Metal peroxides are key intermediates implicated in a range of biological and synthetic processes, including those relevant to renewable energy applications. Rare-earth (RE) peroxides have been shown to exhibit remarkable stability at high temperatures, making them appealing for use in material science. While the formation of RE peroxides via O2 reduction at divalent RE centers is documented, O2 activation at trivalent RE centers via external reductant is less expected, possibly due to weak coordination to the metal. Recently, we presented kinetic and mechanistic details surrounding the peroxide-selective reduction of O2 promoted by decamethylferrocene in the presence of RE(OTf)3. A central finding of this work was that the rate of the reaction did not follow the trends in Lewis acidity, but instead followed that of substrate accessibility. In this presentation, we will discuss the isolation and characterization of the RE peroxides, including the novel tetra-cationic dinuclear RE peroxide, [RE2(18-C-6)2(EG)2(O22–)]4+ (18-C-6: 18-crown-6, EG: ethylene glycol). We will also share the preliminary reactivity of the RE peroxides with Brønsted acid and organic substrates.

Synthesis, characterization and reactivity of soluble rare-earth peroxides via metal-coupled electron transfer to dioxygen

ACS Spring Meeting 2021

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