Molecular structures of protonated and mercurated derivatives of thimerosal

Abstract

The carboxylate oxygen of thimerosal, [(Ar^CO₂)SHgEt]Na, is subject to facile electrophilic attack by H⁺ and [HgEt]⁺ to give (Ar^CO₂H)SHgEt and [(Ar^CO₂HgEt)SHgEt]₂, respectively. X-Ray diffraction demonstrates that (Ar^CO₂H)SHgEt exists as a hydrogen bonded dimer in the solid state whereas [(Ar^CO₂HgEt)SHgEt]₂ is tetranuclear, with the mercury centers being connected by bridging carboxylate groups. ¹H NMR spectroscopic studies indicate that the form of the ¹⁹⁹Hg satellites of the ethyl group of (Ar^CO₂H)SHgEt are dependent on the magnetic field, such that the inner pair of CH₂ and CH₃ satellites appear as a singlet at 400 MHz, as a consequence of ²J_Hg–H and ³J_Hg–H having opposite signs and the difference in chemical shifts of the central CH₂ and CH₃groups being equal to ½{|²J_Hg–H−³J_Hg–H|}.