Strain-Driven Endohedral Redox Couple Ce^IV/Ce^III in Nitride Clusterfullerenes CeM₂N@C₈₀ (M = Sc, Y, Lu)

Abstract

Electrochemical and NMR spectroscopic studies prove the endohedral oxidation of CeIII in nitride clusterfullerenes CeM2N@C80 (M = Sc, Y, Lu). The redox potential of the endohedral CeIV/CeIII couple systematically varies with the ionic radius of the second cluster metal. DFT computations show that this metal dependence is caused by the release of strain when CeIV with a small ionic radius is formed. In particular, after endohedral oxidation the pyramidal CeY2N cluster becomes planar in the [CeM2N@C80]+ cation.

Isolation of CeLu2N@Ih‐C80 through a Non‐Chromatographic, Two‐Step Chemical Process and Crystallographic Characterization of the Pyramidalized CeLu2N within the Icosahedral Cage

“…Previously, DFT computations on CeLu 2 N@ I h ‐C 80 had predicted that the cluster would be planar 34. 40 The sizes of the encapsulated metal ions and the rigid nature of the I h ‐C 80 cage are responsible for the pyramidal nature of this CeLu 2 N unit.…”

“…The redox potential of the Ce 4+ /Ce 3+ couple in the mixed‐metal endohedrals CeSc 2 N@C 80 , CeY 2 N@C 80 , and CeLu 2 N@C 80 varies in response to the different metal ions within the cage 34. 35, 40, 43, 55 Finally, the mixed‐metal endohedral LaSc 2 N@ C s (hept)‐C 80 is the first and only example of an endohedral fullerene that contains a heptagon as a part of the cage 56. All other endohedral fullerenes have cages made up of twelve pentagons and a number of hexagons, with the latter determined by the cage size.…”

“…Typical resolution times from recycling HPLC range from 100–400 min. Extreme examples of very lengthy separation times for the recycling HPLC method were 2900 min to resolve and remove Y 3 N@ D 5 h ‐C 80 from CeY 2 N@ I h ‐C 80 species40 and 4280 min to separate CeY 2 N@C 84 from Y 3 N@C 84 43…”

Metallofullerenes Encaging Mixed‐Metal Clusters: Synthesis and Structural Studies of GdxHo3−xN@C80 and GdxLu3−xN@C80

“…Therefore, several mixed-metal nitride endofullerenes have been synthesized and isolated, such as Ce x M 3Àx N@C 78-88 (x = 1, 2; M = Sc, Y), [2] HoM 2 N@C 80 and Ho 2 MN@C 80 families (M = Sc, Lu, Y), [3] ScYErN@C 80 , [4] Lu x Y 3Àx N@C 80 , [5] Sc 2 TiN@C 80 , [6] Sc x Gd 3Àx N@C 80 , [4] DySc 2 N@C 80 , [7] Ho x Sc 3Àx N@C 80 (x = 1, 2), [8] and so forth. [1] In particular, mixed-metal nitride endofullerenes with two or three types of metal in the encaged cluster provide a platform for the preparation of multifunctional molecules.…”

“…[1] In particular, mixed-metal nitride endofullerenes with two or three types of metal in the encaged cluster provide a platform for the preparation of multifunctional molecules. Therefore, several mixed-metal nitride endofullerenes have been synthesized and isolated, such as Ce x M 3Àx N@C 78-88 (x = 1, 2; M = Sc, Y), [2] HoM 2 N@C 80 and Ho 2 MN@C 80 families (M = Sc, Lu, Y), [3] ScYErN@C 80 , [4] Lu x Y 3Àx N@C 80 , [5] Sc 2 TiN@C 80 , [6] Sc x Gd 3Àx N@C 80 , [4] DySc 2 N@C 80 , [7] Ho x Sc 3Àx N@C 80 (x = 1, 2), [8] and so forth. The functions and applications of mixed-metal endofullerenes attract increasing interest as they are developed, especially in terms of their magnetic and biomedical properties.Fullerene cages provide an ideal delivery carrier for nanomedicines.…”