NEW POLYATOMIC CATIONS OF SULPHUR. SELENIUN

TELLURIUM AND BISMUTH

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" NEW POLYATOHIC CATIONS OF SULPHUR, SELENIUM,

TELLURIUM AND BISMUTH

BY

WOON CHUNG LUK, B.SC.

A Thesis

Submitted to the Faculty of Graduate Studies

in Partial Fu1fillment of the Requirements

for the Degree/

Doctor of Philosophy

~"'-.

McMaster University

August 1975

© WCON lUK

DOCTOR OF PHILOSOPHY (1975)(Chemistry)

MCMASTER UNIVERSITYHamilton, Ontario.

TITLEs New Polyatomic Cations of Sulphur, Selenium, T~lluriumand Bismuth,

AUTHOR, Waon Chung Luk, B.Sc. (The Chinese University ofHong Kong)

SUPERVISORs Professor R. J. Gillespie

NUMBER OF PAGES, x, 103

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ABSTRACT

A number of new compounds 'containing polyatomic

cations of the chalcogens have been prepared and their

structures investigated. In particular methods for preparing

heteroatomic aations containing two Of the elements in the

same cation have been extensively studed for the first time.

Particular emphasis has been given to the preparation of

crystalline samples suitable for the investigation of stiucture

by x-ray crystallography. In addition some structural studies

\ have been made by Raman spectroscopy.

'The following compounds containing homopolyatomic

cations have been prepared by the reaction of ASFS or SbFS

with th~ appropriate element in solution in 502 and their

structures investigated I S16(AsF6 )2' selO(AsF6 )2' Te6(SbF6)21

and TeAsF6 • By reactions between two different homopolyato~ic

cations or by reactions of a single homopolyatomic cation yi~h

one of the ele~ents su~phur, selenium or tellurium the

fOllow~ng compounds ot nev heteropolyatomic cations were

prepared and their st'ructures studied, Te2sea{AsF6)2.502'

'1'03•75e6. 3 (AsF6 )2' Te25e2,(AsF6 )2' Te353 (ASF6 )2 ~d S2Sea(AsF6 )2·

In a rather limited investigation of the reac~ions'of

bismuth with AsFS and SbFS the following compounds containing

the Bis3+ cation have been prepared and characterized by.,"

Raman s~ctroscopy: BiS(AsF6 )j2S02 and B~5(SbF6)3. A polymeric

compound of composition BiF2.AsP6 vas also prepared'.

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ACKNOWLEDGEMENTS

The author wish to expre~s his gratitude to his

~i~'assistance

Particular thanks are due to Dr. D.R. Slim for help

the x-ray diffraction studies and Mfs. B. Spiers for

research director, Professor R.J. Gillespie, for his aid,

encoura~ment and supervision throughout this YOrk.~

in obtaining Raman spectra. The author also ~ishes to thank

his cOlleagues whose friendship and advice has been appreciated ••

Financial assistance by McMaster university is

gratefully acknowledged. Finally the author would like

to thank Mrs. S.C. Lee for typing this thesis.

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TABLE OF CONTENTS

Page

CHAPTER I INTRODUCTION ••••••••••••••••••••••••••••••••••• 1

( .... 11) HI.s tor1 ca 1. . . . . . . . . . . . . • • . • • . . . . .. t • • • • • • • • • • • • • • • •

(2) Preparation of polyatomic cations •.••.....•.•••••• 7

(3) Structures of polyatomic cations .•••.•..•.•...•••• 8

(4) Purpose of this work .•............•...•••..•.• '••.. 8

CHAPTER I I EXPERIMENTAL ........•......•......... · ...•... 16

(1) Preparation and purification of starting

materials ".. 16

(2) General experimental techniques •.•.•.•••.•••••••• l7

(3) Instrumentation .•.•...•••....•••.••.•••.•••••••.• 21

(4) Analysis , 24

CHAPTER III SELENIUM AND SULPHUR CATIONS .. , .•...•....••• 25

A. Se1eniurn cations ••.••.••• , •••••• , ••• , .•.••••.••••• 25

(1) Introduction•....•.•.•.•.•.•••••.••...••••• 25'l>

(2) Preparation of Se10 (AsF6)2 by oxida'tion

of Se with Se8(}.sF6)2 ••••• ~ •••••••••••••••• 26

(3) Preparation of Se10 (AsF6 )2 by oxidation.of Se with AsFS '" . , •••••.••••.•••••.•••••• 28. -~ .

