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Published February 26, 2024 | Published
Journal Article Open

Redox Processes Involving Oxygen: The Surprising Influence of Redox-Inactive Lewis Acids

  • 1. ROR icon California Institute of Technology


Metalloenzymes with heteromultimetallic active sites perform chemical reactions that control several biogeochemical cycles. Transformations catalyzed by such enzymes include dioxygen generation and reduction, dinitrogen reduction, and carbon dioxide reduction–instrumental transformations for progress in the context of artificial photosynthesis and sustainable fertilizer production. While the roles of the respective metals are of interest in all these enzymatic transformations, they share a common factor in the transfer of one or multiple redox equivalents. In light of this feature, it is surprising to find that incorporation of redox-inactive metals into the active site of such an enzyme is critical to its function. To illustrate, the presence of a redox-inactive Ca2+ center is crucial in the Oxygen Evolving Complex, and yet particularly intriguing given that the transformation catalyzed by this cluster is a redox process involving four electrons. Therefore, the effects of redox inactive metals on redox processes–electron transfer, oxygen- and hydrogen-atom transfer, and O–O bond cleavage and formation reactions–mediated by transition metals have been studied extensively. Significant effects of redox inactive metals have been observed on these redox transformations; linear free energy correlations between Lewis acidity and the redox properties of synthetic model complexes are observed for several reactions. In this Perspective, these effects and their relevance to multielectron processes will be discussed.

Copyright and License

© 2024 The Authors. Published by American Chemical Society. This publication is licensed under CC-BY-NC-ND 4.0.


T.A. is grateful to the talented students and postdoctoral scholars who have contributed to projects on multimetallic complexes related to protein active sites developed in the Agapie lab, some of which are included in this Perspective, and to collaborators who have studied these compounds and helped understand their properties. T.A. thanks the NIH (R01-GM102687B) and NSF (CHE-1905320) for generously funding research related to bioinorganic chemistry in his laboratory.

Conflict of Interest

The authors declare no competing financial interest.



Additional details

January 31, 2024
February 29, 2024