Poly[tetra-aqua-bis-(μ(4)-thio-phene-2,5-dicarboxyl-ato)(μ(2)-thio-phene-2,5-dicarboxyl-ato)dieuropium(III)].

The three-dimensional coordination polymer, Eu(2)(C(6)H(2)O(4)S)(3)(H(2)O)(4), has been synthesized under hydro-thermal conditions. The asymmetric unit comprises one Eu(3+) cation, two aqua ligands and one and a half thiophene-2,5-dicarboxylate anions (the half-anion being completed by a twofold rotation axis). The Eu(3+) cation is eight-coordinated in a distorted dodeca-hedral geometry. The crystal structure features O-H⋯O hydrogen bonds.