A Zwitterionic, 10 π Aromatic Hemisphere

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

Research output: Contribution to journalArticlepeer-review

3 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
StatePublished - Nov 6 2017


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

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)


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