Dichloridobis(4-methyl-3,5-diphenyl-1H-pyrazole-κN 2)copper(II)

The asymmetric unit of the title compound, [CuCl2(C16H14N2)2], comprises half of the complex. The CuII atom lies on a crystallographic twofold rotation axis and shows a significantly distorted tetrahedral coordination geometry. The dihedral angle between the phenyl rings is 74.3 (2)°. The crystal structure is stabilized by intermolecular π–π interactions [centroid–centroid distances = 3.635 (2)–3.803 (3) Å].


Comment
There are a lot of publications on coordination chemistry of pyrazole-based chelating ligands which present versatile coordination geometry and nuclearity (Mukherjee, 2000;Mukherjee & Sarka, 2003). The suitable structure and high stability of pyrazoles, in addition to the ability of their deprotonated form to act as powerful nucleophiles in substitution reactions, have made them good candidates for incorporation in the design of new ligands. The easy control of the electronic and steric properties of the pyrazolyl-derived ligands by introducing different substituents in the pyrazolyl rings is another advantage and expands the domain of pyrazole-type ligands. As part of a general study of pyrazole ligands (Hossaini Sadr et al., 2005;Hossaini Sadr et al., 2004), we have determined the crystal structure of the title compound.

Experimental
The title compound was synthesized by adding dry CuCl 2 (1 mmol, 134 mg) to a solution of 4-methyl-3,5-diphenyl-1Hpyrazole (2 mmol, 468 mg) in THF (30 ml). The mixture was stirred for 12 hour. The resultant yellow solution was filtered and the solid phase washed by ether and dried in vacuo. Orange single crystals of the title compound suitable for X-ray structure determination were recrystallized from acethonitrile by slow evaporation of the solvent at room temperature over several days.

Refinement
The N-bound atoms was located in a difference Fourier map and refined freely. All other H atoms were positioned geometrically and refined using a riding model, with C-H = 0.93-0.96 Å and with U iso (H) = 1.2U eq (C) or 1.5U eq (C) for methyl H atoms.

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.