Revisiting the hydration of Pb(II): a QMCF MD approach.

A quantum mechanical charge field (QMCF) molecular dynamics (MD) study of Pb(II) in an aqueous medium was carried out in order to gain insight into its solvation behavior, for both structural and dynamic aspects. Applying the advanced methodology and different basis sets, some new aspects concerning the solvation of Pb(II) have been revealed. One of the most interesting outcomes of the current simulation is the variation of first shell coordination number from 7 to 9 in the Pb(H2O)n(2+) complex with Pb(H2O)8(2+) as a major species. Moreover, a far more dynamic and labile hydration shell was found compared to previous QM/MM MD simulation with only the first hydration shell treated by quantum mechanics, which reported a very rigid first hydration shell with a fixed coordination number of 9. The current simulation results are in much better agreement with the properties reported from the recent thermodynamic studies than the previous QM/MM MD study.