1. Departments of Chemistry, The University of Arizona, Tucson, Arizona 85721, The University of Kansas, Lawrence, Kansas 66047, Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana 46556, Vanguard University, Costa Mesa, California 92626, Department of Pharmaceutical Chemistry, University of Kansas, Lawrence, Kansas 66047 and the Institute of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, 8093 Zürich, Switzerland