2-(Benzenesulfonamido)pyridinium nitrate

In the title compound, C11H11N2O2S+·NO3 −, the dihedral angle between the benzene and pyridinium rings is 87.59 (8)°. An intramolecular C—H⋯O interaction occurs in the cation. In the crystal structure, ion pairs occur, being linked by two strong N—H⋯O interactions, forming R 2 2(8) loops. The packing is further stabilized by weak C—H⋯O interactions.

In the title compound, C 11 H 11 N 2 O 2 S + ÁNO 3 À , the dihedral angle between the benzene and pyridinium rings is 87.59 (8) . An intramolecular C-HÁ Á ÁO interaction occurs in the cation. In the crystal structure, ion pairs occur, being linked by two strong N-HÁ Á ÁO interactions, forming R 2 2 (8) loops. The packing is further stabilized by weak C-HÁ Á ÁO interactions.

Comment
Organic pyridinium salts have been widely used as guests for construction of supramolecular complexes. As part of our ongoing studies of host-guest chemistry involving the pyridinium salts (Li et al., 2007;, the structure of the title compound was determined by X-ray diffraction. For related structures, see: Li et al. (2008a,b).
The title compound, (I), consists of a pyridinium cation and a nitrate anion (Fig. 1). In the cation, the C-N distance [1.378 (2) Å] is short enough to display significant double-bond character (typical C=N = 1.34-1.38 Å), despite the presence of the strong electron-withdrawing sulfonyl group. This could be attributed to the ortho N + atom in the pyridinium ring.
The benzene ring constructs an angle of 87.59 (8)° with the pyridinium ring.

Experimental
The title compound was prepared according to the reported literature (Li, Yang et al. 2008). Colourless blocks of (I) were obtained by evaporation of a nitric acid solution of the sulfonamide.

Refinement
The H atoms bound to C were positioned geometrically (C-H = 0.95Å) and refined as riding with U iso (H) = 1.2 U eq (C).
The N-H hydrogen atoms were refined with their isotropic displacement parameters, and N-H distances are restrained to 0.86 (2) and 0.91 (2) Å, respectively. Fig. 1. View of the molecular structure of (I) with displacement ellipsoids drawn at the 50% probability level and H atoms are shown as small spheres of arbitrary radius. Dashed lines indicates H-bonding. 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.