Open AccessIsostructural Halogen Exchange and Halogen Bonds: The Case of N-(4-Halogenobenzyl)-3-halogenopyridinium Halogenides
Author(s) -
Luka Fotović,
Nikola Bedeković,
Vladimir Stilinović
Publication year - 2022
Publication title -
crystal growth and design
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.966
H-Index - 155
eISSN - 1528-7505
pISSN - 1528-7483
DOI - 10.1021/acs.cgd.1c01285
Subject(s) - isostructural , halogen bond , halogen , chemistry , pyridine , crystallography , crystal structure , acceptor , bromide , inorganic chemistry , medicinal chemistry , organic chemistry , alkyl , physics , condensed matter physics
Six N -(4-halogenobenzyl)-3-halogenopyridinium cations were prepared by reacting meta -halogenopyridines (Cl, Br, and I) with (4-halogenobenzyl) bromides (Br and I) and were isolated as bromide salts, which were further used to obtain iodides and chlorides. Sixteen compounds (out of 18 possible cation/anion combinations) were obtained; two crystallized as hydrates and 14 as solvent free salts, 11 of which belonged to one isostructural series and 3 to another. All crystal structures comprise halogen-bonded chains, with the anion as an acceptor of two halogen bonds, with the pyridine and the benzyl halogen substituents of two neighboring cations. The halogen bonds with the pyridine halogen show a linear correlation between the relative halogen bond length and angle, which primarily depend on the donor halogen. The parameters of the other halogen bonds vary with all three halogens, indicating that the former halogen bond is the dominant interaction. This is also in accord with the calculated electrostatic potential in the σ-holes of the halogens and the thermal properties of the solids. The second isostructural group comprises combinations of the best halogen bond donors and acceptors, and features a more favorable halogen bond geometry of the dominant halogen bond, reaffirming its significance as the main factor in determining the structure.