4-Chloro-N′-(3,5-dibromo-2-hydroxybenzylidene)benzohydrazide

The asymmetric unit of the title compound, C14H9Br2ClN2O2, contains two independent molecules. Both molecules adopt an E configuration about the C=N bond. The dihedral angles between the benzene rings are 30.0 (2) and 51.6 (2)° in the two molecules. In the crystal, molecules are linked through N—H⋯O hydrogen bonds, forming chains along the b axis. In addition, there is an intramolecular O—H⋯N hydrogen bond in each molecule.

The asymmetric unit of the title compound, C 14 H 9 Br 2 ClN 2 O 2 , contains two independent molecules. Both molecules adopt an E configuration about the C N bond. The dihedral angles between the benzene rings are 30.0 (2) and 51.6 (2) in the two molecules. In the crystal, molecules are linked through N-HÁ Á ÁO hydrogen bonds, forming chains along the b axis. In addition, there is an intramolecular O-HÁ Á ÁN hydrogen bond in each molecule.   Table 1 Hydrogen-bond geometry (Å , ). Financial support from Qiqihar University is acknowledged.

Related literature
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: LH5429).
The asymmetric unit of the title hydrazone compound contains two independent molecules, as shown in Fig. 1. Each of the molecules of the compound adopts an E configuration about the C═N double bond. The dihedral angles between the two substituted benzene rings are 30.0 (2)° [C1-C6/C9-C14] and 51.6 (2)° [C15-C20/C23-C28]. In the crystal, molecules are linked through intermolecular N-H···O hydrogen bonds (Table 1), forming chains along the b axis (Fig. 2). In addition, there is an intramolecular O-H···N hydrogen bond in each molecule.

Experimental
3,5-Dibromo-2-hydroxybenzaldehyde (0.280 g, 1 mmol) and 4-chlorobenzohydrazide (0.171 g, 1 mmol) were mixed in 50 ml methanol. The mixture was stirred and refluxed for 30 min and cooled to room temperature to give a colorless solution. Colorless block-shaped single crystals were obtained on slow evaporation of the solution in air.

Refinement
H2 and H4 were located in a difference Fourier map and refined with the N-H distances restrained to 0.90 (1) Å. The remaining H atoms were positioned geometrically, with C-H = 0.93 Å, O-H = 0.82 Å, and with U iso (H) = 1.2U eq (C) and 1.5U eq (O).     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.