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The intercalation of bromine- and iodine fluorosulfate derivatives in solutions of fluorosulfuric acid 1986

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THE INTERCALATION OF BROMINE- AND IODINE FLUOROSULFATE DERIVATIVES I N SOLUTIONS OF FLUOROSULFURIC ACID BY M. SHAH ROSHAN CADER B .Sc . ( H o n s . ) . U n i v e r s i t y o f P e t r o l e u m and M i n e r a l s , D h a h r a n , 1983 A THESIS SUBMITTED I N PARTIAL FULFILLMENT OF THE REQUIREMENT FOR THE DEGREE OF MASTER OF SCIENCE I N THE FACULTY OF GRADUATE STUDIES ( D e p a r t m e n t o f C h e m i s t r y ) We a c c e p t t h i s t h e s i s as c o n f o r m i n g t o t h e r e q u i r e d s t a n d a r d THE UNIVERSITY OF BRITISH COLUMBIA © M.S.R. CADER, September 1986 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 an 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 b y h i s o r h e r 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 h e m i s t r y The 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 1956 Main M a l l V a n c o u v e r , C a n a d a V6T 1Y3 D a t e O c t o b e r 8 , 1986 ABSTRACT The o x i d a t i v e i n t e r c a l a t i o n o f h a l o g e n f l u o r o s u l f a t e d e r i v a t i v e s such as I ( S 0 3 F ) 3 , B r ( S 0 3 F ) 3 , B r S 0 3 F , K [ I ( S 0 3 F ) 4 ] and K [ B r ( S 0 3 F ) 4 ] f r o m s o l u t i o n s i n f l u o r o s u l f u r i c a c i d i n t o g r a p h i t e ( S P - 1 and t o a l e s s e r e x t e n t HOPG) i s s t u d i e d . I n a d d i t i o n , t h e i n t e r c a l a t i o n o f s o l v a t e d c a t i o n s o f t h e t y p e l 2 + and N 0 + i s i n c l u d e d i n t h i s r e s e a r c h as w e l l . The r e s u l t s , s u p p o r t e d b y m i c r o a n a l y s i s , X - r a y powder d i f f r a c t i o n d a t a , Raman f r e q u e n c y s h i f t s , S o l i d s t a t e -^F-NMR s p e c t r o s c o p y and U V - v i s i b l e o p t i c a l s p e c t r a o f t h e s u p e r n a t a n t s o l u t i o n s s u p p o r t t h r e e d i f f e r e n t c o u r s e s o f t h e i n t e r c a l a t i o n r e a c t i o n s : a ) A t v e r y h i g h i n t e r c a l a n t c o n c e n t r a t i o n s ( a b o u t a f i v e f o l d e x c e s s o v e r t h e s t o i c h i o m e t r i c a l l y r e q u i r e d q u a n t i t y ) H a l ( S 0 3 F ) 3 and t h e a n i o n [ H a l ( S 0 3 F > 4 ] " , w i t h H a l - I o r B r , i n t e r c a l a t e w i t h o u t n o t i c e a b l e s o l v e n t c o i n t e r c a l a t i o n . b ) A t i n t e r m e d i a t e c o n c e n t r a t i o n s , s o l v e n t i n t e r c a l a t i o n i s o b s e r v e d . c ) When l o w i n t e r c a l a n t c o n c e n t r a t i o n s a r e u s e d , t h e o n l y i n t e r c a l a t e i s f o u n d t o be t h e s o l v e n t H S 0 3 F . I n a l l t h e i n t e r c a l a t i o n r e a c t i o n s e x c e p t t h e N 0 + ^ s o ^ v ^ p r o m o t e d s y n t h e s i s , f i r s t s t a g e compounds a r e f o r m e d . These s t a g e one G I C ' s w i t h c - a x i s l a y e r r e p e a t d i s t a n c e I c - 8 . 0 A a r e f o u n d f o r t h e i n t e r c a l a n t s I 2 + ( s o i v ) , I ( S 0 3 F ) 3 , B r S 0 3 F and B r ( S 0 3 F ) 3 w i t h c o m p o s i t i o n s C 3 2 S O 3 F . 3 H S O 3 F . 0 - 2 I , C 2 2 l ( S 0 3 F ) 3 , C 1 1 H S 0 3 F . 0 • 5 S 0 3 F . x B r S 0 3 F ( x < 0 . 0 2 5 ) i i i and C 2 6 . 8 B r . 4 S 0 3 F r e s p e c t i v e l y . K [ H a l ( S 0 3 F ) 4 ] <Hal = B r , I ) i n H S O 3 F gave f i r s t s t a g e p r o d u c t s w i t h f o r m u l a e C g 4 B r . 1 1 • 2 2 S 0 3 F and C 8 6 I . 1 0 - 5 1 S O 3 F . The N O + ( s o i v ) i n d u c e d r e a c t i o n l e a d s t o a s t a g e two compound w i t h I c ~ 1 0 . 6 A, and a g e n e r a l c o m p o s i t i o n o f C n x S 0 3 F - y H S 0 3 F i s p r o p o s e d f o r t h e p r o d u c t w h i c h i s c o m p o s i t i o n a l l y inhomogeneous . I n a d d i t i o n , t h e b a s a l p l a n e e l e c t r i c a l c o n d u c t i v i t y enhancements a r e measured f o r t h e g r a p h i t e - l 2 + ( s o i v ) and g r a p h i t e - I ( S 0 3 F ) 3 sys tems e m p l o y i n g a c o n t a c t l e s s r a d i o f r e q u e n c y i n d u c t i o n m e t h o d . - i v - TABLE OF CONTENTS Page ABSTRACT i i TABLE OF CONTENTS i v L IST OF TABLES i x L IST OF FIGURES x GLOSSARY x i i ACKNOWLEDGEMENT x i v I . INTRODUCTION 1 1 . 1 G e n e r a l Comments 2 1.2 H i s t o r i c a l Rev iew 3 1.3 G r a p h i t e 4 1 .4 G r a p h i t e I n t e r c a l a t i o n 7 1.5 Donor I n t e r c a l a t i o n Compounds 11 1.6 A c c e p t o r I n t e r c a l a t i o n Compounds 16 1.7 Methods o f I n t e r c a l a t i o n 18 1 . 7 . 1 D i r e c t I n t e r c a l a t i o n 18 1 . 7 . 2 O x i d a t i o n b y an E x t e r n a l Chemica l S p e c i e s . . 19 1 . 7 . 3 A n o d i c O x i d a t i o n o f G r a p h i t e ( E l e c t r o - c h e m i c a l Method) 20 1 . 7 . 4 I n t e r c a l a t e Exchange and S u b s t i t u t i o n . . . 23 - V - 1 . 7 . 5 I n t e r c a l a t e O x i d a t i o n o r R e d u c t i o n 23 1.8 Rev iew o f S e l e c t e d A c c e p t o r I n t e r c a l a t i o n Compounds . . 24 1 . 8 . 1 G r a p h i t e - H a l o g e n and I n t e r h a l o g e n Compounds . . 24 1 . 8 . 2 G r a p h i t e - F l u o r o s u l f a t e Compounds 26 1 . 8 . 2 a G r a p h i t e F l u o r o s u l f a t e s . . . . . . 27 1 . 8 . 2 b G r a p h i t e - A c i d F l u o r o s u l f a t e s . . . . 27 1 . 8 . 2 c G r a p h i t e - B r o m i n e F l u o r o s u l f a t e s . . 29 1 . 8 . 3 G r a p h i t e I n t e r c a l a t i o n Compounds i n N o n - p r o t o n i c S o l v e n t s 31 1 . 8 . 4 G r a p h i t e I n t e r c a l a t i o n Compounds i n P r o t o n i c S o l v e n t s 32 1 . 8 . 4 a G r a p h i t e - N i t r i c A c i d Compounds . . . 33 1 . 8 . 4 b G r a p h i t e - S o l u t i o n s o f O x i d i z i n g A g e n t s i n P r o t o n i c S o l v e n t s . . . . 34 1.9 I n t e r c a l a t i o n i n F l u o r o s u l f u r i c A c i d 37 1 .10 Enhanced E l e c t r i c a l Conduc tance i n I n t e r c a l a t e d Compounds 4 1 1 . 1 1 Purpose o f T h i s S t u d y 43 I I . EXPERIMENTAL SECTION 45 G e n e r a l Comments 46 2 . 1 A p p a r a t u s 46 2 . 1 . 1 G l a s s Vacuum L i n e 46 2 . 1 . 2 M e t a l F l u o r i n e L i n e 47 2 . 1 . 3 D r y A tmosphere Box 47 3 . 1 . 4 R e a c t i o n V e s s e l s 48 3 . 1 . 5 M i s c e l l a n e o u s G l a s s A p p a r a t u s 50 - v i - 2 . 2 A n a l y t i c a l Equ ipment 56 2 . 2 . 1 V i s i b l e and U l t r a v i o l e t S p e c t r o p h o t o m e t e r . . 56 2 . 2 . 2 I n f r a r e d S p e c t r o p h o t o m e t e r 56 2 . 2 . 3 N u c l e a r M a g n e t i c Resonance S p e c t r o m e t e r 57 2 . 2 . 4 Raman S p e c t r o p h o t o m e t e r 57 2 . 2 . 5 X - r a y Powder D i f f r a c t i o n 59 2 . 3 E l e m e n t a l A n a l y s e s 59 2 . 4 E l e c t r i c a l C o n d u c t i v i t y o f I n t e r c a l a t e d HOPG Samples 60 2 . 5 O t h e r T e c h n i q u e s . . . . . 61 2 . 6 P r e p a r a t i o n and P u r i f i c a t i o n o f Reagen ts 61 2 . 6 . 1 S 2 0 6 F 2 61 2 . 6 . 2 HS0 3 F 63 2 . 6 . 3 l 2 + ( s o l v ) 6 3 2 . 6 . 4 I ( S 0 3 F ) 3 65 2 . 6 . 5 I S 0 3 F 65 2 . 6 . 6 I B r 2 S 0 3 F 66 2 . 6 . 7 K [ I ( S 0 3 F ) 4 ] and K [ B r ( S 0 3 F ) 4 ] 66 2 . 6 . 8 B r ( S 0 3 F ) 3 68 2 . 6 . 9 B r S 0 3 F 68 2 . 6 . 1 0 N0S0 3 F 69 2 . 7 C o m m e r c i a l l y A v a i l a b l e C h e m i c a l s . 69 2 . 7 . 1 G r a p h i t e 69 2 . 7 . 2 O t h e r C h e m i c a l s O b t a i n e d f r o m Commerc ia l Sources 70 - v i i - I I I . SYNTHETIC REACTIONS 72 G e n e r a l Comments 73 3 . 1 I n t e r c a l a t i o n o f l 2 + ( s o l v ) * - n t o G r a p h i t e 74 3 . 2 I n t e r c a l a t i o n o f I ( S 0 3 F ) 3 i n t o G r a p h i t e 75 3 . 2 . 1 H i g h c o n c e n t r a t i o n o f I ( S 0 3 F ) 3 75 3 . 2 . 2 Low c o n c e n t r a t i o n s o f I ( S 0 3 F ) 3 76 3 . 3 I n t e r c a l a t i o n o f K [ I ( S 0 3 F > 4 ] i n t o G r a p h i t e 78 3 . 4 I n t e r c a l a t i o n o f B r ( S 0 3 F ) 3 i n t o G r a p h i t e 79 3 . 5 I n t e r c a l a t i o n o f K [ B r ( S 0 3 F ) 4 ] i n t o G r a p h i t e . . . . 79 3 . 6 I n t e r c a l a t i o n o f B r S 0 3 F i n t o G r a p h i t e 80 3 . 7 I n t e r c a l a t i o n o f N0S0 3 F i n t o G r a p h i t e 81 3 . 8 I n t e r c a l a t i o n o f I B r 2 S 0 3 F i n t o G r a p h i t e 83 3 . 9 R e a c t i o n s o f H a l o g e n F l u o r o s u l f a t e s 83 3 . 9 . 1 A t t e m p t e d O x i d a t i o n o f K [ I ( S 0 3 F > 4 ] 83 3 . 9 . 2 R e a c t i o n o f K [ I ( S 0 3 F ) 4 ] w i t h Excess B r 2 . . . 84 3 . 9 . 3 R e a c t i o n o f I ( S 0 3 F ) 3 w i t h Excess B r 2 . . . . 85 I V . RESULTS AND DISCUSSION 86 G e n e r a l Comments 87 4 . 1 I n t e r c a l a n t P r e p a r a t i o n i n F l u o r o s u l f u r i c A c i d and R e l a t e d S t u d i e s 88 4 . 1 . 1 I 2 + ( s o i v ) . 89 4 . 1 . 2 I S 0 3 F 91 4 . 1 . 3 I ( S 0 3 F ) 3 93 4 . 1 . 4 K [ I ( S 0 3 F ) 4 ] and K [ B r ( S 0 3 F ) 4 ] 95 - v i i i - 4 . 1 . 5 B r ( S 0 3 F ) 3 96 4 . 1 . 6 B r S 0 3 F 97 4 . 1 . 7 NOS0 3F 99 4 . 1 . 8 I B r 2 S 0 3 F 100 4 . 1 . 9 A t t e m p t e d O x i d a t i o n o f K [ I ( S 0 3 F ) 4 ] 101 4 . 1 . 1 0 R e a c t i o n o f K [ I ( S 0 3 F ) ] 4 w i t h Excess B r 2 . . . 102 4 . 1 . 1 1 R e a c t i o n o f I ( S 0 3 F ) 3 w i t h Excess B r 2 . . . 103 4 . 2 I n t e r c a l a t i o n o f I o d i n e C o n t a i n i n g S p e c i e s . . . . 104 4 . 2 . 1 I n t e r c a l a t i o n o f l 2 + ( s o l v ) 104 4 . 2 . 2 I n t e r c a l a t i o n o f I ( S 0 3 F ) 3 109 4 . 2 . 3 I n t e r c a l a t i o n o f K [ I ( S 0 3 F ) 4 ] 115 4 . 2 . 4 A t t e m p t e d I n t e r c a l a t i o n o f I S 0 3 F 117 4 . 3 I n t e r c a l a t i o n o f Bromine C o n t a i n i n g Compounds . . . 119 4 . 3 . 1 I n t e r c a l a t i o n o f B r S 0 3 F 119 4 . 3 . 2 I n t e r c a l a t i o n o f B r ( S 0 3 F ) 3 122 4 . 3 . 3 I n t e r c a l a t i o n o f K [ B r ( S 0 3 F ) 4 ] 124 4 . 3 . 4 I n t e r c a l a t i o n o f I B r 2 S 0 3 F 125 4 . 4 N i t r o s o n i u m I o n ( N 0 + ) P romoted I n t e r c a l a t i o n . . . . 127 4 . 5 G e n e r a l Comments and C o n c l u s i o n 131 REFERENCES 134 - i x - L IST OF TABLES Table Page 1 . 1 A n i s o t r o p y F a c t o r f o r V a r i o u s Types o f G r a p h i t e . . . 8 1.2 P h y s i c a l and T h e r m o c h e m i c a l P r o p e r t i e s o f F l u o r o s u l f u r i c A c i d 38 2 . 1 C h e m i c a l s O b t a i n e d f r o m Commerc ia l Sources 71 3 . 1 M i c r o a n a l y s i s D a t a o f Low C o n c e n t r a t i o n R e a c t i o n s o f I ( S 0 3 F ) 3 77 3 . 2 T y p i c a l M i c r o a n a l y s i s D a t a f o r N0S0 3 F R e a c t i o n s . . 82 4 . 1 S e l e c t e d P h y s i c a l P r o p e r t i e s o f Some H a l o g e n F l u o r o s u l f a t e s 94 4 . 2 T y p i c a l C o n d u c t i v i t y Measurements f o r G r a p h i t e - l 2 + ( s o l v ) Compound 108 4 . 3 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 o f C 2 2 l ( S 0 3 F ) 3 . . . 114 LIST OF FIGURES F i g u r e Page 1 . 1 The U n i t C e l l D i m e n s i o n s o f H e x a g o n a l G r a p h i t e . . . 5 1.2 S t a g i n g i n G r a p h i t e I n t e r c a l a t i o n 13 1.3 The Daumas-Hero ld Mode l f o r S t a g i n g 15 1.4 A p p a r a t u s f o r t h e E l e c t r o c h e m i c a l S y n t h e s i s o f I n t e r c a l a t i o n Compounds 21 1.5 D e n s i t y o f S t a t e s i n P u r e , Reduced and O x i d i z e d G r a p h i t e A c c o r d i n g t o t h e Band Mode l 42 2 . 1 Two P a r t R e a c t i o n V e s s e l s 49 2 . 2 One P a r t R e a c t i o n V e s s e l s 51 2 . 3 One P a r t R e a c t i o n V i a l s 52 2 . 4 S 2 0 6 F 2 A d d i t i o n T r a p 53 2 . 5 Vacuum F i l t r a t i o n A p p a r a t u s 55 2 . 6 B a c k - S c a t t e r i n g A r r a n g e m e n t Used f o r Raman S p e c t r a 58 2 . 7 A p p a r a t u s f o r t h e P r e p a r a t i o n o f S 2 0 g F 2 62 2 . 8 F l u o r o s u l f u r i c A c i d D i s t i l l a t i o n A p p a r a t u s . . . . 64 - x i - 4 . 1 A b s o r p t i o n S p e c t r a o f 1 : 1 and 2 : 1 I 2 / S 2 O 6 F 2 S o l u t i o n s 90 4 . 2 A b s o r p t i o n S p e c t r u m o f I S O 3 F D i s s o l v e d i n F l u o r o s u l f u r i c A c i d 92 4 . 3 UV and V i s i b l e S p e c t r a i n H S O 3 F o f B r 2 : S 2 0 6 F 2 i n V a r y i n g R a t i o s 98 4 . 4 1 9 F - N M R Spec t rum o f C 3 2 S 0 3 F . 3 H S 0 3 F . 0 • 2 1 107 4 . 5 1 9 F - N M R Spec t rum o f C 2 2 I ( S 0 3 F ) 3 I l l 4 . 6 1 9 F - N M R Spec t rum o f C g 6 I . 1 0 • 5 1 S 0 3 F 118 4 . 7 1 9 F - N M R Spec t rum o f C 1 1 H S 0 3 F . - 5 S 0 3 F . x B r S 0 3 F 121 4 . 8 1 9 F - N M R Spec t rum o f G r a p h i t e + N O S O 3 F Compound . . . 129 GLOSSARY A c c e p t o r I n t e r c a l a t i o n Compounds - Compounds f o r m e d f r o m e l e c t r o n a c c e p t o r i n t e r c a l a n t s such as B r 2 and A S F 5 . B o u n d i n g L a y e r s - t h e c a r b o n l a y e r s a d j a c e n t t o an i n t e r c a l a t e l a y e r . Charge T r a n s f e r F a c t o r ( f ) - t h e e x t e n t o f e l e c t r o n r e m o v a l f r o m t h e g r a p h i t e l a t t i c e due t o o x i d a t i o n . D e i n t e r c a l a t i o n - t h e p r o c e s s t h a t o c c u r s a t e l e v a t e d t e m p e r a t u r e s w h i c h p r o d u c e s t h e i n i t i a l i n t e r c a l a n t ( s ) as w e l l as o t h e r v o l a t i l e d e c o m p o s i t i o n p r o d u c t s . Donor I n t e r c a l a t i o n Compounds - compounds s y n t h e s i z e d f r o m e l e c t r o n d o n o r i n t e r c a l a n t s l i k e K and Cs. E x f o l i a t i o n - t h e c o l l a p s e o f t h e l a y e r s t r u c t u r e due t o a n i n t e r c a l a - t i o n - d e i n t e r c a l a t i o n c y c l e . H e x a g o n a l G r a p h i t e - i n f i n i t e s h e e t s o f h e x a g o n s , f o r m e d b y c a r b o n a t o m s , and s t a c k e d t o g e t h e r i n an A B A B . . . . sequence a l o n g t h e c - a x i s d i r e c t i o n . I n t e r c a l a n t ( s ) - m o l e c u l e s , i o n s o r atoms c a p a b l e o f i n s e r t i o n b e t w e e n t h e v a c a n t s i t e s o f t h e h o s t l a t t i c e m a t e r i a l . I n t e r c a l a t e ( s ) - t h e s p e c i e s a c t u a l l y p r e s e n t i n s i d e t h e l a t t i c e a f t e r t h e p r o c e s s o f i n t e r c a l a t i o n . I n t e r c a l a t i o n - t h e i n s e r t i o n o f i o n s , atoms o r m o l e c u l e s g e n e r a l l y i n t o a l a y e r s t r u c t u r e , and s p e c i f i c a l l y b e t w e e n c a r b o n l a y e r s o f t h e g r a p h i t e l a t t i c e . I n t e r i o r L a y e r s - t h e c a r b o n l a y e r s n o t i n d i r e c t c o n t a c t w i t h t h e i n t e r c a l a t e l a y e r . - x i i i - L i m i t i n g C o m p o s i t i o n - d u r i n g t h e i n t e r c a l a t i o n r e a c t i o n , i n t e r c a l a t i o n w i l l n o t p r o c e e d a f t e r r e a c h i n g a l i m i t i n g c o m p o s i t i o n . T h i s compo- s i t i o n may d i f f e r f r o m s t a g e one c o m p o s i t i o n , e . g . t h e GIC C n PFg(CH3N02)y r e f e r s t o a s t a g e two l i m i t i n g c o m p o s i t i o n p r o d u c t . R e s i d u a l Compound - t h e s o l i d m a t e r i a l l e f t a f t e r d e i n t e r c a l a t i o n . S tage I n d e x - t h e number o f c a r b o n l a y e r s s e p a r a t i n g two n e a r e s t i n t e r - c a l a t e l a y e r s . S t a g i n g - t h e r e g u l a r a l t e r n a t i o n o f i n t e r c a l a t e l a y e r s and empty l a m e l - l a r spaces a l o n g t h e v e r t i c a l o r c - a x i s d i r e c t i o n . - x i v - ACKNOWLEDGEMENT I w i s h t o e x p r e s s my s i n c e r e t h a n k s and g r a t i t u d e t o P r o f e s s o r F e l i x A u b k e , f o r t h e g u i d a n c e , u n d e r s t a n d i n g and e x t r e m e c a r e he showed as my r e s e a r c h s u p e r v i s o r d u r i n g t h e e n t i r e c o u r s e o f t h i s s t u d y . Thanks a r e a l s o due t o D r . S. K a r u n a n i t h y , whose u s e f u l c o o p e r a t i o n and h e l p has b e e n an a s s e t t h r o u g h o u t t h i s r e s e a r c h . I am i n d e b t e d t o D r . J o c e l y n W i l l i s , f o r h e r a s s i s t a n c e and p a t i e n c e i n o b t a i n i n g t h e s o l i d s t a t e ^ 9 F-NMR s p e c t r a . P r o f e s s o r J . G . H o o l e y i s t h a n k e d f o r s u p p l y i n g t h e g r a p h i t e and f o r t h e many f r u i t f u l d i s c u s s i o n s r e g a r d i n g t h i s w o r k . I w o u l d a l s o l i k e t o t h a n k P r o f e s s o r J . T r o t t e r , who k i n d l y a l l o w e d t h e use o f X - r a y f a c i l i t i e s . S p e c i a l t h a n k s a r e e x t e n d e d t o Sharon Yap and C o r i n n e Re imer f o r p r o o f - r e a d i n g t h i s t h e s i s , R a n i T h e e p a r a j a h f o r t h e e x c e l l e n t w o r k done i n t y p i n g t h e m a n u s c r i p t , and f i n a l l y , t o my c o w o r k e r s W.V. C i c h a and J . C h r i s t e n s e n f o r t h e i r p l e a s a n t f r i e n d s h i p and h e l p . - 1 - CHAPTER 1 INTRODUCTION - 2 - 1 . 1 G e n e r a l Comments R e s e a r c h on g r a p h i t e i n t e r c a l a t i o n compounds ( G I C ' s ) has undergone e x p l o s i v e and r a p i d g r o w t h d u r i n g t h e l a s t 25 y e a r s . The s y n t h e s i s and c h a r a c t e r i z a t i o n o f G I C ' s have drawn many s p e c i a l i s t s f r o m v a r y i n g f i e l d s s u c h as i n o r g a n i c , p h y s i c a l and s o l i d s t a t e c h e m i s t r y , s o l i d s t a t e p h y s i c s , m a t e r i a l s c i e n c e and e l e c t r i c a l e n g i n e e r i n g t o w o r k t o g e t h e r , and t o r e a c h a b e t t e r u n d e r s t a n d i n g o f t h e c h e m i c a l , s t r u c - t u r a l and e l e c t r o n i c p r o p e r t i e s o f t h i s p o t e n t i a l l y v e r y u s e f u l g roup o f compounds. The use o f g r a p h i t e i n t e r c a l a t i o n compounds as e l e c t r i c a l s t o r a g e sys tems and p l a n a r c o n d u c t o r s 1 " 3 has made them p r i m e c a n d i d a t e s i n i n d u s t r i a l a p p l i c a t i o n s . The u t i l i z a t i o n o f g r a p h i t e as t h e h o s t m a t e r i a l o r m a t r i x i n h e t e r o g e n e o u s c a t a l y s i s ^ has a l s o c o n t r i b u t e d t o t h e p o p u l a r i t y o f i n t e r c a l a t i o n compounds i n b a s i c and i n d u s t r i a l r e s e a r c h . D e t a i l e d r e v i e w a r t i c l e s s u m m a r i z i n g p a s t and r e c e n t advancements b y H e n n i n g 5 and R u d o r f f 6 , H e r o l d e t a l . 7 ( 1 9 6 5 ) , E b e r t 8 ( 1 9 7 5 ) , H e r o l d 9 and F i s c h e r 1 0 ( 1 9 7 0 ) , S e l i g and E b e r t 1 1 ( 1980) and more r e c e n t l y by Forsman e t a l . 1 ^ (1983) r e s p e c t i v e l y have a p p e a r e d d u r i n g t h i s p e r i o d . The f o l l o w i n g o b s e r v a t i o n , made b y a s p e c i a l i s t i n g r a p h i t e i n t e r c a l a - t i o n , summar izes t h e m a j o r , i n i t i a l c h a l l e n g e t o t h e s y n t h e t i c c h e m i s t : "The s y n t h e s i s o f l a m e l l a r compounds poses t h e f o l l o w i n g f u n d a m e n t a l q u e s t i o n t o t h e c h e m i s t : w h i c h r e a g e n t s a r e c a p a b l e o f i n s e r t i o n and u n d e r w h a t c o n d i t i o n s ? " 1 3 More r e c e n t l y , new p r o b l e m s r e g a r d i n g t h e n a t u r e o f t h e i n t e r c a l - a t e d s p e c i e s once i n t e r c a l a t i o n has o c c u r r e d , t h e mechanism b y w h i c h i t - 3 - o c c u r s and t h e e x t e n t o f e l e c t r o n t r a n s f e r b e t w e e n t h e g u e s t o r i n t e r - c a l a t e and t h e h o s t , t h e g r a p h i t e l a t t i c e , have emerged , p r o v i d i n g s u f f i c i e n t s t i m u l u s f o r r e s e a r c h e r s . 1.2 H i s t o r i c a l Rev iew The f i r s t l a m e l l a r o r i n t e r c a l a t i o n compound was made b y S c h a f h e a u t l i n 1840 and 1859^0 b y r e a c t i n g g r a p h i t e w i t h o leum r e s u l t i n g i n o x i d a - t i v e i n t e r c a l a t i o n . C o v a l e n t g r a p h i t e compounds were a l s o known as e a r l y as 1 8 5 9 ^ . These compounds, g e n e r a l l y c a l l e d g r a p h i t e o x i d e o r g r a p h i t e a c i d , a r e s y n t h e s i z e d b y s t r o n g l y o x i d i z i n g sys tems such as s o l u t i o n s o f s o d i u m n i t r a t e o r pe rmangana te i n s u l f u r i c a c i d r e a c t i n g w i t h g r a p h i t e ^ t o p r o d u c e compounds o f f o r m u l a C g 0 2 ( O H ) 2 ^ o r c 8 ° 4 ^ 2 ^ ^ ' ^ " ^ - * s hence i n t e r e s t i n g t o n o t e t h a t s u l f u r i c a c i d as a r e a c t i o n medium p l a y e d an i m p o r t a n t r o l e i n t h e d i s c o v e r y o f b o t h t h e f i r s t GIC and t h e f i r s t c o v a l e n t g r a p h i t e compound. R e s e a r c h on g r a p h i t e i n t e r c a l a t i o n compounds f i r s t r e a c h e d a peak d u r i n g 1959-1960 w i t h t h e v a s t m a j o r i t y o f t h e e f f o r t d i r e c t e d t o w a r d s t h e i r s y n t h e s i s . I n t h e l a t e 1 9 7 0 ' s , m e c h a n i s t i c s t u d i e s and t h e use o f p h y s i c a l methods i n t h e s t r u c t u r a l e l u c i d a t i o n o f G I C ' s became p r o m i n e n t . A t p r e s e n t , i n t e n s e r e s e a r c h a c t i v i t y on t h e e l e c t r o n i c s t r u c t u r e and two d i m e n s i o n a l p h y s i c a l p r o p e r t i e s , n o v e l s y n t h e t i c r o u t e s and m e c h a n i s t i c p a t h w a y s i n t h e i r p r e p a r a t i o n c o n t i n u e as t h e cause o f p o t e n t i a l a p p l i - c a t i o n o f G I C ' s becomes i n c r e a s i n g l y w i d e r . I n 1959 , H e n n i n g ^ l i s t e d - 4 - a b o u t t h r e e dozen known compounds w h i c h s p o n t a n e o u s l y f o r m i n t e r c a l a t i o n o r l a m e l l a r compounds. T o d a y , t h e m e t a l c h l o r i d e s a l o n e c l a i m a l a r g e number o f i n t e r c a l a t i o n compounds, and t h e t o t a l o f a l l known i n t e r c a l - a n t s and t h e i r p r o d u c t s i s now s e v e r a l t i m e s l a r g e r t h a n i n 1959 . L o o k i n g b a c k , i t a p p e a r s t h a t r e s e a r c h on G I C ' s has e v o l v e d f r o m an o b s c u r e f i e l d , r e m i n i s c e n t o f a lchemy i n t h e M i d d l e A g e s , i n t o a h i g h l y c h a l l e n g i n g , m u l t i f a c e t e d s c i e n t i f i c e n d e a v o u r . Much o f t h e c r e d i t f o r t h i s a c h i e v e m e n t mus t go t o t h e d e v e l o p m e n t o f c h e m i c a l l y p u r e , h i g h l y o r d e r e d , and u n i f o r m s y n t h e t i c g r a p h i t e , r e s u l t i n g i n a g r e a t e r r e p r o - d u c i b i l i t y o f r e s u l t s t h a n h a d been p o s s i b l e w i t h n a t u r a l g r a p h i t e s . Some i m p o r t a n t a s p e c t s o f g r a p h i t e i t s e l f w i l l now be d i s c u s s e d i n t h e f o l l o w i n g s e c t i o n . 1.3 G r a p h i t e The s t r u c t u r e o f h e x a g o n a l g r a p h i t e , t h e most common p o l y m o r p h i c f o r m , i s shown i n F i g . 1 . 1 . I n f i n i t e p l a n a r s h e e t s o f h e x a g o n s , f o r m e d b y c a r b o n a t o m s , a r e s t a c k e d t o g e t h e r t o g i v e a l a y e r s t r u c t u r e t o t h e g r a p h i t e l a t t i c e . The i n t r a l a y e r C-C b o n d d i s t a n c e i s 1 .42 A, w h i c h i s s l i g h t l y l e s s t h a n t h e C-C d i s t a n c e o f 1.54 A i n d i a m o n d . P l a n a r i t y w i t h i n t h e l a y e r s and bond a n g l e s o f 120° s u g g e s t t h e i n v o l v e m e n t o f c a r b o n s p ^ h y b r i d o r b i t a l s t o f o r m a - b o n d s . The r e m a i n i n g v a l e n c e e l e c t r o n s r e s i d e i n a t o m i c o r b i t a l s p e r p e n d i c u l a r t o t h e i n f i n i t e s h e e t s and hence c o n t r i b u t e t o d e l o c a l i z e d w-bonds t o p r o d u c e a p o l y a r o m a t i c s y s t e m . I t i s t h i s w - e l e c t r o n d e n s i t y i n t h e v a l e n c e bond w h i c h i s Figure 1.1: The Unit Cell Dimensions of Hexagonal Graphite. - 6 - r e s p o n s i b l e f o r t h e two d i m e n s i o n a l m e t a l l i c c o n d u c t a n c e i n t h e b a s a l p l a n e . The i n t e r l a y e r s p a c i n g i n t h e l a t t i c e i s 3 .35 A, much t o o l o n g f o r c o v a l e n t bond f o r m a t i o n b u t c o n s i s t e n t w i t h t h e v i e w t h a t t h e s e c a r b o n p l a n e s a r e h e l d t o g e t h e r b y r e l a t i v e l y weak Van d e r Waals f o r c e s . As seen f r o m F i g . 1 . 1 , t h e c a r b o n l a y e r s i n h e x a g o n a l g r a p h i t e a r e n o t d i r e c t l y s u p e r i m p o s a b l e and show an ABAB s t a c k i n g sequence . The weak n a t u r e o f t h e i n t e r l a y e r f o r c e s i n g r a p h i t e i s r e s p o n s i b l e f o r i t s use as a s o l i d , h i g h t e m p e r a t u r e l u b r i c a n t , where t h e l a y e r s c a n s l i d e e a s i l y i n a h o r i z o n t a l d i r e c t i o n . A s e c o n d f o r m o f g r a p h i t e , c a l l e d r h o m b o h e d r a l g r a p h i t e , d i f f e r s i n t h e l a y e r s t a c k i n g sequence , w h i c h i s ABCABC. T h i s p o l y m o r p h i c f o r m i s r a r e and has n o t b e e n u s e d e x t e n s i v e l y as a h o s t s p e c i e s i n g r a p h i t e i n t e r c a l a t i o n . A l l w o r k d e s c r i b e d i n t h i s t h e s i s w i l l i n v o l v e h e x a g o n a l g r a p h i t e o n l y . G r a p h i t e u s e d i n i n t e r c a l a t i o n r e a c t i o n s d i f f e r s f r o m g r a p h i t e used as e l e c t r o d e m a t e r i a l i n i n d u s t r i a l e l e c t r o l y s i s , i n n u c l e a r r e a c t o r s as m o d e r a t o r s o r as c o m b u s t i o n m a t e r i a l . I t must meet t h e r e q u i r e m e n t s o f h i g h p u r i t y and o r d e r . Fo r p r a c t i c a l p u r p o s e s , g r a p h i t e may be c l a s s i - f i e d i n t o two b r o a d g r o u p s : n a t u r a l g r a p h i t e and s y n t h e t i c o r p y r o l y t i c g r a p h i t e . B o t h have been u s e d e x t e n s i v e l y i n g r a p h i t e i n t e r c a l a t i o n , b u t t h e d i s a d v a n t a g e i n u s i n g n a t u r a l g r a p h i t e i s i t s u n c e r t a i n and v a r i a b l e p u r i t y . U s u a l l y i r o n , c a l c i u m , and o t h e r m i n e r a l s such as s i l i c a t e s and c a r b o n a t e s a r e p r e s e n t as i m p u r i t i e s a n d , i n a d d i t i o n , many n a t u r a l g r a p h i t e s have c r y s t a l d e f e c t s , w h i c h c o u l d i n t e r f e r e w i t h b o t h t h e i n t e r c a l a t i o n p r o c e s s ^ 1 and t h e i n t e r p r e t a t i o n and r e p r o d u c i b i - l i t y o f r e s u l t s . N e v e r t h e l e s s , n a t u r a l g r a p h i t e w h i c h has been sub- - 7 - j e c t e d t o e x t e n s i v e p u r i f i c a t i o n p r o c e s s e s f i n d s use i n i n t e r c a l a t i o n r e a c t i o n s . P y r o l y t i c g r a p h i t e i s a m o n o l i t h i c g r a p h i t e m a t e r i a l w i t h a h i g h d e g r e e o f p r e f e r r e d c r y s t a l l o g r a p h i c o r i e n t a t i o n o f t h e c - a x i s . I t i s made b y p y r o l y s i s o f s m a l l h y d r o c a r b o n s and s u b s e q u e n t h e a t t r e a t m e n t a t t e m p e r a t u r e s above 2100 K o r by t h e c h e m i c a l v a p o r d e p o s i t i o n - m e t h o d . A p p l i c a t i o n o f h i g h p r e s s u r e and t e m p e r a t u r e s (above 2800 K) p r o d u c e s so c a l l e d H i g h l y O r i e n t e d P y r o l y t i c G r a p h i t e ( H O P G ) 2 2 . HOPG, w h i c h i s a v a i l a b l e i n p l a t e s , e x h i b i t s a h i g h l y o r d e r e d s t r u c t u r e w i t h n e a r l y p a r a l l e l c a r b o n l a y e r s i n t h e b a s a l p l a n e . T h i s f o r m has been u s e d e x t e n s i v e l y i n i n t e r c a l a t i o n r e a c t i o n s , and i t was u s e d d u r i n g t h i s s t u d y i n o r d e r t o measure enhanced e l e c t r i c a l c o n d u c t i v i t i e s . As c a n be seen f r o m T a b l e 1 . 