1. Department of Chemistry, Philipps-University Marburg, Hans-Meerwein-Straße 4, 35043Marburg, Germany
2. Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470Mülheim an der Ruhr, Germany
3. Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Akad.Georgi Bontchev Street, Bl.11, 1113Sofia, Bulgaria
4. Institute of Inorganic Chemistry, University of Göttingen, Tammannstr. 4, D-37077Göttingen, Germany
5. LAB National des Champs Magnétiques Intenses, LNCMI─CNRS, 25 Martyrs Avenue, BP 166, 38042Grenoble Cedex 9, France
6. Institute of Physics, Charles University in Prague, Ke Karlovu 5, CZ-12116Prague, Czech Republic