Amino-[(1H-benzimidazol-2-yl)amino]-methaniminium 4-methyl-benzene-sulfonate.

The asymmetric unit of the title salt, C8H10N5 (+)·C7H7O3S(-), consists of two amino-[(1H-benzimidazol-2-yl)amino]-meth-an-im-inium cations and two 4-methyl-benzene-sulfonate anions. The cations are each stabilized by intra-molecular 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 supra-molecular framework. Two strong π-π 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.