Modeling platinum group metal complexes in aqueous solution.

We construct force fields suited for the study of three platinum group metals (PGM) as chloranions in aqueous solution from quantum chemical computations and report experimental data. Density functional theory (DFT) using the local density approximation (LDA), as well as extended basis sets that incorporate relativistic corrections for the transition metal atoms, has been used to obtain equilibrium geometries, harmonic vibrational frequencies, and atomic charges for the complexes. We found that DFT calculations of [PtCl6]2-·3H2O, [PdCl4]2-·2H2O, and [RhCl6]3-·3H2O water clusters compared well with molecular mechanics (MM) calculations using the specific force field developed here. The force field performed equally well in condensed phase simulations. A 500 ps molecular dynamics (MD) simulation of [PtCl6]2- in water was used to study the structure of the solvation shell around the anion. The resulting data were compared to an experimental radial distribution function derived from X-ray diffraction experime...