Meso-dichlorophenyl substituted Co(III) corrole: A selective electrocatalyst for the two-electron reduction of dioxygen in acid media, X-ray crystal structure analysis and electrochemistry

摘要

A cobalt(III) corrole, represented as (Cl-2 Ph)(3) CorCo(PPh3), where (Cl2Ph)(3) Cor is the trianion of 5,10,15-tri(2,4-dichlorophenyl) corrole, was synthesized and characterized as to its electrochemical and spectroelectrochemical properties. Single-crystal structure analysis showed the corrole to be monoclinic and have a space group P21/c with a = 13.441(3), b = 28.058(6), c = 27.584(6) angstrom, alpha = 90, beta = 92.75(3), gamma = 90 degrees, M-r = 1144.38, V = 1039.1(4)angstrom(3), Z = 8, D-c = 1.463 mg/cm(3), mu= 0.816, F(000) = 4644, R-int = 0.0447, R(I > 4 sigma(I)) = 0.0769, wR(I > 4 sigma(I)) = 0.2104, R(all data) = 0.1214 and wR(all data) = 0.2705. The compound was also examined as a catalyst for the electroreduction of dioxygen when coated on an edge-plane pyrolytic graphite electrode in 1.0 M HClO4. Cyclic voltammetry and linear sweep voltammetry with a rotating disk electrode (RDE) or a rotating ring disk electrode (RRDE) were utilized to evaluate the catalytic activity of the corrole and elucidate the products of reduction, H2O or H2O2. Analysis of the data shows exclusively a two-electron transfer process to give 100% H2O2 as the product and no H2O was detectable.