1. Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona 85287-1604, Institut de Biologie Physico-Chimique, UMR 7141 CNRS-Université Pierre et Marie Curie, 75005 Paris, France, Department of Chemistry, University of Alabama, Tuscaloosa, Alabama 35487, and Department of Chemical Sciences, University of Padua, Via Marzolo 1, 35131 Padova, Italy