An Octahedral Coordination Complex of Iron(VI)

The hexavalent state, considered to be the highest oxidation level accessible for iron, has previously been found only in the tetrahedral ferrate dianion, FeO ₄ ^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 \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \(\mathrm{d}_{xy}^{2}\) ground electronic configuration. The compound is stable at 77 kelvin and yields a high-spin Fe(III) species upon warming.