Affiliations 

  • 1 Research Centre for Crystalline Materials, School of Science and Technology, Sunway University, 47500 Bandar Sunway, Selangor Darul Ehsan, Malaysia
Acta Crystallogr E Crystallogr Commun, 2020 Feb 01;76(Pt 2):245-253.
PMID: 32071755 DOI: 10.1107/S2056989020000572

Abstract

The asymmetric unit of the title 1:2 co-crystal, C14H14N4O2·2C7H5ClO2, comprises two half mol-ecules of oxalamide (4LH2), as each is disposed about a centre of inversion, and two mol-ecules of 4-chloro-benzoic acid (CBA), each in general positions. Each 4LH2 mol-ecule has a (+)anti-periplanar conformation with the pyridin-4-yl residues lying to either side of the central, planar C2N2O2 chromophore with the dihedral angles between the respective central core and the pyridyl rings being 68.65 (3) and 86.25 (3)°, respectively, representing the major difference between the independent 4LH2 mol-ecules. The anti conformation of the carbonyl groups enables the formation of intra-molecular amide-N-H⋯O(amide) hydrogen bonds, each completing an S(5) loop. The two independent CBA mol-ecules are similar and exhibit C6/CO2 dihedral angles of 8.06 (10) and 17.24 (8)°, indicating twisted conformations. In the crystal, two independent, three-mol-ecule aggregates are formed via carb-oxy-lic acid-O-H⋯N(pyrid-yl) hydrogen bonding. These are connected into a supra-molecular tape propagating parallel to [100] through amide-N-H⋯O(amide) hydrogen bonding between the independent aggregates and ten-membered {⋯HNC2O}2 synthons. The tapes assemble into a three-dimensional architecture through pyridyl- and methyl-ene-C-H⋯O(carbon-yl) and CBA-C-H⋯O(amide) inter-actions. As revealed by a more detailed analysis of the mol-ecular packing by calculating the Hirshfeld surfaces and computational chemistry, are the presence of attractive and dispersive Cl⋯C=O inter-actions which provide inter-action energies approximately one-quarter of those provided by the amide-N-H⋯O(amide) hydrogen bonding sustaining the supra-molecular tape.

* Title and MeSH Headings from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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