The triclinic form of dipotassium cobalt(II) bis-(dihydrogendiphosphate) dihydrate

Abstract

In the title compound, K2Co(H2P2O 7)2·2H2O, the octa-hedrally coordinated Co 2+ ion lies on an inversion centre. Two bidentate dihydrogendiphosphate anions form the equatorial plane of the [CoO6] octa-hedron which is completed by two water mol-ecules in axial positions. This results in isolated {Co(H2O)2[H2P2O 7]2}4- entities linked into a three-dimensional network through K - O bonds and O - H⋯O hydrogen-bonding inter-actions involving the dihydrogendiphosphate anions and water mol-ecules. The dihydrogendiphosphate anion, (H2P2O7)2-, is bent and shows an almost eclipsed conformation.