Valence-to-Core X-ray Emission Spectroscopy as a Probe of O−O Bond Activation in Cu2O2 Complexes

Abstract

Valence-to-Core (VtC) X-ray emission spectroscopy (XES) was used to directly detect the presence of an O−O bond in a complex comprising the [CuII2(μ-η2:η2-O2)]2+ core relative to its isomer with a cleaved O−O bond having a [CuIII2(μ-O)2]2+ unit. The experimental studies are complemented by DFT calculations, which show that the unique VtC XES feature of the [CuII2(μ-η2:η2-O2)]2+ core corresponds to the copper stabilized in-plane 2p π peroxo molecular orbital. These calculations illustrate the sensitivity of VtC XES for probing the extent of O−O bond activation in μ-η2:η2-O2 species and highlight the potential of this method for time-resolved studies of reaction mechanisms.