Dioxygen-Derived Nonheme Mononuclear FeIII(OH) Complex and Its Reactivity with Carbon Radicals

A new tetradentate, monoanionic, mixed N/O donor ligand (BNPA(Ph2)O(-)) with second coordination sphere H-bonding groups has been synthesized for stabilization of a terminal Fe-III(OH) complex. The complex Fe-II(BNPA(Ph2)O)(OTf) (1) reacts with O-2 to give a mononuclear terminal Fem(OH) complex, Fe-III(OH)(BNPA(Ph2)O)(OTf) (2), both of which were characterized by X-ray diffraction, electrospray ionization mass spectrometry, UV-vis, H-1 and F-19 nuclear magnetic resonance, Fe-57 Mossbauer, and electron paramagnetic resonance spectroscopies. Treatment of 2 with carbon radicals (Ar3C.) gives Ar3COH and the Fe-II complex 1, in direct analogy with the elusive radical rebound process proposed for nonheme iron enzymes.