2-Methyl-5-[(3-methyl-4-nitrobenzyl)sulfanyl]-1,3,4-thiadiazole

The molecule of the title thiadiazole derivative, C11H11N3O2S2, has a butterfly-like structure and the whole molecule is disordered with a site-occupancy ratio of 0.629 (4):0.371 (4). The molecule is disordered in such a way that the 3-methyl-4-nitrophenyl units of the major and minor components are approximately related by 180° rotation around the C—N bond axis. The dihedral angle between the 1,3,4-thiadiazole and benzene rings is 70.8 (4)° in the major component and 74.9 (6)° in the minor component. In the crystal, molecules are arranged into screw chains along the c axis. These chains are stacked along the b axis. Weak intermolecular C—H⋯O and C—H⋯π interactions and a short C⋯O contact [3.005 (7) Å] are present.


Comment
Many classes of thiadiazole compounds have been intensely investigated with a number of them having found to be biologically and pharmacologically active. The 1,3,4-thiadiazole derivatives exhibit a wide spectrum of pharmacological and biological properties such as antituberculosis, anti-inflammatory, antifungal and antibacterial activities (Bernard et al., 1985;Chandrakantha et al., 2010;Isloor et al., 2010;Kalluraya et al., 2004;Oruç et al., 2004;Salimon et al., 2010). The title 1,3,4-thiadiazole derivative, (I), was synthesized in order to study its biological activity. Herein we report the crystal structure of (I).
The whole molecule of (I), C 11 H 11 N 3 O 2 S 2 , is disordered over two sites with the major component and minor A components having refined site-occupancy ratio of 0.629 (3)/0.371 (3) and has a butterfly-like structure with a torsion angle C8-S1-C7-C6 = -79.8 (5)° in major component [-79.6 (9)° in minor A component]. The molecule is disordered in such a way that the 3-methyl-4-nitrophenyl unit in the major and minor components is related by 180° rotation. The dihedral angle between the 1,3,4-thiadiazole and benzene rings is 70.8 (4)° in the major component [74.9 (6)° in the minor A component].
In both components the nitro group is slightly twisted with respect to the attached benzene ring with the torsion angles  (Allen et al., 1987) and are comparable with the related structures (Fun et al., 2011;Wang et al., 2010).

Experimental
The title compound was synthesized by adding 3-methyl-4-nitrobenzylbromide (3.47 g, 0.0151 mol) dropwise to a stirred solution of 5-methyl-1,3,4-thiadiazole-2-thiol (2.00 g, 0.0151 mol) and anhydrous potassium carbonate (4.16 g, 0.03 mol) in dry acetonitrile (50 ml) at room temperature and the reaction mixture was stirred at room temperature for 5 h. After the completion of reaction, the reaction mixture was filtered and the filtrate was concentrated. The crude product was recrystallized with hot ethanol to afford the title compound as yellow solid (2.20 g, 52% yield). Yellow plate-shaped single crystals of the title compound suitable for x-ray structure determination were recrystalized from ethanol by the slow evaporation of the solvent at room temperature after several days (M.p. 443-445 K).

Refinement
All H atoms were positioned geometrically and allowed to ride on their parent atoms, with d(C-H) = 0.93 Å for aromatic, 0.97 Å for CH 2 and 0.96 Å for CH 3 atoms. The U iso (H) values were constrained to be 1.5U eq of the carrier atom for methyl H atoms and 1.2U eq for the remaining H atoms. A rotating group model was used for the methyl groups. The highest residual supplementary materials sup-2 electron density peak is located at 0.70 Å from C7 and the deepest hole is located at 1.22 Å from S1A. The whole molecule is disordered over two sites with occupancies 0.629 (3) and 0.371 (3). Initially rigidity and similarity restraints were applied. After a steady state was reached, all these restraints were removed before the final refinement. Fig. 1. The molecular structure of the title compound, showing 50% probability displacement ellipsoids and the atom-numbering scheme. Open bond show the minor A component.

Special details
Experimental. The crystal was placed in the cold stream of an Oxford Cryosystems Cobra open-flow nitrogen cryostat (Cosier & Glazer, 1986) operating at 100.0 (1) K. 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.