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Some properties of platinum pentafluoride and some properties of germanium difluoride Akhtar, Masud 1965

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SOME PROPERTIES OF PLATINUM PENTAFLUORIDE AND SOME PROPERTIES OF GERMANIUM DIFLUORIDE by MASUD AKHTAR M.Sc. U n i v e r s i t y o f Peshawar, P a k i s t a n , 1962. A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n the Department of CHEMISTRY accept t h i s t h e s i s as conforming t o the r e q u i r e d standard THE UNIVERSITY OF BRITISH COLUMBIA December, 1965. In p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t o f t h e r e q u i r e m e n t s f o r a n a d v a n c e d d e g r e e a t t h e U n i v e r s i t y o f B r i t i s h C o l u m b i a , I a g r e e t h a t t h e L i b r a r y s h a l l m a k e i t f r e e l y a v a i l a b l e f o r r e f e r e n c e a n d s t u d y . I f u r t h e r a g r e e t h a t p e r -m i s s i o n f o r e x t e n s i v e c o p y i n g o f t h i s t h e s i s f o r s c h o l a r l y p u r p o s e s may be g r a n t e d by t h e H e a d o f my D e p a r t m e n t o r by h i s rep resenta t i ves„ 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 b e 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 T h e U n i v e r s i t y o f B r i t i s h C o l u m b i a V a n c o u v e r 8, C a n a d a D a t e i i ABSTRACT Platinum p e n t a f l u o r i d e has been prepared, by a new p r e p a r a t i v e method, i n a more stable,pure and c r y s t a l l i n e form than the m a t e r i a l already described. I t has been shown, by x-ray powder photography, to be isomorphous with other noble metal p e n t a f l u o r i d e s and almost isodimensional w i t h rhodium p e n t a f l u o r i d e . A t e t r a m e r i c s t r u c t u r a l u n i t l i k e t h a t observed i n ruthenium p e n t a f l u o r i d e i s a l s o assumed f o r platinum p e n t a f l u o r i d e . I t s magnetic p r o p e r t i e s have been shown t o be 5 r e p r e s e n t a t i v e of a t h i r d t r a n s i t i o n s e r i e s d i o n i n a d i s t o r t e d octahedral environment. The nature of the bonding i n germanium d i f l u o r i d e i s discussed i n the l i g h t o f the c r y s t a l s t r u c t u r e , which has been deduced from data obtained from s i n g l e c r y s t a l s prepared i n t h i s work. ; The products of i n t e r a c t i o n o f c h l o r i n e or bromine with the d i f l u o r i d e are c o n s i s t e n t 19 w i t h the s t r u c t u r a l f i n d i n g s . The F n.m.r. s p e c t r a of the mixed c h l o r o f l u o r i d e s (GeFCl 3, G e F 2 C l 2 , GeF CI, GeF ) and bromofluorides, i n d i c a t e t h a t i n t e r m o l e c u l a r exchange between these compounds must be extremely slow, at l e a s t i n the absence of a c a t a l y s t . I t has been shown th a t germanium d i f l u o r i d e i s so strong a reducing agent t h a t i t reduces i o d i n e p e n t a f l u o r i d e to i o d i n e below room temperature. The powerful reducing p r o p e r t i e s of the d i f l u o r i d e were a l s o i l l u s t r a t e d by the r e d u c t i o n of platinum t e t r a f l u o r i d e t o the metal at room temperature. Attempts to reduce tungsten h e x a f l u o r i d e at 300° l e d t o the formation of Ge2WFg. In glass the germanium d i f l u o r i d e reacted w i t h tungsten hexa-f l u o r i d e and the container t o y i e l d WO F. ACKNOWLEDGEMENTS I would l i k e to thank P r o f e s s o r N e i l B a r t l e t t f o r encouragement, guidance and valuable suggestions during t h i s work. I am a l s o g r a t e f u l to Professo r James T r o t t e r f o r the determination of the c r y s t a l s t r u c t u r e of germanium d i f l u o r i d e . F i n a l l y , I would l i k e 19 to thank Mr. P. T. I n g l e f i e l d f o r recording the F n.m.r. s p e c t r a of the mixed h a l i d e s o f germanium. i v CONTENTS SECTION I . SOME PROPERTIES OF P t F 5 Chapter I . I n t r o d u c t i o n Page 2 I I . Experimental and Results 6 ( i ) F l u o r i n e Handling 6 ( i i ) P r e p a r a t i o n 9 ( i i i ) P r o p e r t i e s 11 (i v ) A n a l y s i s 11 (v) Magnetic S u s c e p t i b i l i t y Measurement 13 (v i ) X-ray Powder Data 16 I I I . D i s c u s s i o n 19 SECTION I I SOME PROPERTIES OF GeF^ Chapter I . I n t r o d u c t i o n 25 I I . Experimental and Results 29 ( i ) P r e p a r a t i o n 29 ( i i ) P r e p a r a t i o n of S i n g l e C r y s t a l s and C r y s t a l Data 32 ( i i i ) Reducing P r o p e r t i e s o f Germanium D i f l u o r i d e (a) The GeF 2 + C l 2 and GeF 2 + B r 2 Reactions 34 (b) Reduction of Iodine P e n t a f l u o r i d e 37 (c) The PtF + GeF Reaction i n Anhydrous HF 37 (d) The Reaction between WF, and GeF 2 i n Glass. The Prep a r a t i o n of W02F 38 (e) The Reaction between WF, and Ge metal i n Glass 41 (f) The WF -Ge metal Reaction i n Monel Apparatus 41 V I I I D i s c u s s i o n . ( i ) The C r y s t a l S t r u c t u r e o f Germanium D i f l u o r i d e 43 ( i i ) Chemistry o f GeF2 (a) Reactions w i t h Halogens 49 (b) F l u o r i d e Reduction Reactions 50 REFERENCES 54 APPENDIX I 56 APPENDIX I I 60 v i LIST OF:TABLES Table I . Known P e n t a f l u o r i d e s o f 2nd and 3rd T r a n s i t i o n Metals Page 2 I I . Magnetic S u s c e p t i b i l i t y Data f o r PtF^ 15A I I I . X-ray Powder Data f o r P t F 5 16 19 IV. F n.m.r. Chemical S h i f t Data f o r GeF CI and GeF "Br Compounds 36 V. X-ray Powder Data f o r W02F 40 VI. Comparison of Interatomic Distances and Bond Angles i n GeF 2 and NaSn 2F 5 45 V I I . S t r u c t u r e Data f o r WO-F. 52. v i i LIST OF FIGURES F i g . I . A General Purpose F l u o r i n e Line Page 7 I I . High Pressure Monel Reactor 10 I I I . Apparatus used f o r P y r o h y d r o l y s i s 12 IV. Bonding i n 2nd and 3rd T r a n s i t i o n Metal P e n t a f l u o r i d e s 20A V. P l o t o f y e f £ v s . kT/A f o r d 5 i o n 22 VI. Apparatus f o r GeF^ Pr e p a r a t i o n 30 V I I . Apparatus f o r growing S i n g l e C r y s t a l s of GeF2 33 19 V I I I . F n.m.r. Spectra of GeF./Br. and G e F 2 / C l 2 Reaction Products 35 IX. Apparatus f o r WFg + GeF 2 Reaction 39 X. F l u o r i n e B r i d g i n g i n GeF^ 44 XI. [GeF 4] Group i n GeF 2 46 v i i i LIST OF PLATES P l a t e I . X-ray Powder Photographs of RuF , I r F , RhF;. and P t F 5 Page 19 I I . P r o j e c t i o n o f the S t r u c t u r e o f GeF^ along b ax i s 43 / - 1 -S E C T I O N 1 THE PREPARATION AND SOME PROPERTIES OF PLATINUM PENTAFLUORIDE - 2 -CHAPTER 1 INTRODUCTION B a r t l e t t and Lohmann* were the f i r s t t o prepare platinum p e n t a f l u o r i d e . They obtained m a t e r i a l of e m p i r i c a l formula PtF<. by the f o l l o w i n g methods:-1. By p h o t o l y s i s o f platinum h e x a f l u o r i d e . 2. By f l u o r i n a t i o n o f platinum compounds at temperatures higher than 350°. 3. By f l u o r i n a t i o n o f platinum d i c h l o r i d e contained i n a n i c k e l boat i n a s i l i c a apparatus at 350°. Highest y i e l d s were obtained by the l a s t method. In no case however d i d they prepare a s t a b l e pure sample of the p e n t a f l u o r i d e . At no time d i d they o b t a i n a s u f f i c i e n t l y c r y s t a l l i n e sample f o r X-^ray photography, nor was a large enough sample of high p u r i t y m a t e r i a l ever obtained f o r magnetic s u s c e p t i b i l i t y measurements by the Gouy technique. Thorough s t r u c t u r a l , magnetic and chemical c h a r a c t e r i z a t i o n r e c e n t l y became d e s i r a b l e . Peacock and h i s coworkers r e c e n t l y described the c r y s t a l 2 2 3 s t r u c t u r e s o f the p e n t a f l u o r i d e s o f niobium, tantalum, molybdenum and 4 ruthenium . They gave p r e l i m i n a r y s t r u c t u r a l data on the p e n t a f l u o r i d e s o f 4 technium, rhenium and osmium . T h e i r r e s u l t s have shown t h a t there are three s t r u c t u r a l types c h a r a c t e r i z e d i n Table 1, as monoclinic I , orthorhombic and monoclinic I I . The niobium, tantalum and molybdenum f l u o r i d e s are the f i r s t type. The s t r u c t u r a l u n i t i n t h i s type i s a t e t r a m e r i c u n i t i n which a l l of the metal atoms are i n the same plane and at the corners of a square. F l u o r i n e atoms s i t u a t e d i n the mid-point of each edge of t h i s square l i n k TABLE I . Known P e n t a f l u o r i d e s o f the Second and T h i r d T r a n s i t i o n Metals. Compound Colour m.p.(°C) NbF 5 white 80 m o n o c l i n i c ( I ) a;b;c; (A) 9.62;14.43;5.12 C r y s t a l Class 3 (°) Compound Colour m.p.(°C) 96.1 T a F 5 white 95 monoclinic(I) a;b;c; (A) 9.64;14.45;5.12 C r y s t a l Class MoFg yellow 67 TcF 50 41 RuF 5 green 86.5 dark red 95.5 mo n o c l i n i c ( I ) orthorhombic m o n o c l i n i c ( I I ) m o n o c l i n i c ( I I ) 9.61;14.22;5.16 94.3 5.8;7.6;16.7 12.47;10.01;5.42 ReF 5 yellow 48 99.82 4 0 S F 5 grey green 70 12.38;9.85;5.48 99.2 I r F 5 ? yellow 105 P t F 5 dark red 98.5 B (°) 96.3 orthorhombic m o n o c l i n i c ( I I ) m o n o c l i n i c ( I I ) m o n o c l i n i c ( I I ) 12.5;10.0;5.4 12.37;9.84;5.47 99.8 99 i * Present work. - 4 -the metal atoms by l i n e a r f l u o r i n e b r i d g e s . Each metal atom i s coordinated by a d i s t o r t e d octahedron of f l u o r i n e atoms. Ruthenium p e n t a f l u o r i d e , on the other hand, c h a r a c t e r i z e s the monoclinic I I s t r u c t u r e . The d e t a i l e d 4 s t r u c t u r e described by Holloway, Peacock and Small, again reveals a t e t r a m e r i c s t r u c t u r a l u n i t but i n t h i s case although each metal atom i s again surrounded by a d i s t o r t e d octahedron of f l u o r i n e l i g a n d s , the f l u o r i n e bridges Ru-F-Ru are bent. D e t a i l s of the t h i r d s t r u c t u r e type have not been given and i t i s not even c e r t a i n that the s t r u c t u r a l u n i t i s a tetramer. 2 > Edwards, i n h i s paper on the NbF,. and TaF,. s t r u c t u r e s remarked on the apparent dependence of the s t r u c t u r e on the element r a t h e r than valency s t a t e . The change i n packing from the cubic close packing of f l u o r i n e atoms 4 i n Nb, Ta and MoF^jto the hexagonal cl o s e packing evident i n RuF^ and OsF^ ^ i s s i m i l a r t o the s i t u a t i o n found i n the t r i f l u o r i d e structures."' In Nb, Ta and MoF^ the l i g a n d packing i s again cubic whereas i n RuF^ i t i s hexagonal. I t remained t o determine how general t h i s c o r r e l a t i o n was. Since RuF^ i s s t r u c t u r a l l y r e l a t e d t o RhF^ and PdF^ [Pd^ +(PdF^)~] the p e n t a f l u o r i d e s of rhodium, i r i d i u m , p alladium and platinum appeared l i k e l y , o n t h i s b a s i s , to be s t r u c t u r a l l y akin t o RuF,. and OsF^- With the p r e p a r a t i o n and s t r u c t u r a l 6 7 c h a r a c t e r i z a t i o n i n these l a b o r a t o r i e s of RhF<- and I^F,. as monoclinic I I , the p r o b a b i l i t y of PtF,. being isomorphous with RuF^ appeared more c e r t a i n . S t r u c t u r a l and magnetic inform a t i o n on the p e n t a f l u o r i d e of g platinum was a l s o of value to the e l u c i d a t i o n o f the nature of the X e ( P t F ^ ) x adducts. I t was p o s s i b l e that the platinum r i c h adducts, i . e . those approach-i n g X e f P t F g ^ were mixtures of XePtF^and PtF^. Such adducts u s u a l l y gave weak x-ray powder p a t t e r n s . They were p o s s i b l y patterns of the p e n t a f l u o r i d e . The pure p e n t a f l u o r i d e was i n any event an e s s e n t i a l p r e c u r s o r f o r the - 5 -s y n t h e s i s of XeCPtF^)^ from:-XeF 2 + 2 P t F 5 > X e ( P t F 6 ) 2 The c h a r a c t e r i z a t i o n o f X e ( P t F ^ ) 2 i s necessary to help i n the c h a r a c t e r i z a t i o n of XePtF,. 