UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

Fluorides of palladium Quail, John Wilson 1961

Your browser doesn't seem to have a PDF viewer, please download the PDF to view this item.

Item Metadata

Download

Media
831-UBC_1961_A6_7 Q8 F5.pdf [ 3.06MB ]
Metadata
JSON: 831-1.0062145.json
JSON-LD: 831-1.0062145-ld.json
RDF/XML (Pretty): 831-1.0062145-rdf.xml
RDF/JSON: 831-1.0062145-rdf.json
Turtle: 831-1.0062145-turtle.txt
N-Triples: 831-1.0062145-rdf-ntriples.txt
Original Record: 831-1.0062145-source.json
Full Text
831-1.0062145-fulltext.txt
Citation
831-1.0062145.ris

Full Text

FLUORIDES OF PALLADIUM by JOHN WILSON QUAIL B. Sc., Uni v e r s i t y of B r i t i s h Columbia, 1959 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n the Department of CHEMISTRY We accept t h i s thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA A p r i l , 1961 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 advanced degree a 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 , I agree t h a t the 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 and s t u d y . I f u r t h e r agree 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 purposes may be g r a n t e d by t h e Head o f my Department o r by h i s r e p r e s e n t a t i v e s . I t i s u n d e r s t o o d t h a t c o p y i n g o r p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l not 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 . 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 Vancouver $, Canada. Department o f i i ABSTRACT The preparation and reactions of simple and complex f l u o r i d e s of palladium and gold using f l u o r i d e solvents have been studied. Two new compounds, fluoselenonium hexaf luo-palladate (IV) and fluoselenonium tetrafluoaurate ( I I I ) , have been prepared. Both are acids i n the selenium t e t r a f l u o r i d e solvent system. Fluoselenonium hexafluo-palladate (17) reacts with a base, potassium pentafluo-selenate (IV), to form a s a l t , potassium hexafluopalladate (IV) which c r y s t a l l i z e s i n a t r i g o n a l modification, a = 5.717 ± .003 i? , c . 4.667 + .003 A* . Pure palladium d i f l u o r i d e has been produced i n two reactions. These reactions are: (1) the thermal decomposition of fluoselenonium hexafluopalladate (IV), and (2) the reduction of palladium t r i f l u o r i d e with selenium t e t r a f l u o r i d e . The magnetic moment of the bromine t r i f l u o r i d e adduct of palladium t r i f l u o r i d e has been measured and found to be 2.2 B.M. Evidence i s presented for the existence of a potassium s a l t of the t r i f l u o p a l l a d a t e (II) ion. I t has i i i not been possible to prepare complex f l u o r i d e s of t e r p o s i t i v e palladium i n selenium t e t r a f l u o r i d e s o l u t i o n . i v TABLE OF CONTENTS PAGE L i s t of Figures v i L i s t of Tables v i Chapter 1. Introduction 1 2 . Discussion 8 3 . Conclusion 22 4. Experimental 25 I General Techniques 2 5 a) Glassware 2 5 b) X-Ray Photographs 26 c) Magnetic Measurements '. 26 II A n a l y t i c a l Methods 28 a) Fluorine 28 b) Palladium 30 c) Selenium 31 d) Gold and Selenium 3 1 e) Bromine 3 1 III Reactants 31 a) Fluorine Supply • 31 b) Bromine T r i f l u o r i d e 33 c) Palladium Diiodide and Dibromide 34 d) Gold 34 e) Potassium Fluoride 3 5 V PAGE IV The Preparation of Selenium Tetrafluoride ... 35 V The Preparation of Palladium Trifluoride and Its Adduct ¥ith Bromine Trifluoride 36 VI The Preparation of Fluoselenonium Hexafluopalladate (IV) 38 VII The Reaction of Fluoselenonium Hexafluo-palladate (IV) With Bromine Trifluoride 39 VIII Reactions of Fluoselenonium Hexafluo-palladate (IV) 39 IX The Preparation of Palladium Difluoride 40 X Potassium Fluoride and Palladium Difluoride in Selenium Tetrafluoride 41 XI Potassium Fluoride and Palladium Trifluoride in Selenium Tetrafluoride 42 XII The Preparation of Potassium Hexafluo-palladate (IV) 44 XIII The Crystal Structure of Potassium Hexafluo-palladate (IV) 47 5. Bibliography 52 6. Vita 54 v i LIST OF FIGURES To Follow Page 1. Apparatus for the Preparation of SeF^ 35 2. Apparatus for the Preparation of KgPdF^ 44 LIST OF TABLES Page 1. Known Simple Fluorides of Group VIII Metals .... 2 2. The Physical Properties of Some Fluoride Solvents 6 3. Trigonal Modifications of Potassium Salts of Hexafluo-, Quadripositive Ge, Pd and Pt 14 4. Fluorides of Palladium 23 5. X-Ray Data for a Potassium Salt of Fluo-palladate (II) (CuK^ radiation) 43 6. Assignment of the X-Ray Reflections of K 2PdF£ (CuK^. radiation) 48 7. Observed and Calculated X-Ray I n t e n s i t i e s f o r K 2PdF 6 (CuK^ radiation) 51 v i i ACKNOWLEDGEMENT The author wishes to express his sincere appreciation to Dr. N. B a r t l e t t for h i s guidance and encouragement throughout the course of t h i s work. He also wishes to thank the other members of the s t a f f and his fellow graduate students for th e i r h e l p f u l suggestions. The author i s gr a t e f u l to the National Research Council for f i n a n c i a l assistance, i n the form of a Studentship, during the period from May I960 to A p r i l 1961. INTRODUCTION Immediately after the Second World War commercial supplies of f l u o r i n e became r e a d i l y a v a i l a b l e . This was the r e s u l t of wartime interest i n uranium hexafluoride. The a v a i l a b i l i t y of f l u o r i n e stimulated interest i n f l u o r i n e compounds. The pioneering studies of Moissan and Ruff had layed a foundation to the chemistry of f l u o r i n e and f l u o r i d e s , but much of the early work i s contradictory and u n r e l i a b l e . The recent p r o o f 1 that the long accepted osmium o c t a f l u o r i d e 2 i s i n fa c t osmium hexafluoride points both to the need for caution i n accepting e a r l i e r r e s u l t s and the d i f f i c u l t y inherent i n the experimental work. Despite the great a c t i v i t y i n a l l branches of f l u o r i n e chemistry during the past f i f t e e n years, large gaps remain i n our knowledge. As long as such gaps remain, interest i n t h i s f i e l d w i l l remain at a high l e v e l . The f l u o r i d e s of t r a n s i t i o n metals have been the center of a great deal of interest because of the wide range of valence states which are encountered. The known simple f l u o r i d e s of group VIII metals are shown i n Table 1. Nickel tends toward the lowest oxidation state. In going down and across the group from n i c k e l a tendency toward higher oxidation states i s noted. Fluorine compounds of palladium have been prepared i n the t2, +3 and «-4 oxidation states. Two simple f l u o r i d e s 2 TABLE I Known Simple Fluorides of Group VIII Metals Fe Co Ni FeF 2 CoF 2 N i F 2 FeF^ C o F 3 2 sa m m PdF RUF3 RhF 3 PdF 3 RhF 4 RuFtj Os Ir £t [PtF^J 0 s F 4 I r F 4 P t F 4 O s F 5 [ i r F ^ PtF^ OsF, Ir'F, PtF, Compounds given i n brackets are not established with c e r t a i n t y 3 of palladium have been prepared, the d i f l u o r i d e and the t r i f l u o r i d e . It i s inte r e s t i n g that the t e t r a f l u o r i d e cannot be made although platinum t e t r a f l u o r i d e i s e a s i l y prepared. The t r i f l u o r i d e was f i r s t prepared i n 1 9 2 8 by Ruff and Ascher,^ by heating palladium metal to 500° i n a stream of f l u o r i n e . The black c r y s t a l l i n e powder i s very hygroscopic and i t hydrolyzes r a p i d l y when exposed to moist a i r . Other methods of preparing the t r i f l u o r i d e have been 4 discovered. Sharpe has prepared palladium t r i f l u o r i d e by reacting palladium dibromide with bromine t r i f l u o r i d e to give a bromine t r i f l u o r i d e adduct of palladium t r i f l u o r i d e which was decomposed under vacuum at 2 2 0 ° to give pure palladium t r i f l u o r i d e . B e r z e l i u s ^ claimed to have made palladium d i f l u o r i d e by the action of f l u o r i d e s upon palladous s a l t s i n aqueous so l u t i o n . This claim i s i n v a l i d since palladium d i f l u o r i d e i s r e a d i l y and i r r e v e r s i b l y hydrolyzed. The t r i f l u o r i d e i s e a s i l y reduced to palladium d i f l u o r i d e and to palladium metal by such reagents as hydrogen, sulfu r dioxide and iodine vapour. I f appropriate quantities of palladium t r i f l u o r i d e and palladium metal powder are heated together a reaction occurs and palladium d i f l u o r i d e i s formed. None of the above reactions gives pure palladium d i f l u o r i d e . Palladium metal Is always present. Palladium d i f l u o r i d e was f i r s t prepared pure by B a r t l e t t and Hepworth, 4 who reduced the bromine trif l u o r i d e complex of palladium trif l u o r i d e with selenium tetrafluoride at approximately 1 5 0 ° . Palladium difluoride Is a violet to light brown powder, the color depending on i t s origin. It i s hydrolyzed by moisture to the monoxide, but It can easily be kept for long periods in a dry sealed glass tube, A complex fluoride of palladium was not prepared u n t i l 1950, when Sharpe 4 prepared the bromine tr i f l u o r i d e complex of palladium tri f l u o r i d e as described above, o Hoppe and Klemm soon afterward prepared the hexafluo-palladates (IV) of potassium, caesium