1. Chemistry Department, The University of Alabama, Shelby Hall, Box 870336, Tuscaloosa, Alabama 35487-0336, Unidad de Servicios de Apoyo en Resolución Analítica, Universidad Veracruzana, A. P. 575, Xalapa, Veracruz, México, Department of Chemistry, Washington State University, Pullman, Washington 99164-4630, Department of Chemistry, H. C. Brown Laboratory, Purdue University, West Lafayette, Indiana 47907-1393, and Department of Chemistry, Katholieke Universiteit Leuven, B-3001 Leuven, Belgium