6 The s u c c e s s f u l p r e p a r a t i o n o f rhodium p e n t a f l u o r i d e ^ and pa l l a d i u m 9 t e t r a f l u o r i d e by the medium temperature f l u o r i n a t i o n of the lower f l u o r i d e s i n monel r e a c t o r s , employing pressures of f l u o r i n e of ten atmospheres or gr e a t e r , encouraged the use of t h i s procedure i n the p r e p a r a t i o n of platinum p e n t a f l u o r i d e . I t was a l s o o f i n t e r e s t t o compare the magnetic p r o p e r t i e s of Pt(V) i n PtF,. w i t h those of the [ P t F ^ ] ~ i o n , s i n c e the magnetic s u s c e p t i b i l i t y of t h i s i o n i n the s a l t NOPtF^ had been determined r e c e n t l y i n these l a b o r a t o r i e s by S. Beaton. - 6 -CHAPTER I I EXPERIMENTAL AND RESULTS ( i ) F l u o r i n e Handling F l u o r i n e i s o x i d a t i v e l y the most r e a c t i v e of a l l the elements. Indeed i t s great chemical r e a c t i v i t y has been the primary reason f o r the r a t h e r l a t e development of the chemistry of the element. The l a s t twenty years have seen marked improvements i n the technology of f l u o r i n e generation and h a n d l i n g and w i t h proper precautions f l u o r i n e can now be used i n the l a b o r a t o r y w i t h s a f e t y and assurance. The h a n d l i n g techniques w i l l be b r i e f l y described. A general purpose f l u o r i n e supply which may be d i r e c t l y connected to any form of apparatus i s shown i n F i g . 1. This system i s assembled l a r g e l y from 30,000 p . s . i . monel metal Autoclave Engineering v a l v e s , crosses, tees and seamless t u b i n g . Such an assembly may be e a s i l y taken down and cleaned and p a r t s can be r e a d i l y replaced as needed. The low pressure p a r t of the system incorporates f l e x i b l e 1/4 i n . copper t u b i n g , and valves on the low pressure p a r t o f the assembly are Hoke A431. An important p a r t o f the system i s the soda lime tower which i s used t o remove f l u o r i n e gas from the vacuum l i n e s , and the r e a c t i o n v e s s e l s to the pumping system. Another tower f i l l e d w i t h sodium f l u o r i d e p e l l e t s served t o remove the t r a c e s of hydrogen f l u o r i d e present i n f l u o r i n e . Vacuum of b e t t e r than 10 ^ mm of Hg i s d e s i r a b l e f o r such a system although i n p r a c t i c e i t i s seldom achieved. The pumping system used i n t h i s work was a Welch DUOSEAL mechanical pump coupled to a metal o i l -d i f f u s i o n pump. The vacuum was checked by a combination of a thermocouple-- 7 -MV, 30,000 p . s . i . monel valve; MX, Monel cross; MT, Monel tee; Gi Monel Bourdon gauge, 400 l b . p . s . i . ; G2, Monel Bourdon gauge, 1000 mm. Hg; C, 30,000 p . s . i . seamless monel tubing 3/8 i n . o.d., 1/8 i n . i . d . , s i l v e r soldered to 3/8 in.o.d. copper tubing; F, 3/8 i n . f l a r e f i t t i n g ; K, 3/8 i n . 30,000 p . s . i . tubing, s i l v e r soldered to \ i n . monel tubing; and H2 Hoke A431 and A432 valves, respectively; B, F l e x i b l e copper bellows; SL, Soda lime tower; BV, 3/8 i n . bore teflon-seated b a l l valve; J, Connection for vacuum pumps; HP, High-pressure f l u o r i n e o u t l e t ; LP, Low-pressure f l u o r i n e outlet via "Swagelok" compression f i t t i n g s ; S, "Swagelok" outlet for apparatus requiring f l u o r i n e d i l u t e d with nitrogen. Figure 1. A General Purpose Fluorine Line. - 8 -i o n i z a t i o n c o n t r o l B710 gauge s u p p l i e d by NRC Equipment Corporation, Newton, Massachusetts, U.S.A. Whitey valves and Hoke A431 valves were used i n the vacuum l i n e s , on the various monel pots used f o r v o l a t i l e f l u o r i d e storage, and on the monel r e a c t o r s using low pressure f l u o r i n e . For high pressures of f l u o r i n e Hoke A431 valves were used, never Whitey v a l v e s . (a) F l u o r i d e p r e p a r a t i o n and hand l i n g i n glass or quartz apparatus. For the pr e p a r a t i o n of f l u o r i n e compounds i n glass or quartz apparatus, s t r i c t l y anhydrous co n d i t i o n s are necessary. Even a t r a c e of moisture i s capable o f i n i t i a t i n g the etching c y c l e : -MF + H 20 — M G H + HF 4HF + S i 0 2 — > 2H 20 + S i F 4 Hence a l l the glass apparatus used was baked under vacuum three or fou r times w i t h a non-luminous flame. Any monel apparatus attached t o the glassware was pumped out f o r long p e r i o d s , care being taken that such apparatus was leak t i g h t . (b) Monel Apparatus. In r o u t i n e preparations monel or n i c k e l containers and rea c t o r s proved t o be i n v a l u a b l e . In t h i s work a p a r t i c u l a r l y important v e s s e l was a wide mouthed monel r e a c t o r . This v e s s e l o f ~~100 ml cap a c i t y was a-4 i n . x 2 i n . diam. c y l i n d e r of 1/8 i n . w a l l thickness, capped at one end, and provided with a 1/4 i n . t h i c k flange at the mouth. The 1/4 i n . t h i c k l i d , which was provided w i t h a 1/4 i n . monel tube o u t l e t f i t t e d w i t h a Hoke A431 valve,was sealed to the v e s s e l by an aluminum gasket which was - 9 -compressed by t i g h t e n i n g the s i x flange b o l t s . A chamber was formed above the l i d by s i l v e r s o l d e r i n g a dome to i t . This chamber was provided w i t h i n l e t and e x i t tubes and served, w i t h the passage of a f a s t stream of c o l d compressed a i r , as an e f f e c t i v e condenser i n c e r t a i n p r e p a r a t i o n s . The arrangement i s i n d i c a t e d i n the diagram of the v e s s e l given i n F i g . I I . In a l l of the work described,pieces of monel apparatus were g e n e r a l l y j o i n e d together w i t h the a i d of Swagelock compression f i t t i n g s and 1/4 i n . monel or n i c k e l tubing. Swagelock s t r a i g h t tee and cross unions were al s o employed. A l l monel apparatus was f l u o r i n a t e d p r i o r to use. ( i i ) P r e p a r a t i o n of Platinum P e n t a f l u o r i d e The compound was prepared by the high pressure f l u o r i n a t i o n o f platinum t e t r a f l u o r i d e i n an aluminum gasketed monel r e a c t o r l i k e t hat described i n F i g . I I . The t e t r a f l u o r i d e was obtained as a side product i n the p r e p a r a t i o n of PtF^ by the method described by Weinstock, Malm and Weaver. Platinum t e t r a f l u o r i d e (3g) was taken i n a 100 ml c a p a c i t y monel can, provided w i t h a monel l i d sealed by an aluminum gasket. The can was loaded i n a dry box and the l i d b o l t e d i n p l a c e . Care was taken p r i o r t o f l u o r i n a t i o n t o be sure that the v e s s e l was leak t i g h t . F l u o r i n e at <"wl30 p . s . i . at room temperature was used and the base of the can was heated at 350 - 400° f o r 48 hours. The l i d was kept cooled by a stream of compressed a i r . The pot was cooled at room temperature and the f l u o r i n e was disposed of by passing i t through the soda lime scrubber. Platinum p e n t a f l u o r i d e was obtained as a dark red s o l i d on the j Figure I I . High Pressure Monel Reactor. - 11 -l i d and the upper regions o f the can. A n a l y s i s was by p y r o h y d r o l y s i s . Found: P t , 66.1; F, 32.1% P t F 5 r e q u i r e s P t , .67.3; F, 32.7%. ( i i i ) General P r o p e r t i e s The compound melted sharply at 98.5°. As observed p r e v i o u s l y by B a r t l e t t and Lohmann^ the compound d i s p r o p o r t i o n a t e d as 2PtF^ — > PtFg + P t F^ on h e a t i n g , but t h i s was only evident above the me l t i n g p o i n t , whereas B a r t l e t t and Lohmann had observed d i s p r o p o r t i o n a t i o n at temperatures as low as 80°. The compound may be sublimed under vacuum, however, i n the temperature range 50 - 70°. Unfortunately i t d i d not prove p o s s i b l e t o obtain s i n g l e c r y s t a l s f o r x-ray s t r u c t u r a l i n v e s t i g a t i o n e i t h e r i n the synth e s i s or by vacuum s u b l i m a t i o n . The p e n t a f l u o r i d e reacted exothermally w i t h water, some of the platinum being p r e c i p i t a t e d as the hydrated platinum d i o x i d e , and the remainder being reduced t o h e x a f l u o r o p l a t i n i c (IV) a c i d which remained i n s o l u t i o n . ( i v ) A n a l y s i s by P y r o h y d r o l y s i s The apparatus used f o r a n a l y s i s of platinum p e n t a f l u o r i d e was the same as used by Lohmann,^ shown i n F i g . I I I . I t c o n s i s t e d o f a s i l i c a tube housed i n an e l e c t r i c a l l y heated furnace, and having a 35/20 B.S. s i l i c a socket at one end, and a pyrex glass steam condenser j o i n e d by a B 10 ground s i l i c a cone at the other end. The c a r r i e r gases passed through a steam generator, having a copper - 13 -steam t r a p , which could be j o i n e d leak t i g h t t o the 35/20 B.S. s i l i c a socket. A small platinum boat was weighed i n a small h o r i z o n t a l weighing b o t t l e a f t e r r e d u c t i o n i n hydrogen at v 300°. A known weight of the sample {'sjQ.lg) was taken i n t o the platinum boat i n a dry box, and the boat q u i c k l y t r a n s f e r r e d i n t o the p y r o h y d r o l y s i s tube. Nitrogen c a r r y i n g some moisture from the steam generator was passed over the sample f o r f i v e minutes, a f t e r that the temperature of water i n the steam generator was r a i s e d t o b o i l i n g , a n d that of the furnace t o 'v,300°C., Thus steam passed over the sample at high temperature. The d i s t i l l a t e was c o l l e c t e d by b u b b l i n g through 50 mis of very d i l u t e sodium hydroxide s o l u t i o n . F l u o r i d e i o n . c o n c e n t r a t i o n 12 was determined i n the d i s t i l l a t e as lead c h l o r o f l u o r i d e . For platinum e s t i m a t i o n , steam trap and steam generator were replaced by a two way s i l i c a tubing connected t o n i t r o g e n and hydrogen c y l i n d e r s . The apparatus was f l u s h e d thoroughly by n i t r o g e n , then hydrogen was passed through a t v 3 0 0 ° , the emergent gas being burnt, u n t i l the platinum residue i n the