Aquabis(3,5-dimethyl-1H-pyrazole-κN 2)(oxydiacetato-κ3 O,O′,O′′)copper(II) dihydrate

In the title compound, [Cu(C4H4O5)(C5H8N2)2(H2O)]·2H2O, the CuII cation assumes a distorted octahedral coordination geometry formed by two 3,5-dimethyl-1H-pyrazole ligands, one oxydiacetate (ODA) dianion and one coordinated water molecule. The tridentate ODA ligand chelates to the Cu cation in a facial configuration with a longer Cu—O bond [2.597 (3) Å], and both chelating rings display envelope conformations. In the molecule, the two pyrazole rings are twisted with respect to each other at a dihedral angle of 57.5 (3)°. Extensive intermolecular O—H⋯O and N—H⋯O hydrogen bonding is present in the crystal structure.

In the title compound, [Cu(C 4 H 4 O 5 )(C 5 H 8 N 2 ) 2 (H 2 O)]Á2H 2 O, the Cu II cation assumes a distorted octahedral coordination geometry formed by two 3,5-dimethyl-1H-pyrazole ligands, one oxydiacetate (ODA) dianion and one coordinated water molecule. The tridentate ODA ligand chelates to the Cu cation in a facial configuration with a longer Cu-O bond [2.597 (3) Å ], and both chelating rings display envelope conformations. In the molecule, the two pyrazole rings are twisted with respect to each other at a dihedral angle of 57.5 (3) . Extensive intermolecular O-HÁ Á ÁO and N-HÁ Á ÁO hydrogen bonding is present in the crystal structure.

Comment
Complexes with pyrazole-based ligands are a frequent subject of chemical investigations giving an opportunity for a better understanding the relationship between the structure and the activity of the active site of metalloproteins (Haanstra et al. 1990). Nowadays, attention is paid to the design of various pyrazole ligands with special structural properties to fulfill the specific stereochemical requirements of a particular metal-binding site (Mukherjee, 2000). In our systematic studies on transition metal complexes with the pyrazole derivatives, the title compound was prepared and its X-ray structure is presented here The molecular structure of the title compound is shown in Fig. 1. The complex has a distorted octahedral coordination geometry formed by two 3,5-dimethyl-1H-pyrazole ligands, an oxydiacetate (ODA) dianion and a coordinated water molecule.
Monodentate ligand 3,5-dimethyl-1-H-pyrazole coordinated to the Cu(II) atom by N atoms of pyrazole rings with the 2.015 (4) Å and 1.996 (4) Å of Cu-N bound distance. The adjacent molecules are linked together via O-H···O and N-H···O hydrogen bonding (Table 1) occours between carboxy groups of oxydiacetate dianion and uncoordinated N atom of 3,5-dimethyl-1-H-pyrazole and coordinated water to form the supra-molecular structure as shown in Fig. 2 and Table 1.
The tridentate ODA chelates to Cu(II) atom in a facial configuration, similar to that found in an ODA complex of Cu(II) (Wu et al., 2003). Two carboxyl groups of ODA monodentately coordinate to the Cu(II) atom with the 2.020 (3) Å and 1.959 (3) Å of Cu-O31 and Cu-O33 respectively. Uncoordinated carboxyl oxygen atoms O32 and O34 are hydrogen bonded to the hydrogen atoms of coordinated water of the neighboring complex molecule, as shown in Fig. 2 and Table 1.
The uncoordinated carboxyl oxygen atom O32 is hydrogen bonded to the hydrogen atoms of lattice watter molecule and coordinated water of the neighboring complex molecule respectively.

Refinement
Pyrazole H atoms and water H atoms were located in a difference Fourier map and included in the structure factor calculations with fixed positional parameters, and U iso (H) = 1.2U eq (N) or 1.5U eq (O). H atoms on carbon atoms and on oxygen (coordinated and lattice water) were placed in calculated positions, with C-H distances = 0.93 Å (aromatic, pyrazole ring), 0.97 Å (methylene group), 0.96 Å (methyl group), with O-H distances = 0.85 Å, and were included in the final cycles supplementary materials sup-2 of refinement in riding mode with U iso (H) = 1.2U eq (C(aromatic and methylene)) and U iso (H) = 1.5U eq (C(methyl) and O(water)) respectively. Fig. 1. The molecular structure of (I) with 30% probability displacement ellipsoids, dashed lines showing hydrogen bonding [symmetry code: (i) -x, 1-y, 1-z, (ii) 1+x, y, z].

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.