Structure and properties of (Ac)Fe(III)-5,15-diphenyl-3,7,13,17-tetramethyl-2,8,12,18-tetrabutylporphyrin in the reaction with organic peroxides in benzene: The effect of imidazole on reaction kinetics

The kinetics of the reaction between (Ac)Fe(III)-5,15-diphenyl-3,7,13,17-tetramethyl-2,8,12,18-tetrabutylporphyrin and dicumene peroxide in benzene at 295 K was studied with the purpose of further studying the effect of the conformational and electronic factors of nonplanar metalloporphyrinates on redox properties using a combination of computational and spectrophotometric methods. The molecular structures of reagents and intermediates of the studied reaction were optimized by the PM3 quantum-chemical method. The obtained characteristics were analyzed, and the distortion of a macrocycle was established to considerably increase in the reaction of iron(III) porphyrinate with peroxides. The intermediate molecule was found to be sterically hindered and extremely unstable. The kinetic characteristics of the reaction were obtained spectrophotometrically. The nature of a metal atom and the distortion of a macrocycle were established to have some effect on the process rate. The introduction of imidazole into a reaction mixture and the variation of concentration of a base were shown to produce some changes in the composition of reagents and the kinetics of the process. A good agreement between experimental and calculated data was observed.