ELECTROCHEMICAL-BEHAVIOR OF ISOMERS OF A TETRAAZAMACROCYCLIC NI(II) COMPLEX IN SOLUTIONS SATURATED WITH ARGON, CO AND CO2

Isomers of [Ni(CRH)](2+) have been isolated and studied by d.c. and a. c. voltammetry on mercury electrodes in aqueous solution. The configur ational isomers of [Ni(CRH)](2+) were found to differ in their stabili ty in the solution and the isomerization process was monitored voltamm etrically. The adsorptivity of the isomer A on mercury electrodes was found to be stronger than that of the isomer B, while no differences w ere seen for the adsorbed Ni(I) complexes. The solution resident [Ni(C RH)](+) complexes are more labile than the corresponding Ni(II) compou nds, hence upon reduction the isomer B undergoes fast transformation i nto the more stable isomer A. The electroreduction of [Ni(CRH)](2+) in the presence of CO and CO2 is described and the influence of the isom eric form used in the processes is discussed.