Mechanism of Electrodeposition from Aqueous Solutions of Square Planar Complexes

Abstract

Cathode current efficiencies and/or cathode potentials have been measured for a variety of spin‐paired square planar complexes of Pt(II), Pd(II), and Au (III) in aqueous solutions. It was found that the tendency toward electro‐ deposition depends on the bond strengths of the particular ligands about the central metal ion, and that the over‐all charge of the complex influences current efficiency in the expected direction, i.e., complexes with more negative over‐all charges tend to deposit at lower efficiencies even though thermody‐namically less stable. The mechanism of deposition has been shown not to involve dissociation; rather, experimental data show that deposition proceeds from the undissociated complex as a whole.