1 , n a t u r a l and s y n t h e t i c g r a p h i t e e x h i b i t q u i t e d i f f e r e n t p h y s i c a l p r o p e r t i e s i n a - and c - a x e s . The a n i s o t r o p y r a t i o (aa/oc) i s f a i r l y l o w f o r n a t u r a l g r a p h i t e as compared t o s y n t h e t i c g r a p h i t e . SP-1 g r a p h i t e ( s p e c t r o s c o p i c g r a d e ) , w h i c h was u s e d i n a l l o u r s y n t h e t i c r e a c t i o n s , i s a h i g h l y p u r i f i e d n a t u r a l g r a p h i t e o f g r a i n s i z e a b o u t 5 0 - 1 0 0 m i c r o n s . I t i s made f r o m Madagascar g r a p h i t e and t r e a t e d w i t h HC1 and HF t o remove b a s i c i m p u r i t i e s . A C l 2 s t r e a m a t h i g h t e m p e r a t u r e i s t h e n a p p l i e d t o remove any m e t a l l i c components p r e s e n t . 1 .4 G r a p h i t e I n t e r c a l a t i o n A number o f t e r m s u n i q u e t o g r a p h i t e c h e m i s t r y a r e now i n t r o d u c e d . - 8 - T a b l e 1 . 1 A n i s o t r o p y f a c t o r f o r v a r i o u s t y p e s o f g r a p h i t e M a t e r i a l T ( K ) cr-CohnT 1 m " 1 ) w a ( ) N a t u r a l g r a p h i t e ( C e y l o n , M e x i c o ) N a t u r a l g r a p h i t e ( C e y l o n ) N a t u r a l g r a p h i t e ( T i c o n d e r o g a ) N a t u r a l g r a p h i t e ( T i c o n d e r o g a ) N a t u r a l g r a p h i t e ( T i c o n d e r o g a ) K i s h g r a p h i t e 300 300 300 300 300 300 8 .3 x 1 0 4 1 0 4 1 . 5 - 2 . 3 x 1 0 4 2 x 1 0 4 3 .3 x 1 0 4 1 . 3 - 1 . 5 x 1 0 4 100 100 100 -170 130 80 P y r o l y t i c c a r b o n 300 + ( T d = 2200°C) P y r o l y t i c c a r b o n 300 + ( T d = 2500°C) P y r o l y t i c g r a p h i t e 300 • (HTT - 3000°C) HOPG 300 ( a n n e a l e d 3 5 0 0 ° ) 125 83 385 590 5500 5000 5200 3800 + f r o m r e f e r e n c e 8 9 . T d = D e p o s i t i o n t e m p e r a t u r e . HTT = Hea t T r e a t m e n t T e m p e r a t u r e . - 9 - and d e f i n e d . I n t e r c a l a t i o n r e f e r s t o t h e i n s e r t i o n o f i o n s , atoms o r m o l e c u l e s g e n e r a l l y i n t o a l a y e r s t r u c t u r e and s p e c i f i c a l l y b e t w e e n c a r b o n l a y e r s o f t h e g r a p h i t e l a t t i c e ^ * • ^ 2 . The p l a n a r i t y o f t h e l a y e r s i n t h e h o s t l a t t i c e i s r e t a i n e d i n t h e i n t e r c a l a t i o n p r o c e s s . The s t a c k i n g o r d e r , i n t e r l a y e r s e p a r a t i o n , and t o a f a r l e s s e r e x t e n t i n t r a l a y e r b o n d d i s t a n c e s may a l l be changed due t o i n t e r c a l a t i o n . M o l e c u l e s , i o n s o r atoms c a p a b l e o f such i n s e r t i o n a r e t e r m e d i n t e r c a l a n t s . The s p e c i e s a c t u a l l y p r e s e n t i n s i d e t h e l a t t i c e a f t e r i n t e r c a l a t i o n has t a k e n p l a c e i s c a l l e d i n t e r c a l a t e . D e p e n d i n g o n t h e n a t u r e o f t h e ' g u e s t - h o s t ' i n t e r a c t i o n , i n t e r c a l a n t and i n t e r c a l a t e may d i f f e r i n t h e i r e l e c t r o n i c s t r u c t u r e , e l e c t r o n i c c h a r g e , m o l e c u l a r s t r u c t u r e and even i n t h e i r c h e m i c a l i d e n t i t y . A c l a s s i f i c a t i o n o f G I C ' s may be b a s e d on t h e n a t u r e o f t h e g u e s t - h o s t i n t e r a c t i o n : Donor G I C ' s a r e f o r m e d b y e l e c t r o n d o n o r i n t e r c a l a n t s s u c h as p o t a s s i u m and c e s i u m . A c c e p t o r compounds a r e s y n t h e s i z e d f r o m e l e c t r o n a c c e p t o r i n t e r c a l a n t s such as B r 2 and A S F 5 . I n donor i n t e r c a l a t i o n compounds, t h e I n t e r c a l a n t I s an e f f e c t i v e r e d u c i n g a g e n t , w h i l e a c c e p t o r G I C ' s a r e f o r m e d b y r e l a t i v e l y m i l d o x i d i z i n g a g e n t s , i . e . B r 2 . When a s t r o n g o x i d i z i n g a g e n t such as F 2 i s u s e d as t h e i n t e r c a l a n t , t h e p o l y a r o m a t i c c h a r a c t e r o f t h e g r a p h i t e i s l o s t , t h e p l a n a r i t y o f t h e c a r b o n l a y e r s i s d e s t r o y e d and c o v a l e n t C-F bond f o r m a t i o n o c c u r s w i t h b o n d i n g d e s c r i b e d b y sp^ c a r b o n h y b r i d o r b i t a l s . The r e s u l t i n g c o v a l e n t g r a p h i t e compounds a r e i n s u l a t o r s , o f t e n w h i t e o r g r e y i n c o l o r and have c o m p o s i t i o n s o f - C F . A s h e e t - l i k e n o n - p l a n a r s t r u c t u r e e x i s t s i n t h e s e compounds w i t h F F i n t r a l a y e r c o n t a c t s . - 10 - The c h e m i c a l n a t u r e o f t h e i n t e r c a l a n t s d e t e r m i n e s t h e d i r e c t i o n o f c h a r g e t r a n s f e r d u r i n g i n t e r c a l a t i o n , r e s u l t i n g i n a c c e p t o r o r d o n o r GIC f o r m a t i o n . I n a c c e p t o r i n t e r c a l a t i o n compounds f o r m e d b y o x i d a t i v e i n t e r c a l a - t i o n , c o v a l e n t bond f o r m a t i o n (as i n CF) i s seen as t h e l i m i t i n g case i n o x i d a t i o n . I n c o n t r a s t t o c o v a l e n t bond f o r m a t i o n , i n t e r c a l a t i o n i s p a r t i a l l y r e v e r s i b l e . The compounds t h u s f o r m e d b y i n t e r c a l a t i o n a r e u s u a l l y s e n s i t i v e t o w a t e r and o r g a n i c s o l v e n t s , whereas c o v a l e n t compounds a r e s t a b l e u n d e r t h e s e c o n d i t i o n s . H e a t i n g o f c o v a l e n t compounds p r o d u c e s v o l a t i l e l o w m o l e c u l a r w e i g h t m o l e c u l e s s u c h as C O 2 and C F 4 , w h i l e i n t e r c a l a t i o n compounds u n d e r g o deintercalation. T h i s p r o c e s s , o c c u r r i n g a t e l e v a t e d t e m p e r a - t u r e s , p r o d u c e s t h e i n i t i a l i n t e r c a l a n t as w e l l as o t h e r v o l a t i l e d e c o m p o s i t i o n p r o d u c t s . The s o l i d m a t e r i a l l e f t ( t e r m e d ' r e s i d u e c o m p o u n d ' ) has a c o m p o s i t i o n w h i c h i s d e p e n d e n t on t h e d e i n t e r c a l a t i o n t e m p e r a t u r e and may be d i f f e r e n t f r o m g r a p h i t e , e . g . d e i n t e r c a l a t i o n o f C n A s F 5 may r e s u l t i n a r e s i d u e compound w i t h a s m a l l f l u o r i n e c o n t e n t . These r e s i d u e compounds a r e u s u a l l y p o o r l y u n d e r s t o o d and r a r e l y i n v e s - t i g a t e d . I n t h e case where i n t e r c a l a t i o n i s r e v e r s i b l e , an i n t e r e s t i n g t e c h n i c a l a p p l i c a t i o n r e s u l t s : an i n t e r c a l a t i o n - d e i n t e r c a l a t i o n c y c l e w i l l l e a d t o a c o l l a p s e o f t h e l a y e r s t r u c t u r e ( c a l l e d e x f o l i a t i o n ) y i e l d i n g g r a p h i t e w i t h a l a r g e r s u r f a c e a r e a . T h i s b r i n g s up a n o t h e r i n t e r e s t i n g a s p e c t . Mere a d s o r p t i o n o f t h e i n t e r c a l a n t , t e r m e d c a p i l - l a r y c o n d e n s a t i o n , on t h e GIC s u r f a c e can o c c u r w h i c h a g a i n i s a l i m i t - i n g c a s e . A p p l i c a t i o n o f a dynamic vacuum w i l l u s u a l l y remove such e x c e s s s u r f a c e a d s o r b e d i n t e r c a l a n t s . 11 - A f i n a l comment i s g i v e n b e l o w r e g a r d i n g t h e two c o n t r a s t i n g t y p e s o f i n t e r c a l a t i o n , i . e . o x i d a t i o n and r e d u c t i o n . O x i d a t i o n w i l l g e n e r a t e u s u a l l y C n + - p o s i t i v e l y c h a r g e d g r a p h i t e l a y e r s ( a n d r e d u c t i o n , C n " - n e g a t i v e l y c h a r g e d l a y e r s ) . The e x t e n t o f e l e c t r o n r e m o v a l i s t e r m e d t h e c h a r g e t r a n s f e r f a c t o r ( f ) , and r e p r e s e n t s a c h a r a c t e r i s t i c q u a n t i t y f o r a g i v e n GIC. The r e d u c e d e l e c t r o n d e n s i t y i n t h e v a l e n c e bond ( c a r r i e r d e n s i t y ) r e s u l t s i n a l o w e r i n g o f t h e F e r m i l e v e l and p - t y p e c o n d u c t a n c e enhancement . F i l l i n g i n t e r s t i t i a l space w i t h o p p o s i - t e l y c h a r g e d , g e n e r a l l y m o l e c u l a r i n t e r c a l a t e a n i o n s w i l l i n c r e a s e t h e a n i s o t r o p y o f e l e c t r i c a l c o n d u c t a n c e , w i t h enhanced c o n d u c t a n c e i n t h e a b - p l a n e and r e d u c e d c o n d u c t a n c e i n t h e c - a x i s d i r e c t i o n . C o n v e r s e l y , r e d u c i n g a g e n t s a r e commonly atoms ( e . g . L i , K) w h i c h w i l l d o n a t e e l e c t r o n s i n t o t h e empty c o n d u c t a n c e b o n d c a u s i n g a r i s e i n t h e F e r m i l e v e l and n - t y p e c o n d u c t a n c e enhancement w i t h r e d u c e d a n i s o t r o p y o f c o n d u c t a n c e due t o t h e a t o m i c n a t u r e o f t h e i n t e r c a l a t e a n i o n . I n t e r e s t i n g l y , d o n o r G I C ' s have f o u n d e x t e n s i v e use as mode l r e d u c i n g a g e n t s , whereas r e s e a r c h on a c c e p t o r GICs has f o c u s s e d more on t h e r e s u l t i n g e l e c t r o n i c f e a t u r e s . 1.5 Donor I n t e r c a l a t i o n Compounds W h i l e n o t d i r e c t l y p e r t i n e n t t o t h i s s t u d y , t h i s b r i e f summary s e r v e s two p u r p o s e s : a ) t o i l l u s t r a t e t h e u n p r e d i c t a b l e n a t u r e o f i n t e r c a l a t i o n , and - 12 - b ) t o i n t r o d u c e t h e i m p o r t a n t c o n c e p t o f s t a g i n g . L i t h i u m , p o t a s s i u m , r u b i d i u m and c e s i u m (and t h e i r v a p o r s ) r e a c t w i t h g r a p h i t e t o g i v e d o n o r t y p e i n t e r c a l a t i o n c o m p o u n d s ^ 3 . 2 4 w i t h i n t e r l a y e r s e p a r a t i o n s o f 5-6 A. However , sod ium does n o t i n t e r c a l a t e , and a s a t i s f a c t o r y e x p l a n a t i o n i s s t i l l t o be f o u n d . The r e a c t i o n b e t w e e n p o t a s s i u m and g r a p h i t e p r o d u c e s a compound w i t h a l i m i t i n g c o m p o s i t i o n o f CsK, w h i c h i s c a l l e d a f i r s t s t a g e compound, i m p l y i n g a l l g a l l e r i e s i n t h e g r a p h i t e l a t t i c e a r e f i l l e d . H i g h e r s t a g e compounds w i t h s t o i c h i o m e t r i e s o f C ^ 2 n M c o u l d be s y n t h e s i z e d b y e i t h e r c o n t r o l l i n g t h e i n t e r c a l a t i o n t i m e , t e m p e r a t u r e o r i n t e r c a l a n t c o n c e n - t r a t i o n o r b y p a r t i a l d e i n t e r c a l a t i o n v i a c o n t r o l l e d h e a t i n g . The g r a p h i t e - l i t h i u m r e a c t i o n u n d e r e x t r e m e c o n d i t i o n s y i e l d s a GIC o f f o r m u l a C g n L i 2 5 , 2 6 I n i n t e r c a l a t e d d o n o r compounds, t h e i n t e r l a y e r s e p a r a t i o n d i s t a n c e s t e n d t o be s m a l l e r t h a n t h a t o f a c c e p t o r compounds. T h i s i s due t o t h e f a c t t h a t d o n o r i n t e r c a l a n t s a r e u s u a l l y m i c r o a t o m i c w h i l e a c c e p t o r i n t e r c a l a n t s a r e m o l e c u l a r a g g r e g a t e s b y n a t u r e . The c o n c e p t o f s t a g i n g i n g r a p h i t e i n t e r c a l a t i o n i m p l i e s t h a t i n t e r c a l a t i o n compounds a t e q u i l i b r i u m f a v o u r a s i t u a t i o n where t h e i n t e r l a m i n a r r e g i o n s o r g a l l e r i e s a r e e i t h e r c o m p l e t e l y f i l l e d o r t o t a l l y e m p t y l ^ . A c l a s s i c a l v i e w o f s t a g i n g i s shown i n F i g . 1 . 2 . An i n t e r c a l a n t w i l l f i l l o r v a c a t e a g i v e n l a y e r o r g a l l e r y i n t h e g r a p h i t e l a t t i c e b e f o r e a n o t h e r l a y e r i s e i t h e r a t t a c k e d , opened up and f i l l e d o r v a c a t e d . T h i s w i l l r e s u l t i n a r e g u l a r a l t e r n a t i o n o f i n t e r c a l a n t l a y e r s and empty l a m e l l a r s p a c e s . The s t a g e i n d e x , d e n o t e d by n , i s d e f i n e d as t h e number o f c a r b o n l a y e r s s e p a r a t i n g two n e a r e s t i n t e r c a l a n t l a y e r s . Hence a s t a g e i n d e x - 13 - — ooo ooo = OOO = ooo <ro = ooo ooo ooo First Second TTiird Carbon Layer Intercalate Layer Figure 1.2: Staging in Graphite Intercalation. - 14 - o f 1 i m p l i e s t h e h i g h e s t p o s s i b l e i n t e r c a l a n t c o n c e n t r a t i o n , t h e l o w e s t c a r b o n c o n t e n t o f t h e compound and a s i n g l e u n i q u e i n t e r l a y e r s e p a r a t i o n d i s t a n c e a l o n g t h e c - a x i s I c , w h i c h i s c h a r a c t e r i s t i c o f t h e i n t e r c a l - a t e ' s space r e q u i r e m e n t . I n t e r c a l a t i o n compounds w i t h h i g h e r s t a g e i n d e c e s i m p l y a l o w e r i n t e r c a l a n t t o c a r b o n r a t i o . W i t h i n t e r l a y e r s e p a r a t i o n s i n empty l a y e r s - 3 .35 A as i n g r a p h i t e i t s e l f , t h e i n t e r l a y e r s e p a r a t i o n f o r a s t a g e n compound becomes I c + ( n - 1 ) 3 .35 A, w i t h I c t h e i n t e r l a y e r s e p a r a t i o n i n t h e c o r r e s p o n d i n g f i r s t s t a g e compound. Due t o i n t e r c a l a t i o n , some o r d e r i n g t a k e s p l a c e i n t h e g r a p h i t e l a y e r s as w e l l . The c a r b o n l a y e r s a d j a c e n t t o an i n t e r c a l a t e l a y e r a r e c a l l e d bounding layers , w h i l e t h e o t h e r l a y e r s , n o t I n d i r e c t c o n t a c t w i t h t h e i n t e r c a l a t e a r e t e r m e d Interior layers. The l a t t e r l a y e r s have t h e ABAB l a y e r r e p e a t p a t t e r n , w h i c h i s s i m i l a r t o t h e g r a p h i t e l a t t i c e a r r a n g e m e n t , b u t t h e b o u n d i n g l a y e r s may have ABAB, AAA o r a m i x t u r e o f b o t h t h e s e r e p e a t s e q u e n c e s 2 ^ . I n p r a c t i c e , h o w e v e r , t h e i n f i n i t e r e g u l a r s t a c k i n g o f l a y e r s w i t h i n t e r c a l a t e l a y e r s i n s e r t e d i n e v e r y n t h i n t e r c a r b o n l a y e r space a l o n g t h e c - a x i s , w h i c h i s i m p l i e d b y t h e c l a s s i c a l m o d e l , may n o t be o b s e r v e d . The a b i l i t y o f i n t e r c a l a t e s p e c i e s t o d i s t r i b u t e b e t w e e n t h e g r a p h i t e l a y e r s w i l l r e s u l t i n t h e f o r m a t i o n o f m i x e d s t a g e compounds. I n o r d e r t o accommodate t h i s m a c r o s c o p i c d i s t r i b u t i o n o f I n t e r c a l a t e s p e c i e s , Daumas and H e r o l d p r o p o s e d a domain ( o r p l e a t e d l a y e r ) model f o r t h e l a y e r s t a c k i n g p a t t e r n i n i n t e r c a l a t e d compounds 2 ** ( F i g . 1 . 3 ) . The h o s t c a r b o n and i n t e r c a l a t e l a y e r s t a c k i n g a r r a n g e m e n t f o r compounds o f s t a g e o n e , two and t h r e e a r e shown i n F i g . 1 . 3 . The b a s i c a d v a n t a g e o f t h i s c o n c e p t i s t h a t i t becomes e a s i e r t o e x p l a i n s t a g e t r a n s f o r - - 15 - STAGE ONE STAGE TWO X z. CARBON LAYER INTERCALATE LAYER Figure 1.3: The Daumas-Herold Model for Staging. - 16 m a t i o n s w h i c h , a c c o r d i n g t o t h i s m o d e l , i n v o l v e movement o f i n t e r c a l a t e i s l a n d s . These i s l a n d s a r e f o r m e d by t h e n o n - c o n t i n u o u s o c c u p a t i o n o f a l l t h e i n t e r l a y e r r e g i o n s by t h e i n t e r c a l a t e s p e c i e s . As shown by t h e o r e t i c a l s t u d i e s 2 9 • ^ , t h e i n t e r c a l a t e m o l e c u l e s o r atoms b e t w e e n t h e same two c a r b o n l a y e r s w i l l e x e r t an a t t r a c t i v e f o r c e t o f o r m two d i m e n s i o n a l i s l a n d s w h i l e t h o s e b e t w e e n d i f f e r e n t p a i r s o f c a r b o n l a y e r s w i l l r e p e l each o t h e r . T h i s w i l l e v e n t u a l l y l e a d t o t h e f o r m a t i o n o f domains o f i n t e r c a l a t e s w i t h m a c r o s c o p i c s i z e s . T h i s f o r m a t i o n o f domains a l o n g t h e c - a x i s c o u l d be t e r m e d as s t a g i n g , w h i c h e x p l a i n s t h e e x i s t e n c e o f m i x e d s t a g e s . M i x e d s t a g e f o r m a t i o n t a k e s p l a c e when a m i x t u r e o f d o m a i n s , each o f them p u r e l y f o r m e d , i s o b s e r v e d a l o n g t h e c - a x i s o f t h e g r a p h i t e l a t t i c e . The X - r a y d i f f r a c t i o n m e t h o d , u s e d w i d e l y t o d e t e r m i n e t h e s t a g e ( s ) o f an i n t e r c a l a t e d compound, u s u a l l y g i v e s s t a t i s t i c a l l y a v e r a g e d i n f o r - m a t i o n on t y p i c a l l y ( 0 . 1 mm)-* c r y s t a l s and c a n g e n e r a l l y r e v e a l t h e i r a v e r a g e s t a g e o r d e r i n g - ^ . P r e s e n t d a y h i g h r e s o l u t i o n e l e c t r o n m i c r o - s c o p y , s u p p o r t e d b y c o m p u t e r s i m u l a t i o n s , c o u l d be u s e d t o image and l o c a t e i n t e r c a l a t e d s p e c i e s d i r e c t l y - * 2 . 1.6 A c c e p t o r I n t e r c a l a t i o n Compounds These c o m p r i s e a r a t h e r l a r g e g r o u p o f compounds, and some more r e l e v a n t members o f t h i s g roup w i l l be i n t r o d u c e d i n a subsequen t s e c t i o n . A f e w g e n e r a l comments i n o r d e r t o b e t t e r c h a r a c t e r i z e t h i s g r o u p w i l l be s u m m a r i z e d . U n l i k e donor i n t e r c a l a n t s , w h i c h a r e b a s i - - 17 - c a l l y r e s t r i c t e d t o m e t a l s , a c c e p t o r i n t e r c a l a n t s span a w i d e r range and v a r i e t y . The f o l l o w i n g d i f f e r e n c e s as compared t o d o n o r G I C ' s , c o n t r i b u t e t o t h e i r e x t e n s i v e c h e m i s t r y and p r a c t i c a l i n t e r e s t . A c c e p t o r i n t e r c a l a n t s a r e : a ) m o l e c u l a r - r e s u l t i n g i n a g r e a t e r a n i s o t r o p y w i t h t y p i c a l I c v a l u e s o f a b o u t 8 A; b ) o x i d i z e r s - t h i s l e a d s t o p - t y p e c o n d u c t a n c e w i t h t h e F e r m i l e v e l l o w e r e d r a t h e r t h a n r a i s e d . I n t e n s e p r a c t i c a l i n t e r e s t i n t h e s e t y p e s o f m a t e r i a l s have been shown; c ) c a p a b l e f r e q u e n t l y o f d i r e c t i n t e r c a l a t i o n on a c c o u n t o f t h e i r p h y s i c a l and c h e m i c a l p r o p e r t i e s . T h i s makes them s u i t a b l e sys tems f o r m e c h a n i s t i c s t u d i e s ( e . g . g r a p h i t e - B r 2 s y s t e m ) . The i n t e r c a l a t e i n a c c e p t o r G I C ' s may o r may n o t d i f f e r f r o m t h e i n t e r c a l a n t I n i t s m o l e c u l a r s t r u c t u r e . Two examples a r e g i v e n b e l o w t o i l l u s t r a t e t h i s d i f f e r e n c e : 1 . S 2 O 5 F 2 , b i s ( f l u o r o s u l f u r y l ) p e r o x i d e g e n e r a t e s ' S O 3 F r a d i c a l s , w h i c h i n t u r n a c t as one e l e c t r o n o x i d i z e r and p r o d u c e t h e S O 3 F " i o n on i n t e r c a l a t i o n . 2 . A S F 5 , a r s e n i c ( V ) f l u o r i d e i n t e r c a l a t e s i n t o g r a p h i t e t o g i v e a compound o f l i m i t i n g c o m p o s i t i o n C g A s F 5 3 3 . However , t h e i n t e r c a l a t e a p p e a r s t o be d e s c r i b e d b y t h e e q u i l i b r i u m 3ASF5 + 2e ^ = + - 2 A s F g ' + A s F j . T h e r e f o r e , i n t h i s s y s t e m t h e e x t e n t o f o x i d a t i o n , t h e e q u i l i b r i u m p o s i t i o n and t h e e x a c t c o n c e n t r a t i o n s o f t h e v a r i o u s i n t e r c a l a t e s p e c i e s a r e s u b j e c t t o much c o n t r o v e r s y , and a r e n o t e a s i l y deduced f r o m t h e s t o i c h i o m e t r i c c o m p o s i t i o n . - 18 1.7 Methods o f I n t e r c a l a t i o n The p r i n c i p a l methods u s e d i n g r a p h i t e a c c e p t o r i n t e r c a l a t i o n s y n t h e s i s c o u l d be c l a s s i f i e d a s : d i r e c t i n t e r c a l a t i o n ; o x i d a t i o n b y an e x t e r n a l c h e m i c a l s p e c i e s w h i c h w i l l n o t i t s e l f i n t e r c a l a t e ; a n o d i c o x i d a t i o n o f g r a p h i t e ( m o d i f i c a t i o n o f me thod 1 . 7 . 2 ) ; i n t e r c a l a t e exchange and s u b s t i t u t i o n ; i n t e r c a l a t e o x i d a t i o n o r r e d u c t i o n . A b r i e f summary o f each t e c h n i q u e i s g i v e n b e l o w : 1.7.1 D i r e c t I n t e r c a l a t i o n T h i s method i s t h e most common and most g e n e r a l t y p e u s e d f o r t h e s y n t h e s i s o f g r a p h i t e i n t e r c a l a t i o n compounds and a p p l i e s w e l l t o b o t h a c c e p t o r and d o n o r compound p r e p a r a t i o n . The method c o u l d be i l l u s - t r a t e d b y t h e v e r y s i m p l e e q u a t i o n : n C ( s ) + X ( l , g , s o l u t i o n ) > c n x ( s ) Compounds such as S 2 0 g F 2 , H N O 3 and BrSC^F c o u l d a c t as t h e i n t e r c a l a n t X t o y i e l d t h e C n X p r o d u c t . Some i m p l i c a t i o n s a r e : 1 . S o l u t i o n s r e q u i r e t h e p r e s e n c e o f a s u i t a b l e s o l v e n t , and hence s o l v e n t c o - i n t e r c a l a t i o n may o c c u r . 2 . T e m p e r a t u r e , p r e s s u r e , c o n c e n t r a t i o n , and r e a c t i o n t i m e a r e a l l f a c t o r s c o n t r o l l i n g t h e e x t e n t o f i n t e r c a l a t i o n ; 3 . F o l l o w i n g i n t e r - c a l a t i o n b y w e i g h t becomes t h e s i m p l e s t method o f p r o d u c t a n a l y s i s , - 19 t e r m e d g r a v i m e t r y . T h i s method may be u n r e l i a b l e i n t h e case o f s o l u - t i o n i n t e r c a l a t i o n due t o c o - i n t e r c a l a t i o n t a k i n g p l a c e . 4 . S t r i c t l y p h y s i c a l c r i t e r i a a r e u s e d t o c h a r a c t e r i z e i n t e r c a l a n t s , i . e . an i n t e r - c a l a n t mus t be a g a s , a l i q u i d o r a s o l i d w i t h a m e a s u r a b l e v a p o r p r e s s u r e o r c a p a b l e o f d i s s o l v i n g i n o r d e r t o i n t e r c a l a t e i n t o g r a p h i t e . F i n a l l y , t h e c o m p o s i t i o n o f t h e GIC C n X i s i n f l u e n c e d b y t h e p h y s i c a l d i m e n s i o n s o f X and t h e d e g r e e t o w h i c h i n t e r l a m e l l a r spaces a r e f i l l e d . 1.7.2 Oxidation by an External Chemical Species T h r e e c o n t r a s t i n g examples a r e p r e s e n t e d b e l o w t o i n d i c a t e t h e scope o f t h i s t e c h n i q u e : 1 . Gaseous o x i d i z e r - C l£ a i d e d i n t e r c a l a t i o n o f A I C I 3 3 4 ; 2 . S o l i d m o l e c u l a r o x i d i z e r - Cr03 a c t s as t h e o x i d i z e r i n H 2 S O 4 I n t e r c a l a t i o n 3 - * ; 3 . I o n i c o x i d i z e r - N 0 2 + a l l o w i n g i n t e r c a l a t i o n o f MFg" i o n 3 ^ ; M - P o r Sb. I n a l l t h e above s y s t e m s , t h e o x i d i z i n g s p e c i e s w i l l g e n e r a l l y n o t i n t e r c a l a t e i n t o g r a p h i t e . I t f a c i l i t a t e s t h e i n t e r c a l a t i o n o f n e u t r a l m o l e c u l e s and a n i o n s b y g i v i n g t h e g r a p h i t e l a t t i c e a p o s i t i v e c h a r g e . A I C I 3 v a p o r r e a c t s w i t h g r a p h i t e o n l y i n t h e p r e s e n c e o f C I 2 g a s , 3 4 and a s t a g e one compound, C + 3 Q A 1 C 1 4 " . 2 A 1 C 1 3 i s o b t a i n e d . The r o l e o f C I 2 as t h e o x i d i z e r i s e v i d e n t i n t h e f o l l o w i n g m e c h a n i s m 3 7 , 3 8 : - 20 C 1 2 ( g ) ^ * c l2(ads) 1/2 A l 2 C l 6 ( g ) • A l C l 3 ( g ) m r A l C l 3 ( a d s ) A l c l 3 ( a d s ) + c l2(ads) ^ * c l + A I C I 4 - ( a d s ) C n + C l + . A l C l 4 - ( a d s ) + m A l C l 3 ( g ) > C n +AlCl 4-.mAlCl 3 + C l ' ( a d s ) 2 c l"(ads) > c l2(ads) > c l2(g) In H2S04 intercalation, Cr0 3 reacts i n i t i a l l y with graphite and compounds of general formula C+24n.HS04*.2H2S04 are synthesized 3 5. Strong acids such as H C I O 4 and CF3C00H could be intercalated in a similar manner, using Cr0 3 or other oxidants such as KMn04, Mn02 and Pb02. As shown by B i l l a r d et a l . 3 6 N0 2 + ion, coming from JK^SbFg or N02PFg, oxidizes the graphite in a nitromethane solution, and a product with formula C + 2 3 nMF 6 (CH3N02) could be obtained (M - Sb or P). The value of Y Is given as between 1.7 and 2.5. 1.7.3 Anodic Oxidation of Graphite (Electrochemical Method) This method is primarily used for the intercalation of protonic acids when graphite acts as the anode (Fig. 1.4). denotes the graphite anode and the voltage drop between and C 2 and Is monitored continuously during the intercalation process. A non-aqueous protonic - 21 k2>J E l e c t r o m e t e r V o l t a g e Recorder Pt E l e c t r o l y t e C 2& C 2 a r e G r a p h i t e E l e c t r o d e s Rj& R 2 a r e R e s i s t a n c e s F i g u r e A p p a r a t u s f o r t h e E l e c t r o c h e m i c a l S y n t h e s i s o f I n t e r c a l a t i o n Comoounds. T r e s i s o f 22 - a c i d such as H 2 S 0 4 o r H S O 3 F f u n c t i o n s as e l e c t r o l y t e i n t h e ( e l e c t r o l y - s i s ) c e l l . As i n t e r c a l a t i o n p r o c e e d s , a n i o n s and n e u t r a l a c i d m o l e c u l e s w i l l i n s e r t i n t o t h e g r a p h i t e anode , and a b u i l d - u p o f v o l t a g e t a k e s p l a c e w i t h t i m e . Fo r t h e two p r o t o n i c a c i d s C F 3 S O 3 H and H 2 S 0 4 , t h e f o l l o w i n g r e a c t i o n s c o u l d be w r i t t e n 3 9 : 26C + ( x + 1) C F 3 S O 3 H > C + 2 6 C F 3 S 0 3 " . x C F 3 S 0 3 H + 0 . 5 H 2 ( x = 1 . 6 3 ) 24C + ( x + 1) H 2 S 0 4 > C + 2 4 H S 0 4 - . x H 2 S 0 4 + 0 . 5 H 2 ( x - 2 . 4 2 ) An i n t e r e s t i n g comment c o n c e r n s t h e a n o d i c o x i d a t i o n i n H S O 3 F . T h i s a c i d d i s s o c i a t e s t o g i v e S 0 3 F " as w e l l as H2S03F 4". The a n i o n S 0 3 F " can be o x i d i z e d t o S O 3 F * o r S 2 0 g F 2 a c c o r d i n g t o : 2 S 0 3 F " > S 2 0 6 F 2 + 2e " Hence, t h e a n o d i c o x i d a t i o n j u s t d i s c u s s e d may be i n t e r p r e t e d as i n t e r - c a l a t i o n o f S 2 0 g F 2 i n t h e p r e s e n c e o f an e x c e s s amount o f H S O 3 F . Some c o n d i t i o n a l sys tems where a n o d i c o x i d a t i o n i s u s e d t o s y n t h e s - i z e G I C ' s i n v o l v e m e t a l c h l o r i d e s such as B i C l 3 and T e C l 4 , where t h e i r m e l t s f u n c t i o n as e l e c t r o l y t e s 4 0 o r l i t h i u m s a l t s such as L i P F g , L iAsFg and L i S b F g , w h i c h g i v e compounds o f g e n e r a l f o r m u l a C + 2 4 X " . 4 ( s o l v e n t ) . These a r e e l e c t r o l y z e d i n p r o t i c d o n o r s o l v e n t s 4 1 . - 23 - 1 . 7 . 4 I n t e r c a l a t e Exchange and S u b s t i t u t i o n T h i s method was f i r s t u s e d i n t h e c o n v e r s i o n o f C+24HSC>4~ t o t h e c o r r e s p o n d i n g p e r c h l o r a t e p r o d u c t , a c c o r d i n g t o ^ 2 : C + 24HS04* + excess HC10 4 > C + 2 4 C 1 0 4 " + H2SC>4 Recen t w o r k done b y o u r g roup has p r o v i d e d some a d d i t i o n a l examples o f i n t e r c a l a t e exchange r e a c t i o n s ^ 3 : C 7 S O 3 F + e x c e s s H S O 3 C F 3 — > C 1 2 S 0 3 C F 3 + C 7 S 0 3 F + e x c e s s S b F 5 — > CgSbFg + C 1 2 B r S 0 3 F + excess H S O 3 C F 3 — > C 1 2 S03CF3 + S u b s t i t u t i o n r e a c t i o n s a r e g e n e r a l l y r a r e and even when t h e y o c c u r , i n t e r p r e t a t i o n o f r e s u l t s c o u l d be d i f f i c u l t s i n c e e q u i l i b r i u m m i x t u r e s c o u l d f o r m a t c e r t a i n s t a g e s o f t h e r e a c t i o n : f o r e x a m p l e , when Cg n AsF5 was t r e a t e d w i t h NC^SbFg, t h e r e s u l t i n g p r o d u c t showed t h e f o l l o w i n g i n t e r c a l a t e s : S b F 6 ~ , A s F g " , S b F 5 , A s F 5 and A s F 3 W . 1 . 7 . 