Rings, cages and chains - the rich structural chemistry of the polycations of the chalcogens

The review, with 64 references and 17 figures, reports on the structures of chalcogen polycations and covers the literature since 1988 together with some unpublished work. The structures of the polycations are discussed by the application of basic electron counting rules according to the Zintl concept and are compared with already known cations. A new method of preparation is the chemical vapor transport which leads to novel types of cations and a great increase in the formerly limited number of anions. Recent findings in this held of research are the existence of several isomeric forms of one polycation and the occurrence of polymeric chains as a novel structural feature. (C) 1997 Elsevier Science S.A.