2-Amino-6-methylpyridinium 4-methylbenzenesulfonate

Abstract

In the asymmetric unit of the title salt, C6H9N2+·C7H7O3S−, there are two independent 2-amino-6-methylpyridinium cations and two independent 4-methylbenzenesulfonate anions. Both cations are protonated at their pyridine N atoms and their geometries reveal amine–imine tautomerism. In the 4-methylbenzenesulfonate anions, the carboxylate groups are twisted out of the benzene ring planes by 88.4 (1) and 86.2 (2)°. In the crystal, the sulfonate O atoms of an anion interact with the protonated N atoms and the 2-amino groups of a cationviaa pair of N—H...O hydrogen bonds, forming anR22(8) ring motif. These motifs are connectedviaN—H...O hydrogen bonds, forming chains running along thea-axis direction. Within the chains there are weak C—H...O hydrogen bonds present. In addition, aromatic π–π stacking interactions [centroid–centroid distances = 3.771 (2), 3.599 (2), 3.599 (2) and 3.497 (2) Å] involving neighbouring chains are also observed.