Crystal structure of chlorido{1-(2,3-dimethyl-5-oxido-1-phenyl-1H-pyrazol-2-ium-4-yl-κO)-2-[3-methyl-5-oxo-1-phenyl-4,5-dihydro-1H-pyrazol-4-ylidene-κO]hydrazin-1-ido-κN 1}copper(II) from laboratory X-ray powder data

In the title copper(II) complex containing chloride and a derivative of 3-methyl-1-phenyl-4-hydrazopyrazolin-5-one, acting as a tridentate ligand, the CuII atom is in a slightly distorted square-planar coordination. Molecules stack in columns along the c axis.

In the title compound, [Cu(C 21 H 19 N 6 O 2 )Cl], the Cu II atom is in a slightly distorted square-planar coordination involving two O atoms from the pyrazolone rings [Cu-O = 2.088 (10) and 1.975 (10) Å ], an N atom of the azo group [Cu-N = 2.048 (13) Å ] and a chloride anion [Cu-Cl = 2.183 (5) Å ]. The organic anions act as tridentate chelating ligands. The molecules stack in columns along the c axis.

Chemical context
Derivatives of 3-methyl-1-phenyl-4-hydrazopyrazolin-5-one and their metal complexes are well known dyes and possess a wide spectrum of biological activity (Wiley & Wiley, 2008;Liu et al., 2007;Hallas & Towns, 1996). Despite the fact that quite a number of metal complexes are known to exist, the determination of their crystal structures is rather problematic because of the high dispersity of azo-dyes. Only few of them have been structurally characterized (El-Hefnawy et al., 1992;Casas et al., 2007;Emeleus et al., 2001;Zaitseva et al., 1981;Kovalchukova et al., 2012;Bansse et al., 1997;Lalor et al., 1995). All of them show two similar coordination modes of the organic molecules: bidentate chelating for those with no donating atoms in the arylazo fragment or tridentate chelating for ligands with an extra coordinating group.

Supramolecular features
In the crystal, the molecules are stacked in columns along the c axis in such a way that molecules in neighboring columns at the same level are rotated by approximately 90 (Fig. 2). No CuÁ Á ÁCu interactions between Cu II atoms of neighboring molecules are found.

Database survey
The crystal structures of metal complexes with azopyrazolone derivatives are described by El-Hefnawy et al.

Synthesis and crystallization
The title compound was prepared by mixing equimolar ethanol solutions of the organic ligand and copper(II) chloride. The reaction mixture was stirred under reflux for three hours. After cooling, fine brown needles of the title complex precipitated. These were then filtered off, washed using a small amount of ethanol and dried over P 2 O 5 .

Refinement details
The X-ray powder diffraction data were collected using a Huber G670 Guinier camera (Cu-K 1 radiation, = 1.54059 Å ) equipped with an image-plate detector. The monoclinic unit-cell dimensions were determined using three indexing programs: TREOR90 (Werner et al., 1985), ITO (Visser, 1969) and AUTOX (Zlokazov, 1992(Zlokazov, , 1995. Based on systematic extinctions, the space group was determined to be P2 1 /c. The unit-cell parameters and space group were further tested using a Pawley (1981) fit and confirmed by the crystal structure solution.
The crystal structure was solved with the use of a simulated annealing technique (Zhukov et al., 2001). The initial molecular model of the title complex was obtained using density functional theory (DFT) calculations in vacuo using the quantum-chemical code Priroda (Laikov, 1997(Laikov, , 2004(Laikov, , 2005Laikov & Ustynyuk, 2005) employing the generalized-   View of the crystal packing along the b axis. gradient approximation (GGA) and PBE exchange correlation function (Perdew et al., 1996). In simulated annealing runs (without H atoms), the total number of varied degrees of freedom (DOF) was eight: three translational, three orientational and two torsional ones for the rotation of the two phenyl rings. The solution was fitted with the program MRIA (Zlokazov & Chernyshev, 1992) in a bond-restrained Rietveld refinement using a split-type pseudo-Voigt peak-profile function (Toraya, 1986) and symmetrized harmonics expansion up to the 4th order (Ahtee et al., 1989;Jä rvinen, 1993) for the texture formalism. Restraints were applied to the intramolecular bond lengths and contacts (< 2.8 Å ) where the strength of the restraints was a function of interatomic separation and, for intramolecular bond lengths, corresponded to an r.m.s. deviation of 0.02 Å . Additional restraints were applied to the planarity of aromatic rings with the attached atoms, with a maximum allowed deviation from the mean plane of 0.03 Å . All non-H atoms were refined isotropically. H atoms were positioned geometrically (C-H = 0.93-0.96 Å ) and not refined. The experimental and calculated diffraction profile after the final bond-restrained Rietveld refinements is shown in Fig. 3. Crystal data, data collection and structure refinement details are summarized in Table 1.  (Huber, 2002), MRIA (Zlokazov & Chernyshev, 1992), (Zhukov et al., 2001), PLATON (Spek, 2009), and SHELXL97 (Sheldrick, 2008). Crystal structure of chlorido{1-(2,3-dimethyl-5-oxido-1-phenyl-1H-pyrazol-2-