Pontes Marcelo André Petry, de Carvalho Edson Firmino Viana, Ferrão Luiz Fernando de Araujo, Machado Francisco Bolivar Correto, Roberto-Neto Orlando
Departamento de Química, Instituto Tecnológico da Aeronáutica, São José dos Campos, São Paulo, Brazil.
Laboratório de Computação Científica Avançada e Modelamento (Lab - CCAM), Instituto Tecnológico da Aeronáutica, São José dos Campos, São Paulo, Brazil.
J Comput Chem. 2025 May 30;46(14):e70115. doi: 10.1002/jcc.70115.
Silaformaldehyde (HSiO) 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 + HSiO → H + HSiO (R1), H + HSiO → HSiOH (R2), and H + HSiO → HSiO (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 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 HSiOH, while the bimolecular products H + HSiO dominate at higher temperatures.
硅甲醛（HSiO）是硅烷氧化动力学路径的组成部分之一。对于该物种，动力学分解与三个基元反应有关，即H + HSiO → H + HSiO（R1）、H + HSiO → HSiOH（R2）和H + HSiO → HSiO（R3）。为了改进这些反应体系的动力学，采用ωB97X-D和CCSD(T)方法计算了精确的能量，并使用具有多维隧穿的变分过渡态理论（CVT）方法确定了速率常数。还确定了高温下重要路径（R1）的动力学同位素效应（KIEs）。在ωB97X-D/aug-cc-pVTZ水平下，（R1）、（R2）和（R3）的电子势垒高度值分别为4.5、5.2和0.4 kcal mol⁻¹。除了对基元反应进行表征外，还使用能量粒度主方程方法对由所有相互关联反应组成的机理进行了表征，以确定产物形成的唯象速率常数和物种的时间演化。在高达500 K的温度下，主要反应产物是HSiOH，但在较高温度下双分子产物H + HSiO占主导。
