1. Department of Inorganic Chemistry, Charles University in Prague, Hlavova 2030, 128 40 Prague 2, Czech Republic, Department of Environmental and Life Sciences, University of Eastern Piedmont, “A. Avogadro”, Via Bellini 25/G, I-15100 Alessandria, Italy, Department of Chemistry, Emory University, 1515 Dickey Drive, Atlanta, Georgia 30322, and Department of Chemistry I. F. M., University of Turin, Via P. Giuria 7, I-10125 Torino, Italy