There are many examples of manganese-dependent enzymes in nature that are proposed to utilize manganese-oxygen intermediates. Specifically, peroxomangnese(III) species have been postulated as intermediates in the mechanisms of manganese superoxide dismutase, manganese catalase and oxalate decarboxylase. Peroxomanganese(III) complexes are also involved in synthetic oxidation reactions, such as aldehyde deformylation. Since current mechanistic understanding of these manganese-dependent enzymes is limited, there is a need for detailed studies of relevant model systems. Unfortunately, it is common for synthetic peroxomanganese(III) complexes to be generated in low yields and to also exhibit poor thermal stability. The quinoline-appended-diazocycloalkane ligand employed in this work was designed to enhance the stability of reactive intermediates. The ligand possesses a diazocycloalkane backbone, similar to those shown previously to support peroxomanganese(III) species, but it lacks the common benzylic –CH<sub>2</sub> linker that is believed to be prone to oxidative degradation. Upon ligand metallation, the generated manganese(II) species reacts with triethylamine and hydrogen peroxide at -40°C to form a peroxomanganese(III) intermediate, which has been characterized by both spectroscopic and physical methods. Reactivity studies have been performed to determine the nucleophilic nature of this new peroxomanganese(III) species and to investigate pathways for O–O bond activation.

Investigation of a peroxomanganese(III) species supported by a diazacycloalkane-based tetradentate ligand

255th National Meeting (2018)

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