1. Swiss Federal Institute of TechnologyETH ZurichDepartment of Chemistry and Applied Biosciences Vladimir-Prelog-Weg 2 8093 Zurich Switzerland
2. Current Address: Otto-von-Guericke-Universität MagdeburgInstitut für Chemie Universitätsplatz 2 39108 Magdeburg Germany
3. University of CologneDepartment of ChemistryInstitute of Inorganic Chemistry Greinstrasse 6 50939 Cologne Germany
4. Martin-Luther-Universität Halle-WittenbergInstitut für Chemie Kurt-Mothes-Strasse 2 06120 Halle (Saale) Germany