(Invited) Electronic Structure and Bonding in Endohedral Actinidofullerenes

Abstract

Endohedral metallofullerenes (EMF), i.e. fullerenes that contain metal atoms or metal clusters in their inner void space, have been intensively studied since the isolation of La@C82.1 In 1999, the synthesis and characterization of the first clusterfullerene Sc3N@C80 using the Krätschmer-Huffman method was a milestone in the field of EMF.2 Since this pioneering work, many EMF have been obtained and characterized,3 among them actinide endofullerenes,4 as for example the dimetallic U2@C80.5 In this compound, the metal-metal distance from X-ray diffraction was found to be ranged between 3.46 and 3.79 Å, quite a long bond distance to suppose the presence of a strong metal-metal bond, as observed previously for dimetallic (lanthanide)2@C2n. This experimental confirmation of a weak U-U bonding interaction in a molecular structure is certainly very encouraging, but we were wondering whether it is possible to isolate a compound with a strong U-U bond or not. In this communication we analyze the characteristic electronic structure of a family of endohedral actinidofullerenes related to U2@C80 and discuss about the challenging task of synthesizing new systems showing strong actinide-actinide interaction in the confined space of a fullerene. References 1. 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. 2. Stevenson, S.; Rice, G.; Glass, T.; Harich, K.; Cromer, F.; Jordan, M. R.; Craft, J.; Hadju, E.; Bible, R.; Olmstead, M. M.; Maitra, K.; Fisher, A. J.; Balch, A. L.; Dorn, H. C., Nature 1999, 401, 55. 3. Popov, A. A.; Yang, S.; Dunsch, L. Chem. Rev. 2013, 113, 5989-6113. 4. a) Wang, Y.; Morales-Martínez, R. et al.J. Am. Chem. Soc., 2017, 139, 5110-5116; b) Cai, W. C.; Morales-Martínez, R. et al. Chem. Sci. 2017, 8, 5282-5290; c) Cai, W.; Abella, L. et al.J. Am. Chem. Soc., 2018, 140, 18039-18050. 5. Zhang, X.; Wang, Y.; Morales-Martínez, R.; Zhong, J.; de Graaf, C.; Rodríguez-Fortea, A.; Poblet, J. M.; Echegoyen, L.; Feng, L.; Chen, N. J. Am. Chem. Soc., 2018, 140, 3907-3915.