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Unexpectedly Stable Fulleroid Derivatives from Bromomalonate Cycloaddition to Y3N@C80

This study describes the unexpected formation of highly stable fulleroid derivatives through the cycloaddition of bromomalonates to Y3N@C80. The complete characterization of these derivatives is discussed, including X-ray crystallography, spectroscopic analyses (NMR, HPLC, UV-visible), and electrochemistry. Density functional theory calculations provide insights into the thermodynamic basis for their stability. The research sheds light on the "Open Rather than Closed" Malonate Methano-Fullerene Derivatives and elucidates the formation and stability of methanofulleroid adducts of Y3N@C80.

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Unexpectedly Stable Fulleroid Derivatives from Bromomalonate Cycloaddition to Y3N@C80

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  1. Abstract: • Cycloaddition of bromomalonates to Y3N@C80 unexpectedly gave rise to fulleroid derivatives with unusually high stability. Complete characterization of these derivatives is described including X-ray crystallography, 1H NMR, 13C NMR, HMQC, UV-visible, HPLC, MALDI-MS, and electrochemistry. Density functional theory calculations are also presented, which provide a rationale for the formation of the fulleroid and reveal the underlying thermodynamic basis for their stability.

  2. “Open Rather than Closed” Malonate Methano-Fullerene Derivatives. The Formation of Methanofulleroid Adducts of Y3N@C80 Olena Lukoyanova, Claudia M. Cardona, Jose´ Rivera, Leyda Z. Lugo-Morales, Christopher J. Chancellor, Marilyn M. Olmstead, Antonio Rodrı´guez-Fortea, Josep M. Poblet*, Alan L. Balch, and Luis Echegoyen* J. Am. Chem. Soc. 2007,129, 10423-10430 演講者：莊雲婷

  3. Properties of C60 • Six-membered ring : 20 • Five-membered ring : 12 • [5,6] bonds : 60 (bond length : 1.45Å) • [6,6] bonds : 30 (bond length : 1.38Å) • Averge diameter : 7.1 Å http://nano.nchc.org.tw/dictionary/c60.html

  4. Electrochemical Detection of C606- Echegoyen. L. et. al. J. Am. Chem. Soc. 1992, 114, 3978-3980.

  5. 13C NMR Spectrum of C60 in C6D6 Jingcheng H ,et al ; J. Phys. Chem. B 2006, 110, 68-74

  6. Mass Spectrum of C60 Mehlig.K ,at al ; J. Chem. Phys., 2003,119,5591-5600

  7. Properties of C80 • Six-membered ring : 30 • Five-membered ring : 12 • [5,6] bonds : 60 • [6,6] bonds :60 • Averge diameter : 8.2 Å http://www.fullereneinternational.com/fic/fullerenes.html

  8. Endohedral Metallofullerene ( EMF ) Sc3N@C80 Shinohara, H.; et al. Bioconjugate Chem.2001, 12, 510-514 Stevenson, S.; et al. Nature1999, 401, 55-57

  9. Synthesis of Y3N@(N-ethylpyrrolidino-C80) Y3N Diels-Alder cycloadduct [5.6]&[6,6] Echegoyen, L.et.al; J. Am. Chem. Soc.2005, 127, 10448-10453

  10. [5,6] and [6,6] Junction for Cycloaddition [6,6] [6,6] [5,6] [5,6] Echegoyen, L.; et al. Angew. Chem., Int. Ed.2006, 45, 8176-8180

  11. Interconversion of[6,6] to [5,6] Y3N@pyrrolidino-C80 [5,6] [6,6] Echegoyen, L.; et al. Angew. Chem., Int. Ed.2006, 45, 8176-8180

  12. Retro-Cyclopropanation Reaction Echegoyen, L,et al ; Eur. J. Org. Chem. 2004,2299-2316.

  13. Synthesis Bingel-Hirsch Adducts 1, Y3N@C80-C(CO2Et)2.Yield 85% 2, Y3N@C80-C(CO2CH2Ph)2. Yield 76% ( ODCB )

  14. Cyclic Voltammetry of Compound 1

  15. MALDI-MS Spectrum of Comound 1 • 1, Y3N@C80-C(CO2Et)2, after chemical reduction with sodium metal in THF. • Matrix-Assisted Laser Desorption Ionization .

  16. Y3N@C80-C(CO2CH2Ph)2 C1-C9 : 2.30 Å open Sc3N@C80 C1-C9 1.421Å.

  17. Orientations of Fullerene Cage in 2 five-membered ring containing C1 on the left side six-membered ring containing C9 on the right side. six-membered ring containing C1 on the left side five-membered ring containing C9 on the right side. C1 C9

  18. Three Orientations of the Y3N Units in 2 90 K 0.7 occupancy 0.21 occupancy 0.09 occupancy

  19. 1H NMR Spectra of 2 dd H H d

  20. 13C NMR Spectrum downfield

  21. HMQC • Heteronuclear Multiple Quantum Coherence (HMQC) is selective for direct C-H coupling . 1H NMR 13C NMR http://www.chemistry.msu.edu/facilities/nmr/HMQC.html

  22. HMQC Spectrum 1H NMR 13C NMR

  23. UV-Visible Spectra

  24. I1 I3 I4 Relative Position of the Y3N Unit in Y3N@C80-C(CO2CH3)2 Bond Energiesaab (in kcal mol-1) a BE =E[Y3N@C80-C(CO2CH3)2] - E[Y3N@C80] -E[C(COOCH3)2]. b The calculations were using DFT with B3PW91 / 6-311G(2d,p)

  25. Distances of the [6,6]-Methano Derivative of Y3N@C80 a B3PW91 / 6-311G(2d,p)

  26. Representations of Functionalized La2@C80 DFT Calaulation a B3PW91 / 6-311G(2d,p) b multipole derived charge method(MDC-q)

  27. Representations of Functionalized Sc2@C80 DFT Calaulation a B3PW91 / 6-311G(2d,p) b multipole derived charge method(MDC-q)

  28. Rearrangement To Form the 2 Fulleroid OPEN Bingel-Hirsch Cycloaddition Norcaradiene Rearrangement [6,6] [5,6]

  29. Conclusions • It is also apparent that the endohedral cluster plays a major role in directing the addition sites to EMFs. • A possible thermally induced Norcaradiene rearrangement might occur instead subsequent to the [6,6]-addition to result in cleavage of the cyclopropane ring and formation of an opening in the fullerene cage. • After a thorough experimental and theoretical characterization and analysis of the malonate monoadducts of Y3N@C80, we conclude that their stability must be attributed to the cage-open fulleroid structure.

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