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Updated: Jun 18, 2026

Isolating Free Carbenes, their Mixed Dimers and Organic Radicals
Published on: April 19, 2019
Clar theory for radical benzenoids
Anirban Misra1, T G Schmalz, D J Klein
1Texas A&M University at Galveston, MARS, 5007 Avenue U, Galveston, Texas 77551, USA. anirbanmisra@yahoo.com
Abstract:
Eric Clar's ideas concerning "aromatic sextets" are extended from closed-shell benzenoids to the case of radical benzenoids, particularly those where the unpaired electrons are largely localized on sites of one "type" (starred or unstarred). A quantitative format in terms of a new Clar polynomial is introduced to make quantitative correlations with a selection of numerical data, including delocalization energies, spin densities, and energy gaps between states of different spin multiplicities. The correlations are generally quite good, thereby further validating Clar's ideas and our extension and quantification of them.
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