Synthesis, structural characterization, Hirshfeld surface analysis and QTAIM analysis of 3-(4-cyano-thio-phen-3-yl)-[1,2,4]selena-diazolo[4,5-a]pyridin-4-ium chloride.

The title compound, C11H6N3SSe+·Cl-, produced by the reaction between 3,4-di-cyano-thio-phene and 2-pyridyl-selenyl chloride was isolated as a salt that crystallizes in the triclinic space group P1. Notable features include strong chalcogen inter-actions (Se⋯Cl and Se⋯S), as revealed through Hirshfeld surface analysis, which also highlights significant contributions from N⋯H/H⋯N, C⋯H/H⋯C and H⋯H contacts in the crystal packing. Supra-molecular inter-actions were further analysed using density functional theory (DFT) and quantum theory of atoms in mol-ecules (QTAIM) at the ωB97XD/6-311++G** level of theory.