title: Electrosynthesis of a Sc3N@I(h)-C80 methano derivative from trianionic Sc3N@I(h)-C80.
abstract: The electrosynthetic method has been used for the selective synthesis of fullerene derivatives that are otherwise not accessible by other procedures. Recent attempts to electrosynthesize Sc(3)N@I(h)-C(80) derivatives using the Sc(3)N@I(h)-C(80) dianion were unsuccessful because of its low nucleophilicity. Those results prompted us to prepare the Sc(3)N@C(80) trianion, which should be more nucleophilic and reactive with electrophilic reagents. The reaction between Sc(3)N@C(80) trianions and benzal bromide (PhCHBr(2)) was successful and yielded a methano derivative, Sc(3)N@I(h)-C(80)(CHPh) (1), in which the >CHPh addend is selectively attached to a [6,6] ring junction, as characterized by MALDI-TOF mass spectrometry and NMR and UV-vis-NIR spectroscopy. The electrochemistry of 1 was studied using cyclic voltammetry, which showed that 1 exhibits the typical irreversible cathodic behavior of pristine Sc(3)N@I(h)-C(80), resembling the behavior of other methano adducts of Sc(3)N@I(h)-C(80). The successful synthesis of endohedral metallofullerene derivatives using trianionic Sc(3)N@I(h)-C(80) and dianionic Lu(3)N@I(h)-C(80), but not dianionic Sc(3)N@I(h)-C(80), prompted us to probe the causes using theoretical calculations. The Sc(3)N@I(h)-C(80) trianion has a singly occupied molecular orbital with high spin density localized on the fullerene cage, in contrast to the highest occupied molecular orbital of the Sc(3)N@I(h)-C(80) dianion, which is mainly localized on the inside cluster. The calculations provide a clear explanation for the different reactivities observed for the dianions and trianions of these endohedral fullerenes.
authors.affiliation: Department of Chemistry, University of Texas at El Paso, El Paso, Texas 79968, USA.
authors.forename: Fang-Fang
authors.initials: FF
authors.lastname: Li
authors.forename: Antonio
authors.initials: A
authors.lastname: Rodríguez-Fortea
authors.forename: Ping
authors.initials: P
authors.lastname: Peng
authors.forename: Guillermo A
authors.initials: GA
authors.lastname: Campos Chavez
authors.forename: Josep M
authors.initials: JM
authors.lastname: Poblet
authors.forename: Luis
authors.initials: L
authors.lastname: Echegoyen