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 center dot center dot center dot 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 center dot center dot center dot H-C contact. In order to characterize the nature and implications of C-H center dot center dot center dot 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.