Poly[μ-aqua-aqua-(μ-benzene-1,2,4,5-tetra-carboxyl-ato)gadolinate(III)potassium(I)]

In the title compound, [KGd(C(10)H(2)O(8))(H(2)O)(2)](n), the Gd(3+) ion is nine-coordinated by eight O atoms from five individual benzene-1,2,4,5-tetra-carboxyl-ate (btec) ligands and one water mol-ecule, and the K(+) ion is eight-coordinated by six O atoms from five individual btec ligands and two water mol-ecules. In the crystal, the btec half-mol-ecules are completed by crystallographic inversion symmetry. GdO(9) and KO(8) polyhedra are connected, forming layers in the ab plane, which are further inter-connected by μ(8)- or μ(12)-bridging btec ligands, forming a three-dimensional structure.