1. Contribution from the School of Chemistry, The University of Edinburgh, West Mains Road, Edinburgh, EH9 3JJ, U.K., Department of Chemistry, The University of Manchester, Oxford Road, Manchester, M13 9PL, U.K., Department of Chemistry, University of Florida, Gainesville, Florida 32611-7200, Laboratoire Louis Néel-CNRS, 38042 Grenoble, Cedex 9, France, Department of Chemistry and Biochemistry, The University of Bern, Freiestrasse 3, CH-3000, Berne 9, Switzerland, 1 Physikalisches Institut, Universitat...