Poly[[triaqua­tri-μ(5)-tartrato-dilanthanum(III)] dihydrate]

In the title polymer, {[La(2)(C(4)H(4)O(6))(3)(H(2)O)(3)]·2H(2)O}(n), two symmetry-independent La(III) ions are nine-coordinated and display a distorted monocapped square-anti­prismatic geometry. One is coordinated by seven O atoms from four tartrate ligands and two water mol­ecules, the other by eight O atoms from five tartrate ligands and one water mol­ecule. The three tartrate ligands in the asymmetric unit act identically as μ(5)-ligands, which link lanthanum centres to form a three-dimensional coordination framework. An extensive network of hydrogen bonds is observed in the crystal structure, involving two uncoordinated water mol­ecules, one of which is disordered over two positions, with occupancies of 0.550 (13) and 0.450 (13).