1. Department of Chemistry, Faculty of Science, Masaryk University, Kotlářská 2, 611 37 Brno, Department of Inorganic Chemistry, Faculty of Science, Palacký University, Křížkovského 10, 771 47 Olomouc, and Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nám. 2, 166 10 Prague 6, Czech Republic