CH_2CCl自由基与HNCS反应机理的理论研究  

Theoretical Study of the Reaction Mechanism of CH_2CCl Radical with HNCS

作　　者：徐伯华[1] 

机构地区：[1]涪陵师范学院 化学系,涪陵408003

出　　处：《西南大学学报（自然科学版）》2007年第7期72-78,共7页Journal of Southwest University(Natural Science Edition)

基　　金：重庆市教委自然科学基金(kj061307).

摘　　要：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CH_2CCl自由基与HNCS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,在QCISD(T)/6- 311++G(d,p)水平上计算了各物质的单点能.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,AIM计算所得的部分成键临界点电荷密度的变化也确认了反应过程.对于CH_2CCl自由基与HNCS反应,找到了7条反应通道.结果分析表明.反应通道CH_2CCl+HNCS→IMAl→TSA1→CH_2CHCl+NCS控制步骤活化能最低,是该反应的主要通道.有稳定的氢键复合物IMAl生成,表现为H原子迁移反应特征;反应通道CH_2CCl+ HNCS→TSDl→IMDl→TSD5→CH_2CClS+HNC控制步骤活化能稍高,是该反应的次要通道.The reaction mechanism of CH2CCl radical with HNCS was investigated by E3LYP method at 6- 311 ＋ ＋ G（d, p） basis sets. The geometries and harmonic frequencies of reactants, intermediates, transition states and products were 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＋＋G （d, p） level. Intermediates and transition states were confirmed by the results of vibration analysis and IRC calculation. At the same time, AIM （atom-in-molecule） theory was applied to calculate the charge density of some bonding critical points. Investigation of seven possible reaction pathways indicated that the main pathway is CH2CCl＋ HNCS-→IMAl→TSAl→CH2CHCl＋NCS, which is characterized by hydrogen atom transferring, and the pathway, CH2CCl＋ HNCS→TSDl→IMDl→TSD5-→CH2CClS＋ HNC, is the secondary pathway.

关 键 词：CH2CCl自由基 HNCS 反应机理 活化能 

分 类 号：O643.12[理学—物理化学]