5 I n t e r c a l a t e O x i d a t i o n o r R e d u c t i o n T h i s me thod i s i l l u s t r a t e d b y s t u d y i n g t h e r e d o x r e a c t i o n o f t h e - 24 - g r a p h i t e - F e C l 3 s y s t e m . The i n t e r c a l a t e d FeCl3 c o u l d be r e d u c e d e i t h e r t o FeCl2 b y t r e a t i n g t h e i n t e r c a l a t e d p r o d u c t w i t h H 2 4 5 o r t o F e 2 0 3 b y h e a t i n g i n an o x y g e n s t r e a m 4 0 . A t t e m p t s t o r e d u c e t h e i n t e r c a l a t e d m e t a l h a l i d e s t o p u r e m e t a l , where t h e r e s u l t i n g p r o d u c t i n t u r n c o u l d be u s e d as p o t e n t i a l c a t a l y s t s , have n o t been s u c c e s s f u l so f a r 4 ^ . I n t e r c a l a t e o x i d a t i o n has a l s o been o b s e r v e d i n g r a p h i t e - f l u o r o s u l f a t e compounds. When C ^ B r S G ^ F was r e a c t e d w i t h S 2 0 g F 2 , a compound o f c o m p o s i t i o n C i g B r ( S O 3 F ) 3 was o b t a i n e d 4 3 . T h i s p r o d u c t may l a t e r u n d e r g o i n t e r c a l a t e r e d u c t i o n , t o y i e l d t h e i n i t i a l compound, i . e . C ^ 2 B r S 0 3 F , i n t h e f o l l o w i n g manner : 3 C 1 6 B r ( S 0 3 F ) 3 + 3 B r 2 — > 4 C 1 2 B r S 0 3 F + 5 B r S 0 3 F 1.8 Rev iew o f S e l e c t e d A c c e p t o r I n t e r c a l a t i o n Compounds A b r i e f summary o f some o f t h e g r a p h i t e a c c e p t o r sys tems w h i c h a r e r e l e v a n t t o t h i s w o r k i s g i v e n i n t h e f o l l o w i n g s e c t i o n . 1 . 8 . 1 G r a p h i t e - H a l o g e n and I n t e r h a l o g e n Compounds Of t h e d i a t o m i c h a l o g e n s , o n l y b r o m i n e , B r 2 and p o s s i b l y c h l o r i n e , C l 2 a r e known t o i n t e r c a l a t e i n t o g r a p h i t e t o g i v e t r u e i n t e r c a l a t i o n compounds. The b r o m i n e i n t e r c a l a t i o n compounds o f g r a p h i t e have been known s i n c e 1 9 3 3 , 4 7 and t h e c o m p o s i t i o n C 4 n B r ( n > 2) has been f o u n d f o r - 25 - t h e s e c o m p o u n d s ^ . I t i s i n t e r e s t i n g t o n o t e t h a t t h e l i m i t i n g c o m p o s i t i o n c o r r e s p o n d s t o a s t a g e two compound. A l t h o u g h f o r m u l a e such as C + n B r " . 3 B r 2 were g i v e n t o e a r l y i n t e r c a l a t i o n p r o d u c t s * * 9 , e f f o r t s t o i d e n t i f y s p e c i e s such as B r " o r B r 3 " i n t h e l a t t i c e have p r o v e n f r u i t l e s s , and l a t e r r e s e a r c h i n d i c a t e d t h a t t h e r e i s v e r y l i t t l e c h a r g e t r a n s f e r b e t w e e n t h e i n t e r c a l a n t and t h e h o s t l a t t i c e i n B r 2 i n t e r c a l a - t i o n ^ . I n t e r c a l a t i o n o f c h l o r i n e l e d t o compounds o f f o r m u l a C 4 n C l (3 < n < 5) w i t h i n t e r p l a n a r s p a c i n g o f a b o u t 7 . 0 A5 -̂. I n t e r c a l a t i o n compounds o f i n t e r h a l o g e n s such as I C 1 and I B r have 49 b e e n known f o r somet ime , whereas t e r n a r i e s s u c h as C n B r x C l ^ . x have o n l y r e c e n t l y been c h a r a c t e r i z e d 5 2 . The g r a p h i t e - B r C l s y s t e m i s r a t h e r c o m p l i c a t e d s i n c e B r C l can d i s p r o p o r t i o n a t e r e a d i l y : 2 B r C l - » B r 2 + C l 2 . When r e a c t e d w i t h g r a p h i t e , a p r o d u c t o f f o r m u l a C g B r g . 5 5 C I 0 . 4 5 f ° r t h e r i c h e s t compound was f o u n d 5 2 . W i t h i n c r e a s i n g c o o r d i n a t i o n , p o l a r i z a t i o n o f t h e X-Y bond i s u s u a l l y a c c e n t u a t e d , and hence p o l y a t o m i c i n t e r h a l o g e n s have s t r o n g e r o x i d i z i n g a b i l i t i e s . B r F 3 , I C I 3 and I F 5 a l l u n d e r g o a p p r e c i a b l e a u t o - i o n i z a t i o n i n t h e l i q u i d p h a s e 5 3 : 2BrF3 —— J" B r F 2 + + B r F 4 * ; T 2 < ^ c , * I C 1 2 + + I C I 4 " ; 2 I F 5 -, * TF 4+ + I F 6 " . O x i d a t i o n o f t h e g r a p h i t e l a t t i c e , f o r e x a m p l e , may be c a r r i e d o u t a c c o r d i n g t o ^ 2 : 2nC + 2 I C 1 2 + 2 C n + + I C 1 + - I 2 C 1 6 - 26 - The o b s e r v a t i o n t h a t i n I F 5 i n t e r c a l a t i o n , HF->4 o r B F 3 1 1 c a t a l y s e s t h e r e a c t i o n l e d t o t h e p o s s i b l e I F 4 + a n i o n f o r m a t i o n m e c h a n i s m 1 ^ , 1 F 5 + mHF „ I F ^ F ' m + l o r I F 5 + B F 3 n * I F / , + B F / , ' T h i s c o u l d t a k e p l a c e more e a s i l y t h a n b y a u t o i o n i z a t i o n , and i n t e r c a l a t i o n compounds o f I F 5 may, t h e r e f o r e , c o n t a i n H F 2 " o r B F 4 " i o n s i n a d d i t i o n t o t h e m o l e c u l a r p e n t a f l u o r i d e . 1 . 8 . 2 G r a p h i t e - F l u o r o s u l f a t e Compounds T h i s g r o u p c o n s i s t s o f t h r e e t y p e s o f i n t e r c a l a t i o n compounds: a ) G r a p h i t e f l u o r o s u l f a t e s - CnSC>3F. b ) G r a p h i t e a c i d f l u o r o s u l f a t e s - C n S 0 3 F . ( H S O 3 F ) , and c ) G r a p h i t e b r o m i n e f l u o r o s u l f a t e s - C n B r ( S 0 3 F ) m , m - 1 , 3 and C 2oBrF(S03F) 2. These compounds w i l l be b r i e f l y r e v i e w e d i n t h e f o l l o w i n g subsec- t i o n s . Our r e s e a r c h g r o u p has been a c t i v e l y i n v o l v e d i n t h e r e - i n v e s t i g a t i o n o f g r o u p a) and b ) g r a p h i t e compounds, w h i l e a l l G I C ' s i n g r o u p c ) were r e p o r t e d b y us f o r t h e f i r s t t i m e 4 3 . I n a l l i n s t a n c e s , c o m p l e t e c h a r a c t e r i z a t i o n b y g r a v i m e t r y , m i c r o a n a l y s i s and p h y s i c a l methods s u c h as X - r a y powder d i f f r a c t i o n , 1 9F - N M R , ^H-NMR and Raman - 27 - s p e c t r o s c o p y , l e a v e s l i t t l e d o u b t r e g a r d i n g t h e i r c o m p o s i t i o n s 1 . 8 . 2 a G r a p h i t e - F l u o r o s u l f a t e s The o x i d a t i v e i n t e r c a l a t i o n o f b i s ( f l u o r o s u l f u r y l ) p e r o x i d e , S 2 0 g F 2 i n t o g r a p h i t e was f i r s t u n d e r t a k e n b y B a r t l e t t e t a l . 5 5 . A f i r s t s t a g e compound o f c o m p o s i t i o n CgSC^F was r e p o r t e d b y t h i s g r o u p , b u t l a t e r r e s e a r c h c a r r i e d o u t b y H o o l e y 5 ^ u s i n g gas phase i n t e r c a l a t i o n o f S 2 0 g F 2 i n t o v a r i o u s t y p e s o f g r a p h i t e showed a l i m i t i n g c o m p o s i t i o n o f C 7 S O 3 F . S y n t h e s i s p e r f o r m e d b y o u r g r o u p , i n b o t h l i q u i d and gas p h a s e s * * 3 , c o n f i r m e d t h e above r e s u l t s . The b o n d i n g mode l f o r C 7 S O 3 F has b e e n p r o p o s e d , and a number o f c o n v e r s i o n r e a c t i o n s a r e r e p o r t e d * * 3 and have b e e n m e n t i o n e d i n e a r l i e r s e c t i o n s . 1 . 8 . 2 b G r a p h i t e - A c i d F l u o r o s u l f a t e s I t has g e n e r a l l y b e e n r e c o g n i z e d t h a t f l u o r o s u l f u r i c a c i d , HSC^F, b y i t s e l f does n o t i n t e r c a l a t e w e l l , p r o d u c i n g o n l y a f i f t h s t a g e m a t e r i a l 5 ^ . Hence t h e f o r m a t i o n o f l o w e r s t a g e compounds w o u l d have t o I n v o l v e an o x i d i z i n g a g e n t . E l e c t r o c h e m i c a l o x i d a t i o n , f i r s t r e p o r t e d b y U b b e l o h d e and c o w o r k e r s * * 2 and l a t e r b y H e r o l d e t a l . 5 * * i s s a i d t o p r o d u c e a f i r s t s t a g e i n t e r c a l a t i o n compound f o r m u l a t e d as C + 2 4 • S O 3 F " . m H S G ^ F , w i t h m = 2.0-2.5. Some e v i d e n c e f o r t h e f o r m a t i o n o f a " C ^ 2 + compound" b y o v e r o x i d a t i o n i s f o u n d i n t h e same s t u d y where t h e - 28 f o l l o w i n g sequence i s p r o p o s e d : C + 2 4 S 0 3 F " • m H S 0 3 F > c 2 + . 2 S 0 3 F - . ( m - l ) H S 0 3 F + H + + e" W i t h C r 0 3 as an o x i d i z e r , a f i r s t s t a g e compound o f f o r m u l a C^+-^ HS0 3 F i s s a i d t o be o b t a i n e d - * 7 , and t h e r e s u l t s o f a Raman s t u d y o f t h i s compound-* 9 were i n t e r p r e t e d i n t e r m s o f t i g h t l y p a c k e d a c i d m o l e c u l e s i n t h e l a m e l l a r s p a c e s . Yaddaden e t a l . ^ ° u s e d HS0 3 F and S 0 3 o r C r 0 3 as o x i d i z i n g a g e n t s and c a r r i e d o u t s y n t h e t i c r e a c t i o n s b e t w e e n t h e a c i d s o l u t i o n s and Madagascar g r a p h i t e . A l t h o u g h S 0 3 was u s e d as an o x i d a n t , a d d i t i o n a l S 0 3 w o u l d a l w a y s be p r e s e n t whenever HS0 3 F i s u s e d due t o t h e e q u i l i b r i u m . H S 0 3 F ( 1 ) S 0 3 ( g ) + H F ( g ) F i r s t s t a g e compounds were o b t a i n e d f o r r e a c t i o n s b e t w e e n g r a p h i t e and H S 0 3 F / S 0 3 , w i t h c o m p o s i t i o n s C i o H S 0 3 F t o C 5 H S 0 3 F . These v a l u e s show a p r o n o u n c e d d e v i a t i o n f r o m t h e v a l u e s g i v e n b y o t h e r a u t h o r s f o r c h e m i c a l o x i d a t i o n ^ 9 • . When d i l u t e s o l u t i o n s o f S 0 3 i n HS0 3 F were u s e d , t h e ma in i n t e r c a l a n t was f o u n d t o be S 0 3 . Fo r t h e case where t h e a c i d was r e l a t i v e l y f r e e o f S 0 3 , C r 0 3 had t o be u s e d as t h e o x i d i z i n g a g e n t t o y i e l d f i r s t s t a g e i n t e r c a l a t i o n p r o d u c t s . T h i s s t u d y c l e a r l y shows t h a t t h e p u r i t y o f t h e a c i d c o u l d p l a y an i m p o r t a n t r o l e i n t h e i n t e r c a l a t i o n o f H S 0 3 F i n t o g r a p h i t e . 29 - The i n t e r c a l a t i o n p r o c e s s c a r r i e d o u t i n f l u o r o s u l f u r i c a c i d may, t h e r e f o r e , have m a j o r l i m i t a t i o n s and c o u l d l e a d t o d i f f i c u l t i e s when one a t t e m p t s t o e x p l a i n p o s s i b l e c o m p o s i t i o n s and m e c h a n i s t i c p a t h w a y s . I n o r d e r t o a v o i d i m p u r i t y b a s e d p r o b l e m s , t h e a c i d u s e d i n o u r w o r k was p u r i f i e d b y t h r e e s u c c e s s i v e d i s t i l l a t i o n s and hence made S O 3 f r e e as much as p o s s i b l e . R e s e a r c h p e r f o r m e d e a r l i e r i n o u r g roup* * 3 showed t h a t H S O 3 F i n t e r c a l a t i o n c o u l d be c a r r i e d o u t r a t h e r c o n v e n i e n t l y b y a s u c c e s s i v e i n t e r c a l a t i o n m e t h o d . The i n i t i a l s t a g e two i n t e r c a l a t i o n p r o d u c t , f o r example ^ S 0 3 F , w h i c h was s y n t h e s i z e d u s i n g g r a p h i t e and S 2 ^ 6 F 2 v a p o r , was r e a c t e d w i t h excess H S O 3 F t o g i v e a s t a g e one t e r n a r y p r o d u c t w i t h c o m p o s i t i o n C 1 4 S O 3 F . 1 . 0 5 H S O 3 F . The s i m u l t a n e o u s i n t e r c a l a t i o n o f H S O 3 F and S 2 0 g F 2 i n d i c a t e d o n l y v e r y s m a l l amounts o f a c i d p r e s e n t i n t h e p r o d u c t . T h i s i s due t o t h e g r e a t e r a b i l i t y o f ^ 2 ^ 6 F 2 t o u n d e r g o o x i d a t i v e i n t e r c a l a t i o n . 1 . 8 . 2 c G r a p h i t e - B r o m i n e F l u o r o s u l f a t e s When g r a p h i t e was r e a c t e d w i t h B r S 0 3 F a t a m b i e n t t e m p e r a t u r e , an i n t e r c a l a t e d s t a g e one p r o d u c t w i t h c o m p o s i t i o n C^2BrS03F was o b t a i n e d * * 3 . The r e a c t i o n b e t w e e n g r a p h i t e and B r S 0 3 F a t e l e v a t e d t e m p e r a t u r e ( 1 0 5 - 1 1 0 ° ) , h o w e v e r , g i v e s a d i f f e r e n t p r o d u c t w i t h s t o i c h i o m e t r y C 2oBrF ( S 0 3 F ) 2 * * 3 . The room t e m p e r a t u r e r e a c t i o n i s assumed t o t a k e p l a c e a s : 12C + B r S 0 3 F > C 1 2 B r S 0 3 F 30 The h i g h t e m p e r a t u r e r e a c t i o n sequence i s p r o p o s e d as f o l l o w s : 3 B r S 0 3 F B r 2 + B r ( S 0 3 F ) 3 f o l l o w e d b y , P a r t i a l B r ( S 0 3 F ) 3 > B r F ( S 0 3 F ) 2 + S 0 3 d e c o m p o s i t i o n 20C + B r F ( S 0 3 F ) 2 > C 2 ( ) B r F ( S 0 3 F ) 2 The r e a c t i o n o f C ^ 2 B r S 0 3 F and excess S 2 0 g F 2 , as shown e a r l i e r , g i v e s an o x i d a t i v e i n t e r c a l a t i o n compound o f f o r m u l a C ^ g B r ( S 0 3 F ) 3 . However , b o t h s t o i c h i o m e t r i c and 1 9 F - N M R e v i d e n c e s u g g e s t t h a t some u n i n t e r c a l a t e d B r ( S 0 3 F ) 3 i s s t i l l p r e s e n t 4 3 , and t h i s e x c e s s m a t e r i a l may be c h e m i - a b s o r b e d on t h e i n t e r c a l a t i o n p r o d u c t . I n summary i t seems t h a t s y n t h e t i c app roaches t o b o t h f l u o r o s u l f a t e and h a l o g e n d e r i v a t i v e s o f g r a p h i t e have r e l i e d e x t e n s i v e l y on t h e d i r e c t i n t e r c a l a t i o n o f B r 2 , C l 2 , I C 1 , I B r o r B r C l , S 2 0 g F 2 , B r S 0 3 F and t o a l e s s e r d e g r e e , on o x i d a t i o n o f g r a p h i t e i n HS0 3 F ( v i a a c h e m i c a l o x i d i z e r o r t h e e l e c t r o c h e m i c a l t e c h n i q u e ) o r t h e o x i d a t i v e c o n v e r s i o n o f a GIC, as e x e m p l i f i e d b y t h e s y n t h e s i s o f C ^ g B r ( S 0 3 F ) 3 . I n o r d e r t o w i d e n t h e scope o f t h e more u s e f u l d i r e c t i n t e r c a l a t i o n m e t h o d , f o r example t o I o d i n e f l u o r o s u l f a t e s o r p e r h a p s I 2 i t s e l f , i t becomes n e c e s s s a r y t o c o n s i d e r d i r e c t i n t e r c a l a t i o n w i t h t h e i n t e r c a l a n t d i s s o l v e d i n a s u i t a b l e s o l v e n t . 31 Two g e n e r a l t y p e s o f s o l v e n t p r o m o t e d i n t e r c a l a t i o n sys tems have b e e n d e s c r i b e d and w i l l now be c o n s i d e r e d : 1 . The use o f n o n - p r o t o n i c s o l v e n t s , 2 . H S O 3 F and o t h e r p r o t o n i c a c i d s as s o l v e n t s . These two sys tems w i l l be d i s c u s s e d b e l o w as p a r t o f t h e r e v i e w on s e l e c t e d i n t e r c a l a t i o n compounds. 1 . 8 . 3 G r a p h i t e - I n t e r c a l a t i o n Compounds I n N o n - p r o t o n i c S o l v e n t s Two i n t e r c a l a t i o n s t u d i e s , c a r r i e d o u t b y H e r o l d e t a l . 3 * * and Forsman e t a l . 6 1 , w i l l be i l l u s t r a t e d i n t h i s s e c t i o n . Of t h e two w o r k s , t h e f i r s t m e n t i o n e d g i v e s more d e t a i l s on p o s s i b l e c o m p o s i t i o n s and t h e n a t u r e o f t h e i n t e r c a l a t e d s p e c i e s . N 0 2 + i o n i s a common o x i d i z e r i n b o t h s y s t e m s . I t was shown b y H e r o l d e t a l . 3 6 t h a t n i t r y l s a l t s s u c h as N O 2 B F 4 , N 0 2 P F g and N 0 2 S b F 6 ( o r t h e n i t r o s y l s a l t NOSbFg) when d i s s o l v e d i n d r y n i t r o m e t h a n e , C H 3 N O 2 , p r o d u c e d N 0 2 + ( o r N 0 + f r o m NOSbFg) i o n s , w h i c h were a b l e t o o x i d i z e g r a p h i t e t o g i v e i n t e r c a l a t i o n compounds. F l u o r o a n i o n s o f s a l t s such as B F 4 " , PFg"  a n c i SbFg" were i n t e r c a l a t e d i n t o p y r o g r a p h i t e , and b y c h e m i c a l a n a l y s e s and X - r a y m e t h o d s , t h e G I C ' s were shown t o have t h e i d e a l c o m p o s i t i o n C + 2 3 n M F g " ( C H 3 N 0 2 ) y , where n I s t h e s t a g e and y - 1 . 7 - 2 . 5 . 1 9 F and 3 1 P NMR s t u d i e s have been c a r r i e d o u t on t h e s e c o n d s t a g e p r o d u c t o f PFg" i n o r d e r t o e s t a b l i s h t h e n a t u r e o f t h e i n t e r c a l a t e d s p e c i e s . The m a i n r e a c t i o n i s t h u s g i v e n a s : - 32 - N 0 2 P F 6 + nC > N 0 2 + C n + P F 6 The s e c o n d s t u d y by Forsman e t a l . , n o t i c a b l y l a c k i n g i n c h e m i c a l and s p e c t r o s c o p i c e v i d e n c e , shows t h e i n t e r c a l a t i o n o f SbFg" o r B F 4 " i n t o g r a p h i t e . N0 2 SbFg and N 0 2 B F 4 were d i s s o l v e d i n t e t r a m e t h y l e n e s u l f o n e ( s u l f o l a n e ) t o g i v e t h e above a n i o n s . N e u t r a l s o l v e n t m o l e c u l e s t o g e t h e r w i t h t h e a n i o n s and p o s s i b l y NG^BF^ o r N0 2 SbFg m o l e c u l e s a r e b e l i e v e d t o i n t e r c a l a t e i n t o g r a p h i t e . No i n f o r m a t i o n on t h e a c t u a l c o m p o s i t i o n o f t h e p r o d u c t s was g i v e n . I t was however o b s e r v e d t h a t t h e r e a c t i o n s a t 40°C gave d i f f e r e n t p r o d u c t s f r o m t h o s e r u n a t room t e m p e r a t u r e . T h i s i s e x p l a i n e d b y a s s u m i n g t h a t t h e amount o f s o l v e n t ( t o g e t h e r w i t h t h e a n i o n s and t h e n e u t r a l m o l e c u l e s ) t h a t i n s e r t s may depend on t h e i n t e r c a l a t i o n t e m p e r a t u r e . S o l v e n t - c o i n t e r c a l a t i o n has a l s o b e e n n o t e d b y H o o l e y , where n i t r o m e t h a n e was f o u n d as an i n t e r c a l a t e d u r i n g t h e s o l u t i o n i n t e r c a l a - t i o n o f F e C l 3 6 2 . 1 . 8 . 4 G r a p h i t e - I n t e r c a l a t i o n Compounds i n P r o t o n i c S o l v e n t s The two s o l v e n t sys tems t h a t a r e t o be d e s c r i b e d i n t h i s s e c t i o n a r e : a ) O x i d i z i n g a c i d s ( e . g . H N O 3 ) and g r a p h i t e sys tems b ) S o l u t i o n s o f o x i d i z i n g a g e n t s i n p r o t o n i c a c i d s and g r a p h i t e s y s t e m s . 33 - 1 . 8 . 4 a G r a p h i t e - N i t r i c A c i d Compounds On a c c o u n t o f i t s s t r o n g o x i d i z i n g a b i l i t y , H N O 3 i s u n i q u e i n a c t i n g b o t h as a s o l v e n t and an o x i d i z i n g a g e n t t o w a r d s g r a p h i t e . On ly gaseous o r l i q u i d n i t r i c a c i d i s i n v o l v e d i n t h e r e a c t i o n w i t h g r a - p h i t e ° . T h i s s y s t e m p r o v i d e d u s e f u l i n f o r m a t i o n r e g a r d i n g t h e r o l e p l a y e d b y t h e s o l v e n t i n i n t e r c a l a t i o n r e a c t i o n s . As s u g g e s t e d b y Forsman, t h e a c t i v e s p e c i e s i n i n t e r c a l a t i o n b y H N O 3 i s t h e n i t r o n i u m i o n 3 7 ' 3 * * . N 0 2 + i s g e n e r a t e d i n t h e l i q u i d phase b y t h e s e l f - d i s s o c i a t i o n o f H N O 3 . I n v a p o r phase i n t e r c a l a t i o n , i t i s o b s e r v e d as a s u r f a c e a d s o r b e d s p e c i e s . The f o l l o w i n g mechanism i s p r o p o s e d f o r t h e v a p o r phase i n t e r c a l a - t i o n 3 8 . H N 0 3 ( g ) — v H N 0 3 ( a d s ) 2 H N 0 3 ( a d s ) N 0 2 + ( a d s ) + N 0 3 " ( a d s ) + H 2 ° c n + N ° 2 + ( a d s ) — > c n + + N 0 2 ( a d s ) N 0 2 ( a d s ) •> N 0 2 ( g ) C. 'n + + N 0 3 " ( a d s ) + C n + . N 0 3  _ . m H N 0 3 The number o f n e u t r a l a c i d m o l e c u l e s m i n t h e p r o d u c t i s s t a t e d as 4 . 5 and 4 . 3 6 ^ , r e s p e c t i v e l y , w i t h m dependen t on t h e p a r t i a l p r e s s u r e o f - 34 - H N O 3 , PHN03> r e s u l t i n g f r e q u e n t l y i n s t a g e t r a n s f o r m a t i o n s . The i n i t i a l i n t e r c a l a t i o n o f H N O 3 i n t o g r a p h i t e t a k e s p l a c e a l o n g t h e b a s a l p l a n e s ^ 9 . T h i s o b s e r v a t i o n i s s i m i l a r t o t h e one made e a r l i e r by H o o l e y d u r i n g t h e i n t e r c a l a t i o n o f b r o m i n e ^ > ^ . The f o l l o w i n g c o n c l u s i o n s c a n be d rawn f r o m t h e above d i s c u s s i o n : a ) H N O 3 i s u n i q u e i n p r o v i d i n g b o t h t h e o x i d i z e r ( N 0 2 + ) and t h e i n t e r c a l a t e s ( N O 3 " and H N O 3 ) . b ) Gas phase i n t e r c a l a t i o n o c c u r s b y a complex mechan ism, b u t a s t r o n g s i m i l a r i t y t o t h e i n t e r c a l a t i o n by B r 2 ( g ) i s n o t e d . c ) C o - i n t e r c a l a t i o n o f a c i d m o l e c u l e s t a k e s p l a c e w i t h r e m o v a l o f H N O 3 b e i n g r e l a t i v e l y e a s y . 1 . 8 . 4 b G r a p h i t e - S o l u t i o n s o f O x i d i z i n g A g e n t s i n P r o t o n i c A c i d s S i n c e t h e f o c u s o f t h i s t h e s i s i s on t h e s y n t h e s i s o f a c c e p t o r G I C ' s i n f l u o r o s u l f u r i c a c i d , a c l o s e r l o o k a t some r e l a t e d sys tems i s now n e c e s s a r y . When c o n s i d e r i n g i n t e r c a l a t i o n i n t o g r a p h i t e u s i n g s o l u t i o n s o f s t r o n g p r o t o n i c a c i d s , two q u i t e d i s t i n c t o b j e c t i v e s emerge : 1) I n t e r c a l a t i o n o f a c i d a n i o n s , p o s s i b l y w i t h c o n c o m i t a n t c o i n t e r - c a l a t i o n o f t h e n e u t r a l a c i d m o l e c u l e s a i d e d b y s u i t a b l e o x i d i z i n g a g e n t s : nC + e x c e s s HX + O x i d i z e r > C nX.mHX 35 - T h i s i s t h e g e n e r a l r o u t e t o a c i d s a l t s , a n d , as shown e a r l i e r , a n o d i c o x i d a t i o n i n s t r o n g a c i d s may be t r e a t e d as a s p e c i a l case w i t h i n t h i s g r o u p . 2 ) The i n t e r c a l a t i o n o f a c c e p t o r compounds, w h i c h w i l l n o t i n t e r c a l a t e b y t h e m s e l v e s f o r p h y s i c a l r e a s o n s , d i s s o l v e d i n p r o t o n i c a c i d s a c t i n g as i o n i z i n g s o l v e n t s : t h e o b j e c t i v e now i s t o i n t e r c a l a t e t h e s o l u t e Y, w i t h p o s s i b l e a c i d c o i n t e r c a l a t i o n a c c o r d i n g t o n C + Y ( s o l v ) > C n Y The l a t t e r c a t e g o r y o f r e a c t i o n s i s o f i n t e r e s t t o us w h i l e t h e f i r s t g r o u p has a l r e a d y been r e v i e w e d 3 5 ' 6 * * . G r a p h i t e i n t e r c a l a t i o n i n c h l o r o s u l f u r i c ( H S O 3 C I ) and f l u o r o s u l - f u r i c ( H S O 3 F ) a c i d s was f i r s t r e p o r t e d b y H e r o l d e t a l . 6 9 - 7 0 . C h l o r o - s u l f u r i c a c i d was u s e d as t h e s o l v e n t i n one s y s t e m , and e l e m e n t a l c h l o r i d e s such as C u C l 2 , Z n C l 2 , P b C l 2 , A I C I 3 , B C I 3 , S b C l 5 , and A U C I 3 were d i s s o l v e d , and t h e r e s u l t i n g s o l u t i o n s were exposed t o g r a p h i t e 6 9 . A l t h o u g h no c h e m i c a l a n a l y s e s o r mechanisms were shown, t h e f o l l o w - i n g c o n c l u s i o n s a r e r e p o r t e d f o r t h e i n t e r c a l a t e d p r o d u c t s : a ) I n s e r t i o n o f a c i d o n l y i s q u o t e d f o r most o f t h e h a l i d e s , i . e . C u C l 2 , Z n C l 2 , M n C l 2 , P b C l 2 , F e C l 2 , P C I 5 , N b C l 5 , e t c . , and an i n t e r - l a y e r s e p a r a t i o n I c o f - 8 . 0 3 A was o b s e r v e d w i t h s t a g e s r a n g i n g f r o m 3 t o 5 . b ) F o r m a t i o n o f t e r n a r y B C I 3 + H S O 3 C I compounds w i t h I c ~ 8 . 3 6 A ( s t a g e 3) was f o u n d f o r B C I 3 . c ) Two phase sys tems were shown t o be p r e s e n t : one g r a p h i t e - H S 0 3 C 1 - 36 phase ( I c ' - 8 . 1 0 A) , one g r a p h i t e - A u C l 3 o r S b C l 5 o r SDCI3 p h a s e . I n a l l c a s e s , t h e X - r a y d i f f r a c t i o n t e c h n i q u e was u s e d as t h e s o l e means o f p r o d u c t c h a r a c t e r i z a t i o n . A s i m i l a r s t u d y was c a r r i e d o u t u s i n g H S O 3 F and m e t a l f l u o r i d e s C u F 2 , N i F 2 , A I F 3 , FeF3, N b F 5 , S b F 5 e t c . by t h e same a u t h o r s 7 0 . No mechanisms were g i v e n f o r any r e a c t i o n s , and c h e m i c a l a n a l y s e s were shown o n l y f o r t h e f i r s t s t a g e g r a p h i t e - S b F 5 compound. I n most c a s e s , t h e t e m p e r a t u r e h a d t o be k e p t a t - 6 0 ° C f o r i n t e r c a l a t i o n t o p r o c e e d . Fo r a l l t h e h a l i d e s o t h e r t h a n SbF5, o n l y H S O 3 F was f o u n d as t h e i n t e r c a l a t e . I n t e r p l a n a r d i s t a n c e s were a b o u t 7 . 9 0 A t o 8 . 0 3 A, w i t h s t a g e s o f 2 t o 4 f o r t h e s e i n t e r c a l a t e d p r o d u c t s . Fo r t h e r e a c t i o n b e t w e e n SbF5 and g r a p h i t e , a f i r s t s t a g e t e r n a r y compound w i t h g e n e r a l f o r m u l a C 7 ( H S 0 3 F ) X « ( S b F 5 ) i _ X r was p r o p o s e d 7 0 , where X and X - l r e p r e s e n t t h e f r a c t i o n a l p r o p o r t i o n s o f H S O 3 F and SbF5 i n t h e f r e e s t a r t i n g m i x t u r e s . The many p o s s i b l e comp lex a s s o c i a t i o n s b e t w e e n H S O 3 F and S b F 5 i s c i t e d as t h e p r i m a r y cause w h i c h makes a c c u r a t e i n t e r p r e t a t i o n o f d a t a d i f f i c u l t . I n summary, t h e s e s t u d i e s a r e r a t h e r f r a g m e n t a r y , and t h e r e s u l t i n g p r o d u c t s a r e p o o r l y c h a r a c t e r i z e d . I t i s u n c l e a r f r o m t h e s e s t u d i e s w h e t h e r o x i d a t i v e i n t e r c a l a t i o n o c c u r s o r n o t , w h e t h e r t h e a c i d o r i t s a n i o n i n t e r c a l a t e o r p e r h a p s even b o t h , and i n w h a t o x i d a - t i o n s t a t e and m o l e c u l a r f o r m i n t e r c a l a t e d s o l u t e i s p r e s e n t . - 3 7 - 1.9 I n t e r c a l a t i o n i n F l u o r o s u l f u r i c A c i d The use o f f l u o r o s u l f u r i c a c i d , H S O 3 F , i n o u r s t u d y as t h e s o l v e n t was c o n s i d e r e d a d v a n t a g e o u s f o r s e v e r a l p h y s i c a l and c h e m i c a l r e a s o n s . H S O 3 F i s c o m m e r c i a l l y a v a i l a b l e , e a s i l y p u r i f i e d b y d i s t i l l a t i o n a t a t m o s p h e r i c p r e s s u r e and w i l l n o t e t c h g l a s s a t room t e m p e r a t u r e when p u r e . Some p h y s i c a l p r o p e r t i e s o f t h e a c i d a r e summar ized i n T a b l e 1 . 2 . The a c i d ' s b r o a d l i q u i d range I s an a s s e t w h i c h p e r m i t s t h e s t u d y o f r e a c t i o n s o v e r a v e r y w i d e t e m p e r a t u r e r a n g e . The l o w v i s c o s i t y o f H S 0 3 F compared t o H 2 S O 4 s i m p l i f i e s many o p e r a t i o n s s u c h as f i l t r a t i o n o r vacuum t r a n s f e r and enhances i o n m o b i l i t y . A l s o , e x c e s s a c i d c a n be removed a t room t e m p e r a t u r e v i a a dynamic vacuum, w h i c h makes i t p o s s i b l e t o o b t a i n G I C ' s f r e e o f s u r f a c e a d s o r b e d f l u o r o s u l f u r i c a c i d . As d i s c u s s e d p r e v i o u s l y , H S O 3 F does n o t i n t e r c a l a t e b y i t s e l f w e l l 5 7 , and hence i d e a l l y f u n c t i o n s as an u n c o m p l i c a t e d s o l v e n t medium i n g r a p h i t e i n t e r c a l a t i o n . I t i s a l s o an e x c e l l e n t i o n i z i n g s o l v e n t on a c c o u n t o f i t s h i g h d i e l e c t r i c c o n s t a n t . M o r e o v e r , t h e h i g h a c i d s t r e n g t h makes i t an i d e a l s o l v e n t f o r n o n - v o l a t i l e , o f t e n s o l i d o r v i s c o u s i n t e r c a l a n t s i n GIC s y n t h e s i s . S i n c e a l m o s t a l l t h e compounds u s e d i n t h i s w o r k u n d e r g o i o n i z a t i o n t o v a r y i n g d e g r e e s i n f l u o r o s u l f u - r i c a c i d , mos t s o l u t e s show b a s i c b e h a v i o r r e s u l t i n g i n i n c r e a s e d S 0 3 F " I o n f o r m a t i o n . I n a d d i t i o n , H S O 3 F i s t r a n s p a r e n t o v e r t h e v i s i b l e and n e a r UV r e g i o n , w h i c h s h o u l d a l l o w m o n i t o r i n g i n t e r c a l a t i o n o f a b s o r b i n g s o l u t e s v i a U V - v i s i b l e s p e c t r o s c o p y . A n o t h e r r e a s o n f o r u s i n g H S O 3 F i n o u r r e s e a r c h i s t h a t a l l t h e compounds u s e d have a common a n i o n , i . e . 38 - T a b l e 1 . 2 : P h y s i c a l and T h e r m o c h e m i c a l P r o p e r t i e s o f F l u o r o s u l f u r i c A c i d * P r o p e r t y V a l u e T e m p e r a t u r e ( ° C ) B o i l i n g p o i n t ( ° C ) F r e e z i n g p o i n t ( ° C ) 25 D e n s i t y ( D 4 ) V i s c o s i t y ( c e n t i p o i s e ) D i e l e c t r i c c o n s t a n t S p e c i f i c c o n d u c t a n c e ( o h m " 1 c m " 1 ) H e a t c a p a c i t y ( c a l d e g " 1 g " 1 ) L a t e n t h e a t o f v a p o r i z a t i o n ( k c a l m o l e " 1 ) Hea t o f f o r m a t i o n o f g a s , ( f r o m e l e m e n t s ) ( k c a l m o l e " 1 ) Hea t o f f o r m a t i o n o f l i q u i d , ( f r o m e l e m e n t s ) ( k c a l m o l e " 1 ) Hea t o f f o r m a t i o n o f gas f r o m gaseous S O 3 and HF ( k c a l m o l e " 1 ) 1 6 2 . 