1. Dutch Polymer Institute, Center for Catalytic Olefin Polymerisation, Stratingh Institute for Chemistry and Chemical Engineering, University of Groningen, Nijenborgh 4, 9747 AG Groningen, Netherlands, Fax: +31‐50‐363‐4315
2. Dutch Polymer Institute, Institute for Molecules and Materials, Metal‐Organic Chemistry, Radboud University Nijmegen, P. O. Box 9010, 6500 GL Nijmegen, Netherlands, Fax: +31‐24‐355‐3450