Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2003 Apr 1;100(7):3683-8.
doi: 10.1073/pnas.0536955100. Epub 2003 Mar 17.

The organometallic active site of [Fe]hydrogenase: models and entatic states

Marcetta Y Darensbourg  1 , Erica J Lyon, Xuan Zhao, Irene P Georgakaki
Affiliations

The organometallic active site of [Fe]hydrogenase: models and entatic states

Marcetta Y Darensbourg et al. Proc Natl Acad Sci U S A. .

Abstract

The simple organometallic, (mu-S(2))Fe(2)(CO)(6), serves as a precursor to synthetic analogues of the chemically rudimentary iron-only hydrogenase enzyme active site. The fundamental properties of the (mu-SCH(2)CH(2)CH(2)S)[Fe(CO)(3)](2) compound, including structural mobility and regioselectivity in cyanidecarbon monoxide substitution reactions, relate to the enzyme active site in the form of transition-state structures along reaction paths rather than ground-state structures. Even in the absence of protein-based active-site organization, the ground-state structural model complexes are shown to serve as hydrogenase enzyme reaction models, H(2) uptake and H(2) production, with the input of photo- or electrochemical energy, respectively.

PubMed Disclaimer

Figures

Figure 1
Figure 1
Representation of the evolution of CO-mobilized iron sulfide in nature to yield the active site of [Fe]H2ase and in chemists' laboratories to yield model complexes. [The structure of [Fe]H2ase is reprinted with permission from Peters et al. (24) (Copyright 1998 American Association for the Advancement of Science).]
Figure 2
Figure 2
Structures, ν(CO), ν(CN) stretching frequencies (26), and possible oxidation-state assignments of the oxidized (Hox) and reduced (Hred) forms of the [Fe]H2ase (44) (Fe⋅⋅⋅Fe distances are 2.6 Å for both).
Figure 3
Figure 3
Stereochemical nonrigidity of (μ-pdt)[Fe(CO)3]2 (a) and (μ-o-xyldt)[Fe(CO)3]2 (b).
Figure 4
Figure 4
Polarization of Fe—Fe bond electron density upon Fe(CO)3 unit rotation in (μ-pdt)[Fe(CO)3]2 as shown by the highest occupied molecular orbitals (HOMOs) and the Mulliken charges.
Figure 5
Figure 5
Proposed mechanism for the two-step CN−/CO substitution reaction in (μ-pdt)[Fe(CO)3]2 to yield (μ-pdt)[Fe(CO)2(CN)]formula image.
Figure 6
Figure 6
Calculated and observed diiron complexes with a bridging CO group, closer structural analogues to the active site of [Fe]H2ase.
Scheme 1
Scheme 1
Binuclear oxidative addition of electrophiles H+ and SMe+ to FeIFeI.
Scheme 2
Scheme 2
H/D exchange mechanism.
Scheme 3
Scheme 3
Mechanism for electrocatalytic production of H2.
See this image and copyright information in PMC

References

    1. Stephenson M, Stickland L H. Biochem J. 1931;25:205–214. - PMC - PubMed
    1. Adams M W W, Mortenson L E, Chen J-S. Biochim Biophys Acta. 1981;594:105–176. - PubMed
    1. Graf E-G, Thauer R K. FEBS Lett. 1981;136:165–169.
    1. Cammack R, Frey M, Robson R, editors. Hydrogen as a Fuel. London: Taylor & Francis; 2001.
    1. Hoffmann P. Tomorrow's Energy: Hydrogen, Fuel Cells, and Prospects for a Cleaner Planet. Cambridge, MA: MIT Press; 2001.

Publication types