Structural, Hirshfeld surface and theoretical analysis of two conformational polymorphs of N,N′-bis(pyridin-3-ylmethyl)oxalamide

Jotani, Mukesh M. and Zukerman-Schpector, Julio and Sousa Madureira, Lucas and Poplaukhin, Pavel and Arman, Hadi D. and Miller, Tyler and Tiekink, Edward R. T. * (2016) Structural, Hirshfeld surface and theoretical analysis of two conformational polymorphs of N,N′-bis(pyridin-3-ylmethyl)oxalamide. Zeitschrift für Kristallographie - Crystalline Materials, 231 (7). pp. 415-425. ISSN 2194-4946

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Abstract

The common feature of two conformational polymorphs of N,N′-bis(pyridin-3-ylmethyl)oxalamide is their crystallisation in the monoclinic space group P21/c with Z=4. In low symmetry form 1, the central core is effectively planar and the terminal pyridyl rings adopt a syn-periplanar conformation. In the high symmetry form, 2, there are two independent molecules in the asymmetric unit but each is located about a centre of inversion. The rings again are almost perpendicular to the central plane but, from symmetry are anti-periplanar. Computational chemistry shows that symmetric molecules with syn (two-fold) and anti (centrosymmetric) conformations have nearly identical energies. In the molecular packing of each of 1 and 2, supramolecular tapes based on amide-N–H···O(amide) hydrogen bonding are found. In 1, these are connected into layers by C–H···N(pyridyl) interactions, while in 2, the chains are linked into a three-dimensional architecture by C–H···N(pyridyl) interactions. The importance of hydrogen bonding is emphasised in the analysis of the Hirshfeld surfaces.

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