Snapshots of Dioxygen Activation by Copper: The Structure of a 1:1 Cu/O₂ Adduct and Its Use in Syntheses of Asymmetric Bis(μ-oxo) Complexes

The X-ray structure of a 1:1 Cu/O2 adduct revealed side-on (η2) O2 coordination. Density functional calculations corroborated the structure, indicated a significant contribution of a Cu(III)−(O22-) resonance form, and provided insights into the key bonding interactions. Reaction of a 1:1 adduct supported by a slightly different β-diketiminate ligand with Cu(I) reagents resulted in the formation of novel asymmetric bis(μ-oxo) complexes that were identified by EPR, UV−vis, and Raman spectroscopy, as well as by an X-ray structure in one instance.