Methyl 3-[(E)-furfurylidene]dithiocarbazate

The molecule of the title Schiff base compound, C7H8N2OS2, prepared by the reaction of methyl dithiocarbazate and furfural in an ethanol solution under reflux, adopts an E configuration; the dithiocarbazate and furan units are located on opposite sides of the C=N double bond. The planar dithiocarbazate group is twisted slightly with respect to the furan ring, making a dihedral angle of 5.2 (1)°. Adjacent molecules are linked by N—H⋯S hydrogen bonding to form a supramolecular dimer across an inversion center.

The molecule of the title Schiff base compound, C 7 H 8 N 2 OS 2 , prepared by the reaction of methyl dithiocarbazate and furfural in an ethanol solution under reflux, adopts an E configuration; the dithiocarbazate and furan units are located on opposite sides of the C N double bond. The planar dithiocarbazate group is twisted slightly with respect to the furan ring, making a dihedral angle of 5.2 (1) . Adjacent molecules are linked by N-HÁ Á ÁS hydrogen bonding to form a supramolecular dimer across an inversion center.

Comment
Since some hydrazone derivatives have shown the potential bioactivity as DNA-damaging or mutagenic agents (Okabe et al., 1993), a lots of new hydrazone compounds has been synthesized in our laboratory (Shan et al., 2002(Shan et al., , 2003. As part of the ongoing investigation on hydrazone, we present here the crystal structure of the title compound. The molecular structure is shown in Fig. 1. The N2═C3 bond distance of 1.284 (2) Å clearly indicates the double bond character for the Schiff base compound. The molecule adopts an E configuration, the carbazate and furan moieties located on the opposite positions of the N2═C3 bond; similar to that found in a related structure (Chen et al., 2007). The dithiocarbazate moiety is well co-planar, the maximum atomic deviation being 0.037 (1) Å (S2), and the dithiocarbazate mean plane is slightly twisted with respect to the furan plane by a smaller dihedral angle of 5.2 (1)°. This shows the whole molecule is nearly co-planar.
Inter-molecular N-H···S hydrogen bonding links adjacent molecules to form the centro-symmetric supra-molecular dimmer ( Fig. 1 and Table 1).

Experimental
Methyl dithiocarbazate was synthesized in the manner reported previously (Hu et al., 2001). Methyl dithiocarbazate (1.24 g, 10 mmol) and furfural (0.96 g, 10 mmol) were dissolved in ethanol (10 ml) and refluxed for 4 h. Yellow crystalline product appeared after cooling to room temperature. They were separated and washed with cold water. Single crystals of the title compound were obtained by recrystallization from an 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 = 0.93 and N-H = 0.86 Å, and refined in the riding mode, U iso (H) = 1.2U eq (C,N). Fig. 1 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 Rfactors(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.