Redox-switchable bistable nickel corrole

Stable porphyrinoid-based radicals and diradicaloids that possess delocalized pi-systems can be highly advantageous for use in spintronic and electronic applications. In this work, we present the facile synthesis of a neutral 17 pi-electron nickel corrole monoradical with a SOMO-HOMO degenerate electronic configuration. The one-electron oxidation of this radical produces an open-shell corrole cation-a unique 16 pi-electron Huckel antiaromatic singlet diradicaloid. The 16/17 pi redox species are highly air-stable and reversibly switchable with a moderate redox potential. At various spin and oxidation states, this corrole shows multi-level aromaticity switching behavior according to Huckel or Baird's law. The coexisting counter-rotating diatropic and paratropic ring currents are evaluated for the neutral radical. This work establishes nickel corroles as a promising platform for supporting stable open-shell pi-conjugated systems with facile tunable aromaticity.