化学学报 ›› 2004, Vol. 62 ›› Issue (13): 1191-1196. 上一篇    下一篇

研究论文

HNCS与CX(X=H,F,Cl)自由基反应的理论研究

刘朋军1,2, 赵岷1, 潘秀梅1, 苏忠民1, 王荣顺1   

  1. 1. 东北师范大学化学学院功能材料化学研究所, 长春, 130024;
    2. 海南师范学院化学系, 海口, 571158
  • 投稿日期:2003-09-04 修回日期:2004-01-31 发布日期:2014-02-17
  • 通讯作者: 王荣顺,E-mail:wangrs@nenu.edu.cn E-mail:wangrs@nenu.edu.cn
  • 基金资助:
    教育部"跨世纪优秀人才培养计划"基金(教技函[2001]3)、海南省教育厅科研基金(No.hjkj200312)、东北师范大学年轻教师基金(No.111382)资助项目.

Theoretical Studies on the Mechanism for the Reaction of HNCS with CX (X=H, F, Cl) Radical

LIU Peng-Jun1,2, ZHAO Min1, PAN Xiu-Mei1, SU Zhong-Min1, WANG Rong-Shun1   

  1. 1. Institute of Functional Material Chemistry, Faculty of Chemistry, Northeast Normal University, Changchun 130024;
    2. Department of Chemistry, Hainan Normal University, Haikou 571158
  • Received:2003-09-04 Revised:2004-01-31 Published:2014-02-17

用量子化学密度泛函理论的UB3LYP方法,在6-31+G*水平上按BERNY能量梯度解析法全参数优化了HNCS与CX (X=H,F,Cl)反应势能面上各驻点的几何构型,通过同一水平的振动频率分析确认了中间体和过渡态,并得到各驻点的零点能校正(Ezpc).通过内禀反应坐标(IRC)计算确认了反应物、中间体、过渡态和产物的相关性并得到最小能量途径(MEP).为了得到体系势能面的更准确信息,在各驻点的UB3LYP/6-31+G*构型基础上,又进行了UQCISD(T)/6-311+G**水平上的单点能计算,得到体系的势能面信息和可能的反应机理.应用变分过渡态理论及最小能量途径半经典绝热基态(MEPSAG)、小曲率半经典绝热基态(SCSAG)隧道效应校正的方法计算了标题反应在250~1500 K温度范围内的速率常数.研究结果表明,HNCS与CX自由基反应是通过分子间H原子迁移及N-C键的断裂,生成产物CS+NCXH.反应均为放热反应.

关键词: 异硫氰酸(HNCS), CX自由基, 反应机理, 密度泛函理论(DFT)

DFT-UB3LYP was used to calculate the geometries of reactants, intermediates, transition states and products for HNCS+CX (X=H, F, Cl) reaction on the 6-31+G* level.The transiton states and intermediates of the reaction were verified by frequency analysis.The relationship among reactants, transition states, intermediates and products was affirmed by IRC (intrinsic reaction coordinate) calculation.The energies along the MEP (minimum energy path) were further refined at the UQCISD(T)/6-311+G** level.The kinetics of the title reaction was studied by using the "direct dynamics" method of variational transition-state theory.The rate constants of the title reaction were calculated for the range of temperature 250~1500 K.In the calculation, we considered the tunneling correction.The tunneling correction was calculated by using the centrifugal-dominant small curvature semiclassical adiabatic ground-state (CD-SCSAG) method.The results show that the reaction mechanism of the title reactions involves five steps.The reaction pathway is reactants→IMn1→TSn1→IMn2→TSn2→products.These reactions are exothermic.

Key words: isothiocyanic acid(HNCS), CX radical, reaction mechanism, density functional theory(DFT)