Voltammetric oxidation of solution and solid phases of salts of [V(CO)6]- in aqueous (electrolyte) media
In the absence of water and oxygen the solution phase voltammetry of [V(CO)6]- in organic solvents exhibits an extremely well-defined, reversible, one-electron redox couple [V(CO)6]- ⇋ V(CO)6 + e-; ET1/2 = -0.35 V versus the ferrocenium/ferrocene (Fc+/Fc) couple, where ET1/2 is the reversible half-w...
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| Format: | Article |
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American Chemical Societyservice@acs.org
1998
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| Online Access: | http://psasir.upm.edu.my/id/eprint/116173/ |
| _version_ | 1848866940916858880 |
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| author | Bond, Alan M. Colton, Ray Mahon, Peter J. Snook, Graeme A. Tan, Wee T. |
| author_facet | Bond, Alan M. Colton, Ray Mahon, Peter J. Snook, Graeme A. Tan, Wee T. |
| author_sort | Bond, Alan M. |
| building | UPM Institutional Repository |
| collection | Online Access |
| description | In the absence of water and oxygen the solution phase voltammetry of [V(CO)6]- in organic solvents exhibits an extremely well-defined, reversible, one-electron redox couple [V(CO)6]- ⇋ V(CO)6 + e-; ET1/2 = -0.35 V versus the ferrocenium/ferrocene (Fc+/Fc) couple, where ET1/2 is the reversible half-wave potential. Addition of water or oxygen causes the response to become irreversible, but all components remain soluble. Simulations of the solution-phase voltammetry in acetone/water mixtures (no oxygen present) are consistent with the mechanism V(CO)6 + H2O → V(CO)5(H2O) + CO. The sodium diglyme stabilized [V(CO)6]- salt ([Na-(diglyme)2][V(CO)6]) is slightly soluble in water without decomposition. In contrast, solid V(CO)6 is insoluble in water, but reacts so slowly with it that solid state voltammetry of the [V(CO)6]0/- system is possible in aqueous media. Oxidation of [Na(diglyme)2][V(CO)6] dissolved in water (electrolyte) media gives insoluble V(CO)6, which precipitates onto platinum, gold, or carbon electrodes. Cyclic voltammetry, electrochemical quartz crystal microbalance, chronocoulometric, and electron microscopy studies show that V(CO)6 is precipitated as lumps of solid rather than as uniform layers. Voltammetric studies on [Na(diglyme)2][V(CO)6] mechanically attached to electrodes that are then placed into aqueous (electrolyte) media show distinct relationships to the voltammetry of dissolved [Na(diglyme)2][V(CO)6]. However, in this case, ion exchange with the electrolyte cations and gradual dissolution of the mechanically attached solid occurs. The potentials are independent of the electrolyte anions, but change considerably (>600 mV) with the electrolyte cation. In the cases of the tetraalkylammonium cations (NR4+), the potentials are correlated with the solubility products of [NR4][V(CO)6]. Equations are presented relating the potentials of the processes and the concentration of the cations and the solubility products of the salts. |
| first_indexed | 2025-11-15T14:28:35Z |
| format | Article |
| id | upm-116173 |
| institution | Universiti Putra Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-15T14:28:35Z |
| publishDate | 1998 |
| publisher | American Chemical Societyservice@acs.org |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | upm-1161732025-03-20T01:38:24Z http://psasir.upm.edu.my/id/eprint/116173/ Voltammetric oxidation of solution and solid phases of salts of [V(CO)6]- in aqueous (electrolyte) media Bond, Alan M. Colton, Ray Mahon, Peter J. Snook, Graeme A. Tan, Wee T. In the absence of water and oxygen the solution phase voltammetry of [V(CO)6]- in organic solvents exhibits an extremely well-defined, reversible, one-electron redox couple [V(CO)6]- ⇋ V(CO)6 + e-; ET1/2 = -0.35 V versus the ferrocenium/ferrocene (Fc+/Fc) couple, where ET1/2 is the reversible half-wave potential. Addition of water or oxygen causes the response to become irreversible, but all components remain soluble. Simulations of the solution-phase voltammetry in acetone/water mixtures (no oxygen present) are consistent with the mechanism V(CO)6 + H2O → V(CO)5(H2O) + CO. The sodium diglyme stabilized [V(CO)6]- salt ([Na-(diglyme)2][V(CO)6]) is slightly soluble in water without decomposition. In contrast, solid V(CO)6 is insoluble in water, but reacts so slowly with it that solid state voltammetry of the [V(CO)6]0/- system is possible in aqueous media. Oxidation of [Na(diglyme)2][V(CO)6] dissolved in water (electrolyte) media gives insoluble V(CO)6, which precipitates onto platinum, gold, or carbon electrodes. Cyclic voltammetry, electrochemical quartz crystal microbalance, chronocoulometric, and electron microscopy studies show that V(CO)6 is precipitated as lumps of solid rather than as uniform layers. Voltammetric studies on [Na(diglyme)2][V(CO)6] mechanically attached to electrodes that are then placed into aqueous (electrolyte) media show distinct relationships to the voltammetry of dissolved [Na(diglyme)2][V(CO)6]. However, in this case, ion exchange with the electrolyte cations and gradual dissolution of the mechanically attached solid occurs. The potentials are independent of the electrolyte anions, but change considerably (>600 mV) with the electrolyte cation. In the cases of the tetraalkylammonium cations (NR4+), the potentials are correlated with the solubility products of [NR4][V(CO)6]. Equations are presented relating the potentials of the processes and the concentration of the cations and the solubility products of the salts. American Chemical Societyservice@acs.org 1998 Article PeerReviewed Bond, Alan M. and Colton, Ray and Mahon, Peter J. and Snook, Graeme A. and Tan, Wee T. (1998) Voltammetric oxidation of solution and solid phases of salts of [V(CO)6]- in aqueous (electrolyte) media. Journal of Physical Chemistry B, 102 (7). pp. 1229-1234. ISSN 1520-6106; eISSN: 1520-6106 https://pubs.acs.org/doi/10.1021/jp972830d 10.1021/jp972830d |
| spellingShingle | Bond, Alan M. Colton, Ray Mahon, Peter J. Snook, Graeme A. Tan, Wee T. Voltammetric oxidation of solution and solid phases of salts of [V(CO)6]- in aqueous (electrolyte) media |
| title | Voltammetric oxidation of solution and solid phases of salts of [V(CO)6]- in aqueous (electrolyte) media |
| title_full | Voltammetric oxidation of solution and solid phases of salts of [V(CO)6]- in aqueous (electrolyte) media |
| title_fullStr | Voltammetric oxidation of solution and solid phases of salts of [V(CO)6]- in aqueous (electrolyte) media |
| title_full_unstemmed | Voltammetric oxidation of solution and solid phases of salts of [V(CO)6]- in aqueous (electrolyte) media |
| title_short | Voltammetric oxidation of solution and solid phases of salts of [V(CO)6]- in aqueous (electrolyte) media |
| title_sort | voltammetric oxidation of solution and solid phases of salts of [v(co)6]- in aqueous (electrolyte) media |
| url | http://psasir.upm.edu.my/id/eprint/116173/ http://psasir.upm.edu.my/id/eprint/116173/ http://psasir.upm.edu.my/id/eprint/116173/ |