1. J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, v.v.i., Dolejškova 3, 182 23 Prague 8, Czech Republic
2. Faculty of Science, Charles University, 2030 Hlavova, 128 43 Prague 2, Czech Republic
3. Institute of Inorganic Chemistry of the Czech Academy of Sciences, v.v.i., Husinec-Řež 1001, 250 68 Řež, Czech Republic