2-[(E)-2-(4-Methoxyphenyl)ethenyl]-1-methylpyridinium iodide

In the title molecular salt, C16H10NO+·I−, the dihedral angle between the pyridinium and benzene rings is 6.61 (8)°. In the crystal, the cation is linked to the anion by a C—H⋯I interaction arising from the activated aromatic C atom adjacent to the N+ cation.

In the title molecular salt, C 16 H 10 NO + ÁI À , the dihedral angle between the pyridinium and benzene rings is 6.61 (8) . In the crystal, the cation is linked to the anion by a C-HÁ Á ÁI interaction arising from the activated aromatic C atom adjacent to the N + cation.

Comment
In recent years, the design of new organic nonlinear optical (NLO) materials have been studied (e.g. Jagannathan et al., 2007). As part of our stuies in this area, the title pyridinium derivative compound was synthesized,. It crystallizes in the centrosymmetric Pī triclinic space group, so it does not exhibit second-order nonlinear optical properties (Williams, 1984).
The cation is essentially planar and exist in E configuration. The dihedral angle between the pyridinium and benzene rings is 6.16 (8)°. Bond lengths and angles are comparable with those for closely related structure (Chantrapromma et al., 2010). In the crystal, the cation is linked to the anion by a C-H···I interaction (Table 1).

Experimental
The title compound was prepared by mixing 1:1 molar ratio of solutions of 1,2-dimethylpyridinium iodide (7.052 g, 30 mmol), 4-methoxy benzaldehyde (3.7 ml, 30 mmol) and piperidine (5 drops) in hot methanol (20 ml). The resulting mixture was refluxed at 60°C for 8 h to give yellowish crystalline product, which was filtered off and washed with diethyl ether and dried. Yellow needle-shaped single crystals of the title compound suitable for X-ray structure determination were obtained by recrystallization (three times) from methanol-acetonitrile (1:1) mixture by slow evaporation of the solvent at ambient temperature over several days (m.p. 514-516 K).

Computing details
Data collection: APEX2 (Bruker, 2004); cell refinement: SAINT (Bruker, 2004); data reduction: SAINT (Bruker, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008  ORTEP of the molecule with atoms represented as 30% probability ellipsoids. where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max = 0.001 Δρ max = 0.31 e Å −3 Δρ min = −0.59 e Å −3 Extinction correction: SHELXL97 (Sheldrick, 2008), Fc * =kFc[1+0.001xFc 2 λ 3 /sin(2θ)] -1/4 Extinction coefficient: 0.0288 (14) 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 matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s 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 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.