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Published July 21, 1994 | metadata_only
Journal Article

Preparation and structure of crystals of the metallofullerene Sc_2@C_(84)


IT was first proposed in 1985 that fullerenes can confine atoms in their interior because of their closed-cage structure. Attempts to verify this conjecture following the mass production of fullerenes have yielded metallofullerenes in bulk, and there is now good evidence that these compounds are endohedral—that is, that the metal atoms are inside. But direct confirmation in the form of structural data has been lacking, in part because of the difficulty of separating different metallofullerenes and obtaining pure crystals. Here we report the preparation of pure crystalline Sc_2@C_(84) and analyses of its structure by electron diffraction and high-resolution transmission electron microscopy. At room temperature the Sc_2@C_(84) molecules pack in a hexagonal-close-packed structure with a ratio of lattice constants c/ɑ = 1.63, the value expected for ideal-sphere packing. The molecular spacing of 11.2 Å is the same as that found earlier in crystalline C_(84) (refs 5, 6). The match between our microscopic images and simulations is markedly better for endohedral models than for those in which the metal atoms reside in the lattice outside the C_(84) cages. We believe that this combination of observations points inevitably to the conclusion that the metal atoms are inside the fullerenes.

Additional Information

© 1994 Nature Publishing Group. Received 2 December 1993; accepted 14 June 1994. We thank D. Dorn and L. Jackson for technical assistance, and acknowledge financial support from the Virginia Center for Innovative Technology. C.H.K. acknowledges support from the US NSF and the Materials and Molecular Simulation Center (supported by DOE-AICD, Allied-Signal, BP America, Asahi Chemical, Asahi Glass, Chevron, BF Goodrich and Xerox).

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August 20, 2023
August 20, 2023