platinum boat weighed t o a constant weight. The flow of n i t r o g e n and hydrogen passing through the p y r o l y d r o l y s i s tube was c o n t r o l l e d by passing the gases through bubblers c o n t a i n i n g concen-t r a t e d s u l p h u r i c a c i d . (v) Magnetic S u s c e p t i b i l i t y Measurement Magnetic s u s c e p t i b i l i t y measurements were made w i t h a Gouy balance, 13 a d e t a i l e d d e s c r i p t i o n of which has been given by Clark and O'Brian, over the temperature range 77 - 304°K. A f i n e l y powdered sample of the p e n t a f l u o r i d e was packed i n t o an 11.2 cm x 3 mm. pyrex tube, care being taken t o ensure a u n i f o r m i t y o f - 14 -packing by b r i s k l y tapping the sample between successive a d d i t i o n s of the f i n e powder. A l l manipulations were conducted i n the DRI-LAB - HE 43-2 s u p p l i e d by Vacuum Atmospheres Corporation, Los Angeles, C a l i f o r n i a . The tube was sealed by drawing under vacuum. The length of the sample was 6.2 cm and i t s weight 0.8878 g. The loaded tube was suspended from the balance pan on a t h i n brass chain, i n a t h e r m o s t a t i c a l l y c o n t r o l l e d Dewar f l a s k , the temperature of which was c o n t r o l l e d by the current passing through an e l e c t r i c a l l y heated c o i l . Mercury cobalt t e t r a t h i o c y a n a t e , HgCo(CNS) 4 recommended by F i g g i s 14 and Nyholm was used as the paramagnetic standard. The weighings were correcte d f o r the diamagnetic c o n t r i b u t i o n s of the glass sample tube, which were assessed f o r the f u l l temperature range. The molar s u s c e p t i b i l i t y , X^, was obtained from the r e l a t i o n s h i p : -Aw + <$w W -• „„ XM = x e x -> x x M - W K W Aw + 6w where:- x = gram s u s c e p t i b i l i t y of HgCo(CNS) , 16.44 x 10~ 6 c.g.s. g u n i t s at 20°. 1 4 W and W = weights o f HgCo(CNS) 4 and PtF,- r e s p e c t i v e l y . t AW and AW = changes i n the weights of HgCo(CNS) 4 and P t F 5 . 6w and Sw = Diamagnetic c o r r e c t i o n s f o r the glass c o n t a i n e r s , at each temperature, f o r HgCo(CNS) 4 and P t F 5 . M.W" = Molecular weight of PtF,.. The molar s u s c e p t i b i l i t y , x M> was co r r e c t e d f o r the diamagnetic s u s c e p t i b i l i t y of f l u o r i n e l i g a n d s , t o give the gram atomic s u s c e p t i b i l i t y 1 5 y 16 X A as x A = X M + 55. y g f f was c a l c u l a t e d as y f f = 2.83/x A x T , where T i s the temperature i n °K. A l e a s t squares refinement of the data showed a close obedience - 15 -to Curie-Weiss behaviour, w i t h a value o f 28° f o r the Weiss Constant. A program IBFTC APPROX (Appendix i ) w a s run i n the IBM 7040 computer f o r t h i s purpose. The values f o r the molar s u s c e p t i b i l i t i e s and magnetic moment are given i n Table I I . The p u r i t y o f the m a t e r i a l was checked by a n a l y s i s a f t e r the magnetic measurements. A powder photograph of a sample taken before packing the m a t e r i a l i n t o the glass tube f o r magnetic measurements showed only the p a t t e r n c h a r a c t e r i s t i c of a p e n t a f l u o r i d e . The melti n g p o i n t of the m a t e r i a l used f o r the s u s c e p t i b i l i t y measurements was 98.5°. TABLE I I Magnetic S u s c e p t i b i l i t y of Platinum P e n t a f l u o r i d e . X.obs x 10 6 x? r e f i n e d x 10~ 6 x A°bs-x A r e f i n e d x 10~ 6 ' . ^ ^ ^ ^ ^ T e m P - ° K c.g.s. u n i t s , c.g.s. u n i t s . c.g.s. u n i t s . y=2.83^ T T . u=2,83/xA x (T +0) 77.2 5005 4856 148 1.75 2.10 88.4 4532 4391 140 1.79 2.06 92.4 4414 4246 167 1.80 2.10 107.2 •3732 '3783 -51 1.78 2.01 146.0 2866 2943 -77 1.82 2.00 186.7 2358 2386 -28 1.87 2.06 203.2 2206 2216 -10 1.89 2.02 229.1 1937 1994 -57 1.88 1.99 246.2 1840 1870 -30 1.90 2.01 262.7 1750 1764 -14 1.91 2.02 279.2 1675 1669 5 1.93 2.03 286.2 1614 1632 -18 1.92 2.01 294.3 1614 1591 22 1.95 2.04 304.2 1600 1544 55 1.97 2.06 x£ was obtained by l e a s t squares refinement of x A assuming Curie-Weiss behaviour. > t y c a l c u l a t e d from x A obs. - 16 -( v i ) X-ray Powder Data. The samples f o r the x-ray powder photographs were prepared from the f i n e l y powdered m a t e r i a l i n 0.5 mm., diameter quartz c a p i l l a r i e s . The c a p i l l a r i e s were loaded i n the DRT-LAB under s t r i c t l y anhydrous c o n d i t i o n s . Photographs were taken on a 14.32 em. General E l e c t r i c Camera, usi n g n i c k e l -f i l t e r e d CuK^ r a d i a t i o n (A = 1.5418X.). Photographs of d i f f e r e n t i n t e n s i t i e s were taken w i t h d i f f e r e n t exposure times, depending upon the nature of the m a t e r i a l . The photographs were measured by u s i n g an accurate s c a l e and 2 2 v e r n i e r . Bragg angles, i n t e r p l a n a r spacing d, 1/d v a l u e s , S i n 9 values and Nelson-Riley E x t r a p o l a t i o n Function were obtained by usi n g the program IBFTC INDEX (Appendix I I ) i n an IBM 7040 computer. X-ray powder photographs showed PtF^ to be isomorphous and n e a r l y isodimensional w i t h RhF^. The observed r e f l e x i o n s were indexed on a mono-c l i n i c l a t t i c e w i t h the u n i t c e l l parameters a = 12.37A, b = 9.84A, c = 5.47X, P= 99°, V = 657.6A , D c a l c= 5.86 g/c.c. The data i s given i n Table I I I . TABLE I I I C a l c u l a t e d and Observed X-Ray D i f f r a c t i o n Data f o r PtF,-. h k l r i !/d 2 Calc. —-— obs. I 110 0.0170 0.0172 4 001 0.0342 0.0343 4 011,111 0.0465 0.0467 6 201 0.0515 0.0510 8 111 0.0559 0.0567 6 220 0.0680 0.0682 10 310 0.0705 0.0711 6 021 0.0755 0.0756 6 - 17 -TABLE I I I (continued) 1/d 2 h k l C a l c . — — obs. I obs. 301 0.1086 0.1082 6 221 0.1117 0.1128 6 321 0.1215 0.1212 4 031 0.1271 0.1282 1 131 0.1385 0.1383 4 231 0.1444 0.1428 4 420 0.1483 0.1484 2 330 0.1531 0.1531 4 231 0.1633 0.1630 8 022 0.1781 0.1785 8 222 0.1860 0.1851 1 331 0.2015 0.2030 6 520 0.2085 0.2092 6 431 0.2152 0.2138 6 222 0.2238 0.2245 1 511 0.2355 0.2349. 1 T41 0.2454 0.2435 6 050 0.2580 0.2598 6 531 0.2707 0.2704 6 402 0.2818 0.2808 1 412 0,2921 0.2909 1 203 0.3064 0.3070 1 303 0.3256 . 0.3258 2 T23 0.3418 0.3426 2 242 0.3477 0.3487 8 502 0.3515 0.3544 6 - 18 -TABLE I I I (continued) 1/d 2 h k l C a l c . obs. I obs. 203 0.3631 0.3645 8 451 0.3804 0.3859 2 052 0.3949 0.3943 1 640 0.4060 0.4063 1 313,133 0.4218 0.4214 6 810 0.4385 0.4387 6 603 0.4637 0.4610 4 820 0.4695 0.4694 2 - 19 -CHAPTER I I I DISCUSSION The p r e p a r a t i v e technique which had proved valuable i n the 9 6 pr e p a r a t i o n of PdF^ and RhF,. produced platinum p e n t a f l u o r i d e i n gre a t e r p u r i t y than that p r e v i o u s l y described. The new m a t e r i a l melts sh a r p l y at 98.5°, a temperature considerably higher than the p r e v i o u s l y given melting p o i n t of 80°. The p e n t a f l u o r i d e described by B a r t l e t t and Lohmann''' was not obtained i n a s u f f i c i e n t l y c r y s t a l l i n e form f o r x-ray powder or s i n g l e c r y s t a l photography, but that obtained i n t h i s work gave sharp l i n e , low background powder photographs. Unfor t u n a t e l y attempts to grow s i n g l e c r y s t a l s f a i l e d , but as a consequence of the s i m i l a r i t y of the powder 4 7 6 p a t t e r n to those of RuF,. , I r F ^ and RhF^ the isomorphism o f the compound with the r e l a t e d p e n t a f l u o r i d e s was e s t a b l i s h e d , the close s t r u c t u r a l s i m i l a r i t y i s revealed by P l a t e 1. In p a r t i c u l a r the close s i m i l a r i t y o f the photograph of PtF^ with that of RhFj., i n d i c a t e s that the u n i t c e l l s are almost i s o d i m e n s i o n a l . The c r y s t a l l o g r a p h i c and p h y s i c a l p r o p e r t i e s of the known p e n t a f l u o r i d e s of the second and t h i r d t r a n s i t i o n metals are given i n Table 1. The a n t i c i p a t e d isomorphism of platinum p e n t a f l u o r i d e w i t h the p e n t a f l u o r i d e s of ruthenium, osmium, rhodium,and i r i d i u m has been confirmed. I t i s p a r t i c u l a r l y noteworthy that the diagonal r e l a t i o n s h i p observed i n 17 the h e x a f l u o r i d e s i s again seen here. Platinum p e n t a f l u o r i d e i s not only almost isodimensional w i t h rhodium p e n t a f l u o r i d e but i s l i k e i t i n c o l o u r and i n thermal s t a b i l i t y . This p a r a l l e l s the s i m i l a r i t y i n u n i t c e l l s i z e , colour and s t a b i l i t y of the RuF^* * r F 5 Va^-r- These r e l a t i o n s h i p s may be a t t r i b u t e d t o the s i m i l a r i t y i n p o l a r i z i n g power of the metal atoms i n the X - R A Y P O W D E R P H O T O G R A P H S - 20 -p a i r s P t ( V ) , Rh(V) and I r ( V ) , Ru(V). Presumably the screening e f f e c t i v e n e s s of the non-bonding e l e c t r o n s i n the second t r a n s i t i o n s e r i e s i s not as great 17 as i n the t h i r d . Although i t i s by no means c e r t a i n that the d i f f e r e n c e between the monoclinic I s t r u c t u r e and the monoelinic I I s t r u c t u r e ^ i s t h a t i n the former the M-F-M bridges are l i n e a r , whereas i n the l a t t e r they.- are bent, i t i s h i g h l y probable that t h i s i s so. I t i s c e r t a i n l y e s t a b l i s h e d t h a t i n 2 3 a l l of the monoclinic I cases the bonds are l i n e a r . ' I t of course remains to be demonstrated t h a t the M-F-M bonds i n OsF,., RhF,., IrF^.and PtF^ are n o n - l i n e a r but i t i s i n s t r u c t i v e at t h i s p o i n t t o enquire i f t h i s i s a reasonable t h e o r e t i c a l e x p e c t a t i o n . Although WFj. i s as yet unknown, the p a t t e r n of known s t r u c t u r e s would i n d i c a t e a monoclinic I type here. Although TcF,. and ReF^ are known 18 t o be isomorphous, there are u n f o r t u n a t e l y no s t r u c t u r a l d e t a i l s a v a i l a b l e . The s t r u c t u r a l change i n passing from group VI to group VII and the f u r t h e r but f i n a l change i n passing from group VII t o group VIII A must be s i g n i f i c a n t and i s presumably as s o c i a t e d w i t h the non-bonding d e l e c t r o n c o n f i g u r a t i o n . I t i s probable that a l i n e a r symmetrical M-F-M b r i d g e can only occur where Tf bonding as w e l l as ff* bonding i s operative between M and F. A l i n e a r bridge w i l l r e s u l t i f the b r i d g i n g F l i g a n d forms V bonds w i t h the atom M. A p o s s i b l e scheme i s represented i n the f o l l o w i n g F i g . IV. - 20A -Figure: I Bonding in 2nd and 3rd Trantition Metal Pentafluorides. - 21 -Presumably such a bonding arrangement would be most probable with appropriate vacant d o r b i t a l s on the atom M. Each b r i d g i n g F atom would make as 5 bond and a V bond t o each b r i d g e d metal atom M. Now i n the m onoclinic I s t r u c t u r e each metal atom M i s j o i n e d c i s to two b r i d g i n g F l i g a n d s . Thus each atom M re q u i r e