Cytochrome c nitrite reductase and siroheme-containing nitrite reductase catalyze the six-electron, eight-proton reduction of nitrite to ammonium as part of the global nitrogen cycle. In this talk, the activity of iron and cobalt complexes that mimic these enzymes will be described. One complex is a small cobalt-peptide complex (CoGGH) with an onset potential for nitrite reduction of -0.65 V vs Ag/AgCl (1M KCl) at pH 7.2. CoGGH also catalyzes the reduction of proposed intermediates nitric oxide and hydroxylamine to ammonium. The second catalyst is a pentadentate complex of iron featuring a redox-active ligand with protonatable sites (“FeN5H2”), which catalyzes nitrite reduction to hydroxylamine and ammonium, with ammonium being produced at longer reaction times. Compared to CoGGH, this complex has a lower onset potential for catalysis (-0.90 V) but is notable for being an iron-based catalyst, more closely mimicking the enzymes. Progress toward understanding mechanism and the effects of catalyst modification and reaction conditions on activity will be described.

Electrocatalytic nitrite reduction to hydroxylamine and ammonium in neutral pH water

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.