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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 of Idaho, Moscow. Idaho, 196"9 A THESIS SUBMITTED Hi PARTIAL FOXFILHEZiT OP THE .REQUIREMENTS FOR THE DEGREE OP MASTER OP SCIENCE i n the Department of CHEMISTRY We accept this the3i3 as conforming to the required standard THE UNIvERSITT 0? BRITISH COLUMBIA In present ing th i s thes is in pa r t i a l f u l f i lmen t o f the requirements fo r an advanced degree at the Un ive rs i t y of B r i t i s h Columbia, I agree that the L ib ra ry sha l l make it f r ee l y ava i l ab le for reference and study. I fu r ther agree that permission for extensive copying of th i s thes i s fo r s cho l a r l y purposes may be granted by the Head of my Department or by his representat ives . It is understood that copying or pub l i c a t i on o f th i s thes is fo r f i nanc ia l gain sha l l not be allowed without my wr i t ten permiss ion. Department of C v\ •<?- (A\ \ S T T ij The Un ivers i t y of B r i t i s h Columbia Vancouver 8, Canada - i i -ABSTRACT The infrared and polarized Raman spectra of Se0Br 2 as a solid, melt, and i n solution have been obtained. The frequencies that were found are consistent with C_ symmetry and a pyramidal molecule. Ionic dissociation, l i k e i n other SeOXg compounds, is evidenced by e l e c t r i c a l conductance measurements. Se0Br 2 can -act both as a Lewis acid or base. For example, a salt with the composition KSeOBr^ has been prepared from KBr and SeOBr2. Ligand redistribution reactions of various Se0X2 and SeOY2 compounds, where X and Y are F, CI, Br, and SO^F, were studied via vibrational spectroscopic and nuclear magnetic resonanoe techniques. The presence of the mixed SeOXY compounds has been detected i n a l l these systems basically i n equilibrium with their parent compounds. None of the SeOXY compounds could be separated out of the mixtures. - i i i -TABLE OP CONTENTS Page TITLE PAGE ABSTRACT i i TABLE OP CONTENTS i i i LIST OP TABLES v i i i LIST OP FIGUBES i x ACKNOWLEDGEMENTS x I. INTRODUCTION 1 A. General Points 1 B. Selenium(lV)oxy-halides and a -pseudohalide 3 1. Se0P2 4 a. Preparations and General Properties 4 b. Physical Properties 5 o. Spectroscopic Data 5 d. Structure 8 2. SeOCl 2 8 a. Preparations , 8 b. Physical Properties « 9 c. Spectroscopic Data and Structure 9 3. SeOBr2 10 a. Preparations 1° b. Physical Properties 11 - i v -Page 4. SeO(S0 5P) 2 11 a. Preparations 11 b. Physical Properties 12 c. Speotrosoopio Data 12 C. 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 I I . EXPERBffiHTAL 29 A. Chemicals 29 1. Reagents 29 a. Commercial 29 1) Se 29 2) P 2 29 3) B r 2 30 4) N2 30 5) Se0 2 30 6) SO, 30 7) Se0Cl 2 30 8) KBr 30 9) CC14 31 10) CFC1 31 - V -Page b. Prepared 31 X> S2°6P2 5 1 2) SeO(S0 5P) 2 31 3) SeP 4 32 4) SeOF 2 32 5) SeOBr 2 33 2. Products 33 a. E q u i l i b r i u m - t y p e 34 1) SeOFtSC^F) 34 2) SeOCl(S0 5F) 34 3) SeOBr(S0 5F) , 34 4) SeOCIF 35 5) SeOBrCl 35 6) 11 SeOBrF " 36 b. S a l t - t y p e 36 1) KSeOBr^ 36 B. Apparatus 36 1. Vacuum Lines 36 a. Glass 37 b. Konel 37 2. F 2 l i n e 38 a. S 20 6F 2 type 38 b. SeF 4 type 40 3. Drybox 41 - v i -4. Reactors 41 a. Erlenmeyer 41 b. Two-part pyrex 41 c. Two-part monel 41 d. Kel-F 45 e. SeOBr2 type 45 5. 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 6. Analyses 49 a. Borda 49 b. Bernhardt 49 C. Instruments 50 1. Raman 50 2. Infrared 50 a. P.E. 457 50 b. P.E. 301 52 3. MR 52 4. Conductivity 54 - v i i -Page III. RESULTS kKD DISCUSSIONS 56 A. The Vibrational Spectrum of SeOBr2 56 B. The Assignment of Vibrational Frequencies for SeO(S0 5F) 2 60 C. The Existence of SeOXY Molecules i n Ligand Redistribution Reactions 65 1. SeOBrCl , 66 2. SeOCIF 68 3. 11 SeOBrF " 70 4. SeOBr(S05F) 73 5. SeOCl(S05F) 77 6. Se0F(S05F) 79 7. Conclusions SI D. The Formation of a Salt between KBr and Se0Br 2 ... 82 BIBLIOGRAPHY. 86 - v i i i -LIST OP TABLES Table Page 1 Some Physical Constants of SeOX2-type Molecules 6 2 Vibrational Frequencies (cm"1) for SeOF2 and SeOCl 2 .. 7 3 Some Physical Constants of S0X2-type Molecules 18 4 Vibrational. Frequencies (cm - 1) for SeOBr2 58 5 Conductivity Data as a Function of Temperature for SeOBr2 6l 6 Vibrational Frequencies (cm-1) and Assignment for SeO(S0 5F) 2 64 7 Vibrational Frequencies (cm - 1) for SeOCl 2 and SeOBr2 i n Varying Ratios 67 8 Vibrational Frequencies (cm - 1) for SeOCl 2 and SeOF2 i n 1.0 : 1. 0 Ratio 69 9 ^ F Chemical Shifts for Some Selenium-Fluorine Compounds 71 10 Vibrational Frequencies (cm - 1) for SeOF2 and SeOBr2 i n 1.0 : 1.0 Ratio 72 11 Correlation of Selenium-Oxygen Compounds with Numbers 74 12 Vibrational Frequencies (cm - 1) for Some SeOX(SO^F) Compounds, X = P, CI, Br 75 13 Vibrational Frequencies (cm - 1) for Some 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 Force Constants ... 26 2 M e t a l F l u o r i n e L i n e I n c l u d i n g C a t a l y t i c S 2 0 g F 2 Reactor 39 3 Erlenmeyer Reactor L2 4 Two-part Pyrex Reactor 43 5 Two-part Monel Reactor 44 6 K e l - F Reactor 46 7 Se0Br 2- Type Reactor 47 8 K e l - F Raman C e l l 51 9 Far IR C e l l 53 10 C o n d u c t i v i t y C e l l 55 11 Raman Spectrum o f Se0Br 2 as a S o l i d ; Raman Spectrum o f Se0Br 2 as a Me l t 57 12 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 Functi o n o f Temperature 62 - X -ACOWVLEIXJEHEOTS I would like to sincerely thank Dr. F. Aubke for suggesting this topic of research and for helping me at every stage toward the completion of this project. Thanks are also extended to a l l the members of the research group for their helpful comments, and to Dr. A. Bree for his efforts i n helping to obtain the Far infrared results. - 1 -I. INTRODUCTION A. General Points The occurrence of ligand redistriubtion type reactions has been noted for approximately 100 years 1. But i t was not u n t i l Calingaert and co-workers began their studies on mixed alkyl lead compounds i n the 1940's that much was known about what was 2 5 occurring ' . Indeed, i t was only after somewhat more sophisticated physical techniques^ became available that interest began to increase i n this f i e l d of chemistry. Now many redistribution reactions are known, some of which include members of group VI A as the element under study. A recent interesting example i s the ligand redistribution reaction between SgBr^ and S^Cl^ where the compounds SgBrCl has been identified by vibrational techniques^. Another such case i s the precedent for diselenides to become involved i n an equilibrium type of ligand scrambling reaction as reported by Grant and Van Vfazer^. In this instance, (CH-) 2 Se or (CH^) 2Se 2 was reacted with S e 2 C l 2 to form divalent polyselenides with scrambled terminal substituents, such as CH-tSe^Cl, the chain 3 4 length of selenium varying i n number. Another case i s that of - 2 -Gillespie et a l 7 who attempted to study the mixed oxyhalides of selenium obtained from ligand redistribution type reactions, but who was only able to establish 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 reaction products. The means of detection i n both of these l a t t e r cases was with NMR spectroscopy, % and *^Se respectively. This tool can be of great use i f the lifetime of a product being investigated, i n a ligand exchange reaction i s significantly greater than the time span of the MR experimental procedure. Assuming this to be the case for 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 reaction (providing chemical s h i f t and coupling constant values peculiar to the system are reasonable). If, however, the lifetime of the product i s on the order of or much less than the time required for the NMR detection techniques, a different situation exists. One main difference might be a time averaging of resonance signals i n the IE-IE spectrum leading to a single peak which i s different i n position 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 for explanation. First, a situation similar to that above where a new produot i s formed via a ligand redistribution equilibrium except the lifetime of the new product is 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 for 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 for others this technique may not be applicable. In general, however, due to i t s relatively long time scale, EMR is not suited for investigations of the type where rapid exchange i s possible. In this regard i t became interesting to investiage the mixed selenium-oxyhalides by vibrational spectroscopy, especially with respect to SeOBrCl where results w i l l be shown to be contradictory. The time scale for EMR experiment i s generally between 1CT1 and 10~^ seconds, compared with that for —13 8 vibrational spectroscopy which i s on the order of 10 seconds 0. B. Selenium(lV)oxy-halides and a -pseudohalide This part w i l l very br i e f l y review previously reported work on the synthesis of oxyhalides of selenium(lV), including the related compound SeO(SO^F)2 and some of their physical properties pertinent to their intermolecular association and their subsequent dissociation into 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 far as they are known and on their vibrational spectra. Some general properties of the selenium(lV)oxyhalides and Se0(S0^F) 2 nay be br i e f l y mentioned: ( l ) They are a l l extremely moisture sensitive and easily undergo solvolysis reactions, (2) They are relatively - 4 -corrosive and sensitive toward oxidizable material and (3) They are toxic or very probably toxic l i k e many selenium compounds are known to be 9»10. These features pose many restrictions and make vacuum line and dry box operations mandatory. 1. SeOP2 a. Preparations and General Properties Selenium(IV)oxyfluoride, SeOFg, was made i n 1928 by reacting s i l v e r fluoride, AgF, with selenium(IV)oxychloride, SeOCl,,, SeOCl 2 + 2AgF SeOF2 + 2AgCl ( l ) The reaction had to be carried out i n a platinum bottle due to a decomposition of SeOF2 by glass reactors. It was l a t e r discovered that chlorine tr i f l u o r i d e , CIF^, when reacted with 13 selenium dioxide, SeCv,, would provide SeOFg i n a 11 good " y i e l d . Also mentioned i s the reaction of SeOCl 2 with HF to 14 generate the oxyfluoride according to SeOCl 2 + 2EF *- SeOF2 + 2HC1 (2) But the most efficient way to obtain SeOF2 i s by the reaction 15 of selenium tetrafluoride, SeF^, with Se0 2, where the y i e l d has been found to be nearly quantitative^ SeF 4 + Se0 2 ^ 2SeOF2 (3) Another route to obtain SeOF2 is the reaction of SeF^ with 17 Te0 2 according to: 2 SeF^ + Te0 2 *• 2 SeOF2 + TeF^ (4) Other novel reactions to obtain SeOF2 are described where reaction of suspended KaF i n a solvent reaction medium, such as tetramethylene-2 18 sulfone, i s effected with SeOCl,, , besides that of the direct 19 fluorination of Se0 2 b. Physical Properties The s o l u b i l i t i e s of several compounds in SeOP2 have been qualitatively established. For example, SeOF2 has been found 19 to be a solvent for sulfur and selenium metal ' as well as for ethyl alcohol. Besides, SeOF2 has been found to be soluble i n alcohol and tetramethylenesulfone, but not to any appreciable degree i n a non-polar solvent such as carbontetrachloride, CCl^ The vapor pressure curve of SeOF2 nay be represented as log p = 8.70 - 2316 T between 45° and 125°C. ^  From this equation, the Trouton constant may be calculated to be 26.85 indicating some association of the molecule i n the l i q u i d state. Please see Table 1 for other specific constants. c. Spectroscopic Data The vibrational (Raman) data have been compiled i n Table 2 for SeOFg. Accordingly i t may be noted that four vibrations-1005, 659, 368, and 271 cm - 1 - have been found to be polarized, and the other two- 601 and 305 cm"1 - depolarized , reflecting the 4 symmetrical (A 1) and 2 asymmetrical (A") modes respectively for a molecule of C g symmetry. 