7 1 6 4 . 4 - 8 8 . 9 8 1.726 1.728 1.56 1 .72 -120 1.08 x 1 0 " 4 0 . 2 8 8 . 4 1 8 1 . 9 1 9 0 . 3 184 2 3 . 2 25 25 25 25 25 25 25 f r o m r e f e r e n c e 7 1 . - 3 9 - S O 3 F " , w i t h r e s p e c t t o H S O 3 F . Due t o t h i s , t h e i n t e r c a l a n t s f o r m r e l a t i v e l y s i m p l e i o n s i n a s o l u t i o n o f f l u o r o s u l f u r i c a c i d . The e x t e n s i v e use o f t h e a c i d i n s y n t h e t i c r e a c t i o n s b y o u r g r o u p and o t h e r s , as w e l l as i t s c o m p a t i b i l i t y w i t h o x i d i z i n g a g e n t s s u c h as S 2 O 5 F 2 ( w h i c h has been s t u d i e d p r e v i o u s l y w i t h r e g a r d t o i n t e r c a l a - t i o n 4 3 ) j u s t i f i e s i t s use as a s o l v e n t i n GIC s y n t h e s i s . However , some c o m p l i c a t i o n s do o c c u r i n t h i s s o l v e n t s y s t e m . Many s o l u t i o n s o f H S O 3 F a r e e x c e e d i n g l y c o m p l e x , and i f t h e s e s o l u t i o n s a r e u s e d as i n t e r c a l a n t s , i n t e r p r e t a t i o n o f r e s u l t s may l e a d t o d i f f i c u l - t i e s ; e . g . S b F 5 - H S 0 3 F i n g r a p h i t e i n t e r c a l a t i o n 7 0 . F l u o r o s u l f u r i c a c i d i s s e n s i t i v e t o m o i s t u r e , w h i c h makes i t n e c e s s a r y t o c a r r y o u t s o l v e n t m a n i p u l a t i o n and s y n t h e t i c r e a c t i o n s u n d e r vacuum o r i n e r t a t m o s p h e r e c o n d i t i o n s . A d d i t i o n a l l y , i n t h e p r e s e n c e o f o x i d i z i n g i n t e r c a l a n t s , c o - i n t e r c a l a t i o n o f H S O 3 F may t a k e p l a c e and as a c o n s e q u e n c e , t e r n a r y i n t e r c a l a t i o n compounds a r e g e n e r a l l y f o r m e d . I n s u c h i n s t a n c e s , H - m i c r o a n a l y s i s r e s u l t s c o u l d g i v e an i n d i c a t i o n o f t h e e x t e n t o f a c i d i n t e r c a l a t i o n . I n a d d i t i o n , t h e r e a r e two p r i n c i p a l e q u i l i b r i a i n H S 0 3 F t o c o n s i d e r 7 1 . ( a ) S e l f - i o n i z a t i o n o r a u t o p r o t o l y s i s : 2 H S 0 3 F „ » H 2 S 0 3 F + + S 0 3 F " , K a p - 3 . 8 x 1 0 " 8 m o l e 2 k g - 2 The H 2 S 0 3 F + i o n i s t e r m e d a c i d i u m i o n and S O 3 F " , base i o n . - AO - ( b ) S e l f - d i s s o c i a t i o n : H S O 3 F * " HF + S 0 3 , K s d < 3 x 1 0 * 7 m o l e 2 k g * 2 The S O 3 t h u s p r o d u c e d can a i d o x i d a t i v e i n t e r c a l a t i o n , b u t a t room t e m p e r a t u r e t h e e x t e n t o f d i s s o c i a t i o n c a n be c o n s i d e r e d n e g l i g i b l e . I n o r d e r t o e x t e n d i n t e r c a l a t i o n s t u d i e s t o c a t i o n i c i o d i n e s p e c i e s and i o d i n e as w e l l as b r o m i n e f l u o r o s u l f a t e compounds, H S O 3 F becomes t h e s o l v e n t o f c h o i c e f o r t h e f o l l o w i n g r e a s o n s : ( a ) I o d i n e c a t i o n s , i n p a r t i c u l a r l 3 + and i n s p i t e o f l i m i t e d d i s s o c i a - t i o n l 2 + . flre s t a b l e i n t h i s s o l v e n t , and t h e i r U V - v i s i b l e s p e c t r a a r e k n o w n . 7 2 They may be g e n e r a t e d i n H S O 3 F b y t h e r e a c t i o n , H S O 3 F n l 2 + S 2 0 6 F 2 > 2 I n + ( s o l v ) + 2 S 0 3 F - ( s o l v ) where n - 2 o r 3 . ( b ) I ( S 0 3 F ) 3 and B r ( S 0 3 F ) 3 behave as n o n - e l e c t r o l y t e s i n H S O 3 F , w h i c h i m p l i e s t h a t d i s s o c i a t i o n i s e x t r e m e l y s l i g h t . 9 * * ' 9 7 ( c ) The a n i o n s I ( S 0 3 F ) 4 " o r B r ( S 0 3 F ) 4 " may be o b t a i n e d b y d i s s o l u t i o n o f K [ I ( S 0 3 F ) 4 ] o r K [ B r ( S 0 3 F ) 4 ] i n H S O 3 F . - 4 1 - 1.10 Enhanced E l e c t r i c a l Conduc tance i n I n t e r c a l a t e d Compounds F o r a few compounds, t h e enhanced e l e c t r i c a l c o n d u c t i v i t i e s were measured u s i n g t h e c o n t a c t l e s s r a d i o f r e q u e n c y m e t h o d 8 2 . S i n c e t h e m a i n g o a l o f t h i s t h e s i s i s t h e s y n t h e s i s o f new a c c e p t o r i n t e r c a l a t i o n compounds, o n l y a few samples were u s e d t o o b t a i n b a s a l p l a n e c o n d u c t i - v i t i e s . N e v e r t h e l e s s , an e x p l a n a t i o n o f t h i s phenomenon i s n e c e s s a r y , s i n c e t h e p r a c t i c a l a p p l i c a t i o n o f G I C ' s i s l a r g e l y b a s e d on t h e i r enhanced c o n d u c t a n c e i n t h e b a s a l p l a n e . Enhanced e l e c t r i c a l c o n d u c t i v i t y i n i n t e r c a l a t e d g r a p h i t e samples can be e x p l a i n e d b y s t u d y i n g t h e e l e c t r o n i c d e n s i t y o f s t a t e s f o r g r a p h i t e ( F i g . 1 . 5 ) . I n an i s o l a t e d c a r b o n l a y e r , t h e b o n d i n g (7r) and a n t i b o n d i n g {it ) bands a r e f o r m e d f r o m p o r b i t a l s o f t h e c a r b o n a t o m s , w i t h an o v e r l a p e n e r g y o f a b o u t 30 -40 m e V 8 8 . Due t o t h i s b a n d s e p a r a - t i o n o r g a p , e l e c t r o n s can move f r o m t h e v a l e n c e (n-) b a n d t o t h e c o n d u c t i o n (it ) b a n d . T h i s p r o c e s s c r e a t e s p o s i t i v e h o l e s i n t h e v a l e n c e b a n d . These h o l e s as w e l l as e l e c t r o n s i n t h e c o n d u c t i o n band a r e t h e b a s i c c a r r i e r s o f c h a r g e i n t h e g r a p h i t e l a t t i c e . A l t h o u g h t h i s mode l does n o t t a k e i n t o c o n s i d e r a t i o n t h e i n t e r a c - t i o n b e t w e e n t h e g r a p h i t e l a y e r s , i t i s n o t " i d e a l " , s i n c e t h e i n t e r - l a y e r f o r c e s (Van d e r Waals t y p e ) a r e q u i t e weak b y n a t u r e 8 9 . Donor t y p e i n t e r c a l a n t s w o u l d add e l e c t r o n s and a c c e p t o r i n t e r c a l - a n t s w o u l d remove e l e c t r o n s f r o m t h e c o n d u c t i o n ( T T * ) band and v a l e n c e b a n d (rc) r e s p e c t i v e l y . T h e r e f o r e , i n d o n o r G I C ' s t h e enhanced e l e c t r i - c a l c o n d u c t i v i t y i n b o t h a - a n d c - a x i s d i r e c t i o n s i s due t o t h e p r e s e n c e o f a d d i t i o n a l e l e c t r o n s . However , i n a c c e p t o r compounds, h o l e s , w h i c h - 42 - % i Prist ine Energy F i g u r e 1 . 5 : D e n s i t y o f S t a t e s i n P u r e , Reduced and O x i d i z e d G r a p h i t e A c c o r d i n g t o t h e Band M o d e l . 4 3 - a r e f o r m e d by t h e l o s s o f e l e c t r o n s , w o u l d i n c r e a s e t h e c o n d u c t a n c e a l o n g t h e b a s a l p l a n e . A n o t h e r f a c t o r w h i c h c o n t r i b u t e s t o h i g h b a s a l p l a n e c o n d u c t i v i t y i n a c c e p t o r G I C ' s i s t h e c h a r g e l o c a l i z a t i o n a r o u n d t h e i n t e r c a l a t e s p e c i e s . T h i s p r o c e s s w i l l e f f e c t i v e l y m i n i m i z e any i n t e r a c t i o n b e t w e e n t h e c a r b o n l a y e r s , hence g i v i n g t h e compounds e x t r e m e 2 D c h a r a c t e r i s t i c s 9 ^ * 9 2 . 1.11 Purpose o f T h i s S t u d y The r e a s o n s t h a t i n i t i a t e d t h i s r e s e a r c h l e a d i n g t o t h e s y n t h e s i s o f new a c c e p t o r g r a p h i t e i n t e r c a l a t i o n compounds c a n be summar ized as f o l l o w s : a ) S y n t h e t i c a i m t o i n t e r c a l a t e i o d i n e - f l u o r o s u l f a t e compounds o r i o d i n e i t s e l f b y u t i l i z i n g l 2 + ( s o l v ) a s p r e c u r s o r . b ) C o m p a r a t i v e s t u d y o f t h e i n t e r c a l a t i o n o f BrSC^F r e p o r t e d p r e - v i o u s l y w i t h H S O 3 F as s o l v e n t , and w i t h e x t e n s i o n t o B r ( S 0 3 F ) 3 , h o p e f u l l y p r o v i d i n g a b e t t e r r o u t e t o s y n t h e s i s o f C n B r ( S 0 3 F ) 3 . c ) An a t t e m p t w i l l be made t o a s c e r t a i n r e a c t i o n c o n d i t i o n s , w h i c h w o u l d l e a d t o t h e f o r m a t i o n o f G I C ' s where a c i d c o i n t e r c a l a t i o n i s e l i m i n a t e d o r m i n i m i z e d . d ) U t i l i z a t i o n o f N 0 + + e~ > NO c o u p l e t o i n t e r c a l a t e S O 3 F " i n f l u o r o s u l f u r i c a c i d , and a c o m p a r i s o n o f t h i s s y n t h e t i c r o u t e t o d i r e c t i n t e r c a l a t i o n o f g r a p h i t e b y S 2 O 5 F 2 . T h i s s y s t e m w i l l a l s o be compared t o t h e N 0 + p r o m o t e d i n t e r c a l a t i o n sys tems i n n o n - - 44 - p r o t o n i c s o l v e n t s . E x p l o r a t o r y r e a c t i o n s o f n o n - i n t e r c a l a t e d h a l o g e n f l u o r o s u l f a t e s w h i c h a r e p e r t i n e n t t o i n t e r c a l a t i o n c h e m i s t r y , w i l l be i n v e s t i g a t e d . - 45 - CHAPTER 2 EXPERIMENTAL SECTION - 46 - EXPERIMENTAL G e n e r a l Comments S i n c e most compounds u s e d i n t h i s r e s e a r c h were m o i s t u r e s e n s i t i v e , c a r e was t a k e n a t a l l s t a g e s t o a v o i d any c o n t a c t w i t h m o i s t a i r . The s y n t h e t i c r e a c t i o n s were p e r f o r m e d i n w e l l v e n t i l a t e d fumehoods and t r a n s f e r s o f m a t e r i a l s were c a r r i e d o u t i n a d r y b o x f i l l e d w i t h p u r i - f i e d n i t r o g e n o r a r g o n . A l l v o l a t i l e compounds were h a n d l e d i n g l a s s vacuum l i n e s mounted on m e t a l f r a m e w o r k s i n s i d e fumehoods . 2 . 1 A p p a r a t u s 2 . 1 . 1 G l a s s Vacuum L i n e S t a n d a r d h i g h vacuum t e c h n i q u e s were u s e d i n a l l t h e s y n t h e t i c r e a c t i o n s . The h i g h r e a c t i v i t y o f t h e compounds t o w a r d s m o i s t u r e made i t n e c e s s a r y t o keep t h e p r e s s u r e a t 0 . 0 0 1 t o r r . The m a i n m a n i f o l d o f t h e p y r e x vacuum l i n e was 600 mm i n l e n g t h and 20 mm O.D. F i v e o u t l e t s f i t t e d w i t h K o n t e s t e f l o n s tem s t o p c o c k s were u s e d t o a t t a c h r e a c t o r s and o t h e r a p p a r a t u s t h r o u g h B10 g r o u n d g l a s s cone and s o c k e t j o i n t s . The vacuum l i n e was c o n n e c t e d t o a Welch D u o - s e a l m e c h a n i c a l pump (mode l 1405) v i a a l i q u i d n i t r o g e n c o l d t r a p t o p r e v e n t any c o r r o s i v e v o l a t i l e - 47 - m a t e r i a l s b e i n g d rawn t h r o u g h t h e pump. P r e s s u r e s measured i n t h e m a n i f o l d u s i n g a m e r c u r y manometer showed v a l u e s f r o m 0 . 5 t o r r t o 1 a t m o s p h e r e . T r a n s f e r o f l i q u i d s and o t h e r v o l a t i l e m a t e r i a l f r o m one r e a c t i o n v e s s e l t o a n o t h e r was c a r r i e d o u t u s i n g a T - c o n n e c t i n g b r i d g e , w h i c h was a t t a c h e d t o t h e vacuum l i n e v i a a BIO c o n e . 2 . 1 . 2 M e t a l F l u o r i n e L i n e I n t h e S20gF2 p r e p a r a t i o n ( F i g . 2 . 7 ) , t h e f l u o r i n e l i n e and t h e f l o w a p p a r a t u s were b u i l t u s i n g c o p p e r o r mone l t u b i n g ( 1 / 4 i n c h , O . D . ) a t t a c h e d t o a m e t a l f r ame w o r k . The v a l v e s u s e d were f r o m W h i t e y R e s e a r c h T o o l C o . , C a l i f o r n i a ; Hoke I n c . , New J e r s e y and A u t o c l a v e E n g i n e e r i n g I n c . , P e n n s y l v a n i a r e s p e c t i v e l y . A l l c o n n e c t i o n s i n t h e l i n e were e i t h e r s i l v e r s o l d e r e d o r made w i t h Swage lock f i t t i n g s . 2 . 1 . 3 D r y A tmosphere Box The m a n i p u l a t i o n o f a l l a i r s e n s i t i v e compounds were c a r r i e d o u t i n a Vacuum A tmosphere C o r p o r a t i o n " D r i - L a b " , model H E - 4 3 - 2 , f i t t e d w i t h d r y and p u r i f i e d n i t r o g e n o r a r g o n . P 2 0 5 was k e p t i n an open c o n t a i n e r i n s i d e t h e d r y b o x t o remove any r e s i d u a l m o i s t u r e and t o a c t as an i n d i c a t o r . The d r y box was e q u i p p e d w i t h a " D r i - T r a i n " mode l HE-93B r e c i r c u l a t i n g u n i t f o r c o n s t a n t c i r c u l a t i o n o f n i t r o g e n o r a r g o n o v e r m o l e c u l a r s i e v e s . A M e t t l e r P160 t o p l o a d i n g b a l a n c e was u s e d i n s i d e - 48 - t h e d r y box i n o r d e r t o w e i g h h y g r o s c o p i c m a t e r i a l s . 2 . 1 . 4 R e a c t i o n V e s s e l s P r i m a r i l y two t y p e s o f p y r e x v e s s e l s were u s e d . a ) Two P a r t G l a s s R e a c t o r The r e a c t i o n f l a s k u s e d was e i t h e r a 50 ml E r l e n m e y e r f l a s k o r a r o u n d b o t t o m f l a s k w i t h a s t a n d a r d B19 g r o u n d g l a s s c o n e . The r e a c t o r t o p c o n s i s t e d o f an a d a p t e r w i t h a K o n t e s t e f l o n s tem s t o p c o c k sand - w i c h e d b e t w e e n a B19 s o c k e t and a BIO g r o u n d g l a s s c o n e , f o r a t t a c h m e n t t o t h e g l a s s vacuum l i n e ( F i g s . 2 . 1 ( A ) and 2 . 1 ( B ) ) . The f l a t b o t t o m E r l e n m e y e r f l a s k h a d t h e a d v a n t a g e o f e x p o s i n g a l a r g e r s u r f a c e a r e a o f g r a p h i t e f o r i n t e r c a l a t i o n r e a c t i o n s . O b v i o u s d i s a d v a n t a g e s o f u s i n g a f l a t b o t t o m a p p a r a t u s i n vacuum l i n e w o r k were t h e s m a l l vo lume o f t h e r e a c t i o n s and t h e f a c t t h a t d u r i n g t h e r e a c t i o n s H S O 3 F and more so ^ 2 ° 6 F 2 r a i s e d t h e i n t e r n a l p r e s s u r e a t room t e m p e r a t u r e t o a t l e a s t 5 t o r r . A l s o , t h e a d d i t i o n o f r e a g e n t s and HOPG p l a t e s was much more e a s i l y c a r r i e d o u t i n a two p a r t g l a s s r e a c t o r t h a n i n a s i n g l e p a r t r e a c t o r . The o b v i o u s d i s a d v a n t a g e was t h e p o s s i b l e c o n t a m i n a t i o n o f p r o d u c t s due t o f l u o r o c a r b o n g r e a s e ( o r i t s r e a c t i o n p r o d u c t s ) w h i c h had t o be a p p l i e d a t t h e g r o u n d g l a s s j o i n t s t o m a i n t a i n l e a k p r o o f connec- t i o n s u n d e r vacuum. Q u i t e o b v i o u s l y , two p a r t r e a c t o r s a r e p a r t i c u l a r l y u s e f u l i n e x p l o r a t o r y i n t e r c a l a t i o n s t u d i e s . - 49 - 50 - b ) One P a r t G l a s s R e a c t o r s To a v o i d g r e a s e c o n t a m i n a t i o n a l t o g e t h e r , s i n g l e p a r t r e a c t i o n v e s s e l s were u s e d w h e r e v e r n e c e s s a r y ( F i g s . 2 . 2 and 2 . 3 ) . The s e a l - o f f one p a r t r e a c t o r ( F i g . 2 . 2 ( A ) ) was made up o f e i t h e r a p y r e x E r l e n m e y e r f l a s k o r a r o u n d b o t t o m f l a s k (50 m l ) , w i t h a c o n s t r i c t i o n and a B19 c o n e . The s i d e arm o f t h e r e a c t o r was f i t t e d w i t h a K o n t e s t e f l o n s tem s t o p c o c k , and a BIO c o n e . Once t h e r e a g e n t s were added i n t h e d r y b o x , t h e capped r e a c t o r c o u l d be f l a m e s e a l e d a t t h e c o n s t r i c t i o n . The a d d i t i o n o f l i q u i d r e a c t a n t s was c a r r i e d o u t v i a d i s t i l l a t i o n t h r o u g h t h e s i d e a r m . B o t h s i n g l e p a r t r e a c t i o n v i a l s ( F i g . 2 . 3 ) and r e a c t i o n v e s s e l s w i t h a r o u n d b o t t o m f l a s k ( F i g . 2 . 2 ( B ) ) were a l s o u s e d . The a d d i t i o n o f SP1 g r a p h i t e and s o l i d o r l i q u i d r e a g e n t s c o u l d be done w i t h r e l a t i v e ease i n t h e s e t y p e s o f r e a c t o r s . T e f l o n c o a t e d m a g n e t i c s t i r b a r s (10 mm x 3 mm) were u s e d i n o r d e r t o m i x s o l i d and l i q u i d phases i n i n t e r - c a l a t i o n r e a c t i o n s as w e l l as i n p r i m a r y s y n t h e s i s r e a c t i o n s . 2 . 1 . 5 M i s c e l l a n e o u s G lass A p p a r a t u s a ) S20gF2 A d d i t i o n T r a p When s t o i c h i o m e t r i c amounts o f S20gF2 were needed f o r a r e a c t i o n , an a d d i t i o n t r a p was used ( F i g . 2 . 4 ) . E x a c t vo lumes o f up t o 0 . 5 0 ml c o u l d be d i s t i l l e d u s i n g t h i s d e v i c e . The t r a p was made up o f a p i p e t t e 51 - F i g u r e 2.2: One P a r t R e a c t i o n V e s s e l s , (A ) " S e a l o f f " One P a r t R e a c t o r . (B ) "Round B o t t o m " One P a r t R e a c t o r . F i g u r e 2 . 3 : One P a r t R e a c t i o n V i a l s . (A) "Medium W a l l e d " R e a c t o r . (B ) " T h i c k W a l l e d " R e a c t o r . - 53 S 2 ° 6 F 2 A d d i t i o n T r a p . - 54 ( 0 . 0 0 - 0 . 5 0 m l ) f i t t e d w i t h a 20 mm l o n g (10 mm O . D . ) p y r e x b u l b t o w h i c h a K o n t e s t e f l o n s tem s t o p c o c k was a t t a c h e d . A s i d e arm e x t e n s i o n ended w i t h a B19 g r o u n d g l a s s c o n e . The compact n a t u r e o f t h e t r a p made i t easy t o w e i g h i n an a n a l y t i c a l b a l a n c e , t h u s p r o v i d i n g a n o t h e r method t o c h e c k t h e amounts added . For a d d i t i o n o f l a r g e r amounts o f S 2 O 5 F 2 , a s i m i l a r t y p e o f t r a p , w i t h a 4 . 0 0 m l c a p a c i t y p i p e t t e , was u s e d . b ) Vacuum F i l t r a t i o n A p p a r a t u s I n o r d e r t o s e p a r a t e a s o l i d f r o m a l i q u i d i n a r e a c t i o n m i x t u r e , a vacuum f i l t r a t i o n a p p a r a t u s ( F i g . 2 . 5 ) as d e s c r i b e d i n S h r i v e r 8 7 was u s e d . The a p p a r a t u s c o n s i s t e d o f a 25 mm O.D. p y r e x g l a s s t u b e i n w h i c h a medium c o a r s e n e s s g l a s s f r i t was s e t a b o u t one t h i r d f r o m t h e b o t t o m . The t o p o f t h e t u b e ended i n a B19 cone and t h e b o t t o m i n a B19 s o c k e t . Be tween t h e g l a s s f r i t and t h e B19 s o c k e t , a K o n t e s t e f l o n s tem s t o p c o c k was c o n n e c t e d . The s i d e arm o f t h e a p p a r a t u s a l s o h a d a s i m i l a r s t o p - c o c k , above w h i c h a B19 g r o u n d g l a s s cone was a t t a c h e d . Once t h e B19 s o c k e t was f i t t e d w i t h a 100 ml r o u n d b o t t o m f l a s k , t h e w h o l e a p p a r a t u s c o u l d be e v a p o r a t e d . The f i l t r a t i o n was t h e n c a r r i e d o u t i n t h e d r y b o x . - 55 - F i g u r e 2 . 5 : Vacuum F i l t r a t i o n A p p a r a t u s . - 56 - 2 . 2 A n a l y t i c a l Equ ipment 2 . 2 . 1 V i s i b l e and U l t r a v i o l e t S p e c t r o p h o t o m e t e r A Cary 17D d o u b l e beam s p e c t r o p h o t o m e t e r was u s e d t o o b t a i n room t e m p e r a t u r e U.V. and v i s i b l e s p e c t r a i n t h e range o f A = 750 -300 nm. The w a v e l e n g t h r a n g e o f t h e s p e c t r o p h o t o m e t e r was 186-2650 nm and t h e s p e c t r a l b a n d w i d t h 0 . 1 nm. Samples were f i l l e d i n 1 .00 mm c e l l p a t h q u a r t z o p t i c a l c e l l s o b t a i n e d f r o m T h e r m a l S y n d i c a t e L t d . , E n g l a n d , and k e p t a i r t i g h t w i t h t e f l o n s t o p p e r s . A l l s o l u t i o n s were made and t r a n s - f e r r e d i n t h e d r y b o x . 2 . 2 . 2 I n f r a r e d S p e c t r o p h o t o m e t e r I n f r a r e d s p e c t r a were r e c o r d e d u s i n g a P e r k i n - E l m e r 598 g r a t i n g s p e c t r o p h o t o m e t e r , i n t h e w a v e l e n g t h r a n g e o f 4 0 0 0 - 2 0 0 c m " 1 . S i n c e t h e compounds u s e d were h i g h l y r e a c t i v e and m o i s t u r e s e n s i t i v e , AgBr windows were u s e d w i t h o u t a m u l l i n g a g e n t . The samples were p r e p a r e d i n t h e d r y box and s p e c t r a r e c o r d e d as soon as p o s s i b l e . Gaseous I . R . s p e c t r a were t a k e n u s i n g a mone l m e t a l c e l l , w h i c h was f i t t e d w i t h vacuum t i g h t AgC l w indows ( 0 . 0 4 2 i n c h t h i c k n e s s ) . A p o l y s t y r e n e f i l m was u s e d as a r e f e r e n c e f o r a l l s p e c t r a , and t h e o p t i c a l w indows were o b t a i n e d f r o m t h e Harshaw C h e m i c a l C o . , O h i o . - 57 2 . 2 . 3 N u c l e a r M a g n e t i c Resonance S p e c t r o m e t e r A B r u k e r CXP-200 FT-NMR s p e c t r o p h o t o m e t e r was u s e d t o r e c o r d s o l i d s t a t e 1 9 F s p e c t r a . The s p e c t r o p h o t o m e t e r was o p e r a t e d a t 1 8 8 . 1 5 MHz. NMR t u b e s o f 30 mm l e n g t h and 5 mm O.D. were u s e d . The powder samples were l o a d e d i n s i d e t h e d r y box and f l a m e s e a l e d . F r e o n - 1 1 was used as an e x t e r n a l r e f e r e n c e . H i g h r e s o l u t i o n ^H s p e c t r a o f l i q u i d samples were t a k e n u s i n g a V a r i a n EM-360, a t a f r e q u e n c y o f 60 MHz. T e t r a - m e t h y l s i l a n e (TMS) was used as an e x t e r n a l r e f e r e n c e . s p e c t r a o f l i q u i d s were r e c o r d e d on a V a r i a n EM-360, o p e r a t e d a t 5 6 . 4 5 MHz. H S O 3 F and F r e o n - 1 1 were u s e d as i n t e r n a l and e x t e r n a l r e f e r e n c e s r e s p e c t i v e l y . A l l s p e c t r a were t a k e n a t room t e m p e r a t u r e . 2 . 2 . 4 Raman S p e c t r o p h o t o m e t e r Room t e m p e r a t u r e Raman s p e c t r a were r e c o r d e d u s i n g a Spex Ramalog-5 s p e c t r o p h o t o m e t e r , and t h e e x c i t a t i o n w a v e l e n g t h was t h e g r e e n l i n e a t 5 1 4 . 5 nm, e m i t t e d b y a S p e c t r a P h y s i c s 164 a r g o n i o n l a s e r . S ince g r a p h i t e i n t e r c a l a t i o n compounds have a v e r y h i g h r e f l e c t i v i t y as w e l l as a b s o r p t i o n , a b a c k - s c a t t e r i n g a r r a n g e m e n t was u s e d ^ . T h i s g e o m e t r y m i n i m i z e s t h e l o s s o f l a s e r power a t t h e q u a r t z windows and a l s o p r e - v e n t s any p o l a r i z a t i o n change i n t h e i n c i d e n t beam ( F i g . 2 . 6 ) . A t e f l o n c e l l , w i t h q u a r t z w i n d o w s , was u s e d t o h o l d t h e s a m p l e s . A l l sample m a n i p u l a t i o n s were done i n t h e d r y b o x , and s p e c t r a were t a k e n as soon as t h e sample p r e p a r a t i o n was o v e r . B a c k - s c a t t e r i n g A r r a n g e m e n t Used f o r Raman S p e c t r a . - 59 2 . 2 . 5 X - r a y Powder D i f f r a c t i o n X - r a y powder p h o t o g r a p h s were t a k e n u s i n g a P h i l l i p s powder camera o f 57 mm r a d i u s , h a v i n g a c o n v e n t i o n a l S t r a u m a n i s l o a d i n g a r r a n g e m e n t . C u - K Q X - r a y r a d i a t i o n (A «- 1 .5405 A) was used w i t h a n i c k e l f i l t e r t o r e d u c e Kp r a d i a t i o n . The t i m e o f e x p o s u r e d e p e n d i n g on t h e n a t u r e o f t h e s a m p l e s , r a n g e d f r o m 8-12 h r s . The powder samples were l o a d e d i n t o 0 . 5 mm L indemann g l a s s c a p i l l a r i e s i n t h e d r y b o x and f l a m e s e a l e d . Kodak NS-392 T t y p e f i l m s were u s e d t o o b t a i n X - r a y powder p h o t o g r a p h s . The d i f f r a c t i o n l i n e s were measured on a f i l m i l l u m i n a t o r , w h i c h was made up o f a m e t e r s t i c k t o w h i c h a m e a s u r i n g s l i d e a s s e m b l y , c o n t a i n i n g a V e r n i e r and a m a g n i f i e d c r o s s - h a i r f o r l o c a t i o n o f t h e d i f f r a c t i o n l i n e s , was a t t a c h e d . The a c c u r a c y o f t h e measurement i s ± 0 . 0 3 A. 2 . 3 E l e m e n t a l A n a l y s e s C a r b o n , h y d r o g e n , and n i t r o g e n a n a l y s e s were done b y M r . P. Borda a t t h e M i c r o a n a l y t i c a l L a b o r a t o r y o f t h e C h e m i s t r y D e p a r t m e n t , The 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 . A f l a s h o x i d a t i o n m e t h o d , u s i n g a C a r l o E l b a mode l 1106 e l e m e n t a l a n a l y z e r , was u s e d f o r t h i s p u r p o s e * * 1 . E l e m e n t a l s u l f u r and h a l o g e n s were a n a l y z e d b y A n a l y t i s c h e L a b o r a t o r i e n , Gummersbach i n West Germany. A l l samples u s e d f o r m i c r o a n a l y s i s were l o a d e d i n t o g l a s s t u b e s ( 6 - 7 mm O . D . ) i n t h e d r y box and f l a m e s e a l e d . - 60 - 2 . 4 E l e c t r i c a l C o n d u c t i v i t y o f I n t e r c a l a t e d HOPG Samples A c o n t a c t l e s s r a d i o f r e q u e n c y i n d u c t i o n t e c h n i q u e 8 2 was u s e d t o measure t h e room t e m p e r a t u r e e l e c t r i c a l c o n d u c t i v i t y o f i n t e r c a l a t e d HOPG s a m p l e s . A c i r c u l a r f e r r i t e c o r e o f 60 mm d i a m e t e r was u s e d t o i n s e r t t h e sample t u b e s . The t h i c k n e s s o f t h e sample and t h e s u r f a c e a r e a were measured u s i n g a t r a v e l l i n g m i c r o s c o p e and a t o o l m a k e r ' s m i c r o m e t e r . The s y s t e m was c a l i b r a t e d u s i n g m e t a l samples w i t h known e l e c t r i c a l c o n d u c t i v i t i e s . The o v e r a l l r e l a t i o n s h i p i s g i v e n b y : AV - k t s 2 c r w h e r e , AV = o u t p u t v o l t a g e (mv) s k — c o n s t a n t a t = t h i c k n e s s o f t h e sample (cm) Some o t h e r u s e f u l r e l a t i o n s h i p s a r e as f o l l o w s : s p e c i f i c c o n d u c t i v i t y . (<7g = c o n d u c t i v i t y o f HOPG). s p e c i f i c c o n d u c t i v i t y ( n o r m a l i z e d ) p e r p l a n e o f g r a p h i t e . A V / A V g . i n c r e a s e i n t h i c k n e s s . ( k / k ) / ( t / t Q ) . s u r f a c e a r e a o f t h e sample (cm ) e l e c t r i c a l c o n d u c t i v i t y o f t h e 1 1 sample (ohm" - 1- cm"-1-) a/og = k / k g = t / t Q - - 61 - 2 . 5 O t h e r T e c h n i q u e s Mass s p e c t r a were o b t a i n e d w i t h a K r a t o s MS50 mass s p e c t r o m e t e r o p e r a t e d a t 70 eV. A Thomas Hoover c a p i l l a r y m e l t i n g p o i n t a p p a r a t u s was u s e d t o g e t t h e m e l t i n g p o i n t s . 2 . 6 P r e p a r a t i o n and P u r i f i c a t i o n o f Reagents 2 . 6 . 1 S 2 0 g F 2 B i s ( f l u o r o s u l f u r y l ) p e r o x i d e , S20gF2, was p r e p a r e d ( i n s e v e r a l k i l o g r a m q u a n t i t i e s ) b y t h e r e a c t i o n o f f l u o r i n e and s u l f u r t r i o x i d e u s i n g a AgF2 c a t a l y s t a t a t e m p e r a t u r e o f - 1 8 0 ° C 8 3 , 8 4 • n i e e x p e r i m e n t a l s e t - u p f o r t h i s p r e p a r a t i o n i s shown i n F i g . 2 . 7 . T h i s me thod i s a m o d i f i e d v e r s i o n o f t h e g e n e r a l s y n t h e t i c r o u t e as d e s c r i b e d i n t h e l i t e r a t u r e . P r e s s u r e r e g u l a t e d f l u o r i n e was p a s s e d t h r o u g h 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 NaF. T h i s t r a p i s n e c e s s a r y t o remove any HF i m p u r i t i e s f r o m t h e f l u o r i n e g a s . HF f r e e f l u o r i n e was t h e n a l l o w e d t o r e a c t w i t h s u l f u r t r i o x i d e , w h i c h was c a r r i e d t o t h e AgF2 c a t a l y t i c r e a c t o r b y a s t r e a m o f d r y n i t r o g e n . Excess f l o w o f f l u o r i n e was d e t e c t e d u s i n g a f l u o r o l u b e o i l b u b b l e c o u n t e r . To i m p r o v e t h e y i e l d o f t h e r e a c t i o n , s u l f u r t r i o x i d e was h e a t e d u s i n g a h e a t i n g m a n t l e t o 50°C, and t h e o v e r a l l r e a c t i o n t e m p e r a t u r e was m a i n t a i n e d a t - 1 8 0 ° C . The p r o d u c t s g e n e r a t e d were c o l l e c t e d by c o n d e n s a t i o n i n t h e d r y i c e t r a p s A, B and C, k e p t a t - 7 8 ° C . Excess - 62 - To Flowmeter Copper Gloss Reaclor (J) Whitey Volve Hoke 413 Valve 6 Autoclave Engineering, Valves Ik Cosby P r e s s u r e Guoge To f", cylinder Copper Gloss B 3 4 A B 3 4 B 3 4 To Sodo-JIme Trop -Fluorolube Oil Tube B C F i g u r e 2 . 