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UBC Theses and Dissertations

Oxyfluorides, oxyfluorosulphates and oxycations of the halogens and selenium Carter, Henry Albert 1970

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OXYFLUORIDES, OXYFLUOROSULPHATES AND OXYCATIONS OF THE HALOGENS AND SELENIUM by HENRY ALBERT CARTER B.Sc. (Hons.) M c G i l l U n i v e r s i t y , Montreal, 1966 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 to the required standard THE UNIVERSITY OF BRITISH COLUMBIA I n p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t o f t h e r e q u i r e m e n t s f o r a n a d v a n c e d d e g r e e a t t h e U n i v e r s i t y o f B r i t i s h C o l u m b i a , I a g r e e t h a t t h e L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e a n d s t u d y . I f u r t h e r a g r e e t h a t p e r m i s s i o n f o r e x t e n s i v e c o p y i n g o f t h i s t h e s i s f o r s c h o l a r l y p u r p o s e s may be g r a n t e d by t h e H e a d o f my D e p a r t m e n t o r by h i s r e p r e s e n t a t i v e s . I t i s u n d e r s t o o d t h a t c o p y i n g o r p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l n o t be a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n . D e p a r t m e n t o f C k € . VA <-S"f f ^ T h e U n i v e r s i t y o f B r i t i s h C o l u m b i a V a n c o u v e r 8, C a n a d a D a t e December /<? . (°170 i ABSTRACT A l t e r n a t e routes f o r the p r e p a r a t i o n o f c h l o r y l f l u o r o s u l p h a t e , ClO^SO^Fj have been found. Evidence f o r the e x i s t e n c e o f the ch loronium c a t i o n , C 1 0 2 + , as a r e d - c o l o u r e d spec ies i n f l u o r o s u l p h u r i c a c i d , HSO^F, has been o b t a i n e d from e l e c t r i c a l c o n d u c t i v i t y measurements, employing C10"2S0 F and (C10" 2 ) 2 S 3° io ' d i c h l o r y 1 t r i s u l p h a t e , as s o l u t e s . n u c l e a r magnetic resonance and u v - v i s i b l e spectroscopy were a l s o used to s tudy s o l u t i o n s o f ClC^SOgF i n HSO^F, and are i n agreement w i t h the c o n d u c t i v i t y r e s u l t s . The i n f r a r e d and Raman s p e c t r a o f the whi te s o l i d s , c h l o r y l h e x a f l u o r o a r s e n a t e , c h l o r y l hexaf luoroant imonate and d i c h l o r y l h e x a f l u o r o s t a n n a t e have been o b t a i n e d . The observed v i b r a t i o n s have been i n t e r p r e t e d i n terms o f i o n i c compounds where s t r o n g c a t i o n - a n i o n i n t e r a c t i o n v i a f l u o r i n e b r i d g i n g r e s u l t s i n a symmetry l o w e r i n g o f the a n i o n . The e f f e c t o f t h i s i n t e r a c t i o n i s a l s o seen i n the Mossbauer spectrum o f ( C l O ^ ^ n F ^ , where a non-zero quadrupole s p l i t t i n g i s found. A l l compounds d i s s o l v e i n HSO^F to g ive r e d - c o l o u r e d s o l u t i o n s as a r e s u l t o f the f o r m a t i o n o f C1C>2+ c a t i o n s . Tn a d d i t i o n , c o n d u c t i v i t y measurements show c h l o r y l f l u o r i d e , C 1 0 2 F , to be c o m p l e t e l y ' . d i s s o c i a t e d i n HSO^F and t o form C 1 0 2 + c a t i o n s and SO^F" anions . ' , The v i b r a t i o n a l s p e c t r a o f C l F 2 A s F 6 , C l F 2 S b F 6 and B r F ^ b F ^ have been r e c o r d e d . In a l l compounds, v a r i o u s degrees o f a n i o n - c a t i o n i n t e r a c t i o n are f o u n d , r e s u l t i n g i n the l o w e r i n g of the symmetry o f the a n i o n . In a d d i t i o n , s t r o n g c o u p l i n g o f the v i b r a t i o n a l modes f o r BrF„SbF, are observed . i i An a l t e r n a t e route to the p r e p a r a t i o n o f KBrfSO^F)^ was found. A Raman spectrum o f t h i s compound i n d i c a t e s a square p l a n a r c o n f i g u r a t i o n f o r the an ion w i t h p o l a r bromine-oxygen bonds. The Raman s p e c t r a ob ta ined f o r the t r i s - f l u o r o s u l p h a t e s ICSO^F)^ and Br(SO^F)^ i n d i c a t e s the presence o f two types o f f l u o r o s u l p h a t e s groups and p o l y m e r i c s t r u c t u r e s f o r these compounds. The s t r u c t u r e o f i o d y l f l u o r o s u l p h a t e , IC^SO^F, has been examined by Raman spectroscopy and c o n d u c t i v i t y measurements i n HSO^F. Evidence i s found f o r d i s c r e t e I 0 2 groups l i n k e d by cova lent b i d e n t a t e f l u o r o s u l p h a t e groups. A Raman spectrum o f i o d y l f l u o r i d e showed i t to be d i s s i m i l a r t o the c h l o r i n e analogue, CIC^F , and possess a p o l y m e r i c s t r u c t u r e . No d i s c r e t e I 0 2 groups are found i n IO^AsFg on the b a s i s o f the i n f r a r e d spectrum. The new compound se lenium (IV) o x y f l u o r o s u l p h a t e , SeOCSO^F),,, has been prepared by the r e a c t i o n o f $2®^2 w -*- t ' 1 S e O C l 2 or SeO,,. The s t r u c t u r e o f S e O ( S 0 3 F ) 2 has been i n v e s t i g a t e d m a i n l y by Raman spectroscopy and conduct imetry i n H S 0 3 F . A s e l f - d i s s o c i a t i o n process o f the t y p e , S e O C S 0 3 F ) 2 = SeOCS0 3 F) + + S 0 3 F ~ , i s suggested f o r S e O ( S 0 3 F ) 2 to e x p l a i n the r e s u l t s o f the p h y s i c a l methods. A l s o , the a d d i t i o n o f S e O C l 2 t o S e O ( S 0 3 F ) 2 r e s u l t s i n the f o r m a t i o n o f SeOCSO_F)C1. Both SeO(SO F)C1 and SeO(SO F) show u n u s u a l l y h i g h Se=0 v i b r a t i o n a l s t r e t c h i n g f r e q u e n c i e s i n d i c a t i n g p o l a r Se-0S0„F bonds. i i i TABLE OF CONTENTS Page Abstract -'-i Table of Contents i i i L i s t of Tables v i L i s t of Figures V 1 1 Acknowledgements i x CHAPTER 1. INTRODUCTION 1.1 Oxyfluorides of the Halogens and Selenium 1 1.2 Scope of the Present Research 4 1.3 Preparative Routes to Fluorosulphates 5 1.4 Preparative Routes to Polyfluoroanion Complexes 7 2. GENERAL EXPERIMENTAL TECHNIQUES 2.1 Vacuum Systems and Apparatus 9 2.2 Reagents 20 2.3 Physical Experimental Methods 21 3. CHLORYL FLUOROSULPHATE: CHLORYL COMPOUNDS (RED) PART I 3.1 Introduction 27 3.2 Experimental 28 3.3 Results and Discussion 37 4. CHLORYL HEXAFLUOROMETALLATES: CHLORYL COMPOUNDS (WHITE) PART II 4.1 Introduction 60 4.2 Experimental 61 4.3 Results and Discussion 62 i v 5. DICHLORYL HEXAFLUOROSTANNATE: CHLORYL COMPOUNDS (WHITE) PART II CONTINUED 5.1 Introduction 79 5.2 Experimental 80 5.3 Results and Discussion 81 6. STRUCTURAL STUDIES OF HEXAFLUOROARSENATES AND -ANTIMONATES OF FLUORO-HALOGEN.HETEROCATIONS 6.1 Introduction 95 6.2 Experimental 99 6.3 Results and Discussion 99 7. BROMYL COMPOUNDS 7.1 Introduction 117 7.2 Experimental 118 7.3 Discussion 119 8. RAMAN STUDIES OF B r ( S 0 3 F ) 3 , I ( S 0 3 F ) 3 AND THE ANIONS B r ( S 0 3 F ) 4 " AND I ( S 0 3 F ) 4 ~ 8.1 Introduction 122 8.2 Experimental 123 8.3 Discussion 124 9. IODYL COMPOUNDS 9.1 Introduction 134 9.2 Experimental 136 9.3 Results and Discussion 141 10. SELENIUM (IV) OXYFLUOROSULPHATE 10.1 Introduction 160 10.2 Experimental 160 10.3 Results and Discussion 164 V 11. CONCLUSIONS AND SUMMARY 191 REFERENCES 194 APPENDIX 204 v i LIST OF TABLES Page 1. O x y f l u o r i d e s o f the Halogens and Selenium 2 2. E l e c t r i c a l C o n d u c t i v i t y of C10 2 S0 3 F 40 3. F i r s t I o n i z a t i o n P o t e n t i a l s of Diatomic and T r i a t o m i c M o l e c u l e s 42 4. S p e c i f i c C o n d u c t i v i t i e s of C l O ^ O ^ , ( C 1 0 2 ) 2 S 3 0 1 0 and K S 0 i n HS0 3 F 44 5 . S p e c i f i c C o n d u c t i v i t i e s o f ( C 1 0 2 ) 2 S 3 ° 1 0 i n H 2 S 0 4 4 9 6. 1 H NMR Chemical S h i f t s o f S o l u t i o n s o f C10 2 S0 3 F i n HS0 3 F 53 7. E l e c t r o n i c Spec t ra o f C10 2 S0 3 F i n HSC^F 55 8. The V i b r a t i o n a l Spec t ra o f C10„AsF. and C10„SbF. 63 Z D Z O 9. Assignment o f the C 1 0 2 V i b r a t i o n s 64 10. C 1 0 2 - S t r e t c h i n g Frequencies 64 11. Assignment o f the AsF^ V i b r a t i o n s 69 12. Assignment o f the SbF^ V i b r a t i o n s 69 13. S p e c i f i c C o n d u c t i v i t i e s o f CIO,,- compounds i n HS0 3F 74 14. V i b r a t i o n a l Frequencies f o r SnF^~ Compounds 82 15. V i b r a t i o n a l Frequencies f o r the SnF^ A n i o n 83 16. V i b r a t i o n a l Frequencies o f C 1 0 2 + i n ( C l O ^ S n F g 89 17. Mossbauer Data f o r SnF^~ Compounds 93 18. A s F o and SbF^ Complexes o f F l u o r o - and Oxy-element H e t e r o c a t i o n s 97 19. The V i b r a t i o n a l Spec t ra o f C l F 2 S b F 6 , C l F 2 A s F 6 and BrF„SbF, 100 2 6 + + 20. V i b r a t i o n a l Frequencies o f the spec ies C 1 F 2 and B r F 2 106 21. Frequency Assignments o f AsF^ i n C l F ^ s F ^ 108 22. Fundamental Frequencies f o r the AsF^ Anion 109 23. C o r r e l a t i o n diagram f o r the >*XEg Species 113 24. Fundamental f r e q u e n c i e s f o r the SbF^ a n i o n 114 25. V i b r a t i o n a l f r e q u e n c i e s f o r the ( H a l ( S 0 3 F ) ^ ) A n i o n 125 26. V i b r a t i o n a l f r e q u e n c i e s f o r B r ( S 0 3 F ) 3 and I ( S 0 3 F ) 3 126 v i i ! Page 27. C o r r e l a t i o n Diagram f o r the SO^F group 130 28. V i b r a t i o n a l Spec t ra o f I 0 F 3 and K I O ^ 143 29. V i b r a t i o n a l Spec t ra o f I 0 2 F , I 0 2 A s F 6 and 1 ^ 147 30. V i b r a t i o n a l Frequencies o f B r i d g i n g SO^F Groups 154 31. S p e c i f i c C o n d u c t i v i t i e s o f I 0 2 S 0 3 F i n HS0 3F 157 32. S p e c i f i c C o n d u c t i v i t y of Neat S e O ( S 0 3 F ) 2 as a F u n c t i o n o f Temperature 166 33. S p e c i f i c C o n d u c t i v i t i e s of S e O C l 2 and S e O ( S 0 3 F ) 2 i n HS0 3 F 171 34. C o n d u c t i m e t r i c T i t r a t i o n o f S e O ( S 0 3 F ) 2 i n HS0 3F w i t h Se 175 35. S p e c i f i c C o n d u c t i v i t i e s o f S e O ( S 0 3 F ) 2 i n Superac id 178 36. The Raman V i b r a t i o n a l S p e c t r a o f S e O ( S 0 3 F ) 2 and SeO(S0 3 F)Cl 182 37. Raman Spec t ra o f the S o l u t i o n s : S e O C l 2 i n l H S C ^ F , and S e O C l 2 i n S e O ( S 0 3 F ) 2 186 38. Chemical S h i f t s o f some Oxy Selenium-Compounds 187 39. Se-0 and S-0 S t r e t c h i n g Force Constants 189 LIST OF FIGURES 1. R e a c t i o n V e s s e l f o r S o l i d - L i q u i d and L i q u i d - L i q u i d Reac t ions 12 2. Monel M e t a l 2 -par t R e a c t i o n V e s s e l (Front View) 13 3 . Apparatus f o r the P r e p a r a t i o n o f $2®6^2 16 4. E l e c t r i c a l C o n d u c t i v i t y C e l l 22 5 . 3 - Compartment Diaphragm M i g r a t i o n C e l l (Front View) 36 6. C o n d u c t i v i t i e s of F l u o r o s u l p h a t e s i n HS0 3F 48 7. C o n d u c t i v i t y Curve o f (CIO ) S 3 0 1 0 i n H 2 S 0 4 50 8. 1 H NMR Chemical S h i f t s f o r S o l u t i o n s o f G,10 2S0 3F i n HS0 3F 52 9. U v - v i s i b l e Spectrum of C10 2 S0 3 F i n HS0 3F 54 v i i i 10. The Walsh Diagram f o r T r i a t o m i c Species 56 11. I n f r a r e d Spectrum of C 1 0 2 A s F 6 65 12. The Raman Spectrum o f C 1 0 2 A s F 6 66 13. C o n d u c t i v i t y Curves of AsF^ Compounds 76 14. The High R e s o l u t i o n I n f r a r e d Spectrum o f I^SnF^ 85 15. The I n f r a r e d Spectrum o f ( C 1 0 2 ) 2 S n F 6 87 16. The Raman Spectrum o f ( C 1 0 2 ) 2 S n F 6 88 17. The Mossbauer Spectrum o f ( C l O ^ S n F g 94 18. The I n f r a r e d Spectrum o f C l F 2 A s F 6 101 19. The Raman Spectrum o f ClF^AsF, , 102 Z D 20. The I n f r a r e d Spectrum o f C l F ^ S b F , and BrF n SbF^ 103 Z D Z D 21. The Raman S p e c t r a o f C l F „ S b F ^ BrF„SbF. and C10 oSbF^ 104 Z D Z D Z D 22. The C r y s t a l S t r u c t u r e o f BrF 2 SbF^ 111 23. The Raman S p e c t r a o f K B r ( S 0 3 F ) 4 , K I ( S 0 3 F ) 4 and B r ( S 0 3 F ) 3 128 24. Apparatus Used f o r the P r e p a r a t i o n o f I 0 F 3 139 25. Raman Spec t ra o f I 0 F 3 and K I 0 2 F 2 144 26. Raman Spectrum o f I 0 2 F 148 27. Raman Spectrum o f I 0 2 S 0 3 F 149 28. I n f r a r e d Spec t ra o f I 0 o F and I0„AsF, 150 f- Z Z D 29. The Proposed S t r u c t u r e f o r I 0 2 S 0 3 F 156 30. C o n d u c t i v i t y Curve of I 0 2 S 0 3 F i n HS0 3 F 158 31. C o n d u c t i v i t y of Neat S e 0 ( S 0 3 F ) 2 as a F u n c t i o n of Temperature 167 32. C o n d u c t i v i t y Curves o f S e 0 C l 2 and S e O ( S 0 3 F ) 2 i n HS0 3 F 173 33. C o n d u c t i m e t r i c T i t r a t i o n o f S e 0 ( S 0 3 F ) 2 i n HS0 3F w i t h Se 176 34. C o n d u c t i v i t y Study of S e 0 ( S 0 3 F ) 2 i n H S b F 2 ( S 0 3 F ) 4 179 35. Raman Spectrum o f S e O ( S 0 3 F ) 2 180 36. Raman Spectrum o f Se0(S0 F)C1 181 i x ACKNOWLEDGEMENTS I am v e r y g r a t e f u l to my r e s e a r c h d i r e c t o r , D r . F . Aubke, ; ' 7for h i s guidance and t e a c h i n g d u r i n g my years o f graduate s t u d i e s , and f o r h i s tremendous a s s i s t a n c e i n t h i s r e s e a r c h p r o j e c t . I am a l s o g r a t e f u l to my c o l l e a g u e s w i t h whom i t has been a p l e a s u r e to work, and, i n p a r t i c u l a r , Mr. A . M . Q u r e s h i , ; f o r many i n t e r e s t i n g and h e l p f u l d i s c u s s i o n s . I am indebted to D r . J . R . Sams and h i s r e s e a r c h group f o r o b t a i n i n g the Mossbauer s p e c t r a , and to D r . J . A . Ripmeester f o r 77 the Se NMR s p e c t r a . Thanks are due to the s t a f f o f the machine shop, e l e c t r o n i c s department and g l a s s b l o w i n g shop f o r the c o n s t r u c t i o n o f much o f the apparatus used i n . t h i s r e s e a r c h , and to M r s . B. K r i z s a n f o r the drawing o f the s p e c t r a l f i g u r e s . F i n a l l y , I would l i k e to thank my parents f o r t h e i r encouragement, p a t i e n c e and unders tanding over a l l the y e a r s . 1 C H A P T E R O N E INTRODUCTION 1.1 OXYFLUORIDES OF THE HALOGENS AND SELENIUM E l e m e n t - o x y g e n - f l u o r i n e compounds o f the type E O n F m where n and m are found to range from 1 - 5 , and where both f l u o r i n e and oxygen are d i r e c t l y bonded to the element are commonly known as o x y f l u o r i d e s . T h e i r p h y s i c a l and chemical p r o p e r t i e s depend p r i m a r i l y on the e l e c t r o -n e g a t i v i t y and the o x i d a t i o n s t a t e of the element s e r v i n g as the c e n t r a l atom. The known o x y f l u o r i d e s o f the halogens and se lenium are l i s t e d i n Table 1 a l o n g w i t h some o f t h e i r p r o p e r t i e s and p r e p a r a t i v e r o u t e s . The most genera l s y n t h e t i c r o u t e s t o o x y f l u o r i d e s a r e : (a) F l u o r i n a t i o n o f an o x i d e , e . g . CIO2F can be prepared by the f l u o r i n a t i o n o f C I C ^ • (b) F l u o r i n a t i o n o f oxyanions . e . g . CIO2F can be prepared from the f l u o r i n a t i o n o f KC103 by BrF 3„;or C1F 3 2' 3. A l s o , f l u o r o s u l p h u r i c a c i d has been found to be p a r t i c u l a r l y u s e f u l i n p r o d u c i n g o x y f l u o r i d e s 4 through i t s r e a c t i o n s w i t h oxyac ids and t h e i r s a l t s . (c) P a r t i a l replacement of f l u o r i n e i n f l u o r i d e s by oxygen, e . g . The 5-7 p a r t i a l h y d r o l y s i s o f IFy r e s u l t s i n the p r o d u c t i o n of IOF5 (d) L igand r e d i s t r i b u t i o n between a f l u o r i d e and an ox ide o f a common 8-10 element, e . g . The r e a c t i o n between 12^5 and IF5 produces IOF3 Review a r t i c l e s d e s c r i b i n g the p r e p a r a t i o n s and p r o p e r t i e s o f 11 12 o x y f l u o r i d e s o f the halogens and groups VB and VIB elements are a v a i l a b l e ' 2 TABLE 1 - OXYFLUORIDES OF THE HALOGENS AND SELENIUM OXYFLUORIDE PREPARATIVE ROUTES PHYS. PROP.* REF. REMARKS C10 2 F 2 i + F 2 (-50°) a . C I O b . KCIOT + BrF. m.p. b . p . -115° 1 H i g h l y r e a c t i v e ; - 6° 2,3 A t t a c k s g l a s s C10 3 F a . K C 1 0 3 + F 2 ( -40° ) m.p. b . KCIO4 + HSO3F ( 7 0 ° ) b . p . •146° • 47° 13-16,2 R e l a t i v e l y u n r e a c t i v e ; 17 Very s t a b l e Br0 2 F a . B r 0 2 + F 2 ( - 5 0 ° ) b . K B r 0 3 + B r F 5 m.p. - 9° dec. 56° Thermal ly u n s t a b l e ; A t t a c k s g l a s s I 0 2 F Decomposi t ion o f IOF3 at 110° dec . 210 c 8-10 S tab le i n the absence o f mois ture IO3F HIO4 + F 2 (HF) dec . 100° 19 S tab le i n g l a s s v e s s e l s . I0F: I 2 0 5 + I F 5 dec. 110° -10 C r y s t a l s t r u c t u r e known I0F c P a r t i a l h y d r o l y s i s o f I F 7 t . p . 4 . 6 ° s u b l . - 1 . 9 ° 5-7 Very r e a c t i v e I 0 2 F 3 H0I0F 4 + S0 3 m.p. 41c 20 S tab le i n d r y a i r ; 2 d i f f e r e n t isomers SeOF. Se0 2 + F 2 b . Se0 2 + SeF 4 m.p. 15 c b . p . 126 c 30 21 C o l o u r l e s s l i q u i d Se0 2 F. BaSe0 3 + HS0 3F (150°) m.p. -99 c b . p . - 8C 22 C o l o u r l e s s gas A l l temperatures i n degrees Cent igrade 3 T h i s present r e s e a r c h i s concerned w i t h the p o t e n t i a l o f o x y f l u o r i d e s to form o x y c a t i o n s and o x y f l u o r o c a t i o n s . T h i s can be accomplished i n two ways: (a) The f l u o r i n e atom i s a b s t r a c t e d from the o x y f l u o r i d e by a Lewis a c i d . T h i s r e a c t i o n occurs i n genera l f o r a number o f the o x y f l u o r i d e s of the main group e lements . For example, the r e a c t i o n o f AsF^ w i t h o x y f l u o r i d e s o f n i t r o g e n proceeds as f o l l o w s : FNO + A s F 5 = N 0 + A s F 6 " (23) FN0 2 + A s F 5 = N 0 2 + A s F 6 " (24) F 3NO + A s F 5 = F 2 N O + A s F 6 " (25,26) In p a r t i c u l a r , the f o r m a t i o n o f o x y c a t i o n s o f the halogens and se lenium might be achieved by the r e a c t i o n o f o x y f l u o r i d e s w i t h Lewis a c i d s such as A s F ^ , SbF^, BF3, S 0 3 and SnF,^. ( e . g . The r e a c t i o n s o f these Lewis a c i d s w i t h C10 2 F leads to the complexes C 1 0 2 A s F Q , C 1 0 2 S b F 6 , C10 2 BF4, C10 2S03F and ( C 1 0 2 ) 2 S n F Q , but the e x i s t e n c e o f C 1 0 2 + has not been determined. ) (b) The o x y f l u o r i d e s are s o l v o l y z e d i n s t r o n g p r o t o n i c s o l v e n t s such as HF, H 2S04 and HSO3F to y i e l d o x y c a t i o n s . ( e . g . The e x i s t e n c e of I 0 2 + i n l i q u i d HF w i t h I 0 2 F as the s o l u t e has been proposed by Schmeisser 29 and Lang .) A combinat ion of both methods of forming o x y c a t i o n s would be the s o l u t i o n ; - s t u d i e s o f o x y c a t i o n complexes. Here , i t would be advantageous to employ element o x y f l u o r o s u l p h a t e s as s o l u t e s and f l u o r o s u l p h u r i c a c i d , HSO3F, as the s o l v e n t f o r the f o l l o w i n g r e a s o n s : 4 (a) HSO^F i s a s t r o n g p r o t o n i c a c i d , and many p o l y c a t i o n s such as lg"1" and Se^** have been found to e x i s t i n t h i s m e d i u m ^ . The a c i d i t y of the a c i d may a l s o be i n c r e a s e d by the a d d i t i o n of SO3 and SbF,. r e s u l t i n g 28 i n s u p e r a c i d media (b) S o l u t i o n s t u d i e s are s i m p l i f i e d when the s o l u t e and s o l v e n t have common a n i o n s . (c) Many methods are a v a i l a b l e f o r the p r e p a r a t i o n of f l u o r o s u l p h a t e s . The i n t e r m e d i a t e f o r m a t i o n o f the f l u o r i d e i s not r e q u i r e d (see s e c t i o n 1 . 3 ) . 1.2 SCOPE OF THE PRESENT RESEARCH The problems i n t h i s r e s e a r c h p r o j e c t can now be d e f i n e d as f o l l o w s : (1) the s y n t h e s i s o f o x y f l u o r o s u l p h a t e s o f the halogens and s e l e n i u m , analogous t o the known o x y f l u o r i d e s , and an examinat ion o f t h e i r p h y s i c a l and chemical p r o p e r t i e s . (2)". the i d e n t i f i c a t i o n o f o x y c a t i o n s p o s s i b l y e x i s t i n g i n these compounds, and a l s o i n p o l y f l u o r o a n i o n complexes o f the Lewis a c i d s ASF5, SbF$ and S n F ^ e i t h e r i n s o l u t i o n or i n the s o l i d s t a t e . (3) s p e c t r o s c o p i c s t u d i e s o f the r e l a t e d compounds i n (2) c o n t a i n i n g f l u o r o c a t i o n s . Though many o f these compounds have been p r e v i o u s l y s y n t h e s i z e d , s t r u c t u r a l s t u d i e s f o r the m a j o r i t y are not a v a i l a b l e . 5 1.3 PREPARATIVE ROUTES TO FLUOROSULPHATES F l u o r o s u l p h a t e s were o r i g i n a l l y prepared by the a d d i t i o n o f s u l p h u r t r i o x i d e to element f l u o r i d e s as a c c o r d i n g t o : E F n + nS0 3 » E ( S 0 3 F ) n T h i s r e a c t i o n i s u s e f u l i n the p r e p a r a t i o n of a l k a l i or a l k a l i n e e a r t h metal f l u o r o s u l p h a t e s , b u t , i n g e n e r a l , i s not a s u i t a b l e method f o r the s y n t h e s i s of f l u o r o s u l p h a t e s . In the case o f t r a n s i t i o n metal t r i o x i d e i s o f t e n incomplete even at h i g h temperatures and w i t h j l a r g e excess* o f SO^. In recent y e a r s , however, the syntheses of p e r o x y d i s i i l p h u r y l d i f l u o r i d e (by Dudley and C a d y ^ i n 1957) and i t s d e r i v a t i v e s have made p o s s i b l e the p r e p a r a t i o n o f a l a r g e number of f l u o r o s u l p h a t e s . To d a t e , there are three f l u o r o s u l p h o n a t i n g agents which are commonly employed to prepare f l u o r o s u l p h a t e s . The most e f f e c t i v e agent and most convenient to handle i s p e r o x y d i s u l p h u r y l d i f l u o r i d e , S20 o F2-Prepared by the c a t a l y t i c f l u o r i n a t i o n o f s u l p h u r t r i o x i d e vapour at 180° i n the presence o f s i l v e r C H ) f l u o r i d e , i t i s the f l u o r o s u l p h a t o analogue t o e lementa l f l u o r i n e . Indeed, i t s r e a c t i o n s are v e r y s i m i l a r 36 37 to those of f l u o r i n e where f r e e r a d i c a l s are i n v o l v e d : and non-metal f l u o r i d e s 32-34 , f o r example, the a d d i t i o n o f s u l p h u r 2F- AH, D i s s . = 38 k c a l / m o l e AH, UlSS . = 21 k c a l / m o l e -6 P e r o x y d i s u l p h u r y l d i f l u o r i d e behaves as a pseudohalogen whose r e a c t i v i t y and e l e c t r o n e g a t i v i t y i s c o n s i d e r a b l y g r e a t e r than c h l o r i n e but l e s s than f l u o r i n e . $ 2 0 ^ 2 d i s p l a c e s oxygen and c h l o r i n e from oxides and c h l o r i d e s r e s p e c t i v e l y to form the corresponding f l u o r o s u l p h a t e s , and adds across the double bond o f p e r f l u o r o - o l e f i n s . I t r e a c t s 41 42 w i t h the halogens t o form halogen f l u o r o s u l p h a t e s ' which are s i m i l a r i n a formal sense t o the i n t e r h a l o g e n s . As i n the case o f f l u o r i n e , 3 2 0 ^ 2 r e a c t s e x p l o s i v e l y w i t h a l l o r g a n i c matter i g n i t i n g i t spontaneous ly . As a consequence o f i t s p h y s i c a l p r o p e r t i e s ( b . p . 6 7 . 1 ° , m.p. - 5 5 . 4 ° ) , however, S 2 0^F2 can be c o n v e n i e n t l y handled i n a vacuum l i n e , and i n the absence of m o i s t u r e , can be s t o r e d i n g l a s s v e s s e l s . A l t h o u g h somewhat l e s s e a s i e r to handle i n a vacuum system, bromine monof luorosulphate ^ > ^ , BrSO^F ( b . p . 1 1 7 . 3 ° ) , has a l s o proved to be a good f l u o r o s u l p h o n a t i n g agent . I t i s p a r t i c u l a r l y u s e f u l i n i t s r e a c t i o n s w i t h n o n - m e t a l ( C , S , S i , P ) o x y c h l o r i d e s and c h l o r i d e s to y i e l d bromine monochloride and f l u o r o s u l p h a t e s . By the use of bromine f l u o r o s u l p h a t e as the f l u o r o s u l p h a t i n g agent , o x i d a t i o n o f the n o n - m e t a l , o f t e n encountered when S20^F2 i s employed, i s a v o i d e d . The t h i r d f l u o r o s u l p h a t i n g agent which has found use i n the past i n the p r e p a r a t i o n o f f l u o r o s u l p h a t e s 6<f the a l k a l i and a l k a l i n e e a r t h m e t a l s ^ 5 ' ^ i s f l u o r o s u l p h u r i c a c i d , HSO^F. R e c e n t l y , f i r s t 47 48 t r a n s i t i o n metal f l u o r o s u l p h a t e s ' and f l u o r o s u l p h a t o d e r i v a t i v e s o f t i n ^ have been prepared by m e t a t h e t i c a l r e a c t i o n s o f the anhydrous metal c h l o r i d e s or f l u o r i d e s w i t h f l u o r o s u l p h u r i c a c i d . 7 The above discussion has meant to serve as an introduction to the methods of preparing fluorosulphates and the three fluorosulphating agents which are commonly used. Review a r t i c l e s discussing the chemistry of f l u o r o s u l p h a t e s ^ , and sulphur-fluorine compounds can be found i n the l i t e r a t u r e ^ . The i n v e s t i g a t i o n of possible fluorosulphato compounds has been pursued i n the past on the basis of the well-established chemistry of the analogous inorganic f l u o r i d e s (e.g. S20^F2 v.s. F 2 , HSO3F v.s. HF and KBr(S03F)4 v.s. KBrF^). As synthetic routes to oxyfluorides (Table 1) often involve the use of elemental f l u o r i n e , i t was hoped to prepare oxyfluorosulphates by analogous reactions s u b s t i t u t i n g 8 2 0 ^ 2 for F2 . 1.4 PREPARATIVE ROUTES TO POLYFLUOROANION COMPLEXES Polyfluoroanion complexes can most often be prepared by the reaction of an element f l u o r i d e or element oxyfluoride with a Lewis acid such as AsFg, SbFc; or BF3. This d i r e c t reaction of the f l u o r i d e s i s not always, however, the best means of synthesizing heterocation polyfluoroanion complexes. Other methods are a v a i l a b l e , and these can be summarized as follows: £a) The reaction of an oxyfluoride with the chlorine analogue of the Lewis a c i d . e.g. The synthesis of ( C l O ^ ^ ^ F ^ i s achieved by the reaction of CIO2F with SnCl4-(b) The r e a c t i o n of an oxychloride with the Lewis a c i d . e.g. The syntheses of N 0 A s F 6 , NOSbFg, N0 2AsF 6 and N0 2SbF 6 can be accomplished by reactions of N0C1 and N02C1 re s p e c t i v e l y with the 53 Lewis acids AsF,- or SbF 5 . The highly r e a c t i v e compounds NOF and NO2F are not required. (c) The r e a c t i o n of an o x y f l u o r i d e w i t h o x i d e s . e . g . The r e a c t i o n o f C10 2 F w i t h S b 2 0 5 or at -10° leads to the f o r m a t i o n of C 1 0 2 S b F 6 or C 1 0 2 B F 4 5 4 . I t i s noteworthy tha t these three a l t e r n a t i v e methods o f p r e p a r i n g p o l y f l u o r o a n i o n complexes are e s s e n t i a l l y the same as the d i r e c t r e a c t i o n o f the f l u o r i d e s s i n c e the o x i d e s , c h l o r i d e s and o x y c h l o r i d e s i n v o l v e d are f l u o r i n a t e d i n the i n i t i a l s tages o f the r e a c t i o n . 9 C H A P T E R T W O GENERAL EXPERIMENTAL TECHNIQUES The purpose o f t h i s chapter i s t o d i s c u s s genera l exper imenta l t e c h n i q u e s , appara tus , ins truments and m a t e r i a l s commonly used throughout the r e s e a r c h d e s c r i b e d i n t h i s t h e s i s . More s p e c i a l i z e d techniques and a l l chemical r e a c t i o n s o ther than the s y n t h e s i s o f ^2^6^2 a r e d i s c u s s e d s e p a r a t e l y i n the a p p r o p r i a t e c h a p t e r . 2.1 VACUUM SYSTEMS AND APPARATUS 2 .1 .1 General N e a r l y a l l compounds encountered i n t h i s r e s e a r c h were u n s t a b l e to moist a i r . I t was necessary , t h e r e f o r e , t o use a d r y - b o x c o n t a i n i n g a p u r i f i e d n i t r o g e n atmosphere f o r the t r a n s f e r o f m a t e r i a l s . A l l v o l a t i l e compounds were handled i n e i t h e r g l a s s or monel metal vacuum l i n e s c o n s t r u c t e d on metal frame-works i n s i d e fumehoods. Many o f the compounds were found t o be e x p l o s i v e towards a l l o r g a n i c m a t e r i a l , and s o m e , p a r t i c u l a r l y the se lenium compounds, ' i are h i g h l y t o x i c . Consequent ly , great care was e x e r c i s e d i n t h e i r h a n d l i n g , and a l l r e a c t i o n s were performed i n w e 1 1 - v e n t i l a t e d fumehoods. 2 .1 .2 The Dry-box The Vacuum Atmospheres C o o r p o r a t i o n Model HE-43-2 D r i - L a b w i t h a Model HE 93-B D r i - T r a i n was used . P u r i f i e d " L grade" n i t r o g e n p r o v i d e d an i n e r t atmosphere f o r the d r y - b o x . 10 The n i t r o g e n was c i r c u l a t e d through the d r i - t r a i n equipped w i t h L i n d e ' s m o l e c u l a r s i e v e s , which c o u l d be regenerated by use o f an oven i n c o r p o r a t e d i n the system. The process o f r e g e n e r a t i o n was performed monthly to m a i n t a i n a dry atmosphere. 2 . 1 . 3 The General Purpose Vacuum L i n e T h i s c o n s i s t e d o f a g lass m a n i f o l d w i t h a B19 j o i n t attachment to the s a f e t y t r a p assembly and f i v e B10 outer j o i n t o u t l e t s c l o s e d to the l i n e by F i s c h e r and P o r t e r t e f l o n v a l v e s . These g r e a s e l e s s v a l v e s were found to m a i n t a i n a good vacuum, and i n t h i s r e s p e c t , were s u p e r i o r to normal g l a s s v a l v e s which o f t e n leak as a r e s u l t o f reagent a t t a c k o f the stopcock grease . Vacuum was obta ined by a s tandard r o t a r y vacuum pump. The p r e s s u r e o f the system was measured by a mercury manometer a t tached to one o f the B10 outer j o i n t s . A l a y e r o f K e l - F o i l covered the mercury column to p r o t e c t i t from c o r r o s i v e m a t e r i a l . Before use , the vacuum m a n i f o l d was c leaned w i t h d i s t i l l e d w a t e r , d r i e d , and f i n a l l y f lamed w i t h an oxygen-gas burner to e l i m i n a t e a l l t r a c e s o f m o i s t u r e . 2 .1 .4 The M e t a l Vacuum L i n e In the h a n d l i n g o f compounds r e a c t i v e towards g l a s s , i t was necessary to use a monel metal vacuum l i n e . The vacuum m a n i f o l d c o n s i s t e d o f monel metal t u b i n g , 1/4" O . D . and 1/32" w a l l t h i c k n e s s , j o i n e d by Swagelok f i t t i n g s and equipped w i t h Whitey v a l v e s (1KS4.316) l e a d i n g to the o u t l e t s . 11 The m a n i f o l d was a t tached to the g l a s s s a f e t y t r a p v i a a " C a j o n " j o i n t . Gas pressures w i t h i n the system were measured w i t h a h e l i c o i d t e s t guage and a Kontes i o n i z a t i o n guage. 2 .1 .5 Glass R e a c t i o n V e s s e l s A t y p i c a l r e a c t i o n v e s s e l employed i n r e a c t i o n s i n v o l v i n g a n o n - v o l a t i l e substance and a v o l a t i l e r e a c t a n t i s shown i n F i g u r e 1. The s t a r t i n g m a t e r i a l was i n t r o d u c e d i n the d r y box at the B19 j o i n t . A f t e r removal from the d r y - b o x , the v e s s e l was sea led at the c o n s t r i c t i o n . The r e a c t i o n v e s s e l was then a t tached t o the vacuum l i n e at the BIO j o i n t and the v o l a t i l e r e a c t a n t condensed on t o the s t a r t i n g m a t e r i a l by vacuum d i s t i l l a t i o n . 