77 A Se HMR resonance has been observed for i t at + 100.6 ppm from SeOCl?- ^ - 6 -TAEL2 1 S o i e P h y s i c a l Constants of Se0X o - Tvoe K ^ l e c u l s s S e C ^ SeOCl,, S-03r 9 SeC(S0^F)2 •nelting P o i n t (°C) o 15 ' Q 10.9 ' 45 7 -^5 ( f . n . ) b o i l i n g p o i n t (°C) o 125-6 ' 177.2 9 21^?i,0deco;no. >200 s i . decorro. d e n s i t v (g/ce)" 2.30 q £ 21.5°C y 6 16°C 9 •2 50°C 0 •? i ' ° s p e c i f i c c o n d u c t i v i t y (•n.ho c;i ") 2.0 x 10" = & 25" C 6 x 1,T 5 i- 45-50 cC 1.5? x 10~;' d i e l e c t r i c c o n s t a n t *2 20°C dir-ole mo-neni (Debye) 22 2. Sif 2,o2 Trouton constant 17 26.35 - 7 -T A B L 2 2 V i b r a t i o n a l Frequencies ( c i T ) f o r SeOFg and SeCCL^ SeCF, reference S.F . cigTn=nt . 1 6 2 0 2 0 •3e=C 1 0 1 2 1 0 0 5 9 5 0 055 ( s , .:»e-A2 6 5 9 3 9 0 338 3 9 0 6 0 5 6 0 1 3 4 7 3 5 0 (s) O-Se-X 3 7 3 3 6 3 2 7 3 2 7 9 2 7 1 ^ ( a p ) O-Se-X 3 0 3 3 0 5 2 5 0 2-55 2U6 * X-Se-X 2 7 3 2 7 1 1 6 2 1 6 1 1 5 3 - a -d. Structure The structure of gaseous SeOF2 has been determined by means of microwave spectroscopy. The molecule i s best described as a distorted pyramid of C s symmetry with bond lengths 1.516k for Se-0 and 1.730 for Se-F, and bond angle 92.22° for P-Se-P 00 and 104.82° .for O-Se-F. In terms of Gillespie and Kyholm's 23 electron-pair repulsion theory the molecule can be viewed as a pseudo-tetrahedral species with one lone pair of electrons on selenium occupying one coordination s i t e . 2. SeOCl 2 a. Preparations SeOCl^ w a s f i r s t reported by V/eber in 1859 when he reacted 24 hot SeOg and SeCl^ vapors to obtain the l i q u i d product indicated by the reaction Se0 2 + SeCl 4 *• 2SeOCl 2 (7) However, the oxychloride can be made most simply by adding thionylchloride, S0C12, to Se0 2 i n i t i a l l y forming SeCl4 (and gaseous S0 2 as a byproduct), the SeCl 4 further reacting 25 26 with more Se0 2 to obtain the f i n a l product ' : S0C12 + Se0 2 »• SeOCl 2 + S0 2 (8) Alternatively Se0Cl 2 can be formed by the partial hydrolysis or complete dehydration of parent compounds SeCl^ and dichloroselenious 27,28 acid, H 2Se0 2Cl 2, respectively according to SeCl 4 + H 20 5- Se0Cl 2 + 2EC1 (9) / x H 2 S 0 4 Se(0H) 2Cl 2 ^ Se0Cl 2 + H 2S0 4'E 20 (10) - 9 -b. Physical Properties SeOCl 2 i s a hygroscopic colorless l i q u i d which has a specific conductance of 2.0 x 10 ~5 mho cm"1 ^ which indicates the separation of Se0Cl 2 molecules into ions. Indeed, the ionization of SeOClg has been further supported by ^ C l isotopic exchange reactions between labelled chloride salts dissolved i n Se0Cl 2 50>51# 32 The dielectric constant for SeOClg i s 46.2 at 20°C and i s relatively 33 high when compared to that of 9.25 (at 28° C) for SOClg Together, these properties suggest i t s use as a non-aqueous solvent, and correspondingly, work has been done i n this 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 polarization 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 38.,«39J although perhaps not to such a degree as i t i s f o r water molecules whose dielectric constant i s 78.3 at 25° C. 53 Supporting this case i s the infrared study made of SeOClg i n various solvents where the Se-0 stretching 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 position i n the neat l i q u i d state. 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 their results are collected i n Table 2. 20>41>42 A discussion of the structure has revealed that the molecule - 10 -is again best described as a distorted pyramid with C g symmetry. Such a molecule should give six Raman and infrared active peaks, four being symmetrical (A 1) and polarized, and two being asymmetrical (A") and depolarized in the Raman spectrum. This was confirmed 20 by Paetzold who also assigned the peaks their modes. In 77 7 addition, the 'Se KKR spectrum has also been recorded as w i l l be mentioned later. 3. SeOBr2 a. Preparations The synthesis of selenium(lV)oxybromide, Se0Br2, yielding yellowish-red needles was mentioned for 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 SeOBr2 ( l l ) Later i n 1913 Glauser44 d i s t i l l e d SeOCl 2 onto an excess of NaBr to obtain the same compound. SeOCl 2 + 2 NaBr SeOBr2 + NaCl (12) But i t was not unti l 1922, when efforts were made to prevent atmospheric moisture from entering the reaction system, that relatively pure SeOBr2 was made. 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 o + 2 Br„ -> 2SeOBr9 (13) - 11 -The product was s t i l l reddish-yellow, but later i t was found that i t could be purified .by vacuum sublimation and obtained o T as bright-yellow needles with a melting point of 45 C. b. Physical Properties The specific conductance of SeOBr2 has been measured as being 6 x lO'^mho cm"1 ^ at 45 - 50 °C for the product that Lehner obtained. However, no accurate temperature was recorded, nor was i t reported whether the temperature co-efficient of conductance has a positive 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 interesting to note that SeOBr^ i s immiscible with saturated aliphatic hydrocarbons such as hexane and decane. On the other hand Se0Br 2 has been found to be a suitable solvent i n the molten form for a number of other compounds such as 7 45 iodine, benzene and other selenium(lV)oxyhalides ' . A tabulation of other common properties i s made i n Table 1. Unlike the other oxyhalides, however, neither i t s spectroscopic properties nor i t s structure have been discussed previously. 4. SeO(S0 5P) 2 a. Preparations Seleniun(lV) oxyfluorosulfate, Se0(S0^F) 2 was prepared r e c e n t l y ^ by the action of peroxydisulfuryldifluoride, S^O^F^, upon Se0 2. This reaction, taking 10 hours at 50°C to achieve the products, was later improved upon when SgO^F^ was reacted with Se0Cl 2 to form Se0(S0jF) 2 at room temperature, - 12 -SeOCl 2 + S 20 6P 2 > SeO(S05P)2+ C l 2 (14) It was also discovered that bromine monofluorosulfate, BrOS02F, when reacted with SeOCl 2 would y i e l d similar results, SeOCl 2 + 2BrOS02F —-> Se0(S0 5F) 2 + 2BrCl (15) b. Physical Properties Se0(S0^F) 2 has proved to be very reactive, igniting paper i n an inert atmosphere. The specific conductance of the colorless viscous l i q u i d has been shown to be 1.59 x 10"^ at 25°C indicating that i t , too, i s ionizing i n neat solution. Its high viscosity and low vapor pressure have led 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 is soluble i n HSOjF, moderately so i n excess S20gF2,..and not at a l l i n CC1 Other pertinent physical 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 of the peaks was also presented.47 C. Some Aspects of Thionyl-halides and a -pseudohalide In this part w i l l be given a brief account of some chemical and physical properties of the thionylhalides and a related compound S0(S0^F)2. It i s intended for these properties to show both similarities and dissimilarities of these sulfur compounds to their selenium analogues, which i s of 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) for SOF,,, the strong fluorinating A A action of arsenic t r i f l u o r i d e on SOClg i s typical; b) for S0C12, the reaction of S0 2 with PCl^ can be used, forming the thionylhalide, ^ 8 and POCI3 as a by-product; and c) for SOBr2, the bromination of S0C12 by HBr ^ can be employed. The pseudothionylhalide, S0(S0jF) 2 has also been 50 reported and may be prepared i n an analogous was as that for Se0(S0jF) 2 - with S0C12 and BrOSOgF, c.f. reaction (15) S0C12 + 2BrOS02F »- SO(S0 5F) 2 + 2BrCl ( l6) Other analogous reactions of sulfur(lV) and selenium(IV)oxyhalides . 14 are when a) S0C12 is combined with HF to form the oxyfluoride, as i n reaction (2) according to: S0C12 + 2 HF S0F 2 + 2 HCl (17) 51 and when b) S0C12 i s reacted with Na3r to form the oxybromide, as i n reaction (12) according to: S0C12 + 2 NaBr —>• S0Br 2 + 2 NaCl (18) The vapor pressures of S0Br 2 and S0C12 have been described by 52 53 several workers. ' Both S0C12 and S0Br 2 are liquids at room temperature, but S0F 2 is a gas at that point, b.p. -43.8°C. In addition the orange-yellow color of liq u i d S0Br 2 compares well with the bright-yellow color of crystalline SeOBr,,. A l l of 54, - 14 -the sulfur(IV)oxyhalides are unstable toward water - each being e a s i l y and t o t a l l y hydrolyzed, 48,56 except i n the slow case o f 48 SOP^. Also n o t i c i n g that Se0Br 2 has been found to decompose upon or near i t s b o i l i n g p o i n t , 45,54 S U C A iia3 been found the case f o r 49 57 SQBr 2. I t i s so r e l a t i v e l y unstable that i t has been found to d i s s o c i a t e slowly at room temperature ( i n t o S 2 B r 2 , S 0 2 and B r 2 ) 49,53 A l l three simple oxyhalides o f s u l f u r ( i v ) are soluble i n r e l a t i v e l y non-polar solvents. 52,56 2. Structures Several d i f f e r e n t methods of an a l y s i s have a l l y i e l d e d common conclusions i n the determination of the molecular structures f o r the t h i o n y l h a l i d e s . In the case of SOP 2 a microwave study reports 58 the molecule's s t r u c t u r a l parameters^ , which when compared to the values found f o r SeOF 2 leads to the conclusion that t h i o n y l f l u o r i d e i s a d i s t o r t e d pyramid s i m i l a r to i t s selenium counterpart. An el e c t r o n d i f f r a c t i o n study of S0C1 2 has summarily stated that the 59 structure of t h i o n y l c h l o r i d e i s a l s o pyramidal i n shape , although a discrepancy o f values e x i s t s f o r the CI - S - CI bonding angle as determined by d i f f e r e n t workers. 59,60 An attempt to measure the s t r u c t u r a l parameters f o r S0Br 2 has been t r i e d by means of e l e c t r o n d i f f r a c t i o n ^ * , but not a l l o f the parameters have been determined. From those that were obtained, however, a pyramidal structure i s evidenced. - 15 -A l l molecules would yie l d six infrared and Raman active modes-four of class A' and two of class A". To verify such molecular symmetry, vibrational data have been obtained for each thionylhalide 57>62-67^  mostly via Raman spectra, which have shown the expected number and class of appropriate vibrations for G_ symmetry (except for SOF2 where one A 1 vibration has not been detected). Again, a pseudo-tetrahedral molecule with a lone pair of electrons occupying one coordination site may be assumed for 23 the thionylhalides . 3. Physical and Chemical Properties Of those properties that have been reported for the thionyl-halides, one is the dipole moment for SOP^ and SOClg. These values are 1.62 ^ and 1.58 °^ Debye, respectively, considerably lower than those measured for selenium(lV)oxy-halides. Vapor pressure data has also been obtained for each of the 53 55 68 thionylhalides ' ' with the vapor pressure equation of SOP^ being expressed as log p = 30.333-8.1053 log T -1908.4 T and that of S0C12 being log p = 7.60844 -1648.2 , T Trouton constants have been determined as well for the different halides 53,55 with the following values being respectively 22.6 for S0F 2 , 21.4 for S0C12 and 25.2 for S0Br 2. suggesting that the fluoride and the chloride are " normal " liquids whereas the bromide should be considered to be slightly associated i n the li q u i d state. In addition - 16 -the di e l e c t r i c constant and specific conductivity for 69 S0C12 have been measured 7 and are 9 . 