The N–H⋯S hydrogen bonding pattern in trithiocyanuric acid in crystalline state: geometric, topological, and energetic analysis of trithiocyanuric acid cocrystals

Abstract

Four new crystal structures of trithiocyanuric acid (TTCA) with diazine derivatives have been determined, revealing key N–H⋯S interactions that stabilize molecular aggregates. TTCA forms two types of chains—linear and zigzag—each with distinct structural characteristics. Geometry and Hirshfeld surface analyses, supported by quantum-theoretical calculations, demonstrate that both chain arrangements are equally feasible, arising from inherent preferences in the crystal's structural organization. The critical role of intermolecular hydrogen bonds, particularly those involving amine groups as proton donors, in stabilizing these cocrystals is highlighted. To analyze the energy parameters, we applied the many-body extension of the supramolecular interaction energy approach for chain complexes in their crystal-state geometry, allowing decomposition of the interaction energy into two- and many-body contributions. The prevalent hydrogen bonding synthon, R²₂(8), which forms both linear and zigzag chain structures, was found to be crucial in stabilizing the TTCA aggregates.