Department of Chemistry, Xavier University of Louisiana, 1 Drexel Drive, Box 22, New Orleans, LA 70125, USA.
Phys Chem Chem Phys. 2013 Nov 7;15(41):17742-51. doi: 10.1039/c3cp52768a.
In this work we highlight recent work aimed at the characterization of halogen bonds. Here we discuss the origins of the σ-hole, the modulation of halogen bond strength by changing of neighboring chemical groups (i.e. halogen bond tuning), the performance of various computational methods in treating halogen bonds, and the strength and character of the halogen bond, the dihalogen bond, and two hydrogen bonds in bromomethanol dimers (which serve as model complexes) are compared. Symmetry adapted perturbation theory analysis of halogen bonding complexes indicates that halogen bonds strongly depend on both dispersion and electrostatics. The electrostatic interaction that occurs between the halogen σ-hole and the electronegative halogen bond donor is responsible for the high degree of directionality exhibited by halogen bonds. Because these noncovalent interactions have a strong dispersion component, it is important that the computational method used to treat a halogen bonding system be chosen very carefully, with correlated methods (such as CCSD(T)) being optimal. It is also noted here that most forcefield-based molecular mechanics methods do not describe the halogen σ-hole, and thus are not suitable for treating systems with halogen bonds. Recent attempts to improve the molecular mechanics description of halogen bonds are also discussed.
在这项工作中，我们重点介绍了最近旨在描述卤键特征的工作。在这里，我们讨论了 σ-空穴的起源、通过改变相邻化学基团来调节卤键强度（即卤键调谐）、各种计算方法在处理卤键时的性能，以及溴甲醇二聚体（作为模型复合物）中卤键、二卤键和两个氢键的强度和特征。卤键配合物的对称自适应微扰理论分析表明，卤键强烈依赖于色散和静电相互作用。卤键供体的卤素 σ-空穴和电负性卤素之间发生的静电相互作用是卤键表现出高度方向性的原因。由于这些非共价相互作用具有很强的分散分量，因此非常有必要仔细选择用于处理卤键体系的计算方法，相关方法（如 CCSD(T)）是最佳方法。这里还指出，大多数基于力场的分子力学方法不描述卤素 σ-空穴，因此不适合处理具有卤素键的系统。还讨论了最近改进卤素键分子力学描述的尝试。
