Species containing iron at an oxidation state higher than +III are often termed "high-valent iron" and are considered to be key catalytic intermediates in biochemistry. Here, we report the direct time-domain probing of the photochemical formation of an octahedral nitrido iron(V) complex through dinitrogen cleavage from an diazido iron(III) precursor by using femtosecond mid-infrared (MIR) spectroscopy. From the time-resolved vibrational spectra, a mechanism is suggested for the photooxidation of the metal within 10 ps. This mechanism involves an initial ultrafast non-adiabatic transition, followed by a quasithermal N-N bond rupture on the ground-state surface.
Keywords: IR spectroscopy; dynamics in liquids; femtosecond spectroscopy; iron; photochemistry.
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