1. Department of Chemistry and Biochemistry, University of South Carolina, 631 Sumter Street, Columbia, South Carolina 29208, Department of Chemistry, University of Camerino, Via S. Agostino 1, 62032 Camerino MC, Italy, and Departamento de Química Inorgánica, Universidad de Extremadura, Avda de Elvas S/N, E-06071 Badajoz, España