The Hydration Structure of Sn(II): An ab initio Quantum Mechanical Charge Field Molecular Dynamics Study

摘要

The structural properties of the hydrated Sn2+ ion have been investigated using ab initio quantum mechanical charge field molecular dynamics (QMCF MD) simulations at double-xi HF quantum mechanical level. The results from the work significantly extend previous study using QM/MM MD simulation and are in good agreement with X-Ray and EXAFS diffraction experiments. The data indicate a set of characteristics for the first hydration shell uncommon among metal ions. Although frequent ligand exchange prevents the formation of a well defined structure, more detailed analyses reveal an asymmetric distribution of ligands around Sn(II). An average of eight water molecules coordinate with the Sn2+ ion and are distributed at proximal and distal positions that are distinguishable from the second hydration shell and manifest dissimilar degrees of lability.