Spectrophotometric investigations of binary and ternary complexes of Cd(II), methylthiourea and halide ions in aqueous solution

Abstract

The results of spectrophotometric investigations of mixed-complex formation equilibria of Cd(II), methylthiourea (MeTU) and halide ions (Cl −, Br − and I −) in aqueous solution have been reported. The formation of binary and ternary complexes has been found. The values of the equilibrium constants (log units) for the reaction MA 2+MB 2⇌2MAB, are 1.03±0.10, 1.17±0.12 and 1.34±0.08 for [CdMeTUCl] +, [CdMeTUBr] + and [CdMeTUI] +, respectively. It was found that the stability of ternary complexes depends on the values of the normal redox potential of halide ions.