7 : Appara tus f o r the P r e p a r a t i o n o f S 2 0 6 F 2 . - 63 - f l u o r i n e and b y - p r o d u c t F S O 3 F were c a r r i e d t o a soda l i m e r e a c t o r , hence r e n d e r i n g them i n a c t i v e . The condensed c o l o r l e s s l i q u i d was e x t r a c t e d w i t h 96-98% H 2 S O 4 t o remove any u n r e a c t e d s u l f u r t r i o x i d e . T h i s p u r i f i e d S 2 0 g F 2 was t h e n vacuum d i s t i l l e d i n t o p y r e x s t o r a g e v e s s e l s . Gas phase i n f r a r e d s p e c t r o s c o p y and l i q u i d 1 9 F NMR were u s e d t o c o n f i r m t h e p u r i t y o f t h e S 2 0 g F 2 o b t a i n e d . 2 . 6 . 2 H S O 3 F T e c h n i c a l g r a d e f l u o r o s u l f u r i c a c i d was o b t a i n e d f r o m c o m m e r c i a l l y a v a i l a b l e s o u r c e s and was p u r i f i e d b y a d o u b l e d i s t i l l a t i o n t e c h n i q u e d e s c r i b e d b y Thompson and G i l l e s p i e 8 ^ • 8 f ) . The a p p a r a t u s u s e d f o r t h i s me thod i s shown i n F i g . 2 . 8 . The e n t i r e s y s t e m was f i r s t f l a m e d r i e d t o remove any m o i s t u r e , and n i t r o g e n was f l u s h e d t h r o u g h f o r a b o u t 15 h . D i s t i l l a t i o n was c a r r i e d o u t u n d e r a b l a n k e t o f d r y n i t r o g e n a t a tmo- s p h e r i c p r e s s u r e , and the. f i r s t f r a c t i o n c o l l e c t e d was made HF f r e e b y a c o u n t e r f l o w o f n i t r o g e n . The c o n s t a n t b o i l i n g second f r a c t i o n was t h e n c o l l e c t e d a t 163°C . The s t o r a g e c o n t a i n e r was e v a c u a t e d and t h e a c i d s t o r e d i n t h e d r y b o x t o p r o t e c t i t f r o m any c o n t a m i n a t i o n . 2 . 6 . 3 I 2 + ( s o l v ) P r e p a r a t i o n o f t h i s r e a g e n t was c a r r i e d o u t a c c o r d i n g t o t h e method d e s c r i b e d b y G i l l e s p i e and M i l n e 7 2 . 1 .1057 g o f I 2 and 0 .4298 g o f - 64 - Figure 2.8: Fluorosulfuric Acid D i s t i l l a t i o n Apparatus. - 65 - £>2°6 F2 were u s e d , and t h e r e a c t i o n t o o k p l a c e a c c o r d i n g t o t h e e q u a t i o n , 2 I 2 + S 2 0 6 F 2 > 2 I 2 + + 2 S 0 3 F * The mole r a t i o o f I 2 t o S2C>5F2 was k e p t v e r y c l o s e t o a v a l u e o f 2 : 1 , and t h e r e a c t i o n was a l l o w e d t o t a k e p l a c e f o r 18 h , a t room t e m p e r a t u r e . The s o l u t i o n was used i m m e d i a t e l y f o r i n t e r c a l a t i o n . 2 . 6 . 4 I ( S 0 3 F ) 3 T h i s r e a g e n t was made f r o m I 2 and excess S 2 0 g F 2 as shown b y R o b e r t s and C a d y 7 3 . 1 .1952 g o f I 2 was u s e d , and when t h e r e a c t i o n h a d warmed t o room t e m p e r a t u r e , 4 . 0 0 3 g o f y e l l o w v i s c o u s I ( S 0 3 F ) 3 was o b t a i n e d . The excess S 2 0 g F 2 was removed b y vacuum. I 2 + 3 S 2 0 6 F 2 > 2 I ( S 0 3 F ) 3 The s o l u t i o n s o f I ( S 0 3 F ) 3 were u s e d f o r i n t e r c a l a t i o n w i t h HOPG and SP-1 g r a p h i t e . 2 . 6 . 5 I S 0 3 F S y n t h e s i s was c a r r i e d o u t u s i n g a mole r a t i o o f S 2 0 g F 2 t o I 2 o f 1 . 0 5 . The method i s d e s c r i b e d by Aubke and C a d y 7 4 . 1 .4096 g o f I 2 and - 66 - 1 .1506 g o f S20gF2 were u s e d , and a d a r k b r o w n s o l i d p r o d u c t was o b t a i n e d a c c o r d i n g t o : I 2 + S 2 0 6 F 2 •> 2 I S O 3 F The p r o d u c t was u s e d i m m e d i a t e l y f o r i n t e r c a l a t i o n r e a c t i o n s . 2 . 6 . 6 I B r 2 S 0 3 F P r e p a r a t i o n was done a c c o r d i n g t o t h e t e c h n i q u e p u b l i s h e d b y W i l s o n and A u b k e 7 5 . A l a r g e e x c e s s o f d r i e d and p u r i f i e d b r o m i n e was d i s t i l l e d i n v a c u o o n t o p r e - w e i g h e d I S O 3 F , c o n t a i n e d i n a s i n g l e p a r t r e a c t i o n v e s s e l . The p r o d u c t was s t o r e d u n d e r n i t r o g e n i n t h e d r y b o x s i n c e I B r 2 S 0 3 F i s e x t r e m e l y m o i s t u r e s e n s i t i v e . I S O 3 F + excess Br2 •> I B r 2 S 0 3 F 2 . 6 . 7 K [ I ( S 0 3 F ) 4 ] and K [ B r ( S 0 3 F ) 4 ] Two s y n t h e t i c methods were u s e d . a ) An e x c e s s o f S 2 0 g F 2 ( ~ 3 . 0 0 m l ) was d i s t i l l e d o n t o a b o u t 1 . 0 0 g o f d r i e d K I , t o o b t a i n K [ I ( S 0 3 F ) 4 ] o r o n t o KBr t o s y n t h e s i z e K [ B r ( S 0 3 F ) 4 ] , - 67 - a c c o r d i n g t o t h e method d e s c r i b e d by L u s t i g and Cady ' . S i n c e t h e two phases o f S 2 O 5 F 2 and t h e p o t a s s i u m h a l i d e s d i d n o t g i v e a homogeneous m i x t u r e , t h e r e a c t i o n t o o k a p p r o x i m a t e l y 3 weeks t o a c h i e v e c o m p l e t i o n . A n o v e l a l t e r n a t i v e r o u t e was t r i e d t o overcome t h i s p r o b l e m . b ) D r i e d K I ( - 0 . 5 3 2 g ) was added t o a one p a r t r e a c t o r , w h i c h was i n t u r n c o n n e c t e d t o t h e vacuum l i n e v i a a T - b r i d g e . The s a l t was k e p t u n d e r dynamic vacuum f o r 30 m i n . t o remove any r e s i d u a l m o i s t u r e . A s u f f i c i e n t amount o f H S O 3 F ( - 2 . 0 0 - 3 . 0 0 m l ) was t h e n d i s t i l l e d o n t o t h e K I r e a c t o r , w h i c h was k e p t a t l i q u i d n i t r o g e n t e m p e r a t u r e . I n a s i m i l a r manner , an e x c e s s o f S 2 O 5 F 2 ( - 3 . 0 0 m l ) was d i s t i l l e d i n t o t h e r e a c t o r . Upon w a r m i n g t o room t e m p e r a t u r e , a m i l d e x o t h e r m i c r e a c t i o n t o o k p l a c e , and t h e r e s u l t i n g s o l u t i o n was l i g h t y e l l o w i n c o l o r . The r e a c t i o n went t o c o m p l e t i o n a f t e r a b o u t 2 h . The excess H S O 3 F and S 2 0 g F 2 were removed b y s l o w pump ing u n d e r vacuum. K I + 2 S 2 0 6 F 2 •> K [ I ( S 0 3 F ) 4 ] K I + 2 S 2 0 6 F 2 •> K [ B r ( S 0 3 F ) 4 ] H S O 3 F K I + e x c e s s S 2 0 g F 2 •> K [ I ( S 0 3 F ) 4 ] The r e a c t i o n was m o n i t o r e d b y w e i g h t , and a b o u t 1.568 g o f t h e p r o d u c t was o b t a i n e d . An i d e n t i c a l t e c h n i q u e was u s e d t o s y n t h e s i z e - 68 - K [ B r ( S 0 3 F ) 4 ] • 2.6.8 B r ( S 0 3 F ) 3 B r o m i n e ( I I I ) f l u o r o s u l f a t e was made a c c o r d i n g t o t h e r e a c t i o n An e x c e s s o f S20gF2 was d i s t i l l e d o n t o a b o u t 1.59 g o f Br2 c o n t a i n e d i n a two p a r t r e a c t o r , and t h e m i x t u r e a l l o w e d t o warm t o room t e m p e r a t u r e . The excess S 2 0gF2 was t h e n pumped o f f , l e a v i n g a b o u t 1 .539 g o f l i g h t y e l l o w s o l i d . The r e a c t i o n was f o l l o w e d b y w e i g h t , and c h e c k e d f o r p u r i t y b y I . R . s p e c t r o s c o p y . 2.6.9 B r S 0 3 F B r o m i n e ( I ) f l u o r o s u l f a t e was p r e p a r e d a c c o r d i n g t o t h e method o f Aubke and G i l l e s p i e 7 7 b y u s i n g a mole r a t i o o f S20gF2 t o B r 2 - 1 . 0 1 8 . B r 2 + excess S20gF2 •> 2 B r ( S 0 3 F ) 3 Br2 + S20gF2 -> 2 B r S 0 3 F The s m a l l e x c e s s o f S20gF2 was n e c e s s a r y t o g e t a much i m p r o v e d y i e l d o f B r S 0 3 F . I n t h e i n t e r c a l a t i o n r e a c t i o n w i t h SP-1 g r a p h i t e , a b o u t 0 . 7 9 0 g o f t h e r e d - b r o w n l i q u i d was u s e d . 2 . 6 . 1 0 NOS0 3F - 69 - N i t r o s o n i u m f l u o r o s u l f a t e was p r e p a r e d u s i n g a s l i g h t e x c e s s o f NO and S 2 0 g F 2 , a c c o r d i n g t o t h e method p u b l i s h e d b y Q u r e s h i e t a l . 7 9 . A b o u t 1 .236 g o f NO gas and - 2 . 0 0 m l o f S 2 0 g F 2 were d i s t i l l e d i n t o a one p a r t r e a c t o r , w h i c h was k e p t a t l i q u i d N 2 t e m p e r a t u r e . A b o u t 4 . 2 0 g o f w h i t e s o l i d N O S O 3 F was o b t a i n e d , and t h e p r o d u c t was c h e c k e d f o r p u r i t y u s i n g I . R . S p e c t r o s c o p y . 2 N 0 + S 2 0 6 F 2 > 2 N O S O 3 F The p r o d u c t was w e i g h e d i n t h e d r y box and u s e d f o r i n t e r c a l a t i o n w i t h SP-1 g r a p h i t e . 2 . 7 C o m m e r c i a l l y A v a i l a b l e C h e m i c a l s 2 . 7 . 1 G r a p h i t e Two k i n d s o f g r a p h i t e , SP-1 g r a p h i t e and HOPG were u s e d , b u t most r e a c t i o n s were c a r r i e d o u t u s i n g SP-1 g r a p h i t e o n l y . SP-1 g r a p h i t e ( s p e c t r o s c o p i c g r a d e , p u r i f i e d n a t u r a l g r a p h i t e ) o f 5 0 - 1 0 0 fi g r a i n s i z e was o b t a i n e d f r o m U n i o n C a r b i d e L t d . , Parma, O h i o , and f r o m D r . J . G . H o o l e y , D e p a r t m e n t o f C h e m i s t r y , 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 . HOPG ( H i g h l y O r i e n t e d P y r o l y t i c G r a p h i t e ) was p u r c h a s e d f r o m U n i o n C a r b i d e L t d . , Parma, O h i o . - 70 - The HOPG was p r i m a r i l y used t o s y n t h e s i z e G I C ' s f o r e l e c t r i c a l c o n d u c t i v i t y s t u d i e s , b u t SP-1 g r a p h i t e was u s e d f o r a l l o t h e r r e a c - t i o n s . To o b t a i n an e f f i c i e n t m i x i n g o f g r a p h i t e and l i q u i d phase i n t e r c a l a n t , s m a l l amounts o f g r a p h i t e ( - 1 5 0 mg) were u s e d . 2 . 7 . 2 O t h e r C h e m i c a l s O b t a i n e d f r o m Commerc ia l Sources The f o l l o w i n g t a b l e l i s t s c h e m i c a l s p u r c h a s e d f r o m c o m m e r c i a l s o u r c e s w i t h t h e i r s u p p l i e r s . Source Remarks A l l i e d C h e m i c a l s , M o r r i s t o w n , New J e r s e y A l l i e d C h e m i c a l s , M o r r i s t o w n , New J e r s e y M a t h e s o n o f Canada L t d . M a l l i n c k r o d t I n c . S t . L o u i s , M i s s o u r i A m e r i c a n S c i e n t i f i c and C h e m i c a l , S e a t t l e F i s c h e r S c i e n t i f i c Co. New J e r s e y F i s c h e r S c i e n t i f i c Co. New J e r s e y D o u b l y d i s t i l l e d ( 2 . 6 . 2 ) 98% p u r e , p a s s e d t h r o u g h NaF t o remove HF. A n a l y t i c a l r e a g e n t , s t o r e d o v e r P 2 O 5 t o remove m o i s t u r e and KBr t o remove C l 2 . Reagent g r a d e , u s e d as o b t a i n e d . D r i e d a t - 7 0 ° C t o remove any m o i s t u r e . D r i e d as i n K I . Ma theson o f Canada L t d . Passed t h r o u g h s i l i c a g e l ( ~ - 1 9 8 ° C ) t o remove m o i s - t u r e and N 0 2 . - 72 - CHAPTER 3 SYNTHETIC REACTIONS - 73 - SYNTHETIC REACTIONS G e n e r a l Comments A l l t h e s y n t h e t i c r e a c t i o n s d e s c r i b e d i n t h i s w o r k were c a r r i e d o u t u n d e r vacuum o r n i t r o g e n a tmosphere c o n d i t i o n s . The m a n i p u l a t i o n o f r e a g e n t s and r e a c t a n t s was done i n t h e d r y b o x , and a l l v o l a t i l e com- pounds were t r a n s f e r r e d f r o m b u l k v e s s e l s i n t o r e a c t o r s b y vacuum d i s t i l l a t i o n . SP-1 g r a p h i t e ( s p e c t r o s c o p i c g r a d e ) was u s e d f o r a l l t h e i n t e r c a l a t i o n r e a c t i o n s , and X - r a y and m i c r o a n a l y s i s d a t a were o b t a i n e d f o r t h e p r o d u c t s t h u s s y n t h e s i z e d . The few i n t e r c a l a t i o n compounds s y n t h e s i z e d f r o m HOPG ( H i g h l y O r i e n t e d P y r o l y t i c G r a p h i t e ) were u s e d s o l e l y f o r e l e c t r i c a l c o n d u c t i v i t y measurements . U n l e s s o t h e r w i s e m e n t i o n e d , a l l t h e r e a c t i o n s were p e r f o r m e d a t a m b i e n t t e m p e r a t u r e . The e l e m e n t a l a n a l y s i s v a l u e s shown i n d i c a t e w e i g h t p e r c e n t a g e c o m p o s i t i o n s f o r t h e v a r i o u s e l e m e n t s . P r i o r t o any use o f t h e g r a p h i t e i n t h e r e a c t i o n s , t h e powder r e a c t a n t b u l k was d r i e d f o r a b o u t one h o u r i n a dynamic vacuum. M a g n e t i c s t i r r i n g o f t h e r e a c t i o n m i x t u r e s was c a r r i e d o u t t o o b t a i n phase h o m o g e n e i t y and hence an a c c e l e r a t e d i n t e r c a l a t i o n r a t e . When HOPG p l a t e s were u s e d , t h e r e a c t i o n m i x t u r e was k e p t u n d i s t u r b e d i n o r d e r t o s a l v a g e i n t a c t i n t e r - c a l a t e d g r a p h i t e p l a t e s . - 74 - 3 . 1 I n t e r c a l a t i o n o f I 2 ( s o l v )  i n t o G r a p h i t e The l 2 + ( s o l v ) w a s p r e p a r e d b y u s i n g 1 2 and S 2 0 g F 2 , t h e r a t i o b e i n g 2 : 1 . 6 . 0 m l o f H S O 3 F was u s e d as t h e r e a c t i o n medium, and t h e e s t i m a t e d i n t e r c a l a n t amount was a b o u t 1 .530 g ( 4 . 3 4 m m o l ) . The d a r k b l u e s o l u - t i o n o f I 2 S O 3 F was t h e n r e a c t e d a t room t e m p e r a t u r e w i t h 0 . 5 1 2 3 g o f g r a p h i t e . To o b t a i n good phase h o m o g e n e i t y , t h e r e a c t i o n m i x t u r e was s t i r r e d m a g n e t i c a l l y , and t h e r e a c t i o n was a l l o w e d t o p r o c e e d f o r 18 h . A t t h e end o f t h i s t i m e p e r i o d , t h e s u s p e n s i o n was o b s e r v e d t o be r e d d i s h b r o w n i n c o l o r . The i n t e r c a l a t e d g r a p h i t e p r o d u c t was t h e n d r i e d i n a dynamic vacuum f o r a b o u t 3 h . The p r o d u c t h a d t h e c h a r a c t e r - i s t i c m e t a l l i c b l u e t i n t , and a b o u t 0 . 4 6 8 g w e i g h t i n c r e a s e was n o t i c e d . The i n t e r c a l a t e d g r a p h i t e g r a i n s showed s i z e e x p a n s i o n b y a f a c t o r o f a b o u t t w o . The s y n t h e s i s was r e p e a t e d f o u r t i m e s t o o b t a i n c o n s i s t e n t d a t a . A s i m i l a r p r o c e d u r e was f o l l o w e d i n t h e case o f HOPG i n t e r c a l a t i o n , b u t t h e s o l u t i o n m i x t u r e was a l l o w e d t o s t a n d w i t h o u t s t i r r i n g i n o r d e r t o keep t h e HOPG p l a t e s i n t a c t . The c o m p o s i t i o n o f t h e p r o d u c t , C 3 2 S O 3 F . 3 H S 0 3 F . 0 • 2 1 , a g r e e s w i t h t h e m i c r o a n a l y s i s r e s u l t s . Compound: C 3 2 S O 3 F . 3 H S 0 3 F 0 - 2 1 M i c r o a n a l y s i s d a t a : E lemen t C H I C a l c u l a t e d 4 7 . 5 0 . 3 7 3 . 1 4 Found 4 7 . 2 0 . 3 7 3 . 1 0 - 75 - X - r a y d i f f r a c t i o n v a l u e s o f t h e sample s u g g e s t a compound w i t h a c - a x i s l a y e r r e p e a t d i s t a n c e I c o f 7 . 9 9 ± 0 . 0 3 A. When t h e i n t e r c a l a t e d HOPG samples ( 0 . 1 7 4 6 g ) were h e a t e d a t 200°C f o r 4 h , s m a l l amounts o f 1 2 were o b s e r v e d i n s i d e t h e one p a r t r e a c t o r . The HOPG p l a t e s a p p e a r e d t o be e x f o l i a t e d a f t e r t h e t h e r m a l d e c o m p o s i t i o n p r o c e s s . 3.2 I n t e r c a l a t i o n o f I ( S 0 3 F ) 3 i n t o G r a p h i t e The c o n c e n t r a t i o n o f I ( S 0 3 F ) 3 i n H S O 3 F was v a r i e d , and t h e p r o d u c t s o b t a i n e d were a n a l y z e d f o r c o m p o s i t i o n . 3.2 . 1 H i g h C o n c e n t r a t i o n o f I ( S 0 3 F ) 3 : (~1.20 M) R e a c t i o n was c a r r i e d o u t u s i n g 4 . 1 0 3 g ( 9 . 4 4 3 mmol) o f l i g h t y e l l o w and v i s c o u s I ( S 0 3 F ) 3 as t h e i n t e r c a l a n t . F r e s h l y made I ( S 0 3 F ) 3 was d i s s o l v e d i n 8 . 1 0 m l o f H S 0 3 F i n a two p a r t r e a c t o r i n s i d e t h e d r y b o x . The homogeneous s o l u t i o n h a d a s l i g h t r e d t i n t . 0 .523 g o f g r a p h i t e was added t o t h e I ( S 0 3 F ) 3 s o l u t i o n , and a g r e e n b l u e c o l o r o f t h e s o l u t i o n was n o t e d i m m e d i a t e l y . The r e a c t i o n was a l l o w e d t o p r o c e e d f o r 18 h . When d r i e d i n a dynamic vacuum f o r 3 h , t h e s u r f a c e o f t h e p r o d u c t a p p e a r e d d a r k b l u e . The f i l t r a t e h a d a g r e e n b l u e c o l o r . The w e i g h t o f t h e g r a p h i t e h a d i n c r e a s e d b y 0 .7942 g . The s y n t h e s i s was r e p e a t e d f o u r t i m e s , and a l l t h e p r o d u c t s were a n a l y z e d f o r c o m p o s i t i o n , w h i c h was shown t o be C 2 2 I ( S 0 3 F > 3 . When HOPG p l a t e s were u s e d , a b o u t f i v e p l a t e s , - 76 - w i t h an a v e r a g e w e i g h t o f 0 .0949 g , were r e a c t e d w i t h 3 . 6 4 1 1 g ( 8 . 5 8 9 mmol) o f I ( S 0 3 F > 3 f o r two d a y s . 0 .1765 g w e i g h t i n c r e a s e was o b s e r v e d f o r t h e p r o d u c t s . Compound: C22 l (S03F>3 M i c r o a n a l y s i s d a t a : E lemen t C H I S F C a l c u l a t e d 3 8 . 3 7 0 . 0 1 8 . 4 6 1 3 . 9 5 8 . 2 8 Found 3 7 . 9 0 0 . 0 1 8 . 6 0 1 4 . 0 1 8 . 1 4 Mo le r a t i o 1 : 2 . 9 9 : 2 . 9 3 X - r a y powder d a t a i n d i c a t e d a c - a x i s r e p e a t l a y e r d i s t a n c e I c o f 7 . 9 4 ± 0 . 0 3 A. 3 . 2 . 2 Low C o n c e n t r a t i o n s o f I ( S 0 3 F ) 3 S i n c e t h e p r o d u c t o b t a i n e d f r o m t h e r e a c t i o n b e t w e e n c o n c e n t r a t e d s o l u t i o n s o f I ( S 0 3 F ) 3 and g r a p h i t e h a d a c o m p o s i t i o n o f C 2 2 l ( S 0 3 F ) 3 , s t o i c h i o m e t r i c amounts o f I ( S 0 3 F > 3 and g r a p h i t e were r e a c t e d i n H S O 3 F , and t h e p r o d u c t s were a n a l y z e d f o r c a r b o n , h y d r o g e n and i o d i n e c o n t e n t s r e s p e c t i v e l y . 3 .3465 g ( 7 . 8 9 4 mmol) o f f r e s h l y made I ( S 0 3 F ) 3 was d i s s o l v e d i n 2 0 . 0 0 m l o f H S O 3 F , and t h e s t o c k s o l u t i o n t h u s p r e p a r e d had a c o n c e n t r a t i o n o f 0 . 3 9 5 M. Fo r a t y p i c a l r e a c t i o n b e t w e e n g r a p h i t e and I ( S 0 3 F ) 3 , ( 4 4 C : 0 . 5 - 77 - I ( S 0 3 F ) 3 ) ) , 0 . 1 5 1 0 g o f g r a p h i t e and 0 .0606 g ( 0 . 1 4 2 9 mmol) o f I ( S 0 3 F ) 3 , w h i c h was o b t a i n e d f r o m 0 . 3 6 2 m l o f t h e s t o c k s o l u t i o n , was a l l o w e d t o r e a c t i n a two p a r t r e a c t o r . A b l u e - g r e e n c o l o r s o l u t i o n m i x t u r e was o b s e r v e d , and t h e r e a c t i o n was a l l o w e d t o p r o c e e d f o r 24 h . The p r o d u c t was d r i e d i n a dynamic vacuum f o r 3 h . The f i l t r a t e was b l u i s h g r e e n i n c o l o r , and t h e d r i e d p r o d u c t showed a t y p i c a l m e t a l l i c b l u e s u r f a c e l u s t r e . The f o l l o w i n g t a b l e summar izes t h e r e s u l t s , o b t a i n e d f o r v a r i o u s mole r a t i o s o f c a r b o n and I ( S 0 3 F ) 3 i n H S 0 3 F . T a b l e 3 . 1 : Amount G r a p h i t e Amount I ( S 0 3 F ) 3 Mole r a t i o ( g ) ( g ) C : I ( S 0 3 F ) 3 E l e m e n t a l A n a l y s i s C H I * 0 . 1 5 1 0 0 .0606 ( 0 . 1 4 2 9 mmol) 4 4 : 0 . 5 4 7 . 4 8 0 . 3 5 0 . 0 0 . 2 9 3 4 0 . 0 4 2 4 ( 0 . 1 0 0 mmol) 7 3 . 3 3 : 0 . 3 4 7 . 7 4 0 . 3 4 0 . 0 0 . 1 5 0 2 0 . 1 5 4 4 ( 0 . 3 6 4 2 mmol) 2 7 . 5 : 0 . 8 4 7 . 4 3 0 .27 0 . 0 I o d i n e was a b s e n t i n a l l t h e s a m p l e s . - 78 - 3 . 3 I n t e r c a l a t i o n o f K [ I ( S 0 3 F ) 4 ] i n t o g r a p h i t e I n a t y p i c a l s y n t h e s i s , 0 .1145 g o f g r a p h i t e was a l l o w e d t o r e a c t w i t h 0 . 7 3 2 0 g ( 1 . 3 0 2 mmol) K [ I ( S 0 3 F ) 4 ] . The creamy w h i t e powder o f K [ I ( S 0 3 F ) 4 ] was f i r s t d i s s o l v e d i n 6 . 0 m l o f HS0 3 F and t h e s o l u t i o n , w h i c h was v e r y l i g h t g r e e n y e l l o w i n c o l o r , was t h e n added t o t h e g r a p h i t e powder c o n t a i n e d i n a two p a r t r e a c t o r . The s o l u t i o n m i x t u r e t u r n e d g r e e n , and t h e r e a c t i o n was a l l o w e d t o p r o c e e d f o r 18 h . When t h e p r o d u c t was f i l t e r e d i n v a c u o , t h e f i l t r a t e was o b s e r v e d t o have a g r e e n c o l o r . The powder p r o d u c t o b t a i n e d was d r i e d i n a dynamic vacuum f o r 3 h , and when c o m p l e t e l y d r y , showed a m e t a l l i c b l u e c o l o r . The f o l l o w i n g c o m p o s i t i o n was o b t a i n e d f o r t h e sample b y m i c r o - a n a l y s i s . Compound: C g 6 I . 1 0 - 5 1 S 0 3 F . M i c r o a n a l y s i s : E lemen t C H I S F C a l c u l a t e d 4 6 . 9 2 0 . 0 5 .76 1 5 . 3 2 9 .08 Found 4 6 . 0 9 0 . 0 5 .55 1 4 . 7 4 8 . 8 0 Mo le r a t i o 1 1.0 - 79 - 3 . 4 I n t e r c a l a t i o n o f B r ( S 0 3 F ) 3 i n t o G r a p h i t e Fo r a t y p i c a l p r e p a r a t i o n , 0 .1502 g o f g r a p h i t e was u s e d t o r e a c t w i t h B r ( S 0 3 F ) 3 . The p a l e y e l l o w s o l i d B r ( S 0 3 F ) 3 ( 4 . 5 2 8 7 g ; 2 . 0 1 5 mmol) was d i s s o l v e d i n 8 . 0 ml o f H S 0 3 F , and t h e s o l u t i o n f o r m e d , w h i c h was g o l d e n y e l l o w i n c o l o r , was a l l o w e d t o r e a c t w i t h g r a p h i t e i n a two p a r t r e a c t o r . T o t a l r e a c t i o n t i m e was 24 h and t h e f i l t r a t e s t i l l had t h e g o l d e n y e l l o w c o l o r . The i n t e r c a l a t e d p r o d u c t was vacuum d r i e d f o r 3 h , and t h e powder p r o d u c t s u r f a c e showed a b l u i s h t i n t . The c o m p o s i t i o n o f t h e sample was shown t o be C 2 g g B r . 4 S 0 3 F . Compound: C 2 g g B r . 4 S 0 3 F . M i c r o a n a l y s i s : E lemen t C H Br F C a l c u l a t e d 4 0 . 3 3 0 . 0 1 0 . 0 2 9 .53 Found 3 9 . 9 4 0 . 0 1 0 . 5 6 1 0 . 3 0 Mo le r a t i o 1 : 3 . 9 5 X - r a y d i f f r a c t i o n d a t a gave a GIC w i t h c - a x i s l a y e r r e p e a t d i s t a n c e I c o f 7 . 8 8 ± 0 . 0 3 A. 3.5 I n t e r c a l a t i o n o f K [ B r ( S 0 3 F ) 4 " i n t o G r a p h i t e I n a t y p i c a l s y n t h e s i s , 1 .0325 g ( 2 . 0 0 5 mmol) o f w h i t e creamy 80 - powder K [ B r ( S 0 3 F ) 4 ] was d i s s o l v e d i n 6 . 0 ml o f H S O 3 F , w h i c h gave a g o l d e n y e l l o w s o l u t i o n . 0 .1268 g o f g r a p h i t e was t h e n added t o t h i s s o l u t i o n , and a s u s p e n s i o n o f d a r k b l a c k c o l o r was f o r m e d i m m e d i a t e l y . The r e a c t i o n was a l l o w e d t o t a k e p l a c e f o r 18 h . The powder p r o d u c t was f i l t e r e d i n vacuo and d r i e d i n a dynamic vacuum f o r a b o u t 3 h . The f i l t r a t e s t i l l h a d t h e g o l d e n y e l l o w c o l o r , and t h e i n t e r c a l a t e d g r a p h i t e p r o d u c t showed a d i s t i n c t b l u e t i n t . The m i c r o a n a l y s i s o f t h e sample gave t h e c o m p o s i t i o n as C g 4 B r . 1 1 . 2 2 . S O 3 F . Compound: C g 4 B r . 1 1 • 2 2 S 0 3 F . M i c r o a n a l y s i s : E lemen t C H I C a l c u l a t e d 4 5 . 8 5 0 . 0 3 .63 Found 4 5 . 6 3 0 . 0 3 .63 Mo le r a t i o 3 . 6 I n t e r c a l a t i o n o f B r S 0 3 F i n t o G r a p h i t e Fo r a t y p i c a l p r e p a r a t i o n , 4 . 0 0 g ( 2 2 . 3 6 mmol) o f t h e r e d - b r o w n l i q u i d BrS03F was a l l o w e d t o r e a c t w i t h 0 .1159 g ( 9 . 6 6 mmol) o f g r a p h i t e i n a one p a r t r e a c t o r . The amount o f H S O 3 F u s e d was a b o u t 6 . 0 m l . BrS03F and t h e n t h e a c i d was t r a n s f e r r e d t o t h e r e a c t o r v i a vacuum d i s t i l l a t i o n . A b l a c k - g r e e n s u s p e n s i o n was o b s e r v e d upon w a r m i n g t o room t e m p e r a t u r e . The m i x t u r e was a l l o w e d t o r e a c t f o r 18 h , and t h e S F 1 6 . 3 6 9 .69 1 6 . 4 2 9 .68 1 : 0 .995 - 81 - i n t e r c a l a t e d p r o d u c t was s e p a r a t e d by vacuum d i s t i l l a t i o n a t t h e end o f t h i s t i m e p e r i o d . A r e d d i s h b r o w n f i l t r a t e was o b s e r v e d , and t h e d r i e d powder p r o d u c t was m e t a l l i c b l u e i n c o l o r . The i n t e r c a l a t e d sample was a n a l y z e d f o r i t s c o m p o s i t i o n , and t h e f o l l o w i n g v a l u e s were o b t a i n e d . Compound: C 1 1 H S 0 3 F . 0 • 5 S 0 3 F . x B r S 0 3 F . ( x < 0 . 0 2 5 ) . M i c r o a n a l y s i s : E lemen t C H Br F S C a l c u l a t e d 4 6 . 1 6 0 . 3 5 0 . 6 9 1 0 . 1 3 1 7 . 1 0 Found 4 6 . 3 0 0 . 3 0 0 . 6 7 9 .19 1 5 . 8 0 Mo le r a t i o 1 : 1 .02 The c - a x i s l a y e r r e p e a t d i s t a n c e f o r t h e s a m p l e , as i n d i c a t e d b y X - r a y powder d i f f r a c t i o n d a t a , gave a v a l u e o f 8 . 2 2 ± 0 . 0 3 A. 3.7 I n t e r c a l a t i o n o f NOSO3F i n t o G r a p h i t e Fo r a t y p i c a l s y n t h e t i c r e a c t i o n , 0 .1443 g ( 1 2 . 0 3 mmol) o f g r a p h i t e and 1.305 g ( 1 0 . 1 2 mmol) o f w h i t e s o l i d c r y s t a l l i n e N 0 S 0 3 F , w h i c h was f r e s h l y made, were t r a n s f e r r e d i n t o a one p a r t r e a c t o r i n s i d e t h e d r y b o x . 7 . 0 m l o f HS0 3 F was t h e n d i s t i l l e d i n v a c u o i n t o t h e r e a c t o r , and t h e r e a c t i o n was a l l o w e d t o t a k e p l a c e f o r s e v e r a l days a t room t e m p e r a - t u r e . - 82 - The v o l a t i l e p r o d u c t s f r o m t h e r e a c t i o n were c o l l e c t e d by vacuum d i s t i l l a t i o n . Fo r t h i s p u r p o s e , t h e r e a c t i o n t u b e was k e p t a t d r y i c e t e m p e r a t u r e and t h e c o l l e c t i o n v e s s e l a t l i q u i d N 2 t e m p e r a t u r e . The p r o d u c t s t h u s c o l l e c t e d were t h e n a n a l y z e d b y mass s p e c t r o s c o p y . The i n t e r c a l a t e d g r a p h i t e p r o d u c t was f i l t e r e d and vacuum d r i e d f o r 3 h . M i c r o a n a l y s e s o f t h e samples ( s e v e r a l p r e p a r a t i o n s ) gave v a r y i n g amounts o f c a r b o n and h y d r o g e n , i n d i c a t i n g inhomogeneous sample c o m p o s i - t i o n s . T a b l e 3.2: T y p i c a l M i c r o a n a l y s i s d a t a Sample Amount NO (mmol) Amount G r a p h i t e (mmol) R e a c t i o n t i m e C o m p o s i t i o n C H N 2 5 . 9 3 1 3 . 3 4 10 d 6 7 . 4 9 0 . 2 8 0 . 0 7 0 . 6 2 0 . 0 0 . 0 1 5 . 2 0 1 2 . 0 7 18 h 6 9 . 3 0 0 . 2 0 0 . 0 4 3 . 4 9 1 2 . 0 3 10 d 7 6 . 0 0 . 3 0 0 . 0 7 7 . 0 0 . 1 6 0 . 0 The X - r a y d i f f r a c t i o n v a l u e s o b t a i n e d showed a compound w i t h c - a x i s l a y e r r e p e a t d i s t a n c e I c = 1 0 . 5 9 ± 0 . 0 3 A. The mass s p e c t r a a n a l y s i s gave p r i m a r i l y peaks r e l a t e d t o S i F 4 . NO c o u l d n o t be i d e n t i f i e d i n t h e s e s p e c t r a . The amounts o f c a r b o n and h y d r o g e n as a n a l y z e d b y - 83 - m i c r o - a n a l y t i c a l m e t h o d s , d i d n o t v a r y s i g n i f i c a n t l y when t h e r e a c t i o n t i m e o r r e a c t a n t c o n c e n t r a t i o n s were c h a n g e d . 3 . 8 I n t e r c a l a t i o n o f I B ^ S C ^ F i n t o G r a p h i t e A p p r o x i m a t e l y 3 .50 g ( 9 . 0 7 mmol) o f b r i c k r e d s o l i d I B r 2 S 0 3 F was d i s s o l v e d i n 7 . 0 m l o f H S O 3 F . The b l a c k b r o w n s o l u t i o n t h u s f o r m e d was m i x e d w i t h 0 . 1 4 3 2 g ( 1 1 . 9 3 mmol) o f g r a p h i t e i n a two p a r t r e a c t o r . When t h e g r a p h i t e was added , t h e s o l u t i o n t u r n e d a l m o s t b l a c k . The r e a c t i o n was a l l o w e d t o go on f o r 2 d a y s . The i n t e r c a l a t e d p r o d u c t was t h e n vacuum f i l t e r e d and d r i e d i n a dynamic vacuum f o r 3 h . The d r i e d powder h a d t h e c h a r a c t e r i s t i c m e t a l l i c b l u e c o l o r , and when a n a l y z e d , gave t h e f o l l o w i n g c o m p o s i t i o n . M i c r o a n a l y s i s d a t a : E lemen t C H Found 4 7 . 1 5 0 . 0 3 . 9 R e a c t i o n s o f H a l o g e n F l u o r o s u l f a t e s 3 . 9 . 1 A t t e m p t e d O x i d a t i o n o f K [ I ( S 0 3 F ) 4 ] 0 . 2 6 9 7 g o f K [ I ( S 0 3 F J 4 was t r a n s f e r r e d t o a one p a r t r e a c t o r i n s i d e - 84 t h e d r y b o x , and 6 . 