Complexation of Sc(III), Ga(III), In(III) and Ln(III) with Eriochrome Red B

Cyclic linear-sweep voltammetry was used to study the complexation of Sc(III), Ga(III), In( III) and Ln(III) with eriochrome red B (ERB). It was established that all metal ions investigated form complex compounds with azodye having a mole ratio, M( III): ERB = 1: 2. The hydroxo forms of M( III) ions, which take part in interaction with ERB, were determined by the Nazarenko method. The stability constants for the formation of these chelates are nearly the same. It was shown that the reduction of the ligand in the complex does not only depend on the peculiarities of complexation, but the processes occurring in preelectrode layer also influence it.