Oxidative Addition of Phosphine-Tethered Thiols to Iron Carbonyl: Binuclear Phosphinothiolate Complexes, (μ-SCH2CH2PPh2)2Fe2(CO)4, and Hydride Derivatives
- 22 January 2002
- journal article
- research article
- Published by American Chemical Society (ACS) in Inorganic Chemistry
- Vol. 41 (4) , 699-708
- https://doi.org/10.1021/ic010741g
Abstract
The mononuclear complex Fe(CO)4(PPh2CH2CH2SH), 1, is isolated as an intermediate in the overall reaction of PPh2CH2CH2SH with [Fe0(CO)4] sources to produce binuclear bridging thiolate complexes. Photolysis is required for loss of CO and subsequent S−H activation to generate the metal−metal bonded FeI−FeI complex, (μ-SCH2CH2PPh2)2Fe2(CO)4, 2. Isomeric forms of 2 derive from the apical or basal position of the P-donor ligand in the pseudo square pyramidal S2Fe(CO)2P coordination spheres. This position in turn is dictated by the stereochemistry of the μ-S−CH2 bond, designated as syn or anti with respect to the Fe2S2 butterfly core. Addition of strong acids engages the FeI−FeI bond density as a bridging hydride, [(μ-H)-anti-2]+[SO3CF3]- or [(μ-H)-syn-2]+[SO3CF3]-, with formal oxidation to FeII−H−FeII. Molecular structures of anti-2, syn-2, and [(μ-H)-anti-2]+[SO3CF3]- were determined by X-ray crystallography and show insignificant differences in distance and angle metric parameters, including the Fe−Fe bond distances which average 2.6 Å. The lack of coordination sphere rearrangements is consistent with the ease with which deprotonation occurs, even with the weak base, chloride. The FeI−FeI bond, supported by bridging thiolates, therefore presents a site where a proton might be taken up and stored as a hydride without impacting the overall structure of the binuclear complex.Keywords
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