Are ipr-satisfying structures most stable for Sc_3@C_(82) AND Sc@C_(82)?

摘要

In the study of endohedral metallofullerenes, the structural determination is currently of central interest. As reviewed recently [1,2], this has been successfully achieved for representative mono- and dimetallofullerenes such as Ca@C_(82), Sc@C_(82), Sc_2@C_(842), and La_2@C_(80) through a close interplar between theoretical prediction and experiment. Interest is now directed toward the structural determination of polymetallofullerenes. It has been shown that more than two Sc atoms can be trapped inside the higher fullerene cages to form soluble and relatively air-stable endohedral metallofullerenes [3,4]. Because of the difficulty in producing the pure samples in large quantities, the experimental characterization has been hindered. Meanwhile, the purification and isolation have been achieved for Sc_3@C_(82) [5] and Sc_4@C_(82) [6]. The EPR spectrum [3-5,7,8] and redox properties [9] have been measured for Sc_3@C_(82). However, the structures and electronic properties are still elusive and disputable.