Pyridine-2-carboximidamidate chloride monohydrate

The title compound, C6H8N3 +·Cl−·H2O, crystallizes with three formula units in the asymmetric unit. The cations are non-planar with the –C(NH2)2 groups twisted out of the ring planes. Each pyridine carboximidamidate cation is linked to another cation through N—H⋯N hydrogen bonds, to chloride ions by N—H⋯Cl hydrogen bonds, and to water molecules by N—H⋯O hydrogen bonds. Water molecules and chloride ions are also linked together via O—H⋯Cl hydrogen bonds. In the crystal, all these intermolecular interactions result in a three-dimensional network.

The title compound, C 6 H 8 N 3 + ÁCl À ÁH 2 O, crystallizes with three formula units in the asymmetric unit. The cations are nonplanar with the -C(NH 2 ) 2 groups twisted out of the ring planes. Each pyridine carboximidamidate cation is linked to another cation through N-HÁ Á ÁN hydrogen bonds, to chloride ions by N-HÁ Á ÁCl hydrogen bonds, and to water molecules by N-HÁ Á ÁO hydrogen bonds. Water molecules and chloride ions are also linked together via O-HÁ Á ÁCl hydrogen bonds. In the crystal, all these intermolecular interactions result in a three-dimensional network.

Comment
The pyridinecarboximidamidate derivatives have attracted a great attention due to their very potent antibacterial activities, interesting biological properties and applications in coordination chemistry, but a few samples have been reported (Guo et al., 2005;Góker et al., 2005;Walther et al., 2006;Fan et al., 2009). Here we report the structure of title compound C 6 H 8 N 3 + .Cl -.H 2 O. The title compound is an organic salt and crystallizes with three formula units in the asymmetric unit ( Fig. 1). The molecules are nonplanar with the C(NH 2 ) 2 groups twisted out of the ring planes. The bond lengths and angles exhibit normal values and are comparable with those in the related structures (Guo et al., 2005;Fan et al., 2009).
In the crystal structure, pyridine carboximidamidate cations adopt three different connecting types (Fig. 2). Each pyridine carboximidamidate cation is linked to another cation through N-H···N hydrogen bonds, to chloride ions by N-H···Cl hydrogen bonds, and to water molecules by N-H···O hydrogen bonds. Water molecules and chloride ions are also linked together via O-H···Cl hydrogen bonds (Table 1). In the crystal structure, all these intermolecular interactions result in a three-dimensional network (Fig. 3).

Experimental
To a solution of sodium methoxide (5.15 mmol) in methanol (50 mL) was added 2-cyanopyridine (5.2 g, 4.99 mmol). The mixture was stirred at room temperature for 4 h. Then ammonium chloride (2.9 g, 5.42 mmol) was slowly added to the resulting solution and the mixture was stirred at room temperature for 68 h. The resulting suspension was filtered and the solvent was removed from the filtrate under reduced pressure. Purification by wash with ethyl ether gave 2-amidinopyridine hydrochloride (5.62 g, 92%) as an off-white solid. Colorless crystals were formed after several days.

Refinement
The H atoms were initially found in a difference Fourier map and their coordinates were refined freely. Fig. 1. The molecular structure of the title compound showing 30% probability displacement ellipsoids for non-H atoms.