2 .1 .6 M e t a l R e a c t i o n V e s s e l s Compounds r e a c t i v e t o g l a s s were handled i n monel metal 2 -par t r e a c t i o n v e s s e l s (F igure 2 ) . These metal c o n t a i n e r s were equipped w i t h a Hoke v a l v e (No. 431) , a removable l i d and a t e f l o n gasket which was f i t t e d i n between the l i d and the v e s s e l to p r o v i d e a vacuum-t ight s e a l . The l i d was secured t o the bottom v e s s e l by s i x b o l t s fas tened by an A l l e n wrench. The r e a c t i o n v e s s e l c o u l d be connected to one o f the vacuum l i n e socket o u t l e t s by means of Swagelok n u t s , w i t h f r o n t and back t e f l o n f e r r u l e s i n s e r t e d to p r o v i d e a vacuum-t ight f i t . In a d d i t i o n , 1 l i t r e and 500 ml monel and n i c k e l c o n t a i n e r s , equipped w i t h Hoke 431 or Whitey v a l v e s were used as s torage or weighing c o n t a i n e r s f o r v o l a t i l e f l u o r i n e compounds. B19 Cone + 125 ml Pyrex Erlenmeyer -> F l a s k +- BIO Cone <- BIO Cone •«- F i s c h e r and P o r t e r T e f l o n Va lve T e f l o n V a l v e T h i c k - w a l l Glass Reac t ion V e s s e l S ide View of F i s c h e r and P o r t e r T e f l o n V a l v e FIGURE 1 - React ion V e s s e l For S o l i d - L i q u i d and L i q u i d - L i q u i d React ions Hoke V a l v e (No. 431) Monel Meta l Tube B o l t s to Secure L i d to Bottom V e s s e l Condenser I n l e t Bottom -«- Condenser I n l e t Monel Meta l Reac t ion V e s s e l (150 ml) FIGURE 2 - Monel Meta l 2 -Part React ion V e s s e l (Front View) 1 4 2 . 1 . 7 The F l u o r o s u l p h u r i c A c i d D i s t i l l a t i o n L i n e The apparatus and techniques i n v o l v e d i n the p u r i f i c a t i o n o f f l u o r o s u l p h u r i c a c i d s u i t a b l e f o r c o n d u c t i v i t y measurements have u i A -u J 4 5 , 6 0 been p r e v i o u s l y d e s c r i b e d . F l u o r o s u l p h u r i c a c i d was p u r i f i e d by double d i s t i l l a t i o n , and f o r i t s use i n c o n d u c t i v i t y measurements, f i n a l l y d i s t i l l e d d i r e c t l y i n t o the c o n d u c t i v i t y c e l l a t tached to the d i s t i l l a t i o n a p p a r a t u s ' ^ by means o f a B 1 9 j o i n t . L-grade n i t r o g e n was a l l o w e d to pass through the c o n d u c t i v i t y c e l l and d i s t i l l a t i o n apparatus f o r at l e a s t two h o u r s , d u r i n g which time the apparatus was f lamed p e r i o d i c a l l y to e l i m i n a t e m o i s t u r e . P u r i f i e d f l u o r o s u l p h u r i c a c i d p o s s e s s i n g - 4 - 1 - 1 a s p e c i f i c c o n d u c t i v i t y l e s s than 1 . 3 0 x 1 0 0, cm was deemed s a t i s f a c t o r y f o r c o n d u c t i v i t y measurements. The lowest s p e c i f i c c o n d u c t i v i t y r e p o r t e d i s 1 . 0 8 x 1 0 4 £2 •''cm * 2 . 1 . 8 The F l u o r i n e L i n e And The P r e p a r a t i o n Of S ^ F . ^ The f l u o r i n e l i n e and the f l o w apparatus used f o r the s y n t h e s i s o f ^2^(^2 ( i l l u s t r a t e d i - n F i g u r e 3 ) was b u i l t from copper t u b i n g ( 1 / 4 " O . D . , 1 / 3 2 " w a l l t h i c k n e s s ) on a metal framework i n a fumehood. A l l connect ions were made by Swagelok f i t t i n g s . A u t o c l a v e e n g i n e e r i n g v a l v e s were used to r e g u l a t e the f l u o r i n e p r e s s u r e from the c y l i n d e r . (A Crosby p r e s s u r e guage i n d i c a t e d t h i s p r e s s u r e . ) As shown i n F i g u r e 3 , Hoke diaphragm v a l v e s (No. 4 1 3 K ) were used e x t e n s i v e l y throughout the system and were found to be r e l i a b l e and r e s i s t a n t towards f l u o r i n e . F l u o r i n e was passed through a s t a i n l e s s s t e e l c y l i n d e r c o n t a i n i n g sodium f l u o r i d e to remove i m p u r i t i e s o f HF. Strong b o l t s which c o u l d be opened by an A l l e n wrench f a s t e n e d the two removable l i d s to the c y l i n d e r , and l e a k - t i g h t s e a l s were achieved by t e f l o n g a s k e t s . The c y l i n d e r was wound w i t h Nichrome r i b b o n , i n s u l a t e d w i t h asbestos paper and f i n a l l y w i t h asbestos s t r i n g to permit e l e c t r i c a l h e a t i n g , needed f o r the r e g e n e r a t i o n o f sodium f l u o r i d e . The s u l p h u r t r i o x i d e , c o n t a i n e d i n a pyrex f l a s k , was c a r r i e d by d r y L grade n i t r o g e n to the r e a c t o r where i t mixed w i t h a stream o f f l u o r i n e . The r e a c t a n t s passed through the furnace forming products which were condensed out i n t r a p s A , B and C. A f l u o r o l u b e o i l bubble counter gave a v i s u a l i n d i c a t i o n o f the f l o w r a t e o f excess T^-The s y n t h e s i s o f ^2^(^2 ^ a S ^ e e n P r e v i ° u s l y d e s c r i b e d i n d e t a i l ^ While the d e s i g n o f the apparatus i s e s s e n t i a l l y the same as tha t r e p o r t e d i n the l i t e r a t u r e , a number o f m o d i f i c a t i o n s were made w i t h the r e s u l t o f i n c r e a s e d y i e l d s . The c a t a l y s t A g F 2 was prepared i n s i t u as a c c o r d i n g t o Shreeve and Cady^"*". However, a l a r g e r r e a c t o r (120 x 7.6 cm v . s . 90 x 7.6 cm. was employed to extend the r e s i d e n c e t ime o f the r e a c t a n t s . A l s o , a r e a c t o r temperature o f 180°C. ( v . s . 150°C. ) was found t o g i v e the best r e s u l t s . The r e a c t o r was heated i n a s i m i l a r f a s h i o n as the NaF t r a p , but i t was necessary t o wind a second c o i l o f nichrome w i r e about the r e a c t o r to p r o v i d e adequate h e a t i n g . Thermocouples i n s e r t e d beneath the asbestos l a y e r s i n d i c a t e d the 1 temperature at v a r i o u s p o i n t s a l o n g the r e a c t o r . Whitey Valve Hoke 413 Valve = Autoclave Engineering Valves Crosby Pressure Guage To cylinder To Soda-lime Trap Fluorolube O i l Tube FIGURE 3 - Apparatus for the Preparation of S n,F 2 6 2 17 To a v o i d the condensat ion o f f l u o r i n e f l u o r o s u l p h a t e ( e x p l o s i v e i n l a r g e q u a n t i t i e s ) , t r a p s B and C were both c o o l e d at -78°C. (dry i c e ) i n s t e a d o f l i q u i d oxygen ( -183°C. ) f o r t r a p C used i n the l i t e r a t u r e p r e p a r a t i o n . Trap A was l e f t empty and served to remove n o n - v o l a t i l e s i d e - p r o d u c t s . F i n a l l y , s u l p h u r t r i o x i d e was heated i n i t s f l a s k at about 50°C. ( v . s . 2 5 ° C ) . A p r e s s u r e of 15 mm i n excess o f atmospheric p r e s s u r e f o r both F^ and r e s u l t e d i n the p r o d u c t i o n o f ^>2^(^2 a t a b ° u 1 : 150 g . / h r . ( v . s . 6 g . / h r . ) once the above r e a c t i o n c o n d i t i o n s had been o b t a i n e d . A number o f d i f f i c u l t i e s i n t h i s p r e p a r a t i o n may be avoided i f the f o l l o w i n g p o i n t s are n o t e d : (1) The n i t r o g e n i n l e t tube t o the s u l p h u r t r i o x i d e f l a s k c o n t a i n e r should not be a l l o w e d t o d i p i n t o the l i q u i d , as l i q u i d (y-SO^) tends t o change t o s o l i d (g-SO^) which can r e s u l t i n the tube becoming p l u g g e d . (2) The copper t u b i n g connec t ing the o u t l e t from the r e a c t o r to the c o o l i n g t r a p s must be f lamed r e g u l a r l y to a v o i d c l o g g i n g by condensed m a t e r i a l i n the tube . (3) Traps B and C must be checked r e g u l a r l y and r e p l a c e d by empty t r a p s when the $2®^2 ^ e v e ^ r i s e s t 0 the i n l e t tube . (4) A l s o , l a r g e amounts o f s o l i d m a t e r i a l (SO^) i n these t r a p s i n d i c a t e s t h a t the f l o w r a t e i s too h i g h , w h i l e the presence o f a green c o l o u r i n the l i q u i d (due to FSO^F) i m p l i e s tha t the F 2 f l o w r a t e must be reduced. Unreacted s u l p h u r t r i o x i d e was removed from the product by e x t r a c t i o n w i t h 96-98 % H»S0. i n a s e p a r a t o r y f u n n e l i n the fumehood. 18 (This o p e r a t i o n should be o n l y attempted when necessary . A w e l l - v e n t i l a t e d fumehood i s e s s e n t i a l . Even though no r e p o r t s on the t o x i d i t y o f 6 2 S^O^F^ e x i s t , the r e p o r t e d extreme t o x i d i t y of the r e l a t e d S^O^F^, d i s u l p h u r y l d i f l u o r i d e , can be regarded as a w a r n i n g . ) The p e r o x i d e f r a c t i o n was then cooled t o -78°C. and pumped f o r s e v e r a l hours u n t i l a l l t r a c e s o f f l u o r i n e f l u o r o s u l p h a t e had been e l i m i n a t e d . F i n a l l y , S^O^F^ was vacuum d i s t i l l e d i n t o a t e f l o n v a l v e s torage t r a p . I t s p u r i t y was checked by an ' IR spectrum o f the gas and an NMR spectrum o f the l i q u i d . 2 .1 .9 Source of M a t e r i a l s and Equipment T h i s s e c t i o n g ives f u r t h e r i n f o r m a t i o n and the names and addresses of manufacturers o f a p p a r a t u s , equipment and m a t e r i a l s used i n t h i s r e s e a r c h : 1. K e l - F grease : Formula = C l ( C ^ - C F C l ^ C l ; 3M, M i n n e s o t a , M i n i n g and M a n u f a c t u r i n g Co. S t . P a u l , M i n n . 2. F l u o r o l u b e grease GR-362: F i s h e r S c i e n t i f i c C o . , F a i r Lawn, N . J . These greases were used s u c c e s s f u l l y i n the l u b r i c a t i o n o f s top-cocks and apparatus employed i n the h a n d l i n g o f f l u o r i n e - c o n t a i n i n g compounds. 3. The Crosby High Pressure Guage: Manufactured by C r o s b y , Ashton V a l v e and Guage Co. , Wrentham, Mass. 4. Kontes I o n i z a t i o n Guage: Kontes o f I l l i n o i s , F r a n k l i n P a r k , -3 I l l i n o i s 60131. U s e f u l i n measuring pressures i n the range 1mm - 1 0 Hg. 5. H e l i c o i d Test Guage: American Chain and Cable Co. B r i d g e p o r t , New J e r s e y : U s e f u l i n measuring pressures i n the range 1mm - 1000 mm. 19 6. Swagelok F i t t i n g s : d i s t r i b u t e d by Crawford f i t t i n g s (Canada) L t d . N i a g a r a F a l l s , Ont. 7. F l u o r o l u b e O i l : formula .= CF 2 C1 ( C F 2 C F C l ) x C F 2 C l ; Hooker Chem. C o r p . N i a g a r a F a l l s 8. L inde M o l e c u l a r S i e v e s : produced by Linde A i r Products and d i s t r i b u t e d by F i s h e r S c i e n t i f i c Co. 9. F i s c h e r and P o r t e r t e f l o n v a l v e s : F i s c h e r and P o r t e r Co. Warminster , Pa . 10. Kontes V a l v e s : Kontes o f I l l i n o i s , F r a n k l i n P a r k , I l l i n o i s 60131 11. Rota f low v a l v e s : Made by Q u i c k f i t and Quartz L t d . , S tone, S t a f f o r d s h i r e y England ; V a l v e s i n 9, 10, and 11 i n c o r p o r a t e d i n g l a s s v e s s e l s were found convenient to use and l e a k - t i g h t . 12. Whitey v a l v e s (1KS4.316) : manufactured by Whitey Research Tool Co. 5525 M a r s h a l l S t . , Oakland 8, C a l i f . 13. Hoke V a l v e s : (a) No. .431 (b) No. 413K Made by Hoke Inc . C r e s k i l l , New J e r s e y 14. A u t o c l a v e E n g i n e e r i n g V a l v e s (MV30): made by A u t o c l a v e E n g i n e e r i n g Inc . 2930 W. 22nd S t . , E r i e , P a . 20 2.2 REAGENTS A number of purchased reagents which were used e x t e n s i v e l y d u r i n g the course o f t h i s r e s e a r c h are i n d i c a t e d i n the t a b l e below. Other chemicals used l e s s f r e q u e n t l y and not l i s t e d h e r e , and genera l " s h e l f " reagents are d e s c r i b e d i n the exper imenta l s e c t i o n under the a p p r o p r i a t e c h a p t e r . COMPANY SUBSTANCE % PURITY CLAIMED BY MANUFACTURER A l l i e d Chemical (Canada) L t d . S 0 3 (Sul fan) HS0 3F H 2 S 0 4 Not Given Not Given Not Given 95.5 - 96.5 A l p h a I n o r g a n i c Chemical C o r p . SbF 5 KAsF^ 6 KSbF 5 K 2 S n F 6 Not Given Not Given 95 Not Given B r i t i s h Drug Houses Se Se0 2 SeOCl. 99.0 99.0 97.5 Matheson Co. HF C1F, BrF_ 99.9 98.0 98.0 Ozark Mahoning Co. Not Given 2.3 PHYSICAL EXPERIMENTAL METHODS 2 .3 .1 E l e c t r i c a l Conduct imetry S o l u t i o n s o f a number of compounds i n f l u o r o s u l p h u r i c a c i d and s u l p h u r i c a c i d were s t u d i e d by e l e c t r i c a l c o n d u c t i v i t y measurements. 45 The techniques i n v o l v e d , i n c l u d i n g the d e s i g n of the c o n d u c t i v i t y c e l l , 45 the p u r i f i c a t i o n of HSO^F , and the p r e p a r a t i o n of "minimum c o n d u c t i n g " H ^ S O ^ '^^, have been p r e v i o u s l y d e s c r i b e d . A t h r e e - e l e c t r o d e c o n d u c t i v i t y c e l l w i t h approximate c e l l constants o f 5 , 10 and 15 cm * was used . The c e l l was c a l i b r a t e d w i t h aqueous s o l u t i o n s o f potass ium c h l o r i d e ^ , and the e l e c t r o d e s ' were p l a t i n i z e d ^ , as r o u t i n e procedures p r e c e d i n g a c o n d u c t i v i t y r u n . C o n d u c t i v i t y measurementsjwere made w i t L a Wayne Kerr U n i v e r s a l Br idge B 221A, w h i l e the c e l l was conta ined i n a constant temperature o i l b a t h o f 2 5 . 0 0 ' ± 0 .01°C. w i t h a Sargent Thermonitor CModel ST) . The bath temperature was measured w i t h a p r e c i s i o n thermometer, p r e v i o u s l y checked aga ins t a p l a t i n u m r e s i s t a n c e thermometer, obta ined from B r o o k l y Thermometer Co. The c o n d u c t i v i t i e s o f neat l i q u i d s were measured i n the e l e c t r i c a l c o n d u c t i v i t y c e l l i l l u s t r a t e d i n F i g u r e 4. The c e l l constant was about 1 c m - * , and approx imate ly 2 m l . o f l i q u i d were r e q u i r e d f o r accurate c o n d u c t i v i t y measurements. The c e l l , loaded i n the d r y - b o x , conta ined a p u r i f i e d n i t r o g e n atmosphere. 22 FIGURE 4 - E l e c t r i c a l C o n d u c t i v i t y C e l l ( a c t u a l s c a l e ) B 1 9 1 f Copper Wire Mercury Sample p t S o l i d Glass E l e c t r o d e s 23 2 .3 .2 I n f r a r e d Spectroscopy I n f r a r e d s p e c t r a were recorded on a P e r k i n - E l m e r 457 G r a t i n g Spectrophotometer c o v e r i n g the range 4000 - 250 cm ^. Higher r e s o l u t i o n i n f r a r e d s p e c t r a were obta ined from a P e r k i n Elmer 301 High R e s o l u t i o n G r a t i n g Spectrophotometer (4000 - 100 cm * ) . Owing t o the h i g h r e a c t i v i t y o f the m a j o r i t y o f compounds i n v e s t i g a t e d , e i t h e r s i l v e r c h l o r i d e or KRS-5 windows were used w i t h o u t the use of m u l l i n g agents . KRS-5 ( T h a l l i u m b r o m i d e - i o d i d e ) windows have the advantage o f p e r m i t t i n g the r e c o r d i n g o f i n f r a r e d s p e c t r a down to 250 cm 1 , but are g e n e r a l l y more s u s c e p t i b l e to chemical a t tack than are the AgCl windows which " c u t o f f " at about 400 cm Gaseous i n f r a r e d s p e c t r a were ob ta ined u s i n g a monel metal c e l l equipped w i t h a Hoke v a l v e (No. 431) and f i t t e d w i t h vacuum t i g h t AgCl windows. The c e l l windows were cut from AgCl sheets (0.042" i n t h i c k n e s s ) and p l a c e d i n the c e l l i n the absence o f l i g h t . Black tape was employed to p r o t e c t the windows when the c e l l was not i n use . A l l i n f r a r e d o p t i c a l windows were obta ined from The Harshaw Chemical Company, 1945 East 97th S t . , C l e v e l a n d , Ohio 44106 2 . 3 . 3 Raman Spectroscopy A Cary 81 Spectrophotometer equipped w i t h a Spec t ra P h y s i c s Model 125 He - Ne l a s e r as a source of e x c i t i n g l i g h t (A. = 6328 A) was used . The s o l i d samples were conta ined i n " o p t i c a l " f l a t bottom pyrex tubes (6 mm O . D . ) . 24 Raman c e l l s f o r l i q u i d s were s i m i l a r to the c e l l s used f o r s o l i d s but were e i t h e r T-shaped o r L - s h a p e d to permit t h e i r be ing f l a m e - s e a l e d a f t e r be ing loaded and capped i n s i d e the dry box. 2 .3 .4 Mossbauer Spec t ra The Mossbauer spectrometer c o n s i s t e d o f a TMC Model 305 v e l o c i t y t ransducer d r i v e n at constant a c c e l e r a t i o n by a TMC model 306 wave form generator which a l s o s y n c h r o n i z e d the 400 channel a n a l y s e r . The t r a n s m i t t e d r a d i a t i o n was de tec ted by a Reuter -S tokes RSG - 60 p r o p o r t i o n a l counter w i t h 2 atmospheres Xe-CH^ as f i l l gas , and fed i n t o a N u c l e a r Chicago model 33-15 s i n g l e channel a n a l y s e r and then to a 400 channel memory. The output was d i s p l a y e d on an Hewlett Packard model 120 B o s c i l l o s c o p e and a l s o p r i n t e d out on a model 44-16 IBM t y p e w r i t e r . The p r i n t o u t o f the spectrometer was f i t t e d t o a L o r e n z t i a n curve on an IBM 4070 computer. Other computer programmes were a v a i l a b l e t o p o s s i b l y r e s o l v e quadrupole s p l i t t i n g i n broadened peaks . The source o f the 119m gamma r a d i a t i o n was BaSnO^ e n r i c h e d w i t h Sn which p r o v i d e s a s i n g l e narrow emiss ion l i n e . Samples were p l a c e d on a brass c e l l w i t h mylar windows and the s p e c t r a run at 295° and 80°K. The doppler v e l o c i t y s c a l e was c a l i b r a t e d a g a i n s t the quadrupole s p l i t t i n g o f an NBS s tandard n i t r o p r u s s i d e absorber . The isomer s h i f t s were r e p o r t e d r e l a t i v e to Sn02 at 80°K. The es t imated p r e c i s s i o n o f Mossbauer parameters i s ± 0.03 mm sec l . 25 2 .5 .5 UV - V i s i b l e Spectroscopy A Cary Recording Spectrophotometer Model 14 w i t h a lamp supply (IR, UV, V i s i b l e ) Model D from A p p l i e d P h y s i c s C o r p o r a t i o n was used to o b t a i n e l e c t r o n i c s p e c t r a i n the range X = 2000 - 7000 A. Quartz o p t i c a l c e l l s were obta ined from P y r o c e l l M a n u f a c t u r i n g Co. and p r o v i d e d w i t h o p t i c a l spacers which reduced the path l e n g t h from 10.00 mm t o 1.00, 0 .50 , 0.20 and 0.05 mm. A t e f l o n gasket f i t t e d between the spacer and the c e l l exc luded mois ture from the sample s o l u t i o n . The c e l l s were kept t i g h t l y shut t o prevent f o g g i n g , a n d h y d r o l y s i s d u r i n g the measurement by u s i n g a c e l l h o l d e r made i n our machine shops. The s o l u t i o n s were prepared and the c e l l s f i l l e d i n the dry box. 2 .3 .6 N u c l e a r Magnetic Resonance Spectroscopy 19 F NMR s p e c t r a were o b t a i n e d , u s i n g a V a r i a n HR100 spectrometer , and employing C F C l ^ i n g l a s s c a p i l l a r i e s as an e x t e r n a l s t a n d a r d . ^H NMR s p e c t r a were measured w i t h r e s p e c t to HSO^F as an e x t e r n a l s t a n d a r d , and by u s i n g a V a r i a n HR60 spectrometer . 77 Se NMR s p e c t r a were recorded on a V a r i a n DP60 spectrometer . A d e s c r i p t i o n o f t h i s instrument and the techniques used i n o b t a i n i n g 6 7 the s p e c t r a have been p r e v i o u s l y d e s c r i b e d w i t h the f o l l o w i n g e x c e p t i o n s : 77 The Se resonances were observed at a frequency of 10.0 MHz i n a resonance f i e l d o f about 12300 gauss . For narrow l i n e s , the method o f A c r i v o s was used w i t h a modulat ion frequency o f 432 cps and a modula t ion index o f 1.5 - 2 . 0 , w h i l e f o r the broad l i n e s , the d e r i v a t i v e method was employed. Samples were p l a c e d i n 15 mm O . D . tubes . Chemical s h i f t s were ob ta ined by the sample replacement method, u s i n g neat S e O C ^ as a r e f e r e n c e . 2 . 3 . 7 X-Ray Powder Photography F i n e l y powderedvsamples were packed i n t o 0.5 mm Lindemann g l a s s c a p i l l a r i e s i n s i d e the d r y - b o x . The tubes were sea led w i t h K e l - F grease and then flame s e a l e d a f t e r removal from the d r y - b o x . X - ray powder photographs were obta ined u s i n g a General E l e c t r i c Powder Camera o f 14.32 cm diameter and h a v i n g the c o n v e n t i o n a l Straumanis arrangement. Time of exposure u s i n g n i c k e l - f i l t e r e d copper x - r a d i a t i o n (XK^ = 1.54050 A) g e n e r a l l y v a r i e d from 4 - 6 h o u r s . I l l f o r d " I l l f e x " f i l m was used f o r the s p e c t r a . A f i l m i l l u m i n a t o r and measuring d e v i c e obta ined from P h i l i p s E l e c t r o n i c s I n c . was used to measure the l i n e spacings from which " d " spacings c o u l d be o b t a i n e d . C H A P T E R T H R E E CHLORYL FLUOROSULPHATE CHLORYL COMPOUNDS (RED) PART I 3.1 INTRODUCTION C h l o r y l f l u o r o s u l p h a t e , C102S0gF, was f i r s t prepared i n s m a l l 3 amounts by Woolf i n 1954 by the d i r e c t a d d i t i o n o f s u l p h u r t r i o x i d e to c h l o r y l f l u o r i d e . T h i s r e a c t i o n was d e s c r i b e d to be v i o l e n t , and subsequent i n v e s t i g a t i o n s on the r e a c t i o n s and p r o p e r t i e s o f c h l o r y l f l u o r o s u l p h a t e were not made. Woolf p o s t u l a t e d an i o n i c s t r u c t u r e f o r t h i s compound, 0 0 2 - S O g F . C h l o r y l f l u o r o s u l p h a t e i s a h i g h l y r e a c t i v e r e d s o l i d at room temperature which mel ts at about 27°C. However, i t i s o f t e n observed as a r e d l i q u i d at room temperature due t o the presence o f s m a l l i m p u r i t i e s , and a tendency to s u p e r c o o l , common to many f l u o r o s u l p h a t d e r i v a t i v e s . A r e l a t e d compound and a l s o a red s o l i d , d i c h l o r y l t r i s u l p h a t e , (0102)2^3020? w a s prepared by Lehmann and Krueger by the r e a c t i o n of SO^ and C ^ O j . " ' ' ' . By analogy to the i o n i c compound, (N02 +)2^3^10^ ^ d i c h l o r y l t r i s u l p h a t e was a l s o suggested to have an i o n i c s t r u c t u r e . No s t r u c t u r a l i n v e s t i g a t i o n s have been made, however, to support the i o n i c f o r m u l a t i o n s f o r e i t h e r CIO2SO2F o r (C10 2 )2^30^^. 28 I t i s the o b j e c t o f the r e s e a r c h d e s c r i b e d i n t h i s chapter t o f i n d convenient routes to the p r e p a r a t i o n o f c h l o r y l f l u o r o s u l p h a t e , and to prove the e x i s t e n c e o f the c h l o r y l c a t i o n , VAO^. 3.2 EXPERIMENTAL 3 . 2 . 1 The R e a c t i o n Between KC1C>3 and S 2 0 6 F 2 An excess o f S 2 0^F2 was d i s t i l l e d i n vacuo to a r e a c t i o n v e s s e l (F igure 1) c o n t a i n i n g , i n a t y p i c a l r e a c t i o n , 31.52 mmoles o f f i n e l y powdered KCIO^ ( A . R . ) at -196°C. Upon warming to room temperature , a m i l d r e a c t i o n took p l a c e w i t h the l i b e r a t i o n of 0 2 , and the f o r m a t i o n o f a r e d l i q u i d and a white s o l i d . (At the temperature o f l i q u i d n i t r o g e n , the c o l o u r o f the r e d compound faded to a y e l l o w c o l o u r , a p r o p e r t y c h a r a c t e r i s t i c o f c h l o r y l compounds.) The r e a c t i o n r a t e was i n c r e a s e d by h e a t i n g at 5 0 ° C , and a f t e r about 4 h o u r s , the e v o l u t i o n o f 0 2 had ceased and the r e a c t i o n was complete . A f t e r the removal o f S 2 0 5 F 2 by pumping, c h l o r y l f l u o r o s u l p h a t e was separated from the product mixture by d i s t i l l a t i o n i n vacuo and at e l e v a t e d temperatures , about 80 - 100°C. The remaining product corresponded to 31.59 mmoles o f KSO3F, and i t s i d e n t i t y was conf i rmed by an i n f r a r e d spectrum. C h l o r y l f l u o r o s u l p h a t e was found to be a very r e a c t i v e l i q u i d , i g n i t i n g o r g a n i c m a t e r i a l and e x p l o d i n g w i t h water . A l l attempts t o prepare K C I O ^ S O ^ F ^ at low temperatures by c o n t r o l l i n g the r e a c t i o n o f KCIO^ and $2^(3* 2 a t a t e m P e r a 1 : u r e ° f - 20°C. were u n s u c c e s s f u l . In a l l c a s e s , a mixture o f CIO2SO.JF and KSO^F r e s u l t e d . The e x i s t e n c e o f the f l u o r i n e analogue, KCIO2F2, has 81 been r e c e n t l y r e p o r t e d by Fox et a l . 29 3 . 2 . 2 The R e a c t i o n Between C 1 0 2 and S 2 0 6 F 2 C h l o r i n e d i o x i d e was prepared from KCIO^ and L^SO^ i n the presence 57 o f o x a l i c a c i d as a c c o r d i n g to Brauer . The p u r i f i c a t i o n o f CIO2 was accomplished by pumping at -78°C. to e l i m i n a t e i m p u r i t i e s o f C 0 2 and by t r a p t o t r a p d i s t i l l a t i o n . As CIO2 i s known to be an u n p r e d i c t M e l y e x p l o s i v e compound, the f o l l o w i n g p r e c a u t i o n s were taken to minimize the dangers i n v o l v e d i n i t s p r e p a r a t i o n and h a n d l i n g : (1) The p r e p a r a t i o n o f CIO2 was performed i n a darkened fumehood as CIO2 i s l i g h t s e n s i t i v e . (2) Only s m a l l q u a n t i t i t e s o f C1C>2 were prepared i n a s i n g l e run 57 (about 1/10 the amount o f s t a r t i n g m a t e r i a l s suggested by Brauer ) . (3) The CIO2 generated i n the r e a c t i o n f l a s k was immediate ly coo led by a c o l d water j a c k e t i n c o r p o r a t e d i n the stem o f the r e a c t i o n f l a s k . An excess o f S 2 0 ^ F 2 was d i s t i l l e d on to about 3 g . o f C10 2 c o n t a i n e d i n a r e a c t i o n v e s s e l coo led at -196°C. The r e a c t i o n f l a s k was warmed to - 4 0 ° C , where a m i l d r e a c t i o n took p l a c e r e s u l t i n g i n the f o r m a t i o n o f r e d c r y s t a l s o f C102S0 3 F. A check f o r the p r o d u c t i o n o f non-condens ib le gases was negat ive as the manometer r e g i s t e r e d zero p r e s s u r e f o r the system at -196°C. The f i n a l product was o b t a i n e d i n a pure form by removing the excess p e r o x i d e by d i s t i l l a t i o n at room temperature . I t s e x i s t e n c e as a r e d c r y s t a l l i n e s o l i d at room temperature - i t melted when p l a c e d i n i t s c o n t a i n e r i n a water bath at about 30°C. - was i n d i c a t i v e o f the h i g h p u r i t y o f the p r o d u c t . 3® 3 . 2 . 3 Other Attempts To Prepare O x y f l u o r o s u l p h a t e s Of C h l o r i n e 58 An excess o f 820^2, prepared by the r e a c t i o n o f SO3 w i t h SbF^ , was d i s t i l l e d i n vacuo on to KCIO^ c o n t a i n e d i n a r e a c t i o n v e s s e l . At temperatures up to 8 0 ° C , no r e a c t i o n was e v i d e n t . ^2^6^2 f a - i - ' - e c * t 0 r e a c t w i t h ClO^F and KCIO^ up to temperatures o f 100°C. 3 .2 .4 The R e a c t i o n Between NaC10„ and S„0 .F„ I Z o I The r e a c t i o n between f i n e l y powdered NaC102 CA . R . ) and $20^2, performed under c o n d i t i o n s s i m i l a r to those i n s e c t i o n 3 . 2 . 1 , proceeded s l o w l y at -10°C. and r a p i d l y at room temperature w i t h e v o l u t i o n o f O2, CIO2 and the f o r m a t i o n of a r e d s o l i d . At r e a c t i o n c o m p l e t i o n , the 19 excess p e r o x i d e was removed by d i s t i l l a t i o n . I n f r a r e d and F NMR s p e c t r a r e v e a l e d a l a r g e amount o f ^>2^^2 to be present i n the r e s i d u a l p e r o x i d e . The r e d s o l i d melted at about room temperature , and i t s removal by d i s t i l l a t i o n i n vacuo l e f t behind a whi te s o l i d which was i n d i c a t e d by the weight change and an i n f r a r e d spectrum to be NaS0 3 F. In a d i f f e r e n t r u n , the r e a c t i o n was h a l t e d at an incompletes stage and a Raman spectrum obta ined o f the r e d - c o l o u r e d product m i x t u r e . The f o l l o w i n g products were i d e n t i f i e d : Unreacted NaC102 ( V 3 C 1 ( ) - 832 c m - 1 , V 1 C 1 0 - 804 c m " 1 ) , NaS0 3F (1291, 1078, 800, 592, 2 -1 2 -1 -1 570, and 420 cm ) and C 1 0 2 ( v 3 c i 0 1103 cm , v l c l Q 949 cm ) . No evidence f o r the c h l o r o s y l c a t i o n , CIO , i s o e l e c t r o n i c w i t h 0^ -1 59 + ( v n = 1555 cm ) was f o u n d , w h i l e C 1 0 ? v i b r a t i o n s were e i t h e r h idden by SO2 v i b r a t i o n s , or d i d not appear as a r e s u l t o f a b s o r p t i o n o f the e x c i t i n g l i g h t by the red c o l o u r e d s p e c i e s . On one o c c a s i o n , the r e a c t i o n v e s s e l exploded wi thout warning d u r i n g the course of the r e a c t i o n . The e x p l o s i v e substance i n the system was undoubtedly c h l o r i n e d i o x i d e . T h e r e f o r e , the above r e a c t i o n should be performed w i t h extreme c a r e . 3 .2 .5 The R e a c t i o n Between KNO, And S o 0 ^ F „ 3 2 6 2 The r e a c t i o n s of $2®^ 2 W l t h N0.j and NO^ were i n v e s t i g a t e d t o g a i n f u r t h e r i n f o r m a t i o n on the r e a c t i o n s o f S^O^F^ w i t h s a l t s o f oxyac ids i n g e n e r a l . An excess o f S_0^.Fo was r e a c t e d w i t h KN0_ ( A . R . ) under s i m i l a r 2 6 2 o c o n d i t i o n s as i n s e c t i o n 3 . 2 . 1 . The r e a c t i o n proceeded r a p i d l y at room temperature w i t h the e v o l u t i o n o f 0^ and the f o r m a t i o n o f a mixture o f whi te s o l i d s i d e n t i f i e d by Raman s p e c t r a as KSO^F and N02S0 3 F. The weight change was i n agreement w i t h the f o r m a t i o n of these s o l i d s and 0^ as the o n l y p r o d u c t s . 3 . 2 . 6 The R e a c t i o n Between NaNO 'and S . 0 . F o z 2 o z An excess of S o 0 . F „ was r e a c t e d w i t h NaN0„ ( A . R . ) under s i m i l a r 2 6 2 2 c o n d i t i o n s as i n s e c t i o n 3 . 2 . 1 . The r e a c t i o n proceeded s l o w l y w i t h the e v o l u t i o n of O2 and f o r m a t i o n of whi te s o l i d s . To complete the r e a c t i o n , the f l a s k was heated at 65°C. f o r s e v e r a l days. A Raman spectrum of the product mix ture r e v e a l e d the presence of NaS0 3F and N 0 2 S 0 3 F ( N 0 2 + 1408 c m " 1 ) . A second r u n , i n which the S„0^F . was removed be fore r e a c t i o n z o I comple t ion and the temperature kept at 2 5 ° C , r e s u l t e d i n a d i f f e r e n t Raman spectrum f o r the product m i x t u r e . A g a i n , NaS0 3 F (S0 2sym 1072 cm 1 was observed , but the peak at 1408 cm \ t y p i c a l f o r N 0 2 + was absent . I n s t e a d , a peak was seen at 2303 cm 1 , i n d i c a t i n g the presence of N 0 + and t h e r e f o r e N0S0 3F (S0 2 sym 1090 c m - 1 ) . Peaks observed at 1333, 832 and 1265 cm 1 are due t o unreacted NaN0 2 -3 . 2 . 7 P r e p a r a t i o n o f ( C l O ^ ^ O and D i c h l o r y l t r i s u l p h a t e and potass ium t r i s u l p h a t e were prepared by the r e a c t i o n of potass ium c h l o r a t e w i t h s u l p h u r t r i o x i d e as a c c o r d i n g to Lehmann and K r u e g e r . " ^ ( C 1 0 2 ) 2 S 3 0 ^ Q was separated from K 2 S 3 0 ^ Q by vacuum s u b l i m a t i o n at temperatures l e s s than 8 0 ° C . i n t o a t r a p cooled at - 7 8 ° C. To remove i m p u r i t i e s o f ( C 1 0 ) ( C 1 0 2 ) S 3 0 1 0 , a s m a l l q u a n t i t y of C 1 0 2 was d i s t i l l e d on to the crude C C 1 0 2 ) 2 S 3 0 ^ Q and the mix ture a l l o w e d t o warm t o 0 °C. over a p e r i o d of s e v e r a l h o u r s . The excess C 1 0 2 and the l i b e r a t e d gases , 0 2 and C l 2 were removed by pumping at 0 °C. The f i n a l product melted at 7 4 ° C . ( repor ted 7 5 . 5 ° C . 5 5 ) . The r e s i d u a l K 2 S 3 0 1 Q was heated at 1 5 0 ° C . u n t i l a l l t r a c e s of ( C 1 0 2 ) 2 S 3 0 ^ Q had been e l i m i n a t e d . The r e s u l t i n g whi te s o l i d was t r e a t e d w i t h an excess o f S 0 3 to convert i m p u r i t i e s o f I C ^ O ^ , 33 a r i s i n g from the decomposi t ion o f K^S^O^^, back to -^2^3^10* T ^ e ^ 3 was then removed by pumping, and the p u r i t y o f the r e s u l t i n g product checked by an a c i d - b a s e t i t r a t i o n of the aqueous , - so lut ion . 3 . 2 . 8 R e a c t i o n o f CIO^SO F w i t h KF At room temperature , c h l o r y l f l u o r o s u l p h a t e r e a c t e d v i g o r o u s l y w i t h anhydrous KF, and w i t h e f f o r v e s c e n c e . An i n f r a r e d spectrum showed the gas t o be C l O ^ F , w h i l e a Raman spectrum i d e n t i f i e d the r e s i d u a l s o l i d as KSO^F. 3 . 2 . 9 React ions o f C10 2 S0 3 F w i t h P e r f l u o r o - O l e f i n s 3 . 2 . 9 . 