Direct Combined ab Initio/Transition State Theory Study of the Kinetics of the Abstraction Reactions of Halogenated Methanes with Hydrogen Atoms
Direct Combined ab Initio/Transition State Theory Study of the Kinetics of the Abstraction Reactions of Halogenated Methanes with Hydrogen Atoms
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DOI：
10.1021/jp047305a
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发表时间：
2004-11
影响因子：
2.9
通讯作者：
F. Louis;C. Gonzalez;J. Sawerysyn
中科院分区：
文献类型：
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作者：
F. Louis;C. Gonzalez;J. Sawerysyn
本文对七种取代卤代甲烷（CH_3Cl、CH_2Cl_2、CHCl_3、CCl_4、CHF_3、CHF_2Cl和CHF_2Cl_2）在B y H原子攻击下的H-、Cl-和F-原子夺取反应进行了理论计算。采用非限制性Moller-Plesset二阶微扰理论（UMP 2），在6-311++G（d，p）基组下，进行了结构优化和振动频率计算.在CCSD（T）空间中，采用6-311 ++G（3df，3 pd）基组，用高关联从头算耦合团簇方法计算了单、双和三重（微扰）电子激发下的单点能量.采用经典过渡态理论和简单的隧道效应修正，预测了反应速率常数随温度（700-2500 K）的变化，并拟合了计算的基元通道和总反应速率常数，得到了三参数Arrhenius表达式.
Theoretical calculations were carried out on the H-, Cl-, and F-atom abstraction reactions from a series of seven substituted halogenated methanes (CH3Cl, CH2Cl2, CHCl3, CCl4, CHF3, CHF2Cl, and CHFCl2 )b y H atom attacks. Geometry optimizations and vibrational frequency calculations were performed using unrestricted Moller-Plesset second-order perturbation theory (UMP2) with the 6-311++G(d,p) basis set. Single-point energy calculations were performed with the highly correlated ab initio coupled cluster method in the space of single, double and triple (pertubatively) electron excitations CCSD(T) using the 6-311 ++G(3df,3pd) basis set. Canonical transition-state theory with a simple tunneling correction was used to predict the rate constants as a function of temperature (700-2500 K), and three-parameter Arrhenius expressions were obtained by fitting to the computed rate constants for elementary channels and overall reaction.