1,2-Bis(3-phenoxybenzylidene)hydrazine

Molecules of the title compound, C26H20N2O2, reside on crystallographic centres of inversion located at the mid-point of the N—N bond. The benzylidene ring is essentially coplanar with the central hydrazine group, with an interplanar angle of 4.5 (2)°, whereas the phenyl ring is oriented at 34.0 (3)° with respect to the mean plane of the central 1,2-dibenzylidenehydrazine group. In the crystal, C—H⋯π(arene)-ring interactions link molecules about inversion centres.

Molecules of the title compound, C 26 H 20 N 2 O 2 , reside on crystallographic centres of inversion located at the mid-point of the N-N bond. The benzylidene ring is essentially coplanar with the central hydrazine group, with an interplanar angle of 4.5 (2) , whereas the phenyl ring is oriented at 34.0 (3) with respect to the mean plane of the central 1,2-dibenzylidenehydrazine group. In the crystal, C-HÁ Á Á(arene)-ring interactions link molecules about inversion centres.
ASP thanks the University of Mysore for research facilities. JPJ acknowledges the NSF-MRI program (grant No. CHE1039027) for funds to purchase the X-ray diffractometer.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: GG2067).
Schiff bases are known to exhibit biological activity such as antimicrobial (El-masry et al., 2000& Pandeya et al., 1999, antifungal (Singh & Dash, 1988), antitumor (Hodnett & Dunn, 1970;Desai et al., 2001) and as herbicides. Moreover, Schiff bases are used as substrates in the preparation of number of industrial and biologically active compounds via ring closure, cycloaddition and replacement reactions. Schiff bases have also been employed as ligands for complexation of metal ions (Aydogan et al., 2001). On the industrial scale, they have wide range of applications such as dyes and pigments (Taggi et al., 2002). Compounds containing an azine functionality or a diimine linkage have been investigated in terms of their crystallography and coordination chemistry (Xu et al., 1997;Kundu et al., 2005).
The complete molecule of the title compound, C 26 H 20 N 2 O 2 , is generated by the application of a centre of inversion (Fig.   1). The benzylidene ring is essentially coplanar with the central hydrazine group [dihedral angle = 4.5 (2)°] The dihedral angle between the mean plane of the 1,2-bis(benzylidene) hydrazine group and the two parallel phenyl rings is 34.0 (3)°.

Experimental
A mixture of 3-phenoxybenzaldehyde (0.02 mol) and hydrazine hydrate (0.012 mol) was refluxed in 15 ml of absolute alcohol containing 2 drops of sulfuric acid, for about 3 hours. On cooling, the resulting solid was filtered and dried. Single crystals were grown from DMF (dimethylformamide) by the slow evaporation method. Yield: 86%. (m.p.: 404 K).

Refinement
All of the H atoms were placed in their calculated positions and then refined using the riding model with Atom-H lengths of 0.93Å (C-H). Isotropic displacement parameters for these atoms were set to 1.19-1.20 (CH) times U eq of the parent atom.

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 > σ(F 2 ) is used only for calculating Rfactors(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.