1. Department of Chemistry, Ruder Bošković Institute, P.O. Box 1016, HR-10001 Zagreb, Republic of Croatia, Institute of General, Inorganic and Theoretical Chemistry, University of Innsbruck, Innrain 52a, A-6020 Innsbruck, Austria, and Institut für Meteorologie und Klimaforschung, Forschungszentrum Karlsruhe/Universität Karlsruhe, D-76021 Karlsruhe, Germany