Reversible Intramolecular Single-Electron Oxidative Addition Involving a Hemilabile Noninnocent Ligand

Using the noninnocent ligand Q [= 4,6-di-tert-butyl-(2-methylthiophenylimino)-o-benzoquinone] with a thioether group as potential coordination function, it has been possible to substantiate a single-electron transfer induced oxidative addition within the complex [IrCp*Q]^0/+ (Cp* = C₅Me₅) via structural characterization (catecholato → semiquinonato transition coupled with reversible S→Ir coordination), via cyclic voltammetry, EPR, and DFT (semiquinone formulation with about 8% Ir participation). The intramolecular rearrangement of the 16-electron precursor [IrCp*Q] triggered by electron removal illuminates the complementary activities of the substrate binding metal and the electron-buffering ligand as was recently employed by Ringenberg et al. in dihydrogen activation (Organometallics 2010, 29, 1956).