Molecular structures of protonated and mercurated derivatives of thimerosal

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