Polarographic study on nickel (II) complex with 2-mercaptoethanol

In the presence of 2-mercaptoethanol (2ME), the diffusion limited nickel wave in ammoniac buffer solutions splits in two kinetically controlled waves due to the formation of a Ni-2ME complex in chemical equilibrium with the Ni-amminic complexes. The composition of this complex has been determined exclusively from the polarographic data no catalytic phenomenon being evidenced. The complex contains as ligands two 2ME, one NH3 and one H2O molecule: Ni(C2H6OS)(2)(NH3)(H2O)(2+). The following chemical reaction: Ni(C2H6OS)(2)(NH3)(H2O)(2+) + NH3 +3 H2O reversible arrow Ni(NH3)(2)(H2O)(4)(2+) + 2 C2H6OS is superimposed on the electrochemical one, causing the kinetic nature of the limiting currents. A similar complex is produced in the Co-2ME system, where the catalytic cobalt prewave is produced in addition.