高等学校化学学报

高等学校化学学报 ›› 2005, Vol. 26 ›› Issue (2): 299.

• 研究论文 • 上一篇    下一篇

H3PO→H2POH异构化反应的直接动力学研究

王文亮1, 王渭娜1, 罗琼1,2, 房喻1, 李前树1,2   

  1. 1. 陕西师范大学化学与材料科学学院,西安 710062;
    2. 北京理工大学理学院,北京 100081
  • 收稿日期:2004-03-19 出版日期:2005-02-10 发布日期:2005-02-10
  • 通讯作者: 李前树(1942年出生),男,博士,教授,博士生导师,主要从事量子化学理论与应用、非线性化学动力学等研究.E-mail:qsli@bit.edu.cn E-mail:qsli@bit.edu.cn
  • 基金资助:

    陕西省自然科学基金(批准号:2003B05)资助

Direct Dynamics Studies on the Isomerization Reaction H3PO→H2POH

WANG Wen-Liang1, WANG Wei-Na1, LUO Qiong1,2, FANG Yu1, LI Qian-Shu1,2   

  1. 1. School of Chemistry and Materials Science, Shaanxi Normal University, Xi'an 710062, China;
    2. School of Science, Beijing Institute of Technology, Beijing 100081, China
  • Received:2004-03-19 Online:2005-02-10 Published:2005-02-10

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摘要： 在QCISD(T)/6-311C++G(2df,2pd)//QCISD/6-311C++G(d,p)+ZPE水平上,对H3PO的异构化反应H3PO→(1)H2POH(trans)→(2)H2POH(cis)进行了计算研究.结果表明,H原子由P原子向O原子迁移反应(1)的能垒为250.0kJ/mol,是反应速率控制步骤,而O_H键绕P_O键旋转的构型转化反应(2)的能垒只为12.3kJ/mol.利用经典过渡态理论(TST)与变分过渡态理论(CVT)分别计算了反应(1)在200～2000K温度区间内的速率常数kTST和kCVT,获得了经小曲率隧道效应(SCT)及Eckart模型校正后的速率常数kTST/Eckart和kCVT/SCT.对只涉及H原子迁移的反应(1),量子力学隧道效应的影响在低温段非常明显,而变分效应对反应速率常数的影响很小.

关键词: H3PO, 异构化反应, QCISD, 反应路径, 速率常数

Abstract: The isomerization reaction of H3PO(1)H2POH(trans)(2)H2POH(cis) was studied by using the direct ab initio dynamic method. The optimized geometries and frequencies were calculated at the QCISD/6-311C++G(d,p) level of theory for the reactant, products, and transition states as well as 18 selected points along the minimum energy pathway. In order to obtain more reliable energies, the single-point calculations were carried out at the QCISD(T)/6-311C++G(2df,2pd) level of theory. The barrier of reaction(1), in which the hydrogen atom transfers from phosphor atom to oxygen atom, is more higher than that of reaction(2), the former is 250.0 kJ/mol and the latter is 12.3 kJ/mol. Therefore, reaction(1) is the rate controlling step of the isomerization reaction. The rate constants of reaction(1) were evaluated in the temperature range of 200-2000 K by the classical transition state theory, the classical transition state theory with Eckart tunneling model, the canonical variational transition state theory, and canonical variational transition state theory incorporating small-curvature tunneling correction, respectively. The fitted three-parameter expression from the CVT/SCT and TST/Eckart in the temperature range of 200-2000 K is kCVT/SCT=2.747×10-68 T24.01exp(-1.0094×104/T)s-1 and kTST/Eckart=1.423×10-69 T24.46exp(-1.0182×104/T)s-1, respectively. The results show that the tunneling effect is significant and the variational effect is small for the calculation of the rate constant.

Key words: H3PO, Isomerizazion reaction, QCISD, Reaction pathway, Rate constant

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