N-Methyl-2-(1,2,3,4-tetrahydronaphthalen-1-ylidene)hydrazinecarbothioamide

There are two independent molecules in the asymmetric unit of the title compound, C12H15N3S, both of which display disorder of several C atoms in the N-bound ring (occupancy ratios of 0.75:0.25 in the first independent molecule and 0.50:0.50 in the second) with the methyl H atoms also being disordered in the first molecule (occupancy ratio of 0.70:0.30). The planes of the benzene ring and the N—N—C—N fragment make dihedral angles of 12.92 (14)° in the first independent molecule and 7.60 (13)° in the second. In the crystal, molecules are linked by weak N—H⋯S hydrogen bonds into chains along the a-axis direction. The crystal packing ressembles a herringbone arrangement.

There are two independent molecules in the asymmetric unit of the title compound, C 12 H 15 N 3 S, both of which display disorder of several C atoms in the N-bound ring (occupancy ratios of 0.75:0.25 in the first independent molecule and 0.50:0.50 in the second) with the methyl H atoms also being disordered in the first molecule (occupancy ratio of 0.70:0.30). The planes of the benzene ring and the N-N-C-N fragment make dihedral angles of 12.92 (14) in the first independent molecule and 7.60 (13) in the second. In the crystal, molecules are linked by weak N-HÁ Á ÁS hydrogen bonds into chains along the a-axis direction. The crystal packing ressembles a herringbone arrangement.

Related literature
For the synthesis, coordination chemistry and biological activity of thiosemicarbazones, see: Lobana et al. (2009). For one of the first reports of the synthesis of thiosemicarbazone derivatives, see: Freund & Schander (1902).
We gratefully acknowledge financial support by the State of Schleswig-Holstein, Germany. We thank Professor Dr Wolfgang Bensch for access to his experimental facilities. BRSF thanks CNPq/UFS for the award of a PIBIC scholarship and ABO acknowledges financial support through the FAPITEC/ SE/FUNTEC/CNPq PPP 04/2011 program.

Comment
Thiosemicarbazone derivatives have been used as ligands in coordination chemistry as well as for applications in biological systems, because some of them shows antifungal, antibacterial and anticancer properties (Lobana et al., 2009).
As part of our study on thiosemicarbazone compounds, we report herein the crystal structure of a tetralone thiosemicarbazone derivative.
In the crystal structure of the title compound, there are two crystallographically independent molecules on the asymmetric unit in general positions, in which some of the C, and H atoms are disordered (Fig. 1). For one crystallographic independent molecule, the dihedral angle between the benzene ring (C5-C10) and the N1-N2-C11-N3 fragment amounts to 12.92 (14)° and for the second crystallographically independent molecule the dihedral angle between the benzene ring (C25-C30) and the N21-N22-C31-N23 fragment amouts to 7.60 (13)°. So, the molecules do not only show a different kind of disorder, but differ also in the molecular geometry.
In the crystal, the molecules are linked by long weak N-H···S hydrogen bonding into chains that run along the a-axis.

Experimental
Starting materials were commercially available and were used without further purification. The tetralone-thiosemicarbazone derivative synthesis was adapted from a procedure reported previously (Freund & Schander, 1902). The hydrochloric acid catalyzed reaction of tetralone (8,83 mmol) and 4-methylthiosemicarbazide (8,83 mmol) in ethanol (50 ml) was refluxed for 6 h. After cooling and filtering, the title compound was obtained as a solid. Crystals suitable for Xray diffraction of the title compound were obtained in tethahydrofuran by the slow evaporation of solvent.

Refinement
All non-hydrogen atoms were refined anisotropic. All H atoms were located in difference map but were positioned with idealized geometry (methyl H atoms allowed to rotate but no to tip) and were refined isotropic with U iso (H) = 1,2 U eq (C) (1,5 for methyl H atoms) using a riding model with C-H = 0,95 Å for aromatic and C-H = 0,99 Å for methylene. The N-H H atoms were located in difference map and refined with varying coordinates and varying isotropic displacement parameters. There are two crystallographically independent molecules in the asymmetric unit. In both of them several C atoms disordered (C3, C4 and C23) and were refined using a split model. The methyl C12 H atoms are disordered and were refined in two orientations. SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2006); software used to prepare material for publication: publCIF (Westrip, 2010).

Figure 1
The molecular structure of the title compound with labeling and displacement ellipsoids drawn at the 40% probability level. Disorder is shown with full and open bonds.  Crystal structure of the title compound viewed along the c-axis. The disorder is not shown for clarity.