and rubidium by the fluorination of the corresponding chloropalladates. The only complex dipositive fluoride which Is known i s caesium 9 trifluopalladate (II), which has been prepared by Bartlett. The main reason for the d i f f i c u l t y i n preparing fluorides of palladium i s their i n s t a b i l i t y toward hydrolysis. For the quadripositive hexafluopalladates this behavior is unusual when compared to the quadripositive hexafluo-platinates, which can be recrystallized from aqueous solution. The work which is described in this thesis was directed toward preparing complex fluorides of d l - and terpositive palladium. Complete success was not achieved in this area. However, the paths of several interesting reactions have been established. Also, a new crystal modifi-cation of potassium hexafluopalladate (IV) has been prepared 5 and evidence i s presented for the existence of a potassium s a l t of dispositve palladium. Dry methods of preparation are often unsatis-factory because reaction i s usually incomplete and an inhomo-geneous product i s obtained. An i d e a l s i t u a t i o n would be to have a solvent which was chemically inert but highly polar and capable of d i s s o l v i n g t r a n s i t i o n metal f l u o r i d e s . No such solvent i s known. However, a number of solvents are known which combine varying proportions of the desired q u a l i t i e s of inertness and polar nature. Some of these solvents and t h e i r physical properties are tabulated i n Table 2 . The extremely high Trouton's constant for selenium t e t r a f l u o r i d e suggests that i t would be a very polar solvent. It has mild reducing properties and i t also f l u o r i n a t e s by exchange. Chemical evidence suggests that selenium t e t r a -f l u o r i d e behaves as an i o n i z i n g solvent according to the equilibrium 2 SeF 4 N s S e F 3 f • SeF^~ Complexes are formed with some t r a n s i t i o n metal 12 f l u o r i d e s , such as SeF^ OsF^, which can be considered as an "acid" i n the selenium t e t r a f l u o r i d e solvent system. Bromine t r i f l u o r i d e also has a high Trouton's constant. It has good solvent properties but i t i s an extremely powerful f l u o r i n a t i n g agent, which greatly l i m i t s i t s usefulness. It i s believed to ionize according to the 6 TABLE 2 The Physical Properties of Some Fluoride Solvents m.pt. b.pt. Trouton's Reference Constant B r F 3 8.8° 125° 25.7 10 B r F 5 -61.3° 40.5 23.2 10 IF 5 9.6 98° 26.3 10 S F 4 o -121 o -40 27.1 10 SeF. 4 -9.3° 106 30.0 10 HF -83° © 20 20.6 11 7 equilibrium 2BrF_ - ^ BrF * * BrF ~ 3 ^ 2 4 Evidence for i o n i z a t i o n i s found i n the i s o l a t i o n of such "acids" as BrF^ SbF^ and B rF 2AuF 4 1^ and such "bases" as KBrF 4 and A g B r F 4 . 1 4 None of the above solvents could be considered i d e a l . Each has i t s own advantages and shortcomings. The p a r t i c u l a r reaction to be studied w i l l determine the choice of the most appropriate solvent. DISCUSSION The only f l u o r i d e complex of t e r p o s i t i v e palladium which has been prepared i s the l s l bromine t r i -f l u o r i d e complex of palladium t r i f l u o r i d e . 4 - This complex has been found to possess a magnetic momenty^^ • 2.2 B.M. at 21°, which i s very close to Nyholm and Sharpe's v a l u e 1 ^ for palladium t r i f l u o r i d e ^ e f f » 2.0 B.M.). The magnetic moment of palladium t r i f l u o r i d e could be due to either one or three unpaired electron spins. The value i s large f o r one unpaired electron spin, but could be accounted f o r by three. Low values are usual i n the second and t h i r d t r a n s i t i o n s e r i e s 1 ^ ? 7^ and can be explained by spin-orbit 18 coupling. The c r y s t a l structure i s rhombohedral, being made up of a hexagonal close packing of the f l u o r i n e atoms with palladium atoms i n octahedral hole s i t e s . In the cubic e l e c t r o s t a t i c f i e l d of the f l u o r i n e s , the f i v e degenerate 4d o r b i t a l s of the palladium are s p l i t into a lower t r i p l e t of u d e " o r b i t a l s (d Xy> <3XZ> <3 y z) which are orientated between the three axes on which the f l u o r i n e s are situated and an upper doublet of "d^" o r b i t a l s ( d x 2 l y 2 , d z 2> orientated along the axes. The magnitude of t h i s s p l i t t i n g i s d i r e c t l y proportional to the charge or dipole moment of the ligand, the number of ligands and the average value of the fourth power of the radius of the "d" electrons. It i s inversely proportional to the f i f t h or s i x t h power of the distance from the center of the ion to the center of the ligand. As 9 electrons are added to the "d" o r b i t a l s Hund's rules are obeyed. That i s , two electrons avoid being i n the same or b i t i f possible, and the i r spins are p a r a l l e l i f they are i n d i f f e r e n t singly occupied o r b i t s of the same energy. In an octahedral complex the f i r s t three 11 d" electrons w i l l then go into the lower set of three o r b i t a l s . The next few electrons w i l l either f i l l the higher pair of l e v e l s or pair up and occupy the lower l e v e l s doubly. The choice w i l l depend on the s p l i t t i n g between the upper and lower l e v e l s and on the pairing energy required. I f the s p l i t t i n g i s large, then pairing w i l l occur and a reduced magnetism w i l l r e s u l t . I f the s p l i t t i n g i s small, then the electrons w i l l occupy d i f f e r e n t o r b i t a l s and the maximum paramag-netism w i l l be observed. A l l Pd-F bond lengths are of equal length In a near perfect octahedron. 1® Ligand F i e l d Theory predicts that the f i l l i n g of the dy o r b i t a l s must be symmetrical. Any unsymmetrieal f i l l i n g of the dy o r b i t a l s would r e s u l t i n unequal repulsion on the six surrounding f l u o r i n e s and an imperfect octahedron. It i s probable that the electron configuration i s the same i n the bromine t r i f l u o r i d e complex. For palladium t r i f l u o r i d e the electronic con-f i g u r a t i o n i s p r o b a b l y ^ 10 Palladium difluoride has a ru t i l e structure which places six fluorines octahedrally around each palladium. The Pd-F bond distances are Identical within experimental error. Ligand Field Theory predicts a sym-metric f i l l i n g of the d^, orbitals. Pd +2 H H H V - V -Palladium difluorlde has a magnetic momenty^.^, « 1.84 B.M. at room temperature. 2 0 This value indicates two unpaired electrons in the d shell. The spin only value for two unpaired electron spins is 2.83 B.M. The low value can be explained by spin orbit coupling. Further lowering can be attributed to antiferromagnetlsm. The preparation of palladium difluoride by 7 Bartlett and Hepwortir suggested the existence of a selenium tetrafluoride derivative of palladium t r i f l u o r i d e . In their preparation they reacted the bromine trif l u o r i d e complex of palladium tri f l u o r i d e with selenium tetrafluoride. The compound which resulted was decomposed at 150 , in an atmosphere of selenium tetrafluoride, to palladium difluorlde . An attempt was made to prepare the supposed terpositive intermediate complex by displacing the bromine tr i f l u o r i d e from the 1:1 bromine trifluoride-palladium t r i f l u o r i d e complex with selenium tetrafluoride. Wien the selenium tetrafluoride was added to the complex, copious quantities of bromine were evolved. This was unusual in view of the 11 fact that no reaction is observed between bromine t r i -fluoride and selenium tetrafluoride when they are boiled together. The appearance of bromine was indicative, of reduction of the bromine tr i f l u o r i d e . The isolation of the solid product fluoselenonium hexafluopalladate (IV) proved that the palladium had been further oxidized to the quadripositive state: 6 BrF , PdF- «• 12 SeF >6 (SeF.)_ PdFc «• Br «• 4 BrF_ In this reaction selenium tetrafluoride acts like an a l k a l i fluoride. This reaction is similar to the oxidation of palladium to the quadripositive state by bromine tr i f l u o r i d e in the presence of potassium, rubidium and caesium fluorides as reported by Sharpe. 