Two Closely Related Lanthanum Phosphonate Frameworks Formed by Anion-Directed Linking of Inorganic Chains

Two novel three-dimensional lanthanum coordination polymers have been prepared with the phosphonic acid H2O3PCH2N(C2H4)2NCH2PO3H2 (LH4). La2(LH2)2(LH4)Cl2 (I) and La2(LH2)2(LH3)Cl (II) arise from similar hydrothermal
reactions but differing sources of La. A one-dimensional “lanthanum-phosphate” chain, comprising corner-linked
LaO7 and PO3C polyhedra, forms the basis for the two different structures. The two structures differ in the mode
of connectivity of the inorganic chains via the phosphonate groups. Both materials include extraframework chloride
ions, the different amounts of which apparently direct the polytypic structures. In II, the chloride ions are incorporated
in a noncentrosymmetric manner leading to a polar framework topology.