Journal of Electroanalytical Chemistry, Vol.587, No.2, 314-322, 2006
Electrochemical reduction of Rh(bpy)(3+)(3) at Hg/phosphate electrolyte interface
The electrochemical reduction of tris(2,2'-bipyridine)rhodium(IIl), Rh(bpy)(3)(3+), in phosphate buffer solutions was investigated by cyclic voltammetry, alternating current voltammetry, chronoamperometry and exhaustive electrolysis. The cyclic voltammograms exhibit a series of sharp peaks indicating surface confined processes. The major features of the electroreduction are strong adsorption of Rh(bpy)(3)(3+), participation of mercury in the electroreduction process and the simultaneous loss of bipyridine ligand. The complex forms condensed layer in a narrow potential region around -0.8 V vs. Ag/AgCl. The chernical bond between Rh(bpy)(3)(3+) and mercury is required for the formation of binuclear complex of rhodium(II), [Rh,bpy(3)(HO)Cl](3+), at the potentials about -0.9 V. At the potential of -1.1 V further reduction of [Rhbpy(3)(H2O)Cl](3+) leads to the concomitant oxidation of the mercury electrode, resulting in a mixed Rh(I)-Hg(II) complex and elemental rhodium deposited on the electrode. (c) 2005 Elsevier B.V. All rights reserved.
Keywords:tris(2,2 '-bipyridine)rhodium(III);cyclic voltammetry;mixed Hg-Rh complex;electroreduction;condensed layer formation