1. Institute of Physical and Theoretical Chemistry, Graz University of Technology, Stremayrgasse 9, A-8010 Graz, Austria
2. Institute of Chemistry, Organic and Bioorganic Chemistry, University of Graz, Heinrichstraße 28, A-8010 Graz, Austria
3. Otto Diels Institute for Organic Chemistry, University of Kiel, Otto-Hahn-Platz 4, DE-24118 Kiel, Germany