2-Amino-3-methylpyridinium 2-amino-5-methylpyridinium sulfate monohydrate

The asymmetric unit of the title compound, 2C6H9N2 +·SO4 2−·H2O, contains two isomeric protonated aminomethylpyridine cations, a sulfate anion and a solvent water molecule. The cations are in the iminium tautomeric form. In the crystal structure, intermolecular O—H⋯O, N—H⋯O and weak C—H⋯O hydrogen bonds link the components into a three-dimensional network. Additional stabilization is provided by weak π–π stacking interactions, with centroid–centroid distances of 3.758 (2) and 3.774 (1) Å.

The asymmetric unit of the title compound, 2C 6 H 9 N 2 + Á-SO 4 2À ÁH 2 O, contains two isomeric protonated aminomethylpyridine cations, a sulfate anion and a solvent water molecule. The cations are in the iminium tautomeric form. In the crystal structure, intermolecular O-HÁ Á ÁO, N-HÁ Á ÁO and weak C-HÁ Á ÁO hydrogen bonds link the components into a threedimensional network. Additional stabilization is provided by weakstacking interactions, with centroid-centroid distances of 3.758 (2) and 3.774 (1) Å .

Comment
We are not aware of any articles which report crystal structures containing different two pyridininium cations and a sulfate cation. We present the crystal structure of the title compound, (I), herein.
In the crystal structure, intermolecular O-H···O, N-H···O and weak C-H···O hydrogen bonds link the components of the structure into a three-dimensional network (Fig. 2). Additional stabilization is provided by weak π-π stacking interactions with centroid to centroid distances of 3.758 (2) and 3.774 (1)Å.
Experimental 2-Amino-3-methyl-pyridine, 2-amino-5-methyl-pyridine and sulfuric acid were mixed in molar ratio 1:1:1 and dissolved in sufficient water. The solution was stirred and heated until a clear solution resulted. Colourless crystals of (I) were formed by gradual evaporation of excess water over a period of one week at 293 K.

Refinement
H atoms of the water molecule were located in a differnce Fourier map, and were refined independently with isotropic displacement parameters. Other H atom were placed in calculated positions and allowed to ride on their parent atoms at distances of 0.93 Å for aromatic C atoms, 0.86 Å for amido and 0.96 Å for methyl with isotropic displacement parameters 1.2 times U eq of the parent atoms or 1.5 times U eq for methyl C atoms.