Abstract of Publication No. 363
The superexchange interaction in cyano-bridged transition metal dimers is analysed by a
valence bond configuration interaction model in combination with fourth order
perturbation theory. Ferro- and antiferromagnetic contributions to the exchange splitting are
expressed in terms of metal-ligand hybridization matrix elements, metal-to-ligand,
ligand-to-metal, metal-to-metal charge transfer energies, and intra-atomic exchange integrals.
The formalism is simplified and we arrive at a two-parameter model, with which it is
possible to estimate magnetic ordering temperatures of cubic stoichiometric Prussian Blue
like phases containing first row transition metals. The relevance and applicability of our
theoretical results is demonstrated on critical temperatures reported in the literature. The
model accounts for both ferri- and ferromagnetic ordering temperatures. It is found that
cyanide is an efficient mediator of exchange due to the participation of the
p and p* orbitals to equal extent.