s two vacant d o r b i t a l s f o r the type o,f bonding under c o n s i d e r a t i o n . Since i n the t e t r a m e r i c arrangements each atom M i s s i x coordinated i n f l u o r i n e , approximately o c t a h e d r a l l y , i t i s a f a i r approximation to use the d o r b i t a l model usual f o r 0^ . symmetry. The two r e q u i r e d vacant o r b i t a l s would approximate t o t2g o r b i t a l s . In NbF,., TaF,. (^t2g^ MoF,. ( d ^ g l ) t w o t 2 g type o r b i t a l s are a v a i l a b l e and l i n e a r M-F-M bridges t h e r e f o r e seem appropriate. On the other hand w i t h RuF^, OsF 5 C d t 2g 3-' 5 ^ ^ 5 ' I r F 5 ( dt2g' +^ a n d P t F 5 ^t 2 g 5 - * n o v a c a n t d o r b i t a l s are a v a i l a b l e to f a c i l l i t a t e T T bonding. In these cases if"1 bonding alone must s u f f i c e . The bridge system i s no longer l i n e a r presumably because of the 2 3 19 more e f f e c t i v e bonding, = consequent on sp or sp h y b r i d i z a t i o n o f the f l u o r i n e o r b i t a l s . This would account f o r the bent bridge observed i n RuF^ 4. This simple theory c e r t a i n l y groups the p e n t a f l u o r i d e s a p p r o p r i a t e l y . I t allows that TcF,. and ReF,. i n which the metal atom possess a 2 c o n f i g -u r a t i o n w i t h only one vacant d o r b i t a l could not form a wholly l i n e a r f l u o r i n e b ridged tetramer. I f a tetramer s t r u c t u r e p e r t a i n s i n these f l u o r i d e s the theory would permit two l i n e a r M-F-M bridges and two bent. A s t r u c t u r a l d i f f e r e n c e between the group seven p e n t a f l u o r i d e s and the other p e n t a f l u o r i d e types c e r t a i n l y seems appropriate. The s t r u c t u r e s of TcF,. and ReF^ are awaited w i t h great i n t e r e s t . The moment of [PtF^] i o n v a r i e s from 1.5 to 1.74 B.M. i n the temperature range of 77-304°K w h i l e that of P t F 5 v a r i e s from 1.7 t o 1.97 B.M. i n the same temperature range. The value of the magnetic moment y, of PtF^ i s at £.11 temperatures) higher than t h a t observed f o r the [PtF ] ~ i o n at the 6 - 22 -same temperature. The s u s c e p t i b i l i t y obeys the Curie Weiss law f o r both species and i n n e i t h e r case i s there a s i g n i f i c a n t d e v i a t i o n from t h i s be-haviour above 77°K. The data f o r the [PtF^] i s very close t o that a n t i c i -pated by theory. In an octahedral environment the ^ t2g5 c o n f i g u r a t : > - o n has been 20 shown by Kotani to give moments approaching the s p i n only value of 1.73 B.M. wi t h high s p i n o r b i t coupling,as shown i n the accompanying Fig.V, where A = s.o. coupling constant, and k = Boltzmann constant. 3 0 02 O-fH OOe 0 0 8 o - i 5 . Figure V. P l o t of y _- vs. k'T/A f o r d i o n . b e f f Spin o r b i t coupling f o r Pt(V) i s undoubtedly very high and A. has -1 2 1 been estimated to be ~ 10,000 cm f o r the Free Ion S i n g l e - E l e c t r o n -value. Consequently the magnetic moment of Pt(V) i n an octahedral environment i s a n t i c i p a t e d to be 1.73 B.M. and almost temperature independent. This i s the s i t u a t i o n which p e r t a i n s i n the [PtF^] i o n and here the temperature independent moment i s , approximately 1.74 B.M. a value i n clo s e agreement with theory. The higher value o f the moment of PtF^ i s not e a s i l y accounted f o r . The departure of the environmental symmetry from 0^ . may be re s p o n s i b l e f o r the higher moment but i t i s more l i k e l y t o be due to a cooperative e f f e c t . The b r i d g i n g of the platinum atoms by f l u o r i n e atoms may produce a cou p l i n g of s p i n s , i n a ferromagnetic sense, i n adjacent metal atoms, t o y i e l d a somewhat enhanced moment. In the absence o f a d e t a i l e d s t r u c t u r e f u r t h e r conjecture i s not worthwhile. I t i s noteworthy however that cases of other t h i r d t r a n s i t i o n s e r i e s fd c cases), where again the s p i n o r b i t coupling t2g;> - 23 -should be h i g h , h i g h e r moments than a n t i c i p a t e d have been observed. Thus I r C l ^ possesses a room temperature moment of 1.98 B.M. whereas M 2 ( T ) I r C l ^ 22 s a l t s i n v a r i a b l y show moments s l i g h t l y l e s s than 1.73 B.M. The new f i n d i n g s on'PtF^. have shown that the c r y s t a l l i n e m a t e r i a l does not occur i n any of the X e ( P t F ) x adducts (where x l i e s between 1 and 2 ) . The s u s c e p t i b i l i t y data should be of value i n the i n t e r p r e t a t i o n o f any magnetic data which becomes a v a i l a b l e f o r XePtF^ "and XeCPtFg)^. I f the moments based on platinum f o r these products more c l o s e l y resemble [ P t F ^ ] ~ than PtF,- then some support w i l l be given t o the i o n i c formulations X e + [ P t F 6 ] " and X e 2 + [ P t F 6 ] ~ . - 24 -SECTION I I SOME PROPERTIES OF GERMANIUM DIFLUORIDE - 25 -CHAPTER I INTRODUCTION 23 Winkler was the f i r s t t o c l a i m the existence of a d i f l u o r i d e o f germanium. By hea t i n g potassium fluorogermanate i n a stream o f hydrogen he obtained a dark coloured mass which he claimed t o be the d i f l u o r i d e , an aqueous e x t r a c t of which gave germanous sulphide w i t h hydrogen s u l p h i d e . 24 I t i s probable that Dennis and Laubengayer were the f i r s t to ob t a i n the compound however. They described the d i f l u o r i d e as a white sublimable s o l i d formed i n the red u c t i o n o f germanium t e t r a f l u o r i d e by germanium metal: GeF^ + Ge —> 2GeF2- T h e i r germanium t e t r a f l u o r i d e was obtained by p y r o l y s i s o f barium hexafluogermanate BaGeF^ —> BaF^ + GeV^ and i t was perhaps because of the r a t h e r impure nature of t h i s t e t r a f l u o r i d e that they d i d not report a n a l y s i s to support t h e i r claim. Presumably the impure nature of t h e i r GeF^ prevented the p r e p a r a t i o n of a large enough sample of GeF2 f o r proper c h a r a c t e r i z a t i o n . They were able to show th a t the m a t e r i a l possessed strong reducing p r o p e r t i e s . Although t h i s f i r s t meagre report appeared i n 1927 and a more lengthy d e s c r i p t i o n was promised, t h i s had not appeared by I960 and the report of germanium d i f l u o r i d e was g e n e r a l l y discounted. The existence o f the d i f l u o r i d e of germanium was e s t a b l i s h e d 25 26 independently i n 1961 by M u e t t e r t i e s and C a s t l e and by B a r t l e t t and Yu. 24 The l a t t e r workers used the method of Dennis and Laubengayer with however the important m o d i f i c a t i o n that the t e t r a f l u o r i d e used was pure m a t e r i a l obtained by f l u o r i n a t i o n of germanium metal. M u e t t e r t i e s and C a s t l e obtained the f l u o r i d e by h y d r o f l u o r i n a t i o n of germanium metal: 2HF + Ge-—> ^e^2 + ^2' The nature o f the m a t e r i a l was c l e a r l y independent of the p r e p a r a t i v e method. Mu e t t e r t i e s and Ca s t l e gave a melt i n g p o i n t of 111-112° which c l o s e l y agreed - 26 -wi t h the value of 110° given by B a r t l e t t and Yu. The other p h y s i c a l and. chemical f i n d i n g s s e p a r a t e l y reported were i n agreement. B a r t l e t t and Yu were able to give some s t r u c t u r a l i n f o r m a t i o n on the d i f l u o r i d e . They reported the u n i t c e l l t o be p r i m i t i v e orthorhombic and to contain four molecules. On the b a s i s of the low den s i t y and the s i m i l a r i t y w i t h two •27 of the c e l l dimensions of Se02 B a r t l e t t and Yu concluded t h a t the compound probably possessed an open (poorly packed) SeO^ type s t r u c t u r e . They pointed out that the d i f l u o r i d e s t r u c t u r e was q u i t e u n l i k e the two forms of GeO^ ( r u t i l e and low q u a r t z ) . They conjectured t h a t the germanium atoms were . probably three coordinated i n f l u o r i n e , the s t e r i c a l l y a c t i v e nonbonding p a i r assuming a f o u r t h c o o r d i n a t i o n p o s i t i o n . I t has most often been supposed i n c o n s i d e r i n g the bonding i n 28 29 compounds l i k e J t i n d i c h l o r i d e ' (a chemical r e l a t i v e of GeF2) that the unsymmetrical l i g a n d environment about the c e n t r a l atom was d i s t o r t e d by the s t e r i c a c t i v i t y of the nonbonding e l e c t r o n p a i r on th a t atom. The s o l i d t i n d i c h l o r i d e x-ray s t r u c t u r e e l u c i d a t i o n has shown t h a t each t i n atom has three c l o s e (bonded) c h l o r i n e l i g a n d s , a l l Cl-Sn-Cl bond angles being c l o s e to 90°, the s t r u c t u r a l u n i t being a t r i g o n a l pyramid w i t h the t i n at the apex. D e s c r i p t i o n s of the bonding i n t h i s case have u s u a l l y maintained s t e r i c a c t i v i t y of the nonbonding e l e c t r o n p a i r and have " v i s u a l i z e d " the p a i r as being on the si d e o f the t i n atom f a r t h e s t from the ligands ( i . e . at the top of the t r i g o n a l SnCl^ pyramid). This has X X V i m p l i e d that the " p a i r " i s housed i n an sp or sp d^ h y b r i d o r b i t a l . 30 Rundle however has taken a contrary view and has maintained t h a t an adequate d e s c r i p t i o n o f the t i n c h l o r i d e s t r u c t u r e and many r e l a t e d non-bonding e l e c t r o n p a i r c o n t a i n i n g s t r u c t u r e s , can be given i n terms of the involvement of p o r b i t a l s of the c e n t r a l atom alone i n bonding, the non-- 27 -bonding p a i r being accommodated i n an s o r b i t a l . In Rundle's d e s c r i p t i o n of the s t r u c t u r e of S n C l 2 the pyramidal SnCl^ u n i t w i t h its~»90° Cl-Sn-Cl angles i s a consequence o f the use of only the three orthogonal p o r b i t a l s of the t i n i n bonding, the nonbonding p a i r being l o c a t e d i n the s valence o r b i t a l . I t was hoped that a complete c r y s t a l s t r u c t u r e determination of germanium d i f l u o r i d e would prove o f value in d i s c u s s i n g which of these t h e o r i e s of bonding was more appropriate i n the d e s c r i p t i o n o f f l u o r i d e s of the n o n t r a n s i t i o n elements where a nonbonding e l e c t r o n p a i r i s present. 