Die Komplexchemie des Methylquecksilber‐Kations

Abstract The stability constants of the methylmercury complexes CH 3 HgL 1−λ with a considerable number of ligands L λ− have been determined (Table 1). Like H + , the cation CH 3 Hg + reveals the coordination number 1 almost exclusively. Some ligands form also binuclear adducts (CH 3 Hg) 2 L 2−λ and sulfide even forms (CH 3 Hg) 3 S + . The coordination behaviours of CH 3 Hg + and H + however are very different concerning the selection of ligands, the former being a soft and the latter a hard acid in the sense of P EARSON . The entropy ΔS of the reaction: H + + L − → HL is more positive by about 14 c.u. than Δ S of the reaction: CH 3 HG + + L − → CH 3 HgL. The hydrogen ion in aqueous solution has a far greater order producing action on the solvent than CH 3 Hg + . Two dyes also have investigated, which may serve as indicators for CH 3 HG + and for the determination of pCH 3 Hg (= −logCH 3 Hg + ).