Poly[[tetraaquabis(μ3-pyridine-2,6-dicarboxylato)(μ2-pyridine-2,6-dicarboxylato)dilanthanum(III)] dihydrate]

Abstract

There are two independent LaIII cations in the polymeric title compound, {[La2(C7H3NO4)3(H2O)4]·2H2O}n. One is nine-coordinated in an LaN2O7 tricapped trigonal–prismatic geometry formed by three pyridine-2,6-dicarboxylate anions and two water molecules, while the other is ten-coordinated in an LaNO9 bicapped square-antiprismatic geometry formed by four pyridine-2,6-dicarboxylate anions and two water molecules. The two LaIII cations are separated by a non-bonding distance of 5.026 (3) Å. The pyridine-2,6-dicarboxylate anions bridge the LaIII cations, forming a three-dimensional polymeric complex. The crystal structure contains extensive classical O—H...O hydrogen bonds and weak intermolecular C—H...O hydrogen bonds. The crystal structure is further consolidated by π–π stacking between pyridine rings, the shortest centroid–centroid distance between parallel pyridine rings being 3.700 (5) Å.