0 5 (22° C) and 3.5 x 10~9 aho cm - 1 (20° C) respectively. On the basis of freezing point determinations^ i t has been reported that only weak comyounas are formed between SOCI2 S i C l ^ or Ti C i ^ , these molecules readily dissociating upon warming to liquids and capable of being independently separated. It might also be pointed out that the formation of no compounds i s indicated i n the systems studied involving 19 S0C1 2 and either CCl^, AsCl^ or SnCl^. F NMR studies, however, have provided evidence for complex formation between S0F 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 of S0F 2 with AsF^ reveal that only 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 2 have yielded the maximum upper limits for exchange half-times^l as being between ~>8 and ~13 minutes. In every case complete exchange was concluded to have occurred for labelled chloride ions, whether i n i t i a l l y as part of S0C12 or not. In the case of the pseudothionyl-50 halide, S0(S0^F) 2, only limited information i s available -' . 19 In i t s characterization, a F NMR signal has been observed i n the region typical for flurosulfates, - 52.7 ppa relative to CFClj, and i t s infrared spectrum recorded. The compound appears as a colorless l i q u i d at -22°C with a vapor pressure - 17 -of < 1 torr at 20°C, freezing to a glass at very low temperatures (Please see Table 3 f o r a compilation of physical data f o r the thionyl-halides) D. Mixed Oxyhalides of Sulfur and Selenium There are two main classes of compounds that may be included i n this group of mixed oxyhalides. These are when sulfur or selenium - r e p r e s e n t e d by E - form compounds o f t y p e s(l) EOXX' and (2) EOgXX', where X and X' are different halogens. Bie l a t t e r class (2), which i s of minor interest at this time, inolude SOgClP and SC^BrF which have been well investigated and are apparently unique and stable compounds No selenium analogues exist; i n fact, only SeOgFg * 8 k n o w n *o exist even among the possible simple oxyhalides. However, from class ( l ) , the most substantiated compound i s S0C1P. It has been reported as being prepared i n 20$ y i e l d by the action of SbFj and SbCl^ on 55 73 SOClg » or i n the reaction of IP^ with SOClg upon heating. % J Also suggested was the obtaining of SOBrF by the interaction of S0Br 2 and a halogen-fluoride such as IF^, but no synthesis by this or 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 tried to reproduce the experiment and isolate the compound by fractional 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 derivatives T A B L E 3 Some P h y s i c a l Constnnts of SOXp - Tyne Cowoound.s S0F 2 S0C1 ? S0Br ? S0(S0 3F) 2 ra«?l.t.in,T p o i n t (°C) -U0 . 5 5 4 -10 5 5U -52 •colorless CA l i q u i d ® -22 3 b o i l i n g p o i n t (°C) - 4 3 . 8 5 4 ' 5 5 140 decomn. 7 7 3 t o r r 5^  .',.0 t o r r 54 d e n s i t y (g/cc) ( G ^ ) . _ 2 ^ > A l _ ^ 1.780 5 i ( . © - 100°C" S*13°C 5 4 snpci f i c c o n d u c t i v i t y ( : T i h o c n ~ l ) 3.5 x 10-l> @ 20°C 6 9 d i e l e c t r i c cons t.mt @ 22°C 5-di-Qolf! mo-n^nt (Debve) 1.62 P Trou ton con;- t.-tnt , 55 ??..6 ' 21.4 5 5 2 5 . 2 5 3 r>r<v sure eqn.'1 t i on lo(? t>= 3 0 . 3 3-3 . 1 0 5 3 1 log! - 1903.U/T 6R lop; 0 = 7 . 60 ^'44 cp - l6-'43.?/T < 1 t.nrr @ _'!2°C ^ 0 -19 -may also be included i n this discussion since the fluorosulfate group can be classed as a pseudc— halogen. Indeed, the existence of , . 50 a compound of the type SOCl^SO^F) was evidenced by Des Marteau; however, a pure product was not obtained. Very limited information i s available on analogous mixed halogen Se-0 derivatives. Yarovenko et al claimed i n 1961 the f i r s t preparation of SeOBrCl from S e ^ r ^ Se0 2 and 75 C l 2 i n 15/a y i e l d . The SeOBrCl was reportedly obtained by fractional d i s t i l l a t i o n under reduced pressure. Measured properties included only i t s boiling point and density. In 1950 Wiechert mentioned a reaction of Se0Cl 2 with anhydrous HF, 14 the remaining product after which contained chloride. It was also stated that the reaction " had the appearance as i f great quantities of SeOCIF were formed. " Gillespie et a l 77 i n 1965 using Se nuclear magnetic resonance techniques, studied equisolar binary mixtures of SeOF2 with SeOCl 2 and 7 SeOBr2 . Evidence was obtained only for SeOCIF by the presence of an additional ^Se KMR signal different from those for the starting materials of the mixture. The possibility of SeOBrCl being formed in the equilibrium of SeOCl 2 and SeOBr2 was based upon the presence of a single broad peak located between those measured for the two parent compounds indicating rapid ligand exchange. No evidence was found by these techniques, however, for a similar SeOBrF species being formed, with only the resonances - 20 -for SeOP2 and SeOBr2 being observed. The compound SeOCl(SOjF) also was apparently obtained i n an equimolar reaction of Se0(S0jF) 2 and SeOCl 2 as reported by Carter. ^ Evidence for the existence of the mixed compound is promoted mainly from "^F and 77se resonances as well as from i t s vibrational spectrum. These data indicate the presence of a separate compound apart from both parent compounds. E. Bonding In Thionylhalides Based on the vibrational frequencies obtained from Raman spectra, force constant calculations have been carried out 76 for the thionylhalides as well as for other related sulfur-oxygen compounds. 77>78,79 rp n e progressively stronger S=0 bond trend as expressed by these force constants for thionyl-halides, as the halide varies from Br to F, reflects the greater a b i l i t y of S0F 2 to engage i n multiple bond formation between sulfur and oxygen, than i s the case for S0Br 2. To explain this, a dative bond formation involving the electrons in oxygen's 2p energy levels and the empty orbitals of sulfur's 5d 2 or 3d 2 2 energy levels have been proposed- 8 C^a),20 z x-y generally termed pn-»dit bonding. More sp e c i f i c a l l y , 81 Cruickshank discusses the evidence for such pTT-^d-n-bonding between oxygen and elements with vacant 3d orbitals, such as S i , P, S, and CI, i n tetrahedrally or pseudotetrahedrally coordinated polyhedra on the bases of available molecular structures. - 21 -The results of this axe briefly summarized as follows. The element-oxygen bond, S-O, i n thionylhalides can be described by the three different resonance forms 80(a) X X S = 0 s = + 0 (a) (b) (c) When X i s an electron donating group, (a) i s the most probable resonance structure. An increase i n electronegativity for 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 and corresponding stretching force constants, (3) dipole moment values, which w i l l reflect a decreasing a b i l i t y for oxygen to act as a donor and sulfur 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 for the thionylhalides and related molecules that their 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 2S0 > ClgSO > PgSO. The S=0 stretching frequencies w i l l increase at the same time as the S»0 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 -22 -Trouton constants, as well as the vibrational frequencies and force constants, some values of which have been mentioned earlier (please see section I.C.). In addition to these data a correlation has been made between force constants and bond lengths, besides one between bond lengths and bond orders, as calculated by the authors. 8 2 The failure to obtain stable oxygen-donor type complexes with good acceptors such as SnCl^ for S0C12 4° , and BF^, AsF,_ 71 70 and SbPjj for S0F 2 may also be attributed to intensive p-TwdTT bonding for 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, f a l l into the same category as oxygen-donor a b i l i t i e s . 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 results obtained for S0 2 i n superacid media (KSO^F, SO^, SbF- mixture), the strongest protonating agent avialable, which show a complete lack of evidence 84 for the protonation of S0 2. This view departs i n one aspect from the original ideas of Cruickshank, and subsequently also Gillespie and Robinson. By postulating participation of two of sulfur's 3d orbitals, the maximum-n bond order was restricted to 2, and the 82 total bond order was limited to 6. This maximum value is achieved as i n the case of s0 2*2 w h e n sulfur-oxygen - 23 -bond order i s described as being 2. It is therefore a r b i t r a r i l y assumed that the bond order for the S-F bond i n S0 2F 2 i s 1.0. This, however, i s contradicted by the relatively short sulfur-fluorine bond distances and parallel trends i n the S-F stretching frequence and stretching force constant as noted for those trends between sulfur and oxygen. There i s , i n fact, good evidence that some p-rr-^d-TT 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 via p T T —s»dTT bonding, but i t is found that the assignment of bond orders are slightly misleading. F. Bonding i n Selenium(lY)Oxyhalides This section w i l l center mainly around the following points: a) Is there any evidence for p-rr-^ d-rt bonding i n Se-0 compounds? b) How can differences i n physical properties best be rationalized based on bonding descriptions? c) What differences i n chemical behavior are found and are expected? Since section I.B. has shown strong structural analogies between Se-0 and S-0 compounds of the type discussed (taking into consideration the presence of a stereochemically active lone 23 pair of eleotrons i n both thionyl-.and selenium(lV)oxy-halides) , the orbital symmetry requirements for pTT->d-rr bonding are met. The difference must be seen i n the involvement of 3d orbitals - 24 -on sulfur versus 4d orbitals on selenium as the acceptor orbitals. It i s generally assumed especially for element of groups IV and VI a, 8 0 ( b ) , ( c ) that 4d orbitals are higher i n energy and are also more diffuse than their 3d counterparts. This means p-rr-s> d-rr back-donation w i l l be less efficient for selenium. This expectation i s ill u s t r a t e d by the material provided 21 20 from structure determination and vibrational spectroscopy. ' Se-0 bond distances are found to vary i n the same way as found for those of S-0 compounds; the variation again can be related to an electron inductive effect exerted by the other atoms or 86 groups attached to Se. Consequently, similar variations i n Se-0 stretching modes and force constants have been observed for tetrahedrally coordinate selenium-oxygen compounds, as have been found for the ones encountered i n sulfur-oxygen compounds. In IV compounds of the type XgSe 0, strong dependence ofU on f i s noted: the observed trend i s SeO SeO 82 parallel to the one found for sulfur-oxygen compounds. Numerically the selenium-oxygen force constants 20>85 are lower than the ones of sulfur-oxygen i n compounds with identical ligands X. It can also be seen that both sets of force oonstants were derived by the same methods. This means the Se-0 bonds w i l l be weaker and longer. The three resonance structures proposed earlier for S0X2 type molecules w i l l be much the same for Se0X2 compounds, namely - 25 -S e - 0 Se = 0 -s ^ Se = 0 ^ (a) (b) (c) Contributions from (a), however, w i l l be far more dominant i n Se-0 compounds than for S-0 compounds with respect to molecular bonding. This i s reflected i n empirical relationships between the stretching force constants i n identical sulfur-oxygen and 87 selenium-oxygen compounds as proposed by Paetzold, which may be written as f = 1.687«f - 2.30 and SO SeO fSeO " °- 5 9 3- f30 * 1 - 3 7 ' and i s il 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. That this i s due to less e f f i c i e n t p K~»d - r r bonding rather than <T bonding effects is^evident from the electronegativities for sulfur and selenium which are almost identical (Pauling scale: S = 2.58 and Se = 2.55, Allred-Rochow scale: S = 2.44 and Se = 2.48). 