Observations of the photoredox reactivity of antimony(III) porphyrin complexes are reported. Upon irradiation
with visible light under ambient conditions, a photooxidation to the corresponding dihydroxoantimony(V) porphyrins
occurs. At the same time a two-electron or four-electron reduction of molecular oxygen takes place, depending on
the experimental conditions. In the absence of suitable electron acceptors, a photoinduced disproportionation reaction occurs. The photolysis of antimony(III) porphyrins shows a pronounced wavelength dependence. The reactive
excited state is concluded to be of the metal-centered sp type. An extended model for the electronic structure of
p-type hyper metalloporphyrins is suggested.