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Title: Iron Complexes Bearing Diphosphine Ligands with Positioned Pendant Amines as Electrocatalysts for the Oxidation of H2

The synthesis and spectroscopic characterization of CpC5F4NFe(PtBu2NBn2)Cl, [3-Cl] (where C5F4N is the tetrafluorpyridyl substituent and PtBu2NBn2 = 1,5-di(tert-butyl)-3,7-di(benzyl)-1,5-diaza-3,7-diphosphacyclooctane) are reported. Complex 3-Cl and previously reported [CpC5F4NFe(PtBu2NtBu2)Cl], 4-Cl, are precursors to intermediates in the catalytic oxidation of H2, including CpC5F4NFe(PtBu2NBn2)H (3-H), CpC5F4NFe(PtBu2NtBu2)H (4-H), [CpC5F4NFe(PtBu2NBn2)]BArF4 ([3](BArF4), [CpC5F4NFe(PtBu2NtBu2)]BArF4 ([4](BArF4), [CpC5F4NFe(PtBu2NBn2)(H2)]BArF4 ([3-H2]BArF4), and [CpC5F4NFe(PtBu2NtBu2H)H]BArF4 ([4-FeH(NH)]BArF4). All of these complexes were characterized by spectroscopic and electrochemical studies; 3-Cl, 3-H and 4-Cl were also characterized by single crystal diffraction studies. 3-H and 4-H are electrocatalysts for H2 (1.0 atm) oxidation in the presence of a excess of the amine base N-methylpyrrolidine, with turnover frequencies at 22 °C of 2.5 s-1 and 0.5 s-1, and overpotentials at Ecat/2 of 235 mV and 95 mV, respectively. Studies of individual chemical and/or electrochemical reactions of the various intermediates provide important insights into the factors governing the overall catalytic activity for H2 oxidation, and provide important insights into the role of the pendant base of the [FeFe] hydrogenase active site. This work was supported by the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences. Pacific Northwest National Laboratory is operated by Battelle for themore » U.S. Department of Energy.« less
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Publication Date:
OSTI Identifier:
Report Number(s):
Journal ID: ISSN 0276-7333; KC0307010
DOE Contract Number:
Resource Type:
Journal Article
Resource Relation:
Journal Name: Organometallics; Journal Volume: 24; Journal Issue: 12
American Chemical Society
Research Org:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
Sponsoring Org:
Country of Publication:
United States
catalysis; iron; hydrogen