Stable Subporphyrin meso-Aminyl Radicals without Resonance Stabilization by a Neighboring Heteroatom

Daiki Shimizu; Ko Furukawa; Atsuhiro Osuka

doi:10.1002/anie.201703097

Stable Subporphyrin meso-Aminyl Radicals without Resonance Stabilization by a Neighboring Heteroatom

Angew Chem Int Ed Engl. 2017 Jun 19;56(26):7435-7439. doi: 10.1002/anie.201703097. Epub 2017 May 30.

Authors

Daiki Shimizu¹, Ko Furukawa², Atsuhiro Osuka¹

Affiliations

¹ Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto, 606-8502, Japan.
² Center for Instrumental Analysis, Niigata University, Nishi-ku, Niigata, 950-2181, Japan.

PMID: 28485120
DOI: 10.1002/anie.201703097

Abstract

Most aminyl radicals studied so far are resonance-stabilized by neighboring heteroatoms, and those without such stabilization are usually short-lived. We report herein that subporphyrin meso-2,4,6-trichlorophenylaminyl radicals and a bis(5-subporphyrinyl)aminyl radical are fairly stable under ambient conditions without such stabilization. The subporphyrin meso-2,4,6-trichlorophenylaminyl radical crystal structure displays a characteristically short C_meso -N bond and a perpendicular arrangement of the meso-arylamino group. The stabilities of these radicals have been ascribed to extensive spin delocalization over the subporphyrin π-electronic network as well as steric protection around the aminyl radical center.

Keywords: ESR spectroscopy; aminyl radicals; porphyrinoids; stable radicals; subporphyrins.

Publication types

Research Support, Non-U.S. Gov't