Reaction of Iron Phthalocyanine with Oxygen: Critical Survey and New Data on the Structure of the Forming PcFe(II) μ-Oxo Dimer

Reaction of iron tetra-4-tert-butylphthalocyanine (Pc ^t Fe) with oxygen in noncoordinating solvents at Pc ^t Fe concentrations within (0.63-10.71) × 10^-2 M was studied. The uptake of oxygen (moles per mole of iron phthalocyanine taken into reaction) depends on the concentration of the complex, varying in the examined concentration range from 1/5 to 1/2.7, and thus can significantly differ from the value implied by the stoichiometry of the Pc^tFe -oxo dimer. This fact is due to consumption of the reactants in side processes, including oxidative degradation of the macroring. Indeed, the -oxo dimer is the major but not the only product of reaction of Pc^tFe with oxygen: Up to 20% of the initial complex undergoes oxidative degradation. These data, in combination with the spectral and chemical properties of the Pc^tFe -oxo dimer, suggest that this compound is an Fe(2+) derivative.