N′-(3,5-Dibromo-2-hydroxybenzylidene)-2-methylbenzohydrazide

The asymmetric unit of the title compound, C15H12Br2N2O2, contains two independent molecules in which the dihedral angles between the benzene rings are 49.5 (7) and 66.4 (7)°. Intramolecular O—H⋯N hydrogen bonds generate S(6) ring motifs in each molecule. In the crystal, molecules are linked through intermolecular N—H⋯O hydrogen bonds, forming chains along the b axis.


Comment
Hydrazone compounds have received much attention in biological and structural chemistry in the last few years (Rasras et al., 2010;Pyta et al., 2010;Angelusiu et al., 2010;Fun et al., 2008;Singh & Singh, 2010;Ahmad et al., 2010). In the present paper, the author reports the crystal structure of the new title hydrazone compound (Fig. 1).
Experimental 3,5-Dibromo-2-hydroxybenzaldehyde (0.1 mmol, 28.0 mg) and 2-methylbenzohydrazide (0.1 mmol, 15.0 mg) were dissolved in methanol (20 ml). The mixture was stirred at reflux for 10 min to give a clear colourless solution. Colourless block-shaped crystals of the compound were formed by slow evaporation of the solvent over several days.

Refinement
The amino H atoms were located in a difference Fourier map and refined isotropically, with the N-H distances restrained to 0.90 (1) Å [U iso (H) = 0.08 Å 2 ]. Other H atoms were constrained to ideal geometries and refined as riding, with Csp 2 -H = 0.93 Å, C(methyl)-H = 0.96 Å, and O-H = 0.82 Å; U iso (H) = 1.2U eq (C) and 1.5U eq (O and C methyl ). Fig. 1. The molecular structure of the compound, showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 30% probability level. Hydrogen atoms are shown as spheres of arbitrary radius.

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.
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )