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Infrared spectroscopic studies of some organotin (IV) and organoantimony (V) derivatives Goel, Ram Gopal 1965

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The U n i v e r s i t y o f B r i t i s h  Columbia  FACULTY OF GRADUATE STUDIES  PROGRAMME OF THE FINAL ORAL EXAMINATION FOR THE DEGREE OF DOCTOR OF PHILOSOPHY  of  RAM GOPAL GOEL  BPSC.~„ U n i v e r s i t y  o f Lucknow*  TUESDAY, SEPTEMBER 2 1 AT IN ROOM 2 6 1  S  3.952  1.965  1 ; 3 0 P.M.  k  CHEMISTRY BUILDING  COMMITTEE IN CHARGE Chairman;  R, C= Mann R„ Stewart A, S t o r r Ro C= Thompson  F. W, Dalby Co A. McDowell. G, Bo P o r t a r E x t e r n a l Examiner; Department  G.-E, Coa.tes  o f Chemistry  The U n i v e r s i t y o f Durham Durham Cit.y  ;;  England  INFRARED SPECTROSCOPIC STUDIES OF AND  SOME ORGANOTIN (IV) ]  ORGANOANTIMONY(V); DERIVATIVES  ABSTRACT  Triphenyl-,  t r i m e t h y l - and  trimethylantimony(V), of a c i d s  3  derivatives  of a wide v a r i e t y  i n c l u d i n g those of v e r y s t r o n g  well, as d e r i v a t i v e s were s y n t h e s i z e d . i n the  d i m e t h y l t i n ( I V ) . , and  spectra.  as  of a t r a n s i t i o n metal o x y a n i o n Their  s  structural characteristics  s o l i d s t a t e , under s t r i c t l y  conditions,  acids,  anhydrous  were determined from t h e i r  These s p e c t r o s c o p i c  infrared  r e s u l t s can  only  be  interpreted  i n terms of a v e r y s t r o n g  interaction  between the  organometal group and  corresponding  anionic  group  coordination  s  and  provide strong  or p a r t i a l c o v a l e n t  organometal group and to e a r l i e r r e p o r t s  s  existence  of f r e e R.jSn  the  state.  solid  evidence f o r bonding between  the a n i o n i c  no  the  group,  Contrary  evidence i s found f o r + s  R2Sn^  +  or R2Sb^  the  +  the  cations  in  GRADUATE STUDIES Field  of Study:  Inorganic  Chemistry  Chemistry  R. M. H o c h s t r a s s e r H. C. C l a r k N. B a r t l e t t W. Ro C u l l e n  i n P h y s i c a l Chemistry  J , A. R. Coope A. V. Bree  P h y s i c a l Inorganic  Topics  1  Seminar Topics  • W.: A. i n Inorganic  Advanced I n o r g a n i c  Molecular  Chemistry  Chemistry  Structure  S o l i d S t a t e Chemistry Crystal  Structure  Grganometallic Topics  Chemistry  i n O r g a n i c Chemistry  Bryce  No B a r t l e t t H. C. C l a r k W. R. C u l l e n H. C. C l a r k W. R. C u l l e n C. R e i d E. J . W e l l s L. H. Reeves K„ B. Harvey L, G.  Harrison  J, T r o t t e r So A= Melzak H. C.  Clark  J= P. Kutney A. I . S c o t t F. McCapra  PUBLICATION  H, C= C l a r k and R= G. G o e l R e a c t i o n s o f O r g a n o t i n Compoundso V. S t u d i e s o f Some F u r t h e r T r i - and D i organotin Derivatives, Inorg, Chem.  s  (1965).  In press,  INFRARED SPECTROSCOPIC STUDIES OF SOME ORGANOTIN(IV) AND ORGANOANTIMONY(V) DERIVATIVES  by RAM GOPAL GOEL B.Sc., U n i v e r s i t y of Lucknow, 1952 M . S c , U n i v e r s i t y of Lucknow, 1955  A THESIS SUBMITTED  IN PARTIAL FULFILMENT OF  THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY i n the Department of Chemistry  We accept t h i s t h e s i s as conforming required  to the  standard  THE UNIVERSITY OF BRITISH COLUMBIA August 1965  In p r e s e n t i n g the  this  thesis  in partjal  fulfilment of  r e q u i r e m e n t s f o r an advanced d e g r e e a t t h e U n i v e r s i t y o f  British  Columbia,  I agree that  the Library  a v a i l a b l e f o r r e f e r e n c e and s t u d y . mission  f o r extensive  s h a l l make i t f r e e l y  I f u r t h e r agree that  copying o f t h i s  thesis  per-  f o r scholarly"  p u r p o s e s may be g r a n t e d by t h e Head o f my D e p a r t m e n t o r by his  representatives,  cation  of this  thesis  w i t h o u t my w r i t t e n  Department o f  I t i s understood forfinancial  permission.  Chemistry  The U n i v e r s i t y o f B r i t i s h V a n c o u v e r .8, C a n a d a Date  Columbia  September 24, 1965,  that  gain  copying o r p u b l i -  shall  n o t be a l l o w e d  ABSTRACT  T r i p h e n y l - , t r i m e t h y l - and  dimethyltin(IV),  and  trimethylantimony(V) d e r i v a t i v e s of a wide v a r i e t y of a c i d s , i n c l u d i n g those of very  strong  a c i d s , as w e l l as d e r i v a t i v e s  of a t r a n s i t i o n metal oxyanion, were s y n t h e s i z e d .  Their  s t r u c t u r a l c h a r a c t e r i s t i c s i n the s o l i d s t a t e , under  strictly  anhydrous c o n d i t i o n s , were determined from t h e i r i n f r a r e d spectra.  These s p e c t r o s c o p i c  i n terms of a very group and  strong  r e s u l t s can  only be  interpreted  i n t e r a c t i o n between the  organometal  the corresponding a n i o n i c group, and  provide  strong  evidence f o r c o o r d i n a t i o n or p a r t i a l c o v a l e n t  bonding between  the organometal group and  Contrary  the a n i o n i c group.  to  e a r l i e r r e p o r t s , no evidence i s found f o r the e x i s t e n c e free R Sn , R2Sn +  3  2+  or R S b 3  2 +  c a t i o n s i n the soli-d s t a t e .  of  iii TABLE OF CONTENTS PAGE CHAPTER 1  :  INTRODUCTION  CHAPTER 2  :  TRIPHENYLTIN(IV) DERIVATIVES  1  2.1 :  Triphenyltin Nitrate  19  2.2 :  Triphenyltln Perchlorate  34  CHAPTER 3  : •TRIMETHYLTIN(IV) DERIVATIVES  3.1 :  B i s (trimethy lti'n) Sulphate  43  3.2 :  B i s ( t r i m e t h y l t i n ) Chromate  54  CHAPTER 4  :  DIMETHYLTIN(IV) DERIVATIVES  4.1 :  Dimethyltin D i f l u o r i d e  57  4.2 :  D i m e t h y l t i n Carbonate  59  4.3 :  D i m e t h y l t i n Chromate  69  4.4 :  D i m e t h y l t i n Sulphate  74  4.5 :  Dimethyltin Bis(tetrafluoroborate)  94  4.6 :  Dimethyltin H e x a f l u o r o s i l i c a t e  103  4.7 i  D i m e t h y l t i n D e r i v a t i v e s of Group Vb Hexafluorides  104 2-  4.8 : CHAPTER 5  :  The D i m e t h y l t i n D e r i v a t i v e of B  C 1 1 2  12  1  1  4  TRIMETHYLANTIMONY(V) DERIVATIVES  5.1 :  Trimethylantimony D i h a l i d e s  119  5.2 :  Trimethylantimony D i n i t r a t e  120  5.3 :  Trimethylantimony Carbonate  127  5.4 :  Trimethylantimony  Sulphate  131  5.5 :  Trimethylantimony Chromate  137  5.6 : 5.7 :  Trimethylantimony Oxalate Trimethylantimony B i s ( t e t r a f l u o r o b o r a t e )  141 150  iv PAGE CHAPTER 5  (Continued)  5.8  Trimethylantimony H e x a f l u o r o s i l i c a t e  5.9  Trimethylantimony B i s ( h e x a f l u o r o a n t i m o n a t e ) 159  5.10  The Trimethylantimony D e r i v a t i v e 12Cli2 -  B  of  154  161  2  CHAPTER 6  CONCLUSION  165  CHAPTER 7  EXPERIMENTAL  169  BIBLIOGRAPHY  193  V  LIST OF TABLES TABLE  PAGE  2.1a  :  V i b r a t i o n a l Frequencies of N O 3  2.1b  :  C o r r e l a t i o n Table f o r D , P o i n t Groups  2.1c  :  V i b r a t i o n a l Frequencies of Unidentate and B i d e n t a t e N i t r a t o Groups  23  2.Id  :  I n f r a r e d Absorption Spectra of Anhydrous and Wet Triphenyltin Nitrate  28  2.1e  :  I n f r a r e d A b s o r p t i o n Spectra of The Products Obtained on Heating Anhydrous T r i p h e n y l t i n N i t r a t e  32  2.2a  :  V i b r a t i o n a l Frequencies of CIO"  35  2.2b  :  Vibrations Symmetry  2.2c  :  I n f r a r e d A b s o r p t i o n Spectrum of T r i p h e n y l t i n Perchlorate  3.1a  :  3.1b  :  I n f r a r e d A b s o r p t i o n S p e c t r a of B i s ( t r i m e t h y l t i n ) Sulphate-Methanol Diadduct and B i s ( t r i m e t h y l t i n ) Sulphate  • 3.2  :  V i b r a t i o n a l Frequencies of CrO^  4.2a  :  V i b r a t i o n a l Frequencies of C0  4.2b  : . V i b r a t i o n a l Modes of The Carbonato Group of C2 Symmetry  4.2c  :  C a l c u l a t e d Frequencies of Unidentate Co(III) Carbonato Complexes  4.2d  :  Infrared  A b s o r p t i o n Spectrum of D i m e t h y l t i n Carbonate  67  4.3  :  Infrared  A b s o r p t i o n Spectrum of D i m e t h y l t i n Chromate  72  4.4a  :  I n f r a r e d A b s o r p t i o n Spectrum of D i m e t h y l t i n SulphateMethanol Adduct  79  I n f r a r e d A b s o r p t i o n Spectra of P y r i d i n e Adducts of D i m e t h y l t i n Sulphate and D i m e t h y l t i n D i c h l o r i d e  83  3h  of The  C10  4  D,  Ion Cv  3  20 and C  2  22  s  Ion  Group i n T , d  C  3 v  or C  36  2 v  40  2_ V i b r a t i o n a l Frequencies of SO4 Ion  2-  44  Ion  49  55  2-  4.4b::  3  Ion  60 V  and B i d e n t a t e  62 64  vi TABLE  PAGE  4.4c  :  I n f r a r e d A b s o r p t i o n Spectra of DMSO Adducts of D i m e t h y l t i n Sulphate and D i m e t h y l t i n D i c h l o r i d e  89  4.4d  :  Sn-CrU Coupling Constants Derivatives  92  4.4e  :  Sn-CHo Coupling Constants of D i m e t h y l t i n Sulphate, 93 D i m e t h y l t i n S u l p h a t e - P y r i d i n e , D i m e t h y l t i n SulphateDMSO and D i m e t h y l t i n D i c h l o r i d e - 2 DMSO  4.5a  : V i b r a t i o n a l Frequencies of BF4" Ion  4.5b  :  4.7a  :. V i b r a t i o n a l Modes of An O c t a h e d r a l Group MXg  105  4.7b  :  C o r r e l a t i o n between The V i b r a t i o n a l Modes of An O c t a h e d r a l Group of Oh, D , or C Symmetry  106  :. I n f r a r e d A b s o r p t i o n Spectrum of The D i m e t h y l t i n  116  of Some D i m e t h y l t i n ( I V )  I n f r a r e d A b s o r p t i o n Spectrum of The Mixture of D i m e t h y l t i n B i s ( t e t r a f l u o r o b o r a t e ) and D i m e t h y l t i n Difluoride  4 h  4.8  95  Derivative  101  2 v  of B 1 2 C I 1 2  5.1  :  I n f r a r e d A b s o r p t i o n Spectrum of Trimethylantimony Difluoride  121  5.2  :  I n f r a r e d A b s o r p t i o n Spectrum of Trimethylantimony Dinitrate  124  5.3  :  I n f r a r e d A b s o r p t i o n Spectrum of Trimethylantimony Carbonate  129  5.4a  :  I n f r a r e d A b s o r p t i o n Spectrum of Trimethylantimony Sulphate  133  5.4b  :  I n f r a r e d A b s o r p t i o n Spectrum of Dimethyl  Sulphate  135  5.5  :  I n f r a r e d A b s o r p t i o n Spectrum of Trimethylantimony Chromate  139  5.6a  : V i b r a t i o n a l Modes of C2O4  2— Ion  V i b r a t i o n a l Frequencies of C2O4  o  141  5.6b  :  Ion  5.6c  : V i b r a t i o n Modes of The Free Oxalate The Oxalato Group  5.6d  :  Ion and  I n f r a r e d A b s o r p t i o n Spectrum of Trimethylantimony Oxalate  143 145 147  vii TABLE  PAGE  5.7  :  I n f r a r e d A b s o r p t i o n Spectrum of The Mixture of Trimethylantimony B i s ( t e t r a f l u o r o b o r a t e ) and Trimethylantimony D i f l u o r i d e  153  5.8  :  I n f r a r e d A b s o r p t i o n Spectrum of The Mixture of Trimethylantimony H e x a f l u o r o s i l i c a t e and Trimethylantimony D i f l u o r i d e  158  5.10  :  I n f r a r e d A b s o r p t i o n Spectrum of The Trimethylantimony D e r i v a t i v e of B ^ C l - ^  163  viii LIST OF FIGURES FIGURE  PAGE  2.1  :  Infrared Absorption Nitrate  Spectrum of T r i p h e n y l t i n  27  2.2  :  I n f r a r e d Absorption Perchlorate  Spectrum of T r i p h e n y l t i n  39  3.1a  :  I n f r a r e d Absorption Spectra of B i s ( t r i m e t h y l t i n ) Sulphate-Methanol Diadduct and B i s ( t r i m e t h y l t i n ) Sulphate  47  3.1b  :  I n f r a r e d Absorption Spectra of B i s ( t r i m e t h y l t i n ) • Sulphate-Methanol Diadduct and B i s ( t r i m e t h y l t i n ) .Sulphate  48  3.1c  :  Proposed S t r u c t u r e Methanol Diadduct  f o r B i s ( t r i m e t h y l t i n ) Sulphate-  51  3.Id  :  Proposed S t r u c t u r e  f o r B i s ( t r i m e t h y l t i n ) Sulphate  53  4.2  :  4.3  :  Infrared Absorption Carbonate Infrared Absorption  4.4a  :  I n f r a r e d A b s o r p t i o n Spectrum of D i m e t h y l t i n Sulphate-Methanol Adduct  77  4.4b  :  I n f r a r e d A b s o r p t i o n Spectrum of D i m e t h y l t i n Sulphate-Methanol Adduct  78  4.4c  :  I n f r a r e d A b s o r p t i o n Spectrum of D i m e t h y l t i n P y r i d i n e Monoadduct  Sulphate-  82  4.4d  :  I n f r a r e d Absorption DMSO Monoadduct  Sulphate-  88  4.5a  :  I n f r a r e d A b s o r p t i o n Spectrum of The Mixture of D i m e t h y l t i n B i s ( t e t r a f l u o r o b o r a t e ) and D i m e t h y l t i n Difluoride  99  4.5b  :  I n f r a r e d Absorption Spectrum of The Mixture of D i m e t h y l t i n B i s ( t e t r a f l u o r o b o r a t e ) and D i m e t h y l t i n Difluoride  100  Spectrum of D i m e t h y l t i n . Spectrum of D i m e t h y l t i n  Spectrum of D i m e t h y l t i n  66 Chromate  71  ix FIGURE  PAGE  4.7a  :  I n f r a r e d A b s o r p t i o n Spectrum of The Mixture of B i s ( h e x a f l u o r o a r s e n a t e ) and D i m e t h y l t i n D i f l u o r i d e  109  4.7b  :  I n f r a r e d A b s o r p t i o n Spectrum of D i m e t h y l t i n Bis(hexafluoroantimonate)  111  4.8  :  I n f r a r e d A b s o r p t i o n Spectrum of The D i m e t h y l t i n D e r i v a t i v e of ^±2^12  115  5.2  :  I n f r a r e d A b s o r p t i o n Spectrum of Trimethylantimony Dinitrate  123  5.3  :  I n f r a r e d A b s o r p t i o n Spectrum of Trimethylantimony Carbonate  128  5.4  :  I n f r a r e d A b s o r p t i o n Spectrum of Trimethylantimony Sulphate  132  5.5  :  I n f r a r e d A b s o r p t i o n Spectrum of Trimethylantimony Chromate  138  5.6  :  I n f r a r e d A b s o r p t i o n Spectrum of Trimethylantimony Oxalate  146  5.7  :  I n f r a r e d A b s o r p t i o n Spectrum of The Mixture of Trimethylantimony B i s ( t e t r a f l u o r o b o r a t e ) and Trimethylantimony D i f l u o r i d e  152  5.8  :  I n f r a r e d A b s o r p t i o n Spectrum of The Mixture of Trimethylantimony H e x a f l u o r o s i l i c a t e and Trimethylantimony D i f l u o r i d e  157  5.9  :  I n f r a r e d A b s o r p t i o n Spectrum of Trimethylantimony B i s (hexafluoroantimonate)  160  5.10  :  I n f r a r e d A b s o r p t i o n Spectrum of The T r i m e t h y l a n t i mony D e r i v a t i v e of B - j ^ C l - ^ ^ ~  162  X  ACKNOWLEDGMENTS  The  author  i s g r e a t l y indebted t o P r o f e s s o r H. C.  C l a r k f o r h i s t h o u g h t f u l and s t i m u l a t i n g guidance, without which t h i s study would not have been p o s s i b l e . The  author  the Chemistry  i s g r a t e f u l t o many other members of Department who have a s s i s t e d him i n many  ways, i n p a r t i c u l a r t o Dr. K. B. Harvey f o r the use of h i s spectroscopy  l a b o r a t o r y , and t o Dr. J . D. Cotton  f o r many v a l u a b l e d i s c u s s i o n s .  The author  also  wishes t o thank Dr. E. L. M u e t t e r t i e s , of the C e n t r a l Research Co.,  Department of  Wilmington,  E. I. du Pont de Nemours &  Delaware, f o r the g i f t  of a chemical  and f o r p r o v i d i n g analyses o f two compounds. The  award of a 1964/65 Graduate F e l l o w s h i p by  the U n i v e r s i t y of B r i t i s h Columbia i s g r a t e f u l l y acknowledged. Finally,  the author wishes t o thank h i s w i f e f o r  her p a t i e n t understanding study.  during the years of t h i s  1 CHAPTER 1 INTRODUCTION  Tin  (symbol Sn) i s an element o f atomic number 50 and  occurs i n group IVb and the 5th p e r i o d of the p e r i o d i c t a b l e . Organotin  compounds are substances  carbon bond i s present.  The f i r s t  i n which at l e a s t one t i n o r g a n o t i n compound was  d e s c r i b e d i n 1852 by Lbwig, and many s i g n i f i c a n t c o n t r i b u t i o n s were made i n t h i s f i e l d  during the next  r e s e a r c h i n o r g a n o m e t a l l i c chemistry  few decades.  Although  s h i f t e d then to other  areas, i n t e r e s t i n o r g a n o t i n chemistry was r e v i v e d i n about 1940, and  at the present  the s u b j e c t .  time a v a s t amount of l i t e r a t u r e e x i s t s on  Two e x c e l l e n t reviews  (1, 2a) of o r g a n o t i n  chemistry  appeared i n 1960 c o v e r i n g almost a l l the a v a i l a b l e l i t e r a t u r e on the s u b j e c t to that time.* chemistry  Up to 1960, r e s e a r c h i n o r g a n o t i n  was l a r g e l y c o n f i n e d to p r e p a r a t i v e r e a c t i o n s .  However  s i n c e 1960, s i g n i f i c a n t c o n t r i b u t i o n s have been made towards the study of s t e r e o c h e m i s t r y d i s c u s s i o n i s t o review  of o r g a n o t i n compounds. briefly  The aim of t h i s  the s t e r e o c h e m i s t r y  of organotin(IV)  acid derivatives. A n e u t r a l t i n atom has f o u r t e e n e l e c t r o n s o u t s i d e the krypton  core, i t s c o n f i g u r a t i o n being fjCr] (4d) (5s) (5p) . The 3 ground s t a t e f o r the t i n atom i s a P s t a t e , d e r i v e d from the 2 2 s^p configuration.  1  The f i r s t  0  2  2  e x c i t e d s t a t e of the t i n atom i s  ^"After the completion of t h i s t e x t , a b r i e f review on " C o o r d i n a t i o n i n Organotin Chemistry" by R. C. P o l l e r , has appeared i n J . Organometal. Chem., 3,321-329(1965).  a  s t a t e a r i s i n g from a sp^ c o n f i g u r a t i o n .  s t a t e s of t i n , i . e . Sn(II) and s t a t e and  the f i r s t  s t a t e s are known, however, The  t e t r a a r y 1 - t i n s , R4Sn, are t y p i c a l l y c o v a l e n t ,  i n common organic  The  solvents  but  monomeric, t e t r a -  i n more non-polar s o l v e n t s  R Sn compound i s r e p l a c e d  If one  then the r e s u l t i n g compound may  be c o n s i d e r e d  R3SnX, R S n X 2  such  as  other a n i o n i c group, . an  organotin(IV)  etc.  2  h a l i d e s with the exception  of f l u o r i d e s are  e i t h e r low-melting s o l i d s or l i q u i d s at room temperature. s o l u b l e i n organic  solvents  and  the  also soluble i n polar solvents volatile.  In g e n e r a l ,  soluble  (or more) R groups i n an  by a halogen or any  4  organotin  and  the higher molecular weight sub-  benzene, p y r i d i n e or c h l o r o f o r m .  a c i d d e r i v a t i v e e.g.  tetraalkyl-  lower molecular weight compounds are  stances are s o l u b l e only  The  from the ground  e x c i t e d s t a t e of the t i n atom r e s p e c t i v e l y .  the Sn(IV) i s more commonly encountered.  compounds.  known o x i d a t i o n  Sn(IV), are d e r i v e d  Organotin compounds of both o x i d a t i o n  hedral  The  They  lower members i n a s e r i e s  such as water and  a l l the o r g a n o t i n  v o l a t i l e s o l i d s which are s o l u b l e only  a l c o h o l , and  are  are are  f l u o r i d e s are non-  i n water and  u s u a l l y melt  or decompose above 200°. Organotin c h l o r i d e s , bromides a,nd sidered of the  to be c o v a l e n t t i n atom.  (CH ) SnX, 3  3  The  compounds d e r i v e d  2  from the sp^  electron d i f f r a c t i o n studies  ( C H ) S n X , and 3  i o d i d e s are u s u a l l y con-  2  (CH )SnX 3  3  (3)  configuration of  (where X = CI, Br or I) have  shown t h a t , i n the gaseous s t a t e , these compounds have a hedral  configuration.  a r y l t i n halides  Raman and  (CI, Br,  I)  (4-8)  tetra-  i n f r a r e d s t u d i e s of a l k y l have demonstrated that  and  the  t e t r a h e d r a l c o n f i g u r a t i o n of the t i n atom i s s t i l l maintained i n  the l i q u i d and s o l i d s t a t e , as w e l l as i n s o l u t i o n i n i n e r t nonpolar solvents.  In s o l i d t r i m e t h y l t i n c h l o r i d e and bromide  however, halogen b r i d g i n g has been invoked moment s t u d i e s on s e v e r a l o r g a n o t i n  (7).  The d i p o l e  chlorides also indicate a  t e t r a h e d r a l c o n f i g u r a t i o n of the t i n atom i n these compounds ( 1 ) . The e l e c t r o n d i f f r a c t i o n r e s u l t s (3) showed that the Sn-X (X=C1, Br, I) bond length (CH )SnX3 (CH3)2SnX 3  3  2  increases  i n the s e r i e s SnX^,  and (CH ) SnX. 3  A decrease i n the Sn-X bond  3  length with i n c r e a s i n g X s u b s t i t u t i o n may be considered cate an i n c r e a s e the  i n the Sn-X bond order.  to i n d i -  The e l e c t r o n d e n s i t y on  t i n atom may be a n t i c i p a t e d to decrease with an i n c r e a s e i n  the number of e l e c t r o n e g a t i v e  s u b s t i t u e n t s , and t h i s may  result  i n the back donation of the p e l e c t r o n s to the empty 5d t i n orbitals.  From a recent  a distinct  fall 4  (CH )SnCl , 3  3  (CH ) SnCl 3  2  2  e f f e c t of the methyl groups f a c i l i t a t i n g However, L o r b e r t h  through  and ( C H ) S n C l has been 3  3  ( 4 ) . T h i s sequence f o l l o w s the i n c r e a s i n g  Sn-Cl bond.  chlorides,  i n the Sn-Cl s t r e t c h i n g f o r c e constants  the s e r i e s S n C l , reported  i n f r a r e d study of m e t h y l t i n  inductive  the i o n i z a t i o n of the  and Noth (9) have r e c e n t l y  on the b a s i s of d i p o l e moment d e t e r m i n a t i o n s of R4-nSnCl R = CH , 3  C H5, C 4 H 9 , 2  or C0H5)  an i n c r e a s e  Sn-Cl bond with i n c r e a s i n g value  of n.  n  reported (where  i n p o l a r i t y of the  The authors suggest  that  the f a c t that the Sn-Cl bond becomes more p o l a r by i n c r e a s i n g the number of c h l o r i n e atoms i n s p i t e of a decrease i n Sn-Cl bond distance,  apparently  shows that dTT-p"jT"bonding i s only weak and  cannot compensate f o r the e l e c t r o n a b s t r a c t i o n caused by the negative  i n d u c t i v e e f f e c t of the c h l o r i n e atoms.  Thus the net  e f f e c t on the Sn-Cl bond seems to be an i n c r e a s e about 10 percent chloride.  i n p o l a r i t y of  i n going from t r i m e t h y l t i n c h l o r i d e to m e t h y l t i n  However,  the authors recognize  t h a t , c o n s i d e r i n g the  assumptions i n v o l v e d i n the c a l c u l a t i o n s of these r e s u l t s , the v a r i a t i o n i n the p o l a r i t y of the Sn-Cl bond i s not s i g n i f i c a n t and that other  i n t e r p r e t a t i o n s f o r t h i s v a r i a t i o n are p o s s i b l e , e.g.  change i n atomic p o l a r i z a t i o n , and change i n the Sn-R bond moment due to a change i n the Sn-C•distance. There are other  divergent  of dTT -PTT bonding i n o r g a n o t i n of n u c l e a r  quadrupole c o u p l i n g  views as w e l l on the e x i s t e n c e halides.  From the measurements  constants  of ^ C l i n mono- and  d i - n - b u t y l t i n c h l o r i d e s and mono- and d i p h e n y l t i n c h l o r i d e s , i t has been suggested  (10) that the IT bond c h a r a c t e r  of the Sn-Cl  bond i n c r e a s e s with i n c r e a s e i n s u b s t i t u t i o n of the CI atom by an organic  group.  The u l t r a v i o l e t  (11) and i n f r a r e d (8) s p e c t r o -  s c o p i c s t u d i e s of the homologues to i n d i c a t e that the S n - C ( a a r  character.  r  (CgH^) SnCl _ n  4  n  have been  reported  = a r y l ) bond has some double bond  The authors c o n s i d e r  that the negative  inductive  e f f e c t of the c h l o r i n e atom r e s u l t s i n the donation of the TT e l e c t r o n s from the phenyl groups to the empty 5d o r b i t a l s of the tin  atom. The bonding i n o r g a n o t i n  h a l i d e s has a l s o been r e c e n t l y  s t u d i e d by means of proton n.m.r. and Mossbauer s p e c t r a . study of the v a r i a t i o n of the constants  i n methyltin  1 1 7  Sn-CH  3  and  1 1 9  Sn-CH  3  From a  coupling .  c h l o r i d e s , Holmes and Kaesz (12) have  estimated that the s o r b i t a l p a r t i c i p a t i o n by the t i n atom i n the formation  of the Sn-C bond decreases with the i n c r e a s e i n  5 the number of methyl groups. i n the  By  assuming 25 percent  t i n o r b i t a l s i n ( C H ) S n , the s- c h a r a c t e r 3  4  s-character  i n the t i n  o r b i t a l s i n v o l v e d i n bonding with the methyl groups has estimated to be 32 percent i n d i m e t h y l t i n cent i n m e t h y l t i n of o r g a n o t i n  trichloride.  d i c h l o r i d e and  and  compounds, Herber and  hybridized  Stoeckler  carbon atom, a t i n - sp  than <~^5 p e r c e n t .  (13)  2  studies  have concluded between a  hybridized  atom  has  reported  0.65:  0.65:  that i n organotin  h a l i d e s , the r e l a t i v e degrees  measurements on v a r i o u s  organotin  are  halides  I) have c o n c l u s i v e l y shown that these compounds are  true e l e c t r o l y t e s i n the pure s t a t e solved  bromide s u b s t i t u e n t s  (±0.05).  Conductivity (CI, Br,  be  From s i m i l a r M5ssbauer s t u d i e s , Hayes  of i o n i c i t y of the f l u o r i d e , c h l o r i d e and 1.0:  per-  a t i n - halogen atom bond i n the t r i a r y l or t r i a l k y l cannot  greater (14)  3  48  From the Mossbauer s p e c t r a l  that the d i f f e r e n c e i n percentage i o n i c c h a r a c t e r t i n - sp  been  (1, 2a).  not  However, when d i s -  i n water, p y r i d i n e , or acetone, these compounds are  r e l a t i v e l y good conductors; but  i n benzene, e t h y l ether,  nitro-  benzene or nitromethane they are poor conductors (1, 2a). e l e c t r o l y t i c behaviour of a l k y l t i n h a l i d e s i n h y d r o l y t i c or i n Lewis bases i s due  c h l o r i d e and  solvents  to the formation of a d d i t i o n compounds.  Aqueous s o l u t i o n s of o r g a n o t i n to h y d r o l y s i s  The  (1, 2a). The  h a l i d e s are s l i g h t l y a c i d i c  e q u i l i b r i u m between, say,  p y r i d i n e , a l c o h o l , or water has  due  trimethyltin  been r e p r e s e n t e d  as shown below: (CH ) SnCl + C H N  ^  (CH ) Sn.NC5H5 +  ( C H ) S n C l + ROH  >  (CH ) Sn.0HR+ + C l "  (CH ) SnCl + H 0  >  (CH ) Sn.0H  (CH ) SnOH^ + H 0  >  (CH ) SnOH + H 0  3  3  3  3  3  5  5  3  3  3  2  2  3  CI"  3  3  3  3  3  3  3  + 2  + Cl~ 3  +  (2a)  6 Rochow and  Seyferth  have r e p o r t e d  Rochow, S e y f e r t h ,  (CH ) SnCl 2  2  to the  following  Smith  2  2+  2  2  n  (16),  dichloride  equations: 2+  + n H 0  (CH ) Sn(H 0) 3  and  a complete d i s s o c i a t i o n of d i m e t h y l t i n  i n water, a c c o r d i n g  3  (15), and  "  + 2C1  ^  (CH ) S n (HgO)  »  (CH ) Sn(H 0) _ OH  3  2  '  3  2  2  n  -  ,  +  1  + H 0 3  +  These authors have f u r t h e r s t a t e d that i n water, amines, or amides, the s o l v a t e d  dimethyltin  Although there alkyltin  halides  c a t i o n probably remains t e t r a h e d r a l .  i s c l e a r evidence  f o r the  (or other a c i d d e r i v a t i v e s ) i n the presence of  a s u i t a b l e Lewis base or where the s o l v e n t accumulated evidence i n d i c a t e s that the of the  t i n atom i s no  R Sn " " cat i o n s . +  The  J  2  hedral  longer  only  (17,  18)  solvated  (19,20,21).  The  1 1 7  R Sn  recent  configuration R Sn  or  +  3  tetra-  or R 2 S n c a t i o n s i s 2 +  (CH )(C2H5)(CgHg)SnI 3  i n t o the camphor sulphonate,  into iodide.  However, attempts to repeat  i n t e r v e n i n g years have not been s u c c e s s f u l  Sn-CH  3  and  1 1 9  Sn-CH  3  obtained  from the proton n.m.r. s p e c t r a  i n water  (12)  N,N-  +  3  p a r t i a l r e s o l u t i o n of  by r e c o n v e r s i o n  t h i s experiment i n the  tetrahedral  r e t a i n e d i n the s o l v a t e d  from aqueous s o l u t i o n by c o n v e r s i o n followed  i s a l s o a donor,  experimental evidence f o r the  c o n f i g u r a t i o n of the  the r e p o r t e d  i o n i z a t i o n of  coupling  constant  of t r i a l k y l t i n  data,  chlorides  or Lewis bases such as tetramethylene s u l p h o x i d e ,  dimethylacetamide or N,N-dimethylformamide ( 2 2 ) , i n d i c a t e  a t r i g o n a l bipyramidal planar  c o n f i g u r a t i o n around the  t r i a l k y l t i n group.  coordination alkyltin  of the  As w i l l be  t i n atom has  derivatives.  discussed  t i n atom, and later,  five  been shown i n many other  tri-  a  7  S i m i l a r l y , from recent  Raman and proton n.m.r. s t u d i e s of  aqueous s o l u t i o n s of d i m e t h y l t i n  perchlorate  and n i t r a t e , McGrady  and T o b i a s (21) have concluded that aqueous s o l u t i o n s of d i m e t h y l t i n (IV)  compounds c o n t a i n  an aquocation w i t h a l i n e a r  C-Sn-C s k e l e t o n  and that, i n a l l p r o b a b i l i t y , f o u r water molecules  are c o o r d i n a t e d  t o the c a t i o n i n the e q u a t o r i a l plane by h i g h l y  p o l a r bonds. Organotin h a l i d e s form complexes with halogen ions e.g. R SnX 2  + 2X  2  It has been r e p o r t e d  >  2R SnX 2  4  (23) that the s t a b i l i t y of s i x c o o r d i n a t e  anions of t i n f a l l s as the number of e l e c t r o n e g a t i v e halogen sub222s t i t u e n t s decreases, g i v i n g the s e r i e s SnClg > R S n C l 5 / R S n C l y 22  R3SnCl3  .  In a d d i t i o n , o r g a n o t i n  4  c h l o r i d e s , bromides and i o d i d e s  r e a c t with c e r t a i n e l e c t r o n - p a i r donors to form a d d i t i o n compounds.  The m a j o r i t y  (where R = organic p a i r donor)(1).  of the adducts are of the type  R SnX _ .2L n  The range and s t a b i l i t y of the a d d i t i o n com-  and, f o r t e t r a o r g a n o t i n s ,  a c i d behaviour. been r e p o r t e d  n  group, X = CI, Br or I, and L = an e l e c t r o n -  pounds formed appear to decrease as the number of organic increases  4  there  groups  i s no evidence of Lewis  No a d d i t i o n compound of o r g a n o t i n  f l u o r i d e s has  either.  Although a d d i t i o n compounds of o r g a n o t i n been known f o r a long  time, l i t t l e  information  u n t i l very r e c e n t l y on t h e i r s t e r e o c h e m i s t r y  h a l i d e s have was a v a i l a b l e  and s t r u c t u r e .  E a r l i e r workers (24) favoured an i o n i c f o r m u l a t i o n  f o r compounds  such as ( C H 3 ) 3 S n C l . P y i n v o l v i n g a t e t r a h e d r a l c a t i o n i . e . (CH3)3SnPy CT. +  However, the c r y s t a l s t r u c t u r e d e t e r m i n a t i o n of  8 t h i s compound, by B e a t t i e , M c Q u i l l a n , and Hulme (25,26) has shown that  ( C H ^ g S n C L P y i s a molecular  compound of t r i g o n a l  bipyramidal  c o n f i g u r a t i o n i n which the t r i m e t h y l t i n group i s p l a n a r and c h l o r i n e atom and tion.  the p y r i d i n e molecule  L a t e r C l a r k and O'Brien  occupy the a x i a l  (27) found  t h a t such  the  posi-  trimethyltin  d e r i v a t i v e s as p e r c h l o r a t e and n i t r a t e form s t a b l e diammonia adducts which c o n t a i n the f i v e c o o r d i n a t e c a t i o n (CHg)^Sn(NHg)  2  i n the s o l i d s t a t e , as shown by t h e i r i n f r a r e d s t u d i e s .  Clark,  O'Brien,  (24)  and P i c k a r d (28) confirmed  the e a r l i e r r e p o r t s  that t r i m e t h y l t i n b r o m i d e and c h l o r i d e form u n s t a b l e with ammonia or p y r i d i n e which r e a d i l y to g i v e s t a b l e monoadducts.  The  diadducts  l o s e one mole of the base  i n f r a r e d s t u d i e s by  authors show t h a t the diadducts can be formulated (where L = Lewis base, X = halogen). have r e p o r t e d the formation of 1:1  Matwiyoff  these  as (CH3)gSnL2JK  and Drago  (22)  a d d i t i o n compounds between  t r i a l k y l t i n c h l o r i d e s and Lewis bases such  as  tetramethylene  sulphoxide, N,N-dimethylacetamide, or N,N-dimethyIformamide. i n f r a r e d s p e c t r o s c o p i c and  tin-hydrogen  c o u p l i n g constant  (22) of these compounds again i n d i c a t e t r i g o n a l  The  of a f i v e c o o r d i n a t e t i n atom has a l s o been proposed  r a d i c a l c o n t a i n i n g two  i s an u n s a t u r a t e d  n i t r o g e n atoms i n the 1,3  data  bipyramidal  s t r u c t u r e s c o n t a i n i n g p l a n a r t r i m e t h y l t i n groups.  pounds of the type R^SnR, where  The  existence  (29) i n comorganic  position  (e.g.  imidazole). A d d i t i o n compounds of t r i p h e n y l t i n c h l o r i d e and  bromide  w i t h n i t r o g e n bases have been d e s c r i b e d i n the l i t e r a t u r e However, Kupchik and Lanigan  (30) r e c e n t l y r e p o r t e d the  (1).  products  of r e a c t i o n between t r i p h e n y l t i n bromide and amonia to be  9 b i s ( t r i p h e n y l t i n ) oxide and  ammonium bromide.  These workers con-  cluded  that the r e a c t i o n proceeded v i a an i n t e r m e d i a t e  a Sn-N  bond which was  of low  hydrolytic stability.  no other work appears to have been r e p o r t e d  containing  Unfortunately  on the n i t r o g e n  base  adducts of t r i p h e n y l t i n h a l i d e s . D i a l k y l - and  d i p h e n y l t i n d i h a l i d e s (CI, Br,  a d d i t i o n compounds with c h e l a t e p h e n a n t h r o l i n e and chloride,  1:2  2,2  bipyridyl.  chelate  t r i h a l i d e s and  t r i a l k y l t i n h a l i d e s do not  ligands.  coordinated.  in acetonitrile  S i m i l a r adducts are  t i n tetrahalides.  form a d d i t i o n compounds with six  2  (31); t h e r e f o r e an i o n i c f o r m u l a t i o n  (32)  has  f o r such  From a survey of the known  of MX4.2L (where M = IVb  halogen) adducts, B e a t t i e  group element, X =  suggested that s m a l l  ligands  tend to give c i s adducts, w h i l e l i g a n d s which are  sterically  hindered  further  out Sn-X  tend to g i v e t r a n s adducts.  that by c o n s i d e r i n g  B e a t t i e has  the p o s s i b i l i t y of d/f -pTT  pointed  bonding i n the  bond, the c i s adduct i s favoured assuming thatTT bonding from  X to Sn i s more important thanTT bonding i n v o l v i n g L. coordinating  factor favouring spectroscopic  A  strongly  l i g a n d c o u l d a l s o have the e f f e c t of reducing d"IT -  bonding between the halogen and  the t i n atoms,.in which case  a c i s configuration i s lost.  s t u d i e s of  d i c h l o r i d e and m e t h y l t i n (33)  In  compound ( C H 3 ) S n C l 2 . 2 P y i s a weak e l e c t r o l y t e  a d d i t i o n compounds i s most u n l i k e l y . stereochemistry  1,10  These a d d i t i o n compounds are apparently  The  1:1  With p y r i d i n e or i t s hydro-  a d d i t i o n compounds are formed.  a l s o formed w i t h m e t h y l t i n contrast,  l i g a n d s such as  I) form  (CHg)gSnC^.2Py and  The other  pTT one  infrared dimethyltin  t r i c h l o r i d e a d d i t i o n compounds i n d i c a t e  that these compounds are s i x c o o r d i n a t e ,  w i t h t r a n s methyl  10 groups i n the case of c o o r d i n a t e d So f a r t h i s d i s c u s s i o n has stereochemistry and  (CHg^SnClg. been l a r g e l y concerned with  of o r g a n o t i n ( I V ) c h l o r i d e s , bromides and  t h e i r a d d i t i o n compounds.  n o n - v o l a t i l e s o l i d s and  iodides  As s t a t e d e a r l i e r i n c o n t r a s t  these h a l i d e s , the o r g a n o t i n ( I V ) f l u o r i d e s are  the  to  high-melting,  are i n s o l u b l e i n organic  solvents.  On  the  b a s i s of these d i f f e r e n c e s i n p h y s i c a l p r o p e r t i e s , the f l u o r i d e s have been c o n s i d e r e d derivatives,  to be i o n i c compounds.  l i k e n i t r a t e s and  i n t h i s category.  sulphates,  Coates(2a) has  Other o r g a n o t i n  have a l s o been  acid  included  stated,"Compounds i n which  the  RgSn or R2Sn group i s combined with a h i g h l y e l e c t r o n e g a t i v e such as f l u o r i d e , n i t r a t e , sulphate, different physical properties. volatility  group,  or sulphonate, have q u i t e  T h e i r high m e l t i n g  p o i n t s and  low  indicate a s a l t - l i k e constitution."  Rochow, S e y f e r t h ,  and  Smith (16)  of a l a r g e number of d i m e t h y l t i n ( I V )  reported  the  preparation  a c i d d e r i v a t i v e s , and,  from  a comparison of t h e i r s o l u b i l i t i e s with those of corresponding s a l t s of b i v a l e n t t i n and  l e a d , these authors r e p o r t e d ,  "In  2 dimethyltin  d i c h l o r i d e i t i s probable that the 5s  2 and  5p  elec-  trons are i n v o l v e d i n sp h y b r i d o r b i t a l s l e a d i n g to a symmetrical covalent  molecule, but  i n the d i m e t h y l t i n c a t i o n , the methyl  groups probably occupy the 5s e l e c t r o n s are given  up  o r b i t a l s above, and  to the anion.  In water and  the  other  amines or  amides, the s o l v a t e d c a t i o n probably remains t e t r a h e d r a l , but b e l i e v e that i n anhydrous s a l t s the :Sn The  + +  and  should  a l s o resemble  :Pb  (CHg^Sn*"^ i o n resembles ++  and  :T1  +  in structure."  authors f u r t h e r commented that i f the s u p p o s i t i o n  of  we  11 i o n i z a t i o n of the 5p  e l e c t r o n s i s c o r r e c t , the anhydrous  i o n should bei l i n e a r .  Afterwards  (CH ) Sn 3  2  Freeman (34) r e p o r t e d d i - n -  b u t y l t i n a c e t a t e to be an i o n i c compound on the b a s i s of the low c a r b o n y l frequency a systematic  i n the i n f r a r e d a b s o r p t i o n spectrum.  Later,  i n f r a r e d s p e c t r o s c o p i c study was made by Okawara,  Webster, and Rochow (35) who proposed an i o n i c s t r u c t u r e f o r d i and  trimethyltin carboxylates.  The i n f r a r e d s p e c t r a of these  compounds showed only one Sn-C s t r e t c h i n g frequency and  i n each  case  t h i s was i n t e r p r e t e d i n terms of the presence of d i s c r e t e  planar  (CHg^Sri " 1  and l i n e a r  (CHg^Sn * cations. 2  Furthermore, the  s p e c t r a due to the c a r b o x y l a t e group i n each compound were . s i m i l a r to the spectrum of the corresponding  free carboxylate  T h i s f a c t was c o n s i d e r e d as evidence  f o r the e x i s t e n c e of f r e e  c a r b o x y l a t e anions  i n these  anion.  compounds.  However, as was p o i n t e d out by B e a t t i e and G i l s o n (36), the e f f e c t i v e symmetry of an i o n i c and of a b r i d g i n g c a r b o x y l a t e group i s the same, and the i n f r a r e d s p e c t r o s c o p i c r e s u l t s of d i m e t h y l t i n c a r b o x y l a t e s are a l s o c o n s i s t e n t with a c o o r d i n a t e d s t r u c t u r e i n v o l v i n g b r i d g i n g or c h e l a t i n g c a r b o x y l a t e groups and an o c t a h e d r a l c o n f i g u r a t i o n around the t i n atom with a l i n e a r d i m e t h y l t i n group.  Similarly,  the i n f r a r e d spectrum of t r i m e t h y l -  t i n a c e t a t e can be e x p l a i n e d i n terms of p l a n a r  trimethyltin  groups l i n k e d by b r i d g i n g a c e t a t e groups i n which case atom w i l l . h a v e a t r i g o n a l b i p y r a m i d a l c o n f i g u r a t i o n . Janssen,  the t i n Subsequently,  L u i j t e n , and van der Kerk (37) showed by d e t a i l e d  infra-  red s t u d i e s that t r i a l k y l t i n a c y l a t e s e x i s t as l i n e a r polymers ( i n which each t i n atom has a t r i g o n a l b i p y r a m i d a l c o n f i g u r a t i o n ) i n the s o l i d and molten s t a t e s and i n concentrated  solutions i n  12 non-polar s o l v e n t s ,  but  are monomeric t e t r a h e d r a l  compounds i n  dilute solutions.  These c o n c l u s i o n s were confirmed l a t e r  Okawara and  (38).  Ohara  Okawara, Webster, and structure  Rochow (35)  f o r t r i m e t h y l t i n f l u o r i d e on  ance of only one  Sn-C  stretching  spectrum of t h i s compound.  c l e a r l y shown that groups and manner.  