2 1 The selenium tetrafluoride appears to be a fluoride ion donor, and i t stabilizes the palladium in the quadripositive state by the formation of PdF^~ octahedra. Fluoselenonium hexafluopalladate (IV) i s dia-magnetic. A l l of the electrons must therefore be paired. The six 4d electrons of the quadripositive palladium f i l l the 4d orbitals,/ The 4d orbitals are available to form d sp J hybrid orbitals for octahedral coordination to the six fluorines. It 'is possible that the quadripositive palladium could be stabilized by the donation of electron pairs from the selenium tetrafluoride molecules to vacant orbitals of V 12 the palladium. Linkage through f l u o r i n e atom bridges could also occur. These p o s s i b i l i t i e s appear u n l i k e l y i n view of the fac t that s i m i l a r compounds of quadripositive platinum 7 and germanium have been prepared and are i s o -s t r u c t u r a l with the quadripositive palladium compound. It i s known, however, that the ions PdF^ = , PtF g = and GeF^~ octahedra are extremely similar i n s i 2 e and shape. This w i l l be substantiated i n the following discussion. Fluoselenonium hexafluopalladate (IV) i s an "acid" i n the selenium t e t r a f l u o r i d e solvent system. It can be "neutralized" by a "base" such as potassium pentafluo-selenate(IV) i n selenium t e t r a f l u o r i d e to y i e l d a " s a l t " -potassium hexafluopalladate (IV): (SeF3) 2PdF£ 4- 2KSeF^ > K 2 P d F 6 * 4 S e F 4 An X-ray powder photograph of the product can be wholly indexed on the basis of a t r i g o n a l unit c e l l . When potassium hexafluopalladate (IV) was prepared i n bromine t r i f l u o r i d e P l by the method of Sharpe i t yielded an X-ray powder photo-graph which contained the l i n e s of the t r i g o n a l modification along with strong l i n e s which were associated with another phase. This i s i n agreement with Sharpe*s observation that some bromine t r i f l u o r i d e was solvated and could not be removed from the compound. Potassium hexafluopalladate (IV) o was f i r s t prepared by Hoppe and Klemm i n a hexagonal modification, a = 5.75, c = 9.51 A° , by f l u o r i n a t i o n of the corresponding chloride at 270° . 13 Compounds of the type A 2MF£, where A s K, Rb, Cs ' and M • Pd, Pt, Ge are found i n three e n e r g e t i c a l l y similar c r y s t a l structures which are: ( i ) the t r i g o n a l or K 2GeF£ type structure ( i i ) the hexagonal or K 2MnF£ type structure ( i i i ) the cubic or K 2SiF£ type structure Much ambiguity exists i n the previous c l a s s i f i c a t i o n of these structures. Compounds which have been used to t y p i f y a structure have been found to exist i n more than one modification. This i s further complicated by the frequent d e s c r i p t i o n of the t r i g o n a l K 2GeF^ type structure as hexa-gonal. The only unambiguous system of c l a s s i f i c a t i o n would be to refer d i r e c t l y to the space group concerned. This i s not p r a c t i c a l , however, because i n many cases s u f f i c i e n t information i s not a v a i l a b l e . Only a t r i g o n a l modification of potassium hexa-f l u o p l a t i n a t e (IV) J has been reported. The s t r u c t u r a l data for t h i s and the i s o s t r u c t u r a l potassium hexafluo-24 germanate are compared i n Table 3 with the new modification of the hexafluopalladate. The s i m i l a r i t y of the PtF^~ and PdF^* units i n shape and size i s s t r i k i n g . The presumed electronic con-fi g u r a t i o n s i n the P t * 4 and Pd* 4 ions (5<3g6 and 4d^ 6respect-i v e l y ) i s also very s i m i l a r . In view of t h i s , the difference i n l a b i l i t y of the complex ions i s s u r p r i s i n g . In water, 14 TABLE 3 Trigonal Modifications of Potassium Salts of Hexafluo-, Quadripositive Ge, Pd and Pt a c c/a X f Z f Z^ M-F Reference K 2GeF 6 5.62A° 4.65A° .827 0.148 0.220 0 . 7 0 0 1.77A° 24 K0PdF/r 5 . 7 2 A ° 4 . 6 7 A 0 . 8 l 6 0 . 1 5 0.24 0.70 1.86A° Present d ° Work K 2 P t F 6 5.76A" 4.64A° . 8 0 6 0 . 1 5 0 . 2 5 0.74 1.91A° 23 Atomic positions of space group are 1 Pd (Pt, Ge) i n 0, 0, 0; 2 K i n 1/3 , 2/ 3 , Z; 2 / 3 , 1/3, Z ; 6 F i n X, 2X, Z; X, X, Z; 2X, X, Z; X, 2X, Z; X, X, Z; 2X, X, Z. 15 hexafluopalladate (IV) i s i n s t a n t l y hydrolyzed to the dioxide and hydro gen f l u o r i d e . The hydrolysis of hexafluo-platinate i s extremely slow, and hexafluoplatinate may even be r e c r y s t a l l i z e d from water. Bromine t r i f l u o r i d e does not appear to be capable of s t a b i l i z i n g quadripositive palladium, laftien a sample of fluoselenonium hexafluopalladate (IV) was reacted with bromine t r i f l u o r i d e , i t dissolved to give a solution of t e r p o s i t i v e palladium. The reaction can probably be repre-sented by the equation: 2 (SeF 3) 2PdF 6 «• 3BrF^—> 4SeF 4 2 BrF^, PdF^ * BrF^ An al t e r n a t i v e to the formation of bromine pentafluoride would be the formation of selenium hexafluoride. Since quadripositive selenium does not appear to reduce quadri-p o s i t i v e palladium below 150° , i t i s reasonable to suggest that bromine t r i f l u o r i d e i s the reducing agent. Bromine t r i f l u o r i d e has been observed to act as a reducing agent, i n other reactions with t r a n s i t i o n metals i n high oxidation 25 states, by other workers. J The reaction goes to completion because selenium t e t r a f l u o r i d e , which s t a b i l i z e s quadri-p o s i t i v e palladium, has a b o i l i n g point appreciably lower than the b o i l i n g point of bromine t r i f l u o r i d e and Is, therefore, driven out of the sol u t i o n . A possible explan-ation for the above reaction i s that bromine t r i f l u o r i d e does not act as a f l u o r i d e ion donor i n t h i s system and so cannot s t a b i l i z e quadripositive palladium as hexaf luo p a l l a -date (IV). The linkage may take place through a f l u o r i n e 16 bridge. Fluoselenonium hexafluopalladate (IV) decomposes at 1 5 5 ° to palladium difluoride. The palladium appears to be reduced directly from the quadripositive state to the dispositive state according to the reaction (SeF3) 2PdF£ > PdF2 *• SeF$ * SeF4 A terpositive palladium compound was not detected. The reduction did not depend on an atmosphere of selenium tetrafluoride being present since the difluoride was formed even when the decomposition was carried out in a vacuum. A further attempt was made to prepare a selenium tetrafluoride derivative of terpositive palladium by reacting palladium trifluoride with selenium tetrafluoride. At room temperature there was no apparent reaction. At the boiling point of selenium tetrafluoride the palladium trifluoride was reduced to pure palladium difluoride 2 PdF^ * SeF4 ->> 2 PdF2 «• SeF^ The selenium tetrafluoride was removed in a vacuum just above room temperature and there was no sign of a selenium tetrafluoride derivative of palladium di-fluoride. It appears that the intermediate observed by Bartlett and Hepworth , and assumed to be a 1 : 1 selenium tetrafluoride - palladium trifluoride adduct, was actually a mixture of palladium difluoride and fluoselenonium 17 hexafluopalladate (17). Selenium t e t r a f l u o r i d e reduces palladium t r i -f l u o r i d e at a much lower temperature than previously-reported. It possesses properties which may make i t very useful as a reducing agent i n the preparation of metal f l u o r i d e s . It i s one of the few availa b l e reducing agents for f l u o r i d e s i w k i c h i s a l i q u i d at room temperature..The r e l a t i v e l y high b o i l i n g point (10(?) i s an added convenience. Selenium t e t r a f l u o r i d e i s also one of the best i o n i z i n g solvents f o r f l u o r i d e s and as observed e a r l i e r the f l u o r i d e ion donor properties are e f f e c t i v e i n the s t a b i l i z a t i o n of cert a i n oxidation states of t r a n s i t i o n metals. The non oxid i z i n g properties of t h i s solvent are also of value i n the preparation of derivatives of elements i n low and e a s i l y oxidized oxidation states. Caesium t r i f l u o p a l l a d a t e (II) has been prepared by B a r t l e t t ^ by reacting caesium f l u o r i d e and palladium d i f l u o r l d e i n selenium t e t r a f l u o r i d e solution. When potas-sium f l u o r i d e i s substituted for the caesium f l u o r i d e no reaction occurs. Caesium f l u o r i d e would be expected to be a stronger base than potassium f l u o r i d e i n a f l u o r i d e solvent system and caesium f l u o r i d e i s much more soluble than potas-sium f l u o r i d e i n f l u o r i d e solvents. An attempt was made to prepare a complex f l u o r i d e of t e r p o s i t i v e palladium by reacting palladium t r i f l u o r i d e 18 and potassium f l u o r i d e i n selenium t e t r a f l u o r i d e . The p o s s i b i l i t y existed that a strong base such as potassium f l u o r i d e might s t a b i l i z e t e r p o s i t i v e palladium i n selenium t e t r a f l u o r i d e as i t s t a b i l i z e s quadripositive palladium i n the same solvent. The reaction between equimolar quantities of potassium f l u o r i d e and palladium t r i f l u o r i d e i n selenium t e t r a f l u o r i d e yielded a mixture of palladium d i f l u o r l d e , potassium hexafluopalladate (IV) and some other phase which gave an X-ray pattern of very d i f f u s e l i n e s . The reaction between two molar parts of potassium f l u o r i d e and one molar part of palladium t r i f l u o r i d e did not y i e l d palladium d i f l u o r l d e . The major phase was a magenta s o l i d which gave an X-ray powder photograph pattern of d i f f u s e l i n e s i d e n t i c a l to that observed i n the product from the 1:1 mixture. The magenta s o l i d could not be obtained free of impurities. The main impurities appeared to be potassium pentafluoselenate (IV) and potassium hexa-f l u o s i l i c a t e (IV). The s o l i d Impure product had zero magnetic moment, strongly i n d i c a t i n g that the product was a d i p o s i t i v e complex of palladium, since any t e r p o s i t i v e complex would have at least one unpaired electron spin, lalhen the magenta s o l i d was treated with hydrochloric acid, yellow potassium tetrachloro-palladate (II) was formed. 