(E)-2-Chloro-N′-(2-hydroxy-1-naphthylmethylene)benzohydrazide

In the structue of the title compound, C18H13ClN2O2, a new Schiff base, the dihedral angle between the benzene and naphthyl ring system mean planes is 22.5 (2)°. The molecule has an E configuration about the C=N bond, and an intramolecular hydrogen bond involving the hydoxyl substituent on the naphthyl ring and the N′ atom of the hydrazide. The crystal structure is stabilized by intermolecular N—H⋯O hydrogen bonds, forming one-dimensional chains running parallel to the a axis.

In the structue of the title compound, C 18 H 13 ClN 2 O 2 , a new Schiff base, the dihedral angle between the benzene and naphthyl ring system mean planes is 22.5 (2) . The molecule has an E configuration about the C N bond, and an intramolecular hydrogen bond involving the hydoxyl substituent on the naphthyl ring and the N 0 atom of the hydrazide. The crystal structure is stabilized by intermolecular N-HÁ Á ÁO hydrogen bonds, forming one-dimensional chains running parallel to the a axis.   Table 1 Hydrogen-bond geometry (Å , ). Data collection: SMART (Bruker, 2007); cell refinement: SAINT (Bruker, 2007); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.  (Kucukguzel et al., 2006;Khattab, 2005;Karthikeyan et al., 2006;Okabe et al., 1993). Recently, a large number of hydrazone derivatives have been prepared and structurally characterized (Shan et al., 2008;Fun et al., 2008;Yang, 2008;Ma et al., 2008;Diao, Huang et al., 2008;Diao, Zhen et al., 2008;Ejsmont et al., 2008). As part of an ongoing study, we report herein the crystal structure of the title compound, (I).

Structure Reports Online
The molecular structure of compound (I) is shown in Fig. 1. The bond dstances and angles are normal (Allen et al., 1987). The dihedral angle between the phenyl and naphthyl ring mean planes is 22.5 (2)°. The compound displays an E configuration about the C═N bond, and an intramolecular hydrogen bond involving the hydoxyl substituent on the naphthyl ring and the N-atom of the hydrazide ( Table 1). The crystal structure is stabilized by intermolecular N-H···O hydrogen bonds (Table 1), forming one-dimensional chains running parallel to the a axis, Fig. 2.

Experimental
Compound (I) was prepared by dissolving 2-Hydroxy-1-naphthaldehyde (1.0 mmol, 172.3 mg) in methanol (50 ml), then 2-chlorobenzohydrazide (1.0 mmol, 170.2 mg) was added slowly and the mixture kept at reflux with continuous stirring for 3 h. When the solution was cooled to room temperature a colourless crystalline powder appeared. This was filtered off and washed with methanol three times. Recrystallization from absolute methanol yielded block-shaped single crystals suitable for X-ray analysis.

Refinement
H-atom H2 was located in a difference Fourier map and refined isotropically, with the N-H distance restrained to 0.90 (1) Å. The other H-atoms were placed in calculated positions and treated as riding atoms: O-H = 0.82 Å, C-H = 0.93 Å, with U iso (H) = 1.2U eq (C) and 1.5U eq (O). Fig. 1. The molecular structure of compound (I) with 30% probability displacement ellipsoids for non-H atoms.

Special details
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 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.