Templating an N-heterocyclic carbene (NHC)-cyclometalated Cp*IrIII-based oxidation precatalyst on a pendant coordination platform: assessment of the oxidative behavior via electrochemical, spectroscopic and catalytic probes

Abstract

The coordination of metalloligands to derive modified properties of the metal functionality is one of the interesting strategies practiced in materials chemistry and catalysis. In this work, a pendant terpyridine ligand has been utilized for templating a Cp*Ir^III(NHC)-based (NHC = N-heterocyclic carbene) oxidation precatalyst to assess its modified oxidative behavior via electrochemical, UV-vis spectroscopic, and catalytic probes. These studies suggested that the coordination-template enhances the electron-deficiency at the Ir^III redox center and affects the nature of the oxidized high-valent Ir-oxo species during chemical oxidation. Moreover, both the premodified and postmodified Cp*Ir^III(NHC)-based complexes were found to be equally efficient in catalytic sp³ C–H oxidation reactions with NaIO₄ as a mild sacrificial oxidant.