8 0C d) Because of a l l this, Se-0 compounds are bettter 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 for S0X2 compounds acting this way are known. Furthermore, a stronger intermolecular association for SeOXg - 26 -C O N S T A N T S FIGURE 1 - 27 -compounds i s expected with a possibility of a heterolytic cleavage of associated molecules into conducting fragments. These points are substantiated by physical data, such as melting points, boiling points, Trouton constants and specific conductances, which have been discussed earlier. To help clarify the above claim, several examples are now shown i l l u s t r a t i n g ( l ) SeOX2 compounds as donors, and (2) SeOX^ compounds as acceptors. For case ( l ) there i s much data, since several adducts have been reported for the selenium(lV)oxyhalides. Even for SeOF2, a complex SeOF2 - 17bF^  i s reported. The crystal structure has established that donation from oxygen occurs, rather than from fluoride-ion-transfer and NbFg ion formation. A similar addition compound has been prepared between SeOClg and SbCltj with 1:1 stoichiometry where i t s crystal structure i s also reported. 8 Q / With SnCl^ the stoichiometry is for a di-adduct of SeOClg, including cis 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 . ^ 8 SeOBr2 has been found to yi e l d an adduct with SnBr. of the form SnBr,^ SeOBr., where 4 4 2' 1 1 0 ,Sn Mossbauer and vibrational spectra have indicated donation from oxygen and cis octahedral configuration for t i n . It i s noteworthy at this'time to point out that of the two possible modes of complex formation a) a X2SeO + liX^ > (X^eO-*^ and - 28 -b) m X2SeO + > (XSeO)J m (MX n f a)- m, only type a) i s found to occur. For case (2), where SeOX2 compounds act as acceptors, a large number of complexes of SeOClg are reported. ^ 8 The crystal structure of SeOCl 2«2 C5H5N ^ 2 indicates a pseudo-octahedral environment for selenium. In 38 addition, a complex with SeOBr2 and dioxane has been mentioned. SeOX2 compounds can act as halide ion acceptors according to KX + SeOX2 >- K(SeOX5) where X may be F or CI. 2 6 ' 9 5 Vibrational analysis indicates C_ symmetry i o r the SeOXr ion, a j and thus a distorted pseudo-trigonal bipyramidal structure with X i n both of the axial positions. Evidence of (inseparable mixture products of the type K (SeOClnF5_n) has also been obtained. 26 - 29 -II. EXPERIMEETAL A. Chemicals 1. Reagents Except for 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 for most of them i n the laboratory were conducted with starting materials easily acquired from commercial sources or shelf stocks, a. Commercial 1) Elemental selenium, Se, was supplied by B r i t i s h Drug Houses,Inc.(BDH) at>99fo purity. To ensure the absence of a l l moisture the Se was also crushed and dried at 140°C for at least six 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 long b r i t t l e 56 strands which were then crushed and dried for 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 fluoride, ITaP, metal trap to remove hydrogen fluoride, HP* No attempt vas made to remove the other impurities commonly present i n the P 2 such as 02> Ng or OFg. A high pressure Autoclave Engineering valve and Crosby high pressure gauge regulated the flow of P 2 from the cylinder. 3) Elemental bromine, Br g, was supplied by BDH at > 99.0$ purity and used without further pur i f i c a t i o n . 4) The nitrogen, N 2, used i n maintaining inert atmospheres i n the drybox and reactors^ was of L grade and supplied by Matheson of Canada, Ltd. 5) Selenium dioxide, Se02, was also obtained from EDH at > 99.0$ purity, but was heated to 150°C i n vacuo for 12 hours i n order to remove any traces of moisture that may have been present as supplied. 10,»5*> 6) Sulfur trioxide, SO^, wa3 purchased from Baker and Adams on, A l l i e d Chemical Corporation, as "Sulfan" (purity not given) and used without purification. 7) Selenium(IV) oxychloride, SeOClg, was obtained from EDH i n a glass-sealed vessel, and used without purification. The purity of the straw-yellow colored l i q u i d was > 97.5$ 8) The potassium bromide, K3r, was of reagent grade and was' supplied by Baker and Adamson as crystals, which were subsequently crushed and dried at 150°C before use. - 31 -9) Reagent grade carbontetrachioride, CCl^, was stored over Linde 5A Molecular Sieves for 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 purity not given, b. Prepared 1) Peroxydisulfuryldifluoride, S-O-P , was prepared i n 500g & o 2 quantities by the general method of Shreeve and Cady After having passed through a KaP trap, p was mixed with dry N 5 and SO i n a s i l v e r ( l l ) fluoride, AgP2, catalyzed furnace ^ 3 0 reactor. Please see section II. B. 2. a. After reaction at 180 C the S^O^F^ was trapped i n -78°C dry ice traps and later purified by fractional 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 infrared spectra. Any unreacted SO^ was removed by extraction with oleum, concentrated B^SO^. 2) Selenium(lV) oxyfluorosulfate, SeO(SO^P)2> w a s prepared according to'Carter and Aubke. ^ Typically 7.5 g (45.3 a moles) of SeOClg was weighed into a pyrex Erlenmeyer reactor including a Teflon coated magnetic s t i r r i n g bar, i n a drybox. S 20gP 2 was then d i s t i l l e d in. vacuo onto the SeOCl 2 i n small amounts and stirred. The chlorine, C l 2 , that was evolved was rapidly pumped off to prevent the formation of chlorinemonofluorosulfate, C10S02F, as a side product. The process was repeated u n t i l no further S O^P was taken up, and the identity of the product 2 o 2 - 32 -•was checked by weight increase appropriate for a quantitative transformation to Se0(S0^F) 2 from the SeOCl 2 as well as by i t s Raman spectrum. 3) Seleniumtetrafluoride, SeF^, was prepared i n amounts of 15-20g 19 by passing a slow stream of F 2 diluted with dry N 2 over dried Se. Roughly 20g of Se was finely ground and evenly spread on the f l a t base of the main reactor which was purged of a l l atmospheric a i r and moisture by a flow of dry N 2 overnight. Then the reactor was placed i n a -10°C salt-ice slush bath. The next two collection traps for the SeF^ were held at -30°C which allowed the unreacted F o J N and any SeF A formed as byproducts to pass through the flow c. 2 O type system. A third trap equipped with vacuum stopcocks followed, and was used only as an intermediary storage vessel for 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 identified by comparing i t s Raman spectrum to the one reported i n the literature for SeF^. 4) l6.65g of selenium(lY) oxyfluoride, SeOF2, was generated by 15 heating SeF^ with an excess of SeOg. J In practice 8.4g (75.5 m moies) of dried SeOg was placed i n a two-part monel reactor and 9.7g (62.6 m moles) of 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 for 12 hours. The clear colorless liquid,which was also stored over the Se0 2 i n i t s reactor, was found to be SeOF2 by i t s NMR and Raman spectra. - 33 -5) Selenium(lV) oxybronide, SeOBr^, was prepared i n 30.5g quantities (1x9.0 m moles) basically as described by Lehner. A slight excess of Se, 4.80g or 60.8 m moles Se, was mixed thoroughly i n the drybox with b.JjOg (59.5 m moles) Se0 2, and put i n a reacor f i t t e d with a dropping funnel. A large excess of Br 2, 30 ml at 0°C, was then added via the funnel - the B r 2 being cooled to partly absorb the heat of formation of Se^rg, an intermediate i n the formation of Se03r 2. As i t was, the reactor was placed i n an ice bath, 0°C. After the f i n a l addition of Br 2 the reaction products were warmed to room temperature and mixed thoroughly. Pure Se0Br 2 could be obtained by pumping off the excess Br 2 at -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 crystalline needles whose melting point was 44«5°C ( l i t 41.7°C 4 5 , and 45°C 1 ) . 2. Products As has already been implied, the reactions giving the products to be described i n this section, except xor the salt-type reaction yielding KSeOBr^, are equilibria reactions -SeOX2 + Se0Y2 ^-^ 2Se0XT. In a l l cases of this 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 for the f i r s t time by combining SeO(3C F ) ? •with 5eOP2. I n i t i a l l y 0.775g (5.83 a moles) was d i s t i l l e d i n vacuo on a monel metal vacuum line into a Kel-P reaction vessel. Then 1.700g (5.80 m moles) Se0(S0^?) 2 was added to the 3e0P2 in a dry box via a 1.00 ml pipette and " pi-punp" assembly (Please see II.B.5.e.) - the mass of Se0(S0,P)2 determined by a balance located within the drybox. The mixture was shaken even though the starting materials mixed readily to form a yellow-tinged product whose viscosity was intermediate between that of SeOP2 and SeC(S0jP) 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 (7»52 a moles) of Se0(S0^P)2 was weighed into the reactor. Subsequently 1.241 g (7.51 m moles) of SeOCl 2 was added with the pipette assembly to the correct quantity by volume and mass - the whole operation being conducted i n the inert atmosphere of the drybox. Only after vigorous mixing did the two liquids become homogeneous, the viscosity of which was greater than that of either of the starting materials. 3) The corresponding new bromo compound, selenium(IV) oxybromo-fluorosulfate, SeOBr(SO^P), was made by f i r s t weighing 1.142g (3.91 ci moles) Se0(S0~?) 2 into a two-part glass reactor, and then adding 0.998g (3.91 n moles) of finely crushed Se0Br 2 i n - 35 -the drybox with the aid of the balance. Upon f i r s t addition of the reactant3 a reddish color was imparted to the SeC^SO^F),, but eventually a hard yellowish-orange cake-like substance appeared at the bottom of the reactor. A f t e r heating to 105°C, however, sol u t i o n of a l l reactants was effected to a l i g h t crimson-red l i q u i d which eventually turned to a homogeneous yellow wax upon cooling to room temperature. 4) The reaction of SeOF2 with SeOClg to form seleniua(IV) 7 oxychlorofluoride, SeOCIF, proceeded by the d i s t i l l a t i o n of 1.900g (14.28 m moles) of SeOF2 into a Kel-F trap, and followed by the addition of 2.350g (14.20 m moles) of SeOCl 2 v i a the pipette assembly i n the drybox. The two reactants mixed easily to give a clear yellowish l i q u i d . 