2 6 B a r t l e t t and Yu a l s o i n v e s t i g a t e d some of the reducing p r o p e r t i e s of germanium d i f l u o r i d e . They s t u d i e d i t s r e a c t i o n s w i t h selenium t e t r a -f l u o r i d e , sulphur t r i o x i d e and w i t h c h l o r i n e and i o d i n e . A l l of the re a c t i o n s s t u d i e d showed the d i f l u o r i d e to be a powerful reducing agent, e.g. selenium t e t r a f l u o r i d e being reduced at ord i n a r y temperatures to selenium. They suggested that germanium d i f l u o r i d e might be a u s e f u l reducing agent f o r the pr e p a r a t i o n of lower f l u o r i d e s of the t r a n s i t i o n metals. Indeed the s y n t h e t i c value of germanium d i f l u o r i d e as an agent i n the p r e p a r a t i o n of lower f l u o r i d e s remained l a r g e l y unexplored p r i o r to t h i s work. Germanium d i f l u o r i d e i s of course p a r t i c u l a r l y a t t r a c t i v e as a reducing agent s i n c e the t e t r a f l u o r i d e which i s formed i n the o x i d a t i o n - r e d u c t i o n r e a c t i o n i s a gas at o r d i n a r y temperatures and pressures, and so i s r e a d i l y removed from the r e a c t i o n s i t e . Although B a r t l e t t and Yu reported t h a t germanium d i f l u o r i d e reacted w i t h c h l o r i n e t o give a mixture o f a l l of the c h l o r o f l u o r i d e s i t was not c l e a r from t h i s p r e l i m i n a r y work that t h i s mixture was a consequence o f reaarange-ments of the type: - 28 -2 G e F 2 C l 2 —>• GeF CI + G e F C l 3 2GeF 3Cl — > GeF 4 + G e F 2 C l 2 e t c . 4GeFCl 3 —*• GeF 4 + 3GeCl 4 31 as ass e r t e d by Booth and M o r r i s , or whether the various c h l o r o f l u o r i d e s 19 were primary products of the r e a c t i o n . A c c o r d i n g l y a F n.m.r. study of the products of the r e a c t i o n was undertaken with a view.to e s t a b l i s h i n g 31 the exchange r e a c t i o n claimed by Booth and M o r r i s . - 29 -CHAPTER I I EXPERIMENTAL AND RESULTS ( i ) P r e p a r a t i o n o f Germanium D i f l u o r i d e Germanium d i f l u o r i d e was prepared by the methods, described 26 25 by B a r t l e t t and Yu, and Meuetherties and C a s t l e , w i t h only s l i g h t m o d i f i c a t i o n s o f t h e i r apparatus. The p u r i t y o f the samples was checked by x-ray powder photography and by me l t i n g p o i n t determination, (a) Reduction of Germanium T e t r a f l u o r i d e by Germanium. Germanium t e t r a f l u o r i d e was prepared by the f l u o r i n a t i o n of germanium metal i n a leak t i g h t 100 ml. c a p a c i t y monel can. S t o i c h i o m e t r i c q u a n t i t i e s of high p u r i t y germanium metal (from Johnson Matthey and Co. London) and f l u o r i n e were taken and a f t e r the i n i t i a l r e a c t i o n at -76° the mixture was heated t o ^  200° f o r four hours. Excess f l o u r i n e was pumped out of the can at -196°. The pressure o f germanium t e t r a f l u o r i d e i n the can was checked at room temperature. The t e t r a f l u o r i d e was reduced by germanium i n the apparatus represented i n F i g . VI • The apparatus was d r i e d i n the usual way, then, w i t h the GeF^ pot h e l d at -76° i n D r i k o l d -a l c o h o l mixture, the gas was passed s l o w l y over the hot germanium, which was kept at ^ 2 00° by a p p l i c a t i o n of a small flame. The r a t e o f flow o f GeF^ over the hot germanium was c o n t r o l l e d by means o f a Hoke A431 v a l v e . White s o l i d GeF^ c o l l e c t e d on the co o l e r p a r t s of'the g l a s s , beyond the hot zone. Unreacted GeF^ c o l l e c t e d i n the traps at -196°, beyond the r e a c t i o n zone. When a l l o f the GeF^ from the monel can had been passed, the valve connecting the apparatus to the vacuum pump was closed and the monel can was immersed i n a l i q u i d N^ bath and the unreacted GeF^ was sublimed back i n t o i t . GeF 4 + Ge Figure VI. Apparatus f o r GeF Preparation. This procedure was repeated three to four times, a f t e r which the germanium metal became much l e s s a c t i v e and the r e a c t i o n became so i n e f f i c i e n t that i t was terminated. The d i f l u o r i d e was c o l l e c t e d by-melt i n g and pouring, i n the presence of GeF^, i n t o s m all tubes each provided w i t h a b r e a k - s e a l connection. The samples were kept at room temperature, (b) H y d r o f l u o r i n a t i o n of Germanium. Ge + 2HF — • GeF 2 + H 2 25 M u e t t e r t i e s and C a s t l e prepared germanium d i f l u o r i d e by t a k i n g s t o i c h i o m e t r i c q u a n t i t i e s of germanium metal and hydrogen f l u o r i d e i n a H a s t e l l o y - C - l i n e d pressure v e s s e l , the mixture being heated at 225°. They p u r i f i e d t h e i r product by vacuum su b l i m a t i o n at 110-130°. the T h e i r procedure was f o l l o w e d , / r e a c t o r as described i n the prepara-t i o n of PtFj. being s u b s t i t u t e d f o r the H a s t e l l o y v e s s e l . High p u r i t y grade germanium metal (5.69g.) (from Johnson Matthey and Co. London) and anhydrous hydrogen f l u o r i d e (3.16g.) s u p p l i e d by Matheson Co. Canada, were used. The bottom of the r e a c t o r was heated t o ^ 225° w h i l e i t s top was kept cool by passing a stream of compressed a i r . A f t e r twenty-four hours the v o l a t i l e s , hydrogen, excess hydrogen f l u o r i d e and a small amount of germanium t e t r a -f l u o r i d e were pumped o f f . To ensure complete removal of v o l a t i l e m a t e r i a l , the r e a c t o r was pumped out f o r an hour. When the v e s s e l was opened i n the DRI-LAB the product was found as a white c r y s t a l l i n e deposit on the cooled top of the r e a c t o r . This m a t e r i a l (m.p. 65°) gave a complex x-ray powder p a t t e r n , which was considerably more complex than that o f germanium d i f l u o r i d e . The m a t e r i a l thus obtained was sublimed under vacuum i n the same r e a c t o r , w i t h the base at 110-140° and the top cooled w i t h a stream of c o l d a i r . The sublimate obtained i n t h i s way melted at 90° and gave an x-ray powder p a t t e r n i d e n t i c a l w i t h t h a t c h a r a c t e r i s t i c of d i f l u o r i d e obtained by - 32 -the t e t r a f l u o r i d e r e d u c t i o n . Since a q u a n t i t y o f ye l l o w s o l i d remained at the bottom of the r e a c t o r a f t e r the vacuum s u b l i m a t i o n i t i s probable that some d i s p r o p o r t i o n a t i o n occurred: GeF 9 -—»- GeF. + GeF . ( i i ) The Pre p a r a t i o n of S i n g l e C r y s t a l s of Germanium D i f l u o r i d e Germanium d i f l u o r i d e prepared by r e d u c t i o n of the t e t r a f l u o r i d e described above,was poured, a f t e r m e l t i n g , i n t o the s m a l l bulb o f the c r y s t a l growing device shown i n F i g . V I I . This was a 7 mm. diameter Pyrex glass tube provided w i t h s e v e r a l branches bea r i n g 0.5 mm. diameter quartz c a p i l l a r i e s . The c a p i l l a r i e s were mounted by graded s e a l s at the t i p s o f B-7 d r i p cones and the f r a g i l e c a p i l l a r i e s were p r o t e c t e d from damage by Pyrex caps with B-7 sockets. The apparatus was provided at i t s open end with a Whitey v a l v e . The apparatus was set up v e r t i c a l l y and pumped out v i a the Whitey v a l v e . Meanwhile the GeF2 was heated under good vacuum by immersion of the bulb i n an o i l bath, the temperature of which was r a i s e d s l o w l y . The f i n a l temperature o f the o i l bath was maintained at 110-120° while pumping the glass bulb continuously. At t h i s temperature GeF2 melted and some of i t c o l l e c t e d on the c o o l e r p a r t s of the apparatus and s i n g l e c r y s t a l s of GeF 2 appeared i n the c a p i l l a r i e s . Meanwhile a large p r o p o r t i o n o f GeF 2 decomposed t o a yellow s o l i d i n the bulb. The s i n g l e c r y s t a l c o n t a i n i n g c a p i l l a r i e s were sealed w i t h a small hot flame. C r y s t a l Data. The s i n g l e c r y s t a l s of germanium d i f l u o r i d e were examined by the x-ray s i n g l e c r y s t a l techniques by P r o f e s s o r J . T r o t t e r . His f i n d i n g s - 34 -confirmed that the s i n g l e c r y s t a l s were r e p r e s e n t a t i v e samples of germanium d i f l u o r i d e s i n c e the u n i t c e l l dimensions which he found were 26 the same as those given by B a r t l e t t and Yu from t h e i r powder data. The powder photographs o f samples made i n the course of t h i s work were always the same as that o r i g i n a l l y indexed by B a r t l e t t and Yu. P r o f e s s o r T r o t t e r ' s s i n g l e c r y s t a l data were:-Cu-K_a = 1.54051 A; A, Cu-Ka 2 = 1.54433 A). — Germanium d i f l u o r i d e , GeF 2, M = 110.6, Orthorhombic, a = 4.682 ^ 0 . 0 0 1 , b = 5.178 +_ 0.001, £ = 8.312 +^0.001 A, U = 201.51 A 3 D^ (displacement of carbon t e t r a c h l o r i d e ) = 3.7, Z_ = 4, D" = 3.644 g. cm. - 3, F (000) = 200. Absorption c o e f f i c i e n t s f o r x-rays, y(Cu-Ka) = 201 cm."*, y(Md-Ka) = 157 cm. - 1. Absent s p e c t r a : hOO when h i s odd, OkO when k_ i s odd, 00£_ when I i s odd; space group i s ?-2l2l2l ( i i i ) Reducing P r o p e r t i e s of Germanium D i f l u o r i d e (a) The GeF 2 + C l 2 and GeF 2 + B r 2 Reactions. Gaseous c h l o r i n e d i d not react w i t h germanium d i f l u o r i d e even when the d i f l u o r i d e was melted. Excess of c h l o r i n e ( 2 ml. of l i q u i d ) was condensed on to germanium d i f l u o r i d e ( 0.8g.) contained i n a 3 mm. diameter glass tube which was drawn o f f from the r e s t of the apparatus. I t was allowed t o warm s l o w l y to room temperature. L i q u i d c h l o r i n e under pressure acted as solvent and d i s s o l v e d the germanium d i f l u o r i d e t o form a y e l l o w s o l u t i o n . 19 A F n.m.r. spectrum of t h i s sample was recorded. Bromine, d r i e d by phosphorous pentoxide, was condensed on german-ium d i f l u o r i d e i n a 3 mm. glass tube, an excess of germanium d i f l u o r i d e being employed. The sealed tube was brought t o room temperature, when a c l e a r GeF 2Br 2 GeFjBr GeFBr, 1182 cps 1701.8 cps 2170 cps GeF, GeF 2 c i 2 GeFCl. 1062 cps & 1336.1 cps GeF 3Cl 1565 cps GeF, 19 Figure V I I I . F n.m.r. Spectra of GeF„/Br„ and GeF./Cl, Reaction Products, i L L L 2. - 36 -c o l o u r l e s s l i q u i d was produced which remained i n .contact w i t h a s l i g h t 19 excess o f the d i f l u o r i d e . A F n.m.r. spectrum was recorded. The spectrum i s shown i n F i g . V I I I . 