network of N-H« ' » 0 hydrogen bonds. E v i d e n t l y , these bonds are q u i t e s t r o n g s i n c e fragments c o n t a i n -i n g two and t h r e e g a l l i u m atoms have been i d e n t i f i e d i n the mass spectrum of t h i s compound. (The h i g h e s t observed m/e due to a fragment c o n t a i n i n g one g a l l i u m atom corresponded t o l o s s of a methyl group from the monomer). Hydrogen bonding i s a l s o e v i d e n t i n the form of a very broad band i n the N-H s t r e t c h i n g r e g i o n of - 15 -F i g u r e 5. M o l e c u l a r s t r u c t u r e of H 2NCH 2CH 20•GaMe 2 the i n f r a r e d spectrum. Two 'conformations' o f the -CH 2CH 2~ group are found i n the c r y s t a l s t r u c t u r e . However, these do not remain r i g i d i n s o l u t i o n s i n c e o n l y one s i g n a l i s found f o r each CH 2 group i n the ^H nmr spectrum. The Ga-N bond d i s t a n c e i n t h i s complex was o 2.064 A - c o n s i d e r a b l y s h o r t e r than the cor r e s p o n d i n g bond l e n g t h i n [Me 2Ga•OCH 2CH 2NMe 2] 2 (2.471 A ) . 2.3.2 The O c t a h e d r a l Complexes, [Me2Ga (C-^ HN.,R_2)_ (OCH 2CH 2NH 2)] 2M (R = H, Me) The p r e p a r a t i o n of l i g a n d s i n c o r p o r a t i n g the 'OCH2CH2NH2' moiety r a t h e r than 'OCH2CH2NMe2' was expected t o reduce the s t e r i c requirements of the r e s u l t i n g l i g a n d s i g n i f i c a n t l y and t h i s e x p e c t a t i o n was r e a l i z e d by the i s o l a t i o n of monomeric o c t a h e d r a l complexes. The monomeric f o r m u l a t i o n o f these com-plexes was confirmed by t h e i r mass s p e c t r a . The spectrum of - 16 -[Me 2Ga(pz)(OCH 2CH 2NH 2)] 2Co l i s t e d i n Table I I I i s t y p i c a l of these complexes. The h i g h e s t observed m/e i s due to the parent i o n and the most i n t e n s e s i g n a l i s due to MeGa(pz) 2(OCH 2CH 2NH 2) Co +. Other s i g n a l s are due to l o s s o f p y r a z o l y l and e t h a n o l -amino groups from the parent i o n . In a d d i t i o n , the l o s s o f amino protons i s e v i d e n t i n s e v e r a l o f the observed peaks. • I n f r a r e d s t u d i e s showed t h a t two d i s t i n c t isomers of [Me 2Ga(pz)(OCH 2CH 2NH 2)] 2M are formed. In the case of M = N i , these two morphs were demonstrated by the i s o l a t i o n o f two d i f -f e r e n t c r y s t a l forms: p u r p l e cubes and blue prisms. The c r y s t a l s t r u c t u r e s o f these two compounds were determined by Dr. S. R e t t i g and are presented i n F i g u r e 6 (19). The p u r p l e cubes (a) (b) F i g u r e 6. M o l e c u l a r s t r u c t u r e s o f sym-fac (a) and mer (b) isomers of [Me-Ga(pz)(OCH-CH-NH-)]~Ni. - 17 -Table I I I . Mass spectrum of [Me2Ga(pz) (OCH2CH2NH2) ] 2Co * m/e int e n s i t y assignment 511 36.1 Me 4Ga 2(pz) (OCH 2CH 2NH 2) 2Co + 496 16.8 Me 3Ga 2(pz) 2(OCH 2CH 2NH 2) 2Co + 435 15.9 Me 3Ga 2(pz) (OCH2CH2NH)Co+ 428 61.1 Me 3Ga 2(pz) (OCH-2CH2NH2) (OCH2CH2NH) Co + 384 22.3 Me 4Ga 2(pz)(OCH 2CH 2NH 2)Co + 337 100.0 MeGa(pz) 2(OCH 2CH 2NH 2)Co + 335 12.5 MeGa(pz) 2(OCH 2CH 2N)Co + 330 18.6 MeGa(pz)(OCH 2CH 2NH 2) 2Co + 328 10.0 MeGa(pz)(OCH 2CH 2NH) 2Co + 285 8.1 Me 2Ga(pz)(OCH 2CH 2NH 2)Co + 144 32.7 MeGa(OCH 2CH 2NH 2) + 142 12.0 MeGa(OCH2CH2N)+ 99 11.5 Me 2Ga + 69 6.9 Ga + 68 33.1 (pzH) + 67 4.8 (pz) + * 69 calculated for Ga - 18 -Table IV. Some S t r u c t u r a l Parameters of sym-fac and mer [Me 2Ga(pz)(OCH 2CH 2NH 2] 2Ni o a) bond lengths (A) fa c isomer mer isomer Bond N i -0 N i -N(l) N i -N(3) unco r r . c o r r , Bond uncorr, c o r r . 2 .086(3) 2 .090 N i -0(1) 2 .042 (4) 2 .049 2 .083 (3) 2 .085 N i -N(l) 2 .086 (4) 2 .091 2 .108(3) 2 .112 N i -N'(3) 2 .142(5) 2 .148 N i -0(2) 2 .038 (3) 2 .045 N i -N(4) 2 .098(4) 2 .102 N i -N(6) 2 .152(5) 2 .156 b) bond angles fac isomer mer isomer Bonds Angle(deg) 0 -Ni -N(l) 88 .1(1) 0 -Ni -N(3) 83 • 0(1) N(l) -Ni -N(3) 90 .1(1) 0 -Ni -N(l) ' 91 • 9(1) 0 -Ni -N(3) ' 97 .0(1) N( l ) -Ni -N(3) ' 89 .9(1) Bonds Angle(deq) 0(1) -Ni -N(l) 85.8 (2) 0(1) -Ni -N(3) 80.9 (2) N(l ) -Ni -N(3) 166.2 (2) 0(1) -Ni -N(4) 95.3(2) 0(1) -Ni -N(6) 98.4 (2) N(l) -Ni -N(6) 88.6(2) N (1) -Ni -N(4) 93.7(2) 0(2) -Ni -N(4) 85.9 (2) 0(2) -Ni -N(6) 80.4 (2) N(4) -Ni -N(6) 166.2 (2) 0(2) -Ni -N(l) 93.4 (2) 0(2) -Ni -N(3) 99.7(2) N(4) -Ni -N(3) 91.3(2) N(3) -Ni -N(6) 89.5(2) 0(1) -Ni -0(2) 178.6(2) - 19 -were found to be the sym-fac isomer while the blue prisms were found to be the mer isomer. Both c r y s t a l structures consist of discrete molecules separated by normal Van der Waals distances with the nic k e l atom i n each isomer bonded to two tridentate [Me2Ga(pz) (OCH2CH2NH2)]" ligands. The two modes of coordination are related by a f o l d about the Ni-0 bond which forces a change of coordination geometry of the t r i v a l e n t oxygen atom from nearly planar i n the mer isomer to pyramidal i n the fac isomer. While the coordination geometry about the n i c k e l atom i s di s t o r t e d octahedral i n each case, the d i s t o r t i o n s from 'ideal' geometry are more severe for the asymmetric mer isomer than for the centro-symmetric sym-fac isomer. Table IV l i s t s the pertinent struc-t u r a l parameters. Conversion of one isomer to the other could be effected by suitable choice of solvent for r e c r y s t a l l i z a t i o n . The non-polar fac isomer (purple crystals) when dissolved i n acetone gave the polar mer isomer (blue crystals) on r e c r y s t a l l i z a t i o n . Converse-l y , the mer isomer dissolved i n benzene gave the fac isomer on r e c r y s t a l l i z a t i o n . Heating the fac isomer caused a colour change from purple to blue at ~ 130 C suggesting a rearrangement to the mer isomer. Continued heating caused decompos°ition at ~ 190 C. The blue mer isomer i t s e l f darkens and decomposes at ~ 190 C with no observable colour change below th i s temperature. No evidence for fac/mer isomerism has been found i n the remaining complexes and the assignment of mer or fac isomers for each metal i s based on infrared spectral evidence. Figure 7 i l l u s t r a t e s the two types of spectra observed for [Me 2Ga(pz) (OCH2CH2NH2)] 2M complexes. Differences i n the two spectra are - 21 -primarily i n the regions att r i b u t a b l e to N-H vibrations. In the sym-fac isomer, two bands are found i n the N-H stretching region at z 3300 cm 1 but at least three bands are observed for the mer isomer. In the N-H deformation region of the spectrum, ~ 1600 cm 1 , a single band i s observed for the mer isomer but a three band envelope i s observed for the fac isomer. A t h i r d finger-p r i n t region of the spectra occurs between 400 and 500 cm 1 . In the spectrum of the mer isomer, two bands occur close together at 460 and 475 cm 1 whereas i n the spectrum of the fac isomer, these bands are absent and two new bands occur at 400 and 500 cm - 1. The infrared spectra of the [Me2Ga (p z") (OCH2CH2NH2)] 2M complexes displayed three or four bands i n the N-H stretching region (~ 3300 cm x) and a single broad band i n the N-H deforma-t i o n region (~ 1600 cm x) of the spectrum. Based on t h i s e v i -dence, a meridional arrangement i s assigned to the gallate ligands i n these complexes. The e l e c t r o n i c spectra of the octahedral complexes were recorded i n the range 300-1400 nm and are l i s t e d and assigned i n Table V. The spectra of mer and fac [Me 2Ga(pz)(OCH 2CH 2NH 2)] 2 Ni are shown i n Figure 8. As expected, three spin allowed bands are observed for each complex. In addition, a much weaker band, 3 1 . . assignable to the A 2^ —> E^ t r a n s i t i o n , i s also observed. It i s obvious that the absorptions due to the mer isomer are s i g -n i f i c a n t l y more intense than those for the sym-fac isomer and t h i s i s probably due to the presence of a centre of symmetry i n the immediate ligand environment of the fac isomer. (Crystal - 22 -1000 WAVELENGTH (nm) 500 F i g u r e 8. E l e c t r o n i c spectrum of mer ( ) and fac ( ) [Me 2Ga(pz)(OCH 2CH 2NH 2)] 2Ni i n C 6H 6. s t r u c t u r e s have shown the mer isomer to be more d i s t o r t e d from ' i d e a l i z e d ' o c t a h e d r a l geometry than the fac isomer). The spectrum of [Me 2Ga(pz")(OCH 2CH 2NH 2)] 2Ni i s very s i m i l a r to t h a t of mer [Me 2Ga(pz)(OCH 2CH 2NH 2)] 2Ni (e's s l i g h t l y h i g h e r , p o s i t i o n s of bands s l i g h t l y red s h i f t e d ) . T h i s i s e n t i r e l y i n agreement w i t h the geometry suggested by i n f r a r e d evidence. The e l e c t r o n i c s p e c t r a of [Me 2Ga(pz)(OCH 2CH 2NH 2)] 2Co and [Me 2Ga(pz")(OCH 2CH 2NH 2)] 2Co e x h i b i t two main a b s o r p t i o n bands, assigned as and , with f i n e s t r u c t u r e on the more in t e n s e of these ( v ^ ) • The e l e c t r o n i c spectrum of [Me 2Ga(pz)(OCH 2CH 2NH 2)] 2Fe d i s p l a y s a very weak a b s o r p t i o n i n the i n f r a r e d r e g i o n . However, i t s p o s i t i o n i s p a r t i a l l y obscured by the presence of a very i n t e n s e charge t r a n s f e r band. A s i m i l a r charge t r a n s f e r band i n the spectrum o f [Me 2Ga(pz")(OCH 2CH 2NH 2)] 2 F e prevents the observation of any d-d t r a n s i t i o n s for t h i s complex. The n i c k e l and cobalt spectra have been analyzed on the basis of the energy lev e l s discussed i n r e f . 24. Dq and B values are l i s t e d i n Table V. The observed v 2 and bands of the n i c k e l complexes were used to calculate Dq and B. This led to calculated values of 10.9, 10.65 and 10.4 kK (cf. experimental 10.9, 10.0 and 9.5) for fac and mer [Me 2Ga(pz)(OCH 2CH 2NH 2)] 2Ni and [Me2Ga(pz") (OCH 2CH 2NH 2)] 2Ni, respectively. I t i s noteworthy that the ob-served bands for both mer compounds are red shifted with respect to the calculated value. This i s probably due to the same d i s t o r t i o n from ide a l i z e d octahedral symmetry i n both com-pounds. The expected > 1 e 0 t r a n s i t i o n s are 13.2, 13.4 and 13.1 kK, i n close agreement with the experimental values of 13.1, 13.1 and 12.9 kK (C/B = 4.5 has been assumed for t h i s c a l c u l a t i o n (24)). S i m i l a r l y , and were used to calculate Dq and B values for the cobalt complexes. This led to calculated v 2 values of 19.9 and 19.8 kK f or [Me2Ga (pz)(OCH 2CH 2NH 2)] 2Co and [Me2Ga(pz") (OCH2CH2NH2)] 2Co, respectively. In the l a t t e r complex, t h i s absorption i s observed as a weak shoulder at 19.8 kK. However, no corresponding absorption i s observed i n the former complex. (This absorption i s formally a 'two electron 1 t r a n s i t i o n and i s frequently obscured). The observed shoulder at 18.6 kK could be due to a spin forbidden band or a s p l i t t i n g 4 of the T i g ( p ) l e v e l . Comparison of the calculated spectral parameters with those of the c o r r e s p o n d i n g hexaamine complexes ( C o ( N H 3 ) g T ' Dq = 1020 cm" 1, B = 885 c m - 1 (24); N i ( N H 3 ) g + 2 : Dq = 1080 cm" 1, B = 900 c m - 1 (24); F e ( N H 3 ) 6 + 2 : Dq = 1120 cm" 1 (25)) shows t h a t the t r i d e n t a t e l i g a n d o c c u p i e s approximately the same p o s i t i o n as NH 3 i n the s p e c t r o c h e m i c a l s e r i e s . The B v a l u e s of the c h e l a t e complexes, however, are much lower i n d i c a t i n g a g r e a t e r degree of covalency i n these compounds. I t i s somewhat s u r p r i s i n g t h a t the Dq v a l u e s f o r the sub-s t i t u t e d p y r a z o l y l d e r i v a t i v e s are s l i g h t l y lower than.those f o r the u n s u b s t i t u t e d p y r a z o l y l d e r i v a t i v e s . The methyl s u b s t i t u e n t s on the p y r a z o l y l r i n g should i n c r e a s e the donor c a p a c i t y of the p y r a z o l y l n i t r o g e n atoms through an i n d u c t i v e e f f e c t . A l i k e l y e x p l a n a t i o n i s t h a t s t e r i c i n t e r a c t i o n s o f f s e t t h i s e f f e c t by p r e v e n t i n g c l o s e approach of t h i s l i g a t i n g n i t r o g e n to the cen-t r a l t r a n s i t i o n metal i o n . 2.3.3 The F i v e C o o r d i n a t e Complexes, rMe 2Ga(pz") (OCH 2CH 2NMe 2)]  M[(pz") 2 G a M e J Previous s t u d i e s have shown t h a t the l i g a n d , [Me 2Ga(pz) (OCH 2CH 2NMe 2)] , was not capable of forming ' b i s - l i g a n d ' com-ple x e s because of s t e r i c reasons (13,14). Consequently, i t was no s u r p r i s e t h a t the more s t e r i c a l l y demanding l i g a n d , [Me 2Ga (pz")(OCH 2CH 2NMe 2)] ~ a l s o c o u l d not form b i s - l i g a n d complexes. A n a l y t i c a l and mass s p e c t r a l data suggest t h a t f i v e c o o r d i n a t e mononuclear complexes of the g e n e r a l formula, [Me 2Ga(pz") (OCH 2CH 2NMe 2)] M Kpz") 2GaMe 2 ] are formed by the r e a c t i o n of t h i s l i g a n d w i t h d i v a l e n t t r a n s i t i o n metal i o n s . The h i g h e s t m/e - 25 -T a b l e V . E l e c t r o n i c S p e c t r a of R Me Energy (kK) e D (cm" ) B(cm ) assignment H F e a 12 .1 7 . 5 1210 5 T , 3 E 2g g H Co a 9 18 .4 .6 4 ~2 .3 1055 800 4 T l g ( F ) ^ S 2 g 20 .2 23 .2 Sg^ Me Co a 9 14 19 20 .2 .7(sh) .8(sh) .6 5 0 1 37 2 9 0 1050 850 4 4 T, (F) > *T-4 l g 2 2 g 2 T. (F) > , T. 4 4 2g' lt T. (F) 4 l g 4 2g T l g < F > - » T l g<P) H N i 3 10 9 3 6 1095 800 \ a — \ A->„ * E 3 2g , g JA T , ( F ) 3 2 5 3 l g A 2 g — T l g ( P ) (fac) 13 1 0 4 17 27 2 5 5 8 8 5 H N i b (mer) 10 13 0 1 9 0. 2 6 1065 810 3 A 2 g - * J T2g 3 2g 3 g 3A 2 g - 3 T l g < F ' A 2 g - * T l g ( P ) 16 27. 9 2 8. 16. 7 7 Me N i a 9. 12. 5 9 10. 0. 2 5 1035 790 3 2g 2 2g E g 3A 2 g - 3 T l g ^ ) A 2 g — Tlg< P> 16. 26. 5 5 10. 20. 5 5 Me N i b 9. 12. 5 9 10. 0. 7 5 1035 790 3 2g 2g 3 2g 3 g 3A 2 g ^ T l g < F )  A 2 g ^ Tlg< P> 16. 5 9. 7 26. 5 18. 7 H Cu a 16. 5 130 1650 g 2g measured i n benzene measured i n acetone - 26 -observed i n the mass spectra of these complexes can be assigned to P + or P-Me+ and the most intense signal i n the majority of the spectra was due to [MeGa (pz") 2 (OCH^H^Nr^) M ] + . The one exception was the Cu complex which displayed the ion, [MeGa(pz") (OCH^jCH^NMe^ Cu] + as i t s strongest s i g n a l . This ion was not present i n the fragmentation patterns of the remaining f i v e co-ordinate complexes. The ele c t r o n i c spectra of the N i , Co, and Cu complexes are presented i n Figure 9 and assigned i n Table VI. Table VI. El e c t r o n i c spectra of [Me2Ga (pz") (OCH2CH2NMe2)] M [(pz") 2GaMe 2l* M Energy(kK) E Ni 7.4 15 11.3 30 12.4 24 14.9 35 20.6(sh) — 24.2 130 CO 7.3 9 9.6 15 13.7 13 17.6 198 19.8(sh) -20.7(sh) -Cu 13.5 135 9.0(sh) Assignment 3E ' >3E " (F) 3 3 3 E'—*- 3A 1" , A 2" 3 E ' — » 3 A 2 ' (F) 3 E ' - ^ 3 E " (P)+ 3A 2' (P) i A * • 2 i A ' • A A2 *E" V 4A 2'(P) 4 E " (P) 2A, '—^ 2E(1)+ 2E(2) * benzene solutions, sh = shoulder 20 25 FREQUENCY (kK) Figure 9. E l e c t r o n i c spectra of [Me 2Ga(pz")(OCH 2CH 2NMe 2)] M [ (pz") 2GaMe2] M = Ni ( ), Co ( ), and. Cu(•••) in C6Hg. The n i c k e l spectrum was assigned on the basis of the c r y s t a l f i e l d model discussed by Ciampolini (26) . With the exception of the s p l i t t i n g of one band, the spectrum can be i n -terpreted i n terms of a trigonal bipyramidal model. The s p l i t -t i n g of the band around 11.5 kK into two components indicates a reduction of symmetry from idea l i z e d on which the model i s based. Reduction to C^v symmetry would give two bands as trans-3 3 l t i o n s to A 1(F) and A 9(F) instead of degenerate tr a n s i t i o n s to A^" + A 2 " i n symmetry. The spectrum of the present compound i s almost i d e n t i c a l to that of [Ni (trenMe) CI] + where trenMe = tris(2-dimethylaminoethyl)amine (27), the bromo analog of which has been shown by x-ray crystallography to possess C^v microsymmetry (28). The only notable difference i n the present spectrum i s the s h i f t of a l l the bands to higher energy (NiN^O chromophore vs NiN^Cl chromophore). The o v e r a l l shape of the cobalt spectrum did not f i t ligand f i e l d models for either t r i g o n a l bipyramidal or square pyramidal geometries. This i s probably due to severe d i s t o r t i o n s from these i d e a l i z e d geometries. Indeed, i t i s well known that t r i g o n a l bipyramidal cobalt(II) complexes are commonly more distorted toward the tetrahedron than t h e i r Ni(II) analogs (29). Nevertheless, the band positions for the present complex corre-late c l o s e l y with those of the complex, [Co (NP_.) Br ] +PF ~, where NP^ = tris(2-diphenylphosphinoethyl)amine, which has been shown by x-ray crystallography to possess an extremely d i s t o r t e d t r i g -onal bipyramidal geometry (30). The assignment of bands i n Table VI i s based on the ligand f i e l d model proposed by Wood (31) for i d e a l i z e d high spin t r i g o n a l bipyramidal Co(II) complex-4 4 es. The expected single t r a n s i t i o n '—> E" i s replaced by a complex band envelope, no doubt due to the aforementioned d i s -tortions from the ide a l i z e d geometry. The spectrum of the copper complex shows e s s e n t i a l l y one band with a shoulder to lower energy. Although other geometries are possible, t h i s spectrum i s e n t i r e l y compatible with a t r i -gonal bipyramidal chromophore (27). - 29 -The i n f r a r e d s p e c t r a o f the f i v e c o o r d i n a t e complexes f e l l i n t o two g r o u p s . The F e , N i , and Zn complexes formed one group w h i l e t h e Co and Cu complexes formed a second g r o u p . Both groups gave i r s p e c t r a w h i c h were v e r y s i m i l a r i n t h e r e g i o n 4000-1600 c m " 1 , b u t m a r k e d l y d i f f e r e n t i n the r e g i o n 1600-400 cm 1 (see F i g . 1 0 ) . These d i f f e r e n c e s p r o b a b l y i n d i c a t e t h a t t h e r e a r e a t l e a s t two d i f f e r e n t m o l e c u l a r g e o m e t r i e s adopted by t h e s e c o m p l e x e s , a f a c t s u g g e s t e d by t h e e l e c t r o n i c s p e c t r a . 1 II,/Il J i 1lf P f i i f i \ 1 1 (1 A \ i F i g u r e 10. I r s p e c t r a o f [ M e 2 G a ( p z " ) ( O C H 2 C H 2 N M e 2 ) ] M [ ( p z " ) 2 GaMe 2 ] M = F e , N i , Zn ( u p p e r ) ; M = C o , Cu (lower) i n N u j o l . - 30 -An x - r a y s t r u c t u r e of t h e n i c k e l complex (done by D r . S. R e t t i g ) shows the n i c k e l atom t o p o s s e s s a d i s t o r t e d t r i g o n a l b i p y r a m i d a l geometry ( F i g . 1 1 ) . The t r i d e n t a t e [Me 2 Ga(pz" ) ( O C H 2 C H 2 N M e 2 ) ] i s m e r i d i o n a l l y c o o r d i n a t e d w i t h t h e oxygen atom o c c u p y i n g an e q u a t o r i a l p o s i t i o n and the two n i t r o g e n atoms o c -c u p y i n g a x i a l p o s i t i o n s . The two r e m a i n i n g e q u a t o r i a l p o s i t i o n s a r e o c c u p i e d by the two n i t r o g e n donors o f the [ M e 2 G a ( p z " ) ^ ] ~ l i g a n d . T a b l e V I I l i s t s some i m p o r t a n t s t r u c t u r a l p a r a m e t e r s . The e q u a t o r i a l N i - N bond d i s t a n c e s (2.006(3) and 2.005(3) A) are e q u a l w i t h i n e x p e r i m e n t a l e r r o r and a r e b o t h s i g n i f i c a n t l y l o n g e r than the mean N i - N d i s t a n c e o f 1.895(4) A i n the square p l a n a r complex [ M e 2 G a ( p z ) 2 l 2 N i (32) . The N i - O , N i - N ( p z " ) and N i - N (amino) d i s t a n c e s i n v o l v i n g the t r i d e n t a t e l i g a n d are 1 . 9 9 3 ( 3 ) , 2.072(3) and 2.229(3) A . cnei C(2) CC22A) 0 , 2 1 1 C(20) F i g u r e 11 . M o l e c u l a r s t r u c t u r e of [Me 2 Ga(pz") ( O C H 2 C H 2 N M e 2 ) ] N i [ ( p z " ) 2 G a M e 2 ] . - 31 -Table VII. Some Structural Parameters of [Me2Ga(pz") (OCH 2CH 2NMe 2)lNi [(pz") 2GaMe 2] a) bond lengths (A) b) bond angles Bond uncorr. corr. Bonds Angle(deg) Ni -0 1.989(3) 1.993 0 -Ni -N(2) 126.3(1) Ni -N(2) 2.000 (3) 2.006 0 -Ni -N(4) 131.1(1) 0 -Ni -N(6) 85.4(1) Ni -N(4) 2.001(3) 2.005 0 -Ni -N(7) 79.5(1) Ni -N(6) 2.068(3) 2.072 N(2) -Ni -N(4) 102. 3 (1) N(2) -Ni -N(6) 95.6(1) Ni -N(7) 2.227(3) 2.229 N(2) . -Ni -N(7) 94.5(1) N(4) -Ni -N(6) 95.3 (1) N(4) -Ni -N(7) 93.5(1) N(6) -Ni . -N(7) 164.8 (1) These may be compared to the corresponding distances of 2.047(2), 2.097(6) and 2.152(4) A i n octahedral mer-[Me 2Ga(pz)(OCH 2CH 2NH 2)] 2 Ni. It i s clear that the methyl groups on the amino nitrogen tend to lengthen the metal nitrogen (amino) bond ( r e l a t i v e to the metal nitrogen bond of the unsubstituted ligand). 2.4 Summary The nature of the complexes formed by the reaction of the ga l l a t e ligands, [Me2Ga (C-jHN^) (OCH2CH2NR'2)] ~, with divalent t r a n s i t i o n metal ions i s determined by s t e r i c factors. When R = H, Me and R' = H, the expected monomeric bis- l i g a n d octa-hedral complexes are i s o l a t e d . However., when R' = Me, the form-ation of octahedral complexes i s prevented by mutual s t e r i c interactions between the dimethyl amino moieties. Moreover, the i s o l a t e d product i s dependent on R. The following equations represent the o v e r a l l reactions -when R' = Me: - 32 -,+2 k [Me 2Ga(pz) 2(OCH 2CH 2NMe 2)M] 2 + 2Na + + Js[Me2Ga-OCH2CH2NMe2] 2 (9) + M ,+2 [Me 2Ga(pz")(OCH 2CH 2NMe 2)]M[(pz") 2GaMe 2] + Na +[Me 2Ga(OCH 2CH 2NMe 2) 2]~ + 2Na + (10) In the former case, the 'side product' [Me 2Ga•OCH 2CH 2NMe 2] 2 was isolat e d as a white powder and i d e n t i f i e d by i t s mass spectrum and i n the l a t t e r case, the side product, [Me 2Ga(OCH 2CH 2NMe 2) 2]~ i s assumed on the basis of stoichiometry and s o l u b i l i t y . Unlike previously studied uninegative tridentate ligands (viz n^-C 5H 5 , HB(pz) 3 / and MeGa(pz) 3 ) which can only coordin-ate f a c i a l l y , the present ligands can coordinate either f a c i a l l y or meridionally. This v e r s a t i l i t y allowed the i s o l a t i o n of mer and fac L^M. (R' = H) octahedral complexes and i s exemplified by the interconversion of mer and fac - [Me 2Ga(pz)(OCH 2CH 2NH 2)] 2Ni. The f a c t that only meridional coordination i s found i n the b i -nuclear f i v e coordinate complexes (R = H, R' = Me) and the tri g o n a l bipyramidal f i v e coordinate complexes (R = Me, R' = Me) indicate that t h i s i s the e l e c t r o n i c a l l y favored conformation or that s t e r i c factors prevent f a c i a l coordination of the ligand. I t i s reasonable to expect that i n any p a r t i c u l a r complex where s t e r i c factors do not intervene, e l e c t r o n i c e f f e c t s w i l l deter-mine the coordinating mode (fac or mer) of these ligands. - 33 -CHAPTER I I I CARBONYL DERIVATIVES OF Mn,'Cr, Mo and W 3.1 I n t r o d u c t i o n I t has a l r e a d y been shown t h a t t h e r e i s a c l o s e p a r a l l e l between the chemistry of the t r i s p y r a z o l y l b o r a t e i o n , [RBCpz)^] and the c y c l o p e n t a d i e n y l i o n , Cp (5,6). For example, both Cp and [RB(pz).j] r e a c t w i t h Gp VI hexacarbonyls t o produce the r e s p e c t i v e ions CpM(CO) 3~ and [RB (pz)3]M(CO) 3 ~ (M = Cr,Mo,W) and n e u t r a l d e r i v a t i v e s of the gen e r a l formula DM(CO) 2T (where D = n5-c,-H,- or R B ( p z ) 3 and T = ' t h r e e - e l e c t r o n n e u t r a l l i g a n d ' ) can be obtained by r e a c t i o n of the a p p r o p r i a t e Mo or W c a r b o n y l anion w i t h v a r i o u s e l e c t r o p h i l e s . For example, I T - a l l y 1 d e r i v a -t i v e s are produced by r e a c t i o n w i t h a l l y l i c h a l i d e s (33,34), 3 n -C^H^ d e r i v a t i v e s by r e a c t i o n with the tropenium i o n (33,35), and a r y l d i a z o d e r i v a t i v e s are produced by r e a c t i o n with A r N 2 + (36,37). One noteworthy d i f f e r e n c e was t h a t w i t h the c y c l o -p e n t a d i e n y l system, the r e a c t i o n w i t h a l l y l h a l i d e s i n i t i a l l y produced a a - a l l y l s p e c i e s , whereas i n the p y r a z o l y l b o r a t e system the T T - a l l y l s p e c i e s was i s o l a t e d d i r e c t l y . The anion, [MeGa(pz) 3]Mo(CO) 3 , behaves very s i m i l a r l y to i t s boron analogue (11) . However, the s u b s t i t u t e d anion, [MeGa(pz") 3]Mo(CO) 3~, undergoes some anomalous r e a c t i o n s . As with [RB(pz) 3]Mo(CO) 3 " and [RB (pz" ) 3 ] Mo (CO) 3 ~ , [MeGa (pz) 3 ] Mo (CO) 3 r e a c t s with 'N0+' to gi v e the 'Mo(CO)2NO' d e r i v a t i v e . However, i n attempts t o prepare a l l y l i c d e r i v a t i v e s , compounds of the gen e r a l formula, [MeGa(pz")~(OH)]Mo(CO)_'allyl' were i s o l a t e d - 34 -(12) . T h i s ' t r a n s f o r m a t i o n ' i s b e l i e v e d to o c c u r as a r e s u l t o f s t e r i c c rowding and has n o t been o b s e r v e d i n any boron s y s t e m s . W i t h the i n c o r p o r a t i o n o f the l i g a n d s , L , the r e s u l t i n g c a r b o n y l a n i o n s , LM(CO)^ were expec ted to e x h i b i t s i m i l a r d e r i v a t i v e c h e m i s t r y . However, the c a p a b i l i t y of the g a l l a t e l i g a n d s t o c o o r d i n a t e e i t h e r m e r i d i o n a l l y or f a c i a l l y was expec ted to produce some i m p o r t a n t d i f f e r e n c e s . M o r e o v e r , the asymmetric n a t u r e o f the l i g a n d i n t r o d u c e s s t e r e o c h e m i c a l i m p l i -c a t i o n s which were not e n c o u n t e r e d i n the p r e v i o u s l y d i s c u s s e d s y s t e m s . T h i s c h a p t e r d e t a i l s the p r e p a r a t i o n of the a n i o n s , LM(CO)^ (M = C r , M o and W) and a g e n e r a l i n v e s t i g a t i o n o f t h e i r d e r i v a t i v e c h e m i s t r y . I n a d d i t i o n , the compounds L M n ( C O ) 3 a re d e s c r i b e d . P a r t s o f t h i s work have been p u b l i s h e d p r e v i o u s l y (38 ,39 ) . 3.2 E x p e r i m e n t a l 3 . 2 . 1 S t a r t i n g M a t e r i a l s C r ( C O ) , . , Mo (CO) , and W(CO), were o b t a i n e d from Strem D O D C h e m i c a l s and used as s u p p l i e d . Mn(CO)^Br was p r e p a r e d by t r e a t m e n t of manganese d e c a c a r b o n y l w i t h bromine (40) and (CH^CN) M ( C O ) 3 ( M = Mo, W) were p r e p a r e d by r e f l u x i n g the a p p r o p r i a t e meta l h e x a c a r b o n y l i n a c e t o n i t r i l e (41) . ( p y ) 3 C r ( C O ) 3 (42) , C 7 H 7 M o ( C O ) 2 I (43) and C 7 H 7 W ( C O ) 2 I (44) were p r e p a r e d by l i t e r a -t u r e methods. C 7 H 7 + B F 4 was p r e p a r e d by the method of Dauben (45) . A l l y l bromide ( F i s h e r S c i e n t i f i c C o . ) and m e t h a l l y l - 35 -chloride (Eastman Kodak Co.) were d i s t i l l e d p r i o r to use. Iso-amyl n i t r i t e (Matheson, Coleman and Bell) , N-methyl-N-nitroso p-toluenesulphonamide (Diazald) (Aldrich Chem. Co.) and t e t r a -ethyl ammonium chloride (Eastman Kodak Co.) were used as supplied. Chloromethyl methyl sulphide was prepared from dimethyl sulfoxide and thionyl chloride (46) and benzenediazonium tetrafluoroborate was prepared by a standard method (47). 