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

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.