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Vibrational spectroscopic studies of some simple and mixed selenium (iv) oxy-halides and pseudohalides. Wilson, William W. 1972

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VXBRATIOKAL SPECTROSCOPIC STUDIES OP SOME SIMPLE AND MIXED SEL3inu::(iy)0XT-HALID3S MTU -PSEUDOHALIDES  BY  WILLIAM W. WILSON B.Sc. University o f Idaho, Moscow. Idaho, 196"9  A THESIS SUBMITTED H i PARTIAL FOXFILHEZiT OP THE .REQUIREMENTS FOR THE DEGREE OP MASTER OP SCIENCE  i n the Department of CHEMISTRY  We accept t h i s the3i3 as conforming to the required standard  THE UNIvERSITT 0? BRITISH COLUMBIA  In p r e s e n t i n g t h i s  thesis  an advanced degree at the L i b r a r y I  in p a r t i a l  the U n i v e r s i t y  s h a l l make i t  freely  f u l f i l m e n t o f the of B r i t i s h  available  for  requirements  Columbia, I agree reference  for  that  and s t u d y .  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 copying o f t h i s  thesis  f o r s c h o l a r l y purposes may be g r a n t e d by the Head o f my Department o r by h i s of  this  representatives.  It  thesis for financial  is understood that c o p y i n g o r p u b l i c a t i o n gain shall  written permission.  Department o f  C  v\ •<?- (A\ \ S T T ij  The U n i v e r s i t y o f B r i t i s h Columbia Vancouver 8, Canada  not be a l l o w e d without my  - i i -  ABSTRACT  The i n f r a r e d and polarized Raman spectra of Se0Br as a 2  s o l i d , melt, and i n s o l u t i o n have been obtained.  The frequencies  that were found are consistent with C_ symmetry and a pyramidal molecule.  Ionic d i s s o c i a t i o n , l i k e i n other SeOXg compounds,  i s evidenced by e l e c t r i c a l conductance measurements. -act both as a Lewis a c i d or base.  Se0Br  2  can  For example, a s a l t with the  composition KSeOBr^ has been prepared from KBr and SeOBr . 2  Ligand r e d i s t r i b u t i o n reactions of various Se0X and SeOY 2  compounds, where X and Y are F, CI, Br, and SO^F, v i a v i b r a t i o n a l spectroscopic and techniques.  2  were studied  nuclear magnetic resonanoe  The presence of the mixed SeOXY compounds has been  detected i n a l l these systems b a s i c a l l y i n equilibrium with t h e i r parent compounds.  None of the SeOXY compounds could be separated  out of the mixtures.  - iii -  TABLE OP CONTENTS  Page TITLE PAGE ABSTRACT  i i  TABLE OP CONTENTS  i i i  LIST OP TABLES  viii  LIST OP FIGUBES  ix  ACKNOWLEDGEMENTS  x  I.  INTRODUCTION  1  A.  General Points  1  B.  Selenium(lV)oxy-halides and a -pseudohalide  3  1.  4  2.  3.  Se0P  2  a.  Preparations and General Properties  4  b.  P h y s i c a l Properties  5  o.  Spectroscopic Data  5  d.  Structure  8  SeOCl  8  2  a.  Preparations  b.  P h y s i c a l Properties  c.  Spectroscopic Data and Structure  SeOBr  ,  2  8 «  9 9 10  a.  Preparations  1°  b.  P h y s i c a l Properties  11  - iv -  Page 4.  5  11  2  a.  Preparations  11  b.  Physical Properties  12  c.  Speotrosoopio Data  12  Some Aspects of Thionyl-halides and a -pseudohalide  12  1.  General Features  13  2.  Structures  14  3.  Physical and Chemical Properties  15  D.  Mixed Oxyhalid.es of Sulphur and Selenium  17  E.  Bonding i n Thionylhalides  20  F.  Bonding i n Selenium(lV)oxyhalides  23  C.  II.  SeO(S0 P)  EXPERBffiHTAL  29  A.  Chemicals  29  1.  Reagents  29  a.  Commercial  29  1)  Se  29  2)  P  29  3)  Br  2  4) N  30  2  30  2  5) Se0  6)  30  SO,  7) S e 0 C l 8) KBr  9)  30  2  CC1  2  30 30  4  10) CFC1  31 31  -  V  -  Page b.  Prepared  31  > 2°6 2  X  S  P  5 1  2) SeO(S0 P) 5  3) S e P  32  4  4) S e O F  32  2  5) S e O B r 2.  31  2  33  2  Products  33  a.  Equilibrium-type  34  1 ) SeOFtSC^F)  34  2) SeOCl(S0 F)  34  5  3) SeOBr(S0 F) 5  B.  34  4) SeOCIF  35  5) S e O B r C l  35  6) b.  ,  SeOBrF "  11  36  Salt-type  36  1) KSeOBr^  36  Apparatus  36  1.  Vacuum L i n e s  36  a.  Glass  37  b.  Konel  37  2.  3.  F  2  line  38  a.  S 0 F 2  6  b.  SeF  4  Drybox  2  type  type  38 40 41  - vi -  4.  5.  6.  C.  Reactors  41  a.  Erlenmeyer  41  b.  Two-part pyrex  41  c.  Two-part monel  41  d.  Kel-F  45  e.  SeOBr type  45  2  Miscellaneous  48  a.  Vacuum f i l t r a t i o n apparatus  48  b.  Sublimation apparatus  48  c.  Molecular sieves  48  d.  Grease  49  e.  " pi-pump "  .  49  Analyses  49  a.  Borda  49  b.  Bernhardt  49  Instruments  50  1.  Raman  50  2.  Infrared  50  a.  P.E. 457  50  b.  P.E. 301  52  3.  MR  52  4.  Conductivity  54  - vii -  Page I I I . RESULTS kKD DISCUSSIONS  56  A.  The V i b r a t i o n a l Spectrum o f SeOBr  B.  The Assignment o f V i b r a t i o n a l Frequencies f o r SeO(S0 F) 5  C.  60  2  The Existence o f SeOXY Molecules i n Ligand R e d i s t r i b u t i o n Reactions  65  1.  SeOBrCl  66  2.  SeOCIF  3.  D.  56  2  11  ,  68  SeOBrF "  70  4.  SeOBr(S0 F)  73  5.  SeOCl(S0 F)  77  6.  Se0F(S0 F)  79  7.  Conclusions  SI  5  5  5  The Formation o f a S a l t between KBr and Se0Br  BIBLIOGRAPHY.  2  ...  82  86  - viii -  LIST OP TABLES Table  Page  1  Some Physical Constants o f SeOX -type Molecules  2  V i b r a t i o n a l Frequencies (cm" ) f o r SeOF and SeOCl  3  Some Physical Constants o f S0X -type Molecules  18  4  Vibrational. Frequencies ( c m ) f o r SeOBr  58  5  Conductivity Data as a Function o f Temperature f o r  2  2  2  -1  2  V i b r a t i o n a l Frequencies (cm-1) and Assignment f o r 5  64  2  Vibrational Frequencies ( c m ) f o r SeOCl -1  2  and SeOBr  2  67  i n Varying Ratios 8  V i b r a t i o n a l Frequencies ( c m ) f o r SeOCl -1  i n 1.0 9  ^ F  2  and SeOF  2  : 1. 0 Ratio  69  Chemical S h i f t s f o r Some Selenium-Fluorine 71  Compounds 10  V i b r a t i o n a l Frequencies ( c m ) f o r SeOF and SeOBr -1  2  i n 1.0  : 1.0  2  72  Ratio  11  Correlation o f Selenium-Oxygen Compounds with Numbers  12  V i b r a t i o n a l Frequencies ( c m ) f o r Some  74  -1  SeOX(SO^F) Compounds, X = P, CI, Br 13  7  6l  2  SeO(S0 F) 7  ..  1  SeOBr 6  6  2  75  V i b r a t i o n a l Frequencies ( c m ) f o r Some -1  KSeOX, Compounds, X = F, CI, Br  84  - i x-  LIST OP FIGURES Figure  Page  1  C o r r e l a t i o n between S-0 and Se-0 F o r c e C o n s t a n t s ...  2  Metal Fluorine Line Including Catalytic S 0gF 2  26  2  Reactor  39  3  Erlenmeyer Reactor  L2  4  Two-part P y r e x R e a c t o r  43  5  Two-part Monel R e a c t o r  44  6  K e l - F Reactor  46  7  S e 0 B r - Type R e a c t o r  47  8  K e l - F Raman C e l l  51  9  F a r IR C e l l  53  10  Conductivity Cell  55  11  Raman Spectrum o f S e 0 B r  2  as a S o l i d ;  Raman Spectrum o f S e 0 B r  2  as a Melt  12  2  57  S p e c i f i c C o n d u c t i v i t y o f Some Selenium-Oxy Compounds as a F u n c t i o n o f Temperature  62  -  X -  ACOWVLEIXJEHEOTS  I would l i k e to sincerely t h i s topic  thank Dr. F. Aubke f o r suggesting  o f research and f o r helping me at every stage toward  the completion of t h i s  project.  Thanks are also extended to a l l the members of the research group f o r t h e i r h e l p f u l comments, and to Dr. A. Bree f o r h i s e f f o r t s i n helping to obtain the Far i n f r a r e d  results.  - 1 -  I.  A.  INTRODUCTION  General Points The occurrence o f l i g a n d r e d i s t r i u b t i o n type reactions has  been noted f o r approximately  100 y e a r s . 1  But i t was not u n t i l  Calingaert and co-workers began t h e i r studies on mixed a l k y l lead compounds i n the 1940's that much was known about what was 2 5 occurring ' .  Indeed, i t was only a f t e r somewhat more s o p h i s t i c a t e d  p h y s i c a l techniques^ became a v a i l a b l e that i n t e r e s t began to increase i n this f i e l d o f chemistry.  Now many r e d i s t r i b u t i o n reactions are  known, some o f which include members o f group VI A as the element under study. A recent i n t e r e s t i n g example i s the l i g a n d r e d i s t r i b u t i o n r e a c t i o n between SgBr^ and S^Cl^ where the compounds SgBrCl has been i d e n t i f i e d by v i b r a t i o n a l techniques^.  Another  such case i s the precedent f o r diselenides to become involved i n an equilibrium type o f ligand scrambling r e a c t i o n as reported by Grant and Van Vfazer^. was reacted with S e C l 2  2  In t h i s instance, (CH-)  2  Se o r ( C H ^ ) S e  to form d i v a l e n t polyselenides with  scrambled terminal substituents, such as CH-tSe^Cl, the chain 3 4 length o f selenium varying i n number. Another case i s that o f  2  2  - 2 -  G i l l e s p i e et a l who attempted 7  to study the mixed oxyhalides of  selenium obtained from ligand r e d i s t r i b u t i o n type reactions, but who was  only able to e s t a b l i s h the existence o:f SeOClF unambiguously-  the rapid exchange of ligands ostensibly making i t too d i f f i c u l t to analyze the other r e a c t i o n products. The means of d e t e c t i o n i n both of these l a t t e r cases with NMR  spectroscopy, %  and *^Se r e s p e c t i v e l y .  was  This t o o l  can be of great use i f the l i f e t i m e of a product being investigated, i n a l i g a n d exchange r e a c t i o n i s s i g n i f i c a n t l y greater than the time span of the MR  experimental procedure.  Assuming t h i s to  be the case f o r a system under study, say i f three resonances are found and two may  be ascribed to the parent compounds, then  the remaining one may  safely be assigned to a new product from  the r e a c t i o n (providing chemical s h i f t and coupling constant values p e c u l i a r to the system are reasonable).  I f , however,  the l i f e t i m e of the product i s on the order of or much l e s s than the time required f o r the NMR situation exists.  detection techniques, a d i f f e r e n t  One main difference might be a time averaging  o f resonance signals i n the IE-IE spectrum l e a d i n g to a single peak which i s d i f f e r e n t i n p o s i t i o n from any parent compound i n the reaction.  Such a peak has two p o s s i b i l i t i e s f o r explanation.  F i r s t , a s i t u a t i o n s i m i l a r to that above where a new  produot  i s formed v i a a ligand r e d i s t r i b u t i o n equilibrium except the l i f e t i m e of the new product i s very short and escapes exact  - 3 -  detection due to rapid exchange; or second, no new  product is  formed and the peak observed i s an average one f o r a mixture of only the parent compounds.  In some cases i t may  be possible  to reduce the temperature of the system to gain some information, but f o r others this technique may  not be a p p l i c a b l e .  In  general, however, due to i t s r e l a t i v e l y long time scale, EMR  is  not suited f o r investigations o f the type where r a p i d exchange i s possible.  In t h i s regard i t became i n t e r e s t i n g to investiage  the mixed selenium-oxyhalides by v i b r a t i o n a l spectroscopy, e s p e c i a l l y with respect to SeOBrCl where r e s u l t s w i l l be shown to be contradictory. generally between 1CT  The time scale f o r EMR 1  experiment i s  and 10~^ seconds, compared with that f o r —13  v i b r a t i o n a l spectroscopy which i s on the order of 10  B.  Selenium(lV)oxy-halides  8 seconds . 0  and a -pseudohalide  This part w i l l very b r i e f l y review previously reported work on the synthesis of oxyhalides  o f selenium(lV), i n c l u d i n g the  r e l a t e d compound SeO(SO^F) and some of t h e i r p h y s i c a l properties 2  pertinent to t h e i r intermolecular association and t h e i r subsequent d i s s o c i a t i o n i n t o ions i n the l i q u i d phase.  In addition, emphasis  w i l l be placed on the molecular structures so f a r as they are known and on t h e i r v i b r a t i o n a l spectra. of the selenium(lV)oxyhalides  Some general  properties  and Se0(S0^F) nay be b r i e f l y 2  mentioned: ( l ) They are a l l extremely moisture s e n s i t i v e and easily undergo s o l v o l y s i s reactions, (2) They are r e l a t i v e l y  - 4 -  corrosive and s e n s i t i v e toward oxidizable material and (3)  They are t o x i c or very probably  compounds are known to be 9»10.  t o x i c l i k e many selenium  These features pose many r e s t r i c t i o n s  and make vacuum l i n e and dry box operations mandatory. 1.  SeOP  a.  Preparations  2  and General Properties  Selenium(IV)oxyfluoride,  SeOFg, was made i n 1928  s i l v e r f l u o r i d e , AgF, with selenium(IV)oxychloride, SeOCl + 2AgF  by r e a c t i n g SeOCl,,,  SeOF + 2AgCl  2  (l)  2  The reaction had to be c a r r i e d out i n a platinum b o t t l e due to a decomposition of SeOF by 2  glass reactors.  I t was  later  discovered that chlorine t r i f l u o r i d e , CIF^, when reacted with 13 selenium dioxide, SeCv,, would provide SeOFg i n a yield.  11  good "  Also mentioned i s the reaction of SeOCl with HF to 2  14 generate the oxyfluoride  according to  SeOCl + 2EF  *- SeOF +  2  2  But the most e f f i c i e n t way  2HC1  (2)  to obtain SeOF i s by the r e a c t i o n 2  15 o f selenium t e t r a f l u o r i d e , SeF^, with Se0 ,  where the y i e l d  2  has  been found to be nearly q u a n t i t a t i v e ^ SeF + Se0 4  ^  2  2SeOF  (3)  2  Another route to obtain SeOF i s the reaction of SeF^ 2  with  17 Te0  2  according to:  2 SeF^ + Te0 *• 2 SeOF + TeF^ o f suspended KaF i n a solvent r e a c t i o n medium, such as 2  2  (4) tetramethylene-  18 Other novel reactions to obtain SeOF are described where reaction sulfone, i s effected with SeOCl,, , besides that of the d i r e c t 2 2  f l u o r i n a t i o n of Se0  19  2  b.  Physical Properties The s o l u b i l i t i e s of several compounds i n SeOP have been 2  q u a l i t a t i v e l y established.  For example, SeOF has been found 2  19 to be a solvent f o r s u l f u r and selenium metal ' as well as f o r ethyl a l c o h o l .  