3.2.2 Preparation of LMn(CO)3 4- — m u p Mn(CO) 5Br + Na L > LMn (CO) _ + NaBr + 2C0 (11) reflux One aliquot of ligand (2.0 mmol) was mixed with an equi-molar amount of manganese pentacarbonyl- bromide i n THF (~ 100 ml) and the reaction mixture refluxed. Evolution of a gas was observed and gradually the colour of the solution changed from orange to yellow with concomitant formation of a white p r e c i p i -tate. After 16 h, solvent was removed i n vacuo and the r e s u l t -ant o i l y residue extracted with benzene and f i l t e r e d . Slow evaporation of the f i l t r a t e gave large orange c r y s t a l s of the product. Y i e l d was 50-60%. Physical data are l i s t e d i n Table VIII. 3.2.3 Preparation of N a + L M ( C O ) ( M = Cr, Mo, W) M = Mo, W - Method 1: M(CO), + Na L ii±£_> Na LM(CO) + 3CO (12) b reflux 3 Table VIII. Physical Data for Mefia Mn -co Found(%)/Calcd.(%) 1H nmr T(ppm) a IR(cm _ 1) b R R' C H N R R' H4 GaMe H H 32.7 32.8 4.1 4.1 11.7 11.5 2.46br 2.69br 3.80br 9.84s 10.2 8s 2032, *• -v' 1937, 1911 H Me 36.6 36.6 5.0 4.9 10.7 10.7 2.32d+ 2.66d+ 7.91s 8.70 3.79t + 9.88s 10.21s 2027, 1936, 1908 i Me H 36.7 36.6 4.7 4.9 10.7 10.7 7.70s 7.95s 4.23s 9.72s 10.09s 2030, 1936, 1907 CO (Tl 1 Me Me 39.8 5.5 9.9 7.63s 39.9 5.5 10.0 7.93s 7.83s 4.19s 9.86s 2024, 1934, 1902 8.38s 10.14s measured i n C gD 6, br = broad, s = sin g l e t , d = doublet, t = t r i p l e t measured i n cyclohexane 2 Hz - 37 -An equimolar amount of ligand and the appropriate metal hexacarbonyl (2.0 mmol) were mixed i n THF (100 ml) and the resultant mixture heated to ref l u x . The colour of the solution gradually changed from pale yellow to yellow orange with con-comitant evolution of a gas. Completion of reaction was signaled by the cessation of gas evolution. This reaction was complete after 24-48 h for molybdenum and 72-100 h for tungsten, depend-ing on the number of substituents on L. The unsubstituted ligand (R=R'=H) required the shortest reaction time, while the f u l l y substituted ligand (R=R'=Me) required the longest reaction time. M = Mo, W - Method 2: (CH-CN) ,M(CO) , + Na +L~ THF or CH 3CN > N a + L M ( C O ) ~ + 3CH-.CN (13) One aliquot of Na +L i n THF (10 ml) was added to an equi-molar amount of (CH^CN)3M(CO)3 (2.0 mmol) i n the same solvent and the resultant yellow-orange solution s t i r r e d . In the case of molybdenum, the reaction was complete a f t e r 30 min at r t and in the case of tungsten, the reaction was complete a f t e r 30 min at reflux. M = Cr: (py) 3Cr(CO) 3 + Na +L~ - S l > Na +LCr (CO) 3 ~ + 3py (14) To (py) 3Cr(CO) 3 (2.0 mmol) dissolved i n THF (~ 50 ml) was added an equimolar amount of Na +L i n THF (10 ml). The colour of the solution immediately changed from dark red to orange and the solution was s t i r r e d for 15 minutes to ensure completion of - 38 -reaction. In general, these extremely a i r sensitive sodium s a l t s of the anions were not i s o l a t e d from solution. Instead, the freshly prepared solutions were used i n further reactions. 3.2.4 Preparation of Et^N*[Me 2Ga(pz") (OCH2CH2NMe2)] M(CO) 3~ M = (Cr, Mo, W) Na +[Me 2Ga(pz") (OCH2CH2NMe2)] M(CO) 3 ~ + E t 4 N + C l ~ T H F > Et 4N +[Me 2Ga(pz")(OCH 2CH 2NMe 2)]M(CO) 3~ + NaCl (15) The s a l t , Na +[Me 2Ga(pz") (OCH 2CH 2NMe 2)]M(CO) 3~ was prepared as above (3.2.3) i n THF and an equimolar amount of E t 4 N + C l ~ dissolved i n a minimum amount (~ 5 ml) of MeOH was added. Forma-tion of a p r e c i p i t a t e was immediate. After 5-10 minutes, the mixture was f i l t e r e d and the solvent was removed from the f i l t r a t e i n vacuo. The resultant s o l i d was r e c r y s t a l l i z e d from THF to give c r y s t a l s of the product. Cr: golden yellow plates, y i e l d 35%; Mo: l i g h t yellow needles, y i e l d 55%; W: lemon yellow needles, y i e l d 6 0%. Physical data for these complexes are presented i n Table IX. 3.2.5 Preparation of LM(CO)2NO (M = Mo, W) Na +LM(CO) 3~ +'NO+' _™E> LM(CO)2NO + CO + (16) To Na +LM(CO) 3 (2.0 mmol) i n THF was added either an equi-molar amount of Diazald (N-methyl-N-nitroso-p-toluenesulphon-amide) or an excess of isoamyl n i t r i t e . In both cases, evolution Table IX. Physical Data for Et«N * Found(%)/Calcd.(%) -^H nmr T (ppm) * IR(cm - 1) M C H N Ga-Me N-Me pz-Me H4 Et 4N V CO Cr 49. 2 8.4 9.8 10.63s 7.46s 7.70s 4.60s 8.92br 1880, 1720 a (.5 THF) 49. 2 8.1 9.6 10.74s 8.16s 8.14s 6.63br 1881, 1729 b Mo 45. 1 7.5 8.8 10.62s 7.35s 7.74s 4.52s 8.84br 1878, 1705 a (.25 THF) 45. 2 7.4 9.2 10.65s 8.04s 8.09s 6.64br 1879, 1730 b W 39. 8 6.6 7.8 10.62s 7.30s 7.69s 4.46s 8.81tt C 1870, 170 0 a (.25 THF) 39. 5 6.5 8.0 10.59s 8 .00s 8.06s 6.72q 1873, 1725 b low temperature l i m i t i n g spectrum i n d g-acetone, br = broad, s = singlet, t = t r i p l e t , q = quartet a measured as nujol mulls measured as CH 2C1 2 solutions ° JN-CH 3 = 1 H Z ' JCH-CH = 7 H z - 40 -of a gas was rapid. After, s t i r r i n g for 1 h, the orange solution was stripped of solvent and the o i l y residue extracted with benzene (= 20 ml). F i l t r a t i o n followed by evaporation of the f i l t r a t e gave large orange c r y s t a l s of the product. Yields were ~ 15% using isoamyl n i t r i t e and ~ 70% using Diazald. A n a l y t i c a l and selected i r data are tabulated i n Table X. 3.2.6 Preparation of LM(CO) 2 (N 2Ph) (M = Mo, W) Na +LM(CO) 3~ + PhN 2 +BF 4~ -^3—> LM (CO) 2 (N 2Ph) + Na +BF 4~ + CO (17) A solution of Na +LM(CO) 3 , prepared i n a c e t o n i t r i l e , was cooled to -4 0°C, and an equimolar amount of s o l i d P h N 2 + B F 4 added. Immediately, the colour of the solution changed from yellow to dark red and a gas was evolved. After s t i r r i n g for 1 h at 0°C, solvent was removed i n vacuo and the resultant dark red s o l i d extracted with several portions of petroleum ether (b.p. 65-110°C, t o t a l volume = 100 ml). The extracts were f i l t e r e d and solvent removed from the f i l t r a t e . The resultant dark red c r y s t a l s were washed sparingly with heptane. Y i e l d : ~ 40%. A n a l y t i c a l and selected i r data are tabulated i n Table XI. 3 . 2 . 7 Preparation of LM(CO) 2'allyl', (M = Mo, W ; ' a l l y l ' = Method 1: Na +LM(CO) 3~ + ' a l l y l ' X -^5F-> LM(CO) 2 ' a l l y l ' + NaX + CO (18) Table X. A n a l y t i c a l and IR Data for Mefia Analysis -1 * IR(cm ) M R R' Calculated(%) C H N Found(%) C H N VCO VNO Mo H H 26.4 3.7 13.7 27.0 3.6 13.6 2020, 1920 1645 Mo H Me 30.2 4.4 12.8 30.6 4.4 12.6 2020, 1920 1647 Mo Me H 30.2 4.4 12.8 30.4 4.3 12.8 2018, 1918 1640 Mo Me Me 33.6 5.0 12.1 33.5 4.8 12.2 2015, 1917 1644 W H H 21.8 3.0 11.3 22.2 3.0 11.5 2001, 1898 1627 W H Me 25.2 3.6 10.7 25.9 3.7 10.3 1998, 1894 1626 W Me H 25.2 3.6 10.7 25.6 3.6 10.6 2000, 1898 1625 W Me Me 28.2 4.2 10.1 28.4 4.1 9.8 1997, 1895 1622 I * measured in CH 2C1 2 solution Table XI. A n a l y t i c a l and IR Data for M R R' Calculated(%) Found(%) V Co(cm~ h C H N C H N C6 H12 Mo H H 37.2 4.2 14. 5 37.1 4.3 14. 5 '2003, 1919, 1902 Mo Me H 39.9 4.7 13. 7 40.4 4.9 13. 6 2001, 1915, 1900 Mo H Me 39.9 4.7 13. 7 39.1 4.5 13. 6 2000, 1915, 1899 Mo Me Me 42.3 5.2 13. 0 42.6 5.0 12. 5 1996, 1914, 1892 W H H 31.5 3.5 12. 2 31.5 3.6 12. 2 1992, 1901, 1887 W Me H 34.0 4.0 11. 7 33.6 4.1 11. 8 1987, 1899, 1882 W H Me 34.0 4.0 11. 7 34.3 4.2 11. 7 1988, 1898, 1883 W Me Me 36.3 4.5 11. 2 36.3 4.4 11. 0 1983, 1896, 1877 - 43 -Excess a l l y l bromide or methallyl chloride (~ 1 ml) was added to a THF solution of Na +LM(CO) 3~ (2 mmol) and the r e s u l t -ant clear solution s t i r r e d at r t ( a l l y l bromide) or warmed gently (methallyl c h l o r i d e ) . After 1 h, the THF solvent was removed i n vacuo and the resultant o i l y residue extracted with benzene. F i l t r a t i o n followed by slow evaporation of the f i l t r a t e gave large orange to orange-brown c r y s t a l s of the product. Yields were = 50%. Method 2: (CH3CN) 3M(CO) 3 + ' a l l y l ' X -±fi£» (CH3CN) 2M (CO) 2 ' a l l y l ' X + CO + CH3CN (19) (CH3CN) 2M(CO) 2 a l l y l ' X + Na +L~ _ ™ I > LM (CO) 1 a l l y l ' + NaX + 2CH3CN (20) Excess a l l y l bromide or methallyl chloride (~ 1 ml) was added to a s t i r r e d solution of (CH 3CN) 3M(CO) 3 (2.0 mmol) i n THF (z 100 ml). Gas evolution was observed and the colour of the solution changed from yellow to orange. After cessation of gas evolution (30 min), a THF solution of Na +L (2.0 mmol) was added and aft e r s t i r r i n g for 1 h, the THF solvent was removed i n vacuo and the residue extracted with benzene. F i l t r a t i o n of the extracts, followed by slow evaporation 'of the f i l t r a t e gave the product i n ~ 50% y i e l d . These compounds were i d e n t i c a l to those prepared by Method 1. A n a l y t i c a l and selected i r data are l i s t -ed i n Table XII. T a b l e X I I . A n a l y t i c a l and IR Data f o r C a l c u l a t e d ( % ) Found(%) v c o ( c m - l ) * M R R' R" C H N C H N C y c l o h e x a n e C H 2 C l 2 Mo H H H 34.3 4.8 10.0 34.4 4.8 9.9 1938, 1850 1928, 1832 Mo H H Me 36.0 5.1 9.7 36.2 5.0 9.6 ( 1 9 3 8 v s , { 1 9 5 6 s , 11966m, 1851vs 1842s 1864m 1930, 1835 Mo Me H H 37.5 5.4 9.4 37.6 5.5 9.4 1935, 1847 Mo Me H Me 39.0 5.7 9.1 39.2 5.6 9.3 1933, 1840 Mo H Me H 37.5 5.4 9.4 37.8 5.6 9.4 19 34, 1848 Mo H Me Me 39.0 5.7 9.1 38.9 5.6 9.3 1929, 1841 Mo Me Me H 40.4 5.9 8.8 40.2 6.1 9.1 1931, 1843 Mo Me Me Me 41.7 6.2 8.6 41.6 6.2 8.8 1928, 1838 W H H H 28.4 4.0 8.3 28.5 3.9 8.3 i 1916, 1816 W H H Me 29.9 4.2 8.1 29.8 4.1 8.1 J1928m, ( 1945w, 1836m 1854w 1918, 1817 W Me H H 31.4 4.5 7.8 31.5 4.5 7.7 1929 , 1835 1916, 1813 W Me H Me 32.8 4.8 7.6 32.9 5.0 7.4 1927, 1832 1913, 1913 W H Me H 31.4 4.5 7.8 31.4 4.5 8.0 1926, 1835 1916, 1814 W H Me Me 32.8 4.8 7.6 32.7 4.8 7.9 1922, 18 31 1909, 1809 w Me Me H 34.1 5.0 7.5 33.8 4.9 7.3 1924, 1832 1911, 1810 v s = v e r y s t r o n g , s = s t r o n g , m = medium, w = weak, i = i n s o l u b l e - 45 -3.2.8 P r e p a r a t i o n o f LM(CO) 2(C ?H ?) (M = Mo, W) Method 1: Na +LM(CO) 3~ + C 7 H ? + B F 4 ~ -™L> LM ( co) 2C 7H 7 + CO + NaBF^ (21) To a s o l u t i o n of Na +LM(CO) 3~ (2.0 mmol) i n THF was added s o l i d C 7 H 7 + B F 4 . Immediately, the c o l o u r of the s o l u t i o n changed from y e l l o w t o orange-brown and e v o l u t i o n of a gas was observed. A f t e r 2 h, s o l v e n t was removed i n vacuo and the r e s u l t a n t o i l y brown s o l i d was r e c r y s t a l l i z e d from benzene. Y i e l d was 10-15%. Method 2: C ?H 7M(CO) 2I + Na +L~ b e n z e n e / T H F > LM(CO) 2C 7H ? + Nal (22) To a suspension of C 7H 7M(CO) 2I (2.0 mmol) i n benzene (50 ml) was added Na +L (2.0 mmol) i n THF (10 ml) over a p e r i o d of 1-2 days, the c o l o u r of the mixture changed from dark green to red brown and a white p r e c i p i t a t e formed. A f t e r f i l t e r i n g , the s o l v e n t was removed i n vacuo and the remaining red-brown s o l i d r e c r y s t a l l i z e d from benzene. Y i e l d s were 50-70%. Analy-t i c a l and i r data f o r these complexes are l i s t e d i n Tab l e X I I I . 3.2.9 R e a c t i o n of [Me 2Ga (pz") (OCH 2CH 2Me 2)] Mo (CO) (n3-C-,H?) with Fe (CO) 5 [Me 2Ga(pz") (OCH 2CH 2NMe 2)]Mo(CO) 2 (n 3-C 7H ?) (0.20 g) was d i s s o l v e d i n ~ 250 ml et h e r i n a quartz apparatus equipped with a water c o o l e d j a c k e t and 20 ml of Fe(CO)^ was added. A f t e r degassing w i t h N,, the s o l u t i o n was i r r a d i a t e d with a 450 watt Table X I I I . A n a l y t i c a l and IR Data f o r Me/Sa' C a l c u l a t e d ( % ) Found (%) v r o(cm* .1 M R R' C H N C H N CH? Clo C f iH 1 9 * Mo H H 44.8 5.0 8.2 44. 7 5.1 8.2 1840, 1925 1858, 1875, 1935vs 1956m Mo Me H 43.4 5.2 8.4 43. 9 5.4 8.3 1835, 1922 1855, 1932 Mo H Me 43.4 5.2 8.4 42. 6 5.0 8.3 1835, 1918 1853, 1929 Mo Me Me 45.7 5.8 8.0 45. 3 5.8 7.9 1834, 1919 1849, 1928 * W H H 38.2 4.2 7.0 38. 5 4.3 7.1 1827, 1915 i W Me H 36 .9 4.4 7.2 37. 2 4.6 7.2 1822, 1914 i w H Me 36.9 4.4 7.2 36. 5 4.5 7.3 1825, 1913 1846, 1925 w Me Me 39.1 4.9 6.8 39. 1 5.0 6.8 1821, 1912 1841, 1923 c r y s t a l l i z e d w i t h .5 mole CgH g vs = very s t r o n g , m = medium, i = i n s o l u b l e - 47 -H a n o v i a Model Q u a r t z lamp f o r 16 h t h r o u g h a pyrex f i l t e r . The r e s u l t a n t s o l u t i o n was s t r i p p e d o f s o l v e n t , the r e s i d u e e x t r a c t e d w i t h benzene and the m i x t u r e f i l t e r e d . The f i l t r a t e was then chromatographed on a F l o r i s i l c o l u m n . E l u t i o n w i t h heptane gave a y e l l o w band w h i c h on e v a p o r a t i o n gave 0.02 g o f a y e l l o w s o l i d . A n a l . C a l c d . f o r [ C ^ F e (CO) ] : C , 5 2 . 0 ; H , 3 .10 . F o u n d : C , 5 2 . 7 ; H , 3 . 3 . v C Q ( c m - 1 , c y c i o h e x a n e ) : 2046, 1984, 1973 •""H nmr ( t , C g D 6 ) : 7.56 (m,3H); 5.35 (m,3H); 4.49 (td (J = 12, 1 H z ) , I H ) . E l u t i o n w i t h t o l u e n e f o l l o w e d by C I ^ C ^ gave a brown band w h i c h on e v a p o r a t i o n gave a brown o i l . T h i s p r o d u c t was not i n v e s t i g a t e d f u r t h e r . F i n a l l y , e l u t i o n w i t h acetone gave a dark r e d band w h i c h on e v a p o r a t i o n gave a r e d s o l i d (0.05 g ) . T h i s was i d e n t i f i e d by i r s p e c t r o s c o p y to be a m i x t u r e o f s t a r t -i n g m a t e r i a l (~ 70%) and [ M e 2 G a ( p z " ) ( O C H 2 C H 2 N M e 2 ) ] M o ( C O ) ( C ? H 7 ) • F e ( C O ) 3 . v C Q ( c m - 1 , c y c i o h e x a n e ) : 1924, 1837 ( M o ( C O ) 2 ) ; 1968, 1979, 2045 ( F e ( C O ) 3 ) . 3 .2 .10 P r e p a r a t i o n of L M ( C O ) 2(CUS M e ) (M= Mo, W) Na LM(CO)_ + MeSCH^Cl —±^f—> LM(CO)-CH.SMe + CO + N a C l (23) J - 7 8 ° C 1 Z A THF s o l u t i o n (=: 100 ml) o f N a + L M ( C O ) 3 ~ (2.0 mmol) was c o o l e d to - 7 8 ° C and a THF s o l u t i o n ( = 25 ml) of M e S C H 2 C l added d r o p w i s e . The s o l u t i o n was a l l o w e d to warm to 0 ° C over a p e r i o d of 30 min d u r i n g which t ime the s o l u t i o n d a r k e n e d . A f t e r s t i r -r i n g f o r a f u r t h e r 30 m i n , s o l v e n t was removed i n vacuo and the brown r e s i d u e e x t r a c t e d w i t h benzene . F i l t r a t i o n , f o l l o w e d by e v a p o r a t i o n o f t h e f i l t r a t e gave an o i l y s o l i d which was washed - 48 -sparingly with methanol to produce a yellow powder. This yellow powder was r e c r y s t a l l i z e d from benzene to give golden yellow c r y s t a l s of the product. Yields were 15-20%. A n a l y t i c a l and selected i r data are l i s t e d i n Table XIV. 3.2.11 Preparation of [MeGa(pz)^]Mo(CO)(CH^SMe) The compound, [MeGa(pz) 3]Mo(CO) 2(CH^SMe), was prepared from [MeGa(pz) 3]Mo(CO)^ (11) by the same method as described in section 3.2.10. Anal. Calcd. for MeGa(pz) 3Mo(CO) 2(CH 2SMe): C, 33.7; H, 3.4; N, 16.8. Found: C, 33.9; H, 3.4; N, 16.8. v c o (cm - 1): 1942, 1805 (CH 2C1 2); 1955, 1948, 1835 (cyclohexane). 1H nmr (T, C,D,): -GaMe, 9.99 (s,3H); pz-H(3), 2.29 (d (J = b b 2Hz), IH), 2.10 (d (J = 2Hz), IH), 1.71 (d (J = 2Hz), IH); pz-H(4), 4.11 (t (J = 2Hz), IH), 4.01 (t ( J = 2Hz), 2H); pz-H (5), 2.97 (d (J = 2Hz), IH), 2.84 (d ( J = 2Hz), 2H); -SMe, 8.61 (s,3H); CH2-S, 6.77 (d (J = 6Hz), IH), 6.07 (d (J = 6Hz), IH). Yi e l d was = 15%. 3.2.12 Reactions of the chromium carbonyl anions A l l the reactions performed with LM(CO) 3 (M = Mo, W) were also attempted with LM(CO) 3 (M = Cr). However, i n a l l cases, gas was evolved and the colour of the solutions became dark green. Ir spectroscopy of the resultant solutions showed the absence of any carbonyl ligands. Removal of solvent l e f t dark green o i l s which were soluble i n aromatic hydrocarbon solvents as well as polar solvents but which could not be Table XIV. A n a l y t i c a l and IR Data for -1 * Calculated(%) Found(%) v c o ( c m ) M R R' C H N C H N CH 2C1 2 C 6H 12 Mo H H 30.0 4.6 9.5 30.3 4.6 9.4 1933, 1782 i Mo H Me 33.4 5.2 9.0 33.4 5.3 9.1 1923, 1910 1950, 1811 1924 Mo Me H 33.4 5.2 9.0 33.7 5.2 8.9 1933, 1784 i Mo Me Me 36.3 5.7 8.5 36.4 5.5 8.4 1923, 1781 1945, 1810 , 1921 1806 W H H 25.0 3.8 8.0 25.1 3.8 7.9 1924, 1786 i W H Me 28.1 4.4 7.6 27.4 4.3 7.3 1911, 1769 1939, 1800, 1917 1795 W Me H 28.1 4.4 7.6 27.8 4.4 7.4 1921, 1765 i W Me Me 30.9 4.8 7.2 31.2 4.9 7.2 1914, 1768 1937, 1799, 1914 1792 * i = insoluble - 50 -induced to c r y s t a l l i z e . 3.3 Results and Discussion 3.3.1 LMn(C0) 3 The manganese tr i c a r b o n y l derivatives were conveniently prepared by refl u x i n g manganese pentacarbonyl bromide with the ligand s a l t s i n THF and t h e i r expected momomeric nature was confirmed by mass spectral analysis. Table XV l i s t s the mass spectral data for the complex where R=R'=H. In each case, the highest observed m/e was due to the parent ion and the most intense signal was due to loss of three carbonyls from the parent ion. Other signals observed were att r i b u t a b l e to loss of methyl, py r a z o l y l , and 'ethanolamino' moieties from the LM + ion. In addition, signals incorporating the f i v e membered r i n g i 1 Ga(N-N) Mn(O) , were observed. Infrared spectra of these complexes in cyciohexane show three strong bands i n the v C Q region of the spectrum (Table VIII, p. 36 ). Figure 12 i l l u s t r a t e s a spectrum t y p i c a l of those observ-ed. This pattern of bands indicates that the asymmetric gal-l a t e ligands occupy three f a c i a l positions i n the postulated octahedral structures with the three CO groups occupying the remaining set of f a c i a l positions (48). A meridionally coordin-ated ligand (and hence a meridional arrangement of the three CO groups) would lead to two weak and one strong v C Q bands. F i t t i n g l y , the stereochemistry displayed by these complexes ( f a c i a l coordination) i s the stereochemistry that would be - 51 -Table XV. Mass Spectrum of [Me 2Ga(pz) (OCH2CH2NH2)] Mn(CO)3 m/e Assignment Intensity 365 Me2Ga(pz)(OCH2CH2NH2)Mn(CO) 2.3 350 MeGa(pz)(OCH 2CH 2NH 2)Mn(CO) 3 + 5.2 322 MeGa(pz)(OCH 2CH 2NH 2)Mn(CO) 2 + trace 294 MeGa(pz)(OCH 2CH 2NH 2)Mn(CO) + 8.6 283 Me 2Ga(pz)(OCH 2CH 2NH 2)Mn + 100.0 266 MeGa(pz)(OCH 2CH 2NH 2)Mn + 17.2 251 Ga(pz)(OCH 2CH 2NH 2)Mn + 24.0 222 Me 2Ga(pz)(0)Mn + 8.6 181 (pz)(OCH 2CH 2NH)Mn + 21.9 144 MeGa(OCH 2CH 2NH 2) + 9.5 133 MeGa(pz)(OCH 2CH 2NH 2)Mn + + 15.8 122 (pz)Mn + 5.7 113 (OCH2CH2N)Mn+ 10.5 99 Me 2Ga + 9.5 69 Ga + 21.0 68 (pz)H + 3.0 55 Mn+ 3.0 * 69 calculated with Ga - 52 -Boo 1 Sooo 1 ^ 0 6 (CM^) F i g u r e 12. I r spectrum of [ M e 2 G a ( p z ) ( O C H 2 C H 2 N H 2 ) ] Mn(CO) . p r e d i c t e d on the b a s i s o f ' t r a n s e f f e c t ' a rguments . A c o m p a r i s o n ' o f the c a r b o n y l s t r e t c h i n g f r e q u e n c i e s of the p r e s e n t compounds w i t h t h o s e of s t r u c t u r a l l y s i m i l a r com-pounds (see T a b l e XVI) show the p r e s e n t g a l l a t e l i g a n d s to donate more e l e c t r o n d e n s i t y (lower ) t o the c e n t r a l m e t a l than p r e v i o u s l y s t u d i e d l i g a n d s , namely Cp , R B ( p z ) 3 and M e G a ( p z ) 3 . In a d d i t i o n , the i n c o r p o r a t i o n of m e t h y l groups on the p y r a z o l y l r i n g and on the amino n i t r o g e n (of the l i g a n d , L) tends t o i n c r e a s e e l e c t r o n d e n s i t y on the c e n t r a l manganese atom as i n d i c a t e d by the lower v r n v a l u e s . - 53 -Table XVI. vco of DMn(CO) Compounds D vco Ref. n 5 - c 5H 5 2035, 1953 49 HB(pz) 3 2041, 1941 32 MeGa(pz) 3 2030 , 1930 11 L, R=R'=H 2032 , 1937, 1911 this work L, R=R1=Me 2024 , 1934 , 1902 t h i s work measured i n cyclohexane F a c i a l coordination of these ligands i s also indicated by the nmr spectra of these complexes (Table VIII, p.36). F i g -ure 13 i l l u s t r a t e s a t y p i c a l example. In a l l the spectra, two signals attributable to -GaMe2 were observed. In addition, in those complexes incorporating the 'Od^ CI-^ NMe^ '^ moiety, two signals a t t r i b u t a b l e to -NMe2 were observed. (The signals due to -NH2 are expected to be broad and were not observed). Meridional coordination would r e s u l t i n only one signal for each of these groups (the Ga-Me's and N-Me's would be related by a mirror plane) - contrary to the observed spectra. The signals observed for the -Cl^Ct^- group are also consistent with f a c i a l coordination. Meridional coordination would resu l t i n an pattern (two t r i p l e t s ) whereas a complicated ABXY pattern i s observed for the -CH2CH2~ groups in the present spectra. The o v e r a l l 'shape' of these spectra was not dependent on temperature (-70°C to 80°C). However, the s p l i t t i n g between the two -GaMe2 signals did decrease s l i g h t l y on warming to 80°C. - 54 -- 55 -3.3.2 LM(CO) 3 (M = Cr, Mo, W) In general, derivatives of Gp VI hexacarbonyls can be pre-pared by two methods: 1. d i r e c t displacement of carbon monoxide from the hexacarbonyl by the desired ligand(s) and 2. displace-ment of a substituent ligand by the desired ligand(s) from a p a r t i a l l y substituted carbonyl complex. It was possible to use the f i r s t method to prepare the 'carbonyl anions' of tungsten and molybdenum. In refluxing THF, the reaction of Na +L with the hexacarbonyl was complete aft e r z 2 days for molybdenum and ~ 3 days for tungsten. However, under the same conditions only 1 mole of CO/mole of Cr(CO) c was evolved after 1 week. Attempts b to increase the rate of t h i s reaction with higher b o i l i n g solvents (dioxane and n-butyl ether) resulted in decomposition of product. The second method proved to be the most useful i n the preparation of these der i v a t i v e s . The molybdenum and tungsten carbonyl anions were e a s i l y prepared by the displacement of a c e t o n i t r i l e groups from (CH^CN)^M(CO)^ (M = Mo, W) and the chromium carbonyl anions were prepared by the displacement of pyridine groups from (py)^Cr(CO)^. In the case of chromium and molybdenum, these reactions were complete aft e r 15-30 minutes at r t . The tungsten reaction was complete after 30 minutes under reflux conditions. Sodium s a l t s of a l l three anions were extremely sensitive (especially i n solution) to both oxygen and water, darkening v i s i b l y on exposure to a i r a f t e r several minutes (the Cr anion turned dark green). The order of s t a b i l i t y (to air) was found - 56 -to be W>Mo>Cr and s u b s t i t u t e d l i g a n d d e r i v a t i v e s > u n s u b s t i t u t e d l i g a n d d e r i v a t i v e s . A r e p r e s e n t a t i v e anion f o r each metal was i s o l a t e d as i t s tetraethylammonium s a l t . In each case, the i s o l a t e d c r y s t a l s c o n t a i n e d a sm a l l amount of THF which c o u l d not be removed by 'pumping i n vacuo' a t r t . However, i t i s noteworthy t h a t the amount of THF i n c o r p o r a t e d i n the c r y s t a l s was co n s t a n t ( f o r each metal) f o r d i f f e r e n t p r e p a r a t i o n s . A n a l y t i c a l , i r , and ^"H nmr data f o r these complexes are t a b u l a t e d i n Table IX, p. 39. As w i t h the manganese t r i c a r b o n y l d e r i v a t i v e s , i r s p e c t r a of the c a r b o n y l anions i n d i c a t e a f a c i a l arrangement of the g a l l a t e l i g a n d . (In CH 2C1 2, the two A' and A" bands appear as a s i n g l e broad band) . The r t ^"H nmr spectrum of the tungsten d e r i v a t i v e , shown i n F i g u r e 14, i s c o n s i s t e n t w i t h t h i s a s s i g n -ment - two s i g n a l s f o r -GaMe2 and two s i g n a l s f o r -NMe2. How-ever, the r t s p e c t r a of the chromium and molybdenum d e r i v a t i v e s showed o n l y one broad s i g n a l f o r each of these groups. The s u s p i c i o n o f a f l u x i o n a l p r o c e s s f o r the ions i n s o l u t i o n was confirmed by v a r i a b l e temperature "*"H nmr s t u d i e s . The tempera-t u r e dependent 1H nmr spectrum o f Et 4N +[Me 2Ga(pz")(OCH 2CH 2NMe 2)] C r ( C O ) 3 i s shown i n F i g u r e 15. At -4 0°C, two s i g n a l s are ob-served f o r each o f the -GaMe2 and -NMe2 m o i e t i e s . On warming, these s i g n a l s broaden and c o l l a p s e and at 57°, one sharp s i n g l e t i s observed f o r each of these groups. Although, the coalesence temperature f o r each s e t of s i g n a l s was the same, the -NMe2 s i g n a l began t o broaden a t a much lower temperature than the -GaMe„ s i g n a l and appeared as a sharp s i n g l e t at a higher temp-* + s i g n a l s due to Et^N 10 " I T F i g u r e 14. 100 MHz 1H nmr spectrum of Et 4N +[Me 0Ga(pz")(0CH 2CH 2NMe o)] W(C0) i n d f-acetone, b - 59 -p e r a t u r e than the -GaMe2 s i g n a l . S i m i l a r behavior was e x h i b i t e d by the molybdenum and tungsten d e r i v a t i v e s . The coalescence temperatures were 6, 3.0, and 4 0°C f o r the Cr, Mo and W ca r b o n y l anions, r e s p e c t i v e l y i n d i c a t i n g t h a t the f l u x i o n a l process i s most f a c i l e f o r the chromium complex and l e a s t f a c i l e f o r the tungsten complex. A suggested mechanism f o r the f l u x i o n a l p rocess i n i l l u s -t r a t e d i n F i g u r e 16. T h i s mechanism r e q u i r e s the brea k i n g of the M-NMe2 bond, rearrangement t o a f i v e - c o o r d i n a t e i n t e r m e d i a t e , and reforming o f the M-NMe2 bond. A 'fast' e q u i l i b r i u m between the two l i m i t i n g s t r u c t u r e s would r e s u l t i n the o b s e r v a t i o n of one s i g n a l f o r each o f the -NMe2 and -GaMe2 groups. A f u r t h e r consequence o f t h i s p r o c e s s i s an i n v e r s i o n a t the p y r a m i d a l l y c o o r d i n a t e d oxygen atom. F i g u r e 16. Suggested mechanism f o r the observed f l u x i o n a l process i n the LM(CO) 3 i o n s . 