Calculated Aqueous Reduction Potentials of Neutral and Anionic Halogen Diatomic Molecules

Area of Science:

• Computational Chemistry
• Physical Chemistry
• Quantum Chemistry

Background:

• Accurate calculation of hydration free energies, electron affinities, and reduction potentials is crucial for understanding halogen chemistry.
• Previous methods have shown success for radical species, but comprehensive data for diatomic halogens and their anions is lacking.

Purpose of the Study:

• To calculate gas and aqueous phase properties for diatomic halogens and interhalogens.
• To provide a reliable dataset for electron affinities and reduction potentials.
• To extend these calculations to systems lacking experimental data, such as iodine-containing species.

Main Methods:

• Utilized an established electronic structure approach for calculating free energy of hydration, electron affinity, and reduction potentials.
• Employed complete basis set extrapolation of coupled cluster with singles, doubles, and perturbative triples (CCSD(T)) results for gas phase electron affinities.
• Applied a hybrid solvation approach with explicit solvent molecules and implicit solvation models.

Main Results:

• Achieved excellent agreement (within 0.06 V) with experimental data for aqueous reduction potentials of diatomic neutrals and anions.
• Calculated a comprehensive set of reliable electron affinities for diatomic halogens.
• Predicted the dissociation of F2• into solvated F, HF, and OH•.

Conclusions:

• The developed computational approach provides accurate predictions for halogen and interhalogen redox properties.
• This work expands the available data for reduction potentials, particularly for iodine-containing species and interhalogen anions.
• The findings offer valuable insights into the reactivity and behavior of halogens in aqueous solutions.