An investigation of the equilibrium of mercury(II) thiocyanate complexes in DMF solutions via Raman spectra and factor analysis

Abstract

Using Raman spectra and factor analysis, the equilibria of mercury(II) thiocyanate complexes in N,N-dimethylformamide solutions with SCN^-/Hg(II) molar ratios ranging from 0.6 to 4.0 have been investigated. The spectra were recorded in the region of the ν(Hg–S) and ν(C–N) vibrations. In the former, the Raman bands belonging to four complex species, Hg(SCN)⁺, Hg(SCN)₂, Hg(SCN)₃^- and Hg(SCN)₄^2-, have been extracted by applying principal component analysis to the spectra. Three components were found in the ν(C–N) region. The concentration of the identified complex species in all investigated solutions has been determined by a target factor analysis method and the disproportionation constants of Hg(SCN)⁺ and Hg(SCN)₃^- have been estimated to be 0.18 and 0.21, respectively.