1. Institut des Sciences Moléculaires (ISM, UMR CNRS 5255), University of Bordeaux, 351 Cours de la Libération, 33405 Talence, France
2. Unité de Chimie Physique Théorique et Structurale, Chemistry Department, Namur Institute of Structured Matter, University of Namur, B-5000 Namur, Belgium
3. Department of Industrial Chemistry “Toso Montanari″, University of Bologna, Viale Risorgimento 4, 40136 Bologna, Italy