A Reactive, Photogenerated High-Spin ( = 2) Fe(O) Complex via O Activation.

Addition of dioxygen at low temperature to the non-heme ferrous complex Fe(MeTACN)((OSi)O) () in 2-MeTHF produces a peroxo-bridged diferric complex Fe(μ-O)(MeTACN)((OSi)O) (), which was characterized by UV-vis, resonance Raman, and variable field Mössbauer spectroscopies. Illumination of a frozen solution of in THF with white light leads to homolytic O-O bond cleavage and generation of a Fe(O) complex (ν(Fe=O) = 818 cm; δ = 0.22 mm s, Δ = 0.23 mm s). Variable field Mössbauer spectroscopy measurements show that is a rare example of a high-spin = 2 Fe(O) complex and the first synthetic example to be generated directly from O. Complex is highly reactive, as expected for a high-spin ferryl, and decays rapidly in fluid solution at cryogenic temperatures. This decay process in 2-MeTHF involves C-H cleavage of the solvent. However, the controlled photolysis of with visible light and excess phenol substrate leads to competitive phenol oxidation, via the proposed transient generation of as the active oxidant.