FeI Intermediates in N2O2 Schiff Base Complexes: Effect of Electronic Character of the Ligand and of the Proton Donor on the Reactivity with Carbon Dioxide

The characterization of competent intermediates metal complexes, involved in catalytic transformations for the activation small molecules, is an important target mechanistic comprehension and catalyst design. Iron complexes deserve particular attention, due to rich chemistry iron that allows their application both oxidation reduction processes. In particular, with tetradentate Schiff base ligands show possibility electrochemically generate FeI intermediates, capable reacting carbon dioxide. this work, we investigate electronic spectroscopic features five Fe(LN2O2) evaluate electrocatalytic CO2 presence phenol (PhOH) or trifluoroethanol (TFE) as proton donors. main findings include: (i) a correlation potentials FeII/I couples character LN2O2 ligand energy metal-to-ligand charge transfer absorption species (determined by spectroelectrochemistry, SEC-UV/Vis); (ii) reactivity CO2, proven cyclic voltammetry SEC-UV/Vis; (iii) identification Fe(salen) homogeneous electrocatalyst CO, donors (an overpotential 0.91 V, rate constant estimated at 5 × 104 s?1, turnover number 4); (iv) sudden, ligand-assisted decomposition routes bearing ketylacetoneimine pendant, likely associated protonation under cathodic conditions ligands.