A unique two-dimensional coordination network of 1-benzofuran-2,3-dicarboxylate with lanthanum(III) obtained by solvothermal synthesis.

The title compound, poly[bis[diaqualanthanum(III)]-tris(mu-1-benzofuran-2,3-dicarboxylato)], [La(2)(C(10)H(4)O(5))(3)(H(2)O)(4)](n), was obtained under solvothermal conditions by reacting lanthanum trinitrate hexahydrate with 1-benzofuran-2,3-dicarboxylic acid in a strongly basic environment. It forms an extended two-dimensional coordination network, wherein every lanthanum ion links to four deprotonated diacid ligands, while two of the latter bridge between adjacent metal cations. The component species are additionally linked to one another by hydrogen bonds. The polymeric arrays are tightly stacked one on top of the other, without incorporating any solvent in the interface zones between them, which are lined with the lipophilic benzofuran residues. This study provides the first example of coordination networking with the aid of the 1-benzofuran-2,3-dicarboxylate ligand.