N′-(4-Fluorobenzylidene)-3,4,5-trimethoxybenzohydrazide

The title compound, C17H17FN2O4, is of interest due to its potential pharmaceutical and agrochemical activity. All three methoxy groups are twisted with respect to the attached aromatic ring [C—C—O—C torsion angles = 10.43 (18), 97.38 (14), −19.34 (17)°] and the phenyl ring makes a dihedral angle of 40.6 (2)° with the plane through the remaining atoms in the molecule. Intermolecular N—H⋯O hydrogen bonds link the molecules into chains running along the c axis.

The title compound, C 17 H 17 FN 2 O 4 , is of interest due to its potential pharmaceutical and agrochemical activity. All three methoxy groups are twisted with respect to the attached aromatic ring [C-C-O-C torsion angles = 10.43 (18), 97.38 (14), À19.34 (17) ] and the phenyl ring makes a dihedral angle of 40.6 (2) with the plane through the remaining atoms in the molecule. Intermolecular N-HÁ Á ÁO hydrogen bonds link the molecules into chains running along the c axis.
All three methoxy groups are twisted with respect their attached aromatic ring (10. 41°, 97.38°, -19.34°, respectively) and the phenyl ring itself makes a dihedral angle of 40.64° with the plane through the remaining atoms (C7 through F1) in the molecule (Fig. 1). Similar geometry has been observed in a related hydrazone analogue (Liu et al., 2006). The bond lengths and bond angles are within normal ranges. Intermolecular N-H···O hydrogen bonds link the molecules into chains running along the c axis that help stabilize the molecular structure (Fig. 2).

S2. Experimental
A mixture of 3,4,5-trimethoxybenzohydrazide (1 mmol) and 4-fluorobenzaldehyde (1 mmol) in anhydrous ethanol (10 ml) was refluxed at 80 °C for 2 h. When the solution was cooled to room temperature(25 °C), some white needles separated out. After filtration, colorless single crystals suitable for X-ray analysis were obtained by slow evaporation of a methanol solution at room temperature.

S3. Refinement
All H atoms were placed in geometrically idealized positions and refined as riding, with N-H = 0.88 Å, C-H = 0.95 (aromatic and N=CH), 0.98 (methyl) Å and U iso (H) = xU eq (C, N), where x = 1.5 for the methyl,   The packing of the title compound, viewed down the a axis. The dashed lines represent the hydrogen bonding interactions.

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.