1. Institute of Sciences, Department of Chemistry, University of Koblenz-Landau, Universitätsstrasse 1, D-56070 Koblenz, Germany, Bayer AG, CH-P-PSA, Building N60, D-47812 Krefeld, Germany, and Institute of Inorganic and Analytical Chemistry, Friedrich-Schiller-Universität Jena, August-Bebel-Strasse 2, D-07743 Jena, Germany