Poly[[diaqua-(1,10-phenanthroline-κN,N')(μ(3)-4-sulfonato-benzene-1,2-di-car-boxyl-ato-κO:O,O:O)erbium(III)] dihydrate].

The 4-sulfophthalate trianion in the polymeric complex, {[Er(C(8)H(3)O(7)S)(C(12)H(8)N(2))(H(2)O)(2)]·2H(2)O}(n), bridges three water/phenanthroline-coordinated Er(III) ions to form a three-dimensional network architecture. The metal atom is further chelated by a carboxyl-ate group and is covalently bonded to a monodentate carboxyl-ate group as well as to a monodentate sulfonate group in a distorted square anti-prismatic geometry. The coordinating water molecules and the lattice water molecules, one of which is disordered over two positions [major component 65 (3)%], are hydrogen bonded to the network.