Electrochemical and Computational Chemistry Study of Mn(β-diketonato)₃ complexes

Highlights: • Cyclic voltammetry of Mn(RCOCHCOR′)₃ series. • Aromatic rings (R or R′) in Mn(RCOCHCOR′)₃ stabilize the reduced/oxidized species. • Mean of peak oxidation- and reduction potential relates to electronic parameters. • Mean of peak oxidation- and reduction potential relates to DFT calculated energies. - Abstract: Nine different Mn(β-diketonato)₃ complexes, with β-diketonato = dipivaloylmethanato, acetylacetonato, benzoylacetonato, dibenzoylmethanato, trifluoroacetylacetonato, trifluorothenoylacetonato, trifluorofuroylacetonato, trifluorobenzoylacetonato and hexafluoroacetylacetonato, were synthesized. The effect of the various substituents on the β-diketonato backbone of these complexes, on the ease of oxidation and reduction of the central metal in the nine different Mn(β-diketonato)₃ complexes, was studied by means of electrochemistry. It was found that, when adding aromatic substituents to the backbone of the β-diketonato ligands of the complexes, the reduced/oxidized species were stabilized. It was also found that, when adding more electron withdrawing groups to the backbone of the β-diketonato ligands of the complexes, that Mn(β-diketonato)₃ complex was more easily reduced at a higher potential. Good linear relationships and trends were obtained between the mean value of peak oxidation and reduction potential of the Mn^III/Mn^II redox couple, and various electronic parameters and DFT calculated energies