1. Department of Chemistry, University of York, Heslington, York, YO10 5DD, United Kingdom, Department of Organic Chemistry, University of Nijmegen, NSRIM, 1 Toernooiveld, NL-6525 ED Nijmegen, The Netherlands, and Department of General Instrumentation, University of Nijmegen, 1 Toernooiveld, NL-6525 ED Nijmegen, The Netherlands