H_2CCF自由基与HNCO反应机理的理论研究

Theoretical Study on the Reaction Mechanism of H_2CCF Radical and HNCO

采用密度泛函理论的B3LYP方法,在6-311++G(d,p)基组水平上研究了H_2CCF自由基与HNCO的微观反应机理,优化了反应过程中的反应物、中间体、过渡态和产物,为了获得更精确的能量信息,还在QCISD(T)/6-311++G(d,p)基组水平上计算了各物质的能量.振动分析结果和IRC分析结果证实了中间体和过渡态的真实性,计算所得的成键临界点电荷密度的变化也确认了反应过程.对于H_2CCF自由基与HNCO反应,我们找到了六条可行的反应通道,结果分析表明通道H_2CCF+HNCO→IM3→TS5→H_2CCFH+NCO控制步骤活化能最低,是该反应的主要通道,在此反应过程中有稳定的氢键复合物IM3生成,还表现出氢原子迁移的反应特征.

The reaction mechanism of H2CCF radical with HNCO has been investigated by B3LYP method with 6-311 q＋＋G（d,p） basis set. The geometries and harmonic frequencies of reactants, intermediates, transition states and products have been calculated at the B3LYP/6-311 ＋ ＋G（d,p） level. To get more precise energy information, the energies of stationary points along the pathways were also calculated at QCISD（T）/6-311 q＋＋G（d,p） level. Intermediates and transition states were confu＇med by the results of vibration analysis and the IRC calculation. At the same time, the results of charge density at some bonding critical points confirmed the processes of the reaction. Six feasible reaction pathways were investigated in this study. Analysis indicated that the reaction H2CCF＋HNCO→IM3→TS5→H2CCFH＋NCO was the main pathway, the activation energy of which was the lowest. In this pathway, there were a hydrogen-bond complex IM3 and a characteristic hydrogen shift.