Ab initio molecular dynamics simulations of aluminum ion solvation in water clusters

The results of ab initio molecular dynamics simulations of the solvation of Al3+ and its hydrolyzation products in water clusters are reported. Al3+ ions in water clusters (6 less than or equal to n less than or equal to 16) form a stable hexa-hydrate Al(H2O)(6)(3+) complex in finite temperature simulations. The deprotonated Al(H2O)(2)(OH)(4)(-) complex evolves into a tetra-coordinated Al(OH)(4)(-) aluminate ion with two water molecules in the second cluster solvation shell forming hydrogen bonds to the hydroxyl groups consistent with the observed coordination in water solutions. At high temperature, protons in the first solvation shell of the Al3+(H2O)(14) cluster are very mobile transferring easily to the second cluster solvation shell and leading to the formation of transient (1ps) hydrolysis species.