Synthesis, crystal structure and magnetic properties of an octanuclear cerium(III) complex of pyridine-2,6-dicarboxylate

Abstract

An octanuclear compound of cerium(III), [Ce8(Pydc)10(HPydc)4.22H2O].11H2O (1) (Pydc = pyridine-2,6-dicarboxylate anion) was prepared under mild solvothermal conditions and its crystal structure was determined by single-crystal X-ray diffraction. Three kinds of coordination environments are observed, which include: [Ce(Pydc)3], [Ce(Pydc)(H2O)4(O,O)], and [Ce(H2O)7(O,O)]. Each cerium atom in 1 is nine-coordinated but two different geometries are found. The Ce1 and Ce2 atoms exhibit a nearly tricapped trigonal prismatic CeN3O6 geometry, while Ce3 and Ce4 possess CeNO8 and CeO9 coordination polyhedra, which approximate to slightly distorted mono-capped square antiprisms having 12 triangular faces. The Pydc ligands adopt tri-, tetra-, and penta-coordination modes through tridentate chelating and, μ2 and μ3-bridging modes, respectively. The clusters are joined by O–H···O hydrogen bonds to generate 3D supramolecular network. Magnetic susceptibility measurements for 1 indicate that the χm values obey the Curie-Weiss law. The overall magnetic behavior is typical for the presence of antiferromagnetic exchange coupling interactions between the cerium(III) ions.