Computer modelling of hydration structure of highly charged ions and cationic hydrolysis effects

We made an attempt to clarify effects of the presence of high valence cations on the structure and dynamics of water molecules in aqueous solution. It is shown that the strong cation–water electrostatic interaction leads to formation of very stable structures constituted preferably by six water molecules octahedrally arranged around cation. The increase of cation charge and/or decrease of ionic size results in increase of OH bond length for molecules in cation hydration shell. Further increase of ion–water electrostatic interaction causes the loss of some protons from hydration shell, which is interpreted as hydrolysis effect. As a result of charge redistribution between the hydrolysis products the structure of cation hydration shell is essentially modified. New characteristic high frequencies are observed in spectral density of the hindered translational motion for highly charged cation and oxygens in hydration shell.