Poly[triaqua(μ-butane-1,2,3,4-tetracarboxylato)dicadmium(II)]

The asymmetric unit of the title Cd-II coordination polymer, [Cd-2(C8H6O8)(H2O)(3)](n), contains two crystallographically independent Cd-II cations, one-half each of two independent anionic butane-1,2,3,4-tetracarboxylate units (L) and three water molecules. Both anionic units lie on inversion centers. One of the Cd-II ions is six-coordinated by four carboxylate O atoms from four L anions and two water O atoms in a distorted octahedral coordination environment. The other Cd-II ion is eight-coordinated by seven carboxylate O atoms from four L anions and one water O atom. The anionic units bridge neighboring Cd-II centers, forming a three-dimensional framework. O-H center dot center dot center dot O hydrogen-bonding interactions between the water molecules and carboxylate O atoms further stabilize the structure.