3.3.3 LM(CO) 2T The t r i c a r b o n y l anions LMCCO)^ (M = Mo, W) undergo de-c a r b o n y l a t i o n r e a c t i o n s w i t h v a r i o u s t h r e e - e l e c t r o n donor l i g a n d s , - 60 -T , to form n e u t r a l d i c a r b o n y l s p e c i e s o f the f o r m , L M ( C 0 ) 2 T . The use o f analogous c y c l o p e n t a d i e n y l (50) and p y r a z o l y l b o r a t e (33,37) m e t a l c a r b o n y l a n i o n s as p r e c u r s o r s t o n e u t r a l o r g a n o -m e t a l l i c compounds has been s t u d i e d e x t e n s i v e l y and the m e t a l c a r b o n y l a n i o n s of the p r e s e n t g a l l a t e l i g a n d s were expec ted to y i e l d s i m i l a r d e r i v a t i v e s . However, the i n c o r p o r a t i o n o f asym-. m e t r i c g a l l a t e l i g a n d s i n t r o d u c e s the p o s s i b i l i t y o f p o s i t i o n a l i s o m e r s , a f a c t o r w h i c h d i d not need t o be c o n s i d e r e d i n the p r e v i o u s l y s t u d i e d symmetric l i g a n d s y s t e m s . M o l e c u l a r models i n d i c a t e t h a t the p o s i t i o n o p p o s i t e the p y r a z o l y l n i t r o g e n a f f o r d s the g r e a t e s t degree of freedom t o the group T and t h e r e -f o r e s h o u l d be the s t e r i c a l l y f a v o u r e d p o s i t i o n o f s u b s t i t u t i o n . The p o s i t i o n t r a n s t o the amino n i t r o g e n i s s l i g h t l y more crowded and the p o s i t i o n t r a n s t o the oxygen i s c o n s i d e r a b l y more crowded. 3 . 3 . 3 . 1 N i t r o s y l D e r i v a t i v e s ;(T = NO) N i t r o s y l d e r i v a t i v e s (n^) can be p r e p a r e d by t r e a t i n g the c a r b o n y l a n i o n s w i t h a s o u r c e o f 'NO ' , two c o n v e n i e n t s o u r c e s b e i n g i s o a m y l n i t r i t e and D i a z a l d . D i a z a l d had been used p r e -v i o u s l y as an e f f e c t i v e n i t r o s y l a t i n g agent i n the p r e p a r a t i o n of CpM(CO) 2 NO (M = C r , Mo, W) f rom N a + C p M ( C O ) 3 ~ (51) and c o n s e q u e n t l y i t was no s u r p r i s e t h a t good y i e l d s o f ~ 70% were o b t a i n e d u s i n g t h i s r e a g e n t . The d e s i r e d compounds were a l s o i s o l a t e d w i t h i s o a m y l n i t r i t e as the s o u r c e o f ' N O + ' . However, c o n s i d e r a b l y lower y i e l d s of ~ 15% were o b t a i n e d w i t h t h i s r e a g e n t . The "'"H nmr s p e c t r a o f these n i t r o s y l compounds suggest the p r e s e n c e o f two i somers i n s o l u t i o n (Table X V I I ) . F i g u r e 17 i l l u s t r a t e s one example . In a l l c a s e s , two s e t s o f s i g n a l s were o b s e r v e d . Based on s t e r i c arguments , t h e two e x p e c t e d i s o m e r s would have NO t r a n s t o the p y r a z o l y l n i t r o g e n and t r a n s to the amino n i t r o g e n ( F i g . 18 ) . Isomer A would be f a v o r e d by b u l k y groups a t the 3 p o s i t i o n of the p y r a z o l y l r i n g and Isomer B would be f a v o r e d by b u l k y groups on the amino n i t r o g e n and these f a c t o r s are r e -f l e c t e d i n t h e o b s e r v e d isomer r a t i o s . When the p y r a z o l y l m o i e t y i s s u b s t i t u t e d w i t h m e t h y l groups a t the 3 and 5 p o s i t i o n s and the amino n i t r o g e n u n s u b s t i t u t e d , t h e Isomer A : I s o m e r B r a t i o i s 5 : 1 . When the ' p y r a z o l y l ' moiety i s u n s u b s t i t u t e d and t h e 'amino' n i t r o g e n s u b s t i t u t e d by m e t h y l g r o u p s , the Isomer A : Isomer B r a t i o i s 1 : 1 . I t i s noteworthy t h a t n e i t h e r c h a n g i n g the c e n t r a l m e t a l nor c h a n g i n g the source of ' N 0 + l r e s u l t e d i n a change o f the isomer r a t i o . T h i s i n d i c a t e s t h a t i t i s p r i m a r i l y the s u b s t i t u e n t s on the l i g a n d L t h a t c o n t r o l the p o s i t i o n o f Table XVII. H nmr Data for * Approxi- Predicted T (PP"0 mate p o s i t i o n M R R' R R' H4 Ga -Me isomer r a t i o of NO s u b s t i t u t i o n Mo H H 2.34dt, 2.76dt 3.81tt 9.99s, 10.32 2 A 2.76dt, 2.88dt 4.01tt 9.91s, 10.25 1 B Mo H Me 2.31dt, 2.75dt 7 84s, 8.34s 3.83tt 10.01s, 10.23 1 A 2.71dt, 2.87dt 7 91s, 8.50s 4.02tt 9.91s, 10.19s 1 B Mo Me H 7.64s, 8.00s 4.26s 9.93s, 10.27s 5 A 7.95s, 8.06s 4.43s 9.82s, 10.21s 1 B Mo Me Me 7.60s, 7.99s 7 84s, 8.21s 4.25s 10.06s, 10.19s 3 A 7.79s, 8.10s 8 05s, 8.35s 4.43s 9.88s, 10.14s 1 B W H H 2.29dt, 2.85dt 3.88tt 9.99s, 10.38s 2 A 2.72dt, 2.98dt 4.10tt 9.90s, 10.30s 1 B W H Me 2.28dt, 2.84dt 7. 72s, 8.31s 3.89tt 9.98s, 10.25s 1 A 2.71dt , 2.98dt 7. 72s, 8.47s 4.10tt 9.86s, 10.20s 1 B W Me H 7.62s, 8.04s 4.28s 9.94s, 10.32s 5 A 7.93s, 8.11s 4.48s 9.80s , 10.24s 1 B W Me Me 7.59s, 8.05s 7. 67s, 8.20s 4.28s 10.03s, 10.28s 3 A 7.67s, 8.11s 7. 87s, 8.34s 4.48s 9.86s, 10.18s 1 B * T(TMS) + J z 2 = 10 Hz 0 0 ppm, = 2.84 ppm, s = s i n g l e t , d = doublet, t = t r i p l e t A - p o s i t i o n opposite 'pyrazolyl' nitrogen, B = p o s i t i o n opposite 'amino' nitrogen - 64 -s u b s t i t u t i o n . In each c a s e , t h e most abundant isomer i s the isomer w i t h s u b s t i t u t i o n o p p o s i t e t h e p y r a z o l y l n i t r o g e n . A t t e m p t s t o s e p a r a t e the two isomers by column chromatography were u n s u c c e s s f u l . A l t h o u g h the nmr s p e c t r a o f these compounds c l e a r l y i n d i c a t e s the p r e s e n c e of two i s o m e r s , t h e i r i n f r a r e d s p e c t r a d i d not c o n f i r m t h i s c o n c l u s i o n . S o l u t i o n s p e c t r a i n C H 2 C 1 2 (the compounds were i n s o l u b l e i n cyc lohexane) d i s p l a y e d o n l y two v C Q bands and one v N Q band (see T a b l e X , p . 41 ) . However, i t i s p o s s i b l e t h a t the d i f f e r e n t i s o m e r s g i v e s i m i l a r band p o s i t i o n s and are n o t d e t e c t a b l e as s e p a r a t e e n t i t i e s by i r methods ( p a r t i c u l a r l y s i n c e t h e v C Q and v N Q bands i n C B ^ C ^ a r e r e l a t i v e l y b r o a d ) . 3.3.3.2 A r y l d i a z o D e r i v a t i v e s (T = A r N - J A r y l d i a z o compounds can be p r e p a r e d by t r e a t i n g the c a r -b o n y l a n i o n s , LM(CO).j , w i t h a r y l d i a z o n i u m s a l t s . The a r y l d i a z o l i g a n d i s r e l a t e d to the n i t r o s y l l i g a n d i n t h a t i t f o r m a l l y donates t h r e e e l e c t r o n s and i n t e r a c t s w i t h the m e t a l v i a a s i n g l e n i t r o g e n atom. However, i n c o n t r a s t t o the n i t r o s y l l i g a n d and w h i c h can o n l y c o o r d i n a t e i n one c o n f o r m a t i o n , t h e a r y l d i a -zonium l i g a n d can c o o r d i n a t e i n e i t h e r o f two d i s t i n c t c o n f o r m a -t i o n s ( F i g u r e 1 9 ) . As w i t h the NO complexes , the "^ H nmr of the a r y l d i a z o complexes i n CgDg s o l u t i o n i n d i c a t e the p r e s e n c e o f two i somers (see T a b l e X V I I I and F i g u r e 20 ) . On a n a l y s i s of t h e s e s p e c t r a , i t was found t h a t t h e o b s e r v e d isomer r a t i o was dependent on T a b l e X V I I I H nmr Data f o r Mefia x(ppm) GaHe A p p r o x i -mate P o s i t i o n — i s o m e r o f NO r a t i o s u b s t i t u t i o n * Mo H H 2.62d, 2.83d 4.01t 9.90s, 10.11s 2 A 2.19d, 2.75d - 3.88t 9.93s, 10.20s 1 B Mo H Me 2.59d 7.53s, 8 .52s 4.03t 9.87s, 10.02s 3 A 2.14d 7.68s, 8 .25s 3.89t 9.94s, 10.06s 2 B Mo Me H 7.81s, 8.00s 4.34s 9.81s, 10.07s 3 A 8.01s, 7.90s 4.19s 9.85s, 10.21s 1 B Mo Me Me 7.83s, 8.12s 7.49s, 8 .42s 4.44s 9.91s, 10.20s 2 A 7.77s, 8.07s 7.48s, 8 .16s 4.28s 9.96s, 10.24s 1 B W H H 2.60d, 2.76d 3.93t 9.90s, 10.29s 2 A 2.16d, 2.71d 3.82t 9.99s, 10.29s 1 B W H Me 2.59d, 2.75d 7.65s, 8 .52s 3.94t 9.89s, 10.16s 3 A 2.15d, 2.71d 7.87s, 8 .26s 3.82t 9.93s, 10.19s 2 B W Me H 7.86s, 8.11s 4.44s 9.82s, 10.16s 3 A 7.99s, 8.09s 4.28s 9.90s, 10.30s 1 B W Me Me 7.83s, 8.12s 7.49s, 8 .42s 4.44s 9.91s, 10.20s 2 A 7.77s, 8.07s 7.48s, 8 .16s 4.28s 9.96s, 10.24s 1 B * T < C 6 D 6 ) = 2 .84 ppm, s = s i n g l e t , d = d o u b l e t , t = t r i p l e t " A = p o s i t i o n o p p o s i t e ' p y r a z o l y l ' n i t r o g e n , B = p o s i t i o n o p p o s i t e 'amino' n i t r o g e n . - 66 -D D Figure 19. Bonding conformations of the ArN 2 ligand. the type of substituent on the 3 and 5 positions of the pyrazolyl r i n g and on the amino nitrogen. Methyl groups on the pyrazolyl ring favoured the more abundant isomer and methyl groups on the amino nitrogen favoured the less abundant isomer. This was exactly the same trend found with the NO derivatives and based on t h i s evidence, i t was concluded that the "'"H nmr spectra indicate the presence of p o s i t i o n a l isomers i n solution. More-over, the most abundant isomer i s that isomer with the ^ A r group opposite the pyrazolyl nitrogen. The i r spectra of the afyldiazo complexes i n cyciohexane solution showed three v C Q bands (Table XI, p.42 ) and i n each case, the i n t e n s i t i e s of the three bands were approximately equal (see Figure 21). These re s u l t s are, at f i r s t , somewhat surprising when taken i n conjunction with the "^K nmr spectra. The two p o s i t i o n a l isomers indicated for each of the complexes by the "^H nmr r e s u l t s would be expected to give r i s e to a t o t a l of 4 v r n bands i n two pairs with d i f f e r e n t r e l a t i v e i n t e n s i t i e s - 68 -2000 1800 CM" F i g u r e 21. I r spectrum of [Me 2Ga(pz")(OCH 2CH 2NMe 2)] Mo(CO) 2(N 2Ph) i n cyciohexane. dependent on the extent and p o s i t i o n of methyl s u b s t i t u t i o n of the g a l l a t e l i g a n d . The t h r e e v C Q bands observed i n the i r s p e c t r a , even i f the higher frequency band i s i n f a c t two super-imposed bands, do not d i s p l a y the expected i n t e n s i t y p a t -t e r n s . Moreover, the v N = N s t r e t c h i n g frequency i s expected at ~ 1600 cm ^ (based on p r e v i o u s s t u d i e s on the R B ( p z ) 3 system (51a)) and t h e r e f o r e c o u l d not be the source of one of the bands -1 at z 1900 cm A more a t t r a c t i v e e x p l a n a t i o n i s t h a t the three V^Q bands i n each spectrum a r i s e from one p o s i t i o n a l isomer, due t o a c o u p l i n g o f the N=N s t r e t c h i n g v i b r a t i o n w i t h the s t r e t c h -i n g v i b r a t i o n s of the two CO groups. In t h i s case, the a r y l d i a z o group a c t s as a pseudocarbonyl group and the asymmetric s t r e t c h -i n g v i b r a t i o n (E v i b r a t i o n i n symmetry) i s s p l i t by the - 69 -asymmetric g a l l a t e ligand. In related compounds (viz [RB(pz) 3]Mo (CO) 2(N 2Ar) (36), [MeGa(pz) 3]Mo(CO) 2(N 2Ar) and CpMo(CO) 2(N 2Ar) (37)) incorporating symmetric ligands, the two asymmetric v i b r a -tions are degenerate and a t o t a l of only two v C Q bands i s observed. I f t h i s explanation i s correct, then i t must be assumed that the two p o s i t i o n a l isomers observed i n the ''"H nmr spectra have the same or very s i m i l a r carbonyl stretching frequencies i n the i r . 3.3.3.3 ' A l l y l ' Derivatives (T = n 3-C 3H 5 o r n 3-C 1H ?) 3 n - a l l y l d e r i v a t i v e s , LM(CO) 2'allyl' can be prepared by treating the carbonyl anions with a l l y l i c halides i n THF. As with the pyrazolylborate system (33) and i n contrast to the cyclopentadienyl system, no intermediate a - a l l y l species could be i s o l a t e d . The rate of reaction was found to be dependent on the metal, M, as well as the nature of L. The tungsten carbonyl anions reacted more slowly (than the Mo carbonyl anions) and increasing the number of substituents on L also necessitated longer reaction times. In the case of M=W and L(R=R'=Me), the carbonyl anion did not react with a l l y l bromide or methallyl chloride. However, i t was possible to prepare the desired a l l y l d e rivative by the following route: (CH3CN) 2W(CO) 2 ( n 3 - C 3 H 5 ) B r + Na +L~ > LW(CO) 2 (n 3-C 3H 5) + NaBr + CH3CN (24) 3 This method had been used previously to. prepare CJpMo (CO) 2 (TI -C3H,-) (52) and could be used as an alternate method to synthesize a l l the ' a l l y l ' d erivatives l i s t e d i n Table IX (p. 39). However, - 70 -this method offered no advantage i n terms of y i e l d . Selected nmr data of the prepared compounds are l i s t e d i n Table XIX and the 1H nmr spectrum of Me 2Ga(pz")(OCH 2CH 2NH 2) 3 Mo(CO)2(n -C^ H,.) i s shown i n Figure 22a. In contrast to the n i t r o s y l ( n 1 ) and aryldiazo ( n 1 ) derivatives, i n a l l but one nmr spectrum the presence of only one isomer i s indicated. In 3 addition, each proton on the n -C^ii^ group was found to be d i f -ferent - a necessary consequence of the asymmetric g a l l a t e ligand Although the signals from the -CH2CH2~ moiety frequently obscured the positions of the a l l y l protons, t h e i r assignments (of the C^ H,. protons) could be confirmed by double resonance experiments. For example, i r r a d i a t i o n of the unique a l l y l proton, ( 'A1 i n Fi g . 22a and 22b) caused both syn protons to collapse to doublets and both a n t i protons to collapse to si n g l e t s . The nmr parameters for the C^H^ group i n t h i s p a r t i c u l a r complex, Me2Ga (pz") (OCH_CH_NH_)Mo (CO) „ (n 3-C 0H c) , are as follows: (x, C , D J Z Z Z Z J D o b H s y n , 6.54 (dd (J = 6.5, 3.2 Hz), IH), 7.19 (dd (J = 6.5, 3.2 2Hz), IH); H a n t i , 8.65 (d (J = 10 Hz), IH), 8.98 (d (J = 10 Hz), IH); H . , 6.24 (tt (J = 10, 6.5 Hz), IH) and are representa-unique' ' * 3 t i v e of a l l the r\ - a l l y l complexes studied. Figure 22b c l e a r l y shows the t r i p l e t of t r i p l e t s observed for the unique proton and the doublet of doublets observed for each syn proton. The 'stick' spectrum i s based on the parameters stated above. The two syn and the two anti protons for the C^H^ group were not i d e n t i f i e d unequivocally, but they are also inequivalent. The one H^ nmr spectrum that suggested the presence of more than one isomer was the spectrum of [Me 2Ga(pz)(OCH 2CH 2NH 2)]w(CO) 2 T a b l e X I X . H nmr Data f o r T (ppm)* M R R' R" R R' R" H4 Ga -Me Mo H H H 2 . 5 3 b r , ( 2 . 9 ) Mo H H Me 2.34d, 2.75d 8 .35s 3.80t 9.92s, 10.34s Mo Me H H 7.68s, 8.03s 4.33s 10 .02s, 10.40s Mo Me H Me 7.62s, 8.01s 8 .33s 4.27s 9.93s, 10.39s Mo H Me H 2.67d, 2.91d 7 .08s, 8.51s 3.97t 10.14s, 10.36s Mo H Me Me 2.75d, (2.9) 7 .07s, 8.44s 8 .65s 3.95t 10.05s, 10.35s (br) (br) (br) (br) Mo . Me Me H 7.67s, 8.03s 7 .05s, 8.29s 4.34s 10.06s, 10.33s Mo Me Me Me 7.22s, 8.08s 7 .07s, 8.24s 8 .60s 4.33s 9.98s, 10.34s W H H H 2.53br ,2.95d 4.00t 10.05s, 10.44s W H H Me 2.36d, 2.89d 8 .65s 3.93t 9.94s, 10.44s 2.38d, 2.92d (br) 4.01t 10.24s, 10.41s W Me H H 7.70s, 8.10s 4.39s 10.05s, 10.47s W Me H Me 7.60s, 8.09s 8 .13s 4.34s 9.97s, 10.49s W H Me H 2.63d, 2.98d 6 .97s, 8.58s 4.06t 10.15s, 10.39 W H Me Me 2.71d, 2.94d 6 .93s, 8.43s 8 .52s 4.03t 10.01s, 10.37s W Me Me H 7.67s, 8.09s 6 .94s, 8.35s 4.38s 10.07s, 10.36s * measured i n C,D, s o l u t i o n s = s i n g l e t , d = d o u b l e t , t = t r i p l e t , b r = b r o a d M L l : . L__l I I I l | | 1 | I | | | i l 1 i 1 6 6.5 7 7.5 X Figure 22b. 100 MHz *H nmr spectrum of [Me2Ga (pz") (OCH2CH2NH2)] Mo (CO) 2 (n 3-C 3H 5) (6-7.5 T, s t i c k spectrum based on parameters discussed i n tex t ) . - 74 -3 (n -C^H-j) . For t h i s compound two sets of signals were observed for each of the pyrazolyl and -GaMe2 protons. In addition the Me-allyl signal was f a i r l y broad. The i r spectrum of t h i s compound and i t s molybdenum analog both displayed 6 bands i n the region (measured i n cyclohexane). Although p o s i t i o n a l isomerism i s possible, the lack of 1:1 correspondence between the 'isomer ra t i o s ' derived from 1H and i r data (see Figure 23) i n either of these compounds suggests conformational isomerism, with d i f -ferent orientations of the n -C^H^ group, rather than pos-i t i o n a l isomerism. In addition, the fact that the same two com-plexes show only 2 v C Q bands i n CH 2C1 2 (but broader) supports t h i s conclusion. The e f f e c t of solvent on isomer d i s t r i b u t i o n i n t h i s type of complex has been documented previously (53). In one complex, [Me 2Ga(pz)(OCH 2CH 2NMe 2)]Mo(CO) 2(n 3-C 4H 7), the -NMe2 and -GaMe2 signals i n the nmr spectrum were quite broad and the suspected p o s s i b i l i t y of a f l u x i o n a l process i n solution was confirmed by a variable temperature study (see Figure 24). On cooling the solution to 18°C, each of the -GaMe2 and - NMe2 signals appear as two sharp s i n g l e t s and on warming the solution, these two pairs of signals collapse and reappear as two single signals. In addition, the signals due to -CH2CH2~ now appear as two well resolved t r i p l e t s . Although the -GaMe2 and -NMe2 signals coalesce at the same temperature, the -GaMe2 signal sharpens over a much shorter temperature range. At the highest attainable temperature (92°C), the -GaMe2 i s already a sharp s i n g l e t while the -NMe2 signal i s just beginning to sharpen. The behavior exhibited by t h i s ' a l l y l ' complex i s - 75 -2000 (b) 1800 C M " F i g u r e 23. n m r ( a , C,D,) and i r (b, cyc iohexane) s p e c t r a o f 6 b [Me 2Ga (pz) (OCH 2 CH 2 NH 2 ) ] W(CO) 2 ( n 3 - C 4 H ? ) . s i m i l a r to t h a t o b s e r v e d f o r the p a r e n t t r i c a r b o n y l a n i o n s (p. 59 ) and a s i m i l a r mechanism might be i n v o k e d to e x p l a i n the f l u x i o n a l p r o c e s s (see F i g u r e 25) . The o n l y d i f f e r e n c e i s t h a t the c a r b o n y l l i g a n d o p p o s i t e the p y r a z o l y l n i t r o g e n i s now r e p l a c e d by a n " C ^ H ^ l i g a n d , - 76 -(*) : -CH 2CH 2- protons; (4-) : -NMe2 protons F i g u r e 24. Temperature dependent 100 MHz "'"H nmr spectrum of [Me 2Ga(pz) (OCH 2CH 2NMe 2)]Mo(CO) 2(n 3-C 4H 7) i n CgDg. - 77 -Figure 25. Suggested mechanism for the f l u x i o n a l process observed i n [Me2Ga(pz) (OCH2CH2NMe2)] Mo(CO) 2 ( n 3 - c 4 H 7 ) . To confirm the stereochemistry suggested by the physical data, a c r y s t a l study of the complex [Me 2Ga(pz")(OCH 2CH 2NH 2)] 3 Mo (CO) 2 (n -C 4H 7) was undertaken by Dr. S. Rettig (see Figure 26). The x-ray structure confirms unequivocally the tridentate chelating character of the gal l a t e ligand and also the fac nature of i t s coordination i n t h i s type of complex. In addition, the n 3-C 4H 7 ligand i s situated trans to the pyrazolyl nitrogen - as predicted. Figure 26. Molecular structure of [Me 2Ga(pz") (OCH2CH2NH2) ] Mo(CO) 2(n 3-C 4H 7) . - 78 -Analysis of the bonding parameters of t h i s compound reveal two unusual features. F i r s t , as a r e s u l t of interactions be-tween the a l l y l i c methyl group and the carbonyls, the cen t r a l o Mo-C ( a l l y l ) distance (2.370(6) A) i s s i g n i f i c a n t l y longer than the terminal Mo-C ( a l l y l ) distances (2.331(3) and 2.320(3) A). This i s i n contrast to most other T r - a l l y l structures where the central M-C bond i s the Shortest of the three (55,56). Secondly the two carbonyl C-0 distances were found to be s i g n i f i c a n t l y d i f f e r e n t (C-0 trans to 0: 1.174(3) and C-0 trans to amino o nitrogen: 1.152(3.) A). A complementary e f f e c t was observed i n the M-CO distances, the M-CO bond distance trans to oxygen being much shorter than the M-CO distance trans to the amino nitrogen (1.902(3) vs 1.961(2) A). 3 3.3.3.4 Cycloheptatrienyl Derivatives (T = n -C^H^) Closely related to the a l l y l complexes are the cyclohepta-t r i e n y l derivatives which can be prepared by treating the car-bonyl anions with tropenium s a l t s . However, a more e f f i c i e n t route to the same compounds i s v i a the reaction of C^H^MfCO^I (M = Mo, W) with Na +L . Assuming a tridentate chelating g a l l a t e 7 ligand, the p o t e n t i a l l y n cycloheptatrienyl group i s expected 3 . to act as a 'n - a l l y l i c ' ligand i n the LM(C0) 2T complexes. 3 The preparation of 'Fe(C0) 3' adducts of n ~C^H^ derivatives where the 'Fe(CO)^ group i s bonded to the butadiene part of the C-yH-y ring has been proposed as a chemical proof of a trihapto (as opposed to a penta- or heptahapto ) cycloheptatrienyl r i n g (57). When an ethereal solution of LMo(CO)0(C_H_)(R=R'=Me) was i r r a d i a t e d i n the p r e s e n c e o f F e ( C O ) ^ , the complex LMo(CO)^C^H^• Fe(CO)-j was f o r m e d . However, t h i s r e a c t i o n was c o m p l i c a t e d by d e c o m p o s i t i o n o f e i t h e r the s t a r t i n g m a t e r i a l o r the p r o d u c t to form a s p e c i e s o f the f o r m u l a [C-^H^Fe (CO) ^] 2 • In a d d i t i o n , the d e s i r e d F e ( C O ) 3 adduct c o u l d n o t be s e p a r a t e d from the s t a r t i n g m a t e r i a l u s i n g column chromatography o r f r a c t i o n a l r e c r y s t a l l i z a -t i o n . N e v e r t h e l e s s , i r s p e c t r a measured i n c y c l o h e x a n e showed ( i n a d d i t i o n to bands due to the s t a r t i n g m a t e r i a l ) f i v e v C Q bands a t 1924 , 1837 [ M o ( C O ) 2 ] , 2045, 1979 and 1968 c m - 1 [Fe (CO) ] . T h i s p a t t e r n o f bands i s v e r y s i m i l a r to t h a t o b s e r v e d f o r [ H B ( p z ) 3 ] M o ( C O ) 2 C ? H 7 - F e ( C O ) 3 (1950, 1874, 2050, 1990 and 1980 cm" 1 ) (57) and C p M o ( C O ) 2 C 7 H ? - F e ( C O ) 3 (1950, 1880, 2040, 1980 and 1975 cm 1 ) (58) and s t r o n g l y suggest a t r i h a p t o c y c l o h e p t a t r i e n y l l i g a n d i n the g a l l a t e complex . The compound [ c ^ H ^ F e ( C O ) 3 ] 2 was c h a r a c t e r i z e d by mass s p e c t r o m e t r y ( h i g h e s t m/e = P a r e n t i o n minus C O ) , e l e m e n t a l a n a l y s i s , i r s p e c t r o s c o p y and 1 H nmr s p e c t r o s c o p y . The 1 H nmr spectrum showed t h r e e m u l t i p l e t s a t T 7 .56 , 5.36 and 4.49 w i t h r e l a t i v e i n t e n s i t i e s 3 : 3 : 1 (see F i g . 27) and the i r spectrum i n c y c l o h e x a n e showed t h r e e bands i n d i c a t i n g t h a t the two F e ( C O ) 3 groups are ' e q u i v a l e n t ' . A compound h a v i n g the same m o l e c u l a r f o r m u l a has been r e p o r t e d e a r l i e r (59) and the proposed s t r u c t u r e c o n s i s t e d o f a d i t r o p y l i u m l i g a n d w i t h each F e ( C O ) 3 group a t t a c h e d to a t r o p y l i u m r i n g . The 1 H nmr spectrum of t h i s compound c o n s i s t e d o f t h r e e m u l t i p l e t s w i t h r e l a t i v e i n t e n s i t i e s 8 :4 :2 w i t h the ' u n i q u e ' p r o t o n b e i n g a t h i g h f i e l d . E v i d e n t l y , the p r e s e n t compound does not have t h i s s t r u c t u r e but on the - 81 -other hand, a structure that f i t s a l l the experimental data i s d i f f i c u l t to v i s u a l i z e . 1 3 The H nmr spectra of the ry -CyH^ complexes, recorded i n CgDg, are l i s t e d i n Table XX and i n the majority of the complexes the presence of one isomer i s indicated i n the solutions (see F i g . 28). However, i n the spectra of [Me2Ga (pz) (OCH2CH2NH2)]M 3 (CO) 2(n -C 7H 7) (M = Mo, W), two sets of signals i n the r a t i o 6:1 were found (see F i g . 29). In addition, the i r spectrum of [Me2Ga(pz) (0CH2CH2NH2)]Mo(C0) 2 (n -C ?H 7) i n cyciohexane solution (the analogous W compound was insoluble) showed two pairs of bands i n approximately the same r a t i o (Fig. 29 ( i n s e r t ) ) . Apparently, there are two p o s i t i o n a l isomers formed i n the syn-thesis of these two compounds. 3 The fact that only one sharp signal due to the n -C 7H 7 group i s observed i n the r t ^"H nmr spectra of these complexes indicates that t h i s group i s involved i n a rapid f l u x i o n a l process. This was confirmed by a variable temperature "^H nmr study of the complex [Me2Ga(pz) (0CH2CH2NMe2)] W(CO) 2(n 3-C ?H 7) (see Figure 30). As the sample solution was cooled, the signal due to C 7H 7 successively broadened, disappeared and f i n a l l y reappeared as f i v e d i s t i n c t multiplets. The low temperature l i m i t i n g spectrum was reached at - -75°C and i s shown i n Figure 31. The assignments of the C ?H 7 protons are l i s t e d i n Table XXI and are based on double resonance experiments. I r r a d i a t i o n of resonance (a) caused resonance (g) to collapse to a doublet (resonance (b) p a r t i a l l y obscured by CH- protons) and i r r a d i a t i o n Table XX. T (ppm)* M R R' C 7H ? R R' Ga--Me Mo H H 4.74s 5.04s 3.88t 2. 36d, 2. 85d 10. 9. 15s, 66s, 10. 10. 36s 20s Mo Me H 4.83s 4.27s 7. 53s, 8. 03s 10. 09s, 10. 37s Mo H Me 4.76s 3.91t 2. 34d, 2. 84d 7. 51s, 8. 59s 10. 16s, 10. 28s Mo Me Me 4.83s 4.26s 7. 46s, 8. 02s 7. 48s, 8. 36s 10. 08s, 10. 26s W H H 4.93s 5.21s 3.98t 3.91t 2. 35d, 2. 92d 10. 9. 17s, 67s, 10. 10. 42s 26s W Me H 5.01 4.33 7. 56s, 8. 08s 10. 10s, 10. 43s W H Me 4.95 4.00t 2. 36d, 2. 9 2d 7. 35s, 8. 61s 10. 19s, 10. 34s W Me Me 5.00 4.32s 7. 50s, 8. 07s 7. 32s, 8. 38s 10. 10s, 10. 30s measured i n CgDg solution s = s i n g l e t , d = doublet, t = t r i p l e t * peak due to C ^ H ^ group F i g u r e 28. 100 MHz XE nmr spectrum of [ M e 2 G a ( p z ) ( O C H 2 C H 2 N M e 2 ) ] M o ( C O ) 2 ( n 3 - C 7 H 7 ) i n C , D , . 