a l s o proposed an  the b a s i s  of the  frequency i n the  However, the  mination of t h i s compound by  Clark,  density  O'Brien, and  d i s t r i b u t i o n can  ted i n terms of f i v e c o o r d i n a t e t i n atoms and unsymmetrical S n - F — S n b r i d g e s c o n s i s t e n t of compound.  Trotter of  deter-  (39)  chain-like  only be  interpre-  non-linear .  involving  Sn-O-Sn b r i d g e s has  has  trimethyltin  with a non-ionic  A s i m i l a r polymeric s t r u c t u r e  c o o r d i n a t e t i n atoms and  appear-  c r y s t a l structure  trimethyltin fluoride consists  electron  ionic  infrared  f l u o r i n e atoms arranged a l t e r n a t i v e l y i n a  The  by  type  five  been r e p o r t e d f o r  t r i m e t h y l t i n hydroxide from i n f r a r e d evidence (40,41) as w e l l a preliminary  study  on c r y s t a l s t r u c t u r e  determination  In a s y s t e m a t i c study of t r i m e t h y l t i n d e r i v a t i v e s strong acids  such as t r i m e t h y l t i n n i t r a t e , p e r c h l o r a t e ,  fluoroborate, and  O'Brien  h e x a f l u o r o a r s e n a t e and (27,43) and  evidence f o r the Their  Clark,  e x i s t e n c e of  results indicate  anionic  groups and  i n the  s o l i d state.  (CH )gSn 3  compounds has  (46).  +  Pickard  cation  a polymeric s t r u c t u r e ,  of tetra-  (28)  i n the  Clark  found  solid  (involving  no  state.  bridging  p l a n a r t r i m e t h y l t i n groups) f o r these compounds Similar  r e s u l t s have been r e p o r t e d by  workers f o r t r i m e t h y l t i n p e r c h l o r a t e fluoroborate  (42).  hexafluoroantimonate,  O'Brien, and  as  Most of the  been o b t a i n e d by  (44) , n i t r a t e  (45),  other  and  s t r u c t u r a l evidence f o r these infrared spectroscopic  results  tetra-  13  whereby " c o o r d i n a t i o n " by,  say,  perchlorate  group has  been deduced from the o b s e r v a t i o n  group has  C2v  bidentate  or b r i d g i n g group.  to the t r i m e t h y l t i n that the  perchlorate  (or lower) symmetry i n accord with behaviour as a Such a lowering  of symmetry i n the  s o l i d s t a t e c o u l d be a t t r i b u t e d to c o o r d i n a t i o n .  Alternatively,  c r y s t a l f i e l d e f f e c t s might produce such s p e c t r o s c o p i c e f f e c t s . However, the f o l l o w i n g d i s c u s s i o n shows that the spectroscopic  e f f e c t s are mainly due  to  coordination.  In d i s c u s s i n g the symmetry of the spectrum obtained  reported  l i g a n d from the i n f r a r e d  i n the c r y s t a l l i n e s t a t e , a knowledge of  s i t e group or f a c t o r group a n a l y s i s i s d e s i r a b l e .  the  However, a  survey of the i n f r a r e d s p e c t r a of a v a r i e t y of i o n i c as w e l l coordination  compounds i n which the corresponding i o n i c groups  act as c o o r d i n a t i n g coordination  l i g a n d s shows t h a t , i n g e n e r a l ,  upon the v i b r a t i o n a l modes of the  pronounced than the e f f e c t s due  the e f f e c t s of  l i g a n d s are more  to c r y s t a l f i e l d .  Infrared  s p e c t r a of i o n i c and  coordination  by Nakamoto (47)  the s p e c i f i c examples w i l l be d i s c u s s e d  i n the t e x t .  as  and  compounds have been reviewed later  If the symmetry of the anion i s lowered upon co-  o r d i n a t i o n , the i n f r a r e d i n a c t i v e v i b r a t i o n s of the f r e e i o n become i n f r a r e d a c t i v e and  appear w i t h moderate i n t e n s i t y and  the degenerate v i b r a t i o n s are s p l i t .  Moreover, a l l the  mentals are more or l e s s s h i f t e d according vibration.  The  i n t e n s i t y of the new  magnitude of the s p l i t t i n g ,  and  funda-  to t h e i r modes of  permitted  bands,  the  the frequency s h i f t s are more  pronounced i f the a n i o n i c group i s i n v o l v e d i n c o o r d i n a t i o n . C r y s t a l f i e l d e f f e c t s cause the f o r b i d d e n to appear only weakly and  i n f r a r e d a c t i v e modes  the s p l i t t i n g s of the degenerate modes  14 due  to t h i s e f f e c t are i n g e n e r a l  comparatively  smaller  not very w e l l r e s o l v e d and  are  i n magnitude.  Some suggestions to e x p l a i n the f i v e c o o r d i n a t i o n of t i n atom i n t r i a l k y l t i n d e r i v a t i v e s have been put tly.  Janssen, L u i j t e n , and  in f i v e coordinate  van  der Kerk (48)  forward  recen-  have suggested that  t i n compounds, the p r i n c i p a l i n t e r a c t i o n  i n v o l v e s the donation of d e l e c t r o n s from the f i l l e d 4d of t i n i n t o a p p r o p r i a t e  volved.  Matwiyoff and Drago (22)  orbitals  (p  •+ d 2)  orbitals  l i g a n d o r b i t a l s , although some donation  of l i g a n d e l e c t r o n s i n t o vacant 5d t i n o r b i t a l s may  z  the  consider  the use  a l s o be i n of t i n h y b r i d  i n the bonding of the a x i a l groups to  z  planar  R3Sn. As  discussed  earlier,  f o r compounds of the type R SnX , 2  the p o s s i b i l i t y of t i n a c h i e v i n g adduct formation  arises.  a coordination  Six c o o r d i n a t i o n  of s i x through  of the t i n atom i s  a l s o i n d i c a t e d (49,50) i n compounds of the type R2SnL = methyl or phenyl and 8-quinolinolate been r e p o r t e d  L = chelate  etc.).: ]  recently.  l i g a n d such as  2  (where R  acetylacetonate  A l a r g e number of such compounds have However, no systematic  stereochemical  s t u d i e s of R SnX2 compounds i n which X i s an anionic group 2  from an i n o r g a n i c  a c i d (other than CI, Br,  except r e c e n t l y r e p o r t e d and  derived  or I) have been made,  s t u d i e s on d i m e t h y l t i n d i n i t r a t e (51)  d i a l k y l hydroxide n i t r a t e s (45).  deliquescent  2  crystalline solid,  Dimethyltin  dinitrate is a  s o l u b l e i n water and many other  p o l a r s o l v e n t s butvonly s l i g h t l y s o l u b l e i n chloroform.  The  red spectrum of t h i s compound i n the s o l i d s t a t e i n d i c a t e s d i n a t i o n by  the n i t r a t e group and  around the t i n atom.  infr coor-  a tetrahedral configuration  Its u l t r a v i o l e t absorption  spectrum i n  non-  15 aqueous s o l v e n t s  i s a l s o c o n s i s t e n t with the presence of  n i t r a t o groups.  D i a l k y l t i n hydroxide n i t r a t e s are high  c r y s t a l l i n e substances which are s o l u b l e i n water and but  i n s o l u b l e i n non-polar s o l v e n t s .  The  the melting  methanol,  i n f r a r e d spectra  of  these compounds a l s o i n d i c a t e a t e t r a h e d r a l s t r u c t u r e . The  preceding  d i s c u s s i o n thus shows that i n t r i a l k y l t i n  compounds the t i n atom tends to i n c r e a s e four to f i v e and trialkyltin  that there  e x i s t s on analogous t r i a r y l t i n compounds.  d i a l k y l - and  from  i s no evidence f o r the e x i s t e n c e  c a t i o n s i n the s o l i d s t a t e .  indicates coordination  i t s coordination  However, no  of  information  E x i s t i n g evidence a l s o  of e i t h e r four or s i x f o r the t i n atom i n  d i a r y l t i n compounds, though very  little  i s known  about the nature of I^SnXg compounds i n which X i s a s t r o n g l y electronegative questions 1)  anion.  In view of these c o n c l u s i o n s ,  several  can be r a i s e d : Are  the o r g a n o t i n  c a t i o n s such as RgSn"" and 1  2+ RgSn  unstable,  and  i f so what i s the  of i n t e r a c t i o n between the o r g a n o t i n  nature  group  and  the a n i o n i c group? 2)  Is there any  s i m i l a r i t y between analogous  a l k y l t i n and  a r y l t i n derivatives, since  analogy w i t h the triphenylcarbonium t r i p h e n y l t i n c a t i o n may stability  cation,  w e l l possess  than t r i a l k y l t i n  by the  greater  cations?  In an attempt to answer these questions  a wide v a r i e t y of  t r i m e t h y l - , t r i p h e n y l - , and  d i m e t h y l t i n d e r i v a t i v e s of a c i d s i n -  c l u d i n g d e r i v a t i v e s of very  strong  a c i d s and  t r a n s i t i o n metal  16 oxyanions were s y n t h e s i z e d and examined by i n f r a r e d i n the s o l i d s t a t e .  While  t h i s work was  spectrosopy  i n progress, a report  (52) d e s c r i b i n g an i o n i c c o n s t i t u t i o n f o r trimethylantimony d i 2+ n i t r a t e appeared. electronic. earlier),  The c a t i o n s (Crl3)gSn and +  In view of the accumulated  (CHg^Sb  are i s o -  evidence ( d i s c u s s e d  as w e l l as evidence based on the f i n d i n g s of t h i s i n -  v e s t i g a t i o n f o r the non-existence of t r i m e t h y l t i n c a t i o n i n the s o l i d s t a t e , the r e p o r t e d i o n i c s t r u c t u r e of trimethylantimony d i n i t r a t e can only be c o n s i d e r e d anomalous.  Therefore a  system-  a t i c i n f r a r e d study of trimethylantimony(V) a c i d d e r i v a t i v e s  was  a l s o made. Antimony and  (symbol  Sb, atomic number 51) occurs i n group Vb  the 5th p e r i o d of the p e r i o d i c t a b l e .  The e l e c t r o n i c  u r a t i o n of a n e u t r a l antimony atom i s [kr] 4d-*- - 5s2p3 (  R2SbX2  >  >  (where R = a l k y l or a r y l group,  X= halogen or any other a n i o n i c  group) are d e r i v e d from the Sb(V) atom.  In a d d i t i o n to d i h a l i d e s ,  o x i d a t i o n s t a t e of the antimony the d e r i v a t i v e s c o n t a i n i n g  (NOg)2> (CNS)g,SO4 e t c . r • .. have been d e s c r i b e d i n the (2b, 53).  However, very l i t t l e  config-  i s known about  literature  the nature of these  compounds except the e s t a b l i s h e d s t e r e o c h e m i s t r y of d i h a l i d e s (CI, Br,I).  From X-ray c r y s t a l l o g r a p h y , W e l l s  trimethylantimony d i c h l o r i d e , dibromide  (54) demonstrated  and d i i o d i d e are  that  isomor-  phous and have a t r i g o n a l b i p y r a m i d a l s t r u c t u r e i n which three methyl groups are arranged i n the plane of the metal atom and two halogen atoms l i e at the a p i c e s .  The Sb-X  bond l e n g t h s are  g r e a t e r than t h e i r a p p r o p r i a t e c o v a l e n t r a d i i sums. l e d Wells to suggest  the  This fact  that these compounds c o u l d be i n t e r m e d i a t e  between the molecular and i o n i c forms shown as f o l l o w s .  X CH.  X"  ;Sb  2+ Sb-  CH,  CH,  C  x-  X  Jensen (55)  CH  CH.  CH.  assigned  a t r i g o n a l bipyramidal  s t r u c t u r e to t r i -  phenylantimony d i c h l o r i d e on the b a s i s of a d i p o l e moment determination.  T h i s has  s t r u c t u r e determination  been confirmed r e c e n t l y by an X-ray (56).  "Apart from d i h a l i d e s , no  mation e x i s t s on the s t e r e o c h e m i s t r y except a recent and  of other  r e p o r t on d i n i t r a t e and  Freedman (52).  infor-  I_3SbX2 compounds,  sulphate  studies,  these  authors concluded that trimethylantimony d i n i t r a t e i s an  ionic  s o l i d and  From i n f r a r e d s p e c t r o s c o p i c  by Long, Doak,  that t r i a l k y l a n t i m o n y sulphates  are c o v a l e n t  compounds.  Some s o l u t i o n s t u d i e s on d i h a l i d e s have a l s o been made. However, there are d i v e r g e n t solution.  Conductivity  triphertylantimony  views on the s p e c i e s present  measurements of both t r i m e t h y l -  d i c h l o r i d e s and  in and  dibromides i n a c e t o n i t r i l e  s o l u t i o n have shown that these compounds are e f f e c t i v e l y e l e c t r o l y t e s i n t h i s s o l v e n t but drift has  due  to the formation  the d i i o d i d e s show a conductance  of t r i i o d i d e i o n  (57,58).  Coates  s t a t e d that the d i h a l i d e s are c o v a l e n t l y c o n s t i t u t e d ,  when d i s s o l v e d i n water and  non-  other  polar solvents  (2b)  but  they appear to  i o n i z e as shown below: R SbX 3  Sidgwick (59a)  has  to g i v e the c a t i o n s  >  2  R SbX 3  +  +  X"  s t a t e d that RgSbX2 compounds appear to i o n i z e (R3Sb)2 " or more probably R3SbX . :l  ;  +  Trimethyl-  18 antimony d i h a l i d e s form h i g h l y conducting  s o l u t i o n s i n water.  Lowry and Simons (60) have a t t r i b u t e d the high conductance values i n water due  to the presence  of i o n i c hydroxy h a l i d e s .  From a  d e t a i l e d study of h y d r o l y s i s of t r i a l k y l a n t i m o n y dibromides, Nylen to the  (61) concluded  that these compounds are h y d r o l y s e d  according  equations: R SbBr 3  2  + 2H 0 2  RrjSbBrOH RgSbOH* + H 0 2  >  RgSbBrOH + H3O + B r "  »  R3SbOH  >  R SbO + 3  +  + Br" H^O  However, as p o i n t e d out by Long, Doak, and Freedman (52), a l l the h y d r o l y s i s equations must be r e v e r s i b l e , s i n c e t r i a l k y l a n t i m o n y d i h a l i d e s can be recovered q u a n t i t a t i v e l y by r e c r y s t a l l i z a t i o n water.  These authors have a l s o r e p o r t e d that  d i h a l i d e s can be converted  from  trimethylantimony  to d i h y d r o x i d e by p a s s i n g an aqueous  s o l u t i o n of the d i h a l i d e through  a column c o n t a i n i n g an a n i o n i c  exchange r e s i n . As mentioned e a r l i e r , the present i n v e s t i g a t i o n i s l a r g e l y c o n f i n e d to i n f r a r e d s t u d i e s i n the s o l i d s t a t e and lowing c h a p t e r s , these r e s u l t s are d i s c u s s e d .  i n the  fol-  19 CHAPTER 2 TRIPHENYLTIN(IV) DERIVATIVES  In c o n t r a s t to t r i m e t h y l t i n d e r i v a t i v e s of the type (CHg)gSnX (where X = a h i g h l y e l e c t r o n e g a t i v e  group such as  C I O 4 , NO3,  study of s i m i l a r  BF^, AsFg, or SbFg), no systematic  t r i p h e n y l t i n d e r i v a t i v e s has been made. gation  In the present i n v e s t i -  t h e r e f o r e , two such t r i p h e n y l t i n d e r i v a t i v e s , t r i p h e n y l t i n  n i t r a t e and p e r c h l o r a t e were s y n t h e s i z e d .  A comparative study of  t h e i r i n f r a r e d s p e c t r a w i t h those of analogous t r i m e t h y l t i n d e r i v a t i v e s was made i n an attempt to e l u c i d a t e t h e i r  stereo-  chemistry and to determine the e f f e c t of phenyl groups on the i n t e r a c t i o n between R Sn and X. 3  a brief report  While t h i s work was  i n progress  (62) appeared d e s c r i b i n g the p r e p a r a t i o n  and  and apparent i n s t a b i l i t y of t r i p h e n y l t i n n i t r a t e . 2.1  Triphenyltin Nitrate  (CgH^SnNOg  The i n f r a r e d s p e c t r a of n i t r a t e s and n i t r a t o complexes  have  been w i d e l y s t u d i e d and the s u b j e c t has r e c e n t l y been reviewed (63,64).  Recent r e s e a r c h  has i n d i c a t e d that compounds of elements  (M) and the n i t r a t e group can be d i v i d e d i n t o two c l a s s e s to whether the term  M-NO3  bond i s predominantly i o n i c  according  or c o v a l e n t .  The  ' n i t r a t e ' i s u s u a l l y a p p l i e d to a compound i n which the  M-NOg bond i s i o n i c , i o n , and the term  that i s , a compound c o n t a i n i n g  the n i t r a t e  'nitrato-compound' i s g e n e r a l l y used f o r com-  pounds i n which the NO3  group i s c o v a l e n t l y bonded through one  or more of i t s oxygen atoms. A f r e e n i t r a t e i o n belongs to the p o i n t group Dg^ and has f o u r fundamental modes of v i b r a t i o n .  Two  of these are each doubly  20 degenerate and the other two are nondegenerate. v i b r a t i o n a l f r e q u e n c i e s of the NO3" (65a)  i o n are w e l l  The fundamental established  and are l i s t e d i n Table 2.1a. TABLE 2.1a  Vibrational Vibrational mode  Frequencies of NO3  V 2>  Out-of-plane bend  v  Degenerate N 0 stretch  A  3  (E)  Degenerate N 0 bend  v (^) 4  (R = Raman a c t i v e ;  The  1050  (R)  831  (I.R)  2  1390  (R,I.R)  2  720  (R,I.R)  I.R = I n f r a r e d  a l k a l i metal n i t r a t e s ,  active)  and c e r t a i n  e a r t h metal n i t r a t e s , g i v e i n f r a r e d the  )  1  NO symmetric stretch  1  3tl  Activity  Frequency (cm- )  Assignment  v (A' ) 1  Ion (Poinl; Group D  -  of the a l k a l i n e  s p e c t r a which resemble  p r e d i c t e d spectrum of a f r e e n i t r a t e i o n (66-68).  other hand, many anhydrous metal n i t r a t e s , e s p e c i a l l y  closely  On the the t r a n s i -  t i o n metal n i t r a t e s , are l a r g e l y c o v a l e n t i n c h a r a c t e r and t h e i r i n f r a r e d s p e c t r a resemble those of non-metal n i t r a t e s organic n i t r a t e s covalent.  (64). In  such as methyl n i t r a t e the bonding i s e s s e n t i a l l y  In m e t a l - n i t r a t o compounds the bond c h a r a c t e r i s ex-  pected t o vary from l a r g e l y  i o n i c t o near c o v a l e n t .  Addison and  Logan (64) have p o i n t e d out that m e t a l - n i t r a t o compounds and their derivatives  are much l e s s r e a c t i v e  as compared t o the non-  metal n i t r a t e s such as a l k y l n i t r a t e s and f l u o r i n e n i t r a t e which are  highly  reactive.  These authors c o n s i d e r that  some form of  .21  back-donation of e l e c t r o n s from the metal atom to the empty o r b i t a l s of the n i t r a t e group may make a c o n t r i b u t i o n to the g r e a t e r stability  of m e t a l - n i t r a t o compounds.  Covalent or p a r t i a l c o v a l e n t bonding between the metal atom and n i t r a t e group can i n v o l v e one or two of the oxygen atoms of  the n i t r a t e group thereby r e d u c i n g the symmetry of the n i t r a t e  group to e i t h e r C  s  or C 2  V  as shown below:  .0  M— o — N:  c  (a)  2v  s  y  m m e t r  G  M  C„ symmetry  y  Unidentate n i t r a t o  0  group  M  ^N—0  0 —N4  .0  I C (b)  2 v  symmetry  C2y  M  symmetry  B i d e n t a t e or b r i d g i n g n i t r a t o group  Upon lowering the symmetry of the NO3 group from D3J- to e i t h e r C  2 v  o  r  Cs>  tbe degeneracy of degenerate modes of the f r e e NO3 i o n  i s completely removed and, as such, the n i t r a t o group p o s s e s s i n g either C  or C  2 v  s  symmetry w i l l  g i v e r i s e to s i x nondegenerate  fundamental v i b r a t i o n s , a l l of which are both Raman and i n f r a r e d active. C  2 v  The c o r r e l a t i o n between the v i b r a t i o n a l modes of D 3 ,  and C  n  s  p o i n t groups i s shown i n T a b l e 2 . 1 b .  I t may  be noted  t h a t , i n a u n i d e n t a t e n i t r a t o group, two of the three N-0 will  have double bond c h a r a c t e r w h i l e the remaining N-0  w i l l have s i n g l e bond c h a r a c t e r .  bonds  bond  On the other hand, i n a b i d e n t a t e  22 TABLE C o r r e l a t i o n Table  f o r 0 3 ^ , D 3 , C \, 2  Cs P o i n t Groups ^3  2  v  4  'l( )  A" (I.R)  E'(R,I.R)  E(R,I.R)  D3  A (R)  A (I.R)  E(R,I.R)  E(R,I.R)  C  A (R,I.R)  B^R.LR)  A^(R, I .R)  Aj^R^.R)  D  3h  and  V i b r a t i o n a l Modes v  ^1  Point Group  2.1b  C  A  R  2  X  2 v  2  1  A(R,I.R)  s  A(R,I.R)  +B2(R, L R )  + B (R,I.R)  A(R,I.R) +  A(R,I.R) +  A'(R,I.R)  A^(R,I.R)  2  or b r i d g i n g n i t r a t o group, as the bond order of the two  M-0  bonds  approaches u n i t y , the t e r m i n a l NO  bond approaches a double bond.  Due  to be expected i n the  to the c o n s i d e r a b l e g r a d a t i o n  of the metal n i t r a t e bond and  polarity  t h e r e f o r e a corresponding  gradation  of the n i t r a t e i o n , the a c t u a l f r e q u e n c i e s f o r the n i t r a t o group cannot be p r e d i c t e d as f o r the f r e e i o n . f r e q u e n c i e s found e x p e r i m e n t a l l y  The  infrared  f o r unidentate  and  absorption  bidentate  (or b r i d g i n g ) n i t r a t o groups, by v a r i o u s workers (69,70), shown i n Table The convention bered  are  2.1c.  v i b r a t i o n a l modes have been numbered a c c o r d i n g  to the  t h a t w i t h i n : a p o i n t group, v i b r a t i o n a l modes are num-  from the h i g h e s t  symmetry s p e c i e s , and,  symmetry s p e c i e s , from the h i g h e s t Though many b i d e n t a t e  w i t h i n any  frequency.  (or b r i d g i n g )  nitrato-compounds  (63,64,70,72) show the h i g h e s t n i t r a t e frequency even h i g h e r ,  at 1630  i t must be noted that a b s o r p t i o n frequency  r e g i o n cannot be c o n s i d e r e d  given  a c r i t e r i o n for a bidentate  cm"  1  or  in this •  1  23 TABLE 2.Ic Vibrational  Frequencies of Unidentate and B i d e n t a t e N i t r a t o Groups (C2v Symmetry)  Assignment  Species  NO2 symmetric  Frequency Unidentate  (cm" ) Bidentate or b r i d g i 1  (Al)  ^1(1290-1253)  V2  ( 985)  (Ai)  V (1030-970)  vi  (1630)  NO2 symmetric bend  (Ai)  ^ ( ^  v  3  ( 785)  NO2 asymmetric  (B >  v (1550-1480)  v  4  (1250)  NO2 asymmetric bend  (B )  ^5(^713)  ^5  ( 750)  Out-of-plane  (Bi)  v (800-781)  v  ( 700)  NO  stretch  stretch  Note:  stretch  2  4  2  2  rock  739)  6  6  These authors c l a s s i f i e d modes V 4 and V 5 as belonging t o  B i s p e c i e s and $Q t o B 2 .  T h i s c l a s s i f i c a t i o n has been r e v e r s e d  i n c o n f o r m i t y with the c o r r e l a t i o n t a b l e s i n Wilson, Decius, and Cross (71).  or b r i d g i n g n i t r a t o group.  Cotton, Goodgame, and Soderberg  (73)  have shown that the h i g h e s t n i t r a t e frequency i n the i n f r a r e d spectrum  of Co [(CH ) 3P0] 3  2  (NO3) , where the presence of b i d e n t a t e 2  n i t r a t e groups has been e s t a b l i s h e d by X-ray c r y s t a l l o g r a p h y (74),  occurs at 1517 cm-1.  S i m i l a r l y u r a n y l n i t r a t o compounds  c o n t a i n i n g b i d e n t a t e n i t r a t o groups show the h i g h e s t n i t r a t e frequency i n the r e g i o n 1560 - 1454 c m reported  -1  (63). SnF2(N03)2 i s  (75) to be t e t r a h e d r a l but the i n f r a r e d a b s o r p t i o n  f r e q u e n c i e s of the n i t r a t o group i n t h i s compound are very similar  t o those of Sn(N03)  4  which i s r e p o r t e d (70) t o c o n t a i n  24 b i d e n t a t e n i t r a t o groups. frequency  of a unidentate  as high as 1550  cm''", and -  r e g i o n s f o r unidentate it  i s not,  dentate,  n i t r a t o group can appear at  and b i d e n t a t e  (or b r i d g i n g ) n i t r a t o groups,  i n g e n e r a l , p o s s i b l e to d i s t i n g u i s h between a u n i '  symmetry of the n i t r a t e i o n i n the s o l i d s t a t e can  B u i j s and  the cohesive  Schutte  (66)  to the f i e l d of a c r y s t a l  consider  that, i n i o n i c  Though i n s o l i d s t a t e i n f r a r e d s p e c t r a ,  degenerate i n f r a r e d a c t i v e modes are u s u a l l y s p l i t , a c t i v e modes appear weakly due  any  crystals,  energy i s of the same order as the bond energies  c o v a l e n t compounds.  survey  frequencies  other n i t r a t e bands appear i n s i m i l a r  lowered i f i t i s s u b j e c t e d  lattice.  stretching  2  b i d e n t a t e or b r i d g i n g n i t r a t o group.  The a l s o be  Since the asymmetric N0  the  and Raman  to the c r y s t a l f i e l d e f f e c t s , a  of the s p e c t r a of i o n i c n i t r a t e s  i n t e r a c t i o n with  of  (66-68,76) suggests that  the metal i o n i s i n s u f f i c i e n t  the normal v i b r a t i o n s of the n i t r a t e i o n s .  to r e s t r i c t  By comparing  the  s p e c t r a of i o n i c n i t r a t e s , m e t a l - n i t r a t o compounds and  covalent  n i t r a t e s , some e s t i m a t i o n may  covalent  be made of the degree of  c h a r a c t e r i n the m e t a l - n i t r a t e bond. stressed i n this (a)  The  f o l l o w i n g p o i n t s can  connection:  In i o n i c n i t r a t e s the NO  a very weak a b s o r p t i o n  stretching vibration  i n the 1050  cm~l  shows only  r e g i o n , even i n  cases  where the s i t e symmetry of the n i t r a t e i o n i s lowered to C , s  i n potassium n i t r a t e  (66,76).  In n i t r a t o compounds, the  s t r e t c h i n g v i b r a t i o n appears as a s t r o n g band and the observed frequency observed  (854  be  cm ) -1  (1050  cm ) -1  NO  v a r i e s between  f o r an i o n i c n i t r a t e to that  f o r methyl n i t r a t e  L i v i n g s t o n , and Nyholm (69)  as  (77).  Gatehouse,  have used t h i s c r i t e r i o n to p l a c e a  25 number of m e t a l - n i t r a t o complexes i n the order of the c o v a l e n t c h a r a c t e r of the m e t a l - n i t r a t e bond. (b)  The o u t - o f - p l a n e r o c k i n g mode i n n i t r a t o compounds occurs  almost i n v a r i a b l y at lower frequency than that f o r the f r e e n i t r a t e i o n (64). The degenerage mode V3 of the f r e e n i t r a t e i o n i s s p l i t  (c)  v^ and v*4 i n the n i t r a t o group &  v* = (v^-v^)  into  and the value of the d i f f e r e n c e  ( i n case of b i d e n t a t e n i t r a t o groups &v = v^-v^) ,  i n c r e a s e s p r o g r e s s i v e l y with an i n c r e a s e i n the c o v a l e n t c h a r a c t e r of bonding  of the n i t r a t e group.  The v a l u e s of Av  1  g i v e the same sequence f o r covalency as does the v a r i a t i o n i n the NO s t r e t c h i n g  frequency  (64).  that the extent of t h i s s p l i t t i n g  F e r r a r o (67) has suggested v^-v-^ i s a c r i t e r i o n  of the  s t r e n g t h of the c o v a l e n t bond.  In methyl n i t r a t e V4 and \)i  are  respectively  found a t 1672 and 1287 c m  i s 385 cm~l. (^4-^1)  i s  - 1  In m e t a l - n i t r a t o complexes, the v a l u e of  , i n g e n e r a l , l e s s than 385 c m  other hand, the observed s p l i t t i n g  of V3 i s observed  - 1  (63) but, on the  of ^3 due to c r y s t a l  e f f e c t s are c o m p a r a t i v e l y much s m a l l e r . no s p l i t t i n g  (77) and ( ^ 4 - ^ 1 )  In potassium  field  nitrate  (£6,76). The i n f r a r e d s p e c t r a of  metal n i t r a t e s have a l s o been s t u d i e d i n o r g a n i c s o l v e n t s (78,79). group  In g e n e r a l , the 0^ and v^ f r e q u e n c i e s of the n i t r a t o  are independent  the metal i o n .  of the s o l v e n t , but s t r o n g l y dependent on  From a d e t a i l e d study of the i n f r a r e d  of many metal n i t r a t e s d i s s o l v e d i n t r i b u t y l Katzin 100 c m  phosphate,  (78) concluded that a (v^-v-^) s p l i t t i n g - 1  can be a t t r i b u t e d t o e l e c t r i c a l  to c o v a l e n t bonding, but a ( ^ 4 - ^ 1 )  spectra  of l e s s than  asymmetry r a t h e r  splitting  than  g r e a t e r than 125 cm"  26 i s undoubtedly due  to the e f f e c t s of p a r t i a l c o v a l e n t bonding.  Triphenyltin reaction  n i t r a t e was  prepared  of t r i p h e n y l t i n c h l o r i d e  and  by the m e t a t h e t i c a l  s i l v e r n i t r a t e under  anhydrous c o n d i t i o n s , as w e l l as by using an aqueous  solution  of s i l v e r n i t r a t e as d e s c r i b e d by Shapiro and Becker  (62).  The  infrared  a b s o r p t i o n bands of t r i p h e n y l t i n n i t r a t e are .  l i s t e d , with  t h e i r r e l a t i v e i n t e n s i t i e s and assignments, f o r  both p r e p a r a t i o n s of the compound i n Table 2.Id.  A p o r t i o n of  the spectrum of anhydrous n i t r a t e i s shown i n F i g u r e 2.1. can be seen from Table 2.Id, show any  bands due  attributed  As  the anhydrous n i t r a t e does not  to the f r e e n i t r a t e i o n w h i l e  the bands  to the n i t r a t o group are present at 1515-1492,  1288-1257, 978  and  798  cm .  The  -1  other two  n i t r a t o group cannot be observed  due  s t r o n g phenyl  and 692  a b s o r p t i o n s at 729  bands due  to the presence of cm .  The  -1  a b s o r p t i o n i n t r i p h e n y l t i n n i t r a t e i s very s i m i l a r by t r i m e t h y l t i n  nitrate  (28, 45).  to the  As regards  two  nitrate to that shown  the a b s o r p t i o n s of  the t r i p h e n y l t i n group, there are no apparent d i f f e r e n c e s tween the s p e c t r a of t r i p h e n y l t i n c h l o r i d e azide  (80), t r i p h e n y l t i n n i t r a t e , and  (to be d i s c u s s e d l a t e r ) . (5,8)  to be n o n - a s s o c i a t e d  be non-planar,  Triphenyltin  (5,8),  be-  triphenyltin  triphenyltin perchlorate chloride  i s reported  so that the t r i p h e n y l t i n groups should  while t r i p h e n y l t i n azide i s considered  (81)  to  c o n t a i n p l a n a r t r i p h e n y l t i n groups b r i d g e d by a z i d e groups. Moreover, there i s a c o n s i d e r a b l e disagreement concerning f r e q u e n c i e s at which a b s o r p t i o n due metric stretching observed.  vibrations  to the symmetric and  of the phenyl-iin  G r i f f i t h s and Derwish  the asym-  bonds should  be  (8) have assigned a weak band  27  28 TABLE 2.Id Infrared  A b s o r p t i o n Spectra of Anhydrous and Wet Triphenyltin  Anhydrous Frequency Relative (cm- ) intensity 1  3060  m  2990  Nitrate  Wet Frequency Relative (cm ) intensity -1  3060  m  w  2990  w  1965  w  1965  w  1880  w  1880  w  1815  w  1820  w  1770  w  1760  w  1750  vw  1515  s  1508  s  1492  s  )  1393  vs  sh  1483  m  1437  s  1434  s  1339  m  1334  m  1325  m  1305  m  1303  m  1278  m  s  1271  s  1257  s  C-H s t r .  Phenyl r i n g ,  NO2 asymi. . s t r . , (V4) or NO s t r , , ( V i )  1483  1288  Assignment  NOQ asyiru . s t r . ,(i)  S k e l e t a l C-C vibrations  (3 C-H  NO2 sym..str., (^l) or N O o asym.str., ($4)  29 Table 2.Id continued 1190  vw  1155  vw  1076  m  /Sc-H 1075  m  1062  w  1044  w .  1024  m  1022  m  996  m  996  m  978  m  /3C-H NO s t r . , (v-^  ftC-H Phenyl  ring  NO s t r . , ( v ) or 2  N0 826  m  sym.str.,(v )  2  2  N0 ~ o u t - o f - p l a n e 3  bend, (v^) ON0 plane  798  m  729  s  729  692  s  695  450  s  450  2  out-ofrock, (^ ) 6  s  C-H v i b .  s  C-H.vib.  s  Sn-Phenyl  m = mediumj s = s t r o n g ; vs = very s t r o n g ; vw = very weak; w = weak.  30 at 1164 cm-'- i n the spectrum of t r i p h e n y l t i n c h l o r i d e  t o the  -  p h e n y l - t i n asymmetric s t r e t c h i n g  mode, but Kriegsmann and  G e i s s l e r ( 5 ) have assigned t h i s mode to the strong band observed at 450 cm"-'-. more p r e c i s e configuration  The l a t t e r i s probably more c o r r e c t , i n f o r m a t i o n , i t i s not p o s s i b l e  but without  to d e s c r i b e the  of the t r i p h e n y l t i n group i n t r i p h e n y l t i n  with any c e r t a i n t y .  As d i s c u s s e d e a r l i e r , no c o n c l u s i o n can be  reached about the u n i d e n t a t e , b i d e n t a t e or b r i d g i n g the  n i t r a t o group from the i n f r a r e d  infrared f r e e NO3  spectrum.  nature of  However, the  spectrum of t r i p h e n y l t i n n i t r a t e c e r t a i n l y shows and ( C 6 H 5 ) 3 S n  +  that  i o n s are not present i n anhydrous  t r i p h e n y l t i n n i t r a t e and t h e r e f o r e an i o n i c s t r u c t u r e possible  nitrate  f o r t h i s compound.  t i n n i t r a t e may have e i t h e r  Like t r i m e t h y l t i n a tetrahedral,  i s not  nitrate,  monomeric  structure  c o n t a i n i n g a unidentate n i t r a t o group, or a polymeric c o n t a i n i n g f i v e c o o r d i n a t e t i n atoms and b r i d g i n g  triphenyl-  structure  n i t r a t o groups.  In c o n t r a s t t o the anhydrous compound, the i n f r a r e d  spec-  trum of t r i p h e n y l t i n n i t r a t e prepared from wet acetone c l e a r l y shows the presence of the f r e e n i t r a t e i o n .  The a b s o r p t i o n s a t  1515-1492 and 1288-1257 cm~l i n the anhydrous compound are r e p l a c e d by a s i n g l e very s t r o n g broad band a t 1393 c m c h a r a c t e r i s t i c of the f r e e n i t r a t e i o n .  - 1  which i s  The other expected  a b s o r p t i o n s a t 1062 and 826 cm-*- are a l s o present; the band -  expected a t approximately 720 c m phenyl a b s o r p t i o n .  - 1  i s probably masked by s t r o n g  The same spectrum i s a l s o observed when  anhydrous t r i p h e n y l t i n n i t r a t e i s exposed to moist a i r , the changes i n the i n f r a r e d spectrum being complete a f t e r an exposure of 24 hours.  Thus there i s a c o n s t i t u t i o n a l  between anhydrous and wet t r i p h e n y l t i n  nitrate.  difference  31 Since samples of anhydrous t r i p h e n y l t i n n i t r a t e stable,  a c o n f i r m a t i o n of the r e p o r t e d i n s t a b i l i t y was  Shapiro and Becker prepared  i n wet  appeared sought.  (62) have r e p o r t e d t h a t t r i p h e n y l t i n  acetone,  decomposes spontaneously  nitrate,  at 25° a c c o r -  ding to the equation  (C H ) SnN0 6  5  3  ^C H N0  3  6  and at h i g h e r temperatures,  (C H )-SnN0 6  5  5  6  5  5  gen.  + CgHp  (33%)  2  (C6H )  All  2  a c c o r d i n g to the equation  9 C H N0  3  (87%) + ( C g H s ) SnO (100%)  2  S n 0 2  +  N 0  apparent  a f t e r s t o r a g e i n the dry box  f o r more than two months.  and one-half hours,  were observed  i n the s o l i d ,  was  The  evolved.  infrared  solid,  two  heated under vacuum  and a very s m a l l amount of vapour s p e c t r a of the heated  s o l i d and  In the spectrum  1277,  s t r o n g bands appear at 606  965 and  and  oxide, d i p h e n y l t i n oxide and b i s ( t r i p h e n y l t i n )  at 572(82),  of  774(83) c m  -1  cm . -1  may  Monophenyltin  oxide show the  s t r o n g a b s o r p t i o n s of the tin-oxygen  575(82) and  790  558 which  be p o s s i b l y a s s o c i a t e d w i t h tin-oxygen v i b r a t i o n s .  characteristic  the  a l l the phenyl absorptions; are unchanged, w h i l e  the n i t r a t e a b s o r p t i o n s occur at 1550, In a d d i t i o n ,  When a  some s p e c t r o s c o p i c changes  e v o l v e d vapour are recorded i n T a b l e 2.1e. the heated  showed no  spectrum, as w e l l as i n appearance,  sample of anhydrous t r i p h e n y l t i n n i t r a t e was at 150° f o r one  the oxide of n i t r o -  the anhydrous n i t r a t e  changes i n i n f r a r e d  +  2  t h e i r products were c h a r a c t e r i z e d except In t h i s i n v e s t i g a t i o n  (65%)  respectively.  vibration None of  TABLE 2.1e I n f r a r e d A b s o r p t i o n Spectra of The Products On Heating Anhydrous T r i p h e n y l t i n Solid Frequency R e l a t i v e (cm~l) intensity  Obtained  Nitrate  Vapour Frequency Relative (cm ) intensity -1  3080  w  3070  m  1550  s  2980  w  1535  s  1685-1665  s  1485  m  1485  w  1335  w  1050  w  1277  s  990  m  1265  sh  850  sh  1075  m  825  s.  1065  sh  800  sh  1022  m  685  m  998  m  670  s  965  s  660  m  920  w  615  im  790  m  572  w  730  s  694  s  655  w  606  s  558  s  450  s  m = medium; s = s t r o n g ; sh = shoulder; w = weak.  33 these a b s o r p t i o n s are found i n the spectrum The i n f r a r e d spectrum of any n i t r o g e n oxides.  of the vapour  of the heated i n d i c a t e s the  solid. absence  Some of the a b s o r p t i o n s can be assigned  to benzene but other bands c o u l d not be c h a r a c t e r i z e d . above s p e c t r o s c o p i c data, i t may  be concluded that  From the  decomposition  of the anhydrous t r i p h e n y l t i n n i t r a t e under these c o n d i t i o n s i s s l i g h t , and t h a t , although some s t r u c t u r a l changes must occur, the n i t r a t e group i s s t i l l or C  s  a p p a r e n t l y r e t a i n e d with e i t h e r  C v 2  symmetry. Even the product o b t a i n e d from wet  acetone i s much more  s t a b l e than the product d e s c r i b e d by Shapiro and Becker.  Samples  were always p a l e y e l l o w i n c o l o u r , and d i d not show any change i n appearance  or s p e c t r a over p e r i o d s of s e v e r a l days.  sample of the compound was  When a  heated w i t h o-dichlorobenzene as  d e s c r i b e d by Shapiro and Becker,  decomposition was  found to be  c o n s i d e r a b l e , the f i n a l r e s i d u e being shown by i t s i n f r a r e d spectrum  to c o n t a i n no n i t r a t e , and a l s o , from the reduced  inten-  s i t i e s of the phenyl a b s o r p t i o n s (as compared with those observed f o r the o r i g i n a l compound i n a m u l l of approximately s i m i l a r c e n t r a t i o n ) , to have l o s t phenyl groups.  con-  No a b s o r p t i o n s charac-  t e r i s t i c of b i s ( t r i p h e n y l t i n ) n o x i d e . w e r e observed.  It i s  concluded, t h e r e f o r e , that pure t r i p h e n y l t i n n i t r a t e i s s t a b l e under anhydrous c o n d i t i o n s , and that the i n s t a b i l i t y observed by Shapiro and Becker  i s a s s o c i a t e d w i t h the presence of c a t a l y t i c  i m p u r i t i e s and, to some degree, with the presence of moisture. . T r i m e t h y l t i n n i t r a t e , by r e a c t i o n with ammonia, r e a d i l y forms a  diadduct which i s formulated (28) as  (CH ) Sn(NH ) N02. +  3  3  3  2  S i m i l a r r e a c t i o n s of t r i p h e n y l t i n n i t r a t e w i t h anhydrous ammonia  34 were c a r r i e d out.  However, no a d d i t i o n compound c o u l d be  iso-  l a t e d ; i n s t e a d a mixture of ammonium n i t r a t e and b i s ( t r i p h e n y l t i n ) oxide was  obtained which was  photograph and  c h a r a c t e r i z e d by i t s X-ray powder  i n f r a r e d spectrum (83).  The  r e a c t i o n of  t r i p h e n y l t i n n i t r a t e with ammonia must t h e r e f o r e proceed as follows: (CgH ) SnN0 5  3  + NH  3  H  2(C H ) SnN0 NH 6  5  3  3  2°  3  >(CgHg)gSnNOgNHg  3  r n ^ K 6 5 3 ^ J 2° C  H  )  Sl  +  2 N H  4  N 0  3  S i m i l a r r e s u l t s have been r e p o r t e d by Kupchik and who  found the products  Lanigan  (30)  of r e a c t i o n between t r i p h e n y l t i n bromide  and ammonia to be b i s ( t r i p h e n y l t i n ) oxide and  ammonium bromide.  I t seems t h a t , i n c o n t r a s t to ammonia adducts of a l k y l t i n compounds, the ammonia adducts of t r i p h e n y l t i n d e r i v a t i v e s have a very hydrolytic s t a b i l i t y , and  f o r e i t h e r k i n e t i c or thermodynamic  that i n the present  low reasons,  case h y d r o l y s i s occurred even under c a r e -  f u l l y controlled conditions.  2.2  Triphenyltin Perchlorate The  symmetry  (CgH ) SnC10 5  3  4  f r e e p e r c h l o r a t e i o n (C10 ~) i s of 4  (65b)  tetrahedral(T )  and hence should have nine v i b r a t i o n a l modes g i v i n g  r i s e to four fundamental v i b r a t i o n a l f r e q u e n c i e s . t a l frequences which have been e s t a b l i s h e d (65a) s p e c t r a of p e r c h l o r a t e s are shown i n Table The and V3 and  d  These fundamenfrom the Raman  2.2a.  v^ mode i s nondegenerate, v^ i s doubly degenerate, are each t r i p l y degenerate.  i n f r a r e d s p e c t r a of i o n i c p e r c h l o r a t e s  In the s o l i d s t a t e  (68,84), v^, which i s i n f r a -  TABLE  2.2a  V i b r a t i o n a l Frequencies  Vibrational mode  of C10  4  Ion  (Point Group  Frequency (cm-1)  Assignment  T ) d  Activity  v,  (A,)  Symmetric s t r e t c h  935  (R)  v"  (E)  Symmetric bend  462  (R)  ^3  < 2>  Asymmetric s t r e t c h  2  h  F  Asymmetric bend  (Fo)  (R = Raman a c t i v e ;  I.R  1102  (R.I.R)  628  (R,I.R)  = Infrared active.)  