2-Amino-5-chloropyridinium nitrate

The title structure, C5H6ClN2 +·NO3 −, is held together by extensive hydrogen bonding between the NO3 − ions and 2-amino-5-chloropyridinium H atoms. The cation–anion N—H⋯O hydrogen bonds link the ions into a zigzag- chain which develops parallel to the b axis. The structure may be compared with that of the related 2-amino-5-cyanopyridinium nitrate.

The title structure, C 5 H 6 ClN 2 + ÁNO 3 À , is held together by extensive hydrogen bonding between the NO 3 À ions and 2amino-5-chloropyridinium H atoms. The cation-anion N-HÁ Á ÁO hydrogen bonds link the ions into a zigzag-chain which develops parallel to the b axis. The structure may be compared with that of the related 2-amino-5-cyanopyridinium nitrate.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: DN2495).

Comment
Derivatives of the aminoacid are of considerable interest in biological activities and there has been an increased interest in the chemistry of amine derivatives because of the construction of novel metal-organic frameworks (Manzur et al., 2007;Ismayilov et al., 2007;Austria et al., 2007). The crystal structures of 2-amino-5-chloropyridine (Pourayoubi et al., 2007) and their 2-Amino-5-cyanopyridinium nitrate (Dai, 2008) and 2-Aminopyridinium nitrate (Rademeyer, 2007) have been reported in literature. In this paper, we present the X-ray single-crystal structure of 2-Amino-5-chloropyridinium nitrate (I).
The title compound (I) contains an organic cation and a (NO 3 )anion (Fig1). The cation is roughly planar with the largest deviation from the mean plane being 0.0553 (9)Å. The NO3 anion is slightly twisted with respect to the pyridinium ring making a dihedral angle of 17.2 (1)°T he monoprotonated chloropyridinium cation (C 5 H 6 ClN 2 ) + and the nitrate anion (NO 3 )are linked by N-H···O which forms a zig-zag like chain parallel to the b axis (Table 1, Fig 2).
The crystal structure of 2-Amino-5-cyanopyridinium nitrate (II) (Dai, 2008) was recently published. The title compound (I) and this related compound (II) are isostructural. In both molecules, the asymmetric unit contains an organic cation 2-Amino-5-Xpyridinium (X: chloride (I), C≡N nitrile (II)) and a nitrate anion. They have the same space group (P2 1 /c) and they are characterized by two-dimensional hydrogen-bonded networks.
The distances and angles of the present 2-amino-5-chloropyridinium nitrate molecule are consistent with the values reported in the literature of 2-aminopyridinium nitrate and 4-aminopyridinium nitrate molecules (Rademeyer 2005;2007).
Experimental 2-Amino-5-chloropridine was dissolved in the solution of methanol and nitric acid (0.5 ml). Yellow crystals were obtained after a month on slow evaporation.

Refinement
All H atoms attached to C atoms and N atoms were fixed geometrically and treated as riding with C-H = 0.93Å and N-H = 0.86 Å with U iso (H) = 1.2U eq (C or N).
supplementary materials sup-2 Figures   Fig. 1. Representation of the asymetric unit of 2-amino-5-chloropyridinium nitrate with the atom labeling scheme. Ellipsoids are drawn at the 30% probability level. H atoms are represented as small spheres of arbitrary radii. Hydrogen bonds are shown as dashed lines.

Special details
Experimental. Number of psi-scan sets used was 3 Theta correction was applied. Averaged transmission function was used. No Fourier smoothing was applied (North et al., 1968).
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 > σ(F 2 ) is used only for calculating Rfactors(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.