6 6 \ - 85 -of (b) or (g) caused (a) t o c o l l a p s e to a d o u b l e t as w e l l as a f f e c t i n g resonance (c,f) . In a d d i t i o n , i t was n o t i c e d t h a t i r -r a d i a t i o n o f (b) a f f e c t e d o n l y the l o w f i e l d h a l f o f the ( c f f ) m u l t i p l e t and i r r a d i a t i o n of (g) a f f e c t e d o n l y the u p f i e l d h a l f of the ( c , f ) m u l t i p l e t . I r r a d i a t i o n of the l o w f i e l d h a l f of the ( c , f ) m u l t i p l e t reduced the h i g h f i e l d h a l f of the m u l t i p l e t (e,d) t o a d o u b l e t and i r r a d i a t i o n of the u p f i e l d h a l f of the (c,f) m u l t i p l e t reduced the l o w f i e l d h a l f of the (e,d) m u l t i p l e t t o a d o u b l e t (as w e l l as r e d u c i n g (g) to a d o u b l e t ) . F i n a l l y , i r r a d i a t i o n o f the l o w f i e l d h a l f of m u l t i p l e t (e,d) reduced the u p f i e l d h a l f of m u l t i p l e t (c,f) to a d o u b l e t w h i l e i r r a d i a t i o n of the u p f i e l d h a l f of m u l t i p l e t (e,d) reduced the l o w f i e l d h a l f of m u l t i p l e t ( c , f ) t o a d o u b l e t . These experiments f i x the r e l a t i v e p o s i t i o n s of the r e s p e c t i v e protons and s i n c e the h i g h -f i e l d proton i s coupled t o both protons (b) and (g) (the o t h e r 1 proton m u l t i p l e t s ) , i t must be the one a s s o c i a t e d w i t h the c e n t r a l a l l y l i c carbon atom. The near i d e n t i c a l computer simu-l a t e d spectrum (based on parameters g i v e n i n Table XXI) shown i n F i g u r e 31 confirms u n e q u i v o c a l l y these assignments. I t i s a l s o noted t h a t the o b s e r v a t i o n of seven ' d i f f e r e n t * protons completely e l i m i n a t e s any p o s s i b i l i t y of a monohapto c y c l o h e p t a -t r i e n y l r i n g . I t i s i n t e r e s t i n g to compare the low temperature l i m i t i n g spectrum of the 'symmetric' CpMo(CO)^ (n^-C^H^) complex. T h i s spectrum d i s p l a y e d f o u r s i g n a l s due t o the c y c l o h e p t a -t r i e n y l r i n g - as expected (60). On the o t h e r hand, the l i m i t i n g spectrum of the p y r a z o l y l b o r a t e complex - 86 -Figure 30. Temperature dependent 100 MHz H nmr spectrum of [Me 2Ga(pz)(OCH 2CH 2NMe 2)] W(C0) 2tn 3-C 7H 7) in d g-acetone. F i g u r e 31. Low temperature spectrum o f [Me2Ga(pz) (OCH 2 CH 2 NMe 2 ) ]W(CO) 2 (n 3 - C ? H 7 ) , e x p e r i m e n t a l (upper) and computer s i m u l a t e d ( l o w e r , C 7 H 7 r i n g o n l y ) . - 8 8 -3 [H 2B(pz") 2]Mo(CO) 2(n -C 7H 7), which contains a B-H-Mo two-electron three-centre bond and a trihapto C-JH-J r i n g ( 6 1 ) , also shows (surprisingly) only four signals ( 6 2 ) even though the C 7H 7 group i s asymmetrically positioned with respect to the pyrazolylborate ligand i n the pseudo octahedral complex ( 6 1 ) . Table XXI. Low Temperature nmr Data for the C 7H 7 Ring i n [Me2Ga(pz) (OCH^CB^NI^)] W(CO) 2 (n 3-C 7H 7) Proton a Chemical S h i f t (T) 1 3 Coupling Constants (Hz) Pattern a 9 . 3 9 b 6 . 0 2 c 3 . 4 6 d 4 . 9 6 e 4 . 8 2 f 3 . 5 6 g 5 . 5 4 SL ID C See F i g . 3 1 ; i n d^-acetone; calculated from p o s i t i o n of C 7H 7 ring at r t Preliminary data on the c r y s t a l structure determination of [Me2Ga(pz") (OCH2CH2NH2)] Mo(CO) 2(n 3-C 7H ?) has confirmed the a l -l y l i c nature of the cycloheptatrienyl ligand (63) . However, the position of substitution was found to be trans to the amino nitrogen rather than trans to the pyrazolyl nitrogen. A possible reason for t h i s change i s the bulk and (elongated) shape of the C 7 H 7 r i n g . In the s o l i d state structure the C-/H7 r i n g i s all i g n e d p a r a l l e l to the 'pyrazolyl' r i n g and the two CO groups whereas i f i t were situated opposite the 'pyrazolyl' nitrogen, Jab Jba 6. 6. 6, 6, J ag ^bc = 6. 7. 6 0 t r i p l e t not seen J c d - 1 1 . 0 , J c b — 7. 0 complex Jde = 9. 5, J . dc = 1 1 . 0 complex J e f = 1 2 . 0 , ed = 9. 5 complex fg j ga = 7. 0 , f e = 1 2 . 0 complex = 6. 6, J gf 7. 0 distorted t r i p l e t - 89 -s t e r i c i n t e r a c t i o n s w i t h the g a l l a t e l i g a n d would become q u i t e severe, p a r t i c u l a r l y w i t h the amino a l c o h o l p a r t o f the complex. 2 3 . 3 . 3 . 5 Thiomethoxymethyl D e r i v a t i v e s (T = n -CH^SMe) 2 5The p r e p a r a t i o n of 'n -CI^SMe' d e r i v a t i v e s was prompted by the d e s i r e t o study a system more s t e r i c a l l y demanding than the n i t r o s y l or a r y l d i a z o systems (ri^) but l e s s s t e r i c a l l y 3 demanding than the a l l y l i c or c y c l o h e p t a t r i e n y l systems (n ). These d e r i v a t i v e s were prepared by t r e a t i n g the c a r b o n y l anions LM(CO) 3~ w i t h MeSCH 2Cl at -78°C and, as w i t h the ' a l l y l ' d e r i v a -t i v e s , no a-bonded s p e c i e s was i s o l a t e d . Again, t h i s i s i n d i r e c t c o n t r a s t to the behaviour of the analogous c y c l o p e n t a -d i e n y l system (64). In a d d i t i o n to p o s i t i o n a l isomerism, these complexes can e x h i b i t two types of c o n f o r m a t i o n a l isomerism a r i s i n g from d i f -f e r e n t modes of c o o r d i n a t i o n of the CH^SMe group (see F i g u r e 32). The f i r s t type of c o n f o r m a t i o n a l isomerism i n v o l v e s a r o t a t i o n of the ' s u l f u r l i g a n d ' about the CE^-S bond which would p l a c e the S-Me group i n an up or down p o s i t i o n ( p a i r s a,b and c , d ) . The second type i n v o l v e s a r o t a t i o n of the s u l f u r l i g a n d about the midpoint of the Cli^-S bond which would g i v e the l i g a n d two d i f f e r e n t ' b i t e s ' r e l a t i v e to the remainder of the unsym-m e t r i c a l o c t a h e d r a l molecule ( p a i r s a,c and b,d). The i n f r a r e d s p e c t r a of the complexes i n C I ^ C ^ s o l u t i o n and as n u j o l mulls (Table XI, p. 42 ) show two e q u a l l y strong bands i n the c a r b o n y l s t r e t c h i n g r e g i o n . However, f o r those f o u r complexes s o l u b l e i n cyciohexane, f o u r sharp bands of - 90 -H 2C M / S (a) M H 2C S (b) \ ^ \ M S CH. (c) / M S C H 2 (d) Figure 32. Bonding conformations of the CH2SMe ligand. roughly equal i n t e n s i t y were observed i n t h i s same region (Fig-ure 33). Similar spectra were observed i n CS 2 solution (4 v C Q bands) and these observations indicate the presence of two isomers (positional or conformational) i n these solutions. r 2000 1800 CM" Figure 33. Ir spectrum of [Me2Ga(pz")(OCH2CH2NMe2)] 2 Mo(C0 ) 2 (n -CH2SMe) i n cyciohexane. The "^H nmr spectra, c o l l e c t e d i n Table XXII, also show the presence of two isomers i n solution. However, the r e l a t i v e 1 Table XXII, H nmr Data for Mefia x(ppm) a p p r o x . i s o m e r M R R' S -Me H 4 H a R R Ga -Me r a t i o Mo H H 8 .42s 3 . 8 2 t J 6 .26dt,7.16d* 2 • 19d+ ,2. 73d+ 9 .92s, 10.26s 4 8 .67s 3 . 7 3 t T 6.16crt ,7.20d* 1 .96d f .2. 5 8 d T 10 .14s 10.31s 1 Mo H Me 8 .39s 3 . 9 1 t + 6.41d*,7.22d* 2 • 4 9 s , 2. 7 7 d + 7 .45s, 8 .26B 9 .93s, 10.16s 7 (br) (br) 3 .8 5 t T 7 .49s, 8 .22S 10 .08s, 10.19s 1 Mo Me H 8 .40s 4 .20s 6.29d*,7.23d* 7 .46s, 7. 98s 9 .90s, 10.22s 9 8 .70s 7 .38s, 7. 93s 10 .14s, 10.30s 1 Mo Me Me 8 .40s 4 .25s 6.45?, 7.29d* 7 .44s, 7. 98s 7 .44s, 8 .12s 9 .93s, 10.13s 20 (br ) (br) (br) (br) 10 .10s, 10.17s 1 W H H 8 .20s 3 .92t+ 6.36d+ ,6.96d* 2 .14d| ,2. 8 3 d | 9 .94s, 10.31s 4 8 .44s 3 .82t 6.25d*,7.04dt 1 ,90d T ,2. 8 0 d T 10 • 1 8 s , 10.38s 1 W H Me 8 .15s 3 • 9 8 t + 6.41d*,6.96d* 2 .46s, 2. 83d 1" 7 .24s, 8 .27s 9 .95s, 10.21s 6 + (br) 3 . 9 0 t ' 7 .29s, 8 .24s 10 . l i s , 10.24s 1 W Me H 8 .17s 4 .23s 6.37d*,7.Old* 7 .44s, 8. 03s 9 .90s, 10.23s 10 8 .46s 7 .34s, 7. 98s 10 . 1 3 s , 10.33s 1 W Me Me 8 .17s 4 .27s 6.52d*,7.03d* 7 .53s, 8. 01s 7 .25s, 8 .13s 9 .93s, 10.16s 25 10 .10s, 10.21s 1 I measured i n C,D, s o l u t i o n s = s i n g l e t , d = d o u b l e t , t = t r i p l e t ' J = 2HZ + J = 6Hz - 92 -amount of each isomer was subs t a n t i a l l y d i f f e r e n t from that i n d i -cated by the i r data (see Figure 34). On examination of the isomer r a t i o s (Table XXII), i t i s quite evident that the fewer the methyl substituents on the g a l l a t e ligand, the closer the isomer d i s t r i b u t i o n . With R=R'=H, the isomer r a t i o i s ~ 4:1, with R=Me,R'=H or R=H,R'=Me the r a t i o i s = 8:1 and with R=R*=Me the r a t i o i s -~ 20:1. This i s quite d i f f e r e n t from the n i t r o s y l and aryldiazo complexes where the isomer r a t i o depends greatly on the po s i t i o n of methyl substitution i n the ga l l a t e ligand. Although the d i s t i n c t l y d i f f e r e n t r e l a t i v e amounts of isomers derived from i r and nmr data point to conformational isomers, i t i s possible that there i s r e l a t i v e l y too l i t t l e of a second p o s i t i o n a l isomer to be detected by i r measurements, i e . the i r spectra could be in d i c a t i n g conformational isomerism and the •*"H nmr spectra could be indi c a t i n g either conformational or po s i t i o n a l isomerism. A further argument i n favor of conforma-t i o n a l isomers i s the fa c t that well formed c r y s t a l l i n e samples of the pure complexes were e a s i l y obtained (compared to the c r y s t a l l i n e but poorly formed c r y s t a l s of the n i t r o s y l and aryldiazo complexes) and even samples used i n x-ray studies when examined i n solution gave the above i r and nmr r e s u l t s . 2 The synthesis of [MeGa (pz) 3]Mo (CO) 2 ( n -CH2SMe) was under-taken to help c l a r i f y the above observations. In t h i s complex, p o s i t i o n a l isomerism i s not possible and i n addition, a d i f f e r -ent " b i t e " for the sulf u r ligand would not give r i s e to d i s -tinguishable conformers. The H nmr spectrum of th i s compound contains one set of signals, but the i r spectrum i n cyclohexane - 94 -contains 4 v C Q bands. Evidently there are two conformers i n cyclohexane solution - one with the S-Me group oriented towards and one with the S-Me group oriented away from the ga l l a t e ligand. In the related complex, CpMo(CO) 2(n 2-CH 2SMe) (64,66), both the "^H nmr data and i r r e s u l t s ( v C Q tcyclohexane) : 1952, 1869 cm x) point to only one isomer. This suggests that the highly un-favourable arrangement with the S-Me oriented towards the C^H^ ring i s not observed. From the above physical measurements, i t i s cl e a r that the i r spectra (of the 'asymmetric derivatives') show two conforma-tions (S-Me up or down) in solution. However, i t i s not obvious whether the isomers observed i n the nmr represent p o s i t i o n a l or conformational isomers and the fa c t that these spectra were invariant with temperature (-70 to 80°C) did not help resolve t h i s question. Either the interconversion process for the two conformational isomers i s not very f a c i l e , very f a c i l e or the H^ nmr experiment i s showing the presence of two p o s i t i o n a l isomers i n C,D, solution. D O The s o l i d state structures of [Me 2Ga(pz)(OCH 2CH 2NMe 2)] Mo (CO) 2(r, 2-CH 2SMe) and [Me2Ga (pz") (OCH2CH2NMe2) ] Mo (CO) 2 ( r , 2 -CH2SMe) were determined by Dr. S. Rettig and are shown i n Figure 35. The coordination about the molybdenum atom i n both mole-2 cules can be regarded as d i s t o r t e d octahedral with the n -Cr^SMe ligand occupying one coordination s i t e or as hepta-coordin-2 ated with a bidentate n -CH2SMe ligand. In both structures, the 2 TI -CH2SMe ligand was found to be opposite the pyrazolyl nitrogen and there was no evidence for a second isomer. As with [Me 2Ga(pz")(OCH 2CH 2NH 2)]Mo(CO) 2(n 3-C 7H 7), there are s i g n i f i c a n t differences between the pairs of M-CO and C-0 distances, the Mo-CO distances trans to oxygen being shorter than those trans o to nitrogen by an average of 0.055 A. As expected, the Mo-NMe2 o bond length (2.399(5) A) i n the two 'CH2SMe' derivatives i s o s i g n i f i c a n t l y longer than the Mo-NH2 bond length (2.285(2) A) in the 'C^ H.,' derivative (54) . Figure 35. Cryst a l structures of [Me 2Ga(pz)(OCH 2CH 2 NMe 2)]Mo(CO) 2(n 2-CH 2SMe) and [Me2Ga(pz") (OCH2CH2NMe2)]Mo(CO) 2 (r)2-CH2SMe) . 2 The c r y s t a l structure of CpMo(CO) 2(n -CH2SMe) (63) has also been determined and the Mo(CH2SMe) system i n a l l three complexes i s very s i m i l a r . In each case, the 'CH^-S' ring d i s -cs tance i s =0.05 A shorter than the S-CH^ single bond distance (1.75 vs 1.80 A). This 'shortening' of the CH2~S bond corres-ponds to only a minimum amount of double bond character and the best description of the MCS system i s that of a three-membered metallocyclic r i n g containing an M-C a bond and lone pair - 96 -donation by S to the metal. 3.3.3.6 Trends i n LM(CO) 2T compounds Mass s p e c t r a were obtained f o r a l l the LM(CO) 2T compounds d i s c u s s e d i n t h i s chapter and some of t h i s data i s presented i n Tables XXIII and XXIV. In a l l c a s e s , the parent i o n was observed f o l l o w e d by s u c c e s s i v e l o s s of a methyl and two c a r b o n y l groups. In the cases of T = C^H 7, N 2 p h and NO, t h i s was f o l l o w e d by l o s s o f T. However i n the cases of T = C-.Hr and CH-SMe, t h i s was J o 2. followed by l o s s of propene and d i m e t h y l s u l p h i d e r e s p e c t i v e l y (the l o s s of d i m e t h y l s u l p h i d e was not seen i n those complexes i n c o r p o r a t i n g the 'OCH^H^H^ moiety) . In the m a j o r i t y of the complexes, the s t r o n g e s t s i g n a l was due to the P-2C0 + i o n or the P-2C0-Me + i o n . The one e x c e p t i o n o c c u r r e d i n the s p e c t r a o f some o f the ' a l l y l ' d e r i v a t i v e s where the s i g n a l due to the P-2C0-'propene' i o n was e x c e p t i o n a l l y s t r o n g . In these c a s e s , the s i g n a l due to the P-2C0 + i o n was the second s t r o n g e s t s i g n a l . I t was a l s o n o t i c e d t h a t the s i g n a l due to the P-CO + i o n was s i g n i f i c a n t l y s t r o n g e r i n the s p e c t r a of the tungsten compounds compared with the corres p o n d i n g s i g n a l i n the s p e c t r a o f the molybdenum analogues. In the s o l i d s t a t e a l l the prepared compounds c o u l d be handled i n a i r f o r s h o r t p e r i o d s of time without n o t i c e a b l e decomposition and the order of s t a b i l i t y (determined by v i s u a l i n s p e c t i o n ) was found to be NO>C 3H 5 ~ C 4 H 7 ~ C 7H 7>CH 2SMe>N 2Ph and W>Mo. The tungsten n i t r o s y l compounds were s u f f i c i e n t l y s t a b l e i n s o l u t i o n to permit r e c r y s t a l l i z a t i o n i n a i r . Table XXIII. Mass Spectral Data of [Me 2Ga(pz")(OCH 2CH 2NMe 2)] Mo(CO) 2T* "~ T= s i g n a T \ ^ ^ NO N 2Ph C 3 H 5 C 7H ? CH2SMe P 15.5 8.8 16.4 54.9 29.6 P-Me 15.5 4.4 5.2 trace 4.7 P-CO 50.7 16.6 13.6 trace 19.1 P-Me-CO trace trace trace 0 trace P-2C0 83.8 12.3 4.4 100 100 P-2C0-Me 54.7 100 8 16.9 70.6 P-T 0 0 0 67.8 0 P-2C0-T 100 ? 0 0 P-2C0-T(H) 0 •p 100 ? 71.8 Numbers i n table represent r e l a t i v e i n t e n s i t i e s . - 98 -Table XXIV. Mass Spectra of [ Me2Ga(pz") (OCH2CH2NMe2>] W(CO)2T* signal^"--^^ NO N 2Ph C 3H 5 C 7H ? CH2SMe P 30.5 18.3 31.4 48.1 49.5 P-Me 14.7 2.9 7.9 trace trace P-CO 69.5 14.6 35.0 38.5 60.5 P-Me-CO 0 0 4.7 trace 11.0 P-2CO 68.4 25.0 100 100 15.3 P-2CO-Me 100 100 20.4 19.2 100' P-T 0 0 0 44.2 0 P-2CO-T 11.7 23.7 0 96.2 0 P-2C0-T(H) 0 0 94.3 0 76.3 * Numbers i n table represent r e l a t i v e i n t e n s i t i e s . - 99 -Changing the group T also affected the s o l u b i l i t i e s of the r e s u l t i n g compounds. The r e l a t i v e degree of s o l u b i l i t y (in hydrocarbon solvents) was found to be N2Ph>C3H5>C7H7>CH2SMe>NO and Mo>W. In addition, those compounds incorporating the pz" group were s l i g h t l y more soluble than those incorporating the pz group, and those compounds incorporating the 'OCH2CH2NMe2' moiety were considerably more soluble than those incorporating the 'OCH2CH2NH2' moiety. The carbonyl stretching frequencies of some DMo(CO)2T compounds, where D = a tridentate ligand and T = a three electron donor are l i s t e d in Table XXV. Analysis of the data shows that the compounds incorporating the ligand L(R=R'=Me) exhibit the lowest stretching frequencies implying that t h i s ligand donates a greater amount of electron density to the central metal (and/or accepts the least amount of electron density v i a TT-backbonding) . In addition, the carbonyl frequencies appear in the order N0> N 2 P h > C 3 H 5 ~ C 4 H 7 C?H7>CH2SMe indi c a t i n g that NO i s the strongest TT acceptor and CH2SMe i s the weakest TT acceptor i n t h i s s e r i e s . 3.4 Summary Manganese tri c a r b o n y l derivatives were prepared by reaction of Na +L with manganese pentacarbonyl bromide and the ' i s o -electronic' chromium, molybdenum and tungsten t r i c a r b o n y l anions + — were prepared by reaction of Na L with (py)^Cr(CO)^, (CH^CN)^ Mo(CO)3 and (CH 3CN) 3W(CO) 3 respectively. In each case, the ligand L was coordinated f a c i a l l y . The molybdenum and tungsten tricarbonyl anions could be reacted with various e l e c t r o p h i l e s Table XXV. " Carbonyl S t r e t c h i n g Frequencies f o r some DMo(CO):)T Complexes (cm ) N0 a N 2 P h b C 3 H 5 b C 7 H ? b CH 2SMe b Cp 2020 1945 (67) 2000 1928 (36) 1970, 1903, 1963 1873 (65) 1966, 1911, 1960 1896 (60) 1952 (65) 1869 H B ( p z ) 3 2025 1933 (35) 1994 1904 (35) 1959 1874 (33) 1953 1874 (32) — MeGa(pz) 3 2019 1922 (68) 1990 1910 (68) 1948 1860 (11) 1938 1859 (68) 1955, 1948 (*) 1835, 1822 L,R=R'=Me 2015 1917 (*•)• 1992 1910, (*) 1888 1931 1843 (*) 1928 1849 (*) 1945, 1921 (*) 1810, 1806 . a CH 2C1 2 s o l u t i o n b cyclohexane s o l u t i o n * t h i s work - 101 -to produce a number of compounds of the general formula LM(C0) 2T, where T i s a three-electron donor ligand, and i t was found that the s t e r e o s e l e c t i v i t y of t h i s decarbonylation reaction (position of substitution) depended greatly on the nature of the ligand T. In the case of T = ' a l l y l ' (n 3 ) only one p o s i t i o n a l isomer (sub-s t i t u t i o n opposite pyrazolyl nitrogen) was observed and i n the 3 case of T = C-yH-y (n ) only one isomer (substitution opposite amino nitrogen) was observed i n the majority of the complexes (z 15% of a second isomer (substitution opposite py r a z o l y l nitrogen) was observed i n the complexes incorporating the s t e r i c a l l y l e a s t demanding ligand L, R=R'=H). In the case of 2 T = CH2SMe (n ), the evidence f o r p o s i t i o n a l or lack of p o s i t i o n -a l isomers was not conclusive. The p r i n c i p a l p o s i t i o n of sub-s t i t u t i o n was opposite the pyrazolyl nitrogen and i f there was a second p o s i t i o n a l isomer, i t was i n a very minor amount. F i n a l l y i n the cases of T = NO (n "^) or N 2Ar (n'S , two p o s i t i o n a l isomers (substitution opposite pyrazolyl nitrogen and amino nitrogen) were present and the r a t i o of these isomers was de-pendent on the po s i t i o n of the substituents on the ligand L but independent of the metal M. A l l the complexes prepared were found to be moderately stable i n a i r and could be stored under N 2 or i n vacuo for prolonged periods of time without decomposition. They were reasonably soluble i n hydrocarbon solvents and did not react with CH 2C1 2 or CHC1.J. Although mass spectra were e a s i l y obtained for a l l the complexes, none of the complexes was suf-f i c i e n t l y v o l a t i l e to be sublimed (T > 150°C). - 102 -S e v e r a l o f the complexes e x h i b i t s t e r e o c h e m i c a l n o n r i g i d i t y i n s o l u t i o n . The t r i c a r b o n y l anions LM(CO) 3~ (R=R'=Me; M = Cr, Mo, W) undergo a process which e f f e c t i v e l y exchanges the ' s i t e s ' of the two methyl groups on the amino n i t r o g e n atom and a l s o the s i t e s o f the two methyl groups on the g a l l i u m atom. A s i m i l a r p r o c e s s , i n s o l u t i o n , was observed f o r the complex [Me 2Ga(pz) (OCH 2CH 2NMe 2)]Mo(CO) 2(n 3-C 4H 7). In the C ? H 7 d e r i v a t i v e s , a l l the c y c l o h e p t a t r i e n y l r i n g protons were e q u i v a l e n t a t r t , but at 'low' temperature, a l l seven protons were found t o be chem-i c a l l y d i f f e r e n t . - 103 -CHAPTER IV PYRAZOLYL DERIVATIVES OF METAL NITROSYLS 4.1 I n t r o d u c t i o n The p y r a z o l i d e anion (pz ) can a c t as a monodentate o r an exobidentate l i g a n d . However, i n p r a c t i c e the p y r a z o l y l group i s such a good exobidentate l i g a n d t h a t when a s u i t a b l e a c c e p t o r i s not immediately a v a i l a b l e , a c o o r d i n a t i o n polymer i s formed (69). When s u i t a b l e 'end-capping' groups are a v a i l a b l e , d i m e r i c molecules are u s u a l l y formed and these i n c l u d e [M(pz ) J 2 where M = R h ( C O ) 2 (70), Rh(C0D) 2 (70), P d ( a l l y l ) (70), and F e ( C 0 ) 3 (71). In a d d i t i o n , two examples of groups b r i d g e d by t h r e e p y r a z o l y l m o i e t i e s are known - namely [(CO)^Mn(pz)^Mn(CO)^] (72) and [ (Et) B(pz) 3 B ( E t ) ] + (72). Although c a r b o n y l c o n t a i n i n g m o i e t i e s have been used f r e -q u e n t l y as 'end-capping' groups, t h e r e are as y e t no examples of t h i s type of molecule i n v o l v i n g n i t r o s y l b e a r i n g 'end-capping' groups. T h i s chapter d e s c r i b e s the p r e p a r a t i o n o f s e v e r a l ' p y r a z o l y l - n i t r o s y l ' d e r i v a t i v e s and d e t a i l s the r e a c t i o n o f these molecules w i t h v a r i o u s n u c l e o p h i l e s . P a r t s o f t h i s work have been p u b l i s h e d p r e v i o u s l y (73,74,75). 4.2 Experimental 4.2.1 S t a r t i n g M a t e r i a l s Ni(NO)I, F e ( N 0 ) 2 I and C o ( N O ) 2 l were prepared by the method of Haymore and Feltham (76) and 3 - 5 - d i - t e r t - b u t y l p y r a z o l e - 104 -prepared by a standard route (77). P y r i d i n e was o b t a i n e d from K and K Chemicals and d i s t i l l e d from BaO b e f o r e use. Et^N +Br was o b t a i n e d from Eastman Organic Chemicals and Me^N was o b t a i n e d from Matheson of Canada L t d . . These were used as s u p p l i e d . 4.2.2 Reaction o f Ni(NO)I w i t h Sodium 'Pyrazolide' 2Ni(NO)I + 2 N a + ( ' p z ' ) ~ — ™ £ _ > [ N i ( ' pz ') (NO) ] 2 + 2NaI (25) To Ni(NO)I (2.156 g; 10 mmol) d i s s o l v e d i n THF was added Na +(pz") (1.18 g; 10.0 mmol) i n the same s o l v e n t . A f t e r s t i r -r i n g the r e s u l t i n g b l u e s o l u t i o n f o r 1 h, s o l v e n t was removed i n vacuum and the r e s u l t i n g green s o l i d S o x h l e t e x t r a c t e d w i t h ~ 125 ml of benzene f o r 22 h. The r e s u l t i n g green s o l u t i o n , on c o o l i n g , d e p o s i t e d a dark green c r y s t a l l i n e m a t e r i a l which was i d e n t i f i e d as [ ( O N ) N i ( p z " ) 2 ] 2 N i (0 .05 g; 3.2% of pz" groups). E v a p o r a t i o n o f s o l v e n t from the remaining green s o l u t i o n gave dark green needles o f [Ni(pz") (NO)] 2 (1.01 g; 55%). The a n a l o -gous [Ni (pz) (NO) ] 2 and [Ni (pz*") (NO) ] 2 (pz f c = 3 , 5 - d i - t e r t - b u t y l -p y r a z o l i d e ) dimers were prepared i d e n t i c a l l y by r e a c t i n g the a p p r o p r i a t e sodium 'pyrazolide' w i t h Ni(NO)I. Y i e l d s were 65% and 55% r e s p e c t i v e l y . However, i n c o n t r a s t to the r e a c t i o n w i t h sodium 3 , 5 - d i m e t h y l p y r a z o l i d e , i n these two r e a c t i o n s the dimers were the onl y products i s o l a t e d . 4.2.3 P r e p a r a t i o n of [ C o ( p z " ) ( N O ) 2 J 2 2Co(NO) 2I + 2 N a + ( p z " ) " — ™ F _ > [ C o ( p z . . ) ( N 0 ) ] + 2NaI (26) Co(NO) 2I (0.492 g; 2.0 mmol) was dissolved i n THF and a solution of Na +(pz")~ (0.236 g; 2.0 mmol) i n the same solvent added. After s t i r r i n g the mixture for 1 h, solvent was removed i n vacuo and the s o l i d residue extracted with several portions of benzene. F i l t r a t i o n followed by evaporation of the f i l t r a t e gave large black c r y s t a l s which were washed sparingly with heptane (yield 0.2 g; 46%). 4.2.4 Preparation of [Fe (pz") (NO) ^  ] 2 2Fe(NO) 2I + 2Na +(pz")~ —?JL_> [Fe (pz") (NO) ^  2 + 2NaI (27) This complex was prepared from Fe(NO) 2I and Na +(pz") using a sim i l a r procedure to that described for the analogous cobalt complex (4.2.3). Black c r y s t a l s were obtained i n 75% y i e l d . 4.2.5 Reaction of [Ni('pz') (NO)] 2 with Nucleophiles [Ni('pz') (NO)] 2 + 2B > [Ni ( ' pz •) (NO) (B) ] 2 (28) (a) B = PPh 3 and AsPh 3 [Ni(pz")(NO)] 2 (0.184 g; 0.5 mmol) was dissolved i n THF and s o l i d PPh 3 (0.262 g; lmmol) added to the solution. The i n i t i a l dark green color of the solution gradually changed to a dark blue color. After s t i r r i n g the reaction mixture overnight the solvent was removed i n vacuo. The re s u l t i n g s o l i d was ex-tracted with benzene and the crude material obtained from the benzene solution was r e c r y s t a l l i z e d from benzene/THF to give - 106 -very dark blue c r y s t a l s of pure product (0.373 g; 84%). The AsPh 3 complex, [Ni (pz" ) (NO) (AsPh 3) ] 2 was prepared s i m i l a r l y and was is o l a t e d as blue-green c r y s t a l s from benzene solvent i n 87% y i e l d . The corresponding compounds containing unsubstituted pyrazolyl bridging moieties, v i z . [Ni(pz)(NO) ( P P h 3 ) ] 2 and [Ni(pz)(NO)(AsPh 3)] 2 ware prepared by analogous reactions and were i s o l a t e d as purple-blue c r y s t a l s (yield 47%) and dark blue c r y s t a l s (yield 52%) respectively. (b) B = %(Ph 2PCH 2CH 2PPh 2) [Ni(pz") (NO)] 2 (0.202 g; 0.55 mmol) was dissolved i n THF and diphos (0.220 g; 0.55 mmol) i n the same solvent added to the solution. The dark green solution of the dimer immediately became dark blue. After s t i r r i n g for about 1 h the solvent was removed i n vacuo. The dark blue s o l i d obtained was r e c r y s t a l -l i z e d from THF/benzene to give the pure product, a blue c r y s t a l -l i n e material, i n high y i e l d . (c) B = pz"H [Ni(pz")(NO)] 2 (0.184 g; 0.50 mmol) reacted with 3,5-dimethylpyrazole (0.096 g; 1.00 mmol) i n THF solution to give a blue solution which on work-up gave a blue c r y s t a l l i n e s o l i d (0.186 g; 67%). This s o l i d product, [Ni(pz") (NO) (pz"H)] 2 , appeared i n d e f i n i t e l y a i r - s t a b l e at room temperature and solu-tions, kept under a nitrogen atmosphere, remained blue. - 107 -(d) B = p y r i d i n e A s o l u t i o n (green c o l o r ) o f the [ N i ( p z " ) (NO)] 2 w a s t r e a t e d w i t h an excess o f p y r i d i n e . The s o l u t i o n t u r n e d b l u e and on removal o f s o l v e n t and excess l i g a n d a b l u e s o l i d was o b t a i n e d . At tempted r e c r y s t a l l i z a t i o n by - e v a p o r a t i o n of benzene s o l u t i o n gave o n l y the green dimer s t a r t i n g m a t e r i a l . Even t h e c r u d e b l u e s o l i d out o f THF s l o w l y t u r n e d g r e e n , i n d i c a t i n g ready l o s s o f the p y r i d i n e l i g a n d . Benzene (^H nmr) and c y c l o h e x a n e ( i r ) s o l u t i o n s o f the c r u d e p r o d u c t changed c o l o r f rom b l u e to green on s t a n d i n g , even under an atmosphere o f n i t r o g e n . The i r spec t rum o f a N u j o l m u l l sample o f the ' b l u e s o l i d ' showed t h e p r e s e n c e o f c o o r d i n a t e d p y r i d i n e w i t h c h a r a c t e r i s t i c bands a t 1600, 635, and 436 c m - 1 ( 78 ,79 ) . The v N Q r e g i o n showed two b a n d s , a medium s h o u l d e r a t ~ 1800 cm 1 and a s t r o n g main band a t 1740 c m - 1 . The band a t 18 00 c m - 1 c o u l d w e l l be due t o the p r e s e n c e o f f r e e dimer i n the sample caused b y . l o s s o f p y r i d i n e b e f o r e and d u r i n g sample p r e p a r a t i o n . The nmr i n C..D,. showed 6 b one s i g n a l f o r the 3,5 Me groups a t t a c h e d to the p y r a z o l y l m o i e t i e s b u t the p r e s e n c e o f ' f r e e 1 d imer i s a g a i n e v i d e n t from an i n t e g r a t i o n of the v a r i o u s s i g n a l s . The ready l o s s o f p y r i -d i n e from the b l u e s o l i d a d d u c t hampered a l l a t tempts to o b t a i n a r e a s o n a b l e a n a l y t i c a l a n a l y s i s f o r the compound. (e) B = Me 3 N The dimer [ N i ( p z " ) ( N O ) ] 2 i n THF s o l u t i o n d i s p l a y e d a c o l o r change from green t o b l u e on t rea tment w i t h Me^N a t low temp-e r a t u r e (~ - 7 8 ° C ) . A t room temperature the s o l u t i o n t u r n e d - 108 -green and on removal o f s o l v e n t s and v o l a t i l e s the s t a r t i n g mat-e r i a l was recovered. These o b s e r v a t i o n s i n d i c a t e a p o s s i b l e weak c o o r d i n a t i o n of the amine a t low temperature i n s o l u t i o n . (f) B = CO and d i p h e n y l a c e t y l e n e Attempted c o o r d i n a t i o n of carbon monoxide or d i p h e n y l -a c e t y l e n e to the dimer s p e c i e s d i d not l e a d to i n d i c a t i v e c o l o r changes i n THF s o l u t i o n s of the dimer. On removal o f s o l v e n t and unreacted 'ligands' the dimer was q u a n t i t a t i v e l y r ecovered i n both experiments. P h y s i c a l Data f o r the 'dimer complexes' (Prep. 4.2.2-4.2.5) are l i s t e d i n Table XXVI. 4.2.'6 Reaction o f [M(pz")(NO) 2 ]_ 2 (M = Co,Fe) w i t h PPh 3_ When [Fe(pz") ( N O ) 2 ] 2 was s t i r r e d together w i t h PPh^ i n benzene a t r t , no r e a c t i o n o c c u r r e d (as determined by i r measure-ments) . However on h e a t i n g to r e f l u x , the c o l o u r of the s o l u t i o n changed from dark brown to p a l e y e l l o w and a s o l i d was p r e c i p i -t a t e d . T h i s s o l i d was found t o be i n s o l u b l e i n THF and CH 2C1 2 and was not i n v e s t i g a t e d f u r t h e r . When [ C o ( p z " ) ( N O ) 2 J 2 was s t i r r e d together w i t h PPh^, no r e a c t i o n o c c u r r e d - a t r t or a t r e f l u x temperature. 