title: 2-Amino-6-methyl-pyridinium 4-methyl-benzene-sulfonate.
abstract: In the asymmetric unit of the title salt, C6H9N2 (+)·C7H7O3S(-), there are two independent 2-amino-6-methyl-pyridinium cations and two independent 4-methyl-benzene-sulfonate anions. Both cations are protonated at their pyridine N atoms and their geometries reveal amine-imine tautomerism. In the 4-methyl-benzene-sulfonate anions, the carboxyl-ate 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 inter-act with the protonated N atoms and the 2-amino groups of a cation via a pair of N-H⋯O hydrogen bonds, forming an R 2 (2)(8) ring motif. These motifs are connected via N-H⋯O hydrogen bonds, forming chains running along the a-axis direction. Within the chains there are weak C-H⋯O hydrogen bonds present. In addition, aromatic π-π stacking inter-actions [centroid-centroid distances = 3.771 (2), 3.599 (2), 3.599 (2) and 3.497 (2) Å] involving neighbouring chains are also observed.
authors.affiliation: Department of Physics, Presidency College (Autonomous), Chennai 600 005, Tamil Nadu, India ; Department of Physics, The New College (Autonomous), Chennai 600 014, Tamil Nadu, India.
authors.forename: K Syed Suresh
authors.initials: KS
authors.lastname: Babu
authors.affiliation: Department of Physics, Presidency College (Autonomous), Chennai 600 005, Tamil Nadu, India.
authors.forename: M
authors.initials: M
authors.lastname: Dhavamurthy
authors.affiliation: Department of Physics, The New College (Autonomous), Chennai 600 014, Tamil Nadu, India.
authors.forename: M
authors.initials: M
authors.lastname: NizamMohideen
authors.affiliation: Department of Physics, Presidency College (Autonomous), Chennai 600 005, Tamil Nadu, India.
authors.forename: G
authors.initials: G
authors.lastname: Peramaiyan
authors.affiliation: Department of Physics, Presidency College (Autonomous), Chennai 600 005, Tamil Nadu, India.
authors.forename: R
authors.initials: R
authors.lastname: Mohan