A novel family of lanthanide complexes associating two ligands, glycolate and carbonate.: Synthesis and characterization of Ln2(H3C2O3)4(CO3) with Ln(III) = La, Ce and Nd

New lanthanide complexes involving the two ligands, glycolate and carbonate, have been prepared, as a pure phase, by reacting an aqueous suspension of the corresponding lanthanide formate and glycolic acid in closed reactor, under autogeneous pressure at 200 degrees C for one month. The structure of these compounds was determined from single-crystal X-ray method on neodymium complex. It crystallizes in the monoclinic system (space group P2(1)/n) with a three-dimensional framework structure. The coordination scheme of the two independent neodymium atoms is built up by 9 or 10 oxygen atoms from both glycolate and carbonate ligands. The carbonate group acts as a bismonodentate, bischelating ligand. One glycolate is bischelating while the three latter are chelating and monodentate. Infrared spectrum and thermogravimetric analysis of this family are also presented. A tentative explanation of its synthesis will be briefly discussed. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.