0 ml o f H S O 3 F and excess S 2 0 g F 2 were vacuum d i s t i l l e d i n t o t h e same r e a c t o r . Upon w a r m i n g t o room t e m p e r a t u r e t h e r e a c t i o n m i x t u r e showed a y e l l o w c o l o r . M a g n e t i c s t i r r i n g f o r 5 h d i d n o t g i v e any o b s e r v a b l e change . The r e a c t o r was t h e n h e a t e d u s i n g a w a t e r b a t h , and t h e t e m p e r a t u r e was k e p t c o n s t a n t a t 75°C f o r 18 h . S i n c e no c o l o r change was d e t e c t e d , t h e t e m p e r a t u r e was r a i s e d t o 90°C , and t h e r e a c t i o n a l l o w e d t o p r o c e e d f o r one d a y . The r e a c t o r was t h e n c o o l e d t o room t e m p e r a t u r e and t h e excess H S O 3 F and S 2 0 g F 2 were removed v i a vacuum. The r e a c t o r was k e p t u n d e r dynamic vacuum f o r s e v e r a l h o u r s , and a v i s c o u s r e d c o l o r e d l i q u i d was o b t a i n e d as a p r o d u c t . The r e a c t i o n was m o n i t o r e d b y w e i g h t . 3 . 9 . 2 R e a c t i o n o f K [ I ( S 0 3 F ) 4 ] w i t h Excess B r 2 R.T. K [ I ( S 0 3 F ) 4 ] + excess B r 2 > 2 B r S 0 3 F + K [ I B r 2 ( S 0 3 F ) 2 ] 2 days A p p r o x i m a t e l y 0 .6322 g K [ I ( S 0 3 F ) 4 ] was added t o a one p a r t r e a c t o r , and e x c e s s Br2 was t h e n vacuum d i s t i l l e d i n t o t h e same v e s s e l . A d a r k b r i c k r e d c o l o r was o b s e r v e d i n t h e r e a c t i o n t u b e . The r e a c t i o n was a l l o w e d t o p r o c e e d f o r 2 days a t room t e m p e r a t u r e . The v o l a t i l e b y p r o d u c t s o f t h e r e a c t i o n were c o l l e c t e d v i a vacuum d i s t i l l a t i o n and were a n a l y z e d b y 1 9 F - N M R . The c o l o r o b s e r v e d f o r t h e v o l a t i l e ( s ) was s t i l l b r i c k r e d . The s o l i d p r o d u c t , w h i c h was l i g h t r e d b r o w n i n c o l o r and c r y s t a l l i n e , was a n a l y z e d b y I . R . S p e c t r o s c o p y . The - 85 r e a c t i o n was f o l l o w e d b y w e i g h t as w e l l . 3 . 9 . 3 R e a c t i o n o f I ( S 0 3 F ) 3 w i t h Excess B r 2 I ( S 0 3 F ) 3 + excess B r 2 > I B r 2 S 0 3 F + 2 B r S 0 3 F 3 .4699 g o f I ( S 0 3 F ) 3 , w h i c h was f r e s h l y made i n a one p a r t r e a c t o r , was a l l o w e d t o r e a c t w i t h e x c e s s B r 2 a t room t e m p e r a t u r e f o r 2 d a y s . The r e a c t o r was t h e n h e a t e d u s i n g a w a t e r b a t h ( - 6 5 ° C ) f o r 5 h . A d a r k r e d v i s c o u s l i q u i d was o b s e r v e d . The r e a c t i o n v e s s e l was t h e n e v a c u a t e d u n d e r a dynamic vacuum f o r 48 h w h i l e b e i n g k e p t a t a b o u t 0 °C . The p r o d u c t o b t a i n e d was s t i l l a d a r k r e d v e r y v i s c o u s l i q u i d , and a t t e m p t s t o o b t a i n a s o l i d p r o d u c t b y c o o l i n g a t l i q u i d N 2 t e m p e r a t u r e d i d n o t p r o v e t o be s u c c e s s f u l . The r e a c t i o n was f o l l o w e d b y w e i g h t . - 86 - CHAPTER 4 RESULTS AND DISCUSSION - 87 RESULTS AND DISCUSSION G e n e r a l Comments T h i s c h a p t e r i s i n t e n d e d t o r a t i o n a l i z e t h e o b s e r v a t i o n s and r e s u l t s p r e s e n t e d i n t h e p r e v i o u s s e c t i o n s o f t h i s t h e s i s . I n o r d e r t o m a i n t a i n a l o g i c a l sequence , t h e c h a p t e r i s d i v i d e d i n t o t h e f o l l o w i n g s u b s e c t i o n s : 4 . 1 I n t e r c a l a n t P r e p a r a t i o n i n F l u o r o s u l f u r i c A c i d and R e l a t e d S t u d i e s The s y n t h e s i s o f v a r i o u s f l u o r o s u l f a t e s p e c i e s w h i c h a r e u s e d as i n t e r c a l a n t s and t h e i r p h y s i c a l and c h e m i c a l b e h a v i o u r i n H S O 3 F w i l l be d i s c u s s e d . I n a d d i t i o n t o p r e v i o u s l y r e p o r t e d r e a c t i o n s and p r o p e r t i e s , m i s c e l l a n e o u s a t t e m p t e d r e a c t i o n s o f h a l o g e n f l u o r o s u l f a t e s , p e r t i n e n t t o i n t e r c a l a t i o n c h e m i s t r y , a r e t o be i n c l u d e d i n t h i s s e c t i o n . 4 . 2 I n t e r c a l a t i o n o f I o d i n e C o n t a i n i n g S p e c i e s S o l u t i o n i n t e r c a l a t i o n o f I 2 + , I ( S 0 3 F ) 3 , K [ I ( S 0 3 F ) 4 ] and I S 0 3 F i s c o n s i d e r e d , and t h e r e s u l t s a r e d i s c u s s e d . - 88 - 4 . 3 I n t e r c a l a t i o n o f Bromine C o n t a i n i n g Compounds The f o l l o w i n g compounds and t h e i r i n t e r c a l a t e d p r o d u c t s a r e t o be d i s c u s s e d : B r S 0 3 F , B r ( S 0 3 F ) 3 , K [ B r ( S 0 3 F ) 4 ] , I B r 2 S 0 3 F . 4 . 4 N I t r o s o n i u m I o n ( N 0 + ) P romoted I n t e r c a l a t i o n o f S0 3 F~ A c o m p a r a t i v e s t u d y o f N 0 + i n t e r c a l a t i o n i n H S 0 3 F and i n n o n - p r o t o n i c s o l v e n t s w i l l be made i n t h i s s e c t i o n . 4 . 5 G e n e r a l Comments on HS0 3 F and C o n c l u s i o n 4 . 1 I n t e r c a l a n t P r e p a r a t i o n i n F l u o r o s u l f u r i c A c i d and R e l a t e d S t u d i e s S e c t i o n A The s y s t e m l 2 " S 2 0 g F 2 a l l o w s one t o g e n e r a t e t h e f o l l o w i n g i o d i n e c o n t a i n i n g s p e c i e s : a ) S o l v a t e d i o n s f o r m e d i n s t r o n g p r o t o n i c a c i d s such as l 2 + . I 3 + and p o s s i b l y l 5 + , w i t h n o n - i n t e g e r o x i d a t i o n s t a t e s o f i o d i n e . Of t h e s t r o n g p r o t o n i c a c i d s a v a i l a b l e , H S O 3 F i s s u f f i c i e n t l y a c i d i c t o s t a b i l i z e I 2 + i h u t on a c c o u n t o f i t s o x i d i z i n g a b i l i t y t h e e x i s t e n c e o f I$ + i n t h i s medium i s q u e s t i o n a b l e . - 89 b ) B i n a r y f l u o r o s u l f a t e s o f i o d i n e , i . e . I S O 3 F and I ( S 0 3 F ) 3 , w h i c h a r e f o r m e d i n t h e absence o f a c i d . O t h e r b i n a r y , i o d i n e r i c h s p e c i e s l i k e I 3 S O 3 F and I 7 S O 3 F have been i d e n t i f i e d , 7 " * ' 1 0 6 b u t t h i s s t u d y w i l l c o n c e n t r a t e on I S O 3 F and I ( S 0 3 F ) 3 . F i n a l l y , t e r n a r y K [ I ( S 0 3 F ) 4 ] i s a l s o i n c l u d e d as a p o t e n t i a l i n t e r c a l a n t i n a d d i t i o n t o t h e o t h e r two b i n a r y f l u o r o s u l f a t e s . 4 . 1 . 1 I 2 + ( s o l v ) l 2 + i o n s c a n b e s t be g e n e r a t e d r e a s o n a b l y q u a n t i t a t i v e l y i n H S O 3 F b y t h e method r e p o r t e d b y G i l l e s p i e and M i l n e . 7 2 The i o n has an i n t e n s e b l u e c o l o r i n s o l u t i o n and an o p t i c a l s p e c t r u m c a n be o b t a i n e d . I n a d d i t i o n m a g n e t i c s u s c e p t i b i l i t y measurements and r e s o n a n c e Raman s p e c t r a a r e u s e d i n t h e s t u d y o f t h e s e s p e c i e s . 9 * ' F o r t h e s y n t h e s i s o f l 2 + ( s o l v ) , t h e mole r a t i o o f l 2 : S 2 0 g F 2 has t o be m a i n t a i n e d c l o s e t o 2 : 1 , s i n c e I n a d d i t i o n t o t h e p r i n c i p l e r e a c t i o n H S O 3 F 2 I 2 + S 2 0 6 F 2 > 2 I 2 + ( s o l v )  + 2 s ° 3 F " ( s o l v ) o t h e r c a t i o n s o f i o d i n e such as I 3 " 1 " o r s p e c i e s l i k e I ( S 0 3 F ) 3 c a n be f o r m e d , e i t h e r b y t h e o x i d a t i o n o f excess i o d i n e o r b y t h e use o f excess ^ 2 ° 6 F 2 a t r o o m t e m p e r a t u r e . A b s o r p t i o n s t u d i e s o f l 2 + ( s o l v ) & i - v e t h r e e s h a r p peaks i n t h e o p t i c a l s p e c t r u m a t 6 4 0 , 4 9 0 , and 410 nm, a s s i g n e d t o l 2 + ( F i g . 4 . 1 ) . The s m a l l peak a t 300 nm i n t h e 2 : 1 s o l u t i o n i s due t o t h e l 3 + i o n , w h i c h i s f o r m e d a c c o r d i n g t o : - 90 - Figure 4.1: Absorption Spectra of 1:1 and 2:1 I 2/S 20 6F 2 Solutions: A, 2:1 I 2/S 20 6F 2, - 0.164, path length - 0.005 cm; B. 2:1 I 2/S 20 6F 2, mj - 0.372, path length - 0.01 cm; C, 1:1 I 2/S 20 6F 2, mj - 0.0186, path length - 0.01 cm. from reference 72. 8 I 2 + + 8 S O 3 F * - 91 - 5 I 3 + + 5 S 0 3 F " + I ( S 0 3 F ) 3 However , i n H S O 3 F , t h i s e q u i l i b r i u m p r o d u c e s o n l y v e r y s m a l l amounts o f l 3 + a t l o w e r c o n c e n t r a t i o n s . T h e r e f o r e , i t can be s a f e l y assumed t h a t t h e 2 : 1 I 2 / S 2 O 6 F 2 s o l u t i o n i s p r e d o m i n a n t l y made up o f l 2 + i o n s . To a v o i d t h e p r e s e n c e o f 1 3 " * " , l ow c o n c e n t r a t i o n s were used i n t h e p r e p a r a t i v e s y n t h e s i s . 4 . 1 . 2 I S O 3 F I o d i n e ( I ) f l u o r o s u l f a t e i s s y n t h e s i z e d u s i n g n e a r l y e q u i m o l a r ( 1 : 1 . 0 5 ) amounts o f I 2 and S 2 0 g F 2 . 7 " f When t h e i n i t i a l c r u d e p r o d u c t i s h e a t e d t o 60°C f o r - 1 h , a d a r k b l a c k i s h b r o w n h y g r o s c o p i c s o l i d o f c o m p o s i t i o n I S O 3 F i s o b t a i n e d . When added t o H S O 3 F , I S O 3 F d i s s o l v e s r e a d i l y t o f o r m a b l u e c o l o r s o l u t i o n due t o l 2 + i o n s . The o p t i c a l s p e c t r u m o f I S O 3 F i n H S O 3 F i s shown i n F i g . 4 . 2 . I S O 3 F was f o u n d t o be d i a m a g n e t i c , t h e r e b y i n d i c a t i n g c o v a l e n t b o n d i n g . 7 " * S i n c e t h e compound i s a v e r y s t r o n g o x i d i z e r and h y g r o s c o p i c , s o l u t i o n s o f i t i n H S O 3 F had t o be u s e d i m m e d i a t e l y f o r t h e r e a c t i o n s w i t h g r a p h i t e . I f t h e samples become even p a r t i a l l y h y d r o l y z e d , g r e e n s o l u t i o n s a r e o b s e r v e d due t o t h e f o r m a t i o n o f some l 3 + i o n s . - 92 - Figure 4.2: Absorption Spectrum of IOS02F Dissolved in Fluorosulfuric from reference 74. - 93 - 4 . 1 . 3 I ( S 0 3 F ) 3 I o d i n e ( I I I ) f l u o r o s u l f a t e can be s y n t h e s i z e d b y r e a c t i n g I 2 w i t h an e x c e s s o f S 2 0 g F 2 . 7 3 The r e a c t i o n i s m i l d l y e x o t h e r m i c , and t h e p r o d u c t i s a h i g h l y v i s c o u s l i q u i d o r a l ow m e l t i n g s o l i d ( T a b l e 4 . 1 ) o f l i g h t y e l l o w c o l o r . When h e a t e d t o 50°C i n v a c u o , I ( S 0 3 F ) 3 d i s p r o p o r t i o n a t e s a p p r o x i m a t e l y : 9 3 2 I ( S 0 3 F ) 3 > I S 0 3 F + I F 3 ( S 0 3 F ) 2 + 3 S 0 3 The Raman s p e c t r u m o f l i q u i d I ( S 0 3 F ) 3 has been r e p o r t e d and i n t e r p r e t e d as i n d i c a t i n g t h e p r e s e n c e o f b o t h b i d e n t a t e b r i d g i n g and monoden ta te S 0 3 F g r o u p s i n a p o l y m e r i c s t r u c t u r e . 9 5 The compound shows a m p h o t e r i c b e h a v i o r i n H S 0 3 F , c a p a b l e o f r e a c t i n g as an a c i d o r as a b a s e . O n l y a s i n g l e r e s o n a n c e i s o b s e r v e d i n t h e 1 9 F - N M R s p e c t r u m o f I ( S 0 3 F ) 3 i n H S 0 3 F . 9 4 The b a s i c and a c i d i c i o n i z a t i o n s i n f l u o r o s u l f u r i c a c i d c a n be r e p r e s e n t e d as f o l l o w s : B a s i c b e h a v i o r : I ( S 0 3 F ) 3 ^ z = r - ^ I ( S 0 3 F ) 2 + + S 0 3 F " A c i d i c b e h a v i o r : I ( S 0 3 F ) 3 + S O 3 F " , ** T ( S 0 3 F ) 4 " S o l u t i o n s o f I ( S 0 3 F ) 3 i n H S O 3 F a r e p a l e y e l l o w i n c o l o r and no a b s o r p t i o n maximum i s o b s e r v e d i n t h e o p t i c a l s p e c t r u m above 300 nm. However , a t s h o r t e r w a v e l e n g t h s , t h e r e i s a s t r o n g a b s o r p t i o n , t h e maximum o f w h i c h has n o t been r e p o r t e d . - 94 - Table 4.1: Selected Physical Properties of Some Halogen Fluorosulfates* Property BrSOiF CISO3F ISO3F Br ( S 0 3 F ) 3 K S 0 3 F ) 3 melting point (*C) +31.5 -84.3 +50.2 +59.0 + 3 2 . 2 b o i l i n g point (*C) +117.3 +45.1 +114 @ 30 Torr under decomp. density (g/ml) 2.238 @ 25'C 1.711 @ 20'C 2.40 <? 25*C vapour pressure at 25*C (Torr) 16.98 363.1 s t a b i l i t y and color red l i q u i d stable up to 150*C yellow l i q u i d black-brown s o l i d , stable upto 150*C pale yellow s o l i d , slowly decomposes at room temp. pale yellow s o l i d , or a high viscous l i q u i d slow- l y decompose et room temp 1 9 F NMR chemical s h i f t r e l . to CFC1 3 (ppm) 34.6 33.9 44.0 39.0 47.0 from reference 93. - 95 - 4 . 1 . 4 K [ I ( S 0 3 F ) 4 ] and K [ B r ( S 0 3 F > 4 ] The p r e p a r a t i v e method f o r b o t h compounds r e p o r t e d b y L u s t i g and C a d y 7 6 i s t h e o x i d a t i o n o f K I o r KBr b y a n e x c e s s amount o f S 2 0 g F 2 . T h i s s y n t h e t i c r o u t e i s r a t h e r i m p r a c t i c a l s i n c e t h e r e a c t i o n s p r o c e e d i n a h e t e r o g e n e o u s phase and u s u a l l y r e q u i r e a t l e a s t a few weeks b e f o r e p u r e p r o d u c t s a r e o b t a i n e d . I n o r d e r t o a c c e l e r a t e t h e r e a c t i o n , t h e o r i g i n a l s y n t h e s i s i s m o d i f i e d b y a d d i n g a s m a l l amount o f HS0 3 F as t h e s o l v e n t t o g e t h e r w i t h e x c e s s S 2 0 g F 2 , as d e s c r i b e d i n S e c t i o n 2 . 6 . 7 ( b ) . The a c i d a c t s as t h e s o l v e n t f o r t h e two p r o d u c t s K [ I ( S 0 3 F ) 4 ] and K [ B r ( S 0 3 F ) 4 ) . The o x i d a t i o n p r o c e s s r e a c h e s c o m p l e t i o n w i t h i n a few h o u r s , and f i n e c r y s t a l l i n e p r o d u c t s c a n be i s o l a t e d by r e m o v i n g t h e excess HS0 3 F and S20gF2 i n a dynamic vacuum. K [ I ( S 0 3 F ) 4 ] and K [ B r ( S 0 3 F ) 4 ] d i s s o l v e r e a d i l y i n H S 0 3 F , g i v i n g p a l e y e l l o w s o l u t i o n s due t o t h e a n i o n s I ( S 0 3 F ) 4 " and B r ( S 0 3 F ) 4 " r e s p e c t i v e l y . F o r t h e s y n t h e t i c r e a c t i o n s w i t h g r a p h i t e , t h e s e s o l u - t i o n s were u s e d i m m e d i a t e l y . So f a r , no s o l u t i o n s t u d i e s o f t h e s e compounds i n HS0 3 F has been r e p o r t e d . Raman s p e c t r a o f K [ I ( S 0 3 F ) 4 ] and K [ B r ( S 0 3 F ) 4 ] a r e known, and a r e v e r y s i m i l a r . 9 6 Th ree S-0 s t r e t c h i n g v i b r a t i o n s i n t h e r e g i o n o f 1500 c m " 1 - 900 c m " 1 s u g g e s t t h a t a l l f o u r S 0 3 F g r o u p s a r e i d e n t i c a l and b e s t d e s c r i b e d as m o n o d e n t a t e i n b o n d i n g . A l s o , a s i n g l e b a n d a t t r i - b u t e d t o t h e S-F s t r e t c h i n g v i b r a t i o n f o u n d a t - 8 3 5 c m " 1 i s c o n s i s t e n t w i t h t h i s c o n c l u s i o n . A s q u a r e p l a n a r e n v i r o n m e n t f o r I and B r r e s p e c - t i v e l y i s s u g g e s t e d i n b o t h K [ I ( S 0 3 F ) 4 ] and K [ B r ( S 0 3 F ) 4 ] . 9 6 - 96 - S e c t i o n B As i n t h e s y n t h e s i s o f b i n a r y i o d i n e f l u o r o s u l f a t e s , s i m i l a r compounds o f b r o m i n e such as BrSC^F and Br (S03F>3 c a n be made by t h e s y s t e m B r 2 - S 2 0 g F 2 i n t h e absence o f f l u o r o s u l f u r i c a c i d . The t e r n a r y compound K [ B r ( S 0 3 F ) 4 ] and t h e i n t e r h a l o g e n f l u o r o s u l f a t e I B ^ S C ^ F a r e i n c l u d e d as i n t e r c a l a n t s i n t h i s s e c t i o n as w e l l , s i n c e b o t h t h e s e s p e c i e s c o n t a i n b r o m i n e i n t h e i r c o m p o s i t i o n s . 4 . 1 . 5 B r ( S 0 3 F ) 3 B r o m i n e ( I I I ) f l u o r o s u l f a t e c a n be s y n t h e s i z e d u s i n g B r 2 and an e x c e s s amount o f S 2 0 g F 2 a c c o r d i n g t o 7 3 B r 2 + excess S 2 0 6 F 2 > 2 B r ( S 0 3 F ) 3 Br (S03F>3 i s a p a l e y e l l o w , v e r y m o i s t u r e s e n s i t i v e s o l i d compound and has t o be u s e d i m m e d i a t e l y s i n c e i t t e n d s t o decompose s l o w l y a t room t e m p e r a t u r e , r e s u l t i n g i n t h e f o r m a t i o n o f a r e d c o l o r e d p r o d u c t , p resumed t o be BrSG^F. The Raman s p e c t r u m o f t h e compound shows s t r u c t u r a l s i m i l a r i t y w i t h I ( S 0 3 F > 3 i n t h e s o l i d s t a t e , and s u g g e s t s a S O 3 F b r i d g e d a s s o c i a t e d s t r u c t u r e f o r b o t h B r ( S 0 3 F ) 3 and K S C ^ F ^ . 9 6 Br(S03F>3 d i s s o l v e s r e a d i l y i n H S O 3 F , and t h e r e s u l t i n g s o l u t i o n i s l i g h t y e l l o w i n c o l o r . The U V - v i s i b l e s p e c t r a o f B r 2 : S 2 0 g F 2 a t v a r i o u s - 97 r a t i o s i n H S O 3 F i s shown i n F i g . 4 . 3 On o x i d a t i o n o f B r 2 , t h e i n t e n s i t y o f t h e b a n d a t 375 nm, a s s i g n e d t o t h e B r 3 + c a t i o n , i n c r e a s e s u n t i l a t t h e 0 . 3 3 r a t i o , c o r r e s p o n d i n g t o B r 3 + f o r m a t i o n , t h e c u r v e B i s o b s e r v e d . Above t h i s r a t i o , t h e s h o u l d e r a t 375 nm d e c r e a s e s i n i n t e n - s i t y , b u t a s h o u l d e r a t 310 nm i n c r e a s e s u n t i l a t S20gF2 :Br2 r a t i o o f 3, w h i c h r e l a t e s t o t h e f o r m a t i o n o f B r ( S 0 3 F > 3 , no f u r t h e r change i s n o t e d . 9 2 I t a p p e a r s t h a t B r ( S 0 3 F ) 3 i s q u i t e s t a b l e i n f l u o r o s u l f u r i c a c i d , and no a p p r e c i a b l e d i s p r o p o r t i o n a t i o n i s o b s e r v e d . U V - v i s i b l e s p e c t r a h o w e v e r , a r e n o t s u f f i c i e n t l y d i f f e r e n t i a t e d t o a l l o w q u a n t i t a - t i v e c o n c l u s i o n s d u r i n g i n t e r c a l a t i o n . I n a s u p e r - a c i d s y s t e m l i k e S b F 5 - 3 S 0 3 - H S 0 3 F , B r ( S 0 3 F > 3 does n o t a c t as a n o n e l e c t r o l y t e , b u t f u n c t i o n s as a b a s e : 9 7 B r ( S 0 3 F ) 3 + H 2 S 0 3 F + > B r ( S 0 3 F ) 2 + + 2HS0 3 F 4 . 1 . 6 B r S 0 3 F An e x a c t l y e q u i m o l a r m i x t u r e o f B r 2 and S20gF2 i s r e q u i r e d t o s y n t h e s i z e p u r e B r S 0 3 F , 7 7 a r e d b r o w n l i q u i d , t h e r m a l l y s t a b l e i n a s e a l e d p y r e x t u b e up t o 1 5 0 ° . I t i s e x t r e m e l y s e n s i t i v e t o m o i s t u r e , r e d u c i n g a g e n t s and f l u o r o c a r b o n g r e a s e , w h i c h cause i t t o d a r k e n t o a deep r e d b r o w n c o l o r . Pure BrS03F m e l t s - 3 1 . 5 ° C and t h e 1 9 F - N M R s p e c t r u m o f t h e compound shows a s i n g l e peak a t 35 ppm r e l a t i v e t o C F C I 3 . The v a p o r p r e s s u r e o f t h e l i q u i d ( - 1 7 T o r r a t 25°C) i s s u f f i c i e n t f o r t r a n s f e r i n vacuo i n a g r e a s e f r e e l i n e t o a v o i d - 98 - F i g u r e 4 . 3 : UV and V i s i b l e S p e c t r a i n H S O 3 F . B r 2 : S 2 0 6 F 2 r a t i o : A , 1 : 0 ; B, 1 : 0 . 3 3 ; C, 1 : 1 ; D, 1:3 and 1 : 5 . f r o m r e f e r e n c e 97 . - 99 - c o n t a m i n a t i o n . BrSC^F d i s s o l v e s w e l l i n f l u o r o s u l f u r i c a c i d t o g i v e s t a b l e b rown s o l u t i o n s , and i n c o n d u c t o m e t r i c s t u d i e s , a s l i g h t i n c r e a s e i n t h e c o n d u c t i v i t y i s o b s e r v e d , s h o w i n g t h a t BrSG^F behaves as a v e r y weak e l e c t r o l y t e . As c o u l d be seen f r o m F i g . 4 . 3 , when t h e r a t i o o f B r 2 : S 2 O 5 F 2 i n H S O 3 F app roaches u n i t y , t h e s h o u l d e r a t 310 nm i n c r e a s e s i n i n t e n s i t y , b u t t h e 375 nm peak o f B r 3 + d e c r e a s e s . T h e r e f o r e , i t c o u l d be assumed t h a t BrS03F i s d i s p r o p o r t i o n a t e d t o some e x t e n t i n t o B r 3 + and B r ( S 0 3 F ) 3 i n f l u o r o s u l f u r i c a c i d . 9 7 Raman s p e c t r a and c o n d u c t o m e t r i c d a t a o f BrS03F i n t h e s u p e r a c i d s y s t e m H S 0 3 F - 3 S 0 3 - S b F 5 i n d i c a t e t h e p r e s e n c e o f b o t h B r 3 + and B r 2 + c a t i o n s : 9 7 5 B r S 0 3 F + 2H2S03F+ - * 2 B r 2 + + B r ( S 0 3 F ) 3 + 4 H S O 3 F 4 B r S 0 3 F + H2S03F+ „ » B r 3 + + B r ( S 0 3 F ) 3 + 2 H S O 3 F 4 . 1 . 7 N O S O 3 F N i t r o s o n i u m f l u o r o s u l f a t e , N O S O 3 F , i s b e s t p r e p a r e d b y t h e r e a c t i o n b e t w e e n N 0 ( g ) and S 2 0 g F 2 t o g i v e a w h i t e s o l i d w i t h a m e l t i n g p o i n t o f 2 3 0 ° C . 7 9 The compound i s r a t h e r h y g r o s c o p i c and a p p e a r s i s o s t r u c t u r a l w i t h K S O 3 F i n h a v i n g an o r t h o r h o m b i c u n i t c e l l . The w h i t e c r y s t a l l i n e m a t e r i a l i s v e r y s o l u b l e i n f l u o r o s u l f u r i c a c i d and behaves as a s t r o n g , e x t e n s i v e l y d i s s o c i a t e d base a c c o r d i n g t o : - 100 - HS0 3 F N O S 0 3 F > N 0 + ( £ o l v ) + S 0 3 F - ( s o l v ) The Raman s p e c t r u m o f N0S0 3 F i n HS0 3 F shows a s t r o n g a b s o r p t i o n a t 2320 c m " 1 , a t t r i b u t e d t o t h e N-0 s t r e t c h i n g v i b r a t i o n i n N 0 + i o n . 9 8 The c o m p l e t e d i s s o c i a t i o n o f N0S0 3 F i n HS0 3 F i s u s e f u l i n r e g a r d t o t h e s y n t h e t i c r e a c t i o n s w i t h g r a p h i t e . I n s o l u t i o n , N 0 + i o n s c o u l d be e x p e c t e d t o o x i d i z e t h e g r a p h i t e l a t t i c e , t h e r e b y f a c i l i t a t i n g t h e I n s e r t i o n o f o t h e r i o n s and n e u t r a l m o l e c u l e s . 4 . 1 . 8 . I B r 2 S 0 3 F When a l a r g e e x c e s s o f B r 2 i s r e a c t e d w i t h f r e s h l y p r e p a r e d I S 0 3 F , a r u s t b r o w n s o l i d p r o d u c t o f c o m p o s i t i o n I B r 2 S 0 3 F i s f o r m e d . 7 5 ' 9 9 L i k e most o f t h e i n t e r h a l o g e n f l u o r o s u l f a t e s , I B r 2 S 0 3 F i s e x t r e m e l y m o i s t u r e s e n s i t i v e and b e s t s t o r e d u n d e r a t m o s p h e r i c p r e s s u r e . The s y n t h e s i s f o l l o w s t h e g e n e r a l a d d i t i o n r e a c t i o n a c c o r d i n g t o : I S 0 3 F + X 2 > I X 2 S 0 3 F X - C I , B r o r I . I B r 2 S 0 3 F i s t h e r m a l l y s t a b l e u p t o 90°C and Raman and I R s p e c t r a i n d i c a t e a comp lex s t r u c t u r e w i t h a S 0 3 F " i o n where C 3 y symmet ry i s s t r o n g l y p e r t u r b e d . I B r 2 S 0 3 F d i s s o l v e s i n HS0 3 F r e a d i l y t o g i v e s t a b l e s o l u t i o n s , and l i k e o t h e r i n t e r h a l o g e n f l u o r o s u l f a t e s , behaves as a s t r o n g b a s e . A c c o r d i n g t o c o n d u c t o m e t r i c m e a s u r e m e n t s , I B r 2 S 0 3 F i s - 101 - c o m p l e t e l y d i s s o c i a t e d t o : ' - 5 H S O 3 F I B r 2 S 0 3 F — > I B r 2 + ( s o l v ) + S 0 3 F - ( s o l v ) The 1 9 F - N M R s p e c t r a o f I B r 2 S 0 3 F i n f l u o r o s u l f u r i c a c i d g i v e o n l y a s i n g l e r e s o n a n c e , i n d i c a t i n g d i s s o c i a t i o n and S 0 3 F " f o r m a t i o n . S o l u t i o n s o f I B r 2 S 0 3 F i n s t r o n g p r o t o n i c a c i d s show d i s t i n c t a b s o r p t i o n b a n d s , and i n H S 0 3 F , X m a x v a l u e s o f 560 ( s h o u l d e r ) , 455 ( s h o u l d e r ) , 361 and 232 nm a r e o b s e r v e d i n t h e e l e c t r o n i c s p e c t r u m , c o r r e s p o n d i n g t o I B r 2 + ( s o i v ) i o n s . Hence, i t was a n t i c i p a t e d t h a t I B r 2 S 0 3 F i n H S 0 3 F s h o u l d f u n c t i o n as an o x i d a t i v e i n t e r c a l a n t i n t h e r e a c t i o n w i t h g r a - p h i t e . 4 . 1 . 9 A t t e m p t e d O x i d a t i o n o f K [ I ( S 0 3 F ) 4 ] The r e a c t i o n b e t w e e n e x c e s s S 2 0 g F 2 and K [ I ( S 0 3 F ) 4 ] i n f l u o r o s u l f u r i c a c i d was c a r r i e d o u t ( a t 75°C f o r 18 h and a t 90°C f o r one d a y ) i n o r d e r t o o x i d i z e t h e l a t t e r compound a c c o r d i n g t o : HS0 3 F K [ I ( S 0 3 F ) 4 ] + excess S 2 0 6 F 2 > K [ I ( S 0 3 F ) 6 ] I t has b e e n r e p o r t e d t h a t s o l i d K [ I ( S 0 3 F ) 4 ] i s s t a b l e t o w a r d s f u r t h e r o x i d a t i o n , and when exposed t o a s t r e a m o f F 2 a t 100°C, no r e a c t i o n was o b s e r v e d . 7 ^ The ease w i t h w h i c h i o d i n e i s o x i d i z e d i n H S 0 3 F f r o m - 1 t o - 102 - +3 s u g g e s t s f u r t h e r o x i d a t i o n t o +5 may be p o s s i b l e a t e l e v a t e d t e m p e r a - t u r e and p r o l o n g e d r e a c t i o n t i m e t o o b t a i n e i t h e r [ I ( S 0 3 F ) g ] " ( s o i v ) o r s p e c i e s o f t h e t y p e [ I F n ( S 0 3 F ) g _ n ] " s h o u l d S O 3 be e l i m i n a t e d . I t s h o u l d be r e c a l l e d t h a t 1 2 i s o x i d i z e d b y S20gF2 i n o r d e r t o g i v e t h e compound I F 3 ( S 0 3 F ) 2 9 3 ( see S e c t i o n 4 . 1 . 3 ) . The r e m o v a l o f a l l t h e e x c e s s a c i d and S 2 O 5 F 2 y i e l d e d a h i g h l y v i s c o u s r e d l i q u i d . However , an o v e r a l l w e i g h t d e c r e a s e was o b s e r v e d d u r i n g t h e s y n t h e s i s . From t h e s e o b s e r v a t i o n s , i t has t o be c o n c l u d e d t h a t t h e p resumed r e a c t i o n K [ I ( S 0 3 F ) ] 4 Q*M> K [ I ( S 0 3 F ) 6 ] d i d n o t t a k e p l a c e as a n t i c i p a t e d . 4 . 1 . 1 0 R e a c t i o n o f K [ I ( S 0 3 F ) 4 " w i t h excess B r 2 T h i s r e a c t i o n i s u n p r e c e d e n t e d . I t i s p e r f o r m e d i n o r d e r t o u n d e r s t a n d t h e r e a c t i o n b e t w e e n i n t e r c a l a t e d [ I ( S 0 3 F ) 4 ] " and B r 2 , w h i c h may g i v e some i n d i c a t i o n r e g a r d i n g t h e n a t u r e o f t h e i n t e r c a l a n t s p r e s e n t i n t h e g r a p h i t e l a t t i c e . The r e a c t i o n was e x p e c t e d t o p r o c e e d as f o l l o w s : K [ I ( S 0 3 F ) 4 ] + excess B r 2  R ' T - > 2 B r S 0 3 F + K [ I B r 2 ( S 0 3 F ) 2 ] The r e a c t i o n was m o n i t o r e d b y g r a v i m e t r y and t h e d i f f e r e n c e o b s e r v e d i n w e i g h t s u g g e s t s K [ I B r 2 ( S 0 3 F ) 2 ] as a p o s s i b l e p r o d u c t i n t h e s y n t h e s i s . However , I n f r a r e d s p e c t r a o b t a i n e d on t h e s o l i d p r o d u c t ( s ) show S-0 s t r e t c h i n g f r e q u e n c i e s a t 1225 c m " 1 and 1060 c m " 1 r e s p e c t i v e l y , s u g g e s t - - 103 - i n g a n e a r l y i o n i c S O 3 F g r o u p w h i c h i s c o n s i s t e n t w i t h t h e p r e s e n c e o f i n t e r h a l o g e n f l u o r o s u l f a t e I B r 2 S 0 3 F . 7 5 The r e d b r o w n c o l o r o f t h e s o l i d p r o d u c t may a l s o be due t o t h i s compound. 1 9 F - N M R v a l u e s o f t h e v o l a - t i l e s showed two weak peaks a t 45 and 62 ppm, w h i c h were s i g n i f i c a n t l y d i f f e r e n t f r o m t h e e x p e c t e d v a l u e f o r B r S 0 3 F 9 3 ( 3 4 . 6 p p m ) , b u t s i n c e BrSC^F i s e x t r e m e l y s e n s i t i v e t o f l u o r o c a r b o n g r e a s e , t h i s o b s e r v e d d e v i a t i o n i n NMR d a t a c o u l d be due t o g r e a s e c o n t a m i n a t i o n as w e l l . 4 . 1 . 1 1 R e a c t i o n o f I ( S 0 3 F ) 3 w i t h excess Br£ I ( S 0 3 F ) 3 + e x c e s s B r 2 > I B r 2 S 0 3 F + 2 B r S 0 3 F The above p r o d u c t s were a n t i c i p a t e d f o r t h e r e a c t i o n b e t w e e n I ( S 0 3 F ) 3 and e x c e s s B r 2 ( a t room t e m p e r a t u r e f o r 2 days and a t 65°C f o r 5 h ) . Based on o b s e r v a t i o n s made d u r i n g t h e p r e c e d i n g r e a c t i o n , t h e above s y n t h e t i c r e a c t i o n was a t t e m p t e d i n o r d e r t o p r e p a r e t h e i n t e r h a l - ogen f l u o r o s u l f a t e I B r 2 S 0 3 F i n a d i f f e r e n t manner f r o m t h e o r i g i n a l a d d i t i o n r e a c t i o n o f B r 2 t o I S 0 3 F , t o y i e l d I B r 2 S C > 3 F , 7 5 as p a r t o f a g e n e r a l r e a c t i o n : I S O 3 F + X 2 > I X 2 S 0 3 F X - C I , Br o r I The d a r k r e d v i s c o u s l i q u i d was i n i t i a l l y assumed t o be I B r 2 S C > 3 F , b u t no s o l i d p r o d u c t c o u l d be i s o l a t e d even b y s u p e r c o o l i n g t h e l i q u i d a t l i q u i d N 2 t e m p e r a t u r e . - 104 - U V - v i s i b l e s p e c t r a o f t h e p r o d u c t were o b t a i n e d f o r c o n c e n t r a t i o n s - 4 . 1 9 x 1 0 " 3 m o l e s / k g i n f l u o r o s u l f u r i c a c i d and t y p i c a l l y , p a l e b l u e s o l u t i o n s were o b s e r v e d , w h i c h i n d i c a t e d t h e p r e s e n c e o f I 2 B r S 0 3 F . 7 5 The c o l o r i s c h a r a c t e r i s t i c o f t h e l 2 + c a t i o n i n H S O 3 F , and i s assumed t o be f o r m e d b y s o l v e n t o x i d a t i o n . T y p i c a l d a t a f r o m o p t i c a l s p e c t r a were as f o l l o w s : A m a x (nm) A b s o r b a n c e c m a x ( c m " 1 m o l e " 1 L ) . 