A Systematic approach to the simulation of the voltammetric reduction of [α-SiW 12O 40] 4− in buffered aqueous electrolyte media and acetonitrile

• Published in: Journal of electroanalytical chemistry (Lausanne, Switzerland) Vol. 591; no. 1; pp. 7 - 18
• Main Authors: Guo, Si-Xuan, Mariotti, Andrew W.A., Schlipf, Christine, Bond, Alan M., Wedd, Anthony G.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.06.2006; Elsevier Science
• Subjects: Chemistry; Electrochemistry; Exact sciences and technology; General and physical chemistry; Keggin anions; Kinetics and mechanism of reactions; pH dependence; Reaction scheme; Simulation; Voltammetry; Keggin anions; pH dependence; Voltammetry; Reaction scheme; Simulation; Solvent effect; Heteropolysalt; Theoretical study; Electron transfer; Experimental study; Chemical reduction; Cyclic voltammetry; Kinetic model; Organic solvent; Thermodynamic model; Medium effect; Reaction mechanism; pH; Kinetic parameter; Aqueous solution; Rate constant; Electrochemical reaction
• ISSN: 1572-6657; 1873-2569
• DOI: 10.1016/j.jelechem.2006.03.031

Voltammetric studies of the reduction of [α-SiW 12O 40] 4− have been reported previously in highly acidic media. In this study, the systematic use of rotating disk and cyclic voltammetry over the less acidic pH range 2.1–6.8 provided access to a significant number of parameters that could be determined experimentally and then incorporated into a realistic simulation of the complex reaction scheme needed to account for the pH dependence. The simulated voltammograms reproduce many of the key features detected experimentally and imply that the general scheme for an overall four-electron redox reaction is [Display omitted] with different pathways being dominant at different pH values. Simulations of the simpler voltammetry detected in aprotic acetonitrile media (0.1 M Bu 4NPF 6) for reduction of [α-SiW 12O 40] 4− and [α-PW 12O 40] 3− also are presented and enable the solvent dependence of reversible potential data to be compared. The reversible potential in water for the [α-SiW 12O 40] 6−/7− process is a volt less negative than that for the analogous process in aprotic media. Reasons for this very large difference are considered in terms of solvent and electrolyte properties.