N′-(5-Chloro-2-hydroxybenzylidene)nicotinohydrazide

There are two independent Schiff base molecules in the asymmetric unit of the title compound, C13H10ClN3O2. The dihedral angles between the benzene and pyridine rings are 12.8 (2) and 1.9 (2)° in the two molecules. Intramolecular O—H⋯N hydrogen bonds are observed. Molecules are linked into centrosymmetric R 4 4(26) motifs by N—H⋯O and N—H⋯N interactions.

The author acknowledges Zaozhuang University for funding this study.

Experimental
All the starting materials were obtained with AR grade from Lancaster. 5-Chloro-2-hydroxybenzaldehyde (1.0 mmol, 157.1 mg) and nicotinohydrazide (1.0 mmol, 137.1 mg) were refluxed in a 30 ml methanol solution for 30 min to give a clear yellow solution. Yellow block-shaped single crystals of the compound were obtained by slow evaporation of the solution for five days at room temperature.

Refinement
H2 and H5 were located from a difference Fourier map and refined isotropically, with the N-H distance restrained to 0.90 (1) Å, and with U iso restrained to 0.08 Å 2 . Other H atoms were constrained to ideal geometries, with d(C-H) = 0.93 Å, d(O-H) = 0.82 Å, and with U iso (H) = 1.2U eq (C) and 1.5U eq (O).  Cell parameters from 2236 reflections a = 9.792 (2)

Data collection
Bruker SMART CCD area-detector diffractometer 5342 independent reflections

Special details
Geometry. All e.s. 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 Rfactors(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.