1-(4-Methylbenzylideneamino)pyridinium iodide

The title compound, C13H13N2 +·I−, is a derivative of 1-aminopyridinium iodide. The pyridine and benzene rings are oriented at a dihedral angle of 45.78 (3)°. In the crystal structure, weak intermolecular C—H⋯I hydrogen bonds link the molecules.

The title compound, C 13 H 13 N 2 + ÁI À , is a derivative of 1aminopyridinium iodide. The pyridine and benzene rings are oriented at a dihedral angle of 45.78 (3) . In the crystal structure, weak intermolecular C-HÁ Á ÁI hydrogen bonds link the molecules.

Related literature
For bond-length data, see: Allen et al. (1987).
In the molecule of the title compound ( Fig. 1), the bond lengths (Allen et al., 1987) and angles are within normal ranges.
In the crystal structure, weak intermolecular C-H···I hydrogen bonds (Table 1) link the molecules (Fig. 2), in which they may be effective in the stabilization of the structure.

Experimental
For the preparation of the title compound, 1-aminopyridinium iodide (22.2 g, 0.10 mol) was dissolved in ethanol (20 ml). 4-Methylbenzaldehyde (32.4 g, 0.1 mol) was added with stirring, and then the mixture was heated at reflux for 5 h. Upon cooling to room temperature, a precipitate formed, which was collected by filtration and washed with cold ethanol (2 x 10 ml) to obtain a yellow solid (yield; 38 g, 70%). Crystals suitable for X-ray analysis were obtained by slow evaporation of an ethanol solution.

Refinement
H atoms were positioned geometrically, with C-H = 0.93 and 0.96 Å for aromatic and methyl H, respectively, and constrained to ride on their parent atoms with U iso (H) = xU eq (C), where x = 1.5 for methyl H and x = 1.2 for aromatic H atoms. Fig. 1. The molecular structure of the title molecule, with the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level

Special details
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance mat- 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.