1. Department of Chemistry, University of California, Berkeley, California 94720, Department of Chemistry and Biochemistry, San Diego State University, San Diego, California 92182, CNRS, UPR 8641, Centre de Recherche Paul Pascal (CRPP), Equipe “Matériaux Moléculaires Magnétiques”, 115 avenue du Dr. Albert Schweitzer, 33600 Pessac, France, and Université de Bordeaux, UPR 8641, Pessac F-33600, France