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Disque Hall, Room 109, 32 South 32nd Street, Philadelphia, PA 19135


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Seminar: Iron Nitroxyl Complexes as Central Intermediates in Nitric Oxide Reductases

Thursday, February 6, 2014

4:30 PM-6:00 PM

Nicolai Lehnert, PhD, Department of Chemistry, University of Michigan


Title: Iron Nitroxyl Complexes as Central Intermediates in Nitric Oxide Reductases
Abstract: Despite the extensive work that has been completed on heme and non-heme iron-nitrosyl complexes, {FeNO}7 in the Enemark-Feltham notation, corresponding, one-electron reduced {FeNO}8 complexes where a nitroxyl anion (NO−) is formally bound to an iron(II) center have remained largely elusive. These complexes, and their protonated iron(II)-NHO analogs, are now entering the limelight as proposed key intermediates in nitrite (NO2) and nitric oxide (NO) reducing enzymes in bacteria and fungi. In addition, HNO has been proposed to be a signaling molecule in mammals and also shows protective properties under reperfusion after stroke and heart attack. For these functions, iron-containing proteins are again thought to be of key significance for the production and as receptors of HNO in vivo. In this presentation, recent key advances in the preparation, spectroscopic characterization, and reactivity of ferrous heme and non-heme nitroxyl (NO−/HNO) complexes are highlighted that have greatly enhanced our understanding of the properties and potential biological roles of these species.

Relevant references:
1. L. E. Goodrich, S. Roy, E. E. Alp, J. Zhao, M. Y. Hu, N. Lehnert, "Electronic Structure and Biologically Relevant Reactivity of Low-Spin {FeNO}8 Porphyrin Model Complexes: New Insight from a Bis-Picket Fence Porphyrin", Inorg. Chem. 2013, 52, 7766-7780
2. Zheng, T. C. Berto, E. Dahl, M. B. Hoffman, A. L. Speelman, N. Lehnert, "The Functional Model Complex [Fe2(BPMP)(OPr)(NO)2](BPh4)2 provides Insight into the Mechanism of Flavodiiron NO Reductases", J. Am. Chem. Soc. 2013, 135, 4902-4905
3. A. L. Speelman, N. Lehnert, "Characterization of a High-Spin Non-Heme {FeNO}8 Complex: Implications for the Reactivity of Iron Nitroxyl Species in Biology", Angew. Chem. Int. Ed. 2013, 52, 12283-12287