Redox potentials of ligands and complexes - a DFT approach

A review of the limited literature concerned with theoretical ways to predict experimentally measured redox potentials of ligands and complexes is presented. Electrochemical and related DFT studies involving series of para-substituted nitrobenzenes and -diketone bidentate ligands are discussed. New studies involving ferrocenes and bimetallic complexes (containing both rhodium and iron) are additionally reported. Correlations of redox potentials with calculated descriptors; electron affinity (EA), group electronegativity ( R ), electrophilicity index (), LUMO energy (E LUMO ) and HOMO energy (E HOMO ) – obtained from calculated electronic energies of neutral, anionic and cationic molecules, are compared. Observed E 0’ ,E pa or Epc gave excellent correlations in the linear relationships between Epc and ELUMO (R 2 > 0.99), and Epa and EHOMO (R 2 > 0.92). Close correlation with the