Acta Chimica Sinica ›› 2013, Vol. 71 ›› Issue (05): 743-748.DOI: 10.6023/A13010049 Previous Articles     Next Articles



霍瑞萍a, 张祥b, 黄旭日a, 李吉来a, 孙家锺a   

  1. a 吉林大学理论化学研究所理论化学国家重点实验室 长春 130023;
    b 山西师范大学化学与材料科学学院 临汾 041004
  • 投稿日期:2013-01-10 发布日期:2013-03-05
  • 通讯作者: 李吉来,
  • 基金资助:

    项目受国家自然科学基金(Nos. 21103064, 21073075, 21173097)、教育部博士点基金(No. 20100061110046)、吉林大学理论化学国家重点实验室专项基金、吉林大学基本科研业务费(Nos. 421010061439, 450060445067)和吉林大学研究生创新基金(20121036)资助.

Mechanism Study of C4H(X2+)+H2 Reaction by Direct Ab Initio Methods

Huo Ruipinga, Zhang Xiangb, Huang Xuria, Li Jilaia, Sun Chiachunga   

  1. a State Key Laboratory of Theoretical & Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun 130023, China;
    b School of Chemistry and Materials Science, Shanxi Normal University, Linfen 041004, China
  • Received:2013-01-10 Published:2013-03-05
  • Supported by:

    Project supported by the National Natural Science Foundation of China (Nos. 21103064, 21073075, 21173097), Research Fund for the Doctoral Program of Higher Education of China (No. 20100061110046), the Special Funding of State Key Laboratory of Theoretical and Computational Chemistry, Jilin University, Basic Research Fund of Jilin University (Nos. 421010061439, 450060445067) and the Graduate Innovation Fund of Jilin University (20121036).

Hydrogen-deficient molecules have been implicated as the key intermediates in the combustion, planetary atmospheres, and so on. Their reactions with other molecules and/or radicals play important roles and are hot topic in interstellar chemistry. Although extensive efforts have been addressed on the electronic and spectroscopic properties of these molecules, continued extensive research, for example the kinetics and mechanism of their reactions, is still desirable. Therefore, we investigated the hydrogen abstraction (HAT) reaction by the linear butadiynyl radical C4H (CCCCH) from hydrogen (H2) by direct ab initio kinetics over a wide temperature range 40~1000 K theoretically at the CCSD(T)/aug-cc-pVTZ//BB1K/6-311+G(2d,2p) level of theory. The optimized geometries and frequencies of the stationary points are calculated at the BB1K/6-311+G(2d,2p), B3LYP/6-311+G(2d,2p) and M06-2x/6-311+G(2d,2p) level, respectively. To obtain more reliable reaction energies and barrier heights, high-level single-point calculations for the stationary points have been performed at the CCSD(T)/aug-cc-pVTZ by using BB1K/6-311+G(2d,2p) Cartesian coordinates. Two different hydrogen abstraction channels by C1 and C4 of C4H (C1C2C3C4H) have been explored, namely, Channel 1 (R1) and Channel 2 (R2). The activation barrier heights of Channel 1 and Channel 2 are 3.58 kcal/mol and 26.56 kcal/mol, respectively. The results indicate that C1 position of the C4H is a more reactive site. The electron transfer evolution may offer important clues for understanding hydrogen atom transfer (HAT), we therefore analyzed the electron transfer behaviors by NBO in detail. The theoretical rate constants were predicted by the conventional variational transition state theory (VTST), canonical variational transition-state theory (CVT) incorporating a small-curvature tunneling correction (CVT/SCT) method. For the lowest frequency, the partition function is evaluated using the hindered rotor approximation and the other vibrational modes are treated as quantum mechanical separable harmonic oscillators. The overall CVT/SCT rate constants are excellent in agreement with the available experimental results. The three-parameter expressions of Arrhenius rate constants are also provided within 40~1000 K. It is expected to be helpful for future studies over a wide temperature range where no experimental data available so far.

Key words: C4H, H2, rate constant, transition state theory (TST)