4.2.7 P r e p a r a t i o n o f Et^N* [ ( O N ) N i ( p z " ) 2 ( I ) (Ni(NO)]" 2Ni(NO)I + 2 N a + ( p z " ) ~ +. E t 4 N + C l ~ — T H F > NaCl + N a l + E t 4 N + [ ( 0 N ) N i ( p z " ) 2 ( I ) N i ( N O ) ] ~ (29) . T a b l e X X V I . Compound An a l y s i s * VN0(cm" -1) T(ppm)(CGDC solution) * M R B c H N Cyclohexane Nu j o l R H L N i H 23. 23. 4 1 2.0 1.9 26. 27 . 5 0 1817 1815 1 . 34dt 3.28t Ni Me 32 . 32. 9 7 3.9 3.8 22. 22. 9 9 1800 1800 7 .44s 3.59s t r i m e t a l l i c complex 39. 39. 0 0 4.7 4.6 22. 22. 8 7 1809 i N i t-Bu 49. 49. 0 3 7.3 7.2 16. 15. 0 7 1788 1779 8 .18s 3.48s Co Me NO 28. 28. 2 0 3.3 3.3 26. 26. 0 2 1822, 1750 8 .00s 4. 04s Fe Me NO 28. 28. 5 5 3.3 3.3 25. 26. 8 5 1800, 1785 1735, 1720 1802, 1750, 1780 1710 Ni Me PPh 3 61. 61. 9 9 5.0 5.0 9. 9. 7 4 1804, 1758 1728 7 .47s 3.46s 2, . 64m, 2. 96m N i Me AsPh 3 56. 56. 4 4 4.5 4.5 8. 8. 3 6 1805, 1770 1762 7 .44s 3. 52s 2. .61m, 2. 93m Ni H PPh 3 60. 60. 5 3 4.4 4.3 9. 10. 8 0 1807, 1720 1718 1 .88dt 3.55tt 2. . 52m, 3. 06m Ni H AsPh 3 54. 54. 0 6 3.9 3.9 9. 9. 0 1 1816, 1772 1768 1 .45dt 3.26tt 2. . 63m, 2. 97m Ni Me PPh,-C H 2 -56. 56. 7 4 4.9 4.9 10. 11. 7 0 i 1722 7 .51s 3. 34s 2. 8. .74m, ,23m 3. 00m Ni Me pz"H 42. 42. 5 9 5.3 5.4 24 . 25. 7 0 1800, 1756 1755 7 .88br 3.88br 4. 7. . 15s, ,74s 7. 20s Ni Me py 1805, 1700 1740, 1800sh 7 .29s 3.41s 3. , 08br * i = i n s o l u b l e , s=singlet, d=doublet, t = t r i p l e t , m=multiplet, br=broad t J^2Hz * Found (%)/Calcd- (%) - 110 -A THF solution of Na +(pz")~ (0.236 g; 2.0 mmol) was added to a s t i r r e d THF solution of Ni(NO)I (0.431 g; 2.0 mmol). Solid E t 4 N + C l (0.165 g; 1.0 mmol) was added to the r e s u l t i n g blue solution and the mixture s t i r r e d for 24 h. The solution was f i l t e r e d and the solvent removed i n vacuo. Extraction with CH^C^/ f i l t r a t i o n , followed by evaporation of solvent gave blue c r y s t a l s of product. These were washed with methanol f o l -lowed by ether. 4.2.8 Preparation of Et ^ N+ [(ON) Ni (pz") (Cl) Ni (NO)] + — TT4P + — [Ni(pz") (NO) ] 2 +.Et4N Cl ±f^—> Et 4N [(ON) Ni (pz " ) 2 (Cl) Ni (NO)] (30) [Ni(pz") (NO)] 2 (0.184 g; 0.5 mmol) was dissolved i n THF and a methanol solution of E t 4 N + C l (0.08 3 g; 0.5 mmol) added. The green dimer solution immediately turned blue. Evaporation of the solvent gave blue c r y s t a l s which were washed successively with methanol and ether. The analogous bromo compound was prepared s i m i l a r l y from the dimer and Et 4N +Br . The pyrazolyl bridged halogen deriva-tives were synthesized u t i l i z i n g the [Ni(pz)(NO)]^ dimer as start i n g material. 4.2.9 Preparation of Na +[(ON)Ni (pz") 3 N i (NO)] " 2Ni(NO)I + 3 N a + ( p z " ) ~ — N a + [ (ON)Ni (pz" ) 3 N i (NO)] " + 2NaI (31) A THF solution of Na +(pz")~ (0.354 g; 3.00 mmol) was - I l l -added to a s t i r r e d solution of Ni(NO)I (0.431 g; 2.0 mmol). Solvent was removed i n vacuo and the o i l y residue extracted with benzene and f i l t e r e d immediately. On evaporation of solvent from the r e s u l t i n g solution, lustrous blue c r y s t a l s of the pro-duct formed. Yields and physical data for the 'anionic n i c k e l deriva-tives* (Prep. 4.2.7-4.2.9) are l i s t e d i n Table XXVII. 4.2.10 Reaction of [Fe (pz") (NO) 2 ] _ 2 with I 2 _ [Fe(pz") (NO) 2 ] 2 + I 2 > 2'Fe(pz") (NO) 2 I ' (32) [Fe(pz")(NO) 2] 2 (0.105 g; 0.5 mmol) was dissolved i n d i e t h y l ether and a solution of 1^ (0.063 g; 0.5 mmol) i n the same added dropwise. The dark brown solution slowly became l i g h t brown and a dark s o l i d was p r e c i p i t a t e d . This s o l i d was found to be insoluble in CH 2C1 2 or THF-. Yie l d (0.08 g; 50%). Calcd. for Fe(pz")(NO) 2I : C, 17.8; H, 2.1; N, 16.5. Found: C, 17.8; H, 1.7; N, 16.2. v N Q (cm" 1): 1730, 1791 (Nujol). 4.3 Results and Discussion 4.3.1 Pyrazolyl Bridged Metal N i t r o s y l s The dark green pyrazolyl bridged n i c k e l n i t r o s y l dimers were prepared by the reaction of sodium 'pyrazolide' with n i c k e l n i t r o s y l iodide and the expected dimeric nature of these com-plexes was confirmed by mass spectrometry, i n each case, the highest observed m/e was due to the parent ion (20%) and the strongest signal was due to P-2NO+(100%). Signals observed Table XXVII. P h y s i c a l Data f o r M Compound Ana l y s i s d vNO. % (cm"1) Y i e l d Nujol T(ppm)(dg- acetone solutions)* M X R C H N M H R Et.N 4 I H 29.5 29.6 4.5 4.6 17.1 17.2 40 1770 6. 47q, 8.56tt b 3.45t C 1.60d c E t 4 N Br H 31.8 32.2 5.0 4.9 18.8 18.3 60 1762 6. 48q, 8.55tt b 3.43t c 1.62d c Me .N 4 CI H 28.5 4.3 23.0 45 1754 6. 58s 3.43t C 1.64d c 1 28.5 4.3 23.3 1—1 I—1 to 7.50s Et .N 4 I Me 34.7 34 .6 5.5 5.5 15.7 15.7 61 1752 6. 52q, 8.57tt b 3.85s Et.N 4 Br Me 37.6 37.4 6.0 5.9 17.0 17.0 60 1749 6. 50q, 8.56tt b 3.84s 7.52s Et.N 4 CI Me 40.5 40.5 6.5 6.4 18.4 18.4 64 1742 6. 48q, 8.55tt b 3.84s 7.54s Na N 2C 5H ? Me 43.8 43.8 5.9 5.9 17 .8 17 .8 75 1760 - 3.82s 7.65s * s = s i n g l e t , d = doublet t = t r i p l e t . q = quartet, t t = t r i p l e t of t r i p l e t s 2THF of r e c r y s t a l l i z a t i o n T t h f = 6.30m, 8.15 m HC-C-N 1 4 = 2 H Z ' JJCCH = 7 H Z C J = 2Hz d Found(%)/Calcd.(%) - 113 -were due t o P - N O + (35%), ; p - 2 N 0 - R C N + (20%) and P-2NO-2RCN + (35%). The l o s s o f RCN groups i n t h i s type o f complex has been o b s e r v e d p r e v i o u s l y i n t h e mass s p e c t r a o f [ F e ( * p z ' ) ( C O ) (71) . Of p a r t i c u l a r r e l e v a n c e i s t h e absence o f any N i 2 + s i g n a l . Assuming t h a t t h e r e i s no i n t e r a c t i o n between the m e t a l c e n t r e s ( i . e . no m e t a l - m e t a l b o n d ) , each n i c k e l atom would have a n o n -i n e r t gas c o n f i g u r a t i o n of 16 e l e c t r o n s . In s p i t e o f t h i s u n -f a v o r a b l e e l e c t r o n i c c o n f i g u r a t i o n , these dimers were found to be a i r s t a b l e s o l i d s . S o l u t i o n s , however, r a p i d l y l o s e t h e i r c o l o u r on exposure to a i r w i t h c o n c o m i t a n t l o s s o f the v N Q band i n t h e i r i r s p e c t r a and d e p o s i t i o n of a w h i t e s o l i d . The i r s p e c t r a ( cyc iohexane and N u j o l ) o f the dimers showed one v > T ^ band the p o s i t i o n o f which was v e r y s e n s i t i v e to the NO n a t u r e o f t h e s u b s t i t u e n t s on the 3 and 5 p o s i t i o n s o f the p y r a z o l y l r i n g . By ' c h a n g i n g ' t h e s e s u b s t i t u e n t s from H t o Me to t - b u t y l , t h e r e i s a s i g n i f i c a n t s h i f t to lower wave numbers and t h i s can be s a t i s f a c t o r i l y e x p l a i n e d by i n d u c t i v e e f f e c t arguments . The a r o m a t i c n a t u r e o f the p y r a z o l y l r i n g d i c t a t e s e i t h e r a p l a n a r o r a b o a t c o n f o r m a t i o n f o r the c e n t r a l N i 2 N 4 r i n g and a c r y s t a l s t r u c t u r e d e t e r m i n a t i o n (done by D r . S. R e t t i g ) o f [ N i ( p z " ) ( N O ) ] 2 (see F i g u r e 36) demonstra ted the former s i t u a t i o n . The c o o r d i n a t i o n geometry around the n i c k e l atom i s d i s t o r t e d t r i g o n a l p l a n a r w i t h N - N i - N O a n g l e s of 128.3(2) and 1 2 3 . 3 ( 2 ) ° and a N ( 1 ) - N i - N ( 2 ) * a n g l e of 1 0 8 . 4 ( 1 ) ° . The n o n - e q u i v a l e n t N - N i - N O a n g l e s are m i r r o r imaged by the n o n - e q u i v a l e n t N i - N ( p y r a z o l y l ) d i s t a n c e s o f 1.922(3) and 1.880(3) A . Such - 114 -F i g u r e 36. M o l e c u l a r s t r u c t u r e of [Ni (pz" ) (NO)] 2 . d i f f e r e n c e s between c h e m i c a l l y e q u i v a l e n t bond l e n g t h s and angles have been observed i n other {NiNO} x® complexes (80,81,82) and apart from s t e r i c f a c t o r s , no reasonable e x p l a n a t i o n can be g i v e n . The n i t r o s y l group i s l i n e a r l y c o o r d i n a t e d (Ni-N-0 = 178.9(4)°) wi t h Ni-N and N-0 bond d i s t a n c e s of 1.616(4) and ° o 1.158(4) A r e s p e c t i v e l y . The N i - N i ' s e p a r a t i o n of 3.673(1) A p r e c l u d e s any d i r e c t n i c k e l - n i c k e l i n t e r a c t i o n . However, the o u n u s u a l l y long N(pz)-N(pz) d i s t a n c e of 1.463(4) A (values of O 1.33-1.39 A are u s u a l l y observed (84, and r e f e r e n c e s t h e r e i n ) suggests the p o s s i b i l i t y of a piT-dTr i n t e r a c t i o n between the p y r a z o l y l TT system and the f i l l e d d o r b i t a l s on N i , an i n t e r -a c t i o n t h a t n e c e s s i t a t e s the 'complete p l a n a r i t y ' of t h i s mole-c u l e . In the r e a c t i o n of sodium d i m e t h y l p y r a z o l i d e w i t h n i c k e l n i t r o s y l i o d i d e , a second product was i s o l a t e d i n low y i e l d . T h i s was i d e n t i f i e d by mass spectrometry and m i c r o - a n a l y s i s to - 115 -be [(ON)Ni ( p z " ) ] 2 N i . The mass spectrum of t h i s compound d i s -p layed s t r o n g s i g n a l s due to the t r i m e t a l l i c parent i o n , the parent i o n minus one NO group and the parent i o n minus two NO groups ( s t r o n g e s t s i g n a l ) . In a d d i t i o n , a s i g n a l c o r r e s p o n d i n g to the doubly charged parent i o n minus two NO groups was observed. S u r p r i s i n g l y i n a l l samples s t u d i e d , a s e r i e s of weak s i g n a l s a t t r i b u t a b l e to [Ni(pz") (N0)] 2 was a l s o observed. Since there i s no evidence f o r the presence of the dimer complex i n the a n a l y t i c a l l y pure t r i m e t a l l i c compound, these s i g n a l s must a r i s e from some rearrangement process t a k i n g p l a c e i n the mass s p e c t r o -meter . Although the r a t h e r low y i e l d of t h i s compound prevented a d e t a i l e d i n v e s t i g a t i o n of i t s expected acceptor p r o p e r t i e s , a c o l o u r change from green t o blue was observed when t h i s compound was r e a c t e d w i t h P^Me)^. F u r t h e r c h a r a c t e r i z a t i o n was accomp-l i s h e d by an x-ray study (by Dr. S. R e t t i g , see F i g . 3 7 ) . F i g u r e 3 7 . M o l e c u l a r s t r u c t u r e of [(ON)Ni(pz")_]«Ni. - 116 -The m o l e c u l e c o n s i s t s o f a c e n t r a l square p l a n a r n i c k e l ( I I ) c o o r d i n a t e d to f o u r p y r a z o l y l n i t r o g e n s and two o u t e r t r i g o n a l p l a n a r n i c k e l ( I ) c e n t r e s c o o r d i n a t e d by a n i t r o s y l group and two p y r a z o l y l n i t r o g e n s . E a c h N i 2 N ^ c h e l a t e r i n g was found to assume d i s t o r t e d boat c o n f o r m a t i o n s ( i n o p p o s i t e d i r e c t i o n s ) w i t h the o v e r a l l geometry s i m i l a r to t h a t o b s e r v e d i n the com-p l e x e s [ M e 2 G a ( p z ) 2 ] 2 M where M = N i (32) and Cu (84) . The c e n t r a l N i atom has n e a r l y i d e a l square p l a n a r c o o r d i n a t i o n geometry w i t h u n i q u e N - N i - N a n g l e s o f 89.70(8) and 90.30(8) ° and a mean N i - N o d i s t a n c e o f 1.905(1) A . The c o o r d i n a t e d n i t r o s y l group i s s l i g h t l y bent ( N i - N - 0 = 1 6 8 . 9 ( 3 ) ° , N i - N = 1.625(3) and N-0 = o 1.153 A) and the two p y r a z o l y l n i t r o g e n - N i ( t r i g o n a l ) d i s t a n c e s o are a p p r o x i m a t e l y e q u a l (1.922(3) A ) . I t i s noteworthy t h a t t h e r e l a t e d compound [ M e 2 G a ( p z " ) 2 ] N i , where a Me 2 Ga group r e p l a c e s a N i - N O group c o u l d not be p r e p a r e d (8 3 ) . E v i d e n t l y , the s t e r i c i n t e r a c t i o n s between the Ga-Me and p y r a z o l y l - M e groups a re s u f -f i c i e n t l y p r o h i b i t i v e t o p r e v e n t f o r m a t i o n o f t h i s complex whereas the N i - N O p y r a z o l y l - M e i n t e r a c t i o n i s n o t . The complexes [M(pz") ( N O ) 2 ] 2 where M = C o , F e were p r e p a r e d by r e a c t i n g sodium 3 , 5 - d i m e t h y l p y r a z o l i d e w i t h t h e a p p r o p r i a t e m e t a l d i n i t r o s y l i o d i d e . Based on the 1 8 - e l e c t r o n r u l e , t h e i r o n complex s h o u l d c o n t a i n a m e t a l - m e t a l bond and c o b a l t com-p l e x s h o u l d n o t . However, the f a c t t h a t a p r o t o n nmr spectrum c o u l d not be o b t a i n e d f o r the i r o n complex sugges ted t h a t t h e r e was no i n t e r a c t i o n between the Fe c e n t r e s and a magnet ic s u s c e p -t i b i l i t y measurement (by D r . R . C . Thompson u s i n g a Faraday method) c o n f i r m e d the expected paramagnetism o f the f o r m a l l y - 117 -17-electron complex ( f i e l d independent V e f f = 1.83 B.M. at 293 K (ligand and metal diamagnetism correction = 184 x 10 6 cm3 mol x ) ) . Interestingly, the i s o e l e c t r o n i c complex [Fe(pz") (CO)^ 2 was shown to be diamagnetic on the basis of i t s proton nmr spectrum (71,84) and a Fe-Fe bond was proposed on the basis of a F e 2 + signal i n the mass spectrum. However, mass spectral studies of [M(pz")(NO) 2] 2/ M = Co,Fe (see Table XXVIII) show that a peak i s present whether a metal-metal bond i s expected to be present (Fe) or not (Co) and hence the observation of a F e 2 signal i s inconclusive as to the presence or absence of a Fe-Fe bond. The observed diamagnetism of [Fe(pz") (CO) ^  could be due to a super-exchange phenomenon involving an electron pair coupling of the iron centres v i a the bridging pyrazolyl moieties. Table XXVIII. Mass Spectral Data for [M (pz") (NO) n ] Assignment M = 5 6 F e M = 5 9Co Intensity m/e Intensity m/e M 2(pz") 2(NO) 4 + 2 422 12 428 M 2(pz") 2(NO) 3 + 63 392 37 398 M 2(pz") 2(NO ) 2 + 30 362 18 , 368 M 2(pz") 2(NO) + 53 332 34 338 M 2 ( p z " ) 2 + 100 302 100 308 M 2(pz") (NO) 2 + 0 3 214 M(pz") (NO) + 5 181 6 184 M(pz") + 27 151 21 154 « 2 + 11 112 11 118 - 118 -The c r y s t a l s t r u c t u r e s of [M(pz") (NO) 2 ] 2 (M = Co,Fe) were determined by Dr. S. R e t t i g and are shown i n F i g u r e 38. F i g u r e 38. M o l e c u l a r s t r u c t u r e of [ M ( p z " ) ( N O ) 2 ] 2 , M = Co (a) and Fe (b). In both cases, the complexes have approximately C 2 v symmetry and the c e n t r a l M 2 N4 r i n g i s found to be i n a s l i g h t l y d i s t o r t e d o boat c o n f i g u r a t i o n . The Fe-Fe s e p a r a t i o n of 3.3359(3) A i s o s i g n i f i c a n t l y s h o r t e r than the Co-Co s e p a r a t i o n of 3.4717(4) A (even though the M-N(pz) and N-N(pz) bond d i s t a n c e s are s h o r t e r o by an average of 0.01 A i n the c o b a l t complex) and t h i s may i n d i c a t e some tendency toward a Fe-Fe i n t e r a c t i o n . However, the extremely long Fe-Fe d i s t a n c e leaves l i t t l e doubt as to the absence of a Fe-Fe bond and i t i s d i f f i c u l t to conceive of any conformation of the F e ( p z " ) 2 F e r i n g t h a t would a l l o w such an i n t e r a c t i o n . The boat conformation adopted by the c e n t r a l M 2 ^ 4 r±n<3 x n both s t r u c t u r e s f o r c e s the p s e u d o - a x i a l NO groups c l o s e together such t h a t the N ( n i t r o s y l ) - N ( n i t r o s y l ) d i s t a n c e s are much s h o r t e r than the M-M d i s t a n c e s . T h i s d i s t a n c e was found to be equal i n both s t r u c t u r e s (2.984(2) and 2.990(3) A ) . In the i r o n complex - 119 -a l l f o u r i n d e p e n d e n t Fe-NO d i s t a n c e s a r e e q u a l (Fe-N = 1.696(2) o A) and a l l f o u r n i t r o s y l groups a r e b e n t , the p s e u d o - a x i a l n i t r o s y l groups b e i n g bent s i g n i f i c a n t l y l e s s (168.2(2) and 1 6 7 . 0 ( 2 ) ° ) than the p s e u d o - e q u a t o r i a l n i t r o s y l s (163.4(2) and 1 5 8 . 5 ( 3 ) ° ) . I n the c o b a l t complex , t h e r e i s c o n s i d e r a b l e v a r i a -t i o n i n the Co-NO d i s t a n c e s , the ' e q u a t o r i a l ' C o - N d i s t a n c e s (1.659(2) and 1.646(3) A) b e i n g s i g n i f i c a n t l y s h o r t e r t h a n the • a x i a l ' C o - N d i s t a n c e s (1.672(2) and 1.680(3) A ) . As i n the i r o n complex a l l f o u r n i t r o s y l groups a r e b e n t . However, i n c o n t r a s t t o the i r o n complex , the p s e u d o - a x i a l groups a r e bent s i g n i f i c a n t l y more (165.1(2) and 1 6 1 . 3 ( 3 ) ° ) t h a n t h e p s e u d o -e q u a t o r i a l groups (173.5(3) and 1 7 3 . 0 ( 4 ) ° ) . One o t h e r d i f f e r e n c e i n v o l v i n g t h e n i t r o s y l groups o c c u r s i n the i r s p e c t r a o f the two co m plexes . The i n f r a r e d spect rum of t h e i r o n dimer d i s p l a y s f o u r s h a r p e q u a l i n t e n s i t y bands b o t h i n c y c i o h e x a n e s o l u t i o n and i n t h e N u j o l m u l l s p e c t r u m . On the o t h e r h a n d , the i r spect rum o f t h e c o b a l t dimer d i s p l a y e d two broad bands i n c y c i o h e x a n e s o l u t i o n and a v e r y b r o a d e n v e l o p e i n the N u j o l m u l l s p e c t r u m . A l t h o u g h t h e s e o b s e r v a t i o n s i n d i c a t e t h a t t h e r e i s a d i f f e r e n c e i n the degree of i n t e r a c t i o n between the two M ( N O ) 2 m o i e t i e s , the f a c t o r s a f f e c t i n g such an i n t e r -a c t i o n a r e d i f f i c u l t t o d e t e r m i n e (16) . F o r example , the r e l a t e d complex [ F e f N O ^ I j ^ w h i c h i s known to c o n t a i n a F e - F e bond (85) d i s p l a y s but two v N Q bands i n i t s s o l u t i o n i r spectrum (86) . - 12 0 -4.3.2 Reaction of Nucleophiles with Pyrazolyl Bridged Dimers The [Ni( 1pz')(NO)]2 dimers contain formally 16-electron nic k e l centres and are expected to re a d i l y form adduct complexes with electron donors. However, i n contrast to 'Ni(NO)I' which forms 1:1 complexes of the form [BNitNOJI^, where B i s a 2-electron donor, as well as 2:1 complexes of the form B2Ni(NO)I, the pyrazolyl bridged derivatives form only 1:1 adducts of the form [BNi(pz")(NO)] 2• The adducts l i s t e d in. Table XXVI display one v > T ^ band i n NO the i r Nujol mull spectra but two c l e a r l y resolved bands i n t h e i r i r spectra in cyciohexane. Since a c i s arrangement of ligands would lead to two v N Q bands and a trans arrangement of ligands would lead to one v N Q band (87,88), a possible explanation i s that the ligands occupy c i s positions i n the adducts. In th i s case, the most l i k e l y arrangement for these adducts i s one in which the central Ni2N^ ring remains planar with the two NO groups below this plane and the two donor molecules above t h i s plane. Each Ni atom would then acquire pseudo-tetrahedral geo-metry. A l t e r n a t i v e l y , the above observations could be i n t e r -preted i n terms of an equilibrium i n solution: [BNi('pz') (NO)]2 <r=^ [Ni('pz') (NO)] +' 2B (33) The two bands i n solution would then be due to the parent and the adduct. In t h i s case, the donors would be expected to occupy trans positions. The one exception i s the diphos complex which i s forced to adopt a c i s arrangement. The nmr of the bis-adduct complexes show one signal for - 121 -the 3,5 s u b s t i t u e n t s on the p y r a z o l y l g r o u p s . A t e t r a h e d r a l arrangement (as opposed t o square p l a n a r ) a round t h e n i c k e l atom s a t i s f a c t o r i l y e x p l a i n s the o b s e r v e d s p e c t r a whether the NO groups are c i s o r t r a n s . However, i f the NO groups a r e t r a n s , t h e n the c e n t r a l N i 2 N ^ r i n g must be p l a n a r o r i n a r a p i d l y (on the nmr t ime s c a l e ) i n v e r t i n g boat c o n f o r m a t i o n . The mass s p e c t r a o f t h e b i s - a d d u c t complexes d i d not d i s p l a y a s i g n a l due t o the p a r e n t i o n but r a t h e r gave s p e c t r a s i m i l a r t o the p a r e n t dimer m o l e c u l e s p l u s a d d i t i o n a l s i g n a l s due t o the donor m o l e c u l e s , B . E v i d e n t l y , the adducts a r e n o t s u f f i c i e n t l y t h e r m a l l y s t a b l e t o w i t h s t a n d the n e c e s s a r y probe t e m p e r a t u r e s employed (~ 1 2 0 ° C ) . In a d d i t i o n t o f o r m i n g a d d u c t s w i t h n e u t r a l l i g a n d s , the 1 6 - e l e c t r o n n i c k e l complexes a l s o form ' a d d u c t s ' w i t h u n i n e g a t i v e a n i o n s (see T a b l e X X V I I , p. 112) . B r i d g i n g h a l o g e n complexes were p r e p a r e d by a d d i t i o n o f t e t r a - a l k y l a m m o n i u m h a l i d e s a l t s to the p a r e n t dimer complexes and the t r i p l e ' p y r a z o l y l * b r i d g e complex was p r e p a r e d by r e a c t i n g 3 moles o f sodium 3 , 5 - d i m e t h y l p y r a z o l i d e w i t h 2 moles of n i c k e l n i t r o s y l i o d i d e . S i n c e the o r d e r o f s t a b i l i t y w i t h r e s p e c t t o d i s p l a c e m e n t o f one b r i d g i n g m o i e t y by a n o t h e r i n the p r e s e n c e o f R ^ N + f o l l o w e d the o r d e r I>Br>Cl>pz" i t was i n c o n v e n i e n t t o i s o l a t e the t e t r a a l k y l a m m o n i u m s a l t o f the t r i p l e ' p y r a z o l y l ' b r i d g e complex . R a t h e r , i t was i s o l a t e d as the sodium s a l t c o n t a i n i n g two moles o f THF as s o l v e n t o f c r y s t a l l i z a t i o n . As w i t h the p a r e n t d i m e r s , t h e s e a n i o n s are r e l a t i v e l y a i r s t a b l e as s o l i d s , but g r a d u a l l y decompose i n s o l u t i o n . - 122 -Comparison o f the v N Q v a l u e s (Table X X V I I , p. 112) f o r the I , B r and C I complexes show a t r e n d w h i c h i s o p p o s i t e t o t h a t p r e d i c t e d on s i m p l e e l e c t r o n e g a t i v i t y arguments . T h u s , on e l e c t r o n e g a t i v i t y g r o u n d s , the CI compounds s h o u l d d i s p l a y the h i g h e s t v a l u e s s i n c e s h i f t o f e l e c t r o n d e n s i t y from the n i c k e l NO .atoms towards CI s h o u l d reduce the du-Tr* b a c k - b o n d i n g from N i t o the NO l i g a n d . The r e v e r s e t r e n d o b s e r v e d here has been n o t e d i n r e l a t e d s e r i e s o f compounds (88,89) and may be a t t r i b u t e d t o the g r e a t e r u - a c c e p t o r a b i l i t y of the h e a v i e r h a l o g e n l i g a n d s , an e f f e c t w h i c h e v i d e n t l y outweighs the e l e c t r o n e g a t i v i t y e f f e c t . The nmr s p e c t r a o f the i o n i c complexes (see T a b l e X X V I I , p. 112)show one s i g n a l f o r the 3,5 s u b s t i t u e n t s o f the p y r a z o l y l group and i n d i c a t e a s y m m e t r i c a l l y b r i d g e d b i m e t a l l i c a n i o n i n s o l u t i o n . T h i s was c o n f i r m e d by the c r y s t a l s t r u c t u r e d e t e r -m i n a t i o n s o f E t 4 N + [ ( O N ) N i ( p z " ) 2 ( I ) N i ( N O ) ] ~ and [Na• 2THF] + [ (ON) N i ( p z " ) ^ N i ( N O ) ] and t h e s e are p r e s e n t e d i n F i g u r e s 39 and 40. C(10) C(9) C C 5 > F i g u r e 39. M o l e c u l a r s t r u c t u r e o f E t ^ N + [ (ON)Ni(pz" ) (I )Ni(NO) ] ~ . - 123 -The c r y s t a l structure of Et^N + [(ON) Ni (pz") 2 (I) Ni(NO)]~ consists of d i s c r e t e Et.N cations and binuclear anions which 4 contain two NiNO moieties bridged by an iodide and two 3 , 5-di-methylpyrazolyl ligands. The Ni atoms are tetrahedral (I-Ni-NO = 116.9(5), I-Ni-N(pz) = 93.5(5), N(pz)-Ni-NO = 124.1(8) and N(pz)-Ni-N(pz) = 97.1(1)°) and the two Ni-I distances are approx-o imately equal (2.765(2) A). The mean parameters of n i t r o s y l coordination (Ni-N-0 = 172.5(18)°, Ni-N = 1.649(5) and N-0 = o 1.13(1) A) are near the middle of the observed range i n t e t r a -hedral {NiNO} 1 0 complexes (82,83) and the Ni-Ni separation i s 3. 