Bis[2-(4-benzoyloxy-2-hydroxybenzoyl)-1-phenylethenolato]diethanolzinc(II)

The mononuclear title complex, [Zn(C22H15O5)2(C2H5OH)2], contains a ZnII atom (site symmetry ) surrounded by six O atoms of the keto groups of two substituted 1,3-diketonate ligands and of two ethanol molecules, resulting in a distorted octahedral coordination environment. The molecular configuration is stabilized by an intramolecular hydrogen bond between the phenolic hydroxy group and the adjacent keto group. The hydroxy group acts likewise as an acceptor of an intermolecular O—H⋯O hydrogen bond with the hydroxy group of the ethanol molecule as the donor. The hydrogen-bonding scheme leads to the formation of supramolecular layers parallel to (010).

The mononuclear title complex, [Zn(C 22 H 15 O 5 ) 2 (C 2 H 5 OH) 2 ], contains a Zn II atom (site symmetry 1) surrounded by six O atoms of the keto groups of two substituted 1,3-diketonate ligands and of two ethanol molecules, resulting in a distorted octahedral coordination environment. The molecular configuration is stabilized by an intramolecular hydrogen bond between the phenolic hydroxy group and the adjacent keto group. The hydroxy group acts likewise as an acceptor of an intermolecular O-HÁ Á ÁO hydrogen bond with the hydroxy group of the ethanol molecule as the donor. The hydrogenbonding scheme leads to the formation of supramolecular layers parallel to (010).

Table 2
Hydrogen-bond geometry (Å , ).  carboxypeptidase and carbonic anhydrase, where it is in a hard donor coordination environment of nitrogen and oxygen (Lipscomb & Strater, 1996;Bertini et al., 1994). Zinc has long been recognized as an important cofactor in biological molecules, either as a structural template in protein folding or as a Lewis acid catalyst that can readily adopt 4-, 5-or 6-coordination (Vallee & Auld, 1993). Studies of the structures and properties of the metal coordination sites in in zinc enzymes recently were in focus in the field of bioinorganic chemistry (Zhu et al., 2003). A couple of chemical systems have been developed to reproduce the zinc coordination core. On our continuation of the research in this field, the crystal structure of a mononuclear zinc(II) compound, (I), is reported here.
In the structure of (I), the Zn II atom is situated on an inversion center and adopts a slightly distorted octahedral coordination ( Fig. 1). It is surrounded by six O atoms from the keto groups of two 1,3-diketonate ligands and by two ethanol mo-  (Table 1). The two trans-angles at the zinc(II) center are 180° by symmetry; all angles around Zn1 are close to 90°, ranging from 85.93 (11) to 94.07 (11)°. In the crystal structure, intramolecular and intermolecular O-H···O hydrogen bonding leads to a layered assembly parallel to (010) ( Table 2; Fig. 2).

Experimental
To a ethanol solution (15 ml) of 3-hydroxy-4-(3-oxo-3-phenylpropanoyl)phenyl benzoic acid (0.36 g, 0.001mol), anhydrous zinc acetate (0.092 g, 0.0005 mol) was added at room temperature. After addition, the reaction mixture was refluxed for 30 min with stirring and then was filtered. Single crystals of the title compound were obtained by slow evaporation of the filtrate.

Refinement
All hydrogen atoms were placed in geometrically idealized positions and constrained to ride on their parent atoms, with

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.