Syntheses, crystal structures, and magnetic properties of RE(III)-Cu(II) heteronuclear complexes with -methylacrylic acid

A series of carboxylate-bridged heteronuclear 3d-4f complexes have been prepared by reaction of REL3 (HL = CH2 = C(CH3)COOH) with Cu(NO3)2. A family of air-stable 2-D complexes [RECuL4(H2O)4]nLn (RE = La (1), Ce (2), Eu (3), and Gd (4)) have the same crystal system (monoclinic) and space group (P21/c). The chains which are made by the carboxylate-bridged alternating Cu(II)-RE(III) fragments spreading along the c-axis are linked through hydrogen bonds by uncoordinated carboxylates to form a 2-D network structure along the bc planes. Magnetic measurements showed that 1 and 2 have antiferromagnetic interaction between RE and Cu, but 4 exhibits ferromagnetic interaction. Eu ions show van Vleck behavior in 3.