Hydration, acidity and metal complexing of polysulfide species: A first principles molecular dynamics study

We report a first principles molecular dynamics study on hydration and acidity of polysulfide species. Hydration structures of (poly)sulfides species are pictured by analyzing the trajectories. With the vertical energy gap technique, our calculations reproduce the acidity constants of H2S and predict chain length independent acidity for polysulfanes: pKa1s are about 7.0 and pKa2s are around 9.0. This indicates H2Sn, HSn− and Sn2− can all be dominant under common pH. Furthermore, our simulations show that stable Au+–HSn− complexes can form in solutions, which implies that polysulfides can perform as metal complexing agents in hydrothermal processes.