19 F n.m.r. R e s u l t s . GeF2/Cl2 and GeF2/Br2 r e a c t i o n samples each gave r i s e to a 19 fou r sharp peak F n.m.r. spectrum at 21°. The four peak spectrum had i n d i c a t e d f o u r separate f l u o r i n e c o n t a i n i n g s p e c i e s , assumed t o be GeF^, GeF^X, GeF2X2 and GeFX^. The i n f r a r e d s p e c t r o s c o p i c s t u d i e s of B a r t l e t t 26 33 and Yu and B a r t l e t t and Mak had p r e v i o u s l y e s t a b l i s h e d the production of GeF 4, GeF^X, GeF 2X 2, GeFX 3 and GeX 4 i n the GeF 2/X 2 r e a c t i o n s . The chemical s h i f t s and assignments given i n Table:IV were made on the assump-34 t i o n t h a t , as i n the case of the carbon analogues, the t e t r a f l u o r i d e 19 would e x h i b i t F resonance to highest f i e l d . Table IV 19 F n.m.r. Chemical S h i f t Data f o r GeF. " C l and GeF. "Br Compounds, 4-x x 4-x x r Compound GeF, GeF 3Cl G e F 2 C l 2 GeFCU Chemical S h i f t * (ppm.) 0 -27.8 -51.5 -70.0 Compound GeF, GeF^Br GeF 2Br 2 GeFBr„ Chemical S h i f t * (ppm.) 0 -38.6 -68.8 -89.8 34 Based on the assumption of s i m i l a r i t y t o the carbon analogue sequence 19 Since the GeF 2X 2 and GeF^X F n.m.r. peaks are of comparable i n t e n s i t y i t i s l i k e l y t hat the GeF2X2 concentration i s grea t e r than that of GeF^X. Furthermore the low i n t e n s i t y of the GeF^ resonance absorption i s i n d i c a t i v e of low concentration o f t h i s s p e c i e s . - 37 -(b) Reduction of Iodine P e n t a f l u o r i d e . Iodine p e n t a f l u o r i d e , s u p p l i e d by the Matheson Co. N.J., was t r a n s f e r r e d to a monel can, and p u r i f i e d by t r e a t i n g w i t h a small amount of f l u o r i n e , the mixture being allowed t o warm to room temperature. Remaining f l u o r i n e was pumped from the above mixture at l i q u i d N 2 tempera-t u r e , and the p e n t a f l u o r i d e was vacuum d i s t i l l e d before use. An i n f r a r e d spectrum of the m a t e r i a l showed I F ^ and I OF,, t o be absent. Germanium d i f l u o r i d e ( l g . ) was taken i n a leak t i g h t Kel-F t r a p and an excess of pure i o d i n e p e n t a f l u o r i d e was condensed on to i t at l i q u i d temperature. The p e n t a f l u o r i d e was allowed t o melt s l o w l y on to the germanium d i f l u o r i d e and the Kel-F t r a p was kept immersed i n an i c e c o l d water bath. On contact, i o d i n e was immediately evolved i n an exothermic r e a c t i o n , the bottom of the Kel-F t r a p becoming hot. The germanium d i f l u o r i d e was e n t i r e l y consumed by the r e a c t i o n and vacuum d i s t i l l a t i o n o f the products at room temperature d i d not y i e l d an i n v o l a -t i l e r e s i d u e . The v o l a t i l e products were examined by i n f r a r e d s p e c t r o s -copy, which i n d i c a t e d only i o d i n e p e n t a f l u o r i d e and germanium t e t r a f l u o r i d e . E v i d e n t l y the o v e r a l l r e a c t i o n was: 5GeF 2 + 2 I F 5 — • 5GeF 4 + I (c) The P t F 4 + GeF 2 Reaction i n Anhydrous HF. Platinum t e t r a f l u o r i d e (0.306g.), obtained as described under PtF,-, and germanium d i f l u o r i d e £0.123g.) appropriate f o r s t o i c h i o m e t r i c r e a c t i o n : GeF 2 + P t F 4 —> GeT^ + P t F 2 > were weighed out s e p a r a t e l y , i n the DRI-LAB, i n t o a monel r e a c t o r . The r e a c t o r was s i m i l a r t o that already described under the PtF,- p r e p a r a t i o n . Anhydrous hydrogen f l u o r i d e (4-5 ml.) was condensed under vacuum i n t o the r e a c t o r from a Kel-F container (The Kel-F - 38 -tube container served as a simple measuring device f o r the anhydrous HF, sinc e the amount of HF t r a n s f e r r e d could be gauged v i s u a l l y w i t h f a i r accuracy, the tube being p r e v i o u s l y c a l i b r a t e d ) . The closed r e a c t o r was brought t o room temperature and a f t e r twenty minutes the v o l a t i l e s were removed under vacuum. The r e a c t o r was opened i n the DRI-LAB and the black s o l i d residue i t contained was examined by x-ray powder photography. The s o l i d showed no n o t i c e a b l e r e a c t i o n w i t h water but proved to be hygroscopic. The x-ray powder photographs revealed a sharp l i n e p a t t e r n c h a r a c t e r i s t i c of the P t F ^ and a broad l i n e p a t t e r n ( c h a r a c t e r i s t i c of very small p a r t i c l e s i z e ) o f platinum metal. (d) The Reaction between WF^ and GeF^ i n Glass: The P r e p a r a t i o n of W02F. A small breakseal tube c o n t a i n i n g germanium d i f l u o r i d e was j o i n e d t o a Pyrex apparatus as shown i n F i g . IX. The glassware was c a r e f u l l y vacuum d r i e d , i n the usual manner, a f t e r which the bre a k s e a l was opened and tungsten h e x a f l u o r i d e was t r a n s f e r r e d under vacuum t o the germanium d i f l u o r i d e c o n t a i n i n g tube. The whole apparatus was then closed under vacuum. The glass trap and the c o l l e c t i n g tube were immersed i n i c e c o l d water baths. The tube c o n t a i n i n g germanium d i f l u o r i d e and tungsten hexa-f l u o r i d e was allowed t o warm to room temperature. The tungsten h e x a f l u o r i d e melted on t o the germanium d i f l u o r i d e , but d i d not d i s s o l v e i t or react .with i t . The mixture was heated g r a d u a l l y and i t was not u n t i l a tempera-ture of 240° was reached (using an o i l bath) that an i n t e r a c t i o n was observed. A deep blue s o l i d appeared on the hot glass adjacent t o the germanium d i f l u o r i d e . When the d i f l u o r i d e was e n t i r e l y consumed, the tube c o n t a i n i n g the blue s o l i d was drawn o f f under vacuum. X-ray powder photographs of t h i s s o l i d i n d i c a t e d that the u n i t c e l l was simple cubic To Vacuum Pump if To WF, o Cylinder GeF V 3 N i c k e l Shots. Figure IX. Apparatus f o r WF, + GeF_ Reaction, o 2. - 40 -wi t h a = 3.838 X. The c r y s t a l l o g r a p h i c data i s given i n Table V. A n a l y s i s by p y r o h y d r o l y s i s i n d i c a t e d a composition c l o s e to WO^F. Found: F, 9,1; W, 75.95%. W02F re q u i r e s F, 8,1; W, 78.28%. Unfortunately samples large enough f o r accurate magnetic s u s c e p t i b i l i t y measurements were not obtained. Line i n t e n s i t i e s of the x-ray powder photographs were measured w i t h a H i l g e r § Watts re c o r d i n g micro photometer L.486 provided w i t h a FA17 power supply. TABLE V X-Ray Powder Data f o r WO„F. a = 3.838 X, h k l V = 56.53 X 3 , Z = 2 l / d z Obs. 1, D = c a l c C a l c 6.89 g/c.c. I obs 100 0.0689 0.0679 120 110 0.1388 0.1359 163 111 0,2000 0.2039 66 200 0,2735 0,2718 154 210 0.3416 0.3397 390 211 0.4559 0.4077 188 220 0,5471 0.5436 112 221,300 0.6142 0.6115 128 310 0.6841 0.6795 52 311 0.7522 0.7474 43 222 0.8175 0.8154 48 320 0.8883 0.8883 86 321 0.9537 0.9513 113 400 1.0901 1.0872 120 410,322 1.1569 1.1551 38 330,411 1.2242 1.2231 47 - 41 -Table V (continued) h k l Obs Calc I obs. 331 1.2919 1.2910 44 420 1.3597 , 1.1390 44 421 1.4274 1.4269 332 1.4967 1.4949 (e) The Reaction between WF^ and Ge metal i n Glass. Tungsten h e x a f l u o r i d e was passed over hot germanium contained i n a glass U tube connected t o an apparatus s i m i l a r t o th a t employed i n the pr e p a r a t i o n of germanium d i f l u o r i d e . A white s o l i d appeared on the co o l e r glass beyond the hot germanium whereas a deep blue s o l i d appeared i n the hot region o f the U tube. The blue compound gave the x-ray powder p a t t e r n c h a r a c t e r i s t i c of W02F. The white s o l i d (m.p. 65°) gave a complex powder p i c t u r e which c l o s e l y resembled t h a t o f tungsten oxide t e t r a f l u o r i d e . 35 A n a l y s i s of the white s o l i d by W i l l a r d - W i n t e r d i s t i l l a t i o n f o r f l u o r i n e , tungsten being estimated as the t r i o x i d e , i n d i c a t e d t h a t the compound was W0F4. Found: F, 24.5; W, 65.0%. Cal c . f o r W0F4: F, 27.55; W, 66.64%. (f ) The WF^-Ge metal Reaction i n Monel Apparatus. An attempt was made t o reduce tungsten h e x a f l u o r i d e t o tungsten p e n t a f l u o r i d e using germanium metal. Powdered germanium metal and.tungsten h e x a f l u o r i d e were taken i n s t o i c h i o m e t r i c q u a n t i t i e s i n t o a leak t i g h t monel r e a c t o r , s i m i l a r t o the one used i n PtF^ p r e p a r a t i o n . The reactants were heated t o >350° f o r 48 hours. The l i d o f the monel r e a c t o r was kept c o o l i n the usual way. The v o l a t i l e s were removed from the cooled r e a c t o r , - 42 -and the r e a c t o r opened i n the DRI-LAB, to r e v e a l a white compound on the l i d . This compound melted at 96.5°. The white s o l i d q u i c k l y became l i g h t b lue when exposed to moist a i r . A q u a l i t a t i v e t e s t showed i t to be paramagnetic. I t gave a complex x-ray powder p i c t u r e . 35 A n a l y s i s of the m a t e r i a l , ( f l u o r i n e by Wi l l a r d - W i n t e r d i s t i l l a t i o n , tungsten being estimated as t r i o x i d e by t r e a t i n g w i t h cone. HC1 and HNO^), showed i t to have an e m p i r i c a l formula c l o s e to Ge 0WF 0. z o Found: W, 38.2; F, 29.42; Ge by d i f f e r e n c e 32.4%. Ge 2WF g r e q u i r e s : W, 38.2; F, 31.6; Ge, 30.18%. - 43 -CHAPTER I I I DISCUSSION ( i ) The C r y s t a l S t r u c t u r e of Germanium D i f l u o r i d e The complete three dimensional x-ray s t r u c t u r a l a n a l y s i s c a r r i e d out on s i n g l e c r y s t a l s grown by slow s u b l i m a t i o n under vacuum has confirmed the orthorhombic u n i t c e l l w i t h a = 4.682; b = 5,178; c = 8.312 X, d e r i v e d 26 by B a r t l e t t and Yu from x-ray powder data, and has shown the Se02 type 26 s t r u c t u r e proposed by B a r t l e t t and Yu t o be approximately c o r r e c t . Germanium d i f l u o r i d e i s a chain polymer c o n s i s t i n g of a three dimensional f l u o r i n e bridged array. The s t r u c t u r e i s represented i n P l a t e I I , where a p r o j e c t i o n along a x i s b_ i s shown. I t c o n s i s t s of i n f i n i t e —F-Ge-F-Ge- chains p a r a l l e l t o b, having each f l u o r i n e atom almost e q u i d i s t a n t from the two coordinated germanium atoms. The F-Ge distances are 1.91 and 2.09 X and the Ge-F-Ge angle 157.4°. A l l f l u o r i n e atoms of such a chain are s t r u c t u r a l l y e q u i v a l e n t . Such chains' are cross l i n k e d by a second system of weak f l u o r i n e bridges p a r a l l e l to a_, i n which the f l u o r i n e atoms are l e s s symmetrically p l a c e d , the Ge-F distances being 1.79 and 2.57X. The f l u o r i n e atom at I.79X from one germanium atom i s at 2.57X: from the germanium atom i n an adjacent chain. These bridges then, form weak linkages between the p a r a l l e l chains. The two types of f l u o r i n e bridges are represented i n F i g . X. The three short bonded f l u o r i n e ligands (are F, 1.79, 1.91 and o 2.09A) form a t r i g o n a l pyramid with the a p i c a l germanium atom, the a p i c a l angles being 85.0, 85.6 and 91.6°. This u n i t i s s i m i l a r t o the molecular 32 shape a t t r i b u t e d t o antimony t r i f l u o r i d e , i n c r y s t a l l i n e SbF^, where the Sb-F distance i s 2.03X and F-Sb-F angle i s 88°. T h e C r y s t a l S t r u c t u r e o f G e r m a n i u m D i f l u o r i d e By James Trotter,* M. Akhtar, and Neil Bartlett * f Projection of the structure along the b axis •v Figure X. Fluorine Bridgingin GeF - 45 -S i m i l a r s t r u c t u r a l u n i t s have been observed i n other Ge(II) 30 and Sn(II) compounds, and f o r the most p a r t the d i s c u s s i o n of bonding i n these compounds has merely had reference t o a three coordinated Ge or Sn group. I t i s c l e a r that d i s c u s s i o n of the s t r u c t u r e and bonding i n GeF2 req u i r e s t h a t the f l u o r i n e l i g a n d 2.57A d i s t a n t from each germanium atom must be considered as a bonded l i g a n d a l s o . Thus a [GeF^] group i s app-r o p r i a t e f o r the d i s c u s s i o n of the bonding. The [GeF^] group may be des-c r i b e d as a d i s t o r t e d t r i g o n a l bipyramid arrangement of four f l u o r i n e ligands and a s t e r i c a l l y a c t i v e e l e c t r o n p a i r about the c e n t r a l metal atom. This group i s represented i n F i g . XI. As i s usual f o r such an 36 arrangement (e.g. SF^ ) the s h o r t e r bonded ligands and t h e non-bonding e l e c t r o n p a i r are l o c a t e d i n the e q u a t o r i a l plane. S i m i l a r c o o r d i n a t i o n o f the metal atom has been observed i n the •37 s a l t NaSn^F^ , where Sn^F^ u n i t s , r e s u l t i n g from strong f l u o r i n e b r i d g i n g o f two t r i g o n a l pyramidal groups, e x i s t . The weak f l u o r i n e bridges l i n k the Sn2Fg u n i t s together. Each t i n atom i s f o u r coordinated, having three c l o s e f l u o r i n e atoms, one of these being the b r i d g i n g f l u o r i n e of the Sn2F, u n i t , w h i l e the f o u r t h f l u o r i n e i s of an adjacent S^F^. u n i t . In Table VI the i n t e r a t o m i c distances and angles i n NaS^F^. are compared with those of GeF„. The n o t a t i o n i s the same as t h a t of F i g . XI. Table VI Compound a (A) b (A) c (X) . d (A) ab ac bAc GeF 2 1.79 1.91 2.09 2.5 7 91.6° 162.8° 85.6° 85.0° NaSn 2F 5 2.08 2.07 . 