1. Department of Chemistry, City University of New York, Hunter College and the Graduate School, 695 Park Avenue, New York, New York 10021, Institute of Computational Chemistry and Department of Chemistry, University of Girona, 17071 Girona (Catalonia), Spain, and Facultad de Farmacia, Departamento Quimica Organica, Universidad de Valencia, Avda Vicente Andres Estelles, 46100 Burjassot (Valencia), Spain