Aqueous-Phase Single-Electron Transfer Calculations for Carbonate Radicals Using the Validated Marcus Theory

Single-electron transfer is a major aqueous-phase reaction mechanism commonly used in environmental engineering and natural processes such as aquatic photochemistry and advanced oxidation processes. While the Marcus theory is frequently used to analyze single-electron transfers, many previous studies appear to have overlooked its application, with uncertain energy values being reported without validation. Herein, using the carbonate radical as the oxidant, we analyze the validity of the Marcus theory to aqueous-phase reactions involving aromatic compounds. We highlight the impact of charged targeted molecules by comparing the reactivity with phenolate and aniline. Further, we expand the validated methodology to a wide range of structurally diverse organic compounds and reveal the underlying reaction mechanisms, such as outer-/inner-sphere single-electron transfer and proton coupled electron transfer. Our research outlines the next steps to be taken in Marcus theory calculations to investigate aqueous-phase environmental reactions.