Capturing the elusive aromaticity of bicalicene

W. P. Oziminski*, M. Palusiak, J. Dominikowska, T. M. Krygowski, R. W. A. Havenith, C. M. Gibson, P. W. Fowler*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

13 Citations (Scopus)

Abstract

The ring-current aromaticity of the bicalicene molecule arises, in spite of the 16 p carbon perimeter, from strong local diatropic circulations on the two pentagonal rings, as shown by current-density maps computed at the ipsocentric RHF/6-311G** and DFT/6-311G** levels of theory. Conjugated-circuit models cannot capture this pattern of circulation as it arises from 'ionic' contributions in a valence-bond picture. Canonical molecular-orbital analysis reveals a cancellation of paratropic and diatropic frontier-orbital contributions, which explains the difficulties that Huckel-based models have in producing qualitatively correct current-density maps for this molecule. Other measures of aromaticity reflect, to different extents, the dominance of the 'tetraionic' contribution to the aromaticity of this species.

Original languageEnglish
Pages (from-to)3286-3293
Number of pages8
JournalPhysical Chemistry Chemical Physics
Volume15
Issue number9
DOIs
Publication statusPublished - 2013

Keywords

  • RING CURRENTS
  • MAGNETIC-PROPERTIES
  • CONJUGATED HYDROCARBONS
  • CYCLIC BICALICENE
  • PI-SYSTEMS
  • MOLECULES
  • POLYACENES
  • RESONANCE
  • DENSITY

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