3,5-Bis(4-fluorophenyl)-4,5-dihydro-1H-pyrazole-1-carbaldehyde

In the title molecule, C16H12F2N2O, the pyrazole ring adopts a slight envelope conformation with the methylene C atom deviating by 0.114 (3) Å from the mean plane of the other four atoms [maximum deviation = 0.021 (3) Å]. The dihedral angles between the four essentially planar atoms of the pyrazole ring and the fluoro-substituted benzene rings are 2.6 (2) and 82.2 (2)°. The dihedral angle between the two benzene rings is 83.7 (2)°. The crystal packing is stabilized by weak intermolecular C—H⋯O hydrogen bonds.

In the title molecule, C 16 H 12 F 2 N 2 O, the pyrazole ring adopts a slight envelope conformation with the methylene C atom deviating by 0.114 (3) Å from the mean plane of the other four atoms [maximum deviation = 0.021 (3) Å ]. The dihedral angles between the four essentially planar atoms of the pyrazole ring and the fluoro-substituted benzene rings are 2.6 (2) and 82.2 (2) . The dihedral angle between the two benzene rings is 83.7 (2) . The crystal packing is stabilized by weak intermolecular C-HÁ Á ÁO hydrogen bonds.
Some of these compounds have also antioxidant, anti-diabetic, anaesthetic and analgesic properties (Sarojini et al., 2010;Regaila et al., 1979). In addition, pyrazolines have played a crucial part in the development of theory in heterocyclic chemistry and also used extensively in organic synthesis (Klimova et al., 1999 andBhaskarreddy et al., 1997).
The molecular structure of the title compound is shown in Fig. 1. The pyrazole ring adopts a slight envelope comformation with the methylene C atom (C8) deviating by 0.114 (3)Å from the mean-plane of the other four atoms (C7/C9/N1/N2 with maximum deviation 0.021 (3)Å for N1). The dihedral angles between the four essentially planar atoms of the pyrazole ring and fluoro-substituted benzene rings are 2.6 (2) and 82.2 (2)°, respectively. The dihedral angle between the two benzene rings is 83.7 (2)°. The crystal packing is stabilized by weak intermolecular C-H···O hydrogen bonds (Fig .2).

Experimental
A mixture of (2E)-1,3-bis(4-fluorophenyl)prop-2-en-1-one (2.44 g, 0.01 mol) and hydrazine hydrate (0.5 ml, 0.01 mol) in 20 ml formic acid was refluxed for 8 h. The reaction mixture was cooled and poured into 50 ml ice-cold water. The precipitate was collected by filtration and purified by recrystallization from ethanol. The single-crystal was grown from DMF by slow evaporation method and yield of the compound was 86%. (m. p.: 408 K).

Refinement
All H atoms were positioned geometrically [C-H = 0.93 and 0.97 Å] and allowed to ride on their parent C atoms, with U iso (H) = 1.2U eq (C). Owing to the large number of weak high-angle reflections, the ratio of observed to unique reflections is low (37%). Fig. 1. The title molecule with displacement ellipsoids for non-H atoms are drawn at the 30% probability level.