19 Two p o s s i b i l i t i e s exist for the composition of the magenta product. These are KPdF. and K PdF„. If the 3 2 4 reaction were a straight foreward reduction and complexing of the palladium, the decision would be simple. A 1 :1 molar r a t i o of reactents would react i n one of two ways 2 KF * 2PdF 3 * SeF 4 > PdF 2 * K 2PdF 4 * SeF^ 2 KF 4- 2PdF 3 + SeF 4 > 2KPdF 3 f SeF£ i n the same manner, a 2 :1 molar r a t i o would react i n one of two ways 4 KF * 2PdF 3 «• SeF 4 > 2K 2PdF 4 + SeF 6 4 KF * 2PdF 3 * 3 S e F 4 > 2KPdF 3 * 2KSeF^ «• SeF 6 Neither a 1 :1 nor 2:1 r a t i o resulted i n a pure product. PdF 2 was present i n the 1:1 reaction, but large quantities of KSeFjj were produced i n the 2 :1 reaction. The presence of potassium hexafluopalladate (IV) i n the product was also unusual. To explain the r e s u l t s , i t i s necessary to postulate the formation of an intermediate complex of t e r p o s i t i v e palladium of formula K 2PdF^. The reaction then proceeds by reduction of the complex or disproportionation. Both pro-cesses probably occur. PdF 3 + 2KF V K 2PdF^ 2K 2PdF^ 3 S e F 4 > -KPdF3 2KSeF^ * SeF^ 2K 2PdF 6 1- SeF 4 y &2mF6 * KPdF 3 KSeF^ 20 In the 1:1 r e a c t i o n , enough potassium f l u o r i d e i s present to complex o n l y h a l f of the p a l l a d i u m t r i f l u o r i d e . The o t h e r h a l f i s v u l n e r a b l e to r e d u c t i o n to p a l l a d i u m d i -f l u o r i d e , which w i l l not r e a c t w i t h potassium f l u o r i d e . The f o r m a t i o n o f the t e r p o s i t i v e p a l l a d i u m complex appears to be a r a p i d p r o c e s s , w h i l e the r e d u c t i o n or d i s -p r o p o r t i o n a t i o n o f the complex i s a slower p r o c e s s , the r a t e o f which i s comparable to the r a t e of r e d u c t i o n o f p a l l a d i u m t r i f l u o r i d e by selenium t e t r a f l u o r i d e . The absence o f paramagnetism and the i n d e x i n g o f the X-ray powder photograph l i n e s on the b a s i s o f a t e t r a g o n a l u n i t c e l l , a s 4 . 3 6 , c = 3 .46 - . 0 3 A , u n f o r t u n -a t e l y g i v e no d e f i n i t e i n d i c a t i o n s of the composition o f the d i p o s i t i v e complex. For KPdF^ a P e r o v s k i t e type s t r u c t u r e would be expected and f o r K 2 P d F 4 a S p i n e l type s t r u c t u r e would be expected. With a l l e l e c t r o n s p i n s p a i r e d , a d i s -t o r t i o n would be expected i n both s t r u c t u r e s which could r e s u l t i n a t e t r a g o n a l d i s t o r t i o n o f the u n i t c e l l . When the bromine t r i f l u o r i d e , a u r i c f l u o r i d e complex i s t r e a t e d w i t h selenium t e t r a f l u o r i d e , the bromine t r i f l u o r i d e i s d i s p l a c e d by the selenium t e t r a f l u o r i d e to form an orange-yellow s o l i d which i s a 1:1 selenium t e t r a -f l u o r i d e adduct o f a u r i c f l u o r i d e . AuF^jBrF^ «• S e F 4 > A u F 3 , S e F 4 *• BrF^ 21 o The complex i s diamagnetic and i s stable up to 200 . The high thermal s t a b i l i t y of the compound contrasts with the bromine t r i f l u o r i d e adduct which i s decomposed to bromine t r i f l u o r i d e and auric f l u o r i d e at 180 . This i s an ind i c a t i o n that there i s a difference i n the bonding. The selenium t e t r a f l u o r i d e complex Is probably a fluoselenonium s a l t . Terpositive gold i s pseudoisoelectronic with d i p o s i t i v e palladium, but whereas the l a t t e r exhibits para-magnetism, t e r p o s i t i v e gold i s diamagnetic. The diamag-netism could be the r e s u l t of a square planar or tetragonal s p l i t t i n g of the 5d o r b i t a l s , i n which one o r b i t a l (d xa_ y4> i s of much higher energy than any of the others. The electron configuration would be Au* 3 d x z d y z d z 2 d x y dx 2-y z A study of the pyrolysis products of the complex using X-ray powder techniques may reveal a lower f l u o r i d e . To date, only the t e r p o s i t i v e valence state has been observed i n f l u o r i d e s . It i s also probable that a higher f l u o r i d e w i l l be made i n the future. CONCLUSION The terpositive state of palladium is unstable in selenium tetrafluoride. Selenium tetrafluoride acts as a reducing agent to reduce palladium trifluoride to palladium difluorlde. In the presence of a fluorinating agent, selenium tetrafluoride stabilizes the quadripositive state of palladium. Strong evidence exists which shows that selenium tetrafluoride acts as a fluoride ion donor, resulting in the SeF^*" ion and such ions as hexafluo-palladate (IV) and tetrafluoaurate (III). The hexafluopalladate (IV) ion very closely resembles the hexafluoplatinate (IV) ion in size, shape, and M-F distances. Despite this similarity and the similar electron configurations of the metal ions, hydrolysis of the two complex ions proceeds at vastly differing rates. This behavior cannot be accounted for in terms of structure and must be related to some other property of the ions. The slow hydrolysis of the hexafluoplatinate (IV) is character-i s t i c of an SN.^  mechanism, the slow unimolecular dissociation into a five coordinate ion and a fluoride ion being the rate determining step. It is probable tha$ the hydrolysis of the hexafluopalladate (IV) ion is also a f i r s t order process, the unimolecular dissociation being much more rapid than in the platinum case. An SN 2 mechanism is unlikely to apply in either case since the required seven coordinate inter-mediate would necessitate the ava i l a b i l i t y of a vacant bonding 23 TABLE 4 Fluorides of Palladium 2 4 o r b i t a l . The electronic configurations of the platinum and palladium ions i n these complexes do not provide for such an o r b i t a l . Few complex f l u o r i d e derivatives of d i - and t e r p o s i t i v e palladium have been prepared, but i t i s probable that other compounds of t h i s type w i l l be prepared by the use of other f l u o r i d e solvents, such as f l u o s u l f o n i c acid or iodine pentafluoride. Magnetic s u s c e p t i b i l i t y studies and c r y s t a l structure determinations of such complex lower f l u o r i d e s would prove very i n t e r e s t i n g . EXPERIMENTAL I General Techniques a) Glassware Most v o l a t i l e f l u o r i d e s attack Pyrex glass. The attack i s often due to the presence of hydrogen f l u o r i d e which i s sometimes formed by the hydrolysis of the f l u o r i d e by the water which i s invariably present on the surface of the glass. The hydrolysis i s autocatalytic i n nature, and i n theory, one molecule of water could completely decompose a sample of f l u o r i d e and badly attack the glass container. MF n «• H 20 >> M0F n_ 2 * 2HF 4HF f S i 0 2 > S i F 4 * 2H20 MF n * H2O y etc. Because of t h i s , steps must be taken to thoroughly dry a l l apparatus. This i s best done by "flaming out" under vacuum. It i s also necessary to insure that the f l u o r i d e s to be handled are free from hydrogen f l u o r i d e . Since the reactive v o l a t i l e f l u o r i d e s attack hydrocarbon vacuum tap greases, fluorocarbon grease must be used on a l l ground glass surfaces. Even fluorocarbon grease i s attacked to some extent by such reagents as bromine t r i f l u o r i d e and selenium t e t r a f l u o r i d e . In t h i s work, therefore, the use of glass stopcocks and ground glass i j o i n t s has been kept to a minimum. 26 S i l i c a i s more resist a n t than Pyrex to attack by hydrogen f l u o r i d e and i t would be advantageous to use an apparatus constructed e n t i r e l y i n s i l i c a but the added inconvenience entailed i n i t s construction outweighs the advantage. S i l i c a reaction bulbs which were connected to the Pyrex systems by means of graded seals were used. These seals stood up very well to thermal shock but fractured when subjected to mechanical s t r a i n s . b) X-Ray Photographs X-ray powder photographs of the s o l i d products were taken using a 14.32 cm. General E l e c t r i c camera. The r a d i a t i o n was f i l t e r e d using n i c k e l f o i l (.089 mm.) to remove r a d i a t i o n . The X-ray tube was operated at 40 k i l o v o l t s and 20 milliamps and an average exposure under these conditions was 12 hours. The dry-box technique was employed i n preparing samples. A portion of the substance was f i n e l y powdered and charged into t h i n walled c a p i l l a r i e s (0 .5 mm. diameter) of Pyrex glass or s i l i c a . The c a p i l l a r i e s were quickly sealed using a small, very hot flame. c) Magnetic Measurements Magnetic s u s c e p t i b i l i t i e s of the s o l i d s were obtained using a Gouy balance. A Varian #4004 magnet with 2 inch tapered pole faces provided a magnetic f i e l d of approximately 15 kilogauss with a c o i l current of 2 amperes. For the determination of magnetic s u s c e p t i b i l i t i e s 2 7 by the Gouy method, the specimen tube i s so placed that the bottom of the sample i s i n the center of the homo-geneous portion of the magnetic f i e l d . Also, the length of the sample i s such that i t s top i s i n a region of n e g l i g i b l e f i e l d . The molar s u s c e p t i b i l i t y i s given by the expression X m sAW.M.C W where X m - molar s u s c e p t i b i l i t y of sample W • weight of sample A W B change i n weight of sample on a p p l i c a t i o n of f i e l d M B molecular weight of sample C s the apparatus constant The apparatus constant can be determined accurately by using standard substances of known s u s c e p t i b i l i t y . Two standards are commonly used. They are - 6 Benzene X g - Xrn^ = - 0 . 