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

Authors:

• Marco Ballestri,
• Chryssostomos Chatgilialoglu,
• Maurizio Guerra,
• Andrea Guerrini,
• Marco Lucarini,
• Giancarlo Seconi

Abstract

Me ₃SiSi(H)Me ₂, Me ₃SiSiMe ₂Si(H)Me ₂, and (Me ₃Si) ₃SiSi(H) Me ₂ 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 initio MO studies, at different levels of theory, which predict the Si-H bond dissociation energies of PhSiH ₃, Ph ₂SiH ₂, and XSiH ₂SiH ₂-H, where X = H, Me and SiH ₃. The radical trapping abilities of these silanes and other common radical-based reducing agents are compared.