Scandium Clusters in Fullerene Cages

The production and spectroscopic characterization of fullerene-encapsulated metal-atom clusters is reported. In particular, both solution and solid-state electron paramagnetic resonance (EPR) spectra of Sc 3 C 82 have been obtained. ScC 82 also gives an EPR spectrum, but Sc 2 C n species—the most abundant metallofullerenes in the mass spectrum—are EPR-silent even though Sc 2 is EPR-active in a rare-gas matrix at 4.2 K. The results suggest that the three scandium atoms in Sc 3 C 82 form an equilateral triangle—as was previously suggested for Sc 3 molecules isolated in a cryogenic rare-gas matrix. The spectrum of ScC 82 has features similar to those found earlier for LaC 82 and YC 82 , suggesting that it can also be described as a +3 metal cation within a -3 fullerene radical anion. An implication of this work is that production of macroscopic quantities of cluster-containing fullerenes may make possible the fabrication of exotic new structures with regular arrays of metal-atom clusters isolated in fullerene molecules, resulting in a new type of host/guest nanostructured material.