Long-range superexchange interaction in copper(II)-dimers: A quantum mechanical calculation

Self consistent field-Møller-Plesset (SCF-MP) calculations have been performed to reproduce the experimentally observable exchange interaction J as a function of long distances in Cu-dimers. Four models with different extended bridging ligands were chosen to cover a Cu(II)Cu(II) separation of ca. 7.0–11.0 Å. The calculated J values fit the limiting function of R.E. Coffman and G.R. Buettner (J. Phys. Chem. 18, 2387 (1979)] very well. Nevertheless the tendency of the J values was discussed rather than their absolute values. The reasons for the relatively strong measured exchange interaction of 2J = −140 cm⁻¹ for H = −2J₁₂S₁S₂ for the same terephthalato-bridged Cu(II)Cu(II) dimers with a CuCu separation of 11.25 Å were discussed.