1 C 2 F Into a t w o - p a r t metal r e a c t i o n v e s s e l (F igure 2 ) , about 1 g . o f ClO^SO^F was added i n the d r y - b o x . A s m a l l excess o f C^F^ ( P e n i n s u l a r Chem. Research I n c . ) was d i s t i l l e d on to the CIC^SO^F at - 1 9 6 ° C. Upon warming to room temperature , a v i o l e n t e x p l o s i o n e r u p t e d . No f u r t h e r s t u d i e s o f t h i s r e a c t i o n were at tempted. 3 . 2 . 9 . 2 C . F . 4 4 An excess o f p e r f l u o r o c y c l o - 2 - b u t e n e was d i s t i l l e d on to about 1 g . ClO^SO^F conta ined i n a g l a s s r e a c t i o n v e s s e l coo led at -196°C. Upon warming t o room temperature , the r e a c t i o n v e s s e l and contents exploded. The study of the r e a c t i o n between C^F^ and ClO^SO^F was subsequent ly abandoned. An excess of p e r f l u o r o - 2 - b u t e n e (Matheson Co . ) was condensed i n t o a h e a v y - w a l l e d 100 m l . r e a c t i o n v e s s e l , equipped w i t h a F i s c h e r and P o r t e r t e f l o n v a l v e , c o n t a i n i n g about 2 g . C102S0gF at - 1 9 6 ° C . At room temperature , two l a y e r s c o n s i s t i n g o f unreacted C102S0,jF (bottom red l a y e r ) and unreacted C.F (upper c o l o u r l e s s l a y e r ) were 4 o observed. On warming to about 70°C. and shaking the c o n t a i n e r v i g o r o u s l y f o r about 20 m i n u t e s , a l l t r a c e s of C102S0 3F disappeared and a c o l o u r l e s s l i q u i d remained. The removal of the excess o l e f i n l e f t behind a v i s c o u s l i q u i d . The weight change was c o n s i d e r a b l y l e s s than t h a t expected f o r a 1:1 a d d i t i o n compound. Both i n f r a r e d and Raman s p e c t r a o f the l i q u i d product showed the presence of cova lent SO^F groups , and the absence o f the o l e f i n C=C double bond. No s t r o n g peaks i n the r e g i o n 850 - 1250 cm 1 were observed , and t h e r e f o r e , i t was d i f f i c u l t to r e c o n c i l e the e x i s t e n c e o f cova lent CIO2 groups i n the compound. In a d d i t i o n , a weak peak was seen i n the v i b r a t i o n a l s p e c t r a at 1890 cm 1 and i t can be a t t r i b u t e d to the FC=0 g r o u p i n g . 19 Due to the c o m p l e x i t y o f the F NMR and mass s p e c t r a of the product m i x t u r e , the products were not i d e n t i f i e d . 3 . 2 . 9 . 4 C T F , o o Into a 500 ml g l a s s r e a c t i o n v e s s e l c o n t a i n i n g about 1 g . C102S0 3 F, 1 atmosphere of hexaf luoropropene ( P e n i n s u l a r Chem. Research Co. ) was condensed. An exothermic r e a c t i o n took p l a c e at room temperature 35 between the gas and the r e d l i q u i d . A f t e r the e lapse o f about % h o u r , a l l C K ^ S O ^ F had r e a c t e d , and a c o l o u r l e s s l i q u i d remained. A l l v o l a t i l e m a t e r i a l at -78°C. was d i s t i l l e d i n t o another t r a p . Gaseous i n f r a r e d s p e c t r a o f the product were v e r y s i m i l a r to tha t obta ined from the products o f the C.F - CIO SO F r e a c t i o n . A g a i n , cova lent S0_F groups 4 o z S 6 and the FC=0 group were seen, w h i l e the o l e f i n C=C bond was absent . 3 . 2 . 9 . 5 C ,F . . _ o l U The r e a c t i o n between ClO^SO^F and p e r f l u o r o c y c l o h e x e n e ( P e n i n s u l a r Chem. Research I n c . ) was c a r r i e d out i n s i m i l a r opera t ions to those d e s c r i b e d i n s e c t i o n 3 . 2 . 9 . 3 . At room temperature , a slow r e a c t i o n took p l a c e , but on h e a t i n g f o r about 1 hour at 50°C. and w i t h v i g o r o u s s h a k i n g , the r e d c o l o u r o f ClO^SO^F disappeared and a c o l o u r l e s s l i q u i d remained. The excess o l e f i n was removed by d i s t i l l a t i o n at -10°C. A g a i n , i n f r a r e d s p e c t r a i n d i c a t e d compounds c o n t a i n i n g the FC=0 group, r a t h e r than 1:1 a d d i t i o n p r o d u c t s . 3 .2 .10 S o l u t i o n S tudies 19 1 The b e h a v i o r . o f C10 2 S0 3 F i n HS0 3F was examined by F and H NMR s p e c t r o s c o p y , U V - v i s i b l e spectroscopy and c o n d u c t i v i t y measurements. In a d d i t i o n , c o n d u c t i v i t y measurements were obta ined f o r (C10 2 ) 2 S 3 0 . ^ Q and K 2 S 3 0 1 Q i n HS0 3F and ( C 1 0 2 ) 2 S 3 0 1 0 i n 100% H 2 S 0 4 . 36 The p u r i f i c a t i o n o f HSO^F, r e f e r r e d t o i n s e c t i o n 2 . 1 . 7 , r e q u i r e d a d d i t i o n a l steps be fore i t s use i n U V - v i s i b l e s p e c t r a l s t u d i e s . About 2 g . S^O^F^ were added t o the crude HSCLF, c o n v e r t i n g any i m p u r i t i e s o f SO (X = 2940 my) o z in 3.x to S „ 0 o F o . Excess S „ 0 , F o and S „ 0 o F _ were then e l i m i n a t e d i n the f o r e r u n . 3 o 2 z o 2 o o z Spec t ra o f the C 1 0 2 + c a t i o n were ob ta ined by r u n n i n g the sample spectrum versus neat HSO^F i n the re fe rence c e l l . A three compartment diaphragm m i g r a t i o n c e l l used i n s t u d y i n g ( i n HSO^F) the e l e c t r o l y s i s o f C l O ^ O ^ F i s i l l u s t r a t e d i n F i g u r e 5 . The middle compartment was f i l l e d i n the d r y - b o x w i t h a s o l u t i o n o f C l O ^ O ^ F i n HSO F and the outer compartments w i t h HS0_F. A f t e r the c u r r e n t was turned on , the cathode compartment g r a d u a l l y turned y e l l o w as c h l o r i n e d i o x i d e was l i b e r a t e d at the cathode. The e l e c t r o l y s i s was e f f e c t e d by a F i s h e r S c i e n t i f i c E l e c t r o Model D-612T f i l t e r e d D . C . Power Supply . HS0 3 F -* B19 > E l e c t r o d e B19 Sample S o l u t i o n B19 Socket B19 Cone E l e c t r o d e Diaphragm FIGURE 5 - 3-Compartment Diaphragm M i g r a t i o n C e l l (Front View) The a d d i t i o n o f KCIO^ to HSO^F i n a t e s t tube produced a y e l l o w s o l u t i o n w i t h v i g o r o u s e f forvescence of C l O ^ . I t seems tha t c h l o r i n e d i o x i d e i s produced i n the s o l v o l y s i s o f KCIO^ i n HSO^F, r a t h e r than chloronium c a t i o n s . T h i s i s i n c o n t r a s t to the s o l v o l y s i s o f n i t r a t e s and n i t r i c a c i d which s o l v o l y s e i n s t r o n g p r o t o n i c a c i d s to produce .„ •. 68-70 m t r o n i u m c a t i o n s 3 .3 RESULTS AND DISCUSSION 3 . 3 . 1 The P r e p a r a t i o n o f C 1 0 2 S 0 3 F ; The Reac t ions o f S 2 0 6 F 2  With C h l o r i n e and N i t r o g e n - C o n t a i n i n g O x y - s a l t s Two convenient and n o v e l routes t o the s y n t h e s i s o f ClO^SO^F have been o b t a i n e d : KC10- + S o 0 , F o j z o z 2C10 2 + S 2 0 6 F 2 Both r e a c t i o n s are analogous t o the f o r m a t i o n o f C10 2 F from the f l u o r i n a t i o n o f K C l O j 2 , 3 and C l O ^ . R e a c t i o n (1) i s t y p i c a l of the chemis t ry o f ^ O ^ F ^ where the p r e p a r a t i o n o f f l u o r o s u l p h a t e s i s accomplished by f l u o r o s u l p h a t e f r e e r a d i c a l a t t a c k and subsequent e x p u l s i o n o f oxygen. The f a i l u r e o f S 2 0;_F 2 t o r e a c t w i t h KCIO^ i s not s u r p r i s i n g as a f r e e r a d i c a l mechanism i s not a v a i l a b l e i n i t s r e a c t i o n s . 25°C. — • KS0_F + C10 oS0_F + %0o Slow 3 2 3 2 -40°C. 2C10„S0,F Fast 2 3 38 The second r e a c t i o n occurs at a f a s t e r r a t e and a l s o e l i m i n a t e s the n e c e s s i t y o f s e p a r a t i n g ClO^SO^F from s o l i d KSO^F i n (1 ) . The main disadvantage h e r e , o f c o u r s e , i s the use o f the p o t e n t i a l l y e x p l o s i v e CIO,,. The p r e p a r a t i o n o f ClO^SO^F from SO^F- r a d i c a l s and CIC^ was p r e d i c t e d by an e a r l i e r and analogous f r e e r a d i c a l 37 r e a c t i o n s by L u s t i g and Cady i n which these authors prepared NF_S0„F from S . 0 , F _ and N 0 F . . Z O Z 0 Z Z 4 S„0 ,F„ f a i l e d to r e a c t w i t h KC10. and C10-F , i s o e l e c t r o n i c to the 2 o 2 4 J p e r c h l o r a t e a n i o n . The s t a b i l i t y of the c o o r d i n a t i v e l y s a t u r a t e d •71 72 ClO^F molecule and the C l O ^ anion i s w e l l - k n o w n . ' The r e a c t i o n between NaCIO,, and S^O^F^ produces c h l o r i n e d i o x i d e as a r e s u l t o f S^O^F 2 behaving as a pseudohalogen: NaC10 o + S_0 ,F- > NaSO-F + C10 o Z Z D Z J Z C 1 0 2 + % S 2 0 6 F 2 • C1G 2 S0 3 F C10 2 combines w i t h f l u o r o s u l p h a t e r a d i c a l s to form CIC^SO^F. The l i b e r a t i o n of CL may r e s u l t from the o x i d a t i o n o f C1CL t o C1CL by S O F . , 2 l 6 2 '6 1 which f u r t h e r r e a c t s w i t h S 2 ° 5 F 2 a S i n A s e c o n d p o s s i b i l i t y i n v o l v e s the replacement of an oxygen atom i n C10 2 by SC^F' a s a c c o r d i n g t o : CIO ~ + Sn0V^ • C10S0„F + S0„F~ z z o 2 J O O x i d a t i o n of e i t h e r C10S0 3F or C 1 0 2 " by S 2 0 6 F 2 to C10 2 S0 3 F and C 1 0 3 " r e s p e c t i v e l y would account f o r the S , , 0 3 F 2 found i n the r e s i d u a l p e r o x i d e a f t e r the r e a c t i o n . 39 However, no evidence was found to support the formation of ClOSO^F. The Raman spectrum f a i l e d to reveal any absorption bands i n the frequency + -1 59 region expected for CIO , i s o e l e c t r o n i c with 0^ ( v o - 0 = c m ) • The o v e r a l l reaction using an excess of ^ 20^^ appears to be: NaC10„ + 2S o0,F o(excess) • NaS0„F + ClO^SO^F + S.0_F_ + %0 o / Z o Z j Z 6 Z o Z Z Peroxydisulphuryl d i f l u o r i d e reacted moderately with the analogous nitrogen-containing compounds, KNO^ and NaNO^ at room temperature as according to: KN0_ + S o0.F 9 • KS0„F + N0„S0 7F + %0. 5 Z o Z .5 Z o Z NaN0 o(exc.) + S o 0 £ F o NaSO F + N0S0_F + %0_ Z Z o Z >• J o Z NaN0„ + 2S o0.F„(exc.) — • NaS0„F + NO.SO.F + S„0 cF^ + h0„ z z o z o z o z D z z The reaction between $2®^ 2 and KNO^ i s analogous to the KCIO^-^2^6F2 r e a c t i ° n - However, NaN02 does not apparently react with $2®^ 2 i n a s i m i l a r fashion as i t s chlorine analogue, NaC102- Instead;; .^O^^ displaces an oxygen atom from the n i t r i t e ion to form NOSO^F. In a co n t r o l l e d r eaction, using an excess of NaN02, the Raman spectrum of the reaction product mixture reveals the presence of two fluorosulphates, NaSQ3F and N0S03F (N0 + at 2303 cm" 1); the N0 2 + peak at 1408 cm"1 i s absent. However, an excess of ^ O^F,, i n the reaction r e s u l t s i n the production of N0 2S0 3F and NaS0 3F. As N0S03F i s oxidized to I^SO,^ by the peak i n the Raman spectrum at 2303 cm 1 diminishes, while the absorption peak at 1408 cm 1 due to the N0^ + cation becomes more intense. 40 Due t o the d i f f i c u l t y i n s e p a r a t i n g NOSO^F or r ^ S O ^ F from the a l k a l i metal f l u o r o s u l p h a t e , the above r e a c t i o n s are u n s u i t a b l e p r e p a r a t o r y routes to these f l u o r o s u l p h a t e s . Convenient syntheses f o r NO- and 73 74 NO2- f l u o r o s u l p h a t e s have been p r e v i o u s l y r e p o r t e d . ' 3 . 3 . 2 The P r o p e r t i e s and Reac t ions of C102S0 3F A t room temperature , C102S0 3F e x i s t s as a h i g h l y r e a c t i v e supercooled l i q u i d (m.p. 27°C. ) , which explodes w i t h c o l d water and o r g a n i c m a t e r i a l . I t i s t h e r m a l l y s t a b l e , however, up to temperatures of 1 5 0 ° C , and may be kept i n g l a s s s torage v e s s e l s f o r long p e r i o d s of t i m e . In i o n i c s o l v e n t s such as HSO^F, C102S0 3F i s m i s c i b l e , but i t i s o n l y s l i g h t l y s o l u b l e i n the cova lent l i q u i d s S^O^J^ and ^2^(^2' E l e c t r i c a l c o n d u c t i v i t y v a l u e s f o r the neat l i q u i d are g i v e n i n Table 2: TABLE 2: E l e c t r i c a l C o n d u c t i v i t y of C10 2 S0 F TEMPERATURE ( ° C . ) K (Q 1 c m ~ 1 ) 5.6 3.88 x l o j 10.7 4 .70 x 10 Jl 16.1 5.73 x l o j 25.0 7.51 x 10 32.0 9.00 x 10 The r e l a t i o n of the s p e c i f i c c o n d u c t i v i t y to temperature i s l i n e a r w i t h a p o s i t i v e temperature c o e f f i c i e n t , w h i c h i s t y p i c a l of an i o n i c l i q u i d . The r e l a t i v e l y h i g h neat l i q u i d c o n d u c t i v i t y ( c . f . BrF^ 8.00 x 10~ 3 fi~1cm"1 7 5 versus 7.51 x 10~ 2 fi^cnf1 f o r C10 2 S0 3 F at 25°C. ) i s a t t r i b u t e d t o s e l f - d i s s o c i a t i o n : C10 S0„F = C 1 0 o + + S0_F~. 2 3 2 3 C h l o r y l f l u o r o s u l p h a t e appears to be a s t r o n g o x i d i z i n g agent . I t s r e a c t i o n w i t h p e r f l u o r o - o l e f i n s r e s u l t i n o x i d a t i o n and cleavage at the double bond i n c o n t r a s t w i t h S„0 ,F„ which forms 1:1 a d d i t i o n z 6 z j 38 compounds Whereas ^2^(^2 ^ a ^ * s t 0 r e a c t w i t h potass ium f l u o r i d e , ClO^SO^F undergoes a v i g o r o u s r e a c t i o n w i t h e f forvescence o f ClO^F as a c c o r d i n g to KF + C10 2 S0 3 F •—• KS0 3 F + C10 2 F + Such a r e a c t i o n suggests the p o t e n t i a l use of C10 2 S0 3 F as a p o w e r f u l f l u o r o s u l p h a t i n g agent . 3 . 3 . 3 The E x i s t e n c e of the Chloronium C a t i o n , C 1 0 2 + , i n S o l u t i o n 3 . 3 . 3 . 1 I n t r o d u c t i o n T , . + £ . + . 76-80,82-85 M.+ The e x i s t e n c e of the n i t r o s o n i u m c a t i o n , NO , •j . .,. . 86-90,68-70 + . . . ' , and the n i t r o n i u m c a t i o n ' i n s t r o n S p r o t o n i c s o l v e n t s and i n the s o l i d s t a t e , i s w e l l - k n o w n . These c a t i o n s o r i g i n a t e from the oxides NO and N 0 2 r e s p e c t i v e l y which are e l e c t r o n i c a l l y s i m i l a r to C10 2 i n so f a r as they c o n t a i n a s i n g l e e l e c t r o n i n the h i g h e s t l y i n g occupied molecu lar o r b i t a l (which i s a n t i - b o n d i n g w i t h respec t to the c e n t r a l atom and o x y g e n . ) . A number of i o n i z a t i o n p o t e n t i a l s f o r s imple d i a t o m i c and t r i a t o m i c 48 49 molecules are l i s t e d i n t a b l e 3 ' . Whi le the f i r s t i o n i z a t i o n p o t e n t i a l of C10 2 i s g r e a t e r than t h a t of bo th NO and NO,,, i t i s l e s s 93 than t h a t of 0 „ , which e x i s t s as the c a t i o n i n the s o l i d 0„PtF , Z Z D Thus, on the b a s i s o f i o n i z a t i o n p o t e n t i a l d a t a , the e x i s t e n c e o f C I O * i s q u i t e p o s s i b l e . 42 TABLE 3 : First I on i z a t i onpo t en t i a l s in ev •  a) d i a t o m i c s N O o 2 C O N O + c o + N t 9 . 3 5 1 2 . 2 14. I 1 5 . 7 b) t r i a t o m i c s N 0 2 C I O . N O 2 S O . C O , N O . C IO + N 2 0 ^ S O + c o 2 + 9 . 8 I I. I 1 2 . 9 13. I 1 3 . 8 43 The s t r o n g l y p r o t o n i c s o l v e n t , f l u o r o s u l p h u r i c a c i d , has been 45 94 shown t o be v e r y u s e f u l as a medium f o r s t u d y i n g c a t i o n i c s p e c i e s ' I t undergoes a u t o p r o t o l y s i s as a c c o r d i n g t o : 2HS0 3F = H 2 S 0 3 F + + S 0 3 F ~ Bases i n t h i s s o l v e n t are d e f i n e d as substances which when d i s s o l v e d i n HSO^F i n c r e a s e the c o n c e n t r a t i o n o f the f l u o r o s u l p h a t e i o n SO^F ; whereas, a c i d s are d e f i n e d as substances which i n c r e a s e the c o n c e n t r a t i o n o f H^SO^F*. The s o l u t e KSO^F which behaves as a s t r o n g base i n t h i s s o l v e n t i s o f t e n used as a s tandard i n s t u d y i n g o ther s o l u t e s . The l a t t e r are compared by the c a l c u l a t i o n o f y v a l u e s , d e f i n e d as the number o f moles o f f l u o r o s u l p h a t e anions produced per mole o f s o l u t e . As an a p p r o x i m a t i o n , y v a l u e s are c a l c u l a t e d by d i v i d i n g the s o l u t e m o l a l i t y by the m o l a l i t y o f KSUgF, the r e f e r e n c e s o l u t e , at a g i v e n c o n d u c t i v i t y . 3 . 3 . 3 . 2 C o n d u c t i v i t y Measurements C h l o r y l f l u o r o s u l p h a t e d i s s o l v e d r e a d i l y i n HSO^F to form a r e d c o l o u r e d s o l u t i o n . C o n d u c t i v i t y measurements were o b t a i n e d f o r the d i l u t e s o l u t i o n s , up to 0.045 m o l a l C l O ^ O ^ F . The c o n d u c t i v i t y r e s u l t s , toge ther w i t h those o b t a i n e d f o r ( C I O 2 ) 2S 3 0 ^Q , ^ 2 ^3^10 and the r e f e r e n c e s o l u t e KSO^F, are l i s t e d i n Table 4 . As a means 29 o f f u r t h e r compar ison , the s o l u t e s NOSO^F and J ^ S O ^ F are i n c l u d e d i n the t a b l e . TABLE 4 ( a ) : S p e c i f i c C o n d u c t i v i t i e s o f CIC^SCLF, ( C 1 0 2 ) 2 S 3 0 Q and K ^ O Q i n HSCLF at 25 .00°C . CIO 2 S 0 3 F tcio 2) 2s 3o 10 K 2 S 3 ° 1 0 KSO-F A d d i t i o n s ; M o l a l i t y x 10 2 K X 10 4 2 M o l a l i t y x 10 K X 10 4 M o l a l i t y x io 2 K X 10 4 M o l a l i t y x 2 4 10 K x 10 (Q *cm ^) f n - l - 1 , (ft cm J (fi cm j (fi ^cm 0 000 1.247 0 01032 95.69 0.0000 1.161 0.0000 1.236 0 060 1.778 0 1083 97.56 0.0098 1.456 0.0102 1.407 0 122 2.832 0 3973 102.5 0.0450 2.586 0.0317 2.158 0 161 4.036 0 9236 111.4 0.0921 4.746 0.3382 16.33 0 282 7.122 1 873 126.8 0.1640 8.234 0.4208 19.83 0 360 9.831 2 425 135.4 0.2131 10.62 0.7767 36.. 78 0 498 12.78 3 313 148.7 0.2707 13.48 0.8473 40.11 0 769 19.38 3 767 153.2 0.4721 22.92 1.0781 50.43 0 950 23.46 5 .279 172.8 0.5698 27.87 1.2851 59.91 1 241 29.85 0.7379>- y 35.72 1.5645 72.34 1 509 35.73 0.8249 39.92 1.8598 84.37 1 722 40.24 2 171 49.60 3 579 77.84 4 550 95.31 45 TABLE 4 (b ) : I n t e r p o l a t e d S p e c i f i c C o n d u c t i v i t i e s of S o l u t e s i n HSO F ( 2 S . 0 0 ° C . ) Molality K S 0 3 F (CIQ2) OSQ 2 F (N0 2) O S Q 2 F N O ( O S Q 2 F ) (CIO) s o 2 2 3 JO x IO 2 K x IO 4 Epr' c m i K x I O 4 \pr' cm-'] X K x I O 4 [rr'cm-1] X K x i b 4 [p-1 cm~] X K x I O 4 [or cm'} X O . O O I . .085 1.247 — 1 .116 — 1 . 0 8 4 1 . 161 0 . 2 5 7. O 6. 4 6 0 . 9 1 4 . 8 7 0 . 7 0 6.1 0 . 8 7 1 2 . 4 5 1.78 O. 5 0 13. 61 12 .8 O. 9 4 1 2 . 9 0 . 9 5 12.4 0 . 9 1 2 4 . 3 1,79 O. 7 5 19.7 18. 9 0 . 9 6 19. O O. 9 7 18.8 0. 9 5 3 6 . 8 1.84 1 . O O 2 5 . 8 2 4 . 7 O. 9 5 2 5 . 1 O. 9 7 2 4 . 6 0 . 9 5 4 8 . 4 1.88 1 . 5 0 3 8 . 0 3 5 . 5 0 . 9 3 37 . 1 O. 9 8 3 6 . 8 O. 9 7 2 . 0 0 5 0 . 0 4 5 . 7 0 .91 4 7 . 4 O. 9 5 5 0 . 9 1.02 2 . 5 0 6 2 , 5 57. 1 0.91 5 9 . 5 0 . 9 5 6 0 . 6 O. 9 7 3 . 0 0 7 2 . 7 67. 8 0 . 9 3 70. O O. 9 6 7 2 . 2 0 . 9 9 3. 5 0 8 4 . 9 76.1 O. 9 0 81. 8 0 . 9 7 8 4 . 2 0 . 9 9 4 . 0 0 97. O 8 7 . 0 O. 9 0 9 0 . 0 O. 9 3 9 3 . 3 O. 9 6 4 . 5 0 i i 106. 8 9 4 . 3 O. 8 8 9 8 . 7 0 . 9 3 105. 2 O. 9 9 C h l o r y l f l u o r o s u l p h a t e behaves as a s t r o n g base i n HSO^F as i s e v i d e n t from the y v a l u e s and a c o n t i n u i n g i n c r e a s e i n c o n d u c t i v i t y when KSO^F a d d i t i o n s are made to the s o l u t i o n . The y v a l u e s which are c l o s e to the r e f e r e n c e KSO^F v a l u e of 1.00 i n d i c a t e C10 2 S0 3 F t o be c o m p l e t e l y d i s s o c i a t e d i n HSO^F. The f o l l o w i n g s o l v o l y s i s e q u a t i o n i s sugges ted : C10 2 S0 3 F • C 1 0 2 + + S 0 3 F " The s l i g h t decrease i n c o n d u c t i v i t i e s from the s tandard KSO^F f o r ClO^SO^F i s due t o a d i f f e r e n c e i n the c a t i o n m o b i l i t i e s r a t h e r than an incomplete d i s s o c i a t i o n . The c o n d u c t i v i t y r e s u l t s f o r the s o l u t e s NOSO^F and N O ^ O ^ F l e n d support to t h i s s ta tement , as the + + observed order o f c o n d u c t i v i t i e s at a g i v e n c o n c e n t r a t i o n , K > NO > N 0 2 + > C 1 0 2 + i s i n agreement w i t h the expected t r e n d f o r the c a t i o n s i z The c o n d u c t i v i t y i n c r e a s e f o r ( C 1 0 2 ) 2 S 3 0 ^ Q i s t w i c e as l a r g e as found f o r C 1 0 2 S 0 3 F . The f o l l o w i n g mechanism o f s o l v o l y s i s i s suggested ( C 1 0 2 ) 2 S 3 0 1 0 • 2 C 1 0 2 + + S 3 0 1 0 = S 3 ° 1 0 " + H S 0 3 F " H S 3 ° 1 0 + S 0 3 F H S 3 ° 1 0 " + H S ° 3 F * H 2 S 3 ° 1 0 + S 0 3 F O v e r a l l S o l v o l y s i s : C C 1 0 2 > 2 S 3 ° 1 0 + 2 H S ° 3 F ~ * 2 C 1 ° 2 + + 2 S 0 3 F " + H 2 S 3 ° 1 0 47 I t i s assumed tha t the a c i d H ^ S ^ O ^ behaves as a n o n - e l e c t r o l y t e i n HSO^F. T h i s assumption r e c e i v e s some j u s t i f i c a t i o n from s t u d i e s on 95 the d i s u l p h u r i c a c i d s o l v e n t system , where H ^ S ^ O ^ i s r e p o r t e d to be e s s e n t i a l l y u n d i s s o c i a t e d i n H^S^O^, an a c i d o f comparable s t r e n g t h t o HSO^F. F u r t h e r c o n f i r m a t i o n was o b t a i n e d by s o l v o l y s i s s t u d i e s o f ^ S ^ O i n HSO^F, showing s i m i l a r c o n d u c t i v i t y v a l u e s to those o f ( C I C ^ ) 2 S 3 0 ^ Q at g i v e n c o n c e n t r a t i o n s . The c o n d u c t i v i t y curves f o r ( C I O ^ ^ S ^ O ^ Q and the s o l u t e s d i s c u s s e d above are p l o t t e d i n F i g u r e 6. C o n d u c t i v i t y measurements o f (CIO^) ^^^^Q were a l s o o b t a i n e d i n 100% H^SO^ to examine i t s s o l v o l y s i s b e h a v i o r i n a weaker p r o t o n i c s o l v e n t . The c o n d u c t i v i t y r e s u l t s a long w i t h the r e f e r e n c e s o l u t e , KHSO^, are shown i n Table 5 and p l o t t e d i n F i g u r e 7. (Here, y v a l u e s are d e f i n e d as the number o f moles o f hydrogen s u l p h a t e anions produced per mole o f s o l u t e . ) D i c h l o r y l t r i s u l p h a t e d i s s o l v e s s l o w l y i n 100% ^ S O ^ w i t h o u t apparent chemica l r e a c t i o n . Y e l l o w to r e d s o l u t i o n s are o b t a i n e d i n the c o n c e n t r a t i o n range 0.005 m o l a l to 0.040 m o l a l , where ( C I C ^ - ^ ^ ^ I O behaves as a s t r o n g base. F u r t h e r a d d i t i o n s o f KHSO^ to the s o l u t i o n r e s u l t i n a c o n t i n u e d i n c r e a s e i n c o n d u c t i v i t y . D i c h l o r y l t r i s u l p h a t e i s found to be s l i g h t l y more c o n d u c t i n g than KHSO^. For the p r o d u c t i o n o f 1 mole of HSO^ i n H^SO^ per mole of(C102)2S20^g, the f o l l o w i n g processes l i k e l y o c c u r : 48 49 TABLE 5 ( a ) : S p e c i f i c C o n d u c t i v i t i e s o f ( C 1 0 2 ) 2 S 0 i n H 2 S 0 4 at 25 .00°C . M o l a l i t y x 2 2 10 K x 10 (Sl cm ) 2 M o l a l i t y x 10 K X 10 2  r o - l " I , (Sl cm ) 0.0000 0.0935 0.3192 0.5481 1.025 1.573 2.147 1.045 1.065 1.073 1.085 1.109 1.147 1.192 2.263 2.431 2.511 3.060 3.534 3.750 1.204 1.223 1.234 1.305 1.344 1.360 TABLE 5 (b) : I n t e r p o l a t e d S p e c i f i c C o n d u c t i v i t i e s of ( C 1 0 2 ) 2 S 3 and KHS0 4 i n H" 2S0 4 at 2 5 . 0 0 ° C . KHS0 4 ( c i o 2 ) 2 s 3 °10 M o l a l i t y x 2 2 10 K _ X 1 0 ^ (Sl cm ) K x 10 2 ( S l " l c m ) Y 0.000 0.500 1.000 1.500 2.000 2.500 3.000 3.500 4.000 1.043 1.053 1.068 1.097 1.139 1.180 1.240 1.289 1.356 1.043 1.081 1.109 1.143 1.183 1.227 1.279 1.339 1.408 1.03 1.04 1.04 1.04 1.03 1.03 1.04 1.04 50 FIGURE 7: I . O O l 1 1 — i - l r I 2 3 4 5. 1Q 2 .Mola l i ty ( c i o 2 ) 2 s 3 o 1 0 2 C 1 0 2 : + S 3 ° 1 0 S 3 ° 1 0 _ + H 2 S 0 4 " H S 3 ° 1 0 + H S 0 4 The f o l l o w i n g e q u i l i b r i u m would account f o r the observed y v a l u e s g r e a t e r than 1.00: -y H S 3 ° 1 0 + H 2 S 0 4 • t- H 2 S 3 ° 1 0 + H S 0 4 As H^S^O.^ i s a s t r o n g e r a c i d than H^SO^, the e q u i l i b f i i u m e x i s t s f a r to the l e f t . 3 . 3 . 3 . 3 1 H NMR Spec t ra The p r o t o n magnetic resonance spectrum o f a s o l u t i o n o f C l O ^ O ^ F i n HSO^F shows a s i n g l e peak. The p o s i t i o n o f the s i n g l e t peak w i t h r e s p e c t to the s o l v e n t peak as e x t e r n a l s tandard i s s h i f t e d d o w n f i e l d w i t h i n c r e a s i n g s o l u t e c o n c e n t r a t i o n . T h i s i s i n agreement 96 w i t h the expected t r e n d f o r the f o r m a t i o n of f l u o r o s u l p h a t e a n i o n s . Till r e s u l t s are. t a b u l a t e d i n Table 6 and p l o t t e d i n F i g u r e 8, a long w i t h the r e f e r e n c e KSO^F v a l u e s . The d e v i a t i o n o f the C l O ^ O ^ F curve from l i n e a r i t y at mole f r a c t i o n s g r e a t e r than 0.1 r e s u l t s from the imcomplete d i s s o c i a t i o n o f C l O ^ O ^ F at h i g h c o n c e n t r a t i o n s . FIGURE ; s 52 H C h e m i c a l Sh i f t s For So lut ions of ( C I 0 2 ) O S 0 2 F o.o in H S O 3 F ( C!Op)OSO PF K S 0 3 F ( G i l l e s p i e ) 0.5 I.O 1.5 2 . 0 Mo le F rac t ion x 10 2.5 1 TABLE 6 - 1 H NMR Chemical S h i f t s o f S o l u t i o n s o f C10 2 S0 3 F i n HS0 3F * Mole F r a c t i o n C10 2 S0 3 F 6 (ppm) 0.191 1.367 0.108 0.900 0.035 0.350 0.017 0.167 * r e l a t i v e to HS0 3F e x t e r n a l s tandard 3 . 3 . 3 . 4 U V - V i s i b l e Spec t ra The observed U V - v i s i b l e s p e c t r a of s o l u t i o n s o f C10 2 S0 3 F i n HS0.F show three a b s o r p t i o n peaks at X = 2250 A (e > 2500), o max max A = 2700 A (e ~ 1950), and a shoulder o f lower i n t e n s i t y at about max max ' 3 3300 A . The r e s u l t s are shown i n Table 7, and the U V - v i s i b l e spectrum, f o r the c o n c e n t r a t i o n 0.0159 M and a path l e n g t h of 0.05 c m . , i s reproduced i n F i g u r e 9. T-he e l e c t r o n i c spectrum of C10 2 S0 3 F i n HS0 3F i n HS0 3F can be i n t e r p r e t e d as e s s e n t i a l l y tha t o f the chloronium c a t i o n , C 1 0 2 + . Assignments are made on the b a s i s o f the a b s o r p t i o n spectrum of the 97 i s o e l e c t r o n i c spec ies S 0 2 by Walsh. Walsh 's d iagram, i l l u s t r a t i n g the dependence o f the b i n d i n g energy o f the molecu lar o r b i t a l s o f a t r i a t o m i c molecule on the apex a n g l e , i s reproduced i n F i g u r e 10. FIGURE 9 UV-visible spectrum of C I 0 2 S 0 3 F in HSO3F 4 4 0 0 3 8 0 0 3 2 0 0 Wavelength in TABLE 7 - E l e c t r o n i c Spec t ra of C10 2 S0 3 F i n HSC^F (a) Observed A b s o r p t i o n s and Assignments CIO, SO 55 X (A) max t X (A) max Assignment 2250 >2500 2700 ~1'950 3300 sh ~ 900 2000 2940 3740 "400 B 2 " L B l -(b) E x t i n c t i o n C o e f f i c i e n t s f o r the A b s o r p t i o n at X = 2700 A max 10 M o l a r i t y Path Length (cm) E x t i n c t i o n C o e f f i c i e n t (e) 1.59 1.80 4.31 6.33 0.05 0.05 0.005 0.005 1960 1890 1950 1990 Average = 1948 FIGURE 10 5 6 9 0 I 2 0 150 1 8 0 ° A n g l e B A B 57 The t r i a t o m i c spec ies ClO^ and ClO^ are r e p o r t e d to have apex angles o f 1 1 0 . 5 ° and 1 1 5 . 3 ° r e s p e c t i v e l y ^ . The removal o f an e l e c t r o n I I from the doubly occupied b^ molecu lar o r b i t a l of CIO2 r e s u l t s t h e r e f o r e i n an i n c r e a s e of the O-Cl -O apex angle by about 5 ° . 1 1 (b^ i s a n t i - b o n d i n g f o r C l - 0 , but weakly bonding f o r 0 -0 ) . I t i s 1 1 then expected tha t the removal o f the s i n g l e e l e c t r o n from the b^ M.O. i n ClO^ might r a i s e the apex angle to about 120° i n C 1 0 2 + , o 99 which i s c l o s e to tha t o f the i s o e l e c t r o n i c molecule S02> 119.5 In the ground s t a t e o f C 1 0 2 + , the o n l y l o w - l y i n g vacant o r b i t a l it i s b^ , and low energy e l e c t r o n i c t r a n s i t i o n s w i l l i n v o l v e the e x c i t a t i o n o f an e l e c t r o n to t h i s o r b i t a l . The two a b s o r p t i o n bands at A = 3300 A and A = 2700 A are ass igned to the a l l o w e d max max t r a n s i t i o n s , < * A ^ and ^ l " ^ n e t n i r d t r a n s i t i o n ^ 2 -< * A ^ i n the group of low-energy t r a n s i t i o n s i s f o r b i d d e n . The a l lowed t r a n s i t i o n s are shown i n F i g u r e 10 and are l a b e l e d (1) and (2) . The h i g h l y i n t e n s e a b s o r p t i o n band at X -2250 A i n v o l v e s 6 J r max h i g h e r energy t r a n s i t i o n s to and a l s o to b^ from o c c u p i ed 1 lower l y i n g o r b i t a l s than the IT o r b i t a l s and a , A . • g I s . Thus the e l e c t r o n i c s p e c t r a of s o l u t i o n s of C102S0 3F i n HSO^F can be i n t e r p r e t e d as a r i s i n g from a t r i a t o m i c spec ies i s o e l e c t r o n i c to S 0 2 -I t i s i n t e r e s t i n g to note tha t SO2 i s c o l o r l e s s w h i l e C102 + i s a red c o l o u r e d s p e c i e s . As can be seen i n F i g u r e 9, the h i g h i n t e n s e bands of C102 + o r i g i n a t e i n the v i s i b l e r e g i o n at about 4400 A. The corresponding a b s o r p t i o n bands f o r SO2 have been observed 97 at A = 3740 A and 2940 A , but they are of f a r lower i n t e n s i t y max J J fe f o r the s t r o n g e r band i s -400) and do not reach i n t o the v i s i b l e r e g i o n , max 58 5 . 5 . 3 . 5 M i g r a t i o n Experiment E l e c t r o l y s i s o f ClO^ s o l u t i o n s i n a three compartment diaphragm c e l l r e s u l t e d i n the m i g r a t i o n of the r e d - c o l o u r e d C 1 0 2 + spec ies to the cathode, and the l i b e r a t i o n of CIO,,. The f o l l o w i n g r e a c t i o n occurs at the cathode: C 1 0 2 + (red) + e y C10 2 (ye l low) 3 . 3 . 3 . 6 Summary The f o l l o w i n g experiments g i v e evidence f o r the e x i s t e n c e of CIO,, i n s o l u t i o n : 1. C o n d u c t i v i t y measurements 2. NMR concentra t ion-dependent chemical s h i f t s 3 . U V - v i s i b l e s p e c t r a 4. M i g r a t i o n experiment + The f i r s t two experiments p r o v i d e i n d i r e c t evidence f o r C10 2 c a t i o n s , as they show the f o r m a t i o n of the corresponding f l u o r o s u l p h a t e anions when C10,,S0 3F i s d i s s o l v e d i n HSO^F. The p o s s i b i l i t y of a d i s p r o p o r t i o n a t i o n r e a c t i o n and the f o r m a t i o n of c h l o r i n e d i o x i d e were excluded by two f u r t h e r exper iments : (a) ClO^SO^F c o u l d be recovered from . s o l u t i o n by e v a p o r a t i o n of HSO^F and (b) A s o l u t i o n o f C10 2 S0 3 F i n HSC^F d i d not g i v e an ESR s i g n a l . The e l e c t r o n i c s p e c t r a of s o l u t i o n s of ClO^SO^F i n HSO^F are c o n s i s t e n t w i t h the f o r m a t i o n o f C l O ^ * c a t i o n s , w h i l e the m i g r a t i o n experiment shows tha t the r e d u c t i o n of the spec ies i n s o l u t i o n r e s u l t s i n c h l o r i n e d i o x i d e . S a t i s f a c t o r y Raman s p e c t r a c o u l d not be obta ined f o r s o l u t i o n s of the r e d - c o l o u r e d spec ies i n HSO^F. U n f o r t u n a t e l y , attempts to i n v e s t i g a t e the v i b r a t i o n a l s p e c t r a o f the r e d . c h l o r y l compounds i n the s o l i d s t a t e were u n s u c c e s s f u l . High r e s o l u t i o n Raman s p e c t r a c o u l d not be obta ined due to the i n t e n s e red c o l o u r o f these compounds, w h i l e the h i g h r e a c t i v i t y o f the red c h l o r y l compounds prevented the procurement o f t h e i r i n f r a r e d s p e c t r a ! 60 C H A P T E R F O U R CHLORYL HEXAFLUOROMETALLATES: CHLORYL COMPOUNDS (WHITE) PART I I 4.1 INTRODUCTION A l i m i t e d number of c h l o r y l compounds have been known f o r some 11 18 time . They f a l l i n t o two d i s t i n c t c l a s s e s . C h l o r y l f l u o r i d e , CIO2F , and i t s r e a c t i o n products w i t h s t r o n g Lewis a c i d s such as BF^, AsF^. and S b F , . 3 ' ' ' " ^ 5 ' ' ' ^ are c o l o u r l e s s moderate ly r e a c t i v e compounds. On the o ther hand, c h l o r y l f l u o r o s u l p h a t e , C1Q2S03F and d i c h l o r y l t r i s u l p h a t e , ( C ^ ^ ^ S ^ O . ^ are deep r e d - c o l o u r e d s o l i d s at room temper-ature and are h i g h l y r e a c t i v e compounds. I n t e r e s t i n g l y , a l l compounds + 3,100,102 have been p o s t u l a t e d t o c o n t a i n the ch loronium c a t i o n , CIO2 No s t r u c t u r a l i n v e s t i g a t i o n s have been p r e v i o u s l y made, and no e x p l a n a t i o n has been put f o r t h to account f o r the d i f f e r e n c e s i n r e a c t i v i t y and c o l o u r o f the two c l a s s e s o f CIO2- c o n t a i n i n g compounds. I t was shown i n the l a s t chapter tha t the ch loronium c a t i o n , C 1 0 2 + , e x i s t s as a r e d - c o l o u r e d spec ies i n a s o l u t i o n of f l u o r o -s u l p h u r i c a c i d when C102S0 3F and (CIO2)2S 3 0 .