H原子和(CH3)2SiH2抽提反应的理论研究

采用UMP2/6-31G(d)理论水平优化了H原子和(CH3)2SiH2抽提反应势能面上的所有驻点，并在此水平基础上进行了内禀反应坐标(IRC)的计算，得到该反应的反应途径(MEP)。应用变分过渡态理论及最小能量途径半经典绝热基态隧道效应校正(MEPSAG)、小曲率半经典绝热基态隧道效应校正(SCSAG)等方法对上述反应进行了动力学研究，期望从理论上提供一套温度范围较宽、精度较高的动力学数据，为阐明反应机理和解释实验结果提供理论依据。

Theoretical studies on H with (CH3)2SiH2 abstraction reaction

The abstraction of H with (CH3)2SiH2 has been investigated at high levels of ab initio molecual orbital theory. Geometries were optimized at the MP-2 level with 6-31G(d) basis set, and G2MP2 level was used for the final energy calculations. Theoretical analysis provided conclusive evidence that the main process occurring in this reaction is the abstraction of H from the Si-H bond leading to the formation of the H2 and silyl radical; the abstraction of H from C-H bond has higher barrier height and is difficult to react in this reaction. The kinetics of the title reaction has been studied by using the "direct dynamics" method of variational transition-state theory, which is based on the information on geometries, frequencies and energies calculated for ab initio along the minimum energy path. The rate constants of the title reaction were calculated for the range of temperture 298～1 000 K. In the calculation, we considered the tunneling correction. Since the heavy-light-heavy mass-combination is not present in this hydrogen transfer reaction, the tunneling correction was calculated by using the centrifugal-dominant small curvature semiclassical adiabatic ground-state (CD-SCSAG) method. The rate constants calculated match well with the experimental values.