High-Yield Extraction of Endohedral Rare-Earth Fullerenes

The technique of high-temperature high-pressure extraction with pyridine has been successfully utilized to extract a wide variety of endohedral rare-earth fullerenes of the type Ln@C-2n (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb). Ln@C-80, Ln@C-82, and Ln(2)@C-80 for most of the rare-earth metals can be produced with high-yield and selectively extracted from the carbon-are evaporation soot. Metallofullerenes containing Sm, Eu, and Yb (which could have +2 oxidation states) are especially difficult to extract. Some possible reasons for the high-yield extraction are discussed. The laser desorption mass spectrometric characterization results indicate a relationship between the extraction yields of metallofullerenes and the oxidation states and ionic radii of the rare-earths.