Solvent Extraction from Molten Salts. III [1, 2]. Formation of Anionic Mercury (II) Mixed‐Halide Complexes

In distribution experiments of mercury (II) halides between a polyphenyl eutectic mixture and molten LiNO 3 ‐ KNO 3 eutectic at 150°, various amounts of mixed potassium halide were added to the salt melt, in large excess over the mercury halide. From radiometric measurements of the overall distribution ratio D for mercury (II) species we calculated: the overall complex formation constants\documentclass{article}\pagestyle{empty}\begin{document}$ {\rm \alpha }_{{\rm ij}} = \frac{{\left[ {{\rm HgA}_{\rm i} {\rm B}_{\rm j} \left( {{\rm i} + {\rm j} - 2} \right)^ - } \right]}}{{\left[ {{\rm HgA}_{\rm 2} } \right]\left[ {{\rm A}^ - } \right]^{{\rm i} - 2} \left[ {{\rm B}^ - } \right]^{\rm j} }} $\end{document}and the “ligand mixing” constants\documentclass{article}\pagestyle{empty}\begin{document}$ {\rm X}_{{\rm ij}} = \frac{{\left[ {{\rm HgA}_{\rm i} {\rm B}_{\rm j} \left( {{\rm i} + {\rm j} - 2} \right)^ - } \right]^2 }}{{\left[ {{\rm HgA}_{{\rm i + 1}} {\rm B}_{{\rm j} - 1} \left( {{\rm i} + {\rm j} - 2} \right)^ - } \right]\left[ {{\rm HgA}_{{\rm i} - {\rm j}} {\rm B}_{{\rm j} + 1} \left( {{\rm i} + {\rm j} - 2} \right)^ - } \right]}} $\end{document}with A − and B − representing chloride‐bromide, chloride‐iodide or bromide‐iodide. The results show enhanced stability of Cl‐Br, but not of Cl‐I and Br‐I mixed complexes and point to the existence, in the molten salt phase, of only those species of mercury (II) which have a −2 charge (tetrahalide, trihalide‐mononitrate and dihalide‐dinitrate).