Metalloenzymes activate dioxygen to carry out various biological reactions. The dioxygen activation at the catalytic sites of the metalloenzymes occurs through several steps including the binding of O2 at a reduced metal center, the formation of metal-superoxo and -peroxo complexes, and the O-O bond cleavage of metal-hydroperoxo species to form high-valent metal-oxo oxidants. Because these mononuclear metal-dioxygen (M-O2(H)) adducts are implicated as key intermediates in dioxygen activation reactions catalyzed by metalloenzymes, studies of the structural and spectroscopic properties and reactivities of synthetic biomimetic analogues of these species have supported our understanding of their biological chemistry. In this presentation, we report the synthesis, structural and spectroscopic characterization, and reactivity studies of M-O2(H) complexes bearing tetraazamacrocyclic pyridinophane ligands. We have used various spectroscopic techniques, including UV-vis, EPR and resonance Raman spectroscopy, and density functional theory calculations to characterize several novel M-O2(H) complexes. Reactivity studies performed with the M-O2(H) complexes in oxidative nucleophilic and electrophilic reactions. Different steric properties of the supporting ligands control the reactivity of the intermediates. In addition, we investigate the reactivity comparison of M-O2 and -O2H species toward organic substrates.

Mononuclear metal-O2(H) adducts in oxidative nucleophilic and electrophilic reactions

251st National Meeting (2016)

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