(4) Att~mpted preparation of se16 (AsF6

)2 by'

oxidation of Se with Ses (AsF6 )2 or AsFS•••• 29

(5) Structure of Se102+••••••.•••.••••••••••.•• 29

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..B. Sulphur -ea tions 30

(l) Introduction •.........••...•.•.••..••...•.•.. 30

(2) preparation of single crystals of

S16 (As F6 ) 2 • • •• • • •J'.······.·.·.. ···.. ··.···3 2

CHAPTER IV TELLURIUH CATIONS........•.....•..............• 34

(1)

(2)

Introduct i on " 34

2+Rama~ spectra of Te4 ••.•••.•.••.•.•.••......••.•• 36

(3) Preparation of TeAsF6 by oxidation of Te

n+with AsF5 and the Raman spectrum of Ten .....•.••• 37

(4) ~man spectra of Te62+ and of Te metal •....•....... 47

(5) Vibrational frequencies of tellurium cations •••..•• SO

CHAPTER V MIXED CATIONS OF SELENI~: AND TELLURIU~ ••••••••• 51

(1) Introduction •••..•.••.•...•••..•••.••...•..•.•••••• 51

(2) Preparation of Te2seS(AsF6)2.S02 by

oxidation of Te with Sea(AsF6)2 •••.•..•..••.•...••• S2

(3) Preparation of Te3.7Se6.3(AsF6)2 by

oxidation'of Se with Te4(AsF6)2 ••...••••.•.•••••••• S5

(4) Preparatio~ Of Te2Se2 (AsF6 )2 by the reaction

of Te4 (AsF6 )2 and Se4 (AsF6 )2 •••••••••••••••..••.••• 56

(5) Preparation of TezSe2 (AsF6

)2 by the reaction

of Te6 (AsF6 )2 a~d Se4 (AsF6 )2 ....... II .... II ........ 57

(6) Structures 59

(7) Reactions of polyatomic cations of selenium

and tellurium ., 65

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PageCHAPTER VI MIXED CATIO:-:S OF SULPHUR AND SELENI UN

AND OF SULPHUR AND TELLURI~~ ••...•....•....••. 67

(1) Introduction 67

(2) Preparation of Se4

SAsF6

by oxidation of

sulphur with SeS (AsF6 )2 ..........................• 68

(3) Attempted preparation of Sand Se mixed

cations by oxidation of Se with S8(AsF6)2 •......... 70

(4) Attempted preparation of Sand S mixed

cation by oxidation of Se 3S5 with ASFS••.....•.••.. 72

(5) Preparation of Te3S3 (AsF6 )2 by the reaction

of Te4 (AsF6 )2 and S8(AsF6)2 73

(6) Other attempted preparation of Sand Te mixed

cations 74

(7) Reactions of polycations of Sand Se, Sand Te .•••• 75

CHAPTER VII BISMUTH CATI~NS •.••......•...•............•.• 77

(1) Introduction•........•••.....••............•......• 77

(2) Reactions of Bi with AsPS in 502 •...•..•.•.•...••• 78

(3) Reactions of Bi with SbFS and PF5 in 5°2 .....•.••.• 88

(4) Reactions of Bi with HS03F and HS03Cl •.••.••••..••• 91

CHAPI'ER VII I CONCWSIONS •...•.•.• (' •.•••.....••......•..•.• 93

REFERENCES •• , 100

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LIST OF TABLES

Table

1. Preparation of compounds containing polyatomi~

Page.'

cations of S, Se, ore and Bi •••••••••••••••••••••••••• 10

2. Structures of polyatomic cations of S, Se, Te

and Bi 13

3. Vibrational frequencies of 2+Te4 • • •.••. • . • • . • . . . . • • •• 38

4. Vibrational frequencies of the Te42+, se42+

2+and 54 ions. . . . . . . .. . . . . . • . . . . . . . • . . . . . • . . . .. . . . . . •• 38

5. Vibrational frequencies of TeAsF6

and TeSbF6 ••••••••• 45

6. X-ray powder diffraction data for TeAsF6 •.••••.•..•• 45

2+7. Vibrational frequencies of Ta6 and Te ••••••••••••• 49

8. Vibrational frequencies of Tellurium, Iodine and their

cation species •\ .••_.~/:~ • • • • • • • • • • • • • • • • • • • • • • • •• 50'----'"

