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

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posted on 28.03.2011, 00:00 by Ralph Hübner, Sebastian Weber, Sabine Strobel, Biprajit Sarkar, Stanislav Záliš, Wolfgang Kaim
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).