Solvent rearrangements during the transition from hydrophilic to hydrophobic solvation

Highlights: ► Ab inito molecular dynamics to study the early time dynamics following electron removal from aqueous iodide. ► Ultrafast formation of a 3-electron bond I0–OH2 complex (<100 fs). ► Oscillation frequency of complexed water reflects influence of nearby water molecules. -- Abstract: We present an ab initio Born–Oppenheimer molecular dynamics study of the early time solvent dynamics after electron abstraction from aqueous iodide. An initial response occurs within ∼75 fs, corresponding to a water molecule sharing almost one electron with the iodine. This is followed by the formation of a transient I0⋯OH2 complex within ∼500 fs. Further insight into the driving forces for this complex are obtained using an energy decomposition analysis and frequency calculations of small clusters. It is shown that the anisotropic solvation shell structure of iodide before electron abstraction is likely to be an important factor in the formation of the complex.