9. Reactions of polycations of Se and Te in 502 ••••••••• 66

10. X-ray powder diffraction data for Se4

SAsF6 • • • • • • • • • • 69

11. Reactions of polycations of S and Se, Sand 'l'e •••••• 76

related compounds ••••••••.••••••..••..•••••••••••••• 90

13. Vibrational frequencies of Bi53+ •••••••••••• :.~ •••••• 92

14. Homopo1yatomic cations of group VI •••••••••••••••••• 93

15. Reactions of polycations of S, Se and Te •••••••••••• 96

16. Mixed cations of S, Se and Te ••••••••••••••••••••••• 98

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..t!Ir'

LIST OF FIGURES

Figure Page

1. Reaction vessels 18

2. Special quartz cell for measurinq a~rption spectra

of samples. in 502 solution.......................... 22

3. Apparatus for measuring Raman spectrum at _196°C•••• 22

4. Suggested structure for se102 t 30

5. possible structures of 5162+ 31.........................

6. Possible structures of Tenn+ 35..... ...................7. Possible structures Of :re

62+ 35.. .. ......................

8. Raman spectrum of a 95% H2

SO4

solution of Te ......... 39

9. Raman spectrum of TeAsF6 at a 44 I....196 C••..•.••••.••...••

10. Raman spectrum of Te6 {AsF6 )2 at 196°C...•.•..•...•.• 48 ,

11. Raman spectrum of Te metal at -196°C ........ .......... 48

12. Raman spectrum of a 5°2 solution of

Te2Se2 (As F6 ) 2 58

13. Projection of the structure Te2sea(AsF6)2.S02

cation .

14a. Structure of Te25ea 2+ ••••••••••••••••••••••••••••••

14b.Bond lengths and bond ang1~s for the Te2sea

2+

15. Bond lengths and bond angles for the

2+Te3 . 7596 .3 cation .

16. Structures of the Te35e72+ and the

Te4Se62+ cations ••.••...•.••.••••••.•••••••.•••.•••

17. Structure of Te2Se22+ •••••••••••••••...•.•••.••••..•

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• • • .. .. .. • • • • • • • • • • • • • • • • t • • • • • • • • • • • • • • • • • • •dovn[100]

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Figure

LIST OF FIGURES

Page

2+18. Structure of Te3s 3 •••••••••••••••••••••••••••••• 74

19. Reflectance spectra of Bi S(AICl4 )3 (dash line)

and of the yellow compound obtained from the

reaction betwe~en Bi and AsF5••....•..."~ . • . • • . . . • . . •• 81

20. Raman spectrum of DiS (ASF6 )3. 2502 0 84at -196 C •.••.•••

-21. 19F ~~ spectrum of a solution of ( BiF2)m(AsF6 )m

, in liquid S02 at different temperature ............. 86

22. Raman spectra of (BiF2 )n{AsF6 )n and of . 89Bl F3 • • • • • ••• •

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CHAPTER I

Introduction

. ~ ..

(l) Historical

During recent years a number of homopolyatomic

cations (l).X+ where x,y) have "been- prepared and characterized(l).

These cations are important in terms of their bon~ing and

~~stereochemiBtry and constitute a novel class of compounds

of intrinsic interest. Homonuclear aggregates of atoms are

"well known among transitional metals in "cluster" compounds,

h I 4+ d' h i h 2-suc a$ M06 e 8 ' an 1n the boron ydr des suc as Bl2Hl 2 •

The description of the bonding in these compounds is somewhat

complicated by the presence of the ligands. Therefore the

structures of the homopolyatomic cations are of obvious

interest particularly because of their simplicity in that

they contain only one kind ot atoms.

The most important and widely studied of these

species are the homopolyatomic cations of S, Se, Te r;:d to

a lesser extent ai.

SUlphur PolyatoDlic cations

The history of sulphur polyatomic cations can bo

traced back to 1804 when Bucholz (2) discovered that sulphur

reacts with oleum to give brown, greenish blue and blue,.; sOlutipns. Then in 1812, Vogel (3) "was able to isolate a

deep blue liquid, a bluish-green solid, and a brown liquid

which he considered to be definite compounds. Since then

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a number of chemists have investigated these oleum solutions.

with particular attention being given to the blue compound.

The species responsible for the blue color has been identified;

by various workers as 52°3(4), 52 (5), the radical ion

+(X25 - 5X2 ) (6),'and a species designated 5x (7) •.

