Unique Molecular Properties of a Paramagnetic Endohedral Metallofullerene La@C82: Its Chemical Reactivities, and Electronic and Magnetic Properties

Endohedral metallofullerenes (EMFs) have attracted special interest as new spherical molecules because they have unusual physical and chemical properties that are imparted by the encapsulated metal atoms.^[1] Among the fullerenes in general, paramagnetic EMFs have garnered much attention because of their unique electronic and magnetic properties, quite different from the closely related non-paramagnetic endofullerenes. 

   La@C₈₂ has extensively been investigated as a prototype paramagnetic fullerene because it is the first endohedral metallofullerene which was reported the successful isolation for the first time. ^[2] Moreover, it was demonstrated that a family of lanthanum containing fullerenes were produced and that extraction with toluene yielded abundantly La@C₈₂. La@C₈₂ has an electronic structure which is best described as [La]³⁺[C₈₂]^3- with an open-shell electronic character that is a consequence of transferring three electrons from lanthanum to C₈₂ (Scheme).^[3]  The resulting electron spin imposes a unique chemical reactivity comparable to that of a radical character.^[4] The latter is believed to induce magnetism^[5] and enhance electron conductivity.^[6] In this regard, our group has investigated and revealed unprecedented molecular properties of La@C₈₂.

   In this talk, I will present its unique radical reactivity,^[4] photo-induced intramolecular electron transfer,^[7] and the SAM demonstrating electrochemical switching^[5] based on La@C₈₂.

References:

[1] (For reviews of EMFs) (a) Chemistry of Nanocarbons; Akasaka, T., Wudl, F., Nagase, S., Eds.; Wiley: Chichester, 2010. (b) Chaur, M. N. et al. Angew. Chem. Int. Ed. 2009, 48, 7514. (c) Popov, A. A. et al. Chem. Rev. 2013, 113, 5989.

[2] Chai, Y. et al. J. Phys. Chem. 1991, 95, 75648.

[3] Nagase, S. et al. J. Chem. Soc., Chem. Commun. 1994, 1837.

[4] (a) Takano, Y. et al. J. Am. Chem. Soc. 2008, 130, 16224. (b) Takano, Y. et al. Chem. Commun. 2010, 46, 8035.

[5] Takano, Y. et al. Chem. Commun. 2013, 49, 8145. (Selected for front cover)

[6] Sato, S. et al. J. Am. Chem. Soc. 2011, 133, 2766.

[7] Takano, Y. et al. J. Am. Chem. Soc. 2012, 134, 16103.