635 0 . 9 2 3 1273 490 0 . 3 1 1 429 r a t i o - 1 : 3 395 0 . 4 2 0 579 The c m a x r a t i o o f t h e 635 and 490 nm peaks i s - 1 : 3 , w h i c h i s t h e v a l u e o b t a i n e d f o r I 2 + s p e c i e s i n H S O 3 F b y G i l l e s p i e and M i l n e . 7 2 Hence, t h e p r o d u c t o b t a i n e d seems t o be l 2 B r S 0 3 F f o r t h e r e a c t i o n b e t w e e n I ( S 0 3 F ) 3 and e x c e s s B r 2 . The  1 9 F - N M R o f t h e v o l a t i l e s showed two r e s o n a n c e s a t 4 4 . 1 6 and 4 9 . 7 2 ppm, w h i c h r u l e s o u t BrS03F as a p o t e n t i a l p r o d u c t . 4 . 2 I n t e r c a l a t i o n o f I o d i n e C o n t a i n i n g S p e c i e s 4 . 2 . 1 I n t e r c a l a t i o n o f l 2 + ( s o l v ) I t i s g e n e r a l l y a c k n o w l e d g e d t h a t I 2 i t s e l f w i l l n o t i n t e r c a l a t e i n t o g r a p h i t e (see Sec. 1 . 8 . 1 ) . I f t h i s I s due t o t h e r e l a t i v e l y l ow o x i d i z i n g a b i l i t y , t h e n t h e s t r o n g l y o x i d i z i n g l 2 + w o u l d o f f e r a b e t t e r - 105 - chance o f i o d i n e b e i n g i n t e r c a l a t e d . A t l o w c o n c e n t r a t i o n s , a s o l u t i o n o f m o l a r r a t i o 2 : 1 i n I 2 t o S 2 0 g F 2 i n H S O 3 F c o n t a i n s p r e d o m i n a n t l y I 2 + i o n s , 7 2 and v e r y l i t t l e d i s p r o p o r t i o n a t i o n i s o b s e r v e d . T h e r e f o r e , t h e o x i d i z i n g s p e c i e s i n t h e r e a c t i o n w i t h g r a p h i t e i s most l i k e l y t h e I 2 + ( s o l v ) • ^ e r e a c t i o n t a k e s p l a c e i n a r e l a t i v e l y s h o r t t i m e (18 h ) , i n d i c a t i n g a f a s t o x i d a t i o n o f t h e g r a p h i t e l a t t i c e b y I 2 + s o l u t i o n . I n t e r c a l a t i o n was a l s o c o n f i r m e d v i s u a l l y b y t h e m e t a l l i c b l u e t i n t o b s e r v e d on t h e d r i e d g r a p h i t e p r o d u c t s u r f a c e and b y t h e s w e l l i n g o f t h e g r a i n s t o a f a c t o r o f a b o u t t w o . I n t e r e s t i n g l y , t h e s u s p e n s i o n o f g r a p h i t e and l 2 + ( s o l v ) * n H S O 3 F a t t h e end o f 18 h showed a r e d d i s h b r o w n c o l o r . T h i s s u g g e s t s t h a t I 2 + ( s o l v ) has b e e n r e d u c e d b y g r a p h i t e t o l 3 + ( S o l v ) > w h i c h i s b r o w n i n c o l o r . T h i s c a n be shown a s : 3 I 2 + ( s o l v ) + e " > 2 I 3 + ( s o l v ) However , when e x c e s s I 2 + s o l u t i o n was added , t h e r e d d i s h b r o w n c o l o r c o u l d n o t be d e t e c t e d , and t h e s u s p e n s i o n r e m a i n e d b l u e i n c o l o r . T h i s o b s e r v a t i o n g i v e s a d d i t i o n a l e v i d e n c e t h a t c o n f i r m s t h e r o l e o f * 2 + ( s o l v ) a s *-he o x i d i z i n g a g e n t d u r i n g t h e s y n t h e s i s . The e l e m e n t a l a n a l y s i s d a t a o f t h e p r o d u c t i n d i c a t e a compound w i t h f o r m u l a C 3 2 S O 3 F . 3 H S O 3 F . 0 • 2 1 . The c a r b o n p e r c e n t a g e v a l u e o f 4 7 . 2 p o i n t s t o an i n t e r c a l a t i o n compound w i t h a l o w s t a g e i n d e x . The d a t a , i n p a r t i c u l a r t h e l o w i o d i n e c o n t e n t , a l s o s u g g e s t p r e f e r e n t i a l i n t e r c a l a - t i o n o f S O 3 F " g r o u p s and n e u t r a l H S O 3 F m o l e c u l e s . I t a p p e a r s t h a t t h i s - 106 - s y n t h e s i s f o l l o w s p r e c e d e n t s where p r o t o n i c a c i d s s u c h as H 2 S O 4 o r H S O 3 F i n t e r c a l a t e o n l y i n t h e p r e s e n c e o f an e x t e r n a l o x i d i z i n g a g e n t . 3 5 ' 3 6 I n t h e s e s y s t e m s , t h e e x t e r n a l o x i d i z e r ( e . g . C r03 ) u s u a l l y does n o t i n t e r c a l a t e t o g e t h e r w i t h t h e o t h e r i n t e r c a l a n t s p e c i e s . The v e r y s m a l l amount o f i n t e r c a l a t e d i o d i n e s u g g e s t s some o f t h e o x i d i z i n g a g e n t i s r e t a i n e d i n t h e g r a p h i t e l a t t i c e , b u t l i t t l e c a n be deduced f r o m t h i s i n f o r m a t i o n r e g a r d i n g t h e o x i d a t i o n s t a t e o f i o d i n e i n t h e i n t e r c a l a n t l a y e r s . The l o w s t a g e i n d e x ( s t a g e one) o f t h i s compound can be i n f e r r e d f r o m t h e X - r a y powder d i f f r a c t i o n d a t a . The I c v a l u e o f 7 . 9 9 A a g r e e s w e l l w i t h t h e v a l u e r e p o r t e d b y Yaddaden e t a l . f o r t h e i n t e r c a l a t i o n o f H S 0 3 F - 2 0 % S 0 3 w i t h g r a p h i t e . 6 0 T h i s I c v a l u e i s t y p i c a l f o r g r a p h i t e a c i d f l u o r o s u l f a t e s when b o t h S O 3 F g r o u p s and n e u t r a l a c i d m o l e c u l e s a r e p r e s e n t as i n t e r c a l a t e s i n t h e G I C . " * 3 , 5 8 The 1 9 F - N M R s p e c t r a a r e u s e f u l i n d e t e r m i n i n g t h e c h e m i c a l e n v i r o n m e n t o f t h e i n t e r c a l a n t s p e c i e s . S u r f a c e a d s o r b e d o r condensed g r a p h i t e p r o d u c t s show c h e m i c a l s h i f t s w h i c h a r e c l o s e r t o t h o s e f o r m e d f o r t h e f r e e i n t e r c a l a n t ( s ) , whereas i n t e r c a l a t e d compounds g i v e t y p i c a l r e s o n a n c e s s h i f t e d t o h i g h e r f i e l d s ( l o w e r f r e q u e n c i e s ) . The s o l i d s t a t e 1 9 F - N M R s p e c t r u m o f C 3 2 S O 3 F . 3 H S 0 3 F . 0 • 2 1 e x h i b i t s o n l y a s i n g l e r e s o n a n c e a t 2 0 . 2 ppm ( F i g . 4 . 4 ) . T h i s v a l u e i s s i g n i f i - c a n t l y s h i f t e d t o a h i g h e r f i e l d as compared w i t h t h e l i q u i d H S O 3 F r e s o n a n c e w h i c h a p p e a r s a t 4 0 . 6 ppm r e l a t i v e t o C F C I 3 . 4 3 1 9 F - N M R may however n o t be a s u i t a b l e t e c h n i q u e t o d i f f e r e n t i a t e b e t w e e n i n t e r c a l - a t e d S O 3 F " and H S O 3 F , s i n c e r e s o n a n c e s due t o t h e s e s p e c i e s a r e c l o s e l y s p a c e d and have been o b s e r v e d a t 3 7 . 4 and 4 0 . 6 ppm i n h i g h r e s o l u t i o n - 107 - -120ppm 20.2ppm 115ppm F i g u r e 4 . 4 : ^ F - N M R S p e c t r u m o f C 3 2 S 0 3 F . 3 H S 0 3 F . O - 2 I - 108 - s p e c t r a . 7 8 I o d i n e , 1 2 was f o u n d as a d e i n t e r c a l a t e d s u b l i m e d p r o d u c t when t h e GIC was h e a t e d t o 200°C f o r 4 h . The h i g h t e m p e r a t u r e and r e l a t i v e l y l o n g h e a t i n g t i m e c o n f i r m t h e e x i s t e n c e o f i o d i n e as an i n t e r c a l a n t r a t h e r t h a n a s u r f a c e a d s o r b e d s p e c i e s i n t h e g r a p h i t e l a t t i c e . 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 i n t e r c a l a t e d HOPG samples show enhanced c o n d u c t a n c e i n t h e b a s a l p l a n e s . T y p i c a l d a t a o b t a i n e d were as f o l l o w s : T a b l e 4 . 2 : T y p i c a l C o n d u c t i v i t y Measurements f o r G r a p h i t e - l 2 + ( s o i v ) Compound Compound: C 3 2 S O 3 F . 3 H S 0 3 F . 0 • 2 1 D i m e n s i o n s : S 2 = 9 . 5 9 x 1 0 " 2 c m 2 , t - 5 . 7 0 x 1 0 " 2 cm a x 1 0 " 4 o/ag* k / k g t / t o ( o h m * 1 c m " 1 ) 2 3 . 5 1 0 . 1 3 1 2 . 5 6 1.24 * c r g - 2 . 3 2 x 1 0 4 o h m " 1 c m " 1 ( see Sec. 2 . 4 f o r t h e d e f i n i t i o n s o f t e r m s u s e d ) I n t e r e s t i n g l y , t h e c o n d u c t i v i t y o b s e r v e d i n t h i s compound show a much l a r g e r v a l u e t h a n f o r g r a p h i t e a c i d f l u o r o s u l f a t e s where t h e o n l y i n t e r c a l a n t s a r e SO3F" and HSO3F. 4 3 These h i g h c o n d u c t i v i t y v a l u e s a r e a l m o s t c o m p a r a b l e t o v a l u e s o b t a i n e d f o r g r a p h i t e - A S F 5 i n t e r c a l a t i o n c o m p o u n d s . 1 0 0 • 1 0 1 - 109 - 4 . 2 . 2 I n t e r c a l a t i o n o f I ( S 0 3 F ) 3 The s y n t h e t i c r e a c t i o n s c a r r i e d o u t u s i n g I ( S 0 3 F ) 3 as t h e i n t e r c a l a n t showed a c l e a r dependence o f t h e r e a c t i o n s o n t h e c o n c e n t r a - t i o n o f I ( S 0 3 F ) 3 . T h i s f a c t o r w i l l be d i s c u s s e d i n more d e t a i l l a t e r . The h i g h c o n c e n t r a t i o n ( - 1 . 2 0 M) s y n t h e s i s i s t o be examined h e r e f i r s t . As shown e a r l i e r i n Sec. 4 . 1 . 3 , I ( S 0 3 F ) 3 c o u l d behave e i t h e r as a base o r an a c i d i n f l u o r o s u l f u r i c a c i d . 9 4 I n b o t h c a s e s , i o n s such as I ( S 0 3 F ) 4 " , I ( S 0 3 F ) 2 + o r I ( S 0 3 F ) 3 i t s e l f may f u n c t i o n as t h e o x i d i z i n g a g e n t , where i o d i n e e x i s t s i n a +3 o x i d a t i o n s t a t e . T h i s g i v e s t h e t y p i c a l p a l e y e l l o w c o l o r t o I ( S 0 3 F ) 3 / H S 0 3 F s o l u t i o n s . The g r a p h i t e l a t t i c e was o x i d i z e d i n a r a t h e r s h o r t p e r i o d (18 h ) b y t h e i o d i n e s p e c i e s and t h e d a r k b l a c k b l u e c o l o r o f t h e p r o d u c t s u r f a c e i n d i c a t e d i n t e r c a l a t i o n . The g r e e n b l u e c o l o r o f t h e f i l t r a t e p o i n t s t o t h e f a c t t h a t i o d i n e ( I I I ) has b e e n r e d u c e d b y g r a p h i t e a c c o r d i n g t o : 2 I + 3 + 5e" > . 2 I + 1 / 2 o r I 2 + a n d / o r , 3 I + 3 + 8e" > 3 I + 1 / 3 o r J3+ A m i x t u r e o f I + 3 ( y e l l o w ) and 1 + 1 / 2 ( b l u e ) can p r o d u c e t h e b l u e g r e e n c o l o r o b s e r v e d . A l s o , I + l / 2 and I + l / 3 ( b r o w n ) c a n g i v e i d e n t i c a l r e s u l t s . The m i c r o a n a l y s i s r e s u l t s , w i t h C : I : S : F r a t i o o f 2 1 . 5 : 1 : 2 . 9 9 : 2 . 9 3 , p o i n t s t o a compound w i t h c o m p o s i t i o n C 2 2 I ( S 0 3 F ) 3 . I n t e r e s t i n g l y , h y d r o g e n was f o u n d t o be a b s e n t , w h i c h l e d t o t h e c o n c l u - s i o n t h a t no a p p r e c i a b l e amount o f HS0 3 F i n t e r c a l a t i o n h a d t a k e n p l a c e - 110 - i n t h e s a m p l e . T h e r e f o r e , i t c a n be assumed t h a t I ( S 0 3 F ) 3 a c t s as a s t r o n g o x i d a t i v e i n t e r c a l a n t , f u n c t i o n i n g b o t h as t h e o x i d a n t and i n t e r c a l a n t d u r i n g t h e s y n t h e s i s . An a l t e r n a t i v e f o r m u l a may a l s o be c o n s i d e r e d f o r t h e p r o d u c t , i . e . C 2 2 l . 3 S 0 3 F . I n t h i s c a s e , t h e mechanism o f i n t e r c a l a t i o n c o u l d be s i g n i f i c a n t l y d i f f e r e n t as compared t o C 2 2 l ( S 0 3 F ) 3 f o r m a t i o n . T h a t t h e p r o d u c t i s o f s t a g e one can be c l e a r l y seen f r o m t h e i n t e r - l a y e r s e p a r a t i o n v a l u e o f 7 . 9 4 ± 0 . 0 3 A. I t has b e e n n o t e d b e f o r e t h a t a l l i n t e r l a y e r s e p a r a t i o n s f o r t h e f l u o r o s u l f a t e s f a l l w e l l b e l o w 8 . 0 A, s u g g e s t i n g c l o s e l y p a c k e d s t r u c t u r e s w i t h e l e c t r o n t r a n s f e r f r o m g r a - p h i t e t o i n t e r c a l a n t c a u s i n g Cou lomb ic a t t r a c t i o n b e t w e e n t h e c a r b o n and i n t e r c a l a n t l a y e r . 4 3 • 1 0 2 The s m a l l I c v a l u e o b s e r v e d i s j u s t i f i e d ( e v e n t h o u g h I ( S 0 3 F ) 3 i s q u i t e a l a r g e m o l e c u l e ) i f one assumes 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 f o r i o d i n e , as shown e a r l i e r i n Sec. 4 . 1 . 3 and 4 . 1 . 5 . The f r e q u e n c y s h i f t o f t h e E 2 g ^ v i b r a t i o n a l mode t o 1640-1642 cm"-- i n t h e Raman s p e c t r a a l s o a g r e e s w i t h p u b l i s h e d d a t a r e p o r t e d f r o m o t h e r f i r s t s t a g e c o m p o u n d s . 1 0 3 , 1 0 4 The 1 9 F - N M R s p e c t r u m o f C 2 2 l ( S 0 3 F ) 3 ( F i g . 4 . 5 ) i n d i c a t e s a s i n g l e r e s o n a n c e a t 2 3 . 6 ppm, w h i c h i s a b o u t a 2 3 . 4 ppm s h i f t t o h i g h e r f i e l d compared t o f r e e I ( S 0 3 F ) 3 ( 4 7 . 0 p p m ) . T h i s v a l u e i s i n good agreement w i t h o t h e r r e p o r t e d v a l u e s f o r i n t e r c a l a t e d h a l o g e n f l u o r o s u l f a t e s . 4 3 No s u r f a c e a d s o r b e d o r condensed I ( S 0 3 F ) 3 i s o b s e r v e d i n t h e s e s p e c t r a . The i n t e r c a l a t e d sample was h e a t e d a t 100°C f o r seven d a y s , and t h e v o l a t i l e p r o d u c t s were a n a l y z e d b y I . R . s p e c t r o s c o p y . The s p e c t r a showed peaks c o r r e s p o n d i n g t o C O 2 , S O 2 and p o s s i b l y S O 2 F 2 . The 1 9 F - N M R o f t h e r e m a i n i n g s o l i d sample gave a r e s o n a n c e a t 21 ppm. I t was n o t e d - I l l - 39.2ppm 23.6ppm F i g u r e 4 . 5 : 1 9 F - N M R Spec t rum o f C 2 2 I ( S 0 3 F ) - 112 e a r l i e r i n Sec. 4 . 1 . 3 t h a t a t 50°C i n v a c u o , I ( S C > 3 F ) 3 d i s p r o p o r t i o n a t e s t o I S O 3 F , I F 3 ( S C > 3 F ) 2 and S O 3 r e s p e c t i v e l y . T h e r e f o r e , i t i s p o s s i b l e t h a t t h e r e m a i n i n g s o l i d p r o d u c t may be composed o f g r a p h i t e - I S O 3 F o r I F 3 ( S 0 3 F ) 2 - A l t e r n a t i v e l y , a m i x t u r e o f b o t h t h e s e i n t e r c a l a n t s c o u l d be p r e s e n t i n t h e l a t t i c e as w e l l . However , t h e l a t t e r p o s s i b i l i t y i s u n l i k e l y s i n c e o n l y a s i n g l e r e s o n a n c e was o b s e r v e d f o r t h e p r o d u c t i n t h e 1 9 F - N M R s p e c t r a . I n t e r e s t i n g l y , f o r t h e case o f g r a p h i t e - B r S G ^ F i n t e r c a l a t i o n , t h e i d e a l c o m p o s i t i o n C ^ 2 B r S 0 3 F has been c a l c u l a t e d e a r l i e r u s i n g t h e i n t e r l a y e r s e p a r a t i o n and d e n s i t y o f B r S G ^ F . 1 0 2 I n a s i m i l a r manner , t h e i d e a l p a c k i n g f o r g r a p h i t e - I ( S O 3 F ) 3 i s deduced as f o l l o w s : t h e i n t e r l a y e r s e p a r a t i o n o f 7 . 9 4 A g i v e s a g a l l e r y vo lume o f 1 1 . 9 9 A 3/C a t o m , and u s i n g t h e r e p o r t e d d e n s i t y o f I ( S 0 3 F ) 3 a t 25°C w h i c h i s 2 . 4 0 g / c m 3 , 9 3 t h e m o l e c u l a r vo lume i s c a l c u l a t e d as 293 A3. T h i s s u g g e s t s t h e i d e a l c o m p o s i t i o n as C 2 4 . 4 4 I ( S 0 3 F > 3 . The d i s c r e p a n c y b e t w e e n t h e i d e a l c o m p o s i t i o n and t h e v a l u e o b t a i n e d b y m i c r o a n a l y s i s may be due t o a more t i g h t l y p a c k e d s t r u c t u r e t h a n t h a t assumed i n t h e above c a l c u l a t i o n s . T h i s s i t u a t i o n can a r i s e when an a p p r e c i a b l e amount o f c h a r g e t r a n s f e r t a k e s p l a c e b e t w e e n t h e g r a p h i t e and t h e i n t e r - c a l a n t s , c a u s i n g a c l o s e r p a c k i n g due t o an i n c r e a s e i n e l e c t r o s t a t i c a t t r a c t i o n . I n o r d e r t o s t u d y t h e f u n c t i o n o f I ( S 0 3 F ) 3 c o n c e n t r a t i o n i n t h e f i n a l p r o d u c t f o r m a t i o n , v a r i o u s s t o i c h i o m e t r i c amounts o f I ( S 0 3 F > 3 and g r a p h i t e were r e a c t e d i n H S O 3 F , b a s e d on t h e c o m p o s i t i o n o f C 2 2 l ( S 0 3 F ) 3 . The f i l t r a t e as b e f o r e gave a b l u e g r e e n c o l o r , i n d i c a t i n g t h e o x i d a t i o n o f g r a p h i t e b y t h e i o d i n e s p e c i e s . However , t h e m i c r o a n a l y s i s d a t a on 113 - t h e p r o d u c t s showed t h e absence o f i o d i n e as an i n t e r c a l a n t . The c a r b o n p e r c e n t a g e r e m a i n e d a l m o s t c o n s t a n t i n a l l t h e p r o d u c t s , and no s i g n i f i - c a n t v a r i a t i o n s were seen i n h y d r o g e n c o m p o s i t i o n s , w h i c h showed o n l y s m a l l v a l u e s r e l a t i v e t o c a r b o n . These r e s u l t s i n d i c a t e t h a t a t l o w e r I ( S 0 3 F ) 3 c o n c e n t r a t i o n s , o n l y n e u t r a l a c i d m o l e c u l e s and p o s s i b l y S O 3 F g r o u p s i n t e r c a l a t e i n t o g r a p h i t e t o f o r m f i r s t s t a g e i n t e r c a l a t i o n compounds. I n t h e h i g h c o n c e n t r a t i o n s y n t h e s i s , a b o u t a f i v e f o l d e x c e s s I ( S C > 3 F ) 3 was u s e d as t h e i n t e r c a l a n t . I t seems c l e a r f r o m t h e s e o b s e r v a t i o n s t h a t a n excess o f I ( S 0 3 F ) 3 i s n e c e s s a r y t o o b t a i n G I C ' s w h i c h f u n c t i o n b o t h as t h e o x i d i z e r and i n t e r c a l a n t . T h i s c a n be r a t i o n a l i z e d as f o l l o w s : I n i t i a l l y , I ( S 0 3 F > 3 a c t s as t h e o x i d i z i n g s p e c i e s , and i f o n l y s m a l l amounts o f i t a r e p r e s e n t i n t h e s o l u t i o n , I ( S C > 3 F ) 3 i n t e r c a l a t i o n c o u l d n o t t a k e p l a c e . I n s t e a d , p r e f e r e n t i a l i n t e r c a l a t i o n o f H S O 3 F and S O 3 F " i s o b s e r v e d . A t h i g h c o n c e n t r a t i o n s , s u f f i c i e n t amounts o f I ( S C > 3 F ) 3 a r e a v a i l a b l e t o f u n c t i o n s i m u l t a n e o u s l y as t h e o x i d i z i n g a g e n t and i n t e r c a l a n t , w h i c h l e a d s t o t h e p r o d u c t C 2 2 l ( S 0 3 F ) 3 . The i n t e r c a l a t e d HOPG samples were u s e d t o o b t a i n 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 and t y p i c a l r e s u l t s were as f o l l o w s : - 114 - T a b l e 4 . 3 : 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 o f C 2 2 l ( S 0 3 F ) 3 Compound: C 2 2 l ( S 0 3 F ) 3 D i m e n s i o n s : s 2 = 9 . 5 1 x 1 0 " 2 c m 2 , t = 3 .50 x 1 0 " 2 cm a/a* k / k g t / t o 1 5 . 2 6 .55 1 1 . 7 1.78 * <r g = 2 . 3 2 x 1 0 4 o h m ' 1 c m ' 1 The d a t a i n d i c a t e a c o n s i d e r a b l e enhancement i n t h e c o n d u c t i v i t y a l o n g t h e b a s a l p l a n e , and t h e a/ag v a l u e o f 6 . 5 5 p o i n t s t o e x t e n s i v e e l e c t r o n t r a n s f e r f r o m g r a p h i t e t o t h e i n t e r c a l a n t . A l t h o u g h i t i s e v i d e n t f r o m a l l t h e i n f o r m a t i o n p r e s e n t e d so f a r t h a t I ( S 0 3 F ) 3 a c t s as an a c c e p t o r i n t h e above s y n t h e s i s , t h e e x a c t e x t e n t o f c h a r g e t r a n s f e r and t h e a n i o n s f o r m e d i n t h e i n t e r c a l a n t l a y e r on c h a r g e t r a n s f e r a r e m a j o r q u e s t i o n s w h i c h s t i l l need t o be r e s o l v e d . a x l O - * ( o h m " 1 c m " 1 ) - 115 - 4 . 2 . 3 I n t e r c a l a t i o n o f K [ I ( S 0 3 F ) 4 ] The r a t i o n a l e f o r a t t e m p t i n g t h e i n t e r c a l a t i o n o f t h e s o l v a t e d [ I ( S 0 3 F ) 4 ] " i o n comes f r o m t h e i n a b i l i t y t o c l e a r l y i n t e r c a l a t e I 2 + ( s o l v ) • w h i c h was d i s c u s s e d i n Sec. 4 . 2 . 1 . I t was assumed t h a t t h e i n i t i a l o x i d a t i o n o f t h e g r a p h i t e l a t t i c e a c c o r d i n g t o C n — > C n + + e" w o u l d i m p a r t p o s i t i v e c h a r g e s on t h e g r a p h i t e l a y e r s , w h i c h i n t u r n w o u l d l e a d t o e l e c t r o s t a t i c r e p u l s i o n b e t w e e n t h e g r a p h i t e l a t t i c e and t h e i n t e r c a l a n t . I t mus t a l s o be r e c a l l e d t h a t c a t i o n i n t e r c a l a t i o n i s i n d e e d r a r e and t h a t s u c h s i m p l e c a t i o n s l i k e N 0 + o r N 0 2 + o x i d i z e g r a p h i t e , b u t do n o t i n t e r c a l a t e t h e m s e l v e s . However , i n t h e case o f n e u t r a l i n t e r c a l - a n t s s u c h as I ( S 0 3 F > 3 and Br(SC"3F)3 ( t o be d i s c u s s e d i n Sec. 4 . 3 . 2 ) , r e l a t i v e l y h i g h p e r c e n t a g e s o f i o d i n e and b r o m i n e , i . e . 1 8 . 6 0 and 1 0 . 5 6 r e s p e c t i v e l y , w e r e f o u n d i n t h e i n t e r c a l a t e d p r o d u c t s . I n t e r e s t i n g l y , t h e f i r s t s t a g e compounds t h u s o b t a i n e d d i d n o t show s o l v e n t i n t e r c a l a - t i o n a t h i g h i n t e r c a l a n t c o n c e n t r a t i o n s . T h i s t h e n s u g g e s t s t h a t [ H a l ( S 0 3 F ) 4 ] " w i l l i n t e r c a l a t e w e l l a g a i n , p r o v i d e d t h a t t h e a n i o n i s a s u f f i c i e n t l y s t r o n g o x i d i z i n g a g e n t . I n o r d e r t o v e r i f y t h i s h y p o t h e - s i s , t h e n e g a t i v e l y c h a r g e d [ I ( S 0 3 F ) 4 ] " was u s e d as t h e r e a c t i n g s p e c i e s i n f l u o r o s u l f u r i c a c i d . As e x p l a i n e d i n Sec. 4 . 1 . 4 , s o l u t i o n s t u d i e s o f K [ I ( S 0 3 F ) 4 ] i n H S O 3 F have n o t b e e n r e p o r t e d up t o now, a l t h o u g h t h e s a l t d i s s o l v e s q u i t e e a s i l y i n t h e a c i d , g i v i n g I ( S 0 3 F ) 4 " i o n s . F u r t h e r m o r e , t h e f o l l o w i n g e q u i l i b r i u m i s a l s o p o s s i b l e i n s o l u t i o n , I ( S 0 3 F ) 4 " + H S O 3 F T — » H [ I ( S 0 3 F ) 4 ] + S O 3 F " - 116 - Hence t h e e x a c t n a t u r e o f t h e o x i d i z i n g a g e n t ( s ) c a n n o t be deduced c l e a r l y i n t h i s s y n t h e s i s . However , t h e g r e e n c o l o r o b s e r v e d f o r t h e f i l t r a t e i n d i c a t e s t h a t I + 3 ( f r o m I ( S 0 3 F > 4 " o r f r o m n e u t r a l H [ I ( S 0 3 F ) 4 ] ) has b e e n r e d u c e d b y g r a p h i t e t o I + 1 / 2 ( b l u e ) a n d / o r I + 1 / 3 ( b r o w n ) d u r i n g t h e i n i t i a l i n t e r c a l a t i o n p r o c e s s . A s i m i l a r o b s e r v a t i o n was made d u r i n g t h e g r a p h i t e - I ( S 0 3 F ) 3 s y n t h e s i s , as d i s c u s s e d i n Sec. 4 . 2 . 2 . The e l e m e n t a l a n a l y s i s v a l u e s i n d i c a t e a compound w i t h c o m p o s i t i o n C g 6 l . 1 0 . 5 1 S O 3 F . An a l t e r n a t i v e f o r m u l a such as C g 6 I ( S 0 3 F ) 4 . 6 . 5 I S O 3 F c a n a l s o be w r i t t e n f o r t h e f i n a l p r o d u c t . Two i m p o r t a n t f e a t u r e s can be o b s e r v e d i n t h e c o m p o s i t i o n o f t h e p r o d u c t : a ) s i g n i f i c a n t amount o f i o d i n e i n t e r c a l a t i o n ( 5 . 5 5 % ) , and b ) t h e absence o f s o l v e n t ( H S O 3 F ) i n t h e i n t e r c a l a t e d p r o d u c t . These two f a c t o r s s u g g e s t t h a t i n a d d i t i o n t o n e u t r a l i n t e r c a l a n t s s u c h as I ( S 0 3 F ) 3 and B r ( S 0 3 F ) 3 , a n i o n s l i k e I ( S 0 3 F ) 4 " i n H S O 3 F may a l s o f u n c t i o n as o x i d a t i v e i n t e r c a l a n t s when r e a c t e d w i t h g r a p h i t e . The p r e s e n c e o f n e u t r a l o r n e g a t i v e l y c h a r g e d i n t e r c a l a n t s seems t o l e a d t o w a r d p r e f e r e n t i a l s o l u t e i n t e r c a l a t i o n , whereas i n t e r c a l a n t s p e c i e s c a r r y i n g a p o s i t i v e c h a r g e such as l 2 + ( s o l v ) g i v e p r e d o m i n a n t l y s o l v e n t i n t e r c a l a t e d p r o d u c t s . The l o w c a r b o n c o n t e n t f o u n d f o r t h e compound C g g I . 1 0 . 5 I S O 3 F makes i t r e a s o n a b l e t o assume t h a t t h e p r o d u c t i s o f l o w s t a g e (most p r o b a b l y s t a g e o n e ) . A l s o , t a k i n g i n t o c o n s i d e r a t i o n t h a t t h e r e a r e 1 0 . 5 1 S O 3 F " g r o u p s p e r u n i t f o r m u l a , t h e c o m p o s i t i o n seems t o i n d i c a t e t h e l i m i t i n g v a l u e f o r t h i s s y n t h e s i s . The -- 9F-NMR s p e c t r u m o f t h e s o l i d p r o d u c t showed o n l y a s i n g l e 117 - b r o a d r e s o n a n c e a t 18 ppm, w h i c h e x c l u d e s t h e p r e s e n c e o f any chemiad - s o r b e d o r condensed i n t e r c a l a n t s i n t h e f i n a l compound ( F i g . 4 . 6 ) . The r e s u l t s o b t a i n e d i n t h e above s y n t h e s i s i n d i c a t e t h e f e a s i b i l - i t y o f o n l y s o l u t e i n t e r c a l a t i o n i n a p r o t o n i c s o l v e n t medium l i k e H S O 3 F . I t i s a l s o c l e a r f r o m t h i s s t u d y , as i n I ( S 0 3 F ) 3 and B r ( S 0 3 F ) 3 i n t e r c a l a t i o n , t h a t o x i d a t i v e i n t e r c a l a t i o n does o c c u r d u r i n g t h e s y n t h e s i s . The absence o f a c i d i n t h e p r o d u c t i s p o s s i b l y due t o t h e g r e a t e r a b i l i t y o f t h e i o d i n e s p e c i e s t o u n d e r g o o x i d a t i v e i n t e r c a l a t i o n w i t h g r a p h i t e . I n summary, i t a p p e a r s t h a t K [ I ( S 0 3 F ) 4 ] i n H S O 3 F , w h i c h may be d e f i n e d as a base i n t h e a c i d , i s a s u f f i c i e n t l y good o x i d i z i n g a g e n t t o e f f e c t i n t e r c a l a t i o n . However , t h e S 0 3 F " ^ s o ^ v j i o n s p r e s e n t , p r o v i d e a c o m p e t i t i o n f o r [ I (SC>3F)4 ] " as i n t e r c a l a n t s d u r i n g t h e r e a c t i o n . W h i l e a h i g h e r i o d i n e c o n c e n t r a t i o n i s a c h i e v e d i n t h e GIC when [ I ( S C - 3 F ) 4 ] " a c t s as t h e i n t e r c a l a n t t h a n f o r l 2 + ( s o l v ) - a n a p p r o x i m a t e l y n e u t r a l medium i s f o u n d i n I ( S 0 3 F ) 3 ( a n d Br(SC>3F)3) i n t e r c a l a t i o n , w h i c h seems t o p r o v i d e a b e t t e r o p p o r t u n i t y f o r t h e i n t e r c a l a t i o n o f i o d i n e f l u o r o s u l f a t e s i n t o g r a p h i t e . 4 . 2 . 4 A t t e m p t e d I n t e r c a l a t i o n o f I S 0 3 F S o l u t i o n s o f I S O 3 F were r e a c t e d w i t h g r a p h i t e i n a manner s i m i l a r t o o t h e r i o d i n e f l u o r o s u l f a t e s d i s c u s s e d so f a r . When m i x e d w i t h g r a p h i t e , inhomogeneous s u s p e n s i o n m i x t u r e s were o b s e r v e d . The p r o d u c t s were vacuum d r i e d f o r 3 h , and when t o t a l l y d r y t h e samples i n d i c a t e d p o s s i b l e i n t e r c a l a t i o n s i n c e t h e p r o d u c t s u r f a c e s a p p e a r e d t o be b l a c k - 118 - 119 - b l u e i n c o l o r . However , t h e 1 9 F - N M R s p e c t r a o f t h e compounds gave r e s o n a n c e s i n t h e r e g i o n o f ~ 4 4 ppm, i n d i c a t i n g o n l y s u r f a c e a d s o r b e d f l u o r o s u l f a t e s p e c i e s . Hence i t was c o n c l u d e d t h a t no o x i d a t i v e i n t e r c a l a t i o n has o c c u r r e d i n t h e s y n t h e s i s b e t w e e n I S O 3 F and g r a p h i t e . The absence o f any o x i d i z i n g s p e c i e s i n t h e s o l u t i o n s o f I S O 3 F may be r e s p o n s i b l e f o r t h e l a c k o f i n t e r c a l a t i o n . A c o m p a r a b l e o b s e r v a t i o n has b e e n r e p o r t e d e a r l i e r f o r p u r e I S O 3 F i n t e r c a l a t i o n . 4 3 The s o l u t i o n s c o u l d behave i n a manner s i m i l a r t o I o d i n e i t s e l f , w h i c h does n o t i n t e r c a l a t e i n t o g r a - p h i t e , s i n c e i t does n o t meet t h e e n e r g y r e q u i r e m e n t s t o open t h e g a l l e r i e s i n t h e g r a p h i t e l a t t i c e t o i n i t i a t e t h e i n t e r c a l a t i o n p r o c e s s . 4 . 3 I n t e r c a l a t i o n o f Bromine C o n t a i n i n g Compounds 4 . 3 . 1 I n t e r c a l a t i o n o f B r S 0 3 F The r e a c t i o n b e t w e e n l i q u i d b r o m i n e ( I ) f l u o r o s u l f a t e and g r a p h i t e has b e e n c a r r i e d o u t e a r l i e r and a f i r s t s t a g e compound w i t h a c o m p o s i - t i o n o f C i 2 B r S ° 3 F w a s r e p o r t e d . 4 3 • - - 0 2 However , t h e s y n t h e t i c r e a c t i o n b e t w e e n t h e s e compounds i n f l u o r o s u l f u r i c a c i d p r o c e e d s i n a s i g n i f i - c a n t l y d i f f e r e n t manner . The r e l a t i v e l y s h o r t i n t e r c a l a t i o n t i m e (18 h ) i n d i c a t e s a f a s t o x i d a t i o n o f t h e g r a p h i t e l a t t i c e . The m i c r o a n a l y s i s d a t a w i t h F:S r a t i o o f 1 : 1 . 0 2 i n d i c a t e a compound o f f o r m u l a C ] L l H S O 3 F . 0 - 5 S O 3 F . x B r S O 3 F ( x < 0 . 