Preparation and Characterization of the Triflate Complex [Cp(dppe)FeOSO2CF3]: A Convenient Access to Labile Five‐ and Six‐Coordinate Iron(I) and Iron(II) Complexes

Treatment of the iron hydride [Cp*(dppe)FeH] (1) with methyl triflate (CH3OSO2CF3) yielded the iron triflate adduct [Cp*(dppe)FeOSO2CF3] (4, 85 %). In the solid state, the triflate is coordinated at the iron center as shown by XRD (dFe–O = 2.118(4) Å) and IR spectroscopy (νSO = 1305 cm–1). In solution, 4 is in equilibrium with the 16‐electron species [Cp*(dppe)Fe]OSO2CF3 (5(OSO2CF3)), 4/5(OSO2CF3) = 2:1). The CV of 4 displays two waves (E1 = –0.74 V, E2 = 0.24 V vs. SCE) assigned to the [Cp*(dppe)Fe(I)]/[Cp*(dppe)Fe(II)]+ and [Cp*(dppe)Fe(II)]+/[Cp*(dppe)Fe(III)]2+ redox couples. Reduction of 4 with Cp2Co provided the complex [Cp*(dppe)Fe(I)] (6, 95 %) and oxidation of 6 with [Cp2Fe]PF6 gave [Cp*(dppe)Fe]PF6 (5(PF6), 98 %). XRD established the pseudo‐trigonal bipyramidal geometry for the five‐coordinated cation 5+. The reactivity of 5(PF6) and 6 toward small molecules (CH2Cl2, H2O, CO, H2, N2) is reported. The new complex [Cp*(dppe)FeOSO2CF3] was prepared by treatment of hydride [Cp*(dppe)FeH] with CH3OSO2CF3 (85 % yield). This compound dissociates in THF, opening the route to the five‐coordinated complexes [Cp*(dppe)Fe] and [Cp*(dppe)Fe]PF6, and to the six‐coordinated derivatives [Cp*(dppe)Fe‐L]PF6 (L = CO, H2, N2, H2O)