On the formation of inner-sphere solvation complexes in dilute acetonitrile solutions of the Hg(NO3)2 and Hg(TfO)2 salts: a Molecular Dynamics study

The solvation properties of dilute acetonitrile solutions of the Hg(NO3)2 and Hg(TfO)2 salts have been investigated by using Molecular Dynamics simulations. The Hg2+ ion in acetonitrile was found to coordinate both counterions and acetonitrile molecules in its first solvation sphere by forming inner-sphere complexes. However, different geometries of the Hg2+ solvation polyhedra are formed depending on the counterion: in the Hg(NO3)2 salt solution, Hg2+ forms a 8-fold cluster of acetonitrile and nitrate ligands with a square antiprism symmetry, while in the system containing the Hg(TfO)2 salts, the Hg2+ solvation shell is composed of eight ligands arranged in a C2 symmetry.