7 0 2 x 1 0 " c.g.s. ( 2 7 ) HgCo (SCN) 4 X* » Xrn^ B 16.44 x i o " 6 c.g.s. ( 2 8 ) where X^ i s the gram s u s c e p t i b i l i t y . A l l s u s c e p t i b i l i t i e s were measured at room temperature. Some of the magnetic moment samples were made up i n a dry-box i n dry Pyrex glass tubes which were quickly sealed. Since the other material encountered was loose and 2 8 f i n e l y powdered It could be handled i n a closed system. In t h i s preferred procedure, a side-arm of the glass tubing used for magnetic moments was sealed on to the reaction bulb prior to the reaction. The reaction bulb was sealed o f f under reduced pressure. Some of the product was then transferred to the arm which was sealed o f f . II A n a l y t i c a l Methods The composition of s o l i d products encountered i n the reactions which were studied was determined by chemical analysis. Standard procedures were used. X-ray powder photography was used to i d e n t i f y compounds and detect mixtures. A l i b r a r y of X-ray powder photographs of known substances was b u i l t up to f a c i l i t a t e t h i s , a) Fluorine The main problem i n an analysis for f l u o r i n e i s interference from other ions. This i s overcome by f i r s t separating the f l u o r i d e by d i s t i l l a t i o n as hydrofluoric acid. The f l u o r i d e can be precipitated as t r i p h e n y l t i n f l u o r i d e , calcium f l u o r i d e , or lead c h l o r o f l u o r i d e . The lead chlorofluoride method was used i n t h i s work because of i t s s i m p l i c i t y and the favourable m u l t i p l i c a t i o n f a c t o r . Volumetric determination of f l u o r i d e by t i t r a t i o n with thorium n i t r a t e was not favoured because of the subtle colour change at the end point with the consequent need of much practise to obtain r e l i a b l e r e s u l t s . 29 The f l u o r i n e compound was weighed by difference into a s l i g h t l y a l k a l i n e solution (50 ml). This solution was placed i n a d i s t i l l a t i o n f l a s k f i t t e d with a side arm and dropping funnel, a thermometer and a condenser. About 29 25 ml. of concentrated s u l f u r i c acid or 70% perchloric acid were added. The solution was boiled and the temperature of o o the b o i l i n g mixture was maintained between 130 C. and 135 C. by adding water dropwise as the d i s t i l l a t i o n proceeded. Approximately 250 ml. of the d i s t i l l a t e , (which presumably contained the f l u o r i d e as hydrofluoric and h e x a f l u o s i l i c i c acids) was c o l l e c t e d . Perchloric acid was found to give more consistent r e s u l t s than s u l f u r i c a c i d . It i s believed that small amounts of the acid sometimes splash into the condenser and are washed into the d i s t i l l a t e . In the p r e c i p i t a t i o n of lead chlorofluoride, lead sulphate w i l l also p r e c i p i t a t e whereas lead perchlorate i s soluble. To p r e c i p i t a t e the f l u o r i d e , the d i s t i l l a t e was neutralized and made f a i n t l y a l k a l i n e with sodium hydroxide, using bromphenol blue as an i n d i c a t o r . Concentrated hydro-c h l o r i c acid (1 ml.) was added, the solution heated to 80°C. and lead .nitrate (5 gm.) added. The solution was then heated almost to the b o i l i n g point and hydrated sodium acetate (5 gm) was added. The s o l u t i o n was kept at the b o i l i n g point for one hour and was allowed to cool overnight. The p r e c i p i t a t e was f i l t e r e d on a sintered glass c r u c i b l e , washed with 30 o saturated lead chlorofluoride solution and dried at 140 -150°C. for two hours, b) Palladium A s o l i d weighed sample was placed i n a beaker and dissolved i n concentrated hydrochloric a c i d . The solution was evaporated several times to near dryness with hydrochloric acid to remove a l l traces of f l u o r i d e , which would i n t e r f e r e with most quantitative analyses. The evaporation product and 26 ml. of concentrated hydrochloric acid were made up to 250 ml. Two d i f f e r e n t methods were used to determine palladium. In the f i r s t method, aliquots of palladium solution or weighed samples of compounds were placed i n an a l k a l i n e carbonate solution. The hydrated oxide p r e c i p i t a t e d . It was f i l t e r e d on a quantitative paper and was ignited to palladium metal. It was heated to constant weight i n a stream of hydrogen. The most r e l i a b l e a n a l y t i c a l method was to pre-c i p i t a t e the palladium from a hot d i l u t e s o l u t i o n as the dimethyl glyoxime complex. A minimum volume of one percent dimethylglyoxime i n ethanol was used. The yellow complex was f i l t e r e d on a sintered glass c r u c i b l e , washed with hot water, dried at 155°C, and weighed. 31 c) Selenium Selenium was precipitated as the element by passing sulfur dioxide into a strong hydrochloric acid solution. It was f i l t e r e d on a sintered glass c r u c i b l e and was washed with alcohol and ether and then dried at 110°. d) Gold and Selenium Gold and selenium are precipitated simultaneously by almost any reducing agent. Separation can be accomplished by f i l t e r i n g the gold-selenium mixture on a sintered glass c r u c i b l e , weighing, and then di s s o l v i n g the selenium i n n i t r i c acid of s p e c i f i c gravity 1 .25 . e) Bromine Bromine was precipitated from acid s o l u t i o n as the s i l v e r s a l t . I l l Reactants a) Fluorine Supply Fluorine was supplied i n a s t e e l gas cylinder con-taining six pounds of f l u o r i n e at 400 p . s . i . by the A l l i e d Chemical Company. The cylinder was i n s t a l l e d i n an upright p o s i t i o n i n a walk-in fume hood and was shielded with a brick safety screen. Reduction of the gas pressure was achieved with two s t a i n l e s s s t e e l needle valves (Hoke type 316 No. Y 343H) i n s e r i e s . The high pressure gas l i n e was 3 2 constructed from ^ inch stain l e s s s t e e l pressure tube, threaded and s i l v e r soldered at a l l j o i n t s . On the low pressure side of the needle valves \ inch copper tubing connected with brass compression f i t t i n g s was used. In the low pressure l i n e , d i r e c t l y after the pressure reducing needle valves, was a blow-off con-s i s t i n g of a s i l v e r soldered T-joint of \ inch copper tubing with i t s outlet dipping into a test-tube containing "Fluorolube o i l " (Hooker Chemical Co., FS-5.) The blow-o f f was both a safety device and a crude flow meter. The flow-rate was measured by counting bubbles emerging at the blow-off when the needle valve (Hoke No. 431) at the exit of the low pressure l i n e was closed. To permit d i l u t i o n of the f l u o r i n e , with dry nitrogen, a brass T-joint was provided i n the l i n e . A brass needle valve (Hoke No. 431) controlled the nitrogen i n l e t . A copper tube containing sodium f l u o r i d e p e l l e t s was Inter-posed between the blow-off and the nitrogen i n l e t . The sodium f l u o r i d e removed hydrogen f l u o r i d e present i n the f l u o r i n e gas. Diluted f l u o r i n e passed from the low pressure l i n e through a brass needle valve (Hoke No. 431) into the reaction systems which were connected to the l i n e either with brass compression f i t t i n g s or with t e f l o n tubing sealed with Kel-F fluorocarbon grease. 33 b) Bromine t r i f l u o r i d e Bromine t r i f l u o r i d e was supplied, i n f i f t e e n pound st a i n l e s s s t e e l cylinders containing f i v e pounds of the l i q u i d , by The Matheson Company Inc. A needle valve (Matheson No. 55-670) was used i n series with the valve on the c y l i n d e r . The second valve was connected to pieces of apparatus by means of a short length of t e f l o n tubing of appropriate diameter sealed with "Kel-F" fluorocarbon grease. The bromine t r i f l u o r i d e was used i n portions of 5 mis, to 15 mis. from break-seal b o t t l e s . It was trans-ferred from the cylinder to i n d i v i d u a l bottles by vacuum d i s t i l l a t i o n i n an a l l - g l a s s apparatus. This consisted of a manifold with four to six break-seal bottles with a pair of traps at each end. Both ends of the glass apparatus were open. One end was attached to the cylinder and the other to a vacuum pump. Bromine t r i f l u o r i d e was d i s t i l l e d into the traps nearer the c y l i n d e r . When s u f f i c i e n t bromine t r i f l u o r i d e had been transferred, the valves on the cylinder were closed and the glass tubing was drawn down and sealed with a flame near the t e f l o n connection. A l i q u i d nitrogen trap was placed around one of the traps at the other end -of the apparatus and the l e v e l of nitrogen kept as high as possible. The bromine t r i f l u o r i d e was allowed to d i s t i l and a small quantity of i t quickly plugged the entrance to 34 the trap and made an e f f e c t i v e vacuum s e a l . Liquid nitrogen baths were placed around each of the breakseal bottles and bromine t r i f l u o r i d e d i s t i l l e d into them. If the transference of bromine t r i f l u o r i d e slowed down because of loss of vacuum, usually a r i s i n g from i n t e r a c t i o n of bromine t r i -f l u o r i d e with the glass to form oxygen and s i l i c o n t e t r a -f l u o r i d e , the plug of bromine t r i f l u o r i d e could e a s i l y be melted and the vacuum re-established, the seal being renewed as before. The breakseal bottles were drawn o f f and stored i n dry-ice i n a large Dewar f l a s k . c) Palladium Diiodide and Dibromide Palladium dii o d i d e i s prepared by adding the stoichiometric quantity of iodide (as potassium iodide solution) to a solution of bivalent palladium. The i n -soluble palladium d i i o d i d e i s f i l t e r e d o f f , washed with water and alcohol, and d r i e d . Palladium dibromide was prepared by evaporating an aqua regia solution of palladium with concentrated hydro-bromic acid or by d i s s o l v i n g palladium i n hydrobromic acid containing elemental bromine. The bromide was recovered after evaporation to dryness. d) Gold Gold metal was used i n the form of a very f i n e powder. 