(E)-N′-(5-Bromo-2-hydroxybenzylidene)-2-methoxybenzohydrazide

In the title compound, C15H13BrN2O3, the molecule adopts an E configuration about the C=N bond and the two benzene rings form a dihedral angle of 20.3 (3)°. In the molecule, there are two intramolecular hydrogen bonds, viz. O—H⋯N and N—H⋯O, involving the hydroxy substituent, the methoxy O atom and the hydrazide NH group and N atom. In the crystal structure, molecules are linked through N—H⋯O hydrogen bonds, forming chains propagating along [010].


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 of 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), and herein we report on the crystal structure of the new title hydrazone.
In the title molecule, illustrated in Fig. 1, the dihedral angle between the two benzene rings is 20.3 (3)°, indicating that the molecule is somewhat twisted. Atom C15 deviates from the plane of the benzene ring (C9-C14) by 0.075 (2) Å. All the bond lengths are comparable to those in similar compounds (Cao, 2009;Xu et al., 2009;Shafiq et al., 2009). In the molecule there are two intramolecular hydrogen bonds; O-H···N involving the hydroxyl group and the adjacent N hydrazide atom, and N-H···O involving the NH group and the adjacent O-atom of the methyl group (Table 1). The molecule has the E configuration about the C═N bond.
In the crystal structure, molecules are linked through N-H···O hydrogen bonds, to form chains running parallel to the b axis (Fig. 2, and Table 1).

Experimental
The title compound was prepared by the condensation reaction of 5-bromosalicylaldehyde (0.05 mol, 10 g) and 2-methoxybenzohydrazide (0.05 mol, 8.3 g) in anhydrous methanol (200 mL) at RT. Colourless block-shaped single crystals, suitable for X-ray structure analysis, were obtained by slow evaporation of the solution over a period of a week.   Fig. 1. The molecular structure of the title compound, with displacement ellipsoids drawn at the 30% probability level. Hydrogen atoms are shown as spheres of arbitrary radius. Hydrogen bonds are shown as dashed lines (see Table 1 for details).  Table 1 for details). Hydrogen atoms not involved in hydrogen bonding have been omitted for clarity.

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 )
x y z U iso */U eq