Besides, SeOF has been found to be soluble i n 2  alcohol and tetramethylenesulfone, but not to any appreciable degree i n a non-polar solvent such as carbontetrachloride, CCl^ The vapor pressure curve o f SeOF nay be represented as l o g p = 8.70 - 2316 T 2  between 45° and 125°C. ^  From t h i s equation, the Trouton  constant may be calculated to be 26.85 i n d i c a t i n g some a s s o c i a t i o n of the molecule i n the l i q u i d state.  Please see  Table 1 f o r other s p e c i f i c constants.  c.  Spectroscopic Data The v i b r a t i o n a l (Raman) data have been compiled i n Table 2  f o r SeOFg. 1005,  Accordingly i t may be noted that four v i b r a t i o n s -  659, 368, and 271 cm  -1  - have been found to be polarized,  and the other two- 601 and 305 cm"  1  - depolarized  ,  r e f l e c t i n g the 4 symmetrical ( A ) and 2 asymmetrical (A") 1  modes respectively f o r a molecule of C  g  symmetry.  77 A  Se HMR resonance has been observed f o r i t at  + 100.6  ppm from SeOCl?- ^  - 6 -  TAEL2 1 S o i e P h y s i c a l Constants  boiling p o i n t (°C) densitv (g/ce)"  15  o '  125-6  10.9  o '  2.30 £ 21.5°C  y  SeC(S0^F)2  -^5  7  21^ , deco;no. ?i  0  6 16°C  *2 20°C  22  2. Sif  17  (f.n.)  >200 s i . decorro. •? i' °  & 25" C  26.35  45  9  2,o2  •2 50°C  9  2.0 x 1 0 "  dielectric constant  Trouton constant  Q '  K^leculss  9  q  specif ic conductivity (•n.ho c;i ")  d i r - o l e mo-neni (Debye)  177.2  - Tvoe  o  S-03r  SeOCl,,  SeC^ •nelting P o i n t (°C)  of Se0X  =  0  6 x 1,T  5  i - 45-50 C c  1.5? x 10~ ' ;  - 7TABL2 2  V i b r a t i o n a l Frequencies  (ciT )  f o r SeOFg and SeCCL^  SeCF,  reference . 16  20  20  S.F . igTn=nt c  1012  1005  950  055  •3e=C 659  ( s , .:»e-A2  ( s ) O-Se-X  ^(ap)  O-Se-X  * X-Se-X  390  338  390  347  350  605  601  373  363  273  279  271  303  305  250  2-55  2U6  273  271  162  161  153  - ad.  Structure The structure of gaseous SeOF has been determined  by means  2  of microwave spectroscopy. a d i s t o r t e d pyramid f o r Se-0 and 1.730  of C  s  The molecule i s best described as symmetry with bond lengths 1.516k  f o r Se-F, and bond angle 92.22° f o r P-Se-P 00  and 104.82° .for O-Se-F.  In terms of G i l l e s p i e 23  e l e c t r o n - p a i r repulsion theory  and Kyholm's  the molecule can be viewed as  a pseudo-tetrahedral species with one lone p a i r of electrons on selenium occupying one coordination s i t e . 2.  SeOCl  a.  Preparations  2  SeOCl^  w  a  f i r s t reported by V/eber i n 1859 when he reacted  s  24  hot SeOg and SeCl^ vapors to obtain the l i q u i d product indicated by the r e a c t i o n Se0 + S e C l 2  *• 2SeOCl  4  (7)  2  However, the oxychloride can be made most simply by adding t h i o n y l c h l o r i d e , S0C1 , to Se0 2  (and gaseous S0  2  2  initially  forming SeCl4  as a byproduct), the S e C l  further reacting  4  25 26 with more Se0  to obtain the f i n a l product  2  S0C1 + Se0 2  Alternatively Se0Cl  2  '  »• SeOCl + S0  2  2  : (8)  2  can be formed by the p a r t i a l h y d r o l y s i s or  complete dehydration of parent compounds SeCl^ and dichloroselenious 27,28 acid, H S e 0 C l , respectively according to SeCl + H 0 5- S e 0 C l + 2EC1 (9) 2  2  2  4  2  / x Se(0H) Cl 2  2  H  2  2  S 0  4  ^  Se0Cl  2  + H S0 'E 0 2  4  2  (10)  - 9 b.  Physical Properties SeOCl  2  i s a hygroscopic c o l o r l e s s  conductance of 2.0 x 10 ~5 mho  cm"  l i q u i d which has a s p e c i f i c ^  1  which indicates the  separation of S e 0 C l molecules i n t o ions. 2  Indeed, the i o n i z a t i o n  of SeOClg has been f u r t h e r supported by ^ C l i s o t o p i c exchange reactions between l a b e l l e d chloride s a l t s dissolved i n S e 0 C l 50>51 2  #  32 The d i e l e c t r i c constant f o r SeOClg i s 46.2 a t 20°C  and i s r e l a t i v e l y 33  high when compared to that of 9.25  (at 28° C) f o r SOClg  Together, these properties suggest i t s use as a non-aqueous solvent, and correspondingly, work has been done i n t h i s f i e l d with Gutmann 54,35,36  m  d  smith 57 supplying reviews.  The d i e l e c t r i c  constant being a measure of the p o l a r i z a t i o n of a substance, also tends to indicate f o r SeOClg the association of i t 3 molecules i n the l i q u i d phase 3.,«39 although perhaps not to such a degree 8  J  as i t i s f o r water molecules whose d i e l e c t r i c constant i s 78.3 at 25° C. 53  Supporting t h i s case i s the i n f r a r e d study made of SeOClg  i n various solvents where the Se-0 s t r e t c h i n g frequency undergoes a s h i f t to higher energy when SeOClg i s dissolved i n CS  2  as  compared to i t s p o s i t i o n i n the neat l i q u i d s t a t e . 40 Other data f o r the oxychloride are found i n Table 1. c.  Spectroscopic Data and Structure The complete Raman spectrum of SeOClg has been recorded by  several workers and t h e i r r e s u l t s are c o l l e c t e d i n Table 2. >41>42 20  A discussion of the structure has revealed that the molecule  - 10 -  i s again best described as a d i s t o r t e d pyramid with C  g  symmetry.  Such a molecule should give s i x Raman and i n f r a r e d active peaks, four being symmetrical ( A ) and polarized, and two being asymmetrical 1  (A") and depolarized i n the Raman spectrum.  This was confirmed  20 by Paetzold who also assigned the peaks t h e i r modes. In 77 7 addition, the 'Se KKR spectrum has also been recorded as w i l l be mentioned  later.  3.  SeOBr  a.  Preparations  2  The synthesis o f selenium(lV)oxybromide, Se0Br , 2  y i e l d i n g yellowish-red needles was mentioned  f o r the f i r s t time  ,,43 by Scheider i n 1866  when he reacted selenium tetrabromide, SeBr^,  with dry seleneous acid - Se02>. according to SeBr^ + Se0  2  *• 2 SeOBr  Later i n 1913 Glauser44 d i s t i l l e d SeOCl  2  (ll)  2  onto an excess o f NaBr  to obtain the same compound. SeOCl  2  + 2 NaBr  SeOBr + NaCl 2  (12)  But i t was not u n t i l 1922, when e f f o r t s were made to prevent atmospheric moisture from entering the reaction system, that r e l a t i v e l y pure SeOBr was made. 2  This was done by Lehner who  combined dry selenium metal, sublimed selenium dioxide, and an appropriate quantity of bromine to give the product upon warming^, m.p. 41-5 - 41'7°C, Se + Se0 + 2 Br„ -> 2SeOBr o  9  (13)  - 11 -  The product was s t i l l reddish-yellow, but l a t e r i t was found that i t could be p u r i f i e d .by vacuum sublimation and o as bright-yellow needles with a melting point o f 45 b.  obtained  T C.  Physical Properties The s p e c i f i c conductance of SeOBr has been measured as being 2  6 x lO'^mho cm"  1  obtained.  ^  at 45 - 50 °C f o r the product that Lehner  However, no accurate temperature was  recorded, nor  was  i t reported whether the temperature c o - e f f i c i e n t of conductance has a p o s i t i v e or negative value.  Se0Br  2  can be dissolved i n a number  of solvents, usually somewhat non-polar such as carbontetrachloride, CCl^, and xylene, but i t i s also i n t e r e s t i n g to note that SeOBr^ i s immiscible with saturated a l i p h a t i c hydrocarbons such as hexane and decane.  On the other hand Se0Br has been found to be a s u i t a b l e 2  solvent i n the molten form f o r a number of other compounds such as  7 45 iodine, benzene and other selenium(lV)oxyhalides o f other common properties i s made i n Table 1.  '  .  A tabulation  Unlike the other  oxyhalides, however, neither i t s spectroscopic properties nor i t s structure have been discussed previously. 4.  SeO(S0 P)  a.  Preparations  5  2  Seleniun(lV) oxyfluorosulfate, Se0(S0^F) was 2  prepared r e c e n t l y ^  by the action of p e r o x y d i s u l f u r y l d i f l u o r i d e , S^O^F^, upon Se0 . 2  This reaction, taking 10 hours at 50°C to achieve the  products, was l a t e r improved upon when SgO^F^ was with S e 0 C l  2  to form Se0(S0jF)  2  reacted  at room temperature,  - 12 -  SeOCl  + S 0 P  2  2  6  > SeO(S0 P) + C l  2  5  2  2  (14)  I t was also discovered that bromine monofluorosulfate, BrOS0 F, 2  when reacted with SeOCl SeOCl b.  would y i e l d s i m i l a r r e s u l t s ,  2  + 2BrOS0 F  2  2  —->  Se0(S0 F) 5  2  + 2BrCl  (15)  Physical Properties Se0(S0^F)  2  has proved to be very reactive, i g n i t i n g paper i n an  i n e r t atmosphere.  The s p e c i f i c conductance of the colorless  viscous l i q u i d has been shown to be 1.59  x 10"^ at 25°C i n d i c a t i n g  that i t , too, i s i o n i z i n g i n neat s o l u t i o n .  I t s high v i s c o s i t y  and low vapor pressure have l e d to the. conclusion that the l i q u i d i s highly associated.  Beyond that i t has also been found that i t i s  soluble i n HSOjF, moderately so i n excess S 0gF ,..and not at a l l i n CC1 2  2  Other pertinent p h y s i c a l constants may be found i n Table 1. c.  Spectroscopic Bata The Raman spectrum of Se0(S0^F)  2  has been recorded^and the  frequencies of vibrations are l i s t e d i n Table 6 .  A tentative  assignment o f the peaks was also presented.47 C.  Some Aspects of Thionyl-halides and a -pseudohalide In t h i s part w i l l be given a b r i e f account of some chemical  and physical properties o f the thionylhalides and a related compound S0(S0^F)2.  I t i s intended f o r these properties to  show both s i m i l a r i t i e s and d i s s i m i l a r i t i e s of these s u l f u r compounds to t h e i r selenium analogues, which i s o f prime importance to a discussion of the bonding patterns  - 13 -  of both groups of molecules.  1.  General Features The thionylhalides may be conveniently prepared i n the  following ways: a) f o r SOF,,, the strong f l u o r i n a t i n g AA  action o f arsenic t r i f l u o r i d e on SOClg  i s typical;  b) f o r S0C1 , the reaction of S 0 with PCl^ can be used, 2  2  forming the thionylhalide, ^  8  and POCI3 as a by-product;  and c) f o r SOBr , the bromination of S0C1 2  by HBr ^  2  can  be employed. The pseudothionylhalide, S 0 ( S 0 j F ) has also 2  been  50 reported  and may be prepared i n an analogous was as that  f o r Se0(S0jF) - with S0C1 and BrOSOgF, c.f. reaction 2  2  S0C1 + 2BrOS0 F 2  »- SO(S0 F)  2  5  (l6)  + 2BrCl  2  (15)  Other analogous reactions of s u l f u r ( l V ) and selenium(IV)oxyhalides . 14 are when a) S0C1 i s combined with HF to form the oxyfluoride, as i n reaction (2) according t o : 2  S0C1 + 2 HF  S0F + 2 HCl  2  2  (17) 51  and when b) S0C1 i s reacted with Na3r to form the oxybromide, 2  as i n reaction (12) according t o : S0C1 + 2 NaBr —>• S0Br + 2 NaCl 2  2  (18)  The vapor pressures of S0Br and S0C1 have been described by 2  2  52 53 several workers. ' Both S0C1 and S0Br are l i q u i d s at 54, room temperature, but S0F i s a gas at that point, b.p. -43.8°C. 2  2  2  In addition the orange-yellow c o l o r of l i q u i d S0Br compares 2  well with the bright-yellow color of c r y s t a l l i n e SeOBr,,.  A l l of  - 14 -  the s u l f u r ( I V ) o x y h a l i d e s a r e u n s t a b l e toward w a t e r - each b e i n g e a s i l y and t o t a l l y h y d r o l y z e d , 48,56 except i n the slow  case o f  48 SOP^.  Also n o t i c i n g that Se0Br  o r n e a r i t s b o i l i n g p o i n t , 45,54  S  U  has been found t o decompose upon  2  C  i  A  been found t h e case f o r  ia3  49 57 SQBr . 2  I t i s so r e l a t i v e l y u n s t a b l e t h a t i t has been found t o  d i s s o c i a t e s l o w l y a t room temperature All  (into S Br ,S0 2  2  2  and B r ) 49,53 2  three simple oxyhalides o f s u l f u r ( i v ) a r e s o l u b l e i n  r e l a t i v e l y n o n - p o l a r s o l v e n t s . 52,56 2.  Structures S e v e r a l d i f f e r e n t methods o f a n a l y s i s have a l l y i e l d e d common  c o n c l u s i o n s i n the d e t e r m i n a t i o n o f the m o l e c u l a r s t r u c t u r e s f o r the t h i o n y l h a l i d e s .  I n t h e case o f SOP  2  a microwave study r e p o r t s  58 the m o l e c u l e ' s s t r u c t u r a l parameters^ v a l u e s found f o r S e O F  2  , which when compared t o t h e  leads t o the c o n c l u s i o n that  thionylfluoride  i s a d i s t o r t e d pyramid s i m i l a r t o i t s s e l e n i u m c o u n t e r p a r t . e l e c t r o n d i f f r a c t i o n study o f S 0 C 1  2  has summarily  An  s t a t e d t h a t the  59 s t r u c t u r e o f t h i o n y l c h l o r i d e i s a l s o p y r a m i d a l i n shape  ,  a l t h o u g h a d i s c r e p a n c y o f v a l u e s e x i s t s f o r the CI - S - CI b o n d i n g a n g l e as determined by d i f f e r e n t workers. An attempt  t o measure the s t r u c t u r a l parameters  59,60  f o r S0Br  2  has been t r i e d by means o f e l e c t r o n d i f f r a c t i o n ^ * , b u t n o t a l l o f the parameters  have been d e t e r m i n e d .  From those t h a t were  o b t a i n e d , however, a p y r a m i d a l s t r u c t u r e i s e v i d e n c e d .  - 15 -  A l l molecules would y i e l d s i x i n f r a r e d and Raman active modesfour o f class A' and two o f class A". To v e r i f y such molecular symmetry, v i b r a t i o n a l data have been obtained f o r each  57>62-67^  thionylhalide  mostly v i a Raman spectra, which have  shown the expected number and class o f appropriate vibrations f o r G_ symmetry (except f o r SOF where one A  1  2  detected).  v i b r a t i o n has not been  Again, a pseudo-tetrahedral molecule with a lone p a i r  of electrons occupying one coordination s i t e may be assumed f o r 23 the thionylhalides  3.  .  Physical and Chemical Properties Of those properties that have been reported f o r the t h i o n y l -  halides, one i s the dipole moment f o r SOP^ and SOClg.  These  values are 1.62 ^ and 1.58 °^ Debye, respectively, considerably lower than those measured f o r selenium(lV)oxy-halides.  