Impact of Intramolecular Hydrogen Bonding on the Reactivity of Cupric Superoxide Complexes with O−H and C−H Substrates

The dioxygen reactivity of a series of TMPA‐based copper(I) complexes (TMPA=tris(2‐pyridylmethyl)amine), with and without secondary‐coordination‐sphere hydrogen‐bonding moieties, was studied at ?135 °C in 2‐methyltetrahydrofuran (MeTHF). Kinetic stabilization of the H‐bonded ( TMPA)Cu^II(O₂^.?)]⁺ cupric superoxide species was achieved, and they were characterized by resonance Raman (rR) spectroscopy. The structures and physical properties of ( TMPA)Cu^II(N₃^?)]⁺ azido analogues were compared, and the O₂^.? reactivity of ligand–Cu^I complexes when an H‐bonding moiety is replaced by a methyl group was contrasted. A drastic enhancement in the reactivity of the cupric superoxide towards phenolic substrates as well as oxidation of substrates possessing moderate C?H bond‐dissociation energies is observed, correlating with the number and strength of the H‐bonding groups.