1. Institute of Physical and Theoretical Chemistry, University of Regensburg, D-93040 Regensburg, Germany, CEA, IRAMIS, Service de Chimie Moléculaire (SCM), LIONS, F-91191 Gif sur Yvette Cedex, France, and Institut de Chimie Séparative de Marcoule−UMR 5257, CEA/CNRS/UMR/ENSCM−BP 17171−F-30207 Bagnols-sur-Cèze Cedex, France