0 2 5 ) . As shown by t h e s e r e s u l t s , o n l y a s m a l l f r a c t i o n o f - 120 - b r o m i n e , assumed t o be i n t h e f o r m o f BrS03F, was f o u n d as an i n t e r - c a l a t e . An a l t e r n a t i v e c o m p o s i t i o n i s a l s o p o s s i b l e f o r t h e p r o d u c t , i . e . C 1 1 H S 0 3 F . ( 0 . 5 + x ) S 0 3 F . x B r . The e x i s t e n c e o f B r S 0 3 F as s u c h i n t h e g r a p h i t e l a t t i c e c a n n o t be c o n f i r m e d b y m i c r o a n a l y s i s ( o r 1 9 F - N M R ) v a l u e s . I t may e x i s t as an a n i o n i c s p e c i e s among t h e i n t e r c a l a n t l a y e r s on c h a r g e t r a n s f e r . 1 0 1 The c - a x i s l a y e r r e p e a t d i s t a n c e I c and t h e l o w c a r b o n c o n t e n t f o u n d b y m i c r o a n a l y s i s p o i n t s t o a f i r s t s t a g e i n t e r c a l a t i o n compound. The I c v a l u e o f 8 . 2 2 A i s c l o s e t o t h e v a l u e o b t a i n e d f o r t h e i n t e r c a l a t i o n p r o d u c t w i t h l 2 + ( s o l v ) a s t * i e o x i d i z i n g a g e n t , d i s c u s s e d i n Sec. 4 . 2 . 1 ( - 7 . 9 9 A). T h i s i s e x p e c t e d s i n c e b o t h p r o d u c t s c o n t a i n p r e d o m i n a n t l y t h e same i n t e r c a l a n t s , i . e . n e u t r a l HS0 3 F m o l e c u l e s and S 0 3 F " g r o u p s . As shown b e f o r e , t h i s i s a t y p i c a l i n t e r l a y e r s e p a r a t i o n d i s t a n c e o b s e r v e d f o r f i r s t s t a g e g r a p h i t e a c i d f l u o r o s u l f a t e s . 4 3 > ->8 The 1 9 F - N M R s p e c t r u m o f t h e compound does n o t d i f f e r e n t i a t e b e t w e e n t h e HS0 3 F and S 0 3 F ( o r B r S 0 3 F ) r e s o n a n c e s , and c o n s e q u e n t l y o n l y a s i n g l e s i g n a l a t 1 4 . 9 2 ppm i s o b s e r v e d ( F i g . 4 . 7 ) . T h i s c h e m i c a l s h i f t v a l u e a g r e e s more w i t h G I C ' s h a v i n g g e n e r a l c o m p o s i t i o n C n . X H S 0 3 F . Y S 0 3 F , t h a n w i t h h a l o g e n f l u o r o s u l f a t e i n t e r c a l a t e d c o m p o u n d s . 4 3 I n summary, i t i s c l e a r f r o m t h e above d i s c u s s i o n t h a t t h e i n t e r - c a l a t i o n o f p u r e B r S 0 3 F and as a HS0 3 F s o l u t i o n r e s u l t s i n t h e f o r m a t i o n o f q u i t e d i f f e r e n t p r o d u c t s . D i r e c t i n t e r c a l a t i o n employs B r S 0 3 F as t h e o n l y o x i d i z i n g a g e n t and as a r e s u l t , i t i s f o u n d as t h e s o l e i n t e r - c a l a t e . S o l u t i o n s o f B r S 0 3 F i n f l u o r o s u l f u r i c a c i d l e a d t o a s t a g e one GIC, b u t now S 0 3 F " and HS0 3 F a r e t h e p r e d o m i n a n t i n t e r c a l a t e s w i t h B r S 0 3 F o r a s i m i l a r b r o m i n e - S 0 3 F s p e c i e s p r e s e n t as a m i n o r i n t e r c a l a t e . - 121 - e 4 . 7 : 1 9 F - N M R S p e c t r u m o f CnHSOoF-5S0 ,F ( x < 0 . 0 2 5 ) 3 - 122 - However , n e i t h e r m i c r o a n a l y s i s , i n t e r l a y e r s e p a r a t i o n v a l u e s f r o m X - r a y d a t a o r 1 9 F - N M R s p e c t r a a l l o w a c l e a r i d e n t i f i c a t i o n o f a l l t h e i n t e r - c a l a t e s i n t h e above compound. 4 . 3 . 2 I n t e r c a l a t i o n o f B r ( S 0 3 F ) 3 The c h e m i c a l and p h y s i c a l p r o p e r t i e s o f Br(SC>3F)3, a s o l i d a t room t e m p e r a t u r e w i t h a t e n d e n c y t o w a r d s d e c o m p o s i t i o n a t t h i s t e m p e r a t u r e , makes t h i s m a t e r i a l u n s u i t a b l e f o r d i r e c t i n t e r c a l a t i o n . A p r e v i o u s l y r e p o r t e d r o u t e , t h e o x i d a t i o n o f i n t e r c a l a t e d B r S C ^ F , 4 3 • - - 0 2 i n t h e f o r m o f C ^ 2 B r S 0 3 F y i e l d s a compound o f g e n e r a l c o m p o s i t i o n C i g B r ^ C ^ F ) 3 . I t d o e s , however a p p e a r f r o m b o t h t h e h i g h i n t e r c a l a t e t o c a r b o n r a t i o and t h e 1 9 F - N M R s p e c t r u m t h a t some Br (S03F>3 i s n o t i n t e r c a l a t e d and p o s s i b l y o n l y s u r f a c e a d s o r b e d . T h e r e f o r e , i n t e r c a l a t i o n o f Br(SC>3F)3 f r o m s o l u t i o n s i n H S O 3 F i s a t t e m p t e d . As seen i n Sec. 4 . 1 . 5 , B r ( S 0 3 F ) 3 i s q u i t e s t a b l e i n f l u o r o s u l f u r i c a c i d , and l i t t l e d i s s o c i a t i o n and v i r t u a l l y no d i s p r o p o r t i o n a t i o n a r e o b s e r v e d . 9 7 Hence, i t seems a l m o s t c e r t a i n t h a t B r ( S 0 3 F > 3 f u n c t i o n s as t h e o x i d i z i n g s p e c i e s i n t h e r e a c t i o n w i t h g r a p h i t e . The b l u i s h t i n t o b s e r v e d on t h e g r a p h i t e s u r f a c e a t t h e end o f t h e r e a c t i o n p e r i o d (24 h ) c o n f i r m s i n t e r c a l a t i o n o f t h e l a t t i c e b y B r ( S 0 3 F > 3 . The i n t e r c a l a t e d p r o d u c t i n d i c a t e s a c o m p o s i t i o n o f C 2 g 3 B r . 4 S 0 3 F , d e r i v e d f r o m m i c r o - a n a l y s i s r e s u l t s . The c o m p o s i t i o n o f t h e GIC c a n a l s o be f o r m u l a t e d as c 2 6 . 8 B r ( S 0 3 F > 3 - S 0 3 F C 2 6 . 8 B r S 0 3 F - 3 S 0 3 F - A s compared t o C 1 6 B r ( S O 3 F ) 3 , w h i c h shows a c a r b o n p e r c e n t a g e o f o n l y 3 3 . 8 , C 2 g gBr.4SC>3F s u g g e s t s a - 123 - p r o d u c t c l o s e r t o t h e l i m i t i n g c o m p o s i t i o n , c o n s i d e r i n g t h e i n t e r c a l a t e s i z e . T h i s c a n be seen c l e a r l y f r o m X - r a y and 1 9 F - N M R d a t a o b t a i n e d f o r t h e p r o d u c t . The X - r a y powder v a l u e f o r t h e l a y e r r e p e a t d i s t a n c e I c = 7 .88 A p o i n t s t o a s t a g e one compound. I n a d d i t i o n , t h e s m a l l I c v a l u e a l s o s u g g e s t s e x t e n s i v e c h a r g e t r a n s f e r b e t w e e n t h e g r a p h i t e l a t t i c e and t h e i n t e r c a l a t e ( s ) . The 1 9 F - N M R s p e c t r u m o f t h e compound c o n s i s t s o f o n l y a s i n g l e b r o a d r e s o n a n c e a t 12 ppm, w h i c h i s c o m p a t i b l e w i t h c h e m i c a l s h i f t s o b s e r v e d f o r o t h e r S O 3 F " i n t e r c a l a t e d g r a p h i t e c o m p o u n d s . 4 3 I t i s i n t e r e s t i n g t o n o t e t h a t f o r t h e C ^ 6 B r ( S 0 3 F ) 3 compound, as d i s c u s s e d e a r l i e r , a b r o a d peak i s seen a t 10 ppm, i n a d d i t i o n t o a s e c o n d r e s o n a n c e a t 3 8 . 3 ppm ( r e l a t i v e t o C F C I 3 ) i n t h e 1 9 F - N M R s p e c t r u m . The 1 9 F - N M R s p e c t r a o f C 2 6 g B r . 4 S 0 3 F show t h e absence o f any s u r f a c e a d s o r b e d o r condensed i n t e r c a l a n t s i n t h e f i n a l p r o d u c t . The U V - v i s i b l e s p e c t r a o f t h e f i l t r a t e s were t a k e n i n t h e r a n g e o f A = 360 -750 nm, i n o r d e r t o d e t e c t any r e d u c e d b r o m i n e s p e c i e s such as B r 3 + o r B r 2 + . However , t h e s e a t t e m p t s d i d n o t p r o v e t o be s u c c e s s f u l . The s p e c t r a o b t a i n e d were s i m i l a r t o t h e ones o b s e r v e d f o r Br (S03F>3 i n H S O 3 F ( F i g . 4 . 3 , c u r v e D ) . Even i f B r 3 + c a t i o n s h a d b e e n p r e s e n t i n t h e f i l t r a t e , t h e y may have e x i s t e d i n v e r y l o w c o n c e n t r a t i o n s b e l o w t h e d e t e c t i o n l i m i t , as o n l y s m a l l amounts o f g r a p h i t e ( - 1 2 . 5 mmol) were u s e d as t h e r e d u c i n g a g e n t i n t h e r e a c t i o n s . As an e x a m p l e , f o r 1 2 . 5 mmol g r a p h i t e and 2 . 0 2 mmol B r ( S 0 3 F ) 3 ( t y p i c a l a m o u n t s , see Sec 3 . 4 ) o n l y 0 . 1 6 mmol B r 3 + w o u l d be p r o d u c e d , and i n t h e same f i l t r a t e 1.86 mmol u n r e a c t e d B r ( S 0 3 F ) 3 w o u l d be p r e s e n t as w e l l . I n summary, i t a p p e a r s t h a t n e i t h e r m i c r o a n a l y s i s n o r any o f t h e - 124 - p h y s i c a l t e c h n i q u e s u s e d a r e a b l e t o d i f f e r e n t i a t e b e t w e e n two p o s s i b l e i n t e r c a l a t e f o r m u l a t i o n s as e i t h e r BrCSC^F)^ " o r B r ( S 0 3 F ) 3 + S O 3 F " . A l s o , i t i s n o t e x a c t l y c l e a r why t h e p r o d u c t s d e r i v e d f r o m t h e i n t e r - c a l a t i o n o f I ( S 0 3 F ) 3 and B r ( S 0 3 F ) 3 , b o t h f r o m s o l u t i o n s i n H S O 3 F , d i f f e r i n t h e i r c o m p o s i t i o n s w i t h a p o s s i b l e n e u t r a l i n t e r c a l a t e p r e s e n t i n one case and a n e g a t i v e l y c h a r g e d s p e c i e s i n t h e o t h e r . 4 . 3 . 3 I n t e r c a l a t i o n o f K [ B r ( S 0 3 F ) 4 ] As i n t h e case o f K [ I ( S C ^ F ^ ] - g r a p h i t e s y n t h e s i s , t h e i n t e r - c a l a t i o n r e a c t i o n o f K [ B r ( S C - 3 F ) 4 ] was c a r r i e d o u t i n o r d e r t o s t u d y t h e o x i d a t i v e i n t e r c a l a n t b e h a v i o r o f [ B r ( S C - 3 F ) 4 ] ~ w i t h g r a p h i t e (see Sec. 4 . 2 . 3 ) . S i n c e b o t h K [ I ( S 0 3 F ) 4 ] and K [ B r ( S 0 3 F ) 4 ] e x h i b i t v e r y s i m i l a r c h e m i c a l b e h a v i o u r i n f l u o r o s u l f u r i c a c i d , t h e r e a c t i o n o f t h e s e com- pounds w i t h g r a p h i t e l e a d , n o t s u r p r i s i n g l y , t o G I C ' s h a v i n g c l o s e l y r e l a t e d c h e m i c a l and p h y s i c a l p r o p e r t i e s . Hence, t h e i n t e r c a l a t i o n o f K [ B r ( S C " 3 F ) 4 ] w i l l be e x p l a i n e d o n l y b r i e f l y I n t h e f o l l o w i n g d i s c u s s i o n . I n H S 0 3 F - K [ B r ( S 0 3 F ) 4 ] s o l u t i o n s , b o t h [ B r ( S 0 3 F ) 4 ] " and H [ B r ( S 0 3 F ) 4 ] c a n e x i s t as p o t e n t i a l o x i d i z i n g a g e n t s . I n a n a l o g y w i t h t h e K [ I ( S C > 3 F ) 4 ] - g r a p h i t e r e a c t i o n , i t c o u l d be assumed t h a t d u r i n g t h e s y n t h e s i s , B r + 3 i s r e d u c e d b y g r a p h i t e t o B r 4 " - - / 2 a n d / o r B r + 1 / 3 i n t h e a c i d medium. However , B r + 1 / 2 may n o t be p r e s e n t as a s t a b l e s p e c i e s i n f l u o r o s u l f u r i c a c i d . 9 7 The m i c r o a n a l y s i s r e s u l t s , w h i c h i n d i c a t e a c o m p o s i t i o n o f C g 4 B r . l l . 2 2 S 0 3 F , show a s u b s t a n t i a l amount o f b r o m i n e i n t h e p r o d u c t - 125 - ( c f . C g g I . 1 0 . 5 1 S O 3 F ) . The f o r m u l a o f t h e compound can a l s o be e x p r e s s e d as C g 4 B r ( S 0 3 F ) 4 7 . 2 2 S O 3 F . The absence o f h y d r o g e n i n t h e i n t e r c a l a t e d compound s u g g e s t s a s o l v e n t - f r e e GIC. A g a i n , as i n t h e K f l C S C ^ F ) ^ ] r e a c t i o n , t h e r e l a t i v e l y s m a l l c a r b o n p e r c e n t a g e seen f o r t h e p r o d u c t p o i n t s t o a l o w s t a g e compound. I t i s c l e a r f r o m t h e o b s e r v a t i o n s made so f a r f o r b o t h K t l C S C ^ F ) ^ ] and K [ B r ( S C ^ F ) ^ ] i n s e r t i o n r e a c t i o n s t h a t o x i d a t i v e i n t e r c a l a t i o n does t a k e p l a c e d u r i n g t h e s y n t h e s e s . T h e r e f o r e , t h e c o n c l u s i o n s d rawn f o r t h e K[ I ( S C ^ F ^ ] - g r a p h i t e s y n t h e s i s a p p l y e q u a l l y w e l l f o r t h e p r e s e n t r e a c t i o n t o o . I n summary, a l t h o u g h K[Br(SC"3F)4] i n f l u o r o s u l f u r i c a c i d f u n c t i o n s as a r e l a t i v e l y good o x i d i z i n g a g e n t , t h e i n t e r c a l a t i o n o f h i g h c o n c e n t r a t i o n s o f b r o m i n e - f l u o r o s u l f a t e s c a n be a c h i e v e d more e f f e c t i v e l y b y u t i l i z i n g an a p p a r e n t l y n e u t r a l i n t e r c a l a n t s u c h as B r ( S 0 3 F ) 3 . 4 . 3 . 4 I n t e r c a l a t i o n o f I B r j S C ^ F I t was seen e a r l i e r I n Sec. 4 . 2 . 1 t h a t I 2 ( s o l v ) p r o m o t e d i n t e r c a l a t i o n p r o d u c e d G I C ' s w i t h p r e d o m i n a n t l y S O 3 F " and n e u t r a l H S O 3 F m o l e c u l e s as i n t e r c a l a t e s . T h e r e f o r e , i t seems i n t e r e s t i n g t o c a r r y o u t a s i m i l a r c a t i o n - p r o m o t e d s y n t h e t i c r e a c t i o n i n H S O 3 F u s i n g I B r 2 S 0 3 F as t h e i n t e r c a l a n t . As o b s e r v e d i n Sec. 4 . 1 . 8 , I B ^ S O ^ F behaves as a s t r o n g base i n f l u o r o s u l f u r i c a c i d , u n d e r g o i n g c o m p l e t e d i s s o c i a t i o n t o g i v e I B r 2 + ( s o l v ) and S 0 3 F " ( s o ^ v j i o n s . Hence, d u r i n g t h e r e a c t i o n w i t h g r a p h i t e , i t i s p o s s i b l e t h a t I B r 2 + may f u n c t i o n as t h e o x i d i z i n g a g e n t . - 126 - A r e l a t i v e l y l o n g r e a c t i o n t i m e (2 d a y s ) was r e q u i r e d f o r t h i s s y n t h e s i s , s u g g e s t i n g weaker o x i d i z i n g a b i l i t y o f I B r 2 + i o n s . The m e t a l l i c b l u e c o l o r o b s e r v e d on t h e g r a p h i t e powder s u r f a c e c o n f i r m e d i n i t i a l i n t e r c a l a t i o n o f t h e l a t t i c e . The c o m p o s i t i o n a l a n a l y s i s o f t h e i n t e r c a l a t e d p r o d u c t i s n o t c o m p l e t e and does n o t i n c l u d e t h e h a l o g e n s and s u l f u r . Due t o t h i s r e a s o n , a g e n e r a l f o r m u l a c a n n o t be f o r m u l a t e d f o r t h e f i n a l p r o d u c t . However , t h e l o w c a r b o n c o n t e n t and t h e absence o f h y d r o g e n i n t h e GIC a r e s i g n i f i c a n t w i t h r e g a r d t o t h e s t a g e and c o m p o s i t i o n . The c a r b o n p e r c e n t a g e o b t a i n e d b y m i c r o a n a l y s i s f a l l s w i t h i n t h e r a n g e o f f i r s t s t a g e i n t e r c a l a t i o n compounds ( see Sec. 3 . 1 , 3 . 3 , 3 . 5 and 3 . 6 ) . I n o r d e r t o c o n f i r m t h i s o b s e r v a t i o n , X - r a y d i f f r a c - t i o n v a l u e s o f t h e sample have t o be t a k e n i n t o a c c o u n t . I n c o n t r a s t t o o t h e r c a t i o n p r o m o t e d i n t e r c a l a t i o n r e a c t i o n s d i s c u s s e d i n t h i s t h e s i s ( i . e . l 2 + ( s o l v ) a n c i N 0 + ( s o l v ) > t o D e d i s c u s s e d i n Sec. 4 . 4 ) , t h e p r e s e n t s y n t h e s i s does n o t i n d i c a t e a p p r e c i a b l e h y d r o g e n i n s e r t i o n . T h i s o b s e r v a t i o n l e a d s t o t h e c o n c l u s i o n t h a t n e u t r a l a c i d m o l e c u l es a r e a b s e n t i n t h e GIC. T h e r e f o r e , I t i s v e r y l i k e l y t h a t t h e f i n a l p r o d u c t w i l l c o n t a i n S O 3 F " g r o u p s , and p o s s i b l y h a l o g e n s p e c i e s as i n t e r c a l a t e s . However , t h e p r e s e n c e o f h a l o g e n i n t h e g r a p h i t e l a t t i c e has t o be v e r i f i e d b y e l e m e n t a l a n a l y s i s . I n summary, i t can be assumed t h a t t h e r e a c t i o n b e t w e e n I B ^ S C ^ F and g r a p h i t e i n H S O 3 F p r o c e e d s i n a d i f f e r e n t manner when compared t o * 2 + ( s o l v ) o r ^ ^ ( s o l v ) i n d u c e d r e a c t i o n s , t h e most i m p o r t a n t d i f f e r e n c e b e i n g t h e absence o f a c i d m o l e c u l e s as i n t e r c a l a t e s . To u n d e r s t a n d t h i s s y s t e m i n g r e a t e r d e t a i l , a d d i t i o n a l d a t a such as e l e m e n t a l h a l o g e n c o m p o s i t i o n s , X - r a y d i f f r a c t i o n and 1 9 F - N M R have t o be o b t a i n e d f o r t h e - 127 - i n t e r c a l a t e d compound. 4 . 4 N i t r o s o n i u m I o n ( N 0 + ) P romoted I n t e r c a l a t i o n The s y n t h e s i s o f i n t e r c a l a t i o n compounds u s i n g N 0 + ( a n d NC>2+) as t h e o x i d i z i n g a g e n t i n n o n - p r o t o n i c s o l v e n t s s u c h as n i t r o m e t h a n e , w h i c h i s a m o d e r a t e l y p o l a r , c o o r d i n a t i n g and w e a k l y i o n i z i n g s o l v e n t , was d i s c u s s e d i n Sec. 1 . 8 . 3 . Fo r e x a m p l e , i t was f o u n d t h a t t h e compounds t h u s made have t h e i d e a l c o m p o s i t i o n C 2 3 n + M F g " ( s o l v e n t ) y , where n i s t h e s t a g e , M - P o r Sb, and y u s u a l l y - 1 . 7 t o 2 . 5 . 3 6 T h e r e f o r e , i t seems i n t e r e s t i n g t o c a r r y o u t a s i m i l a r s t u d y i n a p r o t o n i c s o l v e n t l i k e H S O 3 F , w h i c h i s s t r o n g l y i o n i z i n g . N O S O 3 F was u s e d as t h e i n t e r c a l a n t d i s s o l v e d i n f l u o r o s u l f u r i c a c i d . As shown b e f o r e i n Sec. 4 . 1 . 7 , s o l i d N O S O 3 F i s e x t e n s i v e l y d i s s o c i a t e d i n t o N 0 + and S O 3 F " a c c o r d i n g t o : H S O 3 F N O S 0 3 F ( s o l v ) 5 = f c N C - + ( s o l v ) + S 0 3 F - ( s o l v ) I n a n a l o g y t o n o n - p r o t o n i c s o l v e n t s y n t h e s i s , i t was e x p e c t e d t h a t N 0 + ( s o l v ) w o u l d f u n c t i o n as t h e o x i d a n t i n t h e r e a c t i o n w i t h g r a p h i t e , as h a d b e e n t h e case i n n i t r o m e t h a n e . The r e a c t a n t c o n c e n t r a t i o n s and r e a c t i o n t i m e s were v a r i e d i n o r d e r t o o b s e r v e any e f f e c t on t h e c o m p o s i t i o n o f t h e f i n a l p r o d u c t . When t h e G I C ' s f r o m t h e s e s y n t h e s e s were a n a l y z e d f o r c a r b o n , h y d r o g e n and - 128 - n i t r o g e n , v a r y i n g c o m p o s i t i o n s were o b t a i n e d and even t h e same p r e p a r a - t i o n gave i n c o n s i s t e n t e l e m e n t a l a n a l y s i s v a l u e s ( d e t a i l e d v a l u e s o f CHN c o m p o s i t i o n s a r e g i v e n i n T a b l e 3 . 2 ) . An e x p l a n a t i o n f o r t h e above o b s e r v a t i o n s may be f o u n d i n t h e inhomogeneous n a t u r e o f t h e sample c o m p o s i t i o n s . The m i c r o a n a l y t i c a l d a t a d i d n o t i n d i c a t e t h e p r e s e n c e o f n i t r o g e n i n t h e f i n a l p r o d u c t s . T h i s s u g g e s t s t h a t no n e u t r a l N O S O 3 F , NO o r any o t h e r n i t r o g e n c o n t a i n i n g s p e c i e s has been c o i n t e r c a l a t e d . Hence, t h e r o l e o f N 0 + ( s o ] _ v ) as t h e o x i d i z i n g a g e n t seems c l e a r f r o m t h e r e s u l t s o b t a i n e d f o r p r o d u c t c o m p o s i t i o n s . Assuming t h a t t h e r e m a i n i n g i n t e r c a l a n t s i n t h e GIC a r e S O 3 F " g r o u p s , a g e n e r a l f o r m u l a such as C n xS03F.yHSO3F c a n be d e r i v e d f r o m m i c r o a n a l y s i s f o r t h e s e compounds. S i m i l a r c o m p o s i t i o n s have been p r o p o s e d b y H e r o l d e t a l . f o r t h e G I C ' s s y n t h e s i z e d i n a n o n - p r o t o n i c s o l v e n t l i k e n i t r o m e t h a n e 3 ^ ( e . g . C 2 3 n M F g ( s o l v e n t ) y ) . However , t h e c o m p o s i t i o n s o f t h e compounds f o r m e d i n t h e p r o t o n i c s o l v e n t H S O 3 F do n o t s u g g e s t a s i g n i f i c a n t dependence on r e a c t a n t c o n c e n t r a t i o n s o r r e a c t i o n t i m e s (see T a b l e 3 .2 f o r n u m e r i c a l d a t a ) . One g e n e r a l o b s e r v a - t i o n c a n be made s a f e l y : The h i g h c a r b o n p e r c e n t a g e s o b t a i n e d i n d i c a t e t h a t t h e p r o d u c t s a r e o f a h i g h e r s t a g e i n d e x . The X - r a y d i f f r a c t i o n v a l u e m e a s u r e d , w i t h I c = 1 0 . 5 9 ± 0 . 0 3 A, a l s o c o n f i r m s a second s t a g e compound. Fo r a v e r a g e c a r b o n and h y d r o g e n c o m p o s i t i o n s 72% and 0.20%, w i t h S O 3 F " - 2 7 . 8 % , t h e f o r m u l a o f t h e p r o d u c t can be w r i t t e n as C - 7 4 S 0 3 F . 2 - 4 H S 0 3 F , w h i c h shows a s u b s t a n t i a l amount o f s o l v e n t i n t e r c a l a t i o n i n t h e f i n a l p r o d u c t . The 1 9 F - N M R o f t h e sample gave two b r o a d r e s o n a n c e s a t 25 and 36 ppm r e s p e c t i v e l y ( F i g . 4 . 8 ) . T h i s o b s e r v a t i o n d i f f e r s f r o m t h e e a r l i e r 129 - - 130 - 1 9 F - N M R v a l u e s g i v e n f o r c o m p o s i t i o n a l l y homogeneous g r a p h i t e a c i d f l u o r o s u l f a t e s , where o n l y a s i n g l e b r o a d r e s o n a n c e was seen f o r b o t h S O 3 F and H S O 3 F i n t e r c a l a t e s . 4 3 ( see a l s o F i g . 4 . 4 and 4 . 7 ) . Of t h e two v a l u e s , t h e s i g n a l a t 25 ppm i s a s s i g n e d t o t h e S O 3 F " i o n s i n t e r c a l a t e d i n t o g r a p h i t e . The a s s i g n m e n t o f t h e second v a l u e a t 36 ppm t o i n t e r c a l a t e d H S O 3 F i s b a s e d on an e a r l i e r r e p o r t e d o b s e r v a t i o n i n w h i c h a sample o f C 7 S O 3 F w i t h some r e s i d u a l s u r f a c e a d s o r b e d H S O 3 F showed a - - 9 F r e s o n a n c e a t 39 p p m . 4 3 I n a d d i t i o n , a compound o f f o r m u l a C 1 4 S 0 3 F - 1 ' 0 5 H S 0 3 F w a s r e p o r t e d as s h o w i n g two 1 9 F - N M R r e s o n a n c e s a t 1 4 . 1 and 3 5 . 9 ppm r e s p e c t i v e l y . 4 3 As i n t h i s GIC, t h e p r e s e n t p r o d u c t may have S O 3 F and a c i d m o l e c u l e s i n t e r c a l a t e d i n d i f f e r e n t a l t e r n a t e l a y e r s i n t h e g r a p h i t e l a t t i c e , w h i c h w i l l l e a d t o a non-homogemeous p a c k i n g a r r a n g e m e n t a l o n g t h e c - a x i s d i r e c t i o n . The s m a l l u p f i e l d s h i f t o b s e r v e d i n r e g a r d t o H S O 3 F i n t h e 1 9 F - N M R s p e c t r u m ( - 4 . 6 ppm) c o u l d be due t o a l i m i t e d c h a r g e t r a n s f e r f r o m g r a p h i t e t o m o l e c u l a r H S O 3 F . I n c o n t r a s t , t h e l a r g e u p f i e l d s h i f t o f t h e S O 3 F " g r o u p s ( - 1 2 . 4 ppm) s u g g e s t s e x t e n s i v e c h a r g e t r a n s f e r b e t w e e n t h e g r a p h i t e l a t t i c e and S O 3 F i n t h e GIC. A t t e m p t s t o d e t e c t NO i n t h e gas phase b y mass s p e c t r o s c o p y a f t e r i n t e r c a l a t i o n p r o v e d t o be u n s u c c e s s f u l . T h i s i s n o t t o t a l l y u n e x p e c t e d , s i n c e , f o r e x a m p l e , f o r a g e n e r a l f o r m u l a o f C 7 4 S 0 3 F . 2 - 4 H S 0 3 F and - 1 2 . 0 mmol o f g r a p h i t e , o n l y 0 . 1 6 2 mmol o f NO c o u l d be f o r m e d d u r i n g t h e r e a c t i o n . T h i s s m a l l f r a c t i o n o f NO may d i s s o l v e q u i t e e a s i l y i n t h e excess H S O 3 F , hence n e v e r a p p e a r i n g as a v o l a t i l e p r o d u c t i n t h e v a p o r p h a s e . I n a d d i t i o n o x i d a t i o n o f NO i n H S O 3 F and s u b s e q u e n t f u r t h e r r e a c t i o n s o f N 0 2 i n H S O 3 F a r e p o s s i b l e . F i n a l l y , s m a l l amounts o f S O 3 i n H S O 3 F may a c t as an o x i d i z i n g a g e n t , r e s u l t i n g - 131 - i n t h e f o r m a t i o n o f N 0 2 i n i t i a l l y , w h i c h c o u l d s u b s e q u e n t l y i n t e r a c t f u r t h e r . The o v e r a l l r e a c t i o n , b a s e d on t h e r e s u l t s d i s c u s s e d a b o v e , c a n be w r i t t e n as f o l l o w s : H S O 3 F C n + N O S O 3 F > C n S 0 3 F . y . H S 0 3 F + N 0 ( g ) where y - 2 . 4 and n - 7 4 , w h i c h a r e a v e r a g e v a l u e s o f s e v e r a l sample c o m p o s i t i o n s . I n summary, i n t e r c a l a t i o n o f S O 3 F " b y N 0 + o x i d a t i o n i n H S O 3 F does n o t l e a d t o f i r s t s t a g e compounds, as h a d b e e n t h e case i n n i t r o m e t h a n e , a l b e i t u s i n g d i f f e r e n t a n i o n s . 3 ^ The re i s o b v i o u s l y no a d v a n t a g e i n u s i n g t h i s r o u t e o v e r o x i d a t i v e i n t e r c a l a t i o n b y S 2 0 g F 2 i n t h e p r e s e n c e o r absence o f H S O 3 F , t a k i n g i n t o a c c o u n t t h a t N O S O 3 F i s i n i t i a l l y s y n t h e s i z e d f r o m S 2 0 g F 2 - The l a r g e amount o f s o l v e n t i n t e r c a l a t e d i s r a t h e r s u r p r i s i n g . However , t h e o b s e r v a t i o n o f 1 9 F - N M R r e s o n a n c e s i s n o t u n e x p e c t e d . H - b r i d g e d i o n s l i k e [ H ( S 0 3 F ) 2 ] "  1 0 7 a r e o n l y r e a l i s t i c as l o n g as t h e a c i d c o n t e n t i s b e l o w one mole p e r mole S O 3 F . 4 . 5 G e n e r a l Comments and C o n c l u s i o n T h i s t h e s i s has d e s c r i b e d t h e s y n t h e s i s o f b r o m i n e - and i o d i n e f l u o r o s u l f a t e i n t e r c a l a t i o n compounds i n f l u o r o s u l f u r i c a c i d , and some g e n e r a l c o n c l u s i o n s b a s e d on t h i s s t u d y a r e summar ized b e l o w . I n a l l - 132 - t h e s y n t h e t i c r e a c t i o n s , H S O 3 F f u n c t i o n s as an e x c e l l e n t o x i d a t i o n r e s i s t a n t s o l v e n t f o r t h e h i g h l y v i s c o u s and s o l i d i n t e r c a l a n t s l i k e I ( S 0 3 F > 3 and B r ( S 0 3 F > 3 , w h i c h due t o t h e i r p h y s i c a l p r o p e r t i e s and l i m i t e d t h e r m a l s t a b i l i t y c a n n o t be i n t e r c a l a t e d d i r e c t l y i n t o g r a p h i t e . The b r o a d l i q u i d r a n g e o f t h e a c i d a l l o w s w i d e t e m p e r a t u r e v a r i a t i o n s and i t s a b i l i t y t o f o r m s o l u t i o n s w i t h o u t e x t e n s i v e s o l u t e d i s p r o p o r - t i o n a t i o n make t h e s y n t h e s e s r e l a t i v e l y u n c o m p l i c a t e d s i n c e b o t h B r ( S 0 3 F ) 3 and I ( S 0 3 F ) 3 a c t as weak e l e c t r o l y t e s i n H S O 3 F . The o x i d a t i o n o f t h e g r a p h i t e l a t t i c e b y i o d i n e s p e c i e s i n H S O 3 F i s c o n f i r m e d b y t h e o b s e r v e d c o l o r changes i n t h e i n t e r c a l a n t s o l u t i o n s . Whenever I ( S 0 3 F ) 3 , B r ( S 0 3 F ) 3 and K [ H a l ( S 0 3 F ) 4 ] a r e u s e d i n h i g h c o n c e n t r a t i o n s , no a p p r e c i a b l e s o l v e n t i n t e r c a l a t i o n i s n o t e d . C a t i o n i c i n t e r c a l a n t s p e c i e s such as l 2 + ( s o l v ) a n d N 0 + ( s o l v ) S i v e G I C ' s w i t h s u b s t a n t i a l amounts o f a c i d p r e s e n t i n t h e f i n a l p r o d u c t s e v e n a t h i g h c o n c e n t r a t i o n s , w i t h no NO s p e c i e s and o n l y v e r y l i t t l e i o d i n e i n t e r - c a l a t e d i n t h e r e s p e c t i v e compounds. T h i s l e a d s t o t h e c o n c l u s i o n t h a t f l u o r o s u l f u r i c a c i d and S O 3 F " i n t e r c a l a t e p r e f e r e n t i a l l y i n t o t h e h o s t m a t e r i a l when c a t i o n s s o l v a t e d i n H S O 3 F a r e u s e d as o x i d i z e r s . N e u t r a l i n t e r c a l a n t s such as I ( S 0 3 F > 3 and B r ( S 0 3 F > 3 o r a n i o n i c s o l u t e s l i k e K [ H a l ( S 0 3 F ) 4 ] g i v e r i s e t o t h e f o r m a t i o n o f i o d i n e and b r o m i n e c o n t a i n i n g i n t e r c a l a t i o n compounds. The N 0 + ( s o i v ) p r o m o t e d i n t e r c a l a t i o n r e a c t i o n , where H S O 3 F and S O 3 F " a r e t h e most p o s s i b l e i n t e r c a l a t e s , does n o t o f f e r any d i s t i n c t s y n t h e t i c a d v a n t a g e o v e r t h e g r a p h i t e - S 2 0 g F 2 i n t e r c a l a t i o n r e a c t i o n because o n l y h i g h s t a g e m a t e r i a l s a r e o b t a i n e d , and f u r t h e r m o r e , N O S O 3 F i s i n i t i a l l y p r e p a r e d f r o m S 2 0 g F 2 - - 133 - F i n a l l y , a l t h o u g h i n a d d i t i o n t o m i c r o a n a l y s i s , p h y s i c a l methods s u c h as X - r a y powder d i f f r a c t i o n , Raman s p e c t r o s c o p y , S o l i d s t a t e -• 9F-NMR and U V - v i s i b l e s p e c t r o s c o p i c t e c h n i q u e s were u s e d , t h e i d e n t i f i - c a t i o n and c h a r a c t e r i z a t i o n o f t h e s p e c i e s p r e s e n t I n t h e i n t e r c a l a n t l a y e r s s t i l l r e m a i n , t o a l a r g e e x t e n t , t h e most d i f f i c u l t c h a l l e n g e i n g r a p h i t e i n t e r c a l a t i o n c h e m i s t r y . 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