1. Department of Chemistry and Process Technology, Chemistry, Mid Sweden University, S-851 70 Sundsvall, Sweden, Physical Chemistry I, Centre for Chemistry and Chemical Engineering, P.O. Box 124, University of Lund, S-221 00 Lund, Sweden, and Dipartimento di Chimica, Università degli Studi “La Sapienza”, p.le Aldo Moro 5, 00185 Roma, Italy