Poly[[hexa­aqua­bis­(μ3-pyrimidine-4,6-dicarboxyl­ato)dicalcium] dihydrate]

The polymeric structure of the title compound, {[Ca2(C6H2N2O4)2(H2O)6]·2H2O} n , is built up of mol-ecular layers composed of Ca(II) ions bridged by both ligand N and O atoms with one of the O atoms being bis-monodentate. Two adjacent Ca(II) ions are bridged by these O atoms, forming a centrosymmetric dimer which is the building unit of the structure. The dimers are nodes of a cross-linked mol-ecular layer parallel to (101). The Ca(II) ion is coordinated by two bidentate ligands, one monodentate ligand and three water mol-ecules in the form of a distorted polyhedron with a coordination number of eight. Solvate water mol-ecules located between adjacent layers participate as donors and acceptors in a system of hydrogen bonds in which coordinating water mol-ecules also act as donors and non-coordinating carboxyl-ate O atoms act as acceptors.