Raman spectroscopic study of the complexation of the methylmercury(II) cation, CH 3Hg +, by ligands containing oxygen and sulphur

Abstract

The vibrational Raman spectra of methylmercury(II) nitrate in aqueous solution and of its complexes with dimethyl sulphide and dimethyl sulphoxide (DMSO) are presented. A quantitative determination of the ν(HgO) and ν(HgS) stretchin band intensities using the ν(HgC) stretching band as an internal standard for the CH 3HgOH 2 + and CH 3HgS(CH 3) 2 + species in aqueous solution has shown that the methylmercury(II) dimethyl sulphide complex cation is only partially dissociated in 0.01 M aqueous solution, with α = 0.40. An estimate of a factor of 2600 for the preference for sulphur coordination to oxygen coordination under these conditions has been made. The dimethyl sulphoxide complex of the methylmercury(II) cation has a mercury-oxygen bond and not mercury-sulphur as expected.