5-(3-Fluorophenyl)-1-phenylpyrazolidin-3-one

In the molecule of the title compound, C15H13FN2O, the phenyl and fluorophenyl rings are oriented at a dihedral angle of 77.92 (3)°. The pyrazolidine ring adopts an envelope conformation. An intramolecular C—H⋯N hydrogen bond results in the formation of a five-membered ring adopting an envelope conformation. In the crystal structure, intermolecular N—H⋯O and C—H⋯O hydrogen bonds link the molecules. There are C—H⋯π contacts between between aromatic H atoms and the phenyl and fluorophenyl rings. A π–π contact between phenyl rings [centroid–centroid distance = 3.926 (1) Å] is also observed.

In the molecule of the title compound, C 15 H 13 FN 2 O, the phenyl and fluorophenyl rings are oriented at a dihedral angle of 77.92 (3) . The pyrazolidine ring adopts an envelope conformation. An intramolecular C-HÁ Á ÁN hydrogen bond results in the formation of a five-membered ring adopting an envelope conformation. In the crystal structure, intermolecular N-HÁ Á ÁO and C-HÁ Á ÁO hydrogen bonds link the molecules. There are C-HÁ Á Á contacts between between aromatic H atoms and the phenyl and fluorophenyl rings. Acontact between phenyl rings [centroid-centroid distance = 3.926 (1) Å ] is also observed.
In the molecule of the title compound ( Fig. 1), the bond lengths (Allen et al., 1987) and angles are within normal ranges.
In the crystal structure, intermolecular N-H···O and C-H···O hydrogen bonds link the molecules (Fig. 2), in which they may be effective in the stabilization of the structure. The C-H···π contacts (Table 1) between the phenyl rings and the aromatic H atoms and a π-π contact between phenyl rings Cg2···Cg2 i [symmetry code: (i) -x, 1 -y, 1 -z, where Cg2 is centroid of the ring A (C1-C6)] further stabilize the structure, with centroid-centroid distance of 3.926 (1) Å.

Experimental
The title compound was prepared according to the literature method (Jia et al., 2008). The crystals were obtained by dissolving the title compound (1.5 g) in ethyl acetate (25 ml) and evaporating the solvent slowly at room temperature for about 10 d.

Refinement
H atoms were positioned geometrically, with N-H = 0.86 Å (for NH) and C-H = 0.93, 0.98 and 0.97 Å for aromatic, methine and methylene H, respectively, and constrained to ride on their parent atoms with U iso (H) = 1.2U eq (C,N).