Bis[μ-(3-acetyl-2-hydroxy-6-methyl-4H-pyran-4-one-κ3 O:O′,O′′)]diaquatetrakis(pyridine-κN)dicopper(II) diperchlorate

In the centrosymmetric binuclear cation of the title compound, [Cu(C8H7O4)(H2O)(C5H5N)2]2(ClO4)2, the CuII atoms are bridged by a pair of two dehydroacetate anions in a bis-/monodentate mode. The distorted octahedral N2O4 coordination sphere of the metal cation is completed by two pyridine N atoms and one O atom of a water molecule. The complex cations and the perchlorate counter anions are arranged in layers parallel to (100). O—H⋯O hydrogen bonds between the coordinating water molecules and the perchlorate anions constitute ribbons parallel to [10-1]. C—H⋯O hydrogen bonds are also observed.

In the centrosymmetric binuclear cation of the title compound, [Cu(C 8 H 7 O 4 )(H 2 O)(C 5 H 5 N) 2 ] 2 (ClO 4 ) 2 , the Cu II atoms are bridged by a pair of two dehydroacetate anions in a bis-/monodentate mode. The distorted octahedral N 2 O 4 coordination sphere of the metal cation is completed by two pyridine N atoms and one O atom of a water molecule. The complex cations and the perchlorate counter anions are arranged in layers parallel to (100). O-HÁ Á ÁO hydrogen bonds between the coordinating water molecules and the perchlorate anions constitute ribbons parallel to [101]. C-HÁ Á ÁO hydrogen bonds are also observed.
out according to the cytochrome P450 model (Ourari et al., 2008(Ourari et al., , 2011(Ourari et al., , 2012 The molecular structure of the complex binuclear and centrosymmetric cation of (I) is illustrated in Fig. 1 The crystal packing in (I) can be described by alterning layers of cations and tetrahedral perchlorate anions arranged parallel to (100) (Fig. 2). Intermolecular O-H···O hydrogen bonds (Table 2) between the coordinating water molecules and perchlorate anions constitute ribbons parallel to [101]; C-H···O hydrogen bonding interactions eventually links these constituents (Fig. 3).
Experimental 0.168 g (1 mmol) dehydroacetic acid and 0.373 g (1 mmol) copper bis-perchlorate hexahydrate were dissolved in 20 ml of methanol. To this solution 0.108 g (1 mmol) of 1,2-phenylendiamine was added with an excess of pyridine. The mixture was held under stirring and argon atmosphere for two hours. After that time a precipitate appeared that was recovered by filtration. The solid was washed several times with methanol before it was dried under vacuum (yield 64%).
From the resulting filtrate crystals were obtained by slow evaporation.

Refinement
The H atoms were localized on Fourier maps but introduced in calculated positions and treated as riding on their parent C atom with C-H = 0.96 Å (methyl) or 0.93 Å (aromatic) and with U iso (H) = 1.2U eq (C) or U iso (H) = 1.5U eq (methyl). H1W and H2W protons of the water molecule were located in a difference Fourier map and were refined isotropically with supplementary materials

Figure 1
The binuclear complex cation of (I) with the atom-labelling scheme. Displacement ellipsoids are drawn at the 50% Alternating polyhedra of (I) viewed along [001] showing ClO 4 tetrahedra in pink and CuN 2 O 4 octahedra in blue.

Special details
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s 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 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.