1. Department of Chemistry and Pharmacy Inorganic Chemistry Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) Egerlandstraße 1 91058 Erlangen Germany
2. Department of Physics University of Osnabrück Barbarastraße 7 49069 Osnabrück Germany
3. Present address: Department of Chemistry Ludwig-Maximilians-Universität München Butenandtstraße 5–13 81377 Munich Germany