red i n a c t i v e i s u s u a l l y observed as a very weak a b s o r p t i o n about 930  cm .  Vg appears as a broad, strong band, u s u a l l y  -1  i n the 1050-1150 r e g i o n . other  Anhydrous copper p e r c h l o r a t e and  t r a n s i t i o n metal p e r c h l o r a t e s have i n f r a r e d s p e c t r a  d i f f e r e n t from other metal p e r c h l o r a t e s .  (27)  The  (85)  very  coordinated  i n f r a r e d spectrum of t r i m e t h y l t i n per-  a l s o i n d i c a t e s that p e r c h l o r a t e groups act  b r i d g i n g l i g a n d s between the planar spectroscopic  some  showed t h a t , i n  these compounds, the p e r c h l o r a t e groups are s t r o n g l y to the metal atoms.  split  From a d e t a i l e d study  of t h e i r s p e c t r a , Hathaway and U n d e r h i l l (85)  chlorate  at  r e s u l t s are completely  structure containing f i v e coordinate  t r i m e t h y l t i n groups. c o n s i s t e n t with  a  as The  polymeric  t i n atoms.  If the p e r c h l o r a t e group i s i n v o l v e d i n such c o o r d i n a t i o n , i t s symmetry i s lowered from T one  or two  d  to  or  according  to whether  of i t s oxygen atoms p a r t i c i p a t e i n such bonding.  The  c o r r e l a t i o n between the v i b r a t i o n a l modes of the p e r c h l o r a t e group for T , d  or  C  2 v  symmetry  (85)  i s shown i n Table  2.2b.  If  TABLE 2.2b Vibrations  of The C 1 0 Group 4  in T , d  c  3 v  2  2  Symmetry  2 v  J  A (I.R)  E(I.R)  E (I.R)  Aj(R) sym.str,  ^2 E(R) sym.bend  1  CIO,  cio  C  ^6  v  -C103  or  3 v  V i b r a t i o n a l Modes  Symmetry  -o  C  c  _  2 v  Ai(I.R)  A (I.R)  C10|  G10*  sym.str,  V5  AiU.R)  2  A^LR)  k  F (I.R) asym.str, 2  ^  v  A (R) A (I.R) Torsion C 1 0 sym.bend sym. str. X  E(I.R)  5  X  2  * denotes oxygen atoms i n v o l v e d i n bonding.  2  v  6  g  0  3  v  7  B i d . R . ) B (I.R) A^I.R) B ^ L R ) C10 C10 C10 rocking asym. asym. sym. str. str. bend 2  2  2  2  v  9  B (I.R) rocking 2  the symmetry of the p e r c h l o r a t e group i s lowered to C 3  then the  V s  v*i mode of the p e r c h l o r a t e i o n becomes i n f r a r e d a c t i v e , and modes ^3' ^4 On  split  e a c n  i n t o two modes which are a l s o i n f r a r e d a c t i v e .  f u r t h e r lowering  each s p l i t  of the symmetry to C , 2v  the v^ and v ^ modes 1  i n t o three i n f r a r e d a c t i v e modes.  Ross (84)  c o n s i d e r s t h a t , i n view of the known i n s t a b i l i t y  of c o v a l e n t p e r c h l o r a t e s , i t i s u n l i k e l y that c o v a l e n t can c o n t r i b u t e to any  extent  i n metal p e r c h l o r a t e s , and  bonding that  the  s p l i t t i n g s i n the s o l i d s t a t e i n f r a r e d s p e c t r a of v a r i o u s  per-  c h l o r a t e s d e s c r i b e d by Hathaway and U n d e r h i l l might be due  to  the d i s t o r t i o n of the p e r c h l o r a t e i o n i n the c r y s t a l The  observed  (68,84) i n f r a r e d s p e c t r a of some i o n i c  do show lowering crystal field,  weak a b s o r p t i o n .  2v  but,  to the  however, the observed s p l i t t i n g s of the degen-  of a s m a l l e r order.  C  perchlorates  of the p e r c h l o r a t e i o n symmetry due  e r a t e modes i n a l l these cases  chlorates  lattice.  are not as w e l l d e f i n e d and  A l s o , the f o r b i d d e n mode 0-^ shows only a  For example, i n potassium and  ammonium per-  (84), the p e r c h l o r a t e i o n symmetry i s d i s t o r t e d to i n both these cases,  the v*^ mode shows a s p l i t t i n g  about 50 cm-'- as compared to the s p l i t t i n g of about 200 -  trimethyltin perchlorate  (27).  of  cm~^  observed f o r the same mode i n anhydrous copper p e r c h l o r a t e and  are  (85)  Trimethyltin perchlorate  shows four s t r o n g , w e l l r e s o l v e d bands at . 1212-1192, 1112, and 908  cm  -1  and  three medium bands at 625,  606  and 468  998  cm . -1  C o o r d i n a t i o n by the p e r c h l o r a t e group i n t r i m e t h y l t i n p e r c h l o r a t e i s f u r t h e r supported  by i t s i n f r a r e d spectrum (28)  i n methanol  s o l u t i o n where c r y s t a l f i e l d e f f e c t s are completely While t h i s work was  i n progress,  t i o n by the p e r c h l o r a t e group has  f u r t h e r evidence  of  absent. coordina-  been r e p o r t e d i n the f o l l o w i n g  38 compounds:  Ni(3,5-lutidine)(ClO^)  (86) shows p e r c h l o r a t e group  absorptions  a t 1135, 1030 and 930 cm~"l and the magnetic moment of  t h i s compound i s i n accord with  the s i x c o o r d i n a t i o n -  of the  n i c k e l atom.  and Ni(CHgCN) (C10 )  (87) have  Ni(CH CN) (C10 ) 3  4  perchlorate absorption 1106,  4  2  2  4  bands at 1135, 1012, 912 c m  - 1  and 1195,  1000 and 920 cm"-'- r e s p e c t i v e l y , and the c o o r d i n a t i o n by  p e r c h l o r a t e groups i n these compounds i s f u r t h e r supported by t h e i r electronic spectra.  Thus the proceeding  examples demonstrate that  the s o l i d s t a t e i n f r a r e d spectrum can be used to d i s t i n g u i s h between an i o n i c and a c o o r d i n a t e d  perchlorate  group.  Anhydrous t r i p h e n y l t i n p e r c h l o r a t e was obtained solid.  The observed i n f r a r e d a b s o r p t i o n  compound are l i s t e d , with assignments, i n Table i n F i g u r e 2.2. group occur 439  cm~l.  as a white  bands of the anhydrous  t h e i r r e l a t i v e i n t e n s i t i e s and suggested  2.2c.  A p o r t i o n of the spectrum i s shown  The bands which can be assigned  to the p e r c h l o r a t e  at 1200, 1112, 985, 905, 625, 610-604, 455, 449 and The remaining bands are i d e n t i c a l with  those observed  i n the spectrum of t r i p h e n y l t i n n i t r a t e and can be assigned t o the v i b r a t i o n s a s s o c i a t e d with  the t r i p h e n y l t i n group.  The four  strong p e r c h l o r a t e bands at 1200, 1112, 985 and 905 c m almost i d e n t i c a l w i t h  2 v  symmetry of the p e r c h l o r a t e  T h i s i s a l s o supported by the bands at 625, and 610-604,  which are observed f o r t r i m e t h y l t i n p e r c h l o r a t e . p e r c h l o r a t e shows a b s o r p t i o n t r i p h e n y l t i n perchlorate 450  are  those observed f o r t r i m e t h y l t i n p e r c h l o r a t e  (27), and c l e a r l y i n d i c a t e the C group.  - 1  Trimethyltin  bands a t 468 and 450 c m . -1  there i s a strong a b s o r p t i o n  In  band i n  cm-*- r e g i o n due to the t r i p h e n y l t i n group and t h i s may over-  lap p e r c h l o r a t e a b s o r p t i o n  i n t h i s region.  There i s , however,  40 TABLE 2.2c The I n f r a r e d  A b s o r p t i o n Spectrum of T r i p h e n y l t i n  requency R e l a t i v e (cm-1) Intensity  Assignment  Perchlorate  Frequency R e l a t i v e Intensity (cm ) -1  Assignment /SC-H  1158  m  1112  vs  1075  s  £C-H  1020  m  /SC-H  3070  m  2990  m  2990  w  1990  vw  Phenyl r i n g  1967  w  Phenyl r i n g  995  sh  Phenyl r i n g  1905  vw  Phenyl r i n g  985  vs  CIO2  ) )  C-H s t r .  C I O 2 sym.str.,  asym.  str.,(v* ) g  1884  w  Phenyl r i n g  905  s  CIO2  sym.  s t r . , (v* ) 2  728  vs  C-H deform.  w  690  vs  C-H deform.  1644  w  673  .w  1582  w  S k e l e t a l C-C  664  w  1483  m  vibrations  625  m  1818  .'W  1765  1435  s  1335  m  1300  w  1200  vs  Phenyl r i n g  ) ) ) )  610  ) )  604 /.C-H CIO2  455 asym.  str., (v ) 6  weak;  sym.  bend,(v*g)  )  vs = very s t r o n g ;  CIO2  s = strong;  sh = shoulder.  sh ) ) sh )  449  sh ) ) s  439  sh )  )  Rocking CIO4,  (v ) 7  Rocking CIO4,  (0 )? 9  C1Q ' bend, ( v ) ? and Sn-pheny1. s  v  m  2  1  m = medium; w = weak; vw = very  * denotes the two b r i d g i n g  oxygen  atoms.  41 little  doubt that the p e r c h l o r a t e symmetry i n t h i s compound i s not  higher  than  C2 . V  Triphenyltin perchlorate, i s h i g h l y s o l u b l e i n ether On  l i k e t r i m e t h y l t i n perchlorate,  and methanol and  exposing t r i p h e n y l t i n p e r c h l o r a t e  bands at 1200,  1112,  985  band i n the 1075-1150 c m cm .  and  905  hygroscopic.  to a i r , the four  intense  were r e p l a c e d by an i n t e n s e broad  r e g i o n and  -1  i s very  a very weak band at  940  These are c h a r a c t e r i s t i c bands of the f r e e p e r c h l o r a t e  -1  which i s formed by perchlorate. perchlorate  ion  the h y d r o l y s i s of the anhydrous t r i p h e n y l t i n  I d e n t i c a l s p e c t r a l changes occur (27).  in trimethyltin  Thus i n view of the almost i d e n t i c a l  of t r i p h e n y l t i n p e r c h l o r a t e and  spectra  trimethyltin perchlorate,  t h e i r i d e n t i c a l behaviour upon h y d r o l y s i s , i t can be  and  concluded  that both these compounds are almost s i m i l a r i n s t r u c t u r e . Hathaway and  U n d e r h i l l (85)  have suggested assignments f o r  the fundamental f r e q u e n c i e s  of the p e r c h l o r a t o group of  symmetry by comparison with  the assignments f o r s u l p h u r y l  f l u o r i d e , and  sulphate  the b i d e n t a t e  C2  V  group.  These workers have * suggested the f o l l o w i n g assignments f o r the C I O 2 and ClOg i  s t r e t c h i n g v i b r a t i o n s : 1270 stretch cm"  1  (v" ) ; 948-920 cm , -1  g  cm ,  the r e p o r t e d  dimethyl  sulphate  asymmetric ClOg  -1  symmetric C10* s t r e t c h (v^) ; 2  asymmetric C I O 2 s t r e t c h (ve)5 and  CIO2 s t r e t c h (^1). with  - 1245  *  1030  cm , -1  symmetric  However, these assignments are not  consistent  assignments f o r s u l p h u r y l f l u o r i d e (88) (89).  Moreover, the bond order  1130  of the  and two  C l - 0 bonds ( i n v o l v i n g oxygen atoms not p a r t i c i p a t i n g i n coo r d i n a t i o n ) should  be higher  than t h a t of the remaining  two  Cl-0 bonds (0 denotes oxygen atoms p a r t i c i p a t i n g i n c o o r d i n a t i o n ) .  42 Therefore  the ClOg s t r e t c h i n g v i b r a t i o n should occur  at  higher  f r e q u e n c i e s , compared with f r e q u e n c i e s f o r the ClOg s t r e t c h i n g modes.  In dimethyl  t e r i z i n g the two 1200  cm~^  sulphate  double sulphur-oxygen bonds occur near 1400  whereas the s t r e t c h i n g v i b r a t i o n s of the two  sulphur-oxygen bonds occur Therefore  the s t r e t c h i n g v i b r a t i o n s charac-  at 825  and  1200  cm~\  ^lOg  as  -  r e g i o n are assigned  cm~^  as cm" , 1  CIO2 asymmetric s t r e t c h  (v"g) ; and  905  frequency  r e g i o n , there i s no obvious method to d i s t i n g u i s h  -1  ClO^  perchlorate  y m m e t r i c s t r e t c h (v'g) ; 1112  C I O 2 symmetric s t r e t c h ( v ^ ) ; 985 cm ,  -1  single  cm'*' (see s e c t i o n 5.4) .  i n t r i p h e n y l t i n p e r c h l o r a t e the four s t r o n g  a b s o r p t i o n bands i n the 1200-900 c m follows:  752  and  symmetric s t r e t c h (v^) .  between the v i b r a t i o n a l f r e q u e n c i e s of O3, v*y,  In the  lower  and Og modes and  the assignments suggested by Hathaway and U n d e r h i l l are used. T r i m e t h y l t i n p e r c h l o r a t e forms an a d d i t i o n a l compound with anhydrous ammonia which has (27).  been formulated  as ( C H 3 ) g S n . 2 N H 3 C I O 4  However, the r e a c t i o n of t r i p h e n y l t i n p e r c h l o r a t e w i t h  ammonia r e s u l t e d i n the formation b i s ( t r i p h e n y l t i n ) oxide.  of ammonium p e r c h l o r a t e  and  A s i m i l a r r e a c t i o n between ammonia  t r i p h e n y l t i n n i t r a t e has been d i s c u s s e d and  the formation  ammonium p e r c h l o r a t e and b i s ( t r i p h e n y l t i n ) oxide can be e x p l a i n e d i n a s i m i l a r manner.  and  of  in this reaction  43 CHAPTER 3 TRIMETHYLTIN(IV) DERIVATIVES  To seek f u r t h e r i n f o r m a t i o n a c t i o n between R Sn and 3  about the nature of the  inter-  the a n i o n i c group, some t r i m e t h y l t i n  d e r i v a t i v e s c o n t a i n i n g t r a n s i t i o n metal oxyanions were sought. It was  considered  that the e l e c t r o n i c s p e c t r a of such d e r i v a -  t i v e s might p r o v i d e  some i n f o r m a t i o n  about the e l e c t r o n i c  d e s c r i p t i o n of the i n t e r a c t i o n . Perchlorates,  t e t r a f l u o r o b o r a t e s , and  permanganates of  the same c a t i o n are f r e q u e n t l y isomorphous and  the three  anions  have many s i m i l a r f e a t u r e s i n c l u d i n g t h e i r r e g u l a r t e t r a h e d r a l symmetry.  Therefore  permanganate, but instantaneous vents.  an attempt was  made to prepare t r i m e t h y l t i n  t h i s compound c o u l d not be i s o l a t e d due  decomposition i n the presence of a range of  B i s ( t r i m e t h y l t i n ) chromate,  c o u l d r e a d i l y be s y n t h e s i z e d .  [(CH3) SnJ 3  2  C r 0  to i t s sol-  4 > however,  In t h i s compound, f o r m a l l y at  least,  2a doubly charged anion  C 04 r  i s present  so t h a t the  stoichiometry  i s q u i t e d i f f e r e n t from t h a t . o f a t r i m e t h y l t i n d e r i v a t i v e cont a i n i n g u n i v a l e n t anion provide was  such as p e r c h l o r a t e .  a comparison, b i s ( t r i m e t h y l t i n ) sulphate  also studied.  Both the sulphate  i o n and  have r e g u l a r t e t r a h e d r a l symmetry and T  d  3.1  Therefore,  to  [(CH3)_SnJ_S0^  the chromate i o n  belong to the p o i n t group  (47a). B i s ( t r i m e t h y l t i n ) Sulphate The  widely  i n f r a r e d and  studied  (47a).  2of the f r e e SO4  [TcH )gSnj S0 3  2  4  Raman s p e c t r a of s u l p h a t e s The  have been  fundamental v i b r a t i o n a l f r e q u e n c i e s  i o n as shown i n Table 3.1a,  have been e s t a b l i s h e d  44 from, the Raman s p e c t r a (65b) i n aqueous  solutions.  TABLE 3.1a 2V i b r a t i o n a l Frequencies of SO4 Ion (Point Group T ) d  Vibrational mode  Frequency Assignment  (cm-1)  Activity  (Aj)  Symmetric s t r e t c h  981  (R)  451  (R)  v  2  (E)  Symmetric bend  v  3  (F )  Asymmetric s t r e t c h  V4  (F )  Asymmetric bend  g  2  ( R = Raman a c t i v e ;  In  I.R  1104  (R,I.R)  613  (R,I.R)  = Infrared active.)  the s o l i d s t a t e i n f r a r e d s p e c t r a of i o n i c s u l p h a t e s ,  the i n f r a r e d i n a c t i v e mode v'j shows a weak a b s o r p t i o n and the degenerate  frequencies  and v^ appear very s t r o n g l y a n d o f t e n -  d i s p l a y s p l i t t i n g due to c r y s t a l f i e l d field phates  e f f e c t s observed  effects  (90).  The c r y s t a l  i n the s p e c t r a of c r y s t a l l i n e i o n i c  sul-  are s i m i l a r . i n nature and magnitude t o those d i s c u s s e d i n  connection w i t h p e r c h l o r a t e s (90). From i n f r a r e d s t u d i e s , Nakamato and coworkers (91) have shown c o o r d i n a t i o n by the s u l p h a t e group i n c e r t a i n ammino-cobalt (III)  complexes.  T h e i r c o n c l u s i o n s have been confirmed by  B a r r a c l o u g h and Tobe  (92) i n an i n f r a r e d study of ethylenediamine  c o b a l t ( I I I ) complexes.  C o o r d i n a t i o n by the sulphate grqpp has  a l s o been r e p o r t e d r e c e n t l y i n some ethylenediamine and b i p y r i d y l complexes of copper  (93,94).  The s u l p h a t e a b s o r p t i o n s  i n a l l these s u l p h a t o complexes occur i n the f o l l o w i n g frequency (cm" ) ranges: 1  45  Unidentate sulphato group ^3v  V  ^2 438(m)  symmetry  Bidentate sulphato group C2  ^1 965-978(m)  961-995(m)  462(m)  symmetry (m = medium;  A l k y l t i n sulphates  *3 1114-1143(s)  *4 615-645  1032-1070(s)  602-625(s)  1163-1211(s) 1096-1176(s) 1000-1060(s)  632-647(s) 602-632(s) 515-595(m)  s = strong)  are w e l l known, but no work has been  done t o determine t h e i r c o n s t i t u t i o n , except e a r l i e r s t u d i e s by Werner and P f e i f f e r Robinson (96).  (95) and a b r i e f study by G i l l e s p i e and  Werner and P f e i f f e r obtained  molecular weight of d i e t h y l t i n sulphate  a low value  i n water, which l e d  them to conclude that the compound was p a r t i a l l y i n t o d i e t h y l t i n and sulphate  ions.  f o r the  dissociated  As i t d i d not melt or sub-  lime, Werner and P f e i f f e r c l a s s i f i e d the compound as s a l t - l i k e ; however they a l s o s t a t e d that the compound should a c i s configuration. ported  be planar  with  G i l l e s p i e and Robinson have b r i e f l y r e -  t h a t , i n anhydrous s u l p h u r i c a c i d s o l u t i o n , b i s ( t r i m e t h y l t i n )  sulphate  i s i o n i z e d g i v i n g four p a r t i c l e s f o r every molecule of  can be i n t e r p r e t e d e q u a l l y w e l l i n terms of s o l v a t e d In t h i s i n v e s t i g a t i o n , t r i m e t h y l t i n sulphate under anhydrous c o n d i t i o n s by the m e t a t h e t i c a l t r i m e t h y l t i n bromide and s i l v e r sulphate  ions. was  prepared  r e a c t i o n of  using methanol as  46 solvent.  The  f i r s t product of the p r e p a r a t i o n was  a methanol  from which the methanol  adduct.  was  completely removed by h e a t i n g under vacuum at 100° f o r about f o u r hours. 1) and 3.1a  P a r t of the i n f r a r e d s p e c t r a of the adduct  the nonsolvated product  and 3.1b.  suggested  (curve 2) are shown i n F i g u r e s  I n f r a r e d a b s o r p t i o n bands of both the  are l i s t e d i n Table 3.1b, assignments.  (curve  products  with t h e i r r e l a t i v e i n t e n s i t i e s  For both the methanol adduct  and  and the  nonsdlvated b i s ( t r i m e t h y l t i n ) s u l p h a t e , the t r i m e t h y l t i n group shows a b s o r p t i o n at 3000-2900, (C-H s t r e t c h ) ;  1410-1400,  (C-H asymmetric bend); 1205-1195, (C-H symmetric bend); 785-780. (Sn-CH3 r o c k ) ; and 552,  (Sn-C  asymmetric s t r e t c h ) cm . -1  be noted that only the t i n carbon the s p e c t r a , and  i t s frequency  cm  -1  (4).  observed  may  asymmetric s t r e t c h appears i n  i s s h i f t e d to h i g h e r wave number  as compared to the value of 545-540 c m chloride  It  observed  -1  in trimethyltin  T h i s s h i f t to higher f r e q u e n c i e s from 545-540 f o r t e t r a h e d r a l t r i m e t h y l t i n compounds i s observed  i n other t r i m e t h y l t i n d e r i v a t i v e s  (27, 28, 33, 45) c o n t a i n i n g  a p l a n a r t r i m e t h y l t i n group i n a t r i g o n a l b i p y r a m i d a l c o n f i g u r a t i o n around the t i n atom.  In at l e a s t one of these  derivatives,  (CH3)gSnCl.Py, both the p l a n a r i t y of the t r i m e t h y l t i n group and the f i v e c o o r d i n a t i o n of the t i n atom have been c o n c l u s i v e l y e s t a b l i s h e d by an X-ray  s t r u c t u r e d e t e r m i n a t i o n and  s p e c t r o s c o p i c s t u d i e s (25, 26, 33). Sn-C  infrared  Thus the presence  of only the  asymmetric s t r e t c h and i t s s h i f t to a higher frequency i n -  d i c a t e that both i n b i s ( t r i m e t h y l t i n ) s u l p h a t e and i t s methanol adduct,  the t r i m e t h y l t i n group i s p l a n a r .  a b s o r p t i o n bands due 1165,  1095,  1065,  In the methanol  to the s u l p h a t e group are observed  1021,  989,  630,  595,  558  and 447  cm . -1  adduct  at Free  1300  1200  1100 1000 900 800 WAVENUMBER cm-'  700  aoL  700  I  600  1  I  500 WAVENUMBER  450  I  400  cm-' 00  TABLE  3.1b  I n f r a r e d A b s o r p t i o n Spectra of B i s ( t r i m e t h y l t i n )  Sulphate-Methanol  Adduct and B i s ( t r i m e t h y l t i n ) Sulphate |(CH3)3Sn] S 0 2 ( C H 0 H ) 2  4  3  Frequency R e l a t i v e (cm~l) Intensity 3150-3100  [(CH ) s3 3  3  Frequency (cm" ) 1  SO4  Relative Intensity  Assignment 0-H s t r .  s, b  3020  w  3000  w  C-H  asym. s t r .  2920  w  2900  w  C-H  sym.str.  2800  w  1410  m, b  1400  m  C-H  asym.bend  1195  w  1205  w  C-H  sym.  1165  s  S0  asym.str.,(^g)  1100 1095  s, sh  ip65  s  ^ (so  vs  3  1021 989  2  m  S0  2  S0  2  S0  2  2 4  bend  )  sym. s t r . , (0-^) asym. s t r . , sym. s t r . , (v ) 2  785  780  s  CH  630  s  v (S0 4  S0  630 595 558  m sh  552  s  447  m, b  b = broad: w = weak.  552  2  4  Sn-C Sol  s = strong;  4  sh = shoulder;  4  2  -)  rock, ( v ) 7  bend, 0 ) rock, ( v ) 3  9  asym. s t r . bend, (v\.) v = very;  * denotes the oxygen atoms i n v o l v e d i n bonding.  ments f o r the S 0 assuming  S0 S0  m = medium;  rock  3  that S 0  ^Assign-  4  a b s o r p t i o n bands i n the adduct have been made  4  a c t s as a b r i d g i n g  group.  50 methanol a l s o has region.  a s t r o n g a b s o r p t i o n band i n the 1100-1000  However, i n the b i s ( t r i m e t h y l t i n )  adduct, the 1021  cm"  band i s sharp and  1  (1021  methanol.  1095  and  The  cm" )  of only medium i n t e n s i t y  cm  the 1100-1000 cm~^  s t r o n g sulphate The  band i s u n l i k e l y to be due  1  -1  shoulder  sulphate  i s probably  due  cm ; -1  to  to the methanol  r e g i o n methanol band i s masked by  absorption  at 1065  the  cm" . 1  a b s o r p t i o n i n the spectrum of the  trimethyltin  sulphate-methanol adduct c l e a r l y shows that the symmetry of sulphate group i s . reduced to C v. 2  V3 and v^ modes are  The  s p l i t each i n t o three f r e q u e n c i e s and w i t h moderate i n t e n s i t i e s .  1  sulphate-methanol  i n c o n t r a s t to the strong broad a b s o r p t i o n at 3150-3100 therefore this  cm"  the v^ and  the clearly  v^ modes appear  The  a b s o r p t i o n f r e q u e n c i e s are i n r ^ NH 3_ the same range as r e p o r t e d f o r I (NHQ) Co-^ 7>Co(NH ) ion ^S0_j ~-i 2  4  3  4  L  (91).  Therefore  coordinated  i t can be concluded  to two  that each sulphate group i s  t r i m e t h y l t i n groups.  Moreover the 0-H  absor-  p t i o n of the methanol i s observed as a broad band at 3105-3100 cm"  1  lowered from the 3400 c m  band observed f o r methanol i t s e l f .  -1  T h i s i n d i c a t e s t h a t the methanol molecules are a l s o to  the t r i m e t h y l t i n group.  The  e n t i r e spectrum of the methanol  adduct of b i s ( t r i m e t h y l t i n ) s u l p h a t e s t r u c t u r e shown i n F i g u r e 3.1c,  i s thus c o n s i s t e n t with  which c o n t a i n s p l a n a r  groups, a b r i d g i n g sulphato group and  two  molecules,  coordinate.  making the t i n atoms f i v e  The  sulphate absorption  b i s ( t r i m e t h y l t i n ) sulphate brations ^  3  coordinated  i n the spectrum of  shows only the t r i p l y  at 1100-1090, and  V 4 at 630  cm  -1  only the Sn-C  the  trimethyltin methanol  non-solvated degenerate v i -  indicating  presence of the r e g u l a r t e t r a h e d r a l s u l p h a t e group. out e a r l i e r ,  coordinated  As  the pointed  asymmetric s t r e t c h i s observed at  FIGURE  31c  52 552  cm" ,  i n d i c a t i n g the p l a n a r i t y of the t r i m e t h y l t i n groups.  The  s t r u c t u r e shown i n F i g u r e 3.Id  1  i s proposed to i n c o r p o r a t e  these f e a t u r e s , but t h i s can be i n t e r p r e t e d i n terms of i o n s , (CH-)_Sn  +  and SO^ , -  or e q u a l l y w e l l i n terms of a c o o r d i n a t e d  model where every oxygen of the sulphate group i s c o o r d i n a t e d to a t i n atom.  As a r e s u l t of the molecular  s t o i c h i o m e t r y , the  i n f r a r e d spectrum does not d i f f e r e n t i a t e between these two Both the b i s ( t r i m e t h y l t i n ) sulphate-methanol  adduct  b i s ( t r i m e t h y l t i n ) sulphate showed marked changes i n t h e i r red s p e c t r a on exposure to a i r . sulphate-methanol  adduct,  cm  cm""  1  and 0^  bands g r a d u a l l y disappeared  these were r e p l a c e d by a strong broad band at  bands g r a d u a l l y disappeared  band at 983  infra-  In the b i s ( t r i m e t h y l t i n ) :  and a s t r o n g sharp band at 613  -1  cm .  upon exposing  and  i n a d d i t i o n to the appearance of water  bands, the s p l i t t i n g of the and f i n a l l y  models.  cm ;  both  -1  the 989  1105  and  447  and were r e p l a c e d by a weak  Again t h i s change i n the sulphate spectrum,  -1  the s o l i d to a i r , suggests  that f r e e s u l p h a t e ions  and hydrated  t r i m e t h y l t i n c a t i o n s are produced as a r e s u l t of  hydrolysis.  Since the p o s i t i o n and i n t e n s i t y of the. .Sn-C  asymmetric s t r e t c h does not change, i t can be concluded t r i m e t h y l t i n group i s s t i l l  planar and  that  f i v e coordinate.  However,  i n the i n f r a r e d spectrum of a sample of b i s ( t r i m e t h y l t i n ) sulphate-methanol months, the Sn-C  adduct which was  exposed to a i r f o r about  asymmetric s t r e t c h at 552  s t r o n g band at 541  and a medium band at 513  two  cm was r e p l a c e d by a -1  cm"' , probably  indi-  1  c a t i n g the formation of a t e t r a h e d r a l t r i m e t h y l t i n s p e c i e s . S i m i l a r l y i n non-solvated  b i s ( t r i m e t h y l t i n ) s u l p h a t e , the  sulphate  a b s o r p t i o n s showed g r a d u a l changes i n the i n f r a r e d spectrum upon  54 exposing the s o l i d t o a i r .  A f t e r a short exposure, i n a d d i t i o n  to the appearance of water bands, the  mode showed bands at  1140,1100 and 1065, a medium band appeared a t 989 c m , and 630 -1 1 cm band became broad, and a s t r o n g band a t 613 cm and a medium -1  band a t 475 c m  - 1  appeared.  exposure, the V3 mode  A f t e r a longer  appeared a t 1100-1090 as a s i n g l e broad band, the v*-^ mode showed only a weak a b s o r p t i o n 6 1 3 cm" .  a t 885 c m  T h i s gradual  1  and V4 appeared s t r o n g l y a t  - 1  change i n the sulphate  p a r t of the spectrum  i n d i c a t e s t h a t , immediately a f t e r exposure of b i s ( t r i m e t h y l t i n ) sulphate  to a i r , the sulphate  symmetry i s reduced t o C  2 v  as a  r e s u l t of p a r t i a l h y d r o l y s i s and, on f u r t h e r h y d r o l y s i s , f r e e sulphate again 3.2  ions are produced.  T h i s behaviour on h y d r o l y s i s i s  c o n s i s t e n t with a c o o r d i n a t e d B i s ( t r i m e t h y l t i n ) Chromate  structure.  QcHg) 3S11J r 0 4 c  2  The i n f r a r e d and Raman s p e c t r a of chromates have been studied  (68, 97, 98). The e a r l i e r assignments f o r the fundamental  frequencies  of the chromate i o n have been r e v i s e d by Stammreich,  B a s s i and Sala  (97).  The fundamental v i b r a t i o n a l f r e q u e n c i e s and  the r e v i s e d assignments o f the f r e e chromate i o n are shown i n Table.3.2.  I t may be mentioned that these authors c o u l d not be  c e r t a i n whether the assignment i s 0 versa,' but p r e f e r r e d the former. (98)  have r e p o r t e d  = 348, v*^ = 368 or v i c e  However, M i l l e r and coworkers  that the i n f r a r e d band f o r the chromate i o n  i n the cesium bromide r e g i o n therefore  2  i s observed a t 370-420 c m ; -1  the assignments shown i n Table 3.2 are c o n s i d e r e d  to be  correct. Some chromato complexes of c o b a l t have been r e p o r t e d and from the e l e c t r o n i c s p e c t r a l s t u d i e s of these complexes, Shimura  55 TABLE  3.2  2V i b r a t i o n a l Frequencies of C 04  Ion  r  Vibrational mode  (Point Group T<j) Frequency (cm- )  Assignment  1  Activity  (A^)  Symmetric s t r e t c h  847  (R)  V .  (E)  Symmetric bend  348  (R)  V3  (F )  Asymmetric s t r e t c h  884  ^4  ^ 2^  Asymmetric bend  368  s  2  F  (R = Raman a c t i v e ;  I.R  (R,I.R) (R,I.R)  = Infrared active) 2~  and Tsuchida  (99) have i n d i c a t e d the e a r l y p o s i t i o n of CrO^  in  the s p e c t r o c h e m i c a l s e r i e s , but no i n f r a r e d s t u d i e s on c o o r d i n a t e d chromates have been r e p o r t e d .  However, the symmetry of the chro-  mate group, and t h e r e f o r e the number of i n f r a r e d a c t i v e modes, w i l l change upon c o o r d i n a t i o n i n a s i m i l a r manner as t h a t d i s c u s s e d f o r other t e t r a h e d r a l anions. The  observed  i n f r a r e d spectrum  of b i s ( t r i m e t h y l t i n ) chromate  i s very s i m i l a r to that of non-solvated t r i m e t h y l t i n s u l p h a t e . The main f e a t u r e s of the spectrum group at 885  cm" , 1  the Sn-CHg rock at 750  asymmetric s t r e t c h at 554 554  cm . -1  The  are the \?3 mode of the chromate  cm . -1  c r y s t a l l i n e i o n i c chromates at 368  cm"  highly  The  the chromate group has group i s p l a n a r .  The  t r i m e t h y l t i n sulphate  -1  and the  No a b s o r p t i o n was  mode u s u a l l y observed  concentrated nujol mulls.  cm ,  Sn-C  observed  below  as a weak doublet f o r was  1  not observed  spectrum  symmetry and that the  even i n  i n d i c a t e s that trimethyltin  s t r u c t u r e proposed  f o r the non-solvated  (see F i g u r e 3.Id)  i s a l s o a p p l i c a b l e to  56 t r i m e t h y l t i n ehromate and again the i n f r a r e d spectrum i s not h e l p f u l i n e l u c i d a t i n g , t h e nature or the extent of a n i o n - c a t i o n interaction.  T r i m e t h y l t i n chromate, i n c o n t r a s t to t r i m e t h y l t i n  s u l p h a t e , d i d not form a methanol adduct nor d i d i t h y d r o l y s e on exposure t o a i r . The u l t r a v i o l e t of  and v i s i b l e  d i f f u s e r e f l e c t a n c e spectrum  t r i m e t h y l t i n chromate was examined and compared with the spec-  trum of powdered potassium chromate.  T r i m e t h y l t i n chromate  showed a b s o r p t i o n maxima at 310 and 420 nj^,  showing very  change from the maxima observed a t 275 and 375 m// chromate.  f o r potassium  T h i s i s i n agreement w i t h the r e p o r t e d spectrum of the  complex C o ( N H 3 ) g C r O ^ 2CrO^  little  (100), which i s very s i m i l a r t o t h a t of  i o n showing that c o o r d i n a t i o n by chromate through an oxygen  atom has l i t t l e  e f f e c t on the charge t r a n s f e r band.  57  CHAPTER 4 DIMETHYLTIN(IV) DERIVATIVES  As mentioned e a r l i e r , very l i t t l e work has been done on structure  elucidation  of d i a l k y l - or d i p h e n y l t i n  In the present i n v e s t i g a t i o n ,  such as d i m e t h y l t i n  bis(tetrafluoroborate),  derivatives.  attempts were made to s y n t h e s i z e and  examine, by i n f r a r e d spectroscopy, a wide v a r i e t y acid derivatives  acid  dimethyltin  carbonate, chromate,  hexafluorosilicate,  phate), b i s ( h e x a f l u o r o a r s e n a t e ) ,  of  bis(hexafluorophos-  bis(hexafluoroantimonate), 2-  and  the d i m e t h y l t i n  derivative  known compounds, d i m e t h y l t i n  of P12CI12  .  In a d d i t i o n , the  d i f l u o r i d e and s u l p h a t e were a l s o  studied^ 4.1  Dimethyltin Difluoride  (CH3) SnF 2  2  In a comparison of m e t h y l t i n c h l o r i d e s , Wood (4) r e p o r t e d a d i s t i n c t f a l l c o n s t a n t s , i n the s e r i e s SnCl^, (CHg^SnCl.  i n the Sn-Cl s t r e t c h i n g  (CH^SnClg,  T h i s sequence f o l l o w s  Sn-Cl bond.  of d i m e t h y l t i n  inductive  the i o n i z a t i o n of  A s i m i l a r comparison of the i n f r a r e d d i f l u o r i d e and t r i m e t h y l t i n  dered d e s i r a b l e .  force  ( C H g ^ S n C l g and  the i n c r e a s i n g  e f f e c t of the methyl groups, f a c i l i t a t i n g the  Taimsalue and  spectra  f l u o r i d e was c o n s i -  The i n f r a r e d spectrum of d i m e t h y l t i n  and  the Sn-F v i b r a t i o n  not  been r e p o r t e d and were measured i n t h i s work.  difluoride  frequency i n t r i m e t h y l t i n f l u o r i d e have  In the i n f r a r e d spectrum of d i m e t h y l t i n  d i f l u o r i d e , the  a b s o r p t i o n bands were observed at 3040(w), 2940 (vw),  1410  (vw,b) 1210(w,sp), 785(m), 595(m,sp) a n d 3 7 3 ( s ) c m .  These  -1  58 bands can 2940 cm ,  be assigned C-H  -1  as, 3040 cm ,  symmetric s t r e t c h ; 1410  1210  cm'", C-H  Sn-C  asymmetric s t r e t c h .  -  1  symmetric bend; 785 The  a s s o c i a t e d w i t h the Sn-F f l u o r i d e , a strong assigned  C-H  -1  to the Sn-F  sence of only one  cm ,  C-H  -1  asymmetric bend;  CH3 rock;  cm , -1  strong band at 373  bond.  band was  asymmetric s t r e t c h ;  and  cm  595 must  -1  -1  be  In the spectrum of t r i m e t h y l t i n  observed at 355  cm  -1  which can  asymmetric s t r e t c h i n g v i b r a t i o n .  Sn-C  cm  The  be pre-  s t r e t c h i n g frequency i n d i m e t h y l t i n  d i f l u o r i d e i n d i c a t e s that the d i m e t h y l t i n group i s l i n e a r .  Thus  d i m e t h y l t i n d i f l u o r i d e and  t r i m e t h y l t i n f l u o r i d e apparently  have  d i f f e r e n t stereochemistry,  and  each compound should Nevertheless,  the Sn-F  s t r e t c h i n g frequency i n  a r i s e from a d i f f e r e n t v i b r a t i o n a l mode.  i t i s i n t e r e s t i n g to note that^Sn-F frequency i n  d i m e t h y l t i n d i f l u o r i d e occurs at higher wave number compared to the Sn-F  frequency i n t r i m e t h y l t i n f l u o r i d e .  As me-flftioned e a r l i e r , fluoride gests  (39)  the c r y s t a l s t r u c t u r e of t r i m e t h y l t i n  cannot be i n t e r p r e t e d as i o n i c , and  s t r o n g l y sug-  that some type of c o o r d i n a t i v e i n t e r a c t i o n between  t r i m e t h y l t i n groups and comparison of the  Sn-F  f l u o r i n e atoms i s i n v o l v e d .  From a  frequency i n d i m e t h y l t i n f l u o r i d e w i t h  that of t r i m e t h y l t i n f l u o r i d e , and  i n view of the  nature of t r i m e t h y l t i n f l u o r i d e , i t should  non-ionic  t h e r e f o r e be  dered that d i m e t h y l t i n d i f l u o r i d e cannot have a p u r e l y structure.  As was  pointed  d i m e t h y l t i n d i f l u o r i d e may two  out by B e a t t i e and G i l s o n  consiionic  (36),  have a polymeric s t r u c t u r e , i n which  methyl groups occupy t r a n s p o s i t i o n s and  f l u o r i n e atoms occupy the four corner  the four  p o s i t i o n s i n the  plane making the t i n atom s i x c o o r d i n a t e .  bridging equatorial  The e f f e c t i v e  59 symmetry of such a trans o c t a h e d r a l u n i t would be D  4 h  i n f r a r e d a c t i v e v i b r a t i o n s of the s p e c i e s 2 A  U  expected.  Of  these  + 3E  2 u  and  five  would  be  f i v e v i b r a t i o n a l modes, only two  asymmetric s t r e t c h ( A ) , and  Sn-F  2 u  fsn-C (E )^J  asymmetric s t r e t c h  would have v i b r a t i o n a l f r e q u e n c i e s above 300  cm-'-.  U  Thus the  -  observed i n f r a r e d spectrum of d i m e t h y l t i n d i f l u o r i d e i s c o n s i s t e n t with  such a s t r u c t u r e .  The  Sn-F  frequency  d i m e t h y l t i n d i f l u o r i d e compares w e l l w i t h value  (400  cm )  f o r the Sn-0  -1  (373  cm" )  in  1  the r e p o r t e d  (50)  asymmetric s t r e t c h i n g frequency  the d i m e t h y l t i n a c e t y l a c e t o n a t o  complex,  (CH3) Sn(C5Hy0 ) 2  2  which  2  i s a l s o i n d i c a t e d to have a t r a n s o c t a h e d r a l s t r u c t u r e , on b a s i s of i t s  Raman and  in  the  infrared spectra.  It i s known that a l k y l t i n  d i f l u o r i d e s form complexes with + 2a l k a l i metal f l u o r i d e s of the type M R S n F (2a). If the 2+ 2  dialkyltin  2  4  d i f l u o r i d e c o n t a i n s the f r e e ions RgSn  and  F", i . e .  the f l u o r i d e ions are o u t s i d e the c o o r d i n a t i o n sphere of RgSn group, then  the formation  f l u o r i d e i o n s are now be c o n s i d e r e d 4.2  the  of a complex, i n which f o u r  w i t h i n the c o o r d i n a t i o n sphere, can  only  somewhat of an anomaly.  D i m e t h y l t i n Carbonate  (CH ) SnC0 3  2  3  2The  f r e e carbonate i o n (CO3  belongs to the p o i n t group D h 3  s p e c t r a of carbonates  ) i s t r i g o n a l planar  (65a).  have been w i d e l y  The  and  i n f r a r e d and Raman  studied  (47b)  and  the  fundamental f r e q u e n c i e s of the carbonate i o n , shown i n Table 4.2a  are w e l l e s t a b l i s h e d The  ally,  (65a).  s p e c t r a of c r y s t a l l i n e i o n i c carbonates  i n t o one  of two  groups a c c o r d i n g  i s of the c a l c i t e or a r a g o n i t e  type  fall,  gener-  to whether the compound  (47b).  The d i f f e r e n c e  60 TABLE 4.2a 2— V i b r a t i o n a l Frequencies of CO3 Ion (Point Group D 3 ) n  Vibrational  Frequency  mode v-  Assignment  Xcm~l)  CO symmetric  1  stretch  v  2  A'g  Out-of-plane bend  v  3  E'  Degenerate  stretch  v  4  E  Degenerate  bend  /  (R = Raman a c t i v e ;  between the two groups  Activity  1063  (R)  879  (I.R)  1430  (R,I.R)  680  (R,I.R)  I.R = I n f r a r e d  active)  a r i s e s mainly from the i n t e r m o l e c u l a r  c o u p l i n g of the o u t - o f - p l a n e bending  .... mode vVj (101) , and the  lower symmetry of the carbonate i o n i n the c r y s t a l  (47b).  The  s i t e symmetry of the carbonate i o n i n a c a l c i t e type c r y s t a l i s D3, whereas i t i s C  s  i n a r a g o n i t e (47b).  As seen from the c o r -  r e l a t i o n Table 2.1b, there i s no change i n the s e l e c t i o n i n going from Dgj. to D^ symmetry.  The spectrum  rules  of c a l c i t e i s  very s i m i l a r to that of a f r e e carbonate i o n and the i n f r a r e d a b s o r p t i o n bands appear (91).  a t 1430 ( v s ) , 874 (s) and 710 (m) c m  of a r a g o n i t e , the O j mode shows  \In the i n f r a r e d spectrum  a weak a b s o r p t i o n a t 1080 c m  - 1  - 1  and the V4 mode s p l i t s i n t o two  bands a t 710 and 696 c m , but there i s no s p l i t t i n g of the A) -1  mode (91).  3  From a study of the s o l i d s t a t e i n f r a r e d s p e c t r a of  the carbonates of main group Ross and Goldsmith  and f i r s t  row t r a n s i t i o n metals,  (102) have concluded that the c r y s t a l f i e l d i n  carbonates cannot be very s t r o n g .  These authors observed  that  the s p l i t t i n g s of the ^3 and v" modes are u s u a l l y s m a l l and 4  sometimes absent.  I n f r a r e d s p e c t r a of anhydrous a l k a l i  metal  carbonates (103) .  a l s o show only s m a l l s p l i t t i n g s of degenerate modes  Only i n anhydrous l i t h i u m carbonate  show a s p l i t t i n g i s observed  of about 60 c m , and no s p l i t t i n g  i n sodium and potassium  long time.  •Co(NHg)gCO^ i t became  carbonates.  complexes of c o b a l t ( I I I ) have been known From the e x i s t e n c e of C o ( N H ) C 0 3  e v i d e n t that the C 0  b i d e n t a t e and sometimes a u n i d e n t a t e of the carbonate  f o r t h i s mode  -1  Metal-carbonato f o r a very  does the \)g mode  4  3  + 3  and  group sometimes i s a  ligand.  group i n C o ( N H ) C 0 3  3  4  The b i d e n t a t e  nature  has r e c e n t l y been proved by  an X-ray 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  (104).  