1. Contribution from the Departmant of Inorganic Chemistry, Technical University of Budapest, 1521 Budapest, Hungary, Photodynamics Research Center, The Institute of Physical and Chemical Research, 519-1399, Aoba, Aramaki, Aoba-ku, Sendai 980-0845, Japan, and Department of Chemistry, Graduate School of Science, Tohoku University, Aoba-ku, Sendai 980-8578, Japan