H原子和(CH_3)_2SiH_2抽提反应的理论研究  

Theoretical Studies on H with (CH_3)_2SiH_2 Abstraction Reaction

作　　者：张庆竹[1] 王少坤[1] 刘传朴[1] 张吉果[1] 王明刚[1] 顾月姝[1] 

机构地区：[1]山东大学化学学院,济南250100

出　　处：《化学学报》2001年第2期189-194,共6页Acta Chimica Sinica

基　　金：高等学校博士学科点专项科研基金资助课题

摘　　要：采用UMP2 / 6- 3 1G(d)理论水平优化了H原子和 (CH3) 2 SiH2 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 。The abstraction of H with (CH3)(2)SiH2 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 H-2 and silyl radical; the abstraction of ii 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 similar to 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.

关 键 词：反应通道 变分过渡态 隧道效应 速率常数 二甲基硅烷 氢原子 抽提反应 反应动力学 

分 类 号：O621.25[理学—有机化学]