1. Department of General and Inorganic Chemistry, University of Pardubice, Čs. Legií 565, 53210 Pardubice, Czech Republic, Fax: +420‐40‐603‐7068
2. Curent address: School of Chemistry, University of St Andrews, Purdie Building, KY16 9ST, St Andrews, Scotland, UK
3. Department of Inorganic Chemistry, Martin‐Luther‐Universität Halle‐Wittenberg, Kurt‐Mothes‐Straße 2, 06120 Halle (Saale), Germany