1-(3-Chlorophenyl)-4,4,6-trimethyl-3,4-dihydropyrimidine-2(1H)-thione

In the title compound, C13H15ClN2S, the dihydropyrimidine ring is essentially planar, with a maximum deviation from the least-squares plane of 0.122 (3) Å for the unsubstitued olefinic C atom. The dihedral angle between the dihydropyrimidine and benzene rings is 86.62 (13)°. The crystal structure is stabilized by intermolecular N—H⋯S hydrogen bonds, which form centrosymmetric dimers arranged along the c axis.

In the title compound, C 13 H 15 ClN 2 S, the dihydropyrimidine ring is essentially planar, with a maximum deviation from the least-squares plane of 0.122 (3) Å for the unsubstitued olefinic C atom. The dihedral angle between the dihydropyrimidine and benzene rings is 86.62 (13) . The crystal structure is stabilized by intermolecular N-HÁ Á ÁS hydrogen bonds, which form centrosymmetric dimers arranged along the c axis.
The molecular packing is also characterized by centrosymmetric dimers connected by the N-H..S intermolecular hydrogen bond forming a R 2 2 (8) ring (Etter et al., 1990, Bernstein et al., 1995 and are arranged parallel to the c axis (Table   1, Fig 2).

Experimental
The title compound was prepared by the reaction of thiocynic acid (5.4 mmol) and 3-chloroanaline (5.4 mmol) in acetone.

Refinement
All H atoms attached to C atoms were fixed geometrically and treated as riding with C-H= 0.93 Å(aromatic) or 0.96 Å(methy) with U iso (H)=1.2U eq (Caromatic) and 1.5U aq (Cmethyl). The amino hydrogen atom was located from the difference map and refined freely with U iso (H)=1.2U eq (N). In the last cycles of refinement, it was treated as riding on the parent N atom. Both methyl groups attached to C3 display rather elongated ellipsoids however no correct disordered model could be defined and these large ellipsoids may be related to dynamic motion.

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 > 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.