A mononuclear iron(II)-alpha-hydroxy acid complex [(Tp(Ph'me))Fe-ll(benzilate)] (Tp(Ph'me) = hydrotris(3-pheny1-5-methylpyrazol-1-yl)borate) of a facial tridentate ligand has been isolated and characterized to explore its catalytic efficiency for aerial oxidation of organic substrates. In the reaction between the iron(II)-benzilate complex and O-2, the metal-coordinated benzilate is stoichiometrically converted to benzophenone with concomitant reduction of dioxygen on the iron center. Based on the results from interception experiments and labeling studies, different iron-oxygen oxidants are proposed to generate in situ in the reaction pathway depending upon the absence or presence of an external additive (such as protic acid or Lewis acid). The five-coordinate iron(II) complex catalytically cis-dihydroxylates olefins and oxygenates the C H bonds of aliphatic substrates using O-2 as the terminal oxidant. The iron(II) complex exhibits better catalytic activity in the presence of a Lewis acid.