3-{[(E)-(2-Hydroxynaphthalen-1-yl)methylidene]amino}pyridinium perchlorate

In the title Schiff base salt, C16H13N2O+·ClO4 −, the pyridine ring and the naphthalene ring system are approximately co-planar [making a dihedral angle of 6.05 (12)°] and an intramolecular O—H⋯N hydrogen bond occurs between the hydroxyl and imino groups. In the crystal, the cations and anions are linked by N—H⋯O and weak C—H⋯O hydrogen bonds, forming the supramolecular layers parallel to (100). The crystal studied was an inversion twin refined with minor component = 0.43 (13).

In the title Schiff base salt, C 16 H 13 N 2 O + ÁClO 4 À , the pyridine ring and the naphthalene ring system are approximately coplanar [making a dihedral angle of 6.05 (12) ] and an intramolecular O-HÁ Á ÁN hydrogen bond occurs between the hydroxyl and imino groups. In the crystal, the cations and anions are linked by N-HÁ Á ÁO and weak C-HÁ Á ÁO hydrogen bonds, forming the supramolecular layers parallel to (100). The crystal studied was an inversion twin refined with minor component = 0.43 (13).
Herein we report the synthesis and crystal structure of 3-{[E)-(2-Hydroxynaphthalen-1-yl)methylidene]amino}pyridinium perchlorate, (I). The molecular structure of (I), and the atomic numbering used, is illustrated in Fig. 1. The asymmetric unit of (I) consists of one protoned N-(3-pyridil)-2-oxo-1-naphthylidenemethylamine cation and one perchlorate anion. All bond distances and angles are within the ranges of accepted values(CSD, Allen, 2002). The cation is co-planar with r.m.s. deviation all non-H atoms, for cation, are essentially co-planar with a maximum deviation of -0.1158 (39) Å for N5 [r.m.s. deviation: 0.0590 Å]. The molecule is twisted with the dihedral angle between the benzene and the naphthyl ring mean planes being 6.05 (12) °.
In the crystal structure, cationic and anionic layers alternate along the c axis and are linked by intermolecular N-H···O and weak C-H···O hydrogen bonds (Table 1, Fig.2) resulting in a two-dimensional network parallel to (100)plane ( Fig.3). Also, we observe an intramolecular O-H···N hydrogen bond, involving the naphthalene hydroxyl substituent and the pyridine N-atom ( Fig.1, Table 1).

Experimental
The title compound, (I), was prepared by refluxing a mixture of a solution containing (0.1 mmol) of 2-hydroxy-1naphthaldehyde and (0.1 mmol) of 3-aminopyridine in presence of perchloric acid in 20 ml methanol. The reaction mixture was stirred for 1 h under reflux. Microcrystals of (I) were obtained by allowing the clear solution to stand overnight. The powder product was dissolved and recrystallized from DMSO solution. Some red crystals were carefully isolated under polarizing microscope for analysis by X-ray diffraction.

Refinement
All non-H atoms were refined with anisotropic atomic displacement parameters. The remaining H atoms were localized

Figure 1
The molecule structure of the title compound with the atomic labelling scheme (Farrugia, 2012  Hydrogen bond connections as dashed line in the same layers parallel to (100) plane between cations and anions (Brandenburg & Berndt, 2001).

Figure 3
A diagram of the layered crystal packing in (I), viewed down the b axis showing hydrogen bond as dashed line (Brandenburg & Berndt, 2001)  where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.26 e Å −3 Δρ min = −0.28 e Å −3 Absolute structure: Flack (1983), 1362 Friedel pairs Absolute structure parameter: 0.43 (13) 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.