Quasi-chemical study of Be2+(aq) speciation

Be2+(aq) hydrolysis can to lead to the formation of multi-beryllium clusters, but the thermodynamics of this process has not been resolved theoretically. We study the hydration state of an isolated Be2+ ion using both the quasi-chemical theory of solutions and ab initio molecular dynamics. These studies confirm that Be2+(aq) is tetra-hydrated. The quasi-chemical approach is then applied to then the deprotonation of Be(H2O)42+ to give BeOH(H2O)3+. The calculated pKa of 3.8 is in good agreement with the experimentally suggested value around 3.5. The calculated energetics for the formation of [Be·OH·Be]3+ are then obtained in fair agreement with experiments.