Theoretical prediction for redox potentials of oxygen-centered organic anions in aprotic solvents.

It is well known that the feasibility of electron transfer reactions and the thermodynamic relationship between radicals and anions are highly dependent on the standard redox potentials. However, due to experimental limitations on the measurement of irreversible redox reactions, it is often difficult or even impossible to obtain reliable oxidation or reduction potential data. In this study, we assessed the performance of different theoretical methods and solvation models for predicting standard oxidation potentials ( E ox o ) of 33 representative anions including alcoholate, phenolate, and carboxylate anions in aprotic polar solvents. The density functional theory (DFT) M06-2X method and the composite procedure CBS-QB3 both achieved ideal precision for predicting adiabatic ionization potentials (IPs) in the gas phase, with a mean absolute deviation (MAD) value of 0.06 eV and 0.08 eV, respectively. As for solvation contributions, the SMD (solvation model density) model performed better than the latest uESE (Universal Easy Solvation Energy Evaluation) model for this kind of radical/anion couple. We suggest the optimal combination of M06-2X/ma-TZVP for IPs, and the SMD solvation model at M05-2X/6-31G(d) level is suitable for predicting E ox o , with an average error of 0.08 V. This assessment provides an alternative and reliable theoretical procedure to predict the oxidation potential and other related thermodynamic properties of O-centered organic anions. [ABSTRACT FROM AUTHOR]