2-[1-({2-[1-(2-Hydroxy-5-{[methyl(phenyl)amino]methyl}phenyl)ethylideneamino]ethyl}imino)ethyl]-4-{[methyl(phenyl)amino]methyl}phenol

Molecules of the title compound, C34H38N4O2, lie across crystallographic inversion centres. The crystal packing can be described by alternating zigzag chains along the c axis in which the molecules are linked by van der Waals interactions. There is an intramolecular O—H⋯N hydrogen bond and the two benzene rings in the asymmetric unit make a dihedral angle of 79.81 (6)°.

Molecules of the title compound, C 34 H 38 N 4 O 2 , lie across crystallographic inversion centres. The crystal packing can be described by alternating zigzag chains along the c axis in which the molecules are linked by van der Waals interactions. There is an intramolecular O-HÁ Á ÁN hydrogen bond and the two benzene rings in the asymmetric unit make a dihedral angle of 79.81 (6) .
We report here the synthesis of title compound and its crystal structure. The molecular geometry of (I), and the atomic numbering used, is illustrated in Fig. 1. The asymmetric unit of the title compound, (I), consists of one-half of the molecule, with the other half generated by a crystallographic inversion centre. The two phenyl rings make a dihedral angle of 79.81 (6)°. The crystal packing in the title structure can be described by alterning zigzag chains along the c axis ( Fig. 2). There is an intramolecular O-H···N hydrogen bonding (Table 1, Fig. 2) and the packing is stabilized by Van der Waals interactions and weak π···π stackings (minimal distance: Cg1··· Cg2 i = 5.2048 (15) Å; Cg1 and Cg2 are the centroids of rings C4-C9 and C12-C17, respectively; symmetry code: (i) -1 + x, y, z). These interactions link the molecules within the chains and also link the layers together reinforcing the cohesion of the structure.

Experimental
The title compound is a tetradentate Schiff base ligand (H2L). It was synthesized by dissolving 7 g (27.45 mmol) of 5-(N,N-methylphenylaminomethyl)-2-hydroxyacetophenone in 30 ml of absolute ethanol and placed in a three-necked flask of 100 ml, surmounted by a condenser. To this solution, 0.823 g (13.72 mmol) of 1,2-diaminoethane were placed in 20 ml of the same solvent (absolute EtOH) and slowly added. This mixture was heated to 50°C under stirring and nitrogen atmosphere for two hours. A precipitate obtained was filtered, washed with diethyl ether and then dried under reduced pressure to yield 4.26 g (58%) of the expected compound. Its melting point was found to be 156 °C and a suitable single-crystal was formed by slow evaporation from a solvent mixture EtOH/CH 2 Cl 2 (8/2, v/v).

Refinement
The remaining H atoms were localized on Fourier maps but introduced in calculated positions and treated as riding on their parent atoms (C and O) with C-H = 0.96 Å (methyl), 0.97 Å (methylene) or 0.93 Å (aromatic) and O-H = 0.82 Å with U iso (H) = 1.2U eq (C aromatic and C methylene ) or U iso (H) = 1.5U eq (C methyl and O hydroxy ).

Figure 1
The molecular geometry of (I) with displacement ellipsoids drawn at the 50% probability level. H atoms are represented as small spheres of arbitrary radii. Only the non-H atoms of the asymmetric unit are labelled.

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