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

In the title compound, C9H8Cl2N2OS, the conformation of one of the N—H bonds is anti to the C=S group and the other is anti to the C=O group. Further, the conformations of the amide C=S and the C=O group are anti to each other. The 2,6-dichlorophenyl ring and the 3-acetylthiourea side chain are inclined to one another at a dihedral angle of 83.44 (5)°. An intramolecular N—H⋯O hydrogen bond occurs. In the crystal, molecules form inversion dimers through pairs of N—H⋯S hydrogen bonds.

In the title compound, C 9 H 8 Cl 2 N 2 OS, the conformation of one of the N-H bonds is anti to the C S group and the other is anti to the C O group. Further, the conformations of the amide C S and the C O group are anti to each other. The 2,6-dichlorophenyl ring and the 3-acetylthiourea side chain are inclined to one another at a dihedral angle of 83.44 (5) . An intramolecular N-HÁ Á ÁO hydrogen bond occurs. In the crystal, molecules form inversion dimers through pairs of N-HÁ Á ÁS hydrogen bonds.
BTG thanks the University Grants Commission, Government of India, New Delhi, for a special grant under a UGC-BSR one-time Grant to faculty.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: SJ5247). Thiourea and its derivatives exhibit a wide variety of biological activities. As part of our studies of the substituent effects on the structures and other aspects of N-(aryl)-amides (Bhat & Gowda, 2000); Gowda et al., 2003;Shahwar et al., 2012); N-(aryl)-methanesulfonamides (Gowda et al., 2007) and N-chloroarylsulfonamides (Gowda et al., 2005;Shetty & Gowda, 2004), in the present work, the crystal structure of 3-acetyl-1-(2,6-dichlorophenyl)thiourea has been determined The structure shows intramolecular hydrogen bonding between the NH hydrogen atom, attached to the 2,6-dichlorophenyl ring and the amide oxygen. In the crystal, the molecules form inversion type dimers through N-H···S intermolecular hydrogen bonds (Table 1, Fig.2).

Experimental
3-Acetyl-1-(2,6-dichlorophenyl)-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-dichloroaniline (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 infrared spectrum.
Plate like dark yellow single crystals used in X-ray diffraction studies were grown in acetonitrile solution by slow evaporation of the solvent at room temperature.

Refinement
H atoms bonded to C were positioned with idealized geometry using a riding model with the aromatic C-H = 0.93 Å, methyl C-H = 0.96 Å. The amino H atoms were freely refined with the N-H distances restrained to 0.86 (2) Å. All H atoms were refined with isotropic displacement parameters set at 1.2 U eq (C-aromatic, N) and 1.5 U 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
Experimental. Absorption correction: CrysAlis RED (Oxford Diffraction, 2009) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm. 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.