Ethyl 1,5-diphenyl-1H-pyrazole-4-carboxylate

The asymmetric unit of the title compound, C18H16N2O2, contains two independent molecules (A and B). In molecule A, the pyrazole ring is inclined at angles of 48.86 (6) and 60.80 (6)° with respect to the two phenyl rings; the corresponding angles for molecule B are 46.86 (6) and 58.63 (6)°. In the crystal, molecules of type A are linked into sheets parallel to (001) via weak C—H⋯O hydrogen bonds, whereas the molecules of type B are linked into chains along [010] via weak C—H⋯O hydrogen bonds.

The title compound ( Fig. 1) contains two indpendent molecules (A and B) in the asymmetric unit, with similar geometries.
Each molecule consists of two phenyl rings and an ethyl carboxylate moiety attached to the pyrazole ring. In molecule A, the pyrazole ring (N1A/N2A/C7A-C9A) is inclined at angles of 48.86 (6) and 60.80 (6)° with respect to the C1A-C6A and C10A-C15A phenyl rings, respectively. The correspondening angles for molecule B are 46.86 (6) and 58.63 (6)°. Bond lengths and angles are within normal ranges, and comparable to closely related structures (Fun et al., 2009;2010).

Experimental
A mixture of ethyl-3-(dimethylamino)-2-(phenylcarbonyl)prop-2-enoate (2.0 g, 0.0080 mol) and phenyl hydrazine (0.95 g, 0.0088 mol) in absolute ethanol (20 ml) was refluxed for 2 h. Reaction completion was monitored through thin layer chromatography and the reaction mixture was evaporated under reduced pressure. The residue was stirred with 1.5N HCl and the solid separated was filtered and dried under vacuum. The solid obtained was purified by column chromatography using silica gel 60-120 mesh size and petroleum ether: ethyl acetate as eluent to afford title compound as colourless crystals (2.0g, 86.9 %); melting point: 400-405 K.

Refinement
All H atoms were positioned geometrically and refined using a riding model with C-H = 0.93-0.97 Å and U iso (H) = 1.2 or 1.5 U eq (C). A rotating-group model was applied for the methyl groups. Fig. 1. The molecular structure of the title compound showing 50% probability displacement ellipsoids for non-H atoms and the atom-numbering scheme.    Glazer, 1986) operating at 100.0 (1) K.

Figures
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.