17-Electron alkynyl complexes of cyclopentadienyliron(III)
Abstract
The complexes [Fe(CCR)(L–L)(η-C5R′5)][R = But, CO2Me, CO2Et, SiMe3, Ph or CH2OMe, L–L = Ph2PCH2PPh2(dppm), R′= H; R = But or Ph, L–L = Ph2PCH2CH2PPh2(dppe), R′= Me] undergo reversible one-electron oxidation at a platinum electrode in CH2Cl2. Chemical oxidation with [Fe(η-C5H5)2][PF6] gave the isolable salts [Fe(CCR)(dppe)(η-C5Me5)][PF6](R = But or Ph) which Mössbauer spectroscopy suggests to be complexes of FeIII. The ESR spectra of these salts, and of the cations [Fe(CCR)(dppm)(η-C5H5)]+(R = But, CO2Me, CO2Et or Ph), generated by in situ oxidation with [Fe(η-C5H5)2][PF6], are similar to those of low-spin d5 complexes of CrI, MnII and FeIII.