Laboratory of Theoretical Chemistry, Department of Chemistry, University of Maragheh, PO Box: 5513864596, Maragheh, Iran.
J Mol Model. 2013 Jun;19(6):2559-66. doi: 10.1007/s00894-013-1804-1. Epub 2013 Mar 2.
Halogen-bonding, a noncovalent interaction between a halogen atom X in one molecule and a negative site in another, plays critical roles in fields as diverse as molecular biology, drug design and material engineering. In this work, we have examined the strength and origin of halogen bonds between carbene CH₂ and XCCY molecules, where X = Cl, Br, I, and Y = H, F, COF, COOH, CF₃, NO₂, CN, NH₂, CH₃, OH. These calculations have been carried out using M06-2X, MP2 and CCSD(T) methods, through analyses of surface electrostatic potentials V S(r) and intermolecular interaction energies. Not surprisingly, the strength of the halogen bonds in the CH₂···XCCY complexes depend on the polarizability of the halogen X and the electron-withdrawing power of the Y group. It is revealed that for a given carbene···X interaction, the electrostatic term is slightly larger (i.e., more negative) than the dispersion term. Comparing the data for the chlorine, bromine and iodine substituted CH₂···XCCY systems, it can be seen that both the polarization and dispersion components of the interaction energy increase with increasing halogen size. One can see that increasing the size and positive nature of a halogen's σ-hole markedly enhances the electrostatic contribution of the halogen-bonding interaction.
卤键是一种非共价相互作用，发生在一个分子中的卤素原子 X 与另一个分子中的负电荷部位之间，在分子生物学、药物设计和材料工程等多个领域都起着至关重要的作用。在这项工作中，我们研究了卡宾 CH₂与 XCCY 分子之间卤键的强度和起源，其中 X = Cl、Br、I，而 Y = H、F、COF、COOH、CF₃、NO₂、CN、NH₂、CH₃、OH。这些计算是使用 M06-2X、MP2 和 CCSD(T)方法，通过分析表面静电势 V S(r)和分子间相互作用能进行的。毫不奇怪，CH₂···XCCY 配合物中卤键的强度取决于卤素 X 的极化率和 Y 基团的吸电子能力。结果表明，对于给定的卡宾···X 相互作用，静电项略大（即更负）。比较氯、溴和碘取代的 CH₂···XCCY 体系的数据，可以看出相互作用能的极化和色散分量都随卤素尺寸的增加而增加。可以看到，卤素 σ-hole 的尺寸和正电性的增加显著增强了卤键相互作用的静电贡献。