The carbonate  i o n can c o o r d i n a t e to the metal atom (M) i n one of the f o l l o w i n g ways: M  M  \  0  10  1 :  c  n o  /\  ,  /\  0 1  ,  M—-0  0  \/  \/  I  l!  c  o n  c  o n  o n  Unidentate  Bidentate  Bridging  C  C  C  s  symmetry  2 v  M  symmetry  2 v  symmetry  (OI r e p r e s e n t s oxygen atoms i n v o l v e d i n c o o r d i n a t i o n , O i l r e p r e s e n t s oxygen atoms not i n v o l v e d i n c o o r d i n a t i o n . )  As d i s c u s s e d i n s e c t i o n 2.1, upon lowering i o n symmetry to e i t h e r C  s  or C2 > V  t  n  e  the carbonate  i n f r a r e d j l i c t i v e mode  of the f r e e i o n becomes i n f r a r e d a c t i v e and the degenerate modes of the f r e e i o n are each r e s o l v e d i n t o twx> cmodesi;:thu;s /giying r i s e  to a t o t a l of s i x i n f r a r e d a c t i v e v i b r a t i o n s . spectra  In the i n f r a r e d  of carbonato complexes, the v^ mode of the f r e e C0^~  i o n appears w i t h moderate i n t e n s i t y , and the degenerate modes show l a r g e r  s p l i t t i n g s than those causedby  crystal field  effects.  i  Gatehouse, L i v i n g s t o n ,  and Nyholm (105) suggested the v i b r a t i o n a l  modes of a c o o r d i n a t e d carbonato group,  assuming C 2  V  symmetry  which are shown i n Table 4.2b.  TABLE 4.2b V i b r a t i o n a l Modes of The Carbonato  «!>  C0  (Aj)  CO s t r e t c h  h  (AJ)  C0  h  (B )  Asymmetric  h  (82)  P l a n a r rock •  2  symmetric  2  Symmetry  stretch  stretch  rock  These authors c l a s s i f i e d modes  the B j s p e c i e s ,  2 v  bend  2  Non-planar Note:  Groups of C  and v'g t o B . 2  and v" as b e l o n g i n g to 5  T h i s c l a s s i f i c a t i o n has been r e -  v e r s e d here i n c o n f o r m i t y with the c o r r e l a t i o n t a b l e s  i n Wilson,  Decius, and Cross (71). From a s o l i d s t a t e  i n f r a r e d study of a number of metal-  carbonato complexes c o n t a i n i n g both u n i d e n t a t e and b i d e n t a t e carbonato groups,  these authors found that  f r e q u e n c i e s of the carbonato group Vibrational mode Frequency (cm-1)  . v  4  1577-1493  . Vj  fall  the v i b r a t i o n a l  i n the f o l l o w i n g  v* (1080-1055 1338-1260 (1050-1021 2  v  g  889-824  ranges:  v*. or \ ) 809-738  5  of the ^3 mode of the  These authors showed that the s p l i t t i n g 2 —  f r e e CO3  i o n i n c r e a s e s along the s e r i e s :  carbonato complexes < a c i d carbonates  basic  carbonates^  o r g a n i c carbonates.  However, these authors d i d not d i f f e r e n t i a t e between the v i b r a t i o n a l modes o f u n i d e n t a t e and b i d e n t a t e (or b r i d g i n g ) c a r bonato groups.  Nakamoto and coworkers  ( 9 1 ) examined the  i n f r a r e d s p e c t r a o f both u n i d e n t a t e and b i d e n t a t e carbonato groups  and found that the s p l i t t i n g  of the V g mode i s  g r e a t e r f o r the b i d e n t a t e than f o r the u n i d e n t a t e carbonato group,  but that t h e r e  i s no s i g n i f i c a n t  d i f f e r e n c e i n the  f r e q u e n c i e s of the f o u r remaining bands. However, as r e c e n t l y p o i n t e d out by E l l i o t (106)  and Hathaway  the change from a u n i d e n t a t e to a b i d e n t a t e carbonate  group may be c o n s i d e r e d t o i n v o l v e an i n c r e a s e i n the double bond c h a r a c t e r of the C - 0 s t r e t c h i n g v i b r a t i o n , ( v ^ ) , r e s u l t i n g i n an i n c r e a s e i n the C - 0 s t r e t c h i n g frequency, and a lowering of  the double bond c h a r a c t e r o f the C 0  2  group w i t h a consequent  lowering of the f r e q u e n c i e s o f the symmetric CO2 s t r e t c h i n g v i b r a t i o n . a l t e r the assignments of  and asymmetric  The r e s u l t o f t h i s change i s t o  of the f i r s t  t h r e e high frequency bands  the b i d e n t a t e carbonato group t o vi  (A ) C"s--0 symmetric stretch x  1577-1493  v  (B ) C 0 asymmetric stretch 4  2  2  1338-1260  _ (Aj) C O g symmetric stretch v  (1080-1055 (1050-1021  It can be seen that the v i b r a t i o n a l modes suggested by Gatehouse, L i v i n g s t o n , and Nyholm f o r the carbonato group  i n fact represent  the v i b r a t i o n a l modes of a u n i d e n t a t e carbonato group.  The  63 v i b r a t i o n a l modes of u n i d e n t a t e and b i d e n t a t e carbonato groups would be s i m i l a r to those of u n i d e n t a t e and b i d e n t a t e  nitrato  groups and the same convention has been used i n numbering  the  v i b r a t i o n a l modes. L a t e r , F u j i t a , M a r t e l l and Nakamoto (107) r e p o r t e d the r e s u l t s of a normal c o o r d i n a t e a n a l y s i s of u n i d e n t a t e and b i dentate carbonato groups. C  as w e l l as  s  These authors used models based on  symmetry f o r the u n i d e n t a t e carbonato group.  A model based on a four membered c h e l a t e r i n g of was  used f o r the b i d e n t a t e carbonato group.  symmetry  Their  calculated  r e s u l t s are shown i n T a b l e 4.2c. TABLE 4.2c C a l c u l a t e d F r e q u e n c i e s of Unidentate and B i d e n t a t e C o ( I I I ) Carbonato Complexes  (cm ) -1  Unidentate Vibrational mode Assignment  Frequency ^2v  ^3 (C  -°II> str.  1483 1482  (C-0 )  (C-0!)  str. + (C-0j)str,  str. + (C-0 ) str.  n  1373 1376  ^6  ( O C O ) (OnCOn) rock bend n  H  n  1039 1069  765 772  711 676  Bidentate Vibrational mode Assignment  Frequency  vi  ^3  (C-O ) str. n  1595  (G-Oj) (C-Oi) str.+ str. (OiCOn)bend  1282  1038  Ring def,  •+ ( C o - p ;  str,  771  *6 (OlCOn) bend + (C-Oi)str, +(Co-Gi) str. 669  .65  The  numbering of  modes used by these workers i s s l i g h t l y  differ-  ent because v i b r a t i o n a l f r e q u e n c i e s i n v o l v i n g metal-oxygen bonds have a l s o been i n c l u d e d i n the above shown assignments. r e s u l t s confirm  the g e n e r a l c o n c l u s i o n s , about the  s p e c t r a of the c o o r d i n a t e d workers (91, 105).  These  infrared  carbonato group, reached by  earlier  However, these r e s u l t s show c o u p l i n g between  v a r i o u s v i b r a t i o n a l modes i n metal-carbonato complexes c o n t a i n i n g f o u r membered r i n g s . Very r e c e n t l y E l l i o t  and Hathaway (106)  have  r e p o r t e d the p o l a r i z a t i o n data f o r s i n g l e c r y s t a l s of Co(NHg^COsBr. T h e i r r e s u l t s confirm  the normal c o o r d i n a t e  a n a l y s i s model i n -  v o l v i n g c o v a l e n t bonding of the carbonate oxygen atoms to the cobalt ion. The  i n f r a r e d spectrum of d i m e t h y l t i n carbonate  measured on a mixture of d i m e t h y l t i n carbonate and c h l o r i d e , which was  obtained  d i m e t h y l t i n d i c h l o r i d e and  s i l v e r carbonate i n methanol f o l l o w e d  of the mixture were examined and no  X-ray powder photographs  l i n e s due  t i n c h l o r i d e or s i l v e r carbonate were found.  due  to e i t h e r d i m e t h y l Therefore  that the i n f r a r e d spectrum thus; obtained  to d i m e t h y l t i n carbonate.  i s shown i n F i g u r e 4.2,  silver  by the m e t a t h e t i c a l r e a c t i o n of  by removal of the s o l v e n t under vacuum.  considered  was  and  i t may  be  i s largely  A p o r t i o n of the observed spectrum  the f r e q u e n c i e s , together w i t h  the  r e l a t i v e i n t e n s i t i e s of the a b s o r p t i o n bands i n the r e g i o n 2000250  cm  4.2d.  and  -1  The  t h e i r suggested assignments, are l i s t e d i n Table  a b s o r p t i o n bands due  e a s i l y d i s t i n g u i s h e d and  assigned,  bend; 1200  cm ,  cm ,  asymmetric s t r e t c h ; and  -1  Sn-C  stretch.  -1  The  C-H  to the d i m e t h y l t i n group can i . e . 1415  symmetric bend; 785  absorptions  due  523  cm  cm ,  cm , -1  -1  C-H  -1  CH  Sn-C  3  be  asymmetric  rock;  576  symmetric  to the carbonate group occur  at  Frequency ( c m ) -1  67 TABLE 4. 2d I n f r a r e d A b s o r p t i o n Spectrum of D i m e t h y l t i n Carbonate Frequency  (cm ) -1  Relative  Intensity  ; r  ; Assignment  1510  vs  C = 0 sym. s t r . ^ v p  1415  sh  C - H asym.bend  1385  vs  COo asym.str., (v )  1200  m  C - H sym.  1105 1068  w m  CO2  832  m  COo o u t - o f - p l a n e def.,  4  bend  sym.str.,  (v ) 6  785  s  CH3 rock  700  m  CO2 sym.bend , ( ^ 3 )  655  s  C0  576  s  Sn-C asym. s t r .  523  m  Sn-C  500 340 275  s m m  Sn-0 asym. s t r . and L a t t i c e modes ?  m = medium;  s = strong;  sh = shoulder;  Assignments f o r the carbonate  sym. s t r .  v = very;  w = weak.  a b s o r p t i o n bands have been sug-  gested, assuming that the carbonate  1  asym.bend , ( ^ 5 )  2  group i s b r i d g i n g .  68 1510,  1385, 1105, 1068, 832, 700, 655, 500, 340 and 275 c m . I t -1  i s e v i d e n t that the s t r o n g bands a t 1510 and 1385 e m  correspond  -1  to the doubly degenerate mode v'g of the f r e e carbonate i o n which has s p l i t  i n t o these two s t r o n g bands.  The 1105 and 1068 cm"  bands correspond to the i n f r a r e d i n a c t i v e p n o d e ^ i o n , the 832 c m  - 1  1  of the f r e e  band corresponds to the o u t - o f - p l a n e bending  mode Og of the f r e e i o n , and the bands a t 700 and 655 are the two components of the doubly degenerate mode T)^ of the f r e e i o n . a b s o r p t i o n bands i n the r e g i o n 500-275 c m  - 1  are l i k e l y  The  to be  a s s o c i a t e d w i t h the Sn-0 s t r e t c h i n g v i b r a t i o n s as w e l l as w i t h the a b s o r p t i o n s of the l a t t i c e modes. at 450, 375 and 250 cm"  1  S i m i l a r a b s o r p t i o n bands  were a l s o observed i n the spectrum of  trimethylantimony carbonate  (to be d i s c u s s e d l a t e r ) .  It i s  known (108) t h a t the carbonates have a l a t t i c e - t y p e a b s o r p t i o n in this region.  M i l l e r and coworkers  (98) have r e p o r t e d s i m i l a r  bands i n the s p e c t r a of some metal c a r b o n a t e s ^ e . g . ;  lithium  carbonate shows strong a b s o r p t i o n bands a t 498 and 420 c m , -1  l e a d ( I I ) carbonate has a s t r o n g broad band at 400 cm" , and 1  c a l c i t e has a s t r o n g band a t 320 cm~l. The  i n f r a r e d spectrum  of d i m e t h y l t i n carbonate  shows that the symmetry of the carbonate group Dgjj t o C  2 v  i s lowered  or C , and the magnitude of the s p l i t t i n g s s  clearly  observed  f o r degenerate modes i n d i c a t e s that the carbonate group o r d i n a t e d to the d i m e t h y l t i n group. two  from  i s co-  Moreover, the presence of  Sn-C s t r e t c h i n g v i b r a t i o n s of medium i n t e n s i t y suggests that  the d i m e t h y l t i n group  i s non-linear.  f r e q u e n c i e s a t 576 and 523 c m dimethyltin dichloride  - 1  These two Sn-C s t r e t c h i n g  can be compared with those of  (4) which occur a t 567 and 515 c m . -1  Therefore  the p o s s i b i l i t y of any  d i c h l o r i d e being  present  observed s p l i t t i n g  i n the mixture i s very  of the 0-  l e s s than that r e p o r t e d  s i g n i f i c a n t amount of low.  dimethyltin Though the  mode i n d i m e t h y l t i n carbonate i s  (107)  f o r bidentate  carbonato complexes,  the e n t i r e i n f r a r e d spectrum of d i m e t h y l t i n carbonate suggests that the  t i n atom has  a t e t r a h e d r a l c o n f i g u r a t i o n which w i l l  imply; some s o r t of c o o r d i n a t e group and  two  bonding between the  of the oxygen atoms of the carbonate group.  polymeric s t r u c t u r e c o n s i s t i n g of n o n - l i n e a r and  A  d i m e t h y l t i n groups  b r i d g i n g carbonato groups, making the t i n atom t e t r a h e d r a l ,  i s suggested.  A monomeric s t r u c t u r e c o n t a i n i n g  carbonato group c o o r d i n a t e d a l s o p o s s i b l e , but bility 4.3  dimethyltin  and  to a n o n - l i n e a r  i s considered  a  bidentate  d i m e t h y l t i n group i s  l e s s l i k e l y due  to the i n s o l u -  n o n - v o l a t i l i t y of the compound.  Dimethyltin  Chromate  (CH ) SnCr0 3  2  4  In an attempt to prepare d i m e t h y l t i n chromate, Rochow, Seyferth, and by  Smith (16)  obtained  a basic dimethyltin  the r e a c t i o n between d i m e t h y l t i n  chromate i n aqueous s o l u t i o n .  d i c h l o r i d e and  In the present  chromate  sodium  investigation,  d i m e t h y l t i n chromate c o u l d be prepared by  the m e t a t h e t i c a l  a c t i o n between d i m e t h y l t i n  s i l v e r chromate i n  acetone or a c e t o n i t r i l e . due  d i c h l o r i d e and  However, l i k e d i m e t h y l t i n  carbonate,  to the i n s o l u b i l i t y of d i m e t h y l t i n chromate i n any  solvent  (from which the compound c o u l d be recovered  re-  suitable  without  decomposition), the d i m e t h y l t i n chromate formed i n the metat h e t i c a l r e a c t i o n c o u l d not be i s o l a t e d f r e e from chloride.  Therefore  silver  the i n f r a r e d spectrum of t h i s compound  7Q was  s t u d i e d using the mixture of d i m e t h y l t i n chromate and  chloride.  A p o r t i o n of the observed i n f r a r e d spectrum i s shown  i n F i g u r e 4.3. with  The  absorption  frequencies  t h e i r r e l a t i v e i n t e n s i t i e s and  Table  silver  are l i s t e d  together  suggested assignments, i n  4.3. 2— The  fundamental f r e q u e n c i e s  of the chromate i o n ( C r 0  have already been g i v e n i n s e c t i o n 3.2.  In the i n f r a r e d spectrum  of d i m e t h y l t i n chromate, the a b s o r p t i o n bands due t i n group occur bend); 1195  at 2940, (C-H  (C-H  The  bands at 975,  928,  due  to a b s o r p t i o n  by  obtained  s t r e t c h ) ; 1405,  symmetric s t r e t c h ) ; 785,  asymmetric s t r e t c h ) ; and  512,  880,  (Sn-C  750,  (CH  (C-H  390,  the chromate group.  348,  dichloride.  asymmetric  and  cm . -1  305  cm"  1  are was  dimethyltin t h a t some of these  to some unreacted s i l v e r chromate or  dimethyltin  T h i s can be r e j e c t e d , however, on the f o l l o w i n g  grounds: (a) the q u a n t i t a t i v e amount of s i l v e r c h l o r i d e obtained  (Sn-C  Since the spectrum  chromate, the p o s s i b i l i t y must be c o n s i d e r e d be due  dimethyl-  r o c k ) ; 573,  3  f o r a mixture of s i l v e r c h l o r i d e and  bands may  to the  symmetric s t r e t c h )  465,  )  4  on d i s s o l v i n g the mixture i n water a c i d i f i e d  was  with  a c e t i c a c i d ; (b) X-ray powder photographs of the mixture d i d not show any  l i n e s due  dichloride;  to e i t h e r s i l v e r chromate or  (c) the Sn-Cl s t r e t c h i n g v i b r a t i o n s , which  observed i n the i n f r a r e d spectrum at 332  and  dimethyltin  307  cm  -1  (4) of d i m e t h y l t i n d i c h l o r i d e  as s t r o n g bonds, do not appear i n the  i n f r a r e d spectrum of the mixture; stretching frequencies  (d) the observed  - 1  The  Sn-C  i n the spectrum of the mixture  s l i g h t l y from those of d i m e t h y l t i n d i c h l o r i d e (567 cm ).  are  observed spectrum i s t h e r e f o r e due  and  only to  differ 515 dimethyl-  Me SnCr0 2  I  1200  I  I  1000  I  l  800  l  4  l  600  WAVENUMBER (cm ) -1  l  l  400  i  I  200  TABLE 4.3 I n f r a r e d A b s o r p t i o n Spectrum of D i m e t h y l t i n Chromate Frequency  (cm" ) 1  Relative  Intensity  Assignment  2940  vw  C-H  1405  w  C-H asym.bend  1195  m  C-H sym.bend  975  vs  CrOg asym. s t r . >(v )  928  vs  Cr0  2  sym.str  880  vs  Cr0  2  sym.str.,(^3)  785  vs  CH3 rock  750  vs  Cr02  573  m  Sn-C asym.str.  512  m  Sn-C sym.str.  465  ms  CrO^  390  m  Cr0  2  348  m  Cr0  4  305  m  Cr0  2  str.  6  sym.str.,  r o c k , (v" ) 7  bend,(v ) 3  rock,(^ ) 9  sym.bend  m = medium; s = s t r o n g ; v = very; w = weak. Note:  The cromate a b s o r p t i o n bands have been a s s i g n e d by analogy  w i t h SO4 group of C  2 v  symmetry.  73 tin  chromate. The presence of two Sn-C s t r e t c h i n g f r e q u e n c i e s  that the d i m e t h y l t i n group i s n o n - l i n e a r  indicates  i n d i m e t h y l t i n chromate.  The chromate a b s o r p t i o n bands i n d i m e t h y l t i n chromate are r e The 0- mode  markably d i f f e r e n t from those of i o n i c chromates. observed a t 884 c m  - 1  f o r the chromate i o n i s r e s o l v e d i n t o three  strong bands a t 975, 928 and 880 cm"''. 1  The  mode observed only  as a very weak band a t 845 cm""-- f o r the chromate i o n , shows 1  strong absorption  a t 750 cm ' ' appearing -  1  as one of the components  of a broad band g i v i n g r i s e to strong a b s o r p t i o n cm  - 1  r e g i o n ; another component  At lower f r e q u e n c i e s , band due t o the t r i p l y doublet  i s the Sn-CHg r o c k i n g  frequency.  the f r e e chromate i o n shows only a weak degenerate mode 0^, u s u a l l y observed as a  i n the 420-370 cm" ' r e g i o n . 1  defined absorption  i n the 800-720  The appearance of w e l l  bands of medium i n t e n s i t y a t 465, 390, 348  and 305 cm" , i n the i n f r a r e d spectrum of d i m e t h y l t i n chromate, 1  shows t h a t the ^ and the  mode o f the f r e e i o n has s p l i t  i n t o three modes  mode has become i n f r a r e d a c t i v e , although Sn-0 v i -  b r a t i o n s may p o s s i b l y a l s o cause a b s o r p t i o n C e r t a i n l y the chromate a b s o r p t i o n  i n this  region.  bands i n d i m e t h y l t i n  chromate  can only be i n t e r p r e t e d i n terms of a C 2 ( & r p o s s i b l y lower) V  symmetry of the chromate group. As i n the case of other  s o l i d s t a t e s p e c t r a , the lower  symmetry of the chromate group observed i n t h i s spectrum c o u l d be a t t r i b u t e d to c r y s t a l f i e l d e f f e c t s .  However, r e c e n t  studies  made by Campbell (109) on a l a r g e number of chromates, c o n t a i n i n g a wide v a r i e t y of c a t i o n s , showed t h a t c r y s t a l f i e l d e f f e c t s do not cause s i g n i f i c a n t changes i n the i n f r a r e d s p e c t r a of c  74 chromates.  Not even i n ammonium chromate, where hydrogen bonding  i s known t o occur of the  (109) were such l a r g e and w e l l d e f i n e d  splittings  mode observed, and only minor e f f e c t s were observed i n  the 500-250 c m  region  - 1  i n c o n t r a s t t o the pronounced  observed f o r d i m e t h y l t i n chromate. and extent  splittings  The e n t i r e i n f r a r e d p a t t e r n  of s p l i t t i n g s observed f o r d i m e t h y l t i n chromate are  q u i t e d i f f e r e n t from those which c o u l d be a t t r i b u t e d t o c r y s t a l field effects.  Therefore  the i n f r a r e d spectrum of d i m e t h y l t i n  chromate can only be e x p l a i n e d  i n terms of a c o o r d i n a t e d  i n which the chromate group i s c o o r d i n a t e d  structure  t o the n o n - l i n e a r  d i m e t h y l t i n group through two of i t s oxygen atoms, making atom t e t r a h e d r a l . methyltin  the t i n  A polymeric s t r u c t u r e s i m i l a r to that of t r i -  perchlorate  (27) i s t h e r e f o r e proposed, the CrO^ groups  a c t i n g as b r i d g i n g groups between monomeric s t r u c t u r e c o n t a i n i n g  non-linear  a bidentate  (CHg^Sn u n i t s . A  chromate group i s  a l s o p o s s i b l e , although l e s s l i k e l y i n view of the i n s o l u b i l i t y and n o n - v o l a t i l i t y of t h i s compound. The u l t r a v i o l e t and v i s i b l e d i f f u s e r e f l e c t a n c e spectrum of a powdered  sample of the d i m e t h y l t i n chromate and s i l v e r  c h l o r i d e mixture was examined.  Two a b s o r p t i o n  maxima a t 280 and -380 nj// were observed. to that obtained reported 4.4  This r e s u l t i s s i m i l a r  Co(NHg)gCrO^.  Sulphate —  (CHo )2SnS0^ 4 o  n  In t h i s i n v e s t i g a t i o n the p r e p a r a t i o n sulphate  showing  f o r b i s ( t r i m e t h y l t i n ) chromate as w e l l as  (100) f o r  D i m e t h y*l t i n —  bands  of d i m e t h y l t i n  was attempted i n d i f f e r e n t s o l v e n t s , and the i n f r a r e d  s p e c t r a of the p r o d u c t s were examined.  Some a d d i t i o n compounds  75 of d i m e t h y l t i n sulphate infrared  spectroscopy.  The and  metathetical  s i l v e r sulphate  was obtained  absorption  spectra  showed a b s o r p t i o n  r e a c t i o n between d i m e t h y l t i n d i c h l o r i d e  i n aqueous s o l u t i o n r e s u l t e d i n the formation  of d i m e t h y l t i n sulphate sulphate  were a l s o prepared and examined by  and s i l v e r c h l o r i d e , and d i m e t h y l t i n  as a non-hygroscopic s o l i d .  (obtained  on samples made as mulls i n n u j o l  bands a t 1238 (w,sp), 1095 (vs,b),  670  (m,sp), and 600 (s,sp) c m .  600  cm  -1  1238  - 1  The i n f r a r e d  805(s),  The bands a t 1238, 805 and  a r e due to the d i m e t h y l t i n group and can be assigned as  cm , C-H asymmetric s t r e t c h ; 805 c m , CHg rock; 1  -1  cm" , Sn-C asymmetric s t r e t c h . v 21  to the V g mode of the SO^ the  mode of the SO4  of the  The band a t 1095 c m l  i o n and the 670 c m  _i  - 1  corresponds  band i s due t o  i o n . I t may be noted that the frequency  mode i n d i m e t h y l t i n sulphate  i s considerably  towards higher wave number as compared w i t h the value observed i n i o n i c s u l p h a t e s . sulphate  and 600  Nevertheless,  shifted (^613 c m ) -1  the symmetry of the  group i n t h i s compound i s t e t r a h e d r a l .  The d i m e t h y l t i n  group shows only one Sn-C s t r e t c h i n g mode and i t s frequency i s almost the same as observed f o r d i m e t h y l t i n d i f l u o r i d e . 2+ spectrum can be i n t e r p r e t e d i n terms of ( C T ^ ^ S n  The 2—  and SO^  ions.  However, i t can be i n t e r p r e t e d e q u a l l y w e l l i n terms of a p o l y - : meric s t u r c t u r e , i n which every oxygen of the sulphate coordinated  to a t i n atom making the t i n atom s i x  as shown below:  group i s  coordinate,  76 In such a s t r u c t u r e , the T  d  symmetry of the sulphate  l i n e a r i t y of the d i m e t h y l t i n groups are preserved. dimensional and  structure containing  t e t r a h e d r a l sulphate The  and  polymeric  and methanol.  which was  linear  three  dimethyltin  groups i s a l s o p o s s i b l e .  a l s o c a r r i e d out i n acetone,  In both acetone and  acetonitrile  a c e t o n i t r i l e , the r e a c t i o n  a mixture of s i l v e r c h l o r i d e and  dimethyltin  sulphate,  c h a r a c t e r i z e d i n each case by the r e s u l t s of X-ray  powder photographs and mixtures. out  A  and  m e t a t h e t i c a l r e a c t i o n between d i m e t h y l t i n d i c h l o r i d e  s i l v e r s u l p h a t e was  product was  groups  the i n f r a r e d a b s o r p t i o n  spectra, of  However, when the m e t a t h e t i c a l r e a c t i o n was  i n methanol, a mixture of s i l v e r c h l o r i d e and  adduct of d i m e t h y l t i n sulphate was adduct of d i m e t h y l t i n sulphate  obtained.  the  carried  a methanol  Though the methanol  c o u l d not be i s o l a t e d f r e e from  s i l v e r c h l o r i d e on account of i t s i n s o l u b i l i t y i n a range of s o l v e n t s , except water, i t s formation  and presence i n the mix-  t u r e i s demonstrated by i n f r a r e d s p e c t r o s c o p i c evidence. i n f r a r e d absorption very  spectrum of the mixture was  found to  be  d i f f e r e n t from that observed f o r d i m e t h y l t i n s u l p h a t e .  i n f r a r e d absorption t i e s and  bands, together  with  the r e l a t i v e  assignments, are l i s t e d i n Table 4.4a  the spectrum i s shown i n F i g u r e s 4.4a  and 4.4b.  curves r e f e r to the spectrum of the anhydrous Absorption at 1210,  bands due  1175,  absorption  1065,  to the sulphate 995,  665,  606,  bands a s s o c i a t e d with  at 2960, (G-H (C-H  The  and  3  intensi-  a p o r t i o n of  (The  broken  sulphate.)  group i n the mixture appear 585  and 475  em . -1  The  the d i m e t h y l t i n group appear  s t r e t c h ) ; 1415,(C-H asymmetric bend);  symmetric bend); 795,(CH  The  r o c k ) ; and  595,  (Sn-C  1230, asymmetric  I  1200  I  I  1100  I  I  1000  I  1  9 0 0  I  I  8 0 0  Cm  1  00  79 TABLE The  I n f r a r e d A b s o r p t i o n Spectrum  Sulphate-Methanol Adduct  4.4a of the Mixture of D i m e t h y l t i n  and S i l v e r  Chloride T  Frequency  (cm" ) 1  Relative Intensity  3110  m  0-H S t r .  2960  vw  C-H s t r .  2800  V  1455  w  1415  vw  1230  C-H  asym.bend  m  C-H  sym.bend  1210  m  S0  asym.str.,(^6  1175  s  S0  1140  sh  1065  s  SOg asym.str„(0g  995  s  S0<2 sym. s t r  795  s  CHg  rock  655  s  S0  4  rock,(0 )  606  s  S0  2  bend, (\)g)  595  s  Sn-C  585  sh  S0  4  rock, (vg.)  475  m  S0  2  bend , (0 )  m = medium;  s = strong;  sh = shoulder;  * denotes the oxygen atoms (of the S 0 The assignments f o r the S 0 C  2 v  Assignment  symmetry.  4  4  2  2  sym.str.,(0].)  .,(0 ) 2  7  asym.str.  v = very;  4  w = weak.  group) i n v o l v e d i n bonding.  group have been suggested  assuming  80stretch) cm .  There i s no band which can be a t t r i b u t e d to the  -1  Sn-C  symmetric  stretch.  are due to methanol.  The bands at 3110,  The*. 0-H  i n 0-H  -1  s u g g e s t i n g t h a t the  i s c o o r d i n a t e d to d i m e t h y l t i n s u l p h a t e . A S i m i l a r  frequency occurs i n  cm  s t r e t c h i n g frequency has been con-  s i d e r a b l y lowered as compared w i t h methanol, methanol  2800, and 1455  the methanol  s u l p h a t e , as d i s c u s s e d e a r l i e r .  shift;  adduct of b i s ( t r i m e t h y l t i n )  The s u l p h a t e p o r t i o n of the  spectrum i s completely c o n s i s t e n t w i t h the presence of c o o r d i n a t e d 2sulphato group of C v 1  2  symmetry and i n d i c a t e s t h a t no f r e e  i o n s are p r e s e n t i n the mixture.  SO^  The e n t i r e spectrum of the mix-  t u r e s t r o n g l y suggests t h a t a methanol  adduct;of d i m e t h y l t i n  s u l p h a t e i s present and t h a t , i n t h i s adduct, both the methanol and s u l p h a t e group are c o o r d i n a t e d to the l i n e a r group.  dimethyltin  However, i n view of the u n c e r t a i n t y i n the number of  methanol molecules present i n the adduct, no c o n c l u s i o n s can be drawn about i t s d e t a i l e d s t e r e o c h e m i s t r y . The methanol  adduct of d i m e t h y l t i n s u l p h a t e was h y d r o l y s e d  on exposing to a i r , as shown by changes However, a sample show any changes  in i t s infrared  of the mixture kept i n the dry box d i d not i n i n f r a r e d spectrum.  S i m i l a r l y , a sample  the mixture d i d not show any change i n i n f r a r e d spectrum being pumped f o r s e v e r a l hours at room temperature. when the mixture was  of  after  However,  heated under vacuum at 100° f o r about  hours, the methanol was  four  completely removed and the i n f r a r e d  spectrum of the heated s o l i d was t i n sulphate.  spectrum.  i d e n t i c a l to t h a t of d i m e t h y l -  Thus i t i s e v i d e n t t h a t , during t h i s treatment,  the c o o r d i n a t e d methanol s u l p h a t e i s formed.  i s l o s t from the adduct and  dimethyltin  81: D i m e t h y l t i n sulphate a l s o formed 1:1 w i t h p y r i d i n e and dimethyl s u l p h o x i d e .  a d d i t i o n compounds  These a d d i t i o n compounds  are s t a b l e and do not h y d r o l y s e i n a i r .  A 1:2  a d d i t i o n compound  of d i m e t h y l t i n d i c h l o r i d e w i t h p y r i d i n e has been d e s c r i b e d (33). A s i m i l a r a d d i t i o n compound of d i m e t h y l t i n d i c h l o r i d e was with dimethyl s u l p h o x i d e .  obtained  A comparison of the i n f r a r e d s p e c t r a  of these compounds i s made below. The  i n f r a r e d s p e c t r a of p y r i d i n e complexes and p y r i d i n i u m  s a l t s have been s t u d i e d (110). t i n g u i s h e d by the presence cm" ; 1  by a s h i f t  Coordinated p y r i d i n e can be  of a weak band between 1250  i n the s t r o n g 1578  by s h i f t s of the 601  and 403  respectively  The  (110).  cm"  1  cm"  1  band to 1600  bands to 625  dis-  and  1235  cm" ;  and  1  and 420  cm"  1  i n f r a r e d a b s o r p t i o n s p e c t r a of both  d i m e t h y l t i n s u l p h a t e - p y r i d i n e monoadduct and d i m e t h y l t i n d i c h l o r i d e - p y r i d i r i e diadduct are recorded, together with r e l a t i v e i n t e n s i t i e s of the a b s o r p t i o n bands and assignments,  i n Table 4.4b.  shown i n F i g u r e 4.4c; and curves  (b) and  curve  the  suggested  A p o r t i o n of each spectrum  is  (a) r e f e r s to the d i c h l o r i d e  (c) r e f e r to the sulphate adduct.  adduct  The  pyri-  dine a b s o r p t i o n bands i n both the compounds occur at almost  the  same f r e q u e n c i e s and are i n agreement w i t h the p y r i d i n e a b s o r p t i o n bands r e p o r t e d f o r other p y r i d i n e complexes. From a comparison of the spectrum  of the d i m e t h y l t i n s u l p h a t e  adduct w i t h t h a t of the d i m e t h y l t i n d i c h l o r i d e adduct, sulphate a b s o r p t i o n bands i n the d i m e t h y l t i n s u l p h a t e can be d i s t i n g u i s h e d unambiguously. c h l o r i d e adduct, bands at 1210,  the adduct  In the d i m e t h y l t i n d i -  there are f o u r s t r o n g very sharp a b s o r p t i o n  1062,  1037  and  1010  cm" , 1  due  to p y r i d i n e .  In  Me SnS0 .Py 2  1200  1000  4  800  600  Frequency (cm" ) 1  400  83 TABLE 4 • 4b I n f r a r e d A b s o r p t i o n iSpectra of P y r i d i n e Adducts of D i m e t h y l t i n Sulphate and D i m e t h y l t i n D i c h l o r i d e  (CH3) SnGl2.2Py (CH ) SnS0 .Py Relative •equency R e l a t i v e Frequency (cm-1) intensity !cm~l) intensity 3  3100 3050 2940  2  2  4  ) ) )  2450 1605  w vw s  3100 3040 2940  ) ) )  w  1605  s  1570  vw  1492  m  1490  s  1450  s  1450  s  1410  w  1360  vw  1360  vw  1245  sh  1245  w  1232 1217 1208  ) ) )  C-H sym. bend 1210  s  1185  w  1160  vw  1200 1160  vw  1090  s  1066  s  1025 1013 992  1062  • s  1037  s  so  2  asym. s t r .pCvg)  so  2  sym. s t r . X v ' i )  *  s sh  C-H s t r .  C-H asym.bend  m  sh  Assignment  1010  2  so  2  asym. s t r .,(^8)  s  m 973  so  vw  sym.  str  .s(') ) 2  84 Table 4.4b continued 950  wv  887  wv  800  s  780  s  765  s  760  s  745  WW  700 690  ) ) )  CHg rock  s  692  s  655  s  637  s  630  s  598  s  560  s  SO. rocking, (v ) 4  7  Sn-C asym.str.  590 576  m  510  vw  465  m  425  m  417  sh  m = medium;  425  s = strong;  * denotes the oxygen atoms  S0  2  bend,(0 )  S0  4  rock,(v- )  S0  2  bend, ( v )  3  9  4  ms  v = very;  w = weak.  (of the SO4 group) i n v o l v e d i n bonding.  The assignments f o r the SO4 group have been made assuming C2v symmetry. No assignments have been made f o r the a b s o r p t i o n bands due to pyridine.  85 the d i m e t h y l t i n sulphate adduct, correspond cm  -1  the bands at 1208,  1066  and  1010  to three of the above f o u r bands w h i l e the band at  i s a p p a r e n t l y masked by a s t r o n g band at 1023  a b s o r p t i o n bands at 1200,  1090,  1025  and 992  cm"  1  cm" .  1037  Thus the  1  i n the spectrum  of d i m e t h y l t i n s u l p h a t e - p y r i d i n e adduct can be a t t r i b u t e d to the sulphate group.  S i m i l a r l y , i n the lower  bands at 655,. 590,  576  and 465  cm"  are due  1  As regards the a b s o r p t i o n bands due bands at 598 to the Sn-C  and  800  cm"  1  corresponding  560  and 780  cm"  to the sulphate group.  i n the s u l p h a t e adduct can be  r o c k i n g modes r e s p e c t i v e l y .  In both compounds, only the  asymmetric s t r e t c h i n g frequency  appears.  T h e r e f o r e the  t i n group i s apparently l i n e a r i n both compounds. very weak a b s o r p t i o n band at 510 may  assigned  f r e q u e n c i e s i n the d i c h l o r i d e adduct occur at respectively.  1  r e g i o n , the  to the d i m e t h y l t i n group, the  asymmetric s t r e t c h , and CH^  The  frequency  e i t h e r be due  cm  -1  Sn-C  dimethyl-  There i s a  i n the s u l p h a t e adduct, i t  to a s l i g h t d e v i a t i o n from l i n e a r i t y of the  (CHg^Sn group, or more l i k e l y  to a f o r b i d d e n band, because of i t s  very weak i n t e n s i t y . Thus the i n f r a r e d spectrum of d i m e t h y l t i n s u l p h a t e - p y r i d i n e monoadduct again i n d i c a t e s t h a t the s u l p h a t e group i s c o o r d i n a t e d to the d i m e t h y l t i n group and or a b r i d g i n g l i g a n d .  The  that i t a c t s e i t h e r as a b i d e n t a t e  C^  v  symmetry of the s u l p h a t e group  the l i n e a r i t y of the d i m e t h y l t i n group suggest i s f i v e c o o r d i n a t e i n t h i s compound. o r d i n a t i o n of the t i n atom, two be suggested.  One  t h a t the t i n atom  C o n s i d e r i n g the f i v e  co-  s t e r e o c h e m i c a l c o n f i g u r a t i o n s can  i n v o l v e s a t r i g o n a l b i p y r a m i d a l arrangement  c o n t a i n i n g the two methyl groups i n the a p i c a l p o s i t i o n s ; p y r i d i n e molecule  and two  and  the  oxygen atoms of the sulphate group  being c o o r d i n a t e d to the c e n t r a l t i n atom i n the three  axial  1*6  positions. square  The other p o s s i b l e c o n f i g u r a t i o n can be that of a  pyramid i n which the l i n e a r d i m e t h y l t i n group i s coor-  d i n a t e d t o two oxygen atoms i n t r a n s p o s i t i o n s ; the p y r i d i n e molecule  being c o o r d i n a t e d  to the t i n atom a t the apex. However,  i t must be c o n s i d e r e d that a t r i g o n a l b i p y r a m i d a l c o n f i g u r a t i o n f o r t h i s compound i n v o l v e s c o o r d i n a t e d groups i n the a x i a l  plane,  w h i l e the c o v a l e n t l y bonded methyl groups are p l a c e d at the apical positions. The  assignments f o r v i b r a t i o n a l f r e q u e n c i e s of dimethyl  sulphoxide frequency  T h e r e f o r e such a c o n f i g u r a t i o n i s most u n l i k e l y .  (DMSG) have been made (111) and the S-0 s t r e t c h i n g has been w e l l e s t a b l i s h e d .  s t r o n g a b s o r p t i o n band at 1057 c m another and  I t g i v e s r i s e to a very (in a liquid film).  - 1  There i s  very sharp, much l e s s i n t e n s e a b s o r p t i o n at 950 c m , -1  a weaker, broad peak at 915 cm"- , both of them being 1  to CHg rock.  DMSO has an unshared p a i r of e l e c t r o n s on both  sulphur and oxygen, and can c o o r d i n a t e through or through  the oxygen atom.  the sulphur atom  As Cotton and F r a n c i s (112) have  p o i n t e d out, the S-0 bond i n s u l p h o x i d e s has at l e a s t double  assigned  partial  bond c h a r a c t e r which may be c o n s i d e r e d t o r e s u l t from the  s u p e r p o s i t i o n of pTT" -d"TT sigma bond.  bonding from 0 t o S upon the S-0  T h e r e f o r e c o o r d i n a t i o n through  should decrease  pTT  the oxygen atom  - dlT" back bonding and hence lower the  S-0 bond order and the s t r e t c h i n g frequency. c o o r d i n a t i o n v i a sulphur would be expected  to i n c r e a s e  back bonding and thus r a i s e the S-0 s t r e t c h i n g Cotton, F r a n c i s , and Horrocks  On the other hand,  pTT-dTT"*  frequency.  (113) have r e p o r t e d t h a t , i n  s u l p h o x i d e s , the oxygen atom i s the donor i n the m a j o r i t y of the metal  complexes s t u d i e d .  In such cases, the S-0 s t r e t c h  1  a? i s s h i f t e d t o lower f r e q u e n c i e s .  With an acceptor such as P t ( I I )  or P d ( I I ) , sulphur seems to be the donor atom and the S-0 s t r e t c h i n g frequency  i s higher i n the complex than  i n the f r e e l i g a n d .  Though there i s h a r d l y any doubt that i n DMSO complexes such as Co(DMSO) CoCl 6  and SnCl (DMSO) ,  4  4  the donor atom,  2  the oxygen atom o f DMSO a c t s as  the assignments of the v i b r a t i o n a l  have been d i s p u t e d .  In Co(DMSO)gCoCl ,  Cotton,  4  frequencies  Francis,and  Horrocks (113) have a s s i g n e d the S-0 s t r e t c h i n g mode t o a very strong band a t 950 c m  - 1  i n the 1000 cm"-'- r e g i o n .  and the CH3 r o c k i n g mode to a s t r o n g band Contrary  and Meek (114) have assigned and  1000 c m  - 1  t o these assignments, Drago  the 950 c m  - 1  band t o the CH3 rock  band t o the S-0 s t r e t c h .  The i n f r a r e d a b s o r p t i o n bands of DMSO adducts of d i m e t h y l t i n s u l p h a t e and d i m e t h y l t i n d i c h l o r i d e a r e l i s t e d , r e l a t i v e i n t e n s i t i e s and suggested  together w i t h  their  assignments i n Table 4.4c, and  a p o r t i o n of the spectrum of the s u l p h a t e adduct i s shown i n F i g u r e 4.4d. occur  The a b s o r p t i o n bands due to DMSO i n both  at almost  the ^ame f r e q u e n c i e s .  compounds  In a d d i t i o n t o the DMSO  bands which can be r e c o g n i z e d e a s i l y , the main f e a t u r e s of the spectrum of the d i c h l o r i d e adduct are the a b s o r p t i o n bands a t 788, 573, 508 (vw), 415, 340, 312 and 255 c m . -1  788, 573, and 415 cm" can be assigned 1  group],  1  most probably  1  [in(CH3)2  The very weak band a t 508 may be an overtone of  the 255 cm" band.  cm"  t o CH3 rock  the Sn-C asymmetric s t r e t c h and Sn-0 asymmetric s t r e t c h  respectively.  bration.  The bands a t  Of the three bands at 340, 312 and 255 c m , -1  only one band i s due to the Sn-Cl s t r e t c h i n g v i -  In DMSO, there are a b s o r p t i o n bands a t 382 and 333  which have been a s s i g n e d  (111) t o the symmetric and asymmetric  Frequency (cm ) -1  oo oo  89 TABLE 4.4c I n f r a r e d A b s o r p t i o n Spectra  of DMSO Adducts of  Sulphate and D i m e t h y l t i n (CH ) SnS0 .DMSO 3  2  Frequency (cm" ) 1  3040 2960  Dichloride  CH ) SnCl .2DMS0  4  3  Relative intensity w w  Dimethyltin  J )  2  2  Frequency (cm ) -1  Relative intensity  3030 2930  w w  1455  sh  1457  sh  1443  ms  1430  s  1420  w  1410  m  1365  vw ms  1323  m  1320  1300  w  1300 1295  1225  m  1202 1193  s  1080  s, sh  1045  s  ) )  Assignment C-H s t r e t c h  m  1034  s  995  s  1000  m  989  m  945  s  943  s  915  w  »910  m  805  s  788  s  783  sh  727  m  720  m  S0  2  asym. s t r . , ( v ^ )  S0  2  sym. s t r . ,  S0  2  asym.str.,  S0  2  (v ) n  sym.str.,(v )  vHS-O) (DMSO)  CH- rock  2  90 Table 4.4c continued  655  s  597  s  590  s  SO4 573  508  s  m  437  s  415  s  330  m  340  s  312  s  255  m  m  m = medium;  s = strong;  Sn-C asym.str. S0  2  bend ,(v )  S0  2  bend ,(v )  3  vw  468  255  rock  sh = shoulder;  4  Sn-0 s t r e t c h  Sn-Cl s t r .  v = very;  w = weak;  * denotes the oxygen atoms (of the SO4 group) i n v o l v e d i n bonding. The assignments f o r the SO4 group have been made assuming C symmetry  as i n C I O 4 .  2 v  No assignments have been made f o r DMSO  a b s o r p t i o n bands except the vXS-O).  913 C-S-0  deformation.  These bands a r e s h i f t e d t o 330 and 255 c m  i n the d i m e t h y l t i n sulphate  adduct.  