1. Department of Chemistry, University of Southern California, Los Angeles, California 90089-0482, USA
2. Q-Chem, Inc., 6601 Owens Drive, Suite 105, Pleasanton, California 94588, USA
3. Department of Chemistry, University of Southern California, Los Angeles, California 90089-0482, USA and Institut für Physikalische Chemie, Johannes Gutenberg-Universität Mainz, Duesbergweg 10-14, D-55128 Mainz, Germany