Selective Methane Oxidation by Heterogenized Iridium Catalysts

Oxidative methane (CH₄) carbonylation promises a direct route to the synthesis of value-added oxygenates such as acetic acid (CH₃COOH). Here, we report a strategy to realize oxidative CH₄ carbonylation through immobilized Ir complexes on an oxide support. Our immobilization approach not only enables direct CH₄ activation but also allows for easy separation and reutilization of the catalyst. Furthermore, we show that a key step, methyl migration, that forms a C–C bond, is sensitive to the electrophilicity of carbonyl, which can be tuned by a gentle reduction to the Ir centers. While the as-prepared catalyst that mainly featured Ir(IV) preferred CH₃COOH production, a reduced catalyst featuring predominantly Ir(III) led to a significant increase of CH₃OH production at the expense of the reduced yield of CH₃COOH.