Synthesis and redox characteristics of iron complexes with triphenylsubstituted corrols in the presence of argon and oxygen
摘要:
para-Substituted iron meso-triphenylcorrole derivatives [Fe(ms-p-R-Ph)(3)Cor] containing electron- donating (R = OMD mu) and electron-drawing (R = NO2) groups in phenyl rings are synthesized and characterized by H-1 NMR, electronic absorption spectroscopy, and mass spectrometry. The effect of the nature of functional groups within iron complexes on the redox processes involving these complexes in water-alkaline solutions is analyzed. Electronic transitions in the ligand (E (red/ox) = 0.820-0.850 V) and the metal (E (red/ox) =-0.005 to-0.190 and-0.790 to-0.870 V for the Fe4+ a dagger" Fe3+ and Fe3+ a dagger" Fe2+ transitions, respectively) were found in the cyclic voltammograms. Iron in the synthesized complexes I-IV under the conditions under study exists in the +4 oxidation state. The activity of iron complexes in electroreduction of molecular oxygen significantly depends on the nature of a substituent, increases in the series: Fe(ms-p-NO2Ph)(3)Cor (II) < Fe(ms-p-MeOPh)(3)Cor (I) < Fe(beta-Br)(8)(ms-Ph)(3)Cor (IV) < Fe(ms-Ph)(3)Cor (II) and is caused by the fact that low-energy redox electron transitions occur in the molecules. The electrocatalytic activity of iron corroles is much higher than that of metal porphyrins with a similar structure.