3-Methyl-1-benzofuran-2-carbohydrazide

In the asymmetric unit of the title benzofuran derivative, C10H10N2O2, there are three crystallograpically independent molecules, which are slightly twisted; the dihedral angle between the benzofuran ring system and the plane of the carbohydrazide unit is 8.64 (11)° in one molecule, whereas the dihedral angles are 9.58 (11) and 6.89 (10)° in the other two molecules. In the crystal, the three independent molecules are linked to each other through N—H⋯N hydrogen bonds, forming a trimer. The trimers are further linked by weak N—H⋯O and C—H⋯O hydrogen bonds into a three-dimensional network. π–π interactions with centroid–centroid distances in the range 3.4928 (11)–3.8561 (10) Å are also observed.

In the asymmetric unit of the title benzofuran derivative, C 10 H 10 N 2 O 2 , there are three crystallograpically independent molecules, which are slightly twisted; the dihedral angle between the benzofuran ring system and the plane of the carbohydrazide unit is 8.64 (11) in one molecule, whereas the dihedral angles are 9.58 (11) and 6.89 (10) in the other two molecules. In the crystal, the three independent molecules are linked to each other through N-HÁ Á ÁN hydrogen bonds, forming a trimer. The trimers are further linked by weak N-HÁ Á ÁO and C-HÁ Á ÁO hydrogen bonds into a three-dimensional network.interactions with centroid-centroid distances in the range 3.4928 (11)-3.8561 (10) Å are also observed.
There are three crystallographic independent molecules A, B and C in the asymmetric unit of (I) with differences in bond angles (Fig. 1). The molecule of the title benzofuran derivative, C 10 H 10 N 2 O 2 , is slightly twisted. The carbohydrazide fragment in molecules A and B are slightly twisted whereas it is planar in molecule C as indicated by the torsion angles of N2-N1-C9-O1 being -173.31 (17), -6.8 (3) and -179.64 (17)°, in molecules A, B and C, respectively. The dihedral angle between the mean plane through carbohydrazide fragment and the benzofuran ring is 8.64 (11)° in molecule A whereas they are 9.58 (11)) and 6.89 (10)° in molecules B and C, respectively. The bond distances agree with the literature values (Allen et al., 1987) and are comparable with the related structures (Ma et al., 2010;Wang et al., 2011).

Experimental
The title compound was prepared from the reaction of ethyl 3-methyl-2-benzofurancarboxylate with hydrazine according to the reported method (Dawood et al., 2005). Single crystals of the title compound suitable for X-ray structure determination were recrystallized from ethanol by the slow evaporation of the solvent at room temperature after several days.

Refinement
Hydrazide H atoms were located in a difference Fourier map and refined isotropically. The remaining H atoms were placed in calculated positions with C-H = 0.93 Å for aromatic and 0.96 Å for CH 3 atoms. The U iso values were constrained to be 1.5U eq of the carrier atom for methyl H atoms and 1.2U eq for the remaining H atoms. A rotating group model was used for the methyl groups.

Figure 1
The asymmetric unit of the title compound, showing 40% probability displacement ellipsoids and the atom-numbering scheme.  The crystal packing of the title compound viewed along the a axis. Hydrogen bonds are shown as dashed lines. where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max = 0.003 Δρ max = 0.23 e Å −3 Δρ min = −0.17 e Å −3 Extinction correction: SHELXTL (Sheldrick, 2008), Fc * =kFc[1+0.001xFc 2 λ 3 /sin(2θ)] -1/4 Extinction coefficient: 0.00139 (18) 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.