4-Cyanopyridinium chloride

In the crystal structure of the title salt, C6H5N2 +·Cl−, the pyridinium cation links to the Cl− anion via an N—H⋯Cl hydrogen bond. Weak C—H⋯Cl interactions also occur.

In the crystal structure of the title salt, C 6 H 5 N 2 + ÁCl À , the pyridinium cation links to the Cl À anion via an N-HÁ Á ÁCl hydrogen bond. Weak C-HÁ Á ÁCl interactions also occur.

Comment
Simple organic salts containing strong intrermolecular H-bonds have attracted an attention as materials which display ferroelectric-paraelectric phase transitions (Chen et al., 2000;Liu et al., 1999;Zhao et al., 2003). With the purpose of obtaining phase transition crystals of organic salts, various organic molecules have been studied and a series of new materials have been elaborated (Dai & Chen, 2011;Xu et al., 2011;Zheng, 2011). Herewith we present the synthesis and crystal structure of the title compound.

Experimental
The HCl (5 mL), isonicotinonitrile (20 mmol) and ethanol (50 mL) were added into a 100 mL flask. The mixture was stirred at 333 K for 2 h, and then the precipitate was filtrated out. Colourless crystals suitable for X-ray diffraction were obtained by slow evaporation of the solution.

Refinement
All the H atoms were situated into the idealized positions and treated as riding with C-H = 0.95 and N-H = 0.90 Å, U iso (H) = 1.2U eq (C,N).

4-Cyanopyridinium chloride
Crystal data C 6 H 5 N 2 + ·Cl − M r = 140.57 Triclinic, P1 Hall symbol: -P 1 a = 6.6166 (2)  where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.97 e Å −3 Δρ min = −0.62 e Å −3 Special details 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 > 2sigma(F 2 ) is used only for calculating R-factors(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.