取代基
化学
卤素
卤键
价键理论
溴
价(化学)
现代价键理论
Atom(片上系统)
原子轨道
计算化学
接受者
价电子
债券定单
粘结强度
化学物理
分子轨道
电子
结晶学
粘结长度
分子
立体化学
晶体结构
物理
量子力学
有机化学
烷基
胶粘剂
图层(电子)
计算机科学
嵌入式系统
作者
Davide Franchini,Alessandro Genoni,Federico Dapiaggi,Stefano Pieraccini
摘要
Abstract A theoretical investigation on the nature of the halogen bond through a valence‐bond approach has been carried out with two main goals: (a) finding further confirmations of already existing explanations on the physical origins of the halogen bond and (b) possibly enriching the current models with new details. To achieve these goals we have exploited the spin‐coupled method and we have performed computations on RBr⋯NH 3 dimers characterized by a different electron withdrawing power of substituent R to the bromine atom. The analysis of typical spin‐coupled descriptors (eg, shapes and overlaps of the spin‐coupled orbitals, weights of the spin‐coupled structures) in the different cases and in function of the distance between the monomers allowed us to draw qualitative conclusions about the formation and the strength of the halogen bonds. In particular, the investigation not only confirmed the validity of already existing models (ie, σ‐hole and lump‐hole models) but also highlighted interesting new features, such as the fact that the depletion of electron density around the bromine atom does not extend only toward the acceptor of the halogen bond, but also in the opposite direction (toward the substituent of the halogen), thus forming a sort of σ‐tunnel, rather than a simple σ‐hole.
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