No abstract

No abstract

Density functional theory (DFT) was used to explore the different mechanistic possibilities for the hydrosilylation reaction between methyldimethoxysilane and methylvinyldimethoxysilane catalyzed by the Ru(II) complex dicarbonyldichlorobis(triphenylphosphine)ruthenium(II) (A1). Reaction enthalpy profiles of the Chalk-Harrod, modified Chalk-Harrod, and σ-bond metathesis mechanisms were computed for several different active forms of A1. A total of 10 different pathways with different catalytic cycles and different induction steps were compared. We predict that a σ-bond metathesis mechanism involving the formation of a hydride analogue of A1 is most favored, in contrast to the commonly accepted Chalk-Harrod mechanism of hydrosilylation. The B3LYP-calculated activation energy within the catalytic cycle (∆H act ) 21.8 kcal/mol) is small enough to make A1 a reasonable catalyst for this reaction under the normally applied experimental conditions.

No abstract