Cu-Ln complexes with a single μ-oximato bridge

Two original dinuclear (Ln=Yb. 3 and Ln=Er, 4) and one trinuclear Cu-II-Ln(III)-Cu-II (Ln=Gd, 5) complexes derived from a polydentate non symmetrical Schiff base ligand H2L have been prepared. The ligand possesses two functions (phenol and xi me) able to coordinate the Ln ions, but structural studies (X-ray diffraction and powder X-ray diffraction) show that the Cu-II and Ln(III) ions are only bridged by the oximato (N-O) pair The missing phenoxo bridge is replaced by a surprising pseudo-bridge involving one oxygen atom of the nitrato anion linked to the Cu and Ln ions according to a eta(2).eta(1).mu mode Although this latter contact has no role from the magnetic point of view, it introduces a large deformation of the unique bridging network The Cu-Yb complex 3 and the trinuclear Cu-Gd-Cu complex 5 present antiferromagnetic interactions, with a J(CuGd) interaction equal to -1.25 cm(-1) in 5. The genuine single bridge can be considered as responsible for the antiferromagnetic character of the interaction (C) 2010 Academic des sciences Published by Elsevier Masson SAS All rights reserved.