Crystal structure, Hirshfeld surface analysis and computational study of the 1:2 co-crystal formed between N,N′-bis[(pyridin-4-yl)methyl]ethanediamide and 3-chlorobenzoic acid

Abstract

The asymmetric unit of the title 1:2 co-crystal, C14H14N4O2·2C7H5ClO2, comprises a half-molecule of oxalamide (4 LH2), being located about a centre of inversion, and a molecule of3-chlorobenzoic acid (3-ClBA) in a general position. From symmetry, the 4 LH2 molecule has a (+)antiperiplanar conformation with the 4-pyridyl residues lying to either side of the central, planar C2N2O2 chromophore with the dihedral angle between the core and pyridyl ring being 74.69 (11)°; intramolecular amide-N—H...O(amide) hydrogen bonds are noted. The 3-ClBA molecule exhibits a small twist as seen in the C6/CO2 dihedral angle of 8.731 (12)°. In the molecular packing, three-molecule aggregates are formed via carboxylic acid-O—H...N(pyridyl) hydrogen bonding. These are connected into a supramolecular tape along [111] through amide-N—H...O(carbonyl) hydrogen bonding. Additional points of contact between molecules include pyridyl and benzoic acid-C—H...O(amide), methylene-C—H...O(carbonyl) and C—Cl...π(pyridyl) interactions so a three-dimensional architecture results. The contributions to the calculated Hirshfeld surface are dominated by H...H (28.5%), H...O/O...H (23.2%), H...C/C...H (23.3%), H...Cl/Cl...H (10.0%) and C...Cl/C...Cl (6.2%) contacts. Computational chemistry confirms the C—Cl...π interaction is weak, and the importance of both electrostatic and dispersion terms in sustaining the molecular packing despite the strong electrostatic term provided by the carboxylic acid-O—H...N(pyridyl) hydrogen bonds.