Ionic solvation. Part 4.—Copper(I) solvation. Disproportionation and halide-complex formation in propylene carbonate

Abstract

Potentiometric measurements have been obtained in order to examine the thermodynamic stability of copper(I) species and to study halide-complex formation in propylene carbonate in a 0.1 mol dm^–3 tetraethylammonium perchlorate medium at 25 °C. A value of 10^–3.44 dm³ has been found for the concentration constant, K_D, of the disproportionation reaction: 2Cu⁺⇌Cu²+Cu. In the halide systems two mononuclear complexes CuX and CuX₂^– are formed. The solubility products of CuX, pK_sp, are 16.0, 15.8 and 17.9 and overall formation constants of CuX₂^–, log β₂ are 19.9, 17.9 and 17.2 for ×= Cl^–, Br^– and I^–, respectively. The results are discussed in terms of solvation of the various complexes.