Synthesis and structure of 2-amino-4-nitro-1H-imidazol-3-ium chloride.

Single crystals of 2-amino-4-nitro-1H-imidazol-3-ium chloride, C3H5N4O2 +·Cl-, were synthesized by slow evaporation and characterized by X-ray diffraction. The crystal structure features a planar imidazolium cation and a chloride anion, forming a three-dimensional supra-molecular network via N-H⋯Cl and N-H⋯O hydrogen bonds. Hirshfeld surface analysis reveals that O⋯H/H⋯O contacts (28.7%) and Cl⋯H/H⋯Cl inter-actions (24.2%) dominate the inter-molecular packing, with C⋯O/O⋯C contacts (5.1%) indicating significant C-H⋯O hydrogen-bonding contributions. Additional consolidation arises from van der Waals inter-actions (H⋯H, 13.4%), while π-π stacking remains negligible. The synergy of strong hydrogen bonds and weaker inter-actions underpins the robust supra-molecular architecture, providing insights into crystal engineering strategies for nitro-imidazole-based functional materials.