^ are used as s o l u t e s . The i n t e n s e red c o l o u r and h i g h r e a c t i v i t y i n t h i s l a t t e r c l a s s of compounds i s then a t t r i b u t e d to the presence of d i s c r e t e C102 + c a t i o n s . 61 I t i s then the purpose p f t h i s chapter to r e s o l v e the apparent c o n t r a d i c t i o n r e g a r d i n g the ch loronium c a t i o n i n the s o l i d s t a t e by extending the s o l u t i o n s t u d i e s performed i n the l a s t chapter to the c o l o u r l e s s compounds, a n d C l C ^ A s F a n d by s t u d y i n g the v i b r a t i o n a l s p e c t r a o f CICLAsF, and C l O . S b F - . 2 6 2 6 4,2 EXPERIMENTAL C h l o r y l f l u o r i d e was prepared by the r e a c t i o n of KCIO^ w i t h 3 BrF^ i n monel metal r e a c t o r s (F igure 2) as a c c o r d i n g to Woolf . The p u r i t y of CIC^F was checked on the b a s i s of the IR spectrum o f the p r o d u c t . A r s e n i c p e n t a f l u o r i d e and antimony p e n t a f l u o r i d e were p u r i f i e d by t r a p to t r a p d i s t i l l a t i o n . 3 C h l o r y l h e x a f l u o r o a r s e n a t e and -ant imonate were prepared by r e a c t i n g a v e r y s l i g h t excess o f c h l o r y l f l u o r i d e w i t h a known amount o f p e n t a f l u o r i d e i n a monel metal r e a c t o r . The r e a c t i o n was f o l l o w e d by weight changes. The ClO^AsF^ was p u r i f i e d by h i g h vacuum s u b l i m a t i o n . S o l u t i o n s o f ClO^F i n f l u o r o s u l p h u r i c a c i d were prepared by d i s t i l l i n g p u r i f i e d c h l o r y l f l u o r i d e i n a metal vacuum l i n e from a s torage v e s s e l i n t o a weighing b u r e t t e kept at -80°C. and c o n t a i n i n g a known q u a n t i t y of doubly d i s t i l l e d HSO^F. T h i s s tock s o l u t i o n was used f o r a d d i t i o n to the a c i d i n the c o n d u c t i v i t y c e l l . 62 4 .3 RESULTS AND DISCUSSION 4 . 3 . 1 The V i b r a t i o n a l Spec t ra of C10„AsF. and C10„SbE^ z 6 2 6 The v i b r a t i o n a l Raman and 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 and i n t e n s i t i e s f o r ClC^AsF^. and ClO^SbF^ a long w i t h the f r e q u e n c i e s and i n t e n s i t i e s f o r KAsF, and KSbF.. are l i s t e d i n Table 8. The i n f r a r e d 6 6 and Raman s p e c t r a o f ClC^AsF^. are reproduced i n F i g u r e s 11 and 12. The v i b r a t i o n a l s p e c t r a o f C K ^ A s F ^ have a l s o been r e p o r t e d by C h r i s t e 103 et a l almost s i m u l t a n e o u s l y to the p u b l i c a t i o n o f the r e s e a r c h presented i n t h i s c h a p t e r . As w i l l be shown, our i n t e r p r e t a t i o n of i the s p e c t r a l r e s u l t s d i f f e r s c o n s i d e r a b l y from these a u t h o r s , c o n c l u s i o n s . P o s s i b l e molecu lar s t r u c t u r e s f o r C10oMF,. where M = As or Sb a r e : z 6 (a) an i o n i c s o l i d C10_ +MF ~ (b) a m o l e c u l a r 1:1 adduct C 1 0 o F - M F r w i t h z 6 z 5 b r i d g i n g over f l u o r i n e and (c) the same w i t h b r i d g i n g over oxygen. For model ( a ) , the chloronium c a t i o n would be i s o e l e c t r o n i c to s u l p h u r d i o x i d e , and the symmetry would be C^^. w i t h three v i b r a t i o n a l modes, both Raman and IR a c t i v e . T h i s i s conf irmed by the f i n d i n g s shown i n Table 9. The v i b r a t i o n i s s i m i l a r to that of S02(s)" ' '^ which i s s p l i t i n t o two i n f r a r e d and Raman a c t i v e components by the c r y s t a l l i n e f i e l d . I t i s i n t e r e s t i n g to n o t e , however, tha t the average s t r e t c h i n g f r e q u e n c i e s f o r the CIO2 group (Table 10) are lower than that f o r SO2: = 1233 cm * v . s . ^>Q^Q + = 1166 cm * (IR) or 1168 cm * (Raman) — 2 -1 2 -1 i n C 1 0 o A s F , and v „ i n + = 1174 cm (IR) and 1178 cm (Raman) f o r C10_SbF, . z o L I U 2 z 6 TABLE 8: The V i b r a t i o n a l - S p e c t r a of C l O ^ A s F , and CICLSbF O B S E R V E D WAVENUMBERS CcnT1) ClOJVsF^ ClO^SbF, KAsF, KSbF I . R . RAMAN I . R . RAMAN I . R . RAMAN I ; R . RAMAJ1 1293 s 1296 w 1304 s 1313 w 698 s 692 s 655 s 661 s 1280 s 1281 w 1291 s 1295 w 382 br 580 ms 270 s 575 s 1080 w 1045 s 1050 ms 1053 s 375 ms 294 m 1045 s 725 w 810 vw 278 m ; 817 w 684 s 720 s , b r 706 s 725 s , b r • 572 s 680 s , b r 680 s 685 s , b r 518 m 670 s 563 s 370 s 640 s 649 s 515 s 585 ms 592 m •382 s 588 ms 372 s , s h 510 ms 518 w 490 ms 305 m 308 s 288 w 288 m,sh 270 s ,b r 269 w TABLE 9: Assignment of the C10 2 V i b r a t i o n s cio2 I . R . 1045 515 1293,1280 i n CIO A s F , z o RAMAN 1045 518 1296,1281 cio2 I . R . 1050 510 1304,1291 i n C10 o SbF , z o RAMAN 1053 518 1314,1293 S 0 2 ( s ) I . R . 1147 521 1330,1308 Assignment C10, v 3 ( B l } COMPOUND METHOD TABLE 10: C10 2 - S t r e t c h i n g Frequencies (cm -1) C10 2ASYM C10 2SYM C10 2 AVERAGE REFERENCE N a + C 1 0 2 (s) Raman 832 804 818 T h i s work , (aq. s o l n . ) Raman 840 790 815 105 cio2 (g) IR 1111 943 1027 106 FC10 2 (1) Raman 1253 1097 1175 107 C 1 0 2 A s F 6 (s) IR 1293,1280 1045 1166 T h i s work ClOJVsF,, (s) Raman 1296,1281 1045 1168 T h i s work C 1 0 2 S b F 6 (s) IR 1304,1291 1050 1174 T h i s work C 1 0 2 S b F 6 (s) Raman 1314,1293 1053 1178 T h i s work K + C 1 0 3 (s) IR 960 910 935 108 (so2 IR 1330,1308 1147 1233 104} 65 67 On c o n s i d e r i n g the i n c r e a s e i n n u c l e a r charge on c h l o r i n e , one would expect the VQ_Q + v a l u e s to be h i g h e r . However, the i n f r a r e d a b s o r p t i o n frequency o f the NO c a t i o n i n a number o f compounds has been found to v a r y from 2165 cm ^ to 2391 cm * ^ . T h i s v a r i a t i o n has been a t t r i b u t e d to a n i o n - c a t i o n i n t e r a c t i o n which r e s u l t s i n the l o w e r i n g o f the frequency o f the N-0 v i b r a t i o n . For a c o r r e s p o n d i n g MF^ a n i o n w i t h 0^ symmetry, two i n f r a r e d a c t i v e v i b r a t i o n s , (F' ) and ( F i u ) a r e expected together w i t h three Raman a c t i v e v i b r a t i o n s , v , (A, ) , v~ (E ) and v r (F„ 1. 1 l g ' 2 g ' 5 2gJ The observed i n f r a r e d spectrum of C102AsF^ i s more complex than expected. In the r e g i o n o f v ^ , a s t r o n g a b s o r p t i o n at 685 cm ^ occurs w i t h a shoulder at 725 cm ^; t h i s i s i n c o n t r a s t to the spectrum of KAsF^ where a s i n g l e peak i s observed f o r at 698 cm ^. ( A s i m i l a r o b s e r v a t i o n has been made by C l a r k and O ' B r i e n f o r the i n f r a r e d spectrum 109 of ( C H ^ ^ S n A s F ^ , where the AsF^ group i s s a i d to act as a b r i d g i n g group and the symmetry appears to be lowered t o In the r e g i o n o f v^, a doublet i s observed at 382 and 372 cm ^. In a d d i t i o n , a s t r o n g a b s o r p t i o n peak at 563 cm ^ i s observed , but i s not found i n the IR spectrum o f C102SbF^. I t must t h e r e f o r e be due to t h e . A s F ^ group. The Raman spectrum of C102AsF^ a l s o shows more a b s o r p t i o n peaks than expected . The p o s i t i o n s of ," and v,. at 684, 572 and 370 cm ^ r e s p e c t i v e l y are at lower f r e q u e n c i e s than they are observed i n K A s F , . 68 From the p o s i t i o n of the expected mode, v ^ , a t . 572 cm i t i s concluded tha t i t i s i d e n t i c a l w i t h the observed 563 cm * v i b r a t i o n i n the i n f r a r e d spectrum. The 725 cm * v i b r a t i o n i s a l s o weakly Raman a c t i v e , and the p o s s i b i l i t y tha t t h i s v i b r a t i o n i s a combinat ion mode seems r a t h e r u n l i k e l y . From the f i n d i n g s o f the v i b r a t i o n a l s p e c t r a , i t seems t h a t the symmetry of the AsF^ group i s i l o w e r e d c o n s i d e r a b l y from the expected 0^ symmetry, r e s u l t i n g i n the r e l a x a t i o n o f the mutual e x c l u s i o n r u l e f o r IR and Raman a c t i v e v i b r a t i o n s and a genera l s h i f t o f a l l f r e q u e n c i e s i n comparison w i t h o ther AsF^. compounds. The t e n t a t i v e assignment o f the observed f r e q u e n c i e s i s shown i n Table 11. The reason f o r the observed symmetry l o w e r i n g o f the anion can be seen i n a p p r e c i a b l e a n i o n - c a t i o n i n t e r a c t i o n v i a f l u o r i n e b r i d g e s , a l r e a d y r e f l e c t e d i n the s h i f t s o f the C i 0 2 s t r e t c h i n g v i b r a t i o n s (Table 10) . I t i s important to note tha t a p o s s i b l e a n i o n - c a t i o n p o l a r i s a t i o n should not r e s u l t i n the observed t r e n d f o r v ^ , ^ and would be expected to be l a r g e r f o r s m a l l and p o l a r i s i n g c a t i o n s such as N 0 + . T h i s e x p e c t a t i o n i s not conf i rmed by e x p e r i m e n t ^ ? The v i b r a t i o n a l s p e c t r a o f the corresponding hexaf luoroant imonate compound are even more complex. No c e r t a i n assignments f o r the SbF, an ion can be made; crude assignments are g i v e n i n Table 12. The i n f r a r e d spectrum o f ClO^SbF^ r e v e a l s a broad a b s o r p t i o n peak i n the r e g i o n o f w i t h components at 640, 670,680,720 cm * . The peaks at 640, 670 and 720 cm * are ass igned t e n t a t i v e l y t o the components of v ^ , w h i l e the a b s o r p t i o n at 680 cm * i s b e l i e v e d to be due to the i n f r a r e d f o r b i d d e n v ^ . 69 TABLE 11: Assignment o f the A s F , V i b r a t i o n s 6 A s F 6 " i n C 1 0 2 A s F 6 A s F 6 i n K A s F 6 Assignment A s F 6 ~ (0 h ) I . R . RAMAN I . R . RAMAN (685)* 684 - 692 v , (A ) 1 l g ' (563) 572 - 580 v 2 (E ) 725 (725) 698 - v 7 (F, ) 3 l u 382 - 382 - v , (F. ) 4 v l u ' (372) 370 - 375 v (F ) J zg * Frequencies i n parenthese are f o r b i d d e n f o r AsF^ w i t h 0^ symmetry TABLE 12: Assignment o f the SbF ~ V i b r a t i o n s 6 S b F 6 " i n C 1 0 2 S b F 6 S b F 6 " i n KSbF^ Assignment S b F 6 " (0 h ) I . R . RAMAN I . R . RAMAN 680 680 - 661 v , (A ) 1 l g ' 586 592 -j - 575 v 0 ( E J 51 670 I 649 640 ] - ^ v 2 ^ ] 720 n 706 n 655 - V (F ) 1 1 3 l u 270 269 270 - v , (F, ) 4 v l u ' 305 n 308 - i - 294 -j v 5 ( F 2 ) 288 -» 288 J 278 J V 6 70 A broad a b s o r p t i o n i s a l s o observed i n the r e g i o n o f v^, which i s ass igned at 270 cm * ; peaks at about 305 cm ^ and 288 cm ^ are ass igned to v r J but l a c k o f r e s o l u t i o n and p r e c i s i o n i n t h i s range does not d i f f e r e n t i a t e these peaks from components o f v^. In a d d i t i o n , i s observed in- : the i n f r a r e d spectrum as a medium s t r o n g band at 586 cm The Raman spectrum of C102SbFg shows a s i m i l a r c o m p l e x i t y . Strong Raman a c t i v e bands are found at 706, 680 and 649 cm * i n the r e g i o n o f v, , w h i l e v„ i s observed as a doublet at 592 and 588 cm ^. & v 1 2 Vj. i s observed at 308 cm * w i t h a shoulder at 288 cm * . The l o s s o f o c t a h e d r a l symmetry f o r the SbF^ an ion i n C102SbF^ i s q u i t e apparent . The s p l i t t i n g o f the degenerate v i b r a t i o n a l modes, the r e l a x a t i o n o f the mutual e x c l u s i o n r u l e , and the a b s o r p t i o n peaks ass igned t o the SbF^ group appear ing at r e l a t i v e l y h i g h f requenc ies are a l l f e a t u r e s o f the v i b r a t i o n a l s p e c t r a which can a r i s e from a n i o n - c a t i o n i n t e r a c t i o n . Such an i n t e r a c t i o n , which i s more pronounced f o r C102SbF^ than C102AsF^, p r o b a b l y occurs v i a f l u o r i n e b r i d g e s . The average CIO2 - s t r e t c h i n g f r e q u e n c i e s f o r a number o f ei02~ c o n t a i n i n g compounds, a long w i t h the v a l u e s f o r SO2 are shown i n Table 10. I t i s noteworthy tha t f o r the h e x a f l u o r o a n i o n complexes, the average CIO2 s t r e t c h i n g frequency i n each case i s about the same as tha t f o r c h l o r y l f l u o r i d e where v + = 1175 cm ^. 71 Th e bonding i n CIC^F i n v o l v e s a shor t and s t r o n g c h l o r i n e -oxygen bond and a weak and long c h l o r i n e - f l u o r i n e bond as i s ev ident 107 from the r e p o r t e d f o r c e constants . T h i s i s r e m i n i s c e n t o f the s i t u a t i o n i n FNO 1 *' ' ' and F I ^ * " ' ' 2 as w e l l as f o r ®_^2^^ anc^ ®2^^ where the observed element f l u o r i n e bonds are found t o be longer than the normal s i n g l e bonds. Consequent ly , c h l o r y l f l u o r i d e i s a h i g h l y p o l a r molecu le . The C l - F bond has been i n t e r p r e t e d as the i n t e r a c t i o n between a s i n g l y occupied 2p o r b i t a l o f f l u o r i n e to an a n t i - b o n d i n g T T * M.O. o f c h l o r i n e d i o x i d e , r e s u l t i n g i n a h i g h l y d e l o c a l i z e d m u l t i - c e n t r e b o n d i n g . 114 (This type o f b o n d i n g , l a b e l l e d by S p r a t l e y and Pimente l as 113 {ir*-p} a bonding,was used by Lipscomb i n the d e s c r i p t i o n o f 0_^2' where the 0-F bonds r e s u l t from the i n t e r a c t i o n o f a h i g h l y i n g s i n g l y occupied a n t i b o n d i n g T T * o r b i t a l o f 0^ and a s i n g l y occupied 2p o r b i t a l on f l u o r i n e . ) I t seems p o s s i b l e tha t t h i s { 7 T * - p } a i n t e r a c t i o n i s r e t a i n e d when CIO2F r e a c t s w i t h AsF^ and SbF,. , caus ing no a l t e r a t i o n i n the C l - 0 bond o r d e r as evidenced by the v i b r a t i o n a l s p e c t r a . I t was shown i n the l a s t chapter t h a t the e l e c t r o n i c t r a n s i t i o n s r e s p o n s i b l e f o r the r e d c o l o u r o f the C102 + c a t i o n i n v o l v e the low-ii l y i n g b^ a n t i - b o n d i n g m o l e c u l a r o r b i t a l . I f , however, t h i s o r b i t a l became p a r t l y occupied as a r e s u l t o f a {Tr*-p} a i n t e r a c t i o n i n v o l v i n g 11 the b^ M.O. and a 2p o r b i t a l o f one o f the f l o u r i n e atoms o f the a n i o n , the e l e c t r o n i c t r a n s i t i o n s would not be able to o c c u r , and the compound would very l i k e l y appear c o l o u r l e s s . 72 I t i s f e a s i b l e tha t t h i s i s the case w i t h C10 2 F and i t s r e a c t i o n products w i t h Lewis a c i d s . In the case o f C10_AsF^ and C10„SbF. , I o I o t h i s i n t e r a c t i o n i s not n e c e s s a r i l y r e s t r i c t e d to one f l u o r i n e , and two f l u o r i n e atoms may be i n v o l v e d . The {ir*-p} a i n t e r a c t i o n i n whi te c h l o r y l compounds p r o v i d e s a good model to e x p l a i n t h e i r l a c k o f c o l o u r and t o r a t i o n a l i z e the average CIO,, s t r e t c h i n g f r e q u e n c i e s o f C10 2 AsF^ and CIO SbF^',* but o ther e l e c t r o n i c i n t e r a c t i o n s probably e x i s t between the anion and the c a t i o n . In summary, the v i b r a t i o n a l s p e c t r a show the whi te c h l o r y l compounds ClO^AsFg and ClO^SbF^ to be predominant ly i o n i c , but w i t h s t r o n g i n t e r a c t i o n between the an ion and the c a t i o n v i a f l u o r i n e b r i d g i n g . T h i s a n i o n - c a t i o n i n t e r a c t i o n lowers the charge and r e a c t i v i t y o f the C10 2 group and accounts f o r the p o l y f l u o r o a n i o n complexes and C10 2 F o c c u r r i n g as c o l o u r l e s s compounds. 103 In c o n t r a s t to these c o n c l u s i o n s , C h r i s t e et a l have i n t e r p r e t e d the s t r u c t u r e o f C l O ^ s F ^ . , on the b a s i s o f the same v i b r a t i o n a l s p e c t r a , as consist ing s i m p l y o f d i s c r e t e ions and have c a l c u l a t e d f o r c e constants f o r C 1 0 2 + . In our o p i n i o n there seems t o be s t r o n g evidence f o r f l u o r i n e - b r i d g i n g i n C l O ^ s F ^ and r e l a t e d compounds, and . e l a b o r a t e f o r c e constant c a l c u l a t i o n s can not be j u s t i f i e d . As shown i n chapter 3 , the C 1 0 2 + c a t i o n e x i s t s as a r e d - c o l o u r e d spec ies i n HSO^F. I t now became i n t e r e s t i n g t o examine the behavior o f the whi te c h l o r y l compounds i n HSO^F. 4 . 3 . 2 S o l u t i o n S tudies The s o l u t e s KAsF, and CICLAsF , are s o l u b l e and behave as bases 6 2 6 i n HSO^F as i n d i c a t e d by the c o n d u c t i m e t r i c measurements. S p e c i f i c c o n d u c t i v i t i e s at v a r i o u s c o n c e n t r a t i o n s are l i s t e d i n Table 13 a long w i t h the r e f e r e n c e KSO^F v a l u e s . C h l o r y l h e x a f l u o r o a r s e n a t e d i s s o l v e s i n HSO^F to form a r e d - c o l o u r e d s o l u t i o n , the c o l o u r b e i n g c h a r a c t e r i s t i c f o r the C 1 0 2 + c a t i o n , w h i l e the s o l u t e KAsF^ g ives r i s e to a c o l o u r l e s s s o l u t i o n . However, whereas KAsF^ i s o n l y moderately s o l u b l e , the s o l u b i l i t y l i m i t b e i n g 5 .0 x 10~ 2 mola l at 2 5 . 0 ° C , the C10 2 ~ compound i s s o l u b l e to a f a r g r e a t e r degree , up to 1 - 2 m o l a l . The s p e c i f i c c o n d u c t i v i t y v . s . m o l a l i t y p l o t s are shown i n F i g u r e 13. The s p e c i f i c c o n d u c t i v i t i e s o f the ClO^AsF^ s o l u t i o n s are s l i g h t l y h i g h e r than the ones f o r KAsF^ , whereas the s i t u a t i o n was reversed when C10 2 S0 3 F and KSO^F were compared as s o l u t e s . These d i f f e r e n c e s i n s o l u b i l i t y and c o n d u c t i v i t y are unexpected. The r o l e o f the AsF^ an ion i n HSO^F was not i n v e s t i g a t e d as the c o n c e n t r a t i o n ranges were 19 too low f o r meaningful Raman and F NMR s t u d i e s . P o s s i b l y , as i n d i c a t e d by the y v a l u e s , the AsF^ an ion undergoes d i s p r o p o r t i o n a t i o n or chemical exchange i n HSO^F: As t h i s problem was not r e s o l v e d and t o s i m p l i f y the s o l u t i o n s t u d i e s , g r e a t e r a t t e n t i o n was focussed on the s o l u t i o n b e h a v i o r o f C10„F i n HS0,F . TABLE 13: (a) S p e c i f i c C o n d u c t i v i t i e s i n HS0 3 F at 25 .00°C. ClOJVsF , KAsF. C10 o F Z o o Z M o l a l i t y x It) 2 K x 10 4 M o l a l i t y x 10 2 K X 10 4 M o l a l i t y x 10 2 K X 10 4 (ft 1 cm (ft '''cm "*") (ft "'"cm ^) 0. 0000 1. ,236 0. .218 3. ,182 0. ,523 6. ,712 1. 248 17. ,89 1. 972 26. 44 2. 785 34. ,17 3. .964 42. ,93 5. ,025 50. ,04 6. ,309 58. ,38 0. .000 1. .127 0, .202 5, .504 0. ,372 8. .558 0. .554 10. .81 0. ,879 14. .41 1. ,306 18. .93 1. .804 23, .21 2, .147 26, .05 2. .863 31, .74 3. .403 36, .29 4. ,119 41. .78 4. .563 45, .78 0. .0000 1. ,128 0. .1700 3. .665 0. .4690 11. ,94 0. .5954 15. .40 0. ,7820 20. ,20 0. ,8587 22. ,02 1. .1205 30. .82 1. .482 43. .47 2. ,094 63. ,04 2. ,611 78. ,87 3. ,035 91. ,71 3. .759 112. ,5 4. .892 143. .3 6, .134 175. ,8 TABLE 13: (b) I n t e r p o l a t e d S p e c i f i c C o n d u c t i v i t i e s KS0,F KAsF C l O ^ A s F , C10 o F 3 6 2 6 2 MOLALITY K x 10 4 K x 10 4 K x 10 4 K X 1 0 4 x I O 2 ( ft"1™"1) ( f i _ 1 c m _ 1 ) ( ^ " 1 cm" 1 ) ( f i " 1 cm~ 1 ) 0.00 1.085 1.127 1.236 1.329 0.25 7.0 6.8 4 .0 7.0 0.50 13.6 9.8 6.5 13.2 0.75 19.7 12.3 13.2 19.5 1.00 25.8 14.5 16.2 26.1 1.50 38.0 21.7 22.5 44.1 2.00 50.0 24.3 27.3 61.0 2.50 62.5 27.7 31.8 75.8 3.00 72.7 33.3 36.0 90.2 3.50 84.9 37.3 40.0 104.7 4.00 97.0 40.5 43.6 118.9 4.50 106.8 45.1 47.3 133.0 I I 1 1 1 1 n , 0 . 5 I.O 2 . 0 3 . 0 4 . 0 5 . 0 6 . 0 T-O I O 2 Molality F i g . 13 S o l u t i o n s o f C l t ^ F i n HSO^F are r e d - c o l o u r e d and h i g h l y conduct ing (Table and F i g u r e 13) . The U V - v i s i b l e a b s o r p t i o n spectrum corresponds + 19 to that o f C10 2 i n HSO^F. A F NMR spectrum of the s o l u t i o n r e v e a l s the presence o f HF as the o n l y f l u o r i n e - c o n t a i n i n g spec ies bes ides the s o l v e n t . The Y va lues are h i g h e r than the r e f e r e n c e KSO^F v a l u e s , which i s not unexpected s i n c e KF has a l s o been found t o be 45 more conduct ing than KSO^F (because HF behaves as a weak base i n HSO^F). In a d d i t i o n , the p r e p a r a t i o n of the s tock s o l u t i o n o f C10 2 F i n a pyrex c o n t a i n e r may have r e s u l t e d i n s i d e r e a c t i o n s and a very s l i g h t l y h i g h e r c o n d u c t i v i t y v a l u e . At c o n c e n t r a t i o n s below _2 10 m o l a l , Y va lues s l i g h t l y l e s s than 1 are o b t a i n e d . T h i s i s very l i k e l y due to the presence o f SO^ as an i m p u r i t y i n the HSO^F 45 which behaves as an a c i d i n t h i s s o l v e n t system . C h l o r y l f l u o r i d e appears t o i o n i z e i n HSO^F as f o l l o w s : C10 2 F + HS0 3 F • C 1 0 2 + + HF + S0 3 F~ HF + HSO.F »• H _ F + + S0,F~ T h i s would r e s u l t i n y v a l u e s g r e a t e r than 1 .0 . T h e - d e s c r i b e d b e h a v i o r o f C10 2 F i n HS0 3 F was s t u d i e d p r e v i o u s l y by Schmeisser and Fink*^ ' ' ' who p o s t u l a t e d the e q u i l i b r i u m : C10 2 F + HS0 3F < HF + C10 2 S0 3 F I t i s reasonable to assume t h a t i n d i l u t e s o l u t i o n s , HF and C10 2 S0 3 F w i l l be i o n i z e d and the e q u i l i b r i u m s h i f t e d t o the r i g h t . 78 In summary, C10 2 F a n d ClC^AsFg produce r e d - c o l o u r e d s o l u t i o n s i n HSO F as the r e s u l t o f the f o r m a t i o n o f d i s c r e t e CIO c a t i o n s . In a d d i t i o n , C10„SbF, d i s s o l v e s i n HS0„F to form a r e d - c o l o u r e d s o l u t i o n . Z D o I t seems then that the f l u o r i n e b r i d g e bonds are broken when the whi te c h l o r y l compounds are d i s s o l v e d i n the s t r o n g l y p r o t o n i c s o l v e n t o f h i g h d i e l e c t r i c c o n s t a n t : C10 2 F ( c o l o u r l e s s ) • C l 0 2 + (red) + F~ C 1 0 o A s F , (white) >- C I O * (red) + AsF 2 6 <•""—-' K J 6 n SbF^ (white) U- C I O * (red) + SbF," 2 o z o The above r e a c t i o n s i n d i c a t e the f i r s t s tep i n the i o n i z a t i o n o f these compounds i n HSO^F. D i s c r e t e C 1 0 2 + c a t i o n s are formed and s t a b i l i z e d by s o l v a t i o n w i t h HSO^F. C H A P T E R F I V E DICHLORYL HEXAFLUOROSTANNATE : CHLORYL COMPOUNDS (WHITE) PART I I CONTINUED 5.1 INTRODUCTION I t became i n t e r e s t i n g to extend the s tudy o f c h l o r y l compounds to d i c h l o r y l h e x a f l u o r o s t a n n a t e , (C102)2SnF^. In a d d i t i o n t o v i b r a t i o n a l s p e c t r o s c o p y , i t would be now p o s s i b l e 119 to use Sn Mossbauer spectroscopy as a means o f o b t a i n i n g s t r u c t u r a l i n f o r m a t i o n and d e t e c t i n g p o s s i b l e a n i o n - c a t i o n i n t e r a c t i o n i n t h i s compound. The d i s t o r t i o n o f the anion octahedron as a r e s u l t o f a n i o n -c a t i o n i n t e r a c t i o n s h o u l d r e s u l t i n a n o n - v a n i s h i n g e l e c t r i c f i e l d g r a d i e n t and subsequent ly i n a quadrupole s p l i t t i n g . An asymmetric d i s t r i b u t i o n of e l e c t r o n d e n s i t y i n va lence o r b i t a l s about the t i n nucleus w i l l cause a quadrupole s p l i t t i n g . Al though Greenwood and Ruddick''''''^ f i r s t i n t e r p r e t e d the quadrupole s p l i t t i n g i n hexacoordinated 117-118 t i n as a pit-dir bonding e f f e c t , i t i s now g e n e r a l l y b e l i e v e d that a-bonding e f f e c t s , that i s , d i f f e r e n c e s i n bond p o l a r i t i e s , are the dominant f a c t o r i n p r o d u c i n g a quadrupole s p l i t t i n g . 119 I t has been shown on adducts o f the type S n C l ^ " 2R2SO t h a t molecular d i s t o r t i o n caused by b u l k y l i g a n d groups can g i v e r i s e to s m a l l quadrupole s p l i t t i n g s . 80 A f t e r the r e s e a r c h d e s c r i b e d i n t h i s chapter had been completed, 120 121 we learned o f a p u b l i c a t i o n by Sukhovrekhov et a l ' ,who have found quadrupole s p l i t t i n g f o r SnF^ complexes w i t h h e t e r o c a t i o n s BrF2 +, B r F ^ * , C I F ^ * and I F ^ + . U n f o r t u n a t e l y , the v i b r a t i o n a l s p e c t r a of these complexes have not yet been r e p o r t e d . 119 The Sn chemical s h i f t i s commonly used as a measure o f the 5s e l e c t r o n d e n s i t y around t i n . I t has been p r e v i o u s l y r e p o r t e d that 122 the h e x a f l u o r o s t a n n a t e a n i o n , SnF^ , has a very low chemical s h i f t The r e p o r t e d v a l u e both f o r I^SnF^ and Cs^SnF^ o f -0 .44 mm/sec i s 4+ 123 even lower than the c a l c u l a t e d va lue f o r a Sn i o n . T h e r e f o r e , e l e c t r o n i c i n t e r a c t i o n s between the SnF^ a n i o n and h e t e r o c a t i o n s o should a f f e c t the chemical s h i f t v a l u e . P r e v i o u s r e p o r t s on the v i b r a t i o n a l spectrum o f the h e x a f l u o r o -124—126 stannate an ion are both incomplete and i n c o n s i s t e n t . Consequent ly , t h i s chapter i s a l s o concerned w i t h the complete assignments o f the fundamental v i b r a t i o n s o f the SnF, a n i o n . b 5.2 EXPERIMENTAL 3 C h l o r y l f l u o r i d e ,CIO2F, was prepared as a c c o r d i n g t o Woolf . For the p r e p a r a t i o n o f (CIO2)2SnF^, the method o f Schmeisser and F i n k " " ^ was adopted but w i t h m o d i f i c a t i o n s and w i t h o u t the use o f CFClg as a s o l v e n t . The p r e p a r a t i o n i s d e s c r i b e d as f o l l o w s : To minimize the hazard i n v o l v e d i n h a n d l i n g CIO2J 89.1 mmoles o f CIO2F were i n t r o d u c e d i n s m a l l p o r t i o n s i n t o a monel metal r e a c t i o n v e s s e l (F igure 2) c o n t a i n i n g 8.43 mmoles o f p u r i f i e d S n C l ^ ( F i s h e r S c i e n t i f i c C o . ) by vacuum d i s t i l l a t i o n i n a metal l i n e . The r e a c t o r was warmed to room temperature and the v o l a t i l e b y - p r o d u c t s CIC^ and C l ^ were removed by pumping. T h i s procedure was repeated s e v e r a l t imes u n t i l a l l the ClO^F was added. The v o l a t i l e products were removed aga in by pumping and the i n v o l a t i l e s o l i d , i n d i c a t e d by the weight i n c r e a s e , corresponded to ( C l O ^ ^ n F ^ . Potass ium h e x a f l u o r o s t a n n a t e was p u r i f i e d by r e c r y s t a l l i z a t i o n from anhydrous HF i n a p o l y e t h y l e n e r e a c t o r . Sodium Hexaf luoros tannate was prepared from N a 2 S n 0 3 ( F i s h e r S c i e n t i f i c C o . ) i n 49% HF ( F i s h e r S c i e n t i f i c C o . ) . The i n f r a r e d spectrum o f K^SnF^ was recorded on a P e r k i n Elmer 301 High R e s o l u t i o n G r a t i n g Spectrophotometer f o r the range 666-166 cm * N u j o l as a m u l l i n g agent and C s l c e l l windows were used . 5 .3 RESULTS AND DISCUSSION 5 . 3 . 1 V i b r a t i o n a l Spec t ra The i n f r a r e d and Raman data f o r the compounds Na„SnF,, K„SnF, z 6 z 6 and ( C 1 0 2 ) 2 S n F £ are l i s t e d i n Table 14. The v i b r a t i o n a l f r e q u e n c i e s f o r the SnF ~ a n i o n i n K„SnF^ and Na„SnF, are t a b u l a t e d i n Table 15. 6 2 6 2 6 The p r e v i o u s l y r e p o r t e d v a l u e s f o r Na 2 SnF^ and K^SnF^, as w e l l as a number o f o ther SnF^ compounds,are i n c l u d e d . The a l k a l i metal compounds, I^SnF^ and C s ^ n F ^ are r e p o r t e d to have the t r i g o n a l I^GeF^ s t r u c t u r e w i t h the an ion hav ing D^^ s i t e 127 128 symmetry. ' An orthorhombic s t r u c t u r e w i t h a D ^ symmetry s i t e 127 f o r the an ion i s found f o r Na 0SnF,. z o TABLE 14: V i b r a t i o n a l Frequencies For SnF Compounds (cm ) Na^SnF, 2 0 K 2SnF 6 Ccio 2 ) 2 SnF £ 0 I . R . RAMAN I .R . RAMAN I . R . RAMAN 590 sh 594 vs 582 w,sh 628 vw,sh 1302 vs 1309 m 560,vs 480 m 557 vs 598 vs 1290 vs 1293 m 475 vw,sh 416 w 480 vw 478 vs 1076 s 1080 vs 367 vw 420 vw 423 w 1072 s 255 ms 367 vw 368 w 634 s , s h 628 m-: 162 m 257 s 258 s 624 s , s h 254 s , sh 606 s 613 s 163 m 561 vs 563 vw 541 s , s h 549 s 522 s , s h 519 m 470 m-s 482 m 465 •W,: 423 w 314 w 367 w vw = v e r y weak; s = s t r o n g ; w = weak; vs = very s t r o n g ; m-= medium; sh = shoulder oo TABLE 15: V i b r a t i o n a l Frequencies f o r the SnF, A n i o n Compound v , ( A ) v„(E ) v - C F , ) v . (F, ) v c ( F „ ) Reference r 1 l g 2 g 3 l u 4 l u 5 2g K 2 S n F 6 ( s ) 598 478* 582,557 257,254 257 T h i s N a 2 S n F 6 ( s ) 594 480* 590,560 255 T h i s (NO) 2 SnF 6 ( s ) 593 481* 585,555 258 256 29 ( N 0 2 ) 2 S n F 6 ( s ) 590 478 590,565 29 C s 2 S n F 6 (s) 572 460 577,555 256,239 247 126 K 2 S n F 6 . H 2 0 ( s ) 593 620 564 342 125 N a 2 S n F 6 ( s ) 592 477 559 300 252 129 ( N H 4 ) 2 S n F 6 (aq. s o l n . ) 585 470 241 126 * denotes both IR and Raman a c t i v e 130 As a consequence , the i n f r a r e d a c t i v e v i b r a t i o n s ^ ( F ^ ) a n d v ^ ( F ^ u ) f o r K^SnF^ should both be s p l i t i n t o the two components a ^ u and e ^ . A s i m i l a r s p l i t t i n g i s expected f o r V j - t ^ ) r e s u l t i n g i n the components a^ and e . The h i g h r e s o l u t i o n i n f r a r e d spectrum o f I^SnF^ i s reproduced i n F i g u r e 14. As can be seen, both at cm and at 257 cm * have shoulders at 582 cm * and 254 cm * r e s p e c t i v e l y . In a d d i t i o n , v 2 ( E ) appears as a weak a b s o r p t i o n peak at 478 cm * . The Raman a c t i v e v i b r a t i o n v,., however, i s found as a s i n g l e peak i n the Raman -1 126 spectrum (at 257 cm ) i n agreement w i t h p r e v i o u s work f o r C ^ S n F ^ . 125 -1 Kriegsmann and K e s s l e r have r e p o r t e d a shoulder at 620 cm i n the i n f r a r e d spectrum o f K^SnF^.H^O, and have ass igned the same to the Raman a c t i v e v i b r a t i o n which becomes weakly a c t i v e i n the 126 i n f r a r e d . As remarked by Dean and Evans and i n v iew o f the v a l u e s r e p o r t e d f o r f o r a l l o ther SnF^~ compounds, t h i s assignment i s undoubtedly i n c o r r e c t . The p r e v i o u s l y r e p o r t e d v i b r a t i o n a l s p e c t r a o f Na^SnF^ by Begun 129 and Rutenberg are conf i rmed except f o r t h e i r assignment of at 300 cm * and t h e i r f a i l u r e t o r e p o r t a s p l i t t i n g f o r v^. No unusual f e a t u r e s are observed f o r the Raman s p e c t r a o f the SnF^ compounds l i s t e d i n Table 15. The s p e c t r a are v e r y s i m i l a r 126 to t h a t o b t a i n e d f o r an aqueous s o l u t i o n o f (NH^^SnF^ . In the i n f r a r e d s p e c t r a , the s p l i t t i n g o f the and modes and the occurrence o f the f o r b i d d e n t r a n s i t i o n are a t t r i b u t e d to s i t e symmetry e f f e c t s . 