(E)-N′-(5-Bromo-2-hydroxybenzylidene)-4-hydroxy-3-methoxybenzohydrazide methanol solvate

In the title compound, C15H13BrN2O4·CH4O, the two benzene rings form a dihedral angle of 3.2 (2)°. An intramolecular O—H⋯N hydrogen bond is observed. In the crystal structure, molecules are linked through O—H⋯O and N—H⋯O hydrogen bonds, forming a two-dimensional network parallel to (10).


Comment
Considerable attention has been focused on hydrazones and their medicinal applications (Hillmer et al., 2010;Zhu et al., 2009;Jimenez-Pulido et al., 2008;Raj et al., 2007;Zhong et al., 2007). The study on the crystal structures of such compounds is of particular interest (Khaledi et al., 2009;Warad et al., 2009;Back et al., 2009;Vijayakumar et al., 2009). We report herein the crystal structure of the title new hydrazone.
The asymmetric unit of the title compound contains a benzohydrazide molecule and a methanol solvate molecule, as shown in Fig. 1. The dihedral angle between the two benzene rings is 3.2 (2)°, indicating they are nearly coplanar. Atom C15 deviates from the C9-C14 benzene ring by 0.188 (2) Å. All the bond lengths are comparable to those observed in related structures (Cao, 2009;Xu et al., 2009;Shafiq et al., 2009).
In the crystal structure, the hydrazone and methanol molecules are linked through O-H···N, O-H···O, and N-H···O hydrogen bonds, to form a two-dimensional network parallel to the (101) (Fig. 2 and Table 1).

Experimental
The title compound was prepared by the condensation reaction of 5-bromosalicylaldehyde (0.05 mol, 10 g) and 4-hydroxy-3-methoxybenzohydrazide (0.05 mol, 9 g) in anhydrous methanol (200 ml) at ambient temperature. Colourless block-shaped single crystals suitable for X-ray structural determination were obtained by slow evaporation of the methanol solution for a period of 5 d.

Refinement
Atom H2 was located in a difference map and refined isotropically, with the N-H distance restrained to 0.90 (1) Å; U iso (H2) was fixed to 0.08 Å 2 . The remaining H atoms were positioned geometrically and constrained to ride on their parent atoms, with C-H distances of 0.93-0.96 Å, O-H distances of 0.82 Å, and with U iso (H) = 1.2U eq (C) and 1.5U eq (C methyl and O).

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.