Rate Constants and Energetics of the H 2 SiO + H Reaction System: RP ‐ VTST / MT and VRC Calculations

ABSTRACT Silaformaldehyde (H 2 SiO) is one of the components of the kinetics roadmap of silane oxidation. For this species, kinetics decomposition is related to three elementary reactions, that is, H + H 2 SiO → H 2  + HSiO (R1), H + H 2 SiO → H 2 SiOH (R2), and H + H 2 SiO → H 3 SiO (R3). To improve the kinetics of these reaction systems, accurate energetics were computed with the ωB97X‐D and CCSD(T) methods, and the rate constants were determined using CVT methods with multidimensional tunneling. KIEs were also determined for (R1), which is an important path at high temperatures. At the ωB97X‐D/aug‐cc‐pVTZ level, the value of electronic barrier height is 4.5, 5.2, and 0.4 kcal mol −1 for (R1), (R2), and (R3), respectively. In addition to the characterization of the elementary reactions, a mechanism consisting of all interconnected reactions was characterized by using the energy‐grained master equation approach to determine the phenomenological rate constants for the formation of products and the time evolution of the species. Up to 500 K, the main reaction product is H 2 SiOH, while the bimolecular products H 2  + HSiO dominate at higher temperatures.