The activation of O2 is a process that occurs naturally when enzymes containing iron centers, known as mononuclear non-heme iron oxygenase (MNO) enzymes, oxidize challenging substrates. The objective of this project is to develop synthetic model complexes that can mimic the reactivity properties of these MNO enzymes. The use of iron in these catalytic systems is particularly attractive as this metal is earth-abundant and non-toxic and thus this effort opens new avenues in inexpensive and sustainable catalytic transformations. An N2O1 ligand set and its reaction with α-ketoglutarate to generate the FeII/α-ketoglutarate complex was investigated as an MNO enzyme mimic. We have experimentally observed that the structurally characterized fac-[FeII(N2O1)(sol)3]+ complex: (i) rapidly reacts with a variety of α-ketoacids to form 1:1 complexes, (ii) shows significantly enhanced oxygen sensitivity when coordinated by α-ketoacids, (iii) rapidly decomposes the α-ketoacid ligand to CO2 and the corresponding carboxylate ligand, and (iv) generates an Fe-based reactive intermediate that is kinetically competent. A cyclic reaction was observed, where each mole of α-ketoglutarate added, gave rise to 1 mole each of water, formaldehyde, and succinic acid (completely coupled reaction). A Nash Assay was performed to determine the amount of formaldehyde within each sample. A Karl Fischer titration was used to determine the amount of water within each sample. Supported by NSF-REU, Boston University

Dioxygen activation by mononuclear non-heme iron oxygenases and the corresponding model complexes

249th National Meeting (2015)

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