Interactions of triiodide cluster ion with solvents

An equilibrium molecular dynamics model is developed to investigate the interactions of triiodide cluster ion with solvents. The internal dynamics of the triiodide ion is described by a valence bond model which responds to the field of the classical solvent molecules. The solvent molecules were described by standard classical models with rigid molecules, fixed partial charges on atomic sites and site-site Lennard-Jones interactions. One finds the solvent effects on the I-3(-) are unusually strong as it is a very polarizable species. Protic solvents such as water, ethanol, and methanol that can form hydrogen bonds to lead to the I-3(-) geometry with two unequal bonds and an asymmetric distribution of charges. But for the solvents such as xenon, tetrahydrofuran, methyltetrahydrofuran, and acetonitrile, the I-3(-) only illustrates a geometry with two equal bonds. We find that structure changing is induced by local electrostatic attraction between solvent molecules.