Lanthanum Endohedral Metallofulleropyrrolidines: Synthesis, Isolation, and EPR Characterization

Abstract
Lanthanum endohedral metallofulleropyrrolidines have been synthesized for the first time through addition of an azomethine ylide to La@C82-A in toluene. It was found that the addition reaction is very efficient and, to some extent, regioselective. Two major endohedral metallofulleropyrrolidines, a monoadduct and a bisadduct of La@C82-A with abundance ratio of ∼1:0.4, have been isolated by HPLC chromatography and characterized by mass spectrometry, UV/Vis-NIR absorption, and EPR spectroscopy. The electronic structure of La@C82-A has been modified slightly upon monoaddition and significantly upon bisaddition of the pyrrolidines.