Heinemann FW (2007)
Publication Status: Published
Publication Type: Journal article
Publication year: 2007
Publisher: WILEY-V C H VERLAG GMBH
Pages Range: 3385-3393
Journal Issue: 21
The trinuclear complex [('S-2')(Ni(PMe3)}(2)Fe(CO)('S-2')(2)] (1) {'S-2'(2-) = 1,2-benzenedithiolate(2-)} has been reported as a structural as well as functional model for [NiFe] hydrogenases since it contains key structural features of the [NiFe] hydrogenase active site, and is oxidized by protons to give [1](+), and H-2. Complex 1 formed as an unexpected product from the reaction of [Fe(CO)(2)('S-3')](2) {'S-3'(2-) = bis(2-mercaptophenyl) sulfide(2-)} and [Ni(PMe3)(2)('S-2')]. Both the iron and nickel centers of 1 are chelated by 'S-2' donors, but not with any 'S-3' ligand. In order to understand this reaction, the new precursor [Fe(CO)(2)(S-si(3))](2) (2) {S-si(3)2- = bis(2-mercapto-3-tri-methylsilylphenyl) sulfide(2-)) was synthesized. Compound 2 readily loses its CO ligand to give [Fe(CO)(S-si(3))](2) (3), which consists of two 16 valence electron fragments and could be isolated in the solid state. Conversion of 3 to 2 is feasible with gentle bubbling of CO gas for about 2 min. Treatment of 2 with [Ni(PMe3)(2)('S-2')] resulted exclusively in the formation of complex 1, which confirms that all three 'S-2' ligands in 1 originate from [Ni(PMe3)(2)('S-2')]. Therefore, an alternative synthesis of 1, which does not involve any 'S-3' ligand, has been developed. Density functional theory (DFT) calculations suggest that the oxidation states of the metal centers are Fe-II and Ni-II and do not change upon oxidation of 1 to [1](+). The impaired electron in [1](+) is located to a large extent on the nickel atoms and the adjacent thiolate donor functions. The charge, however, is distributed over the whole cluster, main parts residing on the 'S-2' ligands. Preliminary constant potential coulometric measurements indicate that 1 mediates the reduction of protons to dihydrogen at a mild potential (-0.48 V vs. NHE). Based upon these experimental and theoretical results, plausible mechanisms for this reduction are briefly discussed. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007).
APA:
Heinemann, F.W. (2007). Alternative synthesis, density functional calculations and proton reactivity study of a trinuclear [NiFe] hydrogenase model compound. European Journal of Inorganic Chemistry, 21, 3385-3393. https://doi.org/10.1002/ejic.200601077
MLA:
Heinemann, Frank Wilhelm. "Alternative synthesis, density functional calculations and proton reactivity study of a trinuclear [NiFe] hydrogenase model compound." European Journal of Inorganic Chemistry 21 (2007): 3385-3393.
BibTeX: Download