Observation of a CuII2(μ‐1,2‐peroxo)/CuIII2(μ‐oxo)2 Equilibrium and its Implications for Copper–Dioxygen Reactivity |
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| Authors: | Dr Matthew T Kieber‐Emmons Jake W Ginsbach Dr Patrick K Wick Dr Heather R Lucas Dr Matthew E Helton Dr Baldo Lucchese Prof Masatatsu Suzuki Prof Andreas D Zuberbühler Prof Kenneth D Karlin Prof Edward I Solomon |
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| Institution: | 1. Department of Chemistry, Stanford University, Stanford, CA 94305 (USA);2. Department of Chemistry, University of Basel, 4056 Basel (Switzerland);3. Department of Chemistry, The Johns Hopkins University, Baltimore, MD 21218 (USA);4. Division of Material Sciences, Kanazawa University, Kakuma‐machi, Kanazawa 920‐1192 (Japan) |
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| Abstract: | Synthesis of small‐molecule Cu2O2 adducts has provided insight into the related biological systems and their reactivity patterns including the interconversion of the CuII2(μ‐η2:η2‐peroxo) and CuIII2(μ‐oxo)2 isomers. In this study, absorption spectroscopy, kinetics, and resonance Raman data show that the oxygenated product of (BQPA)CuI]+ initially yields an “end‐on peroxo” species, that subsequently converts to the thermodynamically more stable “bis‐μ‐oxo” isomer (Keq=3.2 at ?90 °C). Calibration of density functional theory calculations to these experimental data suggest that the electrophilic reactivity previously ascribed to end‐on peroxo species is in fact a result of an accessible bis‐μ‐oxo isomer, an electrophilic Cu2O2 isomer in contrast to the nucleophilic reactivity of binuclear CuII end‐on peroxo species. This study is the first report of the interconversion of an end‐on peroxo to bis‐μ‐oxo species in transition metal‐dioxygen chemistry. |
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| Keywords: | copper dioxygen ligands Raman spectroscopy structure– function relationship tyrosinase |
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