3-Acetyl-1-(2,6-dimethylphenyl)thiourea

In the title compound, C11H14N2OS, the two N—H bonds are anti to each other and one of them is anti to the C=S and the other is syn. Further, the amide C=S and the C=O groups are anti to each other. The dihedral angle between the benzene ring and the side chain is 83.74 (5)°. An intramolecular N—H⋯O hydrogen bond occurs. In the crystal, molecules are linked into inversion dimers by pairs of N—H⋯S interactions.

In the title compound, C 11 H 14 N 2 OS, the two N-H bonds are anti to each other and one of them is anti to the C S and the other is syn. Further, the amide C S and the C O groups are anti to each other. The dihedral angle between the benzene ring and the side chain is 83.74 (5) . An intramolecular N-HÁ Á ÁO hydrogen bond occurs. In the crystal, molecules are linked into inversion dimers by pairs of N-HÁ Á ÁS interactions.
The conformation of the two N-H bonds are anti to each other, and one of them is anti to the C═S and the other is syn in the urea moiety. Furthermore, the conformations of the amide C═S and the C═O are anti to each other, similar to the anti conformation observed in 3-acetyl-1-(2-methylphenyl)thiourea (Shahwar et al., 2012).
The structure shows intramolecular hydrogen bonding between the hydrogen atom of the NH attached to the phenyl ring and the amide oxygen. In the crystal, the molecules form inversion type dimers through N-H···S intermolecular classical hydrogen bonds (Table 1, Fig. 2).

Experimental
The 3-acetyl-1-(2,6-dimethylphenyl)-thiourea was synthesized by adding a solution of acetyl chloride (0.10 mol) in acetone (30 ml) dropwise to a suspension of ammonium thiocyanate (0.10 mol) in acetone (30 ml). The reaction mixture was refluxed for 30 min. After cooling to room temperature, a solution of 2,6-dimethylaniline (0.10 mol) in acetone (10 ml) was added and refluxed for 3 h. The reaction mixture was poured into acidified cold water. The precipitated title compound was recrystallized to constant melting point from acetonitrile. The purity of the compound was checked and characterized by its IR spectrum. The characteristic absorptions observed are 3156.1 cm -1 , 1698.1 cm -1 , 1365.7 cm -1 and 710.4 cm -1 for the stretching bands of -N-H, -C═O, -C-N-and -C═S, respectively.
Prism like light yellow single crystals used in X-ray diffraction studies were grown in acetonitrile solution by slow evaporation of the solvent at room temperature.

Refinement
The amino H atoms were freely refined with the N-H distances restrained to 0.86 (2)Å. H atoms bonded to C were positioned with idealized geometry using a riding model with the aromatic C-H = 0.93Å, methyl C-H = 0.96Å. All H atoms were refined with isotropic displacement parameters set at 1.2U eq (C-aromatic, N) and 1.5U eq (C-methyl) of the parent atom.  (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2009); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).  Molecular packing of the title compound with hydrogen bonding shown as dashed lines.

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