Structure and solvation of mercury(II) iodide and bromide in tetrahydrothiophene solution

Abstract

The structure of the solvated neutral Hgl₂ and HgBr₂ molecular complexes in tetrahydrothiophene (tht) solution has been studied by X-ray diffraction and vibrational spectroscopic methods. Pseudo-tetrahedral[Hgl₂(tht)₂]and [HgBr₂(tht)₂] species of approximately C_2V symmetry are formed in solution. The Hg–I bond length is 2.670(4)Å and the Hg–Br 2.535(6)Å. The IHgl angle was found to be 143(2)° at 25 °C and BrHgBr 132(2)° at 30 °C including estimated corrections for shrinkage effects. Raman and i.r. spectra of the solutions and the solids are consistent with molecular models derived from the diffraction data. A comparison with crystal structure data for [HgBr₂(tht)₂] and [HgCl₂(tht)₂] is made.