3-Bromo-N′-(3,5-dichloro-2-hydroxybenzylidene)benzohydrazide

The title compound, C14H9BrCl2N2O2, was prepared by the reaction of 3,5-dichloro-2-hydroxybenzaldehyde and 3-bromobenzohydrazide in methanol. The dihedral angle between the two benzene rings is 13.0 (2)°. An intramolecular O—H⋯N hydrogen bond is observed. The molecules are linked into chains along the c axis by intermolecular N—H⋯O hydrogen bonds.

The title compound, C 14 H 9 BrCl 2 N 2 O 2 , was prepared by the reaction of 3,5-dichloro-2-hydroxybenzaldehyde and 3bromobenzohydrazide in methanol. The dihedral angle between the two benzene rings is 13.0 (2) . An intramolecular O-HÁ Á ÁN hydrogen bond is observed. The molecules are linked into chains along the c axis by intermolecular N-HÁ Á ÁO hydrogen bonds.

Comment
Schiff bases are readily synthesized by the reaction of aldehydes with primary amines (Akitsu & Einaga, 2006;Pradeep, 2005;Butcher et al., 2005;Habibi et al., 2007). We have reported a few Schiff bases and their complexes Zhu et al., 2007;Wang et al., 2006). In this paper, the crystal structure of a new Schiff base compound is reported.
The C═N bond length in the title molecule ( Fig.1) is comparable with those observed in other Schiff bases (Yehye et al., 2008;Odabaşoğlu et al., 2007;Yathirajan et al., 2007). All bond lengths are within normal ranges and are comparable to those observed in a related compound (Bao & Wei, 2008). The dihedral angle between C1-C6 and C9-C14 phenyl rings is 13.0 (2)°, indicating that the molecule is non-planar. An intramolecular O1-H1···N1 hydrogen bond is observed.
The crystal structure is stabilized by intermolecular N-H···O hydrogen bonds (Table 1), forming chains along the c axis ( Fig. 2).
Experimental 3,5-Dichloro-2-hydroxybenzaldehyde (1.0 mmol) and 3-bromobenzohydrazide (1.0 mmol) were dissolved in methanol (30 ml). The mixture was stirred at reflux for 10 min to give a clear colourless solution. After keeping this solution in air for 5 d, colourless needle-shaped crystals were formed.

Refinement
Atom H2 was located in a difference Fourier map and refined isotropically, with the N-H distance restrained to 0.90 (1) Å.
All other H atoms were positioned geometrically (C-H = 0.93 Å and O-H = 0.82 Å) and refined as riding, with U iso (H) values set at 1.2U eq (C) and 1.5U eq (O).

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 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.