5) Although the preparation of selenium(rv) ojcybi-owGchloride, SeOBrCl, has been claimed previously by the addition of SeOg 75 and C l 2 to Se 2Br 2, the seemingly simpler method of adding SeOCl 2 to SeOBr2 was employed. To begin, 1.662 g (6.52 m moles) of fi n e l y ground SeOBr 2 was weighed i n t o a two-part pyrex reactor containing a Teflon-coated magnetic s t i r r i n g bar; 1.085g (6.54 m moles) of SeOCl 2 was added with the pipette assembly - a l l i n the drybox. The SeOBr 2 did not t o t a l l y dissolve i n the SeOCl 2 u n t i l the reactants were heated to about 5O°0 (even with s t i r r i n g ) where upon a dark red-brown sol u t i o n was obtained wtiich remained so at room temperature. - 36 -6) In the attempt to make selenium(lV) oxybromofluoride, SeOBrF,' 3.250g (24.OO m moles) of SeOF2 w a s o n c e again d i s t i l l e d i n vacuo into a Kel-F tube, and 6.058g (23-70 m moles) of finely crushed Se0Br 2 was added in the drybox by weight. The SeOBr,, f a i l e d to totally dissolve i n the Se0F2, although i t did impart a red-orange color to the l i q u i d phase. After heating the mixture to 50°C, however, an intensely dark, almost black, solution was seen with a l l of the Se03r 2 dissolved - remaining so at room temperature. b. Salt-type l ) The salt potassium oxotribromoselenate(lV)> KSeOBr^, was prepared by adding an excess, 2.683g (l0.52~ia moles) of finely crushed Se0Br 2 to 0.513g (4.31 m moles) of powdered and dried KBr i n a f l a t bottomed two-part pyrex reactor, the Se03r 2 added i n the drybox. The raix+.rre was then heated to 55°C and stirred (with a magnetic Teflon-coated s t i r r i n g bar) for an hour. The resulting 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 indicating dissolved Se03r 2 i n the CCl^. 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 of a l l compounds because of their highly toxic and hygroscopic behaviour. In order to achieve and maintain - 37 -a necessary vacuum for the lines, a Welch Duo-Seal Pump, Hodel I4OO, was used, capable of obtaining a vacuum of 10"^  torr. The pump was connected to the lines through a l i q u i d cold trap which collected stray volatile materials before they could be drawn through the pump. a. Glass The main manifold of the glass vacuum line was made of pyrex tubing, 65 cm long and 20 mm diameter, sealed off at one end and connected to the cold trap by a Fischer-Porter 4mm glass and teflon stopcock and B19 ground glass cone and socket. Four additional Fischer-Porter stopcocks served as inlets to the manifold to which reactors and other kinds of 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 of the previously mentioned vacuum l i n e , a monel line had to be used- The metal i t s e l f was a copper-nickel alloy fashioned into tubing-j-" o.d. and l/32" wall thickness. The line was 70 cm long and was attached to the cold trap via a "Cajon" glass-metal connector, Columbia Valves and Fittings, Vancouver, B.C., B19 cone and socket, and a Whitey-type- valve IKS4.316, Whitey Research Tool Co., Oakland, California. At various intervals T-pieces serving as inlets for the reactors, etc. were s i l v e r soldered into the l i n e . At each of these inlets was attached a Whitey valve, connected by Swagelok f i t t i n g s and Teflon ferrules, Crawford Fittings - 38 -(Canada) Ltd., Niagara Palls. A Kontes thermocouple gauge, model 2A, Televac, The Predricks Co., was used as a means to check 3 leaktightness and pressures of 10 to 1 torr. 2. Metal Fluorine Line For the preparations of S 20gF 2 and SeF^ i t became necessary to use a system suitable for flow reactions. The fluorine line used consisted basically 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., Creskill, New Jersey, and Autoclave Engineering Inc., Erie, 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 either be mixed with dry N 2 or not. After this, the flow of fluorine could be led directly to a reactor furnace where another i n l e t would allow other gases to mix -with the fluorine 3as in.the preparation of S2^6 F2J o r ^ cou-1-<* b e l e c* *° another type of reaction apparatus bypassing the high temperature reactor. (See Figure 2) a. S 20gF 2 type In the case of the 3 20gP 2 reaction, F 2 was mixed with a stream of N 2 and SO^  i n the furnace reactor, heated to —180°C by a series of el e c t r i c a l windings, the temperature being controlled by a variable rheostat. The resulting products then passed into a series of traps, the f i r s t of which was maintained at room temperature to collect any solids (.polymeric 50-^) and the rest were heid at dry ice temperature (-78°Cj to collect the S 2u bF^ but allow FSo^F, To Flowmeter Copper Glass SOOml . Pyrex F lask Reac to r (J) Whitey Va lve •0- H o k e 4 1 3 Va lve pp] Autoc lave Engineer ing I—I Valves FIGURE 2 NaF Trap •8-, 9 c m 1 L CrO'-by Prcoourc Guage r h J l — r h . 1_J -20cm-*-F 2 Outlet To F^  cylinder Copper Glass B 3 4 A B 3 4 B B 3 4 To Soda - lime Trap -Fluorolube Oil Tube C M E T A L F L U O R I N E LINE INCLUDING C A T A L Y T I C S ^ F ^ , R E A C T O R - 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 Fa l l s . A l l connections between traps were made with BIO cones and sockets. (Please see Fig. 2) b. SeFj type For the generation of SeF^, F^ diluted with was entered through a Fluorolube o i l bubble-type flow meter, (attached with Swagelok fi t t i n g s to the main F 2 outlet) into a two-liter f l a t bottomed flask, i t s e l f attached to the flow meter with a B19 cone and socket. To this main reactor flask were connected two primary collection bulbs via B19 cones and sockets. These bulbs, 10 cm long and 40 mm diam., were immersed i n trichloroethylene-dry ice baths of -30°C to trap the SeF^ but allow F 2,N 2 and SeF^ to pass through. Next i n the line, 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 collect 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 last trap with vacuum tubing. Thi3 same last trap could also be attached with Swagelok f i t t i n g s to the monel vacuum line previously described for the transfer of the SeF^ into i t s monel storage vessel. - 41 -3. Drybox The drybox used i n the course of the experiments to exclude atmospheric a i r and moisture was obtained from Vacuum Atmospheres Corporation (VAC), Model HE-43-2 Dri-Lab, The nitrogen 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 sieves. These sieves were regenerated a f t e r about a month's use by a heating u n i t located with the drybox i t s e l f , VAC, Model HE-93-B Dri-Train. 4. Reactors a. Erlenaeyer A s p e c i a l pyrex reactor (Pig.3), constructed of a 125-ml erlanmayer flask equipped with a Fischer-Porter Teflon stopcock, and a constricted neck which could be sealed o f f a f t e r the addition of so l i d s and l i q u i d s was occasionally used. A BIO cone allowed the vessel to be attached to the vacuum system. b. Two-part Pyrex In addition, a two-part pyrex reactor ( F i g . 4) was employed which consisted of a t e f l o n Fischer-Porter stopcock connected to a vessel 10 cm long and 16 mm diam., separable v i a a B19 ground glass cone and socket. A BIO cone permitted i t to be attached to a vacuum l i n e . c. Two-part Monel A t o t a l l y monel reactor ( F i g . 5) was used i n the preparation of Se0F 2 because of i t s resistance to attack by SeOF2, which attacks pyrex reactors. The main reactor 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 ischer and Porter Teflon React ion Vessel Valve FIGURE 3 « 7 . - -FIGURE 4 TWO-PART M O N E L REACTOR ( Lid CC n Hoke Valve ( No 431) Monel Metal Tube Bolts to Secure Lid to Bottom Vessel \ P -4 Condenser Inlet \ 1 JD Bot tom 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 teflon gasket providing the seal. A Whitey valve was joined to the l i d i n l e t and the monel vacuum line with Swagelok f i t t i n g s . d. Kel-F Another reactor of considerable use wliere glass-reacting compounds were used was a Kel-F reactor (Fig. 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 direct vacuum tight seal. To the monel top was joined a metal bellows-type Hoke valve. The whole reactor was then attached to a monel vacuum l i n e with Swagelok f i t t i n g s . e. SeOBr^ type The preparation of SeOBrg required a vessel that would exclude at-mospheric moisture outside the dry box, and be capable of being evacuated. With this i n mind,a 250 ml round bottom reactor equipped with a B24 cone was assembled to a dropping funnel (Fig. 7). The dropping funnel was constructed with a B19 cone at the top, l a t e r capped with a sealed o f f B19 socket. In addition, the funnel had a teflon stopcock allowing the Br^ to be added to the Se and Se02 i n the reactor without contamination with stopcock grease. Also as part 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 . - 46 -FIGURE 6 SeOBr 2 — T Y P E R E A C T O R - 48 -5. Miscellaneous a. Vacuum, f i l t r a t i o n apparatus A pyres device designed to separate liquids 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 off B24 socket, and enclosed at the bottom with a 250ml round bottomed flask having a B24 socket. From each half 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 for the drying of CCl^ and for the drybox's circulation system were Linda chromatograph grade 5A sieves purchased from Union Carbide, Eedondo Beach, California. Molecular sieves for drying CCl^ were heated i n vacuo for 24 hoars at 150°C "before use. d. Lnbrioating Grease A l l cones and sockets described i n the preceeding seotions were lubricated with a low-volatility 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., Pair Lawn, New Jersey, as Fluorolube Grease GE-90 distributed by Fisher Scienti f i c Co. e. " pi-pump " A pipetting device used quite regularly i n this work a^nd suitable for manipulation i n the dry box was made by G l a s f i m of West Germany and distributed through Bel-Art Products, Pequannock, Hew Jersey. It consisted of an acid resistant 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 position by an externally located and maneuverable cogged wheel. The m^-Hrm™ volume transferable at one time was 2 ml. 6. Analyses The Br analysis on KSeOBr^ was done by Mr. P. Borda, UBC, while the Se analysis on the same compound was done by Alfred Bernhardt Mikxcanalytisches Laboratoriua, 5251 Elbach uber Engelskirohen, West Germany. C. Instruments 1. Raman The Raman spectra of the compounds were measured with a Cary 81 spectrophotometer acoompanied by a Speotraphysios Model 125 He-Ne laser 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 la t e r flame-sealed a i r tight, or a bent right angle tube 10 cm i n total length and 5 nm i n diameter, equipped with a spacer to allow a relatively small amount of sample to be analyzed, which could also be sealed off with a torch after the introduction of liquids* A special Kel-F Raman tube was also designed and used for 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 teflon plug (Fig. 8). 2. Infrared a. P.E, 457 Infrared spectrographs were recorded by means of a Perkin-Elmer Model 457 Grating Infrared Spectrophotometer i n the range 4000-250 cm"1. Samples were generally run neat between two windows, 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 -K E L - F R A M A N C E L L l ? J l fW1 k f 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 sufficient 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**1, which needed to be 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 for the transmission of l i g h t and detection of sample vibrations were made of 1 mm thick pieces of polyethylene which had no absorptions i n this region. In conjunction with these windows was constructed an infrared c e l l for liquids and solids which had the windows separated by a 1mm stainless steel spacer (Pig. 9). Liquids could be introduced with a syringe, or solids could be placed directly into the c e l l , which was f i n a l l y sealed with teflon plugs. 