Synthesis and structure of [Ce2(H2O)3](C2O4)2.5(H3C2O3) and Ce2(C2O4)(H3C2O3)4: The latter structure presents an interesting new framework, with 2-fold interpenetration

Single crystals of two cerium complexes, with mixed-ligands oxalate and glycolate, have been prepared in a closed system, at 200 °C for one month: [Ce2(H2O)3](C2O4)2.5(H3C2O3) 1 and Ce2(C2O4)(H3C2O3)42. 1 crystallizes in the orthorhombic system, space group Pbca, with a=13.0090(13)Å, b=10.3870(8)Å, and a=22.102(3)Å while 2 crystallizes in the tetragonal system, space group P42/nbc, with a=11.7030(4)Å, c=13.2570(2)Å. For both complexes, the three-dimensional framework structure is built up by the linkages of the cerium and all the oxygen atoms of oxalate and glycolate ligands. For 2, its structure presents a nice case of two 3D identical sub-lattices, with 2-fold interpenetration. The only link between these two sub-lattices is assumed by strong hydrogen bonds between the hydroxyl function of the glycolate and the oxygen atoms of the oxalate. The schematized framework of 2, including only the cerium atoms, can be compared to that of cooperite (PtS).For 1, the two independent cerium have 9- or 10-fold coordination, forming a distorted monocapped or bicapped square antiprism polyhedron while for 2, the two independent cerium present 8-fold coordination, forming an almost regular dodecahedron. A quite relevant feature of 2 is the complete absence of water. 2 has been extended to other lanthanides (Ln=Ce…Lu, yttrium included) leading to a family, which has been characterized by infra-red and thermal analysis.