Therefore  i t i s suggested  that i n the d i m e t h y l t i n d i c h l o r i d e adduct, the 312 c m a s s o c i a t e d with 340  and 255 c m  - 1  - 1  band i s  the Sn-Cl s t r e t c h i n g v i b r a t i o n and the bands a t - 1  a r e due t o the DMSO l i g a n d .  frequency i s i n d i c a t e d f o r each o f the Sn-C,  Thus only one Sn-0 and Sn-Cl  s t r e t c h i n g v i b r a t i o n s i n the i n f r a r e d spectrum of the d i m e t h y l t i n dichloride-DMSO diadduct. trans octahedral regards  In view of these s p e c t r a l f e a t u r e s , a  s t r u c t u r e i s suggested f o r t h i s compound.  the assignments f o r the S-0 s t r e t c h i n g frequency,  are two strong bands of almost equal and  As there  i n t e n s i t y at 995 and 943 cm"  i t i s not p o s s i b l e t o d i s t i n g u i s h which of the two bands c o r -  responds t o the S-0 s t r e t c h .  However, i n d i m e t h y l t i n  sulphate-  DMSO adduct the most i n t e n s e band due t o DMSO appears at 945 cm" and  1  t h e r e f o r e t h i s band i s assigned  t o the S-0 s t r e t c h .  1  On t h i s  b a s i s , the 943 cm" band i n the d i c h l o r i d e adduct can be assigned 1  to the S-0 s t r e t c h and the 995 cm~l The  band to CH  1045,  rock  (DMSO).  main f e a t u r e s of the i n f r a r e d spectrum of the dimethyl-  t i n sulphate-DMSO adduct a r e the a b s o r p t i o n 1080,  3  989, 655, 590 and 468 cm" . 1  of the spectrum of the s u l p h a t e  bands a t 1207-1193,  Comparing the DMSO p a r t  adduct with  that of the d i c h l o r i d e  adduct, i t can be seen t h a t no bands due t o DMSO occur regions sulphate  except a band a t 1034 c m band at 1045 cm" . 1  - 1  i n these  which i s masked by the strong  The sulphate  absorption  bands i n  the d i m e t h y l t i n sulphate-DMSO adduct are almost i d e n t i c a l t o those observed f o r the d i m e t h y l t i n s u l p h a t e - p y r i d i n e  adduct.  Thus  the i n f r a r e d spectrum of d i m e t h y l t i n sulphate-DMSO adduct a l s o shows c o o r d i n a t i o n between the sulphate  and the d i m e t h y l t i n groups.  92 The  Sn-C and Sn-0 v i b r a t i o n s i n the d i m e t h y l t i n sulphate-DMSO  adduct appear a t 597 and 437 cm" r e s p e c t i v e l y .  I t may be noted  1  that only the Sn-C asymmetric s t r e t c h i n g and Sn-0 asymmetric s t r e t c h i n g v i b r a t i o n s appear. gested  The s t e r e o c h e m i c a l  for dimethyltin sulphate-pyridine  f e a t u r e s sug-  adduct can a l s o be  suggested f o r the DMSO adduct because o f the almost spectrum of the d i m e t h y l t i n and the sulphate  identical  groups i n both  compounds. •'• The  c o o r d i n a t i o n by the sulphate  groups i n the adducts  of d i m e t h y l t i n sulphate with methanol, p y r i d i n e and DMSO as shown by the above s p e c t r o s c o p i c  r e s u l t s , i s not c o n s i s t e n t  an i o n i c c o n s t i t u t i o n o f d i m e t h y l t i n sulphate coordinated  with  and suggests a  s t r u c t u r e f o r t h i s compound.  Proton n.m.r. s t u d i e s on d i m e t h y l t i n ( I V ) r e c e n t l y been used to estimate  compounds have  the percentage s - c h a r a c t e r  i n the  t i n o r b i t a l s d i r e c t e d t o the methyl groups, by the measurement of the 7sn-CH- or ^^Sn-CHg c o u p l i n g constants. 11  constant  data r e p o r t e d  (50)  Coupling  f o r some d i m e t h y l t i n compounds cXYfc  shown i n Table 4.4d.  TABLE 4.4d Sn-GH.3 Coupling' Constants of Some D i m e t h y l t i n (IV) D e r i v a t i v e s Compound  Solvent  J( Sn-CH ) c.p.s. 1 1 7  3  J(  Sn~CH ) c.p.s.  1 1 9  3  (CH ). Sn(C104)2  H 0  102  107  (CH ) Sn(N0 )  H 0  104.3  108. 7  3  2  2  3  2  (CH ) SnCl 3  2  3  2  2  HC1  2  (CH )2Sn(C5H70 ) 3  2  (CH ) SnCl 3  2  2  (CH ) Sa(OCH ) 3  2  3  2  2  92.5  97.5  CDC1  3  95.0  99.3  CDC1  3  66.5  69.8  71.3  74.4  cci  4  93 Raman and i n f r a r e d s t u d i e s on aqueous s o l u t i o n s of dimethylt i n compounds (21) c a t i o n s with coordinated  a l i n e a r C-Sn-C s k e l e t o n and four water molecules i n the e q u a t o r i a l plane.  dimethyltin(IV), and  i n d i c a t e the presence of the aquodimethyltin  (CHg) gSn^sHyOg) 2  i n f r a r e d and proton  with  i  Bis(acetylacetonato) s  also considered,  from Raman  n.m.r. s t u d i e s (50), t o be o c t a h e d r a l  t r a n s methyl groups.  The c o n f i g u r a t i o n of the l a s t two  compounds l i s t e d above, i . e . d i m e t h y l t i n d i c h l o r i d e (4) dimethoxy d i m e t h y l t i n (115), chloroform constant  solution.  values  ent from those  and  i s r e p o r t e d to be t e t r a h e d r a l i n  As seen from Table 4.4d,  the c o u p l i n g  f o r the o c t a h e d r a l s p e c i e s are markedly  differ-  of t e t r a h e d r a l s p e c i e s .  In t h i s i n v e s t i g a t i o n the proton dimethyltin sulphate  n.m.r. s p e c t r a of  as w e l l as i t s adducts w i t h  p y r i d i n e and  DMSO, and d i m e t h y l t i n chloride-DMSO adduct were determined. The values o f the c o u p l i n g c o n s t a n t s  obtained  are shown i n Table  4. 4e. TABLE 4.4e Sn-CHg Coupling  Constants of D i m e t h y l t i n Sulphate,  Sulphate-Pyridine,  Dimethyltin  D i m e t h y l t i n Sulphate-DMSO, and D i m e t h y l t i n Dichloride-2DMSO  Compound  Solvent  J(  1 1 7  Sn-CH ) 3  c.p.s.  J(  1 1 9  Sn-CH ) 3  c.p.s.  (CH ) SnS04  H 0  104.5  109.5  (CH ) SnS04.Py  H 0  91.0  95.0  (CH ) SnS0 -DMS0  H 0  104.5  109.5  (CH ) Sn.Cl -2DMSO (CH )2SnCl  H 0 CHC1  102.0 82.5  107.0 86.5  3  2  3  2  2  3  2  3  2  2  4  2  2  2  , 2 D M S O  3  2  3  Note: D i m e t h y l t i n s u l p h a t e and i t s a d d i t i o n compounds with p y r i d i n e and DMSO a r e not s o l u b l e i n o r g a n i c s o l v e n t s such as CHC1 or C C l ^ . 3  94 The c o u p l i n g sulphate,  constant  values  f o r aqueous s o l u t i o n s of d i m e t h y l t i n  the d i m e t h y l t i n sulphate-DMSO adduct and the  dimethyl-  t i n dichloride-DMSO adduct are i n good agreement with the values reported  for dimethyltin perchlorate  and n i t r a t e , and i t can be  i n f e r r e d that l i k e d i m e t h y l t i n p e r c h l o r a t e  and n i t r a t e ,  these  compounds are a l s o d i s s o c i a t e d i n aqueous s o l u t i o n to form s i x coordinate constants but  aquodimethyltin  cations.  The values  of the d i m e t h y l t i n s u l p h a t e - p y r i d i n e  they are of the same order  constants  adduct are lower  as those r e p o r t e d  for dimethyltin dichloride i n hydrochloric coupling  f o r the c o u p l i n g  i n Table 4.4d  acid solution.  The  f o r d i m e t h y l t i n dichloride-DMSO adduct are  lower compared w i t h those f o r b i s (acetylacetonato)dimethyltin (IV) . According and  to the l i n e a r r e l a t i o n  percentage s - c h a r a c t e r  groups, s - c h a r a c t e r  (12) between c o u p l i n g  constant  i n the t i n o r b i t a l s d i r e c t e d to methyl  i n the Sn-CH3 bond i s about 40 percent i n  d i m e t h y l t i n dichloride-DMSO adduct and 46 percent (acetylacetonato)dimethyltin(IV).  in bis-  The Sn-0 s t r e t c h i n g frequen-  c i e s i n these two.compounds occur at 415 and 400 c m  res-  -1  Hie.  p e c t i v e l y , i n d i c a t i n g greater  Sn-0 bond s t r e n g t h  i n dimethyltin A  dichloride-DMSO adduct.  However,  the Sn-C s t r e t c h i n g  i n the two compounds occur at 573 and 570 cm" i n d i c a t i n g very  little  frequencies  respectively,  1  change i n the Sn-C bond s t r e n g t h  i n the  two compounds. 4.5  Dimethyltin  Bis(tetrafluoroborate)  (CH ) Sn(BF ) 3  2  4  2  The t e t r a h e d r a l symmetry(T )of the t e t r a f l u o r o b o r a t e i o n d  has been e s t a b l i s h e d by i n f r a r e d and Raman s t u d i e s However,  the f r e q u e n c i e s  (116, 117).  of the fundamental v i b r a t i o n s of the  95  t e t r a f l u o r o b o r a t e i o n r e p o r t e d by two groups of workers (116, 117)  are s l i g h t l y d i f f e r e n t and both s e t s of values are l i s t e d  i n Table 4.5a. TABLE 4.5a V i b r a t i o n a l Frequencies Vibrational mode  \  of  ^2  (Al)  (E)  (R)  (R)  BF^  -  Ion (Point Group T^)  ^3  ^4 (F )  (F > (R,I.R)  2  2  (R,I.R)  Frequency (cm-1) (116)  786  369  (117)  769  353  (R = :  The  1100  541  984,1016  Raman a c t i v e ; I.R = I n f r a r e d a c t i v e )  d e t a i l e d i n f r a r e d s p e c t r a of some i o n i c  borates  have been s t u d i e d (118-120).  borates  g i v e many a b s o r p t i o n bands other  the most prominent f e a t u r e being a doublet mode.  524  Crystalline  tetrafluorotetrafluoro-  than the fundamentals,  the s p l i t t i n g of the v* mode, 3  f o r ^ v ^ mode and the appearance of the f o r b i d d e n v-^  Cote and Thompson (118) c o n s i d e r e d  a r e s u l t of the lowering the c r y s t a l .  this splitting  t o be  of the s i t e symmetry of the anion i n  From an i n f r a r e d s p e c t r o s c o p i c study  of potassium  t e t r a f l u o r o b o r a t e c o n t a i n i n g an e n r i c h e d i s o t o p e r a t i o of (10B : B), N  Greenwood (120) showed t h a t the s p l i t t i n g and  broadening of peaks i n potassium t e t r a f l u o r o b o r a t e i s due to a combination of the lowering  of s i t e symmetry and the presence of  the two i s o t o p e s of boron.  However, the i n f r a r e d spectrum (43)  of t r i m e t h y l t i n t e t r a f l u o r o b o r a t e i s c o n s i d e r a b l y d i f f e r e n t  from  96 the i n f r a r e d s p e c t r a  of the i o n i c t e t r a f l u o r o b o r a t e s .  ionic tetrafluoroborates, broad band i n the r e g i o n  While i n  the Vg mode appears as a very 1050-1075 c m  - 1  strong  showing s p l i t t i n g  i n the  form of f i n e s t r u c t u r e , i n t r i m e t h y l t i n t e t r a f l u o r o b o r a t e ,  this  mode i s c l e a r l y r e s o l v e d  1070,  and  930 cm" .  S i m i l a r l y , the  1  "forbidden"  i n t o three  strong  bands at 1170,  mode appears only  t r a n s i t i o n a t 771 c m  - 1  i n the s p e c t r a  as a weak of i o n i c  t e t r a f l u o r o b o r a t . e s , but i n the spectrum of t r i m e t h y l t i n t e t r a f luoroborate,  the A ) J mode shows a strong  absorption  a t 746 c m . -1  Another important f e a t u r e of the spectrum of t r i m e t h y l t i n tetrafluoroborate These f e a t u r e s fluoroborate the  i s the appearance of a broad band a t 446 c m . -1  of the i n f r a r e d spectrum of t r i m e t h y l t i n t e t r a -  are c o n s i s t e n t with the suggested C y symmetry of 2  t e t r a f l u o r o b o r a t e group and i n d i c a t e strong  between the t e t r a f l u o r o b o r a t e Coordination (86)  interaction  and t r i m e t h y l t i n groups.  by the t e t r a f l u o r o b o r a t e group has a l s o been  reported  in Ni(3,5-lutidine) (BF ) . 4  The  i n f r a r e d spectra  fluoroborate-(methyl i n f r a r e d spectra  4  2  (121) of Mn(II) and Zn(II) t e t r a -  cyanide) complexes a l s o d i f f e r from the  of s i l v e r and potassium  tetrafluoroborates.  Attempts were made to prepare d i m e t h y l t i n b i s ( t e t r a f l u o r o borate) by the m e t a t h e t i c a l d i c h l o r i d e and s i l v e r  r e a c t i o n between  tetrafluoroborate.  dimethyltin  However, the m e t a t h e t i c a l  r e a c t i o n , c a r r i e d out i n methanol as w e l l as i n ether,  resulted  i n the f o r m a t i o n of d i m e t h y l t i n b i s ( t e t r a f l u o r o b o r a t e ) , dimethyltin The  d i f l u o r i d e , boron t r i f l u o r i d e and s i l v e r  evolution  chloride.  of boron t r i f l u o r i d e was confirmed by the formation  of boron t r i f l u o r i d e - a m i n e adducts.  When the m e t a t h e t i c a l  97 r e a c t i o n was done i n methanol, the q u a n t i t a t i v e amount of s i l v e r c h l o r i d e was p r e c i p i t a t e d . the f i l t r a t e , The  Upon removal of the methanol from  an extremely hygroscopic  white s o l i d was  obtained.  i n f r a r e d spectrum, a n a l y t i c a l r e s u l t s and the X-ray powder  photographs of the s o l i d showed i t t o be a mixture of d i m e t h y l t i n b i s ( t e t r a f l u o r o b o r a t e ) and d i m e t h y l t i n d i f l u o r i d e . tical  results indicate  percent  The  that the mixture contained  analy-  n e a r l y 46  d i m e t h y l t i n b i s ( t e t r a f l u o r o b o r a t e ) and 54 percent of  dimethyltin  difluoride.  The mixture d i d not show any change,  e i t h e r s p e c t r o s c o p i c a l l y or a n a l y t i c a l l y , when i t was heated to 60 - 70° under vacuum f o r about s i x hours.  Therefore  concluded that the decomposition of d i m e t h y l t i n fluoroborate)  bis(tetra-  i s not due t o i t s thermal i n s t a b i l i t y  experimental conditions.  '  under  Q u a n t i t a t i v e p r e c i p i t a t i o n of s i l v e r  c h l o r i d e shows that the m e t a t h e t i c a l to c o m p l e t i o n , i . e .  i t is  r e a c t i o n i n methanol goes  * CH 0H 3  (CH )2SnCl 3  2  + 2AgBF  ^  4  (CH3) Si? 2  (Solvated)  + 2BF ~ 4  + 2AgCl  The  formation  (1)  of d i m e t h y l t i n d i f l u o r i d e can be e x p l a i n e d  i n the  f o l l o w i n g manner: o-f  (CH ) Sn 3  The  2  (solvated)+ 2 B F  formation  —CH3OH  (CH ) SnF  4  of d i m e t h y l t i n  3  2  2  + 2BF  3  . .(2)  d i f l u o r i d e upon removal of the s o l -  vent a l s o i n d i c a t e s that d i m e t h y l t i n b i s ( t e t r a f l u o r o b o r a t e ) i s s t a b l e i n methanol but p a r t i a l l y solvent  according  decomposes upon removal of the  to equation ( 2 ) .  These r e s u l t s i n d i c a t e a very strong i n t e r a c t i o n between (CHg^Sn and B F 4 groups i n the s o l i d s t a t e , apparently t h i s p a r t i a l decomposition.  causing  T h i s i n t e r a c t i o n i s f u r t h e r sup-  ported by the s p e c t r o s c o p i c r e s u l t s . between d i m e t h y l t i n d i c h l o r i d e and also.done i n l i q u i d sulphur  The m e t a t h e t i c a l r e a c t i o n  s i l v e r t e t r a f l u o r o b o r a t e was  d i o x i d e but d i m e t h y l t i n b i s  ( t e t r a f l u o r o b o r a t e ) c o u l d not be i s o l a t e d i n the pure form. Although only a s o l i d mixture of d i m e t h y l t i n b i s ( t e t r a f l u o r o b o r a t e ) and  d i m e t h y l t i n d i f l u o r i d e was  obtained,  the  i n f r a r e d spectrum of t h i s mixture shows very i n t e r e s t i n g f e a suggests strong i n t e r a c t i o n between (CH^gSn and B F 4  t u r e s and groups.  The  i n f r a r e d a b s o r p t i o n spectrum obtained  m u l l sample of the s o l i d i n t e n s i t i e s and i n Table 4.5b and  i s recorded  together w i t h  on a n u j o l the  relative  suggested assignments of the a b s o r p t i o n  bands,  and p a r t of the spectrum i s shown i n F i g u r e s  4.5a  4.5b. The  1066,  a b s o r p t i o n bands at 1280,  1047,  1030,  940,  760,  1207,  525-510, 455  1195,  and 410  a t t r i b u t e d to the t e t r a f l u o r o b o r a t e group. the spectrum i s markedly d i f f e r e n t ion.  The  triply  degenerate mode v  1157,  1095,  cm ,  can  -1  It i s evident  be that  from that of the f r e e BF4" of the f r e e i o n i s c l e a r l y  3  r e s o l v e d i n t o three s t r o n g bands at 1157,  1066,  and  940  cm ; -1  the i n f r a r e d f o r b i d d e n mode v^ of the f r e e i o n appears as a s t r o n g sharp band at 760 O4  cm , -1  and  the t r i p l y  degenerate mode  of the f r e e i o n which u s u a l l y appears as a doublet  525  cm"  and  two  1  now  at 536  shows one medium a b s o r p t i o n band at 525-510  s t r o n g bands at 455  and 410  bands which are a l l weak, apparently  cm . -1  The  are due  other  to the  and  em""  1  absorption isotope  1  1200  I  1  1100  I  I  1000  I  I  9 0 0  I  I  800  I  Cm  F I G U R E 4-5b i 600  i  i  5O.o  _J  i 400  i  i 3 0 0  i  i 2 0 0  i _ Cm"  1  o o  TABLE  101  4.5b  I n f r a r e d A b s o r p t i o n Spectrum of The Mixture of D i m e t h y l t i n B i s ( t e t r a f l u o r o b o r a t e ) and D i m e t h y l t i n D i f l u o r i d e Frequency  Assignment  (cm" ) R e l a t i v e I n t e n s i t y 1  1280  w  1225  w,sp  1207  vw  1195  vw  1157  s  1095  sh  1066  s  1047  sh  1030  sh  C-H  sym.  bend  BF  9  asym.str., (v«)  BF  2  sym.str.,(v^)  940  s  BF  2  asym. s t r . , (\)g)  815  s  CH  3  760  s  BF^  604  m  Sn-C  m  BF  455  s, b  (BF )  rock,  410  s, b  (BF )  rock, ( i ) )  375-350  sh  Sn-F  rock sym.  str.^Vg)  asym.str.  525 518  bend,  2  (v^)  510  b = broad; w = weak. The  m = medium;  4  4  s = strong;  s t r . , ^(CHg^SnF^  sh = shoulder; v  assignments f o r the BF^ group have been suggested 4  group of C  2 v  7  9  * denotes the f l u o r i n e atoms i n v o l v e d i n  analogy with C10  (v )  symmetry.  = very;  bonding. by  102 e f f e c t as w e l l as to overtones and at 1225,  815,  and  bend, CH3 rock and Dimethyltin and 373  604  cm  Sn-C  The  a shoulder i n the 375  to the 373  absorption  cm"  1  strong  bands  symmetric  cm l -  the bands due  r e g i o n and  l a r g e l y due  787,  broad band at 410  band of d i m e t h y l t i n  spectrum i s t h e r e f o r e  to the C-H  bands at 1210,  These bands are masked by  -1  The  asymmetric s t r e t c h i n g modes r e s p e c t i v e l y .  bis(tetrafluoroborate). has  can be assigned  -1  d i f l u o r i d e has  cm .  combination bands.  595  to cm"  dimethyltin clearly  1  t h i s i s probably  difluoride.  The  due  observed  to d i m e t h y l t i n b i s ( t e t r a f l u o r o -  borate) . The (43) be  observed spectrum i s almost i d e n t i c a l  f o r t r i m e t h y l t i n t e t r a f l u o r o b o r a t e and  i n t e r p r e t e d i n terms of c o o r d i n a t e d  of Cgy  o r  lower symmetry.  borate a b s o r p t i o n  Due  reported  both s p e c t r a can  only  t e t r a f l u o r o b o r a t e groups  to the presence of t e t r a f l u o r o -  bands i n the 525-510 cm  difficult  to say whether the Sn-C  present.  However, the  Sn-C  to that  1  region,  i t is  symmetric s t r e t c h i s a l s o  asymmetric s t r e t c h i n g v i b r a t i o n i n  t h i s compound occurs at almost the same frequency as t h a t observed in dimethyltin difluoride, sulphate  adducts.  Since  d i m e t h y l t i n sulphate,  and  dimethyltin  the i n f r a r e d s p e c t r a of these compounds  suggest the presence of a l i n e a r d i m e t h y l t i n group, i t i s very likely  that the d i m e t h y l t i n group i s l i n e a r i n d i m e t h y l t i n  bis(tetrafluoroborate).  Considering  the d i m e t h y l t i n group and fluoroborate  groups of C  2 v  the probable l i n e a r i t y  the presence of c o o r d i n a t e d  tetrad,  symmetry, i t can be suggested that i n  d i m e t h y l t i n b i s ( t e t r a f l u o r o b o r a t e ) , four f l u o r i n e atoms are ordinated  of  to the l i n e a r d i m e t h y l t i n group, i n the  plane making the t i n atom s i x  ii'  coordinate.  equatorial  co-  103 Like  trimethyltin tetrafluoroborate,  bis(tetrafluoroborate) changes i n the  i s extremely h y g r o s c o p i c , and  1066,  525-510 c m  940,  760,  bands of the BF^ cm  and  -1  455  and  disappeared and  -1  marked  i n f r a r e d spectrum of the mixture were observed  on exposing i t to a i r f o r a few 1157,  dimethyltin  seconds.  410  cm  and  -1  strong  bands at  the medium band at  the spectrum showed c h a r a c t e r i s t i c  i o n , i . e . a broad strong  a doublet at 535  The  and  520  cm" . 1  band at 1110-1025 The  methyl r o c k i n g  the  Sri-C asymmetric s t r e t c h i n g v i b r a t i o n s were s h i f t e d to  and  575  cm"  respectively.  1  The  marked changes i n the  790  spectrum  upon exposing the mixture to a i r again i n d i c a t e that f r e e ions and  hydrated  (CH^JgSn ' c a t i o n s  are produced by  and  BF^  hydrolysis  of the anhydrous product. 4.6  Dimethyltin An  Hexafluorosilicate  (CHg^SnSiFg  attempt to prepare t h i s d e r i v a t i v e was  not  successful.  N e v e r t h e l e s s , the r e a c t i o n products from the attempted p r e p a r a t i o n are  i n t e r e s t i n g i n that they show a very strong  between (CHg^Sn and between d i m e t h y l t i n  SiFg groups. d i c h l o r i d e and  The • m e t a t h e t i c a l silver  interaction reaction  hexafluorosilicate  i n methanol r e s u l t e d i n instantaneous p r e c i p i t a t i o n of chloride.  However, a f t e r pumping o f f the  temperature) from the d i f l u o r i d e was  The  a c i d i c and  only be  3  2  2  + Ag SiF 2  6  2 2+ ( C H ) S n (solvated)+ SiF,6 3  2  The  c o n t a i n e d s i l i c o n and  interpreted CH 0H 3  (CH ) SnCl  dimethyltin  X-ray powder photographic data.  highly  r e s u l t s can  f i l t e r e d s o l u t i o n , pure  (at room  obtained, as shown by a n a l y t i c a l r e s u l t s ,  red spectrum and methanol was  solvent  silver  according to the  infra-  recovered fluorine. scheme:  104 The metal f l u o r o s i l i c a t e s are s t a b l e , being only about one cent h y d r o l y s e d  i n aqueous s o l u t i o n (59b).  The  per-  decomposition of  2 the SiFg  i o n i n aqueous s o l u t i o n i s considered  f o l l o w i n g manner  to proceed i n the  (122): SiFg "  »  2  SiF  + 2F"  . . . .  (1)  + HgSiOg  . . .  .(2)  4  f o l l o w e d by the r a p i d h y d r o l y s i s SiF The  4  + 3H 0  * 4HF  2  value of the e q u i l i b r i u m constant  reported &H-f  (122) 2-  of SiFg  to be 1x10"  at 20  .  K, The  f o r the 1st r e a c t i o n i s heat of  formation  i o n i n aqueous s o l u t i o n i s -558.5kcal/mole  Although the corresponding different, s t i l l  (123).  values i n methanol s o l u t i o n would be  i t can be seen from these  f i g u r e s that complete  decomposition of d i m e t h y l t i n h e x a f l u o r o s i l i c a t e must i n v o l v e a very s t r o n g i n t e r a c t i o n between (CHg^Sn and 4.7  D i m e t h y l t i n D e r i v a t i v e s of Group Vb Phosphorus, a r s e n i c and  anions  of the formula  metry and  belong  MXg.  SiFg groups.  Hexafluorides  antimony form s t a b l e h e x a f l u o r i d e  These anions  to p o i n t group 0^.  An  have o c t a h e d r a l  sym-  o c t a h e d r a l molecule, or  i o n , should have f i f t e e n normal v i b r a t i o n s d i s t r i b u t e d between s i x v i b r a t i o n a l modes (47c)  as shown i n Table 4.7a.  If the  group i s i n v o l v e d i n c o o r d i n a t i o n then i t s symmetry would lowered.  4  and  Oh,  D  4 h  or C  2 v  symmetry i s shown i n  I f the h e x a f l u o r i d e i o n a c t s as a t r a n s b r i d g i n g  l i g a n d , then the Oh to D h  be  A c o r r e l a t i o n between the modes of v i b r a t i o n of a  o c t a h e d r a l group, having Table 4.7b.  MXg  symmetry of the h e x a f l u o r i d e i o n i s lowered  t h i s should r e s u l t i n f i v e i n f r a r e d a c t i v e fundamental  105 TABLE 4.7a V i b r a t i o n a l Modes of An O c t a h e d r a l Group MXg Vibrational mode  Assignment  Activity  (A )  M-X symmetric  <E )  X-M-X  < lu>  X-M-X bend  < lu>  M-X asymmetric  l g  g  F  F  stretch  (R)  stretch  (R) (I.R) stretch  (I.R)  X-M-X bend  (R)  X-M-X bend  < 2u> F  (R = Raman a c t i v e ;  vibrations  belonging to ( 2 A  2 u  (Inactive)  (out-of-plane) I.R = I n f r a r e d  + 3E ) species. U  active)  Moreover, the bond  l e n g t h s of one p a i r of t r a n s M-X bonds would be expected t o increase,  and as a r e s u l t of t h i s e l o n g a t i o n , the i n f r a r e d  antisymmetric F-M-F s t r e t c h i n g  mode (corresponding to the A  fundamental a r i s i n g from the s p l i t t i n g Vg—• A has  2 u  + E ) should s h i f t u  been observed  to a lower frequency.  This e f f e c t  (43) i n the i n f r a r e d spectrum of t r i m e t h y l t i n  i n t o two bands a t 675 cm"" and 710 cm . 1  i o n a c t s as a c i s b r i d g i n g 2 v  .  In that  2 u  of the degenerate mode  h e x a f l u o r o a r s e n a t e , i n which the v ^ mode of the AsFg" i o n  to C  active  1  ligand,  splits  I f the h e x a f l u o r i d e  then i t s symmetry i s lowered  case, the degeneracy of i n f r a r e d a c t i v e modes i s  completely removed and the number of i n f r a r e d a c t i v e  fundamental  modes i s i n c r e a s e d to t h i r t e e n .  Complete removal of degeneracy  of the V3 mode has been observed  (43) i n the i n f r a r e d  spectrum  of t r i m e t h y l t i n hexafluoroantimonate i n which the Oo mode of  1£>6 the  SbFg i o n s p l i t s i n t o three modes at 675, 656 and 640 cm"" . 1  TABLE 4.7b C o r r e l a t i o n Between Ahe V i b r a t i o n a l Modes of An O c t a h e d r a l Group of Oh, D4h, o r : C2v Symmetry  D  A  lg  A  lg  4h  °h A  + l g B  2A + 2 E 2u  E  l g  A  2 g  + Eg  F  2 g  B  2 u  + E  F  2 u  u  V i b r a t i o n s of s p e c i e s A and Eu are i n f r a = red a c t i v e 2 u  l + 2A  l u  B  2v  l  A  g 2F  U  C  l  B  + 2B  X  Al + A A  Vibrations of s p e c i e s F i are infrared active  l +  A  X  + 2B  2  2  +  l  B  2  V i b r a t i o n s of s p e c i e s A i , B i , and B are infrared active  u  2  S p l i t t i n g s of the degenerate i n f r a r e d a c t i v e modes of the octahedral reported  anions due to c r y s t a l f i e l d e f f e c t s have a l s o been (124) i n the s o l i d s t a t e i n f r a r e d s p e c t r a  of ammonium  hexafluorogermanate and barium hexafluorogermanate. (125) s p l i t t i n g  The r e p o r t e d  of the V 3 mode of barium h e x a f l u o r o s i l i c a t e  probably i s a l s o due to the same e f f e c t .  However,  cases, the Raman a c t i v e modes of the h e x a f l u o r i d e  i n a l l these i o n do not  appear w i t h any s i g n i f i c a n t i n t e n s i t y i n the i n f r a r e d U n f o r t u n a t e l y only of h e x a f l u o r i d e  very few s t u d i e s  spectra.  on the v i b r a t i o n a l  spectra  ions have been made, probably due to great  experimental d i f f i c u l t i e s i n v o l v e d  i n such  studies.  In t h i s i n v e s t i g a t i o n an attempt was made t o prepare dimethyltin  d e r i v a t i v e s of hexafluorophosphate, h e x a f l u o r o -  arsenate and hexafluoroantimonate.  Derivatives  of both  107 hexafluorophosphate  and h e x a f l u o r o a r s e n a t e  decomposed p a r t i a l l y  to g i v e d i m e t h y l t i n f l u o r i d e and the corresponding  Lewis a c i d as  d e s c r i b e d below. When s t o i c h i o m e t r i c amounts of s i l v e r  hexafluorophosphate  and d i m e t h y l t i n d i c h l o r i d e were allowed to r e a c t i n methanol, s i l v e r c h l o r i d e was p r e c i p i t a t e d i n s t a n t a n e o u s l y .  However, upon  removal of the methanol under vacuum at room temperature,  a sticky  s o l i d was o b t a i n e d which c o u l d not be f u r t h e r d r i e d and which was not completely  s o l u b l e i n methanol or water.  The i n f r a r e d  trum of the s o l i d showed i n t e n s e bands a t 1210, 800,  495 and 475 cm*" .  1110,  spec-  1050, 815,  The recovered methanol was h i g h l y a c i d i c  1  and c o n t a i n e d f l u o r i n e as w e l l as phosphorus as shown by q u a l i tative  tests. When the above m e t a t h e t i c a l r e a c t i o n was performed i n  l i q u i d sulphur d i o x i d e , the product was a white s o l i d which gave i n f r a r e d a b s o r p t i o n bands a t 1260, 1150, 920, 885, 810, 600, 590,  565, 535, and 480 c m . An X-ray powder photograph of the -1  s o l i d showed the presence  o f d i m e t h y l t i n d i f l u o r i d e , and the  recovered sulphur d i o x i d e c o n t a i n e d some phosphorus o x y t r i f l u o r i d e , POF3, which was i d e n t i f i e d by i t s i n f r a r e d Since s i l v e r hexafluorophosphate  can best be prepared  l i q u i d sulphur d i o x i d e (126), POF3 cannot a r i s e from r e a c t i o n of PFg~ w i t h S 0 .  spectrum. from direct  T h e r e f o r e , the r e s u l t s can only be  2  i n t e r p r e t e d i n the f o l l o w i n g manner: (CH ) SnCl 3  2  + 2AgPF  2  (CH ) Sn(PF ) 3  3  6  •  6  °  2  (CH3) Sn(PF )  y  2  >  2  PF  S  5  + S0  2  >  6  2  (CH ) SnF 3  2  POF3 + SGF  2  + 2Ag d l 2  + 2PF  5  108 S i m i l a r r e s u l t s have been r e p o r t e d (43) f o r the r e a c t i o n between t r i m e t h y l t i n bromide and s i l v e r  hexafluorophosphate.  The m e t a t h e t i c a l r e a c t i o n between d i m e t h y l t i n d i c h l o r i d e and s i l v e r h e x a f l u o r o a r s e n a t e i n methanol r e s u l t e d i n i n s t a n t a n eous p r e c i p i t a t i o n of s i l v e r c h l o r i d e . s o l v e n t from  the f i l t r a t e  Upon removal of the  a hygroscopic white  which g r a d u a l l y turned y e l l o w i s h .  s o l i d was o b t a i n e d  The recovered methanol was  h i g h l y a c i d i c and c o n t a i n e d a r s e n i c and f l u o r i n e . photograph of the s o l i d showed the presence difluoride.  The i n f r a r e d spectrum  below i n d i c a t e d the presence  An X-ray powder  of d i m e t h y l t i n  of the s o l i d as d e s c r i b e d  of the h e x a f l u o r o a r s e n a t e group.  These r e s u l t s can be e x p l a i n e d i n terms of p a r t i a l of d i m e t h y l t i n b i s (hexaf luoroarsenat<e)  decomposition  to g i v e d i m e t h y l t i n  d i f l u o r i d e and a r s e n i c p e n t a f l u o r i d e . The  i n f r a r e d spectrum  of the mixture  i n a nujol mull  showed a b s o r p t i o n bands a t 1210, 825, 800, 760, 718, 595, 475, and 375 c m . -1  The spectrum  shown i n F i g u r e 4.7a. v i b r a t i o n a l modes, broad,  but symmetrical  i n the 850 - 250 c m  region i s  - 1  The AsFg" i o n has two i n f r a r e d and v^.  The  active  mode g i v e s a s t r o n g ,  band at approximately  700 cm"  w h i l e the V,. mode i s r e p o r t e d to occur at 400 c m 4 1  - 1  1  (127),  (128) .  a d d i t i o n s u b s i d i a r y bands a t 1300, 1065, 970 and 825 cm" appear i n the i n f r a r e d spectrum mixture,  (127).  In the spectrum  the bands a t 1210, 800, and 595 c m  - 1  1  In also  of the  can be a s s i g n e d  to the C-H symmetric band, the CHg rock, and the Sn-C asymmetric s t r e t c h i n g modes r e s p e c t i v e l y .  The bands a t 760 and 718 c m  - 1  are the two components of the v*_ mode of the h e x a f l u o r o a r s e n a t e group.  S i m i l a r l y the bands a t 375 and 475 are probably the two  Frequency (cm-) 1  110 components of the V4 mode, although d i m e t h y l t i n d i f l u o r i d e a l s o absorb at 375  cm" . 1  Thus i t appears t h a t the symmetry of  the A S F Q group has been lowered from 0  n  to D4 .  The  n  spectrum of  the mixture thus shows f e a t u r e s s i m i l a r to those r e p o r t e d for t r i m e t h y l t i n hexafluoroarsenate. and  will  The  (43)  spectroscopic r e s u l t s  the p a r t i a l decomposition of the d i m e t h y l t i n b i s ( h e x a f l u o r o -  arsenate) both suggest very  s t r o n g i n t e r a c t i o n between  (CHg^Sn  and A S F Q groups r e s u l t i n g i n the p a r t i a l decomposition of AsFg group. .Dimethyltin b i s ( h e x a f l u o r o a n t i m o n a t e )  c o u l d be prepared  by  the m e t a t h e t i c a l r e a c t i o n between d i m e t h y l t i n d i c h l o r i d e and s i l v e r hexafluoroantimonate i n methanol. c o u l d not be obtained  However, the product  f r e e from methanol even a f t e r pumping  s o l i d f o r 24 hours at 60°.  When the s o l i d was  heated to  under vacuum, decomposition of the hexafluoroantimonate and  some antimony p e n t a f l u o r i d e was  formed.  r e a c t i o n between d i m e t h y l t i n d i c h l o r i d e and fluoroantimonate An  was  The  silver  white s o l i d was  X-ray powder photographs of the s o l i d d i d not to d i m e t h y l t i n d i f l u o r i d e . was  obtained.  N u j o l mull  120° occurred  metathetical hexa-  a l s o performed i n l i q u i d sulphur  anhydrous, extremely hygroscopic  dioxide. obtained.  show any  However, no a n a l y s i s of the  lines  samples of the s o l i d prepared f o r the  windows but r e p r o d u c i b l e s p e c t r a c o u l d be obtained samples by using s i l v e r c h l o r i d e or polythene  ported the 750  i n f r a r e d spectrum has  cm"  1  salt  on n u j o l mull  sheets.  f e a t u r e s s i m i l a r to those r e -  f o r t r i m e t h y l t i n hexafluoroantimonate. - 250  due  product  measurements of the i n f r a r e d spectrum r e a c t e d r a p i d l y with  The  the  The  r e g i o n i s shown i n F i g u r e 4.7b.  spectrum i n Other bands  .112 were observed at 1210(w), 990(m), 910(m), 828(m), 782(w) and 760(vw).  (the O3 mode) has  Only one i n f r a r e d a c t i v e frequency  been r e p o r t e d  (128) f o r the SbFg i o n .  In order to compare the  spectrum of d i m e t h y l t i n b i s ( h e x a f l u o r o a n t i m o n a t e ) with that of the  SbFg i o n , the i n f r a r e d spectrum of s i l v e r  hexafluoroantimonate  was a l s o measured under comparable c o n d i t i o n s . showed a very s t r o n g broad band at 660 cm" 560 cm" ) 1  (with a shoulder at  1  and another strong band showing peaks at 310, 290 and  270 cm" .  The 660 c m  1  the  The spectrum  -1  band i s due to the r e p o r t e d V3 mode and  band i n the 310-270 c m  mode which i s s p l i t  -1  r e g i o n i s e v i d e n t l y due to the v^  due to c r y s t a l f i e l d e f f e c t s .  In the spec-  trum of d i m e t h y l t i n b i s ( h e x a f l u o r o a n t i m o n a t e ) , the bands at 1210 and  828 cm"  1  can be a s s i g n e d to the C-H symmetric band and the  CH3 r o c k i n g modes r e s p e c t i v e l y .  The spectrum of s i l v e r hexa-  f l u o r o a n t i m o n a t e does not show any bands i n the 1000-800 region.  The medium bands at 990 and 910 cm"  cm"  1  are t h e r e f o r e the  1  v i b r a t i o n a l modes, i n f r a r e d i n a c t i v e f o r the o c t a h e d r a l SbFg ion, of  which have become i n f r a r e d a c t i v e as a r e s u l t of d i s t o r t i o n  the SbFg group by (CHg^Sn.  from the F i g u r e 4.7b,  1  as can be seen  the O 3 mode f o r d i m e t h y l t i n b i s ( h e x a -  fluoroantimonate) i s s p l i t 635 cm" ,  Significantly,  and shows peaks at 675, 650 and  and a d d i t i o n a l bands which do not appear i n the  spectrum of s i l v e r hexafluoroantimonate are present at 595, 545, 445 and 365 cm" . 1  to cm" the  The band at 595 c m  -1  can be assigned  the Sn-C asymmetric s t r e t c h but the bands at 540 and 445 1  are c e r t a i n l y due to the hexafluoroantimonate group.  Thus  hexafluoroantimonate a b s o r p t i o n i n d i m e t h y l t i n b i s ( h e x a -  fluoroantimonate) i s s i g n i f i c a n t l y  d i f f e r e n t from that of the  1.13 SbFg  ion.  The appearance of 540 and 445 c m  -1  bands cannot be  a t t r i b u t e d to c r y s t a l f i e l d e f f e c t s , and i n d i c a t e strong a c t i o n between  inter-  (CHg^Sn and SbFg groups as a r e s u l t of which the  0^ symmetry of the SbFg group i s d i s t o r t e d (probably to C v) . 2  Although the s t e r e o c h e m i s t r y i n t h i s compound cannot be determined w i t h any c e r t a i n t y , the i n f r a r e d r e s u l t s are c o n s i s t e n t w i t h a configuration  i n which l i n e a r (CHg) Sn groups are c o o r d i n a t e d i n 2  the e q u a t o r i a l plane by c i s f l u o r i n e atoms of the SbFg group making the t i n atom s i x c o o r d i n a t e .  Coordination  between  ( C H ) S n and SbFg i s a l s o i n d i c a t e d by the marked changes brought 3  2  about i n the spectrum when the compound was  exposed to a i r .  bands at 990, 910, 782, 760, 545, 445 and 365 c m  -1  The  completely  disappeared and the bands at 675, 650 and 635 were r e p l a c e d broad band showing a maximum at 660 c m . -1  dimethyltin  by a  Thus, upon exposure of  b i s ( h e x a f l u o r o a n t i m o n a t e ) to a i r , f r e e SbFg ions are  produced as a r e s u l t of h y d r o l y s i s . ; The d i m e t h y l t i n  d e r i v a t i v e s of group  Vb  hexafluorides  are very s i m i l a r to the analogous t r i m e t h y l t i n d e r i v a t i v e s Trimethyltin  (43 ).  hexafluorophosphate i s u n s t a b l e , the h e x a f l u o r o -  arsenate and antimonate which are d e r i v e d  from  progressively  s t r o n g e r Lewis a c i d s AsFg and SbFg are s t a b l e , the anion i n the  former a c t i n g as a t r a n s ,  bridging  group.  The s t a b i l i t i e s of corresponding  derivatives follow vatives  and i n the l a t t e r as a c i s dimethyltin  the same sequence though d i m e t h y l t i n  are a p p a r e n t l y l e s s s t a b l e than the t r i m e t h y l t i n  derivatives.  deri-  1-14 4.8  ,  The D i m e t h y l t i n ( I V )  v  2-  D e r i v a t i v e of B 1 2 C I 1 2  2—  The  Bi2 li2  i  c  o  n  i  considered  s  (129) to have an i c o s a 2 -  hedral  s t r u c t u r e s i m i l a r t o that of B 1 2 H 1 2  s t r u c t u r e of B  1 2  H  12 ~  crystallography. should Ag,  n  2  a  s  b  e  e  established  n  •  A molecule or i o n belonging  s i n g l e strong  g  C 1  12~ (  l i n e at 300 c m 1 2 9  )•  to observe other  J  t  h  strong  a  s  b  e  e  - 1  n  However, only a  i s observed i n the Raman spectrum suggested  (129) that the f a i l u r e  Raman l i n e s may be a consequence of a c c i -  d e n t a l c a n c e l l a t i o n of p o l a r i z a b i l i t y  changes of o p p o s i t e l y  char-  boron and halogen atoms i n t o t a l l y symmetric v i b r a t i o n s .  Only one fundamental i n f r a r e d a b s o r p t i o n has  t o p o i n t group 1^  Raman L i n e s of s p e c i e s H , and three u  ged  icosahedral  e  g i v e r i s e to two s t r o n g l y p o l a r i z e d Raman L i n e s of s p e c i e s  and four d e p o l a r i z e d  1 2  n  (130) by X-ray  i n f r a r e d a c t i v e fundamentals of s p e c i e s F ^ .  of B  T  been r e p o r t e d The  frequency at 1030 c m  2  (129) f o r  &i2^12 ion  2 -  d i m e t h y l t i n d e r i v a t i v e of B-j^Cl-j^  a hygroscopic  - 1  white s o l i d which contained  was obtained as  some methanol.  The  methanol c o u l d not be removed from the s o l v a t e d product even a f t e r heating  f o r 24 hours at 100° under vacuum.  The a n a l y t i c a l  r e s u l t s of the heated s o l i d i n d i c a t e that the product  contained  about one to two moles of methanol per mole of (CHg) gSnB-j^Cl-^. Due to the very high m o l e c u l a r weight of (CHg) gSnB-^Cl-^ r a t h e r d i f f i c u l t t o a s c e r t a i n the exact amount of methanol i n the i  t  i  s  2 -  product. occurred  However, no decomposition o f the &\2^12 and the recovered  group  methanol was n e i t h e r a c i d i c nor con-  t a i n e d any c h l o r i n e or boron. 1  The i s recorded  i n f r a r e d spectrum of the d i m e t h y l t i n B ^ g C l . ^ d e r i v a t i v e i n Table 4.8 and p a r t of the spectrum i s shown i n  TABLE 4.8 Infrared Absorption  Spectrum of The D i m e t h y l t i n D e r i v a t i v e of  Frequency  Relative  Intensity  3460  ; s  3080  vw  2960  vw  1600  w  1455  m  1400  w  1250  w  1220  vw  1170  vw  1144  w  1040  s  1002  m  950 925  m = medium;  (cm "*")  ) ) )  m  857  s,sh  824  s  590  vw  535  vs  480  m  425  w  328  w  s = strong;  sh = shoulder;  v = very; w = weak.  117 F i g u r e 4.8  (curve  solid Ag B 2Clj2 2  4.8  1  (curve  a).  