Prediction of Aqueous Reduction Potentials of X • , ChH • , and XO • Radicals with X = Halogen and Ch = Chalcogen.

The aqueous electron affinity and aqueous reduction potentials for F • , Cl • , Br • , I • , OH • , SH • , SeH • , TeH • , ClO • , BrO • , and IO • were calculated using electronic structure methods for explicit cluster models coupled with a self-consistent reaction field (SMD) to treat the aqueous solvent. Calculations were conducted using MP2 and correlated molecular orbital theory up to the CCSD(T)-F12b level for water tetramer clusters and MP2 for octamer cluster. Inclusion of explicit waters was found to be important for accurately predicting the redox potentials in a number of cases. The calculated reduction potentials for X • and ChH • were predicted to within ∼0.1 V of the reported literature values. Fluorine is anomalous due to abstraction of a hydrogen from one of the surrounding water molecules to form a hydroxyl radical and hydrogen fluoride, so its redox potential was calculated using only an implicit model. Larger deviations from experiment were predicted for ClO • and BrO • . These deviations are due to the free energy of solvation of the anion being too negative, as found in the p K a calculations, and that for the neutral being too positive with the current approach.