The stabilization of fused-pentagon fullerene molecules

Abstract

The isolated pentagon rule (IPR) is now widely accepted as a general rule for determining the stability of all-carbon fullerene cages composed of hexagons and pentagons. Fullerenes that violate this rule have been deemed too reactive to be synthesized. The stabilization of non-IPR endohedral fullerenes depends on charge transfer from the encapsulated metal clusters (endoclusters) to fullerene cages, the electronic properties of empty all-carbon cages, the matching size and geometries of fullerene and endocluster, as well as the strong coordination of the metal ions to fused pentagons. The stability of non-IPR exohedral fullerenes can be rationalized primarily by both the 'strain-relief' and 'local-aromaticity' principles. This Review focuses on recent work on stabilization of non-IPR fullerenes, including theoretical and empirical principles, experimental methods, and molecular structures of fused-pentagon fullerenes characterized so far. The special chemical properties of non-IPR fullerenes that distinguish them from IPR-satisfying ones are also emphasized.

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Figure 1: Basic fused-pentagon configurations (with 2–3 pentagon subunits) in non-IPR fullerenes.
Figure 2: Prototypical molecular orbitals (MOs) for endofullerene Sc3N@#6,140C68.
Figure 3: Structures of metallofullerenes.
Figure 4: Structures of trimetallic nitride endofullerenes.
Figure 5: Structure of Sc2C2@#6,073C68 with metal carbide inside.
Figure 6: Structures of exohedral derivatives.
Figure 7: Schlegel diagrams of C58 and C62 derivatives.

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Acknowledgements

The authors thank Michael Blackburn from the University of Sheffield, UK, and Xin Lu from Xiamen University, China, for help in preparing the manuscript. This work was supported by the NNSFC (No. 20525103, 20531050, 20721001) and the 973 Program (No. 2007CB815301).

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Correspondence to Su-Yuan Xie.

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Tan, Y., Xie, S., Huang, R. et al. The stabilization of fused-pentagon fullerene molecules. Nature Chem 1, 450–460 (2009). https://doi.org/10.1038/nchem.329

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