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Gas-phase production and photoelectron spectroscopy of the smallest fullerene, C20


Fullerenes are graphitic cage structures incorporating exactly twelve pentagons1. The smallest possible fullerene is thus C20, which consists solely of pentagons. But the extreme curvature and reactivity of this structure have led to doubts about its existence and stability. Although theoretical calculations have identified, besides this cage, a bowl and a monocyclic ring isomer as low-energy members of the C20 cluster family2, only ring isomers of C20 have been observed3,4,5,6 so far. Here we show that the cage-structured fullerene C20 can be produced from its perhydrogenated form (dodecahedrane C20H20) by replacing the hydrogen atoms with relatively weakly bound bromine atoms, followed by gas-phase debromination. For comparison we have also produced the bowl isomer of C20 using the same procedure. We characterize the generated C20 clusters using mass-selective anion photoelectron spectroscopy; the observed electron affinities and vibrational structures of these two C20 isomers differ significantly from each other, as well as from those of the known monocyclic isomer. We expect that these unique C20 species will serve as a benchmark test for further theoretical studies.

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Figure 1: Isomers of C20.
Figure 2: Preparation of precursors for cage 1 and bowl 2.
Figure 3: Cation mass spectrum of [C20HBr13]; 70-eV electrons were used for ionization.
Figure 4: Anion mass spectra of [C20HBr13] (a) and [C20HBr9] (b).
Figure 5: Photoelectron spectra of the mass-selected C-20 clusters.


  1. Kroto, H. W. Smaller carbon species in the laboratory and in space. Int. J. Mass Spectrom. Ions Process. 138, 1– 15 (1994).

    Article  ADS  Google Scholar 

  2. van Orden, A. & Saykally, R. J. Small carbon clusters. Spectroscopy, structure, and energetics. Chem. Rev. 98, 2313–2357 (1998).

    Article  CAS  Google Scholar 

  3. Yang, S. et al. UPS of 2–30-atom carbon clusters: Chains and rings. Chem. Phys. Lett. 144, 431–436 (1988).

    Article  ADS  CAS  Google Scholar 

  4. Handschuh, H. et al. Stable configurations of carbon clusters: Chains, rings, and fullerenes. Phys. Rev. Lett. 74, 1095– 1098 (1995).

    Article  ADS  CAS  Google Scholar 

  5. Wakabayashi, T. et al. Photoelectron spectroscopy of C-n produced from laser ablated dehydroannulene derivatives having carbon ring size of n = 12, 16, 18, 20 and 24. J. Chem. Phys. 107 , 4783–4787 (1997).

    Article  ADS  CAS  Google Scholar 

  6. Von Helden, G. et al. Do small fullerenes exist only on the computer? Experimental results on C+/-20 and C+/-24 . Chem. Phys. Lett. 204, 15– 22 (1993).

    Article  ADS  CAS  Google Scholar 

  7. Heilbronner, E. & Dunitz, J. D. Reflections on Symmetry (VCH, Weinheim, 1993).

    MATH  Google Scholar 

  8. Von Helden, G., Gotts, N. G. & Bowers, M. T. Experimental evidence for the formation of fullerenes by collisional heating of carbon rings in the gas phase. Nature 363, 60–63 ( 1993).

    Article  ADS  CAS  Google Scholar 

  9. Kroto, H. W. The stability of the fullerenes Cn, with n = 24, 28, 32, 36, 50, 60 and 70. Nature 329, 529– 531 (1987).

    Article  ADS  CAS  Google Scholar 

  10. Piskoti, C., Yarger, J. & Zettl, A. C36, a new carbon solid. Nature 393, 771–774 ( 1998).

    Article  ADS  CAS  Google Scholar 

  11. Fowler, P. W. et al. C36, a hexavalent building block for fullerene compounds and solids. Chem. Phys. Lett. 300, 369–378 (1999).

    Article  ADS  CAS  Google Scholar 

  12. Koshio, A., Inakuma, M., Sugai, T. & Shinohara, H. A preparative scale synthesis of C36 by high-temperature laser vaporization: Purification and identification of C36H6 and C 36H6O. J. Am. Chem. Soc. 122, 398–399 (2000).

    Article  CAS  Google Scholar 

  13. McEwen, A. B. & Schleyer, P. v. R. In-plane aromaticity and trishomoaromaticity: A computational evaluation. J. Org. Chem. 51, 4357–4368 ( 1986).

    Article  CAS  Google Scholar 

  14. Wahl, F., Wörth, J. & Prinzbach, H. The pagodane route to dodecahedranes: An improved approach to the C20H20 parent framework; partial and total functionalizations—does C20-fullerene exist? Angew. Chem. Int. Edn Engl. 32, 1722–1726 (1993).

    Article  Google Scholar 

  15. Prinzbach, H. & Weber, K. From an insecticide to Plato's Universe—the pagodane route to dodecahedranes: New pathways and new perspectives. Angew. Chem. Int. Edn Engl. 33, 2239– 2257 (1994).

    Article  Google Scholar 

  16. Bertau, M. et al. From pagodanes to dodecahedranes—search for a serviceable access to the parent C20H20 hydrocarbon. Tetrahedron 53, 10029–10040 (1997).

    Article  CAS  Google Scholar 

  17. Cioslowsky, J., Edgington, L. & Stefanov, B. B. Steric overcrowding in perhalogenated cyclohexanes, dodecahedranes, and [60]fulleranes. J. Am. Chem. Soc. 17, 10381–10384 (1995).

    Article  Google Scholar 

  18. Beckhaus, H.-D. et al. Experimental enthalpies of formation and strain energies for the caged C20H20 pagodane and dodecahedrane frameworks. J. Am. Chem. Soc. 116, 11775–11778 (1994); 117, 8885 (1995).

    Article  Google Scholar 

  19. Melder, H.-P. et al. Unsaturated dodecahedranes - synthesis of the highly pyramidalized, highly reactive C20H18 and C20H16 olefins. Res. Chem. Intermed. 22, 667– 702 (1996).

  20. Scott, L. T. et al. Corannulene. A three-step synthesis. J. Am. Chem. Soc. 119, 10963–10968 ( 1997).

    Article  CAS  Google Scholar 

  21. Galli, G., Gygi, F. & Golaz, J.-C. Vibrational and electronic properties of neutral and negatively charged C20 clusters. Phys. Rev. B 57, 1860–1867 (1998).

    Article  ADS  CAS  Google Scholar 

  22. Duškesas, G. & Larsson, S. Bond lengths and reorganization energies in fullerenes and their ions. Theor. Chem. Acc. 97, 110–118 ( 1997).

    Article  Google Scholar 

  23. Haberland, H., Kornmeier, H., Ludewigt, C., Risch, A. & Schmidt, M. A double/triple time-of-flight mass spectrometer for the study of photoprocesses in clusters, or how to produce cluster ions with different temperatures. Rev. Sci. Instrum. 62, 2621–2625 (1991).

    Article  ADS  CAS  Google Scholar 

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We thank J. Leonhardt, G. Leonhardt-Lutterbeck, S. Ruf and C. Warth for technical assistance, and G. Seifert, S. Larsson and R. C. Haddon for discussions. This work was supported by the BASF AG, the Deutsche Forschungsgemeinschaft, the Fonds der Chemischen Industrie, and the US National Science Foundation.

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Correspondence to Horst Prinzbach.

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Prinzbach, H., Weiler, A., Landenberger, P. et al. Gas-phase production and photoelectron spectroscopy of the smallest fullerene, C20. Nature 407, 60–63 (2000).

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