物理化学学报 >> 2012, Vol. 28 >> Issue (12): 2817-2823.doi: 10.3866/PKU.WHXB201208291

理论与计算化学 上一篇    下一篇

二聚体C2H4-nFn···LiH (n=0, 1, 2)中π锂键的性质和弱方向性

王树建, 李莹, 吴迪   

  1. 吉林大学理论化学研究所, 理论化学计算国家重点实验室, 长春 130023
  • 收稿日期:2012-07-05 修回日期:2012-08-27 发布日期:2012-11-14
  • 通讯作者: 吴迪 E-mail:wud@mail.jlu.edu.cn
  • 基金资助:

    国家自然科学基金(21173095)资助项目

Properties and Weak Directionality of the π-Lithium Bond in C2H4-nFn···LiH (n =0, 1, 2) Dimers

WANG Shu-Jian, LI Ying, WU Di   

  1. State Key Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun 130023, P. R. China
  • Received:2012-07-05 Revised:2012-08-27 Published:2012-11-14
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (21173095).

摘要:

采用二级微扰理论(MP2)量子化学研究方法, 对C2H4-nFn···LiH (n=0, 1, 2)二聚体的结构和π锂键性质进行了分析. 结果表明氟原子的取代改变了乙烯分子的π电子云形状, 从而使二聚体体系中的π锂键发生偏移、伸长和弯曲. 通过与类似的π氢键体系C2H4-nFn···HF (n=0, 1, 2)比较, 发现π锂键在二级弱相互作用的影响下, 发生了明显的弯曲, 表现出弱的方向性. 在CCSD(T)/6-311++G(3df, 3pd)理论水平下, 二聚体的相互作用能强弱顺序为: 33.85 kJ·mol-1 (C2H4-LiH)>27.32 kJ·mol-1 (C2H3F-LiH)>21.34 kJ·mol-1 (cis-C2H2F2-LiH)>20.25 kJ·mol-1 (g-C2H2F2-LiH), 说明氟取代削减了乙烯分子与LiH之间的相互作用.

关键词: π锂键, π氢键, 弱相互作用, 二级微扰理论, 取代效应

Abstract:

Using the second-order Møller-Plesset perturbation method, the structures and π-lithium bonding properties of C2H4-nFn···LiH (n=0, 1, 2) dimers were analyzed. The results showed that F substitution led to π electron cloud deformation in the ethylene molecule, and subsequent changes (deviation, elongation, and bend) in the π-lithium bonds in C2H4-nFn···LiH. In contrast to the π-hydrogen bonds in the C2H4-nFn···LiH (n=0, 1, 2) systems, the π-lithium bonds in the C2H4-nFn···LiH dimers were obviously bent because of secondary hydrogen bond interactions, and they exhibited weak directivity. For the four C2H4-nFn···LiH dimers, the strength of the interaction was 33.85 kJ·mol-1 (C2H4-LiH)>27.32 kJ·mol-1 (C2H3F-LiH)>21.34 kJ·mol-1 (cis-C2H2F2-LiH)>20.25 kJ·mol-1 (g-C2H2F2-LiH) at the CCSD(T)/6-311++G(3df, 3pd) level. This indicates that the F substituent effect decreases the strength of the interaction between ethylene and LiH molecules.

Key words: π-Lithium bond, π-Hydrogen bond, Weak interaction, Second-order Mø, ller-Plesset perturbation theory, Substituent effect

MSC2000: 

  • O641