the a b s o r p t i o n and 328 c m  group.  s  a  l ° measured and i s a l s o shown i n F i g u r e ... s  In the spectrum of the d i m e t h y l t i n d e r i v a t i v e , bands at 1040,  1002,  950, 925, 824, 535, 480, group.  The  425  other  bands are due to the methanol and the d i m e t h y l t i n  The CHg  by the strong asymmetric  a  For comparison, the i n f r a r e d spectrum of  can be a t t r i b u t e d to the B-j^Cl]^  -1  absorption  w  b).  r o c k i n g mode of (CHg^Sn group i s p r o b a b l y masked  band at 824 c m .  I t may  -1  s t r e t c h appears at 590 cm" ; 1  p o s s i b l e to a s c e r t a i n whether  the Sn-C  be noted that the  Sn-C  however, i t i s not symmetric  stretch i s also  present. Comparing tin  the B - ^ C l ^  p a r t of the spectrum i n the  dimethyl-  d e r i v a t i v e w i t h that of the s i l v e r s a l t i t becomes evident  t h a t , i n the d i m e t h y l t i n s a l t ,  the spectrum of the B ^ C l - j ^ group 2 -  i s very  d i f f e r e n t from that of the f r e e B-j_ Cl]_ 2  is d i f f i c u l t  to d e r i v e any d e f i n i t e c o n c l u s i o n s  ion.  2  Though i t  about the s t e r e o -  chemistry i t can be i n f e r r e d that the symmetry of B - ^ C l ] ^  n  a  s  been lowered i n t h i s compound as a r e s u l t of which the i n f r a r e d i n a c t i v e modes of the f r e e i C l j 2 B  2  active.  T h i s can be e x p l a i n e d  i o n have become i n f r a r e d  e i t h e r i n terms of c r y s t a l  field  e f f e c t s or i n terms of an i n t e r a c t i o n between the d i m e t h y l t i n group and the B - ^ C l ] ^ group. s c o p i c r e s u l t s of other that the changes dimethyltin  d i m e t h y l t i n d e r i v a t i v e s , i t i s suggested  i n the B  1 2  d e r i v a t i v e may  between (CHg) Sn 2  by the gradual  In view of the i n f r a r e d s p e c t r o -  C1  1 2  p a r t of the spectrum of the  be due t o some form of  and i 2 ^ 1 2 groups. B  : 1  coordination  T h i s i s f u r t h e r supported  changes i n the i n f r a r e d spectrum of t h i s com-  pound upon exposure of the compound to a i r .  The bands at 950,  118 925,  824,  480,  425  and 328  g r a d u a l l y diminished i n i n t e n s i t y  a f t e r an exposure of three days, these bands disappeared CHo  r o c k i n g mode appeared at 790  cm" . 1  and  and the  110 CHAPTER 5 TRIMETHYLANTIMONY(V) DERIVATIVES'  Apart from the c r y s t a l s t r u c t u r e d e t e r m i n a t i o n of methylantimony d i c h l o r i d e , dibromide is  known about  and d i i o d i d e , very  little  the s t e r e o c h e m i s t r y of trimethylantimony  v a t i v e s of the type RgSbXg.  tri-  deri-  R e c e n t l y Long, Doak, and Freedman  (52) r e p o r t e d i n f r a r e d s p e c t r a of trimethylantimony the d i n i t r a t e and the s u l p h a t e .  dihalides,  However, some of the  results  o b t a i n e d by these workers appear r a t h e r anomalous.  In the  present i n v e s t i g a t i o n , some of the work r e p o r t e d by  these  workers was  repeated.  derivatives  In a d d i t i o n , a wide v a r i e t y of a c i d  of trimethylantimony(V) were prepared and  their  i n f r a r e d s p e c t r a were examined. 5.1  Trimethylantimony D i h a l i d e s C r y s t a l s t r u c t u r e d e t e r m i n a t i o n s (54) of trimethylantimony  d i c h l o r i d e , d i b r o m i d e and d i i o d i d e have shown t h a t these  dihalides  are t r i g o n a l b i p y r a m i d a l molecules c o n t a i n i n g a p l a n a r t r i m e t h y l antimony group i n the e q u a t o r i a l p o s i t i o n . of  The g e n e r a l c o n c l u s i o n s  Long, Doak, and Freedman (52) are c o n s i s t e n t w i t h the  gonal b i p y r a m i d a l s t r u c t u r e .  The main f e a t u r e s of the s p e c t r a of  these d i h a l i d e s r e p o r t e d by these workers are the C-H s t r e t c h i n the 3020-3010 c m in  the 2928 - 2920 cm""  1403-1387 cm" and the Sb-C  1  1  asymmetric  r e g i o n , the symmetric C-H  -1  r e g i o n , the C-H  r e g i o n , the CH  tri-  3  stretch  asymmetric bend i n the  rock i n the 8 7 0 i - 860  asymmetric s t r e t c h i n the 587-554 c m  -1  cm  -1  region  region.  However, these authors r e p o r t e d t h a t , i n the spectrum  of \  trimethylantimony d i f l u o r i d e , complex bands occur i n the  1120-  120 1050,  730,  and 540  s t r e t c h at 587 c m  - 450  cm  The  observed  the C-H  bend at 1415 the CH  of  this  the C-H  -1  the C-H  -1  symmetric bend at 1235 the Sb-C  The main  asymmetric s t r e t c h at 3065  symmetric s t r e t c h at 2965 cm , cm ,  relative  are l i s t e d i n Table 5.1.  are the C-H  1  and the Sb-F  In view of t h i s i n c o n -  a b s o r p t i o n bands, w i t h t h e i r  rock at 855 cm" ,  3  asymmetric  s t u d i e d again.  f e a t u r e s of the spectrum -1  the Sb-C  of the d i f l u o r i d e , the spectrum  i n t e n s i t i e s and assignments,  cm ,  r e g i o n s , and  i s p a r t i a l l y masked.  -1  s i s t e n c y i n the spectrum compound was  -1  asymmetric  and 1221  cm , -1  asymmetric s t r e t c h at 585  asymmetric s t r e t c h at 475  cm .  cm , -1  Contrary to the  -1  r e p o r t s of Long, Doak, and Freedman, the spectrum  of the  d i f l u o r i d e does not show any complex bands i n the 1120-1050, 730,  and 540  - 450  cm"  regions.  1  The  observed  spectrum  i s com-  p l e t e l y c o n s i s t e n t with a t r i g o n a l bipyramidal s t r u c t u r e . a d d i t i o n a l bands observed  by Long, Doak, and Freedman must  t h e r e f o r e be a s s o c i a t e d w i t h i m p u r i t i e s present i n t h e i r Trimethylantimony  d i f l u o r i d e sublimes,  at room  under vacuum, and i s s o l u b l e i n o r g a n i c s o l v e n t s such methanol, acetone  and c h l o r o f o r m .  v a l e n t l i k e other d i h a l i d e s . frequency Sn-F  (475 cm ) -1  A comparison of the Sb-F  Trimethylantimony  (355 cm ) -1  Dinitrate  of trimethylantimony  as co-  stretching the  in trimethyltin fluoride difluoride.  (CH ) Sb(N0 ) 3  3  3  Long, Doak, and Freedman (52) d e s c r i b e d the spectrum  temperature  d i f l u o r i d e with  i n d i c a t e s the c o v a l e n t nature of trimethylantimony 5.2  sample.  It i s therefore largely  i n trimethylantimony  s t r e t c h i n g frequency  The  d i n i t r a t e and  infrared  from i t concluded  also  121 TABLE 5.1 I n f r a r e d A b s o r p t i o n Spectrum of Trimethylantimony Frequency  (cm ) -1  Relative  Intensity  Difluoride  Assignment  3065  w  C-H asym.  2965  w  C-H sym.  2450  vw  2110  vw  1812  w  1768  w  1415  m  C-H asym. bend  m,sp  C-H sym.bend  855  vs  CH  585  s,sp  Sb-C asym. s t r .  475  vs  Sb-F asym. s t r .  1235 1221  m = medium;  ) ) )  s = strong;  sp = sharp;  3  v = very;  str. str.  rock  w  = weak.  that t h i s compound has an i o n i c s t r u c t u r e .  They observed the  n i t r a t e a b s o r p t i o n f r e q u e n c i e s at 1516(s), 83.4(s), and 728(w) c m . -1  1457(s),  In view of the r e c e n t l y  evidence f o r the nonexistence  1050(vw), accumulated  of the t r i m e t h y l t i n c a t i o n i n the  s o l i d s t a t e , the i o n i c s t r u c t u r e f o r trimethylantimony seems r a t h e r s u r p r i s i n g .  dinitrate  T h e r e f o r e , i n t h i s work, t r i m e t h y l a n t i  mony d i n i t r a t e was prepared under anhydrous c o n d i t i o n s , and the i n f r a r e d and u l t r a v i o l e t s p e c t r a of t h i s compound were s t u d i e d . R e l i a b l e i n f r a r e d s p e c t r a of trimethylantimony  dinitrate  c o u l d only be o b t a i n e d on samples made as m u l l s and p l a c e d between s i l v e r c h l o r i d e sheets.  When the s p e c t r a were measured  e i t h e r on m u l l s p l a c e d between potassium samples made i n potassium  bromide p e l l e t s , c o n s i d e r a b l e ex-  change o c c u r r e d between trimethylantimony sium bromide.  bromide p l a t e s or on  d i n i t r a t e and potas-  The s p e c t r a measured by using s i l v e r  sheets were always r e p r o d u c i b l e . mony d i n i t r a t e i n the 1650-650 c m m u l l i s shown i n F i g u r e 5.2. the 4000 - 400 c m  - 1  The spectrum - 1  chloride  of t r i m e t h y l a n t i -  region obtained i n a n u j o l  The a b s o r p t i o n f r e q u e n c i e s ( i n  region) together with t h e i r r e l a t i v e i n -  t e n s i t i e s and assignments,  are l i s t e d i n Table 5.2.  The  a b s o r p t i o n bands due t o the n i t r a t e group occur a t 1550-1510, 1290-1275, 965, 795, 730, and 708 cm' . 1  I t can be c l e a r l y  that the n i t r a t e group i n trimethylantimony infrared absorption c h a r a c t e r i s t i c s e c t i o n 2.1). are absent  seen  d i n i t r a t e shows  of a n i t r a t o group (see  The c h a r a c t e r i s t i c bands of a f r e e n i t r a t e i o n  i n the observed  spectrum.  Therefore  trimethylanti-  mony n i t r a t e must have a n o n - i o n i c s t r u c t u r e and the n i t r a t e groups are a p p a r e n t l y c o o r d i n a t e d t o the trimethylantimony  Frequency (cm") 1  to  124 TABLE 5.2 I n f r a r e d A b s o r p t i o n Spectrum of Trimethylantimony Frequency  (cm ) -1  Relative Intensity  Dinitrate  Assignment  3070  m  C-H asym. s t r .  2960  m  C-H sym. s t r .  2820  w  2260  w  1990  w  1820  w  1765  w  1675  w  1530  s, b  N0  1415  m  C-H asym. s t r .  1290  s  )  1275  s  )  1245  m  )  1230  m  C-H sym. bend  965  s  NO s t r . , (02)  865  s  CHg  rock  795  m  NOg  out-of-plane rock, (Vg)  728  s  N0  2  sym.  708  m  N0  2  580  ms  Sb-C asym.  520  w, b  Sb-C sym. s t r . ?  b = broad;  m =.medium;  s = strong;  N0  asym. str.,(v* )  2  4  sym. s t r . ,  2  (0-^)  bend,(^3)  asym.bend,(^5) str.  w = weak.  N i t r a t e a b s o r p t i o n bands have been a s s i g n e d assuming that the n i t r a t e group i s u n i d e n t a t e .  125  group. can  The  be  absorptions  assigned  by  C-H  stretch;  and  2960 c m ,  C-H  -1  CH3  -1  rock;  and  580  p r e s e n c e o f o n l y one intensity,  cm ,  cm" ,  ranging  f r o m medium t o  L o n g , Doak, and cm  - 1  i n the  (52)  forbidden  3  2  i n f r a r e d spectrum.  and  i n other  trimethylantimony  occurs  i n the  frequency  can  ciated with  a l s o occur  the  1  region.  later,  o f t h i s weak b a n d may  antimony  atoms.  examined the  infra-  found t h a t  the  i n t h i s region i n these  due  stretching compounds, i t  i n this region i s  A l t e r n a t e l y , the  to the s l i g h t  and  absorption  symmetric s t r e t c h i n g v i b r a t i o n which  be  529  dinitrate  a s i m i l a r weak  Though a Sb-0  a p p e a r as a symmetry f o r b i d d e n mode.  with  the  d e r i v a t i v e s s u c h as c a r b o n a t e  t h a t t h e weak a b s o r p t i o n Sb-C  represent  In t r i m e t h y l a n t i m o n y  described  530-520 cm  i s more l i k e l y  G r e e n (131)  528  associated  symmetric s t r e t c h appears weakly at  i n the  be  inten-  2  be  o r may  [ ( C H 3 ) ^ S b j H g I 3 and  cm-1  chromate which w i l l  intensity  [(CH3)3 S b C 1 0 ^ j 0 .  and  c o n t a i n i n g t h e c a r b o n and  Sb-C  group would  o b s e r v e d a weak band a t  [(CH ) gSbCl] 0  V e r y r e c e n t l y C u l l e n , D e a c o n , and  infrared  strong  s t r e t c h i n g b a n d w i t h an  h a v e s u g g e s t e d t h a t t h i s b a n d may  Raman s p e c t r a o f  The  group i s p l a n a r .  trimethylantimony  the antimony-oxygen s t r e t c h i n g v i b r a t i o n  r e d and  865  strong.  Freedman  d i s t o r t i o n of the plane  1  s t r e t c h i n g band o f medium  i n f r a r e d s p e c t r a of  These a u t h o r s  cm" ,  o f medium  trimethylantimony  t o a s y m m e t r i c Sb-C  1415  symmetric bend;  s t r e t c h i n g frequency  i n d i c a t e s t h a t the  asym-  asymmetric s t r e t c h .  i n a d d i t i o n t o t h e a s y m m e t r i c Sb-C sity  C-H  1  A non-planar c o n f i g u r a t i o n of the give rise  C-H  -1  Sb-C  -1  Sb-C  i . e . 3070 c m ,  symmetric s t r e t c h ;  1230  group  the s p e c t r a of t r i m e t h y l -  difluoride,  a s y m m e t r i c b e n d ; 1245,  cm ,  to the trimethylantimony  comparison with  antimony dibromide, metric  due  assomay  presence  d i s t o r t i o n of  the  126 plane c o n t a i n i n g the carbon and antimony atoms. spectrum  of trimethylantimony  Thus the e n t i r e  d i n i t r a t e can be i n t e r p r e t e d i n  terms of a t r i g o n a l b i p y r a m i d a l s t r u c t u r e i n which each n i t r a t e group occupies the a p i c a l p o s i t i o n and i s bonded through  one  oxygen atom to the trimethylantimony group s i t u a t e d i n the e q u a t o r i a l plane. F u r t h e r evidence of p a r t i a l c o v a l e n t bonding  between  n i t r a t e groups and the antimony atom i s p r o v i d e d by the v i o l e t a b s o r p t i o n spectrum chloroform s o l u t i o n s .  measured i n aqueous and  In aqueous s o l u t i o n , the a b s o r p t i o n  maximum occurs at 302 m^, The  which was  ultra-  and  i n c h l o r o f o r m s o l u t i o n , at 280nyi4.  a b s o r p t i o n maximum at 302 m^  i n aqueous s o l u t i o n i s char-  a c t e r i s t i c of the f r e e n i t r a t e i o n  and i s a t t r i b u t e d to the  symmetry f o r b i d d e n n—*u * t r a n s i t i o n i n the n i t r a t e i o n (64). A l l such n  >TT* t r a n s i t i o n s show a blue s h i f t  ( i . e . the  a b s o r p t i o n maximum i s d i s p l a c e d to higher frequency)  in a  s e r i e s of s o l v e n t s with i n c r e a s i n g d i e l e c t r i c constant Since c h l o r o f o r m has a lower  d i e l e c t r i c constant  (D =  (132). 4.8)  than water, the f r e e n i t r a t e i o n i n t h i s s o l v e n t would be  ex-  pected to show an n—»JT* t r a n s i t i o n at longer wave lengths than i n water.  The  observed maximum at 280m/4 i n c h l o r o f o r m  i n d i c a t e s that trimethylantimony  solution  dinitrate dissociates in  aqueous s o l u t i o n to produce n i t r a t e i o n s , but i n c h l o r o f o r m s o l u t i o n , no n i t r a t e i o n s are present.  S i m i l a r s h i f t s of  a b s o r p t i o n maxima i n going from water to a s o l v e n t of d i e l e c t r i c constant have been observed pounds, e.g.  t r a n s i t i o n metal n i t r a t e s ,  lower  f o r other n i t r a t o comin t-butyl  alcohol,  show a b s o r p t i o n maxima at 270-275 m/* (133), and d i m e t h y l t i n n i t r a t e i n e t h y l a l c o h o l shows a b s o r p t i o n maximum at 285m^< (51) . /  127 The proton resonance  spectrum  d i n i t r a t e i n chloroform s o l u t i o n  of  trimethylantimony  shows one peak, a t Y 7 . 8 5 .  Under the same c o n d i t i o n s , trimethylantimony  dibromide  shows a  peak a t r 7.3. 5.3  Trimethylantimony The  carbonato  Carbonate  vibrational  (CH3)3SbC03  f r e q u e n c i e s of the carbonate  group have been d i s c u s s e d e a r l i e r .  trum of trimethylantimony carbonate was  The  i o n and  infrared  the spec-  measured on samples made  as m u l l s , as w e l l as on samples made as p e l l e t s i n potassium bromide. observed  Both methods gave i d e n t i c a l r e s u l t s . spectrum  i s shown i n F i g u r e 5.3,  A p o r t i o n of  and the a b s o r p t i o n  f r e q u e n c i e s , together with t h e i r r e l a t i v e i n t e n s i t i e s and gested assignments, bands due  are l i s t e d  i n Table 5.3.  absorption  to the trimethylantimony group appear at 2950 ,  (C-H asymmetric s t r e t c h ) ;  2880,(C-H symmetric s t r e t c h ) ;  1385,(C-H asymmetric bend); 1225, (CH3 r o c k ) ; and 575,  (Sb-C  (C-H  symmetric bend);  asymmetric s t r e t c h ) cm .  r e g i o n 575-500 cm , -1  The  attributed  to the carbonate  1110,  740,  1075,  combination  632, 1040  bands.  The  i n the  450,  The  group occur at 1730,  375,  and 510  a b s o r p t i o n bands which can  and 250 -1  cm  cm . -1  1280,  be 1115,  The weak bands  are probably overtones  and  appearance of the weak band at 525  has a l r e a d y been d i s c u s s e d i n connection with dinitrate.  875,  the trimethylantimony group i s a p p a r e n t l y  p l a n a r i n t h i s compound.  790,  appears  1405-  Since  -1  only one a b s o r p t i o n band of medium i n t e n s i t y  at 1460,  The  sug-  carbonate  -1  trimethylantimony  a b s o r p t i o n bands i n t h i s compound  c l e a r l y show that the carbonate  cm  group i s i n v o l v e d i n . p a r t i a l  Me Sb C 0 3  O r  2000  I  I  1800  I  I  1600  I  I  1400  I  I  1200  I  Frequency  3  1  :  1000 (cm ) -1  I  _1  800  I  1  600  1  1  400  1  1  200  129 TABLE 5.3 I n f r a r e d A b s o r p t i o n Spectrum of Trimethylantimony Carbonate Assignment  Frequency  (cm ) Relative  2950  m  2880  sh  C-H  1730  s  C  1460  w  1405-1385  w  C-H  asym.bend  1280  s  C0  asym. s t r . , (v )  -1  Intensity  C - H asym.str. sym. s t r .  ^^0  o  2  sym. s t r . ,  4  C-H  sym.bend  COg  sym. s t r . , ( v )  1225  w  1115  s  1100  s  1075  vw  1040  vw  875  vs  C H g rock  790  vs  COg  0  out-of-plane def.,(vg)  740  COg  sym.bend,  632  COo  asym.bend,  575  s  Sb-C  asym. s t r .  525  w  Sb-C  sym. s t r . ?  510  w m m s  Sb-Ostr. ? L a t t i c e modes ?  450 375 250 m = medium;  s = strong;  v = very;  w = weak.  Assignments f o r the carbonate group have been suggested assuming that the C O g group i s b r i d g i n g .  130 covalent  bonding  symmetry  cannot  Vg  observed  with  the trimethylantimony  be h i g h e r  i n ionic  than  C  carbonates  2 v  •  T  n  g r o u p and t h a t i t s  doubly  e  a t 1415 c m  degenerate  has s p l i t  - 1  s t r o n g w e l l d e f i n e d bands a t 1730 and 1280 cm" . f r e q u e n c i e s c a n be compared w i t h  carbonate  which occur  Similarly,  appears  a s an i n t e n s e band, s p l i t  1100 965  cm ; cm  and a t 1078 c m  - 1  splitting plexes split  into  cm .  lattice  i n dimethyl  i n ethylene  G  observed  degenerate  f the f r e e  modes, a l t h o u g h  - 1  carbonate  carbonato  mony g r o u p s t h r o u g h arrangement  region.  Similarly  ( 1 3 5 ) . The com-  i o n has  and t h e o u t - o f -  - 1  are similar  t o those  indicates  also  cause  spectrum that  of  this  a n t i m o n y atom, and t h e s p e c -  i n terms o f a p o l y m e r i c s t r u c t u r e  g r o u p i s bonded t o p l a n a r  two o x y g e n atoms.  of a trigonal  a highly strained  - 1  The i n f r a r e d  undoubtedly  i n which a carbonato  corner p o s i t i o n s volve  of the free  Sb-0 v i b r a t i o n s may p o s s i b l y  trum c a n o n l y be i n t e r p r e t e d which each  (solid)  occurs at  ; and may be due t o t h e  compound c o n t a i n s a p e n t a - c o v a l e n t  in  a t 1115 and  i o n shows a s t r o n g a b s o r p t i o n a t  i n 500 - 400 c m  trimethylantimony  i o n now  i n metal-carbonato  mode  i n d i m e t h y l t i n carbonate  absorption  respectively  carbonate  carbonate  The bands a t 450, 375 a n d 250 c m  - 1  observed  The o t h e r  a doublet  two s t r o n g bands a t 740 and 632 c m  p l a n e mode ^ 790  - 1  into  band  o f t h i s mode i s a l s o  (105).  - 1  t h e Raman a c t i v e mode v^ o f t h e f r e e  the corresponding  - 1  frequencies of  a t 1750 and 1280 c m  (134).  these  t h e C=0 and C-C*2 (* r e p r e s e n t s  o x y g e n atoms i n v o l v e d i n b o n d i n g ) s t r e t c h i n g dimethyl  i n t o two  In f a c t  1  two  mode  trimethylanti-  The o t h e r p o s s i b l e  g r o u p i s bonded t o any two  b i p y r a m i d a l monomer, w o u l d i n -  s t r u c t u r e and may be r u l e d o u t .  a monomeric s t r u c t u r e i n w h i c h  the carbonate  group i s  131 u n i d e n t a t e l y bonded to the trimethylantimony group would not be c o n s i s t e n t with the p l a n a r i t y of the trimethylantimony group as w e l l as with the observed 5.4  Trimethylantimony The  f r e q u e n c i e s of the carbonate  Sulphate  i n f r a r e d spectrum  of trimethylantimony  sulphate was  r e p o r t e d r e c e n t l y by Long, Doak, and Freedman (52). authors concluded,  group.  These  from t h e i r i n f r a r e d r e s u l t s , that t r i m e t h y l -  antimony sulphate i s c o v a l e n t . However, these authors remarked that the observed  i n f r a r e d bands do not correspond w e l l w i t h  those g i v e n f o r sulphato complexes c o n t a i n i n g e i t h e r or b i d e n t a t e sulphato groups, c u l t to i n t e r p r e t .  and that the spectrum  very r a p i d l y when a potassium  bromide p e l l e t c o n t a i n i n g trimethylantimony  i n f r a r e d spectrum i n t h i s work.  is diffi-  These authors a l s o r e p o r t e d that pronounced  changes o c c u r r e d i n the spectrum  to the atmosphere.  unidentate  s u l p h a t e was exposed  In view of t h i s i n c o n c l u s i v e r e p o r t , the of trimethylantimony  sulphate was s t u d i e d again  The i n f r a r e d s p e c t r a were measured on anhydrous  samples made as mulls i n the dry box, as w e l l as on samples which were exposed to a i r and made as mulls or potassium pellets.  bromide  Both the anhydrous samples and samples exposed to a i r  gave i d e n t i c a l s p e c t r a by both methods ( i . e . as mulls or potassium  bromide p e l l e t s ) .  A p o r t i o n of the spectrum  on a n u j o l m u l l sample i s shown i n F i g u r e 5.4.  obtained  The a b s o r p t i o n  f r e q u e n c i e s together with t h e i r r e l a t i v e i n t e n s i t i e s and suggested assignments are l i s t e d i n Table 5.4a.  The a b s o r p t i o n  bands due t o the trimethylantimony group occur at 3050, (C-H asymmetric s t r e t c h ) ; 2950, (C-H  symmetric s t r e t c h ) ; 1415,  (C-H asymmetric bend); 1230, (C-H symmetric bend); and 860,  0 !-  1600  I  i  1400  i  i  1200  i  i  1000  i  I  I  800  Frequency ( c m ) - 1  I  600  I  I  400  1  1  200  133 TABLE 5.4a I n f r a r e d A b s o r p t i o n Spectrum of Trimethylantimony Frequency  (cm ) Relative Intensity  Assignment  -1  3050  w  C-H asym. s t r .  2950  w  C-H sym. s t r .  2120  vw  1760  vw  1415  m  C-H asym. bend  1285  s  SC>2 asym. s t r . , (Og)  1230  m  C-H sym. bend  1145  s  SO2 sym. s t r . , ( v ^ )  >  980  sh  950  s  SO2 asym. s t r . , ( 0 g )  860  s  CHg rock  825  s  SO2  sym.str.,(v )  650  s  S0  4  rocking,(0^)  600  s  S0  2  bend, ( v )  495  m  Rocking ( S 0 ) ,. ( v )  428  w  SO* bend, (v >  250  s  L a t t i c e mode ?  m = medium; s = s t r o n g ; v = very.  Sulphate  * denotes  2  3  4  Q  4  sh = shoulder; sp = sharp; w = weak;  the oxygen atoms i n v o l v e d i n bonding.  134 (CH  rock) cm" .  825,650>, 600, of  The a b s o r p t i o n bands at 1285,  1  3  980, ( s h ) , 950,  495 and 428 can be a t t r i b u t e d t o the v i b r a t i o n s  the sulphate group.  observed  1145,  The number of sulphate a b s o r p t i o n : bands  i n the spectrum  of trimethylantimony  sulphate c l e a r l y 2-  shows that t h i s compound does not c o n t a i n f r e e SO4  ions and that  the symmetry of the s u l p h a t e group i n t h i s compound cannot than C  2 v  .  I t i s t r u e that the observed  be higher  bands do not correspond w e l l  w i t h those r e p o r t e d (91) f o r metal sulphato complexes c o n t a i n i n g u n i d e n t a t e o r b i d e n t a t e s u l p h a t o group.  However, i t must be con-  s i d e r e d that the changes i n the v i b r a t i o n a l f r e q u e n c i e s of the l i g a n d upon c o o r d i n a t i o n t o a metal atom, would depend upon the degree of c o v a l e n t i n t e r a c t i o n between the l i g a n d and the metal atom.  I t has a l r e a d y been shown that the C - 0 s t r e t c h i n g  c i e s i n trimethylantimony  carbonate  ching f r e q u e n c i e s observed those observed  make a comparison, was  measured.  t o the C-0 s t r e t -  i n o r g a n i c carbonates,  i n metal-earbonato  trimethylantimony  correspond  complexes.  r a t h e r than t o  The s i t u a t i o n i n  s u l p h a t e seems t o be very s i m i l a r . the i n f r a r e d spectrum  The observed  of dimethyl s u l p h a t e  i n Table 5.4b.  are s i m i l a r t o those o f CIO4 group of C  2 v  their  The i n f r a r e d  a c t i v e v i b r a t i o n a l modes of the s u l p h a t e group of C  Table 2.1b.  In order t o  absorption frequencies with  r e l a t i v e i n t e n s i t i e s are l i s t e d  frequen-  2 v  symmetry  symmetry d e s c r i b e d i n  In dimethyl s u l p h a t e , two o f the f o u r S - 0 bonds i n  the s u l p h a t e group should have double bond c h a r a c t e r w h i l e the remaining character.  two S-0 bonds w i l l e s s e n t i a l l y have s i n g l e bond The  (0=S=0)  and ( 0 - S - O ) v i b r a t i o n s i n dimethyl sulphate  have been r e p o r t e d (89) t o occur at 1400, s t r e t c h ] ; 1200,  [symmetric  [asymmetric  (0=S=0) s t r e t c h ] ;  (0-S-O) s t r e t c h ] ; and 752,[symmetric  875,  (0=S=0)  [asymmetric  (0-S-0) s t r e t c h ] cm" .  The value of the (0-S-O) asymmetric s t r e t c h i n g frequency  1  seems  135 TABLE 5.4b I n f r a r e d A b s o r p t i o n Spectrum Frequency (cm ) -1  3100 1460 1395  Relative intensity  of Dimethyl Sulphate  Assignment  m m s  (SO4 group)  (0=S=0) a s s y m e t r i c s t r e t c h (vg) (0=S=0) symmetric ime (v )  1200  stretch  x  1010 985 825  sh s s  752  (O-S-0)  asymmetric s t r e t c h (vg)  (O-S-0) symmetric (v )  m  stretch  2  615 592  sh m  SO4 r o c k i n g (v^)  573  m  (0=S=0) bend ( A ) )  520 502  sh s  S0  428  m  (0-S-O) bend ( v )  to be erroneous because spectrum cm  - 1  3  rocking ( v )  4  g  4  no band was observed at 875 c m  of dimethyl s u l p h a t e .  - 1  i n the  Instead a band i s observed at 825  and i t i s now suggested t h a t the value of the (O-S-0) •  asymmetric  s t r e t c h i n g frequency i s 825 cm \  The i n f r a r e d  spectrum  of dimethyl s u l p h a t e has not been r e p o r t e d p r e v i o u s l y f o r the potassium bromide r e g i o n . spectrum  From a comparison  of s u l p h u r y l d i f l u o r i d e  (88), the four observed bands i n  t h i s r e g i o n can be a s s i g n e d as f o l l o w s : 573  cm , -1  (0=S=0) bend; 502 c m ,  (O-S-0) bend.  -1  w i t h the i n f r a r e d  S0  592 c m , -1  S 0 rocking; 4  r o c k i n g ; and 428 c m-1, : -1  4  136 The 825  cm  f o u r sulphate a b s o r p t i o n bands at 1285,  observed  -1  i n the spectrum  of trimethylantimony  correspond to the f o u r s u l p h a t e bands at 1395, cm , -1  observed  i n the spectrum  1145,  1200,  950,  and  sulphate  825 and  of dimethyl s u l p h a t e .  752  Therefore,  these bands can be assigned to the same v i b r a t i o n a l modes, i . e . 1285 950  cm , -1  cm"  stretch  S0  , S0  2  asymmetric s t r e t c h ;  2  1145  cm ,  asymmetric s t r e t c h ; and 825  cm , -1  Similarly,  symmetric  S0  2  bend; 495  cm" ,  r o c k i n g ; and 428  1  cm ,  cm" ,  symmetric  S0  -1  r e g i o n i s ; probably due  2  bend.  cm  i s e v i d e n t from  the s u l p h a t e a b s o r p t i o n bands t h a t  sulphate i s l a r g e l y covalent. r e g i o n 600-495 cm" . 1  The  broad  trimethylantimony  asymmetric s t r e t c h being a p p a r e n t l y cm" . 1  The  infrared  spec-  s u l p h a t e i s thus completely c o n s i s t e n t  each group being bonded through  two  groups,  of i t s oxygen atoms t o the  p l a n a r trimethylantimony group, making the antimony atom f i v e  carbonate,  -1  trimethylantimony  w i t h a polymeric s t r u c t u r e c o n t a i n i n g b r i d g i n g s u l p h a t o  ordinated.  cm ,  There i s no a b s o r p t i o n band i n the  masked by the s t r o n g s u l p h a t e band a t 600 trum of trimethylantimony  the  to a l a t t i c e mode. I t  T h i s i n d i c a t e s t h a t the  group i s p l a n a r , the Sb-C  with  r o c k i n g ; 600  1  band i n the 250  -1  stretch;  -the f o u r s u l p h a t e a b s o r p t i o n bands i n  low frequency r e g i o n can be assigned as 650 2  2  (* denotes the oxygen atoms i n v o l v e d i n bonding  antimony atom).  S0  S0  -1  As mentioned i n c o n n e c t i o n with  co-  trimethylantimony  the p o s s i b i l i t y of a monomeric s t r u c t u r e c o n t a i n i n g a  b i d e n t a t e s u l p h a t e group can be r u l e d out due  to the l a r g e s t r a i n  i n v o l v e d i n such a s t r u c t u r e . The potassium s u l p h a t e was  bromide p e l l e t c o n t a i n i n g trimethylantimony  exposed to a i r and no change i n the spectrum  served on s h o r t exposure.  was  ob-  However, a f t e r about f o u r hours exposure  to a i r , a d d i t i o n a l bands due  to i o n i c s u l p h a t e and a band at  137 565 c m  - 1  appeared.  After  twenty-four  hours,  the i n t e n s i t y of  the i o n i c s u l p h a t e bands had i n c r e a s e d c o n s i d e r a b l y while the bands due to the sulphato group became l e s s i n t e n s e . i n the spectrum  of the potassium  T h i s change  bromide p e l l e t of t r i m e t h y l a n -  timony s u l p h a t e , on exposure t o a i r , must be due t o the exchange reaction  between trimethylantimony  bromide.  Long, Doak,and Freedman  asymmetric s t r e t c h i n g o c c u r s a t 564 cm" . 1  frequency  s u l p h a t e and potassium (52) c o n s i d e r that the Sb-C  i n trimethylantimony  sulphate  However, t h i s a b s o r p t i o n i s due to the Sb-C  asymmetric s t r e t c h i n g  v i b r a t i o n of the trimethylantimony  dibromide  (which i s formed i n the p e l l e t ) and not due t o the Sb-C asymmetric s t r e t c h i n g mode of trimethylantimony appears 5.5  only a f t e r the exchange r e a c t i o n  Trimethylantimony  reaction  i n the p e l l e t takes p l a c e .  Chromate  Trimethylantimony  water.  s u l p h a t e because t h i s band  chromate was o b t a i n e d by the m e t a t h e t i c a l  of trimethylantimony The i n f r a r e d spectrum  dibromide  and s i l v e r chromate i n  of t h i s compound was measured on  samples made as m u l l s , as w e l l as on potassium  bromide p e l l e t s .  I d e n t i c a l s p e c t r a were o b t a i n e d by these methods. the observed  spectrum  i s shown i n F i g u r e 5.j^.  A p o r t i o n of  The a b s o r p t i o n  f r e q u e n c i e s , together with t h e i r r e l a t i v e i n t e n s i t i e s and suggested assignments,  are l i s t e d i n Table 5.£>. The a b s o r p t i o n bands at  3040, 2940, 1410, 1230, 852, and 575 c m  - 1  can be assigned t o the  C-H asymmetric s t r e t c h , C-H symmetric s t r e t c h , C-H asymmetric bend, C-H symmetric bend, CHg rock and Sb-C asymmetric respectively. bidden due  stretch,  The weak band at 530 i s probably due to the f o r -  Sb-C asymmetric s t r e t c h i n g mode.  The a b s o r p t i o n bands  t o the chromate group occur a t 964, 940, 838, 700, 420, 390  Me SbCr0 . 3  4  en  100 h  o  80 -  -  CD  ^—  60 -  CD O  o  40 -  -*—  "E CO d  o  20 -  -  F I G U R E 5-5  0 1200  1000  I 6 0 0  _J  I . 4 0 0  I  I 2 0 0  Frequency (cm-') CO  oo  139 TABLE  5.5  I n f r a r e d A b s o r p t i o n Spectrum of Trimethylantimony Chromate Frequency  (cm" ) R e l a t i v e I n t e n s i t y  Assignment  1  3040  vw  C-H asym. s t r .  2940  vw  C-H sym. s t r .  1410  w  C-H asym. bend  1230  m  C-H sym. bend  964  s  Cr0  2  asym. s t r . , (v^g)  940  s  Cr0  2  sym. s t r . , (v^)  852  s  CHg  838  s(sh)  CrOg asym. s t r . , ( ^ )  700  vw, b  Cr0  575  ms  Sb-C asym. s t r .  530  w  Sb-C sym. s t r . ?  420  m  Cr0  4  rock, (v" )  390  m  Cr0  2  bend, (v*g)  355  m  Cr0  4  rock, ( ) )  313  m  Cr0  2  bend, (v^)  b = broad; y = very;  m = medium;  rock 8  s = strong;  2  sym. s t r . , (v'g)  7  Q  sh = shoulder;  w = weak. * denotes the oxygen atoms i n v o l v e d i n bonding.  The assignments f o r the C r 0 comparison with the SO  4  group have been suggested by  group of C  2 v  symmetry.  140 355 and 313 c m .  I t can be n o t i c e d that the i n f r a r e d spectrurm  -1  of the chromate group i n trimethylantimony chromate i s almost i d e n t i c a l t o the chromate spectrum observed i n d i m e t h y l t i n chromate.  The e i g h t observed bands: show c l e a r l y that the symme-  t r y of the chromate group has been lowered from T^ t o lower).  (o  The V g mode of the f r e e chromate i o n i s r e s o l v e d  three s t r o n g  bands a t 964, 940 and 838 c m . -1  into  Though the 838 cm"  band i s p a r t l y masked by the strong band a t 852 c m mode), n e v e r t h e l e s s  r  - 1  (CHg r o c k i n g  the bands a t 852 and 832 show two a b s o r p t i o n  maxima. The strong  Raman a c t i v e mode ^  absorption  a t 700 c m . -1  of the f r e e i o n now shows very The three medium bands a t 420,  390 and 355 cm"'' correspond t o the t r i p l y degenerate mode 0^ of 1  the f r e e i o n and the Raman a c t i v e mode ^2 of the f r e e i o n shows medium a b s o r p t i o n  a t 313 c m . -1  The presence of only one sharp  band of medium i n t e n s i t y i n the r e g i o n 575-500 again , the p l a n a r i t y of the trimethylantimony group.  indicates  The chromate 2—  absorption  i n t h i s compound e v i d e n t l y shows that f r e e CrO^  are not present.  ions  The e n t i r e i n f r a r e d spectrum of t r i m e t h y l a n -  timony chromate i s again  c o n s i s t e n t w i t h a polymeric  structure  i d e n t i c a l t o that proposed f o r trimethylantimony s u l p h a t e . trimethylantimony sulphate,  Like  the i n f r a r e d spectrum of t r i m e t h y l -  antimony chromate d i d not show any change upon exposing the compound t o a i r .  Both the compounds are i n s o l u b l e i n o r g a n i c  s o l v e n t s but s o l u b l e i n water, are p e r f e c t l y s t a b l e , and are non-volatile.  1  141 5.6  Trimethylantimony Oxalate  (CH ) SbC 04 3  3  2  The s t r u c t u r e d e t e r m i n a t i o n of sodium o x a l a t e (136) i n d i c a t e s that the o x a l a t e interatomic  distances n  i o n i s planar  and bond angles: >o  Ov o  C  - r C i  I  ii  124° 0  However, i t i s c o n s i d e r e d symmetry  and has the f o l l o w i n g  I  (137-139) that the o x a l a t e  i o n has Vh  and the d i f f e r e n t v a l u e s f o r the angles C-C-Oi and  C-C-OJI  might be due t o e r r o r s i n the X-ray a n a l y s i s  oxalate  i o n of V  n  symmetry  as shown i n f a b l e 5.6a  (138).  should have twelve normal v i b r a t i o n s  (65c). TABLE 5.6a  2V i b r a t i o n a l Modes of C 04 Ion (Point Group Vh) 2  Vibrational mode  Assignment  Activity  symmetric  (O-C-O) s t r e t c h  CA )  R  CA )  R  CA )  R  symmetric  (A )  Inactive  C-C t o r s i o n  (B )  R  symmetric(O-C-O)  (Big)  ,R  C0  I.R  Out-of-plane CO2 wagging  g  g  g  u  lg  ( lu> B  :  C-C s t r e t c h  2  (O-C-O) bend  stretch  rock or symmetric (C-C- 0)  ^8  (B )  R  Out-of-plane CO2 wagging  0  (B2u)  I.R  Asymmetric  I.R  CO2 rock or symmetric (C-C-•0)  I.R  Symmetric  v  9  2 g  10 ( 2u) B  (B u) 3  ^12  (B u> 3  An  (O-C-O) s t r e t c h  (O-C-O) s t r e t c h  Asymmetric (O-C-O) bend I.R (R = Raman a c t i v e ; I.R = I n f r a r e d a c t i v e )  142 Assignments of the fundamental f r e q u e n c i e s of the o x a l a t e i o n have been r e p o r t e d by s e v e r a l workers (137-139), but there are some d i f f e r e n c e s i n the r e p o r t e d r e s u l t s .  Murata and Kawai  (137) r e p o r t e d t h a t the r u l e of mutual e x c l u s i o n holds i n the Raman and i n f r a r e d s p e c t r a of the o x a l a t e i o n , and t h e r e f o r e the o x a l a t e i o n should have V  symmetry.  n  (139,) have a l s o r e p o r t e d V  n  Schmelz and coworkers  symmetry  f o r the o x a l a t e i o n .  However, these workers have r e p o r t e d two a d d i t i o n a l Raman bands at 1600 and 1310 c m  - 1  i n aqueous s o l u t i o n s of potassium  monohydrate and have assigned them to the v^j(B3 ) u  oxalate  and V g ( B  2 u  )  modes which are f o r b i d d e n i n the Raman spectrum by the s e l e c t i o n rules for symmetry i.e.  symmetry.  Hence these workers concluded  of the o x a l a t e i o n i n aqueous s o l u t i o n i s changed t o V,  the o x a l a t e i o n i s no longer planar^ and V g modes become Raman a c t i v e .  and consequently, the  In a d d i t i o n t o t h i s ,  there i s disagreement i n the assignments of the lower vibrations. frequency  that the  frequency  Murata and Kawai r e p o r t e d the V g ( B i g ) Raman  a t 545 c m  t h i s frequency  - 1  w h i l e Schmelz and coworkers r e p o r t e d t h a t  occurs a t 317 c m . -1  Murata and Kawai, and  Schmelz and coworkers, from a normal c o o r d i n a t e a n a l y s i s , c a l c u l a t e d the frequency cm  - 1  f o r the v ^ ( B 2 ) mode to be 295 and 222 0  u  r e s p e c t i v e l y , w h i l e F u j i t a , Nakamoto and Kobayashi (138)  have a s s i g n e d  the 518 c m  - 1  i n f r a r e d band to t h i s mode.  Schmelz  and coworkers have a l s o r e p o r t e d a s t r o n g i n f r a r e d band at 514 cm it.  - 1  i n sodium o x a l a t e but have not suggested  an assignment f o r  In view of these c o n f l i c t i n g r e s u l t s the i n f r a r e d spectrum  of sodium o x a l a t e was measured. agreement with  The observed  v a l u e s are i n  the values r e p o r t e d by F u j i t a , Nakamoto and  143 Kobayashi.  T h e r e f o r e the assignments made by F u j i t a , Nakamoto  and Kobayashi are p r e f e r r e d and are recorded i n Table 5.6b. TABLE 5.6b _1 V i b r a t i o n a l Frequencies (cm ) of • Vibration mode  *1 ^2 ^3 ^4 ^5 ^6  I  o  n  Raman (Aqueous solution)  Infrared XSolid)  1485, 1450  Inactive  Symmetric  898  Inactive  (C-C) s t r e t c h  443  Inactive  Symmetric  Inactive  Inactive  —  1664  Inactive  Asymmetric  (C-0) s t r e t c h  545  Inactive  Asymmetric  (C-C-0) bend  (C-0) s t r e t c h  Inactive  ^7  2^2^4  Assignment (C-0) s t r e t c h  (0-C-O) bend  —  Inactive  ^8 Inactive  1630  Asymmetric  V  Inactive  518  Symmetric  (C-C-0) bend  vii  Inactive  1335,1316  Symmetric  (C-0) s t r e t c h  12  Inactive  768  Asymmetric  v  (0-C-O) bend  The o x a l a t e group i s a very common l i g a n d and numerous metal o x a l a t o complexes are r e p o r t e d i n the l i t e r a t u r e  (140).  In metal o x a l a t o complexes i n which the o x a l a t e group i s b i dentate  (with u n i d e n t a t e c a r b o x y l i c groups), arid i n c i s d i a k y l  o x a l a t e s , the symmetry of the o x a l a t e group i s lowered to C  2 v  as shown below:  144  C  -C  A  I  I  -Qf  ——0"l  —fs-  (01 r e p r e s e n t s the oxygen atoms i n v o l v e d i n bonding.) The c o r r e l a t i o n between the p o i n t groups V shown i n Table 5.6c.  n  and C 2  Thus an o x a l a t o group of  symmetry  have ten i n f r a r e d a c t i v e fundamental v i b r a t i o n s . s p e c t r a of m e t a l - o x a l a t o workers (47d).  (138) i s  V  The i n f r a r e d  complexes have been s t u d i e d by s e v e r a l  F u j i t a , M a r t e l l , and Nakamoto (141) have done a  normal c o o r d i n a t e a n a l y s i s f o r metal-oxalato-complexes, Urey-Bradley  f o r c e f i e l d approximations.  