Organosilanes as radical-based reducing agents with low hydrogen donating abilities

Abstract

Me₃SiSi(H)Me₂, Me₃SiSiMe₂Si(H)Me₂, and (Me₃Si)₃SiSi(H)Me₂ have been used as radical-based reducing agents for a variety of organic substrates. Rate constants for the reaction of primary alkyl radicals with these silanes have been measured over a range of temperature by using the neophyl rearrangement as a radical clock. Some kinetic data have also been obtained for phenyl substituted silanes. The experimental findings are complemented by ab initioMO studies, at different levels of theory, which predict the Si–H bond dissociation energies of PhSiH₃, Ph₂SiH₂, and XSiH₂SiH₂–H, where X = H, Me and SiH₃. The radical trapping abilities of these silanes and other common radical-based reducing agents are compared.