Bond orders for intermolecular interactions in crystals: charge transfer, ionicity and the effect on intramolecular bonds

IUCrJ

Karton, A.¹  Alhameedi, K.² 

[1] College of Education for Pure Science, University of Karbala, Karbala, Iraq;School of Molecular Sciences, University of Western Australia, 35 Stirling Highway, Perth 6009, Australia

关键词: INTERMOLECULAR INTERACTIONS;    BOND ORDER;    IONICITY;    HYDROGEN BONDING;    HALOGEN BONDING;    CRYSTAL ENGINEERING;    COMPUTATIONAL MODELLING;    MOLECULAR CRYSTALS;   

DOI  :  10.1107/S2052252518010758

学科分类：数学（综合）

来源: International Union of Crystallography

【 摘 要 】

The question of whether intermolecular interactions in crystals originate from localized atom⋯atom interactions or as a result of holistic molecule⋯molecule close packing is a matter of continuing debate. In this context, the newly introduced Roby–Gould bond indices are reported for intermolecular `σ-hole' interactions, such as halogen bonding and chalcogen bonding, and compared with those for hydrogen bonds. A series of 97 crystal systems exhibiting these interaction motifs obtained from the Cambridge Structural Database (CSD) has been analysed. In contrast with conventional bond-order estimations, the new method separately estimates the ionic and covalent bond indices for atom⋯atom and molecule⋯molecule bond orders, which shed light on the nature of these interactions. A consistent trend in charge transfer from halogen/chalcogen bond-acceptor to bond-donor groups has been found in these intermolecular interaction regions via Hirshfeld atomic partitioning of the electron populations. These results, along with the `conservation of bond orders' tested in the interaction regions, establish the significant role of localized atom⋯atom interactions in the formation of these intermolecular binding motifs.

【 授权许可】

CC BY