(Z)-Ethyl 2-chloro-2-[2-(4-methylphenyl)hydrazinylidene]acetate

The molecule of the title compound, C11H13ClN2O2, is approximately planar (r.m.s. deviation = 0.099 Å for non-H atoms) and adopts a Z conformation about the C=N double bond. In the crystal, molecules are linked by N—H⋯O and C—H⋯O hydrogen bonds to the same O-atom acceptor, forming zigzag chains propagating along [010]. These interactions give rise to R 2 1(6) loops.

The molecule of the title compound, C 11 H 13 ClN 2 O 2 , is approximately planar (r.m.s. deviation = 0.099 Å for non-H atoms) and adopts a Z conformation about the C N double bond. In the crystal, molecules are linked by N-HÁ Á ÁO and C-HÁ Á ÁO hydrogen bonds to the same O-atom acceptor, forming zigzag chains propagating along [010]. These interactions give rise to R 2 1 (6) loops.
The title compound, Fig. 1, and II contain methyl and methoxy groups respectively at para positions of aromatic ring, which make them different from each other. The aromatic ring (C1-C6) is oriented at a dihedral angle of 9.49 (8)° with respect to the mean plane of the ester moiety (N1/N2/O1/O2 C7-Cl0; r.m.s. deviation 0.0454 Å), while the same angle in II is 3.05 (2) °. The spatial arrangements of different functional groups around the C7═N2 double bond give rise to trans isomer i.e. Z conformation.
In the crystal, N-H···O and C-H···O hydrogen bonds connect the molecules along the b axis to form zigzag chains, enclosing six membered R 1 2 (6) ring motifs -see Table. 1 and Fig. 2.

Experimental
The molecule was synthesised according to the literature procedure (Asiri et al., 2011) and recrystallized from ethanol under slow evaporation giving yellow needles.

Refinement
The N-H H atom was located in a difference Fourier map and refined with U iso (H) = 1.2U eq (N). The C-bound H-atoms were included in calculated positions and treated as riding atoms: C-H = 0.93, 0.96 and 0.97 Å for CH(aromatic), CH methyl , and CH methylene H atoms, respectively, with U iso (H) = k × U eq (parent C-atom), where k = 1.5 for CH methyl H atoms and = 1.2 for other H atoms.

Computing details
Data collection: CrysAlis PRO (Agilent, 2012); cell refinement: CrysAlis PRO (Agilent, 2012); data reduction: CrysAlis PRO (Agilent, 2012); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2009); software used to prepare material for publication: WinGX (Farrugia, 2012 Table 1 for details. 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.