A. Calusaru et al., CATALYTIC POLAROGRAPHIC WAVES OF NICKEL AND HYDROGEN-IONS IN THE NICKEL-2-MERCAPTOBENZOTHIAZOLE SYSTEM - HIGH 2-MERCAPTOBENZOTHIAZOLE CONCENTRATION, Revue Roumaine de Chimie, 40(11-12), 1995, pp. 1125-1133
At higher 2-mercaptobenzothiazole (MBT) concentration (over 1x10(-3) M
) in the presence of Ni2+ ions a hydrogen catalytic wave is formed at
E(H)(1/2)- -1.48 V by a complex adsorbed on the mercury cathode surfac
e. Around -1.55 V the catalytic current decreases sharply owing to the
desorption of active complex, that loses its catalytic activity when
it is in the bulb of solution only. The polarographic catalysis in the
system Ni-MBT was explained as mediated by a zero charge complex of n
ickel, formed after electrolytic discharge. This complex is protonated
at the N-atom of the heterocycle and the deprotonation occurs by the
charge transfer from Ni(O) to the protons. The catalytic waves height
increases with the increase of both MBT and NH3 concentrations. This b
ehaviour is a proof that in the structure of the Ni-MBT complex is bou
nd also NH3 as ligand.