1. Department of Chemistry, University of Calgary, University Dr. 2500, Calgary, Alberta, Canada T2N 1N4, Anorganisch-chemisches Institut Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland, Bayer Polymers AG, Bayer AG, BPO-IIS-INN-SYR-SPE, 51268 Leverkusen, Q 18, Germany