1. Department of Inorganic and Analytical Chemistry, A. József University, 6701 Szeged, P.O. Box 440, Hungary, Laboratoire de Chimie Physique Organique et Colloidale, UMR SRSMC CNRS No. 7565, Université Henri PoincaréNancy I, B.P. 239, F-54506 Vandoeuvre-lès-Nancy Cedex, France, Research Group on Biocoordination Chemistry of the Hungarian Academy of Sciences, A. József University, 6701 Szeged, P.O. Box 440, Hungary, and Department of Inorganic Chemistry, University of Palermo, Palermo, Italy