Structural and dynamical properties of Pd2+ in aqueous solution have been investigated by a combined quantum mechanical/molecular mechanical (QM/MM) molecular dynamics (MD) simulation at Hartree-Fock level. For the structural elucidation of the Pd2+ complex in aqueous solution several data sets such as radial and angular distribution functions (RDF/ADF) were employed. Dynamics have been characterized by the ligands' mean residence time (MRT) and ion-ligand stretching frequencies. For a final decision, whether besides the tightly bound four in-plane ligands additional axial ligands are present, an extension of the methodical accuracy beyond that of a one-shell QMM/MM MD simulation appears necessary. (c) 2006 Elsevier B.V. All rights reserved.