A Zwitterionic, 10 π Aromatic Hemisphere

Nema Hafezi, Wondimagegn T. Shewa, James C. Fettinger, Mark Mascal

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2 Scopus citations


A new concept in anionic 10 π aromaticity is described by the embedding of a compensating charge within an aromatic cyclononatetraenide ring by the symmetric superposition of an alkyl ammonium bridge. This is accomplished by the methylation of azatriquinacene to give a quaternary ammonium salt, followed by oxidation to the tetraene and final deprotonation. The resulting zwitterion is a stable [9]annulene with strong aromaticity as shown by its degree of C−C bond equalization and a nucleus-independent chemical shift value lower than that of benzene. The solid-state structure shows an eclipsed stacking motif with the electron-poor ammonium methyl groups occupying the electron-rich cavity of the aromatic bowl.

Original languageEnglish (US)
Pages (from-to)14141-14144
Number of pages4
JournalAngewandte Chemie - International Edition
Issue number45
Publication statusPublished - Nov 6 2017



  • ab initio calculations
  • annulenes
  • aromaticity
  • hemispherical molecules
  • zwitterions

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)

Cite this

Hafezi, N., Shewa, W. T., Fettinger, J. C., & Mascal, M. (2017). A Zwitterionic, 10 π Aromatic Hemisphere. Angewandte Chemie - International Edition, 56(45), 14141-14144. https://doi.org/10.1002/anie.201708521