Issue 4, 2017

Acid/base triggered interconversion of μ-η22-peroxido and bis(μ-oxido) dicopper intermediates capped by proton-responsive ligands

Abstract

CuII2(μ-η22-peroxido) and CuIII2(μ-oxido)2 cores represent key intermediates in copper/dioxygen chemistry, and they are mechanistically important for biological hydroxylation and oxidation reactions mediated by dinuclear (type III) copper metalloenzymes. While the exact nature of the active species in different enzymes is still under debate, shifting equilibria between Cux/O2 species is increasingly recognized as a means of switching between distinct reactivity patterns of these intermediates. Herein we report comprehensive spectroscopic, crystallographic and computational analysis of a family of synthetic CuII2(μ-η22-peroxido) and CuIII2(μ-oxido)2 dicopper complexes with a bis(oxazoline) (BOX) capping ligand. In particular, we demonstrate that a reversible peroxido/bis(μ-oxido) interconversion of the [Cu2O2] core can be triggered by peripheral (de)protonation events on the ligand backbone. As the copper ions in the enzymes are typically supported by histidine imidazoles that offer a backside N atom amenable to potential (de)protonation, it is well conceivable that the shifting of equilibria between the [Cu2O2] species in response to changes in local pH is biologically relevant.

Graphical abstract: Acid/base triggered interconversion of μ-η2:η2-peroxido and bis(μ-oxido) dicopper intermediates capped by proton-responsive ligands

Supplementary files

Article information

Article type
Edge Article
Submitted
31 Oct 2016
Accepted
22 Jan 2017
First published
17 Feb 2017
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY-NC license

Chem. Sci., 2017,8, 3031-3037

Acid/base triggered interconversion of μ-η22-peroxido and bis(μ-oxido) dicopper intermediates capped by proton-responsive ligands

V. E. Goswami, A. Walli, M. Förster, S. Dechert, S. Demeshko, M. C. Holthausen and F. Meyer, Chem. Sci., 2017, 8, 3031 DOI: 10.1039/C6SC04820J

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