An Octahedral Coordination Complex of Iron(VI)

Abstract

The hexavalent state, considered to be the highest oxidation level accessible for iron, has previously been found only in the tetrahedral ferrate dianion, FeO₄^2–. We report the photochemical synthesis of another Fe(VI) compound, an octahedrally coordinated dication bearing a terminal nitrido ligand. Mössbauer and x-ray absorption spectra, supported by density functional theory, are consistent with the octahedral structure having an Fe N triple bond of 1.57 angstroms and a singlet ground electronic configuration. The compound is stable at 77 kelvin and yields a high-spin Fe(III) species upon warming.