Further theoretical evidence for the exceptionally strong ferromagnetic coupling in oxo-bridged Cu(II) dinuclear complexes

The magnetic behavior of the oxo-bridged Cu(II) dinuclear complexes has been investigated using hybrid density functional methods (B3LYP) and a post-Hartree-Fock approach (difference-dedicated configuration interaction method, DDCI). Both methods confirm the strong ferromagnetic coupling predicted for such complexes at geometries close to the energy minimum. For large Cu-O-Cu bridging angles, the DFT calculations predict an increase, whereas the DDCI method predicts a decrease of the ferromagnetic interaction, a result that is associated with the different weight of the excited charge-transfer configurations.