Hexaaquacobalt(II) 4,4′-(1,2-dihydroxyethane-1,2-diyl)dibenzoate monohydrate

The title compound, [Co(H2O)6](C16H12O6)·H2O, is composed of one 4,4′-(1,2-dihydroxyethane-1,2-diyl)dibenzoate anion lying on an inversion center, one [Co(H2O)6]2+ dicationic complex and a solvent water molecule located on mirror planes. In the crystal, a chain is constructed via O—H⋯O hydrogen bonds involving the carboxylate and hydroxyl groups of the organic anion; the chains are further connected into a three-dimensional framework by additional O—H⋯O hydrogen bonds between the [Co(H2O)6]2+ cations, solvent water molecules and the anions.

The title compound, [Co(H 2 O) 6 ](C 16 H 12 O 6 )ÁH 2 O, is composed of one 4,4 0 -(1,2-dihydroxyethane-1,2-diyl)dibenzoate anion lying on an inversion center, one [Co(H 2 O) 6 ] 2+ dicationic complex and a solvent water molecule located on mirror planes. In the crystal, a chain is constructed via O-HÁ Á ÁO hydrogen bonds involving the carboxylate and hydroxyl groups of the organic anion; the chains are further connected into a three-dimensional framework by additional O-HÁ Á ÁO hydrogen bonds between the [Co(H 2 O) 6 ] 2+ cations, solvent water molecules and the anions.
As shown in Figure

Experimental
A mixture of 4,4'-(1,2-dihydroxyethane-1,2-diyl)dibenzoate(0.5 mol, 0.15 g) and Co(NO 3 ) 2 (0.5 mol, 0.14 g) in 30 ml of absolute ethanol was heated under reflux for 6 h in the presence of 1-2 drops of NaOH. The reaction mixture was cooled to room temperature for 2 h. The light-red crystal was filtered off and washed several times using absolute ethanol.

Refinement
H atoms bound to C atoms were placed at calculated positions and were treated as riding on the parent atoms, with C-H = 0.93 Å(aromatic) and 0.98 Å(CH) and with U iso (H) = 1.2 U eq (C) H atoms of hydroxyl group and water molecules were

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq