Structural modeling and magnetostructural correlations for heterobinuclear Cu(II)-Ni(II) complex

The magnetostructural correlation of model Cu(II)-Ni(II) heterobinuclear complexes was studied by using the broken symmetry approach within the framework of density functional theory. The antiferromagnetic coupling interaction is weakened with the decrease of the dihedral angle between the plane O1CuO2 and the plane O1NiO2 in the core moiety CuO1O2Ni of the model from 180 to 125degrees, in agreement with the experimental results. The ferromagnetic behavior was also predicted theoretically with dihedral angle less than 125degrees. The magnetic coupling interaction is reinforced with the increase of the bond angle Cu-O-Ni. The relationship between the magnetic coupling interaction and the spin density localized on the magnetic centers or on the bridging O atoms was investigated. The bond angle Cu-O-Ni for the model with lowest energy was determined and the theoretical value (104) is a little more than the experimental value (99degrees). (C) 2002 Wiley Periodicals, Inc.