Reversible Single-Electron-Transfer to Oxygen in a Stable N-Heterocyclic Carbene Palladium(I) Metalloradical

Inorg Chem. 2023 Dec 11;62(49):19838-19842. doi: 10.1021/acs.inorgchem.3c02878. Epub 2023 Nov 22.

Abstract

The chemical and electrochemical one-electron oxidation of [Pd(IPr)2] (1) leads to the formation of mononuclear palladium(I) complex [Pd(IPr)2][PF6] (2). This bench-stable metalloradical has been fully characterized and its structure confirmed by X-ray diffraction analysis. EPR and DFT studies confirm the localization of the unpaired electron onto the metal center. Low temperature NMR and EPR measurements reveal the ability of complex 2 to reversibly coordinate and reduce the dioxygen molecule, leading to the formation of a three-coordinate complex, [PdII(IPr)21-O2)]+ (4), in which the unpaired electron has been transferred to the superoxido ligand.