Structural study of endohedral dimetallofullerenes Sc2 @C84 and Sc2 @C74

Ab initio molecular orbital and density functional calculations are carried out to predict the structures of the Sc2 @C84 isomers. It is found that three structures with D2d, Cs, and C2v symmetry are close in energy and most stable. This agrees with the fact that three isomers have been isolated and purified for Sc2 @C84. The predicted endohedral D2d and Cs structures are consistent with the available experimental data. The structure and stability of Sc2 @C74 are also calculated and compared.