Gas phase reactivity of organosilane radical cations. A FT-ICR study

The bimolecular reactivity of organosilane radical cations (RSiMe3.+) toward selected bases/nucleophiles (N) has been studied in the gas phase by the FT-ICR technique. The two major reaction pathways are H+ and Me3Si+ transfer, whose branching ratio depends on the features of R and N. The onset for Me3Si+ transfer is close to its thermochemical threshold. Deprotonation of ionized benzyltrimethylsilane is unprecedented in solution but is highly efficient in the gas phase when a strong nitrogen base is used, suggesting a potentially useful route to obtain silylated radicals. The kinetic study of a model degenerate reaction suggests that the activation barrier for Me3Si+ transfer between oxygen centers is negligible, as observed for the corresponding proton-transfer process.