Published in:
European Journal of Organic Chemistry, 2021 (2021) 46, Seite 6450-6458
Language:
English
DOI:
10.1002/ejoc.202101228
ISSN:
1434-193X;
1099-0690
Origination:
Footnote:
Description:
<jats:title>Abstract</jats:title><jats:p>Azulene is stabilized by “zwitterionic aromaticity”, what about its ring <jats:italic>carbo</jats:italic>‐mer? The greater dipole moment of the latter is oriented in the opposite direction, while providing an enhanced zwitterionic aromatic character. Comparison of local aromaticity indices for the two rings, with 5 and 7 C−C bonds in azulene or C−C<jats:sub>2</jats:sub>−C edges in <jats:italic>carbo</jats:italic>‐azulene, allows analysis of the quasi‐independent influence of size on the π‐electronic properties of these aromatic bicyclic molecules exhibiting quasi‐identical shapes and π‐resonance schemes between their common set of <jats:italic>sp</jats:italic><jats:sup>2</jats:sup>C−H vertices. The electrostatic features of such dipolar hydrocarbons are also analyzed by comparison with their respective radical cation and anion, and with their apolar bicyclic isomer, naphthalene and <jats:italic>carbo</jats:italic>‐naphthalene.</jats:p>