Structurally Characterized μ-1,2-Peroxo/Superoxo Dicopper(II) Pair
Alexander Brinkmeier1, Roland A Schulz1, Moritz Buchhorn2
1Institut für Anorganische Chemie, Universität Göttingen, Tammannstraße 4, D-37077 Göttingen, Germany.
Journal of the American Chemical Society
|June 30, 2021
Summary
This study reports the first crystallographic structure of a superoxo dicopper(II) complex, a key intermediate in copper-oxygen chemistry. This structural insight explains the facile interconversion between superoxo and peroxo dicopper species.
Area of Science:
- Bioinorganic Chemistry
- Coordination Chemistry
- Oxidation Catalysis
Background:
- Superoxo complexes of copper are crucial in oxygen-activating metalloenzymes and oxidation reactions.
- Their high reactivity makes isolation and structural characterization challenging.
- Previous work established thermochemical data but lacked structural details of dicopper(II) superoxo species.
Purpose of the Study:
- To report the first crystallographic structure of a superoxo dicopper(II) species.
- To characterize its peroxo congener and their interconversion.
- To provide structural insights into the reactivity of these key copper-oxygen intermediates.
Main Methods:
- Crystallographic structure determination of superoxo and peroxo dicopper(II) complexes.
- Electrochemical studies to determine redox potentials and reversibility.
- Spectroscopic analysis (IR, EPR) and magnetic measurements.
- Density functional theory (DFT) calculations.
Main Results:
- First crystallographic structure of a superoxo dicopper(II) species (3) and its peroxo congener (2) determined.
- Reversible 1e- interconversion between complexes 2 and 3 at low potential (-0.58 V vs Fc/Fc+).
- Structural and spectroscopic data confirm redox activity at the O2-derived unit.
- CuII-superoxo-CuII complex exhibits an S=1/2 spin ground state.
- DFT calculations reveal shallow potential energy surfaces for dihedral angle changes.
Conclusions:
- The study provides the first structural characterization of a superoxo dicopper(II) complex.
- Structural and computational findings explain the facile, low-reorganization energy interconversion of μ-1,2-superoxo/peroxo dicopper(II) couples.
- These results offer a foundation for further investigations into copper-oxygen chemistry and related enzymatic mechanisms.
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