(Invited) Metal-Cage Interactions in Actinide Mono-Metallofullerenes: Some Insights from Computations

Intensive research has been devoted to the family of closed-cage carbon nanostructures since the discovery of buckminsterfullerene in 1985.1 Endohedral metallofullerene La@C60, with La inside the cage void space, was already detected the same year and La@C82 was isolated few years later.2 During the last two decades, many different M atoms have been encapsulated inside carbon cages of different sizes, in particular those metals of the lanthanide series.3 More recently, the first metallofullerene containing an actinide, Th@C82, was isolated and characterized.4 Later, other mono-actinidofullerenes as non-IPR U@C80, Th@C80 and U@C76; or IPR U@C82, U@C84 and U@C86 have been also characterized.5 In these actinide endofullerenes, the actinide tends to act with oxidation state +4, which involves an important metal-cage interaction with significant covalent contributions. Consequently, the predictions made by the ionic model are less reliable than for lanthanofullerenes. We here analyze in detail this actinide-cage interaction focusing on symmetry aspects of the cage patterns that mostly stabilize the internal actinide. References Kroto, H. W.; Heath, J. R.; O’Brien, S. C.; Curl, R. F.; Smalley, R. E. Nature 1985, 318, 162-163. a) Heath, J. R.; O’Brien, S. C.; Zhang, Q.; Liu, Y.; Curl, R. F.; Kroto, H. W.;Tittel, F. K.; Smalley, R. E. J. Am. Chem. Soc. 1985, 107, 7779-7780; (b) Chai, Y.; Cuo, T.; Jin, C.; Haufler, R. E.; Felipe Chibante, L. P.; Fure, J.; Wang, L.; Alford, J. M.; Smalley, R. E. J. Phys. Chem. 1991, 95, 7564-7568. Popov, A. A.; Yang, S.; Dunsch, L. Chem. Rev. 2013, 113, 5989-6113. Wang, Y.; Morales-Martínez, R.; Zhang, X.; Yang, W.; Wang, Y.; Rodriguez-Fortea, A.; Poblet, J. M.; Feng, L.; Wang, S.; Chen, N. J . Am. C hem. Soc. 2017, 139, 5110-5116. a) Cai, W.; Abella, L.; Zhuang, J.; Zhang, X.; Feng, L.; Wang, Y.; Morales-Martínez, R.; Esper, R.; Boero, M.; Metta-Magaña, A.; Rodriguez-Fortea, A.; Poblet, J. M.; Echegoyen, L.; Chen, N. J. Am. Chem. Soc. 2018, 140, 18039-18050; b) Yao, Y.-R.; Roselló, Y.; Ma, L.; Puente Santiago, A. R.; Metta-Magaña, A.; Chen, N.; Rodriguez-Fortea, A.; Poblet, J. M.; Echegoyen, L. J. Am. Chem. Soc. 2021, 143, 15309-15318.