A Theoretical Study of Mechanisms of Silylene Insertion into Si-H and Si-Cl Bonds

Abstract

A systematic DFT study of the substituent effects on the transition structures and energies of the insertions of a silylene into Si-X bonds of YZ₂Si-X (X = H, Cl) via three-membered cyclic transition states has disclosed important electronic and steric factors to determine the rates and selectivity. The migrating atom X affects not only n(Si)-sigma*(Si-X), ppai(Si)-sigma(Si-X), and ppai(Si)-n(X) interactions but also the geometry of the three-membered ring TSs, and in turn, the steric effects between the silylene and the secondary substituents Z. Electronegative Y located in the same plane with the three-membered ring accelerates the insertions through the n(Si)-sigma*(Si-Y) interaction, while the extent depends on X and Z.