1. Contribution from the Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne, EPFL, Batochime, 1015 Lausanne, Switzerland, Département de Chimie, associé au CNRS, Ecole Normale Supérieure, 24 Rue Lhomond, 75231 Paris Cedex 05, France, and Kemisk Institut, Aarhus Universitet, Langelandsgade 140, 8000 Aarhus C, Denmark