Vapor  pressure data has also been obtained f o r each o f the  53 55 thionylhalides  '  68  '  with the vapor pressure equation o f  SOP^ being expressed as  30.333-8.1053  log p =  l o g T -1908.4  T and that o f S0C1 being 2  l o g p = 7.60844 -1648.2 ,  T Trouton constants have been determined as well f o r the d i f f e r e n t halides S0F  2  53,55 with  the f o l l o w i n g values being respectively 22.6 f o r  , 21.4 f o r S0C1 and 25.2 f o r S0Br . suggesting that the f l u o r i d e 2  2  and the chloride are " normal " l i q u i d s whereas the bromide should be considered to be s l i g h t l y associated i n the l i q u i d s t a t e .  In a d d i t i o n  - 16 -  the d i e l e c t r i c constant and s p e c i f i c conductivity f o r 69 S0C1  2  have been measured  3.5 x 10~9 aho cm  -1  and are 9 . 0 5 (22° C) and  7  (20° C) r e s p e c t i v e l y .  On the basis o f  f r e e z i n g point d e t e r m i n a t i o n s ^ i t has been reported that only weak comyounas are formed between SOCI2  S i C l ^ or  T i C i ^ , these molecules readily d i s s o c i a t i n g upon warming to l i q u i d s and capable o f being independently separated. I t might also be pointed out that the formation o f no compounds i s indicated i n the systems studied i n v o l v i n g 19 S0C1 and e i t h e r CCl^, AsCl^ o r SnCl^. 2  F NMR studies,  however, have provided evidence f o r complex formation between S 0 F  2  and SbP^ where, i t must be noted, that the bond  between the two molecules i s through the oxygen atom*^. 19 Further  P NMR studies o f S 0 F with AsF^ reveal that only 2  a very weak complex i s formed, and at that mainly at low  71 temperatures  . Radiochlorine exchange reactions between  both iiH^Cl and SbCl^ with S0C1 have y i e l d e d the maximum 2  upper l i m i t s f o r exchange h a l f - t i m e s ^ l as being between ~>8 and ~13 minutes.  In every case complete exchange was  concluded to have occurred f o r l a b e l l e d chloride ions, whether i n i t i a l l y as part o f S0C1  In the case o f the pseudothionyl50 halide, S0(S0^F) , only l i m i t e d information i s available ' . 2  or not.  -  2  19 In i t s characterization, a  F NMR signal has been observed  i n the region t y p i c a l f o r f l u r o s u l f a t e s , - 52.7 ppa r e l a t i v e to CFClj, and i t s i n f r a r e d spectrum recorded.  The compound  appears as a colorless l i q u i d at -22°C with a vapor pressure  - 17 -  of < 1 t o r r a t 20°C, f r e e z i n g to a glass a t very low temperatures (Please see Table 3 f o r a compilation o f p h y s i c a l data f o r the t h i o n y l - h a l i d e s )  D.  Mixed Oxyhalides  o f S u l f u r and Selenium  There are two main classes o f compounds that may be included i n t h i s group o f mixed oxyhalides.  These are when s u l f u r o r  - r e p r e s e n t e d by E - f o r m compounds o f t y p e s ( l ) EOXX'  selenium  and (2) EOgXX', where X and X' are d i f f e r e n t halogens.  Bie l a t t e r  c l a s s ( 2 ) , which i s o f minor i n t e r e s t a t t h i s time, inolude SOgClP and SC^BrF which have been w e l l investigated and are apparently unique and stable compounds e x i s t ; i n f a c t , only SeOgFg * simple oxyhalides.  8 k  n  o  w  n  No selenium analogues  *o e x i s t even among the p o s s i b l e  However, from c l a s s ( l ) , the most  substantiated compound i s S0C1P.  I t has been reported as being  prepared i n 20$ y i e l d by the a c t i o n o f SbFj and SbCl^ on SOClg  55  » o r i n the r e a c t i o n o f IP^ with SOClg upon heating.  73 % J  Also suggested was the obtaining o f SOBrF by the i n t e r a c t i o n of S0Br and a halogen-fluoride such as IF^, but no synthesis by 2  t h i s o r any other method has thus f a r been reported.  .  74  SOBrCl was f i r s t olaimed to have been obtained by Besson i n 1896, 53 but disclaimed l a t e r by Mayes and Partington  who t r i e d to reproduce  the experiment and i s o l a t e the compound by f r a c t i o n a l d i s t i l l a t i o n . The issue seems to be s t i l l very much i n doubt.  SO^F d e r i v a t i v e s  TABLE  3  Some P h y s i c a l Constnnts o f SOXp - Tyne Cowoound.s  S0F ra«?l.t.in,T p o i n t (°C)  -U0.5  boiling p o i n t (°C)  -43.8  S0C1  2  '  -10 5  3.5  (:Tiho  @ 20°C  dielectric cons t.mt  Trou ton con;- t.-tnt  r>r<v s u r e eqn.' t i on 1  5  4  x 10- >  snpci f i c conductivity  di-Qolf! mo-n^nt (Debve)  •colorless CA l i q u i d ® -22 3  S*13°C  (  cn~l)  2  7 7 3 t o r r 5^ .',.0 t o r r 54  5 5  (G^)._2^>Al_^ 1.780 i . © - 100°C" 5  3  -52  140 decomn. density (g/cc)  S0(S0 F)  ?  5U  5 4  5 4  S0Br  ?  l  6  9  @ 22°C 5  1.62  P  , 55 ??..6 '  lo(? t>=  21.4  lop;  5  5  25.2  < 1 t.nrr  0=  60 ^'44  3 0 . 3 3 - 3 . 1 0 5 3 1 log!  7.  - 1903.U/T 6R  - l6-'43.?/T  5 3  cp  @  _'!2°C ^  0  -19  may  -  also be included i n this d i s c u s s i o n since the f l u o r o s u l f a t e  group can be classed as a pseudc— halogen.  ,  Indeed, the existence o f  .  a compound of the type SOCl^SO^F) was evidenced by Des Marteau; however, a pure product was not obtained. Very l i m i t e d information i s available on analogous mixed halogen Se-0 d e r i v a t i v e s .  1961  Yarovenko et a l claimed i n  the f i r s t preparation of SeOBrCl from S e ^ r ^  Se0  2  and  75 Cl  2  i n 15/a y i e l d .  The SeOBrCl was reportedly obtained by  f r a c t i o n a l d i s t i l l a t i o n under reduced pressure.  Measured  properties included only i t s b o i l i n g point and density. 1950  Wiechert mentioned a reaction of S e 0 C l  2  In  with anhydrous HF,  14 the remaining product a f t e r which contained chloride. It was also stated that the reaction " had the appearance as i f great quantities of SeOCIF were formed. "  G i l l e s p i e et a l  77 i n 1965  using  Se nuclear magnetic resonance  techniques,  studied equisolar binary mixtures of SeOF with SeOCl 2  2  and  7 SeOBr  2  .  Evidence was obtained only f o r SeOCIF by the  presence of an additional ^ S e  KMR  signal d i f f e r e n t from  those f o r the s t a r t i n g materials o f the mixture.  The  p o s s i b i l i t y of SeOBrCl being formed i n the equilibrium of SeOCl  2  and SeOBr was 2  based upon the presence of a  single broad peak located between those measured f o r the two parent compounds i n d i c a t i n g rapid ligand exchange. No evidence was  found by these techniques, however, f o r  a s i m i l a r SeOBrF species being formed, with only the  resonances  50  - 20 -  f o r SeOP and SeOBr being observed. 2  2  The compound SeOCl(SOjF)  also was apparently obtained i n an equimolar reaction o f Se0(S0jF)  2  and SeOCl  2  as reported by Carter.  ^  Evidence f o r the existence of the mixed compound i s promoted mainly from "^F and  77se  resonances as well as from  i t s v i b r a t i o n a l spectrum.  These data indicate the presence o f  a separate compound apart from both parent compounds.  E.  Bonding In Thionylhalides Based on the v i b r a t i o n a l frequencies obtained from Raman  spectra, force constant calculations have been c a r r i e d out  76 f o r the thionylhalides oxygen compounds.  as well as f o r other r e l a t e d s u l f u r -  77>78,79  rp  ne  progressively stronger S=0  bond trend as expressed by these force constants f o r t h i o n y l h a l i d e s , as the halide varies from Br to F, r e f l e c t s the greater a b i l i t y of S0F  2  to engage i n multiple bond formation between  s u l f u r and oxygen, than i s the case f o r S0Br . 2  To explain  t h i s , a dative bond formation i n v o l v i n g the electrons i n oxygen's 2p energy l e v e l s and the empty o r b i t a l s o f 8 s u l f u r ' s 5d 2 or 3d 2 2 energy l e v e l s have been proposed- ^Ca),20 z x-y generally termed pn-»dit bonding. More s p e c i f i c a l l y , 81  Cruickshank  discusses the evidence f o r such pTT-^d-n-  bonding between oxygen and elements with vacant 3d o r b i t a l s , such as S i , P, S, and CI, i n tetrahedrally or pseudotetrahedrally coordinated polyhedra on the bases o f available molecular structures.  - 21  -  The results of this axe b r i e f l y summarized as follows. The element-oxygen bond, S-O,  i n thionylhalides can  be described by the three different resonance forms  X  S =  s  0  =  80(a)  +  0  X (a)  (b)  (c)  When X i s an electron donating group, (a) i s the most probable resonance structure. An increase i n electronegativity f o r X w i l l favor mainly (b) and perhaps ( c ) .  This effect can be  observed by noticing the differences i n ( l ) S=0 bond distances and molecular bond angles, (2) S=0 stretching frequencies corresponding stretching force constants, (3)  and  dipole moment  values, which w i l l r e f l e c t a decreasing a b i l i t y f o r oxygen to act as a donor and s u l f u r to act as an acceptor going from (a) to (b) to ( c ) , and (4) intermolecular association, which w i l l decrease with decreasing probability of the polar structures. It follows f o r the thionylhalides and related molecules that t h e i r a b i l i t i e s to function as oxygen donors w i l l decrease i n the series (CH^SO > Br S0 2  >  ClgSO >  PgSO.  The  S=0  stretching frequencies w i l l increase at the same time as the bond distances decrease i n the series. This model has been. 82 extended to a large number of S-0 compounds.  Experimental  evidence i s compiled i n the form of molecular structures and  S»0  -22 -  Trouton constants, as well as the v i b r a t i o n a l frequencies and force constants, some values of which have been mentioned e a r l i e r (please see s e c t i o n I.C.).  In a d d i t i o n to these data a c o r r e l a t i o n  has been made between force constants and bond lengths, besides one between bond lengths and bond orders, as c a l c u l a t e d by the authors.  8  2  The f a i l u r e to obtain stable oxygen-donor type complexes with good acceptors such as SnCl^ f o r S0C1 4 ° , and BF^, AsF,_ 7 1 2  70 and SbPjj p-TwdTT  f o r S0F may also be a t t r i b u t e d to i n t e n s i v e 2  bonding f o r thionylhalides i n general.  Proton acceptor a b i l i t i e s i n strong protonic acids, where the proton i s viewed here as the simplest Lewis acid, into the same category as oxygen-donor a b i l i t i e s .  fall  Uhereas  diorganylsulfoxides-for example, (CgHcj^SO - behave as strong bases i n B^SO^  ,  SOP2 would have to be considered as being only  very weakly protonated, i f at a l l , based upon the r e s u l t s for S0  2  obtained  i n superacid media (KSO^F, SO^, SbF- mixture), the strongest  protonating agent avialable, which show a complete l a c k o f evidence  84 f o r the protonation o f S0 . 2  This view departs i n one aspect from the o r i g i n a l ideas o f Cruickshank, and subsequently  also G i l l e s p i e and Robinson.  By p o s t u l a t i n g p a r t i c i p a t i o n of two of s u l f u r ' s 3d o r b i t a l s , the maximum-n bond order was r e s t r i c t e d to 2, and the 82 t o t a l bond order was l i m i t e d to 6. i s achieved as i n the case o f 0 * 2 s  2  This maximum value w  h  e  n  sulfur-oxygen  - 23 bond order i s described as being 2.  I t i s therefore a r b i t r a r i l y  assumed that the bond order f o r the S-F bond i n S 0 F 2  2  i s 1.0.  This, however, i s contradicted by the r e l a t i v e l y short s u l f u r f l u o r i n e bond distances and p a r a l l e l trends i n the S-F s t r e t c h i n g frequence and s t r e t c h i n g force constant as noted f o r those trends between s u l f u r and oxygen. evidence that some  p-rr-^d-TT  There i s , i n f a c t , good  contribution w i l l have to be invoked 81  i n order to explain the S-F bond.  For this reason i t i s  preferred to consider the S-0 bonds as doubtlessly strengthened v i a p T T —s»dTT bonding, but i t i s found that the assignment of bond orders are s l i g h t l y misleading. F.  Bonding i n Selenium(lY)Oxyhalides This s e c t i o n w i l l center mainly around the f o l l o w i n g points: a)  Is there any evidence f o r p - r r - ^  d-rt  bonding i n Se-0  compounds? b)  How can differences i n p h y s i c a l properties best be r a t i o n a l i z e d based on bonding descriptions?  c)  What differences i n chemical behavior are found and are expected?  Since s e c t i o n I.B. has shown strong s t r u c t u r a l analogies between Se-0 and S-0 compounds of the type discussed ( t a k i n g i n t o consideration the presence of a stereochemically active lone 23 p a i r of eleotrons i n both thionyl-.and selenium(lV)oxy-halides) the o r b i t a l symmetry requirements  f o r pTT->d-rr bonding are met.  The difference must be seen i n the involvement  of 3d o r b i t a l s  ,  -  24  -  on s u l f u r versus 4d o r b i t a l s on selenium as the acceptor o r b i t a l s . I t i s generally assumed e s p e c i a l l y f o r element o f groups IV and VI a,  8 0  ( ),( ) b  c  that 4d o r b i t a l s are higher i n energy and are  also more d i f f u s e than t h e i r 3d counterparts.  This means  p-rr-s> d-rr back-donation w i l l be l e s s e f f i c i e n t f o r selenium. This expectation i s i l l u s t r a t e d by the material provided 21 20 from structure determination and v i b r a t i o n a l spectroscopy.  '  Se-0 bond distances are found to vary i n the same way as found f o r those o f S-0 compounds;  the v a r i a t i o n again can be r e l a t e d  to an e l e c t r o n inductive e f f e c t exerted by the other atoms or 86 groups attached to Se.  Consequently,  similar variations i n  Se-0 s t r e t c h i n g modes and force constants have been observed f o r tetrahedrally coordinate selenium-oxygen compounds, as have been found f o r the ones encountered i n sulfur-oxygen compounds. IV compounds o f the type XgSe 0, strong dependence ofU on f i s noted: the observed trend i s SeO SeO 82  In  p a r a l l e l to the one found f o r sulfur-oxygen compounds. Numerically the selenium-oxygen force constants are lower than the ones o f sulfur-oxygen i d e n t i c a l ligands X.  bonds w i l l be weaker and longer.  Se0X  2  >5 8  i n compounds with  I t can also be seen that both sets of force  oonstants were derived by the same methods.  