3. Nuclear Magnetic Resonance ^ P Nuclear Magnetic Resonance chemical shifts 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 F I G U R E 9 FAR IR C E L L an external reference tube of Freon 11, CFClj, (taken as Zero) located within the sample tube. 4. Conductivity The conductivity of SeOBr2 as a l i q u i d was measured as a function of temperature with the aid of a conductivity bridge, Universal Bridge Model B221-A, obtained from the Wayne Kerr Laboratories Ltd. Measurements of 0.080 /mho to 25.34 ;umho were read when the e l e c t r i c a l leads of 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 of a two-liter beaker wrapped several times with asbestos paper fo r insulation, and f i l l e d with Fisher 02 High Temperature Bath O i l which was constantly stirred by means of 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 the drybox. These e l e c t r o d e s were platinized with 'platinum black" by electrolysis from a hexachloro-95 p l a t i n a t e ( _ I V ) s o l u t i o n i n HC1 as recommended. The power source source was a Model D-612T f i l t e r e d power supply 0-l6 volts, purchased from Fisher Scienti f i c Company. A calibration of the c e l l was done with a 1.070 x 10-2M solution of KC1, giving a c e l l constant of 0.8135 cm"1. - 55 -F I G U R E 10 CONDUCTIVITY C E L L III. RESULTS AND DISCUSSIONS A. The Vibrational Spectrum of SeOBr,, No vibrational data for SeOBr2 has been previously reported, but the molecular structure of this compound i s expected to be either pyramidal or planar, that i s , with or without a stereochemically active lone pair of electrons. The results of the Raman spectra as shown i n Figure 11 are l i s t e d below i n Table 4 for SeOBr2 as a solid, as a melt and i n benzene. The six bands which are described may be taken as the six fundamental vibrations of the SeOEr2 molecule. The polarization data have been obtained only i n the molten state of SeOBr2. As can be seen there are four polarized peaks representing symmetric vibrational modes, and two depolarized ones characteristic of asymmetric vibrations. These results immediately rule out structures of point groups C-^ , with six expected polarized modes, as well as C 2 v , which should have only three symmetric vibrations. The only reasonable choice l e f t i s v.hat of C g symmetry,in agreement 20 with findings for SeOF2 and SeOCl 2 . This implies that SeOBr2 i s a non-planar pyramidal molecule with a stereochemically active lone pair. Complete assignment of the six modes follows closely the reported assignment for selenium(lV)oxyfluoride and -chloride. The - 57 -Raman Spectrum of S e O B r 2 as a solid 1 0 5 2 3 0 3 0 2 2 9 1 " 2 7 5 9 1 Q 8 9 3 2 0 8 Raman Spec t rum 2 2 2 of Se O Br 2 as a melt 1 0 0 0 2 8 6 9 3 4 1 0 4 — 1 I 7 5 1 0 0 0 Wavenumber (cm - 1 ) F I G U R E 11 —1 7 5 TABLS 4 Vibrational Frequencies (cm"""'-) for S^ ORr^  [rela tive intensity of neaks in ( ),~] Raman Infrarod /issipn'Jient Cr.ys talline Molten In (§> (dilute) In © (dilute) Crystal! ine C910 (2.9)1 t-393 (2.4)3" 9 3 4 ( P ) ( 1 . 9 ) 960 (10.0) 9^5(sh) C905-? 1302 ( 7 . 9 ) 7 1291 (l.») 3 2r,(p)(r.h) 297 (<^) ^sym Se-Br2 275 ( 5 . 0 ) 23l(dn)(7.4) 230 (0.3) 272 275 Hasyn Se-Br,, 230 (10.0) 222(n)(10.0) 221 (0.7) 0- p ^ sym 0-5e-Br 203 ( 7 . 3 ) 204(dp)(sh) 191 (0.2) '  r>nn yn 0-3e-Br 105 ( 9 . 7 ) 104(p)(3.2) 102 6 Br-Se-Br t (sh) = sh-.uldor [n) = polarized (dp) = depolarized - 59 -symmetric peak at 934 cm"1 i s assigned as the Se=0 stretching mode. Based upon the polarization data, the two frequencies at 286 cm"1 and 281 cm"1 are ascribed to the symmetric and asymmetric stretching vibrations of the SeBr 2 group. Other Se-Br vibrations ^ -1 105,106,107 have been found previously at 290 cm x for SeBr 2, and 260 cm"1 i n Se 2Br 2 The 0 - Se - Br bending vibrations are found at 222 cm"1 and 204 cm""1, corresponding respectively to the symmetric and asymmetric bending modes. The sixth frequency at 104 cm"*1, which i s also symmetric, i s assigned to the Br - Se - Br bending vibration for the molecule. The expected lowering of the Se=0 stretching frequency i n the series 0=SeP2>0=SeCl2 > 0=SeBr2 reflects the decreasing strength and increasing length of the Se=0 bond as less electronegative ligands are attached to Se. In addition, i t must be realized that even i n the molten state, the position of the Se=0 stretching mode shows some association of SeOBr2 molecules, presumably via /Se=0-»>Se=0 linkage. The reported values i n the melt are therefore only partly a reflection of the Se=0 bond strength and partly an association of the molecules. This association i s best i l l u s t r a t e d by the observed trend inU for Se0Br o i n various physical environments J SeO * where the frequencies decrease and the association increases i n the series -solution of SeOBr2> molten SeOBr2 > so l i d SeOBr2. The position of the Se-Br 2 stretching frequencies is not unprecedented, as mentioned earlier; neither i s the fact that the symmetric ^Se-Br 2 m o a e occurs at higher wavenumber than does the - 6*0 -asymmetric one-a similar situation i s encountered for the isostructural thionylhalides. The position and the s p l i t t i n g of the two symmetric stretching vibrations, ^ S e 0 and V s y a se£r 2 * into two doublets i n the crystalline state can be interpreted as being caused by even stronger association of SeOBTg molecules i n the s o l i d state together with possible site symmetry effects. 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 increasing temperature, shown i n Table 5 and Figure 12 reveals a positive temperature coefficient of e l e c t r i c a l conductance, typical for electrolytic dissociation into ions. Such a phenomenon i s consistent with other selenium(lV)oxyhalides and Se0(S0jF) 2 as mentioned previously. B. The Assignment of Vibrational Frequencies for Se0(S0^F) 2 Inclusion of Se0(S0jF) 2 into the group of Se0X2 type compounds i s based upon the following rationale. The fluorosulphate group, -SO^F, together with peroxydisulphuryldifluoride, S 20gF 2, can be regarded as a pseudohalide or pseudohalogen respectively with i t s electronegativity somewhere between F and CI. The SO^F group has been found to be an excellent bidentate bridging group i n a large 96 97 number of t i n and organotin compounds. ' Also i n this f i e l d there are good examples for non-random ligand redistribution of SO^F compounds. w a 3 hoped, therefore, that a greater preferenc for mixed compounds would occur i n reactions between Se0(S0^F) 2 - 61 -TABLE 5 f i c C o n d u c t i v i t y of SeCErv, as s Function of Te*wersture Tender?ture ( JC) S p e c i f i c Conductivit. I C P KFT) (^1--"1-C'TI-1) 46.4 0.905 46.7 1.146 4 7 . 9 1.180 53.6 1.339 54.7 1.415 5 4 . 8 1.420 55.0 1.425 55.2 1.435 53.4 1.439 66.2 1.764 6 6 . 4 1.773 66.6 1.731 6 7 . 7 1.306 6 7 . 3 1.310 7 1 . 1 1.925 71.4 1 . 9 3 3 71.6 1.942 7 2 . 1 1.953 7 2 . 3 1.966 7 5 . 3 2 . 0 6 1 - 62 -3.00-j 2.80 -2.60 -^ 2 4 0 -7 E 2 .20H O 2.00 w 1.60 1.40H 1.20 I.OO o = 3 " O c o U 2.00 4 E ' o —y a M 8 0 -6 0 -4 0 -o 1.20 -1.00 -S e O ( S 0 3 F ) 2 Specific Conductivity of Some Selenium—Oxy Compounds as a Function of Temperature S e O B r . A S e O C L lO 20 —l 1— 30 4 0 ~1 1— 8 0 9 0 IOO 50 60 TO Temperature ( °C) Self ionization = ( S e O X z ^ ^ ^ SeOX +4- S eOX J ) F I G U R E 12 \ - 63 -and other S'eOX2 molecules. Subtle changes i n v o l v i n g the i n t e r n a l SOjF v i b r a t i o n a l f r e q uencies on l i g a n d r e d i s t r i b u t i o n should be r e c o g n i z a b l e i n such a system. The s y n t h e s i s and Raman spectrum o f Se0(S0^F) 2 has a l r e a d y been r e p o r t e d , ^ as mentioned i n s e c t i o n I.B.4., but 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 the 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 spectrum was made t o v e r i f y i t s composition as the b i s f l u o r o s u l p h a t e . One a d d i t i o n a l peak a t 133 cm - 1 was observed 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 . experiments which i s i n c l u d e d i n the f o l l o w i n g Table 6. I t was a l s o decided a t t h i s time to r e i n v e s t i g a t e the v i b r a t i o n a l assignment that had p r e v i o u s l y been t e n t a t i v e l y proposed. 46,47 The frequencies at 1431 cm" 1 and 1220 cm"1 are the asymmetric and symmetric SO^ s t r e t c h i n g v i b r a t i o n s , whereas the 1056 cm" 1 peak i s the S-OSe s t r e t c h , unchanged from the pr e v i o u s assignment. Li k e w i s e i s so f o r those bands a t I U 4 4 cm" 1, which i s a s s i g n e d the Se=0 s t r e t c h i n g mode, and 853 cm" 1, which i s the S-F s t r e t c h i n g mode. The peak a t 638 cm" 1, however, i s re a s s i g n e d as 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 the asymmetric s t r e t c h i n g mode f o r Se-OS i s found at 459 cm" 1. Other v a l u e s that have been assigned t o Se-OX s t r e t c h e s occur a t 57& C Q " 1 ^ or SeO(OCH^) 2 ^ , 646 cm"1 and 584 cm" 1 f o r SeO(OC 2 H ^ ) 2 ^ 8 , and 644 cm" 1 and 577 cm" 1 f o r SeO^CH^XOCgHfj) S i m i l a r values may a l s o be found f o r 99 100 100 H 2Se0j, HSeOjCRj and HSeO^CgR^ , as w e l l as those f o r T A E L S 6 V i b r a t i o n a l Frequencies (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 of peaks i n ( )J frequencies r e f . dep P sh br d e p o l a r i z e d p o l a r i s e d shoulder broad This work 1430 dep (1) 1431 (0.6) 122^ P (6) 1220 (3.6) 10 55 P W 1056 (2.7) 1044 (4) 1044 sh 84P. n (3) 353 (1.2) 639 P ( O 633 (3.4) 533 P (2) 590 (0.7) 5.51 der (2) 551 (0.6) 452 (4) 459 (3.0) 446 ^(4) 443 (3.2) 390 br (].) 403 sh 340 sh (1) 350 sh 31."1 311 265 - a n ) 266 (10.0) kv, (6) 230 (5.6) r.b (2) 177 (0.4) 133 (1.0) Assignment V asym s vm V V V S y syra rock asym wag t w i s t so2 so2 S-OSe Se=0 SF Se-05 SOp S 0 2 Se-OS SF SO Deformation Modes /Cc Na 2Se 20 5, 1 0 1 K 2Se 20 5, 1 0 1 and ( N H ^ S e ^ . 