1. Department of Chemistry, Bard College, P.O. Box 5000, Annandale-on-Hudson, New
York 12504, United States
2. Departament de Quı́mica
Inorgànica, Facultat de Quı́mica, Universitat de Barcelona, Diagonal 645, E-08028 Barcelona,
Spain
3. Department of Chemistry, Vassar College, Poughkeepsie, New York, United States