Synthesis and magnetic studies of copper(II)-lanthanide(III) 5-bromosalicylideneglycylglycine

Abstract

IntroductionMagnetism of molecular complexes simultaneously comprising 3d and 4f metal ions has been the subject of investigation in the last few years. These compounds are important not only in preparative coordination chemistry but also to understand the mechanism of the magnetic interaction between 3d and 4f centres, which are potential magnetic materials. The magnetic interactions between rareearth and d block metal ions have been found to be weak, as one can expect given the relatively low covalency of the lanthanide-to-ligand bonds, but their effects are by no means negligible, producing profound modifications on the nature of the magnetic materials, depending on the nature of the lanthanides and 3d metal ions involved. In particular the copper(II)-gadolinium(III) couple has been extensively studied both from a structural as well as from magnetic point of view, in a number of binuclear Cu(II)-Gd(III) and polynuclear system with Cu 2 Gd, Cu 4 Gd, Cu 4 Gd 2 or (CuGd) n cores, bridged by phenoxo or multidentate ligand with hetero donating groups. The most frequently used ligands are polydentate Schiff base. The nature of the magnetic interaction between Cu(II) and Gd(III) ions within polynuclear species is, in most cases, ferromagnetic, as in dinuclear complexes. From a magnetic point of view, well isolated dinuclear complexes have a great advantage for they only contain the Cu-Gd interaction parameter. On the contrary, in complexes of higher nuclearity, as in trinulcear Cu 2 Gd complexes for example, we have to take into account the desired Cu-Gd interaction but also a possible Cu-Cu interaction (antiferromagnetic, ferromagnetic or equal to zero) [1][2][3][4][5][6][7][8][9][10][11][12][13][14].As a continuation of our earlier work here we reported the magnetic properties of original