proposed  20  e a r l i e r f o r S0X  compounds, namely  2  This means the Se-0  The three resonance structures  type molecules w i l l be much the same f o r  - 25 -  Se-0  Se = 0  -s  ^  Se = 0 ^  (a) Contributions Se-0  (b)  (c)  from ( a ) , however, w i l l be f a r more dominant i n  compounds than f o r S-0 compounds with respect to molecular  bonding.  This i s r e f l e c t e d i n empirical r e l a t i o n s h i p s between  the s t r e t c h i n g force constants i n i d e n t i c a l sulfur-oxygen and 87 selenium-oxygen compounds as proposed by Paetzold, which may be w r i t t e n as  f  f  SO  = 1.687«f  SeO  SeO " ° -  5 9 3  - 2.30 and  - 30 * f  1  3 7  '  and i s i l l u s t r a t e d i n Figure 1. The selenium-oxygen bonds are evidently"more polar than the sulfur-oxygen bonds i n comparable compounds. to l e s s e f f i c i e n t p K ~ » d - r r bonding rather than  That t h i s i s due  <T bonding  e f f e c t s is^evident from the e l e c t r o n e g a t i v i t i e s f o r s u l f u r and selenium which are almost i d e n t i c a l (Pauling s c a l e : S = 2.58 and Se = 2.55, Allred-Rochow s c a l e : S = 2.44 and Se = 2.48). C ) 80  d  Because o f a l l t h i s , Se-0 compounds are b e t t t e r oxygen donors than the corresponding S-0 compounds, and i n addition, selenium can also function as an acceptor i n Se0X2 compounds, whereas no examples f o r S0X  2  compounds acting t h i s way are known.  Furthermore, a stronger intermolecular  a s s o c i a t i o n f o r SeOXg  - 26 -  CONSTANTS FIGURE 1  - 27  -  compounds i s expected with a p o s s i b i l i t y of a h e t e r o l y t i c of associated molecules  i n t o conducting fragments.  are substantiated by p h y s i c a l data, such as  cleavage  points  These  melting points, b o i l i n g  points, Trouton constants and s p e c i f i c conductances, which have been discussed e a r l i e r . To help c l a r i f y the above claim, several examples are  now  shown i l l u s t r a t i n g ( l ) SeOX compounds as donors, and (2) SeOX^ 2  compounds as acceptors.  For case ( l ) there i s much data, since  several adducts have been reported f o r the selenium(lV)oxyhalides. Even f o r SeOF , a complex SeOF - 17bF^ i s reported. 2  2  The  crystal  structure has established that donation from oxygen occurs, rather than from f l u o r i d e - i o n - t r a n s f e r and NbFg i o n formation.  A similar  a d d i t i o n compound has been prepared between SeOClg and SbCltj with 1:1 also reported.  stoichiometry where i t s c r y s t a l structure i s 8Q/  With SnCl^ the stoichiometry i s f o r a di-adduct  of SeOClg, i n c l u d i n g c i s octahedral environment around the t i n atom.  ^°  Other complexes with SeOCl,, are also mentioned  i n the l i t e r a t u r e . ^  SeOBr has been found to y i e l d an  8  2  adduct with SnBr. of the form S n B r , ^ SeOBr., 4 4 2' 1 1 0 ,  where  S n Mossbauer and v i b r a t i o n a l spectra have i n d i c a t e d donation from  oxygen and c i s octahedral configuration f o r t i n .  I t i s noteworthy  at this'time to point out that of the two possible modes of complex formation a) a X SeO + liX^ 2  and  >  (X^eO-*^  - 28 -  b) m X SeO + 2  >  (XSeO)J  m  (MX  only type a) i s found to occur.  )- , m  n f a  For case (2), where SeOX  2  compounds act as acceptors, a large number of complexes o f SeOClg are reported. ^  8  The c r y s t a l structure o f SeOCl «2 C5H5N 2  indicates a pseudo-octahedral environment f o r selenium.  ^  2  In 38  addition, a complex with SeOBr and dioxane has been mentioned. 2  SeOX compounds can act as halide i o n acceptors according to 2  KX + SeOX where X may be F or CI.  2 6  '  2  >- K(SeOX ) 5  9 5  V i b r a t i o n a l analysis indicates C_ symmetry i o r the SeOXr i o n , a j and thus a d i s t o r t e d pseudo-trigonal bipyramidal structure with X i n both of the a x i a l p o s i t i o n s .  Evidence o f (inseparable  mixture products o f the type K (SeOCl F5_ ) has also been obtained. n  n  26  - 29 -  II.  A.  Chemicals  1.  Reagents  EXPERIMEETAL  Except f o r selenium(lV,)oxy chloride, SeOClg, a l l of the reagents used i n the reactions of general type SeOXg + SeOYg^—2SeOXT  were not comnercially available and  other means had to be found to obtain them.  Such being the case  preparations f o r most of them i n the laboratory were conducted with s t a r t i n g materials e a s i l y acquired from commercial  sources  or s h e l f stocks, a.  Commercial  1) Elemental selenium, Se, was supplied by B r i t i s h Drug Houses,Inc.(BDH) at>99fo p u r i t y .  To ensure the absence of a l l moisture the Se  was also crushed and dried at 140°C f o r at l e a s t s i x hours under vacuum before using.  In one case.the vitreous form of Se was  used, which required heating the Se to a melt i n a crucible and pouring rapidly into a beaker of cold water to achieve l o n g b r i t t l e 56 strands which were then crushed and dried f o r the reaction-^ . 2) Fluorine, F_, 9&p pure, used i n several of the preparations  - 30 -  was obtained from A l l i e d Chemical Corporation, and passed through a sodium f l u o r i d e , ITaP, metal trap to remove hydrogen f l u o r i d e , HP*  No attempt vas made to remove the other impurities  commonly present i n the P  2  such as 0 > 2  Ng o r OFg.  A high  pressure Autoclave Engineering valve and Crosby high pressure gauge regulated the flow o f P  2  from the c y l i n d e r .  3) Elemental bromine, B r , was supplied by BDH at g  > 99.0$  p u r i t y and used without f u r t h e r p u r i f i c a t i o n . 4) The nitrogen, N , used i n maintaining i n e r t atmospheres i n 2  the drybox and reactors^ was of L grade and supplied by Matheson o f Canada, L t d .  5) Selenium dioxide, Se0 , was also obtained from EDH at 2  > 99.0$ p u r i t y , but was heated to 150°C i n vacuo f o r 12 hours i n order to remove any traces o f moisture that may have been present as supplied. »5*> 10,  6) S u l f u r t r i o x i d e , SO^, wa3 purchased from Baker and Adams on, A l l i e d Chemical Corporation, as "Sulfan" (purity not given) and used without p u r i f i c a t i o n . 7) Selenium(IV) oxychloride, SeOClg, was obtained from EDH i n a glass-sealed v e s s e l , and used without p u r i f i c a t i o n . The p u r i t y o f the straw-yellow colored l i q u i d was  > 97.5$  8) The potassium bromide, K3r, was o f reagent grade and was' supplied by Baker and Adamson as c r y s t a l s , which were subsequently crushed and dried at 150°C before use.  - 31 -  9)  Reagent grade carbontetrachioride, CCl^, was  stored over  Linde 5A Molecular Sieves f o r 48 hours before use. 10)  Pre on 11, trxchjiorofluoroaethane, CPC1-, used as an external 19  reference i n  P IIMR experiments, was  obtained from Matheson of  Canada, Ltd., with the p u r i t y not given, b.  Prepared  1) P e r o x y d i s u l f u r y l d i f l u o r i d e , S-O-P , was prepared i n 500g & o 2 quantities by the general method o f Shreeve and Cady A f t e r having passed through a KaP trap, p was mixed with dry N  5  ^  and SO  reactor.  3  i n a s i l v e r ( l l ) f l u o r i d e , AgP , catalyzed furnace 2  0  Please see section I I . B. 2. a.  the S^O^F^ was  A f t e r reaction at 180 C  trapped i n -78°C dry i c e traps and l a t e r p u r i f i e d  by f r a c t i o n a l d i s t i l l a t i o n to y i e l d pure product as indicated by i t s 1TMR and gaseous i n f r a r e d spectra.  Any unreacted  SO^  was removed by e x t r a c t i o n with oleum, concentrated B^SO^. 2)  Selenium(lV) oxyfluorosulfate, SeO(SO^P) > 2  according to'Carter and Aubke. ^  w  a  s  prepared  T y p i c a l l y 7.5 g (45.3 a moles)  of SeOClg was weighed i n t o a pyrex Erlenmeyer reactor i n c l u d i n g a T e f l o n coated magnetic s t i r r i n g bar, i n a drybox. was  S 0gP 2  2  then d i s t i l l e d in. vacuo onto the SeOCl i n small amounts 2  and s t i r r e d .  The chlorine, C l , that was 2  evolved was  rapidly  pumped o f f to prevent the formation of chlorinemonofluorosulfate, C10S0 F, as a side product. The process was repeated u n t i l no further S O^P was taken up, and the i d e n t i t y of the product 2 o 2 2  - 32 -  •was checked by weight increase appropriate f o r a quantitative transformation to Se0(S0^F)  2  from the SeOCl  as well as by i t s  2  Raman spectrum.  3) Seleniumtetrafluoride, SeF^, was prepared i n amounts o f 15-20g 19 by passing a slow stream of F Roughly  2  d i l u t e d with dry N  2  over d r i e d Se.  20g o f Se was f i n e l y ground and evenly spread on the f l a t  base o f the main reactor which was purged o f a l l atmospheric a i r and moisture by a flow o f dry N  2  overnight. Then the reactor  was placed i n a -10°C s a l t - i c e slush bath.  The next two c o l l e c t i o n  traps f o r the SeF^ were held at -30°C which allowed the unreacted F  o J  c.  N  and any SeF  A  formed as byproducts to pass through the flow  O  2  type system.  A t h i r d trap equipped with vacuum stopcocks followed,  and was used only as an intermediary storage vessel f o r the SeF^ before i t was f i n a l l y transferred i n vacuo into a monel storage vessel.  The colorless l i q u i d product was i d e n t i f i e d by comparing  i t s Raman spectrum to the one reported i n the l i t e r a t u r e f o r SeF^. 4)  l6.65g of selenium(lY) oxyfluoride, SeOF , was generated by 15 2  heating SeF^ with an excess o f SeOg.  J  In p r a c t i c e 8.4g  (75.5 m moies) o f dried SeOg was placed i n a two-part monel reactor and 9.7g (62.6 m moles) o f SeF^ was transferred i n vacuo onto i t . The reactor was then closed to the atmosphere and heated i n an o i l bath to 100°C f o r 12 hours. also stored over the Se0  2  The c l e a r colorless liquid,which was  i n i t s reactor, was found to be SeOF  by i t s NMR and Raman spectra.  2  - 33 5) Selenium(lV) oxybronide, SeOBr^, was prepared i n 30.5g (1x9.0 m moles) b a s i c a l l y as described by Lehner.  quantities  A s l i g h t excess o f Se, 4.80g or 60.8 m moles Se, was mixed thoroughly i n the drybox with b.JjOg (59.5  m moles) Se0 , and 2  put i n a reacor f i t t e d with a dropping funnel.  A large excess  of B r , 30 ml at 0°C, was then added v i a the funnel - the B r 2  2  being cooled to partly absorb the heat of formation of S e ^ r g , an intermediate i n the formation of Se03r . 2  reactor was placed i n an i c e bath, 0°C. Br  2  2  the  A f t e r the f i n a l addition o f  the reaction products were warmed to room temperature and mixed  thoroughly. Br  As i t was,  at  Pure Se0Br could be obtained by pumping o f f the excess 2  -30°C i n vacuo ana f i n a l l y vacuum subliming the crude Se0Br  2  at room temperature to long yellow c r y s t a l l i n e needles whose melting point was  2.  44«5°C ( l i t 41.7°C , and 45°C ) . 4 5  1  Products As has already been implied, the reactions giving the products  to be described i n this section, except xor the salt-type reaction y i e l d i n g KSeOBr^, are e q u i l i b r i a reactions SeOX + Se0Y ^ - ^ 2Se0XT. 2  2  In a l l cases of t h i s l a t t e r type, equimolar  amounts of both reagents were to be added, calculated f i r s t by volume through density values when applicable, and l a t e r checked by mass measurements.  - 34 -  a.  Equilibria-type  1)  Seleniun(lV) oxyfluoro(fluorosulfate), SeOF(SO^P),  has been obtained f o r the f i r s t time by combining •with 5eOP .  Initially  2  0.775g (5.83  SeO(3C F )  ?  a moles) was d i s t i l l e d  i n vacuo on a monel metal vacuum l i n e into a Kel-P reaction vessel. 3e0P  2  Then  1.700g (5.80  m moles) Se0(S0^?) was 2  added to the  i n a dry box v i a a 1.00 ml pipette and " pi-punp" assembly  (Please see II.B.5.e.) - the mass of Se0(S0,P) balance located within the drybox.  2  determined by a  The mixture was shaken even  though the s t a r t i n g materials mixed readily to form a yellowtinged product whose v i s c o s i t y was intermediate between that o f SeOP and SeC(S0jP) . 2  2)  2  A sample of seleniun(lV) oxychlorofluorosulfate, SeOCl(SO^P),  was prepared i n a two-part pyrex reactor where f i r s t 2.202g a moles) of Se0(S0^P) was weighed into the reactor. 2  1.241  (7»52  Subsequently  g (7.51 m moles) o f SeOCl was added with the pipette 2  assembly to the correct quantity by volume and mass - the whole operation being conducted i n the i n e r t atmosphere  o f the drybox.  Only a f t e r vigorous mixing did the two l i q u i d s become homogeneous, the  v i s c o s i t y of which was greater than that of e i t h e r o f the  s t a r t i n g materials. 3)  The corresponding new bromo compound, selenium(IV) oxybromo-  f l u o r o s u l f a t e , SeOBr(SO^P), was made by f i r s t weighing  1.142g (3.91  ci moles) Se0(S0~?) into a two-part glass reactor, 2  and then adding 0.998g (3.91 n moles) of f i n e l y crushed Se0Br  2  in  - 35 -  the drybox w i t h the a i d o f the balance.  Upon f i r s t a d d i t i o n o f  the reactant3 a reddish c o l o r was imparted t o the SeC^SO^F),, but eventually a hard yellowish-orange c a k e - l i k e substance appeared at the bottom o f the reactor.  A f t e r heating to 105°C, however,  s o l u t i o n o f a l l reactants was e f f e c t e d to a l i g h t  crimson-  red l i q u i d which eventually turned to a homogeneous yellow wax upon c o o l i n g to room temperature. 4)  The r e a c t i o n o f SeOF w i t h SeOClg to form s e l e n i u a ( I V ) 2  7 o x y c h l o r o f l u o r i d e , SeOCIF,  proceeded by the d i s t i l l a t i o n o f  1.900g (14.28 m moles) o f SeOF i n t o a K e l - F t r a p , and 2  followed by the a d d i t i o n o f 2.350g (14.20 m moles) o f SeOCl v i a the p i p e t t e assembly i n the drybox.  2  The two reactants mixed  e a s i l y to give a c l e a r y e l l o w i s h l i q u i d . 5) Although the p r e p a r a t i o n o f selenium(rv) ojcybi-owGchloride, SeOBrCl, has been claimed p r e v i o u s l y by the a d d i t i o n o f SeOg  75 and C l to S e B r , 2  2  2  the seemingly  SeOCl t o SeOBr was employed. 