307 (1) A. Figure 40. Molecular structure of [Na•2THF] + [(ON)Ni(pz") 3Ni(NO)] ". The molecular structure of [Na-2THF] + [(ON)Ni (pz") 3 N i (NO)] ~ consists of two NiNO moieties bridged by three 3,5-dimethyl-pyrazolyl ligands, two of which are also coordinated to sodium 2 via a novel n (N,N) ir-interaction (mean Na-N = 2.61(3), Na-X(l) = 2.531 and Na-X(2) = 2.502 A, where X(l) and X(2) are the mid-points of the N(3)-N(4) and N(5)-N(6) bonds). Distorted - 124 -tetrahedral coordination about the sodium i s completed by two THF oxygen atoms (Na-0 = 2.301(6) and 2.266(5) A). The nick e l atoms are distorted tetrahedral (N(pz)-Ni-NO and N(pz)-Ni-N(pz) of 121(1) and 95.6(9)° respectively) and the n i t r o s y l g roup i s l i n e a r l y coordinated (Ni-N-0 = 176.9(11)°, Ni-N = 1.591(6) and N-0 = 1.183(8) A). The Ni-Ni separation of 3.439(1) A i s con-siderably longer than the Ni-Ni separation (3.307(1) A) i n the related iodide bridged complex, as expected. In contrast to the r e l a t i v e ease of adduct formation between the 16-electron n i c k e l dimers and electron donor ligands both the 17-electron iron dimer [Fe(pz")(NO) 2] 2 and the 18-electron cobalt dimer [Co(pz")(NO) 2] 2 were found to be i n e r t towards r e l a t i v e l y strong ligands such as PPh^. However, reac-tion of [Fe(pz")(NO) 2] 2 with iodine produced a polymeric sub-stance of empirical formula [Fe(pz")(NO) 2l]. In t h i s respect, i t i s noteworthy that both Fe(NO) 2I and Co(NO) 2I react with electron donating ligands to form monomeric adduct complexes (90). Undoubtedly the pyrazolyl ligand must play a major role in s t a b i l i z i n g the d i n i t r o s y l dimers. 4.4 Summary The compounds [Ni('pz') (NO)] 2 were prepared by the reaction of sodium 'pyrazolide' with nic k e l n i t r o s y l iodide. These 16-electron compounds form adduct complexes with r e l a t i v e l y strong donors such as PPh^ and AsPh^ and at low temperature, a weak interaction was indicated with NMe^- However, these dimers d i d not react with CO or diphenylacetylene. Reaction with t e t r a -- 125 -alkylammonium h a l i d e s gave b i m e t a l l i c anions c o n t a i n i n g two Ni(NO) m o i e t i e s b r i d g e d by two p y r a z o l y l groups and a halogen atom. In a d d i t i o n , the compound [ N a * 2 T H F ] + [ ( O N ) N i ( p z " ) 3 N i ( N O ) ] " was prepared by r e a c t i n g 3 moles of sodium 3 , 5 - d i m e t h y l p y r a z o l i d e with 2 moles of n i c k e l n i t r o s y l i o d i d e . A l l the n i c k e l dimers and t h e i r adducts were a i r s t a b l e i n the s o l i d s t a t e . However, s o l u t i o n s which are exposed t o a i r g r a d u a l l y become c o l o u r l e s s and l o s e t h e i r v X T _ band wi t h concomitant formation of a white NO p r e c i p i t a t e . In one r e a c t i o n , a novel t r i m e t a l l i c compound, [(ON)Ni(pz") 2 ] 2 N i w a s a l s o i s o l a t e d and c h a r a c t e r i z e d . The compounds [M(pz") (NO)^^*- where M = Co, Fe were p r e -pared by r e a c t i n g sodium 3, 5 - d i m e t h y l p y r a z o l i d e w i t h the a p p r o p r i a t e metal d i n i t r o s y l i o d i d e . The i r o n compound was shown to be paramagnetic and d i d not c o n t a i n the 'expected' Fe-Fe bond. In c o n t r a s t to the n i c k e l systems, these two com-pounds d i d not form adduct compounds w i t h n u c l e o p h i l e s . - 126 -CHAPTER V METAL NITROSYL DERIVATIVES OF PYRAZOLYLGALLATE LIGANDS 5.1 Introduction As shown i n Chapter IV, the 'pyrazolyl' group was very e f f e c t i v e i n s t a b i l i z i n g unusual metal n i t r o s y l complexes and i t was expected that chelating ligands derived from pyrazole would exhibit s i m i l a r s t a b i l i z i n g properties. I t has already been shown that i n a number of t r a n s i t i o n metal carbonyl complexes, the tridentate p y r a z o l y l g a l l a t e (and borate) ligands behave very 5 s i m i l a r l y to the n -cyclopentadienyl ligand (see Chapter I I I ) . However, i n contrast to the vast amount of l i t e r a t u r e dealing with cyclopentadienyl metal carbonyl complexes, comparatively l i t t l e has been published on the subject of cyclopentadienyl metal n i t r o s y l complexes - although recently there has been an upsurge in th i s area. The ( l i n e a r l y coordinated) n i t r o s y l ligand i s formally a three-electron ligand and consequently two NO groups are equivalent to 3 CO groups, one NO group i s equivalent to a CO group and a metal-metal single bond, etc.. This chapter describes the preparation of several metal n i t r o s y l derivatives and discusses the re l a t i o n s h i p between t h e i r geometry and the nature of the chelating ligand. Parts of th i s work have been published previously (91,92). - 127 -5.2 Experimental 5.2.1 Starting Materials Mn{P(OMe)3)2 (NO) 2Br was prepared from Mn{P (OMe) 3} 2 (CO) 3Br and NO gas (93) and Mo(NO) 2Cl 2 was prepared from Mo(CO) g and NOC1 (94). AgPFg was obtained from A l f a Inorganics. 5.2.2 Preparation of [Me2Ga (pz" ) (OCH2CH2NMe2)] Ni (NO) + — T H V Ni(NO)I + Na L (R=R'=Me) >LNi (NO) + Nal (34) Ni(NO)I (0.324 g; 1.50 mmol) was dissolved i n THF and a solution of Na +[Me 2Ga (pz") (OO^a^NMe^ ]~ (1.63 mmol) i n the same solvent added to the r e s u l t i n g dark green solution. There was an immediate colour change to dark blue and af t e r s t i r r i n g over-night, the solvent was removed i n vacuo and the dark blue residue extracted with benzene. F i l t r a t i o n of the extracts followed by slow evaporation of the f i l t r a t e gave dark blue c r y s t a l s of the product (0.39 g; 70%). It was also possible to purify t h i s compound by vacuum sublimation at ~ 80°C. Anal. Calcd. for Me 2Ga(pz")(OCH 2CH 2NMe 2)Ni(NO): C, 35.5; H, 6.2; N, 15.1. Found: C, 35.7; H, 6.3; N, 14.8. v • (cm - 1): 1770 (cyciohex-ane); 1750 br (Nujol). 1H nmr (T, CgDg): pz-Me(3), 7.17 (s,3H); pz-H(4), 3.94 (s,lH); pz-Me(5) f 7.90 (s,3H); -GaMe2, 9.88 (s,6H); -CH2CH2~, 6.53 (t (J - 5Hz),2H), 8.65 (t (J Z 5Hz)2H); -NMe2, 7.78 (s,6H). 5.2.3 Preparation of [Me2Ga(pz") (OCH2CH2NMe2)] Ni (pz") 2Ni (NO) Ni(NO)I (0.324 g; 1.50 mmol) was dissolved i n THF and a - 128 -THF solution of Na +[Me 2Ga(pz") (OCH2CH2NMe2)] ~ (1.63 mmol) added. After s t i r r i n g the reaction mixture for about 10 minutes, approx-imately 1 ml of water was added and the dark blue solution heated to r e f l u x . Oxygen (air) was admitted p e r i o d i c a l l y u n t i l a green tinge appeared i n the solution and af t e r cooling the mixture to r t , the solvent was removed in vacuo and the blue-green residue extracted with benzene. After several r e c r y s t a l l i z a t i o n s from benzene/heptane mixtures, dark green a i r sensitive c r y s t a l s were is o l a t e d (~ 20%). Anal. Calcd. for [Me 2Ga(pz")(OCH 2CH 2NMe 2)]Ni ( p z " ) 2Ni(NO): C, 4 0.6; H, 6.0; N, 18.0. Found: C, 40.7, H, 6.0; N, 17.7. v N Q (cm" 1): 1790 (Nujol). 5.2.4 Preparation of [MeGa (pz" ) 3 ]Ni (NO) Ni(NO)I + Na [MeGa(pz") 3J ?• [MeGa (pz") 3] Ni (NO) + Nal (35) Ni(NO)I (0.311 g; 1.44 mmol) was dissolved i n THF and Na + [MeGa(pz") 3] (1.45 mmol) i n the same solvent added. After s t i r r i n g the reaction mixture overnight, the solvent was removed in vacuo. The remaining blue s o l i d was r e c r y s t a l l i z e d from ben-zene to give well formed c r y s t a l s ( y i e l d ~ 60%). Anal. Calcd. for MeGa(pz") 3Ni(NO): C, 41.9; H, 5.2; N, 21.4. Found: C, 41.6; H, 5.3; N, 20.7. 1H nmr ( x , CgDg): pz-Me(3), 8.14 (s,9H); pz-H(4), 4.09 (s,3H); pz-Me(5), 7.43 (s,9H); -GaMe, 9.97 (s,3H). v N Q (cm - 1): 1785 (cyclohexane); 1765 (Nujol). - 129 -5.2.5 P r e p a r a t i o n of [MeGa(pz) 3]Ni(NO) Ni(NO)I + Na +[MeGa(pz) 3 ] " - ™ I > [MeGa (pz) 3 ] N i (NO) + Nal (36) A s o l u t i o n of N a + [ M e G a ( p z ) 3 ] ~ (1.6 mmol) i n THF (25 ml) was added dropwise t o a s t i r r e d s o l u t i o n o f Ni(NO)I (0.350 g; 1.6 mmol) i n THF (50 ml) a t -78°C. A f t e r a l l o w i n g the r e a c t i o n mixture t o warm slowly t o r t , s o l v e n t was removed i n vacuo and the remaining s o l i d e x t r a c t e d with benzene. F i l t r a t i o n , f o l l o w e d by slow e v a p o r a t i o n o f the f i l t r a t e gave blue c r y s t a l s t ogether w i t h a smal l amount of orange m a t e r i a l . Vacuum s u b l i m a t i o n a t 60°C gave blue c r y s t a l s o f the pure product. A n a l . C a l c d . f o r [MeGa(pz) ]Ni(NO): C, 32.1; H, 3.2; N, 26.3. Found: C, 32.4; H, 3.3; N, 23.2. 1H nmr (T, CgDg): pz-H(3), 1.43 (d (J - 2Hz), 3H) ; pz-H(4), 3.77 (t (J ~ 2Hz),3H); pz-H(5), 2.90 (d (J s. 2Hz), 3H); -GaMe, 10.22 (s,3H). v N Q ( c m - 1 ) : 1786 (cyclohexane); 1815 ( N u j o l ) . 5.2.6 Reaction of Ni (NO) I wit h Na"*"[Me2Ga (pz) J ~ and Na +[Me 2Ga (p z " ) 2 ] " Ni(NO)I was d i s s o l v e d i n THF and an equimolar amount of the a p p r o p r i a t e l i g a n d added. In each case, the green s o l u t i o n immediately turned deep blue i n c o l o u r . A f t e r s t i r r i n g over-n i g h t , s o l v e n t was removed i n vacuo and the r e s i d u e r e c r y s t a l -l i z e d from benzene. In the case of [Me 2Ga(pz) 2] , the onl y product i s o l a t e d was [ M e 2 G a ( p z ) 2 l 2 N i (54% o f pz groups) and i n the case of [ M e 2 G a ( p z " ) 2 ] , the i s o l a t e d products were [MeGa (pz") 3]Ni(NO) (63% of pz" groups) and [(ON)Ni (pz") 2 ] N i ( t r a c e ) . - 130 -5.2.7 Reaction of Ni(NO)I with 'Et^N* [Me2Ga (pz" ) J ~ ' Ni(NO)I (.430 g; 2 mmol) was dissolved in THF (50 ml) and E t 4 N + C l ~ (.335 g; 2 mmol) i n CH 2C1 2 (50 ml) added. The r e s u l t -ant green solution was cooled to -78°C and Na +[ Me 2Ga(pz") 2] 2.0 mmol) i n THF (25 ml) added dropwise over a period of 30 min-utes. Gradually, the colour of the solution turned blue and a pre c i p i t a t e formed. The mixture was allowed to warm to r t , anhydrous MgSO^ was added and the mixture f i l t e r e d . Removal of solvent from the f i l t r a t e i n vacuo gave dark blue c r y s t a l s which were washed with benzene u n t i l the washings were colourless. These were i d e n t i f i e d as E t 4 N + [(ON) Ni (pz ") 2 (I) Ni (NO) ]~ by i t s c h a r a c t e r i s t i c H^ nmr spectrum (0.16 g; 13% of pz" groups). Evaporation of the washings gave blue c r y s t a l s of [MeGa(pz")^] Ni (NO) 0.21 g; 35% of pz" groups). 5.2.8 Preparation of (pz"H) 2Ni(NO)I Ni(NO)I + 2pz"H (pz"H) 2Ni(NO) I (37) Ni(NO)I (0.215 g, 1.0 mmol) was dissolved i n THF and pz"H (0.192 g, 2 mmol) added to the r e s u l t i n g dark green solution. Immediately, the colour of the solution turned dark blue and after 20 minutes, solvent was removed i n vacuo. The resulting blue residue was r e c r y s t a l l i z e d from benzene. Y i e l d (0.33 g, 81%). Anal. Calcd. for (pz"H) 2Ni(NO)I: C, 29.4; H, 3.9; N, 17.2. Found: C, 29.7; H, 3.8; N, 16.9. 1H nmr ( x , CCDC): D D pz-Me(3), 8.60 (s,6H); pz-H(4), 3.74 (s,2H); pz-Me(5), 7.84 N^O (s,3H); N-H, -0.53 ( 2 H ) . v (cm- 1): 1754 (Nujol). - 131 -5.2.9 Preparation of [Me 2Ga(pz")(OCH 2CH 2NMe 2)]Mo(NO) 2C1 + — T H F Mo(NO) 2Cl 2 + Na L (R=R'=Me) > LMo(NO)2C1 + NaCl (38) Mo(NO) 2Cl 2 (0.341 g; 1.50 mmol) was dissolved i n a 1:1 mixture of CH2C12/THF (* 50 ml) and Na +[Me 2Ga(pz") (OCH2CH2NMe2)] (1.50 mmol) i n THF (25 ml) added. After ref l u x i n g for 3h, the solvent was removed i n vacuo and the resultant green residue extracted with benzene. F i l t r a t i o n followed by evaporation of the f i l t r a t e gave dark green c r y s t a l s of the product. Yi e l d : =20% Anal. Calcd. for Me 2Ga(pz")(OCH 2CH 2NMe 2)Mo(NO) 2C1: C, 27.9; H, 4.9; N, 14.8. Found: C, 27.9; H, 4.8; N, 14.5. 1H nmr (T, GgDg): pz-Me (3) , 7 . 52 (s,3H); pz-H(4), 4.30 (s,lH); pz-Me(5), 7.67 (s,3H); -GaMe2, 9.94 (s,3H), 10.06 (s,3H); -NMe2, 8.01 (s,6H). v N Q (cm - 1): 1778, 1660 (cyclohexane); 1765, 1640 (Nujol). 5.2.10 Preparation of [Me2Ga(pz") (OCH2CH2NMe2)] Mn(NO)2 THF + Mn{P (OMe) 3> 2 (NO) 2 B r + AgPF g — [ M n { P (OMe) 3> 2 (NO) 2 (THF)] PF g + AgBr ( I ) (39) (I) + Na +L~ (R=R'=Me) LMn (NO) 2 + N a + P F 6 " ( 4 0 ) Mn{P(OMe) 3} 2(NO) 2Br (0.32 g; 0.72 mmol) was dissolved i n THF (~ 50 ml) and s o l i d AgPF g (0.20 g; 0.80 mmol) added to the res u l t i n g solution. Immediately, the colour of the solution changed from orange to yellow green and a white s o l i d formed. Na +[Me 2Ga(pz")(OCH 2CH 2NMe 2)]" (0.78 mmol) i n THF was added and aft e r s t i r r i n g for 3h, the dark green solution was f i l t e r e d . - 132 -Evaporation of the f i l t r a t e gave an orange s o l i d which was wash-ed with MeOH and f i l t e r e d . The orange s o l i d c o l l e c t e d was re-c r y s t a l l i z e d from THF/benzene to give dark red c r y s t a l s of the product. Y i e l d (0.093 g; 32%). Anal. Calcd. for Me 2 Ga(pz") (OCH2CH2NMe2)Mn(NO)2: C, 33.2; H, 5.8; N , 17.6. Found: C, 33.3; H, 5.7; N, 17.4. v N Q (cm" 1): 1709, 1643 (cyciohexane); 1705 br, 1648 br (Nujol). X H nmr (T, CgDg): p z - M e(3), 7.53 (s,3H); pz-H(4), 4.31 (s,lH); pz-Me(5), 7.92 (s,3H); -GaMe2, 9.94 (s,6H); -CH2CH2~, 6.27 (t (J - 6Hz),2H), 8.16 (t (J - 6Hz), 2H); -NMe2, 8.20 (s,6H). 5.2.11 Preparation of [Me2 Ga(pz") (0CH2 CH_2NMe_2)] Fe (NO) 2 Fe(NO) 2I + Na +L~ (R=R*=Me) T H F > LFe(NO) 2 + Nal (41) Fe(NO) 2I (0.22 g; 0.91 mmol) was dissolved i n THF (-20 ml) and Na +[Me 2Ga(pz") (OCH2CH2NMe2)] ~ (1.0 mmol) i n THF (10 ml) was added to the re s u l t i n g solution. After s t i r r i n g the mixture for l h , the solvent was removed i n vacuo and the remaining s o l i d residue extracted with several portions of benzene. F i l t r a t i o n of the extracts followed by evaporation of the f i l t r a t e gave shiny black c r y s t a l s of the product (0.29 g; 81%). Anal. Calcd. for Me 2Ga(pz")(OCH 2CH 2NMe 2)Fe(NO) 2: C, 33.1; H, 5.8; N, 17.5. Found: C, 33.5; H, 6.0; N, 17.3. v N Q (cm - 1): 1750, 1673 (cyciohexane); 1740, 1668 (Nujol). [Me 2Ga(pz)(OCH 2CH 2NMe 2)]Fe(NO) 2 was prepared by an i d e n t i -c a l method i n 56% y i e l d . Anal. Calcd. for Me 2Ga(pz)(OCH 2CH 2NMe 2) Fe(NO) 2: C, 29.2; H, 5.2; N, 18.9. Found: C, 29.1; H, 5.1; - 133 -N , 1 8 . 5 . v N Q ( c m - 1 ) : 1750, 1671 ( c y c i o h e x a n e ) ; 1724 b r , 1630 b r ( N u j o l ) . 5 .2 .12 R e a c t i o n o f Fe (NO) 2 1 w i t h [MeGa (pz") J ~ and [MeGafpz)-, T_ F e ( N O ) 2 I was d i s s o l v e d i n THF and an e q u i m o l a r amount of the a p p r o p r i a t e l i g a n d ([MeGa (pz ") 3 ] ~ or [ M e G a ( p z ) 3 ] ~ ) i n THF added. A f t e r s t i r r i n g f o r l h , s o l v e n t was removed i n vacuo and the r e s i d u e r e c r y s t a l l i z e d from benzene . In the case o f [ M e G a ( p z ) 3 ] , t h e o n l y p r o d u c t i s o l a t e d was [ M e G a ( p z ) 3 ] 2 F e (26% o f pz groups) and i n the case o f [ M e G a ( p z " ) 3 ] , t h e p r o d u c t i s o -l a t e d was [Fe (pz") (NO) ] 2 (30% of p z " g r o u p s ) . In a d d i t i o n , i n the l a t t e r r e a c t i o n mass s p e c t r o s c o p i c a n a l y s i s o f the c r u d e m a t e r i a l showed the p r e s e n c e o f ' g a l l i u m d i m e r s 1 . ( ' g a l l i u m d i m e r s ' = M e 4 G a 2 ( p z " ) 2 + n ' n = 0 - 2 . ) . 5 . 2 . 1 3 R e a c t i o n o f Co (NO) 2 1 w i t h N a + [ M e 2 G a ( p z " ) (OCH 2 CH 2 NMe 2 )] N a + [ M e 2 G a ( p z " ) ( O C H 2 C H 2 N M e 2 ) ] ~ (2.0 mmol) i n THF (25 ml) was added d r o p w i s e t o a THF s o l u t i o n (50 ml) of C o ( N 0 ) 2 I (.442 g ; 2.0 mmol) c o o l e d t o - 7 8 ° C . A f t e r a l l o w i n g the r e a c t i o n m i x -t u r e t o warm t o r t , the s o l v e n t was removed i n vacuo and the r e m a i n i n g brown r e s i d u e e x t r a c t e d w i t h b e n z e n e . F i l t r a t i o n , f o l l o w e d by e v a p o r a t i o n of the f i l t r a t e gave c h a r c o a l c r y s t a l s o f [Co (pz") (NO) 2 ] 2 (40% o f p z " g r o u p s ) . T h i s was the o n l y p r o d u c t i s o l a t e d . - 1 3 4 -5.3 R e s u l t s and D i s c u s s i o n 5 . 3 . 1 N i c k e l N i t r o s y l D e r i v a t i v e s The p r e p a r a t i o n of CpNi(NO) was r e p o r t e d some y e a r s ago ( 9 5 , 9 6 ) . T h i s compound i s a d a r k r e d l i q u i d , a i r s t a b l e , s l i g h t l y decomposed upon d i s t i l l a t i o n and c o n t a i n s a l i n e a r N i - N - 0 g r o u p -i n g w i t h a N i - N d i s t a n c e o f 1.58 A (97) . F o r m a l l y analogous compounds i n v o l v i n g p y r a z o l y l g a l l a t e l i g a n d s can be p r e p a r e d by r e a c t i o n of t h e a p p r o p r i a t e l i g a n d ( [ M e G a ( p z ) 3 ] ~ f [ M e G a ( p z " ) 3 ] ~ o r [ M e 2 G a ( p z " ) ( O C H 2 C H 2 N M e 2 ) ] " ) w i t h N i ( N O ) I . The r e s u l t i n g compounds a re b l u e s o l i d s w h i c h a r e s t a b l e under n i t r o g e n b o t h as s o l i d s or i n s o l u t i o n . However, i n the p r e s e n c e o f a i r s o l u t i o n s r a p i d l y l o s e NO w i t h u l t i m a t e f o r m a t i o n o f N i ( I I ) s p e c i e s . A c o m p a r i s o n of the v N Q s t r e t c h i n g f r e q u e n c i e s o f the p r e s e n t compounds (1786, 1785 and 1770 c m " 1 f o r [MeGa(pz) ] N i ( N O ) , [MeGa(pz") ]Ni(NO) and [ M e 2 G a ( p z " ) ( O C H 2 C H 2 N M e 2 ) ] N i ( N O ) r e s p e c t i v e l y ) w i t h t h a t of CpNi(NO) (1833 c m " 1 (97)) i n d i c a t e t h a t the N i - N O bond s h o u l d be s t r o n g e r i n t h e p y r a z o l y l g a l l a t e d e r i v a t i v e s . A p p a r e n t l y , the l o s s o f NO f r o m t h e s e d e r i v a t i v e s i s not due t o the s t r e n g t h of the N i - N O b o n d . R a t h e r , i t i s p r o b a b l y due to the i n h e r e n t s t a b i l i t y of the N i ( I I ) p r o d u c t s produced i n the d e c o m p o s i t i o n r e a c t i o n s (see C h a p t e r I I , 10 , 11 ) . An analogous d e c o m p o s i t i o n r o u t e f o r CpNi(NO) would l e a d t o C p 2 N i , a r e l a t i v e l y u n s t a b l e compound which decomposes s l o w l y a t r t even i n the absence o f a i r and l i g h t (98) . In f a c t , a p r e p a r a t i v e r o u t e to CpNi(NO) i s the a c t i o n o f NO on C p 2 N i (96) . P a r t i a l o x i d a t i o n o f [ M e 9 G a ( p z " ) ( O C H CH-NMe, ) ]Ni(NO) gave - 135 -the n o v e l t r i m e t a l l i c compound [Me 2Ga(pz") (OCH 2CH 2NMe 2)] N i ( p z " ) 2 Ni(NO) which c o n t a i n s f o r m a l l y both a N i ( I ) c e n t r e and a N i ( I I ) c e n t r e . The N i ( I ) c e n t r e i s expected t o e x h i b i t the same geo-metry as the n i c k e l atoms i n (ON)Ni(pz") 2Ni(NO) ( t r i g o n a l planar) and the N i ( I I ) c e n t r e i s expected t o e x h i b i t the same geometry as the n i c k e l atom i n [Me 2Ga(pz") (OCH 2CH 2NMe 2)] N i [ ( p z " ) 2 G a M e 2 3 ( t r i g o n a l b i p y r a m i d a l ) . Of the two complexes [ MeGa(pz")^]Ni(NO) and [MeGa(pz) JNi(NO), the former i s the more r e a d i l y prepared and i s more s t a b l e t o l o s s o f NO. The l a t t e r complex r e a d i l y l o s e s NO i n s o l u t i o n and i t s p r e p a r a t i o n i s hampered by the tendency t o form [ MeGa (pz) 31 2 N i (11) and [Me 2Ga (pz) ] 2 N i (10) . In a d d i t i o n , f a c i l e l o s s of NO i n the a n a l y t i c a l instrument i s i n d i c a t e d by a low a n a l y s i s f o r n i t r o g e n . In the presence of a i r , [MeGa(pz") 3]Ni(NO) a l s o l o s e s NO i n s o l u t i o n but much more sl o w l y . However, the f i n a l product(s) from t h i s decomposition were not i d e n t i f i e d . In t h i s r e s p e c t , i t i s noteworthy t h a t t h e r e has y e t t o be any N i ( I I ) d e r i v a t i v e s s y n t h e s i z e d from [MeGa (pz") 3 ] ~ or [Me 2Ga (pz ") ] " . The monomeric nature of the n i c k e l n i t r o s y l compounds was a s c e r t a i n e d from t h e i r mass s p e c t r a . In the case of [MeGa(pz") 3] Ni(NO) and [MeGa(pz) 3]Ni(NO) the h i g h e s t observed m/e was due to the parent i o n and the s t r o n g e s t s i g n a l was due t o the parent minus n i t r o s y l i o n , P-NO+. T h i s s i g n a l was ~ 10X s t r o n g e r than any o t h e r s i g n a l observed. In the case of [Me 2Ga(pz")(OCH 2CH 2 NMe 2)]Ni(NO) and [Me 2Ga(pz")(OCH 2CH 2NMe 2)]Ni(pz n) 2Ni(NO), the s t r o n g e s t s i g n a l s were P-NO-Me+ and P-NO+, i n t h a t o r d e r . Again the h i g h e s t m/e i n each case was a t t r i b u t a b l e t o the parent i o n . - 136 -F o r [MeGa(pz) ] N i (NO) and [ MeGa (pz") 3 ] N i (NO) , pseudo t e t r a -h e d r a l geometry around the n i c k e l atom i s r e q u i r e d s i n c e t h e t r i d e n t a t e l i g a n d i n b o t h o f t h e s e compounds cannot occupy a p l a n a r s e t of c o o r d i n a t i o n s i t e s . However, i n [Me2Ga(pz")[OCU^ C H 2 N M e 2 ) ] N i ( N O ) , a square p l a n a r arrangement o f the f o u r donor atoms about t h e n i c k e l atom i s p o s s i b l e . The nmr s p e c t r u m o f t h i s compound (see F i g . 41) shows o n l y one s i g n a l f o r each of the - N M e 2 and -GaMe2 m o i e t i e s , s u g g e s t i n g a m e r i d i o n a l l y c o o r d i n -a ted l i g a n d ( i e . square p l a n a r c o o r d i n a t i o n around the n i c k e l a tom) . However, the f a c t t h a t f l u x i o n a l p r o p e r t i e s have been o b s e r v e d f o r t h i s type o f l i g a n d and t h a t p r e v i o u s s t u d i e s have shown t h a t square p l a n a r {MNO} 1 0 complexes s h o u l d have a M-N-0 a n g l e o f 1 2 0 ° (82) ( c o n t r a r y to the ' l i n e a r ' NO group i n d i c a t e d by i r r e s u l t s ) l e d us to view these nmr r e s u l t s w i t h some degree of c a u t i o n . A t low temperature ^H nmr s p e c t r a i n t o l u e n e - d g s o l u t i o n d i d i n d e e d r e v e a l the f l u x i o n a l n a t u r e o f t h i s compound. In t h i s e x p e r i m e n t , the sharp -GaMe2 s i g n a l was m o n i t o r e d . As t h e s o l u t i o n was c o o l e d , the -GaMe2 s i g n a l g r a d u a l l y broadened u n t i l a t - 7 0 ° C , i t became a b r o a d hump. A t - 8 0 ° C (the l o w e s t t e m p e r a -t u r e a t t a i n a b l e ) , the appearance of two s i g n a l s , one to each s i d e of the o r i g i n a l s i g n a l was j u s t d i s c e r n a b l e . E v i d e n t l y , the n i c k e l atom i n t h i s m o l e c u l e i s t e t r a h e d r a l l y c o o r d i n a t e d and the r t nmr spectrum i n d i c a t e s a r a p i d l y f l u x i o n a l s p e c i e s i n s o l u t i o n . A mechanism s i m i l a r to t h a t p r o p o s e d f o r t h e f l u x i o n a l o c t a h e d r a l c a r b o n y l complexes i n C h a p t e r I I s a t i s f a c -t o r i l y e x p l a i n s the o b s e r v e d s p e c t r a (see F i g . 42 ) . The one d i f f e r e n c e i s t h a t the i n t e r m e d i a t e i s now a t r i g o n a l p l a n a r 5 Jc A UI r i i i i • i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i I i i 3 4 5 6 7 8 » W « F i g u r e 41. 100 MHz X H nmr spectrum o f [Me 2 Ga(pz") (OCH 2 CH 2 NMe 2 ) ] N i (NO) i n CgDg. - 138 -s p e c i e s r a t h e r than a t r i g o n a l b i p y r a m i d a l s p e c i e s . Again, the br e a k i n g of the M-N(amino) bond and i n v e r s i o n at the pyramidal oxygen atom i s an i n t e g r a l p a r t of the mechanism. F i g u r e 42. Proposed mechanism f o r the f l u x i o n a l process observed i n [Me 2Ga (pz") (OCH 2CH 2NMe 2)] N i (NO) . The t e t r a h e d r a l c o o r d i n a t i o n around the n i c k e l atom was confirmed by an x-ray c r y s t a l l o g r a p h i c study ( F i g . 43). The F i g u r e 43. M o l e c u l a r s t r u c t u r e of [Me 2Ga(pz")(OCH 2CH 2 NMe 2)]Ni(NO). molecule c o n t a i n s a system of t h r e e fused f i v e membered r i n g s with the c e n t r a l GaONiNN r i n g being roughly c o p l a n a r w i t h the p y r a z o l y l r i n g and p e r p e n d i c u l a r to the NiOCCN r i n g . T h i s arrangement i s s i m i l a r to t h a t observed i n the o c t a h e d r a l complexes £ a c - [ M e 2 G a (pz) ( O C r ^ C B ^ N H j ] 2 N i (18) and [ M e 2 G a ( p z " ) ( O C H 2 C H 2 N H 2 ) ] M o ( C O ) 2 ( n 3 - C 4 H 7 ) (54) . The a n g l e s around the n i c k e l atom range from 8 4 . 4 ° to 1 3 3 . 5 ° and the n i t r o s y l group i s c o -o r d i n a t e d i n a n o n - l i n e a r f a s h i o n w i t h N i - N - 0 = 1 6 3 . 3 ° , N i - N = 1.632(4) and N-0 = 1.147 A . The N i - O , N i - N ( p z " ) and N i - N ( a m i n o ) o bond d i s t a n c e s o f 2 . 0 4 5 ( 2 ) , 1.989(3) and 2.071(3) A may be com-p a r e d t o the c o r r e s p o n d i n g d i s t a n c e s o f 2 . 0 9 0 ( 3 ) , 2.085(3) and 2.112(3) A i n the o c t a h e d r a l N i ( I I ) complex f a c - [ M e 2 G a ( p z ) ( O C H 2 C H 2 N H 2 ) 3 2 N i w h i c h has a s i m i l a r l i g a n d geometry . The l o n g e r d i s t a n c e s i n the N i ( I I ) complex p r o b a b l y r e s u l t f rom c o n s i d e r a b l y g r e a t e r s t e r i c c r o w d i n g . I t i s noteworthy t h a t t h e n i c k e l n i t r o s y l compound i s o p t i c a l l y a c t i v e and b o t h e n a n t i o m e r i c forms are found i n t h e c r y s t a l s t r u c t u r e . The sugges ted mechan-ism f o r t h e f l u x i o n a l p r o c e s s o b s e r v e d i n s o l u t i o n would i n t e r -c o n v e r t the two o p t i c a l i s o m e r s . At tempts t o p r e p a r e 1 6 - e l e c t r o n t r i g o n a l c o m p l e x e s , s i m i l a r t o t h e 1 6 - e l e c t r o n p y r a z o l y l b r i d g e d dimers (Chapter I V ) , b u t i n v o l v i n g b i d e n t a t e b i s p y r a z o l y l g a l l a t e l i g a n d s p r o v e d t o be u n s u c c e s s f u l . R e a c t i o n o f N i ( N O ) I w i t h N a + [ M e 2 G a ( p z " ) 2 ] r e s u l t e d i n the i s o l a t i o n o f [ M e G a ( p z " ) 3 ] N i ( N O ) and [ (ON)Ni ( p z " ) 2 l 2 N i w h i l e the r e a c t i o n o f N i ( N O ) I w i t h N a + [Me 2Ga (pz) 2 ]~ r e s u l t e d i n the i s o l a t i o n o f [ M e 2 G a ( p z ) 2 ] 2 N i . A g a i n , t h e s e " d e c o m p o s i t i o n s " may be due to the ' s t a b i l i t y ' of t h e r e s u l t a n t p r o d u c t s . When N i ( N O ) I was r e a c t e d w i t h N a + [ M e 2 G a ( p z " ) 2 ] i n the p r e s e n c e o f E t ^ N C l i n t h e hopes o f p r e p a r i n g E t ^ N [Me 2 Ga(pz") 2 ]Ni(NO) 17 the i s o l a t e d p r o d u c t s were E t 4 N + [ ( O N ) N i (pz") 2 ( I ) N i (NO) ] " and [MeGa(pz") ].Ni (NO) . In t h i s r e s p e c t , i t i s noted t h a t ( p z " H ) 2 N i ( N O ) I (see e x p e r i m e n t a l ) i s e a s i l y - 140 -prepared and does not exhibit any disproportionation reactions. i n solution (under N 2). 