Methyl (E)-3,5-dimethoxy-2-{[2-(4-methoxybenzoyl)hydrazin-1-ylidene]methyl}benzoate

In the title compound, C19H20N2O6, the azomethine [C=N = 1.269 (2) Å] double bond adopts an E conformation and the dihedral angle between the planes of the benzene rings is 17.41 (11)°. In the crystal, inversion dimers linked by pairs of N—H⋯O hydrogen bonds generate R 2 2(16) loops. The dimers are connected by C—H⋯O and C—H⋯N hydrogen bonds, forming sheets lying parallel to (100).

In the title compound, C 19 H 20 N 2 O 6 , the azomethine [C N = 1.269 (2) Å ] double bond adopts an E conformation and the dihedral angle between the planes of the benzene rings is 17.41 (11) . In the crystal, inversion dimers linked by pairs of N-HÁ Á ÁO hydrogen bonds generate R 2 2 (16) loops. The dimers are connected by C-HÁ Á ÁO and C-HÁ Á ÁN hydrogen bonds, forming sheets lying parallel to (100).

Experimental
A mixture of 2 mmol of each 4-methoxybenzohydrazide and methyl 2-formyl-3,5-dimethoxybenzoate and catalytical amount of acetic acid was refluxed for 3 h. The progress of the reaction was monitored by TLC. After completion of reaction, the solvent was evaporated by vacuum to afford the crude product (0.610 g, yield 82%), which was recrystallized from methanol solution to yield colourless blocks of the title compound.

Refinement
H atoms on Methyl, phenyl and methine were positioned geometrically with C-H = 0.95 Å (CH 3 ), and 0.93 Å (CH) and constrained to ride on their parent atoms with U iso (H)= 1.5U eq (CH 3 ) 1.2U eq (CH). The H atoms on the nitrogen (N-H= 0.85 (2) Å) was located in difference Fourier maps and refined isotropically. A rotating group model was applied to the methyl groups.  The molecular structure of (I) with displacement ellipsoids drawn at 30% probability level.

Figure 2
The crystal packing of the title compound I. Only hydrogen atoms involved in hydrogen bonding are shown.

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.