using  The o x a l a t e group a c t s  as c h e l a t i n g l i g a n d i n these complexes forming chelate ring.  will  a four membered  The r e s u l t s of F u i t a , M a r t e l l and Nakamoto show  strong c o u p l i n g between v a r i o u s v i b r a t i o n a l modes due to the presence of the c h e l a t e r i n g . both  However,  i t i s expected  that i f  the 0 j oxygen atoms i n the o x a l a t e group p a r t i c i p a t e i n  bonding, the C - 0 i bond length w i l l i n c r e a s e and the C - O n bond w i l l be shortened, C-On  r e s u l t i n g i n the s h i f t s of the C - 0 i and  s t r e t c h i n g f r e q u e n c i e s to lower and higher  respectively.  An X-ray s t r u c t u r e d e t e r m i n a t i o n of  K^rC204(H 0) "]3H 0 2  frequencies  2  2  (142) i n d i c a t e s that the two C-^Oj bonds  coordinated two C - O u  to the metal atom are lengthened (1.39^) and the o bonds shortened ( 1 . 1 7 A ) . In metal-oxalato complexes  the f r e q u e n c i e s of the C - O J I cm  -1  region)  stretching vibrations (1700-1600  i n c r e a s e , and those of the C-Oj  ( 1 4 5 0 - 1 3 5 0 cm  -1  and 1 3 0 0 - 1 2 0 0 c m  -1  s t r e t c h i n g vibra"  regions) decrease  as the  145  TABLE 5.6c The V i b r a t i o n a l Modes of Th® Free Oxalate Ion ( V Symmetry h  and The Oxalato Group ( C v  3  A  1 A  2  Symmetry)  V  Assignment eim C  h 3 A  (R)  g  (Inactive)  u  2  B  l g  1  B  l u  1  B  2 g  2  B  2 u  2  B  3 u  X  1 A  2  (R,I.R)  V (C-O),  S  (R)  v  1 B  2  Out-of-plane  A  2  (I.R)  2 A  x  H.R)  2 B  (R)  1  1  ;  sym.  Out-of-plane v(C-O),  (I.R)  (C-C),  V  (0-C-O)  2 B i (R,I.R)  (R)  2  (R,I.R)  asym.  $(C-C-0)  Out-of-plane  (R) (R,I.R)  v ( C - O ) ,• sym. S ( C - C - O )  (R,I.R)  v ( C - O ) , asym.  §(0-C-O)  frequency of the metal-oxygen s t r e t c h i n g v i b r a t i o n i n c r e a s e s . In c i s dimethyl o x a l a t e , each O i oxygen atom i n the o x a l a t e group i s c o v a l e n t l y bonded t o a methyl group and the C-On  and C - O i s t r e t c h i n g f r e q u e n c i e s appear  1325,  1165 cm  s h i f t e d , e.g.  - 1  respectively.  the ( i 0 - C - 0 n )  (B^) f r e q u e n c i e s appear the  C - C  stretch  Other  at 1 7 7 6 ,  f r e q u e n c i e s are a l s o  bend (A^) and the  bend  (JO-C-OJI)  at 4 0 4 and 8 5 1 cm"" r e s p e c t i v e l y and  (Ai) appears  1  at  862  cm"  1  A p o r t i o n of the i n f r a r e d spectrum o x a l a t e i s shown i n F i g u r e 5 v 6 ,  (139).  of trimethylantimony  and the f r e q u e n c i e s , together  with t h e i r i n t e n s i t i e s and probable assignments Table 5 . 6 d .  1 7 7 0 and  are l i s t e d i n  The s p e c t r a were o b t a i n e d on samples made as  m u l l s , as w e l l as on potassium  bromide p e l l e t s .  methods gave i d e n t i c a l s p e c t r a . of the spectrum  Both the  The trimethylantimony p a r t  can be e a s i l y assigned, i . e .  3035  cm , -1  C - H  Me SbC 0 3  2  4  iOOh  2000  1800  1600  1400  1200  1000  Frequency ( c m ) - 1  800  600  400  200  147 TABLE 5.6d I n f r a r e d A b s o r p t i o n Spectrum of Trimethylantimony Frequency  (cm" ) R e l a t i v e 1  Intensity  Oxalate  Assignment  3035  w  C-H asym. s t r .  2950  m  C-H sym. s t r .  2570  w  1665  vs  ( C - 0 ) s t r . , (B-L)  1620  s, sh  (C-OJJ)  1375  m  (C-0j) s t r . ,  vs  (C-Oj)  n  str.-, ( A ) x  (Ai)  1250 1227  s t r . , (B-L)  1215 855  CHg rock  827  s, sh  C-C s t r . , ( A )  755  s  (Oj.-C-Pu) asym.  x  bend, ( B ^ 585  w  (C-C-O) asym. bend, ( B ^  575  m  Sb-C asym. s t r .  525  s  (C-C-O) sym. bend, (A±)  420  m = medium;  (Oj-C-Ou) sym. bend, (A^)  s = s t r o n g ; sh = shoulder; v = very; w = weak.  Gj denotes oxygen atomsinvolved i n bonding.  148 asymmetric s t r e t c h ; 2950 cm ^ C-H symmetric s t r e t c h ; 855 c m -1  CHg  rock; and 575 c m , Sb-C asymmetric s t r e t c h .  Absorption  -1  bands due t o the o x a l a t e group occur a t 1665, 1250-1215,  827, 755, 585, 525 and 420 cm" .  - 1  1620,  1375,  The i n f r a r e d  1  a b s o r p t i o n bands i n sodium o x a l a t e occur a t 1640(s,b), 1420(w), 1340-1315(s,b), 777(s,sp)  and 515(s,b) em" . 1  By comparison with the spectrum it  can.be seen that the spectrum  of the f r e e o x a l a t e i o n  of trimethylantimony  oxalate  2-  i s q u i t e d i f f e r e n t from t h a t of the C2O4 bands a t 1665 and 1250-1215 c m C-0i  - 1  correspond  s t r e t c h i n g f r e q u e n c i e s observed  i o n . The a b s o r p t i o n t o the C - 0 u and  i n metal-oxalato  complexes.  2-  Moreover the Raman a c t i v e modes f o r the f r e e C2O4  i o n now  appear w i t h moderate or s t r o n g i n t e n s i t y .  The o x a l a t e  i n trimethylantimony  i n accord with the  presence  o x a l a t e i s completely  o f an o x a l a t e group of C  2 v  symmetry.  c o n c l u s i v e can be s a i d about the presence s t r e t c h due to the presence  Though nothing  of the Sb-C symmetric  of a s t r o n g band i n the 525 cm"  r e g i o n , i t may be noted t h a t the Sb-C asymmetric frequency  i n t h i s compound appears  and with almost carbonate,  spectrum  1  stretching  i n the same frequency r e g i o n  the same i n t e n s i t y as i n trimethylantimony  the d i n i t r a t e , and the dibromide, which  indicates  that the geometry o f the trimethylantimony group i n t r i m e t h y l antimony o x a l a t e i s not s i g n i f i c a n t l y i n these l a t t e r compounds.  d i f f e r e n t from t h a t found  C o n s i d e r i n g the p l a n a r i t y of the  trimethylantimony group and the C 2 v symmetry of the o x a l a t e group, i t i s suggested  that the o x a l a t e groups act as b r i d g i n g  l i g a n d s between p l a n a r trimethylantimony groups making the antimony atom f i v e c o o r d i n a t e .  T h e r e f o r e a polymeric s t r u c t u r e  149 s i m i l a r t o t h a t proposed f o r trimethylantimony  carbonate,  sulphate and chromate can a l s o be proposed f o r the o x a l a t e . The a l t e r n a t i v e monomeric s t r u c t u r e c o n t a i n i n g a c h e l a t e r i n g would i n v o l v e a c o n s i d e r a b l e d i s t o r t i o n of the trimethylantimony to a non-planar arrangement as w e l l as lengthening bond t o a great extent;  group  of the C-C  i t i s very u n l i k e l y that such a s t r u c -  t u r e c o u l d be p o s s i b l e .  L i k e trimethylantimbny  sulphate and  chromate, the o x a l a t e i s i n s o l u b l e i n o r g a n i c s o l v e n t s and i s non-volatile. In a polymeric  structure i n v o l v i n g planar  trimethylantimony  groups and b r i d g i n g o x a l a t o groups, the c o u p l i n g between the v a r i o u s v i b r a t i o n a l modes of the o x a l a t e group may not be so s t r o n g as compared with m e t a l - o x a l a t o chelate ring.  Therefore  complexes c o n t a i n i n g a  the f ollowing;.assignments,  based on  the c o r r e l a t i o n between the v i b r a t i o n a l modes o f the f r e e o x a l a t e i o n and the c o o r d i n a t e d o x a l a t o group of C are suggested  symmetry,  f o r the a b s o r p t i o n f r e q u e n c i e s of the o x a l a t e  group i n trimethylantimony (a)  2 v  oxalate:  The bands at 1375,  827 and 420  cm  - 1  correspond  to the three Raman a c t i v e modes of A^g s p e c i e s i n the o x a l a t e ion  ( i . e . 1485-1450,  t h e r e f o r e assigned (A^)  898 and 443  cm" ). 1  to the C - O j s t r e t c h  and the symmetric  (Oj-C-0n)  These bands are (A^), the C-C s t r e t c h  bend (A.]_) r e s p e c t i v e l y .  (b) The two Raman a c t i v e modes of B^g s p e c i e s i n the Vh p o i n t group become i n f r a r e d a c t i v e modes of B^ s p e c i e s i n the C  2 v  p o i n t group, t h e r e f o r e the bands at 1665  are assigned  to the C - O . n s t r e t c h  (C-C-0) bend (Bj_) r e s p e c t i v e l y .  and 585 cm~l  (B^) and the asymmetric  i5o;> (c) The bands at 1620 i n f r a r e d a c t i v e modes (B2 )  stretch  -1  correspond to the  at 1640-1630 and 515 c m  U  oxalate ion.  and 525 c m  -1  of the  T h e r e f o r e these bands are a s s i g n e d to the  (Ai) and the symmetric  (C-C-O) bend (A^)  (d) The bands at 1250-1215, and 755 c m the two i n f r a r e d a c t i v e assigned to the C-Oj  -1  two  (C-0jj)  respectively. correspond to  modes of the f r e e i o n and are  stretch  (B]^) , and the asymmetric  (l0-C-0n)  bend (Bi) r e s p e c t i v e l y . 5.7  Trimethylantimony B i s ( t e t r a f l u o r o b o r a t e )  (CH ) Sb(BF ) 3  3  4  2  The m e t a t h e t i c a l r e a c t i o n between trimethylantimony dibromide and s i l v e r  t e t r a f l u o r o b o r a t e i n methanol  i n s t a n t a n e o u s p r e c i p i t a t i o n of s i l v e r bromide. the methanol,  a white s o l i d was  obtained.  c o n t a i n e d boron t r i f l u o r i d e which was spectrum and q u a l i t a t i v e t e s t s .  resulted i n  Upon removal of  The r e c o v e r e d methanol  i d e n t i f i e d by i t s i n f r a r e d  The i n f r a r e d spectrum of the  s o l i d i n d i c a t e d the presence of the t e t r a f l u o r o b o r a t e group, but the a n a l y t i c a l r e s u l t s do not correspond to An X-ray powder photograph  (CH ) Sb(BF ) . 3  3  4  2  of the s o l i d showed the presence of  trimethylantimony d i f l u o r i d e .  On the b a s i s of s p e c t r o s c o p i c ,  a n a l y t i c a l , and X-ray powder photographic r e s u l t s , i t i s conc l u d e d that the s o l i d i s an approximately 1:1 mixture of trimethylantimony b i s ( t e t r a f l u o r o b o r a t e ) and t r i m e t h y l a n t i m o n y difluoride.  The mixture sublimed r e a d i l y at 50° under vacuum  and the i n f r a r e d spectrum, photographs  a n a l y t i c a l r e s u l t s and X-ray powder  of the sublimed product were i d e n t i c a l to that of  the unsublimed mixture, i n d i c a t i n g t h a t no f u r t h e r had o c c u r r e d during s u b l i m a t i o n .  decomposition  151 These r e s u l t s can be e x p l a i n e d i n the f o l l o w i n g manner: ( C H ) S b B r > 2AgBF 3  3  2  2 4> (CH )' .Sb ( s o l v a t e d )  CHgOH 4  3  3  + 2BF ~ + 2AgBr  . . . (1)  4  2+ (CH ) Sb ( s o l v a t e d ) + 2BF 3  3  -solvent —>  4  (CH ) SbF 3  + 2BF  In  the i n f r a r e d a b s o r p t i o n spectrum  bands were observed  i n the 4000-1500 c m  - 1  3  2  . . .(2)  3  of the mixture, no r e g i o n except weak  bands a t 3050-2900 cm-1 due to C-H s t r e t c h i n g v i b r a t i o n s .  The  a b s o r p t i o n bands ( i n 1500-250 c m  their  - 1  r e g i o n ) , together w i t h  r e l a t i v e i n t e n s i t i e s and suggested  assignments,  are l i s t e d i n  Table 5.7 and p a r t of the spectrum  i s shown i n F i g u r e 5.7. The  a b s o r p t i o n bands at 1410, 1235, 885 and 587 are a s s o c i a t e d with the trimethylantimony group and can be assigned as 1410 c m , -1  C-H asymmetric bend; 1235 c m , C-H symmetric bend; 880 c m , -1  CH  -1  rock; and 587 c m , Sb-C asymmetric s t r e t c h . -1  3  1287, cm  - 1  The bands a t  1150, 1100, 1053, 1040, 1015, 760, 572, 545, 515 and 400 can be a t t r i b u t e d t o the t e t r a f l u o r o b o r a t e group.  a b s o r p t i o n bands due t o trimethylantimony expected  The  d i f l u o r i d e would be  to occur a t 1415, 1235, 855, 586 and 475 c m .  Apparently  -1  the bands at 855 and 475 c m  bands a t 880 and 400 c m . -1  of a band i n t h i s r e g i o n .  s t r o n g bands at 1100 and 1053 c m  corresponds  mode ^  3  of B F  4  are masked by s t r o n g  The broad shoulder i n the 475, c m  r e g i o n i n d i c a t e s the presence  degenerate  - 1  - 1  correspond  t o the t r i p l y  i o n and the weak band a t 760 cm"-'-,  t o the Raman a c t i v e mode v , of the f r e e i o n .  the low frequency  The  1  x?  In  r e g i o n , the bands a t 572 and 515 cm~l are  - 1  Frequency ( c m ) -1  CJl  TABLE 5.7 I n f r a r e d A b s o r p t i o n Spectrum of The Mixture of Trimethylantimony Bis(tetrafluoroborate) Frequency  (cm" ) R e l a t i v e  and Trimethylantimony Intensity  1  Difluoride Assignment  C-H asym. bend  1410  w  1287  m  1235  m  1150  sh  1100  s  B-F s t r . ,  1053  s  BFg sym. str.,(v*-j_)  1040  sh  1015  sh  C-H sym. bend  )  880  s  CH3 rock  760  w  B-F* s t r . , ( v )  587  ms  Sb-C asym.  572  s  BFg asym.bend,(0 )  545  w  515  ms  BFg sym. bend, (\)g)  475  sh  S-F asym. s t r . ,  2  str. 5  [(CH3)3SbF2] 400 m = medium;  BF  s s = strong;  sh = shoulder;  * F r e p r e s e n t s the f l u o r i n e atom i n v o l v e d  4  rocking,  v = very;  (0 ) g  w = weak.  i n bonding.  154  probably two components of the t r i p l y broad band a t 4 0 0 c m mode v  of the f r e e  2  On  - 1  ion.  exposing the mixture t o a i r , the a b s o r p t i o n bands group showed marked changes.  bands a t 1 1 0 0 and 1 0 5 3 were r e p l a c e d  band a t 1 0 5 5 cm" The  1  - 1  by a very strong  broad  which i s c h a r a c t e r i s t i c of the f r e e BF4"" i o n .  bands at 7 6 0 and 5 7 3 c m  400 cm  The  may be c o r r e l a t e d with the Raman a c t i v e  a t t r i b u t e d t o the t e t r a f l u o r o b o r a t e The  degenerate mode ^ 4 .  - 1  disappeared and the i n t e n s i t y of  band was d i m i n i s h e d .  New bands appeared i n the 5 0 0 - 4 5 0  region. The  spectroscopic  r e s u l t s thus suggest that  antimony b i s ( t e t r a f l u o r o b o r a t e ) that  the t e t r a f l u o r o b o r a t e  trimethyl-  i s present i n the mixture and  groups are c o o r d i n a t e d to the  trimethylantimony group through, one of the f l u o r i n e atoms. The  volatility  of the mixture a l s o i n d i c a t e s a n o n - i o n i c con-  s t i t u t i o n f o r trimethylantimony C o n s i d e r i n g the r e s u l t i n g C$ group, the f o l l o w i n g the  tetrafluoroborate  v  bis(tetrafluoroborate).  symmetry o f the t e t r a f l u o r o b o r a t e  assignments f o r the a b s o r p t i o n bands of groups a r e suggested:  1 1 0 0 c m , B-F -1  s t r e t c h v^ ( E ) ; 1 0 5 3 cm" , B F 3 symmetric s t r e t c h v^A-^); 7 6 0 1  c m , B-F* s t r e t c h ^ ( A ^ ) ; -1  T) (E); 5  rocking  5 7 2 c m , B F 3 asymmetric bend -1  5 1 5 c m , B F 3 symmetric bend vg (A].) ; and 4 0 0 cm" , -1  mode v ^ ( E ) .  in coordination.)  1  (F* r e p r e s e n t s the f l u o r i n e atom  These assignments have been suggested by  comparison with the v i b r a t i o n a l assignments r e p o r t e d f o r the p e r c h l o r y l f l u o r i d e , 5.8  (143,144)  CIO3F.  Trimethylantimony Hexaf l u o r o s i l i c a t e The  involved  hexafluorosilicate ion (SiFg)*  (CH^^SbSiFg i s o c t a h e d r a l and  155 belongs  to p o i n t group 0 . n  The v i b r a t i o n a l modes of an o c t a -  h e d r a l group have a l r e a d y been d i s c u s s e d .  Only  three fundamental  v i b r a t i o n a l f r e q u e n c i e s v^, V g , and V4 of the S i F g " i o n are known. Raman a c t i v e frequency v^ occurs at 656 red a c t i v e f r e q u e n c i e s respectively  (128).  cm"  (145)  1  v*g and v" occur at 726 4  C r y s t a l l i n e potassium  and the  and 480  h e x a f l u o r o s i l i c a t e , the  about 20 cm"  1  (125).  1  and ammonium hexa-  f l u o r o s i l i c a t e s show no s p l i t t i n g of the degenerate i n barium  cm"  infra-  modes but,  mode shows a s p l i t t i n g  of  2No example of c o o r d i n a t i o n by the SiFg  i o n has been r e p o r t e d so f a r . The m e t a t h e t i c a l r e a c t i o n between dibromide  trimethylantimony  and s i l v e r h e x a f l u o r o s i l i c a t e i n methanol r e s u l t e d i n  instantaneous p r e c i p i t a t i o n of s i l v e r bromide.  Upon removal  of the s o l v e n t under vacuum, a white c r y s t a l l i n e , s o l i d was spectrum  obtained.  X-ray  hygroscopic  powder photographic d a t a i n f r a r e d 3  and a n a l y t i c a l r e s u l t s of the s o l i d showed i t to be a  mixture of trimethylantimony h e x a f l u o r o s i l i c a t e and  trimethyl-  antimony d i f l u o r i d e c o n t a i n i n g about 52 percent h e x a f l u o r o s i l i c a t e and 48 percent d i f l u o r i d e .  The  recovered methanol  h i g h l y a c i d i c and c o n t a i n e d s i l i c o n and f l u o r i n e . sublimed  The  r e a d i l y under vacuum at 50° and the i n f r a r e d  was  solid spectrum,  X-ray powder photograph and a n a l y t i c a l r e s u l t s of the subl i m a t e were i d e n t i c a l to those of unsublimed that no f u r t h e r decomposition The p a r t i a l decomposition  mixture  indicating  had o c c u r r e d during s u b l i m a t i o n .  of trimethylantimony  hexafluorosilicate  can be e x p l a i n e d i n a manner s i m i l a r to t h a t suggested p a r t i a l decomposition borate) , i . e.  of the trimethylantimony  f o r the  bis(tetrafluoro-  156 CH 0H 3  (CH ) SbBr 3  3  +• A g S i F  2  2  6  2 3  9+ o (CH ) Sb^ (solvated) + S i F ^ "  + SiF  The  i n Table 5.8.  no  Part  of the  The  475  3  C-H  rock, and cm  stretching  2  ...(2)  4  vibrations  a b s o r p t i o n bands,  i n the  880-855, and  asymmetric bend, the C-H  the  band can  1  1240,  Sb-C  region  be a t t r i b u t e d to the  v i b r a t i o n of the  5.8. 3050-2900  region. cm"  1  The  can  be  symmetric bend, respectively.  Sb-F  asymmetric  trimethylantimony d i f l u o r i d e .  the h e x a f l u o r o s i l i c a t e group. change i n the  1  586  asymmetric s t r e t c h  remaining medium or strong bands are  the  3  bands were observed i n the 4000-1500 cm"  assigned to the CH  3  spectrum i s shown i n F i g u r e  stretching  a b s o r p t i o n bands at 1410,  the  ...(1)  (CH ) SbF  r e l a t i v e i n t e n s i t i e s of the  Except f o r the. C-H -1  " + 2AgBr  i n f r a r e d spectrum of the mixture i s recorded,  together with the  cm ,  2 6  solvent —>  3  (solvated)  3  + SiF  3  +  -> (CH ) Sb^  This  therefore  associated  i s further  supported  spectrum when the mixture was  The with by  exposed to a i r .  A sample of the mixture exposed to a i r showed c h a r a c t e r i s t i c i n f r a r e d a b s o r p t i o n bands of the band at 735 spectroscopic  cm~l  and  2— SiFg i o n , i . e . a strong broad  a strong band i n the 480  r e s u l t s i n d i c a t e the presence of  h e x a f l u o r o s i l i c a t e i n the mixture. spectrum i n the from that of the  Since the  cm  -1  region.  Thus  trimethylantimony hexafluorosilicate  anhydrous mixture i s s i g n i f i c a n t l y d i f f e r e n t 2SiFg  i o n , i t can  be  concluded that  trimethyl-  antimony h e x a f l u o r o s i l i c a t e i s n o n - i o n i c , but on exposure to a i r , 2i t i s h y d r o l y s e d ,to produce f r e e SiFg ion. The v o l a t i l i t y of  158TABLE 5.8 I n f r a r e d A b s o r p t i o n Spectrum of The Mixture of Trimethylantimony H e x a f l u o r o s i l i c a t e and Trimethylantimony Frequency  (cm" ) R e l a t i v e 1  50-2900  w  1495  m  1410  w  1288  ms  1240  w  1057  w  997  ms  880  sh  855  s  785  s  720  m  586  m  555  s  533  w  475  s  445  m  350  m  m = medium;  s = strong;  Intensity  Assignment C-H s t r .  C-H asym. bend  C-H sym. bend  ) ) )  CH  0  o  rock  Sb-C asym. s t r .  Sb-F  sh - shoulder; v = very;  No assignments are suggested SiFg group.  Difluoride  asym. s t r .  w = weak.  f o r the a b s o r p t i o n bands due t o the  159 the mixture a l s o i n d i c a t e s a n o n - i o n i c c o n s t i t u t i o n .  However,  due to the presence of a l a r g e number of bands i n the  spectrum,  no c o n c l u s i o n s can be reached about the p o s s i b l e s t e r e o c h e m i s t r y of trimethylantimony h e x a f l u o r o s i l i c a t e . 5.9  Trimethylantimony B i s ( h e x a f l u o r o a n t i m o n a t e ) T h i s compound was  white s o l i d , antimony  (CHg)gSb(SbFg)  2  obtained, as an extremely h y g r o s c o p i c  by the m e t a t h e t i c a l r e a c t i o n between t r i m e t h y l -  dibromide and s i l v e r hexafluoroantimonate i n l i q u i d  sulphur d i o x i d e .  X-ray powder photographs  of the s o l i d d i d not  show any l i n e s due to e i t h e r trimethylantimony d i f l u o r i d e or the dibromide; however, the f l u o r i n e percentage i n the sample was  found to be f i v e percent lower than the c a l c u l a t e d v a l u e .  The substance r e a c t e d r a p i d l y with s a l t windows, but r e p r o d u c i b l e s p e c t r a c o u l d be o b t a i n e d by using s i l v e r c h l o r i d e and polythene sheets. sample,  A p o r t i o n of the i n f r a r e d spectrum, i s shown i n F i g u r e 5 9. f  1180(m) and 880(m) c m . -1  the CHg  r o c k i n g mode.  on a n u j o l m u l l  Other bands were observed at  The 880 c m  -1  band can be a s s i g n e d to  The other band which can be  to the trimethylantimony group occurs at 585 c m assigned to the Sb-C  asymmetric  stretch.  -1  attributed and can be  The r e s t of the bands  must t h e r e f o r e be a s s o c i a t e d w i t h the hexafluoroantimonate group. As can be seen from F i g u r e 5.9,  the spectrum  i n t h i s r e g i o n shows  a d d i t i o n a l bands of medium i n t e n s i t y at 550 and 445 cm , -1  shoulder i n the 370 c m  -1  region.  Moreover,  and a  the \)g mode which —1  appears as a broad, symmetrical band at 660 cm trum of the SbFg i o n , i s now 640  cm . -1  split,  As d e s c r i b e d e a r l i e r ,  A  i n the spec-  and shows peaks at 665  almost s i m i l a r  and  spectroscopic  161 f e a t u r e s are observed  for dimethyltin bis(hexafluoroantimonate).  However, i n d i m e t h y l t i n b i s ( h e x a f l u o r o a n t i m o n a t e ) , the shows three peaks.  Thus i t appears  mode  t h a t , i n trimethylantimony  b i s ( h e x a f l u o r o a n t i m o n a t e ) , t h e o c t a h e d r a l symmetry of the SbFg group i s lowered  to probably C^  v  or D ^ .  The almost  similar  s p e c t r o s c o p i c e f f e c t s observed f o r t r i m e t h y l t i n h e x a f l u o r o a n t i monate, d i m e t h y l t i n b i s ( h e x a f l u o r o a n t i m o n a t e ) , and t r i m e t h y l antimony b i s ( h e x a f l u o r o a n t i m o n a t e ) s t r o n g l y suggest that s p e c t r o s c o p i c e f f e c t s are due to c o o r d i n a t i o n .  This i s further  supported by the change i n the i n f r a r e d spectrum anhydrous compound was exposed to a i r .  these  when the  The bands a t 1180,  and 445 disappeared, and the ^3 mode showed a s i n g l e  550,  broad  symmetrical peak a t 660 c m . -1  5.10  Trimethylantimony(V)  2 D e r i v a t i v e of B ^ g C l ^ 2—  The  trimethylantimony(V) d e r i v a t i v e of i 2 ^ 1 2 B  o b t a i n e d as a crimson red, h y g r o s c o p i c s o l i d . s o l i d changed to white on exposure water or .methanol vapour.  the spectrum  a  s  The c o l o u r of the  of the anhydrous s o l i d to  However, the recovered  from these s o l u t i o n s was always c o l o u r e d . the anhydrous s o l i d  w  The aqueous or methanol s o l u t i o n of  MegSbB-j^Clig was a l s o c o l o u r l e s s .  of  1  The i n f r a r e d  solid  spectrum  i s recorded i n Table 5.10 and p a r t of  i s shown i n F i g u r e 5.10.  The a b s o r p t i o n bands due  to the trimethylantimony group appear a t 3000-2900,(C-H s t r e t c h ) ; 1405,  (C-H asymmetric bend);  1245, (C-H symmetric bend); 865,  (CH3 r o c k ) ; and 570, (Sb-C asymmetric s t r e t c h ) c m . -1  The  a b s o r p t i o n bands at 1030', 1000, 827, 532, 450, and 320 cm" can be a t t r i b u t e d to the &\2^\2  g  r o u  P«  1  By comparing the spec-  1200  1000  800  600  Frequency (cm ) -1  400  200  163  TABLE 5.10 I n f r a r e d A b s o r p t i o n Spectrum of Me3SbBi2Cli2  Frequency (cm- ) 1  Relative intensity  3000 - 2900  Assignment  vw  C-H s t r e t c h  1405  vw  C-H asymmetric  bend  1307  vw  1245  w  C-H asymmetric  bend  1030  vs  1000  m  865  s  827  s  570  w  532  vs  450  m, b  320  m, b  b = broad;  m = medium;  CH  3  rock  Sb-C asymmetric  s = strong;  v = very;  stretch  w = weak  No assignments have been suggested f o r the a b s o r p t i o n bands due to the B12CI12 group  164 trum of M e 3 S b B C l 12 with that of A g ^ B i g C l - ^ i t becomes e v i d e n t 1 2  that inMe^SbB^2Cli2 There  i s no a p p r e c i a b l e change i n the trimethylantimony p a r t of  the spectrum it  the symmetry of B ^ C l - ^ group i s reduced.  as compared w i t h trimethylantimony dibromide,  is difficult  to determine whether the Sb-C  i s a l s o present i n the spectrum The bands at 827, 450 MegSbB-j^Cl^ ^°  a  i  r  ^  o r  ^  stretch  of M e g S b B ^ C l ^ .  and 320  hours.  symmetric  though  cm  -1  disappeared on exposing  Thus i t i s reasonable to  conclude that the symmetry of the B 1 2 C I 1 2 group i s a p p r e c i a b l y d i s t o r t e d i n MegSbB^Cl-j^ and that t h i s e f f e c t i s most l i k e l y due  to the c o o r d i n a t i o n between MegSb and B ^ C l ^ g  groups.  ;  165 CHAPTER 6 CONCLUSION  The r e s u l t s of t h i s i n v e s t i g a t i o n demonstrate the e x i s t e n c e of an i n t e n s e i n t e r a c t i o n between the organometal group, i . e . (CgH(j)gSn, (CH3> Sn, (CHgJgSn, 3  or ( C ^ ^ S b  and the a n i o n i c  i n a l l the o r g a n o t i n ( I V ) or organoantimony(V) studied.  acid  group  derivatives  The decomposition of the organometal d e r i v a t i v e s of  s t r o n g Lewis a c i d s such as BFg and S i F ^ , i n t o the organometal f l u o r i d e and the c o r r e s p o n d i n g Lewis a c i d , i n d i c a t e s t h i s strong interaction.  The i n f r a r e d s p e c t r a of a l l the compounds u n i f o r m l y  show marked changes i n the spectrum of the a n i o n i c group, i . e . significantly  l a r g e s p l i t t i n g s of the degenerate modes and the  appearance of the Raman a c t i v e modes w i t h moderate intensities.  From a comparison w i t h the i n f r a r e d  to strong spectroscopic  data of a l a r g e number of c o r r e s p o n d i n g i o n i c s a l t s ,  i t becomes  obvious that these s p e c t r o s c o p i c o b s e r v a t i o n s cannot be a t t r i b u t e d to c r y s t a l f i e l d e f f e c t s .  In view of the p o s s i b i l i t y of unknown  factors:, i n i n t e r p r e t i n g the s p e c t r a of s o l i d s , s i n g l e spectrum may  be open t o q u e s t i o n .  the r e s u l t s of a  However, the p r o b a b i l i t y  of almost i d e n t i c a l e f f e c t s o c c u r r i n g i n a wide v a r i e t y of compounds i s e x c e e d i n g l y s l i g h t .  The observed s p e c t r o s c o p i c  can t h e r e f o r e be a t t r i b u t e d to c o o r d i n a t i o n or p a r t i a l  effects  covalent  bond f o r m a t i o n between the organometal and the a n i o n i c groups. A l t e r n a t i v e l y , a very strong p o l a r i z a t i o n by the organometal c a t i o n may  produce these e f f e c t s .  However, there i s no obvious  reason why  these simple c a t i o n s of low charge d e n s i t y should be  more p o l a r i z i n g than any other known c a t i o n .  Consequently, i t  166 i s concluded that these s p e c t r o s c o p i c a t i o n or p a r t i a l c o v a l e n t the a n i o n i c groups.  e f f e c t s are due  to  coordin-  bonding between the organometal  Unfortunately,  and  there i s no obvious experimen-  t a l method which w i l l d i s t i n g u i s h unambiguously between terms such as  'strong p o l a r i z a t i o n ' , ' p a r t i a l covalent  coordination.  bonding  1  and  However, none of these compounds appear to 1  contain  f r e e organometal c a t i o n s , i . e . ( C e H s ^ S r i * " , (CHg^Sn" " , (CHg^Sn " " 4  2  1  2 + or  (CHg) Sb  , although i t must be s t r e s s e d that the bonding  3  between the metal atom and i n the same c o v a l e n t ganic groups.  The  the a n i o n i c group cannot be  terms as that between the metal and  bonding between the metal atom and  group i s presumably l e s s c o v a l e n t The  described the  the  or-  anionic  than the metal-carbon bond.  i n s t a b i l i t y of the o r g a n o t i n  c a t i o n s i n the s o l i d  state  probably a r i s e s p a r t l y from the tendency of the t i n atom to increase  i t s coordination  g a t i o n , as w e l l as other  number. recent  The  f i n d i n g s of t h i s  s t u d i e s on o r g a n o t i n  investi-  compounds,  demonstrate the tendency of the t i n atom to i n c r e a s e i t s coord i n a t i o n r e a d i l y to f i v e or s i x . has  been r e p o r t e d  (146)  T e t r a k i s ( 8 - q u i n o l i n a t o ) t i n (IV)'-  to be an e i g h t c o o r d i n a t e  t i n ( I V ) compound.  In t r i m e t h y l t i n ( I V ) d e r i v a t i v e s f i v e c o o r d i n a t i o n of the t i n atom i s a t t a i n e d through a polymeric s t r u c t u r e i n v o l v i n g b r i d g i n g a n i o n i c groups and  a t r i g o n a l bipyramidal  the t i n atom. Dimethyltin.(IV)  c o n f i g u r a t i o n around  d e r i v a t i v e s are apparently  t e t r a h e d r a l or s i x c o o r d i n a t e d ,  and  either  polymeric s t r u c t u r e s i n -  v o l v i n g b r i d g i n g a n i o n i c groups are a l s o i n d i c a t e d f o r these derivatives. volatility  The  insolubility  i n non-polar s o l v e n t s and  of such d e r i v a t i v e s are not  s i d e r i n g these compounds as i o n i c and  non-  s u i t a b l e c r i t e r i a f o r conthese p h y s i c a l p r o p e r t i e s  167 can  be a t t r i b u t e d to polymeric  structures.  Like trimethyltin(IV) d e r i v a t i v e s , a t r i g o n a l configuration tives.  bipyramidal  i s a l s o i n d i c a t e d f o r trimethylantimony(V)  These r e s u l t s are c o n s i s t e n t w i t h the g e n e r a l  chemistry of group Vb of f i v e c o o r d i n a t e  elements.  deriva-  stereo-  From n.m.r. s t u d i e s of a v a r i e t y  compounds i n c l u d i n g a number of mono-, d i - ,  and  t r i s u b s t i t u t e d pentahalides  of group Vb  and  coworkers (147,148) have shown that a t r i g o n a l  c o n f i g u r a t i o n w i t h the most e l e c t r o n e g a t i v e  elements,  Muetterties  bipyramidal  groups occupying  the  a p i c a l p o s i t i o n s i s the most favoured c o n f i g u r a t i o n f o r such compounds.  Compounds of the type RgSnX2 such as  d i h a l i d e s and  trimethylantimony  d i n i t r a t e are monomeric. In compounds of the  type  R SbY, such as trimethylantimony carbonate,sulphate, chromate 3  and  oxalate,  the  t r i g o n a l bipyramidal  c o n f i g u r a t i o n can  be  a t t a i n e d through a polymeric s t r u c t u r e , i n v o l v i n g b r i d g i n g groups i n a manner s i m i l a r to t h a t i n R3SnX d e r i v a t i v e s . 2+ i n s t a b i l i t y of the R3Sb  anionic The  c a t i o n again r e f l e c t s the p r e f e r e n c e of  the antimony atom to a t t a i n a higher  coordination.  However, the electronic: d e s c r i p t i o n of bonding i n these compounds i s not known w i t h any explanation  of the penta- and  certainty.  The  most w i d e l y used  hexacoordinated molecules i s given  by assuming the h y b r i d i z a t i o n of the a v a i l a b l e s and with one  or two  bipyramidal and  d o r b i t a l s r e s p e c t i v e l y (149), i . e . the t r i g o n a l  configuration  an o c t a h e d r a l  t i n and  p orbitals  can be e x p l a i n e d  c o n f i g u r a t i o n by s p ^ d  2  by sp^d  hybridization  hybridization^  Both  antimony have empty d o r b i t a l s a v a i l a b l e i n t h e i r  valence s h e l l s and four e l e c t r o n s .  hence are capable of a c c e p t i n g  For  t r i g o n a l bipyramidal  more than  compounds, i t has  been suggested  (22,147) that the three h y b r i d . o r b i t a l s of the  c e n t r a l atom i n the e q u a t o r i a l plane may combination of the s and p o r b i t a l s  be c o n s t r u c t e d from a  (5s and 5p i n the case of  t i n or antimony) and those on the a p i c a l a x i s from a (p_+ d combination  X5p  z  and 5d ^ i n the case of t i n and  Janssen, L u i j t e n , and van der Kerk  )  antimony).  (48) c o n s i d e r t h a t , i n f i v e  c o o r d i n a t e t i n compounds, the p r i n c i p a l i n t e r a c t i o n the donation of e l e c t r o n s from f i l l e d  involves  d o r b i t a l s of the metal  atom i n t o s u i t a b l e o r b i t a l s of the l i g a n d .  Gn the other hand,  McGrady and T o b i a s (50) c o n s i d e r that i n d i m e t h y l t i n c h e l a t e complexes (R2SnL2) the t i n 5s and 5 p almost e n t i r e l y i n the two  z  o r b i t a l s are i n v o l v e d  t i n - c a r b o n bonds and the bonding  o r b i t a l s i n the e q u a t o r i a l plane are mainly d e r i v e d from  5p and x  5py o r b i t a l s a c c o r d i n g to the m o l e c u l a r o r b i t a l treatment of Rundle (150).  169 CHAPTER 7 EXPERIMENTAL General Preparation The s i z e d ' by and  the  of  Compounds  compounds s t u d i e d  the m e t a t h e t i c a l appropriate  in this  i n v e s t i g a t i o n were s y n t h e -  r e a c t i o n b e t w e e n an o r g a n o m e t a l  silver salt in a suitable  O r g a n o t i n h a l i d e s were o b t a i n e d T r i m e t h y l a n t i m o n y d i b r o m i d e was a G r i g n a y d r e a g e n t on reaction with from the  following  Chemicals.  the  reaction  - F r e d e r i c Smith Co. . ) )'  • ).  S i l v e r Carbonate S i l v e r Chromate S i l v e r Oxalate  J  S i l v e r Permanganate Silver Hexafluorosilicate  ) )  Silver Silver SiIver Silver  ) ) ) )  Tetrafluoroborate Hexafluor©phosphate Hexafluoroarsenate Hexafluoroantimonate  - B.D.H., A.R.  by V o g e l  (151)  M e t h a n o l was and  grade  - A l f a Inorganics, - Ozark Mahoning  Inc. Co.  - G i f t f r o m Dr. E. L. Muetterties, Central Research Laboratory, E . I . du P o n t de Nemours Co., W i l m i n g t o n , D e l a w a r e .  S a l t of B i 2 C l i 2 ~  Spectro grade.  Chemical  - M a l l i n c k r o d t , A.R.grade - F i s h e r S c i e n t i f i c Co. - K & K Laboratories  O r g a n i c s o l v e n t s w e r e o f e i t h e r a n h y d r o u s A.R.  described  obtained  sources:  Silver Nitrate S i l v e r Sulphate  o r A.R.  of  subsequent  Anhydrous s i l v e r s a l t s were  Silver Perchlorate  JSilver  by  a n t i m o n y t r i c h l o r i d e and  bromine.  solvent.  from M & T  synthesized  halide  f u r t h e r d r i e d by  a c e t o n e was  Mallinckrodt the  method  d r i e d over d r i e r i t e .  170  The sulphur d i o x i d e and ammonia used were Matheson anhydrous grade. Sulphur d i o x i d e was f u r t h e r d r i e d over s u l p h u r i c a c i d and then f r a c t i o n a t e d , and ammonia was d r i e d over sodium metal. Except where otherwise s t a t e d , compounds were prepared and handled i n an atmosphere of dry n i t r o g e n i n the dry box which was c o n s t a n t l y f l u s h e d with n i t r o g e n , d r i e d f i r s t a c i d , then sodium hydroxide and f i n a l l y s i l i c a  over  gel.  sulphuric  Fresh phos-  phorus pentoxide was maintained i n the dry box at a l l times. The r e a c t a n t s were weighed i n a i r - t i g h t were t r a n s f e r r e d t o the dry box.  weighing b o t t l e s which  Sintered glass funnels with  Q u i c k f i t j o i n t s were used f o r f i l t r a t i o n .  Mixing of the r e a c -  t a n t s and f i l t r a t i o n of i n s o l u b l e s i l v e r h a l i d e were in  performed  the dry box and s o l v e n t s were removed under vacuum; then the  evacuated f l a s k s were t r a n s f e r r e d again t o the dry box. Gonventional vacuum techniques were used f o r the manipul a t i o n of v o l a t i l e  substances.  S c h u l t z and G i r a r d o t in  An apparatus d e s c r i b e d by P a r r y ,  (152) was used f o r c a r r y i n g out r e a c t i o n s  l i q u i d sulphur d i o x i d e .  The apparatus was f i r s t  then t r a n s f e r r e d t o the dry box where organometal s i l v e r s a l t were added.  was f r o z e n .  h a l i d e and  The c l o s e d apparatus was then evacuated  again and anhydrous sulphur d i o x i d e was condensed reactants.  on t o the  The mixture was shaken and then the sulphur d i o x i d e The apparatus was i n v e r t e d and p r e c i p i t a t e d  halide.was f i l t e r e d o f f and r e t a i n e d on the s i n t e r e d filter.  evacuated,  Finally,  silver  glass  the sulphur d i o x i d e was removed under vacuum  and the evacuated apparatus was t r a n s f e r r e d to the dry box. Analysis C, H, N, S, and F analyses were performed  e i t h e r i n the  171 m i c r o a n a l y t i c a l l a b o r a t o r y of t h i s department or at Microana l y t i s c h e s Laboratorium  im M a x - P l a n c k - I n s t i t u t , Miilheim (Ruhr),  Germany, or at the Schwarzkopf M i c r o a n a l y t i c a l Laboratory, York.  B and C l analyses were obtained by c o u r t e s y of Dr.  M u e t t e r t i e s ait the C e n t r a l Research Pont  de Nemours Co.,  performed Scott  Wilmington,  E.L.  Laboratory of E . I . du t  Delaware.  Other  analyses were  a c c o r d i n g to the methods d e s c r i b e d by Vogel  (154).  New  (153)  or  Most of the analyses were done i n d u p l i c a t e .  Measurement of S p e c t r a I n f r a r e d a b s o r p t i o n s p e c t r a i n the range 4000-700 were recorded on a P e r k i n Elmer model 21 Spectra i n the r e g i o n 2000-250 c m  -1  spectrophotometer.  P e r k i n Elmer model  137 i n f r a c o r d s f i t t e d w i t h sodium c h l o r i d e or potassium o p t i c s were a l s o used f o r a few measurements.  0.1  cm.  or halocarbon o i l .  as mulls  Samples were  i o d i d e , potassium bromide or  t h i c k sheets of s i l v e r c h l o r i d e or polythene.  were wrapped w i t h p o l y v i n y l tape.  Salt  plates  S p e c i a l l y designed c e l l s w i t h  t e f l o n r i n g s were used to mount s i l v e r c h l o r i d e and sheets.  bromide  Except where  otherwise s t a t e d , samples were prepared i n the dry box  p l a c e d between p l a t e s of cesium  -1  were measured on a P e r k i n  Elmer model 421 g r a t i n g spectrophotometer.  i n n u j o l , hexachlorobutadiene  cm  polythene  S e v e r a l s p e c t r a of each substance were recorded at  varying concentrations. posing the substance  Spectra were a l s o recorded a f t e r  to a i r .  windows and m u l l i n g agents.  Blanks were o f t e n run on In a few cases, s p e c t r a of  ex-  cell finely  powdered samples c o u l d be o b t a i n e d without any m u l l i n g agents. S p e c t r a of some compounds were a l s o measured i n potassium bromide p e l l e t s using f r e s h l y d r i e d potassium bromide.  Infra-  172 red  s p e c t r a of v o l a t i l e substances were measured using potassium  bromide  or s i l v e r c h l o r i d e gas  cells.  E l e c t r o n i c s p e c t r a i n the u l t r a v i o l e t and v i s i b l e  region  were r e c o r d e d on a Cary Model 14 spectrophotometer. The proton n.m.r. measurements were made w i t h a V a r i a n A60 spectrometer at 60 Mc/sec. X-ray Powder Photographs X-ray powder photographs were o b t a i n e d by using Kc< r a d i a t i o n w i t h a n i c k e l f i l t e r unit.  of  cm.  