(E)-Methyl 3-(2-nitrobenzylidene)dithiocarbazate

The asymmetric unit of the title compound, C9H9N3O2S2, contains two independent molecules, A and B, with similar bond dimensions. In both molecules, the nitro group is tilted with respect to the aromatic ring [dihedral angles 32.0 (1)° in molecule A and 34.0 (1)° in molecule B]. The dithiocarbazate unit is nearly coplanar with the aromatic ring in both molecules. For molecule B, pairs of molecules are linked by N—H⋯O and C—H⋯O hydrogen bonds about a centre of symmetry to form a dimer, whereas molecules A are not involved in hydrogen bonding in the crystal structure.

The asymmetric unit of the title compound, C 9 H 9 N 3 O 2 S 2 , contains two independent molecules, A and B, with similar bond dimensions. In both molecules, the nitro group is tilted with respect to the aromatic ring [dihedral angles 32.0 (1) in molecule A and 34.0 (1) in molecule B]. The dithiocarbazate unit is nearly coplanar with the aromatic ring in both molecules. For molecule B, pairs of molecules are linked by N-HÁ Á ÁO and C-HÁ Á ÁO hydrogen bonds about a centre of symmetry to form a dimer, whereas molecules A are not involved in hydrogen bonding in the crystal structure. Mo K radiation = 0.45 mm À1 T = 291 (2) Table 1 Hydrogen-bond geometry (Å , ).

Comment
Hydrazone and its derivatives have attracted our much attention because of their application in biological field (Okabe et al., 1993). As part of our ongoing investigation on anti-cancer compounds (Hu et al., 2001), the title compound has been prepared and its structure is presented here.
The asymmetric unit of the title compound contains two crystallographic independent molecules, A (C1-containing molecule) and B (C11-containing molecule), with the similar structure ( Fig. 1). In the two molecules, the nitro groups are tilted with respect to the connected benzene rings by dihedral angles of 31.96 (11) and 33.96 (11)°, respectively; while dithiocarbazate moieties are nearly co-planar with the benzene rings, dihedral angles being 3.00 (6) and 4.03 (6)°, respectively. The centro-symmetry related B molecules are linked by N-H···O hydrogen bonding to form the supramolecular dimer (Table   2). Whereas the A molecules are not involved in hydrogen bonding in the crystal structure. The N2═C7 and N12═C17 bond distances (Table 1) indicate the typical N═C double bonds. Around the N═C double bonds, both molecules A and B exhibit the E configuration, similar to those found in related compounds (Chen et al., 2007;Shan & Zhang, 2006;Zhang et al., 2005).

Experimental
Methyl dithiocarbazate was synthesized in the manner reported previously (Hu et al., 2001). Methyl dithiocarbazate (1.24 g, 10 mmol) and 2-nitrobenzaldehyde (1.51 g, 10 mmol) were dissolved in ethanol (10 ml) and refluxed for 4 h. Fine yellow crystals appeared on cooling. They were separated and washed with cold water three times. Single crystals of the title compound were obtained by recrystallization from an absolute ethanol solution.

Refinement
Methyl H atoms were placed in calculated positions with C-H = 0.96 Å and torsion angle was refined to fit electron density, U iso (H) = 1.5U eq (C). Other H atoms were placed in calculated positions with C-H = 0.97 and N-H = 0.86 Å, and refined in the riding mode, with U iso (H) = 1.2U eq (C,N). Fig. 1 as large as those based on F, and R-factors based on ALL data will be even larger.