Reactions of trisilaallene and 2-germadisilaallene with various reagents

A number of the distinctive reactions of trisilaallene 1 and 2-germadisilaallene 4 with various reagents including water, alcohols, acetone, and haloalkanes were studied. The addition reactions of 1 to water and alcohols occur in a regiospecific manner to afford 1,3-dioxytrisilanes in high yields. The additions are explained by a stepwise mechanism involving the initial nucleophilic attack of a hydroxy oxygen to a terminal allenic silicon to give an intermediate unsymmetric disilene. The regiospecificity is rationalized by the shape of the frontier molecular orbitals and the NPA charge distribution of trisilaallene 1 and the intermediate disilene.