Photographs were taken i n  (2.26 g.)  and s i l v e r n i t r a t e  i n 50 ml. of acetone and the mixture was The p r e c i p i t a t e d s i l v e r c h l o r i d e was  and acetone removed under vacuum.  (1.00 g i )  shaken f o r  f i l t e r e d off  The same r e a c t i o n was  also  performed, more r a p i d l y and without shaking, i n methanol to  the g r e a t e r s o l u b i l i t y of s i l v e r n i t r a t e i n t h i s  The product was  a white s o l i d .  C, 52.42; H, 3.67; (b) of  N, 3.39.  T r i p h e n y l t i n n i t r a t e was triphenyltin chloride  nitrate  (1.698 g.)  owing  solvent.  A n a l y s i s , c a l c d . f o r C^gH-j^SnNOg:  Found:  C, 51.90; H, 3.70;  N,  3.32.  a l s o prepared by mixing s o l u t i o n s  (3.855 g.)  i n 50 ml. acetone and  i n 5 ml. of water.  S i l v e r c h l o r i d e was  t e r e d o f f and the s o l v e n t removed under vacuum. the  dia-  Nitrate  Triphenyltin chloride  three days.  or 0.3 mm.  diameter camera.  Triphenyltin  were mixed  X-ray  i n the dry box and the open ends  the c a p i l l a r y tubes were s e a l e d .  a 14.32  (a)  on a General E l e c t r i c  Quartz C a p i l l a r y tubes of e i t h e r 0.5 mm.  meter were f i l l e d with samples  copper  silver fil-  The product and  removed s o l v e n t were both y e l l o w i n c o l o r s u g g e s t i n g some  173 decomposition. H, 3 . 6 7 ; (c)  Analysis, calcd.  N, 3 . 3 9 .  C, 5 3 . 5 3 ;  Found:  S t a b i l i t y of T r i p h e n y l t i n  n i t r a t e was  f o r CigH-j^SnNOg: H, 4 . 4 0 ;  Nitrate:  N,  52.42;  C, 3.23.  Anhydrous  triphenyltin  found to be s t a b l e at room temperature i n the dry  box f o r more than two months.  After  t h i s time, there was  change i n appearance, nor i n the i n f r a r e d spectrum.  However,  exposure of the anhydrous compound to a i r caused marked i n the i n f r a r e d sample  spectrum.  no  changes  Some changes a l s o o c c u r r e d when a  of the anhydrous compound was heated to 1 5 0 ° i n vacuum f o r  one and one h a l f hours. wet acetone was  A sample  of the n i t r a t e prepared from  heated i n 6 - d i c h l o r o b e n z e n e as d e s c r i b e d by  Shapiro and Becker  (62)  and the i n f r a r e d  s p e c t r a of the r e s i d u e  and of the y e l l o w d i s t i l l a t e were r e c o r d e d . (d)  R e a c t i o n w i t h Ammonia:  to a sample solution  Anhydrous  ammonia was  condensed  on  of the anhydrous t r i p h e n y l t i n n i t r a t e and on to a  of t r i p h e n y l t i n n i t r a t e i n methanol.  kept at - 7 0 °  Both mixtures were  f o r 24 hours, a f t e r which the excess ammonia and  s o l v e n t were removed under vacuum, to leave white s o l i d s .  Ana-  l y t i c a l r e s u l t s of the s o l i d s were not r e p r o d u c i b l e but were always of the same order, a t y p i c a l r e s u l t being as f o l l o w s . Analysis, calcd. N, 9 . 4 2 . 6.53.  f o r C H S n N 0 ( N H ) : C, 1 8  1 5  3  3  2  Galcd. f o r C H S n N 0 ( N H ) :  Found:  1 8  1 5  3  C, 5 0 . 3 1 ; H, 4 . 7 6 ;  graphs and the i n f r a r e d  3  C, 5 0 . 3 5 ;  N, 5 . 8 8 .  H,  4.75;  H, 4 . 2 3 ;  N,  X-ray powder photo-  s p e c t r a of the products showed them to  be mixtures c o n t a i n i n g ammonium n i t r a t e and ide.  48.44;  bis(triphenyltin)ox-  174 Triphenyltin  Perchlorate  (a) T r i p h e n y l t i n (1.092 g.)  (2.030 g.)  and  shaken f o r three days.  filtered  o f f and  the  f i l t r a t e was  C H S n C 1 0 : C, 48.20; H, 1 5  3.34.  4  Triphenyltin  perchlorate  Analysis,  Triphenyltin  which l i k e w i s e following  46.35; H,  3.38.  The  ether.  exposure  perchlorate  as  allowed to as  an react  described  products were white s o l i d s  gave n o n - r e p r o d u c i b l e a n a l y t i c a l r e s u l t s ,  being t y p i c a l ;  C, 44.75; H,  H,  4.35;  3.86;  N,  N,  Analysis,  5.79.  3.00.  for  i n f r a r e d spectrum.  same c o n d i t i o n s  for triphenyltin n i t r a t e .  chloride  i n methanol and  anhydrous s o l i d or i n methanol s o l u t i o n , was with excess ammonia, under the  the  calcd.  h y d r o l y s e s immediately on  R e a c t i o n w i t h Ammonia:  earlier  silver  Found: C, 48.9;  to a i r as shown by marked changes i n the (b)  of ether and  removed under vacuum, at  i s very s o l u b l e  I t i s very h y g r o s c o p i c and  perchlorate  Precipitated  room temperature to leave a white s o l i d . l g  silver  were mixed i n a f l a s k with 50 ml.  mixture was was  chloride  the  c a l c d . f o r CigHi5SnC104(NH3)g:  Calcd. for C H S n C 1 0 ( N H ) : 1 8  Found: C,  X-ray powder photographs and  the  1 5  44.63; H,  4  4.63;  i n f r a r e d spectra  showed them to be mixtures c o n t a i n i n g  N, of  C,  3  3.99.  the  products  ammonium p e r c h l o r a t e  and  bis(triphenyltin)oxide. Trimethyltin  Permanganate  Attempts to prepare t h i s compound were not  successful.  The  metathetical reaction  and  s i l v e r permanganate, u s i n g methanol, acetone, or water  solvent, the  resulted  r e a c t i o n was  i n the  between t r i m e t h y l t i n bromide or  p r e c i p i t a t i o n of the  accompanied by  the  chloride  s i l v e r halide  decomposition of  the  as but  175 permanganate.  No r e a c t i o n  o c c u r r e d when t - b u t y l  alcohol,  c h l o r o f o r m , a c e t o n i t r i l e , or ether was used as s o l v e n t . Attempts t o r e a c t  solid  trimethyltin halide  manganate or s i l v e r permanganate also  and potassium per-  at 50° i n a c l o s e d  system were  unsuccessful.  Bis(trimethyltin)  Sulphate  Trimethyltin  bromide (1.220 g.) and s i l v e r  sulphate  (0.781 g.) were mixed i n 50 ml. of methanol, and the mixture was shaken f o r three days.  The p r e c i p i t a t e d s i l v e r  was f i l t e r e d o f f (0.949 g.,  bromide  c a l c d . 0.941 g.) and, on removal  of the methanol under vacuum at room temperature, white c r y s t a l s of b i s ( t r i m e t h y l t i n ) sulphate-methanol adduct were obtained.  Analysis,  H, 4.13; S 0 , 19.70. 4  c a l c d . f o r ( C H S n ) S 0 ( C H O H ) : C, 19.68; 3  9  2  4  3  2  Found: C, 19.00; H, 4.59; S O 4 , 20.48.  On h e a t i n g the methanol adduct at 100° under vacuum f o r about f o u r hours, the methanol was completely removed  and anhydrous  b i s ( t r i m e t h y l t i n ) s u l p h a t e was o b t a i n e d as a white s o l i d . Analysis,  c a l c d . f o r ( C g H g S n ) S 0 : C, 17.01; H, 4.25. 2  C, 17.55; H, 4.46.  4  Both b i s ( t r i m e t h y l t i n ) s u l p h a t e and i t s  methanol adduct are s o l u b l e  i n water and methanol, but i n s o l u b l e  i n s o l v e n t s such as acetone, e t h e r , and a c e t o n i t r i l e . the  Found:  Both  compounds are h y d r o l y s e d on exposure to a i r as shown by  changes i n t h e i r i n f r a r e d Bis(trimethyltin)  spectra.  Chromate  Trimethyltin  bromide  (2.793 g.) and s i l v e r  (1.901 g.) were allowed t o r e a c t c i p i t a t e d s i l v e r bromide  chromate  i n 50 ml. of methanol.  Pre-  (2.142 g., c a l c d . 2.152 g.) was imme-  176 diately f i l t e r e d off.  The  methanol was  vacuum at room temperature and t i n ) chromate were o b t a i n e d . C,  16.24; H,  4.06;  C r 0 , 25.46.  yellow c r y s t a l s of b i s ( t r i m e t h y l Analysis,  C r 0 , 26.17.  c a l c d . f o r (C^HgSn) gCrO^.:  Found:  4  C,  16.08; H,  B i s ( t r i m e t h y l t i n ) chromate i s s o l u b l e  4  methanol but  decomposes slowly  u a l darkening of c o l o u r . and  q u i c k l y removed under  I t i s only  s l i g h t l y soluble Unlike  h y d r o l y s e d on exposure to a i r .  d i f l u o r i d e was  potassium f l u o r i d e (2.8206 g.) of water.  The  washed w i t h water and from a 40  spectroscopically.  prepared by  and  the r e a c t i o n  dimethyltin  ethanol.  The  filtered  product was  recrystallized  c a l c d . f o r C HeSnF2: C, 2  acid in a 12.90; H,  d i c h l o r i d e (1.0850 g.)  were mixed i n 50 ml.  and  silver  of methanol and  A f t e r removal of the  carbonate  the mixture  solvent  carbonate was  photograph.  o b t a i n e d which was  characterized  X-ray powder photograph.  No  by  was  under vacuum  at room temperature, a mixture of s i l v e r c h l o r i d e and  dimethyltin  3.23.  3.60.  shaken f o r three days.  spectrum and  and  Carbonate  Dimethyltin (1.3624 g.)  of  d i c h l o r i d e (5.332  p r e c i p i t a t e d s o l i d was  Analysis,  12.98; H,  Dimethyltin  i n acetone  Samples  percent aqueous s o l u t i o n of h y d r o f l u o r i c  platinum d i s h . Found: C,  grad-  Difluoride  Dimethyltin  i n 50 ml.  the  and  bis(trimethyltin)  exposed to a i r f o r three days showed no changes Dimethyltin  i n water  i n s o l u t i o n as shown by  i n s o l u b l e i n ether or c h l o r o f o r m .  s u l p h a t e , i t i s not  4.00;  dimethyltin  i t s infrared  l i n e s due  to e i t h e r  d i c h l o r i d e or s i l v e r carbonate appeared i n the powder However, d i m e t h y l t i n  carbonate c o u l d not  be  isolated  g.)  f r e e from s i l v e r c h l o r i d e due solvent.  to i t s i n s o l u b i l i t y i n a s u i t a b l e  I t i s i n s o l u b l e i n methanol, acetone,  or dimethyl sulphpxide but  acetonitrile  d i s s o l v e s i n hot water with decom-  p o s i t i o n to g i v e d i m e t h y l t i n oxide as the f i n a l product. i n f r a r e d spectrum of a sample of the mixture not  show any  hydrolysed  exposed to a i r d i d  change i n d i c a t i n g that d i m e t h y l t i n carbonate i s not  on exposure to a i r .  Dimethyltin  Chromate  (a) D i m e t h y l t i n (2.718  g.)  i n 5 0 ml.  dichloride  (1.800  g.)  were allowed to r e a c t i n  and  silver  ml.  50  chromate  acetone, as w e l l  of a c e t o n i t r i l e i n the same manner as d e s c r i b e d  d i m e t h y l t i n carbonate.  c h l o r i d e and  d i m e t h y l t i n chromate was  i n f r a r e d s p e c t r a and  obtained,  l i n e s due  d i m e t h y l t i n d i c h l o r i d e or s i l v e r chromate.  On  to e i t h e r  a d d i t i o n of  the  no p r e c i -  the p r e v i o u s l y formed s i l v e r c h l o r i d e s e t t l e d  recovered  i n q u a n t i t a t i v e amounts.  From the  the q u a n t i t a t i v e weight of barium chromate was that there had  been no r e d u c t i o n  mixture of d i m e t h y l t i n chromate and any  silver  solids.  mixture to water a c i d i f i e d w i t h a c e t i c a c i d , there was  confirming  for  as shown by  X-ray powder photographs of the  X-ray powder photographs d i d not show any  p i t a t i o n , only  as  A f t e r removal of the s o l v e n t under vacuum  at room temperature, i n each case a yellow mixture of  and was  The  spectroscopic  filtrate,  precipitated,  of chromium.  The  s i l v e r c h l o r i d e d i d not show  changes on exposure to a i r , i n d i c a t i n g that  d i m e t h y l t i n chromate i s not h y d r o l y s e d  in a i r .  On  t r e a t i n g the  mixture w i t h hot water, d i m e t h y l t i n chromate d i s s o l v e d to g i v e a yellow recovered  s o l u t i o n , but pure d i m e t h y l t i n chromate c o u l d not from the aqueous s o l u t i o n due  to p a r t i a l  be  decomposition  178 of the chromate. (b)  The  above m e t a t h e t i c a l  S i l v e r c h l o r i d e was  r e a c t i o n was  a l s o done i n methanol.  p r e c i p i t a t e d instantaneously,  but  the  d i m e t h y l t i n chromate formed r e a c t e d with the s o l v e n t as shown by a r a p i d darkening i n c o l o u r . Dimethyltin (a)  Sulphate  Dimethyltin  (1.7454 g.)  and  were allowed to r e a c t i n 50 ml.  pitated silver 1.6040 g . ) .  d i c h l o r i d e (1.2300 g.)  c h l o r i d e was  The  f i l t r a t e was  C H SnS0 :  2.47.  C, 9.80;  4  methyltin  sulphate  S,  of water, and p r e c i -  Found:  Analysis, calcd. for  C, 9.67;  i s s o l u b l e i n water but  H,  for (b)  and  Diorganic  dimethyl  i n a i r , a sample exposed to a i r  24 hours showed no change i n the i n f r a r e d spectrum. Dimethyltin  (1.4690 g.) was  It i s not h y d r o l y s e d  2.46.  insoluble in  s o l v e n t s such as methanol, acetone, a c e t o n i t r i l e , sulphoxide.  calcd.  evaporated on a water bath to g i v e  d r i e d under vacuum.  6  sulphate  f i l t e r e d o f f (1.6036 g.,  a white s o l i d which was 2  silver  d i c h l o r i d e (1.0346 g.)  were mixed i n 50 ml.  shaken f o r three days.  which was  recovered  temperature.  The  An  and  silver  of methanol and  sulphate  the mixture  i n s o l u b l e mixture was  by evaporating  precipitated  the s o l v e n t under vacuum at room  i n f r a r e d spectrum and  an X-ray powder  photograph of the d r i e d s o l i d showed i t to be a mixture of s i l v e r c h l o r i d e and  a methanol adduct of d i m e t h y l t i n  sulphate.  However, the d i m e t h y l t i n sulphate-methanol adduct c o u l d not i s o l a t e d f r e e from the s i l v e r c h l o r i d e due a suitable solvent.  The  be  to i t s i n s o l u b i l i t y  in  i n f r a r e d spectrum of the mixture showed  marked changes when the  s o l i d was  h y d r o l y s i s of the d i m e t h y l t i n  exposed to a i r i n d i c a t i n g  sulphate-methanol adduct.  methanol adduct d i s s o l v e d i n water and aqueous s o l u t i o n , pure d i m e t h y l t i n  heated to 100° was  upon evaporating  sulphate  a p o r t i o n of the methanol adduct and  and  was  the  recovered.  When  s i l v e r c h l o r i d e mixture  was  under vacuum f o r about f o u r hours, the methanol  completely removed l e a v i n g a mixture of  sulphate  The  s i l v e r c h l o r i d e , as shown by  dimethyltin  the  i n f r a r e d spectrum  of the heated m i x t u r e . (c) D i m e t h y l t i n  d i c h l o r i d e and  silver  sulphate  r e a c t i n acetone, as w e l l as i n a c e t o n i t r i l e , described sulphate spectra  Insoluble  silver  and  c h l o r i d e and  a f t e r removing the  solvent  the i n f r a r e d  Solid  under vacuum. dimethyltin  r e f l u x e d w i t h excess p y r i d i n e f o r 24 hours.  vacuum.  dimethyltin  X-ray powder photographs of the anhydrous mixtures  Reaction with P y r i d i n e :  s o l i d was  filtered The  product was  found to be  The  sulphate  Insoluble  o f f , washed w i t h chloroform  p y r i d i n e monoadduct.  and  dimethyltin  same product was  was  white  d r i e d under sulphate-  also precipitated  when excess p y r i d i n e was  added to an aqueous s o l u t i o n of d i -  methyltin  p r e c i p i t a t e was  and  sulphate.  dimethyltin  The  sulphate-pyridine  washed w i t h chloroform  and  2  26.14; H,  6  3.74;  4  5  5  N, 4.40.  d i s s o l v e d i n water  monoadduct was  d r i e d under vacuum.  c a l c d . f o r C H S n S 0 ( C H N ) : C, C,  to  i n the manner  were formed i n each case, as shown by  obtained (d)  above.  were allowed  27.64; H,  Dimethyltin  adduct i s i n s o l u b l e i n p y r i d i n e and  3.91;  crystallized, Analysis, N, 4.61.  Found:  sulphate-pyridine  organic  solvents  such  as  180 methanol, acetone, a c e t o n i t r i l e , and chloroform,  but s o l u b l e i n  water. (e) Reaction w i t h Dimethyl Sulphoxide (DMSO):  Solid dimethyltin  sulphate was shaken with excess DMSO f o r 24 hours. s o l i d was f i l t e r e d o f f , washed with chloroform vacuum.  The product  monoadduct.  The i n s o l u b l e  and d r i e d under  was found t o be d i m e t h y l t i n sulphate-DMSO  Another p r e p a r a t i o n o f d i m e t h y l t i n sulphate-DMSO  adduct was performed i n aqueous s o l u t i o n , and c r y s t a l l i n e d i m e t h y l t i n sulphate-DMSO monoadduct was obtained manner as d e s c r i b e d above. C,  i n a similar  A n a l y s i s , c a l c d . CgHgSnSO^(CHg)gSO:  15.34; H, 3.86; S, 20.50.  Found: C, 15.59; H, 3.84; S, 20.56.  D i m e t h y l t i n sulphate-DMSO adduct i s i n s o l u b l e i n DMSO and organic  s o l v e n t s such as methanol, acetone, a c e t o n i t r i l e , and  chloroform,  but s o l u b l e i n water.  D i m e t h y l t i n D i c h l o r i d e Adducts (a) D i m e t h y l t i n d i c h l o r i d e - p y r i d i n e diadduct was prepared method d e s c r i b e d by B e a t t i e and M c Q u i l l a n  by the  (33).  (b) D i m e t h y l t i n dichloride-DMSO diadduct was prepared  by adding  excess DMSO t o a s o l u t i o n of d i m e t h y l t i n d i c h l o r i d e i n c h l o r o form, f o l l o w e d by a d d i t i o n o f excess of e t h e r .  A white  crystal-  l i n e p r e c i p i t a t e was o b t a i n e d which was washed with ether and r e c r y s t a l l i z e d from c h l o r o f o r m . C H S n C l \iCn ) s6^ 2  C,  6  2  3  2  2  Analysis, calcd. f o r  C , 19.16; H, 4.82; S, 17.07.  19.14: H, 4.64; S, 16.97.  Found:  D i m e t h y l t i n dichloride-DMSO adduct  i s s o l u b l e i n p o l a r s o l v e n t s such as water and methanol as w e l l as i n non-polar o r g a n i c s o l v e n t s such as chloroform.  181 Dimethyltin (a)  Bis(tetrafluoroborate)  Dimethyltin  d i c h l o r i d e (0.6470 g.) and s i l v e r t e t r a f l u o r o -  borate (1.470 g.) were allowed to r e a c t i n about 25 ml. of methanol.  P r e c i p i t a t e d s i l v e r c h l o r i d e was  f i l t e r e d o f f (0.8370 g.  c a l c d . 0.8440 g.) and the f i l t r a t e was  removed under vacuum at  room temperature to g i v e a white s o l i d  (1).  for C H Sn(BF ) : 2  6  4  H, 2.82;  C, 7.44;  2  F, 32.47.  H, 1.87;  Analysis, calcd. for  F, 47.14.  Found:  C, 10.47;  As i n d i c a t e d by the a n a l y s i s , p a r t i a l decom-  p o s i t i o n of d i m e t h y l t i n b i s ( t e t r a f l u o r o b o r a t e ) o c c u r r e d to g i v e boron t r i f l u o r i d e and d i m e t h y l t i n d i f l u o r i d e .  T h i s was confirmed  by the f o l l o w i n g e x p e r i m e n t a l r e s u l t s : i)  A p o r t i o n of the r e c o v e r e d methanol was  to about 10 ml. of p y r i d i n e . under vacuum, a white s o l i d trum was  condensed  on  Upon e v a p o r a t i o n of the mixture (II) was  i d e n t i c a l to that r e p o r t e d  l e f t , whose i n f r a r e d spec(155) f o r the boron  t r i f l u o r i d e - p y r i d i n e adduct, BFg.Py. ii)  Another p o r t i o n of the r e c o v e r e d methanol gave a  p o s i t i v e t e s t f o r f l u o r i n e and boron and was  found to be markedly  acidic. iii)  Upon r e d i s s o l v i n g the s o l i d  one-half of the s o l i d was T h i s i n s o l u b l e s o l i d was  (I) i n methanol,  about  found to be i n s o l u b l e i n methanol. identified  (from i t s i n f r a r e d spectrum,  X-ray powder photograph and a n a l y t i c a l r e s u l t s ) to be dimethyltin  difluoride.  12.90; H, 3.23, iv)  A n a l y s i s , c a l c d . f o r C HgSnF : C, 2  Found: C, 12.85; H,  3.21.  The i n f r a r e d spectrum of the s o l i d  s i m i l a r to that r e p o r t e d  2  (I) was very  (43) f o r t r i m e t h y l t i n t e t r a f l u o r o b o r a t e .  Upon exposure of the s o l i d to a i r f o r a few seconds, the i n f r a r e d  182 spectrum showed c h a r a c t e r i s t i c a b s o r p t i o n bands of the f r e e BF4~ i o n . (b)  The thermal s t a b i l i t y of the mixture of d i m e t h y l t i n  b i s ( t e t r a f l u o r o b o r a t e ) and d i m e t h y l t i n d i f l u o r i d e was  I)  examined by h e a t i n g the s o l i d at 60 - 70° under vacuum  f o r about 6 hours,  The s o l i d d i d not sublime nor d i d i t show  any change i n i t s i n f r a r e d spectrum and a n a l y s i s 10.57; ,H, 2.60). Cc)  (solid  No boron t r i f l u o r i d e was e v o l v e d .  Dimethyltin dichloride  fluoroborate  (found: C,  (0.8444 g.)  and s i l v e r  tetra-  (1.4968 g.) were mixed i n about 25 ml. of e t h e r .  T h i s r e s u l t e d i n p r e c i p i t a t i o n of s i l v e r c h l o r i d e and an i n s o l u b l e product. the e t h e r was r e s i d u e was  A f t e r shaking the mixture f o r f i v e  minutes,  removed under vacuum at room temperature.  The  s t i c k y and the q u a l i t a t i v e a n a l y s i s showed the  presence of s i l v e r c h l o r i d e i n i t .  The i n f r a r e d spectrum of  the r e s i d u e showed a l l the a b s o r p t i o n bands shown by the mixt u r e of d i m e t h y l t i n b i s ( t e t r a f l u o r o b o r a t e ) and difluoride  (solid  I  dimethyltin  d e s c r i b e d above), and, on exposing the  r e s i d u e to a i r , the same changes were observed i n the i n f r a r e d spectrum as d e s c r i b e d above f o r the p r e v i o u s m i x t u r e s . 5 ml. of t r i m e t h y l a m i n e was  condensed  onto the r e c o v e r e d e t h e r ,  and the ether and excess t r i m e t h y l a m i n e were removed vacuum at room temperature.  A white s o l i d was  i n f r a r e d spectrum of t h i s s o l i d was that r e p o r t e d (156, 156) adduct, BF3.N(CH3) . 3  f o r boron  About  under  obtained.  The  found to be i d e n t i c a l to trifluoride-trimethylamine  183 (d)  Dimethyltin  d i c h l o r i d e (0.7708 g.)  borate (1.2774 g.) l i q u i d sulphur  silver tetrafluoro-  were allowed to r e a c t i n about 20 ml.  dioxide.  The  d i o x i d e was  i n s o l u b l e product was  and  the sulphur  was  l e f t behind a f t e r removal of sulphur  tered s o l u t i o n .  and  pumped o f f .  of  f i l t e r e d off  Only a t r a c e of  solid  d i o x i d e from the  fil-  A p o r t i o n of the f i l t e r e d r e s i d u e gave a p o s i t i v e  test for s i l v e r chloride.  The  i n f r a r e d s p e c t r a of the  residue,  under anhydrous c o n d i t i o n s as w e l l as a f t e r exposure to a i r , were i d e n t i c a l to those obtained  f o r the p r e v i o u s l y  mixture of d i m e t h y l t i n b i s ( t e t r a f l u o r o b o r a t e ) and difluoride  (solid  described  dimethyltin  I ) .  Dimethyltin Hexafluorosilicate An  attempt to prepare t h i s compound was  When d i m e t h y l t i n d i c h l o r i d e (0.6402 g.) silicate  (1.0426 g.)  s i l v e r c h l o r i d e was  and  not  successful.  silver  hexafluoro-  were mixed i n about 25 ml. precipitated.  of methanol,  Upon removal of the methanol,  under vacuum at room temperature, the product was  found to  d i m e t h y l t i n d i f l u o r i d e which was  i t s X-ray  c h a r a c t e r i z e d by  powder photograph, i n f r a r e d spectrum, and  analytical results.  A n a l y s i s , c a l c d . f o r CgHgSnFg: C,  12.90; H,  C,  methanol was  and  12.82; H, 3.07. contained  The  recovered  s i l i c o n and  be  3.23.  Found:  highly  acidic  f l u o r i n e which were i d e n t i f i e d by  q u a l i t a t i v e a n a l y s i s of h y d r o l y s i s p r o d u c t s of the  the  recovered-  methanol. Dimethyltin  Bis(hexafluorophosphate)  (a) Attempts to prepare t h i s compound were not metathetical and  successful.  r e a c t i o n between d i m e t h y l t i n d i c h l o r i d e (1.542  s i l v e r hexafluorophosphate (3.505 g.)  i n 25 ml.  The g.)  of methanol  r e s u l t e d i n the p r e c i p i t a t i o n of s i l v e r c h l o r i d e .  Upon removal  of the s o l v e n t from the f i l t e r e d s o l u t i o n under vacuum at room temperature, methanol.  a white product was  The  The  recovered methanol was  p l i s h e d by q u a l i t a t i v e The  measured  c o u l d not be c h a r a c t e r i z e d by i t s i n f r a r e d  both f l u o r i n e and phosphorus.  (b)  insoluble in  i n f r a r e d spectrum of t h i s product was  but the product trum.  obtained which was  h i g h l y a c i d i c and  spec-  contained  T h i s i d e n t i f i c a t i o n was  accom-  analysis.  above m e t a t h e t i c a l r e a c t i o n was  sulphur d i o x i d e s o l u t i o n .  a l s o performed i n a  The p r e c i p i t a t e d s i l v e r c h l o r i d e was  shown by an X-ray powder photograph to c o n t a i n d i m e t h y l t i n difluoride.  F r a c t i o n a t i o n of the v o l a t i l e m a t e r i a l from the  sulphur d i o x i d e s o l u t i o n gave a sample r i c h i n phosphorus o x y t r i f l u o r i d e , POF^, s o l i d remaining  as shown by i t s i n f r a r e d spectrum.  The  on removal of the sulphur d i o x i d e under vacuum  a l s o c o n t a i n e d d i m e t h y l t i n d i f l u o r i d e which was  identified  by  an X-ray powder photograph. Dimethyltin Bis(hexafluoroarsenate) Dimethyltin dichloride arsenate  (0.7790 g.)  and s i l v e r  hexafluoro-  (2.1044 g.) were mixed i n 25 ml. of methanol and  precipitated silver  c h l o r i d e was  filtered off.  the  The methanol  was  removed from the f i l t e r e d s o l u t i o n under vacuum at room temperature to g i v e a hygroscopic white s o l i d which g r a d u a l l y turned yellowish-white.  The  i n f r a r e d spectrum of the s o l i d was  s i m i l a r to t h a t r e p o r t e d (43) f o r t r i m e t h y l t i n i n d i c a t i n g the presence  very  hexafluoroarsenate  of the h e x a f l u o r o a r s e n a t e group i n i t .  An X-ray powder photograph of the s o l i d showed the presence :  of d i m e t h y l t i n d i f l u o r i d e .  Thus the s o l i d was a mixture of  d i m e t h y l t i n d i f l u o r i d e and the b i s ( h e x a f l u o r o a r s e n a t e ) .  When  the s o l i d was exposed t o a i r , i t s i n f r a r e d spectrum showed the c h a r a c t e r i s t i c strong band of AsFg i o n a t 720 c m . -1  methanol was h i g h l y a c i d i c and contained  The recovered  both f l u o r i n e and  a r s e n i c as shown by q u a l i t a t i v e t e s t s . Dimethyltin (a)  Bis(hexafluoroantimonate)  The m e t a t h e t i c a l r e a c t i o n between d i m e t h y l t i n d i c h l o r i d e  (1.0606 g.) and s i l v e r hexafluoroantimonate (3.3178 g.) was performed i n 25 ml. methanol i n the manner d e s c r i b e d product was a hygroscopic  above.  white s o l i d which contained  methanol as shown by i t s i n f r a r e d spectrum.  The  some  The recovered  meth-  anol was not a c i d i c and d i d not show presence of any f l u o r i n e or antimony i n d i c a t i n g t h a t no decomposition of h e x a f l u o r o a n t i monate had o c c u r r e d . 120°  When the recovered  s o l i d was heated up t o  under vacuum t o remove the methanol, decomposition of the  s o l i d occurred  and o i l y drops of antimony p e n t a f l u o r i d e , SbFg  were condensed i n the t r a p .  Q u a l i t a t i v e t e s t s on t h i s o i l  showed the presence of antimony and f l u o r i n e . (b)  Dimethyltin  d i c h l o r i d e (1.038 g.) and s i l v e r  monate (3.2476 g.) were allowed sulphur off.  t o r e a c t i n 25 ml. of l i q u i d  d i o x i d e and the p r e c i p i t a t e d s i l v e r  Removal of sulphur  hygroscopic  solid.  hexafluoroanti-  cls&jvide was f i l t e r e d  d i o x i d e under vacuum gave a very  X-ray powder photographs of the s o l i d and  the s i l v e r c h l o r i d e d i d not show any l i n e s due t o d i m e t h y l t i n difluoride.  The i n f r a r e d spectrum of the s o l i d showed s i m i l a r  f e a t u r e s t o those r e p o r t e d  (43) f o r trimethylantimony  hexafluoro?-  antimonate and the i n f r a r e d spectrum of a sample of the s o l i d '  186 exposed to a i r showed c h a r a c t e r i s t i c band of the  SbFg" i o n  660  obtained.  cm" .  However, no  1  The* D i m e t h y l t i n  Derivative  Dimethyltin (0.7118 g.)  analysis  of the  of B i C l 2  dichloride  c h l o r i d e was  ~  (0.2030 g.)  were allowed to r e a c t  tated s i l v e r  2 1 2  s o l i d was  and  i n 25 ml.  filtered  Ag B 2  the  it  not  be  was  not  a c i d i c and that no  occurred.  Analysis,  56.6;  The  &\2^12  2  16.4;  12^ 12  water but  6  1 2  1 2  Cl  C l , 57.8.  soluble  i s  1  insoluble  g  chlorine  r o u  1 2  1 2  ±  ( C H 3 O H ) : B, 2  The  i n polar  dimethyltin solvents  i n chloroform.  5  :  B,  16.9;  P  n a c  *  B,  1 2  2  The  r e c o v e r e d methanol  calcd. for C HgSnB Cli2(CH3OH):  calcd. for C H S n B  Found: B, B  hours.  decomposition of the  2  was  s o l i d even a f t e r h e a t i n g  calcd. for C H g S n B C l ( C H 3 O H )  57.8;  Precipi-  a white product  gave n e g a t i v e t e s t s f o r boron and  indicating  Cl,  f o r 24  12  i t s i n f r a r e d spectrum.  removed from the  under vacuum at 100°  c l  solvent  removed under vacuum at room temperature to g i v e  methanol could  1 2  methanol.  o f f and  which c o n t a i n e d methanol as shown by  at  17.6;  17.26; C l , Cl,  55.4.  derivative  of  such as methanol  and  I t i s very h y g r o s c o p i c  and  h y d r o l y s e s on exposure to a i r as shown by changes i n i t s i n f r a r e d spectrum. Trimethylantimony Dibromide T h i s was Davies  (157).  t i l l e d A.R. iodide.  the method d e s c r i b e d  Trimethylstibine  was  trimethylstibine  atmosphere and  and  the  by Morgan  and  prepared from f r e s h l y d i s -  grade antimony t r i c h l o r i d e and  The  a nitrogen  prepared by  methyl magnesium  ether were c o - d i s t i l l e d  distillate  in  t r e a t e d with a carbon  t e t r a c h l o r i d e s o l u t i o n of bromine.  Precipitated  mony dibromide was  r e c r y s t a l l i z e d from water.  Analysis,  filtered  o f f and  calcd. for C H SbBr : 3  9  2  C,  1 1 . 2 0 ; H,  trimethylanti-  2.80;  Br,  48.92.  187 Found: C,  11.09; H,  Trimethylantimony  2.46;  Br, 48.90.  Difluoride  An aqueous s o l u t i o n of s i l v e r s o l v i n g s i l v e r carbonate  f l u o r i d e was  made by  i n 40 percent aqueous s o l u t i o n of  h y d r o f l u o r i c a c i d i n a platinum d i s h . which c o n t a i n e d 0.7160 g. of s i l v e r  20 mi. of t h i s  f l u o r i d e , was  dryness.  f i l t e r e d o f f and  The  product was  the f i l t r a t e was  17.00; H, 4.29.  c h l o r o f o r m and  9  2  C,  17.58; H, 4.39.  Trimethylantimony  crystalline solid.  to  then r e c r y s t a l l i z e d from e t h a n o l  Analysis, calcd. for C H SbF : C,  Silver  evaporated  f u r t h e r p u r i f i e d by s u b l i m a t i o n under vacuum at room 3  solution  allowed to  r e a c t with 0.9214 g. of trimethylantimony dibromide. bromide was  dis-  and  temperature. Found:  d i f l u o r i d e i s a white  I t i s s o l u b l e i n water, methanol  and  i s not h y d r o l y s e d i n a i r .  Trimethylantimony  Dinitrate  Trimethylantimony  dibromide  (0.6472 g.)  and s i l v e r  nitrate  (0.6732 g.) were allowed to r e a c t i n 25 ml. of methanol. cipitated silver  bromide was  Pre-  f i l t e r e d o f f and the s o l v e n t removed  under vacuum at room temperature.  White f l a k e s of  trimethyl-  antimony d i n i t r a t e were o b t a i n e d which were r e c r y s t a l l i z e d chloroform. 3.10;  A n a l y s i s , c a l c d . f o r CgHgSb(NO3) : 2  N, 9.63.  Found: C,  Trimethylantimony and c h l o r o f o r m . moisture.  2.95;  N,  12.40; H,  9.89.  d i n i t r a t e i s s o l u b l e i n water, methanol  I t i s h y d r o l y s e d s l o w l y i n the presence  However, the h y d r o l y s i s i s r e v e r s i b l e and the  product was vacuum.  12.78; H,  C,  The  from  of hydrated  converted i n t o anhydrous d i n i t r a t e by d r y i n g under h y d r a t i o n and d e h y d r a t i o n c o u l d be f o l l o w e d by  188 observing the changes i n the i n f r a r e d spectrum. Trimethylantimony  Carbonate  Trimethylantimony bonate  ''  dibromide  (0.9712 g,)  and s i l v e r car-,  (0.8200 g.) were allowed to r e a c t i n 20 ml. of  sulphur d i o x i d e .  S i l v e r bromide was  liquid  f i l t e r e d o f f and,  after  removal df sulphur d i o x i d e under vacuum, white trimethylantimony carbonate was H, 4.00.  obtained..  A n a l y s i s , c a l c d . f o r C3 Hg Sb CO3: C,  Found: C, 21.37; H, 4.23.  21.17  It i s soluble i n l i q u i d  sulphur d i o x i d e , water and methanol,  but i n s o l u b l e i n c h l o r o f o r m .  I t d i d not sublime under vacuum up to 100° and no changes were observed i n the i n f r a r e d spectrum Trimethylantimony  water.  to a i r .  Sulphate  Trimethylantimony sulphate  on exposing the s o l i d  dibromide  (0.6274 g.)  and  silver  (0.5992 g.) were allowed to r e a c t i n about 25 ml. P r e c i p i t a t e d s i l v e r bromide was  f i l t e r e d o f f and  f i l t r a t e evaporated to dryness on a steam bath/. : A white ;  s t a l l i n e s o l i d was  o b t a i n e d which was  and d r i e d under vacuum.  the cry-  r e c r y s t a l l i z e d 'from water  A n a l y s i s , c a l c d . f o r CsHgSbSO^: C,  H, 3.45.; Found: C, 13.78; H, 3.87.  Trimethylantimony s u l p h a t e  i s i n s o l u b l e i n o r g a n i c s o l v e n t s such as methanol, and c h l o r o f o r m , but s o l u b l e i n water.  13.70  acetonitrile  I t i s not h y d r o l y s e d i n  air. Trimethylantimony  Chromate  Trimethylantimony chromate was  o b t a i n e d as a yellow  c r y s t a l l i n e s o l i d from t r i m e t h y l a n t i m o n y dibromide and s i l v e r chromate (1.0872 g.)  (1.0706  g.)  using the same method as that  d e s c r i b e d f o r trimethylantimony s u l p h a t e .  Analysis, calcd. for  189 C H S b C r 0 : C, 12.73; H, 3.20; 3  9  4  H, 3.12;  C r 0 , 41.29.  C r 0 , 41.03.  Found: C,.12.66;  4  I t i s a l s o i n s o l u b l e i n methanol and  4  a c e t o n i t r i l e and i s not h y d r o l y s e d i n a i r . Trimethylantimony  Oxalate  T h i s compound was dibromide  (1.1064 g.)  prepared from trimethylantimony  and s i l v e r  o x a l a t e (1.0280,g .) i n the 1  manner d e s c r i b e d f o r t r i m e t h y l a n t i m o n y s u l p h a t e . c a l c d . f o r C 3 H S b C 0 : C, 23.55; H, 3.56; 9  2  C, 23.51; H, 3.68;  4  C 0 , 34.36. 2  Analysis,  C 0 , 34.54. 2  Found:  4  Trimethylantimony o x a l a t e i s  4  s o l u b l e i n water but i n s o l u b l e i n methanol and  acetonitrile.  I t i s not h y d r o l y s e d i n a i r . Trimethylantimony  Bis(perchlorate)  Trimethylantimony dibromide perchlorate  the l a s t  silver  bromide was  filtered off.  Most of the  removed under vacuum at room temperature  but  t r a c e s were removed by warming to about 60°.  An  anhydrous s o l i d was  o b t a i n e d which  scratching with a n i c k e l spatula. work was  and  (0.6868 g.) were allowed to r e a c t i n 25 ml. of  methanol and s i l v e r methanol was  (0.5410 g.)  exploded v i o l e n t l y Consequently,  no  done on i t .  Trimethylantimony tetrafluoroborate of methanol.  dibromide  ^ v  (0.5614 g.)  and  -  silver  (1.0268 g.) were allowed to r e a c t i n 25 ml.  S i l v e r bromide was  filtered off.  the s o l v e n t under vacuum at room temperature, o b t a i n e d which was  lytical  on  further  Trimethylantimony B i s ( t e t r a f l u o r o b o r a t e )  was  .  After  a white  sublimed under vacuum at 50°.  removing solid The  r e s u l t s and i n f r a r e d s p e c t r a of both unsublimed  ana-  and  190 sublimed products were i d e n t i c a l .  Analysis,  C H S b ( B F ) : C, 10.57; H, 2.66. 3  9  4  Found: C, 14.28; H,  2  As i n d i c a t e d  calcd. for 3.60.  by the a n a l y t i c a l r e s u l t s , p a r t i a l decomposition  of the t e t r a f l u o r o b o r a t e f i r m e d i n the f o l l o w i n g  group had o c c u r r e d . manner:  T h i s was  con-  X-ray powder photographs  of  the sublimed s o l i d showed the presence of trimethylantimony difluoride.  The r e c o v e r e d methanol was  c o n t a i n e d boron t r i f l u o r i d e , which was infrared a portion  spectrum  highly  acidic  i d e n t i f i e d by i t s  and by the presence of boron and f l u o r i n e i n  of the r e c o v e r e d methanol.  Thus the product was  mixture of t r i m e t h y l a n t i m o n y b i s ( t e t r a f l u o r o b o r a t e ) difluovude. product was  The presence of the t e t r a f l u o r o b o r a t e i n f e r r e d from the i n f r a r e d  Trimethylantimony  a  and group  i n the  spectrum.  Hexafluorosilicate  Trimethylantimony fluorosilicate  and  dibromide  (1.0160 g.)  and s i l v e r hexa-  (1.1132 g.) were allowed t o r e a c t  methanol and a c o l o u r l e s s ,  i n 25 ml. of  deliquescent, c r y s t a l l i n e s o l i d  was  o b t a i n e d a f t e r removal of the methanol as d e s c r i b e d above. s o l i d was  sublimed under vacuum at 50°.  and i n f r a r e d  s p e c t r a of both the unsublimed  were i d e n t i c a l . H, 2.93,  Analysis,  F, 36.90.  powder photographs  calcd.  infrared  results  and sublimed s o l i d  f o r CgHgSbSiFg-. C, 11.65;  Found: C, 14.99; H, 3.71;  F, 28.00 X-ray  of the sublimed s o l i d showed the presence of  trimethylantimony d i f l u o r i d e . The  The a n a l y t i c a l  The  spectrum  Thus the product was  a mixture.  of a sample of the mixture exposed  to a i r  2showed the c h a r a c t e r i s t i c 735 and 480  cm" . 1  and gave p o s i t i v e  a b s o r p t i o n bands of the SiFg  The r e c o v e r e d methanol was  highly  tests  fluorine.  f o r both s i l i c o n and  i o n at  acidic  and  191 Trimethylantimony B i s ( h e x a f l u o r o a n t i m o n a t e ) (a)  Trimethylantimony  fluoroantimonate methanol.  dibromide  (0.7240 g.)  perature.  hexa-  (1.5236 g.) were allowed to r e a c t i n 25 ml. of  The s i l v e r bromide was  methanol was  and s i l v e r  f i l t e r e d o f f and most of the  removed from the f i l t r a t e under vacuum at room tem-  The  l a s t t r a c e s of the methanol c o u l d not be removed  even on prolonged pumping at 100°, and the product c o u l d not t h e r e f o r e be i s o l a t e d i n a pure s t a t e .  However, the recovered  methanol n e i t h e r showed any a c i d i t y nor gave a p o s i t i v e t e s t f o r e i t h e r f l u o r i n e or antimony, i n d i c a t i n g that no decomposition of hexafluoroantimonate had o c c u r r e d . (b)  The m e t a t h e t i c a l r e a c t i o n between t r i m e t h y l a n t i m o n y dibromide  (1.1080 g.) of  and s i l v e r hexafluoroantimonate  (2.3304 g.)  i n 25 ml.  l i q u i d sulphur d i o x i d e gave, f o l l o w i n g removal of the p r e c i -  p i t a t e d s i l v e r bromide and e v a p o r a t i o n of the sulphur d i o x i d e , an extremely h y g r o s c o p i c white s o l i d . C H S b ( S b F ) : F, 35.72. 3  9  6  photographs  2  of the s o l i d  Analysis, calcd. for  Obtained: F, 30.90.  X-ray powder  d i d not show any l i n e s due  antimony d i f l u o r i d e and the i n f r a r e d spectrum  to t r i m e t h y l -  of the  solid  confirmed the presence of hexafluoroantimonate group  in i t .  2The Trimethylantimony D e r i v a t i v e of B 1 2 C I 1 2 Trimethylantimony  dibromide  (0.3320 g.)  (0.7836 g.) were allowed to r e a c t i n methanol. off  and  Ag2 i2Cli2 B  After  filtering  the p r e c i p i t a t e d s i l v e r bromide, a c o l o u r l e s s s o l u t i o n  obtained,'which was  evaporated under vacuum at room  temperature  to g i v e a pink r e d s o l i d which c o n t a i n e d some methanol as c a t e d by i t s i n f r a r e d spectrum*  was  indi-  The r e c o v e r e d methanol was  not  192 a c i d i c and gave n e g a t i v e t e s t s f o r boron and c h l o r i n e ,  indicating  that no decomposition of the B12CI12 group had o c c u r r e d .  The  s o l i d was  then heated at about 60° under vacuum f o r about 6 hours.  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