N′-(3,4-Dimethoxybenzylidene)acetohydrazide

In the title molecule, C11H14N2O3, the acetohydrazide group is planar 0.084 (1) Å and forms a dihedral angle of 19.7 (1)° with the benzene ring. One of the methoxy groups is coplanar with the attached benzene ring within 0.052 (3) Å, whereas the other is slightly twisted [C—O—C—C = 6.3 (3)°]. The molecule adopts a trans configuration with respect to the C=N bond. In the crystal, the molecules are linked into chains along the a axis by N—H⋯O hydrogen bonds and the chains are cross-linked into a three-dimensional network by C—H⋯O hydrogen bonds.

In the title molecule, C 11 H 14 N 2 O 3 , the acetohydrazide group is planar 0.084 (1) Å and forms a dihedral angle of 19.7 (1) with the benzene ring. One of the methoxy groups is coplanar with the attached benzene ring within 0.052 (3) Å , whereas the other is slightly twisted [C-O-C-C = 6.3 (3) ]. The molecule adopts a trans configuration with respect to the C N bond. In the crystal, the molecules are linked into chains along the a axis by N-HÁ Á ÁO hydrogen bonds and the chains are cross-linked into a three-dimensional network by C-HÁ Á ÁO hydrogen bonds.
They are also important ligands, which have been reported to have mild bacteriostatic activity and are used as potential oral iron-chelating drugs for genetic disorders such as thalassemia (Offe et al., 1952;Richardson et al., 1988). Metal complexes based on Schiff bases have received considerable attention because they can be utilized as model compounds of active centres in various complexes (Tamboura et al., 2009). We report here the crystal structure of the title compound (Fig. 1).
The acetohydrazide group is planar and it forms a dihedral angle of 19.7 (1)° with the benzene ring. One of the methoxy groups is coplanar with the attached benzene ring [C1-O1-C4-C5 = -1.7 (3)°] whereas the other is slightly twisted The molecule adopts a trans configuration with respect to the C═N bond. Bond lengths and angles are comparable to those observed for N'-[1-(4-methoxyphenyl)ethylidene]acetohydrazide (Li et al., 2008).
The molecules are linked into a chain along the a axis by N-H···O hydrogen bonds (Table 1). The chains are cross-linked into a three-dimensional network by C-H···O hydrogen bonds (Fig.2).
Experimental 3,4-Dimethoxybenzaldehyde (1.66 g, 0.01 mol) and acetohydrazide (0.74 g, 0.01 mol) were dissolved in stirred methanol (25 ml) and left for 2.5 h at room temperature. The resulting solid was filtered off and recrystallized from ethanol to give the title compound in 90% yield. Single crystals suitable for X-ray analysis were obtained by slow evaporation of an ethanol solution at room temperature (m.p. 470-472 K).

Refinement
H atoms were positioned geometrically (N-H = 0.86 Å and C-H = 0.93 or 0.96Å) and refined using a riding model, with U iso (H) = 1.2U eq (C,N) and 1.5U eq (C methyl ). A rotating group model was used for the methyl groups.

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 > 2sigma(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.