5.3.2 [Me2Ga(pz")(OCH^CH^NMe^)]Mo(NO)^Cl The reaction of Na +L~ (R=R'=Me) with Mo(NO) 2Cl 2 gave LMo(NO) 2Cl. The highest m/e i n the mass spectrum of t h i s com-pound i s a t t r i b u t a b l e to the P-Me+ ion and the strongest signal i s due to the P-2NO-Me+ ion. The nmr spectrum (see Figure 44) displays two signals for the -GaMe2 group, one signal for the -NMe2 group and two complicated multiplets for the -CH2CH2~ group and i s i n d i c a t i v e of a f a c i a l l y coordinated chelating ligand (the expected two -NMe2 signals are probably a c c i d e n t a l l y degenerate). This mode of coordination (facial) i s not sur-p r i s i n g since previously studied systems (viz [HB(pz)^]Mo(NO)2C1 (36) and CpMo(NO) CI (99)) of t h i s type contain f a c i a l l y coor-dinated ligands. However, i t i s somewhat surprising that only one isomer (out of a p o s s i b i l i t y of three) was i s o l a t e d . The i r spectrum of [Me2Ga(pz") (OCH2CH2NMe2)] Mo (NO) 2C1 exhibits two v N Q bands at 17 78 and 1660 cm"1. In addition, two weak but d i s t i n c t overtone bands appear at 3550 and 3320 cm - 1. As expected, the v N Q bands of the present compound are s l i g h t l y lower than those of the analogous boron compound (V^Q of [HB(pz") 3]Mo(NO) 2C1 = 1781, 1678 cm"1 (36)). However i t i s puzzling that both the p y r a z o l y l g a l l a t e and pyrazolylborate derivatives possess v N Q bands that are anomalously high compared to those of CpMo(NO) 2Cl ( v N Q of CpMo(NO) 2Cl = 1759, 1665 cm"1 (CH 2C1 2) (99)). - 142 -5.3.3 D i n i t r o s y l Derivatives of Manganese and Iron If the NO ligand i s considered to be a three-electron donor ligand, then two NO ligands may formally replace three CO ligands and the compound LMn(NO)2 would be the n i t r o s y l analog of LMn (CO) 3 (Chapter I I I ) . This compound was prepared by the reaction of Mn(P(OMe) 3) 2(NO) 2Br with AgPF g followed by addition of Na +L~ (R=R*=Me) to the r e s u l t i n g intermediate, [Mn{P(OMe) 3) 2(NO) 2(THF)] + PFg . In thi s reaction, the THF i s probably replaced f i r s t by one of the donor atoms on the ligand L and then the stronger P(OMe) 3 ligands are susceptible to displacement v i a a chelate e f f e c t . Direct reaction of Mn(P(OMe) 3> 2(NO) 2Br with Na +L~ (R=R*=Me) resulted i n an int r a c t a b l e o i l . D i n i t r o s y l derivatives of iron could be prepared by reac-t i o n of Na +L (R=H or Me; R1=Me) with Fe(NO) 2I. These compounds contain a formally 19-electron Fe centre and are expected to be paramagnetic. Considering t h i s f a c t , they are remarkably stable. Solutions begin to decompose a f t e r several minutes i n a i r but cr y s t a l s of the pure material only begin to lose t h e i r l u s t r e a f t e r several days i n a i r . Attempts to prepare the 18-electron complex [LFe(NO) 2] + (via oxidation of the 19-electron complex) were not successful. LFe(NO) 2 d i d not react with NO+PFg i n + — r e f l u x i n g benzene and reaction of LFe(N0) o with Ag PF,. gave a black tar which was not characterized. The mass spectra of the LFe(NO) 2 compounds were very simi-l a r and the spectra of [Me 2Ga(pz")(OCH 2CH 2NMe 2)]M(NO) 2 (M=Mn, Fe) were e s s e n t i a l l y i d e n t i c a l . In each case, the highest m/e observed was due to the P-Me ion (3%) and the strongest s i g n a l corresponded to the P-2N0+ ion. Other strong signals were due to the P-NO+ (40%) and the doubly charged P-2NO-Me++(20%) ions. The absence of parent ion signals i n the mass spectra of organo-gallium compounds, p a r t i c u l a r l y those containing the -GaMe2 moiety has been observed previously (83,100). The nmr spectrum of the manganese complex (see F i g . 45), [Me 2Ga(pz")(OCH 2CH 2NMe 2)]Mn(NO) 2, displays one sharp signal for the -GaMe2 moiety, one sharp signal for the -NMe2 signal and two well resolved t r i p l e t s for -CH2CH2~ moiety. These re s u l t s suggest a t r i g o n a l bipyramidal structure with equatorial NO groups and a meridional g a l l a t e ligand. Attempts to obtain the ''"H nmr spectrum of the iron compounds were thwarted by t h e i r predicted paramagnetic character. However, since the mass spectra and i r spectra (positions of v N Q excepted) of LM(NO)2 (R=R'=Me; M=Fe,Mn) were i d e n t i c a l , a sim i l a r structure i s sug-gested for the iron complexes. It i s i n t e r e s t i n g to compare related uninegative s i x -electron ligands i n t h i s area of chemistry. A very early attempt to prepare CpMn(NO)2 resulted i n an associated material, of the correct empirical formulation containing both bridging and term-i n a l v„,_ bands i n i t s i r spectrum (101) . Various reasons were NO advanced at that time to explain the absence of the monomeric species. CpFe(NO) 2 has not been reported. However a dimeric compound [CpFe(NO)] 2 has been described in which a Fe=Fe double bond and bridging NO groups are postulated to l i n k the monomer units (102). In the case of [RB(pz) 3]~ (R=H, a l k y l ) , no d i n i -t r o s y l complexes have been reported and our attempts to prepare - 144 -- 145 -[MeGa(pz)21 M (NO)2 (M=Mn,Fe) have so f a r p r o v e n u n s u c c e s s f u l . The r e a c t i o n of [ M e G a ( p z ) 3 ] w i t h F e ( N O ) 2 I produced o n l y [MeGa ( p z ) 3 l 2 F e and the r e a c t i o n o f [MeGa (pz") 3 ] ~ w i t h F e ( N O ) 2 I gave o n l y [Fe (pz") (NO) 2 ] 2 . A l i k e l y e x p l a n a t i o n f o r t h e above o b s e r v a t i o n s i s the a b i l i t y of the asymmetric g a l l a t e l i g a n d s to occupy a s e t o f t h r e e m e r i d i o n a l c o o r d i n a t i o n s i t e s about the t r a n s i t i o n m e t a l atom, an arrangement w h i c h appears n e c e s s a r y to s t a b i l i z e the 5 monomeric s p e c i e s and which i s i m p o s s i b l e f o r the l i g a n d s n -C 5 H 5 , R B ( p z ) 3 o r M e G a ( p z ) 3 . T h i s i s f u r t h e r s u b s t a n t i a t e d by the s t r u c t u r e o f Mn{P(OMe)2?h}2(NO) 2C1 where monodentate l i g a n d s are i n v o l v e d (103). In t h i s m o l e c u l e , the h a l o g e n atom and p h o s p h i n e l i g a n d s have been shown to occupy m e r i d i o n a l c o o r d i n a t i o n s i t e s i n t h e t r i g o n a l b i p y r a m i d a l m o l e c u l e , w i t h the two n i t r o s y l groups o c c u p y i n g e q u a t o r i a l s i t e s (103,104). In a d d i t i o n , t h e o -r e t i c a l s t u d i e s p r e d i c t t h a t i n f i v e c o o r d i n a t e d i n i t r o s y l complexes , the most f a v o u r a b l e arrangement would have a t r i g o n a l b i p y r a m i d a l geometry w i t h e q u a t o r i a l NO groups (82) . The c o o r d i n a t i o n geometry sugges ted by the p h y s i c a l d a t a was c o n f i r m e d by an x - r a y c r y s t a l l o g r a p h i c s tudy (done by D r . S. R e t t i g ) o f the i r o n compound [Me 2 Ga (pz") (OCH 2 CH 2 NMe 2 ) ] Fe (NO) 2 • The m o l e c u l e (see F i g . 46) has a d i s t o r t e d t r i g o n a l b i p y r a m i d a l geometry w i t h the oxygen and two n i t r o g e n atoms o f the [Me2Ga (pz") (OCH2CH2NMe2 ) ] " l igand o c c u p y i n g one e q u a t o r i a l and the two a x i a l s i t e s r e s p e c t i v e l y . The two n i t r o s y l groups occupy the r e m a i n i n g e q u a t o r i a l p o s i t i o n s . The i r o n atom i s s l i g h t l y o (0.075 A) d i s p l a c e d out of the e q u a t o r i a l p l a n e and the n i t r o s y l F i g u r e 46. M o l e c u l a r s t r u c t u r e of [Me 2Ga(pz") (OCH 2CH 2NMe 2)]Fe(NO) 2. groups are n o n - l i n e a r l y c o o r d i n a t e d (Fe-N-0 = 158.6°; Fe-NO = 1.703(6), FeN-0 = 1.153(7) A) w i t h ON-Fe-NO = 108.1°. The o e q u a t o r i a l Fe-0 d i s t a n c e i s 2.037(3) A and the a x i a l Fe-N d i s -o tances are 2.112(3) (pz) and 2.279(amino) A. The a x i a l bond l e n g t h s are c o n s i d e r a b l y more d i f f e r e n t than expected on the b a s i s of h y b r i d i z a t i o n d i f f e r e n c e s at the n i t r o g e n atoms and t h i s i s probably due t o s t e r i c i n t e r a c t i o n s between the amino methyl groups and the two n i t r o s y l groups. Attempts t o prepare LCo(NO) 2 (R=R'=Me) r e s u l t e d o n l y i n the i s o l a t i o n of [ C o ( p z " ) ( N O ) 2 ] 2 . E v i d e n t l y a 2 0 - e l e c t r o n Co metal c e n t r e c o u l d not be s t a b i l i z e d s u f f i c i e n t l y by the g a l l a t e l i g a n d t o y i e l d an i s o l a b l e complex. 5.4 Summary The compounds DNi (NO) where D = [ M e G a ( p z ) 3 ] , [MeGa(pz") 3] and [Me 2Ga(pz")(OCH 2CH 2NMe 2)] were prepared by r e a c t i n g the appropriate tridentate chelating g a l l a t e ligand with Ni(NO)I. These compounds were found to be stable under nitrogen but i n the presence of a i r , solutions r a p i d l y lose NO, and Ni(II) pro-ducts are formed. In the case of D = [Me 2Ga(pz")(OCH 2CH 2NMe 2)], 'controlled' oxidation led to the i s o l a t i o n of [Me 2Ga(pz") (OCH 2CH 2NMe 2)]Ni(pz") 2Ni(NO) which contains both a Ni(II) and a Ni(I) centre. The four coordinate n i c k e l n i t r o s y l complexes were found to have tetrahedrally coordinated n i c k e l atoms and the compound [MeGa(pz") (OCH2CH2NMe2)] Ni(NO) was found to be fl u x i o n a l i n solution. The compound LMo(NO) 2Cl (R=R'=Me) was prepared by reacting Na +L with Mo(NO) 2C1 2. The g a l l a t e ligand coordinates i n a fac-i a l manner and only one isomer (out of a p o s s i b i l i t y of three) was i s o l a t e d . The compounds LMn(NO)2 and LFe(NO) 2 (R=R'=Me) were prepared by reacting Na +L with an appropriate d i n i t r o s y l precursor. In each case, the ligand occupies a set of meridional coordination s i t e s i n the t r i g o n a l bipyramidal complexes with equatorial NO groups. This configuration of the gal l a t e ligand appears to be necessary for s t a b i l i z i n g these complexes. Although both the •Mn(NO)2' (18-electron) and 'Fe(NO)2' (19-electron) complexes proved to be thermally stable, attempts to prepare a 20-electron 'Co(NO)0' complex were unsuccessful. - 148 -CHAPTER VI FURTHER INVESTIGATIONS 6.1 Introduction In Chapter I I I , several chromium, molybdenum, tungsten and manganese carbonyl derivatives of py r a z o l y l g a l l a t e ligands were described and i n Chapter V, a variety of n i c k e l , iron and man-ganese derivatives incorporating these ligands were discussed. This chapter describes attempts to synthesize some related com-plexes involving other f i r s t row tra n s i t r o n metal elements. In addition, a number of new gallate ligands are introduced and t h e i r coordinating properties discussed b r i e f l y . 6.2 Experimental 6.2.1 Starting Materials (C^Hc-) 2 N i was prepared from C^Hj-MgCl and NiB r 2 and subse-quently converted to [ (C^H^-)NiBr] 2 by reaction with HBr (106). [ ( ' a l l y l ' ) P d C l ] 2 ( ' a l l y l ' = C 3H 5 and C 4H ?) was prepared v i a the reaction of PdCl 2 with ' a l l y l ' C I i n the presence of CO and MeOH (107) and (PPh^CuBr was prepared from PPh 3 and CuBr (108) . Fe(NO) 2(CO) 2 (109), Co(NO)(CO) (110) and F e 3 ( C O ) 1 2 (111) were prepared by l i t e r a t u r e methods. 6.2.2 Preparation of [Me 2Ga(pz") 2]Pd'allyl' [ ' a l l y l ' P d C l ] 2 + 2Na +[Me 2Ga(pz") 2 3~ -^F-> [Me2Ga (pz" ) 23 Pd ' a l l y l ' + NaCl (42) - 149 -[ ( C 4 H 7 ) P d C l ] 2 (0.394 g; 1.5 mmol) was dissolved i n THF and Na +[Me 2Ga(pz") 2] (3.0 mmol) i n the same solvent added. The yellow solution slowly turned colourless and af t e r s t i r r i n g for 1 h, solvent was removed i n vacuo and the residue extracted with benzene. F i l t r a t i o n of the extracts followed by slow evaporation of the f i l t r a t e gave white c r y s t a l s of the product. Y i e l d : (P.61 g; (58%). Anal. Calcd. for Me 2Ga(pz") 2Pd(C 4H ?): C, 42.6; H, 6.0; N, 12.4. Found: C, 42.8; H, 6.0; N, 12.4. 1H nmr ( T, CgDg): -GaMe2, 9.57 (s,3H), 9.65 (s,3H); pz-Me(3), 7.78 (s,6H); pz-H(4), 4.23 (s,2H); pz-Me(5), 7.92 (s,6H); methallyl-Me, 8.28 (s,3H); methallyl-H (syn), 6.71 (s,2H); methallyl-H (anti), 7.51 (s,2H). The compound [Me 2Ga(pz") 2]Pd(C 3H 5) was prepared i n an iden-t i c a l manner. Y i e l d : 75% . Anal. Calcd. for Me 2Ga(pz") 2Pd (C 3H 5): C, 41.2; H, 5.6; N, 12.8. Found: C, 41.3; H, 5.8; N, 13.2. 1H nmr ( x, CgDg): -GaMe2, 9.61 (s,3H), 9.66 (s,3H); pz-Me(3), 7.77 (s,6H); pz-H(4), 4.22 (s,2H); pz-Me(5), 7.93 (s,6H); a l l y l - H (unique), 4.89 (tt (J = 7,12 Hz), IH); a l l y l - H (syn), 6.59 (d (J= 7 Hz), 2H); a l l y l - H ( a n t i ) , 7.49 (d (J = 12Hz, 2H) . 6.2.3 Preparation of [Me 2Ga(pz") 2]Ni(C 3H 5) [ ( C 3 H 5 ) N i B r ] 2 + 2Na +[Me 2Ga(pz") 2 ] " T H F > 2[Me2Ga (pz" ) 2 J N i ( C ^ ) + 2NaBr (4 3) A THF solution of [ ( C 3 H 5 ) N i B r ] 2 (0.287 g; 0.8 mmol) was cooled to -78°C and a solution of Na+[Me:>Ga (pz") (1.6 mmol) - 150 -i n the same s o l v e n t added dropwise over 30 minutes. The c o l o u r of the s o l u t i o n g r a d u a l l y changed from red t o y e l l o w and a f t e r s t i r r i n g f o r a f u r t h e r 30 minutes a t 0°C, MgSO^ (~ 5 g) was added and the mixture f i l t e r e d . Removal of s o l v e n t from the f i l t r a t e gave yellow-brown f l a k e s of the product. Yield:0.27 g (70%). A n a l . C a l c d . f o r M e 2 G a ( p z " ) 2 N i ( C 3 H 5 ) : C, 46.2; H, 6.5; N, 14.4. Found: C, 46.0; H, 6.5; N, 14.4. 1H nmr (T, CgDg): -GaMe2, 9.19 (s,3H), 9.66 (s,3H); pz-Me(3), 7.81 (s,6H); pz-H(4), 4.36 (s,2H); pz-Me(5), 7.89 (s,6H); a l l y l - H (unique), 4.69 (m,lH); a l l y l - H (syn), 7.32 (d (J = 7 Hz), 2H); a l l y l - H ( a n t i ) , 8.02 (d (J = 1.5 Hz), 2H). 6.2.4 Reaction of Na +L~ wit h [ ( C 3 H 5 ) N i B r ] 2 A THF s o l u t i o n o f 'C-.H.-NiBr' was c o o l e d to -78°C and an equimolar amount of Na +L i n the same s o l v e n t added dropwise. Slowly the red s o l u t i o n became y e l l o w and a white p r e c i p i t a t e was observed. 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 1 h a t 0°C, v o l a t i l e s were removed i n vacuo. In some cases, a y e l l o w s o l i d co-condensed i n the c o l d t r a p and t h i s m a t e r i a l was i d e n -t i f e d as ( C 3 H ^ ) 2 N i by mass spectrometry. The remaining y e l l o w -brown r e s i d u e was e x t r a c t e d w i t h heptane to leave a green or blue r e s i d u e (the c o l o u r of the r e s i d u e depended on the s u b s t i -t u e n t s on the l i g a n d , L ) . The heptane e x t r a c t s were f i l t e r e d and e v a p o r a t i o n of the f i l t r a t e gave red c r y s t a l s of [Ni('pz') ( C 3 H j . ) ] 2 . F i n a l l y , the green or blue r e s i d u e was e x t r a c t e d with benzene. F i l t r a t i o n f o l l o w e d by e v a p o r a t i o n of the f i l t r a t e gave c r y s t a l s of L 2 N i , [ L N i ( p z ) ] 7 or L N i [ ( p z " ) 2 G a M e 2 ] . - 151 -(These compounds were discussed f u l l y i n Chapter I I ) . 6.2.5 Preparation of [ N i ( p z " ) ( C 3 H 5 ) ] 2 [ (C 3 H 5 ) N i B r ] 2 + 2Na +(pz")~ _ ™ H > [Ni (pz") (C 3H 5) ] 2 + 2NaBr (44) [ ( C 3 H 5 ) N i B r ] 2 (0.180 g; 0.5 mmol) was dissolved i n THF and a solution of Na +(pz") (0.118 g; 1.0 mmol) i n the same solvent added. The colour of the solution changed from red to yellow and a f t e r the reaction mixture was s t i r r e d for 2 h, the solvent was removed i n vacuo. The remaining yellow residue was r e c r y s t a l -l i z e d from benzene to give red c r y s t a l s . Y i e l d : 0.08 g (41%). Anal. Calcd. for N i ( p z " ) ( C 3 H 5 ) : C, 49.3; H, 6.2; N, 14.4. Found: C, 49.1; H, 6.3; N, 14.1. 1H nmr (T, CgDg): pz-Me, 7.64s, 7.71s, 7.89s; pz-H(4), 4.21s; a l l y l - H (unique), 4.59 m; a l l y l - H (syn), 7.2 m; a l l y l - H ( a n t i ) , ?. 6.2.6 Preparation of [Me^Gatpz") (OCH2CH2NMe2)] Cu(PPhQ + — THF '(PPh3)CuBr' + Na L (R=R'=Me) > LCu(PPh 3) + NaBr (4 5) A THF solution of Na +L (R=R'=Me) (1.6 mmol) was added to a s l u r r y of '(PPh^CuBr' (0. 649 g; 1.6 mmol) i n the same solvent and af t e r the reaction mixture was s t i r r e d overnight, solvent was removed i n vacuo. The remaining white ( s l i g h t l y tinged blue) s o l i d was extracted with toluene and the extracts f i l t e r e d . Slow evaporation of the f i l t r a t e gave large white c r y s t a l s of the product. Y i e l d : 0.77 g (80%). Anal. Calcd. f o r - 152 -M e 2 G a ( p z " ) ( O C H 2 C H 2 N M e 2 ) C u ( P P h 3 ) : C , 5 7 . 2 ; H , 6 . 3 ; N, 6 . 9 . Found: C , 5 7 . 6 ; H , 6 .4 ; N , 7 . 0 . ^ nmr (x, C g D g ) : - G a M e 2 , 9.97 ( s , 6 H ) ; p z - M e ( 3 ) , 7.66 ( s , 3 H ) ; p z - H ( 4 ) , 4 .01 ( s , l H ) ; pz-Me (5) , 7.85 ( s , 3 H ) ; - C H 2 C H 2 ~ , 5.97 (t (J = 5 H z ) , 2H) , 7 .90 ( t (J = 5 H z ) , 2H) ; - N M e 2 , 8.15 ( s , 6 H ) ; - P P h 3 , 2.41 (m,6H), 2 .95 (m,9H). 6 .2 .7 At tempted P r e p a r a t i o n of LCu(CO) (R=R'=Me) C u C l (1.0 mmol) was suspended i n a s o l u t i o n o f d i e t h y l e t h e r which was s a t u r a t e d w i t h c a r b o n monoxide and a s o l u t i o n o f N a + L (R=R'=Me, 1.0 mmol) i n THF was added d r o p w i s e o v e r a p e r i o d o f 30 m i n u t e s . S l o w l y a f l o c c u l e n t whi te p r e c i p i t a t e formed and a f t e r the r e a c t i o n m i x t u r e was s t i r r e d o v e r n i g h t (under an atmo-sphere of C O ) , the p a l e b l u e m i x t u r e was f i l t e r e d . The i r s p e c -trum o f the s o l u t i o n showed a v C Q band a t z 2070 cm x . However, a f t e r removal o f v o l a t i l e s i n v a c u o , the r e m a i n i n g w h i t e s o l i d showed no e v i d e n c e f o r a Cu-CO moie ty i n i t s i n f r a r e d s p e c t r u m . When the w h i t e s o l i d was t r e a t e d w i t h CO g a s , the i n f r a r e d s p e c -trum o f the r e s u l t i n g r e s i d u e showed a weak v C Q band a t 2078 c m - 1 . A g a i n , t h i s band d i s a p p e a r e d when the s o l i d was 'pumped i n v a c u o ' . The w h i t e s o l i d was reexamined a f t e r one week and ^H nmr and mass s p e c t r o m e t r y i n d i c a t e d t h a t the m a j o r i t y o f t h i s s o l i d was [ M e 2 G a ( O C H 2 C H 2 N M e 2 ) ] 2 , The p r o p e n s i t y of t h i s Cu compound to d e -compose as w e l l as i t s extreme s e n s i t i v i t y to a i r p r e v e n t e d a more d e t a i l e d s t u d y o f t h i s r e a c t i o n . - 153 -6.2.8 R e a c t i o n of NaV with F e 3 ( C O ) 1 2 Fe 3(CO)^2 w a s d i s s o l v e d i n THF and an e q u i v a l e n t amount (1 mole/Fe centre) of Na^L - was added. Immediately, the dark green s o l u t i o n became dark red and a gas was evolved (2 moles/ Fe c e n t r e ) . A f t e r the r e a c t i o n mixture was s t i r r e d f o r 3 h, s o l i d E t 4 N + C l was added. F u r t h e r e v o l u t i o n of gas (2 moles/Fe centre) was observed. Removal of s o l v e n t from t h i s mixture gave a dark red o i l which c o u l d not be induced to c r y s t a l l i z e . 6.2.9 Reaction of Na +L~ (R=R'=Me) wit h 'CofCQ^I' (112) To a s o l u t i o n of C o 2 ( C O ) g (0.342 g; 1.0 mmol) d i s s o l v e d i n e ther (25 ml) was added I 2 (0.253 g; 1.0 mmol) i n the same s o l v e n t (15 m l ) . 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 5 min at 20°C, the s o l v e n t was removed i n vacuo and the dark green r e s i d u e d i s s o l v e d i n THF (50 m l ) . Na +L~ (R=R'=Me, 2.0 mmol) i n THF was immediately added and a f t e r s t i r r i n g the mixture f o r 1 h, s o l v e n t was removed i n vacuo to l e a v e a p u r p l e b l u e s o l i d . Ex-t r a c t i o n of t h i s s o l i d with benzene gave a p u r p l e s o l u t i o n which on e v a p o r a t i o n gave 0.10 g of LCo [(pz" )2GaMe2 ] ( i d e n t i f i e d by mass s p e c t r o s c o p y ) . The remaining blue r e s i d u e was e x t r a c t e d w i t h CH 2C1 2 and e v a p o r a t i o n of the e x t r a c t s gave blue c r y s t a l s (0.13 g) which were i d e n t i f i e d as L C o 2 I 2 ( p z " H ) 2 by m i c r o a n a l y s i s . A n a l . C a l c d . f o r Me 2Ga(pz")(OCH 2CH 2NMe 2)Co 2I 2(pz"H) 2: C, 29.8; H, 4.6; N, 11.6. Found: C, 29.9; H, 4.7; N, 11.4. - 154 -6.3 R e s u l t s and D i s c u s s i o n 6 . 3 . 1 A l l y l i c D e r i v a t i v e s of N i c k e l and P a l l a d i u m In C h a p t e r V , the p r e p a r a t i o n s o f s e v e r a l compounds o f g e n e r a l f o r m u l a DNi(NO) (where D i s a t r i d e n t a t e p y r a z o l y l g a l l a t e l i g a n d ) were d i s c u s s e d . The f o r m a l r e p l a c e m e n t o f the NO l i g a n d by the i s o e l e c t r o n i c a l l y l l i g a n d l e a d s t o a marked d i f f e r e n c e i n the s t a b i l i t y o f the r e s u l t i n g compounds. When N a + L was r e a c t e d w i t h [ ( C ^ H ^ ) N i B r ] 2 , the i s o l a t e d g a l l i u m c o n t a i n i n g p r o -d u c t was i n e v i t a b l y t h e same N i ( I I ) p r o d u c t o b t a i n e d from the r e a c t i o n o f N a + L ~ w i t h N i B r 2 (see C h a p t e r I I ) . In a d d i t i o n , when N a + L ~ (R=R'=Me) was r e a c t e d w i t h [ ' a l l y l ' P d C l ] 2 ( ' a l l y l ' = C 3 H 5 , C 4 H ? ) the o n l y p r o d u c t i s o l a t e d was [Pd(pz") ' a l l y l ' ] 2 . In sharp c o n t r a s t t o t h e s e anomalous r e a c t i o n s , the r e a c t i o n o f [ ( C 3 H 5 ) N i B r ] 2 and [ ' a l l y l ' P d C l ] w i t h b i d e n t a t e p y r a z o l y l g a l l a t e l i g a n d s d i d g i v e the expec ted compounds. I n the case of the n i c k e l d e r i v a t i v e s , t h i s i s a g a i n i n d i r e c t c o n t r a s t t o the n i t r o s y l systems where N i n i t r o s y l compounds c o n t a i n i n g a b i s -p y r a z o l y l g a l l a t e l i g a n d c o u l d not be i s o l a t e d . I t s h o u l d be noted t h a t i n the c y c l o p e n t a d i e n y l sys tem, the compounds CpPd ( C 3 H 5 ) (107) and C p N i ( C 3 H 5 ) (113) have b o t h been p r e p a r e d and C p P d ( C 3 H 5 ) has been s t r u c t u r a l l y c h a r a c t e r i z e d (114) . I n a d d i -t i o n , the compound [HB(pz) 3 ] P d (CjH,-) has a l s o been p r e p a r e d but t h e ^ H nmr "data f o r t h i s compound s u g g e s t s a b i d e n t a t e p y r a z o l y l -b o r a t e l i g a n d (33) . [ M e 2 G a ( p z " ) 2 ] P d ' a l l y l ' and [ M e 2 G a ( p z " ) 2 ] N i ( C 3 H 5 ) were p r e -pared by the r e a c t i o n of N a + [ M e 2 G a ( p z " ) 2 ] ~ w i t h [ ' a l l y l ' P d C l 3 2 and [ (C-.H,-)NiBr ]_ r e s p e c t i v e l y . In each c a s e , the h i g h e s t m/e - 155 -observed i n the mass s p e c t r a of these compounds was due to the parent i o n (5%). Other s t r o n g s i g n a l s were due to the P-Me+ (60%) and P - M e - ' a l l y l ' - H + (100%) i o n s . The nmr spectrum of [Me 2Ga (pz" ) 2 ] P d (C3Hj.) i s shown i n F i g . 47 and t h a t o f [Me 2 G a ( p z " ) 2 ] P d ( C 4 H 7 ) i s s i m i l a r . In each case, o n l y one s i g n a l i s observed f o r each of the syn and a n t i protons o f the a l l y l group, and t h i s i s i n d i c a t i v e o f e i t h e r a r a p i d l y r o t a t i n g or symmetrically c o o r d i n a t e d (with r e s p e c t t o the g a l l a t e l i g a n d ) a l l y l group. The o b s e r v a t i o n o f two s i g n a l s f o r the Ga-Me protons i s c o n s i s t e n t w i t h a boat conformation f o r the Ga-fN-N^Pd r i n g and i n f a c t t h i s i s the conformation found f o r the Ga-(N-N)-2-Ni s i x membered r i n g of [Me 2Ga (pz") 2 ] N i (C 3H 5) i n the s o l i d s t a t e (63). The nmr spectrum of [ M e 2 G a ( p z " ) 2 ] N i (C 3H 5) was s i m i l i a r t o t h a t of [Me 2 G a ( p z " ) 2 ] P d ( C 3 H 5 ) but the s i g n a l s due t o the -GaMe2 protons were very broad. On c o o l i n g the sample s o l u t i o n , these s i g n a l s g r a d u a l l y sharpened (the low temperature l i m i t i n g spectrum was reached a t 0°C) and on warming the sample s o l u t i o n , these s i g n a l s disappeared and reappeared as a s i n g l e s i g n a l (60° C). A probable e x p l a n a t i o n f o r these o b s e r v a t i o n s i s t h a t at 'low temperature', the Ga-fN-Nf 2Ni r i n g i s s t a t i c but a t 'high temperature', the Ga-(N-N>Ni r i n g i s r a p i d l y i n v e r t i n g (Figure 48). A s i m i l a r mechanism has been proposed f o r [ M e 2 G a ( p z ) 2 ] 2 N i , where two Ga-Me s i g n a l s were observed a t 'low temperature' but on l y one Ga-Me s i g n a l i s observed at 'high temperature' (115). In the mechanism proposed f o r the present compound, i t has been assumed t h a t the a l l y l group i s r a p i d l y r o t a t i n g . - 157 -Figure 48. Proposed mechanism for the f l u x i o n a l process observed i n [Me2Ga(pz") ]N i ( C 3 H 5 ) . The Ni compound was also found to undergo a disproportiona-t i o n reaction i n solution: 2[Me 2Ga(pz") 2]Ni(C 3H 5)- < =-> [ Me2Ga (pz ") ] 2 + [Ni (pz") ( C ^ ) ] 2 (46) The extent of t h i s reaction was monitored by "'"H nmr spectroscopy. Freshly prepared solutions of [Me2Ga (pz") 2 ] N i (C3H,-) showed no extraneous sign a l s . However a f t e r 1 day (at rt) substantial amounts of [Me 2Ga(pz")] 2 and [Ni(pz")(C 3H 5 ) 1 2 were present i n the sample solution. (These were i d e n t i f i e d by comparison of the new signals with the ^H nmr spectra of the pure materials). The extent of disproportionation increased gradually over approxim-ately one week (at r t ) . However, a f t e r t h i s time, the r e l a t i v e amounts of [Me2Ga (pz") 2 ] N i (C 3H 5) , [Me2Ga (pz") 2~] 2 and [Ni(pz") ( C 3 H 5 ) ] 2 did not change s i g n i f i c a n t l y i n d i c a t i n g that an e q u i l i -brium had probably been established. The compound [Ni(pz") (C-H,.) ]~ could be prepared d i r e c t l y . - 158 -by the r e a c t i o n of N a + ( p z " ) ~ w i t h [{C^E^)NiBr] . The expec ted d i m e r i c n a t u r e o f t h i s compound was c o n f i r m e d by mass s p e c t r o -metry and t h e nmr spectrum was found t o be s i m i l a r t o t h a t of i t s p a l l a d i u m analogue (70) . The o b s e r v a t i o n o f f o u r s i g n a l s f o r the p y r a z o l y l - m e t h y l p r o t o n s and a f a i r l y c o m p l i c a t e d p a t t e r n f o r t h e a l l y l p r o t o n s i n d i c a t e s t h a t t h e a l l y l groups are p r o b -a b l y s t a t i c and e x i s t i n more t h a n one c o n f o r m a t i o n . V a r i a b l e temperature s t u d i e s on the p a l l a d i u m compound has shown t h i s m o l e c u l e t o p o s s e s s dynamic C 2 v symmetry a t ' h i g h ' t empera tures (70) . 