A Novel Reactivity Descriptor for mn4 Molecular Catalysts for the Oxidation of 2-Mercaptoethanol and of Thioglycolic Acid: The Electrochemical Hardness

This manuscript describes a novel reactivity descriptor for Fe phthalocyanines molecular catalysts confined on the surface of OPG electrodes. The descriptor ΔE°’cat. is the gap in potential between the E°Fe(III)/(II) and E°Fe(II)/(I) redox processes for each FeN4 catalyst. This descriptor, labeled as the electrochemical hardness ΔE°’<inf>cat</inf>. Was examined using FeN4 macrocyclic complexes for the electrooxidation of 2-mercaptoethanol (2-ME) and thioglycolic acid TGA. Our findings reveal that the reactivity as log log(j/Γ)E, plotted versus E°Fe(III)/(II) or E°Fe(II)/(I) give two linear correlations. The activity log(j/Γ)<inf>E</inf> in both cases decreases with the redox potential of each FeN4 catalyst. In contrast log(j/Γ)<inf>E</inf>, or log (TOF)<inf>E</inf>, increase with ΔE°’<inf>cat..</inf> The Fe[sbnd]S binding energy ΔE°’<inf>cat.</inf> Correlates linearly with ΔE°’<inf>cat.</inf> so the softer the system the greater the binding energy and the lower the catalytic activity. © 2024