Abstract
O-2 bubbling into a THF solution of Fe-II(BDPP) (1) at -80 degrees C generates a reversible bright yellow adduct 2. Characterization by resonance Raman and Mossbauer spectroscopy provides complementary insights into the nature of 2. The former shows a resonance-enhanced vibration at 1125 cm(-1), which can be assigned to the v(O-O) of a bound superoxide, while the latter reveals the presence of a high-spin iron(III) center that is exchange-coupled to the superoxo ligand, like the Fe-III-O-2(-) pair found for the O-2 adduct of 4-nitrocatechol-bound homoprotocatechuate 2,3-dioxygenase. Lastly, 2 oxidizes dihydroanthracene to anthracene, supporting the notion that Fe-III-O-2(-) species can carry out H atom abstraction from a C-H bond to initiate the 4-electron oxidation of substrates proposed for some nonheme iron enzymes.
