The reaction of Fe<sub>2</sub>(S<sub>2</sub>C<sub>2</sub>H <sub>4</sub>)(CO)<sub>6</sub> with cis-Ph<sub>2</sub>PCH=CHPPh<sub>2</sub> (dppv) yields Fe<sub>2</sub>(S<sub>2</sub>C<sub>2</sub>H<sub>4</sub>)(CO) <sub>4</sub>(dppv), 1(CO)<sub>4</sub>, wherein the dppv ligand is chelated to a single iron center. NMR analysis indicates that in 1(CO)<sub>4</sub>, the dppv ligand spans axial and basal coordination sites. In addition to the axial-basal isomer, the 1,3-propanedithiolate and azadithiolate derivatives exist as dibasal isomers. Density functional theory (DFT) calculations indicate that the axial-basal isomer is destabilized by nonbonding interactions between the dppv and the central NH or CH<sub>2</sub> of the larger dithiolates. The Fe(CO) <sub>3</sub> subunit in 1(CO)<sub>4</sub> undergoes substitution with PMe <sub>3</sub> and cyanide to afford 1(CO)<sub>3</sub>(PMe<sub>3</sub>) and (EttN)[1(CN)(CO)<sub>3</sub>], respectively. Kinetic studies show that 1(CO)<sub>4</sub> reacts faster with donor ligands than does its parent Fe <sub>2</sub>(S<sub>2</sub>C<sub>2</sub>H<sub>4</sub>)(CO)<sub>6</sub>. The rate of reaction of 1(CO)<sub>4</sub> with PMe<sub>3</sub> was first order in each reactant, k = 3.1 × 10<sup>-4</sup> M<sup>-1</sup> s<sup>-1</sup>. The activation parameters for this substitution reaction, ΔH‡ = 5.8(5) kcal/mol and ΔS‡ = -48(2) cal/deg·mol, indicate an associative pathway. DFT calculations suggest that, relative to Fe <sub>2</sub>(S<sub>2</sub>C<sub>2</sub>H<sub>4</sub>)(CO)<sub>6</sub>, the enhanced electrophilicity of 1(CO)<sub>4</sub> arises from the stabilization of a "rotated" transition state, which is favored by the unsymmetrically disposed donor ligands. Oxidation of MeCN solutions of 1(CO) <sub>3</sub>(PMe<sub>3</sub>) with Cp<sub>2</sub>FePF<sub>6</sub> yielded [Fe<sub>2</sub>(S<sub>2</sub>C<sub>2</sub>H<sub>4</sub>)(μ-CO)(CO) <sub>2</sub>(dppv)(PMe<sub>3</sub>)(NCMe)](PF<sub>6</sub>)<sub>2</sub>. Reaction of this compound with PMe<sub>3</sub> yielded [Fe<sub>2</sub>(S <sub>2</sub>C<sub>2</sub>H<sub>4</sub>)-(μ-CO)(CO)(dppv)(PMe <sub>3</sub>)<sub>2</sub>(NCMe)](PF<sub>6</sub>)<sub>2</sub>. © 2007 American Chemical Society.
Justice, A.K., Zampella, G., De Gioia, L., Rauchfuss, T.B., van der Vlugt, J.I., & Wilson, S.R. (2007). Chelate control of diiron(I) dithiolates relevant to the [Fe-Fe]-hydrogenase active site. INORGANIC CHEMISTRY, 46(5), 1655-1664.
Citazione: | Justice, A.K., Zampella, G., De Gioia, L., Rauchfuss, T.B., van der Vlugt, J.I., & Wilson, S.R. (2007). Chelate control of diiron(I) dithiolates relevant to the [Fe-Fe]-hydrogenase active site. INORGANIC CHEMISTRY, 46(5), 1655-1664. |
Tipo: | Articolo in rivista - Articolo scientifico |
Carattere della pubblicazione: | Scientifica |
Titolo: | Chelate control of diiron(I) dithiolates relevant to the [Fe-Fe]-hydrogenase active site |
Autori: | Justice, AK; Zampella, G; De Gioia, L; Rauchfuss, TB; van der Vlugt, JI; Wilson, SR |
Autori: | |
Data di pubblicazione: | 5-mar-2007 |
Lingua: | English |
Rivista: | INORGANIC CHEMISTRY |
Digital Object Identifier (DOI): | http://dx.doi.org/10.1021/ic0618706 |
Appare nelle tipologie: | 01 - Articolo su rivista |