Benzyl N-[(Z)-(1-methyl-2-sulfanylpropylidene)amino]carbamodithioate

The title compound, C12H16N2S3, was obtained by the condensation reaction of S-benzyl dithiocarbazate and 3-mercaptobutan-2-one. The phenyl ring and thiol (SH) group are approximately perpendicular [S—C—C—C and N—C—C—S torsion angles = 67.8 (3) and 116.9 (2)°, respectively] to the rest of the molecule. In the crystal, molecules are linked by weak S—H⋯S and N—H⋯S hydrogen bonds, π–π interactions between the benzene rings [centroid–centroid distance = 3.823 (2) Å] and C—H⋯π interactions.


Crystal data
Cg1 is the centroid of the C5-C10 ring.

D-HÁ
Data collection: CrysAlis PRO (Agilent, 2011); cell refinement: CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: SIR92 (Altomare et al., 1994); program(s) used to refine structure: CRYSTALS (Betteridge et al., 2003); molecular graphics: Mercury (Macrae et al., 2006); software used to prepare material for publication: publCIF (Westrip, 2010 The past few years have seen a growing interest in the synthesis of Schiff base ligands and metal complexes specifically those derived from dithiocarbazates (Tarafder et al., 2002;Hossain et al., 1996). S-benzyldithiocarbazate (SBDTC) has been extensively studied due to the possibility of modifying its derivatives by the introduction of different substituents (Khoo et al., 2005), furthermore, SBDTC-derived Schiff base ligands have been shown to possess antimicrobial and anticancer properties (Hossain et al., 1996). Therefore, we have managed to synthesize the title compound, (I), which was a result of the condensation reaction between SBDTC and 3-mercaptobutan-2-one in order to investigate the bioactivity of this ligand and its metal complexes. In our course of research we have managed to grow crystals of the title compound,  Table 2). The benzene rings at (x, y, z) and (1 -x, 2 -y, 1 -z) are stacked parallel to each other and form π-π interactions with a separation of 3.823 Å and a shift distance of 1.539 Å [ Fig.3.], while the distance between the planes of the benzene rings is 3.500 Å. Furthermore, there are C-H···π interactions (Table 2) between the molecules of the structure [ Fig.4.] and the perpendicular distance between the plane of the benzene ring and H71 was found to be 2.790 Å. Cg in (Table 2) refers to the centroid of the benzene ring present in the structure.
The molecule crystallizes in the conformer in which the thione sulfur is in a trans position with the ketone moiety across the C2-N11 bond but adopts a cis position with the phenyl group across the C2-S3 bond. The ketone moiety is cis to the phenyl group with respect to the C2-N11 bond. Such geometrical arrangements are similar to dithiocarbazate derived compounds reported previously (Khoo et al., 2005;How et al., 2007).

Experimental
The method used for synthesis of the Schiff base ligand was a modified form of the one reported by (Tarafder et al., 2002). (0.02) moles of S-benzyldithiocarbazate were dissolved in 40 ml absolute ethanol and then heated on a heating plate with constant stirring in order to ensure complete dissolving. Similarly, (0.02) moles of 3-mercaptobutan-2-one were mixed with 40 ml of absolute ethanol and heated on a heating plate for 10 minutes. The reactants were mixed and 2-4 drops of concentrated H 2 SO 4 were added to the mixture. The mixture was kept on the heating plate for 5 more minutes and then cooled to 0°C in an ice-bath until the Schiff base precipitated. The Schiff base precipitated was filtered via suction filtration, washed with cold ethanol and dried over silica gel (yield 79.7%, m.p 361.45 K). Crystals suitable for X-ray analysis have been obtained via slow evaporation of ethanol over a period of 10 days.

Refinement
The H atoms were all located in a difference map, but those attached to carbon atoms were repositioned geometrically.
The H atoms were initially refined with soft restraints on the bond lengths and angles to regularize their geometry (C-H in the range 0.93-0.98 and N-H= 0.86 Å) and isotropic atomic displacement parameters (U iso (H) in the range 1.2-1.5 times U eq of the parent atom), after which the positions were refined with riding constraints. H atom for the thiol group was located in a difference map and its coordinates were refined

Figure 3
Molecules in the structure are linked by π-π interactions between pairs of benzene rings with centroid-centroid distance  Diagram showing the C-H···π interactions between the molecules of the structure. Distance between the centroid of the benzene ring and the hydrogen atom of the neighbouring molecule is 2.970 Å. Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )