Poly[[diaqua-(μ(8)-benzene-1,2,4,5-tetra-carboxyl-ato)calciumzinc] monohydrate]

In the title complex, {[CaZn(C(10)H(2)O(8))(H(2)O)(2)]·H(2)O}(n), the Zn(II) ion is coordinated by four O atoms from four benzene-1,2,4,5-tetra-carboxyl-ate anions in a distorted tetra-hedral geometry. The Ca(II) ion is eight-coordinated by six O atoms from four benzene-1,2,4,5-tetra-carboxyl-ate anions and by two water mol-ecules in a distorted square-anti-prismatic geometry. The Ca(II) and Zn(II) ions and the lattice water mol-ecule are located on twofold rotation axes; the centroid of the benzene-1,2,4,5-tetra-carboxyl-ate anion is located on a centre of inversion. The μ(8)-bridging mode of the anion results in the formation of a three-dimensional structure with channels extending along [100] in which lattice water mol-ecules are situated. Inter-molecular O-H⋯O hydrogen bonds involving the coordinating and lattice water mol-ecules as donors and the carboxyl-ate O atoms and lattice water mol-ecules as acceptors are present in the structure.