Issue 1, 2015

The stability of nitrogen-centered radicals


Radical stabilization energies (RSEs) for a wide variety of nitrogen-centered radicals and their protonated counterparts have been calculated at G3(MP2)-RAD and G3B3 level. The calculated RSE values can be rationalized through the combined effects of resonance delocalization of the unpaired spin, electron donation through adjacent alkyl groups or lone pairs, and through inductive electron donation/electron withdrawal. The influence of ring strain effects as well as the synergistic combination of individual substituent effects (captodatively stabilized N-radicals) have also been explored. In symmetric N-radicals the substituents may also affect the relative ordering of electronic states. In most cases the π-type radical (unpaired spin distribution perpendicular to the plane of the N-radical) is found to be most stable. Closed shell precursors of biological and pharmaceutical relevance, for which neither experimental nor theoretical results on radical stabilities exist, have been included.

Graphical abstract: The stability of nitrogen-centered radicals

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Article information

Article type
04 Aug 2014
16 Oct 2014
First published
16 Oct 2014
This article is Open Access
Creative Commons BY license

Org. Biomol. Chem., 2015,13, 157-169

Author version available

The stability of nitrogen-centered radicals

J. Hioe, D. Šakić, V. Vrček and H. Zipse, Org. Biomol. Chem., 2015, 13, 157 DOI: 10.1039/C4OB01656D

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