Preparation and Reactions of Polysilanyl Anions and Dianions

The author's rather accidental discovery of the synthesis of [tris(trimethylsilyl)silyl]potassium by reaction of tetrakis(trimethylsilyl)silane with potassium tert -butoxide in 1996 was the starting point for the continuation of some chemistry reported by earlier workers which had been mostly dormant for almost 30 years. The reaction of polysilanes with potassium alkoxides was found to be superior to analogous chemistry using methyllithium. The high selectivity for the cleavage of peripheral trimethylsilyl groups allowed not only the preparation of higher polysilanyl anions but also of dianions. The latter are especially useful for the synthesis of cyclic and also bicyclic polysilanes, including heterocyclic compounds. The incorporation of heteroatoms into the starting materials gave silyl anions with ambiphilic character. (Polysilanyl)potassium compounds were used to prepare a number of transition-metal compounds, including the first example of an early-transition-metal disilene complex. Recent studies have shown that the method of anion formation via the reaction of silylated precursors with potassium tert -butoxide works equally well with carbon, germanium, and tin compounds.