The reactions of Nickel(II) with 1,2-Ethanedithiol

Ethanedithiol reacts with nickel(II) under alkaline conditions to give the extremely stable complexes Ni(2)es(2)(-) and Nies(2)(-). The formation constants for these complexes are about 2 X 10(+47) and 4 X 10(+25), respectively, at 30 degrees and at an ionic strength of 0.1. A comparison of the spectra of these complexes with those of the analogous 2,3-dimercapto-1-propanol (DMP) complexes of nickel(II) shows that in these latter complexes coordination takes place only through the sulfur atoms. Relative activities of DMP and ethanedithiol at a given concentration in solution have been determined, and these are shown to have quite a large effect on the relative values of the molar formation constants of Ni(DMP)(2)(-) and Niesi(2)(-). The combination of ligand activity effects and complex ion solvation energies obscures conclusions drawn from the relative values of molar formation constants regarding the nature of either bonding or steric factors in a series of complexes.