An Anionic, Tetragonal Copper(Ⅱ) Superoxide Complex

摘要

Insight into copper-oxygen species proposed as intermediates in oxidation catalysis is provided by the identification of a Cu(Ⅱ)-superoxide complex supported by a sterically hindered, pyridinedicarboxamide ligand. A tetragonal, end-on superoxide structure is proposed based on DFT calculations and UV-vis, NMR, EPR, and resonance Raman spectroscopy. The complex yields a trans-1,2-peroxodicopper(Ⅱ) species upon reaction with [(tmpa)Cu(CH_3CN)]OTf and, unlike other known Cu(Ⅱ)-superoxide complexes, acts as a base rather than an electrophilic (H-atom abstracting) reagent in reactions with phenols.