2-Amino-5-methylpyridinium 3-aminobenzoate

In the title compound, C6H9N2 +·C7H6NO2 −, the H atom of the N—H group and an H atom of the 2-amino group from the cation are involved in intermolecular N—H⋯O hydrogen bonds with the O atoms of the carboxylate group of the anion, forming an R 2 2(8) ring motif. These ring motifs are, in turn, connected by further N—H⋯O hydrogen bonds, forming a two-dimensional network. The crystal structure is further stabilized by π⋯π stacking interactions involving the benzene and pyridinium rings with a centroid–centroid distance of 3.7594 (8) Å.

In the title compound, C 6 H 9 N 2 + ÁC 7 H 6 NO 2 À , the H atom of the N-H group and an H atom of the 2-amino group from the cation are involved in intermolecular N-HÁ Á ÁO hydrogen bonds with the O atoms of the carboxylate group of the anion, forming an R 2 2 (8) ring motif. These ring motifs are, in turn, connected by further N-HÁ Á ÁO hydrogen bonds, forming a two-dimensional network. The crystal structure is further stabilized by Á Á Á stacking interactions involving the benzene and pyridinium rings with a centroid-centroid distance of 3.7594 (8) Å .

Experimental
A hot methanol solution (20 ml) of 2-amino-5-methylpyridine (54 mg, Aldrich) and 3-aminobenzoic acid (68 mg, Merck) were mixed and warmed over a heating magnetic stirrer for a few minutes. The resulting solution was allowed to cool slowly at room temperature and crystals of the title compound appeared after a few days.

Refinement
The methyl H atoms were positioned geometrically and were refined using a riding model, with U iso (H) = 1.5U eq (C). A  Fig. 1. The asymmetric unit of the title compound. Displacement ellipsoids are drawn at the 50% probability level.   Glazer, 1986) operating at 100.0 (1) k.
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.
Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > 2sigma(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.