1-Methyl-4-(4-methylstyryl)pyridinium 4-methylbenzenesulfonate

In the title salt, C15H16N+·C7H7O3S−, the dihedral angle between the pyridine and benzene rings of the cation is 5.98 (18)°. In the crystal, adjacent anions and cations are linked by weak non-classical C—H⋯O hydrogen bonds and π–π interactions, with a centroid–centroid distance of 3.749 (2) Å.


Comment
In continuation of our studies of molecular compounds with non linear optical properties which are known to exhibit applications in optoelectronic and photonic devices (Bosshard et al., 1995;Nalwa & Miyata, 1997), we determined the crystal structure of the title compound I.
The asymmetric unit of I, (Fig. 1), contains C 15 H 16 N + cation and C 7 H 7 O 3 Sanion. The geometric parameters of the title compound are comparable with the similar reported structures: Murugavel et al., 2009;Sivakumar et al., 2012;Okada et al., 1990. The cation is planar -torsion angle about the double bond between the two rings in the cation, C1-C6═C7-C8 is 178.2 (3)°. The benzene ring in the anion is almost planar, with the maximum deviation of 0.003 (3)Å.

Experimental
The title compound was synthesized by the condensation of 4-methyl-N-methyl pyridinium tosylate, which was prepared from 4-picoline (4.65 g, 5 mmol) and methyl p-toluenesulfonate (9.31 g, 5 mmol), and 4-methylbenzaldehyde (6 g, 5 mmol) in the presence of piperidine. The single crystals were grown by slow evaporation method in room temperature.

Refinement
The H atoms were positioned geometrically and refined using riding model with C-H = 0.93Å and U iso (H) = 1.2U eq (C) for aromatic H, C-H = 0.96Å and U iso (H) = 1.5U eq (C) for methyl H. The components of the anisotropic displacement parameters for C7 and C8 were restrained to be equal within an effective deviation of 0.001 using DELU instruction in SHELXL (Sheldrick, 2008).  The molecular structure of I with atom labels. Displacement ellipsoids are drawn at 30% probability level. H atoms are presented as a small spheres of arbitrary radius.

Figure 2
The packing of I, viewed down b axis. Intermolecular hydrogen bonds are shown as dashed lines. H atoms not involved in hydrogen bonding have been omitted for clarity. where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.57 e Å −3 Δρ min = −0.37 e Å −3 Special details Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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 > 2σ(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.