(4Z)-4-[(Cyclopropylamino)(phenyl)methylene]-3-methyl-1-phenyl-1H-pyrazol-5(4H)-one

In the title compound, C20H19N3O, the dihedral angles formed by the pyrazolone ring with the two phenyl rings are 64.27 (6) and 17.00 (6)°. The molecular structure is stabilized by intramolecular N—H⋯O and C—H⋯O hydrogen bonds. In the crystal, the molecules are linked into chains along the b axis by intermolecular C—H⋯O hydrogen bonds.

In the title compound, C 20 H 19 N 3 O, the dihedral angles formed by the pyrazolone ring with the two phenyl rings are 64.27 (6) and 17.00 (6) . The molecular structure is stabilized by intramolecular N-HÁ Á ÁO and C-HÁ Á ÁO hydrogen bonds. In the crystal, the molecules are linked into chains along the b axis by intermolecular C-HÁ Á ÁO hydrogen bonds.

Related literature
For the antibacterial, biological and analgesic activity of metal complexes of 1-phenyl-3-methyl-4-benzoylpyrazolon-5-one, see: Li et al. (1997); Liu et al. (1980);Zhou et al. (1999). For a related structure, see: Wang et al. (2003).  Table 1 Hydrogen-bond geometry (Å , ).  Comment 1-Phenyl-3-methyl-4-benzoylpyrazolon-5-one (HPMBP), an effective β-diketonate, is widely used and well known for its extractive ability. In recent years, HPMBP and its metal complexes have also been found to have good antibacterial and biological properties. Its metal complexes have analgesic activity (Liu et al., 1980;Li et al., 1997;Zhou et al., 1999). In order to develop new medicines, we have synthesized the title compound and its crystal structure is reported here.

Experimental
The structure of the title molecule is shown in Fig. 1. The dihedral angles formed by the pyrazolone ring with the C6-C11 and C15-C20 phenyl rings and cyclopropane ring are 64.27 (6)°, 17.00 (6)° and 71.28 (11)°, respectively. The O atom of the 3-methyl-1-phenylpyrazol-5-one moiety and the N atom of the amino group are available for coordination with metals.

Experimental
The title compound was synthesized by refluxing a mixture of 1-phenyl-3-methyl-4-benzoylpyrazol-5-one (10 mmol) and cyclopropanamine (10 mmol) in ethanol (80 ml) over a steam bath for about 16 h. Excess solvent was removed by evaporation and the solution was cooled to room temperature. After 2 d, a colourless solid was obtained and this was dried in air.
The product was recrystallized from ethanol, to afford colourless crystals of the title compound suitable for X-ray analysis.

Refinement
C-bonded H atoms were positioned geometrically, with C-H = 0.95-1.00 Å and the amine H atom (H1) was found in a difference map. The amine H atom was refined freely, while C-bonded H atoms were included in the final cycles of refinement using a riding model, with U iso (H) = 1.2U eq (CH 2 and CH) or 1.5U eq (CH 3 ).

Special details
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.