Does silicon prefer to form conjugated bonds with carbon in the C6SiH8+ system?

Quantum chemical calculations based on geometry optimization using density functional theory at the B3LYP/6-31G* level are used to determine the relative stabilities of neutral and cationic C6SiH8 species, namely, the p-silaphenylmethane, phenylsilane and the silacycloheptatriene species. It is found that for the cations, silicon substitution in the phenyl ring leads to increased stability, thereby, causing the p-silaphenylmethane cation to be more stable than the phenylsilane cation by about 11 kcal mol(-1). However, the situation is reversed in the case of the neutrals. The silacycloheptatriene species is the least stable of the three, both in neutral and cationic form.