2-Amino-4,6-dimethylpyridinium benzoate

In the title compound, C7H11N2 +·C7H5O2 −, the 2-amino-4,6-dimethylpyridinium cation and the benzoate anion are linked by two N—H⋯O hydrogen bonds, forming an R 2 2(8) ring motif. The H atoms in both the methyl groups are rotationally disordered, with fixed site occupancies of 0.50. In the crystal structure, the molecules are stabilized by intermolecular N—H⋯O hydrogen bonds. A π–π interaction, with a centroid–centroid distance of 3.661 (2) Å, is also observed.


Comment
This compound is derived from 2-amino-4,6-dimethylpyridine and benzaldehyde. Schiff bases provide more potential sites for both chemical and biological activities of compounds. Schiff bases with azomethine linkage were used as anti-infectious agents (Dhar et al., 1982). Pyridine and its derivatives play an important role in heterocyclic chemistry (Jeffrey, 1997). They are often involved in hydrogen-bond interactions (Jeffrey & Saenger, 1991).
The title 1:1 adduct compound contains an 2-amino-4,6-dimethylpyridinium cation and benzoate anion in the asymmetric unit. The parameters in (I), (Fig. 1), are within normal ranges. The 2-amino-4,6-dimethylpyridinium cation is planar with the maximum deviation of 0.005 (2)Å for atom C9. The H atoms of the methyl groups are disordered over two positions and with fixed site-occupancy factors of 0.50:0.50 for both of the methyl groups. The carboxylate group in benzoate anion is slightly twisted and make a dihedral angle of 7.2 (1)° with the attached benzene ring.

Experimental
An ethanol solution (20 ml) of 2-amino-4,6-dimethylpyridine (1.22 g, Aldrich) and benzaldehyde (1.06 g, Merck) were mixed, heated on a hot plate and stirred with a magnetic stirrer. The reaction mixture was refluxed for 4h. The resulting condensation solution was allowed to cool slowly at room temperature to form brownish materials. Purification was done using thin layer chromatography (TLC) and silica gel column chromatography (CC) eluted by chloroform:methanol and n-hexane:ethyl acetate solvent system. Finally the pure compound was recrystallized in ethanol which afforded the

Refinement
N bound H atoms was located from a difference Fourier map and were refined using a riding model, with U iso (H) = 1.2U eq (N). The methyl hydrogen atoms were located from the difference Fourier map and refined freely with the parent atom [U iso (H) = 1.5U eq (C)]. The rest of the hydrogen atoms were positioned geometrically and refined as riding model sup-2

Special details
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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq Occ. (