Bond Marcus R, Silwal Sajan
Department of Chemistry and Physics, Southeast Missouri State University, Cape Girardeau, MO 63701, USA.
IUCrdata. 2023 Jan 10;8(Pt 1):x230015. doi: 10.1107/S2414314623000159. eCollection 2023 Jan.
The organic cation in the title mol-ecular salt, CHNCl·Cl, exhibits the effect with a C-H bond of the C atom β to the chloro group donating electrons to the anti-bonding orbital of the C-Cl bond to stabilize the conformation [Cl-C-C-C = -68.6 (6)°], as confirmed by DFT geometry optimizations that show a lengthening of the C-Cl bond relative to that of the conformation. Of further inter-est is the higher point group symmetry of the crystal (), compared that of the that of the mol-ecular cation, which arises from a supra-molecular head-to-tail square arrangement of four mol-ecular cations that circulate in a counterclockwise direction when viewed down the tetra-gonal axis.
标题分子盐CHNCl·Cl中的有机阳离子表现出这样一种效应：与氯原子相连的碳原子的β位C-H键将电子给予C-Cl键的反键轨道，以稳定其构象[Cl-C-C-C = -68.6 (6)°]，密度泛函理论（DFT）几何优化证实了这一点，该优化表明相对于反式构象，C-Cl键有所延长。晶体（）的点群对称性高于分子阳离子的点群对称性，这一现象更有趣，它源于四个分子阳离子的超分子头对头方形排列，当沿四方轴向下看时，这些阳离子沿逆时针方向循环。
