Abstract
Reaction betwenn molecular oxygen and polystyrene covalently bonded Co(II) protoporphyrin IX complex, which was prepaired by the incorporation of a cobaltous ion into the metal‐free porphyrin polymer, was studied in the presence of N‐ethylimidazole by measuring visible absorption and electron spin resonance spectra. It was found that the complex forms a monomeric oxygen adduct reversibly at low temperature dependent on oxygen pressure. In the presence of molecular oxygen, a new electron spin resonance signal due to the oxygen complex at g~iso~=2.02 shows no superhyperfine splitting structure in fluid toluene solution even at −80 °C, but it was observed in frozen toulene glass solution at −120°C, The oxygen adducts of the complexes between C0(II) protoporphyrin IX dimethyl ester and N‐ethylimidazole and copoly(styrene‐N‐vinylimidazole) showed eight resolved superhyperfine splitting at −40 and −60°C, respectively. The polymer covalently bonded Co(II) complex with N‐ethylimidazole was oxidized at room temperature under oxygen atmosphere. It was suggested that a Co(II) porphyrin–oxygen adduct with an axial ligand may be oxidised monomolecularly at high temperature.