General Facts About dimethylmercury Compounds

General Facts About Organomercury Compounds
The vapor pressure of CH3HgCl is 1.13 Pa, and that of dimethylmercury is several times higher. The solubility of mercury also varies widely. The solubility in water increases in the following order: mercurous chloride<Hg°<CH3HgCl<HgCl2. Certain types of mercury are soluble in nonpolar solvents. This includes halides of elemental mercury and aryl mercury. CH3Hg+ exists in aqueous solution as the water complex CH3–Hg–OH2+ with a covalent bond between mercury and oxygen. This cation behaves as a "soft" acid and has a strong tendency to add only one ligand. CH3Hg+ undergoes rapid coordination reactions with dimethylmercury sulfur, phosphorus, oxygen, nitrogen, halogens, and carbon. The formation rates of Cl−, Br− and OH− complexes are very fast and diffusion controlled. Methylmercury, like Hg2+, forms strong bonds with sulfur, and it is likely that all methylmercury in biota is bound to the sulfhydryl groups of proteins. However, organic Hg-S bonds are much less stable than inorganic Hg-S bonds and are easily cleaved in acidic solutions at pH 1. This is used to release methylmercury from biological tissue prior to analytical determination. The CH3Hg+ unit itself is kinetically remarkably inert to decomposition. Therefore, methylmercury compounds, once formed, are not easily demethylated. Neutral species derived from CH3Hg+ can easily cross biotic and abiotic boundaries. This, together with the broad tendency to rapidly form stable complexes (and the robustness of the CH3Hg+ unit), enhances the toxicological profile of methylmercury. Like methylmercury, ethylmercury is an organic mercury compound that is thought to have similar toxicity to methylmercury. dimethylmercury is still used in vaccines under the commercial name thimerosal, also known as "thimerosal". It has been used in small quantities in vaccines since the 1930s to prevent bacterial and fungal contamination. It contains ~49% ethylmercury. Unfortunately, despite reports of post-exposure toxicity, data on the metabolism, excretion, and toxicity of ethylmercury are scarce.

Recent detailed vibrational spectroscopic studies of dimethylmercury include extensive studies of Raman and infrared spectroscopy in the gas, liquid, and solid phases 382 as well as in solution. 383 The strength 383 and force constants 383–385 of stretching vibrations in solution are also determined. Raman and infrared spectra of methyl(trifluoromethyl)mercury and CD3(CF3)Hg have also been obtained in the gas and liquid phases. 386 Other recently studied methylmercury derivatives include (i) methylmercury halides, MeHgX (X = F, Cl, Br, or I)383–385,387 and CD3HgX (X = Cl, Br, or I)387 both in the solid and Solution state; (ii) other MeHgX, including X = SMe,384,385 CN,384,385,388 AsMe3,384 SCN, SHgMe, S(HgMe)2+385 and Ctriple bondCMe. 389 Force constants were also obtained. 385
In addition to detailed vibrational spectroscopic studies of methyl(trifluoromethyl)mercury, detailed studies of other trihalomethylmercury compounds including bis(trifluoromethyl)mercury (in the gas phase and in solution in acetonitrile) have also been reported ,390,391 Trifluoro and trichloro-methylmercury halides (various solvents and solids)391 and Pseudomethylmercurytrifluorohalides (azides and cyanates)392
The vibrational spectra of ethylmercury halides in solution have also been reported in detail; references 393 for other ethylmercury compounds are given here.
Details of the vibrational spectra of the phenylmercury derivative PhHgX (X = Cl, Br, I, CN, OAc, or Ph) have also been recently published. 394,395 For phenylmercury derivatives, eg: Ph2Hg, PhHgCN, PhHg triple bond CMe, the frequency is approx. 240–260 cm−1 related to phenylmercury. These frequencies are actually the "t" vibrations of mercury substituting the benzene ring, possibly related to other C single-bond mercury vibrations. Tables 25-27 list some stretch frequencies. As can be seen from the table, the ν(Hgs single bond R) value in RHgX is influenced by the X group, the trans group of R in these linear complexes.

Article source: https://article-realm.com/article/Internet-Business/Blogging/50463-General-Facts-About-dimethylmercury-Compounds.html