2  simpler method o f adding To begin, 1.662 g (6.52  2  m moles) o f f i n e l y ground SeOBr was weighed i n t o a two-part 2  pyrex r e a c t o r c o n t a i n i n g a Teflon-coated magnetic s t i r r i n g bar; 1.085g (6.54 m moles) o f SeOCl was added w i t h the p i p e t t e 2  assembly - a l l i n the drybox.  The SeOBr d i d not t o t a l l y d i s s o l v e 2  i n the SeOCl u n t i l the reactants were heated to about 5O°0 2  (even w i t h s t i r r i n g ) where upon a dark red-brown s o l u t i o n was obtained wtiich remained so a t room temperature.  - 36 -  6)  In the attempt to make selenium(lV) oxybromofluoride, SeOBrF,'  3.250g (24.OO m moles) o f SeOF into a Kel-F tube, and 6.058g Se0Br was added 2  w  a  s  o  n  c  e  2  (23-70 m  again d i s t i l l e d i n vacuo moles) o f f i n e l y  i n the drybox by weight.  crushed  The SeOBr,, f a i l e d to  t o t a l l y dissolve i n the Se0F , although i t d i d impart a 2  red-orange color to the l i q u i d phase.  A f t e r heating the mixture  to 50°C, however, an intensely dark, almost black, s o l u t i o n was seen with a l l o f the Se03r  2  dissolved - remaining so at room  temperature. b. l)  Salt-type The s a l t potassium oxotribromoselenate(lV)> KSeOBr^, was  prepared by adding an excess, 2.683g (l0.52~ia moles) o f f i n e l y crushed Se0Br to 0.513g (4.31 m moles) o f powdered and dried KBr 2  i n a f l a t bottomed two-part pyrex reactor, the Se03r the drybox.  2  added i n  The raix+.rre was then heated to 55°C and s t i r r e d  (with a magnetic Teflon-coated s t i r r i n g bar) f o r an hour.  The  r e s u l t i n g products were then put into a vacuum f i l t r a t i o n device and washed with dry CCl^ u n t i l the disappearance of the reddish color i n the washings - the color i n d i c a t i n g dissolved Se03r CCl^.  2  i n the  The product obtained was a light-yellow powdery s o l i d .  B.  Apparatus  1.  Vacuum Lines Standard high vacuum techniques were employed throughout the  preparations o f a l l compounds because o f t h e i r highly toxic and hygroscopic behaviour.  In order to achieve and maintain  - 37 -  a necessary vacuum f o r the l i n e s , a Welch Duo-Seal Pump, Hodel I4OO, was used, capable of obtaining a vacuum o f 10"^ torr.  The pump was connected to the l i n e s through a l i q u i d  cold trap which c o l l e c t e d stray v o l a t i l e materials before they could be drawn through the pump. a.  Glass  The main manifold of the glass vacuum l i n e was made o f pyrex tubing, 65 cm long and 20 mm diameter, sealed o f f at one end and connected to the cold trap by a Fischer-Porter 4mm glass and t e f l o n stopcock and B19 ground glass cone and socket.  Four a d d i t i o n a l  Fischer-Porter stopcocks served as i n l e t s to the manifold to which reactors and other kinds o f apparatus could be attached through BIO sockets.  Pressures i n the manifold could be  measured by a mercury manometer attached through a BIO cone. b.  Monel  In cases where reagents attacked the glass o f the previously mentioned vacuum l i n e , a monel l i n e had to be used-  The metal i t s e l f was  a copper-nickel a l l o y fashioned into tubing-j-" o.d. and l/32" wall thickness.  The l i n e was 70 cm long and was attached  to the cold trap v i a a "Cajon" glass-metal connector,  Columbia  Valves and F i t t i n g s , Vancouver, B.C., B19 cone and socket, and a Whitey-type- valve IKS4.316, Whitey Research Tool Co., Oakland, C a l i f o r n i a .  At various i n t e r v a l s T-pieces s e r v i n g  as i n l e t s f o r the reactors, e t c . were s i l v e r soldered into the line.  At each o f these i n l e t s was attached a Whitey valve,  connected by Swagelok f i t t i n g s and T e f l o n f e r r u l e s , Crawford  Fittings  - 38 -  (Canada) Ltd., Niagara P a l l s .  A Kontes thermocouple gauge, model  2A, Televac, The Predricks Co., was used as a means to check  3 leaktightness and pressures of 10 2.  to 1 t o r r .  Metal Fluorine Line For the preparations of S 0 g F 2  2  and SeF^ i t became necessary  to use a system suitable f o r flow reactions. The f l u o r i n e l i n e used consisted b a s i c a l l y of a system of copper tubing and Whitey, Hoke, and Autoclave Engineering valves, the l a t t e r two supplied by Hoke Inc., C r e s k i l l , New  Jersey, and Autoclave Engineering Inc., E r i e , Perm.,  respectively.  Fluorine was brought i n through a NaF trap,  which could be regenerated by e l e c t r i c a l heating to remove the HF trapped within, and could e i t h e r be mixed with dry N  or not.  2  A f t e r t h i s , the flow of f l u o r i n e could be l e d d i r e c t l y to a reactor furnace where another i n l e t would allow other gases to mix -with the f l u o r i n e a s in.the preparation of S 2 ^ 6 2 J F  3  o r  ^  cou  --* 1  <  b e  l e c  * *°  another type of reaction apparatus bypassing the high temperature reactor. (See Figure 2) a.  S 0gF 2  2  type  In the case of the 3 0 g P 2  of N  2  2  reaction, F  was mixed with a stream  2  and SO^ i n the furnace reactor, heated to — 1 8 0 ° C by a  series of e l e c t r i c a l windings, by a variable rheostat.  the temperature being c o n t r o l l e d  The r e s u l t i n g products then passed i n t o a series  o f traps, the f i r s t of which was maintained at room temperature to c o l l e c t any solids (.polymeric 50-^) and the rest were heid at dry i c e temperature (-78°Cj to c o l l e c t the S u F ^ but allow FSo^F, 2  b  CrO'-by Prcoourc Guage  N a F Trap  1  To Flowmeter Copper  •8-  Glass  F  2  rh  , 9 c m  Jl—rh.  1_J  L  -20cm-*-  To F^ cylinder  Outlet  SOOml. Pyrex Flask  Copper  Reactor  Glass To S o d a - lime Trap  (J) •0-  Whitey H  o  k  e  4  1  Valve 3  B  B 3 4  B34  34  Valve  -Fluorolube O i l T u b e  pp] A u t o c l a v e E n g i n e e r i n g I—I Valves A FIGURE 2  M E T A L FLUORINE LINE  B  C  INCLUDING C A T A L Y T I C S ^ F ^ ,  REACTOR  - 40 -  Hg, and unreacted F  2  to pass through.  The whole system  was  followed f i n a l l y by a bubble-type flow meter f i l l e d with Fluorolube o i l , Hooker Chemical Corp., Niagara F a l l s . A l l connections between traps were made with BIO cones and sockets. (Please see F i g . 2) b.  SeFj type  For the generation of SeF^, F^ d i l u t e d with  was entered through  a Fluorolube o i l bubble-type flow meter, (attached with Swagelok f i t t i n g s to the main F  outlet) i n t o a t w o - l i t e r f l a t bottomed  2  f l a s k , i t s e l f attached to the flow meter with a B19 socket.  cone and  To this main reactor f l a s k were connected two primary  c o l l e c t i o n bulbs v i a B19 10 cm l o n g and 40 mm  cones and sockets.  These bulbs,  diam., were immersed i n t r i c h l o r o e t h y l e n e -  dry i c e baths of -30°C to trap the SeF^ but allow F , N 2  SeF^ to pass through.  2  and  Next i n the l i n e , an intermediary trap,  50 cm long and 50 mm  diameter, equipped with two 4 nim bore greased  vacuum stopcocks was  connected with a B19  cone and socket.  The  intermediary trap was used to c o l l e c t the SeF^ as i t transferred i n vacuo from the primary bulbs with the help of a vacuum pump, which could be attached to the l a s t trap with vacuum tubing.  Thi3 same  l a s t trap could also be attached with Swagelok f i t t i n g s to the monel vacuum l i n e previously described f o r the t r a n s f e r of the SeF^ i n t o i t s monel storage v e s s e l .  - 41 3.  Drybox The drybox used i n the course o f the experiments to exclude  atmospheric a i r and moisture was obtained from Vacuum Atmospheres Corporation (VAC), Model HE-43-2 Dri-Lab,  The n i t r o g e n used w i t h i n ,  as i t s atmosphere, was dry L-grade and was constantly being c i r c u l a t e d over molecular s i e v e s .  These sieves were regenerated a f t e r about  a month's use by a h e a t i n g u n i t l o c a t e d w i t h the drybox i t s e l f , VAC, Model HE-93-B D r i - T r a i n . 4.  Reactors  a.  Erlenaeyer  A s p e c i a l pyrex r e a c t o r (Pig.3), constructed o f a 125-ml erlanmayer f l a s k equipped with a Fischer-Porter Teflon  stopcock, and a c o n s t r i c t e d neck which could be sealed o f f a f t e r the a d d i t i o n o f s o l i d s and l i q u i d s was o c c a s i o n a l l y used.  A BIO cone allowed the v e s s e l t o be attached t o the vacuum  system. b.  Two-part Pyrex  In a d d i t i o n , a two-part pyrex r e a c t o r ( F i g . 4) was employed which c o n s i s t e d o f a t e f l o n F i s c h e r - P o r t e r stopcock connected t o a v e s s e l 10 cm l o n g and 16 mm diam., separable v i a a B19 ground g l a s s cone and socket.  A BIO cone permitted i t to be attached t o  a vacuum l i n e . c.  Two-part Monel  A t o t a l l y monel r e a c t o r ( F i g . 5) was used i n the p r e p a r a t i o n o f Se0F because o f i t s r e s i s t a n c e t o attack by SeOF , which attacks 2  pyrex r e a c t o r s .  2  The main r e a c t o r base, 10 cm deep and 50 mm diam.  E R L E N M E Y E R  R E A C T O R  Side View of F i s c h e r a n d P o r t e r Teflon Valve  Reaction Vessel FIGURE 3  « . 7  -  FIGURE 4  -  TWO-PART  MONEL  Hoke Valve ( No 431)  (  REACTOR  Monel Metal Tube Bolts to Secure L i d to Bottom Vessel Lid  n  \ P  \ 1 CC  Condenser Inlet  -4  JD  Bottom Condenser Inlet  Monel Metal Reaction Vessel (150 ml )  FIGURE 5  - 45 -  was attached to i t s l i d with s i x Allen-type screws and a t e f l o n gasket p r o v i d i n g the s e a l .  A Whitey valve was  joined to the  l i d i n l e t and the monel vacuum l i n e with Swagelok f i t t i n g s . d.  Kel-F  Another r e a c t o r of considerable use wliere glass-reacting compounds were used was a Kel-F reactor ( F i g . 6).  A Kel-F base, 15  cm  long and 15 mm i . d . , was secured by a tightening metal screw to a monel top, forming a d i r e c t vacuum t i g h t s e a l . top was joined a metal bellows-type Hoke valve. was then attached to a monel vacuum l i n e with e.  To the monel  The whole r e a c t o r  Swagelok f i t t i n g s .  SeOBr^ type  The preparation o f SeOBrg required a vessel that would exclude a t mospheric moisture outside the dry box, and be capable of being evacuated. With t h i s i n mind,a 250 ml round bottom r e a c t o r equipped with a B24  cone was  assembled  to a dropping funnel ( F i g . 7).  dropping funnel was constructed with a B19 capped with a sealed o f f B19  socket.  The  cone at the top, l a t e r  In addition, the funnel  had a t e f l o n stopcock allowing the Br^ to be added to the Se and  Se0  2  i n the reactor without contamination with stopcock grease.  A l s o as p a r t of the dropping funnel was a vacuum outlet closed to the atmosphere with a 2m  bore greased stopcook and a BIO cone  which peanitted the entire assembly to be attached to a glass vacuum l i n e .  -  FIGURE 6  46  -  SeOBr — T Y P E 2  REACTOR  - 48 -  5. Miscellaneous a.  Vacuum, f i l t r a t i o n apparatus A pyres device designed to separate l i q u i d s from solids  by vacuum pumping was also used.  This apparatus vas constructed of  a medium-grade courseness glass f r i t , 25 mm diam., located i n the middle of the assembly t o t a l l i n g 15 cir. i n length. At each end was a B24 cone capped at the top end with a sealed o f f B24 socket, and enclosed at the bottom with a 250ml round bottomed flask having a B24 socket. From each h a l f of the apparatus was an outlet conneoted to a 4 mm bore greased stopcock and f i n a l l y to a BIO cone which permitted i t to be hooked up to a glass vacuum l i n e . b.  Sublimation apparatus'  The sublimation apparatus used to purify the SeOBrg was b u i l t from a 50 mm diameter piece of pyrex tubing 20 cm i n length. Connecting the 15 cm vessel containing the material to be sublimed to the sublimation finger was a B45 cone and socket. The finger i t s e l f was a water-cooled configuration 20 mm i n diameter and extending to within 4 cm of the bottom of the vessel.  An outlet  near the top of the apparatus was achieved through a 4 nm bore greased stopcock and BIO oone. c. Molecular Sieves The molecular sieves used f o r the drying of CCl^ and f o r the drybox's c i r c u l a t i o n system were Linda chromatograph grade 5A sieves  purchased from Union Carbide, Eedondo Beach, C a l i f o r n i a . Molecular sieves f o r drying CCl^ were heated i n vacuo f o r 24 hoars at 150°C "before use. d.  Lnbrioating Grease A l l cones and sockets described i n the preceeding seotions  were l u b r i c a t e d with a l o w - v o l a t i l i t y grease designed to maintain leakproof connections i n the vacuum-type apparatus.  The grease  i t s e l f vas supplied by Hooker Chemical Co., P a i r Lawn, New as Fluorolube Grease GE-90 d i s t r i b u t e d by F i s h e r S c i e n t i f i c e.  Jersey, Co.  " pi-pump " A p i p e t t i n g device used quite regularly i n t h i s work ^and  s u i t a b l e f o r manipulation i n the dry box was made by G l a s f i m o f West Germany and d i s t r i b u t e d through Bel-Art Products, Pequannock, Hew  Jersey.  I t consisted of an acid r e s i s t a n t p l a s t i c tube containing  a t i g h t - f i t t i n g inner rod that moved up and down the tube to any desired p o s i t i o n by an externally l o c a t e d and maneuverable cogged wheel. 6.  The m^-Hrm™ volume transferable at one time was  2 ml.  Analyses The Br analysis on KSeOBr^ was done by Mr. P. Borda, UBC,  while the Se analysis on the same compound was done by A l f r e d Bernhardt Mikxcanalytisches Laboratoriua, 5251 Engelskirohen, West Germany.  