Presentation Type
Oral Presentation
Category
STEM (science, technology, engineering, mathematics)
Abstract/Artist Statement
Dinuclear metal-peroxo species have been proposed as key intermediates in the dioxygen activation pathway for a number of nonheme diiron and dicopper enzymes such as soluble methane monooxygenase (sMMO). A key step in the O activation is the cleavage of the metal-peroxo O-O bond to form higher-valent metal-oxo species. Meanwhile, the reverse O–O bond formation process catalyzed by the Oxygen-Evolving Complex (OEC) in natural Photosystem II is a pivotal step in the conversion of water into molecular oxygen during photosynthesis. In synthetic chemistry, compared to the diiron and dicopper complexes, dicobalt peroxo complexes are relatively less studied. Furthermore, none of the known dicobalt peroxo complexes have exhibited O–O bond activation to generate higher-valent derivatives.
In this work, UV–vis spectroscopy revealed a reversible O–O bond activation and formation process in dinuclear cobalt complexes. We systematically investigated the thermodynamic and kinetic factors governing the fate of the O–O bond within the equilibrium between CoII(μ-OO)CoII and CoIII₂(μ-O)₂ species. This equilibrium is affected by the reaction temperature. Further characterization of this system using NMR spectroscopy and cyclic voltammetry indicated that the observed interconversion is driven by modulation of the cobalt redox potentials.
This is the first time that the reversible cleavage and formation of the O-O bond is clearly demonstrated in a cobalt system. This finding not only challenges conventional understanding of metal–oxygen reactivity but also opens new avenues for designing new catalytic systems and studying fundamental bond activation mechanisms. Taken together, these discoveries push the boundaries of known cobalt chemistry and demonstrate how synthetic models can offer new insights into biological oxidation processes.
Mentor Name
Dong Wang
wenting oral pre
Reversible O-O Bond Activation and Formation on Dinuclear Cobalt Complexes
UC 327
Dinuclear metal-peroxo species have been proposed as key intermediates in the dioxygen activation pathway for a number of nonheme diiron and dicopper enzymes such as soluble methane monooxygenase (sMMO). A key step in the O activation is the cleavage of the metal-peroxo O-O bond to form higher-valent metal-oxo species. Meanwhile, the reverse O–O bond formation process catalyzed by the Oxygen-Evolving Complex (OEC) in natural Photosystem II is a pivotal step in the conversion of water into molecular oxygen during photosynthesis. In synthetic chemistry, compared to the diiron and dicopper complexes, dicobalt peroxo complexes are relatively less studied. Furthermore, none of the known dicobalt peroxo complexes have exhibited O–O bond activation to generate higher-valent derivatives.
In this work, UV–vis spectroscopy revealed a reversible O–O bond activation and formation process in dinuclear cobalt complexes. We systematically investigated the thermodynamic and kinetic factors governing the fate of the O–O bond within the equilibrium between CoII(μ-OO)CoII and CoIII₂(μ-O)₂ species. This equilibrium is affected by the reaction temperature. Further characterization of this system using NMR spectroscopy and cyclic voltammetry indicated that the observed interconversion is driven by modulation of the cobalt redox potentials.
This is the first time that the reversible cleavage and formation of the O-O bond is clearly demonstrated in a cobalt system. This finding not only challenges conventional understanding of metal–oxygen reactivity but also opens new avenues for designing new catalytic systems and studying fundamental bond activation mechanisms. Taken together, these discoveries push the boundaries of known cobalt chemistry and demonstrate how synthetic models can offer new insights into biological oxidation processes.