1. Laboratoire LCP, Universités d’Aix-Marseille I, II, III et CNRS, Avenue Escadrille Normandie-Niemen, 13 397 Marseille Cedex 20, France, Chemical Research Center, Institute of Structural Chemistry, P.O. Box 17, H-1525 Budapest, Hungary, and Steacie Institute for Molecular Sciences, National Research Council of Canada, 100 Sussex Drive, Ottawa, Ontario K1A 0R6, Canada