LAUSR

The isolation and identification of intermediates formed in the course of the activation of dioxygen at transition metal centers reveals important mechanistic insights concerning such processes. We previously reported the reaction of the dinuclear Cr complex [L2Cr2(MeCN)2] [Li(MeCN)]2 (L=PhSi(OSiPh2O )3) (5) with dioxygen, which resulted in the formation of the Cr oxo complex [L2Cr2O2] [Li(THF)2]2 (6), as the final room temperature stable product. Here we now report the isolation and characterization of an intermediate en route to 6, namely the dinuclear Cr superoxo complex [L2Cr2(O2)2][Li(MeCN)]2 (7). 7 is the first example of a structurally characterized dinuclear Cr superoxo complex with two independent side-on bound superoxo ligands. Reactivity studies outline the capability of this superoxo complex to activate weak O H bonds.