Benzyl 2-methyl-3-[(E)-(thiophen-2-yl)methylidene]dithiocarbazate

In the title compound, C14H14N2S3, the thione S atom and methyl group are syn, as are the two thioether S atoms. The molecule is twisted, the dihedral angles between the central (C2N2S2) residue and the pendent 2-thienyl and phenyl rings being 21.57 (6) and 77.54 (3)°, respectively. In the crystal, molecules assemble into a three-dimensional architecture via C—H⋯π interactions, involving both the five- and six-membered rings as acceptors, as well as S⋯S interactions [3.3406 (5) Å] between centrosymmetrically related 2-thienyl rings.

In the title compound, C 14 H 14 N 2 S 3 , the thione S atom and methyl group are syn, as are the two thioether S atoms. The molecule is twisted, the dihedral angles between the central (C 2 N 2 S 2 ) residue and the pendent 2-thienyl and phenyl rings being 21.57 (6) and 77.54 (3) , respectively. In the crystal, molecules assemble into a three-dimensional architecture via C-HÁ Á Á interactions, involving both the five-and sixmembered rings as acceptors, as well as SÁ Á ÁS interactions [3.3406 (5) Å ] between centrosymmetrically related 2-thienyl rings.
The University Grants Commission, Bangladesh, is thanked for a fellowship to BG. We also thank the Ministry of Higher Education (Malaysia) for funding structural studies through the High-Impact Research scheme (UM.C/HIR/MOHE/SC/ 12). In a rare example of a closely related compound, an S-methyl ester, the extreme ends of the molecule are both co-planar with the central residue (Scovill & Silverton, 1980). In (I), the thione-S and methyl group are syn, as are the two thioether-S atoms.

Experimental
The title compound was isolated after a four step synthetic procedure. Synthesis of N-methyl-S-benzyldithiocarbazate: Potassium hydroxide (11.5 g), was dissolved in 90% ethanol (60 ml) and the mixture was cooled down to 273 K in an ice-bath. To this, methyl hydrazine (11.1 ml) was added slowly with mechanical stirring. A solution of carbondisulfide (12 ml) was added drop-wise from a burette with constant stirring over a period of 1 h. During this addition, the temperature of the reaction mixture was not to allowed to rise above 279 K. A yellow solution was obtained. Benzyl chloride (25 mL) was then added drop-wise with vigorous mechanical stirring. After the complete addition, the mixture was stirred for further 15 min, whereupon well formed crystals appeared. The product was separated by filtration and washed with water and recrystallized from ethanol and dried in a vacuum desiccator over silica gel. Yield: 15.75 g. M.pt: Synthesis of (I): A hot solution thiophene-2-carboxaldehyde (1.05 ml, 10 mmol) in absolute ethanol (40 ml) was mixed with a hot solution of N-methyl-S-benzyldithiocarbazate (2.12 g, 10 mmol) in the same solvent (40 ml). The mixture was refluxed for 6 h. on a water bath. After reducing a pale-red product appeared which was filtered off. This product was washed with ethanol several times (3 × 2 ml) and dried in a vacuum desiccator over silica gel Attempted preparation of the dioxomolybdenum(VI) complex with (I): [MoO 2 (acac) 2 ] (10 mmol) was dissolved in dry ethanol (40 ml) to which a hot solution of L (10 mmol) in dry ethanol (40 ml) was added. The mixture was refluxed for 6 h. on a water bath. After reducing the volume and standing overnight a light-blue product appeared, which was washed with ethanol for several times and dried in a vacuum desiccator over silica gel. M. pt: of product was > 493 K.
Crystallization: The product was dissolved in ethanol to which half volume of petroleum ether was added (10/5 ml v/v).
The solution was left for several days after which the title compound, (I), was deposited as crystals.

Special details
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s 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 > σ(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.