Citation: LIU Ling-Ling, WANG Yong-Cheng. Spin-Forbidden Reaction Mechanism of CO2 Cleavage Activated by W+ in Gas Phase[J]. Acta Physico-Chimica Sinica, 2010, 26(02): 441-446. doi: 10.3866/PKU.WHXB20100218
气相中W+活化CO2分解的自旋禁阻反应机理
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.
English
Spin-Forbidden Reaction Mechanism of CO2 Cleavage Activated by W+ in Gas Phase
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 al rithm 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.
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