2-(2H-Tetrazol-5-yl)pyridinium nitrate

In the cation of the title compound, C6H6N5 +·NO3 −, the dihedral angle between the pyridinium and tetrazole rings is 8.2 (2)°. The constituent ions of the compound are linked via N—H⋯O hydrogen bonds, forming helical chains running along the b axis. C—H⋯N and C—H⋯O hydrogen bonds are also observed.

In the cation of the title compound, C 6 H 6 N 5 + ÁNO 3 À , the dihedral angle between the pyridinium and tetrazole rings is 8.2 (2) . The constituent ions of the compound are linked via N-HÁ Á ÁO hydrogen bonds, forming helical chains running along the b axis. C-HÁ Á ÁN and C-HÁ Á ÁO hydrogen bonds are also observed.

Comment
In the past few years, more and more people have focused on the chemistry of tetrazole derivatives because of their multiple coordination modes as ligands to metal ions and for the construction of novel metal-organic frameworks Wang, et al. 2005;Xiong, et al. 2002;Wen 2008). We report here the crystal structure of the title compound, 2-(2H-tetrazol-5-yl)pyridinium nitrate.
In the title compound ( Fig.1), the N atom (N1) of the pyridine ring is protonated. The pyridine and tetrazole rings are nearly coplanar and are twisted from each other by a dihedral angle of 8.2 (2)°. The geometric parameters of the tetrazole ring are comparable to those observed in related structures (Wang et al. 2005;Dai & Fu 2008).
The crystal packing is stabilized by N-H···O hydrogen bonds which link the molecules into a helical chain running along the b axis (Table 1 and Fig.2). In addition, C-H···N and C-H···O hydrogen bonds are observed.

Experimental
Picolinonitrile (30 mmol), NaN 3 (45 mmol), NH 4 Cl (33 mmol) and DMF (50 ml) were added in a flask under nitrogen atmosphere. The mixture stirred at 110°C for 20 h. The resulting solution was then poured into ice-water (100 ml), and a white solid was obtained after adding HCl (6 M) at pH = 6. The precipitate was filtered and washed with distilled water.
Colourless block-shaped crystals suitable for X-ray analysis were obtained from the crude product by slow evaporation of an ethanol-HNO 3 (50:1 v/v) solution.