35 e) Potassium Fluoride Anhydrous potassium f l u o r i d e was prepared by the reaction of AR grade potassium carbonate with AR grade hydrofluoric a c i d . The product, which i s the hydrate, was then heated to approximately 800 C i n a platinum c r u c i b l e to obtain the unsolvated s a l t . It was allowed to cool i n a desiccator and was then transferred to a dry-box to be powdered and was stored In a desicator. IV The Preparation of Selenium Tetrafluoride Selenium t e t r a f l u o r i d e was prepared by the method described by Aynsley, Peacock and Robinson,"^0 A Pyrex glass apparatus as shown i n F i g . 1 was used. Selenium p e l l e t s (100 gms.) were placed i n the reaction bulb between traps 1 and 2 . The selenium was sublimed under vacuum on to the walls of the reaction vessel. Dry nitrogen was allowed to enter the system at A and a slow stream of dry nitrogen was passed from A to D. Dry-ice-alcohol baths, or pre-fera b l y l i q u i d oxygen baths, were placed around a l l traps. Liquid nitrogen i s not used as a r e f r i g e r a n t since i t con-denses f l u o r i n e . An i c e bath was placed around the reaction v e s s e l . Fluorine was introduced into the nitrogen stream and i t reacted with the cold selenium to give selenium t e t r a -f l u o r i d e , which collected as a l i q u i d i n the bottom of the ve s s e l . When most of the selenium had been consumed, the •oo CO c o w « Q: w o «0 fC < 36 flu o r i n e stream was cut o f f and the system was purged of f l u o r i n e with dry nitrogen. The system was sealed at B and then evacuated through D. The selenium t e t r a f l u o r i d e was d i s t i l l e d into traps 2 and 3, then the system was sealed at C. A l i q u i d nitrogen bath was placed around each of the break-seal bottles and one as high up on trap 4 as possible. The selenium t e t r a f l u o r i d e i n traps 2 and 3 was allowed to warm up} Some selenium t e t r a f l u o r i d e immediately d i s t i l l e d into the opening of trap 4 , where i t condensed and formed a plug. The remainder d i s t i l l e d into the break-seal b o t t l e s . When the transference was complete the break-seal bottles were drawn o f f under vacuum and stored u n t i l needed i n "dry-i c e . " There i s a d e f i n i t e advantage to using a plug of the reactant to seal the system during a d i s t i l l a t i o n . If the vacuum i n the system i s l o s t through the formation of v o l a t i l e products, such as oxygen, by attack of the reactant on the glass, i t i s a simple matter to open the plug and re-evacuate the system. Opening of the system after a d i s t i l l a t i o n i s also simplified. V The Preparation of Palladium T r i f l u o r i d e and Its Adduct  With Bromine T r i f l u o r i d e In order to save time and conserve materials, two or more related preparations were often done i n a single apparatus. Palladium t r i f l u o r i d e and i t s adduct with bromine 37 t r i f l u o r i d e were simultaneously prepared after the method 4 described by Sharpe. An apparatus was constructed of Pyrex glass and consisted of a manifold connected to a l i n e of two traps which were i n turn connected to a vacuum pump. The manifold had a side tube containing n i c k e l b a l l s . Attached to the manifold were a break-seal bo t t l e of selenium t e t r a f l u o r i d e and two bulbs, each containing about three grams of palladium dibromide. The apparatus was evacuated and the bromine t r i -f l u o r i d e break-seal was opened. By placing a l i q u i d nitrogen trap as high as possible on one of the traps, a plug of bromine t r i f l u o r i d e was made to form i n the narrow neck of the trap. The bromine t r i f l u o r i d e was then d i s t i l l e d on to both of the palladium dibromide samples. When the trans-ference was complete, the plug of bromine t r i f l u o r i d e was removed and the two bulbs were allowed to warm slowly to room temperature at atmospheric pressure. The vigorous reaction between bromine t r i f l u o r i d e and palladium dibromide was controlled by occasionally cooling the bulbs with l i q u i d nitrogen. Large quantities of bromine were formed i n the course of the reaction. After the palladium dibromide was completely dissolved, the bromine and excess bromine t r i -f l u o r i d e were pumped into the two traps. When a l l of the v o l a t i l e substances had been removed, a dark brown s o l i d remained. One of the reaction bulbs was sealed o f f at t h i s 38 time to obtain a sample of the complex f l u o r i d e . This was the bromine t r i f l u o r i d e adduct of palladium t r i f l u o r i d e . A sample was taken for analysis. Found: Br, 2 5 . 3 $ ; P, 3 9 . 0 $ ; Pd, 3 3 . 9 $ . Calculated for BrF^, PdF 3: Br, 2 6 . 5 $ ; F, 3 8 . 0 $ ; Pd, 35 .5$ It was paramagnetic^ / W eff = 2.24 B.M. at 20°C. The complex f l u o r i d e i n the remaining bulb was heated to 220°C. i n a vacuum to remove a l l of the bromine t r i f l u o r i d e . The residue was black palladium t r i f l u o r i d e . VI The Preparation of Fluoselenonium Hexafluopalladate (IV) For the preparation of fluoselenonium hexafluo-palladate (IV) an apparatus very s i m i l i a r to that shown i n F i g . 2 was used. Only one reaction bulb was used, however. The apparatus consisted of two traps connected to a manifold with three branches: one branch to the reaction bulb, one branch to a bromine t r i f l u o r i d e break-seal bottle and the remaining branch to a selenium t e t r a f l u o r i d e break-seal b o t t l e . Palladium dibromide (3 gm.), contained i n the bulb was converted to the bromine t r i f l u o r i d e - palladium t r i f l u o r i d e adduct i n the manner described above. Selenium t e t r a f l u o r i d e was added to t h i s adduct and the mixture was refluxed for two hours. Copious quantities of bromine were evolved. Removal of the v o l a t i l e substances at 100°C. under vacuum l e f t a yellow product, which was fluoselenonium 39 hexaf luopalladate (IV). Found F, 45.6$; Pd, 21.9$; Se, 31.3$ ( S e F 3 ) 2 P d F 6 requires F, 46.3$; Pd, 21.6$; Se, 32 .1$ -6 The s o l i d was diamagnetic, X g = -.36 x 10 c.g.s. u n i t s . VII The Reaction of Fluoselenonium Hexafluopalladate (IV)  with Bromine T r i f l u o r i d e Yellow fluoselenonium hexaf luopalladate dissolved In bromine t r i f l u o r i d e on warming to give a red solu t i o n . The bromine t r i f l u o r i d e was removed under vacuum to leave the paramagnetic bromine t r i f l u o r i d e - palladium t r i f l u o r i d e adduct. ' VIII Reactions of Fluoselenonium Hexafluopalladate (IV) The temperature of decomposition and the thermal decomposition products of fluoselenonium hexaf luopalladate (IV) were studied by keeping samples of the compound at set temperatures for periods of approximately one hour. Decom-position was carried out both under vacuum and at atmospheric pressure. X-ray powder photographs of the products showed decomposition to be complete i n one hour at 1 5 5 ° (atmospheric pressure), the product being palladium d i f l u o r i d e . At 135° (atmospheric pressure) decomposition was slow and incomplete. After 30 minutes a mixture of palladium d i f l u o r i d e and fluoselenonium hexafluopalladate (IV) remained. The complex f l u o r i d e reacted rapi d l y with water, 4 0 r e s u l t i n g i n the p r e c i p i t a t i o n o f a brown s o l i d c o n t a i n i n g p a l l a d i u m and selenium, probably p a l l a d o u s s e l e n a t e . Hydro-c h l o r i c a c i d d i s s o l v e d the hexaf l u o p a l l a d a t e and when t h i s s o l u t i o n was mixed wi t h potassium c h l o r i d e a red p r e c i p i t a t e of potassium h e x a c h l o r o p a l l a d a t e (IV) was formed. IX The P r e p a r a t i o n o f P a l l a d i u m D i f l u o r i d e P a l l a d i u m d i f l u o r l d e was prepared by the r e -d u c t i o n o f p a l l a d i u m t