Supramolecular association of 1,2,5-chalcogenadiazoles: an unexpected self-assembled dissymetric [Se⋯N]2 four-membered ring

The structure of a self-assembled system containing benzoselenadiazole with the corresponding cationic N-methyl salt was determined by X-ray diffraction analysis. The assembly has a distinct tendency to establish intermolecular links in the solid state through secondary intermolecular bonding Se⋯N interactions. In such supramolecular association, the observation of an unusual asymmetric four-member ring [Se⋯N]2 with a short contact of 2.573 Å and a long contact of 2.966 Å was observed.