Redox active iron nitrosyl units in proton reduction electrocatalysis.
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(N2S2)Fe(NO)2](+) complex maintains structural integrity in two redox levels; it consists of a (N2S2)Fe(NO) complex (N2S2=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.
Department of Chemistry, Texas A&M University, College Station, Texas 77843, USA.
Chung-Hung
CH
Hsieh
Department of Chemistry, Texas A&M University, College Station, Texas 77843, USA.
Shengda
S
Ding
Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, 45470 Muelheim a.d. Ruhr, Germany.
Özlen F
ÖF
Erdem
Department of Chemistry, Texas A&M University, College Station, Texas 77843, USA.
Danielle J
DJ
Crouthers
Center for Molecular Electrocatalysis, Pacific Northwest National Laboratory, Richland, Washington 99354, USA.
Tianbiao
T
Liu
Joint Center for Artificial Photosynthesis, California Institute of Technology, Pasadena, California 91125, USA.
Charles C L
CC
McCrory
Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, 45470 Muelheim a.d. Ruhr, Germany.
Wolfgang
W
Lubitz
Department of Chemistry, Ursinus College, Collegeville, Pennsylvania 19426, USA.
Codrina V
CV
Popescu
Department of Chemistry, Texas A&M University, College Station, Texas 77843, USA.
Joseph H
JH
Reibenspies
Department of Chemistry, Texas A&M University, College Station, Texas 77843, USA.
Michael B
MB
Hall
Department of Chemistry, Texas A&M University, College Station, Texas 77843, USA.
Marcetta Y
MY
Darensbourg
D002384:Catalysis; D055664:Electrochemical Techniques; D004578:Electron Spin Resonance Spectroscopy; D007501:Iron / Q000737:chemistry*; D009589:Nitrogen Oxides / Q000737:chemistry*; D010084:Oxidation-Reduction; D011522:Protons; D015204:Spectroscopy, Mossbauer
D009589:Nitrogen Oxides; D011522:Protons; C073661:dinitrosyl iron complex; D007501:Iron