N′-(5-Bromo-2-hydroxybenzylidene)-3-hydroxybenzohydrazide

The asymmetric unit of the title compound, C14H11BrN2O3, contains two crystallographically independent molecules with slightly different conformations with respect to the aromatic rings; the dihedral angles between the two benzene rings in the two molecules are 55.0 (7) and 16.3 (7)°. In the crystal structure, molecules are linked through intermolecular N—H⋯O, O—H⋯O and O—H⋯N hydrogen bonds, forming chains running along the a axis.

The asymmetric unit of the title compound, C 14 H 11 BrN 2 O 3 , contains two crystallographically independent molecules with slightly different conformations with respect to the aromatic rings; the dihedral angles between the two benzene rings in the two molecules are 55.0 (7) and 16.3 (7) . In the crystal structure, molecules are linked through intermolecular N-HÁ Á ÁO, O-HÁ Á ÁO and O-HÁ Á ÁN hydrogen bonds, forming chains running along the a axis.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: RZ2193).

Y. Nie
Comment Schiff base compounds have been widely investigated due to their easy synthesis, versatile structures and widely applications (Sigman & Jacobsen, 1998;Akitsu & Einaga, 2006;Pradeep, 2005;Butcher et al., 2005). The excellent antibacterial and antitumor properties of such compounds have attracted much interest in recent years (Hodnett & Mooney, 1970;Bahner et al., 1968;Merchant & Chothia, 1970). In order to further investigate the structures of such compounds, a new Schiff base compound is reported in this paper.
The asymmetric unit of the title compound contains two crystallographically independent molecules ( Fig. 1) with slightly different conformation with respect to the aromatic ring planes. The dihedral angles between the two benzene rings in the molecules are 55.0 (7) and 16.3 (7)°, respectively. The molecular conformation is stabilized by intramolecular N-H···O hydrogen bonding interactions (Table 1). In the crystal structure, molecules are linked through intermolecular N-H···O and O-H···O hydrogen bonds (Table 1), forming chains running along the a axis (Fig. 2).

Experimental
The title compound was obtained by stirring of 5-bromosalicylaldehyde (0.1 mmol, 20.1 mg) and 3-hydroxybenzoic acid hydrazide (0.1 mmol, 15.2 mg) in a methanol solution (10 ml) at room temperature. Yellow block-shaped single crystals suitable for X-ray diffraction were formed from the solution after three days.

Refinement
H2 and H4B were located from a difference Fourier map and refined isotropically, with N-H distances restrained to 0.90 (1) Å, and with U iso (H) set to 0.08 Å 2 . Other H atoms were positioned geometrically (C-H = 0.93Å and O-H = 0.82 Å) and refined as riding, with U iso (H) = 1.2U eq (C) and 1.5U eq (O). Fig. 1. The molecular structure of the title compound with 30% probability ellipsoids.  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.