Characterization of structure and dynamics of an aqueous scandium(III) ion by an extended ab initio QM/MM molecular dynamics simulation

Dalton Trans. 2012 Oct 14;41(38):11889-97. doi: 10.1039/c2dt31117h. Epub 2012 Aug 22.

Abstract

Hydration structure and dynamics of an aqueous Sc(III) solution were characterized by means of an extended ab initio quantum mechanical/molecular dynamical (QM/MM) molecular dynamics simulation at Hartree-Fock level. A monocapped trigonal prismatic structure composed of seven water molecules surrounding scandium(III) ion was proposed by the QM/MM simulation including the quantum mechanical effects for the first and second hydration shells. The mean Sc(III)-O bond length of 2.14 Å was identified for six prism water molecules with one capping water located at around 2.26 Å, reproducing well the X-ray diffraction data. The Sc(III)-O stretching frequency of 432 cm(-1) corresponding to a force constant of 130 N m(-1), evaluated from the enlarged QM/MM simulation, is in good agreement with the experimentally determined value of 430 cm(-1) (128 N m(-1)). Various water exchange processes in the second hydration shell of the hydrated Sc(III) ion predict a mean ligand residence time of 7.3 ps.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Ions / chemistry
  • Ligands
  • Molecular Dynamics Simulation*
  • Quantum Theory*
  • Scandium / chemistry*
  • Water / chemistry

Substances

  • Ions
  • Ligands
  • Water
  • Scandium