title: Theoretical Study of Silicon Monoxide Reactions with Ammonia and Methane.
abstract: High-accuracy calculations were performed to study the mechanisms of the reactions between the diatomic silicon monoxide (SiO) with NH3and CH4. These reactions are relevant to the SiO-related astrochemistry and atmospheric chemistry as well as the activation of the N-H and C-H bonds by the SiO triple bond. Energetic data used in the construction of potential energy surfaces describing the SiO + NH3/CH4reactions were obtained at the coupled-cluster theory with extrapolation to the complete basis set limit (CCSD(T)/CBS) using DFT/B3LYP/aug-cc-pVTZ optimized geometries. Standard heats of formation of a series of small Si-molecules were predicted. Insertion of SiO into the N-H bond is exothermic with a small energy barrier of ∼8 kcal/mol with respect to the SiO + NH3reactants, whereas the C-H bond activation by SiO involves a higher energy barrier of 45 kcal/mol. Eight product channels are opened in the SiO + NH3reaction including dehydrations giving HNSi/HSiN and dehydrogenations. These reactions are endothermic by 16-119 kcal/mol (calculated at 298.15 K) with the CCSD(T)/CBS energy barriers of 21-128 kcal/mol. The most stable set of products, HNSi + H2O, was also the product of the reaction pathway having lowest energy barrier of 21 kcal/mol. Ten product channels of the SiO + CH4reaction including decarbonylation, dehydration, dehydrogenation, and formation of Si + CH3OH are endothermic by 19-118 kcal/mol with the energy barriers in the range of 71-126 kcal/mol. The formation of H2CSiO + H2O has the lowest energy barrier of 71 kcal/mol, whereas the most stable set of products, SiH4+ CO, is formed via a higher energy barrier of 90 kcal/mol. Accordingly, while SiO can break the N-H bond of ammonia without the assistance of other molecules, it is not able to break the C-H bond of methane.
authors.affiliation: Computational Chemistry Research Group, Ton Duc Thang University , Ho Chi Minh City, 778000 Vietnam.|Faculty of Applied Sciences, Ton Duc Thang University , Ho Chi Minh City, 778000 Vietnam.
authors.forename: Huyen Thi
authors.initials: HT
authors.lastname: Nguyen
authors.affiliation: Department of Chemistry, KU Leuven , Celestijnenlaan 200F, B-3001 Leuven, Belgium.
authors.forename: Tran Dieu
authors.initials: TD
authors.lastname: Hang
authors.affiliation: Computational Chemistry Research Group, Ton Duc Thang University , Ho Chi Minh City, 778000 Vietnam.|Faculty of Applied Sciences, Ton Duc Thang University , Ho Chi Minh City, 778000 Vietnam.|Department of Chemistry, KU Leuven , Celestijnenlaan 200F, B-3001 Leuven, Belgium.
authors.forename: Minh Tho
authors.identifier: http://orcid.org/0000-0002-3803-0569
authors.initials: MT
authors.lastname: Nguyen