Tetrahedral structure of aluminate ion, Al(OH)4-
In this run, the deprotonated hexa-hydrate complex (we removed the protons from this hexa-hydrate complex so it became Al(H2O)2(OH)4-) quickly became unstable after 0.1 ps and readily evolved towards the equilibrium tetrahedral structure of aluminate ion, Al(OH)4- .
The two remaining water molecules were forced out of the first solvation shell and formed the hydrogen bonds to the hydroxyl groups coordinated to the aluminum ion (blue).
Ab initio molecular dynamics of aluminum solvation
by Mark I. Lubin and John H. Weare, UCSD