1. Department of Chemistry, University of Virginia, Charlottesville, Virginia, 22904-4319, Department of Theoretical Chemistry, Chemical Center, University of Lund, POB 124, 2-221 00 Lund, Sweden, Unidade de Ciências Químicas e Radiofarmacêuticas, Instituto Tecnológico e Nuclear/CFMCUL, 2686-953 Sacavém, Portugal, and Chimie Métallurgique des Terres Rares, ICMPE, CNRS, 2/8 rue Henri Dunant, 94320 Thiais, France