Homocatenation of metal and metalloid main group elements

Abstract

Interest in poly(diorgano)silanes, catenated silicon compounds and heavier element analogues of alkanes has derived largely from their 1-dimensional delocalisation across the Si-Si σ framework, which affords similar properties observed for polyene and unsaturated "all organic" polymers. Although not so widely recognised or studied, similar "σ-delocalised" activity may also be observed for homocatenated species of other p-block elements. In this study, a foundation for an understanding of the phenomenon of σ-delocalisation is provided through consideration of the structures, methods of synthesis and electronic behaviour of the well-established poly(diorgano)silanes. Synthetic and theoretical developments relating to analogous derivatives based upon silicon's heavier group 14 congeners are then reviewed along with the more limited examples of catenated compounds among the heavier elements of groups 15 and 13. This coverage does not dwell upon detailed aspects of structure or electronic behaviour for the individual compounds and classes of compound included. Rather, the intention is to promote something of a phenomenological awareness of a series of superficially disparate chemical systems and to encourage a more widespread appreciation of the implication that, in not displaying σ-delocalisation, it is the elements of the first full period that display the more unusual or anomalous behaviour. © Springer-Verlag Berlin Heidelberg 2010.