1. Faculty of Chemistry and Mineralogy, Institute of Inorganic Chemistry, Universität Leipzig, Johannisallee 29, 04103 Leipzig, Germany, Fax: +49‐341‐973‐9319, http://www.uni‐leipzig.de/chemie/hh
2. Faculty of Chemistry and Chemical Engineering, Babeş‐Bolyai University, M. Kogălniceanu 1, 400084 Cluj‐Napoca, Romania