Selenium, homopolyatomic cations

Although it had been known since the early 19th century that elemental sulfur, selenium and tellurium dissolve in oleum to afford intensively colored solutions, it was not until the 1960s that the structures of the responsible homopolyatomic cations began to be elucidated in detail. 

Polyheteroatom Cations. So far, only studies on homopolyatomic cations of oxygen, sulfur, selenium, and tellurium have been discussed. Most of them were of the type X,21. There is a new class of polyatomic cations that comprise two or more heteroatoms. 

The preparation and properties of homopolyatomic cations of the Group VI elements have been reviewed recently.1 The general method described below, involving the oxidation of elemental sulfur, selenium, and tellurium with either antimony pentafluoride or arsenic pentafluoride in liquid sulfur dioxide, is convenient for the preparation of compounds containing these polyatomic cations. The procedure is basically that briefly described previously2 for the preparation of Se8(Sb2F j i )2. 

N. Burford, j. Passmore and J. C. P. Sanders, Chap. 2, Preparation, Structure and Energetics of the Homopoly-atomic Cations of Groups 16 and 17, in J. F. Liebman and A. Greenburg (eds.). From Atoms to Polymers Isoelec-tronic Analogies, VCH PubL, Honda, 1989, pp. 53-108. J. Passmore, Chap. 19 Homopolyatomic Selenium Cations... 

Passmore, J., "Homopolyatomic Selenium Cations and Related Halopolyselenium Cations," In The Chemistry of Inorganic Ring Systems Steudel, R., Ed. Elsevier New York, 1992 p 373. 

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