Performance of Functionals and Basis Sets in Calculating Redox Potentials of Nitrile Alkenes and Aromatic Molecules using Density Functional Theory

To calculate redox potentials of small organic compounds in acetonitrile, the performance of different functionals and basis sets has been evaluated using density functional theory with the polarized continuum model. Several Pople and Ahlrichs basis sets and functionals at distinct levels of the Jacob's Ladder have been studied: PW91, PBE, M06-L, B3LYP, PBE0, M06-2X, CAM-B3LYP, omega B97X-D3, RI-B2PLYP. It is shown that redox studies should not be done considering oxidation and reduction potentials jointly but analyzing them separately. Functional M06-2X has a more consistent and uniform response both in reductions and oxidations, having an adequate balance between accuracy and computational effort. Linear dependence between the basis set size and the accuracy of the calculated redox potential has not been found.