On the magnetic coupling in asymmetric bridged Cu(II) dinuclear complexes: The influence of substitutions on the carboxylato group

A quantum chemical study is presented of the magnetic coupling in a series of Cu(II) dinuclear complexes with an asymmetric double bridge formed by a μ-carboxylato- and a μ-alkoxo ligand. The complexes have different substituents on the carboxylato group and show non-intuitive relative magnetic coupling strengths. We address the influence of the substituents and establish the relative importance of the two bridges for the magnetic coupling. Moreover, we give a quantitative estimate of the complementarity effect of the two ligands. Finally, the study of the magneto-structural correlations show that the angle between the planes formed by the atoms surrounding the Cu(II) atoms is the determining factor to explain the differences in the magnetic coupling observed in the complexes and that the electronic effect of the substituents is negligible.