3-Amino-1-methylpyrazin-1-ium chloride

In the cation of the title compound, C5H8N3 +·Cl−, the C—N(H2) bond distance [1.348 (3) Å] is at the lower end of the range for aryl amines. In the crystal structure, cations and anions are linked via N—H⋯Cl hydrogen bonds, forming one-dimensional chains along [100].

In the cation of the title compound, C 5 H 8 N 3 + ÁCl À , the C-N(H 2 ) bond distance [1.348 (3) Å ] is at the lower end of the range for aryl amines. In the crystal structure, cations and anions are linked via N-HÁ Á ÁCl hydrogen bonds, forming one-dimensional chains along [100].

Comment
The title chloride compound, (I), was recovered from the ion exchange (Dowex 1-X8 ion exchange resin saturated with Clanions) of the iodide precursor of N-methyl-3-aminopyrazinium iodide (Foucher et al., 1993). The proximity of the amine group to one of the diazine N atoms makes it an ideal chelating ligand to metals and geometrically suggests the possibility for amine-imine tautomerism. We have investigated the possibility that a smaller counter ion might induce a preference for the imine tautomer in these salts.

Experimental
General procedures for the synthesis of this type of compound are given by Goto et al. (1968) and Kazheva et al. (2006).
The aqueous fractions containing the crude title compound were collected and brought to dryness. Crystals suitable for X-ray diffraction were isolated from the recrystallization of the crude product from boiling ethanol. Yield 0.11 g, 78%.
Characterization by NMR agreed with previous literature (Foucher et al., 1993).

Refinement
H atoms bonded to C atoms were placed in calculated positions with C-H = 0.95 and 0.98 Å, and included in a riding-model approximation with U iso (H) = 1.2U eq (C) or 1.5U eq (C methyl ). H atoms bonded to the amine group N atom were refined independently with isotropic displacement parameters.
supplementary materials sup-2 Figures   Fig. 1. The asymmetric unit of (I) with displacement ellipsoids drawn at the 30% probability level. The dashed line indicates a hydrogen bond.