86 However, no s imple e x p l a n a t i o n based on an i o n i c compound w i t h an a n i o n s i t e o f lower symmetry than 0^ appears to be p o s s i b l e f o r ( C l C ^ ^ S n F ^ . I t s v i b r a t i o n a l s p e c t r a are reproduced i n F i g u r e s 15 and 16. The h i g h r e a c t i v i t y of t h i s compound r e l a t i v e to the c o r r e s p o n d i n g a l k a l i metal complexes prevented h i g h r e s o l u t i o n i n f r a r e d s p e c t r o s c o p y . A l s o , attempts to observe low frequency Raman bands f a i l e d . C o n s e q u e n t l y , the i n t e r p r e t a t i o n o f the v i b r a t i o n a l s p e c t r a o f ( C l G ^ ^ S n F ^ i s r e s t r i c t e d to the range down to 300 cm ^ and the a n i o n fundamentals v±>v2 a n d V 3 ' F o c u s s i n g our a t t e n t i o n t o the a n i o n as a sensor f o r a n i o n - c a t i o n i n t e r a c t i o n , the f o l l o w i n g f e a t u r e s o f the Raman spectrum, shown i n F i g u r e 16 i n the range o f 800-300 cm * are noteworthy : v ^ , which i s s p l i t i n t o 2 components, presumably as a r e s u l t o f s o l i d - s t a t e s p l i t t i n g , i s s h i f t e d to h i g h e r f r e q u e n c i e s as i t occurs i n K^SnF^, and i s observed at 628 and 606 cm The n o r m a l l y Raman i n a c t i v e i s observed as a s t r o n g a b s o r p t i o n band at 549 cm * w i t h a weak s h o u l d e r at 563 cm ^. occurs as a weak a b s o r p t i o n band at 470 cm * . A b s o r p t i o n bands at 423 and 367 cm * appear ing as v e r y weak and d i f f u s e peaks are seen i n a l l SnF^ Raman s p e c t r a and are due to the pyrex t u b e s . (For Na^SnF^ and K^SnF^, the moderately s t r o n g band at about 165 cm a l s o r e s u l t s by background a b s o r p t i o n from the pyrex t u b e . FIGURE 15: The I n f r a r e d Spectrum o f (C10 o ) o SnF / . 2 2 6 ( C I 0 2 ) 2 S n r J FIGURE 16: The Raman Spectrum o f (CIO ) SnF The i n f r a r e d spectrum o f ( C l O ^ ^ n F ^ shown i n F i g u r e 15 has a very b r o a d , b a r e l y r e s o l v e d band i n the r e g i o n from 630 cm 1 t o 520 cm 1 Assignments f o r the anion v i b r a t i o n s gre d i f f i c u l t f o r two reasons : (1) R e s o l u t i o n i s r a t h e r poor and (2) i t becomes d i f f i c u l t to d i s t i n g u i s h between a t r u e s p l i t t i n g or a d d i t i o n a l peaks caused by a breakdown o f the mutual e x c l u s i o n r u l e s . Two components o f are ass igned t o the a b s o r p t i o n at 561 cm 1 and a shoulder peak at -1 -1 541 cm . v occurs as a f o r b i d d e n t r a n s i t i o n s p l i t at 634 cm and 606 cm ^ , w h i l e i s observed as a medium s t r o n g band at 478 cm 1 . I t i s d i f f i c u l t to r e c o n c i l e the v i b r a t i o n a l s p e c t r a o f (C10_) o SnF, I 2 o w i t h an i o n i c s t r u c t u r e and anion s i t e o f lower symmetry than o c t a h e d r a l As i n the case o f the s p e c t r a o f d O ^ s F ^ and ClO^SbF^, s t r o n g a n i o n -c a t i o n i n t e r a c t i o n i s suggested. A n i o n - c a t i o n i n t e r a c t i o n should a f f e c t the v i b r a t i o n a l modes o f the c a t i o n as w e l l . The a b s o r p t i o n peaks i n the s p e c t r a due t o C l O ^ * are shown i n Table 16: TABLE 16: V i b r a t i o n a l Frequencies o f CIO + i n (CIO ) SnF (cm" 1 ) I . R . . . . . RAMAN ASSIGNMENT 1302,1290 1309,1293 v 3 C10 2 Asym. 1076,1072 1080 v C 1 0 2 Sym. 522 519 v 2 C 1 0 2 Bending As ClO^ i s i s o e l e c t r o n i c w i t h SO^j i t i s reasonable to expect C 2 v symmetry. T h i s would make a l l three v i b r a t i o n s non-degenerate and both i n f r a r e d and Raman a c t i v e . A p o s s i b l e i n t e r a c t i o n should t h e r e f o r e a f f e c t o n l y the band p o s i t i o n s . T h i s i s i l l u s t r a t e d by a comparison o f the C 1 0 2 + f r e q u e n c i e s f o r the white c h l o r y l compounds. The average s t r e t c h i n g f r e q u e n c i e s are r a i s e d by 5-10 cm * when going from C 1 0 2 A s F 6 over C 1 0 2 S b F 6 t o ( C l O ^ S n F ^ In p a r t i c u l a r , the symmetric v i b r a t i o n f o r the h e x a f l u o r o s t a n n a t e anion i s s h i f t e d upwards by about 30 wave numbers compared t o C10 2 AsFg and C l O ^ b F ^ . A g a i n , i n t e r a c t i o n between the an ion and the c a t i o n w i l l l i k e l y occur over f l u o r i n e b r i d g e s . In the l a s t c h a p t e r , the involvement o f the b1 m o l e c u l a r o r b i t a l (of C 1 0 2 ) i n bonding i n C 1 0 2 F , C 1 0 2 A s F 6 and C10„SbF £ was invoked to e x p l a i n the absence o f c o l o u r f o r CIO + . 2 6 2 The noted i n c r e a s e i n the average s t r e t c h i n g f r e q u e n c i e s o f the C 1 0 2 + c a t i o n i n ( C l O ^ ^ n F ^ can be e x p l a i n e d by e l e c t r o n t r a n s f e r p o s s i b l y i n v o l v i n g the b ^ " and the a^ g m o l e c u l a r o r b i t a l s on C 1 0 2 , where e l e c t r o n w i t h d r a w l from the c a t i o n r e s u l t s i n an i n c r e a s e d e l e c t r o n d e n s i t y i n the t i n - f l u o r i n e bonding r e g i o n . I f t h i s i d e a i s c o r r e c t and p r o v i d e d an e l e c t r o n t r a n s f e r s t a b i l i z e s c e r t a i n Sn-F bonds over o t h e r s , the e f f e c t on the Mossbauer spectrum s h o u l d be n o t i c e a b l e . 91 5 . 3 . 2 Mossbauer Spectra The Mossbauer data f o r the SnF 6 ~ complexes are l i s t e d i n Table 17 f o r 80° and 298° K. The accuracy l i m i t f o r the Mossbauer data i s judged to be - 0.03 mm/sec f o r both the isomer s h i f t and the quadrupole s p l i t t i n g . The l i n e w i d t h v a l u e s are a l s o l i s t e d i n Table 17, as w e l l 131 as the room temperature e f f e c t R , where R i s d e f i n e d as e o n o o / e o n o , 298 80 e b e i n g the magnitude o f the Mossbauer e f f e c t . A l l compounds s t u d i e d , 29 as w e l l as (N0)_SnF, and (N0_) SnF^ i n c l u d e d i n the t a b l e f o r Z D 2 2 ° comparison, gave w e l l - r e s o l v e d s p e c t r a at room temperature , a f e a t u r e 131 132 49 n o r m a l l y a s s o c i a t e d w i t h i n t e r m o l e c u l a r a s s o c i a t i o n ' ' and p o l y m e r i c s t r u c t u r e s . As i n d i c a t e d by the v i b r a t i o n a l s p e c t r a , the e x c e p t i o n a l p o s i t i o n o f (C102)2S n F D i s a l s o found f o r the Mossbauer spectrum. The isomer s h i f t i s the h i g h e s t r e p o r t e d i n t h i s s e r i e s , i n d i c a t i n g an i n c r e a s e i n s - e l e c t r o n d e n s i t y around t i n . As shown i n F i g u r e 17, a w e l l - r e s o l v e d quadrupole s p l i t t i n g o f about 1.00 mm/sec i s observed. The A va lue i s comparable to the p r e v i o u s l y r e p o r t e d v a l u e s f o r ( E h ^ ^ S n F ^ i o n and C B r F 4 ) 2 S n F 6 o f 0.80 and 1.15 mm/sec r e s p e c t i v e l y . The occurrence o f quadrupole s p l i t t i n g i n these compounds i n d i c a t e s c o n s i d e r a b l e d e p a r t u r e from o c t a h e d r a l symmetry f o r the S n F ^ - a n i o n , which i s best e x p l a i n e d by a n i o n - c a t i o n i n t e r a c t i o n . In c o n t r a s t , the Mossbauer s p e c t r a o f K„SnF., N a . S n F , , (N0)_SnF. 2 O 2 O Z D and (ITC^^SnF^ a l l show broad s i n g l e t s . T h i s l i n e broadening i s a t t r i b u t e d to u n r e s o l v e d quadrupole s p l i t t i n g s which can be produced as the r e s u l t o f the low s i t e symmetry o f the a n i o n . 92 I t i s p o s s i b l e by means o f computer f i t t i n g to r e s o l v e t h i s s p l i t t i n g . T h i s i s the case f o r the Mossbauer spectrum o f ( N C O . S n F , . . 2 2 b In c o n c l u s i o n , the v i b r a t i o n a l and Mossbauer s p e c t r a o f (C10_)„SnF, 2 2 b are i n c o n s i s t e n t w i t h a s imple i o n i c s t r u c t u r e f o r t h i s compound. Al lowance must be made f o r a s u b s t a n t i a l i n t e r a c t i o n between the anion and the c a t i o n . ( S i m i l a r c o n c l u s i o n s f o r the f l u o r o - h a l o g e n h e t e r o c a t i o n complexes ( C I F J „ S n F , , ( B r F J - S n F . , (BrF, )„SnF^ and 2 2 b 2 2 b 4 2 b 120 121 ( I F ^ ^ S n F ^ have been p r e v i o u s l y made by Sukhovrekhov and D z e v i t s k i i ' on the b a s i s o f Mossbauer s p e c t r o s c o p y . ) I t appears , however, not p o s s i b l e to d i s c r i m i n a t e between and s i t e symmetry f o r the t i n atom, as the two most obvious p o s s i b i l i t i e s f o r a d i s t o r t e d o c t a h e d r a l a n i o n , m a i n l y because no s a t i s f a c t o r y v i b r a t i o n a l s p e c t r a i n the r e g i o n o f v . and v r c o u l d be o b t a i n e d . 5 4 5 TABLE 17: Mossbauer Data For SnF Compounds Compound Temp. (°K) Isomer S h i f t 6 (mm/sec) Quadrupole S p l i t t i n g A (mm/sec) L i n e w i d t h R Na^SnF. 80 - .480 1.77 0.71 2 6 298 - .528 - 1.35 K SnF, 80 - .432 1.59 0.61 2 6 298 - .468 - 1.11 (NO) 2 SnF 6 80 - .421 - 1.45 298 - .456 - 1.10 ( N 0 2 ) 2 S n F 6 80 - .431 .769 1.46 ' 1.57 0.58 298 - .504 .680 1.11 1.75 ( C 1 0 2 ) 2 S n F 6 80 - .403 1.008 1.46 1.46 0.71 298 - .433 .956 1.16 1.11 94 C H A N N E L S FIGURE 17: The Mossbauer Spectrum o f (C10J- ,SnF C H A P T E R S I X STRUCTURAL STUDIES OF HEXAFLUOROARSENATES AND -ANTIMONATES OF FLUORO-HALOGEN HETEROCATIONS 6.1 INTRODUCTION Hexaf luoroarsenate and -ant imonate complexes o f f l u o r o - and oxy-133 element h e t e r o c a t i o n s have been known f o r some t ime . These complexes are formed by the r e a c t i o n o f the Lewis a c i d s AsF,. or SbF,. w i t h an element f l u o r i d e or element o x y f l u o r i d e t o form a 1:1 complex: EF , M F . n-1 6 EO F + M F r >- EO ,MF^ m 5 m - l 6 E = P , S, Se, C l , B r , I and o thers M = A s , Sb A l a r g e number o f f l u o r i d e s can act as Lewis a c i d s i n the above equat ions ( e . g . BF^, S i F 4 , GeF^, T i F ^ , V F 5 , N b F 5 , P F 5 and o t h e r s ) . The two most l i k e l y and extreme forms f o r the molecu lar s t r u c t u r e o f these complexes a r e : (1) a covalent s t r u c t u r e , e . g . E F ^ M F j . , a 1:1 adduct i n v o l v i n g b r i d g i n g over f l u o r i n e ; (2) an i o n i c s t r u c t u r e c o n s i s t i n g o f d i s c r e t e i o n s , where the Lewis a c i d has comple te ly e x t r a c t e d a f l u o r i d e i o n from the element f l u o r i d e or o x y f l u o r i d e . EF + M F r n 5 96 A number of such h e x a f l u o r o a r s e n a t e and -antimonate complexes are shown i n Table 18. These complexes have been suggested to be 3 i o n i c i n the p a s t . Woolf , f o r example, p o s t u l a t e d i o n i c s t r u c u r e s f o r C l O J V s F , and C10_SbF, . On the b a s i s o f c o n d u c t i v i t y d a t a i n z o z o 134 l i q u i d frrf^j Woolf and Emeleus proposed f o r the 1:1 complex produced from the r e a c t i o n of BrF„ and SbF_ the s t r u c t u r e BrF_ + SbF^ 3 5 z 6 i n l i e u o f B r F ^ S b F . . R e c e n t l y , the s t r u c t u r a l aspects of t h i s c l a s s o f compounds 133 have r e c e i v e d much a t t e n t i o n . However, there has been some c o n t r o v e r s y i n the s t r u c t u r a l i n t e r p r e t a t i o n . The v i b r a t i o n a l 103 135 136 s p e c t r a o f the r e l a t e d compounds C102AsF^ and ClF2AsF^ ' have been i n t e r p r e t e d u s i n g a s t r i c t l y i o n i c model as evidenced by e l a b o r a t e f o r c e constant c a l c u l a t i o n s . On the o ther hand, evidence f o r a n i o n - c a t i o n i n t e r a c t i o n i n C102AsF^ was presented i n Chapter 4 . A s i m i l a r i n t e r p r e t a t i o n i s i n d i c a t e d by the x - r a y 137 d i f f r a c t i o n s tudy o f BrF2SbF^ , where a d i s t o r t e d o c t a h e d r a l -SbF^ u n i t i s f o u n d , e x e r t i n g f l u o r i n e b r i d g e bonding to bromine i n the c a t i o n . The purpose o f t h i s chapter , i s to extend the s tudy o f the c h l o r y l compounds C102AsF^ and C102SbF^ (chapter 4) to the r e l a t e d compounds o f f l u o r o - h a l o g e n h e t e r o c a t i o n s . In p a r t i c u l a r , a comparative study of C l F 2 A s F ^ , C l F 2 S b F ^ and BrF2SbF^ i s made u s i n g i n f r a r e d spectroscopy down t o 250 cm * and l a s e r Raman s p e c t r o s c o p y . The c a t i o n s C1F2 + and B r F 2 + are chosen because they are t r i a t o m i c , presumably bent and o f comparable s i z e to the C102 + c a t i o n . TABLE 18: AsF,~ AND SbF," COMPLEXES OF FLUORO- AND OXY-ELEMENT HETEROCATIONS PERIOD GROUP 5A GROUP 6A GROUP 7A N 2FAsF 6 N0AsF 6 2 N 2F 3AsF 6 N0 2ASF 6 NF.AsF, NOSbF, 4 6 6 F oN0AsF, NO„SbF, I o I o PF 2AsF 6 SF 3AsF 6 C£F 2AsF 6 3 PF 2SbF 6 SF 3SbF 6 C£F 2SbF 6 C£0 2AsF 6 CJl0 2SbF 6 4 SeF 3AsF 6 SeF 3SbF 6 BrF~SbF, l o to From a study o f a number o f r e l a t e d n i t r o g e n -oxy and - f l u o r o h e x a f l u o r o a r s e n a t e s and - a n t i m o n a t e s 1 1 ^ , a narrow frequency range f o r the a c t i v e v i b r a t i o n a l fundamentals o f A s F , and SbF. has been 6 6 e s t a b l i s h e d . These compounds were suggested to have i o n i c s t r u c t u r e s , and t h e r e f o r e should be u s e f u l i n comparison w i t h the v i b r a t i o n a l s p e c t r a o f the c o r r e s p o n d i n g - A s F ^ and -SbF^ complexes o f f l u o r o -halogen h e t e r o c a t i o n s . A n i o n - c a t i o n i n t e r a c t i o n i n the l a t t e r compounds i s expected to a f f e c t the v i b r a t i o n a l modes o f the h i g h l y symmetr ica l an ion i n the f o l l o w i n g ways: (1) removal o f the degeneracy of the E and F modes; (2) r e l a x a t i o n o f the mutual e x c l u s i o n r u l e f o r Raman and IR a c t i v e v i b r a t i o n s and (3) a genera l s h i f t i n f r e q u e n c i e s from where they occur i n the v i b r a t i o n a l s p e c t r a o f the corresponding i o n i c potass ium s a l t s , K A S F Q a n ( i KSbF^. As a c c o r d i n g to Walsh ' s 97 p r e d i c t i o n s , the c a t i o n s are a l l expected to have symmetry, where a l l three v i b r a t i o n s are non-degenerate and both Raman and i n f r a r e d a c t i v e . S h o r t l y a f t e r the t ime tha t t h i s study had been completed, 138 G i l l e s p i e and Morton r e p o r t e d the Raman s p e c t r a o f C l F ^ A s F ^ 13S 136 and C l F ^ S b F ^ . In c o n t r a s t to e a r l i e r work ' , they have concluded that there i s f l u o r i n e b r i d g i n g between the C I F ^ * c a t i o n and the a n i o n s . 99 6.2 EXPERIMENTAL' A l l compounds were found to be v e r y s e n s i t i v e towards mois ture and h i g h l y r e a c t i v e . E i t h e r the monel metal vacuum l i n e or dry-box was employed i n the t r a n s f e r of m a t e r i a l s . The 2 -par t monel metal r e a c t i o n s v e s s e l s (F igure 2) were used . A l l reagents were p u r i f i e d by d i s t i l l a t i o n . F o l l o w i n g p u r i f i c a t i o n , SbF^ was added to the r e a c t i o n v e s s e l i n the d r y box , w h i l e AsF,. was d i s t i l l e d d i r e c t l y i n the vacuum l i n e . Except f o r the use o f monel metal vacuum l i n e equipment and r e a c t o r s , the r e p o r t e d p r e p a r a t i v e 139 140 routes were employed ' . The r e a c t i o n s were f o l l o w e d by w e i g h t , w i t h the most v o l a t i l e component i n excess . 6.3 RESULTS AND DISCUSSION  6 .3 .1 R e s u l t s The i n f r a r e d and Raman v i b r a t i o n a l s p e c t r a o f C l F ^ A s F ^ , ClF„SbF, and BrF„SbF, are reproduced i n F i g u r e s 18 - 21, w h i l e z 6 z 6 the f r e q u e n c i e s and i n t e n s i t i e s are l i s t e d i n Table 19. The Raman spectrum o f ClO^SbF^ i s i n c l u d e d i n F i g u r e 21 w i t h the ~SbF^ complexes f o r the purpose o f comparison. A g a i n , as i n Chapters 4 and 5 , assignments can be made on the b a s i s of predominant ly i o n i c s t r u c t u r e s , and w i t h r e f e r e n c e to the i o n i c s a l t s KAsF, and KSbF , . 100 TABLE 19: The V i b r a t i o n a l Spec t ra of C l F 2 S b F 6 , C l F _ A s F . and BrF„SbF, Z D Z D ClF„SbF. C l F . A s F . BrF„SbF. 2 6 2 6 2 6 IR RAMAN IR RAMAN IR RAMAN (cm 1 ) (cm 1 ) (cm 1 ) (cm (cm 1 ) ( c m - 1 ) 1310 vw 1064 vw 830 sh,vw 826 s h , s 2315 ms 706 vs 1295 vw 1040 vw 813 br ,w .809 vs 673 vs 693 w 1065 vw 833 m 688 vs 693 vs 663 vs , b r 679 s 830 s 810 vs 605 m 603 w 638 s 641 s 803 s 662 vs 560 wm 544 s 535 m, sh 552 vs 677 s 644 w 520 w 382 s 523 ms 523 m 660 s 596 w 383 vs 372 s 495 ms 493 ms 647 s 542 mw 310 w 370 w,sh 367 m 604 s , sh 537 mw 285 m,sh 284 m,sh 582 mw 385 mw 270 m,sh 270 m 375 mw 292 w 265 m 290 w,sh 282 m 283 w,sh 267 m 265 s Vw = v e r y weak, mw = medium weak, w = weak, m = medium, s = s t r o n g vs = v e r y s t r o n g , sh = s h o u l d e r , b r = broad — | ' 1 1 — I r -lOOO 8 0 0 600 4 0 0 250 Wave number ( c m r 1 ) FIGURE 18: The IR Spectrum o f C l F 2 A s F 6 FIGURE 19: The Raman Spectrum of C l F - A s F , 2 6 C I E ; Asf^  9 0 0 8 0 0 7 0 0 6 0 0 , 5 0 0 4 0 0 3 0 0 Wavenumber ( c m H ) 2 0 0 T h e R a m a n S p e c t r a of C\FZ SDrf , B r f f S b r j a n d C I 0 2 S b f ^ r i i i 1 1 1 — 900 800 700 600 500 400 300 Wavenumber (cm - 1 ) F I G U R E 21 105 138 Agreement w i t h the r e s u l t s o f G i l l e s p i e and Morton i s good except f o r minor d i f f e r e n c e s . A s m a l l s p l i t t i n g o f v ^ C l F ^ * observed by these authors i n the Raman spectrum of ClF^SbF^ and i n t e r p r e t e d as a s o l i d s t a t e s p l i t t i n g was not r e s o l v e d i n t h i s work. In a d d i t i o n , a shoulder o f weak i n t e n s i t y at 644 cm 1 was observed. 6 .3 .2 Assignment of the C a t i o n V i b r a t i o n s The v i b r a t i o n a l f r e q u e n c i e s ass igned f o r the c a t i o n i c groups C I F ^ * and BrF^* are presented i n Table 20. The v i b r a t i o n a l modes of the C 1 F 2 + c a t i o n can be ass igned on the b a s i s o f comparison w i t h the i s o e l e c t r o n i c spec ies ClO^ , which has v ^ , \>2, and at 804, 432 and 832 cm 1 r e s p e c t i v e l y . The assignments f o r C 1 F 2 + d i f f e r from 136 those p r e v i o u s l y r e p o r t e d by C h r i s t e and Sawodny i n tha t the C 1 F 2 + bending mode, v^, i s ass igned to the band at 382 cm 1 ( i n C1E> A s F , ) r a t h e r than 544 cm 1 . In a d d i t i o n , these authors were unable 2 D to r e s o l v e the C I F ^ * asymmetric and symmetric s t r e t c h i n g f r e q u e n c i e s i n the Raman spectrum which i n t h i s work were found n o t i c e a b l y separated at 826 and 809 cm 1 r e s p e c t i v e l y . + -1 -1 The reassignment of V 2 C 1 F 2 (382 cm v . s . 544 cm ) i s made f o r the f o l l o w i n g r e a s o n s : (1) The d i f f i c u l t y i n a s s i g n i n g the bending mode o f C 1 F * i n ClFJ\.sF, l i e s i n the f a c t tha t the AsF ~ Z Z O O anion a l s o absorbs i n t h i s r e g i o n . However, the v i b r a t i o n a l s p e c t r a o f C l F 0 S b F ^ a l s o show a band near 380 cm 1 , where the SbF^ an ion 2 D 6 does not absorb . (2) The v a l u e f o r of 382 cm 1 i s i n much c l o s e r agreement to t h a t f o r the i s o e l e c t r o n i c spec ies C l O ^ where v 2 C 1 0 2 = 432 cm ^, 106 TABLE 20 V i b r a t i o n a l Frequencies o f the Species C1F + and B r F „ + (cm *) Species Compound Method v. ,,v„ v C 1 F 2 + C l F 0 A s F £ Raman 809 382 826 G I F / C l F J V s F , I 0 IR 813 - 830 C 1 F 2 + ClF„SbF, / 6 Raman 810 385 833 G I F / C l F 0 S b F , 2. o IR 803 375 830 B r F 2 + BrF„SbF / o Raman 706 366 -B r F 2 + BrF„SbF, / o IR - 365 715 ) 107 (3) As a " r u l e o f thumb", the bending mode i n bent t r i a t o m i c spec ies always seems t o occur at a wavenumber equal t o approximate ly o n e - h a l f the symmetric s t r e t c h i n g frequency (see Table I I - 7 i n re fe rence 59) . In accordance w i t h the assignments of the CIF^* s t r e t c h i n g f r e q u e n c i e s , the assignment o f the bending mode at 544 cm 1 would be too h i g h . P r i n c i p a l d i f f i c u l t i e s are encountered i n the assignment o f the v i b r a t i o n a l f r e q u e n c i e s and f o r B r F 2 + , because both are expected and found r o u g h l y i n the same r e g i o n as and v^CSbF^ ) . T h i s leads to poor r e s o l u t i o n n o t i c e a b l e p a r t i c u l a r l y i n the IR spectrum. The bending mode \)^{BrF^+) i s found at 366 cm thus l e n d i n g support to the reassignment o f V 2 ( C 1 F 2 + ) q u i t e w e l l . The i n t e n s e v i b r a t i o n at 706 cm 1 i n the Raman spectrum o f BrF2SbF^ i s bes t ass igned as and a s t r o n g shoulder i n the i n f r a r e d at 715 cm 1 i s ass igned as which i s not r e s o l v e d i n the Raman spectrum. T h i s t e n t a t i v e assignment i s i n good agreement w i t h the C1F2 + bands. The extremely h i g h i n t e n s i t y o f v^(BrF2 + )^ which i s found to be the s t ronges t peak i n the Raman spectrum i s noteworthy. 6 . 3 . 3 Assignment o f the Anion V i b r a t i o n s Assignments f o r the AsF^ an ion i n both the IR and Raman s p e c t r a o f ClF2AsF^ are shown i n Table 21. A comparison o f the AsF^ f r e q u e n c i e s i n C l F . A s F , . and i n K A s F , , ClOJVsF,. and i n a number of complexes 2 b 6 2 b c o n t a i n i n g n i t r o g e n f l u o r o - a n d o x y - c a t i o n s i s made i n Table 22. The p o l y f l u o r o a n i o n complexes c o n t a i n i n g h e t e r o c a t i o n s o f n i t r o g e n have been i n t e r p r e t e d as i o n i c complexes where a p p r e c i a b l e a n i o n - c a t i o n i n t e r a c t i o n i s absent : s m a l l s p l i t t i n g s i n the mode and the appearance of \>2 as a weak a b s o r p t i o n band i n the IR spectrum are p o s s i b l y due to s i t e symmetry e f fec ts . ' ' ' 4 ' ' ' TABLE 21: Frequency Assignments o f AsF i n ClF„AsF (cm *) 6 2 6 I . R . RAMAN Assignment 693 v l C A l g ) 605,560 603,544 v 2 CE ) 688 - v 3 C F l u ) 383 - v 4 ( F l u ) 382,372 V 5 ( F 2 g ) V F 2 J In c o n t r a s t to the v i b r a t i o n a l s p e c t r a o f the o ther AsF.. 6 compounds i n Table 22, UpfAsF^ ) appears to be w i d e l y s p l i t at 603 cm * and 544 cm * i n the Raman spectrum as w e l l as i n the IR spectrum o f C l F ^ s F ^ . . v i n the Raman spectrum appears to be s p l i t at TABLE -22: Fundamental Frequenc i e s f o r the A s F , Anion 6 (cm ) Compound Ref . NOAsF, 0 693 582* 695 385 379,370 94 NOJVsF-z o 693 582* 690 385 380,370 94 N 2 F 3 A s F 6 690 583* 690 380 376,370 94 N_FAsF, z o 688 583* :715 - 375 99,100 NF.AsF 4 6 687 581* 709 406 378 98 ONF„AsF, z 0 689 584* 692 373 378,372 94 KAsF, D 692 580 698 382 375 THIS WORK C l O J V s F , Z D 685* 572* 725* 382 372* THIS WORK C l F J V s F , z o 693 603,544* 688 383 382,372 THIS WORK * denotes a v i b r a t i o n found both i n the IR and-Raman spectrum 110 382 and 372 cm 1 , but the 382 cm 1 a b s o r p t i o n may s o l e l y be long to the bending mode o f C I F ^ * - The weak a b s o r p t i o n band i n the i n f r a r e d spectrum at 310 cm 1 i s ass igned to the combinat ion band - v^. The band at 520 cm 1 as w e l l as bands at 1290 and 1045 cm 1 i n both the IR and Raman s p e c t r a are due to i m p u r i t i e s o f ClO^AsF^ . Weak bands which can be a t t r i b u t e d to C l O ^ * i m p u r i t i e s are found i n both the s p e c t r a o f ClO^AsF^ and ClO^SbF^, and presumably a r i s e from h y d r o l y s i s or g l a s s i n t e r a c t i o n s . Assignment o f the v i b r a t i o n a l f r e q u e n c i e s f o r the SbF^' group i n C l F _ S b F . and BrF„SbF, i s more d i f f i c u l t due to the c o m p l e x i t y 2 6 2 6 r J o f the s p e c t r a . In both the I . R . and Raman s p e c t r a , f a r more l i n e s are observed than expected f o r an an ion of o c t a h e d r a l symmetry. Before a t t e m p t i n g an a n a l y s i s o f the s p e c t r a , i t i s u s e f u l to examine the known c r y s t a l s t r u c t u r e o f BrF2SbF^ r e p o r t e d by Edwards 137 and Jones . Some o f t h e i r r e s u l t s are reproduced i n F i g u r e 22. The s t r u c t u r e o f BrF^SbF^ c o n s i s t s o f p o l y m e r i c c o i l e d chains w i t h 2 molecules i n the c h a i n per u n i t c e l l . Each SbF,. u n i t i s d i s t o r t e d o by c i s - f l u o r i n e b r i d g i n g to two bromine atoms r e s u l t i n g i n the l o w e r i n g o f the an ion symmetry from 0^ to At the same t i m e , two SbF^ u n i t s are coupled by a s i n g l e BrF2 u n i t r e s u l t i n g i n a d i s t o r t e d square p l a n a r c o o r d i n a t i o n f o r bromine. While the d i f f e r e n c e i n the Br -F t e r m i n a l and b r i d g i n g d i s t a n c e s i s l a r g e (0.60 A ) , the d i f f e r e n c e i n the same f o r Sb-F i s s m a l l (0.07 A ) , sugges t ing t h a t BrF^SbF^ remains e s s e n t i a l l y an i o n i c s t r u c t u r e d u r i n g the presence o f f l u o r i n e b r i d g i n g . FIGURE 22: Crystal Structure of B A . J . Edwards and G.R. Oones G. Chem. Soc. (A) 1467 (1969) Fz S b ! | Bond ang les ( ° ) R 4 ) - S b - F ( 4 1 ) = 9 3 F ( 3 ) - S b — F ( 3 ' ) = 1 7 4 F — B r — F = 9 3 . 5 o Interatomic d is tances ( A ) S b - F ( 1 ) = 1 . 9 1 S b — F ( 4 ) = 1 . 8 3 B r — F(1 ) = 2 . 2 9 B r — F ( 2 ) = 1 . 6 9 112 When Lta^SbF^. i s d i s s o l v e d i n B r F ^ , these b r i d g e s are broken and d i s c r e t e ions are produced. I t i s i n t e r e s t i n g to note the analogy between L M ^ S b F ^ and the whi te c h l o r y l compounds which when d i s s o l v e d i n HSO^F produced r e d c h l o r y l c a t i o n s . The s a l i e n t f e a t u r e s o f the c r y s t a l s t r u c t u r e which may be used i n the i n t e r p r e t a t i o n o f the v i b r a t i o n a l s p e c t r a o f BrF^SbF^ are c o r r e l a t e d i n Table 23. The l o w e r i n g o f the symmetry o f the SbF,. 6 a n i o n from 0^ to C as a r e s u l t o f c i s - f l u o r i n e b r i d g i n g r e s u l t s i n the s p l i t t i n g o f a l l degenerate modes. In a d d i t i o n , the arrangement of BrF2SbF^ i n p o l y m e r i c c o i l s w i t h two molecules i n the same c h a i n per u n i t c e l l leads t o the o v e r a l l symmetry D^. The e f f e c t o f t h i s c o u p l i n g where the BrF group acts as a s p r i n g between two SbF 2 . 6 groups r e s u l t s i n t w i c e the number o f bands. Assignments f o r the an ion f r e q u e n c i e s i n both BrF2SbF^ and ClF2SbF^ are made i n Table 24, where the v i b r a t i o n a l frequency assignments f o r SbF^ i n KSbF^ and ClG^SbF^ are i n c l u d e d as a means o f comparison. In the case of BrF2SbF^, the bands o r i g i n a t i n g from the mode can be e x p l a i n e d as f o l l o w s : The mode i s s p l i t i n t o f o u r components, namely, A , B^, B2 and B^. The B modes, B^, and B^ are observed i n the i n f r a r e d spectrum at 535, 523 and 495 cm 1 r e s p e c t i v e l y , w h i l e the A mode i s i n f r a r e d i n a c t i v e . Only t h r e e o f the f o u r expected modes appear i n the Raman spectrum, 552 ( A ) , 523(B2) and 493 (B-r) cm ^ > a n d i t i s assumed t h a t the B band i n the Raman i s 3 1 obscured by the v e r y i n t e n s e band at 552 cm 113 TABLE 23 C o r r e l a t i o n diagram f o r the XF , spec ies Free molecule D i s t o r t e d molecule Molecu le i n c h a i n P o i n t group 0 C„ D • h 2v 2 V i b r a t i o n a l mode: V l A l g A l A + B 2 A A + B v„ E A 2 g B 2 B 3 + B l A A + B V 3 ( ° r V F l u B l B 3 + B l B 2 B 3 + B l • A A + B 5 2g A 2 A + B 2 B l B 3 + B l TABLE 24 Fundamental frequencies f o r the SbF A anion. Compound Method CM 5-SbF, 2 o IR Raman BrF„SbF, 2 6 IR Raman C£0 2SbF 6 IR Raman KSbF, o IR Raman Assignment: v i [V 660 678 680 680 661 v 2 IE g ] 582 596 542i 537* 552 535 523 523 495 493 592 586 588 575 677 647 644 604 673 641 663 638 720 706 670 649 640 655 265 267 265 270 269 270 290 292 283 282 285 284 270 270 305 308 288 288 294 278 The remain ing A modes o r i g i n a t i n g from and can be ass igned to the s t r o n g bands at 678 c m - 1 and 641 c m - 1 , i n the i n f r a r e d spectrum appears to be s p l i t i n t o three components at 673, 663 and 638 cm Lack o f r e s o l u t i o n , however, prevents the o b s e r v a t i o n of the c o u p l i n g e f f e c t f o r and a l s o f o r and i n which the l a t t e r i s s p l i t i n t o two components at 285 and 270 cm I t i s v e r y d i f f i c u l t t o a s s i g n the remain ing B modes due to the c l o s e l y spaced A modes and v ^ ( B r F 2 + ) at 706 cm * . Only a weak shoulder i s found at 690 cm ^ which i s t e n t a t i v e l y ass igned as o r i g i n a t i n g from v^. The above mentioned h i g h i n t e n s i t y o f the 706 cm ^ band suggests a c o u p l i n g between a l l the d i f f e r e n t A modes. I t should a l s o be mentioned t h a t c o u p l i n g w i l l l i k e w i s e a f f e c t the B r F 2 + v i b r a t i o n s and f o r the c h a i n modes, f o u r components f o r v 1 and V j are expected o f the type A , B 2 and B . The l a c k of r e s o l u t i o n i n the i n f r a r e d spectrum and the c l o s e l y spaced bands i n the Raman spectrum do not a l l o w a complete assignment beyond the p o i n t where the 706 cm 1 band i s a s s i g n e d as the A mode and the 715 cm" shoulder as B 2 or B^. I t may a l s o be p o s s i b l e tha t the shoulder at 690 cm * i s b e t t e r ass igned as B^ and b e l o n g i n g to B r F 2 + . The v i b r a t i o n a l s p e c t r a o f C l F ^ b F ^ are found to be r e l a t i v e l y s i m p l e . Here , v 2 ( E ) i s s p l i t i n t o two components A^ and B . The B 2 mode i s observed at 596 cm 1 i n the Raman and at 582 cm 1 i n the i n f r a r e d spectrum. The s p l i t t i n g o f the Raman a c t i v e A^ at 542 and 537 cm ^ i s i n t e r p r e t e d as caused by the c r y s t a l l i n e f i e l d . Three components o f are found at 604, 647 and 677 cm ^ i n the IR, the band at 647 cm ^ b e i n g a l s o weakly Raman a c t i v e . v^(SbF^) appears not t o be s p l i t and i s found at 662 cm ^. .116 The above mentioned s p l i t t i n g s suggest symmetry f o r the SbF^ group i n d i c a t i n g f l u o r i n e b r i d g e bonding over c i s f l u o r i n e atoms i n the SbF^ u n i t as found f o r BrF^SbF^. The apparent d i s s i m i l a r i t y between the v i b r a t i o n a l s p e c t r a f o r both compounds may be due to d i f f e r e n t c r y s t a l s t r u c t u r e s , or weaker b r i d g e b o n d i n g , p r e v e n t i n g the c o u p l i n g o f v i b r a t i o n s . 6 .3 .4 C o n c l u s i o n s and Summary. I t i s apparent that the an ion i n the complexes C l F ^ A s F ^ , ClF^SbF^ and BrF^SbF^ has l e s s than o c t a h e d r a l symmetry. The d i s t o r t i o n o f the an ion oc t ahedron , more obvious f o r hexaf luoroant imonates than f o r h e x a f l u o r o a r s e n a t e s , i s best e x p l a i n e d as due t o a n i o n - c a t i o n i n t e r a c t i o n which occurs v i a f l u o r i n e b r i d g e s . In g e n e r a l , there seems to be s u b s t a n t i a l i n t e r a c t i o n between the an ion and c a t i o n f o r _ A s F ^ and -SbF^ complexes of h e t e r o c a t i o n s of group 7A elements . Covalent i n t e r a c t i o n has a l s o been p o s t u l a t e d 142 by Peacock and co-workers f o r - A s F ^ and -SbF^ complexes c o n t a i n i n g 143 d i - f l u o r o - p h o s p h o r u s h e t e r o c a t i o n s and by G i l l e s p i e and co-workers f o r complexes w i t h h e t e r o c a t i o n s o f s u l p h u r . In c o n t r a s t to these h e t e r o c a t i o n s o f main group elements i n the 3rd and 4th p e r i o d s (Table 18) the h e t e r o c a t i o n s of n i t r o g e n i n the 2nd p e r i o d are r e p o r t e d to e x i s t as d i s c r e t e ions i n - A s F ^ and -SbF^ c o m p l e x e s . 1 ^ 117 C H A P T E R S E V E N BROMYL COMPOUNDS 7.1 INTRODUCTION The d i f f i c u l t y i n p r e p a r i n g compounds c o n t a i n i n g bromine-oxygen bonds i s w e l l known. The chemis t ry o f the r e p o r t e d bromine o x i d e s , 144-146 146-150 , . . . . 