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化学学报
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化学学报 ›› 2007, Vol. 65 ›› Issue (24): 2839-2846. 上一篇    下一篇

研究论文

SiH2自由基与HNCO反应机理的理论研究

耿志远*, 韩彦霞, 王永成, 梁俊玺, 闫盆吉, 姚琨, 贾宝丽   

  1. (西北师范大学化学化工学院 甘肃省高分子重点实验室 兰州 730070)
  • 投稿日期:2007-01-21 修回日期:2007-06-21 发布日期:2007-12-28
  • 通讯作者: 耿志远

Theoretical Study of the Reaction Mechanism for SiH2 Radical with HNCO

GENG Zhi-Yuan*; HAN Yan-Xia; WANG Yong-Cheng; LIANG Jun-Xi; YAN Pen-Ji; YAO Kun; JIA Bao-Li   

  1. (Gansu Key Laboratory of Polymer Materials, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070)
  • Received:2007-01-21 Revised:2007-06-21 Published:2007-12-28
  • Contact: GENG Zhi-Yuan

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采用密度泛函理论B3LYP方法研究了SiH2自由基与HNCO的反应机理, 并在B3LYP/6-311＋＋G**水平上对反应物、中间体、过渡态进行了全几何参数优化, 通过频率分析和内禀反应坐标(IRC)确定了中间体和过渡态. 为了得到更精确的能量值, 又用QCISD(T)/6-311＋＋G**方法计算了在B3LYP/6-311＋＋G**水平优化后的各个驻点的相对能量. 计算结果表明SiH2自由基与HNCO的反应有五条反应通道, 其中顺式反应通道SiH2＋HNCO→IM3→ TS4→IM5→TS5→IM6→SiH2NH＋CO反应能垒最低, 为主反应通道.

关键词: SiH2自由基, HNCO, 反应机理, 活化能, 过渡态

The reaction mechanism of SiH2 radical with HNCO has been investigated by a B3LYP method of density functional theory, while the geometries and harmonic vibration frequencies of reactants, intermediates, transition states and products have been calculated at the B3LYP/6-311＋＋G** level. To obtain more precise energy result, stationary point energies were calculated at a QCISD (T)/6-311＋＋G**// B3LYP/6-311＋＋G** level. The intermediates and transition states were confirmed by the results of vibrational analysis and the Intrinsic Reaction Coordinates (IRC) calculation. The results indicate that the reaction of SiH2 radical with HNCO has five channels, among which the reaction SiH2＋HNCO→IM3→ TS4→IM5→TS5→IM6→SiH2NH＋CO was the main pathway with the lowest activation energy.

Key words: silylene radical, isothiocyanic acid, reaction mechanism, activation energy, transition state