Experimental Crystal data

R factor = 0.044; wR factor = 0.109; data-to-parameter ratio = 12.1. The asymmetric unit of the title salt, C8H10N5 +C7H7O3S, consists of two amino[(1H-benzimidazol-2-yl)amino]methan-iminium cations and two 4-methylbenzenesulfonate anions. The cations are each stabilized by intramolecular N—H N hydrogen bonds between the free amino groups and the imine N atoms of the benzimidazole units, forming S(6) ring motifs. In the crystal, cations and anions are linked by N—H O and C—H O hydrogen bonds, forming a three-dimensional supramolecular framework. Two strong – stacking inter-actions [centroid–centroid distances = 3.4112 (14) and 3.4104 (14) Å] also occur between the centroids of the imidazole rings of like cations. Related literature For the synthesis of guanidine-containing compounds, see: Wu et al. (2002); Hopkins et al. (2002); Kilburn et al. (2002); Manimala & Anslyn (2002). For pharmaceutical and chemica