N-(Diphenylcarbamothioyl)-3-methylbenzamide

The synthesis of the title compound, C21H18N2OS, involves the reaction of 3-methylbenzoyl chloride with potassium thiocyanate in dry acetone followed by condensation of the 3-methylbenzoyl isothiocyanate with diphenylamine. The carbonyl [C—O = 1.215 (2) Å] and thiocarbonyl [C—S = 1.6721 (17) Å] distances indicate that these correspond to double bonds. The short C—N bonds at the center of the molecule reveal the effects of resonance in this part of the molecule. The conformation of the molecule with respect to the thiocarbonyl and carbonyl groups is twisted. The 3-methylphenyl and two phenyl rings are also twisted, with dihedral angles of 75.67 (9) and 14.91 (9)°. The phenyl rings are rotated out of the mean plane of the N—C—S—N atoms by 66.87 (8) and 78.40 (9)°. Pairs of molecules are linked into centrosymmetric dimers via intermolecular N—H⋯S interactions and a C—H⋯O link also occurs. The dimers are stacked along the a axis.

As can be seen from the packing diagram ( Fig. 2), intermolecular N-H···S hydrogen bond (Table 1) links the molecules into dimers, which are stacked along the a axis. The C-H···O intermolecular contact is also listed in Table 1.

Experimental
The title compound was prepared with a procedure similar to that reported in the literature (Arslan et al., 2003c). A solution of 3-methylbenzoyl chloride (0.01 mol) in acetone (50 ml) was added dropwise to a suspension of potassium thiocyanate (0.01 mol) in acetone (30 ml). The reaction mixture was heated under reflux for 30 min, and then cooled to room temperature. A solution of diphenylamine (0.01 mol) in acetone (10 ml) was added and the resulting mixture was stirred for 2 h. Hydrochloric acid (0.1 N, 300 ml) was added to the solution, which was then filtered. The solid product was washed with water and purifed by recrystalization from an ethanol:dichloromethane mixture (1:2). Analysis calculated for C 21 H 18 N 2 OS: C 72.8, H 5.2, N 8.1%. Found: C 72.6, H 5.2, N 8.0%.

Refinement
H atoms bound to C atoms were placed geometrically and allowed to ride during subsequent refinement with C-H = 0.95 and 0.98 Å and U iso (H) = 1.2 or 1.5 U eq (C). The nitrogen-bound H atom was located in a difference Fourier map and refined freely. Fig. 1. The molecular structure of (I). Displacement ellipsoids are drawn at the 50% probability level.

Special details
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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.