Ferro- and antiferromagnetic coupling in a chlorido-bridged, tetranuclear Cu(II) complex

A bispidine-like ligand involving four pyridine-N and three aliphatic-N donor atoms forms a bimetallic species with CuCl2 in which all seven N-donors are bound and which aggregates in the crystal through double chloride-bridging to give a tetranuclear unit. The magnetism of this solid can be interpreted in terms of a relatively weak antiferromagnetic coupling between the two Cu(II) centres of the dinuclear subunits and a strong ferromagnetic coupling of the Cu(II) centres in different dinuclear units involved in the bis-chlorido bridge. In solution, the assembly decays into the dinuclear subunits and, in agreement with the solid state studies, the interaction between the corresponding Cu-II centres is shown to be primarily due to dipole-dipole coupling.