Initial synthesis and structure of an all-ferrous analogue of the fully reduced [Fe 4 S 4 ] 0 cluster of the nitrogenase iron protein
- 28 June 2005
- journal article
- research article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences
- Vol. 102 (28), 9741-9744
- https://doi.org/10.1073/pnas.0504258102
Abstract
The synthetic cubane-type iron-sulfur clusters [Fe(4)S(4)(SR)(4)](z) form a four-member electron transfer series (z = 3-, 2-, 1-, and 0), all members of which except that with z = 0 have been isolated and characterized. They serve as accurate analogues of protein-bound [Fe(4)S(4)(SCys)(4)](z) redox centers, which, in terms of core oxidation states, exhibit the redox couples [Fe(4)S(4)](3+/2+) and [Fe(4)S(4)](2+/1+). Clusters with the all-ferrous core [Fe(4)S(4)](0) have never been isolated because of their oxidative sensitivity. Recent work on the Fe protein of Azotobacter vinelandii nitrogenase has demonstrated the formation of the all-ferrous state upon reaction with a strong reductant. Treatment of the cyanide cluster [Fe(4)S(4)(CN)(4)](3-) with K[Ph(2)CO] in acetonitrile/tetrahydrofuran affords the all-ferrous cluster [Fe(4)S(4)(CN)(4)](4-), isolated as the Bu(4)N(+) salt. The x-ray structure demonstrates retention of a cubane-type structure with idealized D(2)(d) symmetry. The Mössbauer spectrum unambiguously demonstrates the [Fe(4)S(4)](0) oxidation state. Bond distances, core volumes, (57)Fe isomer shifts, and visible absorption spectra make evident the high degree of structural and electronic similarity with the fully reduced Fe protein. The attribute of cyanide ligation causes positive [Fe(4)S(4)](2+/1+) and [Fe(4)S(4)](1+/0) redox potential shifts, facilitating the initial isolation of an analogue of the [Fe(4)S(4)](0) protein site.Keywords
This publication has 28 references indexed in Scilit:
- The First All‐Cyanide Fe4S4 Cluster: [Fe4S4(CN)4]3−Angewandte Chemie International Edition, 2004
- Synthesis and Reactions of Cubane-Type Iron−Sulfur−Phosphine Clusters, Including Soluble Clusters of Nuclearities 8 and 16Inorganic Chemistry, 2002
- Crystal Structure of the All-Ferrous [4Fe-4S]0 Form of the Nitrogenase Iron Protein from Azotobacter vinelandii,Biochemistry, 2000
- Evidence for a Two-Electron Transfer Using the All-Ferrous Fe Protein during Nitrogenase CatalysisPublished by Elsevier ,2000
- Effects of Temperature and Pressure on the Mössbauer Spectra of Models for the [4Fe-4S]2+Clusters of Iron−Sulfur Proteins and the Structure of [PPh4]2[Fe4S4(SCH2CO2C2H5)4]Inorganic Chemistry, 1999
- Magnetic Circular Dichroism Study of the All-Ferrous [4Fe-4S] Cluster of the Fe-Protein of Azotobacter vinelandii NitrogenaseJournal of the American Chemical Society, 1998
- All-Ferrous Titanium(III) Citrate Reduced Fe Protein of Nitrogenase: An XAS Study of Electronic and Metrical StructureJournal of the American Chemical Society, 1998
- A simple hydrocarbon electrolyte: completing the electron-transfer series [Fe4S4(SPh)4]1–/2–/3–/4–Journal of the Chemical Society, Chemical Communications, 1985
- Chemical and electrochemical interrelationships of the 1-Fe, 2-Fe, and 4-Fe analogs of the active sites of iron-sulfur proteinsInorganic Chemistry, 1977
- Synthetic analogs of the active sites of iron-sulfur proteins. VI. Spectral and redox characteristics of the tetranuclear clusters [Fe4S4(SR)4]2-Journal of the American Chemical Society, 1974