Synthesis and characterization of a superoxo complex of the dicobalt cofacial diporphyrin [(.mu.-O2)Co2(DPB)(1,5-diphenylimidazole)2][PF6], the structure of the parent dicobalt diporphyrin Co2(DPB), and a new synthesis of the free-base cofacial diporphyrin H4(DPB)

Abstract

Chemical oxidation of the dicobalt cofacial diporphyrin Co 2 II / II (DPB), followed by exposure to dioxygen affords the bridged superoxo complex [(μ-O 2 )Co 2 (DPB)][PF 6 ]. This μ-superoxo complex has been implicated in possible mechanisms of four-electron dioxygen reduction by dicobalt cofacial diporphyrins but has not been isolated and fully-characteized previously.