Density functional study of the exchange coupling in distorted cubane complexes containing the Cu4O4 core

A density functional study of the exchange coupling in two complexes with cubane structure is presented. One of them can be considered as a pair of binuclear hydroxo-bridged Cu(II) complexes and the second one is an alkoxo-bridged distorted cubane with S-4 symmetry. In the former complex, the ferromagnetic coupling is due to the nature of the hydroxo bridges, whereas in the latter the distortion of the Cu4O4 core induces ferromagnetic couplings despite the usual antiferromagnetic behavior expected for the alkoxo bridges. (C) 2001 Elsevier Science Ltd. All rights reserved.