Peer-Reviewed Journal Details
Mandatory Fields
Hugenbruch S.;Shafaat H.;Krämer T.;Delgado-Jaime M.;Weber K.;Neese F.;Lubitz W.;Debeer S.
2016
January
Physical Chemistry Chemical Physics
In search of metal hydrides: An X-ray absorption and emission study of [NiFe] hydrogenase model complexes
Published
13 ()
Optional Fields
18
16
10688
10699
© 2016 the Owner Societies. Metal hydrides are invoked as important intermediates in both chemical and biological H2production. In the [NiFe] hydrogenase enzymes, pulsed EPR and high-resolution crystallography have argued that the hydride interacts primarily at the Ni site. In contrast, in [NiFe] hydrogenase model complexes, it is observed that the bridging hydride interacts primarily with the Fe. Herein, we utilize a combination of Ni and Fe X-ray absorption (XAS) and emission (XES) spectroscopies to examine the contribution of the bridging hydride to the observed spectral features in [(dppe)Ni(μ-pdt)(μ-H)Fe(CO)3]+. The corresponding data on (dppe)Ni(μ-pdt)Fe(CO)3are used as a reference for the changes that occur in the absence of a hydride bridge. For further interpretation of the observed spectral features, all experimental spectra were calculated using a density functional theory (DFT) approach, with excellent agreement between theory and experiment. It is found that the iron valence-to-core (VtC) XES spectra reveal clear signatures for the presence of a Fe-H interaction in the hydride bridged model complex. In contrast, the Ni VtC XES spectrum largely reflects changes in the local Ni geometry and shows little contribution from a Ni-H interaction. A stepwise theoretical analysis of the hydride contribution and the Ni site symmetry provides insights into the factors, which govern the different metal-hydride interactions in both the model complexes and the enzyme. Furthermore, these results establish the utility of two-color XES to reveal important insights into the electronic structure of various metal-hydride species.
1463-9076
10.1039/c5cp07293j
Grant Details