Synthesis, structural, redox and mössbauer characterization of four-electron-oxidized tetrakis(cyclohexyl)iron(II)porphodimethene with different axial ligations

Abstract

The cover picture shows induced electron-transfer reactions with I₂ or Br₂ as external oxidant, Fe^III as internal oxidant, and coordinated porphyrinogen as internal reductant. As a result of this simultaneous metal-and ligand-based redox reaction, the square-planar iron(III) complex is transformed to a square-pyramidal iron(II) complex, and the tetraanionic porphyrinogen ligand is oxidized to the neutral porphodimethene. The iron(III/II) redox potential of porphodimethene complexes are more positive than that of the heme cofactor. The large quadruple splitting with large isomeric shift indicates a high-spin state (S=2) for the [LΔ Δ FeII-I]⁺ cation.