6 .3 . 2 C u ( I ) D e r i v a t i v e s The compound LCu(PPh 3 )(R=R 1 =Me) was p r e p a r e d by the r e a c t i o n •of N a + L w i t h (PPh^jCuBr . T h i s compound was found to be a i r s t a b l e i n the s o l i d s t a t e and s t a b l e i n h y d r o c a r b o n s o l v e n t s under a n i t r o g e n atmosphere . However, on exposure o f s o l u t i o n s to a i r or on d i s s o l u t i o n of the s o l i d i n h a l o g e n a t e d s o l v e n t s , d e c o m p o s i t i o n i s e v i d e n c e d by the f o r m a t i o n of b l u e s o l u t i o n s . The mass spectrum o f LCu(PPh^) d i d not d i s p l a y the p a r e n t i o n s i g n a l . R a t h e r t h e h i g h e s t m/e o b s e r v e d was due t o the [ M e 2 G a ( p z " ) ( O C H 2 C H 2 N M e 2 ) C u ] + i o n . E v i d e n t l y the P P h 3 group i s not v e r y s t r o n g l y c o o r d i n a t e d . Other s t r o n g s i g n a l s o b s e r v e d + + + r i n the mass spectrum were due to the P P h 3 , P P h 2 , PPh , [.MeGa ( p z " ) ( O C H 2 C H 2 N M e 2 ) C u ] + and [ M e G a ( p z " ) ( 0 ) C u ] + i o n s . The "^ H nmr o f L C u ( P P h 3 ) (see F i g . 49) d i s p l a y e d one s i g n a l due t o the g a l l i u m - m e t h y l p r o t o n s , one s i g n a l due t o the N - m e t h y l p r o t o n s and two p s e u d o - t r i p l e t s due t o the - C H 9 C H 9 - g r o u p . 1 1 ' I I I I I | | | | | ) | | | | , | | i i | |. | | | , | | | | | | | ! , | | | | | | i i i | ! | , ! | | I I I I I I I I I I I I I I I I I 1 4 5 6 7 8 9 10 i s i g n a l s due t o PPh-j F i g u r e 49. 100 MHz 1 H nmr spectrum of [Me 2Ga (pz") (OCH 2 CH 2 NMe 2 ) ]Cu(PPh 3 ) i n C^D - 160 -A g a i n , t h i s i s s u g g e s t i v e of a m e r i d i o n a l l y c o o r d i n a t e d l i g a n d and c o n s e q u e n t l y a s q u a r e - p l a n a r Cu(I ) c e n t r e . However, t h i s geometry i s v e r y u n u s u a l f o r a Cu(I) c e n t r e and i n d e e d a low temperature "4i nmr s t u d y r e v e a l e d the f l u x i o n a l n a t u r e o f t h i s compound i n s o l u t i o n . On c o o l i n g t h e sample s o l u t i o n , the - G a M e 2 peak broadened ( b e g i n n i n g a t - 4 0 ° C ) , d i s a p p e a r e d and r e a p p e a r e d as two sharp s i n g l e t s a t -15°C. A p p a r e n t l y , t h e Cu(I) c e n t r e i s t e t r a h e d r a l l y c o o r d i n a t e d , but t h e m o l e c u l e undergoes a f l u x i o n a l p r o c e s s t h a t has a l r e a d y been o b s e r v e d i n s e v e r a l compounds i n -c o r p o r a t i n g t h i s t y p e o f l i g a n d ( F i g . 50 ) . P r e l i m i n a r y x - r a y s t r u c t u r a l d a t a f o r t h i s compound a l s o show a t e t r a h e d r a l l y c o o r d i n a t e d Cu c e n t r e i n the s o l i d s t a t e (63) . F i g u r e 50. Proposed mechanism f o r the f l u x i o n a l p r o c e s s o b s e r v e d i n [ M e 2 G a ( p z " ) ( O C H 2 C H 2 N M e 2 ] C u ( P P h 3 ) . In t h e o r y , the compound LCu(CO) where the CO l i g a n d f o r m -a l l y r e p l a c e s the PPh^ group s h o u l d e x i s t . However, i n p r a c t i c e copper c a r b o n y l compounds are v e r y u n s t a b l e (116) . O n l y r e c e n t l y have s t a b l e copper c a r b o n y l complexes been i s o l a t e d (8, 117) . These i n c l u d e t h e p y r a z o l y l b o r a t e complex , [HB(pz") 3 ] C u ( C O ) (8) and the e t h y l e n e t r i a m i n e complex , [Cu(dien) (CO) JBPh^ (117). In - 161 -b o t h c a s e s , the s t a b i l i t y o f the i s o l a t e d compounds was a t t r i b u t e d (at l e a s t i n p a r t ) t o the i n c r e a s e d e l e c t r o n d e n s i t y on the c o p -per c e n t r e which l e a d s t o a s t r o n g e r Cu-CO bond ( v C Q [HB(pz") ] Cu(CO) = 2066 c m - 1 , v C 0 [ C u ( d i e n ) (CO)] B P h 4 = 2080 c m " 1 ) . When N a + L (R=R'=Me) was r e a c t e d w i t h C u C l i n the p r e s e n c e o f CO, a v c o band was d e t e c t e d i n s o l u t i o n a t 2070 c m - 1 ( d i e t h y l e t h e r s o l v e n t ) . However, when the s o l v e n t was removed i n v a c u o , the i r spect rum of t h e r e m a i n i n g s o l i d d i d not show a v C Q b a n d . The w h i t e s o l i d i s o l a t e d was found to be e x t r e m e l y a i r s e n s i t i v e , t u r n i n g b l u e i n s t a n t a n e o u s l y on exposure to the a tmosphere . On exposure o f t h e w h i t e s o l i d t o CO g a s , a weak v C Q band appeared i n the i n f r a r e d spect rum but a g a i n d i s a p p e a r e d on pumping the s o l i d i n v a c u o . A l t h o u g h the c l e a r p o s s i b i l i t y o f r e v e r s i b l e c a r b o n monoxide b i n d i n g e x i s t s w i t h t h i s compound, i t s u n s t a b l e c h a r a c t e r p r e v e n t e d any f u r t h e r m e a n i n g f u l s t u d i e s . A f t e r 1 week, t h e m a j o r i t y o f t h e w h i t e s o l i d was found t o be [Me 2 Ga ( O C H 2 C H 2 N M e 2 ) ] . 6 . 3 . 3 R e a c t i o n s o f N a + L (R=R'=Me) w i t h I r o n and C o b a l t  ' C a r b o n y l s ' The compounds C p C o ( C O ) 2 (118) and C p F e ( C O ) 2 ~ (119) are w e l l known compounds i n c o r p o r a t i n g the c y c l o p e n t a d i e n y l l i g a n d and f o r m a l l y analogous compounds i n c o r p o r a t i n g the l i g a n d L ought to be i s o l a b l e . However, when N a + L (R=R=Me) was r e a c t e d w i t h C o ( C O ) 4 I , a l l the c a r b o n y l l i g a n d s were d i s p l a c e d and a m i x t u r e of LCo [ ( p z " ) 2 G a M e 2 ] and L C o 2 I 2 ( p z " H ) 2 was i s o l a t e d . The former compound had been p r e p a r e d p r e v i o u s l y from N a + L and - 162 -C 0 C I 2 and i s d i s c u s s e d i n Chapter I I . The l a t t e r compound was i d e n t i f i e d p r i n c i p a l l y on the b a s i s o f m i c r o - a n a l y s i s . I r s p e c t r o s c o p y showed the p r e s e n c e o f two N-H s t r e t c h i n g bands a t 3310 and 3500 cm 1 and the h i g h e s t m/e o b s e r v e d i n the mass spectrum o f t h i s compound was due to the [ L C o l ] + i o n . A l i k e l y s t r u c t u r e f o r t h i s compound i s shown i n F i g u r e 51. F i g u r e 51. P o s s i b l e s t r u c t u r e of [ M e 2 G a ( p z " ) ( O C H 2 C H 2 N M e 2 ) ] C o 2 ( I ) 2 ( p z " H ) 2 . When F e ^ l C O ) ^ w a s r e a c t e d w i t h 3 e q u i v a l e n t s of N a + L ~ (R=R'=Me), two moles of CO p e r mole of Fe were e v o l v e d . P r e -sumably , t h i s o b s e r v a t i o n i n d i c a t e s the f o r m a t i o n o f L F e ( C O ) 2 . However, when E t ^ N + C l was added t o the dark r e d s o l u t i o n , f u r t h e r gas e v o l u t i o n o c c u r r e d and the i s o l a t e d r e d o i l c o n t a i n e d no CO l i g a n d s . From these two r e a c t i o n s , i t can be r e a d i l y seen t h a t the c a r b o n y l groups on i r o n and c o b a l t a re e a s i l y d i s p l a c e d by the c h e l a t i n g g a l l a t e l i g a n d s . T h i s i s a l s o t r u e of the r e l a t e d n i t r o s y l l i g a n d . When C o ( N O ) ( C O ) 3 and F e ( N O ) 2 ( C O ) 2 was r e a c t e d + — w i t h Na L. , the p r o d u c t s were a g a i n c a r b o n y l and n i t r o s y l f r e e . - 163 -6.3.4 Related Tridentate Ligands The main part of t h i s thesis has described the reactions of various t r a n s i t i o n metal species with the ligands [Me 2Ga(pz) (OCH 2CH 2NR' 2)]" and [Me 2Ga(pz")(OCH 2CH 2NR' 2)]~ (R'=H or Me). ^ The v e r s a t i l i t y of the g a l l a t e ligands and the preparation of a variety of unique derivatives prompted the synthesis of a number of related chelating ligands. These can be prepared by reaction of a suitable compound with the [Me^Ga('pz' ) ] ion: Na +[Me 3Ga( 'pz')]" + XH _?ii!L> Na +[Me 2Ga ( 'pz') (X) ] ~ + MeH (47) The following 'XH' compounds have been u t i l i z e d i n t h i s reaction: Ph2PCH2CH2OH, H2NCH2CH2CH2OH, H2NC(Me)2CH2OH, Me(H)NCH2CH2OH, R2NCH2CH2SH (R=H or Me) and RSCH2CH2OH (R=Et or Ph). With the exception of the ligand [Me 2Ga('pz')(OCH 2CH 2SR)]~, which was studied extensively by S. Ford i n our laboratory, only prelimin-ary reactions have been car r i e d out with these new ligands. In general, the ligand [Me2Ga( 'pz') (OCH 2CH 2SEt)]~ behaves very s i m i l a r l y to the ligands, L , but i r evidence suggests that i t i s a s l i g h t l y weaker electron donor or a better TT acceptor. The ligands incorporating the 'H2NC (Me2) CH20' , 'Me (H) NCHjO^O' and 'H2NCH2CH2GH20' moieties were found to form octahedral b i s -ligand complexes with divalent t r a n s i t i o n metal halides and so are not as s t e r i c a l l y demanding as the ligands incorporating the 'Me2NCH2CH20' moiety. However, the octahedral complexes derived from ligands incorporating the 'Me(H)NCH2CH20' and 'H2NC(Me)2CH20' moieties were found to be considerably more sensitive to a i r than compounds derived from ligands incorporating the 'H^ NCH^ CH^ O' - 164 -moiety. The ligands incorporating the 'SCrj^Cr^NF^' moiety appear to behave s i m i l a r l y to the ligands incorporating the *OCH2CH2NR2' but do increase the s o l u b i l i t y of the r e s u l t i n g compounds con-siderably. F i n a l l y , ligands incorporating the ,OCH 2CH 2PPh 2' moiety have so far yielded no i s o l a b l e complexes, and t h i s may well be due to s t e r i c reasons. 6.4 Conclusions and Perspectives At the beginning of t h i s work, one of the primary objectives was to develop synthetic routes to t r a n s i t i o n metal compounds incorporating asymmetric g a l l a t e ligands and to demonstrate the v e r s a t i l i t y of these ligands. To t h i s end, t h i s objective has been l a r g e l y f u l f i l l e d . The behavior of these ligands towards a number of 2 and 3 row t r a n s i t i o n metal compounds, p a r t i c -u l a r l y those of Ru and Rh remains to be investigated. In addition, the generality of the synthetic routes developed should be investigated with related ligands such as those discussed i n Sec. 6.3.4. Moreover, the scope of asymmetric ligands may be widened further by incorporating r i n g systems other than pyrazole and the d e n t i c i t y of the ligands can be modified by using appro-priate 'X-H' compounds in the reaction given by Eq. (47). A further area that could be investigated more f u l l y i s the general chemical behavior of the compounds described i n t h i s t h e s i s . Several of the compounds prepared have exhibited stereo-s p e c i f i c i t y i n t h e i r reactions, stereochemical n o n r i g i d i t y i n solution and some are coordinatively unsaturated. These prop-e r t i e s suggest that selected compounds may well f i n d useful ap-pl i c a t i o n s i n c a t a l y s i s . - 165 -BIBLIOGRAPHY 1. J . G . Vos and V . L . G r o e n v e l d , I n o r g . C h i m . A c t a 2_4, 123 (1977); 26, 71 (1978). 2. N . F . B o r k e t t and M . I . B r u c e , J . Organomet. Chem. 6_5, C51 (1974) . 3. G . M i n g h e t t i , G. B a n d i t e l l i , and F . B o n a t i , I n o r g . Chem. 18, 658 (1979). 4. S. T r o f i m e n k o , A c c t s . Chem. Res . 4_, 17 (1971) . 5. S . T r o f i m e n k o , Chem. Rev. 72_, 497 (1972). 6. A . S h a v e r , J . Organomet. Chem. L i b r a r y 3_, 157 (1977) . 7. G . J . B u l l e n , R. Mason, and P. P a u l i n g , I n o r g . Chem. 4_, 456 (1965), and r e f e r e n c e s w i t h i n . 8. M . I . Bruce and A . P . P . O s t a z e w s k i , J . Chem. S o c . D a l t o n T r a n s . , 2433 (1973). 9. F . A . C o t t o n and T . J . M a r k s , J . Am. Chem. S o c . 9_2, 5114 (1970). 10. K . R . B r e a k e l l , D . J . Patmore , and A . S t o r r , J . Chem. S o c . D a l t o n T r a n s . , 749 (1975). 11. K . R . B r e a k e l l , S . J . R e t t i g , D . L . S i n g b e i l , A . S t o r r , and J . T r o t t e r , C a n . J . Chem. 5_6, 2099 (1978). 12. K . R . B r e a k e l l , S . J . R e t t i g , A . S t o r r , and J . T r o t t e r , C a n . J . Chem. 57, 139 (1979). 13. K . S . Chong, S . J . R e t t i g , A . S t o r r , and J . T r o t t e r , C a n . J . Chem. 55, 4166 (1977) . 14. K . S . Chong, B . S c . T h e s i s , U . B . C . (1976). 15. W . L . J o l l y , The S y n t h e s i s and C h a r a c t e r i z a t i o n o f I n o r g a n i c  Compounds, P r e n t i c e H a l l , N . J . (1970). 16. D . M . Adams, M e t a l - L i g a n d and R e l a t e d V i b r a t i o n s , Edward ' A r n o l d , London (1967). 17. S. T r o f i m e n k o , J . Am. Chem. S o c . 89 ,^ 3170 (1967). 18. K . S . Chong, S . J . R e t t i g , A . S t o r r and J . T r o t t e r , C a n . J . Chem. 56, 1212 (1978). 19. K . S . Chong, S . J . R e t t i g , A . S t o r r and J . T r o t t e r , C a n . J . Chem. 57, 586 (1979). - 166 -20. M. A r e s t a , C F . N o b i l e and D. P e t r u z z e l l i , Inorg. Chem. 16, 1817 (1977). 21. A. S t o r r and B.S. Thomas, Can. J . Chem. 4_8, 3667 (1970). 22. S.J. R e t t i g , A. S t o r r and J . T r o t t e r , Can. J . Chem. 52, 2206 (1974). 23. G.E. Coates and K . Wade, Organ o m e t a l l i c Compounds: the  main group elements V o l . 1 3rd ed., Methuen, London (1967). 24. A.P.B. Lever, Inorganic E l e c t r o n i c Spectroscopy, E l s e v i e r , New York (1968). 25. C. F u r l a n i , Gazz. Chim. I t a l . J57 , 371 (1957). 26. M. C i a m p o l i n i , Inorg. Chem. 5, 35 (1966). 27. M. C i a m p o l i n i and N. N a r d i , Inorg. Chem. 5_, 41 (1966). 28. P.L. O r i o l i " and M. D i V a i r a , i n o r g . Chem. 6, 955 (1967). 29. L. Sacconi, Coord. Chem. Rev. 8_, 351 (1972). 30. M. D i V a i r a , J . Chem. Soc. Dalton Trans., 1575 (1975). 31. J.S. Wood, Inorg. Chem. ]_, 852 (1968). 32. D.F. Rendle, A. S t o r r and J . T r o t t e r , J . Chem. Soc. Dalton Trans., 176 (1975). 33. S. Trofimenko, J . Am. Chem. Soc. 9_1; 588 (1969). 34. M. Cousins and M.L.H. Green, J . Chem. S o c , 899 (1968). 35. R.B. King and M.B. B i s n e t t e , Inorg. Chem. 3_, 785 (1964) . 36. S. Trofimenko, Inorg. Chem. 8_, 2675 (1969). 37. R.B. King and M.B. B i s n e t t e , Inorg. Chem. 5_, 300 (1966) . 38. K.S. Chong, S.J. R e t t i g , A. S t o r r and J . T r o t t e r , Can. J . Chem. 58_ (1980) . 39. K.S. Chong and A. S t o r r , Can. J . Chem. 57_, 167 (1979). 40. E.W. Abel and G. W i l k i n s o n , J . Chem. S o c , 1501 (1959). 41. D.P. Tate, W.R. Knipple and J.M. Augl, Inorg. Chem. 1, 433 (1962). 42. D.E.F. Gracey, W.R. Jackson, W.B. Jennings and T.R.B. M i t c h e l l , J . Chem. Soc. (B), 1204 (1969). - 167 -43. R . B . K i n g and A . F r o n z a g l i a , I n o r g . Chem. 5_, 1837 (1966). 44. R . B . K i n g , O r g a n o m e t a l l i c S y n t h e s i s , Academic P r e s s , New York (1965). 45. H . J . Dauben, L . R . Honnen and K . M . Harman, J . O r g . Chem. 25, 1442 (1960). 46. F . G . B o r d w e l l and B . M . P i t t , J . Am. Chem. S o c . 572 (1955). 47. S . R . S a n d l e r and W. K a r o , O r g a n i c Chem. 12_, 402 (1968). 48. F . A . C o t t o n , I n o r g . Chem. 3, 702 (1964). 49. R . D . F i s c h e r , Chem. B e r . 9_3/ 165 (1960). 50. R . B . K i n g , J . Organomet. Chem. 100, 111 (1975). 51. A . E . Crease and P . L e g z d i n s , J . Chem. S o c . D a l t o n T r a n s . , 1501 (1973). 51a. D. S u t t o n , C a n . J . Chem. 5_2, 2634 (1974) . 52. R . G . H a y t e r , J . Organomet. Chem. 13_, P l (1968). 53. J .W. F a l l e r and M . J . I n c o r v i a , I n o r g . Chem. 1_, 840 (1968) . 54. K . S . Chong, S . J . R e t t i g , A . S t o r r and J . T r o t t e r , C a n . J . Chem. 57, 1335 (1979). 55. C F . P u t n i k , J . J . W e l t e r , G . D . S t u c k y , M . J . D ' A n i e l l o J r . , B . A . S u s i n s k y , J . F . K i r n e r and E . L . M u e t t e r t i e s , J . Am. Chem. S o c . 100, 4107 (1978). 56. J . A . Kaduk, A . T . P o u l o s and J . A . I b e r s , J . Organomet. Chem. 127, 245 (1977). 57. J . L . C a l d e r o n , F . A . C o t t o n and A . S h a v e r , J . Organomet. Chem. 57, 121 (1973). 58. F . A . C o t t o n and C R . R e i c h , J . Am. Chem. S o c . 9_1, 847 (1969) . 59. G. D e g a n e l l o , T . B o s c h i and L . T o n i o l o , J . Organomet. Chem. 97_, C46 (1975) . 60. J . W . F a l l e r , I n o r g . Chem. 8, 767 (1969). 61. F . A . C o t t o n , M. J e r e m i c and A . S h a v e r , I n o r g . C h i m . A c t a . 6, 543 (1972). 62. J . L . C a l d e r o n , F . A . C o t t o n and A . S h a v e r , J . Organomet. Chem. 42, 419 (1972). - 168 -63. S . J . R e t t i g , p e r s o n a l c o m m u n i c a t i o n . 64. R . B . K i n g and M . B . B i s n e t t e , I n o r g . Chem. 4_, 486 (1965) . 65. R . B . K i n g , I n o r g . Chem. 5, 224.3 (1966). 66. E . R . d e G i l and L . F . D a h l , J . Am. Chem. S o c . £ 1 , 3751 (1969). 67. B . F . G . Johnson and J . A . M c C l e v e r t v , P r o g r . I n o r g . Chem. 7, 277 (1966). 68. A . S t o r r , p e r s o n a l c o m m u n i c a t i o n . 69. M. Inoue, M. K i s h i t a and M. Kubo, I n o r g . Chem. 4^ 626 (1965). 70. S. T r o f i m e n k o , I n o r g . Chem. 1 £ , 1372 (1971). 71. A . N . Nesmeyanov, V . N . B a b i n , N . S . K o c h e t k o v a , Y . S . N e k r a s o v , Y . A . B e l o u o v and S . Y . S i l ' v e s t r o v a , D o k l . C h e m . , P r o c . A c a d . S c i . , USSR Chem. S e c , 738 (1974). 72. S. T r o f i m e n k o , J . Am. Chem. S o c 91, 5410 (1969). 73. K . S . Chong, S . J . R e t t i g , A . S t o r r and J . T r o t t e r , C a n . J . Chem. 57, 3090 (1979). 74. K . S . Chong, S . J . R e t t i g , A . S t o r r and J . T r o t t e r , C a n . J . Chem. 5_7, 3099 (1979) . 75. K . S . Chong, S . J . R e t t i g , A . S t o r r and J . T r o t t e r , C a n . J . Chem. 57, 3119 (1979) . 76. B . Haymore and R . D . F e l t h a m , I n o r g . S y n t h . _L4, 81 (1973). 77. J . E l g u e r o , E . G o n z a l e z and R. J a c q u i e r , B u l l . S o c . Chim. F r . 2, 707 (1968). 78. N . S . G i l l , R . H . N u t t a l l , D . E . S c a r f e and D . W . A . S h a r p e , J . I n o r g . N u c l . Chem. 18_, 79 (1961). 79. R . J . H . C l a r k and C S . W i l l i a m s , I n o r g . Chem. 4, 350 (1965). 80. J . H . Enemark, I n o r g . Chem. 10, 1952 (1971). 81. K . J . H a l l e r and J . H . Enemark, I n o r g . Chem. 17_, 3552 (1978). 82. J . H . Enemark and R . D . F e l t h a m , C o o r d . Chem. Rev. 13_, 339 (1974) . 83. R . T . B a k e r , S . J . R e t t i g , A . S t o r r and J . T r o t t e r , C a n . J . Chem. 54_, 343 (1976) . - 169 -84. R.B. King and A. Bond, J . Am. Chem. Soc. 96_, 1343 (1974). 85. L.F. Dahl, E.R. d e G i l and R.D. Feltham, J . Am. Chem. Soc. 91, 1653 (1969). 86. A. John, Z. Anor'g. A l l g . Chem. 301, 301 (1959). 87. W. Hieber and I. Bauer, Z. Anorg. A l l g . Chem. 321, 107 (1963) . 88. W. Beck and K. L o l t e s , Z. Anorg. A l l g . Chem. 325, 258 (1965). 89. R.G. Copperwaite, R.H. Reimann and E. S i n g l e t o n , Inorg. Chim. A c t a . 28^ , 107 (1978) . 90. B.F.G. Johnson and J.A. McCleverty, Prog. Inorg. Chem. 1_, 277 (1966) . 91. K.S. Chong, S.J. R e t t i g , A. S t o r r and J . T r o t t e r , Can. J . Chem. 5_7, 3113 (1979) . 92. K.S. Chong, S.J. R e t t i g , A. S t o r r and J . T r o t t e r , Can. J . Chem. 57, 3107 (1979) . 93. R.H. Reimann and E. S i n g l e t o n , J . Chem. Soc. Dalton Trans., 841 (1973). 94. F.A. Cotton and B.F.G. Johnson, Inorg. Chem. 3_, 1609 (1964) . 95. T.S. P i p e r , F.A. Cotton and G. W i l k i n s o n , J . Inorg. N u c l . Chem. 1, 165 (1955), 96. E.O. F i s c h e r , 0. Beckert, W. Hafner and H.O. S t a h l , Z. N a t u r f o r s c h 10b, 598 (1955). 97. I.A. Ronova, N.V. Alekseeva, N.N. Veniaminov and M.A. Kravers, Zh. S t r u k t . Khim. 16_, 476 (1975). 98. G. W i l k i n s o n , P.L. Pauson, J.M. Birmingham and F.A. Cotton, J . Am. Chem. Soc. _75, 1011 (1953). 99. R.B. King, Inorg. Chem. ]_, 90 (1968). 100. A. A r d u i n i and A. S t o r r , J . Chem. Soc. Dalton Trans., 503 (1974). 101. R.B. King, Inorg. Chem. 6_, 30 (1967). 102. H. Brunner, J . Organomet. Chem. 14, 173 (1968). 103. M. L a i n g , R. Reimann and E. S i n g l e t o n , Inorg. Nucl. Chem. L e t t . 10, 557 (1974). - 170 -104. M. L a i n g , R. Reimann and E . S i n g l e t o n , I n o r g . Chem. 18, 324 (1979). 105. B . F . G . Johnson and J . A . M c C l e v e r t y , P r o g . I n o r g . Chem. 7_, 277 (1966). 106. G . W i l k e , B . B o g d a n o v i c , P . H a r d t , P . Heimbach, W. Keim, M. K r o n e r , W. O b e r k i r c h , K. T a n a k a , E . S t e i n r i i c k e , D. W a l t e r and H . Zimmerman, Angew. Chem. I n t e r n a t . E d i t . 5, 151 (1966). 107. B . L . Shaw, P r o c . Chem. S o c , 247 (1960). 108. G. C o s t a , E . R e i s e n h o f e r and L . S t e f a n i , J . I n o r g . N u c l . Chem. 27, 2581 (1965). 109. W. H i e b e r and H . B e u t e r , Z . A n o r g . A l l g e m . Chem. 320, 101 (1963) . 110. W . C . F e r n e l i u s , I n o r g . S y n t h . 2, 239 (1946). 111. W. M c F a r l a n e and G. W i l k i n s o n , I n o r g . S y n t h . £ , 181 (1964) . 112. E . J . B u l t e n and H . A . B u d d i n g , J . Organomet. Chem. 8_2, 121 (1974) . 113. W.R. M c C l e l l a n , H . H . Huehn, H . N . C r i p p s , E . L . M u e t t e r t i e s and B.W. Howk, J . Am. Chem. S o c . 83_, 1601 (1961). 114. M. K h . M i n a s y a n t s and Y u . T . S t r u c h k o v , Z h . S t r u k t . Khim. 9, 481 (1968). 115. F . G . H e r r i n g , D . J . Patmore and A . S t o r r , J . Chem. S o c . D a l t o n T r a n s . , 711 (1975). 116. F . H . J a r d i n e , A d v . I n o r g . Chem. Radiochem. 17_, 115 (1975). 117. M. P a s q u a l i , F . M a r c h e t t i and C . F l o r i a n i , I n o r g . Chem. 17, 1684 (1978). 118. R . B . K i n g and F . G . A . S t o n e , I n o r g . S y n t h . 7, 99 (1963). 119. T . S . P i p e r and G . W i l k i n s o n , J . I n o r g . N u c l . Chem. 3_, 104 (1956). - 171 -APPENDIX I THEORETICAL INTENSITY PATTERNS FOR MASS SPECTROSCOPIC ANALYSIS N i , 138 1 4 0 142 m /e 1 116 118 120 122 m/e N i - G a N i - G a . 127 129 131 133m/e 196 i«e 555 555 m/l - 172 -C u - G a . "201 2o3 265 207 m'/e" C u - G a "133 i53 i36 M o - G a 161 163 164 165 166 167 168 169 171 m/e W - G a 251 252 253 254 255 257 m/e - 174 -APPENDIX I I STEREO DIAGRAMS OF SOME OF THE PREPARED COMPOUNDS CI10) [ M e 0 G a ( p z ) 0 ( O C H 2 C H 2 N M e 2 ) C u ] [ M e 2 N C H 2 C H 2 0 ' G a M e 2 ] 2 - 175 -H„NCH_CH_0•GaMe sym-fac [Me 2Ga(pz)(OCH 2CH 2NH 2)] 2Ni - 176 -[ M e 2 G a ( p z " ) ( O C H 2 C H 2 N M e 2 ) ] N i [ ( p z " ) 2 G a M e 2 ] - 177 -[ M e 2 G a ( p z ) ( O C H 2 C H 2 N M e 2 ) ] M o ( C O ) 2(n 2 - C H 2 S M e ) - 178 -[ N i ( p z " ) ( N O ) ] 2 - 179 -[Co(pz" ) ( N O ) 2 ] 2 - 180 -E t 4 N + [ ( O N ) N i ( p z " ) 2 ( I ) N i ( N O ) ] - 181 -[ N a - 2 T H F ] + [ ( O N ) N i ( p z " ) 3 N i ( N O ) ] [ M e 2 G a ( p z " ) ( O C H 2 C H 2 N M e 2 ) ] N i ( N O ) - 182 -[ M e 2 G a ( p z " ) 2 ] N i ( C 3 H 5 ) \ PUBLICATIONS "Synthes i s and C h a r a c t e r i z a t i o n of B i n u c l e a r T r a n s i t i o n Metal Complexes I n c o r p o r a t i n g the T r i d e n t a t e C h e l a t i n g Ligand Dimethyl (N,N-dimethyl-ethanolamino)1-pyrazolyl) g a l l a t e ; C r y s t a l and Mo l e c u l a r S t r u c t u r e o f B i s - y - p y r a z o l y l ( N ( l ) , N ( 2 ) ) - b i s [ d i m e t h y l ( N , N - d i m e t h y l e t h a n o l a m i n o ) ( 1 -p y r a z o l y l ) g a l l a t o (N(2),0,N) copper ( I I ) ] , by K.S. Chong, S.J. R e t t i g , A. S t o r r and J . T r o t t e r , Canad. J . Chem.,55, 4166 (1977). "S y n t h e s i s , C h a r a c t e r i z a t i o n and X-ray S t r u c t u r a l S t u d i e s of O c t a h e d r a l T r a n s i t i o n Metal Complexes I n c o r p o r a t i n t the Novel A n i o n i c T r i d e n t a t e Ligand Dimethyl(ethanolamino) ( 1 - p y r a z o l y l ) g a l l a t e [ M e 2 G a ( O C H 2 C H N H „ ) ( N 2 C H 3 ] " " , by K.S. Chong, S.J. R e t t i g , A. S t o r r and J . T r o t t e r , Canad. J . Chem. 56, 1212 (1978). "Molybdenum, Tungsten and Manganese Carbonyl Compounds I n c o r p o r a t i n g Novel T r i d e n t a t e C h e l a t i n g D i m e t h y l ( 1 - p y r a z o l y l ) ( e t h a n o l a m i n o ) g a l l a t e Ligands", by K.S. Chong and A. S t o r r , Canad. J . Chem.,57, 167 (1979). "Synthesis and C r y s t a l and Mo l e c u l a r S t r u c t u r e of E t h a n o l -aminogallium dimethyl,H 2NCH 2CH 20•GaMe 2", by K.S. Chong, S.J. R e t t i g , A. S t o r r and J . T r o t t e r , Canad. J . Chem., 57, 586 (1979). 3 " C r y s t a l and Molecular S t r u c t u r e of (n - 2 - m e t h y l a l l y l ) [ d i m e t h y l ( e t h a n o l a m i n o ) ( 3 , 5 - d i m e t h y l - p y r a z o l y l ) g a l l a t o ( N ( 2 ) , (N(3) , (0) ] d i c a r b o n y l molybdenum, [Me„Ga (N-C.-H ) (OCH CH NH )] Mo (CO) 2(n -C.H ", by K.S.Chong, S.J7 R e t t i g , A. S t o r r and J . T r o t t e r , Canad. J . Chem.,57, 1335 (1979). "N e u t r a l P y r a z o l y l - b r i d g e d n i c k e l n i t r o s y l complexes. S y n t h e s i s , S t r u c t u r e and R e a c t i v i t y " , by K.S. Chong, S.J. R e t t i g , A. S t o r r and J . T r o t t e r , Canad. J . Chem., 57, 3090 (1979). "A n i o n i c P y r a z o l y l - b r i d g e d n i c k e l n i t r o s y l complexes. S y n t h e s i s , S t r u c t u r e and R e a c t i v i t y " , by K.S. Chong, S.J. R e t t i g , A. S t o r r and J . T r o t t e r , Canad. J . Chem.,57, 3099 (1979). "Reactions of Ni(NO)I wirh p y r a z o l y l g a l l a t e l i g a n d s : c r y s t a l and molecular s t r u c t u r e of [Me„Ga(N„C H )(OCH„CH NMe„)] Ni(NO)", by K.S. Chong, S.J. R e t t i g f A. S t o r r and J . T r o t t e r , Canad. J . Chem. 57, 3107 (1979). " F i v e - c o o r d i n a t e i r o n and manganese d i n i t r o s y l complexes i n c o r p o r a t i n g t r i d e n t a t e c h e l a t i n g d i methyl ( 1 - p y r a z o l y l ) N,N-dimethylethanolamino) g a l l a t e l i g a n d s : c r y s t a l and molecular s t r u c t u r e of ^Me 2Ga(N C H )(OCH CH 2NMeJ]Fe(NO) 2", by K.S. Chong, S.J. R e t t i g , A. s t o r r and J . T r o t t e r , Canad. J . Chem., 57, 3113 (1979). "Synthesis and S t r u c t u r e of 3 , 5 - d i m e t h y l p y r a z o l y l i r o n and c o b a l t d i n i t r o s y l dimers", by K.S. Chong, S.J, R e t t i g , A. S t o r r and J . T r o t t e r , Canad. J . Chem., 57, 3119 (1979). 

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