SULPHUR, SELENIUM, AND TELLURIUM

We describe in this chapter the structural chemistry of sulphur, selenium, and tellurium, excluding certain groups of compounds which are discussed elsewhere. Metal oxysulphides and sulphides (simple and complex) are described in Chapter 17, sulphides of non-metals are included with the structural chemistry of the appropriate element, and alkali-metal hydrosulphides are grouped with hydroxides in Chapter 14. 

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The elements, sulphur, selenium and tellurium form both di- and tri-oxides. The dioxides reflect the increasing metallic character of... 

Oxygen halides are dealt with in Chapter 11, p. 334. Sulphur, selenium and tellurium form many halides, and only a brief introduction to the subject is given here. 

Since tire alkali and alkaline metals have such a high affinity for oxygen, sulphur aird selenium they are potentially useful for the removal of these iron-metallic elements from liquid metals with a lower affinity for these elements. Since the hairdling of these Group I and II elements is hazardous on the industrial scale, their production by molten salt electrolysis during metal rehning is an attractive alternative. Ward and Hoar (1961) obtained almost complete removal of sulphur, selenium and tellurium from liquid copper by the electrolysis of molten BaCla between tire metal which functioned as the cathode, and a graphite anode. 

The stereodynamics of metal complexes of sulphur, selenium and tellurium containing ligands. E. W. Abel, S. K. Bhargava and K. G. Orrell, Prog. Inorg. Chem., 1984, 32,1 (250). 

The stereodynamics of metal complexes of sulphur-, selenium- and tellurium-containing ligands14,15... 

Sulphur, selenium and tellurium can be incorporated into Si in a variety of forms (Grimmeiss et al., 1981 Wagner et al., 1984). As isolated ions, they are all double donors, with levels around 260 and 550 meV from the conduction band. These impurities may also be introduced as pairs, which also act as a double donors (Pensl et al., 1986). Depending on the thermal history of the Si during diffusion of S, Se and Te, they may also be incorporated as higher-order impurity complexes (Grimmeiss et al., 1981 Wagner et al., 1984). 

Chemical Combinatioii of Hydrogen with Sulphur Selenium, and Tellurium. 

Sulphur, Selenium, and Tellurium Compounds.—The crystal structure of the metal-rich zirconium sulphide Zr Sj has been determined and each sulphur atom shown to be at the centre of a square antiprism of zirconium atoms. The reaction of ZrS2 with potassium in liquid ammonia has been shown to give four K ZrS2 phases (.x = 1, 0.86, 0.71, or 0.71—0.22) which differ in the nature of the co-ordination sites occupied by the potassium atoms between the ZrS2 layers. ZrCl reacts with NaS2P(OEt)2 in toluene to form [Zr S2P-(OEt)2 4], which appears to involve a trigonal-dodecahedral arrangement of sulphur atoms about the metal. ... 

The sulphur, selenium and tellurium nucleophiles required for these SrnI reactions can be generated in a preliminary step by reduction of a sacrificial cathode of graphite mixed with elemental sulphur, selenium or tellurium [160,162]. 

D. H. Reid, ed., Organic Compounds of Sulphur. Selenium, and Tellurium, Spec. Period. Rep. Chem. Soc., London. 

From what has just been said with regard to carbon, it is evident that the atomicity of an element is, apparently at least, not a fixed and invariable quantity thus nitrogen is sometimes equivalent to five atoms of hydrogen, as in ammonic chloride, (i H Cl), sometimes to three atoms, as in ammonia (N" H,), mid sometimes to only one atom, as in nitrous oxide (N,0). But it is found that this variation in atomicity always takes place by the disappearance or development of an even number of bonds thus nitrogen is either a pentad, a triad, or a monad phosphorus and arsenic, either pentads or triads carbon and tin, either tetrads or dyads and sulphur, selenium, and tellurium, either hexads, tetrads, or dyads. 

Solid sulphur, selenium, and tellurium inflame in fluorine gas at ordinary temp. sulphur burns to the hexafluoride, SF6. The reactivity of sulphur or selenium with fluorine persists at —187°, but tellurium is without action at this temp. Hydrogen sulphide and sulphur dioxide also burn in the gas—the former produces hydrogen fluoride and sulphur fluoride. Each bubble of sulphur dioxide led into a jar of fluorine produces an explosion and thionyl fluoride, S0F2, is formed but if the fluorine be led into the sulphur dioxide, there is no action until the sulphur dioxide has reached a certain partial pressure when all explodes. If the fluorine be led into an atm. of sulphur dioxide at the temp, of the reaction, sulphuryl fluoride, S02F2, is formed quietly without violence. Sulphuric acid is scarcely affected by fluorine. 

R. J. S. Beer, "Organic Compounds of Sulphur, Selenium and Tellurium (Sr. Reporter,... 

Sulphur, selenium and tellurium exhibit allotropy, and in certain of their crystalline forms the elements are isomorphous. As would be expected from the increased positive character of tellurium, the allotropy of this element is less well defined. In the liquid condition the elements arc miscible with one another and yield mixed crystals the ternary system, S— Sc—Tc, exhibits neither the formation of compounds nor ternary eutectics, but contains two zones of complete miscibility in which there exist mixed crystals of selenium and tellurium with sulphur, and of sulphur and tellurium with selenium.2... 

The hydrides of sulphur, selenium and tellurium, which arc gaseous at ordinary temperatures, may be liquefied and solidified with comparative case. The boiling- and melting-points rise with increasing molecular weight ... 

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