Concerted Proton–Electron Transfer Reactivity at a Multimetallic Co4O4 Cubane Cluster

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High-valent oxocobalt(IV) species have been invoked as key intermediates in oxidative catalysis, but investigations into the chemistry of proton-coupled redox reactions of such species have been limited. Herein, the reactivity of an established water oxidation catalyst, [Co 4 O 4 (OAc) 4 (py) 4 ][PF 6 ], toward H-atom abstraction reactions is described. Mechanistic analyses and density functional theory (DFT) calculations support a concerted proton–electron transfer (CPET) pathway in which the high energy intermediates formed in stepwise pathways are bypassed. Natural bond orbital (NBO) calculations point to cooperative donor–acceptor σ interactions at the transition state, whereby the H-atom of the substrate is transferred to an orbital delocalized over a Co 3 (μ 3 -O) fragment. The mechanistic insights provide design principles for the development of catalytic C–H activation processes mediated by a multimetallic oxo metal cluster.