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Redox active iron nitrosyl units in proton reduction electrocatalysis

Hsieh, Chung-Hung and Ding, Shengda and Erdem, Özlen F. and Crouthers, Danielle J. and Liu, Tianbiao and McCrory, Charles C. L. and Lubitz, Wolfgang and Popescu, Codrina V. and Reibenspies, Joseph H. and Hall, Michael B. and Darenbourg, Marcetta Y. (2014) Redox active iron nitrosyl units in proton reduction electrocatalysis. Nature Communications, 5 . Art. No. 3684. ISSN 2041-1723. doi:10.1038/ncomms4684.

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Base metal, molecular catalysts for the fundamental process of conversion of protons and electrons to dihydrogen, remain a substantial synthetic goal related to a sustainable energy future. Here we report a diiron complex with bridging thiolates in the butterfly shape of the 2Fe2S core of the [FeFe]-hydrogenase active site but with nitrosyl rather than carbonyl or cyanide ligands. This binuclear [(NO)Fe(N_2S_2)Fe(NO)_2]+ complex maintains structural integrity in two redox levels; it consists of a (N_2S_2)Fe(NO) complex (N_2S_2=N,N′-bis(2-mercaptoethyl)-1,4-diazacycloheptane) that serves as redox active metallodithiolato bidentate ligand to a redox active dinitrosyl iron unit, Fe(NO)_2. Experimental and theoretical methods demonstrate the accommodation of redox levels in both components of the complex, each involving electronically versatile nitrosyl ligands. An interplay of orbital mixing between the Fe(NO) and Fe(NO)_2 sites and within the iron nitrosyl bonds in each moiety is revealed, accounting for the interactions that facilitate electron uptake, storage and proton reduction.

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McCrory, Charles C. L.0000-0001-9039-7192
Lubitz, Wolfgang0000-0001-7059-5327
Additional Information:© 2014 Macmillan Publishers Limited. Received 11 November 2013; Accepted 18 March 2014; Published 02 May 2014. We are grateful for financial support from the National Science Foundation (CHE-1266097 to M.Y.D., CHE-0910552 to M.B.H. and CHE-0956779 to C.V.P.) and the R.A. Welch Foundation (A-0924 to M.Y.D. and A-0648 to M.B.H.). We acknowledge Gudrun Klihm for EPR technical support and financial support from the EU/Energy Network Project SOLAR-H2 (FP7 contract 212508) and the Max Planck Society (to Ö.F.E. and W.L.). Bulk electrolysis measurements are based in part on work performed at the Joint Center for Artificial Photosynthesis, a DOE Innovation Hub, supported through the Office of Science of the US Department of Energy under Award Number DE-SC0004993. C.-H.H. and M.Y.D. performed synthesis and characterization; S.D. and M.B.H. performed computational studies; D.J.C., T.L. and C.C.L.M. performed the electrochemical studies and hydrogen detection; Ö.F.E. and W.L. performed the EPR measurements and interpretation; C.V.P. performed the Mossbauer measurements; The X-ray crystal structures were determined by C.-H.H. and J.H.R. The manuscript was drafted by all with final edits by S.D., M.Y.D. and M.B.H. The authors declare no competing financial interests. Accession codes: The X-ray crystallographic coordinates for structures reported in this Article have been deposited at the Cambridge Crystallographic Data Centre (CCDC), under deposition number CCDC940518 (1red). These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via
Funding AgencyGrant Number
Robert A. Welch FoundationA-0924
Robert A. Welch FoundationA-0648
EU/Energy Network Project SOLAR-H2212508
Max Planck SocietyUNSPECIFIED
Department of Energy (DOE)DE-SC0004993
Record Number:CaltechAUTHORS:20140314-123801645
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Official Citation:Hsieh, C.-H. et al. Redox active iron nitrosyl units in proton reduction electrocatalysis. Nat. Commun. 5:3684 doi: 10.1038/ncomms4684 (2014).
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:44341
Deposited By: George Porter
Deposited On:17 Jul 2014 18:14
Last Modified:10 Nov 2021 16:51

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