Formation and High Reactivity of the anti-Dioxo Form of High-Spin μ-Oxodioxodiiron(IV) as the Active Species That Cleaves Strong C-H Bonds

Recently, it was shown that mu-oxo-mu-peroxodiiron(III) is converted to high-spin mu-oxodioxodiiron(IV) through O-O bond scission. Herein, the formation and high reactivity of the anti-dioxo form of high-spin mu-oxodioxodiiron(IV) as the active oxidant are demonstrated on the basis of resonance Raman and electronic-absorption spectral changes, detailed kinetic studies, DFT calculations, activation parameters, kinetic isotope effects (KIE), and catalytic oxidation of alkanes. Decay of mu-oxodioxodiiron(IV) was greatly accelerated on addition of substrate. The reactivity order of substrates is toluene