Contribution of Directional Dihydrogen Interactions in the Supramolecular Assembly of Single Crystals: Quantum Chemical and Structural Investigation of C17H17N3O2 Azine

Crystalline systems can be organized from several types of intermolecular interactions, among which classical and weak H-bonds are the most common, playing a very important role in the supramolecular assembly. However, in recent years a number of works have considered the influence of the homonuclear dihydrogen interaction, which had been neglected for a long time, to describe the supramolecular assembly of single crystals. In the C17H17N3O2 azine of the present study, a nonclassical dihydrogen interactions (C–H···H–C contact) have appeared in the crystal structure with a fundamental contribution toward the stability of crystalline packing. Nonetheless, an X-ray structural analysis is not conclusive to assess the real importance of the C–H···H–C contact. In order to characterize the nature and implications of C–H···H–C contacts concomitant with the classical interactions, the crystallized compound was evaluated by Hirshfeld surface, Quantum Theory of Atoms in Molecules, natural bond orbital, and Car–Parrinello molecular dynamics. The results establish that these interactions really exist, and their extension is responsible for the cooperative effect on the stability of crystalline packing. We expect that a more thorough understanding and description of homonuclear dihydrogen interactions in the supramolecular assembly of C17H17N3O2 can assist in the crystal engineering of small molecules, offering progress on physical–chemistry parameters of biological and material processes.