151 , D . , B r 2 0 , B r 0 2 , and polymers o f formulae , ( B r 2 0 r . J n and (Br^Og)^ i s v i r t u a l l y u n s t u d i e d . A l l are o f v e r y low thermal s t a b i l i t y . U n t i l r e c e n t l y , the o n l y s t a b l e spec ies c o n t a i n i n g s o l e l y bromine and oxygen had been the bromate a n i o n , BrO^ . In the p a s t , attempts to prepare the perbromate anion have 152 f a i l e d . The n o n - e x i s t e n c e o f BrO^ was e x p l a i n e d by Urch as due to the absence o f good TT bonding between the 2p o r b i t a l s o f oxygen and 4d o r b i t a l s o f bromine. In s t r i k i n g c o n t r a s t t o t h e o r e t i c a l p r e d i c t i o n s , however, Appelmann ^ 3 has r e c e n t l y prepared perbromic a c i d , HBrO^, i n s o l u t i o n and potass ium perbromate, KBrO^, a s o l i d s t a b l e up to 280°C. Perbromyl f l u o r i d e , BrO^F, has a l s o been s y n t h e s i z e d 1 ^ ' and, on the b a s i s o f v i b r a t i o n a l s p e c t r a , appears to have a molecu lar s t r u c t u r e s i m i l a r to ClO^F w i t h C symmetry. T h i s work r e p o r t s the attempts to prepare bromyl f l u o r o s u l p h a t e , B r O ^ O ^ F , and to i n v e s t i g a t e the e x i s t e n c e o f the bromyl c a t i o n , B r 0 2 + . The o n l y known B r 0 2 ~ d e r i v a t i v e s F B r O ^ ^ f ' 1 * ' 9 and B r O ^ O , , 1 ^ are o f very l i m i t e d thermal s t a b i l i t y , be ing comparable t o the bromine o x i d e s . 7.2 EXPERIMENTAL An excess of S „ 0 , F . was d i s t i l l e d i n vacuo on to 6.503 mmoles z 6 z of KBrOg- Upon warming to 0 ° C , the r e a c t i o n proceeded moderately f a s t w i t h the f o r m a t i o n of a b r i g h t orange i n t e r m e d i a t e . The r e a c t i o n mixture was kept at 0°C. u n t i l oxygen e v o l u t i o n has ceased. A f t e r removal of the oxygen and the excess ^ 2 0 ^ ^ by pumping, 6.50 mmoles o f KBr(0S02F)^ were o b t a i n e d . A decomposi t ion p o i n t o f 170°C. was found. The sample was ana lysed f o r bromine a f t e r h y d r o l y s i s . A second run performed at room temperature l e d to i m p u r i t i e s o f B r ( S 0 3 F ) 3 and KS0 3 F i n the main product which was aga in K B r ( O S 0 2 F ) 4 . These i m p u r i t i e s presumably arose from the s l i g h t decomposi t ion o f KBr(OS02F)^ due to the e x o t h e r m i c i t y of the r e a c t i o n . B r ( S 0 3 F ) 3 was removed from the product by e x t r a c t i o n w i t h 8 2 0 ^ 2 and i d e n t i f i e d by a n a l y s i s ; KS0 3 F was de tec ted i n a Raman spectrum o f the p r o d u c t . A t h i r d r u n was made at -40°C. over a p e r i o d o f s e v e r a l h o u r s . The removal of $ 2 0 ^ 2 at -40°C. l e f t an orange-red s o l i d . On warming to h i g h e r temperatures , the s o l i d decomposed w i t h the l i b e r a t i o n of O2 and Br2• The r e s i d u a l s o l i d , however, was found t o c o n t a i n l a r g e amounts o f unreacted KBrOy The absence of $ 2 0 ^ 2 i n the r e s i d u a l p e r o x i d e c o l l e c t e d from 19 a l l r e a c t i o n runs was i n d i c a t e d by F.';NMR and i n f r a r e d s p e c t r a . The r e s i d u a l S„0^F„ was o f t e n c o l o u r e d orange due to v e r y s m a l l z 6 z amounts o f B r S 0 3 F . T h i s orange c o l o u r disappeared on s t a n d i n g as BrS0 3 F was o x i d i z e d t o B r ( S 0 3 F ) 3 -Attempts to s tudy the KBrO^ - ^ O ^ F , ^ """n ^ • L U o r o s u - L P n u r i c a c i d were u n s u c c e s s f u l , as KBrO^ alone r e a c t s r a t h e r v i o l e n t l y w i t h HSO^F t o produce KSO^F, B r 2 and 0^. 7.3 DISCUSSION The r e a c t i o n s o f S o 0 , F o w i t h KC10 7 and KI0„ (chapter 9) r e s u l t Z O Z J 6 i n the f o r m a t i o n o f ClC^SO^F and IO^SO^F r e s p e c t i v e l y . By analogy to these r e a c t i o n s , i t was hoped to prepare BrO^SO^F through the r e a c t i o n o f S^O^F'2 w i t h KBrO^. However, t h i s r e a c t i o n proceeds to the f o r m a t i o n o f KBr(OSO^F)^. The net r e a c t i o n i s best d e s c r i b e d a s : K B r 0 3 + 2 S 2 0 6 F 2 *• K B r ( 0 S 0 2 F ) 4 + 3 / 2 . 0 2 I t seems f e a s i b l e t h a t the observed i n t e r m e d i a t e i s BrC^SO^F, expected to be t h e r m a l l y u n s t a b l e i n accordance w i t h the i n s t a b i l i t y o f known bromyl compounds. A p o s s i b l e r e a c t i o n sequence i n agreement w i t h exper imenta l o b s e r v a t i o n s i s : KBrO„ + S o 0 , F „ * KSO-F + Br0_S0„F + 1/2 0_ o z o z J Z J Z Orange B r 0 2 S 0 3 F * 1/2 B r 2 + 0 2 + 1/2 1/2 Br„ + 1/2 S o 0 , F _ • BrS0_F Z Z o Z o BrS0 3 F + S 2 0 6 F 2 • B r ( S 0 3 F ) 3 B r ( S 0 3 F ) 3 + KS0 3 F »• K B r C S 0 3 F ) 4 120 161 I t i s i n t e r e s t i n g to note t h a t the r e a c t i o n of w i t h KBrO^ i s analogous to the KBrO^ - S^O^F^ system, and at room temperature proceeds to the f o r m a t i o n o f KBrF^ . A l s o , the p r e p a r a t i o n o f ClO^F from KCIO^ and BrF^ i s not analogous to the r e a c t i o n of BrF^ and 162 KBrO^; i n l i e u o f Br02F, KBrF^ i s produced a long w i t h Br^ and 0^ In e x p l o r i n g the p o s s i b i l i t y o f p r e p a r i n g Br02S0 3 F, i t i s u s e f u l to examine the p r e p a r a t o r y routes to Br02F. The f i r s t s u c c e s s f u l / p r e p a r a t i o n o f Br02F 1 ^ , 1 5 9 i n v o i v e c j the r e a c t i o n o f F2 w i t h Br02 at - 5 0 ° C . : C 5 F 1 2 B r 0 9 + 1/2 F + BrO F 1 1 -50°C. 1 Subsequent p r e p a r a t i o n s invoked the use o f BrF,. as a f l u o r i n a t i n g agent : -61°C. K B r 0 3 + B r F 5 y KBrF^ + B r 0 2 F + 1/2 0 2 and B r F 5 + 2 B r 2 + 10 0 3 + 5Br0 2 F + 10 0 2 A p o s s i b l e route to the s y n t h e s i s o f Br02S0 3 F might be the r e a c t i o n o f B r 0 2 and S 2 0 6 F 2 at -40°C. In v iew o f the r e s u l t s o f the s tudy o f the K B r 0 3 - S 2 0 6 F 2 r e a c t i o n , i t i s h i g h l y p o s s i b l e that B r 0 2 S 0 3 F i s u n s t a b l e above temperatures o f -40°C. S t r u c t u r a l s t u d i e s s e e k i n g the e x i s t e n c e of the B r 0 2 + c a t i o n and employing the techniques used i n Chapter 3 ( c o n d u c t i v i t y s t u d i e s e t c . ) would be v e r y d i f f i c u l t indeed;. 121 158 159 I t i s r e p o r t e d tha t bromyl f luorocomplexes are not obta ined ' from the r e a c t i o n o f Br0 2 F and BF^, AsF,. or SbF,.. T h i s p r e c l u d e s the p o s s i b i l i t y o f s t u d y i n g the B r 0 2 + c a t i o n i n p o l y f l u o r o a n i o n complexes. While the KBrO„ - S „ 0 , F . r e a c t i o n i s u n s u c c e s s f u l i n s o f a r as i t o Z o Z does not l e a d to bromyl f l u o r o s u l p h a t e as the f i n a l p r o d u c t , i t does p r o v i d e a convenient route to the s y n t h e s i s o f K[Br (OSC^F)^] . • The p r e v i o u s l y r e p o r t e d p r e p a r a t i o n i n v o l v i n g the r e a c t i o n o f KBr and 75 S 2 0 ^ F 2 r e q u i r e s a r e a c t i o n t ime o f s e v e r a l days and h e a t i n g to 50°C. As no s t r u c t u r a l i n f o r m a t i o n was a v a i l a b l e on the complex K[Br (OSC^F)^ ] , i t became i n t e r e s t i n g to o b t a i n i t s Raman spectrum and the s p e c t r a o f a number o f r e l a t e d compounds. The r e s u l t s o f these s t u d i e s are d e s c r i b e d i n the next c h a p t e r . 122 C H A P T E R E I G H T RAMAN STUDIES OF B r ( S 0 3 F ) 3 , ICSC>3F)3 AND THE ANIONS [ B r ( S 0 3 F ) 4 ] ~ AND { U S O ^ ] ' 8.1 INTRODUCTION The r e a c t i o n o f bromine and i o d i n e w i t h excess S~0,F„ has been / D 2 found to y i e l d the t r i s - f l u o r o s u l p h a t e compounds Br(SC> 3F) 3 and 163 I(SO F ) , r e s p e c t i v e l y . Under s i m i l a r c o n d i t i o n s , KBr and KI 3  J3 75 have been found to g ive complex s a l t s o f the composi t ion K [ B r ( S 0 3 F ) 4 ] and K [ I ( S 0 3 F ) 4 ] r e s p e c t i v e l y . Subsequent s t u d i e s 4 3 ' 1 ^ 4 > ' ' " ^ w i t h the t r i s - f l u o r o s u l p h a t e s have y i e l d e d some i n f o r m a t i o n on t h e i r chemical and p h y s i c a l p r o p e r t i e s as w e l l as t h e i r s o l u t i o n .behavior i n HSOjF. However, no s t r u c t u r a l i n f o r m a t i o n on any of these compounds has yet been r e p o r t e d . A convenient route t o the s y n t h e s i s o f K[Br ( S 0 3 F ) 4 ] was found and d e s c r i b e d i n the p r e v i o u s chapter . I t i s the o b j e c t o f t h i s chapter t o i n v e s t i g a t e the s t r u c t u r e o f K [ B r ( S 0 3 F ) 4 ] by means of l a s e r Raman s p e c t r o s c o p y , and a l s o the s t r u c t u r e s o f the r e l a t e d compound K [ I ( S 0 3 F ) 4 ] and the t r i s - f l u o r o s u l p h a t e s B r ( S 0 3 F ) 3 and I ( S 0 3 F ) 3 . The h i g h r e a c t i v i t y o f these compounds has prevented i n f r a r e d s t u d i e s so f a r . By analogy to the s q u a r e - p l a n a r anions I C l ^ and BrF^ 167,168 the complex anions [ B r ( S 0 3 F ) 4 ] ~ and [ I ( S 0 3 F ) 4 ] are l i k e l y to have a s q u a r e - p l a n a r c o n f i g u r a t i o n . The most f e a s i b l e s t r u c t u r a l models f o r the t r i s - f l u o r o s u l p h a t e s are p r o v i d e d by analogues from among the i n t e r h a l o g e n compounds o f the A B 3 t y p e : (a) the T-shaped monomeric molecule as found f o r B r F ^ * ^ and C I V ^ ® . (b) the f l u o r o s u l p h a t e 172 b r i d g e d dimer or p o s s i b l y polymer s i m i l a r to the I2^1^ s t r u c t u r e . 19 The f a c t t h a t the F NMR spectrum o f the melt or the s o l u t i o n i n ^2^6^2^^ shows o n l y a s i n g l e l i n e f o r both t r i s - f l u o r o s u l p h a t e s might imply tha t n e i t h e r model i s s a t i s f i e d , but r a p i d i n t e r m o l e c u l a r or i n t r a m o l e c u l a r exchange i s a d e f i n i t e p o s s i b i l i t y . 8.2 EXPERIMENTAL The complex K [ B r ( S 0 3 F ) 4 J was prepared from the r e a c t i o n o f K B r 0 3 and $2^6^2 a s d e s c r i b e d i n the l a s t ; The r e a c t i o n was performed at 0°C. to a v o i d i m p u r i t i e s o f KSOjF and B r ( S 0 3 F ) 3 i n the p r o d u c t . The sample o f K [ I ( S 0 3 F ) 4 ] was obta ined from M r . S . P . L . Jones , whose a s s i s t a n c e i n t h i s p r o j e c t , i s g r a t e f u l l y acknowledged. B r ( S 0 , F ) „ was obta ined from the r e a c t i o n o f BrS0„F and S_0,F„ •5 6 o Z 6 Z 163 and I f S 0 _ F ) „ , from the r e a c t i o n o f I„ w i t h S„0 ,F„ . Sublimed o o Z Z o Z a n a l y t i c a l grade was s u p p l i e d by B . D . H . K B r F 4 was prepared by the r e a c t i o n o f KC10 3 and B r F 3 as a c c o r d i n g 3 to Woolf , as a byproduct i n the s y n t h e s i s o f C l O ^ F . 124 8.3 DISCUSSION 8 .3 .1 R e s u l t s The Raman s p e c t r a o f K [ B r ( S 0 3 F ) 4 J and K [ I ( S 0 3 F ) 4 J are l i s t e d i n Table 25, t o g e t h e r w i t h the es t imated i n t e n s i t i e s and t e n t a t i v e assignments . The s p e c t r a f o r B r ( S 0 3 F ) 3 and I ( S 0 3 F ) 3 are l i s t e d i n Table 26. Approximate p o l a r i s a t i o n r a t i o s f o r the most i n t e n s e peaks o f i o d i n e t r i s - f l u o r o s u l p h a t e were a l s o o b t a i n e d s i n c e the spectrum was obta ined f o r the supercooled m e l t . A l l f o u r compounds were found to g ive w e l l r e s o l v e d s p e c t r a at r a t h e r low s e n s i t i v i t i e s . The Raman s p e c t r a o f K [ I ( S 0 3 F ) 4 J , K [ B r ( S 0 3 F ) 4 J and B r ( S 0 3 F ) 3 are shown i n F i g u r e 23. A l l attempts to o b t a i n w e l l r e s o l v e d i n f r a r e d s p e c t r a by a v o i d i n g window a t t a c k d i d not l e a d t o s a t i s f a c t o r y r e s u l t s . 8 .3 .2 K [ B r ( S 0 3 F ) 4 ] and K [ I ( S 0 3 F ) 4 J The Raman s p e c t r a o f K [ B r ( S 0 3 F ) 4 J and K { I C S 0 3 F ) 4 J are v e r y s i m i l a r , i n d i c a t i n g s t r u c t u r a l l y r e l a t e d compounds. The f a c t t h a t o n l y three v i b r a t i o n s are found i n the su lphur-oxygen s t r e t c h i n g frequency r e g i o n o f 1500 cm 1 to 900 cm 1 suggest tha t a l l f o u r f l u o r o s u l p h a t e groups are i d e n t i c a l . Some s m a l l s p l i t t i n g s o r :i the presence o f shoulders c o u l d be due to f a c t o r group s p l i t t i n g . A l s o , a s i n g l e band a t t r i b u t e d to the S-F s t r e t c h i n g v i b r a t i o n i s found at about 835 cm 1 . TABLE 25: V i b r a t i o n a l Frequencies f o r the [ H a l ( S 0 3 F ) 4 ] A n i o n K B r ( S 0 3 F ) 4 K I ( S 0 3 F ) 4 Assignment 1424 mw 1409 m v y A ' 1407 mw 1237 s 1250 s v 1 A ' 1220 w,sh 1222 w,sh 970 m,s 1002 m v 4 A ' 834 m 837 m \>_ A ' 615 vs 620 vs v 3 A* 578 ms 582 m v 5 A ' 553 w 554 m v g A " 447 s 442 s V j H a l - 0 A 406 w 407 w v Q A " 399 w 397 w \>4Hal-0 B 2 g 270 s 260s \>2Hal-0 B 239 vs 239 vs v f e A ' 126 TABLE 26: V i b r a t i o n a l Frequencies f o r B r ( S 0 3 F ) 3 and I ( S 0 3 F ) 3 Br (SO^F) 3 JZ •"•""3 ^ I ( s Assignment Termina l Br idg ing 1490 mw 1469 m v ? 1467 w 1372 m 1381 mw v , 1 1356 mw,sh 1241 s 1233 s , p ( 0 . 3 4 ) v 1230 m,sh 1168 mw 1182 w,sh 645 v s , b r 642 v s , p ( 0 . 4 9 ) 612 vs 619 p(0 .48) v 3 '1 - 7 ' 1122 m 1076 w,sh 1050 m,p(0.62) v 4 ' 1010 m 963 m,p(0.29) v. 1015 m 859 m 869 p(0 .40) v 2 ' 827 vw 826 w 801 m 800 m v 2 721 ms 700 w v 5 * v 3 583 ms 580 m,sh v c 563 m 556 m Vg' 551 vw 540 w 540 m,sh v Q . / c o n t i n u e d 127 TABLE 26 . . . c o n t i n u e d B r ( S 0 3 F ) 3 I t S 0 3 F ) 3 Assignment Termina l B r i d g i n g 455 s 457 s , p ( 0 . 3 9 ) v 1 H a l - 0 430 m 430 w,sh V 9 408 mw 412 m V 9 384 mw,sh 386 mw,sh v 4 H a l - 0 303 vs 290 v s , p ( 0 . 4 6 ) V 6 276 vs 270 s , s h v 2 H a l - 0 225 ms 206 m 181 m V 6 148 m p = p o l a r i z e d , sh = s h o u l d e r , w = weak, m = medium, s = s t r o n g , br = broad vs = v e r y s t r o n g , vw = very weak K [ B r ( S 0 3 F ) J i 1 1 1 1 1 1 1 1 1 1 1 1 1 1 i 1600 1400 1200 100Q 800 600 400 200 WAVENUMBER [cm-'] FIGURE 23 129 The observed f r e q u e n c i e s d i f f e r markedly i n t o t a l number and - 173 85 p o s i t i o n o f the a b s o r p t i o n bands from tha t o f a SO^F i o n ' Covalent i n t e r a c t i o n w i l l i n c r e a s e the number o f v i b r a t i o n a l modes from 6 f o r the SO^F i o n w i t h symmetry to 9 f o r the cova lent monodentate or b i d e n t a t e S0_F group, both w i t h C symmetry by the removal o f degeneracy f o r the 3 E modes. A l l v i b r a t i o n s f o r C ^ v and C s symmetry w i l l be IR and Raman a c t i v e . The change i n band p o s i t i o n s i s i l l u s t r a t e d n i c e l y f o r the 174 175 monodentate cova lent compounds by ^2^s^2 a n < ^ r e l a t e d compounds ' , where bands at about 1500 and 1250 cm 1 are f o u n d , i n d i c a t i n g a l a r g e r degree o f m u l t i p l e bonding f o r the remaining t e r m i n a l su lphur-oxygen bonds. A c o r r e l a t i o n diagram, where a t e n t a t i v e assignment f o r the [HalCSO^F)^] i o n i s made i s shown i n Table 27. The degree o f s p l i t t i n g of the E..modes, best r e c o g n i z e d f o r the S-0 s t r e t c h i n g modes, w i l l i n d i c a t e the degree o f covalency i n the halogen-oxygen bond. T h i s i s w e l l i l l u s t r a t e d when the [BrCSO^F)^] an ion i s compared to the [ICSO^F)^] a n i o n where a s l i g h t l y s m a l l e r s p l i t t i n g f o r the l a t t e r i n d i c a t e s a s l i g h t l y more p o l a r bond. The v i b r a t i o n a l f r e q u e n c i e s o f the anions can be i n t e r p r e t e d as b e i n g due t o a c o v a l e n t l y bonded monodentate SO^F group. The remaining bands at about 445, 395 and 260 cm 1 are most p r o b a b l y due to h a l o g e n -oxygen v i b r a t i o n s and f o r the bromine s p e c i e s , occur at s l i g h t l y h i g h e r f requenc ies than the i o d i n e s p e c i e s , as expected from the d i f f e r e n c e i n masses. TABLE 27: CORRELATION DIAGRAM OF THE S0 3 F GROUP S 0 3 F " ION ( C 3 v Symmetry): V i b r a t i o n a l W W W V 4 ( E ) V 5 ^ V E ) modes V S0 3 sym V SF S0 3sym V S0 3 asym SO a^sym rock Example: group: V l CA« ) v^A') v^A') v^A') v y ( A " ) v 5 ( A * ) v g ( A " ) v^A') v g ( A n ) Example: [ B r ( 0 S 0 2 F ) 4 r ( cm _ 1 ) 1237,1220 834 615 970 1424 578 553 239 406 1407 0* o 131 The number o f v i b r a t i o n a l modes agrees w e l l w i t h a square p l a n a r _ 167 168 c o n f i g u r a t i o n , a l r e a d y suggested by the s t r u c t u r e o f the BrF^ an ion ' which i s found t o have symmetry. To o b t a i n some i n d i c a t i o n o f the approximate p o s i t i o n o f the v i b r a t i o n a l bands i n the f l u o r o s u l p h a t e compounds, the Raman spectrum o f KBrF^ was recorded which shows a p a t t e r n o f three a b s o r p t i o n l i n e s at 532 ( s ) , 457 (ms) and 246 (m) cm ^. Due to the thermal i n s t a b i l i t y o f bromine-oxygen bonds, no o ther comparable assignments c o u l d be found i n the l i t e r a t u r e . The same l a c k o f comparable systems i s found f o r the [IfSO^F)^] a n i o n . A l l v i b r a t i o n a l s t u d i e s on t e r v a l e n t i o d i n e - o x y g e n compounds 176 are concerned w i t h i n f r a r e d s p e c t r a o f i o d o s y l d e r i v a t i v e s where the i o d i n e - o x y g e n bond appears to have a p p r e c i a b l e m u l t i p l e bond c h a r a c t e r . 8 .3 .3 B r ( S 0 3 F ) 3 and I ( S 0 3 F ) 3 The Raman s p e c t r a o f both t r i s - f l u o r o s u l p h a t e s i n d i c a t e s t r u c t u r a l s i m i l a r i t y but are f a r more complex than the a n i o n i c s p e c i e s . The v i b r a t i o n a l f r e q u e n c i e s are l i s t e d i n Table 26, together w i t h a t e n t a t i v e assignment . For both compounds, a - . to ta l number o f 6 v i b r a t i o n a l modes i s found i n the su lphur-oxygen s t r e t c h i n g r e g i o n and two s t r o n g bands become a s s i g n a b l e to s u l p h u r - f l u o r i n e s t r e t c h i n g . A s i m i l a r d u p l i c a t i o n o f v i b r a t i o n s i s found i n the lower range o f the bending and r o c k i n g modes. Bands p r e v i o u s l y ass igned t o ha logen-oxygen are found aga in w i t h comparable i n t e n s i t y i n the same p l a c e as the a n i o n i c s p e c i e s . 132 The obvious e x p l a n a t i o n f o r the m u l t i t u d e o f bands i s tha t two types o f f l u o r o s u l p h a t e groups are present i n both compounds. One set o f bands i s i n approx imate ly the same p l a c e as found f o r the t e t r a -f l u o r o s u l p h a t o h a l a t e ( I I I ) a n i o n s , even though the asymmetric S-0 s t r e t c h i n g frequency appears at a h i g h e r wavenumber. A g a i n , the s h i f t i s l a r g e r f o r the bromine compound, i n d i c a t i n g a h i g h e r degree o f covalency as found b e f o r e . The second set o f 9 v i b r a t i o n a l modes c o u l d p o s s i b l y be due to a second c o v a l e n t l y bonded monodentate SO^F groups as expected f o r a T-shaped molecule or due t o a b i d e n t a t e b r i d g i n g group. The l a t t e r a l t e r n a t i v e i s chosen f o r the f o l l o w i n g r e a s o n s : (1) The halogen-oxygen f r e q u e n c i e s would be found i n a d i f f e r e n t p l a c e and a t o t a l number o f s i x Raman a c t i v e bands would be expected f o r the C 2 model w i t h three i n the s t r e t c h i n g range. (2) Only minor p o s i t i o n a l changes f o r a second t e r m i n a l SO^F group would be expected . (3) F i n a l l y , f a i r agreement i s found w i t h the b r i d g i n g f l u o r o s u l p h a t e 177 group i n the hexacoordinated compounds SntSO^F)^ and C ^ S n f S O ^ F ^ I t seems then tha t the two halogen t r i s f l u o r o s u l p h a t e s are not monomeric i n the s o l i d s t a t e . The most l i k e l y models f o r the s t r u c t u r e are a c h a i n - t y p e polymer or a b r i d g e d d imer , both w i t h a square p l a n a r c o n f i g u r a t i o n f o r the h a l o g e n . Even though the observed s o l u b i l i t y i n s o l v e n t s such as S20^F^ and ^2^6^2 P 0 ^ n t s t o l ° w molecu lar weight s p e c i e s , no c l e a r d i s t i n c t i o n can be made at t h i s p o i n t . The occurrence o f many d o u b l e t s i n the spectrum o f BrCSO^F)^ i s best e x p l a i n e d by assuming d i f f e r e n t conformations o f both the t e r m i n a l and the b r i d g i n g group or p o s s i b l y by f a c t o r group s p l i t t i n g . Only s i n g l e t s are observed f o r most corresponding bands o f I.'GSOjF) present as a m e l t . A l l assignments f o r the two f l u o r o s u l p h a t e groups are t e n t a t i v e p a r t i c u l a r l y i n the lower frequency range . The h i g h e r frequency S-F v i b r a t i o n i s a ss igned to the b r i d g i n g SO^F group, 177 -1 based on the C ^ S n C S O ^ F ^ example. V i b r a t i o n a l modes at 200 cm and lower c o u l d p o s s i b l y be due t o l a t t i c e modes. 134 C H A P T E R N I N E IODYL COMPOUNDS 9.1 INTRODUCTION A number o f i n o r g a n i c compounds c o n t a i n i n g the I O 2 - group have been r e p o r t e d over the y e a r s . They i n c l u d e i o d y l f l u o r i d e , 10 . ^ F ^ - ^ ' ^ , and i t s r e a c t i o n products w i t h the Lewis a c i d s , BF^ and AsF^'''"'", where + - 11 199 the l a t t e r compound i s commonly regarded as IO2 AsF^ ' and not A s F 4 + I 0 2 F 2 a S s u S S e s t e d p r e v i o u s l y 2 ^ . The o ther known i o d y l compounds can be regarded as s a l t s o f s t r o n g oxyac ids and i n c l u d e the compounds 201 202 1R9 707, ( I O ^ ^ O ^ , I 0 2 S 0 3 F , I0 2 C F 3C0 2 , (I0 2) 2Se0 4 and ( I O ^ H S e O I o d y l compounds are whi te or p a l e y e l l o w s o l i d s , which were 204 4 p r e v i o u s l y thought to c o n t a i n the iodonium c a t i o n , I 0 2 + . The e x i s t e n c e 205 o f t h i s c a t i o n has been p o s t u l a t e d as a r e a c t i o n i n t e r m e d i a t e However, no evidence has been found f o r the e x i s t e n c e o f I 0 2 + i n the 206 s u l p h u r i c a c i d s o l v e n t system . In a d d i t i o n , i n f r a r e d v i b r a t i o n a l 207 s p e c t r a o f the r e l a t e d i o d o s y l s a l t s (10) ,^0^ and ( I O ) 2 S e 0 4 have suggested the s t r u c t u r e s o f these compounds to c o n s i s t o f p o l y m e r i z e d 1-0 chains c r o s s - l i n k e d by the SO^ or SeO^ groups present as e i t h e r d i s c r e t e anions or f o u r - c o v a l e n t g r o u p i n g s . As a consequence, s i m i l a r r i r +1, • A i n- v. -n- ,203,204,206 , + f o r m u l a t i o n s f o r the i o d y l s a l t s have r e s u l t e d , but any s t r u c t u r a l p r o o f f o r the p o s t u l a t e d i o d i n e - o x y g e n b r i d g e d s t r u c t u r e s i s c l e a r l y l a c k i n g . Except f o r an incomplete i n f r a r e d spectrum of 199 208 I 0 2 A s F ^ , and a very b r i e f r e p o r t on the i n f r a r e d spectrum o f I0,,F , no d e t a i l e d v i b r a t i o n a l s p e c t r a o f the i o d y l compounds has been r e p o r t e d . 135 I t i s t h e r e f o r e the purpose o f t h i s chapter t o apply i n f r a r e d and l a s e r Raman spectroscopy to a s y s t e m a t i c s tudy o f the i o d y l compounds, I 0 2 F , I 0 2 A s F 6 and I 0 2 S 0 3 F . I t should be p o s s i b l e to d e c i d e , whether a common s t r u c t u r e o f the i o d y l group i s found i n a l l these compounds and whether such a group i s p o l y m e r i z e d v i a d i s c r e t e I - O - I b r i d g e s or e x i s t s as the c a t i o n w i t h m u l t i p l e bonding from oxygen t o i o d i n e , analogous to the f o r m a l l y r e l a t e d ch loronium c a t i o n , C 1 0 2 + . A n i o n - c a t i o n i n t e r a c t i o n , as found i n the c h l o r y l compounds d i s c u s s e d i n Chapter 4 , i s a l s o a d i s t i n c t p o s s i b i l i t y . I n c l u s i o n o f the r e l a t e d compounds lOF^ and K I 0 2 F 2 i n t h i s v i b r a t i o n a l s tudy should h e l p i n the i n t e r p r e t a t i o n s i n c e the X - r a y 209 210 c r y s t a l s t r u c t u r e s are r e p o r t e d f o r both compounds ' . No d e t a i l e d v i b r a t i o n a l s p e c t r a appear to have been r e p o r t e d f o r these compounds. S o l u t i o n s t u d i e s i n f l u o r o s u l p h u r i c a c i d were undertaken f o r three main reasons : 206 (1) The study by G i l l e s p i e and Sen ior uses i o d i c a c i d as the s o l e s o l u t e i n I-^SO^. A p o s s i b l e I 0 2 + c a t i o n , formed a c c o r d i n g t o the net e q u a t i o n ; : H I 0 3 + 2 H 2 S 0 4 = I 0 2 + + H 3 0 + + 2HS0 4 ~, would have t o c o e x i s t w i t h the H 3 0 + i o n . S o l u t i o n s t u d i e s o f s o l u t e s a l r e a d y c o n t a i n i n g the i o d y l group would a v o i d the f o r m a t i o n o f the H 3 0 + i o n and would present a b e t t e r chance to o b t a i n evidence f o r the I 0 2 + c a t i o n . I t i s i n t e r e s t i n g to note t h a t , i n ana logy , a s o l v a t e d ch loronium c a t i o n i s formed not by s o l v o l y s i s o f metal c h l o r a t e s a r c h l o r i c a c i d , but by c h l o r y l compounds as s o l u t e s ( c h a p t e r s 3 , 4 ) . (2) F l u o r o s u l p h u r i c a c i d i s a s t r o n g e r p r o t o n i c a c i d than H^SO^ and i s c l e a r l y b e t t e r s u i t e d f o r the s tudy o f such h i g h l y e l e c t r o p h i l i c 27 c a t i o n s as shown by many examples (3) The most i d e a l s o l u t e i n HSO^F, i o d y l f l u o r o s u l p h a t e , was f i r s t 189 r e p o r t e d to be i n s o l u b l e i n HSO^F . I t was found l a t e r d u r i n g the course o f t h i s r e s e a r c h tha t the compound d i s s o l v e s at room temperature i n HSO^F i n an extremely slow process over s e v e r a l days to g ive c l e a r s o l u t i o n s , concentra ted enough f o r c o n d u c t i v i t y s t u d i e s . F i n a l l y , the r e a c t i o n s o f S ^ ^ F , , w i t h KIO^ and KIO^ were i n v e s t i g a t e to see whether compounds c o n t a i n i n g the I C ^ - g r o u P o r ^®_<~ g r o u P would r e s u l t , or i f the f o r m a t i o n o f K I G ^ C S O ^ F ^ , analogous to K I 0 2 F 2 , would o c c u r . 9.2.1 EXPERIMENTAL 9 .2 .1 The P r e p a r a t i o n o f I02SC>3F I o d y l f l u o r o s u l p h a t e was prepared from the r e a c t i o n o f l 2 0 j - and 189 ^2^6 F2 a s a c c o r d i - n g t 0 Aubke et a l 9 .2 .2 The Reac t ion between KI0„ and S_0,F„ o z o z An excess o f S .CLF, , was d i s t i l l e d i n vacuo on to 9.67 mmoles o f z 6 z f i n e l y powdered KIG"3 (BDH) conta ined i n a r e a c t i o n v e s s e l w i t h a s t i r r i n g bar (F igure 1) c o o l e d at l i q u i d n i t r o g e n temperature . On warming to 2 5 ° C , a very slow r e a c t i o n o c c u r r e d w i t h the l i b e r a t i o n 137 of 0^. The r a t e o f r e a c t i o n was enhanced by r a i s i n g the temperature to 50°C. - h i g h e r temperatures r e s u l t e d i n decomposi t ion o f the product and a f t e r about 12 h o u r s , the e v o l u t i o n o f 0^ had ceased and the r e a c t i o n was complete . Removal o f the excess -^O^F2 ^-e^ D e h i n d a f l a k y p a l e y e l l o w s o l i d o f weight cor responding to a mixture of 9.65 mmoles o f both IC^SO^F and KSO^F. The presence o f these compounds i n l i e u o f K I C ^ ( S O ^ F ^ was r e v e a l e d by a Raman spectrum and x - r a y 19 powder p a t t e r n o f the p r o d u c t . Gaseous IR and F NMR s p e c t r a of the r e s i d u a l p e r o x i d e i n d i c a t e d the absence o f S20,-F2. 9 . 2 . 3 The R e a c t i o n between KIO, and S „ 0 , F n 4 2 o 2 An excess o f S o 0 , F _ was r e a c t e d w i t h 3.01 mmoles KIO. (BDH) Z o Z 4 under the same r e a c t i o n c o n d i t i o n s as i n s e c t i o n 9 . 2 . 2 . A g a i n , the r e a c t i o n proceeded very s l o w l y at room temperature w i t h the e v o l u t i o n o f 0^, w h i l e temperatures g r e a t e r than 60°C. r e s u l t e d i n the decomposi t ion o f the p r o d u c t . To complete the r e a c t i o n , h e a t i n g at 50°C. f o r 12 hours was r e q u i r e d . Removal o f the excess p e r o x i d e l e f t b e h i n d a f l a k y p a l e y e l l o w s o l i d resembl ing the product obta ined i n the KIO^ - ^2*^6^2 r e a c t i ° n - A Raman spectrum i n d i c a t e d the product to be a mixture o f IO^SO^F and KSO^F, w h i l e the weight change corresponded to 2.94 mmoles f o r each component. In each r u n , the weight change was found t o be l e s s than the t h e o r e t i c a l va lue due to the l o s s o f s m a l l 19 amounts o f IO2SO2F to the vacuum l i n e by s u b l i m a t i o n . F NMR and gaseous IR s p e c t r a o f the r e s i d u a l 520^p2 s n o w e d that 820,^2 was not formed i n t h i s r e a c t i o n . 138 9 .2 .4 The P r e p a r a t i o n o f KIO F 2 Potassium d i f l u o r o i o d a t e was prepared by the e v a p o r a t i o n o f a s o l u t i o n o f KIO^ i n 52% HF ( F i s h e r S c i e n t i f i c Co . ) as a c c o r d i n g to Helmholz and R o g e r s 2 1 ^ . 9 .2 .5 The P r e p a r a t i o n o f I 0 F 3 g IOF^ was prepared by the r e a c t i o n of ^ ^ 5 a n c * b o i l i n g I F 5 As the d e s c r i p t i o n o f the procedure r e p o r t e d i n t h e . l i t e r a t u r e i s r a t h e r g b r i e f , a d e t a i l e d account o f the p r e p a r a t i o n now f o l l o w s : I m p u r i t i e s o f i o d i n e and complexes o f I ^ + i n IF^ ( g i v i n g r i s e t o a b l u e - c o l o u r e d l i q u i d ) were removed by d i s t i l l i n g IF,, from the main c y l i n d e r (Matheson Co . ) i n t o a s torage t r a p c o n t a i n i n g about 10 g. o f mercury. A metal vacuum l i n e was used i n t h i s t r a n s f e r . A f t e r about 50 g. o f IFj- had c o l l e c t e d , the s torage t r a p was removed from the l i n e and shaken f o r s e v e r a l minutes to ensure complete r e d u c t i o n o f the i o d i n e and spec ies to I i n the form of the n o n v o l a t i l e s o l i d H g l 2 - The s torage t r a p was once aga in a t tached t o the metal l i n e . The g lass apparatus used f o r the p r e p a r a t i o n o f I0F^ i s i l l u s t r a t e d i n F i g u r e 24. About 1.5 g . o f f i n e l y powdered I 20,- > P r e v i ° u s l y heated f o r 6 hours at 100°C. i n vacuo, was admit ted t o the apparatus 'at the opening B. The v e s s e l was flame s e a l e d at C and at tached to the metal l i n e at A v i a a f l e x i b l e c o i l o f copper t u b i n g , t o a l l o w movement o f the apparatus w h i l e a t tached to the metal l i n e . About 30 g. o f the 139 Kontes Valve A B * Coarse F i l t e r v / E D FIGURE 24: Apparatus used f o r the p r e p a r a t i o n o f IOF^ p u r i f i e d IF^ was d i s t i l l e d from the mercury s torage t r a p on to the I^O,. conta ined i n the D compartment o f the evacuated r e a c t i o n v e s s e l . Dry a i r was then admit ted i n t o the system v i a a ?2®5 d r y i n g tube at tached to the vacuum m a n i f o l d . The e n t i r e r e a c t i o n v e s s e l was then immersed i n an o i l bath and heated u n t i l the IF,, began t o b o i l . A f t e r s e v e r a l minutes and constant shaking o f the v e s s e l , a l a r g e amount o f ^2^5 n a d d i s s o l v e d i n the c o l o u r l e s s l i q u i d . The hot s o l u t i o n was then pumped through the coarse f i l t e r i n t o compartment E , w h i l e the v e s s e l was t i p p e d sideways to a i d i n the t r a n s f e r . White n e e d l e -l i k e c r y s t a l s separated from the mother l i q u o r on c o o l i n g . The f i n a l product was o b t a i n e d by pumping o f f the excess IF,, at room temperature . 