Strength, character, and directionality of halogen bonds involving cationic halogen bond donors
Year: 2017
Type: article
Abstract: Halogen bonds involving cationic halogen bond donors and anionic halogen bond acceptors have recently been recognized as being important in stabilizing the crystal structures of many salts. Theoretical characterization of these types of interactions, most importantly in terms of their directionality, has been limited. Here we generate high-quality symmetry adapted perturbation theory potential energy curves of a H 3 N–CC–Br + ⋯Cl − model system in order to characterize halogen bonds involving charged species, in terms of contributions from electrostatics, exchange, induction, and dispersion, with special emphasis on analyzing contributions that are most responsible for the directionality of these interactions. It is found that, as in the case of neutral halogen bonds, exchange forces are important contributors to the directionality of charged halogen bonds, however, it is also found that induction effects, which contribute little to the stability and directionality of neutral halogen bonds, play a large role in the directionality of halogen bonds involving charged species. Potential energy curves based on the ωB97X-D/def2-TZVP/C-PCM method, which includes an implicit solvation model in order to mimic the effects of the crystal medium, are produced for both the H 3 N–CC–Br + ⋯Cl − model system and for the 4-bromoanilinium⋯Cl − dimer, which is based on the real 4-bromoanilinium chloride salt, whose crystal structure has been determined experimentally. It is found that, within a crystal-like medium, charged halogen bond are significantly weaker than in the gas phase, having optimum interaction energies up to approximately −20 kcal mol −1 .
Source: Faraday Discussions
DOI: 10.1039/c7fd00106a
Authors: Kevin E. Riley, Khanh-An Tran
Institution: Xavier University of Louisiana
Language: English
Subfield: Physical and Theoretical Chemistry
Field: Chemistry
Domain: Physical Sciences
Open Access status: green
Awards: BUILD at Xavier, Project Pathways II, BUILD at Xavier, Project Pathways II, Generation of Liver X Receptor Agonists with LXRb Subtype Selectivity using Modern Computational and Chemical Synthetic Methods, Xavier RCMI Center for Cancer Research , G4171764187, RISE Option II at Xavier University of Louisiana
OpenAlex ID: W2602188051