N-(1,5-Dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)-2-[4-(methylsulfanyl)phenyl]acetamide

In the title compound, C20H21N3O2S, the 2,3-dihydro-1H-pyrazole ring is nearly planar (r.m.s. deviation = 0.023 Å) and forms dihedral angles of 16.96 (6) and 38.93 (6)° with the benzene and phenyl rings, respectively. The dihedral angle between the benzene and phenyl rings is 55.54 (6)°. The molecular conformation is consolidated by an intramolecular C—H⋯O hydrogen bond, which forms an S(6) ring. In the crystal, inversion dimers linked by pairs of N—H⋯Op (p = pyrazole) hydrogen bonds generate R 2 2(10) loops. The dimers are linked by C—H⋯O hydrogen bonds into sheets lying parallel to (100).

In the title compound, C 20 H 21 N 3 O 2 S, the 2,3-dihydro-1Hpyrazole ring is nearly planar (r.m.s. deviation = 0.023 Å ) and forms dihedral angles of 16.96 (6) and 38.93 (6) with the benzene and phenyl rings, respectively. The dihedral angle between the benzene and phenyl rings is 55.54 (6) . The molecular conformation is consolidated by an intramolecular C-HÁ Á ÁO hydrogen bond, which forms an S(6) ring. In the crystal, inversion dimers linked by pairs of N-HÁ Á ÁO p (p = pyrazole) hydrogen bonds generate R 2 2 (10) loops. The dimers are linked by C-HÁ Á ÁO hydrogen bonds into sheets lying parallel to (100).

Refinement
Atom H1N1 was located in a difference Fourier map and refined freely [N-H = 0.878 (19) Å]. The remaining H atoms were positioned geometrically and refined using a riding model with C-H = 0.95-0.99 Å and U iso (H) = 1.2 or 1.5 U eq (C).
A rotating-group model was applied for the methyl groups.  The molecular structure of the title compound showing 50% probability displacement ellipsoids for non-H atoms.

Computing details
Intramolecular hydrogen bond is shown as dashed line.

Figure 2
The crystal structure of the title compound, viewed along the b axis. H atoms not involved in hydrogen bonds (dashed lines) have been omitted for clarity.  (Cosier & Glazer, 1986) operating at 100.0 (1) K. 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq S1 0.90518 (2