Understanding and controlling aqueous
speciation of metal oxides
are key for the discovery and development of novel materials, and
challenge both experimental and computational approaches. Here we
present a computational method, called POMSimulator, which is able
to predict speciation phase diagrams (Conc. vs pH) for multispecies
chemical equilibria in solution, and which we apply to molybdenum
and tungsten isopolyoxoanions (IPAs). Starting from the MO4 monomers, and considering dimers, trimers, and larger species, the
chemical reaction networks involved in the formation of [H32Mo36O128]8– and [W12O42]12– are sampled in an automatic
manner. This information is used for setting up ∼105 speciation models, and from there, we generate the speciation phase
diagrams, which show an insightful picture of the behavior of IPAs
in aqueous solution. Furthermore, we predict the values of 107 formation
constants for a diversity of molybdenum and tungsten molecular oxides.
Among these species, we could include several pentagonal-shaped species
and very reactive tungsten intermediates as well. Last but not least,
the calibration employed for correcting the density functional theory
(DFT) Gibbs energies is remarkably similar for both metals, which
suggests that a general rule might exist for correcting computed free
energies for other metals.