O2 activation by nonheme iron complexes:: A monomeric Fe(III)-oxo complex derived from O2

Iron species with terminal oxo Ligands are implicated as key intermediates in several synthetic and biochemical catalytic cycles. However, there is a dearth of structural information regarding these types of complexes because their instability has precluded isolation under ambient conditions. The isolation and structural characterization of an iron(III) complex with a terminal oxo Ligand, derived directly from dioxygen (O-2), is reported. A stable structure resulted from placing the oxoiron unit within a synthetic cavity Lined with hydrogen-bonding groups. The cavity creates a microenvironment around the iron center that aids in regulating O-2 activation and stabilizing the oxoiron unit. These cavities share properties with the active sites of metalloproteins, where function is correlated strongly with site structure.