The properties of metal/dioxygen species, key intermediates in oxidation catalysis, can be modulated by interaction with redox-inactive Lewis acids, but structural information about these adducts is scarce. Here we demonstrate that even mildly Lewis acidic alkali metal ions, which are typically viewed as innocent “spectators”, bind strongly to a reactive cis-peroxo dicopper(II) intermediates. Unprecedented structural insight has now been obtained from X-ray crystallographic characterization of the “bare” dicopper-peroxo motif and its Li+, Na+, and K+ complexes.
UV–vis, Raman, and electrochemical studies show that the binding persists in MeCN solution, growing stronger in proportion to the cation’s Lewis acidity. The affinity for Li+ is surprisingly high, leading to theextraction of Li+ from its crown ether complex. Computational analysis indicates that the alkali ions influence the entire Cu-OO-Cu core, modulating the degree of charge transfer from copper to dioxygen. This induces significant changes in the electronic, magnetic, and electrochemical signatures of the Cu2O2 species.
These findings have far-reaching implications for analyses of transient metal/dioxygen intermediates, which are often studied in situ, and they may be relevant to many (bio)chemical oxidation processes when considering the widespread presence of alkali cations in synthetic and natural environments.
The study is the result of a collaboration between the groups of Prof. Franc Meyer (Göttingen, DE) and Prof. Marcel Swart, and was recently published in Journal of the American Chemical Society:
A. Brinkmeier, K.E. Dalle, L. D’Amore, R.A. Schulz, S. Dechert, S. Demeshko, M. Swart, and F. Meyer
“Modulation of a mu-1,2-Peroxo Dicopper(II) Intermediate by Strong Interaction with Alkali Metal Ions”
J. Am. Chem. Soc. 2021, 143, 17751-17760
OpenData related to this publication is available at iochem-bd:
Girona, November 17, 2021
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