Complex formation in dimethyl sulphoxide. Part II. Mercuric iodide and potassium iodide

Abstract

The stepwise formation of the ions Hgl₂^– and Hgl₄^2– in solutions of mercuric and potassium iodides in dimethyl sulphoxide has been inferred from a study of the conductance and spectrophotometric properties of the solutions. At low concentrations (<10^–4M) the autoionisation process 2Hgl₂= Hgl⁺+ Hgl₃^– occurs in dimethyl sulphoxide. Raman spectrophotometric measurements are consistent with a linear structure for the Hgl₂ molecule and a tetrahedral structure for the Hgl₄^2– ion in this solvent. The heat of formation of the Hgl₄^2– ion from the Hgl₂ molecule and I^– ions in dimethyl sulphoxide was –10·5 kcal./mole Hgl₂.