9 .2 .6 The P r e p a r a t i o n o f I 0 2 F I o d y l f l u o r i d e , I C ^ F , was prepared by the method o f A y n s l e y g et a l . by h e a t i n g I0F_ at 110°C. i n the presence o f dry a i r as a c c o r d i n g t o : 1 . 1 0 ? I 0 2 F + I F 5 + 140 The white s o l i d was heated at 110°C. under vacuum f o r a shor t p e r i o d o f time to e l i m i n a t e a l l t r a c e s of I F ^ . A l l attempts t o prepare i o d y l f l u o r i d e by the d i r e c t f l u o r i n a t i o n 19 of a s o l u t i o n o f i n anhydrous HF were u n s u c c e s s f u l . A t y p i c a l exper iment i s d e s c r i b e d as f o l l o w s : A q u a n t i t y o f 6.0 g . o f f i n e l y powdered and p u r i f i e d 1 w a s d i s s o l v e d i n 20 g . o f anhydrous HF (Matheson Co. ) conta ined i n a K e l - F t r a p . F l u o r i n e gas ( u n d i l u t e d ) was bubbled v i g o r o u s l y through the s o l u t i o n f o r a p e r i o d o f 27 hours at 25°C. (Moisture i s prevented from e n t e r i n g the t r a p by a l a r g e pressure o f f l u o r i n e which a l s o r e a c t s w i t h ^ 0 to convert i t to HF.) The f l o w o f f l u o r i n e was then h a l t e d and the K e l - F tube immediate ly a t tached t o the vacuum l i n e . The s o l v e n t was removed by pumping at 50°C. f o r s e v e r a l h o u r s . A Raman spectrum o f the product showed i t to c o n t a i n a mixture o f HIO^ and ^2^5 O N ^ * w n i l e a n analysis r e v e a l e d o n l y t r a c e amounts o f f l u o r i n e . As t h i s experiment was attempted s e v e r a l t imes under d i f f e r e n t r e a c t i o n c o n d i t i o n s and l e d to e i t h e r HlOg o r unreacted ^^c; i n e a c n i n s t a n c e , the o r i g i n a l l i t e r a t u r e r e p o r t must be regarded as h i g h l y q u e s t i o n a b l e . 9 . 2 . 7 The P r e p a r a t i o n o f I 0 2 A s F 6 I o d y l h e x a f l u o r o a r s e n a t e was prepared by the r e a c t i o n o f AsF^ and a s o l u t i o n o f IC^F i n anhydrous H F . ^ As the l i t e r a t u r e r e p o r t s o f t h i s p r e p a r a t i o n are r a t h e r b r i e f , the s y n t h e s i s o f IO^AST^ i s now d e s c r i b e d i n d e t a i l : 141 About 15 g. o f anhydrous HF was d i s t i l l e d through a metal vacuum l i n e i n t o a pre-weighed monel metal r e a c t i o n v e s s e l (F igure 2) c o n t a i n i n g 1.2 g . o f I 0 2 F coo led at - 1 9 6 ° C , f o l l o w e d s u c c e s s i v e l y by about 5 g . AsF , . . The r e a c t i o n v e s s e l was warmed to room temperature and then heated at 40°C. f o r two h o u r s . The anhydrous HF and excess AsF^ were then removed by pumping. The r e s u l t i n g product was a y e l l o w powder and was i d e n t i f i e d as IG^AsFg by a n a l y s i s f o r i o d i n e and the weight change. A s i m i l a r attempt to o b t a i n IO^AsF^ by the r e a c t i o n o f IC^F and A s F r wi thout the use o f HF as s o l v e n t r e s u l t e d i n a mixture o f IO^AsF. o 2 o and unreacted 9 .3 RESULTS AND DISCUSSION 9 .3 .1 The React ions o f S„CLF„ w i t h K I O , and KIO, 2 o 2 3 4 The r e a c t i o n o f KIO^ and S_®(^2 P r o c e e c * s s i o w l y a t room temperature to a mixture o f KSO^F and IO^SO^F as e s t a b l i s h e d by a Raman spectrum o f the p r o d u c t s . The r e a c t i o n , analogous to the KC10„ - S_0 ,F„ 6 2 o 2 r e a c t i o n , can be formula ted as : K I 0 3 + S 2 ° 6 F 2 ' K S 0 3 F + I 0 2 S 0 3 F + 1 / 2 °2 The r e a c t i o n o f KIO. w i t h S„0 ,F_ r e s u l t s i n the same products , and 4 2 o 2 proceeds as f o l l o w s : K I 0 4 + S 2 ° 6 F 2 " K S 0 3 F + I 0 2 S 0 3 F + °2 No evidence f o r the e x i s t e n c e of the complex K I 0 2 ( S 0 2 F ) 2 cou ld be found. 142 9 .3 .2 V i b r a t i o n a l Spec t ra o f I o d y l Compounds 9 . 3 . 2 . 1 R e s u l t s Wel l r e s o l v e d Raman s p e c t r a f o r the i o d i n e - o x y g e n compounds were o b t a i n e d i n a l l cases , except f o r I C ^ A s F ^ , where s t r o n g s c a t t e r i n g o f the l a s e r l i g h t o c c u r r e d . Due to the extreme r e a c t i v i t y o f lOF^ and IC^SO^F, s a t i s f a c t o r y IR s p e c t r a f o r these compounds c o u l d not be o b t a i n e d . The v i b r a t i o n a l f r e q u e n c i e s f o r lOF^ and 0 ( ^ 2 are l i s t e d i n Table 28, t o g e t h e r w i t h es t imated i n t e n s i t i e s and suggested assignments, and the Raman s p e c t r a o f lOF^ and 1(1(^2 are reproduced i n F i g u r e 25. The v i b r a t i o n a l f requenc ies f o r IC^F and IC^AsF^ toge ther w i t h crude assignments and es t imated i n t e n s i t i e s are conta ined i n Table 29. The Raman s p e c t r a o f IC^F and IC^SO^F are shown i n F i g u r e s 26 and 27, w h i l e the i n f r a r e d s p e c t r a o f IC^F and IC^AsFg are shown i n F i g u r e 28. 9 . 3 . 2 . 2 I 0 F 3 and I 0 2 F 2 ~ 209 - 210 The s t r u c t u r e s o f lOF^ and the 102^2 a r e known and t h e r e f o r e t h e i r v i b r a t i o n a l s p e c t r a should be h e l p f u l i n i n t e r p r e t i n g the s p e c t r a o f the i o d y l compounds. Both lOF^ and the 102^2 ~^on ^ n ^®2^2 a r e f ° u n c * t o n a v e r e l a t e d s t r u c t u r e s , d e r i v e d from 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 , w i t h a s t e r e o c h e m i c a l l y a c t i v e lone p a i r on the c e n t r a l atom, two f l u o r i n e atoms i n a x i a l p o s i t i o n s and the remain ing two atoms i n e q u a t o r i a l p o s i t i o n s . As i s g e n e r a l l y observed f o r t h i s bond t y p e , the e q u a t o r i a l 143 TABLE 28: V i b r a t i o n a l Spec t ra o f I 0 F 3 and K I 0 2 F I 0 F 3 K I 0 2 F 2 Observed Frequencies (cm Observed Frequencies (cm ) Raman Assignment Raman I .R Assignment 918 vw—. 907 w I o d i n e - 830 w,sh 855 844 " ] m J V I 0 2 asym 883 vs oxygen s t r e t c h 808 vs 816 VS -» I 0 o sym 862 w 805 vs J z 809 w ^ I 0 2 F 472 s 476 s V I F 716 w J Impur i ty 434 s 657 vs 550 vs V I - F eq. V I - F ax. 355 ms 345 m,sh 358 340 m,sh s 5 l 0 E 515 ms V I - F 324 s 322 m,sh 350 m -•I 220 ms ^ 2 rock 304 ms I Deformation j Bands 190 m,sh 196 ms 295 vw -J vw = v e r y weak, vs = very s t r o n g , ms = medium-strong, w = weak, s = s t r o n g , m = medium, sh = shoulder FIGURE 25: Raman Spec t ra o f IOF and 10 F Raman Spectra of IOF and IO F i l 1 1 1 1 1 1 1 10OO 800 600 400 200 145 bonds are s h o r t e r and s t r o n g e r than the a x i a l bonds. Both s t r u c t u r e s are d i s t o r t e d from the t r i g o n a ^ . p y r a m i d a l c o n f i g u r a t i o n ( as i n d i c a t e d by the bond angles) as a r e s u l t o f the i n f l u e n c e o f the non-bonding p a i r o f e l e c t r o n s . A l s o , s h o r t e r bonds are found i n lOF^ than f o r 1 0 ^ 2 , a l though a comparison i s d i f f i c u l t due t o the l a r g e e r r o r l i m i t s r e p o r t e d f o r the l a t t e r . The f a c t t h a t unequal i o d i n e -a x i a l f l u o r i n e bond d i s t a n c e s i n I0Fg are observed i s i n d i c a t i v e o f I . . . F i n t e r m o l e c u l a r i n t e r a c t i o n . Nine i n f r a r e d and Raman a c t i v e v i b r a t i o n s are expected f o r I0F w i t h C symmetry, w h i l e the I 0 ? F ion. , w i t h C„ symmetry, i s expected to have 9 Raman a c t i v e and 8 i n f r a r e d a c t i v e modes. The d e s c r i b e d s t r u c t u r a l type i s r a t h e r unprecedented i n the chemis t ry o f the main group elements , and o n l y f o r the r e l a t e d i o n i c spec ies — 181 SeOFg are v i b r a t i o n a l s p e c t r a r e p o r t e d . A t o t a l o f 7 v i b r a t i o n a l modes are found f o r l O F ^ , and these are t e n t a t i v e l y ass igned i n Table 28. I t can be argueddthat the remain ing deformat ion modes are found at lower f r e q u e n c i e s and are obscured by the s t r o n g background from the e x c i t i n g l i g h t i n t h i s r e g i o n . Low frequency v i b r a t i o n s are i n f a c t found i n the f a r i n f r a r e d spectrum o f K I 0 2 F 2 at 220 and 196 c m " 1 . A t e n t a t i v e assignment o f the v i b r a t i o n a l f r e q u e n c i e s f o r lOF^ 190 can i n p a r t be based on the v i b r a t i o n a l frequency assignments f o r I0F,. , where p o l a r i z a t i o n measurements on the l i q u i d sample and the o b s e r v a t i o n o f numerous combinat ion bands i n the i n f r a r e d have a l lowed more complete 209 ass ignments . As i n d i c a t e d by the r e p o r t e d s t r u c t u r e o f I0F^ , a n o n - b r i d g i n g 146 i o d i n e - o x y g e n bond e x i s t s i n l O F ^ , and the observed a b s o r p t i o n band at 883 cm '' 'is ass igned to the i o d i n e - o x y g e n s t r e t c h i n g v i b r a t i o n ( c f . 927 cm * f o r 1=0 s t r e t c h i n g i n IOF,.) . Weak a b s o r p t i o n bands at 918, 907 and 862 cm * very p o s s i b l y a r i s e from f a c t o r group s p l i t t i n g . I o d i n e -f l u o r i n e s t r e t c h i n g modes are observed at 657, 550 and 515 cm The band o c c u r r i n g at the h i g h e s t f requency , 657 cm * , i s ass igned to the e q u a t o r i a l f l u o r i n e - i o d i n e s t r e t c h . The f requenc ies o f the two remaining s t r e t c h i n g v i b r a t i o n s i n v o l v i n g the a x i a l f l u o r i n e atoms are c o n s i d e r a b l y l o w e r , which may i n d i c a t e some i n t e r m o l e c u l a r i n t e r a c t i o n . No c e r t a i n assignment i s p o s s i b l e at t h i s p o i n t f o r the bending v i b r a t i o n s . The observed f r e q u e n c i e s f o r the v i b r a t i o n a l s p e c t r a o f KIO2F2 199 are i n agreement w i t h the few r e p o r t e d va lues . A b s o r p t i o n bands due to the i o d i n e - o x y g e n s t r e t c h i n g modes are aga in s p l i t and occur at c o n s i d e r a b l y lower f r e q u e n c i e s than the i o d i n e - o x y g e n s t r e t c h i n I O F y The i o d i n e - f l u o r i n e s t r e t c h i n g v i b r a t i o n s i n lO^P^ a^s0 o c c u r at lower f r e q u e n c i e s , i n d i c a t i n g weaker i o d i n e - f l u o r i n e bonds. A s t r o n g a b s o r p t i o n band observed at 434 cm ^ i n the IR spectrum, but not found i n the Raman spectrum, i s p o s s i b l y a combinat ion band. A s i m l a r spread o f element - oxygen and element - f l u o r i n e s t r e t c h i n g — 181 v i b r a t i o n s i s found f o r the SeOF^ i o n i n KSeOF^. No d e f i n i t e a s s i g n -ments f o r the bending modes i s presentedciby thedauthorsv.•. 9 . 3 . 2 . 3 I 0 2 F D i s c r e t e IC>2~ g r o u p s i n i o d y l compounds would be expected t o absorb i n the same r e g i o n as the i o d i n e - oxygen v i b r a t i o n s i n lOF^ and I 0 2 F 2 ~ - T h i s i s f u r t h e r supported by the va lue o f 810 cm 1 f o r the 147 TABLE 29: V i b r a t i o n a l Spec t ra o f 10 F , 10 AsF and 1 0 I 0 2 F IR (cm ) -1 Raman (cm ) Assignments I 0 2 A s F 6 IR (cm ) Assignment J2°S Raman (cm 858 s 830 s 801 s 716 s 557 vs 534 m,sh 356 ms 337 ms 300 ms 866 w 830 w,sh 807 vs 705 vs 550 vs 364 w 328 s 304 mw 251 I - 0 s t r e t c h i n g modes I - F s t r e t c h i n g Deformat ion modes 774 w,sh 718 s 689 s 614 m,w 534 w,sh 394 m,sh 384 s 376 m,slv 350 w,sh 301 m 3 A S F 6 v . A s F , 4 6 221 w 240 s 276 w 314 w 335 w 352 w 373 w 398 w 455 m 541 w 616 w 644 w 671 w 735 s 747 vs 776 m 798 w 814 w 148 FIGURE 26: Raman Spectrum of K I 0 9 F ? 149 FIGURE 27: Raman Spectrum o f IO-SO F o r O CM 150 FIGURE 28: I n f r a r e d S p e c t r a o f I0„F and I 0 _ A s F / 2 2 6 I 0 2 F 1 0 0 0 c m - 1 2 5 0 10£AsFs 384-1 0 0 0 cm-1 2 5 0 151 frequency o f the symmetric s t r e t c h i n g mode o f the TeC^ m o l e c u l e , i s o e l e c t r o n i c t o 10 ^', as determined by a v i b r a t i o n a l a n a l y s i s o f the e l e c t r o n i c a b s o r p t i o n s p e c t r u m * ^ . The e x i s t e n c e o f d i s c r e t e K ^ - groups i s indeed found f o r i o d y l f l u o r i d e , as evidenced by the v i b r a t i o n a l f r e q u e n c i e s i n the r e g i o n o f 800 cm ^. The i n f r a r e d spectrum i s i n good agreement w i t h the 208 p r e v i o u s l y r e p o r t e d one . The Raman spectrum shows three very s t r o n g a b s o r p t i o n bands i n the s t r e t c h i n g r e g i o n at 807, 705 and 550 cm . The extreme c o m p l e x i t y o f bands i n the i o d i n e - o x y g e n r e g i o n - a t o t a l o f three bands are approx imate ly d e s c r i b e d as 1-0 s t r e t c h i n g v i b r a t i o n s -i n d i c a t e s e x t e n s i v e v i b r a t i o n a l c o u p l i n g . Simple i o n i c s t r u c t u r a l models such as I02 + F or I02 + I02p2 are not c o n s i s t e n t w i t h the observed spectrum. The a b s o r p t i o n band at 550 cm " ' is i n the i o d i n e - f l u o r i n e s t r e t c h i n g r e g i o n and i s comparable to the frequency v a l u e s found f o r the i o d i n e - f l u o r i n e s t r e t c h i n IOF^ , where the f l u o r i n e i s i n an a x i a l p o s i t i o n . F l u o r i n e b r i d g e b o n d i n g , a l r e a d y i n d i c a t e d by the r e s u l t s o f the x - r a y a n a l y s i s o f IOF^j may a l s o be i n v o l v e d i n the s t r u c t u r e o f I n a d d i t i o n , b r i d g e bonding v i a oxygen i s p o s s i b l e , as suggested by the a b s o r p t i o n band at 716 cm ^ , which i s c o n s i d e r a b l y lowered from the expected range o f IO2 s t r e t c h i n g f r e q u e n c i e s . (Frequency v a l u e s o f about 600 cm ^ are 207 ass igned f o r I - 0 - I v i b r a t i o n s i n i o d o s y l compounds .) Both types o f b r i d g e bonding c o u l d account f o r the apparent p o l y m e r i c nature o f i o d y l f l u o r i d e . Complex v i b r a t i o n a l s p e c t r a are a l s o found f o r i o d i n e 192 p e n t o x i d e , where i n s p i t e o f a p r e v i o u s attempt u s i n g i n f r a r e d d a t a , no s imple assignments appear p o s s i b l e . The Raman spectrum o f I20<- has been recorded i n t h i s work, and the frequency va lues are l i s t e d i n Table 29. 9 . 3 . 2 . 4 I 0 2 A s F ( By analogy to the chemical b e h a v i o r o f o ther o x y f l u o r i d e s , e . g . C l O J F ^ ^ ^ ' ^ ^ , the r e a c t i o n o f IC^F w i t h s t r o n g Lewis a c i d s such as BFg and AsF^ should proceed under f l u o r i d e a b s t r a c t i o n and I 0 2 + i o n f o r m a t i o n . However, the i n f r a r e d spectrum o f IG^AsF^ shows no a b s o r p t i o n bands between 800 - 1000 cm 1 , the r e g i o n expected f o r + 199 I 0 2 s t r e t c h i n g f r e q u e n c i e s , i n agreement w i t h p r e v i o u s work Bands at 689 and 384 cm 1 are i n agreement w i t h the expected f r e q u e n c i e s f o r the and modes o f the AsF^ i o n , but the h i g h e s t band observed i s a weak shoulder at 774 cm ^. Two p o s s i b l e e x p l a n a t i o n s can be o f f e r e d f o r the observed spectrum (1) The s t r u c t u r e o f IO^sF^, c o n s i s t s o f p o l y m e r i c c a t i o n s w i t h i o d i n e - o x y g e n - i o d i n e b r i d g e bonds and AsF^ i o n s . A b s o r p t i o n s at 614 and 535 cm 1 c o u l d be a t t r i b u t e d to I - 0 - I b r i d g i n g . (2) Complex f o r m a t i o n between AsF,. and I 0 2 F proceeds v i a oxygen 187 b r i d g i n g as found r e c e n t l y f o r SeOF^SbF, . . However, i t would be s u r p r i s i n g to f i n d A s - F s t r e t c h i n g and bending modes i n the expected p o s i t i o n s o f and f o r the AsF^ group. The f a i l u r e to observe a Raman spectrum f o r t h i s compound does not a l l o w a more d e t a i l e d assignment o f the l i s t e d v i b r a t i o n a l modes. I t can be concluded tha t a monomeric I 0 2 + c a t i o n seems to be absent . 153 9 . 3 . 2 . 5 I 0 2 S 0 3 F A d i f f e r e n t s i t u a t i o n i s encountered i n the Raman spectrum o f IO^SO^F as shown i n F i g u r e 27. S t rong a b s o r p t i o n bands are found at 876 and 865 cm * i n the r e g i o n expected f o r a monomeric iodonium c a t i o n . However, the observed spectrum has f a r too many a b s o r p t i o n bands t o a l l o w a s imple i n t e r p r e t a t i o n f o r the s t r u c t u r e as I C ^ S O ^ F , even i f a l lowance i s made f o r f a c t o r group s p l i t t i n g . The su lphur -oxygen s t r e t c h i n g r e g i o n shows three main bands at about 1335, -1170 and -1030 cm * w i t h e x t e n s i v e s p l i t t i n g f o r the l a t t e r two bands. T h i s i s i n d i c a t i v e o f a symmetry l o w e r i n g f o r the SO^F group from C^v i n the f r e e i o n to C . Such symmetry l o w e r i n g would be expected when the SO^F group becomes c o v a l e n t l y bonded t o the c a t i o n i c group and ac ts e i t h e r as a monodentate group or as a b i d e n t a t e b r i d g i n g or c h e l a t i n g group. As d i s c u s s e d i n Chapter 8, b i d e n t a t e grouping are found f o r B r ( S 0 3 F ) 3 and I ( S 0 3 F ) 3 , as w e l l as monodentate S0 3 F groups . The f requenc ies f o r the b i d e n t a t e groupings i n B r C S 0 3 F ) 3 , I C S 0 3 F ) 3 and 177 49 193 a l s o i n ( C H 3 ) 2 S n ( S 0 3 F ) 2 ' where the c r y s t a l s t r u c t u r e i s known , are l i s t e d i n Table 30 w i t h the observed v i b r a t i o n a l f r e q u e n c i e s o f I 0 2 S 0 3 F . As can be seen i n the t a b l e , good agreement e x i s t s between the f r e q u e n c i e s o f the r e f e r e n c e compounds and I0 , ,S0 3 F. I t i s on t h i s evidence tha t the c h a r a c t e r i s t i c S0 3 F f r e q u e n c i e s i n the spectrum o f I 0 2 S 0 3 F are ass igned to a b i d e n t a t e b r i d g i n g g r o u p i n g , r a t h e r than a b i d e n t a t e c h e l a t i n g g r o u p i n g , r e s u l t i n g i n a p o l y m e r i c s t r u c t u r e . TABLE 30: V i b r a t i o n a l Frequencies o f B r i d g i n g SO^F Groups '(em *) Assignment I ( S 0 3 F ) 3 B r ( S 0 3 F ) 3 (CHj) 2 Sn(S0 3 F) I 0 2 S 0 3 F (Raman) (Raman) (IR) (Raman) 1 1381 1372,1356 1360 1336 7 1182 1168 1180 1172 4 1076,1050 1120 1088,1072 1070 2 869 859 825 865 5 700 721 725 692 3 642 645 650 663 8 556 563 555 565 9 430 430 420 431 6 290:: 303 304 318 ,1332 155 Assignments f o r the IC^ group can now be made. The bands at 900 and 876 cm ^ are ass igned to IO2- asymmetric s t r e t c h i n g and the band at 865 cm ^ to 102~ symmetric s t r e t c h i n g . The occurrence o f both the asymmetric and symmetric s t r e t c h i n g f r e q u e n c i e s o f the c a t i o n i c group i n the Raman spectrum i n d i c a t e s a n o n - l i n e a r arrangement f o r the IO2- g r o u p i n g . A band at 459 cm * i s most l i k e l y to be the 10^ bending v i b r a t i o n . The very s t r o n g band at 428 cm * i s ass igned t o a symmetric s t r e t c h i n g i n v o l v i n g the s i n g l y bonded oxygen atoms and the c e n t r a l i o d i n e atom. The band at 520 cm ^ i s a ss igned t o the corresponding 0- 1-0 asymmetric v i b r a t i o n , aga in i n d i c a t i n g a n o n - l i n e a r arrangement, as found i n a d i s t o r t e d t r i g o n a l b i p y r a m i d a l s t r u c t u r e w i t h a s t e r e o -chemical l y a c t i v e lone p a i r on i o d i n e . In c o n c l u s i o n , a p o l y m e r i c s t r u c t u r e i s suggested w i t h c a t i o n IO2 groups , where s t r o n g i o d i n e - o x y g e n m u l t i p l e bonding i s p r e s e n t , and p o l y m e r i z a t i o n v i a b r i d g i n g a n i o n s , r a t h e r than b r i d g i n g over 1- O-I groups , o c c u r s . The proposed s t r u c t u r e f o r I02S0 3 F i s i l l u s t r a t e d i n F i g u r e 29. A p r i n c i p a l s t r u c t u r a l difference between IO2SO2F and I02AsF^ i s q u i t e apparent . 9 . 3 . 3 S o l u t i o n S tudies I o d y l f l u o r o s u l p h a t e , o r i g i n a l l y r e p o r t e d to be i n s o l u b l e i n 189 HSO^F , d i s s o l v e s s l o w l y i n t h i s s o l v e n t over a p e r i o d of s e v e r a l days w i t h a n o t i c e a b l e i n c r e a s e i n c o n d u c t i v i t y . The s p e c i f i c c o n d u c t i v i t i e s o f I02S0 3 F i n HSO^F are shown i n Table 31 and p l o t t e d _2 versus m o l a l i t y i n F i g u r e 30. At c o n c e n t r a t i o n s l e s s t h a n r 3 . 0 x 10 m o l a l , FIGURE 29: The Proposed S t r u c t u r e f o r I 0 2 S 0 3 F TABLE 31: S p e c i f i c C o n d u c t i v i t i e s o f I 0 2 S 0 3 F i n HS0 3F at 25 .00°C . KS0 3 F A d d i t i o n s 10 2 x M o l a l i t y 10 4 x K 1 0 2 M o l a l i t y 10 4 x K (fl 1 cm 1 ) C^ _ 1cm - 1) 0.0000 1.125 0.0429 31.45 0.0536 1.912 0.3477 36.45 0.2882 5. 728 1.210 51.86 1.026 13.83 2.796 83.01 1.541 18.07 3.725 101.6 2.071 21.68 4.911 125.5 2.778 25.92 3.196 28.49 3.635 30.77 I n t e r p o l a t e d S p e c i f i c C o n d u c t i v i t i e s 4 - 1 - 1 K x 10 (fl cm ) 7 KS0 F 10 SO F M o l a l i t y x 10 6 0.00 1.085 1.125. 0. 25 7.0 4 .9 0.50 13.61 8.0 0.75 19.7 10.8 1.00 25.8 12.4 1.50 38.0 17.7 2.00 50.0 21.5 2.50 62.5 24.8 3.00 72.7 27.7 3.50 84.9 30.1 4.00 97.0 31.9 120-i 100H E (J 8 0 ^ t o x ^ 60 "d c o o g 4 0 a CO 4 C H Electrical conductivity of IQ, S0 3F_ in H S Q F at 2 5 ° C . o K S Q . F standard 0 I O 2 S O 3 F A K S 0 3 F a d d e d Molality x i o 2 moles/kg 159 IG^SO^F behaves as a weak - medium base i n HSO^F, presumably g i v i n g r i s e to s o l v a t e d I 0 2 + c a t i o n s and SO^F a n i o n s . However, w i t h i n c r e a s i n g c o n c e n t r a t i o n , s m a l l e r i n c r e a s e s i n c o n d u c t i v i t y are observed , p o s s i b l y because o f the f o r m a t i o n o f p o l y m e r i c s p e c i e s . The a d d i t i o n o f KSO^F to the s o l u t i o n r e s u l t s i n an i n c r e a s e i n c o n d u c t i v i t y , but the s lope o f the KSO^F a d d i t i o n curve i s not q u i t e as steep as expected f o r the normal r e f e r e n c e KSO^F c o n d u c t i v i t y c u r v e . I t i s u n l i k e l y that IC^SO^F i s e x h i b i t i n g a c i d i c b e h a v i o r t o account f o r the s l i g h t l y reduced c o n d u c t i v i t y v a l u e s f o r KSO^F, but i t i s very p o s s i b l e t h a t f l u o r o s u l p h a t e anions are b e i n g consumed i n polymer f o r m a t i o n . I t seems tha t at low c o n c e n t r a t i o n s , IC^SO^F can d i s s o l v e i n HSOgF and form s o l v a t e d I0" 2 + c a t i o n s by the b r e a k i n g o f b r i d g e bonds. At h i g h e r c o n c e n t r a t i o n , d i m e r i z a t i o n f o l l o w e d by h i g h e r p o l y m e r i z a t i o n p r o b a b l y o c c u r s . However, the nature o f these p o l y m e r i c spec ies was not determined as the s o l u t i o n s were too d i l u t e t o o b t a i n meaningful Raman s p e c t r a . 160 C H A P T E R T E N SELENIUM (IV) OXYFLUOROSULPHATE 10.1 INTRODUCTION T h i s chapter d e s c r i b e s the s y n t h e s i s , p r o p e r t i e s and r e a c t i o n s of the new compound, se lenium (IV) oxyf l u o r o s u l p h a t e , S e O f S O ^ F ^ . In a d d i t i o n , the s t r u c t u r e o f SeOfSO^F)^ i s d i s c u s s e d on the b a s i s o f i t s Raman v i b r a t i o n a l spectrum and c o n d u c t i m e t r i c measurements i n HS0 3 F . No o ther o x y f l u o r o s u l p h a t e s o f se lenium have yet been r e p o r t e d , and i n f a c t few f l u o r o s u l p h a t e s o f se lenium are known. Barr et a l . 178 179 have prepared and c h a r a c t e r i z e d the i o n i c compound Se^fSO^F)^ ' The f l u o r o s u l p h a t e , SeF^SO^F, prepared by the a d d i t i o n o f SO^ t o 21 SeF^, has been known f o r some time , but s t r u c t u r a l s t u d i e s have appeared o n l y r e c e n t l y 1 ^ . 10.2 EXPERIMENTAL 10 .2 .1 M a t e r i a l s Reagent grade se lenium o x y c h l o r i d e and se lenium d i o x i d e were used wi thout f u r t h e r p u r i f i c a t i o n . A n a l y t i c a l grade se lenium was f i n e l y ground i n a mortar and p e s t l e . Potass ium o x o t r i c h l o r o s e l e n a t e ( I V ) , 181 KSeOCl^, was prepared as a c c o r d i n g t o P a e t z o l d and A u r i c h (anal %C1 Theor : 4 4 . 2 , Found: 43.6) 161 Bromine (I) monof luorosulphate was prepared by the method o f 42 Roberts and Cady . Anhydrous a n a l y t i c a l grade s t a n n i c c h l o r i d e was ob ta ined from J . T . Baker Co. and f u r t h e r p u r i f i e d by d i s t i l l a t i o n . 45 Potass ium f l u o r o s u l p h a t e was prepared as a c c o r d i n g to Barr et a l . The t r a n s f e r o f a l l compounds was performed i n a d r y - b o x , w h i l e a h i g h vacuum system was employed i n the p r e p a r a t i o n o f se lenium (IV) o x y f l u o r o s u l p h a t e . 10 .2 .2 P r e p a r a t i o n of S e O ( S 0 3 F ) 2 Three routes l e a d i n g to the s y n t h e s i s o f SeOfSO^F)^ were found and are d e s c r i b e d as f o l l o w s : (1) An excess o f S^^F,^ W a S d i s t i l l e d i n vacuo i n t o a 150 ml pyrex r e a c t i o n f l a s k (F igure 1) c o n t a i n i n g i n a t y p i c a l p r e p a r a t i o n 28.31 mmoles o f SeOCl,, at -196°C. Upon warming the r e a c t i o n to room temperature , a m i l d l y exothermic r e a c t i o n took p l a c e w i t h the e v o l u t i o n o f C l , , . At r e g u l a r i n t e r v a l s , the C l 2 was pumped o f f to a v o i d the f o r m a t i o n o f CISO^F and p o s s i b l e s i d e r e a c t i o n s , and the r e a c t i o n v e s s e l was shaken. To complete the r e a c t i o n , f r e s h S 2 P ^ F 2 was added and the r e a c t i o n v e s s e l shaken u n t i l the e v o l u t i o n o f C l , , had ceased, and the p a l e y e l l o w c o l o u r o f S e O C l 2 had d i s a p p e a r e d . The excess S 2 0 ^ F 2 was then removed, l e a v i n g a c o l o u r l e s s , v i s c o u s and n o n - v o l a t i l e l i q u i d , corresponding t o 28.25 mmoles o f S e 0 ( S 0 3 F ) 2 > A n a l . C a l c . f o r S e O ( S 0 3 F ) 2 : Se 26.94, F 12 .95 ; Found: Se 26 .93 , F 12.59 162 (2) An excess o f S „ 0 , F o was d i s t i l l e d i n vacuo on to 9.27 mmoles o f 2 6 z Se02 conta ined i n the u s u a l type o f r e a c t i o n v e s s e l ( F i g u r e 1 ) . Upon warming t o room temperature , a s low r e a c t i o n took p l a c e w i t h e v o l u t i o n o f 0^. The r e a c t i o n v e s s e l was heated at 5 0 ° C , and a f t e r 10 hours had e l a p s e d , a l l s o l i d Se02 was consumed, and a v i s c o u s l i q u i d , i n s o l u b l e i n $ 2 0 ^ 2 , remained. The excess S_®(f2 was pumped o f f at room temperature , l e a v i n g 9.24 mmoles o f SeOtSO^F^ b e h i n d . The product was i d e n t i f i e d by i t s Raman spectrum and Se a n a l y s i s (26.3% v . s . 26.9% c a l c ) . (3) A s m a l l excess o f BrSO^F was d i s t i l l e d i n vacuo on to 6.60 mmoles o f Se0Cl2 conta ined i n a pyrex r e a c t i o n v e s s e l (F igure 1 ) . At room temperature , a moderate r e a c t i o n proceeded w i t h the e v o l u t i o n o f and C I 2 . Removal o f the excess BrSO^F l e f t behind a v i s c o u s l i q u i d , contaminated w i t h BrSO^F. The Raman spectrum of the product and the mass change was i n agreement w i t h the f o r m a t i o n o f S e O f S O ^ F ^ . Because o f the d i f f i c u l t y i n removing the excess o f BrSO^F from the p r o d u c t , the f i r s t two p r e p a r a t i o n s have always been employed i n f u r t h e r p r e p a r a t i o n s o f S e O f S O ^ F ^ . 10 .2 .3 Attempts t o Prepare K S e 0 ( S 0 3 F ) 3 (1) Into a r e a c t i o n v e s s e l comple te ly sea led o f f from the atmosphere and c o n t a i n i n g 3.41 mmoles Se0(S0 3F)2> m i l l i g r a m q u a n t i t i e s o f KS0 3 F were added w i t h s h a k i n g , u n t i l 3.40 mmoles had been added. At room temperature , no v i s i b l e r e a c t i o n was observed , and warming 163 the r e a c t i o n mixture to 60° - 80°C. produced no apparent e f f e c t . A Raman spectrum o f the mixture o n l y showed the o r i g i n a l components. (2) An excess o f S„0 ,F„ was d i s t i l l e d at -196°C on to 1 g o f KSeOCl , z o Z • ° 3 conta ined i n a r e a c t i o n v e s s e l s i m i l a r to tha t used i n the p r e p a r a t i o n o f Se0(S0.jF)2 (F igure 1 ) . At room temperature , a r e a c t i o n took p l a c e immediate ly to form a whi te s o l i d , a v i s c o u s l i q u i d and c h l o r i n e gas. The mass change was c o n s i s t e n t w i t h the f o r m a t i o n o f a product o f the compos i t ion o f KSeOtSO^F)^; a Raman spectrum o f the p r o d u c t , however, c o u l d be i n t e r p r e t e d as a mixture of KSO^F and SeOfSO^F)^. (3) H i g h l y p u r i f i e d HSO^F was added to 1 g o f KSeOCl^ conta ined i n a 2 - p a r t pyrex v e s s e l and equipped w i t h a F i s c h e r and P o r t e r t e f l o n v a l v e . A y e l l o w s o l u t i o n immediate ly formed and e f forvescence o c c u r r e d . A Raman spectrum showed the presence o f S e O C l 2 . E v a p o r a t i o n o f the l i q u i d phase l e f t r e s i d u a l s o l i d KSO^F as a c c o r d i n g t o a Raman spectrum. 10 .2 .4 The R e a c t i o n Between S n C l 4 and S e O ( S 0 3 F ) 2 An excess o f S n C l ^ was d i s t i l l e d i n vacuo on t o 1.4 g S e O ( S 0 3 F ) 2 . A f t e r the r e a c t i o n f l a s k was shaken f o r s e v e r a l minutes at room temperature , the excess S n C l ^ was d i s t i l l e d o f f , l e a v i n g a g l a s s y s o l i d b e h i n d . The c o l o u r l e s s g l a s s f a i l e d to c r y s t a l l i z e when i t was coo led at -196°C. and a l l o w e d t o s l o w l y warm up . A Mossbauer spectrum o f the g l a s s y product showed a broad peak at 6 = -0 .133 mm/sec r e l a t i v e to S n 0 2 . T h i s chemical s h i f t i s too 49 low f o r the product t o be a s imple adduct o f S n C l ^ P o s s i b l y , a l i g a n d sc rambl ing r e a c t i o n occurs i n which one or more o f the 164 c h l o r i n e atoms i s r e p l a c e d by f l u o r o s u l p h a t e grouping which would account f o r the low chemical s h i f t . 10 .2 .5 V i b r a t i o n a l Spec t ra The Raman c e l l s f o r l i q u i d s and s o l u t i o n s d e s c r i b e d i n chapter two were u s e d . Attempts to o b t a i n an i n f r a r e d spectrum o f SeOCSO^F)^ between AgCl p l a t e s r e s u l t e d main ly i n a spectrum o f AgSO^F and SeOCl^ , e v i d e n t l y as the r e s u l t o f the r e a c t i o n : 2AgCl + S e O ( S 0 3 F ) 2 • 2AgS0 3F + S e O C l 2 The use of s i l i c o n windows a l s o f a i l e d t o produce s a t i s f a c t o r y s p e c t r a . 10 .2 .6 C o n d u c t i v i t y S t u d i e s C o n d u c t i v i t y measurements were obta ined f o r s o l u t i o n s o f S e O ( S 0 3 F ) 2 i n both HS0 3 F and H [ S b F 2 ( S 0 3 F ) 4 ] . The p r e p a r a t i o n o f s u p e r a c i d , H[SbF 2 ( S 0 3 F ) 4 J , has been p r e v i o u s l y d e s c r i b e d ^ 2 ' . 10.3 RESULTS AND DISCUSSION 10 .3 .1 The P r e p a r a t i o n and P r o p e r t i e s o f S e 0 ( S 0 3 F ) 2 Three s y n t h e t i c routes have) been found l e a d i n g t o the new compound, S e O ( S 0 3 F ) 2 . P e r o x y d i s u l p h u r y 1 d i f l u o r i d e , ^2^6^2' and bromine (I) m o n o f l u o r o s u l p h a t e , B r S 0 3 F , are employed as f l u o r o s u l p h a t i n g agents as a c c o r d i n g t o : 165 25°C. SeOCl„ + S _ 0 , F . 