物理化学学报 >> 2010, Vol. 26 >> Issue (02): 441-446.doi: 10.3866/PKU.WHXB20100218

量子化学及计算化学 上一篇    下一篇

气相中W+活化CO2分解的自旋禁阻反应机理

刘玲玲, 王永成   

  1. 兰州城市学院化学与环境科学学院, 兰州 730070; 西北师范大学化学化工学院, 兰州 730070
  • 收稿日期:2009-08-05 修回日期:2009-11-25 发布日期:2010-01-26
  • 通讯作者: 王永成 E-mail:wangyc@nwnu.edu.cn

Spin-Forbidden Reaction Mechanism of CO2 Cleavage Activated by W+ in Gas Phase

LIU Ling-Ling, WANG Yong-Cheng   

  1. College of Chemistry and Environment Science, Lanzhou City University, Lanzhou 730070, P. R. China; College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070, P. R. China
  • Received:2009-08-05 Revised:2009-11-25 Published:2010-01-26
  • Contact: WANG Yong-Cheng E-mail:wangyc@nwnu.edu.cn

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摘要：

用密度泛函理论中的UB3LYP方法, 对W采用相对论校正赝势基组(SDD), 对C、O采用6-311+G(3d)基组, 研究了气相中不同自旋态W+活化CO2分解的反应机理. 计算结果表明, W+活化CO2分解反应以六重态进入反应通道, 经过六重态势能面到四重态势能面的系间窜越(ISC),最后产物WO+和CO以四重态离开反应通道. 运用Harvey方法优化出最低能量交叉点(MECP), 并计算了MECP处的自旋-轨道耦合(SOC)常数(494.95 cm-1), 势能面的交叉和在MECP处较强的自旋-轨道耦合作用降低了自旋禁阻反应能垒, 为反应提供了一条低能反应路径, 反应总放热量为122.33 kJ·mol-1.

关键词: 密度泛函理论, W+活化, 自旋禁阻反应, 最低能量交叉点, 自旋-轨道耦合

Abstract:

We investigated the spin-forbidden reaction mechanism of CO2 cleavage, activated by W+ in gas phase, using density functional theory (DFT, UB3LYP) with the relativistic effective core potential (ECP) of basis sets (SDD) for Wand the 6-311+G(3d) basis set forCand O. The calculation results showthatW+ initially closes to CO2 on the sextet surface, then the products, WO+ and CO, exit the channel on the quartet surface. The process involves an intersystem crossing (ISC) from the sextet to the quartet state. We obtained a minimum energy crossing point (MECP) using the algorithm in Harvey method. The large spin-orbital coupling (SOC) constant (494.95 cm-1) calculated shows that the spin-forbidden reaction takes place easily. Furthermore, the overall exothermicity is 122.33 kJ·mol-1.

Key words: Density functional theory, W+activation, Spin-forbidden reaction, Minimumenergy crossing point, Spin-orbital coupling

MSC2000: 

  • O641