Global Aromaticity and Antiaromaticity in Porphyrin Nanoring Anions

Martin D Peeks; Michael Jirasek; Timothy D W Claridge; Harry L Anderson

doi:10.1002/anie.201909032

Global Aromaticity and Antiaromaticity in Porphyrin Nanoring Anions

Angew Chem Int Ed Engl. 2019 Oct 28;58(44):15717-15720. doi: 10.1002/anie.201909032. Epub 2019 Sep 17.

Authors

Martin D Peeks^{1

2}, Michael Jirasek¹, Timothy D W Claridge¹, Harry L Anderson¹

Affiliations

¹ Department of Chemistry, University of Oxford, Chemistry Research Laboratory, Oxford, OX1 3TA, UK.
² School of Chemistry, University of New South Wales, Sydney, NSW, 2052, Australia.

Abstract

Doping, through oxidation or reduction, is often used to modify the properties of π-conjugated oligomers. In most cases, the resulting charge distribution is difficult to determine. If the oligomer is cyclic and doping establishes global aromaticity or antiaromaticity, then it is certain that the charge is fully delocalized over the entire perimeter of the ring. Herein we show that reduction of a six-porphyrin nanoring using decamethylcobaltocene results in global aromaticity (in the 6- state; [90 π]) and antiaromaticity (in the 4- state; [88 π]), consistent with the Hückel rules. Aromaticity is assigned by NMR spectroscopy and density-functional theory calculations.

Keywords: anions; annulenes; aromaticity; macrocycles; porphyrinoids.

Abstract

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