2 2 6 2 S e O ( S 0 3 F ) 2 + C l 2 (1) 25°C. SeOCS0 3 F) 2 + 2 B r C l * (2) 50°C. Se0 o + S o 0 , F _ 2 2 6 2 10 hours S e O ( S 0 3 F ) 2 + 1/2 0 2 (3) * B r C l d i s s o c i a t e s i n t o Cl„ and Br„ at room temperature The f i r s t r e a c t i o n i s c e r t a i n l y the most convenient method o f p r e p a r i n g S e O ( S 0 3 F ) 2 . The d i f f i c u l t y i n s e p a r a t i n g the product from the r e l a t i v e l y n o n - v o l a t i l e bromine monof luorosulphate prevents the second r e a c t i o n from be ing a u s e f u l r o u t e to S e 0 ( S 0 3 F ) 2 , w h i l e the t h i r d r e a c t i o n i s slow and r e q u i r e s s e v e r a l hours f o r c o m p l e t i o n . Selenium (IV) o x y f l u o r o s u l p h a t e i s a h i g h l y r e a c t i v e compound which r e a c t s v i o l e n t l y w i t h w a t e r , and e x p l o s i v e l y w i t h o r g a n i c m a t e r i a l . A v i s c o u s , c o l o u r l e s s and n o n - v o l a t i l e l i q u i d at room temperature , i t s o l i d i f i e s to a g l a s s at -45°C. The compound i s t h e r m a l l y s t a b l e i n a pyrex c o n t a i n e r up to about 60°C. at which p o i n t the l i q u i d t u r n s a p a l e y e l l o w and some decomposi t ion b e g i n s . The 3 d e n s i t y o f se lenium (IV) o x y f l u o r o s u l p h a t e i s 2.43 g/cm . I t i s i n s o l u b l e i n C C l ^ , moderately s o l u b l e i n S ^ ^ F , , and m i s c i b l e w i t h H S 0 3 F . The neat l i q u i d has a temperature-dependent e l e c t r i c a l c o n d u c t i v i t y t y p i c a l o f a n o e l e c t r o l y t i c d i s s o c i a t i o n as i s shown i n F i g u r e 31 .and i n Table 32. TABLE 32 S p e c i f i c C o n d u c t i v i t y of Neat S e O ( S 0 3 F ) 2 as a F u n c t i o n o f Temperature TEMP.(°C.) K x 1 0 3 ( f i " 1 c m _ 1 ) 1 9 . 1 5 1 . 2 2 8 2 5 . 0 0 1 . 5 9 2 2 8 . 0 0 1 . 8 3 1 2 9 . 0 0 1 . 9 0 5 3 3 . 2 0 2 . 2 3 5 3 6 . 7 0 2 . 5 4 5 4 0 . 4 0 2 . 8 3 5 c f . S e O C l 2 at 2 5 . 0 0 ° C . 2 U K = 2 . 0 0 x 10 5 n 1 cm 1 Conduct iv i ty of neat S e O ( S 0 3 F ) 2 as a Funct ion of Temperature Temperature ( ° C ) FIGURE 31 A c i d - b a s e p r o p e r t i e s o f the cova lent m o l e c u l e , SeOCl^j are w e l l 184 known . e . g . Bas ic b e h a v i o r i s e x h i b i t e d by the donor oxygen atoms i n S e 0 C l o which can i n t e r a c t w i t h the Lewis a c i d S n C l . to _ 2 4 185 186 form the c i s - a d d i t i o n compound SnCl^.2SeOCl2 ' . On the other hand, S e O C ^ can behave as a Lewis a c i d i n r e a c t i n g w i t h a l k a l i metal 181 c h l o r i d e s t o form compounds o f the type MSeOCl^ , where M i s an a l k a l i m e t a l . In a s i m i l a r f a s h i o n , SeOF^ a l s o forms compounds of 181 the type MSeOF^ w i t h a l k a l i metal f l u o r i d e s . (However, l i t t l e i s known about the p o s s i b l e donor p r o p e r t i e s o f SeOF2, o t h e r than 187 the very r e c e n t l y r e p o r t e d c r y s t a l s t r u c t u r e o f SeOF2-NbF,_ where the oxygen atom o f SeOF2 i s b r i d g e d to n i o b i u m . ) Selenium (IV) o x y f l u o r o s u l p h a t e d i f f e r s markedly from S e O C ^ i n donor -acceptpcr^proper t ies . A l l attempts to prepare KSeO(SO^F) 2> the analogue o f KSeOCl^ , were u n s u c c e s s f u l and i t i s u n l i k e l y tha t t h i s compound e x i s t s as evidenced by the f o l l o w i n g : (1) The a d d i t i o n o f f i n e l y ground KSO^F t o S e O ( S 0 3 F ) 2 does not r e s u l t i n a r e a c t i o n . (2) The r e a c t i o n of KSeOCl_ w i t h an excess o f S _ 0 , F o j 2 6 z produces a mixture o f S e O ( S 0 3 F ) 2 and KSO^F as a c c o r d i n g t o : KSeOCl 3 + 3/2 S 2 0 6 F 2 • KS0 3 F + S e O ( S 0 3 F ) 2 +3/2 C l 2 (3i) A mixture o f S e O C l 2 and KS0 3 F r e s u l t s from the r e a c t i o n o f K S e O C l 3 and H S 0 3 F : . KSeOCl 3 + HS0 3 F > KS0 3 F + S e O C l 2 + HCl 169 P o s s i b l e donor p r o p e r t i e s of SeOCSO^F)^ were i n v e s t i g a t e d by r e a c t i n g i t w i t h S n C l ^ . A g l a s s y s o l i d o f u n c e r t a i n compos i t ion r e s u l t e d i n s t e a d o f a s imple a d d i t i o n compound. The Mossbauer spectrum r e v e a l e d a broad peak at 6 = -0 .133 mm/sec r e l a t i v e to Sn02, f a r o u t s i d e the normal range of +0.2 t o +0.5 mm/sec f o r adducts o f 119 S n C l . . I t i s f e a s i b l e t h a t one or more c h l o r i n e atoms i n SnCl„ 4 4 are r e p l a c e d by f l u o r o s u l p h a t e groups account ing f o r the negat ive isomer s h i f t , and t h a t SeOfSO^F^ does not behave as a Lewis base i n t h i s r e a c t i o n , but as a f l u o r o s u l p h a t i n g agent . The nature o f the ob ta ined product was not i n v e s t i g a t e d f u r t h e r . I t i s noteworthy i n t h i s connec t ion tha t s t a b l e Sn-0S02F bonds have been found i n a 131 l a rge number o f Sn(IV) compounds ( e . g . S n C ^ C S O ^ F ^ ) . The e l e c t r i c a l c o n d u c t i v i t y o f the neat l i q u i d i s h i g h e r than f o r se len ium (IV) o x y c h l o r i d e . The f o l l o w i n g s e l f - d i s s o c i a t i o n process has been invoked to e x p l a i n the observed e l e c t r i c a l 181 c o n d u c t i v i t y o f the l a t t e r : —> _ - „ + 2 S e O C l 2 < SeOCl + S e O C l 3 By ana logy , the s e l f - d i s s o c i a t i o n process f o r SeOfSO^F^ might be : 2 S e 0 ( S 0 _ F ) „ v S e 0 ( S 0 „ F ) + + SeO(SO-F),~ 3 Z 3 3 3 In view o f the u n s u c c e s s f u l attempts to prepare K S e O ( S 0 3 F ) 3 , i t seems more a p p r o p r i a t e to d e s c r i b e the s e l f - d i s s o c i a t i o n process a s : Se0(S0 T F)_ . A Se0(S0_F) + + S0 7 F~ 3 Z 3 3 Two consequences a r i s e from the f a c t that both SeOCl^ and SeOCSO^F)^ are s i g n i f i c a n t l y d i s s o c i a t e d i n the l i q u i d phase: (1) Both should be s t r o n g e l e c t r o l y t e s i n a p r o t o n i c s o l v e n t . (2) Both may p o s s i b l y undergo l i g a n d exchange r e a c t i o n s v i a an i o n i c mechanism. Thus, se lenium CIV) o x y c h l o r o f l u o r o s u l p h a t e , SeOClfSO^F) , i s prepared by the d i r e c t a d d i t i o n o f S e O C l 2 to SeO(S0 3F) ';. The f o r m a t i o n o f a new compound, as opposed t o a s o l u t i o n of the s t a r t i n g m a t e r i a l s , i s i n d i c a t e d by the observed i n c r e a s e d v i s c o s i t y o f the r e s u l t i n g l i q u i d . More d i r e c t evidence i s p r o v i d e d by a Raman v i b r a t i o n a l spectrum as i s d i s c u s s e d i n a l a t e r s e c t i o n . 10 .3 .2 C o n d u c t i m e t r i c S t u d i e s S o l u t i o n s o f S e O C l 2 and S e O ( S 0 3 F ) 2 i n HS0 3 F were s t u d i e d by c o n d u c t i v i t y measurements i n hopes o f d e t e c t i n g the f o r m a t i o n o f o x y c a t i o n s i n t h i s s o l v e n t . Both s o l u t e s are m i s c i b l e w i t h HS0 3 F and behave as bases i n H S 0 3 F , as i s evidenced by a cont inued i n c r e a s e i n c o n d u c t i v i t y upon the a d d i t i o n o f K S 0 3 F . The c o n d u c t i v i t y r e s u l t s together w i t h the re fe rence s o l u t e KS0 3 F are l i s t e d i n Table 33 and p l o t t e d i n F i g u r e 32 . A comparison o f the s p e c i f i c c o n d u c t i v i t i e s o f S e 0 ( S 0 3 F ) 2 w i t h those o f the r e f e r e n c e s o l u t e , K S 0 3 F , i n d i c a t e tha t S e O ( S 0 3 F ) 2 behaves as a moderate base i n HS0 3 F ; The s i m p l e s t mode o f i o n i z a t i o n can be f o r m u l a t e d as i n the neat l i q u i d , S e O ( S 0 3 F ) 2 = SeOCS0 3 F) + + S0 3 F where Se0(S0„F) i s i n c o m p l e t e l y d i s s o c i a t e d . TABLE 33: (a) S p e c i f i c C o n d u c t i v i t i e s o f SeOCl and SeO (S0_F) i n HSO F at 25 .00° S e O C l 2 S e O ( S 0 3 F ) 2 M o l a l i t y K X 10 M o l a l i t y K x 10 2 - 1 - 1 2 -1 -1 x 10 (ft cm ) x 10 (ft cm ) 0.000 1. 265 0.000 1.169 0.267 7. 000 0.091 3.562 0.683 21. 27 0.113 4.010 1.956 41 . 24 0.159 4.167 3.747 74. 94 0.231 5.989 4.368 91. 47 0.384 8.001 5.159 106. 7 0.677 10.83 6.767 134. 5 0.986 13. 21 7.255 142. 6 1.341 15.55 7.952 154. 8 1.750 17.61 8.708 168. 2 2.308 19.82 2.517 20.62 3.162 23.01 . / c o n t i n u e d 172 Table 33 Cont inued (b) I n t e r p o l a t e d s p e c i f i c c o n d u c t i v i t i e s o f SeO(SCLF) and SeOCl 2 M o l a l i t y x 10 K X 10 4 (ft" -1 - 1 -cm J KS0 3 F S e O ( S 0 3 F ) 2 S e O C l 2 0.00 1 085 1 148 1.265 1.00 25 8 13 3 27.5 1.50 38 0 16 4 36.3 2.00 50 0 18 7 45.5 2.50 62 5 20 5 54.8 3.00 72 7 22 3 64.0 3.50 84 9 24 2 73.5 4.00 97 0 82.5 IO 2 Molal i ty 174 At a g iven c o n d u c t i v i t y , the degree o f d i s s o c i a t i o n , a , f o r the above e q u i l i b r i u m can be c a l c u l a t e d from a = m.,,,. „/m„ n , „ . , and the KSO^F SeOCSO^Fj^ e q u i l i b r i u m constant K ^ , from = "^SeOCSO F) ^ 1 ~ a * C a l c u l a t e d •3 2 values o f are found to v a r y o n l y s l i g h t l y i n the c o n c e n t r a t i o n range _3 0.01 to 0.04 m o l a l , and a mean va lue o f 4 .0 x 10 was obta ined f o r K^. Higher s p e c i f i c c o n d u c t i v i t i e s obta ined f o r the s o l u t e SeOCl^ , can be accounted f o r by the f o l l o w i n g s e r i e s o f e q u a t i o n s : S e 0 C l o — ' • S e 0 C l + + C l " C l " + HS0 3 F v.\ HCl + S 0 3 F " HS0 3F + HCl - -» H 2 C 1 + + S 0 3 F " C h l o r i d e s ions formed i n the f i r s t s tep are immediate ly pro tonated by HS0 3F w i t h the r e l e a s e of f l u o r o s u l p h a t e i o n s , which account f o r the s p e c i f i c c o n d u c t i v i t i e s b e i n g c l o s e to those o f the re ference s o l u t e . HCl behaves as a weak base i n H S 0 3 F , and i s pro tonated o n l y to a s m a l l e x t e n t . The r e a c t i o n o f o x i d i z i n g agents such as Se0 2 w i t h se lenium i n HS0 3 F r e s u l t s i n the f o r m a t i o n o f the spec ies S e ^ + + and S e g + + To examine the o x i d i z i n g p r o p e r t i e s o f SeOCSO^)^ i n H S 0 3 F , a s o l u t i o n o f S e O ( S 0 3 F ) 2 i n HS0 3F was t i t r a t e d c o n d u c t i m e t r i c a l l y w i t h e lemental se len ium. The r e s u l t s are g iven i n Table 34 and F i g u r e 33. The se lenium a d d i t i o n s impart a green c o l o u r t o the s o l u t i o n as the r e s u l t o f the f o r m a t i o n o f the spec ies S e g + + . The s o l u t i o n o f S e g + + was found t o be s t a b l e over a p e r i o d o f 24 hours , w i t h o n l y s l i g h t o x i d a t i o n to the more s t a b l e spec ies S e ^ + + . The f o l l o w i n g r e a c t i o n s are i n v o l v e d i n the t i t r a t i o n : 175 TABLE 34: Conduct imetr i c T i t r a t i o n o f S e O ( S 0 3 F ) 2 i n HSC^F w i t h Elemental Se S e O ( S 0 3 F ) 2 Se 4 4 M o l a l i t y K x 10 M o l a l i t y K X 10 2 - 1 - 1 2 -1 -1 x 10 (Sl cm ) x 10 (Si cm ) 0 0000 1 148 0 1620 4 269 0 3671 7 514 0 7479 11 48 1 080 13 89 1 560 16 59 1 856 18 00 2 168 19 35 2 757 21 60 3 607 24 61 0 0000 24 61 0 2234 25 93 1 575 34 97 2 908 43 93 4 932 58 49 7 230 76 43 9 312 91 09 11.57 119.7 176 Conductivity curve of S e O ( S 0 3 F ) 2 in HSO F at 2 5 °C . IO2 Molality IO2 Molality S e O ( S O F ) Selenium 3 2 FIGURE 33 177 SeO(SO„F). + 15 Se + 2 HSCLF > 2 S e Q + + + 4 SO_F + H„0 j 2 o o J 2 H.O + HSO-F • H_0 + + S0-F~ • H . S 0 . + HF z o •< j j — Z 4 Assuming t h a t the g e n e r a t i o n o f 1 mole o f ^ 0 i n HSO^F produces 0.60 — 188 — moles o f SO^F , 0.306 moles o f SO^F / mole o f s o l u t e are expected f o r the occurrence o f the above p r o c e s s e s . A comparison o f the s lopes o f the Se and KSO^F c o n d u c t i v i t y curves are i n good agreement w i t h t h i s e x p e c t a t i o n . While SeOCSO^F)^ i s o n l y p a r t i a l l y d i s s o c i a t e d i n HSO^F, i t i s f u l l y i o n i z e d i n s u p e r a c i d media. The c o n d u c t i v i t y data are shown i n Table 35 and F i g u r e 34. The end p o i n t occurs when 1 mole o f s u p e r a c i d has been n e u t r a l i z e d by 1 mole o f SeOCSO^F)^- Past the e n d - p o i n t , a s l i g h t c o n d u c t i v i t y decrease i s observed up to 1.9 mola l SeOCSO^F^-T h i s l o w e r i n g i n c o n d u c t i v i t y , as opposed to an i n c r e a s e from the moderately b a s i c behavior o f Se0(S0_F) 9 i n HS0_F, i s unexpected. 10 .3 .3 V i b r a t i o n a l S p e c t r a The Raman v i b r a t i o n a l s p e c t r a o f S e 0 ( S 0 3 F ) 2 and SeO(S0 3 F)Cl are reproduced i n F i g u r e s 35 and 36- The observed f r e q u e n c i e s , r e l a t i v e i n t e n s i t i e s and t e n t a t i v e assignments are g i v e n i n Table 36-Two f e a t u r e s o f the Raman spectrum o f SeOfSOgF^ are immediately apparent : (1) The Se=0 s t r e t c h occurs at a frequency o f 1044 cm 1 , much h i g h e r than SeOF^ and S e O C ^ , which have t h e i r Se=0 s t r e t c h i n g f requenc ies at 1012 cm 1 and 955 cm 1 r e s p e c t i v e l y 1 ^ ( c . f . P=0 i n 40 190 POCSO^F)^ which i s lower than that observed f o r POF^ ) . TABLE 35 S p e c i f i c i C o n d u c t i v i t i e s o f SeOCSO^F)^ In Superac id 4 Mole R a t i o K X 10 S e O ( S 0 3 F ) 2 / A c i d fc'^m"1) 0.0000 276.5 0.0211 264.6 0.0442 251.3 0.0669 238.5 0.1065 212.6 0.1267 207.2 0.1547 193.7 0.1821 179.8 0.2083 168.9 0.2442 152.8 0.2945 1 134.8 0.3594 113.2 0.4167 97.72 0.4651 85.76 0.5302 72.26 0.5862 63.24 0.6353 57.01 0.7232 49.98 0.795 2 46.29 0.9127 42.61 0.9910 40.72 1.022 40.09 1.119 38.89 1.310 37.48 1.424 36.65 Conductiv i ty Study of S e O ( S 0 3 F ) 2 in HSbF ; ( S 0 3 F ) 4 at 2 5 ° Base • S e O ( S 0 3 F ) 2 o K S 0 3 F 180 181 FIGURE 36 : RAMAN SPECTRUM OF SeO(S0 3 F)Cl 182 TABLE 36: The Raman V i b r a t i o n a l Spec t ra of Se0(S0 F) and SeO(SO F)C1 S e O ( S 0 3 F ) 2 SeO(S0 3 F)Cl Assignment* (cm 1 ) I n t e n s i t y ( c m - 1 ) I n t e n s i t y 1430 dep 1 1405 dep 0.2 v ?(A") 1220 p 6 1212 p 1.0 1055 p 4 1071 p 1.5 . ^ 4 C A , ) 1044 p 4 1048 p 0.5 Se=0 s t r . (SeO(S0 3 F) 2 ) 1011 p 2.5 Se=0 s t r . (SeO(S0 3 F)Cl) 944 p 0.2 Se=0 s t r . (SeOCl 2 ) 848 p 3 839 p 0.5 v 2 ( A ' ) 639 p 5 6635 p 1.5 v 3(A«) (SeO(S0 3 F) 2 ) 6622 p 2.0 v 3CA«) 588 p 2 587 p 0.2 v 5 ( A ' ) 551 dep 2 551 dep 0.1 v 8(A») 452 4 Se-0 asym. s t r . 446 p 4 430 p 10.0 Se-0 sym. s t r . 411 p , sh 2.0 S e - C l s t r . 390 b r 1 v 9 ( A " ) 340 sh 1 0=Se02 asym bending 311 p 4 0=Se02 sym. bending 276 1.0 0=Se0Cl bending 265 p 10 0=Se02 sym. bending 232 dep 6 232 dep 1.0 v 6 ( A " ) 175 sh 2 171 2.0 S0 3 F T o r s i o n 210 1.0 0=Se0Cl bending * Symbols d e s c r i b i n g the cova lent S0 3 F group v i b r a t i o n a l modes are taken from the c o r r e l a t i o n t a b l e on page 130 183 and (2) The asymmetric and symmetric SO^ s t r e t c h i n g f r e q u e n c i e s found at 1430 cm 1 and 1220 cm 1 are c o n s i d e r a b l y lowered from the normal -1 72 p o s i t i o n s of about 1500 and 1250 cm f o r a covalent SO^F grouping T h i s i s r e m i n i s c e n t o f the c o v a l e n t SO^F groups c o n t a i n e d i n KBrfSO^F)^ and d i s c u s s e d i n Chapter 8 , where the l o w e r i n g o f the SO^ s t r e t c h i n g f r e q u e n c i e s was a t t r i b u t e d t o p o l a r bromine-oxygen bonds. I t seems f e a s i b l e tha t the Se-0 bonds i n S e O ( S 0 3 F ) 2 have a c e r t a i n degree o f i o n i c c h a r a c t e r , a p r o p e r t y that i s a l r e a d y expressed i n the h i g h c o n d u c t i v i t y o f the neat l i q u i d , i . e . • A p o s i t i v e charge on the se len ium atom would account f o r the s t r o n g Se=0 bond, and the l o w e r i n g o f the S 0 2 s t r e t c h i n g f r e q u e n c i e s from where they are found i n a covalent SO^F group. The s e l f - i o n i z a t i o n process suggested i n s e c t i o n 10 .3 .1 would produce such a charged s p e c i e s . The i n t e r p r e t a t i o n o f the spectrum o f Se0(S0gF) 2 can be made by theory o f group v i b r a t i o n s . As a f i r s t approx imat ion f o r the 12 atom molecule where a maximum number of 30 v i b r a t i o n a l modes are p o s s i b l e , assignments are made on the b a s i s o f 2 independent se ts o f group v i b r a t i o n s which are as f o l l o w s : (1) the SeOY 2 v i b r a t i o n s (where Y r e p r e s e n t s the SO^F group as a s i n g l e u n i t ) , and (2) the cova lent SO^F group v i b r a t i o n s g i v i n g r i s e to 2 se ts o f 9 v i b r a t i o n s ; the two se t s w i l l be i n d i s t i n g u i s h a b l e i f the f l u o r o s u l p h a t e groups are e q u i v a l e n t . The c o v a l e n t SO^F group v i b r a t i o n s can be ass igned as f o l l o w s : The asymmetric and symmetric SO^ s t r e t c h i n g f r e q u e n c i e s at 1430 and 1220 c m " 1 , the S-F s t r e t c h at 848 c m " 1 , the S03, de format ion f requenc ies at 639, 588 and 551 cm 1 and the S0„ r o c k i n g f r e q u e n c i e s 184 at 390 and 232 cm account f o r 8 o f the 9 v i b r a t i o n s expected f o r a cova lent SO^F group. The remain ing mode o f v i b r a t i o n , the SeO-S s t r e t c h i s most d i f f i c u l t to a s s i g n , and p o s s i b l y c o i n c i d e s w i t h the a b s o r p t i o n peak due t o the Se=0 s t r e t c h . T h e r e f o r e , a h i g h l y t e n t a t i v e assignment f o r the SeO-S s t r e t c h i s made at 1055 cm The Se=0 s t r e t c h i s a s s i g n e d t o the shoulder at 1044 cm * , a l though one can e q u a l l y make the assignments i n r e v e r s e f o r these l a t t e r two a b s o r p t i o n s . The SeOY^ v i b r a t i o n s can becass igned by comparison to bromine-29 oxygen v i b r a t i o n s i n K B r f S O ^ F ^ and BrSO^F . The three s t r e t c h i n g modes are ass igned at 1044 cm * (Se=0 s t r e t c h ) , 446 cm * (Se^-0 symmetric s t r e t c h ) and to the shoulder at 452 cm * (Se-0 asymmetric s t r e t c h ) . The three bending modes are ass igned at 340,311 and 265 cm The a b s o r p t i band at 175 cm ^ i s ass igned to one o f the t o r s i o n modes. The remain ing t o r s i o n , modes, p o s s i b l y o c c u r r i n g below 150 cm * were not observed due to the s t r o n g R a y l e i g h s c a t t e r i n g o f the l a s e r beam i n t h i s r e g i o n . The Raman v i b r a t i o n a l spectrum o f a s o l u t i o n from an equal number o f moles o f S e O C l 2 and S e O ( S 0 3 F ) 2 i s c o n s i s t e n t w i t h the f o r m a t i o n of S e C S 0 3 F ) C l . The replacement o f a S0 3 F group i n S e O ( S 0 3 F ) 2 by c h l o r i n e r e s u l t s i n the f o l l o w i n g changes i n band p o s i t i o n s : C l ) The Se=0 s t r e t c h i n g frequency i s lowered to 1011 cm ^. (Shoulders , at 1048 and 944 c m - 1 are due t o S e 0 ( S 0 3 F ) 2 and S e 0 C l 2 r e s p e c t i v e l y , which are i n e q u i l i b r i u m w i t h S e ( S 0 3 F ) C l ) . (2) A sharp i n t e n s e band at 1071 cm ^ i s ass igned t o the S-OSe s t r e t c h . T h i s assignment i s c o n s i s t e n t w i t h the expected i n c r e a s e i n the S-OSe bond s t r e n g t h . 185 (3) The Se-0 symmetric s t r e t c h i s lowered i n frequency to 430 cm"^; the Se-0 asymmetric s t r e t c h can not be r e s o l v e d from t h i s i n t e n s e band. A shoulder band at 411 cm * i s ass igned to the S e - C l s t r e t c h . Assignments f o r the cova lent SO^F group v i b r a t i o n s are made by comparison to the spectrum o f SeOCSO^F),,. The remaining bands are ass igned to S e - O - C l bending and t o r s i o n modes. The Raman s p e c t r a o f s o l u t i o n s o f S e O C l 2 and S e O ( S 0 3 F ) 2 at d i f f e r e n t mole r a t i o s are t a b u l a t e d i n Table 3 7 . A l l bands i n these s p e c t r a can be ass igned to S e O C l 2 , S e O ( S 0 3 F ) 2 or S e O ( S 0 3 F ) C l . A c o n c e n t r a t e d s o l u t i o n o f S e O C l 2 i n HS0 3 F shows a peak at 1011 cm * , i n d i c a t i n g the f r o m a t i o n o f S e O ( S 0 3 F ) C l , and a l s o a weak a b s o r p t i o n band at 2906 cm * that can be ass igned t o H - C l s t r e t c h i n g . These o b s e r v a t i o n s are i n agreement w i t h the c o n d u c t i v i t y r e s u l t s . 10 .3 .4 Nuc lear Magnetic Resonance S tudies The r e s u l t s o f the NMR s p e c t r a are summarized i n Table 38. 19 The F NMR s p e c t r a o f S e O ( S 0 3 F ) 2 and SeO(S0 3 F)Cl show sharp s i n g l e peaks at chemical s h i f t s d o w n f i e l d from the corresponding s u l p h u r compounds, S 0 ( S 0 3 F ) 2 and S0(S0 3 F)C1 which have t h e i r 1 9 F NMR chemical 44 s h i f t s at -52 .7 and -50 .1 ppm r e s p e c t i v e l y . No f i n e s t r u c t u r e 19 77 or even peak broadening due t o F - Se c o u p l i n g was d e t e c t e d . 77 The Se chemical s h i f t s f o r the compounds o f type 0=SeXY (X,Y = C l , S 0 3 F , F) show the expected t r e n d f o r an i n c r e a s e i n the 77 e l e c t r o n e g a t i v i t y o f X or Y . The Se chemical s h i f t f o r SeOF 2 r e p o r t e d TABLE 37: Raman Spec t ra o f the S o l u t i o n s : S e O C l 2 i n S e O ( S 0 3 F ) 2 and SeOCl i n HS0_F (Frequencies i n Cm *) Mole R a t i o S e O C l 2 : S e O ( S 0 3 F ) 2 Mole R a t i o S e O C l 2 : H S 0 3 F 0:1 1:3 1:1 9:1 1:0 0:1 1:3 175 * (2) 178 (2) 171 C2) 162 (3) 161 (4) 176 (3) 215 (3) 210 (1.5) 210 (.5) 212 (1) 232 (6) 232 (5) 232 CD 254 (2) 255 (3) 265 (10) 268 (5) 276 CD 277 (3) 279 (3) 311 (4) 311 (2) 347 (4.5) 390 (1) 390 CD 411 (2) sh 391 (10) 390 (10) 405 (8) 405(3) sh 446 C4) 436 (10) 430(10) 422 (6) 421 (7) sh 452 (4) 435 (10) 551 (2) 551 (.3) 551 C D 555 (10) 556 (1) 588 (2) 588 (.6) 587 (.2) 560 (10) 560 (1) sh 639 (5) 629 (4) 622 635 (2) (1.5) 640 ( 0 M ) 848 (3) 852 CD 839 (.5) 850 (10) 842 (1) 911 (.2) 944 (.2) 944 (2) 944 (2) 968 (6) 951(.4) 968 (.4) 1011 (2.5) 998 CD 1011 (.4) 1044 C4) 1055 C3) 1048 (.5) 1055 C4) 1071 (1.5) 1071 (D 1088 (1) 1220 (6) 1218 C4) 1212 (1.0) 1218 (.2) 1230 (6) 1212 (1) 1430 CD 1428 CD 1405 (.2) 1445 (3) 1440 (.2) 2906 (.4) Numbers i n b r a c k e t s i n d i c a t e r e l a t i v e i n t e n s i t y 187 by B i r c h a l l et a l . i s l i s t e d i n Table38 f o r comparison. A b s o l u t i o n o f S e O C ^ and SeOCSO^F)^ i n a 1:1 mole r a t i o shows a peak at 28 ppm c o n s i s t e n t w i t h the f o r m a t i o n o f SeOfSO^F jCl . A 60% s o l u t i o n o f S e O C ^ i n HSO^F shows a chemical s h i f t at 11 ppm i n agreement w i t h the e q u i l i b r i u m , S e O C l 2 + HS0 3 F = SeO(S0 3 F)Cl + H C l , as suggested by the v i b r a t i o n a l and c o n d u c t i v i t y d a t a . TABLE 38 Chemical S h i f t s o f some Oxy Selenium Compounds C 0 m P ° U n d 1 9 F NMRa 7 7 S e NMRb S e O C l 2 - 0 S e O C l 2 i n HS0 3 F - 1 1 - 5 S e 0 ( S 0 3 F ) C l -47 .7 2 8 - 1 0 S e O ( S 0 3 F ) 2 -48 .6 6 9 - 5 S e O F 2 C 100.6 a chemical s h i f t s i n ppm from i C F C l 3 e x t e r n a l s tandard b chemical s h i f t s i n ppm from S e O C ^ c r e f e r e n c e 212 10.3 .5 Conc lus ions As mentioned b r i e f l y i n the d i s c u s s i o n o f the Raman s p e c t r a o f S e 0 ( S 0 3 F ) 2 and Se0(S0gF)Cl , s t r o n g evidence f o r a s t r e n g t h e n i n g o f the Se=0 bonds v i a pff-dTr bonding e x i s t s . S ince the molecu lar s t r u c t u r e of s e l e n y l compounds o f the type SeOX 2 and SeOXY can be approx imate ly d e s c r i b e d as d i s t o r t e d t e t r a h e d r a l w i t h a s t e r e o c h e m i c a l l y lone p a i r , 194 the same arguments as presented by Cruickshank f o r P-0 and S-0 compounds w i t h t e t r a h e d r a l c o o r d i n a t i o n around P and S r e s p e c t i v e l y , apply h e r e , w i t h the s o l e departure tha t not 3d but 4d outer o r b i t a l s are i n v o l v e d as i r - e l e c t r o n acceptor o r b i t a l s . The v e r y same f e a t u r e s 194 observed by Cruickshank u s i n g e x t e n s i v e l y x - r a y data and by 218 G i l l e s p i e and Robinson , u s i n g v i b r a t i o n a l s p e c t r a as the main source o f i n f o r m a t i o n are found f o r selenium-oxygen compounds. The Se-0 bond d i s t a n c e s and the Se-0 s t r e t c h i n g f o r c e constants show a l i n e a r r e l a t i o n s h i p , both depending s t r o n g l y on the e l e c t r o -n e g a t i v i t y o f X and Y . -These f e a t u r e s have been d i s c u s s e d and t D f . . r u i - *• 181,197,198,213,214 i n t e r p r e t e d by P a e t z o l d i n a s e r i e s o f p u b l i c a t i o n s ' ' . 198 I t has a l s o been noted t h a t f o r compounds o f the type E0X 2 and EOXY (E = S , S e ) , a l i n e a r c o r r e l a t i o n e x i s t s between SO and SeO s t r e t c h i n g f o r c e constants f o r i d e n t i c a l X and Y l i g a n d s . T h i s r e l a t i o n s h i p can be extended to S O ^ , S0 2 XY, S e O ^ and Se0 2XY w i t h replacement o f the lone p a i r i n the t e t r a v a l e n t compounds by another oxygen. The f o l l o w i n g f e a t u r e s are noteworthy : 189 (1) S t r e t c h i n g f o r c e constants (and, o f c o u r s e , element-oxygen s t r e t c h i n g f r e q u e n c i e s ) are h i g h e r f o r the type molecules 50^X^ or SeG" 2X 2 than f o r the type S0X 2 or SeOX 2 > i n d i c a t i n g a h i g h e r degree o f p - r r - d ^ bonding i n the former t y p e . (2) The s t r e t c h i n g f o r c e constants f o r su lphur-oxygen compounds are much h i g h e r than the corresponding selenium-oxygen compounds. These t rends are i l l u s t r a t e d i n Table 39, where a number o f s e l e c t e d examples have been l i s t e d : TABLE 39: S-0 and Se-0 S t r e t c h i n g Force Constants Compound S t r e t c h i n g Force Constant (mdyn/A) S 0 2 F 2 12.04 S0F 2 11.17 S 0 2 ( 0 C H 3 ) 2 10.4 S 0 2 :9 .91 S0C1 2 9.84 S 0 4 = 6.82 S e 0 2 F 2 8/07 SeOF 2 7.91 S e 0 2 ( 0 C H 3 ) 2 7.36 Se0 2 7.53 S e O C l 2 5.74 190 The second f e a t u r e i n d i c a t e s s t r o n g e r o v e r a l l bonding i n S-0 compounds and very l i k e l y s t r o n g e r pn-idir bonding than f o r the corresponding 198 se len ium compounds. P a e t z o l d has found an e m p i r i c a l r e l a t i o n s h i p between the S-0 and Se-0 s t r e t c h i n g f o r c e c o n s t a n t s : ? f s o = 2 - 6 8 7 - f s e 0 " 2 ' 3 0 ; f SeO = ° - 5 9 3 - f S 0 + 1 - 3 7 A p p l y i n g the above i n f o r m a t i o n to the case o f SeOCSO^F)^ where b r i d g i n g between Se(IV) and S(VI) occurs v i a oxygen, i t seems safe to say t h a t c o m p e t i t i o n f o r t r - e l e c t r o n d e n s i t y e x i s t s between Se;(IV) and S ( V I ) , and tha t S(VI) as the b e t t e r TT acceptor i n t h i s system, w i l l withdraw n - e l e c t r o n d e n s i t y from s e l e n i u m , r e s u l t i n g i n weaker and p o l a r bonds. As p o i n t e d out e a r l i e r , the observed e l e c t r i c a l c o n d u c t i v i t y i n d i c a t e s an i o n i c d i s s o c i a t i o n i n the l i q u i d s t a t e . A l s o , the p o s i t i v e l y p o l a r i z e d se lenium w i l l a t t r a c t e l e c t r o n d e n s i t y from c h l o r i n e i n S e ( S 0 3 F ) C l r e s u l t i n g i n the observed r e l a t i v e l y h i g h frequency f o r V g ^ ^ * a n d from oxygen i n the Se=0 u n i t , r e s u l t i n g i n u n u s u a l l y h i g h v a l u e s f o r v C H A P T E R E L E V E N CONCLUSIONS AND SUMMARY The presented exper imenta l r e s u l t s are concerned w i t h three p r i n c i p a l groups o f compounds: (a) o x y f l u o r i d e s o f the halogens and s e l e n i u m , (b) o x y f l u o r o s u l p h a t e s o f the halogens and se len ium and (c) o x y c a t i o n complexes o f p e r f l u o r o a n i o n s w i t h the c e n t r a l atoms o f the c a t i o n s b e i n g C l , I and Se. A l l three c l a s s e s o f compounds can + + ++ be i n t e r p r e t e d as c o n t a i n i n g the o x y c a t i o n s ClO^ , I 0 2 and SeO or SeOX + where X = halogen o r SO^F, or as g i v i n g r i s e to the f o r m a t i o n o f o x y c a t i o n s when used as s o l u t e s i n a s t r o n g p r o t o n i c a c i d s o l v e n t such as H S 0 3 F . 215 187 With the e x c e p t i o n o f SeOF 2 and SeOF^NbF^ , no s t r u c t u r a l d e t a i l s f o r any o f these compounds are a v a i l a b l e at p r e s e n t , and t h e r e f o r e , the bonding i n these compounds must be d i s c u s s e d on the s t r u c t u r a l i n f o r m a t i o n obta ined i n t h i s s t u d y , m a i n l y from v i b r a t i o n a l spectroscopy and s o l u t i o n s t u d i e s . T h i s d i s c u s s i o n can o n l y be q u a l i t a t i v e , which i s the i n t e n t i o n o f the f o l l o w i n g summary o f the bonding i n v o l v e d i n the f o l l o w i n g compounds: (1) C10 2 F - The bonding i n c h l o r y l f l u o r i d e i s best d e s c r i b e d i n terms 114 o f the (TT* - p) a model a l s o employed i n the analogous compounds FNO and F N 0 2 -(2) C l O ^ O ^ F - C h l o r y l f l u o r o s u l p h a t e i s s t r o n g l y d i s s o c i a t e d as a c c o r d i n g to C l O ^ O ^ F = C 1 0 2 + + SO^F , as the s i m p l e s t equat ion to d e s c r i b e the d i s s o c i a t i o n . While the presence of d i s c r e t e C 1 0 2 + c a t i o n s are l i k e l y r e s p o n s i b l e f o r the r e d c o l o u r o f t h i s compound, 192 i t i s b e l i e v e d to be covalent w i t h a h i g h l y p o l a r C ^ C l ^ * - ^"OSC^F g r o u p i n g . On the o ther hand, ( C l O ^ ^ ^ O . ^ i s l i k e l y to be i o n i c , s i m i l a r to ( N C ^ ) 2 ^ 3 ^ 1 0 ^ ' A c r y s t a l s t r u c t u r e d e t e r m i n a t i o n o f (CIC^)2S3O10 would be worth w e l l a t t e m p t i n g . (3) C 1 0 o A s F , , C 1 0 o S b F £ , ( C l O . K S n F , - These white s o l i d s are Z D Z D Z Z O predominant ly i o n i c , but there i s s t r o n g evidence f o r a n i o n - c a t i o n i n t e r a c t i o n v i a f l u o r i n e b r i d g i n g , p o s s i b l y i n v o l v i n g the b^ a n t i b o n d i n g o r b i t a l i o f C 1 0 2 + o r outer 3d o r b i t a l s w i t h lone p a i r o r b i t a l s on f l u o r i n e . The order o f i n t e r a c t i o n appears to be : AsF^ <*'SbFg < SnF^ . T h i s type o f i n t e r a c t i o n has a l s o been "found f o r the c o r r e s p o n d i n g complexes c o n t a i n i n g the c a t i o n s , C 1 F 2 + and B r F 2 + , but not the n i t r o g e n h e t e r o c a t i o n s ko +, N 0 2 + , N 2 F 3 + a n d ^ N F 2 + ' A l l three c h l o r y l compounds appear to be good sources f o r s o l v a t e d C 1 0 2 + cafcions. (4) I 0 2 F - The s t r u c t u r e o f I 0 2 F appears to be p o l y m e r i c , p o s s i b l y i n v o l v i n g both oxygen and f l u o r i n e b r i d g i n g . (5) IC^AsF^ - There does not appear t o be I 0 2 + g r o u P s present i n t h i s compound as t h e r are C 1 0 2 + groups i n C l C ^ A s F ^ . There i s evidence + _ f o r a p o l y m e r i c ( I 0 2 ) n c a t i o n and d i s c r e t e AsF^ a n i o n s . (6) IC^SO^F - I o d y l f l u o r o s u l p h a t e i s p o l y m e r i c w i t h b r i d g i n g b i d e n t a t e f l u o r o s u l p h a t e groups and d i s c r e t e I 0 2 + groups; w i t h i o d i n e - o x y g e n m u l t i p l e bonding . (7) SeOF 2 - Selenium (IV) o x y f l u o r i d e has a t e t r a h e d r a l c o o r d i n a t i o n 214 198 w i t h evidence f o r the SeO bonds h a v i n g s u b s t a n t i a l P ^ - d ^ c h a r a c t e r ' 193 (8) SeOCSO^F)^ - The v i b r a t i o n a l s p e c t r a and e l e c t r i c a l c o n d u c t i v i t y measurements i n d i c a t e very p o l a r Se-OSO^F bonds f o r t h i s compound. The e x i s t e n c e o f the SeOCSO^F)* c a t i o n i n HSO^F and the s u p e r a c i d , H S b F 2 ( S 0 3 F ) 4 , seems l i k e l y . (9) SeOF 2 -NbF 3 - T h i s 1:1 adduct e x i s t s through bonding from oxygen 187 to n iobium . 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S p e c . 23 272 (1967) 204 APPENDIX The f o l l o w i n g a b b r e v i a t i o n s were used throughout t h i s m a n u s c r i p t : asym = asymmetric sym = symmetric s t r = s t r e t c h K = s p e c i f i c c o n d u c t i v i t y e = e x t i n c t i o n c o e f f i c i e n t ,, '} , e = magnitude of the Mossbauer e f f e c t 6 = isomer s h i f t or chemical s h i f t (Mossbauer Spectroscopy) <S = chemical s h i f t (Nuclear Magnetic Resonance) A = quadrupole s p l i t t i n g 

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