Metal�oxyl radical complexes have been invoked as precursors to O�O bond formation in photosystem II and in synthetic water oxidation catalysts, and in the activation of strong C�H bonds. The remarkable reactivity of metal oxyls is apparently a consequence of unpaired spin on the terminal oxo, but the paucity of isolable oxyl complexes has hindered their study and limited their use in catalysis applications. We hypothesized ancillary ligands that support open-shell electron configurations might impart radical character to closed shell metal�oxo fragments and engender oxyl-like reactivity. For instance, the previously reported d0 Re(VII) complex [Et4N][Re(O)2(apPh)2] ([apPh]2� = 2,4-di-tert-butyl-6-(phenylamido)phenolate) is oxidized at modest potentials to afford a complex bearing a ligand radical. This talk presents the synthesis and characterization of related oxorhenium compounds bearing bis-bidentate or polydentate amidophenolate type ligands, along with their one electron oxidized counterparts. In addition, it reports on their oxyl-like reactivity with radical substrates to yield new O�R bonds. It also presents recent efforts to expand this mode of reactivity to other low d electron count metals.

Redox-active ligands for radical O�R coupling at terminal metal�oxo groups

248th National Meeting (2014)

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