2.22 2.53 89.3 142.4 81.2 84.1 - 47 -Rundle has discussed the nature of bonding i n Sn(II) and Ge(Ii) 30 compounds. He describes the SnC]^ s t r u c t u r e , which c o n s i s t s of -Sn-Cl-Sn-Cl-chains i n which each t i n atom has two b r i d g i n g c h l o r i n e neighbours and a t h i r d c l o s e l y bound unique c h l o r i n e l i g a n d , i n terms of the SnCl^ s t r u c t u r a l u n i t . Rundle's d e s c r i p t i o n of the bonding i n t h i s compound assumes the Sn(II) nonbonding e l e c t r o n p a i r t o be l o c a t e d i n the valence set s o r b i t a l . The three c h l o r i n e ligands are considered t o be bonded as a consequence of the use of the three p o r b i t a l s of the Sn(IT) valence s e t . Thus a p a i r of e l e c t r o n s from one of the c h l o r i n e ligands and one e l e c t r o n p a i r from each of the other two c h l o r i n e ligands s a t i s f y the octet c o n d i t i o n . The ^ 9 0 ° bond angles are accounted f o r by t h i s hypothesis. I f such a d e s c r i p t i o n , u s i n g p o r b i t a l s alone, i s chosen f o r the s t r u c t u r e of germanium d i f l u o r i d e , i t i s necessary t h a t , two f l u o r i n e ligands could be bonded t o germanium by three centre four e l e c t r o n p a i r bonding i n v o l v i n g only one Ge(IT) p o r b i t a l and two by conventional e l e c t r o n p a i r bonds. Thus a u n i t w i t h two long bonded f l u o r i n e atoms w i t h a F-Ge-F angle of 180° and two short bonded f l u o r i n e atoms w i t h a F-Ge-F angle of 90° would a r i s e . L i g a n d - l i g a n d r e p u l s i o n s should lead t o bond angles even gre a t e r than t h i s . But the [GeF^] group i n germanium d i f l u o r i d e shows fou r F-Ge-F angles <90°. Indeed although Rundle p o i n t s out t o the repeated occurrence of X-M-X bond angles of 90° as support f o r h i s p o r b i t a l hypothesis, i t i s noteworthy t h a t the bond angles are considerably l e s s than 90°. With the non-bonding valence e l e c t r o n p a i r i n a s o r b i t a l , one would expect t h a t l i g a n d l i g a n d r e p u l s i o n s increase the bond angles to >90°. I t appears that the best bonding d e s c r i p t i o n of the GeF2 s t r u c t u r e should allow f o r s t e r i c a c t i v i t y of the non-bonding valence e l e c t r o n p a i r . The t r i g o n a l bipyramid arrangement of one e l e c t r o n and f o u r ligands w i t h two - 48 -long a x i a l bonds of 2.09 and 2.57A and with two short e q u a t o r i a l "bonds o f 1.79 and 1.9lA round the germanium atom i s i n agreement w i t h the 38 p r e d i c t i o n s of the simple valence e l e c t r o n p a i r r e p u l s i o n r u l e s . That a l l of the bond angles are l e s s than the i d e a l values may be accounted f o r i n terms of lone pair-bond p a i r r e p u l s i o n s . Furthermore the long empty tunnels i n the s t r u c t u r e are c o n s i s t e n t w i t h the presence of s t e r i c a l l y a c t i v e nonbonding valence e l e c t r o n p a i r s on the s i d e of each germanium d i s t a n t from the f l u o r i n e l i g a n d s . I t would appear then that a bonding scheme which uses p o r b i t a l s alone i s u n s a t i s f a c t o r y , and the involvement of outer o r b i t a l s , presumably d, at l e a s t i n germanium d i f l u o r i d e , appears l i k e l y . - 49 -( i i ) Chemistry of GeF^ (a) Reactions w i t h Halogens 26 33 The f i n d i n g s of B a r t l e t t and Yu and B a r t l e t t and Mak i n i n f r a r e d s p e c t r o s c o p i c examination of the products of the GeF2/Cl2 and GeF2/Br2 r e a c t i o n s agreed with the e a r l i e r observations of Booth and 31 M o r r i s , that the c h l o r o f l u o r i d e s and bromofluorides of germanium (IV) s l o w l y rearrange to unmixed t e t r a h a l i d e s , f o r example; 2 G e F 2 C l 2 :—• GeF 3Cl + GeCl 3F 2GeF 3Cl — > GeF^ + G e F 2 C l 2 e t c . 19 The F n.m.r. f i n d i n g s show, however, t h a t the rearrangements must, i n the absence of a c a t a l y s t , be very slow, s i n c e the resonance s p e c t r a at room temperature showed no evidence of f l u o r i n e l i g a n d exchange, and showed no change over a p e r i o d of s e v e r a l days. I t i s probable t h a t the exchange observed by the previous workers may have been c a t a l y s e d by HF i m p u r i t y , an i m p u r i t y l i k e l y t o be present i n the mixtures of the e a r l i e r s t u d i e s but not i n t h i s i n v e s t i g a t i o n , where r i g o r o u s l y anhydrous c o n d i t i o n s were maintained. The observed mixtures of c h l o r o f l u o r i d e s and bromofluorides from the halogen - GeF2 r e a c t i o n s : w i t h a very low t e t r a f l u o r i d e content, a s l i g h t excess of GeF2X2 and approximately equal concentrations o f GeFX 3 and GeF 3X, are c o n s i s t e n t w i t h the s t r u c t u r a l f i n d i n g s on GeF 2. Since each germanium atom i s short bonded t o three f l u o r i n e l i g a n d s , a GeF 3X product i s expected. Since the f o u r t h f l u o r i n e l i g a n d i s more d i s t a n t i t i s not s u r p r i s i n g that t h i s bond i s more r e a d i l y cleaved by by halogen. S i g n i f i c a n t l y , though the t e t r a f l u o r i d e i s observed, i t s concentration i s s m a l l . Of the four f l u o r i n e ligands about each germanium - 50 -atom i n the c r y s t a l (GeF: 1.79; 1 . 9 l ; 2.O9; 2.57A) the unusually long bond i s l i k e l y t o be most e a s i l y cleaved i n the o x i d a t i o n . On the other hand the s h o r t e s t bond i s l e a s t l i k e l y t o be broken. Thus the c h l o r i n a -t i o n (or bromination) o f the s o l i d i s seen to be u n l i k e l y t o produce large c o n c e n t r a t i o n of t e t r a f l u o r i d e or t e t r a c h l o r i d e (or tetrabromide). Presumably the 1.91'A GeF bond i s s l i g h t l y more d i f f i c u l t to break than the 2.09A bond. This being so, the p r e f e r r e d species r e s u l t i n g from the o x i d a t i o n s would be GeF2X2» with GeFX^ and GeF^X i n somewhat lower concen-t r a t i o n s . (b) F l u o r i d e Reduction Reactions. The i n a b i l i t y t o produce a lower f l u o r i d e o f i o d i n e by the r e d u c t i o n o f the p e n t a f l u o r i d e , w i t h the d i f l u o r i d e , matched the lack of 26 success which B a r t l e t t and Yu had i n t h e i r e f f o r t s t o derive a lower selenium f l u o r i d e from the t e t r a f l u o r i d e ' (elemental selenium was formed). The ready s e p a r a t i o n of i o d i n e and the absence of a s o l i d residue on removal of the excess i o d i n e p e n t a f l u o r i d e , i n d i c a t e d t h a t the r e a c t i o n had proceeded according t o the equation; 5GeF 2 +• 2 I F 5 > 5GeF 4 + I 2 The a l l e g e d i n s t a b i l i t y of the t r i f l u o r i d e towards d i s p r o p o r t i o n a t i o n : 5 I F 3 —*• I 2 + 3IFj- i n any case gave l i t t l e prospect of success. C l e a r l y i f germanium d i f l u o r i d e i s t o be a s u i t a b l e reagent f o r the p r e p a r a t i o n of unstable lower f l u o r i d e s l i k e SeF2 and I F ^ , a solvent convenient f o r low temperature work w i l l need t o be found. Anhydrous hydrogen f l u o r i d e does d i s s o l v e the d i f l u o r i d e and remains f l u i d t o low temperatures. I t may t h e r e f o r e have a p p l i c a t i o n i n t h i s area. A s o l u t i o n o f the d i f l u o r i d e i n anhydrous hydrogen f l u o r i d e - 51 -proved t o be capable of reducing platinum t e t r a f l u o r i d e . U n f o r t u n a t e l y the lower f l u o r i d e of platinum which had been hoped f o r was not produced. The t e t r a f l u o r i d e - germanium d i f l u o r i d e r a t i o , was appropriate f o r the formation of platinum d i f l u o r i d e : P t F ^ + GeF^ — > F t F 2 + GeF^f, but only h a l f of the platinum t e t r a f l u o r i d e was reduced and that d i r e c t l y t o the metal: 2 P t F 4 + 2GeF 2 — o - Pt + 2GeF4+. + P t F 4 > The sharpness o f the x-ray powder d i f f r a c t i o n p a t t e r n o f the platinum t e t r a f l u o r i d e i n the product i n d i c a t e d t h a t i t was the unchanged s t a r t i n g m a t e r i a l . I f the t e t r a f l u o r i d e i n the product had a r i s e n by the d i s p r o p o r t i o n a t i o n : 2 P t F 2 -—> Pt + P t F 4 the p a t t e r n would undoubtedly have been d i f f u s e . The d i f f u s e platinum metal p a t t e r n , which was recognised i n the powder d i f f r a c t i o n photographs of the r e s i d u e , were c o n s i s t e n t w i t h the r a p i d production o f the element at low temperature: P t F 4 + 2GeF 2 — > Pt + 2GeF 4. Since t h i s r e a c t i o n occurred below or at room temperature, there i s l i t t l e hope that i t could be e a s i l y c o n t r o l l e d t o produce a pure lower f l u o r i d e . C l e a r l y , i f a lower f l u o r i d e i s produced i n i t i a l l y , i t s r e d u c t i o n i s p r e f e r r e d t o that o f the o r i g i n a l h i g her f l u o r i d e . Since tungsten h e x a f l u o r i d e i s not e a s i l y reduced and s i n c e , other 39 than a p o o r l y c h a r a c t e r i z e d t e t r a f l u o r i d e , no other b i n a r y f l u o r i d e s o f tungsten were known, an e f f o r t was made to reduce the h e x a f l u o r i d e w i t h germanium d i f l u o r i d e . The i n i t i a l r e a c t i o n was c a r r i e d out i n glass appara-tu s . Since the only i d e n t i f i a b l e reduced tungsten product was an o x y f l u o r i d e of e m p i r i c a l formula W02F, i t i s p o s s i b l e t h a t t h i s arose by a r e a c t i o n sequence: 2WF, + SiO„ — S i F . + 2W0F. b ' 2. 