Elbach uber  C. Instruments 1. Raman The Raman spectra o f the compounds were measured with a Cary 81 spectrophotometer  acoompanied by a Speotraphysios  Model 125 He-Ne l a s e r source using the ruby red exciting radiation at 6328A. The pyrex sample tubes were always f i l l e d i n the drybox and generally consisted of a tube 5 nm i n diameter with an optically f l a t end into which solids could be placed and l a t e r flame-sealed a i r t i g h t , or a bent right angle tube 10 cm i n t o t a l length and 5 nm i n diameter, equipped with a spacer to allow a r e l a t i v e l y small amount o f sample to be analyzed, which could also be sealed o f f with a torch a f t e r the introduction of l i q u i d s * A special Kel-F Raman tube was also designed and used f o r compounds reacting severely with glass. The tube, 50 mm long and 9 mm i . d . was made up with a spacer to be inserted within and eapped with a tapering top which had a small hole that oould f i n a l l y be stoppered with a t e f l o n plug ( F i g . 8). 2. Infrared P.E, 457  a.  Infrared spectrographs were recorded by means of a Perkin-Elmer Model 457 Grating Infrared Spectrophotometer i n the range 4000250 cm" . Samples were generally run neat between two windows, 1  or alternatively i n the case of solids as a Nujol mull.  Due to  the high reactivity of the samples, the windows employed i n most  - 51 -  KEL- F RAMAN CELL  l?J  l fW  1  kf  FIGURE 8  of these spectra were s i l v e r bromide, AgBr, and even these were midly attacked.  KES-5 windows were severely attacked, and  both sodium chloride, NaCl, and s i l v e r chloride, AgCl, windows did not permit s u f f i c i e n t transparency i n the lower range of the spectrum to allow the observation of important low energy frequencies, b.  P.E.  301  In fact, frequencies below 250 cm**, which needed to be 1  observed, had to be taken on a high resolution  Perkin-Elmer  Model 301 double beam Halford-Savitsky type recording far-infrared spectrophotometer. By manipulation of the various gratings, f i l t e r s , and choppers the range of detection accomplished was between 350 cm"*  1  and 90 cm" . 1  Windows appropriate f o r the transmission  of l i g h t and detection of sample vibrations were made of 1 mm pieces of polyethylene which had no  thick  absorptions i n t h i s region.  In conjunction with these windows was constructed an infrared c e l l f o r l i q u i d s and solids which had the windows separated by a 1mm  stainless steel spacer ( P i g . 9).  Liquids could be introduced  with a syringe, or solids could be placed d i r e c t l y into the c e l l , which was f i n a l l y sealed with t e f l o n plugs. 3.  Nuclear Magnetic Resonance ^ P Nuclear Magnetic Resonance chemical s h i f t s were reoorded  with a Varian Associates T60 NMR Spectrometer operating at a radio frequency of 56.433 MS  . Spectra were run of fluorine-  containing species held i n a standard NMR tube, which was f i l l e d i n the drybox and capped. A l l spectra were calibrated using  I  FIGURE  9  FAR IR C E L L  an external reference tube o f Freon 11,  CFClj, (taken as Zero)  located w i t h i n the sample tube. 4.  Conductivity The conductivity o f SeOBr as a l i q u i d was measured as a 2  function o f temperature with the a i d of a conductivity bridge, Universal Bridge Model B221-A, obtained from the Wayne K e r r Laboratories L t d . Measurements o f 0.080 /mho  to 25.34 ;umho  were read when the e l e c t r i c a l leads o f the bridge were connected to the small conductivity c e l l , (Fig.10), f i l l e d with Se0Br . 2  The c e l l was placed i n an o i l bath apparatus constructed o f a t w o - l i t e r beaker wrapped several times with asbestos paper f o r i n s u l a t i o n , and f i l l e d with F i s h e r 02 High Temperature Bath O i l which was constantly s t i r r e d by means o f an e l e c t r i c a l s t i r r e r . The c e l l , whose volume was about 2 ml to cover the two Pt electrodes, contained besides the electrodes a B19  cone  and cap which allowed the c e l l to be f i l l e d and closed to the atmosphere i n s i d e t h e drybox. These e l e c t r o d e s were p l a t i n i z e d with 'platinum black" by e l e c t r o l y s i s from a hexachloro95 platinate(_IV)  s o l u t i o n i n HC1  as recommended.  The power s o u r c e  source was a Model D-612T f i l t e r e d power supply 0-l6 purchased from F i s h e r S c i e n t i f i c Company. c e l l was done with a 1.070 c e l l constant of 0.8135  x 10 M -2  cm" . 1  volts,  A c a l i b r a t i o n o f the  s o l u t i o n o f KC1, g i v i n g a  - 55 -  F I G U R E 10  CONDUCTIVITY  CELL  III.  A.  RESULTS AND DISCUSSIONS  The V i b r a t i o n a l Spectrum of SeOBr,, No v i b r a t i o n a l data f o r SeOBr has been previously reported, 2  but the molecular structure of this compound i s expected to be e i t h e r pyramidal  or planar, that i s , with or without a stereochemically  active lone p a i r of electrons.  The r e s u l t s o f the Raman spectra as  shown i n Figure 11 are l i s t e d below i n Table 4 f o r SeOBr as a s o l i d , 2  as a melt and i n benzene.  The s i x bands which are described may  be  taken as the s i x fundamental vibrations of the SeOEr molecule. 2  The p o l a r i z a t i o n data have been obtained only i n the molten state of SeOBr . 2  As can be seen there are four p o l a r i z e d peaks representing  symmetric v i b r a t i o n a l modes, and two depolarized ones c h a r a c t e r i s t i c of asymmetric v i b r a t i o n s . These r e s u l t s immediately rule out structures of point groups C-^, with s i x expected p o l a r i z e d modes, as well as C  2 v  , which should have only three symmetric v i b r a t i o n s .  The only reasonable  choice l e f t i s v.hat of C  g  symmetry,in agreement  20 with findings f o r SeOF and SeOCl 2  2  .  This implies that SeOBr i s 2  a non-planar pyramidal molecule with a stereochemically a c t i v e lone pair. Complete assignment of the s i x modes follows closely the reported assignment f o r selenium(lV)oxyfluoride and - c h l o r i d e .  The  - 57 -  Raman Spectrum of S e O Br as a melt  R a m a n Spectrum of S e O B r as a solid  2  2  222  104  105  286  2 3 0  302  2 0 8  275 291" 9 3 4  91Q 893  1000  —1 7 5  —1 75  I 1000  Wavenumber (cm ) -1  FIGURE  11  TABLS 4 Vibrational Frequencies (cm"""'-) for S^ORr^ [rela tive intensity of neaks i n ( ),~]  Infrarod  Raman  /issipn'Jient Cr.ys t a l l i n e  Molten  In (§> (dilute)  C910 (2.9)1 t-393 (2.4)3"  934( )(1.9)  960 (10.0)  1302 ( 7 . 9 ) 7 1291 (l.») 3  2r,(p)(r.h)  P  In © (dilute)  9^5(sh)  C905-?  297  275 ( 5 . 0 )  23l(dn)(7.4)  230 (0.3)  272  230 (10.0)  222(n)(10.0)  221 (0.7)  0- p  203 ( 7 . 3 )  204(dp)(sh)  191 (0.2)  105 ( 9 . 7 )  104(p)(3.2)  (sh) = sh-.uldor  Crystal! ine  (<^)  ^sym Se-Br2 Hasyn Se-Br,,  275  ^ sym 0-5e-Br r>nn  ''  yn 0-3e-Br  102  6 t  [n) = polarized  (dp) = depolarized  Br-Se-Br  - 59 symmetric peak at 934 cm" i s assigned as the Se=0 s t r e t c h i n g 1  mode. 286  Based upon the p o l a r i z a t i o n data, the two frequencies a t  cm" and 281 cm" are ascribed to the symmetric and asymmetric 1  1  s t r e t c h i n g vibrations o f the SeBr  group.  2  ^  -1  have been found previously a t 290 cm 260 cm" i n S e B r found a t 222 cm"  2  1  x  f o r SeBr ,  105,106,107  and  2  The 0 - Se - Br bending vibrations are  1  2  Other Se-Br vibrations  and 204 cm"", corresponding respectively to the 1  symmetric and asymmetric bending modes.  The s i x t h frequency a t  104 cm"*, which i s also symmetric, i s assigned to the Br - Se - Br 1  bending v i b r a t i o n f o r the molecule. The expected lowering o f the Se=0 s t r e t c h i n g frequency i n the 0=SeP2>0=SeCl > 0=SeBr  series  2  2  r e f l e c t s the decreasing strength  and increasing length o f the Se=0 bond as less ligands are attached to Se.  electronegative  I n addition, i t must be r e a l i z e d that  even i n the molten state, the p o s i t i o n o f the Se=0 s t r e t c h i n g mode shows some association o f SeOBr molecules, presumably v i a 2  /Se=0-»>Se=0 linkage.  The reported values i n the melt are therefore  only p a r t l y a r e f l e c t i o n of the Se=0 bond strength and p a r t l y an association o f the molecules.  This association i s best i l l u s t r a t e d  by the observed trend i n U f o r Se0Br i n various p h y s i c a l environments SeO * o  J  where the frequencies  decrease and the association increases i n the s e r i e s -  s o l u t i o n o f SeOBr > molten SeOBr > s o l i d SeOBr . 2  The p o s i t i o n o f the Se-Br  2  2  s t r e t c h i n g frequencies  2  i s not unprecedented,  as mentioned e a r l i e r ; neither i s the f a c t that the symmetric ^Se-Br  m 2  o  a  e  occurs at higher wavenumber than does the  - 6*0 -  asymmetric one-a s i m i l a r s i t u a t i o n i s encountered f o r the isostructural thionylhalides.  The p o s i t i o n and the s p l i t t i n g of  the two symmetric s t r e t c h i n g v i b r a t i o n s , ^  and V  S e 0  s y a  se£r * 2  i n t o two doublets i n the c r y s t a l l i n e state can be i n t e r p r e t e d as being caused by even stronger association of SeOBTg molecules i n the s o l i d state together with possible s i t e symmetry e f f e c t s . The e l e c t r i c a l conductance of l i q u i d Se0Br  2  as a function  of i n c r e a s i n g temperature, shown i n Table 5 and Figure  12  reveals a p o s i t i v e temperature c o e f f i c i e n t of e l e c t r i c a l conductance, t y p i c a l f o r e l e c t r o l y t i c d i s s o c i a t i o n i n t o ions. i s consistent with other selenium(lV)oxyhalides  Such a phenomenon and  Se0(S0jF)  2  as mentioned previously.  B.  The Assignment of Vibrational Frequencies f o r Se0(S0^F) Inclusion of Se0(S0jF)  2  2  i n t o the group of Se0X type compounds  i s based upon the following r a t i o n a l e .  2  The fluorosulphate  group,  -SO^F, together with peroxydisulphuryldifluoride, S 0gF , can 2  2  be regarded as a pseudohalide or pseudohalogen respectively with i t s electronegativity somewhere between F and CI. has been found to be an excellent bidentate 96 number of t i n and organotin compounds.  The SO^F  b r i d g i n g group i n a large 97  '  Also i n t h i s f i e l d  are good examples f o r non-random l i g a n d r e d i s t r i b u t i o n of compounds.  w a 3  group  hoped, therefore, that a greater  SO^F  preferenc  f o r mixed compounds would occur i n reactions between Se0(S0^F)  2  there  - 61 -  TABLE 5 f i c Conductivity  T e n d e r ? t u r e ( C) J  of SeCErv, as s F u n c t i o n of T e * w e r s t u r e  Specific ICP  46.4  46.7 47.9  53.6 54.7 54.8 55.0 55.2  KFT)  Conductivit.  (^1--" -C'TI- )  0.905 1.146 1.180 1.339 1.415  1.420 1.425  53.4 66.2  1.435 1.439 1.764  66.4  1.773  66.6  1.731  67.7  1.306  67.3 71.1  71.4  1.310 1.925 1.933  71.6  1.942  72.1  1.953  72.3  1.966  75.3  2.061  1  1  - 62 -  3.00-j  SeO(S0 F) 3  2  2.80 2.60 ^ 7 E O  240 2.20H 2.00  Specific Conductivity of S o m e Selenium—Oxy Compounds as a Function of Temperature  w 1.60  1.40H o  =3 "O c o  1.20  SeOBr.  I.OO  U  ASeOCL  2.00 4  E '  o  —y  a M  o  806040-  1.20 1.00 lO  20  —l  30  1—  40  50  60  TO  Temperature ( ° C ) Self ionization = ( S e O X z ^ ^ ^ FIGURE  12  ~1  80  1—  90  IOO  SeOX 4- S e O X J ) +  \  - 63 -  and o t h e r S'eOX m o l e c u l e s . 2  S u b t l e changes i n v o l v i n g t h e i n t e r n a l  SOjF v i b r a t i o n a l f r e q u e n c i e s on l i g a n d r e d i s t r i b u t i o n s h o u l d be r e c o g n i z a b l e i n s u c h a s y s t e m . The s y n t h e s i s and Raman s p e c t r u m o f Se0(S0^F) has a l r e a d y 2  been r e p o r t e d , ^  a s mentioned i n s e c t i o n I.B.4., b u t d u r i n g a  r o u t i n e p r e p a r a t i o n o f t h e compound f o r f u t h e r l i g a n d r e d i s t r i b u t i o n r e a c t i o n s , a check o f i t s Raman s p e c t r u m was made t o v e r i f y i t s c o m p o s i t i o n as t h e b i s f l u o r o s u l p h a t e . 133 c m  - 1  One a d d i t i o n a l peak a t  was o b s e r v e d and s u b s t a n t i a t e d by f u r t h e r s i m i l a r  . e x p e r i m e n t s w h i c h i s i n c l u d e d i n t h e f o l l o w i n g T a b l e 6. I t was a l s o d e c i d e d a t t h i s time t o r e i n v e s t i g a t e t h e v i b r a t i o n a l assignment t h a t had p r e v i o u s l y been t e n t a t i v e l y p r o p o s e d . 46,47 The f r e q u e n c i e s a t 1431 cm" and 1220 cm" a r e t h e asymmetric 1  1  and symmetric SO^ s t r e t c h i n g v i b r a t i o n s , whereas t h e 1056 cm"  1  peak i s t h e S-OSe s t r e t c h , unchanged f r o m t h e p r e v i o u s a s s i g n m e n t . L i k e w i s e i s s o f o r t h o s e bands a t I U 4 4 cm" , w h i c h i s a s s i g n e d 1  t h e Se=0 s t r e t c h i n g mode, and 853 cm" , w h i c h i s t h e S-F 1  s t r e t c h i n g mode.  The peak a t 638 cm" , however, i s r e a s s i g n e d as 1  the symmetric Se-OS s t r e t c h i n g v i b r a t i o n w h i l e t h e asymmetric s t r e t c h i n g mode f o r Se-OS i s found a t 459 cm" . 1  Other values that  have been a s s i g n e d t o Se-OX s t r e t c h e s o c c u r a t 57& C Q " ^or SeO(OCH^) ^ , 1  646 cm" and 584 cm" f o r SeO(OC H ^ ) ^ , and 644 cm" and 577 cm" 1  1  8  2  f o r SeO^CH^XOCgHfj) H Se0j, 2  99  HSeOjCRj  1  2  S i m i l a r v a l u e s may a l s o be f o u n d f o r 100  and HSeO^CgR^  100  , a s w e l l as t h o s e f o r  2  1  TAELS  6  V i b r a t i o n a l F r e q u e n c i e s (cm"' ) and .Assignment f o r SeO(SO^F) [ r e l a t i v e i n t e n s i t y o f peaks i n ( )J  Assignment  frequencies ref.  T h i s work  dep (1) P (6) 10 55 P W 1044 (4) 84P. n (3) P (O 639 533 P (2) 5.51 der (2) (4) 452 ^(4) 446 390 br (].) 340 sh (1)  1430 122^  31."1 265  -  an)  kv, (6) r.b (2)  dep P  sh  br  depolarized polarised shoulder broad  1431 1220 1056  (0.6) (3.6) (2.7)  1044  sh  353 633  (1.2)  590 551 459  (0.7) (0.6) (3.0) (3.2)  443 403 350 311  266 230 177 133  (3.4)  sh sh (10.0) (5.6) (0.4) (1.0)  V asym s vm V V V  S  syra rock  y asym wag twist  Deformation Modes  so so  2  S-OSe Se=0 SF Se-05 SOp S0 Se-OS SF SO  2  2  /Cc  Na Se 0 , 2  2  1 0 1  5  K Se 0 , 2  2  1 0 1  5  and ( N H ^ S e ^ .  