1 0 1 In fact the relatively low value of 459 cm"*1 for SeO(SO^P)2 may be compared to the frequencies of 475 cn""1 and 491 cm"1 (as measured i n the IH and Raman spectra, respectively) for the asymmetric Se-OX stretch i n Ka2Se20^. Only those bands down to ~4°0 cm - 1 may be safely assigned at this time, with the peaks occuring at 590 cm"1, 551 cm"1, 443 cm"1 and 403 cm"1 being described as the S0 2 bending, S0 2 rocking, SF wagging, and SO twisting modes from the SOjF group corresponding to similar assignments that have previously been made for a number of other fluorosulphate , . . , 96,97,102,103,104 containing molecules. ' C. The Existence of SeOXY Molecules i n Ligand Redistribution Reactions The reaction-type to be investigated further i s the ligand redistribution or ligand scrambling reaction. Exemplified by the general equation SeOXg + SeOY 2^ ^ 2SeOXY ( 19) where X and Y = F, CI, Br and SO^F, ligand exchange i s accomplished presumably via four-center intermediates or via 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 for a l l SeOX2 or SeOY2 compounds. It became interesting to see whether exchange does indeed take place and whether this results i n a s t a t i s t i c a l or non-statistical distribution of the three compounds. - 66 -1. SeOBrCl Combination, of SeOCl 2 and SeOBr2 i n a 1.0 : 1.0 molar ratio gives rise to the formation of a red-brown colored l i q u i d , exhibiting o a rather broad melting-point-range of 10.5 - 19.0 C. Solutions with other combinations of the molar ratios of Se0Cl 2 : Se0Br 2 5.0: 1.0 and 1.0: 3.0 showed the same color. Raman spectra were obtained from these three solutions and their frequencies are l i s t e d i n Table 7. Absorption bands due to the two parent compounds SeOCl 2 and SeOBr2 may be distinguished easily i n the mixtures by measuring the intensities of various bands i n the three mole ratios. A clear distinction whether, i n addition to SeOBr2 and SeOCl2, the new species SeOBrCl exists i n the mixture cannot be made by observing any of the rather broad strethcing modes. For instance, the position of v g e Q for SeOCl 2 and l i q u i d SeOBr2 are only different by 10 cm"1 as shown i n Tables 2 and 4. It must be assumed that y for SeOBrCl w i l l also f a l l i n this region. Since the Se=0 stretching modes i n the liquids are a l l found to give rise to broad bands, the identification here i s extremely d i f f i c u l t . The same applies for ^ Seci ^SeBr ^ w e l 1 . Of the bending motions only one type - SeCl 2 and SeBr 2 - are -1 _ i found well enough apart, separated by ~50 cm at 158 cm and 105 cm to be useful. The occurrence of a new band at 135 cm'"1" i n a l l mixtures of SeOCl 2 and SeOBr2 must be caused by the presence of the SeBrCl group. 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"1) f o r SeOClp find SeOBr^ i n Varying Ratios [ r e l a t i v e i n t e n r - i t y of -^eaks i n ( )] SeOCl, l i q u i d 9 4 4 {?./-,) 390 (10.0) 3.50 ( s M 3^0:1 .0 l i q u i d 271 246 1 5 3 (5- '•) ^'7 ( 3 . 0 ) 336 ( 1 0 . 0 ) 3<;< (1.0 ! '• I ( 1 . 5 ) 2 ' 0 '•I.-; (sh) ( 4 . 7 ) (sh) ( 3 . 9 ) ( 2 . 3 ) ( 2 . 3 ) ( 2 . 0 ) SeOCl ?:SeOBr o 1".'0:1.0 ' l i q u i d 943 ( 4 . 3 ) 330 ( 9 . 3 ) 362 (sh) 2 % ( 9 . 6 ) 2 2 2 ( 1 0 . 0 ) 1 6 1 ( 0 . 5 ) 1 3 5 (3.7) 1 0 5 ( 3 . D SeOCloCS^OBr, 1^ 0:3.0 2 S eOBr. l i q u i d s o l i d 936 (2.3) 3 6 5 ( 3 - 2 ) 2*2 ( 3 . 1 ) 2 2 3 ( 1 0 . 0 ) 2 1 1 (sh) 1 6 1 ( 0 . 3 ) 132 ( 2 . 0 ) 1 0 3 ( 4 . 5 ) l.io ivi.H oio ( 5 . 2 ) 394 ( 3 . 9 ) 363 ( 2 . 9 ) 301 (8./-!) 2 9 0 (sh) 2 7 6 ( 7 . 0 ) 23 2 ( 1 0 . 0 ) 2 1 0 ( 7 . 3 ) I 6 3 ( 0 . 2 ) 1 3 3 ( 2 . 5 ) 10 ' , ( 8 . 8 ) s o l i d 934 ( 1 .9) 236 (sh) 2^1 (.?.'•) 222 (10.' 20- ( ' .1 10M ( .2) 0 1 0 ( 2 . 9 ) 3 9 3 ( 2 . 4 ) 302 ( 7 . 9 ) ^ 1 ( 1 . 9 ) Assignment SoO V syin S e C l 0 ^sytn SeBr.'" 7 V svn SeBrp' 2 7 5 (5.0) f 6 syin 0-S<--Cl asyrn SoBr, 6 asyn O-Sn-C 3-30 (10.0) <*> syn 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 sh ; houl d .iy ON - J - 68 -75 According to Yarovenko et al , a product with the stoichiometry SeOBrCl was obtained pure from a reaction yielding not only that product but SeOCl 2 as well. Attempts to obtain SeOBrCl by similar fractional d i s t i l l a t i o n methods under reduced pressure, generated acoording to reaction (19) i n this laboratory failed, however, with considerable decomposition of products. The only analysis of the resulting materials was made by a Raman spectroscopic experiment. In the spectrum were observed a variety of peaks (some perhaps due to Se0 2 and Se^Brg as decomposition products), some of which could be identified as belonging to SeOCl 2 and SeOBrCl. 2. SeOClP A mixed selenium(lV)oxyhalide i s also observed i n a 1.0 : 1.0 reaction mixture of Se0Cl 2 and SeOPg. The frequencies from the Raman spectrum of the colorless l i q u i d products are l i s t e d i n Table 8 along with an assignment of the peaks. In the Se-0 stretching frequency range, peaks for both SeOCl 2 and Se0F 2 can be observed for the redistribution reaction mixture. The same can be said for the SeX2 stretching and the O-Se-X bending frequencies besides the X-Se-X bending modes for SeOPg and SeOCl 2 , too. But again, as for the SeOCl 2 - SeOBr2 reaction mixture, one peak remains unaccounted for i n the reaction of SeOCl 2 and SeOP2 - the one at 220 ca" 1. This peak has been assigned to the Cl-Se-P bending vibration for the SeOClP molecule, occurring neatly between - j -TABL.3' 3 V i b r a t i o n a l ? r ? a u e n c l e s ( c t n "1) f o r S e C C l g ' snd SeOFg i n 1.0 : 1.0 R a t i o [Vs 1st i v e intensity o f -:e?'^ i n ( }] SeOCl. l i q u i d 944 ( 2 . 6 ) 3^0 (10.0) 350 ( s h ) 271 (1.6) 246 ( 1 . 5 ) 15? (5.0) SeOCl,, : SeCF 9 170 ; 1.0"' l i c u i d H 1013 (1.0) 9.54 ( 2 . 3 ) 670 ( b r ) ( 1 . 4 ) 6 2 6 ( s h ) 391 (10.0) 3C5 239 274 254 220 1*0 ( s h ) ( s h ) (2.6) ( 1 . 7 ) (0.2) ( 5 1 ) l i a u i d 1 0 1 2 (s. 3 ) 6'6 ( 1 0 . 0 ) 6 1 0 (3.4) 331 ( 4 . 2 ) 3 2 0 (4.Q) 258 ( s h ) Assignment V S eC V s V S asvn j e - r ? s'.m 3e-Cl sym Q-Se-F V a s y n S e - C l p & a s y a G-Se-F cS s.yn C - S e - C l <S ssv-n O-Ss-Cl ! & Cl - S e-cn b r = bro".d s h = shoul-'er - 70 -the corresponding bending modes of the parent molecules. Additional evidence for the SeOCIF species has been obtained 19 via a F M spectrum of the 1.0 : 1.0 mixture, the chemical s h i f t of which i s given i n Table 9 along with those of other selenium-fluorine containing compounds. Present i n the spectrum are two sets of t r i p l e t s . The one centered at -42.4 ppa has a spin-spin coupling constant value of 846 Hz for J77se_p » and can be identified as being due to SeOFo, which has a J7'(c oe—jj* value of 856 Hz as measured i n the pure state here. In addition 7 T. Birchall et al - 1 have reported a value of 837 Hz for J773e_19;p for Se0?2 from ^Se HHR spectra. The intensity of this f i r s t peak when compared to that of the second is given by the ratio 4:1. Thus i t i s the second set of peaks which may be attributed to SeOCIF. This peak centers at -32.3 ppa and has a J77,, 19 „ be F value of 654 Hz. 3. " SeOBrF," The 1.0 : 1.0 mixture of SeOFg and 3eOBr2 was also investigated. A Raman spectrum of the solution, at roora temperature was taken and the frequencies are l i s t e d i n Table 10. As i s plainly evident from the Table, .all observed peaks may be interpreted i n terms of either SeOF2 or SeOBr2 with no peaks definitely attnoutable to SeOBrP. The poss i b i l i t y that the BrSeP bending mode may be obscured by other deformation modes of SeOBr2 does not permit SeOErF to be ruled out completely, however. It seems, though, that the existence of I A E L 2 9 C'-'STdcsl Shifts for So'ne Selpnium-Fluorine Compounds Compound 3eO(SC~F) ? FSeC(SCy ) ClSeC(30,.F) SoCF0 SOC1F 3~CFo : 3e03r 2: 1.0:1.0 3-?,.(C:)2 3eF5(OF) 3eFcCCF0 SeF^CSeF. F C5?F Chemical Shift (rn-) relative to CFC10 o-v:t 3 ft-? -43.6 (br) -40.3 ! -32.3 -43.1 103 -48 -61 -4? 103 55.7 110 110 -47 -32.2 110 110 -43.6 -43.4 -47.' 42 - p c o co I I C C-<r e o" to co co i 1 I CN) I o o h n 5-cfi- cc i i C O o o c-•H 1/5 . IT. u. tr. tr. cv cv O Ox C • ON O-• O • • U - r-J O-r—' O O CN rH O cr cc cv H ^ o cr. vo O CN O- ON o c ON OJ CM OJ. OJ r-i co c-rH • rH OJ • c • • o- H ^ cr a' PT: O CO • C r-i co c C O CT' •r-i ON ON O r-» rH ON O 0 C O O cr cr cr ifN, o r--NC NC ON N O H N - 3 c c o " cv o o OJ OJ OJ O! H H CN CNJ --T • OJ ^ • O • • O- rH VTN NT U-NNT cr cr cv o c O! CN! OJ I—! t-o • H O! c rH NC O r- 1 O i j N H T N \ C NG ON ON O J of SeOBrP i s not evident from the observed spectrum under these conditions. A U.JR spectrum of the solution was also obtained; however, only a single peak at -43.1 ppm relative to CFCl^ was observed, 19 occurring near the value for pure SeOF2 i n i t s F NMR spectrum as shown i n Table 9 . 4. SeOBrKsC^F) SeOBr and 5e0(S0 ? ) 0 produce a yellow waxy substance when 2 3 £ combined i n a 1.0 : 1.0 molar ratio at room temperature, but upon warming to 100°C the product turns to a li 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 solid sample, even with highest sensitivity, gave resolution of only those peaks at 293 cm"1, 144 cm"1, and 115 cm"1. The results are l i s t e d i n Tables 11 and 12. The peaks at 1415 cm"1 and 1219 ca" 1 can be ascribed to the asymmetric and symmetric S 0 2 stretching modes of the SO^F group, but i t cannot be said for sure to which of S e o C S O ^ F ^ or SeOBr(SOjF) these vibrations result. Another peak at 1185 cm 1 may be interpreted as being one of the vibrational modes of Se0Br(S0jF), but no clear explanation can be given to account for this rather pronounced shoulder. The peak at 1070 cm"1, however, may be assigned to the S-OSe stretch from the SeOBr(SO^F) molecule, which i s analogous to the 1055 cm"1 frequency observed for pure S e O C s o ^ F ^ i n i t s spectrum. The y g modes from Se0(S0^F) 2, SeOBr(SOjF), and SeOBr2 are a l l observed i n the spectrum of the equilibrium mixture and are found at IO46 cm"1, 1028 cm"1, and 935 cm"1 - 74 -TA3L2 11 C o r r e l a t i o n of Selenium-Cxyzen Couinourvis w i t h Numbers [?le?.se use i n reference to Table 12 } Coir~ound Nurr.b* r SeO ( S 0 3 ? ) 2 1 SeOF 2 2 3eCCl2 3 SeOBr 2 SeOF(SO^F) 5 SeCCKSOjF) 6 SeOBr(SC-jF) 7 TABLE 12 Vibrational Frequencies (cm - 1) for Some SeOX(SO-}F) Compounds X = F, CI, Br J SeOFCSC^F) Numbers i n square brackets refer to compounds considered responsible for given frequency of vibration, as per Table 11. Relative intensity of peaks are in parentheses "for each peak. SeOCl(S03F) SeOBr(SC-F) Frequency Intensity Frequency Intensity Frequency Intensity U [51 D-l [5] [5] W [5] [1] [51 W 15] 1425 1226 1072 1041 CU [5] D-] [5] fll [51 CU [5] [2] [5] [1] [51 852 [2] [51 [ll [51 663 639 591 557 435 45=; 443 411 347 305 294 237 215 177 135 (br) (0.3) (4.5) (sh) ( sh) (sh) (sh) (sh) (sh) (sh) (6.2) (1.7) (6.2) (6.0) (0.3) (0.7) (9.1) (2.1) (5.D (10.0) (1.5) (1.0) [11 [61 141-8 [1] [6] 1210 [61 10?7 [1] 1047 [6] 1003 [31 941 [ll [6] 835 [ll 645 [61 619 [11 [63 537 [11 [6] 55" [61 490 [61 423 [ll [6] 411 277 227 211 173 165 (br) (0.8) (M.0) (sh) (sh) (br) (sh) (7.7) (3.5) (1.2) ( 5 . 3 ) (0.7) (0.3) (0.7) (6.2 x 10.0) (sh) (6.1) (sh) (3.3) (10.0) (sh) [7] L?l [ll [ll [71 [1] [71 [4] [1] [71 [ll [71 [1] [7] [1] [7] [71 [ll [71 [ll [71 1415-1 2 1 9 1135 1 0 7 0 1046 1023 9 3 5 3 3 7 304 502 560 4 9 3 420 2-3 222 l nQ 144 (br) (0.9) (".6) (sh) (sh) (sh) (sh) (sh) (3.7) (10.0) (0.4) (1.7) (6.4) (6.4) (<0.1) (2.6) (^.2) (sh) (150-x-10.0) (sh) ( 4 . 3 ) (45 x 1 0 . 0 ) ( 5 0 x 1 0 . 0 ) respectively with the peak at 1028 cm"1 having the greatest intensity. A shoulder at 804 cm"1, found on the main peak at 857 cm"1, can be assigned to the S-F stretching vibration of SeOB^SOjF), found at a lower frequency than the same vibration of SeoCso^ F),,, which accounts for the main peak. Between the two peaks observed at 652 cm"1 and 650 cm"1 must be assigned the Se-OS stretching modes from SeOCSO^F^ and SeOBrCSO^F). Although the occurrence of this mode i n the pure Se0(S0jF) 2 spectrum i s at 639 cm - 1, i t i s generally assumed that this vibration would be of higher energy than the one for SeOBr(SOjF) due to the more electronegative influence of SO^F over Br. Thus the 652 cm"1 vibration has been assigned to ^2e-0X for SeO(SO^F)2 and the one at 630 cm"1 has been assigned to y Se-OX *"or S e 0 ^ r ( S 0 j F ) . Other fluorosulphate modes resulting from either one or both of SeOtSOjF^ and SeOBr(SO-F) are found at 592 cm"1, 560 cm"1, 441 cm"1, and 420 cm"1 and may be described,respectively as the modes for SQQ , 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 intensities may be noticed. For example, the strong 265cm"1 peak from Se0(S0^F) 2 is missing i n the spectrum of the mixture whereas a very strong peak at 293 cm"1 does occur which coincides with a relatively strong band i n this region from Se0Br 2 > Peaks at I44 cm"1 and 115 cm"1 are definitely new to the system and perhaps may be a result of vibrational - 77 -modes of SeOBr(SCuF). Enough evidence can be seen from this, however, to verify the presence .of the mixed compound SeOBr(SO-F). 