A second monoclinic polymorph of 4-[(E)-(4-benzyloxybenzylidene)amino]-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one

In the title compound, C25H23N3O2, the central benzene ring makes dihedral angles of 77.14 (8) and 87.7 (2)° with the terminal benzene rings and an angle of 1.9 (1)° with the pyrazolone ring. The benzene ring and the N atom of the pyrazole ring bearing the phenyl substituent are disordered over two sets of sites with an occupancy ratio of 0.71 (2):0.29 (2). The N atoms of the pyrazole ring have a pyramidal environment, the sums of the valence angles around them being 354.6 (3) and 352.0 (6)/349.5 (15)°. In the crystal, molecules are packed into layers parallel to the ac plane. The other monoclinic polymorphic form was reported recently [Dutkiewicz et al. (2012 ▶). Acta Cryst. E68, o1324].

In the title compound, C 25 H 23 N 3 O 2 , the central benzene ring makes dihedral angles of 77.14 (8) and 87.7 (2) with the terminal benzene rings and an angle of 1.9 (1) with the pyrazolone ring. The benzene ring and the N atom of the pyrazole ring bearing the phenyl substituent are disordered over two sets of sites with an occupancy ratio of 0.71 (2):0.29 (2). The N atoms of the pyrazole ring have a pyramidal environment, the sums of the valence angles around them being 354.6 (3) and 352.0 (6)/349.5 (15) . In the crystal, molecules are packed into layers parallel to the ac plane. The other monoclinic polymorphic form was reported recently [Dutkiewicz et al. (2012). Acta Cryst. E68, o1324]. antimycobacterial (Patole et al., 2006). In view of the pharmacological importance of schiff base derivatives, the title compound (I) is prepared and its crystal structure is reported.

Experimental
The title compound was synthesized by adding 4-benzyloxybenzaldehyde (0.212 g, 1 mmol) to the solution of 4-aminoantipyrine (0.203 g, 1 mmol) in methanol (30 ml) containing few drops of conc. sulfuric acid. The mixture was refluxed for 3hrs and left stirring overnight at room temperature. The resultant solid obtained was then filtered. Yellow needleshaped single crystals suitable for X-ray structure determination were formed after slow evaporation of dichloromethane at room temperature (431-433 K).
In the refinement process restraints were imposed on C-C [1.38 (1) Å] distances of the disordered molecular fragments and the displacement parameters. All H atoms were positioned geometrically and were treated as riding on their parent C atoms, with C-H distances of 0.93-0.97 Å and with U iso (H) = 1.2U eq (C) or 1.5U eq (methyl C).

Figure 1
ORTEP view of the molecule with the atom-labeling scheme. The displacement ellipsoids are drawn at the 40% probability level. H atoms are shown as small spheres of arbitrary radii.

Figure 2
The packing arrangement of molecules viewed down the b axis. Hydrogen atoms have been omitted for clarity.   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 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 Occ.