r e l a t i v e l y low value of 459 to the frequencies of 475  cm"*  In fact the  1 0 1  f o r SeO(SO^P) may  1  2  cn"" and 491 1  cm"  1  be compared  (as measured i n the  IH and Raman spectra, r e s p e c t i v e l y ) f o r the asymmetric Se-OX s t r e t c h i n Ka Se 0^. 2  2  Only those bands down to ~4°0  cm  may  -1  be safely assigned at t h i s time, with the peaks occuring at 590 551  cm" , 1  443  bending, S0  2  cm"  1  and 403  cm"  being described as the  1  S0  cm" , 1  2  rocking, SF wagging, and SO t w i s t i n g modes from the  SOjF group corresponding to s i m i l a r assignments that have previously been made f o r a number of other fluorosulphate  , . .  ,  containing molecules.  C.  96,97,102,103,104 '  The Existence of SeOXY Molecules i n Ligand R e d i s t r i b u t i o n Reactions The reaction-type to be investigated f u r t h e r i s the l i g a n d  r e d i s t r i b u t i o n o r ligand scrambling reaction.  Exemplified by  the general equation SeOXg + S e O Y ^ 2  where X and Y = F, CI, Br and SO^F,  (19)  ^ 2SeOXY l i g a n d exchange i s  accomplished  presumably v i a four-center intermediates or v i a ions formed i n the l i q u i d phase.  E l e c t r i c a l conductance measurements indicate that ions  of some sort are formed f o r a l l SeOX or SeOY compounds. 2  2  It  became i n t e r e s t i n g to see whether exchange does indeed take place and whether t h i s r e s u l t s i n a s t a t i s t i c a l or n o n - s t a t i s t i c a l d i s t r i b u t i o n of the three compounds.  - 66 -  1.  SeOBrCl Combination, o f SeOCl  2  and SeOBr i n a 1.0 2  : 1.0 molar r a t i o  gives r i s e to the formation of a red-brown colored l i q u i d , e x h i b i t i n g o a rather broad melting-point-range of 10.5 - 19.0  C.  Solutions with other combinations o f the molar r a t i o s of Se0Cl  2  : Se0Br  2  5.0: 1.0  and 1.0: 3.0 showed the same c o l o r .  Raman spectra were obtained from these three solutions and t h e i r frequencies are l i s t e d i n Table 7. two parent compounds SeOCl  2  Absorption bands due to the  and SeOBr may be distinguished e a s i l y 2  i n the mixtures by measuring the i n t e n s i t i e s of various bands i n the three mole r a t i o s . A clear d i s t i n c t i o n whether, i n addition to SeOBr and SeOCl2, 2  the new  species SeOBrCl exists i n the mixture cannot be made by  observing any of the rather broad s t r e t h c i n g modes. the p o s i t i o n of v g e Q f o r SeOCl d i f f e r e n t by 10 cm"  1  assumed that y  2  For instance,  and l i q u i d SeOBr are only 2  as shown i n Tables 2 and 4.  I t must be  f o r SeOBrCl w i l l also f a l l i n this region.  Since  the Se=0 s t r e t c h i n g modes i n the l i q u i d s are a l l found to give r i s e to broad bands, the i d e n t i f i c a t i o n here i s extremely d i f f i c u l t . The same applies f o r ^Seci  ^SeBr ^  w  e  l  1  .  Of the bending motions only one type - S e C l and SeBr 2  -1 found well enough apart, separated by ~50 cm to be u s e f u l .  The occurrence of a new band at  mixtures of SeOCl the SeBrCl group.  2  2  - are  _i at 158 cm  and 105 cm  135 cm'"" i n a l l 1  and SeOBr must be caused by the presence of 2  This band presents therefore the only good evidence  that SeOBrCl i s indeed formed.  TABLS ? V i b r a t i o n a l FreouencVos (cm" ) f o r SeOClp find SeOBr^ i n V a r y i n g  Ratios  1  [ r e l a t i v e i n t e n r - i t y o f -^eaks i n ( )] SeOCl :SeOBr  SeOCl,  ?  liquid  944  ^'7  {?./-,)  390 (10.0) 3.50  (sM  271  (1.0  246  (1.5)  153  sh  1".'0:1.0 '  liquid  liquid  (3.0)  336  (10.0)  3<;<  (sh)  943  330 362  SeOCloCS^OBr, 2  o  3^0:1.0  (4.3)  (9.3)  (sh)  1^0:3.0  liquid  936  (2.3)  solid  oio 394  (2.9)  (3-2)  363  2*2  (3.1)  290  Assignment l.io ivi.H  934 (5.2) (3.9)  365  S eOBr.  (1.9)  ! '• I  (5- '•)  2'0  (4.7)  (sh)  276  (7.0)  (10.0) (7.3) (0.2) (2.5)  (sh) 222  '•I.-;  (9.6)  (3.9) (2.3) (2.3) (2.0)  (10.0)  161  (0.5)  135 105  (3.7)  132  (2.0)  232 210 I63 133  (3.D  103  (4.5)  10', ( 8 . 8 )  223 211  (10.0)  (sh)  161 ( 0 . 3 )  010  (2.9)  393  (2.4)  SoO V  3 0 1 (8./-!) 2%  solid  236 ( s h ) 2^1 (.?.'•)  222 (10.' 20- ( ' .1 10M  (  .2)  302 ( 7 . 9 )  syin  SeCl  0  ^ s y t n SeBr.'"  7 V svn SeBrp' ( 5 . 0 ) f 6 syin 0-S<--Cl asyrn SoBr, 6 asyn O-Sn-C -30 (10.0) <*> s y n O-So-Br 208 ( 7 . 3 ) S> asyn O-So-B & Cl-So-Cl £ Cl-Sft-Pr 1 0 5 ( 9 . 7 ) <5 Br-Sft-Br ^1 275  (1.9)  3  ; houl d .iy  ON -J  - 68 -  According to Yarovenko et a l  75  , a product with the stoichiometry  SeOBrCl was obtained pure from a r e a c t i o n y i e l d i n g not only that product but SeOCl  2  as w e l l .  Attempts to obtain SeOBrCl by s i m i l a r  f r a c t i o n a l d i s t i l l a t i o n methods under reduced pressure, generated acoording to reaction (19) i n t h i s laboratory f a i l e d , however, w i t h considerable decomposition o f products.  The only analysis o f the  r e s u l t i n g materials was made by a Raman spectroscopic experiment. In the spectrum were observed a variety o f peaks (some perhaps due to Se0  2  and Se^Brg as decomposition products), some of which  could be i d e n t i f i e d as belonging to SeOCl  2.  2  and SeOBrCl.  SeOClP A mixed selenium(lV)oxyhalide i s also observed i n a 1.0  r e a c t i o n mixture of S e 0 C l and SeOPg. 2  : 1.0  The frequencies from the  Raman spectrum o f the c o l o r l e s s l i q u i d products are l i s t e d i n Table 8 along with an assignment o f the peaks.  In the Se-0  s t r e t c h i n g frequency range, peaks f o r both SeOCl  2  and Se0F  be observed f o r the r e d i s t r i b u t i o n r e a c t i o n mixture. be said f o r the SeX  2  But again, as f o r the SeOCl  2  The same can  2  , too.  - SeOBr reaction mixture, one peak 2  remains unaccounted f o r i n the reaction of SeOCl 1  can  s t r e t c h i n g and the O-Se-X bending frequencies  besides the X-Se-X bending modes f o r SeOPg and SeOCl  one at 220 c a " .  2  2  and SeOP - the 2  This peak has been assigned to the Cl-Se-P  bending v i b r a t i o n f o r the SeOClP molecule, occurring neatly between  -  j  -  TABL.3' 3 V i b r a t i o n a l ?r?auencles  1  ( c t n " ) f o r S e C C l g ' snd SeOFg i n 1.0  : 1.0  Ratio  [Vs 1st i v e intensity o f -:e?'^ i n ( }] SeOCl.  SeOCl,, : S e C F 9 170 ; 1.0"' licuid  liquid  Assignment liauid  H  944  3^0  (2.6)  (10.0)  1013 9.54  (1.0)  670  (br)(1.4)  1012  (sh)  626  (sh)  391  (10.0)  35 C  V  (2.3) 6'6  (10.0)  610  (3.4)  V  S  (4.2)  (sh)  239  (sh)  S eC  s asvn  V 331  350  s  ( .3)  je-r?  s'.m 3e-Cl sym  Q-Se-F  V asyn Se-Clp 320  (4.Q)  258  (sh)  &  a s y a G-Se-F  271  (1.6)  274  (2.6)  cS  246  (1.5)  254  (1.7)  <S ssv-n O - S s - C l  220  (0.2)  1*0  (51)  15?  br sh  (5.0)  = bro".d = shoul-'er  !  s.yn C - S e - C l  & Cl-Se-cn  - 70 -  the corresponding bending modes o f the parent molecules. Additional evidence f o r the SeOCIF species has been obtained  19 via a  F M  spectrum o f the 1.0 : 1.0 mixture, the chemical  s h i f t o f which i s given i n Table 9 along with those o f other selenium-fluorine containing compounds. are two sets o f t r i p l e t s .  Present i n the spectrum  The one centered at -42.4 ppa has  a spin-spin coupling constant value o f 846 Hz f o r J77s _p » e  and can be i d e n t i f i e d as being due to SeOFo, which has a J7'( oe—jj* value o f 856 Hz as measured i n the pure state here. In addition c  7  T. B i r c h a l l et a l f o r Se0? from ^Se 2  1  have reported a value o f 837 Hz f o r J77 _19 3e  HHR spectra.  The intensity  ;p  o f this f i r s t peak  when compared to that o f the second i s given by the r a t i o  4:1.  Thus i t i s the second set o f peaks which may be a t t r i b u t e d to SeOCIF. This peak centers at -32.3 ppa and has a J77,, 19 „ be F value o f 654 Hz. 3.  " SeOBrF," The 1.0 : 1.0 mixture o f SeOFg and 3eOBr was also investigated. 2  A Raman spectrum o f the solution, at roora temperature the frequencies are l i s t e d i n Table 10.  was taken and  As i s p l a i n l y evident from  the Table, .all observed peaks may be interpreted i n terms of e i t h e r SeOF or SeOBr with no peaks d e f i n i t e l y a t t n o u t a b l e to SeOBrP. 2  2  The p o s s i b i l i t y that the BrSeP bending mode may be obscured by other deformation modes o f SeOBr out completely, however.  2  does not permit SeOErF to be ruled  I t seems, though, that the existence o f  I A E L 2  9  C'-'STdcsl S h i f t s f o r So'ne Selpnium-Fluorine Compounds Chemical S h i f t (rn-) r e l a t i v e to CFC1 o-v:t  Compound  0  3 ft-? 3eO(SC~F)  -43.6 ?  -43.6 (br)  FSeC(SCy )  -47.'  ClSeC(30,.F)  SoCF  -40.3  0  ! -32.3  SOC1F 3~CFo : 3e03r : 1.0:1.0 2  -43.1 103 -48 103 -61  3-?,.(C:)  2  3eF (OF) 5  -4? 55.7  -47  SeF^CSeF.  -32.2  F  110  110  3eF CCF0 c  -43.4  110  C5?F  110  42  5-  I  o  -p  c  I  CN)  I  <r e o" to co co i C  o  C1  o  cfi- cc  I  i  h  n  CO  O  Ox  o  i  o  c-  co  u.  •H  1/5  tr. tr.  . IT.  cv cv cv H O CN ON OJ  O CN rH O cr cc  r—' O  PT: O CO • C r-i co  ^ o cr. vo O- ON o c CM OJ. OJ r-i  •c  o- H ^  rH  a'  • ON O• O • • Ur-J O-  • rH OJ  c-  co  C  H  N O  cc  ON ON  OJ  O r-»  C O O  rH ON O 0  NC NC ON  N  -  • • cr  3  cv o o OJ OJ O! H  o"  --T • OJ ^ • O • • O- rH VTN NT  CT' •r-i  c C O  to  O! •H  c rH  cr cr cr ifN, o r --  1  NC O ri j N H T \ C NG ON  H  CN CNJ  O N  ON  OJ  U-NNT cr  cr cv o c O! CN! OJ I—!  of SeOBrP i s not evident from the observed spectrum under these conditions. UJ.R  A  spectrum o f the s o l u t i o n was also obtained; however,  only a single peak at -43.1 ppm r e l a t i v e to CFCl^ was observed, 19 occurring near the value f o r pure SeOF i n i t s 2  F NMR spectrum  as shown i n Table 9 . 4.  SeOBrKsC^F) SeOBr and 5e0(S0 ? ) produce a yellow waxy substance when 2 3 £ 0  combined i n a 1.0 : 1.0 molar r a t i o a t room temperature, but upon warming to 100°C the product turns to a l i g h t crimson-red l i q u i d . Raman spectra were recorded on this l i q u i d sample at ~* 100°C because the s o l i d sample, even with highest s e n s i t i v i t y , gave r e s o l u t i o n o f only those peaks at 293 cm" , 144 cm" , and 115 cm" . 1  1  1  The r e s u l t s are l i s t e d i n Tables 11 and 12. The peaks at 1415 cm" and 1219 c a " can be ascribed to the 1  1  asymmetric and symmetric S 0 s t r e t c h i n g 2  modes o f the SO^F  group, but i t cannot be s a i d f o r sure to which o f S e o C S O ^ F ^ or SeOBr(SOjF) these vibrations r e s u l t .  Another peak  at 1185 cm  1  may be interpreted as being one of the v i b r a t i o n a l modes o f Se0Br(S0jF), but no c l e a r explanation can be given to account f o r this The peak at 1070 cm" , however, may be  rather pronounced shoulder.  1  assigned to the S-OSe s t r e t c h from the SeOBr(SO^F) molecule, which i s analogous to the 1055 cm"  1  i n i t s spectrum.  The  y  g  frequency observed f o r pure S e O C s o ^ F ^ modes from Se0(S0^F) , SeOBr(SOjF), 2  and SeOBr are a l l observed i n the spectrum o f the equilibrium 2  mixture and are found a t IO46 cm" , 1028 cm" , and 935 cm" 1  1  1  - 74 -  TA3L2 11 C o r r e l a t i o n o f Selenium-Cxyzen Couinourvis w i t h Numbers [?le?.se use i n r e f e r e n c e t o T a b l e 12 }  Nurr.b* r  Coir~ound SeO(S03?) SeOF  2  1 2  2  3eCCl  2  SeOBr  2  3  SeOF(SO^F)  5  SeCCKSOjF)  6  SeOBr(SC-jF)  7  TABLE 12 V i b r a t i o n a l Frequencies (cm ) f o r Some SeOX(SO-}F) Compounds X = F, CI, Br -1  J  Numbers i n square brackets refer to compounds considered responsible f o r given frequency of vibration, as per Table 11. Relative i n t e n s i t y of peaks are i n parentheses "for each peak.  Frequency  3  Intensity  [5] D-] [5]  1425 1226  (br)  fll [51 CU [5] [2] [5]  1072 1041  (sh)  CU  (0.3) (4.5)  (sh)  852  (1.7)  [2] [51 [ll [51  663  (6.2)  U [51 [5]  591 557 435  [1] [51  443  W  411 347  D-l  [5]  W [5] 15]  (6.0)  639  45=;  305  294  237 215 177  135  (0.3) (sh) (sh)  (0.7)  (9.1) (sh) (sh)  (sh)  Frequency  [11 [61 141-8 [1] [6] 1210 [61  (6.2)  [51  [1]  SeOBr(SC-F)  SeOCl(S0 F)  SeOFCSC^F)  (2.1) (5.D (10.0)  (1.5) (1.0)  [1]  [6] [31 [ll [6]  10?7 1047 1003 941  835  Intensity (br)  (sh) (sh) (br)  (0.8)  Frequency  (M.0)  [ll [ll  (7.7)  [71  [7] 1415L?l 1 2 1 9 1135  [1] (3.5) (1.2)  [71 [4] [1]  [71 [ll [61 [11 [11  [61  645  [63 [6]  619  (sh) (5.3)  (0.7) (0.3) (0.7)  537 55" 490  [61 423 [ll [6] 411  277 227  (6.2 x 10.0) (sh) (sh)  211  173 165  (".6)  (sh)  1046 1023  (3.7)  (sh)  (10.0) (0.4) (1.7)  935 337  304  (sh)  [ll [71  [1] [7] [1] [7]  (6.4) (6.4) 502  (sh) (<0.1) (2.6)  560  [71  493  [ll [71 [ll [71  420  (^.2) (sh)  (sh) 2-3  (10.0)  (0.9)  (br)  1070  (6.1) (3.3)  (sh)  Intensity  222  lQ 144 n  (150-x-10.0) (4.3)  (sh)  (45 x (50  x  10.0) 10.0)  respectively with the peak at 1028 cm"  1  intensity.  having the greatest  A shoulder at 804 cm" , found on the main peak 1  at 857 cm" , can be assigned to the S-F s t r e t c h i n g v i b r a t i o n 1  o f SeOB^SOjF), found at a lower frequency than the same v i b r a t i o n o f SeoCso^F),,, which accounts f o r the main peak. Between the two peaks observed at 652 cm" and 650 cm" 1  must  1  be assigned the Se-OS s t r e t c h i n g modes from SeOCSO^F^ and SeOBrCSO^F). Se0(S0jF)  Although the occurrence o f this mode i n the pure  spectrum i s at 639 cm , i t i s generally assumed -1  2  that this v i b r a t i o n would be o f higher energy than the one f o r SeOBr(SOjF) due to the more electronegative influence o f SO^F over Br.  