1. Clausthal University of Technology; Institute of Organic Chemistry; Leibnizstrasse 6 38678 Clausthal-Zellerfeld Germany), Fax: (+49)-5323-722834
2. University of Helsinki; Laboratory of Inorganic Chemistry; Department of Chemistry; P.O. Box 55 (A.I. Virtasen aukio 1) 00014 Helsinki Finland