r i f l u o r i d e w i t h selenium t e t r a f l u o r i d e . A s i n g l e Pyrex g l a s s apparatus was used f o r the p r e p a r a t i o n o f p a l l a d i u m t r i f l u o r i d e and i t s subsequent r e d u c t i o n w i t h selenium t e t r a f l u o r i d e . The apparatus c o n s i s t e d o f a. manifold connected to a l i n e o f f o u r t r a p s . To the manifold were attached a bromine t r i f l u o r i d e b r e a k s e a l , a selenium t e t r a f l u o r i d e b r e a k s e a l and a bulb c o n t a i n i n g p a l l a d i u m dibromide ( c i r c a 3g. ) P a l l a d i u m t r i f l u o r i d e was prepared as d e s c r i b e d above. The v o l a t i l e s from t h i s p r e p a r a t i o n were pumped i n t o the two t r a p s f a r t h e s t from the r e a c t i o n b u l b . The two t r a p s were drawn o f f under vacuum a f t e r the selenium t e t r a -f l u o r i d e b r e a k - s e a l had been opened. The selenium t e t r a -f l u o r i d e was d i s t i l l e d onto the p a l l a d i u m t r i f l u o r i d e and the apparatus was then opened to d r y a i r . The r e a c t i o n bulb was warmed and the selenium t e t r a f l u o r i d e r e f l u x e d a t atmospheric p r e s s u r e . The b l a c k p a l l a d i u m t r i f l u o r i d e 41 turned brown. After a two hour r e f l u x , the excess selenium t e t r a f l u o r i d e was vacuum d i s t i l l e d at approximately 50°C. Into the two remaining traps. The residue, which was a l i g h t brown s o l i d was palladium d i f l u o r i d e . Found: F, 26 .1$; Pd, 73 .1$; Calculated for PdF 2 F, 2 6 . 3 $ ; Pd, 7 3 . 7 $ . An X-ray powder photograph showed only the l i n e s character-i s t i c of palladium d i f l u o r i d e . X Potassium Fluoride and Palladium D i f l u o r i d e i n Selenium  Tetrafluoride Palladium d i f l u o r i d e (.440 gm.) and potassium f l u o r i d e ( .353 gm.) were weighed into a breakseal bo t t l e i n a 1:2 molar r a t i o . The tube through which the materials were placed i n the breakseal b o t t l e was immediately sealed. The breakseal b o t t l e containing the palladium d i f l u o r i d e and potassium f l u o r i d e and another breakseal b o t t l e contain-ing about 10 mis. of selenium t e t r a f l u o r i d e were both sealed on to a Pyrex glass manifold which was connected to a vacumm pump through two traps. The apparatus was evacuated. Both breakseals were then broken and the selenium t e t r a f l u o r i d e was vacuum d i s t i l l e d on to the palladium d i f l u o r i d e and potassium f l u o r i d e mixture with the system sealed by a plug of selenium t e t r a -f l u o r i d e i n the neck of one of the traps. After the transfer of the selenium t e t r a f l u o r i d e , the plug was removed and 42 dry a i r was admitted into the apparatus. The mixture was warmed and refluxed for four hours, after which the selenium t e t r a f l u o r i d e was removed into the t\m traps. The residue was dried i n a vacuum at approximately 80°C. The product was a mixture of a white and a very dark or black s o l i d . It was paramagnetic. An X-ray powder photograph showed i t to be a mixture of palladium d i f l u o r i d e and potassium pent af luo selenate CEV) . XI Potassium Fluoride and Palladium T r i f l u o r i d e i n Selenium  Tetrafluoride a) In Molar Ratio 2:1 The preceding reaction was repeated using potassium f l u o r i d e (.348 gm.) and palladium t r i f l u o r i d e (.490 gm.) i n a 2:1 molar r a t i o . On warming the reaction mixture, a black suspension was formed. The color changed on re f l u x i n g and after one hour was purple. Two phases appeared to be present: a dense purple s o l i d which sedimented quickly and a white s o l i d which settled more slowly i n admixture with some of the purple s o l i d . The selenium t e t r a f l u o r i d e was removed slowly under vacuum and the natural separation of the phases was maintained. The residue was dried under vacuum at approximately 80°. Small quantities of the two phases were separated mechanically i n a dry-box. X-ray powder photographs of these two samples were taken. A mixture of the two phases was found to have zero magnetic 43 TABLE 5 X-Ray Data for a Potassium Salt of Fluopalladate (II) (CuK^ radiation) A 2 Possible doublet Possible doublet lobs Obs. Calc. h k l W 0 .0526 0 .0530 100 M 0 .0835 0 .0835 001 V.S. 0.1071 0 .1060 110 M 0.1403 0.1365 101 V.W. 0.1840 0 .1895 111 ¥ 0 .2699 0 .2650 210 W 0.2854 0 .2955 201 M 0.3420 0.3485 211 V.W. 0.3901 0.3870 102 v . w . 0.4244 0.4240 0.4400 220 112 V.W. 0 .5109 0 .5075 221 v . v . w . 0 .5586 0 .5605 301 v.w. 0.6785 0.6890 320 v.w. 0.9518 0.9540 0.9560 330 411 V.S. > S.y M.S. y M. >^ M.W. y W. y V.W. ^ V.V.W. 44 moment. The dense purple phase gave a powder photograph consisting of a series of blurred l i n e s , i n d i c a t i v e of poor c r y s t a l l i n i t y ( i . e . small p a r t i c l e s i z e ) . The poor qu a l i t y of the photographs has made unambiguous indexing of the l i n e s impossible, but they are consistant with a tetragonal unit c e l l : a = 4.36, c = 3.4-6 - .03A. The calculated and found values for 1 / d 2 are given i n Table 5. The pink phase contained strong l i n e s due to potassium pentafluoselenate (IV) and also a pattern character-i s t i c of potassium hexafluosicicate (IV). Lines due to the t r i g o n a l form of potassium hexafluopalladate (IV) were also observed. b) In Molar Ratio 1:1 The above reaction was carried out using a 1:1 molar r a t i o of palladium t r i f l u o r i d e and potassium f l u o r i d e . An X-ray powder photograph of the product showed palladium d i f l u o r i d e , potassium h e x a f l u o s i l i c a t e and the series of blurred l i n e s c h a r a c t e r i s t i c of the dense purple-red phase described above. XII The Preparation of Potassium Hexafluopalladate (IV) An apparatus was constructed as shown i n F i g . 2. Potassium bromide (1.688 g.) and palladium dibromide (1.892g.) were accurately weighed i n a 2:1 molar r a t i o into separate bulbs. The bulbs were s i l i c a and were joined to the Pyrex 4 5 system through graded seals. After the system was evacuated the bromine t r i f l u o r i d e breakseal was opened. Liquid nitrogen baths were placed on the two reaction bulbs. A l i q u i d nitrogen bath was placed on the l e f t hand trap with the nitrogen l e v e l as high as possible. Bromine t r i -f l u o r i d e condensed i n the tube above the trap and formed a plug. The remaining bromine t r i f l u o r i d e d i s t i l l e d into the two reaction bulbs. The plug was then removed and dry ai r was allowed into the system. The bromine t r i f l u o r i d e was allowed to melt, and a reaction took place i n each bulb. Both reactions liberated copious quantities of bromine: 3KBr r 4BrF 3 y 3KBrF 4 • 2Br 2 2PdBr 2 «• 4BrF^ »2PdF^, BrF^ • 3Br 2 Both solutions were refluxed for a few minutes to insure complete reaction. The bromine and bromine t r i f l u o r i d e were d i s t i l l e d into the two traps. The bulbs were warmed to 10G C. to completely remove the excess bromine t r i -f l u o r i d e . The selenium tetrafluoride breakseal was then opened and a plug of selenium t e t r a f l u o r i d e was formed i n the entrance of the l e f t hand trap. After transference to the two bulbs was complete, the system was again opened to an atmosphere of dry a i r and the selenium t e t r a f l u o r i d e was melted and warmed. The bromine t r i f l u o r i d e i n the potassium tetrafluobromite ( I I I ) was e a s i l y displaced by the selenium 46 t e t r a f l u o r i d e : KBrF, + SeF. • .KSeF^ + BrF 0 - 4 4 ^ 5 ' 3 The brown bromine t r i f l u o r i d e complex of palladium t r i -f l u o r i d e assumed the yellow-brown colour of fluoselenonium hexafluopalladate (IV). Bromine was evolved: 6 P d F 3 , B r F 3 «• 12SeF 4 > 6(SeF 3) 2PdF 6 <• B r 2 * 4BrF^ After prolonged r e f l u x i n g (1-2 hours) of the mixtures i n the separate bulbs the apparatus was tipped and the potassium pentafluoselenate (IV) solution was poured into the palladium f l u o r i d e suspension. The yellow-brown colour of the l a t t e r changed to a bright canary yellow. Complete transference of the potassium pentafluoselenate (IV) was achieved by d i s t i l l i n g selenium t e t r a f l u o r i d e into the reaction bulb and tipping the apparatus again. After a reflux of one hour the product appeared homogenous. The v o l a t i l e s were removed under vacuum, at 100°, to leave a f i n e yellow powder. This was potassium hexafluopalladate (IV). Found: Pd, 3 4 . 6 $ ; F, 3 7 . 9 $ ; y i e l d , 2 .166 g. K 2PdF6 requires Pd, 3 5 . 7 $ ; F, 3 8 . 