Asymmetric electrode kinetics induced by concurrent metal-ligand bond dissociation

• Published in: Electrochimica acta 1993-05, Vol.38 (7), p.927-934
• Main Authors: Carlin, Richard T., Sullivan, Thom, Sherman, John W., Aspinwall, Craig A.
• Format: Article
• Language: English
• Subjects: carbon monoxide; Chemistry; copper; Electrochemistry; Exact sciences and technology; General and physical chemistry; High temperature electrochemistry (including molten salts); kinetics; microelectrodes; molten salts
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/0013-4686(93)87011-2

The electrochemistry of the Cu(II)/Cu(I) couple under nitrogen and carbon monoxide has been investigated in the ambient-temperature molten salt AlCl 3:MEICl (MEICl = 1-methyl-3-ethyl-imidazolium chloride) at a 250 μm tungsten disk electrode. Under nitrogen, the couple exhibits reversible electrode kinetics; however, under carbon monoxide, a Cu(I)CO complex is formed and the Cu(II)/Cu(I) couple displays asymmetric, quasi-reversible electrode kinetics. Pulse voltammetric data were fit with a nonlinear least-squares fitting program to give an apparent standard rate constant ( k 0 a) of 1.5 × 10 −3 cm s −1 and an anodic transfer coefficient (β) of 0.12–0.17 for the oxidation of the Cu(I)CO complex. The change from reversible to quasi-reversible electrode kinetics is attributed to the concurrent dissociation of the Cu(I)CO bond during the electron transfer process.