Hydrothermal Synthesis, Crystal Structure, and Characterizations of a New Lanthanide Oxalatophosphonate with a 3D Framework Structure

A new lanthanide oxalatophosphonate with a 3D framework, [Nd2(HL)(C2O4)2(H2O)3]·H2O (1) (H3L = HOOCC5H9NCH2PO3H2) was synthesized by hydrothermal reaction at 140 °C by using carboxyphosphonic acid as phosphonate ligand and oxalate as additional metal linker. It was structurally characterized by single-crystal as well as powder X-ray diffraction methods, infrared spectroscopy, elemental analysis, and thermogravimetric analysis. In compound 1, the interconnection of the neodymium(III) ions by chelating and bridging oxalate anions leads to a neodymium oxalate layer, these layers are further bridged by carboxyphosphonate ligands to form a 3D framework structure. It is interesting that the result of these connections is the formation of 20- and 16-atom rings that are parallel to one another and run in the b axis direction.