N′-(Diphenylmethylene)-2-hydroxybenzohydrazide

In the title compound, C20H16N2O2, intramolecular N—H⋯O and intermolecular O—H⋯O hydrogen bonds are found. The intermolecular hydrogen bonds link the molecules into an infinite chain along the c axis. The dihedral angles between the aromatic rings are 16.9 (3), 80.8 (3) and 64.6 (3)°

In the title compound, C 20 H 16 N 2 O 2 , intramolecular N-HÁ Á ÁO and intermolecular O-HÁ Á ÁO hydrogen bonds are found. The intermolecular hydrogen bonds link the molecules into an infinite chain along the c axis. The dihedral angles between the aromatic rings are 16.9 (3), 80.8 (3) and 64.6 (3)

Comment
The chemistry of 2-hydroxybenzohydrazide and its derivatives are studied because of their multiply coordination environment (Chang, 2008;Huo et al., 2004). They represent a class of highly useful compounds in which the presence of O and N atom renders various hydrogen bonding motifs leading to the formation of versatile architecture in the crystal lattice. As the continue of the aspect, we study the reaction of benzophenone and 2-hydroxybenzohydrazide in the state of refluxing in ethanol.

Experimental
Benzophenone and 2-hydroxybenzohydrazide were added to the solvent of ethanol and the mixture was stirred for 4 h at 323 K. After cooling down to the room temperature, the solution was filtered. The solvent was removed from the filtrate under vacuum and the solid residue was recrystallized from ether; colourless crystals suitable for X-ray diffraction study were obtained. Yield, 79%. m.p. 463 K. Analysis, calculated for C 20 H 16 N 2 O 2 : C 79.19, H 5.65, N 4.62; found: C 79.36, H 5.43, N 4.35%. The elemental analyses were performed with a Perkine Elemer PE2400II instrument.

Refinement
The all H atoms were placed in idealized positions and constrained to ride on their parent atoms, with distances: N-H = 0.86 Å and O-H = 0.82 Å, C-H = 0.93 Å. The U iso (H) values were set at 1.2U eq (parent C, N) and 1.5U eq (O).

Special details
Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'s 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 > 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.