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本文用RHF/6-31G~(?)解析梯度方法研究了单重态硅烯与甲醛环加成反应的机理,用二级微扰方法对各构型的能量进行了相关能校正,并用统计热力学方法和过渡态理论计算了该反应在不同温度下的热力学函数的变化和动力学性质.结果表明,此反应历程由两步组成:1)硅烯与甲醛生成—中间配合物,是一无势垒的放热反应,2)中间配合物异构化为产物,此步势垒经零点能校正后只有51.4kJ·mol~(-1)(MP2/6-31G~(?)∥6-31G~(?));从热力学和动力学的综合角度考虑,该反应在300～400K温度下进行为宜,如此,反应既有较大的自发趋势和平衡常数,又具有较快的反应速率.
In this paper, the mechanism of the cycloaddition reaction of monomeric silylene with formaldehyde was studied by RHF / 6-31G ~ (?) Analytic gradient method. Correlation energy of each configuration was corrected by two-step perturbation method. Thermodynamic method and transition state theory were used to calculate the thermodynamic function and kinetics of the reaction at different temperatures.The results showed that the reaction process consisted of two steps: 1) the formation of intermediate complexes between silylene and formaldehyde, The exothermic reaction of the barrier, 2) the isomerization of the intermediate complex into a product, and the potential barrier is only 51.4 kJ · mol -1 (MP2 / 6-31G ~ (?) ∥6- 31G ~ (?)). From the perspective of thermodynamics and kinetics, the reaction is preferably carried out at a temperature of 300-400K. Thus, the reaction has a larger spontaneous tendency and equilibrium constant and a faster reaction rate .