Theoretical study of the solvation of HgCl2, HgClOH, Hg(OH)2 and HgCl3−: a density functional theory cluster approach

Ludovic Castro (1) , A. Dommergue (2) , A. Renard (2) , C. Ferrari (2) , A. Ramírez-Solís (3) , Laurent Maron (1)

1 LPCNO - Laboratoire de physique et chimie des nano-objets
2 CHANG - CHANG
3 Departamento de Fisica

The determination of the solvation shell of Hg(II)-containing molecules and especially the interaction between Hg(II) and water molecules is the first requirement to understand the transmembrane passage of Hg into the cell. We report a systematic DFT study by stepwise solvation of HgCl2 including up to 24 water molecules. In order to include pH and salinity effects, the solvation patterns of HgClOH, Hg(OH)2 and HgCl3− were also studied using 24 water molecules. In all cases the hydrogen bond network is crucial to allow orbital-driven interactions between Hg(II) and the water molecules. DFT Born-Oppenheimer molecular dynamics simulations starting from the stable HgCl2-(H2O)24 structure revealed that an HgCl2-(H2O)3 trigonal bipyramid effective solute appears and then the remaining 21 water molecules build a complete first solvation shell, in the form of a water-clathrate. In the HgCl2, HgClOH, Hg(OH)2-(H2O)24 optimized structures Hg also directly interacts with 3 water molecules from an orbital point of view (three Hg-O donor-acceptor type bonds). All the other interactions are through hydrogen bonding. The cluster-derived solvation energies of HgCl2, HgClOH and Hg(OH)2 are estimated to be −34.4, −40.1 and −47.2 kcal mol−1, respectively.

Domains: Glaciology

Ludovic Castro, A. Dommergue, A. Renard, C. Ferrari, A. Ramírez-Solís, et al.. Theoretical study of the solvation of HgCl2, HgClOH, Hg(OH)2 and HgCl3−: a density functional theory cluster approach. Physical Chemistry Chemical Physics, 2011, 13 (37), pp.16772-16779. ⟨10.1039/C1CP22154J⟩. ⟨insu-00646729⟩