932706-71-3Relevant academic research and scientific papers
Chelate control of diiron(I) dithiolates relevant to the [Fe-Fe]-hydrogenase active site
Justice, Aaron K.,Zampella, Giuseppe,De Gioia, Luca,Rauchfuss, Thomas B.,Van Der Vlugt, Jarl Ivar,Wilson, Scott R.
, p. 1655 - 1664 (2008/10/09)
The reaction of Fe2(S2C2H 4)(CO)6 with cis-Ph2PCH=CHPPh2 (dppv) yields Fe2(S2C2H4)(CO) 4(dppv), 1(CO)4, wherein the dppv ligand is chelated to a single iron center. NMR analysis indicates that in 1(CO)4, 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 CH2 of the larger dithiolates. The Fe(CO) 3 subunit in 1(CO)4 undergoes substitution with PMe 3 and cyanide to afford 1(CO)3(PMe3) and (EttN)[1(CN)(CO)3], respectively. Kinetic studies show that 1(CO)4 reacts faster with donor ligands than does its parent Fe 2(S2C2H4)(CO)6. The rate of reaction of 1(CO)4 with PMe3 was first order in each reactant, k = 3.1 × 10-4 M-1 s-1. 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 2(S2C2H4)(CO)6, the enhanced electrophilicity of 1(CO)4 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) 3(PMe3) with Cp2FePF6 yielded [Fe2(S2C2H4)(μ-CO)(CO) 2(dppv)(PMe3)(NCMe)](PF6)2. Reaction of this compound with PMe3 yielded [Fe2(S 2C2H4)-(μ-CO)(CO)(dppv)(PMe 3)2(NCMe)](PF6)2.