4 4 2WGF4 +'GeF2 —>• GeF 4 + 2WOF3 2WOF3 + S i 0 2 —t 2W02F + S i F 4 - 52 -The i n v o l a t i l e tungsten o x y f l u o r i d e i s of some s t r u c t u r a l and magnetic i n t e r e s t , but i t i s u n l i k e l y that i t has been obtained pure. I n s u f f i c i e n t m a t e r i a l was secured f o r magnetic s u s c e p t i b i l i t y measurements over a temperature range by the Guoy technique. C l e a r l y i t would be more s a t i s f a c t o r y t o prepare the m a t e r i a l i n higher y i e l d and p u r i t y by re d u c t i o n of the appropriate tungsten (VI) o x y f l u o r i d e : 2W0 2F 2 + GeF 2 — • 2W02F + GeF^ ? The observed x-ray d i f f r a c t i o n data show that the W02F has an ReO^ 40 s t r u c t u r e . The oxygen and f l u o r i n e atom arrangement must be disord e r e d . With the tungsten atoms at the o r i g i n of the simple cubic u n i t c e l l , the l i g h t atom arrangement which gives the best f i t w i t h the observed i n t e n s i t y data i s that w i t h the atoms i n the mid p o i n t cube edge l o c a t i o n s i.e.^an ReOg arrangement. This^may be seen by reference t o Table VII. . Table VII S t r u c t u r a l Data f o r W02F P r i m i t i v e Cubic u n i t c e l l a l t e r n a t i v e s (1) W at 0,0,0; 3F(0) at 1,6,0; 0,1,0; 0,0,1; e t c . (2) W at 0,0,0; 3F(0) at l,*-,0; 0,l_,|-; ^,6,^; e t c . R e l a t i v e I n t e n s i t i e s - I h k l I obs I c a l c ( 1 ) * I c a l c ( 2 ) * 100 13.2 17.2 10.9 110 17.9 18.2 18.2 111 7.3 6.7 20.2 200 16.9 12.7 12.7 210 42.9 32.9 23.8 211 20.7 21.1 21.1 220 12.4 15.1 15.1 - 53 -Table V I I I (continued) * 40 I n t e n s i t y data c a l c u l a t e d f o r ReO^ by M e i s e l . The i n t e n s i t y agreement with the a l t e r n a t i v e model i n which the l i g h t atoms are loc a t e d at the face centre p o s i t i o n s o f the cube (with W at 0,0,0) i s much l e s s s a t i s f a c t o r y . I t i s perhaps not without s i g n i -f i c a n c e that ReO^ and t h i s new and i s o s t r u c t u r a l o x y f l u o r i d e of tungsten 39 are isoelectr:onic. I t remains t o be seen i f WOF^ w i l l possess the same s t r u c t u r e . . . -The attempts t o prepare a lower b i n a r y f l u o r i d e o f tungsten by red u c t i o n of the h e x a f l u o r i d e e i t h e r by germanium d i f l u o r i d e or by germanium metal,both w i t h and without anhydrous hydrogen f l u o r i d e s o l v e n t , were un s u c c e s s f u l . The m a t e r i a l which was produced both i n the WF^ + GeV^ and WFg + Ge r e a c t i o n s i s as yet p o o r l y c h a r a c t e r i z e d , having an e m p i r i c a l formula approximating to Ge„WF . S u r p r i s i n g l y , t h i s white paramagnetic Z o s o l i d i s sublimable (m.p. 96.5°) and yet f o r m a l l y the tungsten i s r e q u i r e d t o be fou r v a l e n t ( i f the germanium, as seems reasonable, i s counted as d i v a l e n t ) . I t i s conceivable, although unexpected, that the germanium d i f l u o r i d e i s here a c t i n g as an e l e c t r o n p a i r donor and th a t the tungsten i s four coordinated by f l u o r i n e ligands and two coordinated by GeF^ groups as shown: F v . F V \/ / Ge — > W « Ge S A N F F Unfortunately n e i t h e r s i n g l e c r y s t a l s nor i n t e r p r e t a b l e x-ray powder photographs were obtained and there i s as yet no s t r u c t u r a l i n f o r m a t i o n f o r t h i s i n t e r e s t i n g compound. - 54 -REFERENCES 1. N.. B a r t l e t t and D. H. Lohmann, J . Chem. S o c , 619 (1964). 2. A. J . Edwards, J . Chem. S o c , 3714 (1964). 3. A. J . Edwards, R. D. Peacock and R. W. H. Small, J . Chem. S o c , 4486 (1962). 4. J . H. Holloway, R. D. Peacock and R. W. H. Small, J . Chem. S o c , 644 (1964). 5. M. A. Hepworth, K. H. Jack, R. D. Peacock and G.'J. Westland, Acta C r y s t . , 10, 63 (1957). 6. J . H. Holloway, P. R. Rao and N. B a r t l e t t , Chem. Comm., 306 (1965). 7. N. B a r t l e t t and P. R. Rao, Chem. Comm., 252 (1965). 8. N. B a r t l e t t and N.K. Jha, "The Xenon-Platinum H e x a f l u o r i d e Reactions and Related Reactions", i n "Noble Gas Compounds", ed. H. H. Hyman, U n i v e r s i t y of Chicago Press, Chicago, (1963). 9. N. B a r t l e t t and P. R. Rao, P r o c Chem. S o c , 393 (1964) . 10. B. Weinstock, J . G. Malm, and E. E. Weaver, J . Am. Chem. S o c , 83, 4310 (1961). 11. D. H. Lohmann, Ph.D. Th e s i s , U n i v e r s i t y of B r i t i s h Columbia, Canada. (1961). 12. G. Star k , Z. Anorg. Chem., 70, 173 (1911). 13. H. C. Clark and R. J . O'Brian, Can. J . Chem., 39, 1030 (1961). 14. B. N. F i g g i s and R. S. Nyholm, J . Chem. S o c , 4190 (1958). 15. P. W. Selwood, "Magnetochemistry", 2nd ed., I n t e r s c i e n c e , New York, 92 (1956). 16. B. N. F i g g i s and J . Lewis, "The Magnetic P r o p e r t i e s o f T r a n s i t i o n Metal Complexes", i n "Progress i n Inorganic Chemistry", V o l . 6, ed. F. A. Cotton, I n t e r s c i e n c e , New York, (1964). 17. N. B a r t l e t t , 1st. Noranda Lecture, Chemistry i n Canada, p.33, August 1963. 18. A. J . Edwards, unpublished work. 19. L. P a u l i n g , "The Nature of Chemical Bond", 3rd ed., C o r n e l l U n i v e r s i t y P r e s s , I t h a c a , New York, 108 (1960). - 55 -20. M. K o t a n i , J . Phy..Soc. (Japan), \ 4, 293 (1948). 21. B. N. F i g g i s , at e l , Faraday Soc. D i s c , 26, 103 (1958). 22. D. Bose and H. Bhar, Z. Phy., 48, 716 (1928). 23. C. Winkler, J . p r a k t . Chem., 36(2), 193 (1887) . 24. L. M. Dennis and A. W. Laubengayer, Z. physik. Chem. ( L e i p z i g ) , 130, 530(1927). 25. E. L. M u e t t e r t i e s and J . E. C a s t l e , J . Inorg. N u c l . Chem. 18, 148 (1961) . 26. N. B a r t l e t t and K. C. Yu, Can. J . Chem.,39, 80 (1961). 27. J . D. McCullough, J . Am. Chem. Soc., 59, 790 (1937). 28. D. Olson and R. E. Rundle, unpublished work. 29. K. S. Rao, B. P. S t o i c h e f f , and R. Turner, Can. J . Phy., 1916 (1960). 30. R. E. Rundle, "Coordination Number and Valence i n Modern S t r u c t u r a l Chemistry", i n "Record of Chemical Progress", V o l . 23, No.4, December 1962. 31. H. S. Booth and W. C. M o r r i s , J . Am. Chem. S o c , 58, 90 (1936) . 32. A. Bystrom and A. Westgren, A r k i v Kemi M i n e r a l . Geol., 17B, No.2, (1943). 33. N. B a r t l e t t and S. Y. C. Mak, unpublished r e s u l t s . 34. L. H. Meyer and H. S. Gutowsky, J . Phy. Chem.,,57, 481 (1953) . 35. H. H. W i l l a r d and 0. B. Winter, Ind. Eng. Chem. Anal. Ed., 5, 7 (1933). 36. F. A. Cotton, J . W. George and J . S. Waugh, J . Chem. Phy., 28, 994 (1958). R. E. Dodd, L. A. Woodward, and H. L. Roberts, Trans. Faraday S o c , 52, 1052 (1956). 37. R. R. McDonald, A. C. Larson and D. T. Cromer, Acta. C r y s t . , 17, 1104 (1964). 38. R. J . G i l l e s p i e and R. S. Nyholm, Quart. Revs., 11, 339 (1957). R. J . G i l l e s p i e , J . Chem. Edu., 40, 295 (1963). 39. H. F. P r i e s t and W. C. Schumb, J . Am. Chem. S o c , 70, 3378 (1948). 40. V. K. M e i s e l , Z. Anorg. und A l l e g e . Chem., 207, 121 (1932). 41. J . Edwards, D. H u g i l l and R. D. Peacock, c i t e d i n Proc. Chem. S o c , 205 (1963) . - 56 -APPENDIX I $IBFTC APPROX C FORTRAN FOUR CONVERSION OF STRAIGHT LINE APPROXIMATION C ESTIMATION OF PARAMETERS FOR A STRAIGHT-LINE APPROXIMATION C LET N = NUMBER OF OBSERVATIONS C LET X = IMDEPENDENT VARIABLE C LET Y = DEPENDENT VARIABLE C THIS PROGRAM FITS LINE TO 1/MAGS VS TEMP C LET Y(J) BE MAGS NOT 1/MAGS C LET X(J) BE TEMP 14 SX = 0. SY = 0. SXX = 0. SXY = 0. SYY = 0. J=0 READ(5,1)N,AX,AY 1 FORMAT(16,2X,A4,2X,A4) DIMENSIONX(IOO),Y(100) DO 2 I = 1,N J=J+1 READ(5,3)X(J) ,Y(J) 3 FORMAT(F7.0/F7.0) Y(J)=1./Y(J) SX = SX + X(J) SY = SY + Y(J) SXX=SXX+X(J)*X(J) SXY=SXY+X(J)*Y(J) 2 SYY=SYY+Y(J)*Y(J) READ(5,20)TEST 20 FORMAT(A3) CALL SETHOL(CHECK,3HEND) IF(TEST-CHECK)11,12,11 11 WRITE(6,13) 13 FORMAT(5IH WRONG NUMBER OF DATA CARDS OR LAST DATA CARD NOT , 1 32HFOLLOWED BY AN END-OF-DATA CARD ) STOP 12 FN = N DN = l./FN AVX = SX*DN AVY = SY*DN CALL SKIP TO (1) WRITE(6,4)AX,AVX,AY,AVY 4 FORMAT(16H MEAN VALUE OF A4,3H = E13.6/15X,A4,3H = E13.6) DNN = l./CFN - 1.) S = SXX - SX*AVX COVX = S*DNN COVX = (SYY - SY*AVY)*DNN COVXY = (SXY - SX*AVY)*DNN STDX=SQRT(COVX) STDY=SQRT(COVY) WRITE(6,5)AX,STDX,AY,STDY 5 FORMAT(//23H STANDARD DEVIATION OF A4,3H = E13.6/22X,A4,3H = E13.6 1 ) - 58 -CORR = COVXY/(STDX*STDY) WRITE(6,6)AX,AY,CORR 6 FORMAT(//21H CORRELATION BETWEEN A4,4HAND A4,3H = F10.8) A = COVXY/COVX WRITE(6,7)A 7 FORMAT(//32H SLOPE OF REGRESSION LINE = E13.6) B = AVY - A*AVX WRITE(6,8)B 8 FORMAT(32H INTERCEPT OF REGRESSION LINE = E13.6) R=SQRT ( (FN-1 .'•) * (C0VY-A*A*COVX) / (FN-2.) ) WRITE(6,9)R 9 FORMAT(32H STANDARD ERROR OF ESTIMATE = E13.6) SI=R*SQRT(DN+AVX*AVX/S) SS=R*SQRT(1./S) WRITE(6,10)SS,SI 10 FORMAT(3IH CONFIDENCE INTERVAL PARAMETERS/21X10HSLOPE = E13.6/ 121X10HINTERCEPT E13.6) WRITE(6,22) 22- FORMAT(////115H TEMP SUSC.(OBS) SUSCCCALC) 1 DEVIATION (CGS*10E-6) 1 / T E M P ^ C C O E S ) (1/CGS)) N=FN J=0 D0421=1,N J=J+1 YCALC=A*XCJ)+B SCALC=1000000./YCALC SOBSV=1000000./Y(J) SDEVI=SOBSV-SCALC - 59 -TINV=1./X(J) WRITE(6,33)X(J),SOBSV,SCALC,SDEVI,TINV,Y(J) 33 FORMAT(F10.2,8H ,F10.2,9H ,F10,2,9H ,F10.2, 116H ,F10.5,2H ,F10,2) 42 CONTINUE WRITE(6,44) 44 FORMAT(////28H TEMP SUSC(CALC)//) TEMP=60. D0521=l,12 TEMP=TEMP+20, YCALC=A*TEMP+B SCALC=1000000./YCALC WRITE(6,55)TEMP,SCALC 55 FORMAT(FIO. 2,8H ,F10..2) 52 CONTINUE GO TO 14 END - 60 -APPENDIX I I $IBFTC INDEXX 44 BN=0. CN=0. SCP=0. SBP=0. C CALC OF BEAM STOP CENTRE BPA=AV(Xl*X2/2) C DATA CARD WITH X1=X2=0 SIGNALS END OF DATA 1 READ(5,30)XI,X2 30 FORMAT(2F10.3) BP=(Xl+X2)/2. SBP=SBP+BP IF(BP.EQ.O.)GO TO 3 BN=BN+1. GO TO 1 3 BPA=SBP/BN C CALC OF COLLIMATOR CENTRE CPA=AV(X1+X2)/2 C DATA CARD WITH X1=X2=0. SIGNALS END OF DATA 4 READ(5,30)XI 3X2 CP=(Xl+X2)/2. SCP=SCP+CP IF(CP.EQ.0.)GO TO 5 CN=CN+1. GO TO 4 5 . CPA=SCP/CN WRITE(6,75) - 61 -75 FORMAT(IX,10H XI ,20H 2THETA,20H D 1HKL ,20H 1/D*D. ,30H NRFN // 2/) C FACTOR TO CONVERT ARC TO ANGLE ANGLE=3.1414/(CPA-BPA) IF(ANGLE.LT.O.)GO TO 7 GO TO 13 7 ANGLE=-ANGLE C CALC OF 2THETA,DCORR,l/D*D C IF X FOR ALPHA1 ADD 100 TO X VALUE C IF X FOR ALPHA2, ADD 200 TO X VALUE 'IT*' C X1=0 SIGNALS END OF DATA +'NO OTHER SET C Xl=999 SIGNALS END OF DATA + ANOTHER SET FOLLOWING 13 READ(5,2)X1 2 FORMAT(F10.3) IF(X1.EQ.O.)GO TO 17 IF(X1.EQ.999.)G0 TO 70 IF(XI.GT.200.)GO TO 14 IF(X1.GT.100.)GO TO 15 AMBDA=0.7709 GO TO 16 14 Xl=Xl-200. AMBDA=0.77217 GO TO 16 15 X1=X1-100. AMBDA=0.77025 GO TO 16 - 62 -16 X2=X1-BPA THETA2=X2*ANGLE IF(THETA2.LT.0.)G0 TO 20 GO TO 21 20 THETA2=-THETA2 21 THETA=THETA2/2. CTHETA=COS(THETA) STHETA=SIN(THETA) XTHETA=1./STHETA DHKL=AMBDA*XTHETA DINSQ=1./(DHKL*DHKL) XNRFN=0.5*C(CTHETA*CTHETA/STHETA)+(CTHETA*CTHETA/THETA)) THETA2=360./6.2828*THETA2 WRITE(6,18)X1,THETA2,DHKL,DINSQ,XNRFN 18 F0RMAT(1X,F10.3,10H ,F10.3,10H ,F10.5,10H 1 ,F10.6,20H ,F10.3/) GO TO 13 70 CALL SKIP TO (1) GO TO 44 17 STOP END 

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