Quantum Chemical Study on Endohedral Heteronuclear Dimetallofullerene M1M2@Ih-C80 toward Molecular Design

Structural and electronic properties on neutral and anionic species of M1M2@Ih-C80 including heteronuclear metal/lanthanides were theoretically investigated. Theoretical analysis demonstrates that M1M2@Ih-C80 can be categorized into three groups: (i) LaM@Ih-C80 (M = Ce, Pr), (ii) LaM@Ih-C80 (M = Sm, Eu), and (iii) GdM@Ih-C80 (M = Sc, Y, La, Lu). Molecular orbital analysis suggests that electron transfer from metal to cage is different for three groups because of the energy level of the metal-based molecular orbital and inherent oxidation state of metals. Thus, choosing suitable combinations of the heterometals for the encapsulation is an effective way to control the stability of M1M2@Ih-C80. The anionization can also stabilize the M1M2@Ih-C80 complexes, as confirmed for homonuclear cases. In addition, we found that the absorption spectra for the studied heterodimetallofullerenes are nearly independent of the metals encapsulated because the π → π* transitions on the cage are dominant even though metal orbi...