1. Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, Department of Inorganic and Physical Chemistry, Faculty of Sciences, University of Antananarivo, P.O. Box 906, 101 Antananarivo, Madagascar, Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut 06520-8103, and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139