3-Chloro-6-{4-[3-(trifluoromethyl)phenyl]piperazin-1-yl}pyridazine

The title compound, C15H14ClF3N4, was synthesized from 3,6-dichloropyridazine and 1-[3-(trifluoromethyl)phenyl]piperazine. The piperazine ring is flanked by 3-chloropyridazine and 3-trifluoromethylphenyl rings and adopts a chair conformation, whereas the 3-chloropyridazine and 3-trifluoromethylphenyl rings are planar, with maximum deviations of 0.0069 (13) and 0.0133 (14) Å, respectively. The crystal structure is stabilized by weak intermolecular C—H⋯N hydrogen-bond interactions.


Comment
It is known that some pyrazolone derivatives like oxyphenbutazone, dipyrone, antipyrine and phenylbutazone are used primarily for their anti-inflammatory, antipyretic and analgesic activities, but several side effects have limited the clinical use of these drugs such as some of pyrazolone derivatives are toxic and carcinogenicin animals, clastogenic in somatic and germ cells of male mice, and also weakly mutagenic in Salmonella strain TA100 in presence of rat liver homogenate. In addition, some of pyrazolone derivatives induce peptic ulcer, hypersensitivity reaction, hepatitis, nephritis and bone marrow suppression (Giri & Mukhopadhyay, 1998).
The molecular structure of I consists of 3-chloropyridazine and 3-trifluoromethylphenyl arms connected to a piperazine ring. The 3-chloropyridazine and 3-trifluoromethylphenyl rings are planar with a maximum deviation of -0.0069 (13) Å for atom C7 and -0.0133 (14) Å for atom C3. The dihedral angle between these two rings is 18.77 (6) °. The piperazine ring adopts a chair conformation. This is confirmed by the puckering parameters q 2 = 0.0107 (14)

Refinement
The H atoms were positioned geometrically and allowed to ride on their parent atoms, with C-H distances of 0.95 Å (CH) or 0.99 Å (CH 2 ), and with U iso (H) = 1.2U eq of the parent atoms.
Figures Fig. 1. The molecular structure of (I), showing ellipsoids at the 50% probability level.

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 > σ(F 2 ) is used only for calculating Rfactors(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 C1  (17)