1 $ ; y i e l d , 2 .125 g. A preparation of potassium hexaf luopalladate (IV) was carried out i n bromine t r i f l u o r i d e by the method of 21 Sharpe. A 2:1 molar r a t i o of potassium bromide and palladium dibromide was placed i n a reaction bulb. This mixture was reacted with bromine t r i f l u o r i d e using the same 47 techniques described above. The v o l a t i l e s were removed under vacuum at 100° to leave a yellow powder. X-ray powder photographs showed a complex pattern of l i n e s , among which were the l i n e s c h a r a c t e r i s t i c of the t r i g o n a l mod-i f i c a t i o n of potassium hexafluopalladate (IV). XIII The Cr y s t a l Structure of Potassium Hexafluopalladate (IV) Debye X-ray powder photographs of the potassium hexafluopalladate (IV) were taken as described. Arc lengths on a selected photograph were measured with an accurate scale and vernier. Arc lengths were converted into d spacings and Vd 2 values with the aid of an Alwac I I I E d i g i t a l computer. The pattern was indixed on the basis of a t r i g o n a l unit c e l l , a= 5.7*17 ± .003 A° , c = 4 .667 t .003A0 . For the determination of unit c e l l dimensions the Nelson, R i l e y extrapolation function-^ 1 was employed. The calculated and found values of Vd 2 are given i n Table 6 . Comparison of the unit c e l l dimensions of t r i -gonal potassium hexaf luopallad ate (IV) with those of the t r i g o n a l forms of potassium hexafluoplatinate (IV) and potassium hexafluogermanate (IV) suggested that the symmetry of these three compounds was the same. The space group chosen, therefore, was C 3m - with the following s p e c i a l positions Pd i n (a): ( 0 , 0 , 0)-, 2K i n 2(d): (1/3, 2/3, z ) , ( 2 / 3 , 1/3, 2)5 48 -TABLE 6 Assignment of the X-Ray Reflections of lyPdF^ h k 1 Calc. 0bs t h k 1 Calc. O P S . 100 0.0408 0.0424 313 0.9435 0.9439 001 0.0459 0.0475 322 0.9589 0 .9607 101 0 .0867 0.0889 500 1.0200 1 .0215 110 0.1223 0 .1251 214 1.0202 U l 0.1683 0 .1706 412 1.0404 1.0415 201 0.2091 0.2116 501 1 .0659 1.0687 102 0.2244 0 .2266 403 1 .0659 210 0 .2856 0.2889 330 1.1016 1.1029 112 0 .3060 0 .3092 331 1.1475 1.1493 211 0.3315 0.3342 005 1.1478 202 0.3469 0.3495 421 1.1884 300 0.3672 0.3696 323 1.1884 1.1895 301 0.4131 105 1.1884 0.4158 1 .2036 003 0.4132 502 1 .2055 103 ' 0.4539 0.4567 224 1.2242 1.2254 212 0.4693 0.4716 510 1.2648 I . 2 6 7 0 220 0.4896 0.4916 314 1 .2650 310 0.5304 0.5343 115 1 .2701 1.2699 1.2715 113 0 .5355 413 0.5381 1 .3106 211 0 .5355 511 1.3116 302 0 .5509 0.5534 205 1.3110 TABLE O P S . h k 1 C a l c . bs t 203 0.5764 0.5777 311 0.5763 401 0.6987 0.7005 213 O.6987 312 0.7140 0.7158 004 0.7345 0.7372 320 0.7752 0.7779 321 0.8213 0.8245 402 0.8364 0.8379 410 0.8568 0.8595 223 0.9027 0.9056 411 0.9027 48A 6 (cont 1 d) h k 1 C a l c . Obs. 422 1.3260 1.3270 503 1.4331 1.4338 215 1.4333 600 1.4688 1.4698 430 1.5095 1.5105 324 1 .5097 305 1.5150 1.5150 333 1.5147 423 1.5556 1 .5560 431 1.5555 520 1.5912 1.5914 225 1.6374 1.6376 49 6F i n 6 ( i ) : (x, x, z ), (x, 2x,z ), (2x, x, z ), (x, x , z ) , (x, 2 x , z ) , ( 2 x , x , Z ) . The i n t e n s i t i e s of l i n e s were calculated with the formula I <*C F hkl 2 P 1 1 - c o s 2 2 $ s i n 6 c o s O where F, , _ i s the calculated structure factor for the set hkl 2 of planes h k l , p i s the permutation fac t o r , and 1 » cos 2Q sin2© cos© i s a combination p o l a r i z a t i o n , Lorentz and geometric f a c t o r . A problem arose, when i t was found that the X-ray powder photograph of the sample which was considered purest and most c r y s t a l l i n e showed anomalous i n t e n s i t i e s which did not correspond to any reasonable structure. Close Inspection of the photograph showed that the l i n e s which were much stronger than expected were a l l due to planes of atoms p a r a l l e l to the C axis. The 001 l i n e was weaker than expected and uneven i n t h i s photograph. The i n t e n s i t y of the 100 l i n e was very strong i n the equatorial zone of the photograph, but faded appreciably at i t s edges. This evidence established that preferred o r i e n t a t i o n of the c r y s t a l l i t e s i n the glass c a p i l l a r y had occured. The c r y s t a l s are presumably needle shaped, the C axis being p a r a l l e l to the axis of the c r y s t a l . When packed into a f i n e c a p i l l a r y the cr y s t a l s next to the wall of the tube tend to l i n e up p a r a l l e l to the wall with the i r long axes along the length of the c a p i l l a r y . Since potassium hexaf luopalladate (IV) has a high absorption 50 c o e f f i c i e n t , the i n t e n s i t y of X-ray powder photograph l i n e s i s determined l a r g e l y by the outermost layer of the cylinder of material. An X-ray powder photograph of another preparation which had been more c a r e f u l l y powdered gave a pattern i n which the preferred o r i e n t a t i o n e f f e c t s were absent. The r e l a t i v e i n t e n s i t i e s were estimated v i s u a l l y on a scale v . s . ^ s. m.s.^ m. ^  m.w. ^  w. ^ v.w. ^  v.v.w. The f i n a l positions of the atoms were obtained by t r i a l and error methods. The structure factor F n k l for a plane of atoms i s the algebraic sum of the structure factors of the various atoms i n that plane. phki= W p d> *ww *W F> F^^(Pd) i s independent of any variables because of the unique po s i t i o n assigned to the Pd atom. The value of F h k l ( P d ) i s therefore constant. FhkJ.( K) i s d e P e n < 3 e n t on only one variable, Z. Fnk.x(F) i s d e P e n d e r r f c o n "k™0 v a r i a b l e s , X p and Zp. I n t e n s i t i e s due to planes of the hkO series w i l l be independent of Z , and w i l l therefore depend only on X p. Using an Alwac III E d i g i t a l computer, values for p^ (1 ,^cos22e) ^ F h k l ( p d ) * F h k l ( K ^ ^ (si n © cos©) ' ' P^ (1 t cos 22 ) £(F (F)) were calculated and ( M r r e e d s e ) ( h K 1 % ) tabulated for a range of possible values of Z K , X F and Zp. 51 Values of the parameters were arrived at by comparison of the calculated i n t e n s i t i e s of a l l possible combinations of parameters with the observed values of the i n t e n s i t i e s . The f i n a l values for the parameters were: Z k z .70 t .02 x F m .15 t .01 Z P - .24 * .02 The observed and calculated i n t e n s i t i e s for th i s structure are l i s t e d i n Table 7. TABLE 7 Observed and Calculated I n t e n s i t i e s f o r K 2 PdP 6 h k l obs *calc hkl I . obs ''"calc 100 S 721 211 M.S. 275 001 M 244 202 S. 346 101 V.S. 949 300 w. 81 110 s 427 301,003 w. 69 200 N i l . 5 103 v.v.w. 15 111 M.W. 153 212 M.S. 259 002 N i l 8 220 M. 145 201 V.S. 794 310 V.W. 31 102 M 210 113,221 M. 137 210 W 42 302 V.W. 23 112 W 57 203,311 400 M.S. N i l 189 2 BIBLIOGRAPHY 1. Weinstoek and Malm, J . Amer. Chem. Soc.. 80, 4466 (1958) 2. Ruff and Tschirch, Ber., 4 6 , 929 (1913) 3 . Ruff and Ascher, Z. anorg. Chem.. 183. 204 (1929) 4 . Sharpe, J . Chem. Soc., 3444 (1950) 5. Berzelius, Handworterbuch der Chemie, VIII, p.449 6 . Ruff and Ascher, Z. anorg. Chem.. 183. 211 (1929) 7. B a r t l e t t and Hepworth, Chem and Ind.. 1425 (1956) 8. Hoppe and Klemm, Z. anorg. Chem.. 268. 364 (1952) 9 . B a r t l e t t , Ph.D. Thesis, U n i v e r s i t y of Durham, 1958 10. Clark, Chem. Reviews. £8, 869 (1958) 11. Simons, Fluorine Chemistry, Academic Press Inc., New York, N.Y. V o l . I, p.226 (1950) 12. Hepworth, Robinson and Westland, Chem. and Ind., 1516 (1955) 13. Emeleus and Woolf, J . Chem. S o c . 2865 (1949) 14. Sharpe and Emeleus, J . Chem. Soc., 2135 (1948) 15. Nyholm and Sharpe, J . Chem. S o c . 3579 (1952) 16. Earnshaw, F i g g i s , Lewis and Nyholm, Nature. 179. 1122 (1957) 17. Nyholm, Report to the Tenth Solvay Council, p.37? May 1956 18. Hepworth, Jack, Peacock and Westland, Acta Cryst.« 10, 63 (1957) 19. Sharpe, "Advances i n Fluorine Chemistry", Butterworth S c i e n t i f i c Publications, London, V o l . I, p.56 2 0 . B a r t l e t t and Ma i t land, Acta Cryst.. 11, 74-7 (1958) 2 1 . Sharpe, J . Chem. Soc. 197 (1953) 53 22. B a r t l e t t and Yu, Can. J. Chem.. 3£, 81 (1961) 2 3 . Mellor and Stephenson, A u s t r a l . J. S c i . Res.. 4A, 406 ( 1 9 5 D 24. Hoard and Vincent, J. Amer. Chem. Soc., 6 3 . , 2849 (1939) 25. Weinstock and Malm, J. Inorg. and Nucl. Chem.« 2, 380, (1956) 26. Sharpe, J. Chem. S o c 2901 (1949) 27. French and Trew, Trans. Far. Soc., 41, 439 (1945) 2 8 . F i g g i s and Nyholm, J. Chem. Soc.. 4190 (1958) 2 9 . Willard and Winter, Ind. Eng.. Chem., Anal. Ed., % 7 (1933) 3 0 . Aynsley, Peacock and Robinson, J. Chem. Soc., 1231 (1952) 31. Sagel, "Tabellen zur Ronteenstrukturanalyse." Springer Verlag, B e r l i n , p. 106-119 (1958) 3 2 . Azaroff and Buerger, "The Powder Method." McGraw-Hill Book Company, Toronto, (1958). 

Cite

Citation Scheme:

        

Citations by CSL (citeproc-js)

Usage Statistics

Share

Embed

Customize your widget with the following options, then copy and paste the code below into the HTML of your page to embed this item in your website.
                        
                            <div id="ubcOpenCollectionsWidgetDisplay">
                            <script id="ubcOpenCollectionsWidget"
                            src="{[{embed.src}]}"
                            data-item="{[{embed.item}]}"
                            data-collection="{[{embed.collection}]}"
                            data-metadata="{[{embed.showMetadata}]}"
                            data-width="{[{embed.width}]}"
                            async >
                            </script>
                            </div>
                        
                    
IIIF logo Our image viewer uses the IIIF 2.0 standard. To load this item in other compatible viewers, use this url:
http://iiif.library.ubc.ca/presentation/dsp.831.1-0062145/manifest

Comment

Related Items