Intramolecular Hydrogen Bonding Enhances Stability and Reactivity of Mononuclear Cupric Superoxide Complexes

[(L)­CuII(O2•–)]+ (i.e., cupric-superoxo)
complexes, as the first and/or key
reactive intermediates in (bio)­chemical Cu-oxidative processes, including
in the monooxygenases PHM and DβM, have been systematically
stabilized by intramolecular hydrogen bonding within a TMPA ligand-based
framework. Also, gradual strengthening of ligand-derived H-bonding
dramatically enhances the [(L)­CuII(O2•–)]+ reactivity toward hydrogen-atom abstraction (HAA)
of phenolic O–H bonds. Spectroscopic properties of the superoxo
complexes and their azido analogues, [(L)­CuII(N3–)]+, also systematically change as
a function of ligand H-bonding capability.

[(L)­CuII(O2•–)]⁺（即cupric-superoxo，超氧合二价铜）配合物，作为（生物）化学铜氧化过程中的初始乃至关键活性中间体（包括单加氧酶PHM与DβM参与的反应过程），已通过基于TMPA配体骨架的分子内氢键作用实现系统性稳定。此外，配体衍生氢键的逐步强化可显著提升[(L)­CuII(O2•–)]⁺对酚类O–H键的氢原子转移（hydrogen-atom abstraction, HAA）反应活性。该类超氧配合物及其叠氮类似物[(L)­CuII(N3⁻)]⁺的光谱性质，同样会随配体氢键能力的变化呈现系统性改变。