化学学报 ›› 2006, Vol. 64 ›› Issue (7): 637-646. 上一篇    下一篇

研究论文

气相中CrO2+活化甲烷C—H键的理论研究

王永成*,陈晓霞,耿志远,高立国, 戴国梁,吕玲玲,王冬梅   

  1. (西北师范大学化学化工学院 甘肃省高分子材料重点实验室 兰州 730070)
  • 投稿日期:2005-05-12 修回日期:2005-12-26 发布日期:2006-04-15
  • 通讯作者: 王永成

Theoretical Study of Gas Phase Activation of C—H Bond of Methane by CrO2+

WANG Yong-Cheng*, CHEN Xiao-Xia, GENG Zhi-Yuan, GAO Li-Guo, DAI Guo-Liang, LÜ Ling-Ling, WANG Dong-Mei   

  1. (Gansu Key Laboratory of Polymer Materials, College of Chemistry and Chemical Engineering,
    Northwest Normal University, Lanzhou 730070)
  • Received:2005-05-12 Revised:2005-12-26 Published:2006-04-15
  • Contact: WANG Yong-Cheng

用密度泛函UB3LYP/6-311++G**方法计算研究了气相中CrO2+ (2A1/4A")活化甲烷CH键的微观机理, 找到了四条反应通道. 对其中涉及的两态反应(TSR)进行了分析, 并对影响反应机理和反应速率的势能面交叉现象(potential energy surfaces crossing)进行了详细讨论, 进而运用Hammond假设和Yoshizawa等的内禀坐标单点垂直激发计算的方法找出了一系列势能面交叉点[crossing points (CPs)], 并作了相应的讨论. 进一步用碎片分子轨道理论[fragment molecular orbital (FMO)]对TS1中的轨道相互作用进行了分析, 解释了CrO2+活化甲烷CH键的机理.

关键词: 活化甲烷CH键, 两态反应, 势能面交叉点, 碎片分子轨道理论

The gas phase reaction of oxo-species CrO2+ (2A1/4A") with CH4 was selected as a system of CH bond activation by CrO2+. The reaction mechanism has been investigated with density functional theory at the B3LYP/6-311++G** level. Four reaction path channels have been studied on both the doublet and quartet potential energy surfaces. The geometries for reactants, the transition states and the products were completely optimized. All the transition states were verified by the vibrational analysis and the intrinsic reaction coordinate (IRC) calculations. The potential energy curve-crossing dramatically affecting reaction mechanism and reaction rate has been discussed detailedly. The Hammond postulate and the IRC analyses used by Yoshizawa et al. have been used to locate and character a series of crossing points involving the structures and energy values. In addition, the orbital analysis of CH bond activation has been carried out by fragment molecular orbital.

Key words: activation of CH bond of methane, two-state reactivity, potential energy surfaces crossing point (CP), fragment molecular orbital