1. Inorganic Chemistry 1, Department of Chemistry, Lund University, P.O. Box 124, S-221 00 Lund, Sweden, Diptartimento di Chimica Fisica e Inorganica, Università di Bologna, Viale de Risorgimento 4, I-40136 Italy, and Department of Pharmaceutics, Astra Draco AB, P.O. Box 34, S-221 00 Lund, Sweden