The nature of solutions of sulphur in oleum was finally~, .

elucidated by Gillespie and his coworkers. The various colors

produced by sUlphur in hleum have been shown to be due to the

cations S16 2+, 582+ and 54

2+ (a-lO). Solid compounds containing\

these cations can be conveniently prepared by the oxidation

of sulphur with arsenic or antimony pentafluorides. The red

compounds S16(AsF6 )2 and 5l6 (SbF6 )2' the deep blue compounds

Sa(AsF6 )2 and Sa{Sb2F1l )2 and the pale yellow compound

S4(SbF6 )2 have all been prepared in this way (a,ll). The

structure of Sa(AsF6 )2 has been determined by x-ray crystallo­

graphy (10). Oxidation of sulphur by S206F2 in fluorosulphuric

acid at ooc (a) also produced red and blue solutions in which the

presence of 5162+ 'nd Sa 2+ were established by spectroscopic.

- .conductometric and cryoscopic measurements. The pale yellow

~

compound S4(S03F)2 has been prepared by carefully-reacting

S206F2 with elemental sulphur inS02 at low temperature.

The reaction of sulphur with sulphuric acid and ole~

has been studied by ultraviolet spectroscopy (12). In 95-100%

H2S04 SUlphur forms a colloidal solution, but afte~ 12 hours

at 7So the element dissolves as 58 molecules. In 5% oleum

oxidation is observed and 5162+ is formed. Increase in S03

••

II~

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, "S 2+ d S 2+concentrat~on causes further ox~datlon to 8 an to 4

in ole~ having more than 15% S03' None of these solutions

is completely stable, and 'oxidation continues slowly to give

S02 as the final product. The presence of the radical ions

S4 + and S8 + had been established in the oleum solutions by ,/

ESR studies (12)0(

Selenium Polyatomic Cations

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In 1827, Magnus reported that fuming sUlphuric acid

dissolved selenium to yield a green solution (13), which

deposits selenium when poured into water. Observing the

evolution of S02 in the same reaction, Fisher (14) in 1828

first pointed out that selenium must have been oxidized.

Then Weber (15) obtained a green compound ,by reacting selenium

with S03 and he formulated this as SeS03 in the same way as

~ he f~rmu1ated the blue and red compounds obtained from the

reactions of Sand Te with S03 as S203 and TeS03 respectively.

Divers and Shimose (16) agreed with Weber's finding and further

observed that on heating the gree~ SeS0 3 a bright yellow

amorphous mass is obtained which they considered to be an

allotropic 'form Of the green compound. Since then various

~esults (17) were reported on these species providing a

substantial amount of data but 1ittl~ understanding of the

system. Recently it has been shown that these compounds

actually contain the yellow se4 2+ and green se82+ polyatomic

cations (18).

The discovery of the nature of these species was due

4

to Ehe studies of solutions of ~eleniurn in highly acidic

media by Gillespie and his coworkers (IS). In fluorosulphuric

acid elemental selenium can be dissolved to form a greent

solution. In the presence of SZ06F2' selenium has been shown

to give green, yellow and finally colorless solutions as the

quantity of S206F2 is increased. The formation of se42+ and

SeS 2+ in these solutions was established by cryoscopic,

conductometric and spectroscopic measurements. since then

a number of solid compounds containing se4 2+ and seS 2+ have

been prepared by oxidizing selenium with sulphur trioxide,

oleum, disulphuric acid, Sbfs and AsFS (19,20,2l). The

presence of the cations was confirmed by comparison of the

Raman spectra of the solid and the absorption spectra of

their sOlutions in oleum or HS03F with those obtained

previously for solutions of se42+ and ses2+ in these solvents.

From phase diagram studies on the systems Se-(SeC~4Aic13)'

the compounds Se4(AIC14)2 and SeS (AlCI4 )2 have been identified,

and the crystal structure of the latter compound has been

reported (2Z).

Tellurium Polyatomic cations

The red color produced when tellurium dissolves in

concentrated sUlphuri~ acid was ~irst~ed as long ago

as 1798 (23), but the origin of this color has re~ained a

mystery unti~~ecentlY. Bjerrum and Smith (24) and Bjerrum

(25) have stdJied the reaction of tellurium tetrachloride

with tellurium in molten AICl3-NaCl. A purple melt was formed,

.,,'.,~{t