Ion-pair Formation of Some Substitution-inert Complexes and Sulfate Ions. Determination of Association Constants Using Polarographic Diffusion Current

Abstract

Abstract The polarographic diffusion current of some tervalent substitution-inert complex cations decreases by the addition of sulfate. From the change in diffusion current the association constants of substitution-inert complex and sulfate ions are obtained at ionic strength 0.1 (NaClO4) and 25°C. The values are 69±8, 58±8 and 4×10 for [Co(NH3)6]3+–SO42−, [Cr(NH3)6]3+–SO42− and [Cr(H2O)6]3+–SO42 respectively. The formation of [Co(NH3)6]3+–HSO4− is negligibly small compared with that of [Co(NH3)6]3+–SO42−.