5. SeOCl(S0 3F) 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 in agreement with previous findings. These frequencies are assigned as follows. Bands at 141S cm - 1 and 1210 cm"1 are i n the region of the asymmetric and symmetric SO^ stretching vibrations from the SO^F group, which are not very different from those i n Se0(S0jF) 2 and may be ascribed to either SeOCl(SO^F) or Se0(S0^F)2. A peak at 1077 cm"1 i s assigned as the asymmetric (A 1) S-OSe stretching mode of SeOCL(SO^F). Se=0 stretching frequencies are observed for each of the parent compounds Se0(S0^F) 2 and SeOCl 2 as well as the mixed chlorofluorosulphate at 1047 cm"1, 941 cm \ and 1008 cm"1 with the f i r s t two of relatively low intensities. The 835 cm"1 absorption band i s mostly li k e l y due to the S-F stretch of SeOCl(SO^F), although the peak is broad: this may be compared with a peak at e48 cm"1 i n the case of Se0(S0^F) 2 for i t s S-F vibration. The Vge-OS *"or SeOCl(SO-F) is assigned as the peak at 619 cm"1, with the shoulders at 645 cm"1 being assigned to V S e_os ^om SeO(SO^F)2 i n keeping with the assignment of this region for SeOBr(SOjF). Other fluorosulphate modes which may be due to either SeOCltSOjF) or Se0(S0jF) 2 can be found at 587 cm"1, 554 cm"1, and 411 ca" 1 corresponding to the S0 2 bending, - 78 -SCv, rocking, and SO twisting modes. The most intense peak i n the spectrum of the equimolar mixture occurs at 428 cm""'*" and unfortunatley clouds one of the SO^F vibrations, namely the S-F wagging mode. This strong peak, however, i s unambigously assigned to ^ se_Q^ for SeOCl(SOjF). This may be compared to the frequencies at 390 cm"1 and 350 cm"1 for SeOCl 2 which have been assigned as the symmetric and asymmetric ^ge_ci modes which incidentally are the most intense peaks i n that spectrum. The other peaks below ^ 400 cm"1 may be treated i n the same manner as for SeOBr(SO^F). A definitely different set of peaks occurs for the mixed chlorofluorosulphate than for the bisfluorosulphate. Again the strong 265 cm"1 peak i s seen i n the spectrum for SeOCl(SO^F). In addition, the vibration at 177 cm"1 for SeOCl(SOjF) i s much more pronounced than the similar one for Se0(S0jF) 2. Even though the assignment for the peaks below ^OOcm"1 cannot be unambigously given, a noted contrast between the Raman spectrum for an equimolar mixture of SeOCl 2 and SeO(SO^P)2 compared to those spectra of the starting materials alone can be seen. In other words, for the Se0Cl 2/Se0(S0jF) 2 system good evidence has been obtained for the existence of SeOClCSO^P) from vibrational data. The ^ F MR spectrum has also been recorded ^  with a resonance being observed at - 4 7 . 7 ppa relative to CFClj external (please see Table 9 ) . This value, characteristic of resonances for fluorine on sulphur i n fluorosulfihates, while differing from the - 4 8 . 6 ppm - 79 -value for Se0(S0^F) 2 i s not significantly different enough to come to a conclusion about the existence of SeOCl(SO^F) on i t s own merit. The fact that i t is different is readily explained i n conjunction with vibrational data, however. 6. SeOFCSO^F) From the reaction mixture of SeOF2 and Se0(S0^F) 2 was obtained a Raman spectrum, the absorption bands of which are l i s t e d i n Table 12. Peaks definitely attributable 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 Se0(S0jF) 2. For example, the peaks at 1425cm" 1 and 1226 cm"1 may be safely ascribed to the asymmetric and symmetric S0 2 stretching modes for the SO^F group, and the shoulder at 1072cm" 1 can be assigned to the S-OSe stretching mode. Furthermore, the peaks at 852 cm"1, 591 cm"1, 557 cm"1, and 4 1 1 cm"1 may similarly be described as various modes of vibration 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 result of the SO^F vibrations from Se0(S0jF) 2 or Se0F(S0jF). The Se=0 stretching frequencies are also very close i n Se0F 2 and SeO(SO^F)2, with values of 1012 cm"1 and IO44 cm"1 respectively, thus preventing a simple determination of SeOFCSO^F) i n this region. In addition, this mode i s usually quite broad. In the 7OO-6OO cm"1 range, - 60 -both Se0(S0-P) 2 and SeOP2 have bands at 650-610 cm which are assigned as the Se-OS. symmetric stretching frequency and the Se-P stretching frequency for 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 for exchange must be drawn from the fact that relative intensities of many absorption bands i n the mixed product and i n the parent compounds do not agree. The spectrum for Se0P(S0^P) cannot be produced by merely superimposing the Raman spectra of SeOPg and Se0(S0j?) 2. It may be noticed that i n the spectrum for Se0P\S0jP) there seems to be a peak missing at 610 cm"1 which might be expected to appear with nearly the same intensity as that for the frequency of 656 cm"1 as i n the case for SeOF2 i f the mixture contained just the two parent compounds in solution with each other. For this normally strong peak to be absent while other weak ones at 591 cm"1 and 557 cm"1 are present indicates that there i s at least some interaction occurring. In addition, the peak at 265 cm"1 i n the spectrum for Se0(S05P)2 i s the most intense of a l l peaks for that compound, but i n the spectrum for the mixture of SeOP2 and Se0(S0^P) 2 there is a remarkable absence of any peak at that frequency. Furthermore, a shoulder at 215 cm"1 upon a main peak at 237 cm"1 i n the l a t t e r spectrum cannnot be adequately explained by comparison to the spectra of either of the two parent compounds. - 81 -A • L"F NMR spectrum of the equimolar s o l u t i o n of SeOF 2 and SeO(SO^F) 2 gives s i n g l e peaks at -43.6 (broad) and -48.4 ppm r e l a t i v e to external CFCl^ (please see Table 9 ) . The l a t t e r i s i n t e r p r e t e d as being due to the f l u o r i n e attached to s u l f u r , where other values f o r seleniumoxy(fluorosulphate)s have been recorded at -48.6 and -47.7 PPQ. The broad resonance at -43.6 ppm i s assigned to the f l u o r i n e on selenium with the broadness being 77 1 9 due to r a p i d exchange and or Se - A ' F hyperfine i n t e r a c t i o n . A s i m i l a r s i t u a t i o n has been previously discussed f o r the mixture 77 7 of SeOF 2 and SeOCl 2 u s i n g Se NMR techniques. The above r e s u l t s seem to i n d i c a t e some exchange and the possible formation of SeOF ( S0 5F). 7. Conclusions I t must be sa i d i n conclusion that the presence of these molecules of type SeOXY has only 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 contrasted to being observed i n a pure i s o l a t e d s t a t e . Observations from s o l u t i o n s of various molar r a t i o s o f reactants as well as the d i s t i l l a t i o n experiment o f SeOBrCl tend toward the conclusion that an 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 ligands, and that i s o l a t i o n of products from t h i s type of r e a c t i o n would not be p o s s i b l e . Indeed, based upon the v i b r a t i o n a l data i n v o l v i n g i n t e n s i t i e s of peaks, one must conclude that a greater amount of i n t e r a c t i o n i s occurring i n some systems than f o r others, and that the mixed compounds can be observed i n what must be c a l l e d an equ i l i b r i u m . A further remark i s due i n respect to the vibrational frequencies found for the SO^F group, i n particular for the stretching frequency region. Even though the SO^F group has 0 been interpreted as being basically monodentate, - 0 - SP 104 0 some assocaition, as noted for example i n BrOSOgF , may well exist. This i s born out by the good correspondence between the vibrational spectra for BrOS02P and Se0(S0^P) 2. In particular for the mixed products, \) g_ 0^ moves to higher frequencies resulting i n a pattern of SO stretching modes reminiscent of 96 97 a bidentate SO^ P. group as found i n some organotin derivatives and which would have the same symmetry (Cs). Since i t seems not very easy to differentiate between these two p o s s i b i l i t i e s , this point has not really been discussed i n any detail, mainly because i t ultimately has no bearing on the problem. D. The Formation of a Salt between KBr and Se0Br 2 As already mentioned i n section I.H., SeOBr2 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, for example, with pyridine. To test the accentor abi l i t y of SeOBr2, efforts 93 93 were made to prepare the bromo analogue of KSeOFj and KSeOCl^ and to investigate i t s vibrational spectrum. The salt KSeOBr^ was prepared by direct addition of an excess of SeOBr2 to KBr, and an analysis showed that i t contained 20.98>o Se and 63.96^ Br, which may be compared to the theoretical values of - 33 -21. 127$ Se and 64.135$ Br for 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 identical melting points of 138°C. 9 5 Farther experiments on KSeOBr^ have shown that when the compound is heated to 60°C in vacuo for 48 hours, there is a loss of a l l Se-0 containing moieties as evidenced i n i t s IR spectrum. Only a white salt, presumed to be KBr remains, the melting point of which was >350°C. A similar breakdown of KSeOBrj was observed when CCl^ was allowed to wash through the salt i n a Sohxlet apparatus overnight. Only a white sal t , with no Se-0 modes i n i t s infrared spectrum, remained after the washing. A Raman spectrum of KSeOBr^ was recorded and the frequencies 93 are tabulated i n Table 13. In the ionic model for SeOXJ the symmetry point group for the ion would be C_ and nine vibrations should be found - a l l Raman and IR active. In the case of KSeOBr^, however, the solid state s p l i t t i n g of one of the vibrations raises to ten the total number of observed Raman peaks. A similar observation had been made for s o l i d SeOBr2. The peak at 934 cm - 1 is assigned to the Se-0 stretching frequency, quite i n keeping with other Se-0 vibrations found i n similar KSeOX^ and Se0X2 molecules. The pair of vibrational frequencies at 297 cm"1 and 292 cm"1 may be interpreted as one of the Se-Br stretching frequencies being s p l i t by the - 34 -TABL3 13 Vibrational Frequencies (cm - 1) for Some KSeOX^ Compounds X = F. CI, 3r ^relative intensity' of re^Vs in ( ) 1 KSeCFo ( solid)' 1 K3sOCl3 (solid)^ KSeC (soli Pr-, dr Assignment 982 949 (10) 93a (1.9) s-=-o 535 373 (7) 297 292 (sh) (sh) V Se-X 513 341 (1) 235 (2.3) V Se-X 434 323 (5) 2 56 (2.0) y 3e-X 450 353 (3) 234 (4.9) "A 430 294 (2) 222 (7.1) 413 231 (2) 20.5 (10.0) V 7 Deformation A ~ e. 2 50 (0) 111 (2.0) \ ,\o es (0) 101 .... .... (1.1) ) shoulder - 85 -crystalline f i e l d . Two other Se-Er stretching vibrations are observed at 285 cm - 1 and 256 cm - 1. The five other vibrations are simply described as the remaining deformation modes for the molecule i n accordance with Paetzold. 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