2-[N-(4-{4-[(2-Hydroxy-5-methoxybenzylidene)amino]benzyl}phenyl)carboximidoyl]-4-methoxyphenol

In the title Schiff base, C29H26N2O4, the complete molecule is generated by a crystallographic twofold axis and is V-shaped. The planes of the benzene rings of the central diphenylmethane unit make a dihedral angle of 78.11 (4)° while adjacent benzene and 5-methoxysalicylidene rings are twisted with respect to each other by a dihedral angle of 11.84 (8)°. The Schiff base is in the enol–imino form and an intramolecular O—H⋯N hydrogen bond is observed.

In the title Schiff base, C 29 H 26 N 2 O 4 , the complete molecule is generated by a crystallographic twofold axis and is V-shaped. The planes of the benzene rings of the central diphenylmethane unit make a dihedral angle of 78.11 (4) while adjacent benzene and 5-methoxysalicylidene rings are twisted with respect to each other by a dihedral angle of 11.84 (8) . The Schiff base is in the enol-imino form and an intramolecular O-HÁ Á ÁN hydrogen bond is observed.

Experimental
The molecule of the title compound is arranged around the two fold axis at 1/2, y, 3/4 of the unit cell and methylene carbon C14 coinciding with it. The molecule is V-shaped and has a dihedral angle of 78.11 (4)° between the two inner phenyl rings. The phenyl and the 5-methoxysalicylidene rings are slightly twisted with respect to each other by a dihedral angle of 11.84 (8)°. There are two symmetry equivalent intramolecular O-H···N hydrogen bonds. The bond lengths and bond angles within the molecule agree well with those of the closely related compounds C 27 H 22 N 2 O 2 (CCDC refcode YEFWUC; Birkedal & Pattison, 2006) and C 26 H 20 N 2 O 3 (Shahverdizadeh & Tiekink, 2011). In the unit cell, the molecules are tightly stacked one above the other along the short b-axis (b = 4.5993 (3) Å) and are held together in this direction by slipped π-π stacking interactions between the phenyl rings and the iminomethylidene groups. The architecture and space group of the title structure is identical with CCDC YEFWUC.

Refinement
All H atoms attached to C were fixed geometrically and treated as riding with C-H = 0.96 Å (methyl), 0.92 Å (methylene) or 0.93 Å (aromatic) with U iso (H) = 1.2U eq (C) or U iso (H) = 1.5U eq (methyl). The H atom of the hydroxyl group was initially refined using a soft restraint O-H = 0.89 (1) Å and U iso (H) = 1.2U eq (O). Then, in the last cycles of refinement, it was treated as riding on its parent O atom.

Computing details
Data collection: EXPOSE (Stoe & Cie, 1995); cell refinement: X-RED (Stoe & Cie, 1995); data reduction: X-RED (Stoe & Cie, 1995); program(s) used to solve structure: SIR92 (Altomare et al., 1993); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: publCIF (Westrip, 2010). 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq O1 0.37635 (