1. Department of Chemistry, University of Oslo, P.O. Box 1033, N-0315 Oslo, Norway, Institut Lavoisier, UMR CNRS 8180, Université de Versailles Saint Quentin en Yvelines, 45, avenue des Etats-Unis, 78035 Versailles, France, and Department of Chemistry IFM & NIS Centre of Excellence, University of Torino, Via Giuria 7, I-10125 Torino, Italy