Thus the 652 cm"  1  f o r SeO(SO^F)2 and the one at 630 cm"  1  y Se-OX *"  or S e 0  ^ (S0jF). r  ^2e-0X  v i b r a t i o n has been assigned to has been assigned to  Other fluorosulphate modes  r e s u l t i n g from either one o r both of SeOtSOjF^ and SeOBr(SO-F) are found at 592 cm" , 560 cm" , 441 cm" , and 420 cm" 1  1  1  and may  1  be described,respectively as the modes f o r S  QQ  , rock S0 , 2  wag SF, and twist SO as per Table 10. Again there i s no assignment of the bands below 400 cm , 1  but differences i n peak positions and i n t e n s i t i e s may be noticed. For example, the strong  265cm" peak from Se0(S0^F) 1  2  i s missing i n  the spectrum o f the mixture whereas a very strong peak a t 293 cm"  1  does occur which coincides with a r e l a t i v e l y strong band i n t h i s region from Se0Br  Peaks at I44 cm"  1  2>  and 115 cm" are 1  d e f i n i t e l y new to the system and perhaps may be a r e s u l t o f v i b r a t i o n a l  - 77 -  modes of SeOBr(SCuF).  Enough evidence can be seen from t h i s ,  however, to verify the presence .of the mixed compound SeOBr(SO-F).  5.  SeOCl(S0 F) 3  The existence of SeOCl(SO^F) has previously been reported but some doubt about the correct assignment existed.  ,  The Raman  spectrum was reinvestigated and the frequencies that were observed are l i s t e d i n Table 12 and are i n agreement with previous findings.  These frequencies are assigned as follows.  Bands at 141S cm  and 1210 cm"  -1  1  are i n the region o f the  asymmetric and symmetric SO^ s t r e t c h i n g vibrations from the SO^F  group, which are not very d i f f e r e n t from those i n Se0(S0jF)  and may  2  be ascribed to e i t h e r SeOCl(SO^F) or Se0(S0^F) . 2  A peak at 1077  cm"  1  i s assigned as the asymmetric ( A ) S-OSe 1  s t r e t c h i n g mode of SeOCL(SO^F).  Se=0 s t r e t c h i n g frequencies are  observed f o r each of the parent compounds Se0(S0^F) as well as the mixed chlorofluorosulphate at 1047 and 1008 cm"  1  The 835 cm"  1  2  cm" ,  941  1  with the f i r s t two of r e l a t i v e l y low  2  cm  \  intensities.  absorption band i s mostly l i k e l y due to the S-F s t r e t c h  of SeOCl(SO^F), although the peak i s broad: this may with a peak at e48 vibration.  and SeOCl  The  cm"  i n the case of Se0(S0^F)  1  Vge-OS  *"  or  2  be compared  f o r i t s S-F  SeOCl(SO-F) i s assigned as the peak  at 619 cm" ,  with the shoulders at 645  V S e _os ^om  SeO(SO^F) i n keeping with the assignment of this region  1  f o r SeOBr(SOjF).  cm" , 1  and 411  1  being assigned to  2  Other fluorosulphate modes which may  to e i t h e r SeOCltSOjF) or Se0(S0jF) 554  cm"  ca"  1  2  can be found at  corresponding to the S0  2  be due  587  bending,  cm" , 1  - 78 -  SCv, rocking, and SO t w i s t i n g modes.  The most intense peak i n the  spectrum o f the equimolar mixture occurs at 428 cm""'*" and unfortunatley clouds one o f the SO^F v i b r a t i o n s , namely the S-F wagging mode. This strong peak, however, i s unambigously assigned to ^se_Q^ f o r SeOCl(SOjF).  This may be compared to the frequencies at 390 cm"  and 350 cm"  f o r SeOCl which have been assigned as the symmetric  1  1  and asymmetric  2  ^g e _ci modes which i n c i d e n t a l l y are the most intense  peaks i n that spectrum. The other peaks below ^ 400 cm" may be treated i n the same 1  manner as f o r SeOBr(SO^F).  A d e f i n i t e l y d i f f e r e n t set o f peaks  occurs f o r the mixed chlorofluorosulphate than f o r the bisfluorosulphate. Again the strong 265 cm" peak i s seen i n the spectrum f o r SeOCl(SO^F). 1  In addition, the v i b r a t i o n at 177 cm"  1  f o r SeOCl(SOjF) i s much  more pronounced than the s i m i l a r one f o r Se0(S0jF) . 2  Even though the assignment f o r the peaks below ^OOcm"  1  cannot be unambigously given, a noted contrast between the Raman spectrum f o r an equimolar mixture o f SeOCl  2  and SeO(SO^P)  2  compared to those spectra o f the s t a r t i n g materials alone can be seen. In other words, f o r the Se0Cl /Se0(S0jF) system good evidence 2  2  has been obtained f o r the existence o f SeOClCSO^P) from v i b r a t i o n a l data. The ^ F MR  spectrum has also been recorded ^  with a resonance  being observed a t - 4 7 . 7 ppa r e l a t i v e to CFClj external (please see Table 9 ) .  This value, c h a r a c t e r i s t i c o f resonances f o r f l u o r i n e  on sulphur i n fluorosulfihates, while d i f f e r i n g from the - 4 8 . 6 ppm  - 79 -  value f o r Se0(S0^F) i s not s i g n i f i c a n t l y d i f f e r e n t enough to 2  come to a conclusion about the existence of SeOCl(SO^F) on i t s own merit.  The fact that i t i s d i f f e r e n t i s readily explained  i n conjunction with v i b r a t i o n a l data, however.  6.  SeOFCSO^F) From the r e a c t i o n mixture o f SeOF and Se0(S0^F) was obtained 2  2  a Raman spectrum, the absorption bands o f which are l i s t e d i n Table 12.  Peaks d e f i n i t e l y a t t r i b u t a b l e to a fluorosulphate  containing molecule may readily be distinguished by comparison of those frequencies l i s t e d i n Table 6 For example, the peaks at 1425cm"  1  for Se0(S0jF) . 2  and 1226 cm"  1  may be  safely ascribed to the asymmetric and symmetric S 0 s t r e t c h i n g 2  modes f o r the SO^F group, and the shoulder at 1072cm" assigned t o the S-OSe s t r e t c h i n g mode. at 852 cm" , 591 cm" , 557 1  1  1  can be  Furthermore, the peaks  cm" , and 4 1 1 cm" 1  1  may s i m i l a r l y  be described as various modes o f v i b r a t i o n of the SO^F group. But i n spite of these peaks' appearances there i s considerable d i f f i c u l t y i n determining i f they are a r e s u l t of the SO^F v i b r a t i o n s from Se0(S0jF)  2  or Se0F(S0jF).  are also very close i n S e 0 F of 1012 cm"  1  and IO44 cm"  1  2  The Se=0 s t r e t c h i n g frequencies  and SeO(SO^F) , with values 2  r e s p e c t i v e l y , thus preventing a  simple determination of SeOFCSO^F) i n this region. t h i s mode i s usually quite broad.  In addition,  In the 7OO-6OO cm"  1  range,  - 60 -  both Se0(S0-P)  and SeOP have bands at  2  2  which are assigned as the Se-OS. symmetric  650-610 cm s t r e t c h i n g frequency and  the Se-P s t r e t c h i n g frequency f o r the two molecules.  The incidence  of any new peaks due to these vibrations i n Se0P(S0^P) would most l i k e l y be indistinguishable from the previously  mentioned  peaks. Evidence f o r exchange must be drawn from the f a c t that r e l a t i v e i n t e n s i t i e s of many absorption bands i n the mixed product and i n the parent compounds do not agree.  The spectrum f o r Se0P(S0^P)  cannot be produced by merely superimposing the Raman spectra of SeOPg and Se0(S0j?) .  I t may be noticed that i n the spectrum  2  f o r Se0P\S0jP) there seems to be a peak missing at 610  cm"  1  which might be expected to appear with nearly the same i n t e n s i t y as that f o r the frequency of 656 cm"  1  as i n the case f o r SeOF i f 2  the mixture contained j u s t the two parent compounds i n s o l u t i o n with each other.  For t h i s normally strong peak to be absent while  other weak ones at 591 cm"  and 557 cm"  1  1  are present indicates that  there i s at l e a s t some i n t e r a c t i o n occurring. peak at 265 cm"  In addition, the  i n the spectrum f o r Se0(S05P) i s the most  1  2  intense o f a l l peaks f o r that compound, but i n the spectrum f o r the mixture of SeOP and Se0(S0^P) 2  2  there i s a remarkable absence o f  any peak at that frequency.  Furthermore, a shoulder at 215  upon a main peak at 237 cm"  i n the l a t t e r spectrum cannnot be  1  cm"  1  adequately explained by comparison to the spectra of e i t h e r o f the two parent compounds.  - 81 -  A • "F NMR spectrum o f the equimolar L  and S e O ( S O ^ F )  2  s o l u t i o n o f SeOF  g i v e s s i n g l e peaks a t -43.6  2  and -48.4  (broad)  r e l a t i v e t o e x t e r n a l C F C l ^ ( p l e a s e see T a b l e 9 ) .  ppm  The l a t t e r  i s i n t e r p r e t e d as b e i n g due t o the f l u o r i n e a t t a c h e d t o s u l f u r , where o t h e r v a l u e s f o r s e l e n i u m o x y ( f l u o r o s u l p h a t e ) s have been r e c o r d e d a t -48.6 is  and -47.7  PPQ.  The broad resonance a t -43.6  a s s i g n e d t o the f l u o r i n e on s e l e n i u m w i t h the broadness  77 due  t o r a p i d exchange and o r  19  Se - ' F h y p e r f i n e A  ppm  being  interaction.  A s i m i l a r s i t u a t i o n has been p r e v i o u s l y d i s c u s s e d f o r the m i x t u r e of SeOF  2  and S e O C l  2  using  77  Se NMR t e c h n i q u e s .  7  The above r e s u l t s  seem t o i n d i c a t e some exchange and the p o s s i b l e f o r m a t i o n o f SeOF(S0 F). 5  7.  Conclusions I t must be s a i d i n c o n c l u s i o n t h a t t h e p r e s e n c e  molecules  o f these  o f type SeOXY has o n l y been d i s t i n g u i s h e d i n e q u i l i b r i u m  as c o n t r a s t e d t o b e i n g observed Observations  i n a pure i s o l a t e d  state.  from s o l u t i o n s o f v a r i o u s m o l a r r a t i o s o f r e a c t a n t s as  w e l l as the d i s t i l l a t i o n  experiment o f SeOBrCl tend toward the  c o n c l u s i o n t h a t a n a c t i v e r e d i s t r i b u t i o n i s o c c u r r i n g between d i f f e r e n t X and Y l i g a n d s , and t h a t i s o l a t i o n o f p r o d u c t s of  r e a c t i o n would n o t be p o s s i b l e .  from t h i s  type  Indeed, based upon t h e  v i b r a t i o n a l d a t a i n v o l v i n g i n t e n s i t i e s o f peaks, one must conclude  t h a t a g r e a t e r amount o f i n t e r a c t i o n i s o c c u r r i n g i n  some systems than f o r o t h e r s , and t h a t the mixed compounds c a n be observed  i n what must be c a l l e d an e q u i l i b r i u m .  A further remark i s due i n respect to the v i b r a t i o n a l frequencies found f o r the SO^F group, i n p a r t i c u l a r f o r the s t r e t c h i n g frequency region.  Even though the SO^F group has  0 been interpreted as being b a s i c a l l y monodentate,  - 0 - SP  104 some assocaition, as noted f o r example i n BrOSOgF exist.  0  , may  well  This i s born out by the good correspondence between the  v i b r a t i o n a l spectra f o r BrOS0 P and Se0(S0^P) . 2  In p a r t i c u l a r  2  \) g _ ^ moves to higher frequencies  f o r the mixed products,  0  r e s u l t i n g i n a pattern o f SO s t r e t c h i n g modes reminiscent o f 96  a bidentate SO^P. group  97  as found i n some organotin  derivatives and which would have the same symmetry ( C s ) .  Since  i t seems not very easy to d i f f e r e n t i a t e between these two p o s s i b i l i t i e s , t h i s point has not r e a l l y been discussed i n any d e t a i l , mainly because i t ultimately has no bearing on the problem. D.  The Formation o f a Salt between KBr and Se0Br As already mentioned i n section I.H., SeOBr  2  2  can act as a  Lewis base toward such a species as SnBr^ to form oxygen-donor complexes, but i t may also behave as a Lewis acid, f o r example, with p y r i d i n e .  To t e s t the accentor a b i l i t y o f SeOBr , e f f o r t s  were made to prepare the bromo analogue o f KSeOFj  2  93  and KSeOCl^  93  and to investigate i t s v i b r a t i o n a l spectrum. The s a l t KSeOBr^ was prepared by d i r e c t a d d i t i o n o f an excess of SeOBr to KBr, and an analysis showed that i t contained 20.98>o Se 2  and 63.96^ Br, which may be compared to the t h e o r e t i c a l values o f  - 33 -  21. 127$ Se and 64.135$ Br f o r KSeOBr^.  The yellow s o l i d when heated  to 120°C i n a melting point tube changed composition to a dark-red substance which eventually decomposed to a dark-red l i q u i d at 171°C.  KSeO&sj and KSeOF^ both have i d e n t i c a l melting points  of 138°C.  9 5  Farther experiments  on KSeOBr^ have shown that when the  compound i s heated to 60°C i n vacuo f o r 48 hours, there i s a loss of a l l Se-0 containing moieties as evidenced i n i t s IR spectrum.  Only a white s a l t , presumed to be KBr remains,  melting point of which was >350°C.  the  A s i m i l a r breakdown of  KSeOBrj was observed when CCl^ was allowed to wash through the s a l t i n a Sohxlet apparatus overnight.  Only a white s a l t , with  no Se-0 modes i n i t s i n f r a r e d spectrum, remained a f t e r the washing. A Raman spectrum of KSeOBr^ was recorded and the frequencies 93  are tabulated i n Table 13.  In the i o n i c model f o r SeOXJ  the symmetry point group f o r the i o n would be C_ and nine vibrations should be found - a l l Raman and IR a c t i v e .  In the  case of KSeOBr^, however, the s o l i d state s p l i t t i n g of one of the vibrations raises to ten the t o t a l number of observed Raman peaks.  A s i m i l a r observation had been made f o r s o l i d SeOBr . 2  The peak at 934 cm  i s assigned to the Se-0  -1  stretching  frequency, quite i n keeping with other Se-0 vibrations found i n s i m i l a r KSeOX^ and Se0X molecules.  The p a i r of v i b r a t i o n a l  2  frequencies at 297 cm"  1  and 292 cm"  1  may  be interpreted as  one of the Se-Br s t r e t c h i n g frequencies being s p l i t by the  - 34 -  TABL3 13 V i b r a t i o n a l Frequencies (cm ) f o r Some KSeOX^ Compounds -1  X = F. CI, 3r ^relative 1 KSeCFo ( solid)'  intensity' of re^Vs i n ( ) 1  K3sOCl (solid)^  3  KSeC Pr-, (soli  Assignment  dr  93a  (1.9)  297  (sh) (sh)  V  Se-X  235  (2.3)  V  Se-X  (5)  2 56  (2.0)  y  3e-X  353  (3)  234  (4.9)  430  294  (2)  222  (7.1)  413  231  (2)  20.5  (10.0)  982  949  (10)  535  373  (7)  513  341  (1)  434  323  450  2 50  292  "A  V  7  (0)  111  (2.0)  \  (0)  101  (1.1)  )  .... .... shoulder  s-=-o  Deformation ,\o  A  ~  e.  es  - 85 -  crystalline f i e l d . observed at 285  cm  Two -1  other Se-Er s t r e t c h i n g v i b r a t i o n s are  and 256  cm . -1  The f i v e other vibrations  are simply described as the remaining deformation modes f o r the molecule i n accordance with Paetzold.  A more d e t a i l e d assignment  would require i s o t o p i c l a b e l l i n g and or s o l u t i o n studies i n the hope to record p o l a r i z e d Raman spectra. 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