Voltammetry, Electron Microscopy, and X-ray Electron Probe Microanalysis at the Electrode-Aqueous Electrolyte Interface of Solid Microcrystalline cis- and trans-Cr(CO)2(dpe)2 and trans-[Cr(CO)2(dpe)2]+ Complexes (dpe = Ph2PCH2CH2PPh2) Mechanically Attached to Carbon Electrodes

Alan M. Bond; Ray Colton; Fred Daniels; Denise R. Fernando; Frank Marken; Yukio Nagaosa; Reinhard F.M. Van Steveninck; Jacky N. Walter

doi:10.1021/ja00074a021

Voltammetry, Electron Microscopy, and X-ray Electron Probe Microanalysis at the Electrode-Aqueous Electrolyte Interface of Solid Microcrystalline cis- and trans-Cr(CO)₂(dpe)₂ and trans-[Cr(CO)₂(dpe)₂]⁺ Complexes (dpe = Ph₂PCH₂CH₂PPh₂) Mechanically Attached to Carbon Electrodes

Alan M. Bond, Ray Colton, Fred Daniels, Denise R. Fernando, Frank Marken, Yukio Nagaosa, Reinhard F.M. Van Steveninck, Jacky N. Walter

Research output: Contribution to journal › Article › peer-review

Abstract

Microcrystalline forms (size range 0.1–10μm) of cis-Cr(CO)₂(dpe)₂ (cis⁰), trans-Cr(CO)₂(dpe)₂ (trans⁰), and trans-[Cr(CO)₂(dpe)₂]⁺ (trans⁺) (dpe = Ph₂PCH₂CH₂PPh₂) may be mechanically attached to carbon electrodes. The voltammetry of these water-insoluble materials produces exceedingly well defined processes over a wide scan rate range when the electrode is placed into aqueous media containing 0.1 M NaClO₄ or 0.1 M KClO₄ as the electrolyte. Electron probe microanalysis demonstrates that ClO₄⁻ partially covers the edges and the surface of the solid after oxidative electrolysis. This suggests that oxidative voltammetry of the uncharged complex occurs at the crystalelectrode-solution interface to form a perchlorate complex. The redox processes observed for the arrays of microcrystalline carbonyl compounds attached to the electrode may be summarized by the following reaction schemes: cis-Cr(CO)₂-(dpe)₂ ⇆ cis-Cr(CO)₂(dpe)₂ + e⁻ and trans-Cr(CO)₂(dpe)₂ ⇆ trans-[Cr(CO)₂(dpe)₂]⁺ + e⁻ ⇌ trans- [Cr(CO)₂(dpe)₂]⁺ + e⁻ with cis-[Cr(CO)₂(dpe)₂]⁺ slowly isomerizing to trans-[Cr(CO)₂(dpe)₂]⁺. Interestingly, the trans⁰ complex may be reversibly oxidized to trans* and trans²⁺ under most conditions, but not as readily reduced from trans⁺ back to trans⁰ if the potential is held for short periods of time at potentials intermediate between the trans^+/0 and trans^2+/+ processes. This indicates that the presence of a pure trans⁺ phase hinders reduction; however stepping the potential to a value more negative than the reduction potential of the trans⁺/ trans⁰ couple and then scanning in the positive potential direction restores the current to its original value. The experimental results are in accord with an electrochemical process that takes place at the solid-solution interface to form a layer of oxidized material. Electron transfer is postulated to occur by electron hopping via self exchange and cross redox reactions with the rate (apparent diffusion coefficient) being dependent on the state of the electrode-compound-solution interface and the surface charge.

Original language	English
Pages (from-to)	9556-9562
Number of pages	7
Journal	Journal of the American Chemical Society
Volume	115
Issue number	21
DOIs	https://doi.org/10.1021/ja00074a021
Publication status	Published - 1 Oct 1993

ASJC Scopus subject areas

Catalysis
General Chemistry
Biochemistry
Colloid and Surface Chemistry

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Bond, A. M., Colton, R., Daniels, F., Fernando, D. R., Marken, F., Nagaosa, Y., Van Steveninck, R. F. M., & Walter, J. N. (1993). Voltammetry, Electron Microscopy, and X-ray Electron Probe Microanalysis at the Electrode-Aqueous Electrolyte Interface of Solid Microcrystalline cis- and trans-Cr(CO)₂(dpe)₂ and trans-[Cr(CO)₂(dpe)₂]⁺ Complexes (dpe = Ph₂PCH₂CH₂PPh₂) Mechanically Attached to Carbon Electrodes. Journal of the American Chemical Society, 115(21), 9556-9562. https://doi.org/10.1021/ja00074a021

Voltammetry, Electron Microscopy, and X-ray Electron Probe Microanalysis at the Electrode-Aqueous Electrolyte Interface of Solid Microcrystalline cis- and trans-Cr(CO)₂(dpe)₂ and trans-[Cr(CO)₂(dpe)₂]⁺ Complexes (dpe = Ph₂PCH₂CH₂PPh₂) Mechanically Attached to Carbon Electrodes. / Bond, Alan M.; Colton, Ray; Daniels, Fred et al.
In: Journal of the American Chemical Society, Vol. 115, No. 21, 01.10.1993, p. 9556-9562.

Research output: Contribution to journal › Article › peer-review

Bond, AM, Colton, R, Daniels, F, Fernando, DR, Marken, F, Nagaosa, Y, Van Steveninck, RFM & Walter, JN 1993, 'Voltammetry, Electron Microscopy, and X-ray Electron Probe Microanalysis at the Electrode-Aqueous Electrolyte Interface of Solid Microcrystalline cis- and trans-Cr(CO)₂(dpe)₂ and trans-[Cr(CO)₂(dpe)₂]⁺ Complexes (dpe = Ph₂PCH₂CH₂PPh₂) Mechanically Attached to Carbon Electrodes', Journal of the American Chemical Society, vol. 115, no. 21, pp. 9556-9562. https://doi.org/10.1021/ja00074a021

Bond AM, Colton R, Daniels F, Fernando DR, Marken F, Nagaosa Y et al. Voltammetry, Electron Microscopy, and X-ray Electron Probe Microanalysis at the Electrode-Aqueous Electrolyte Interface of Solid Microcrystalline cis- and trans-Cr(CO)₂(dpe)₂ and trans-[Cr(CO)₂(dpe)₂]⁺ Complexes (dpe = Ph₂PCH₂CH₂PPh₂) Mechanically Attached to Carbon Electrodes. Journal of the American Chemical Society. 1993 Oct 1;115(21):9556-9562. doi: 10.1021/ja00074a021

Bond, Alan M. ; Colton, Ray ; Daniels, Fred et al. / Voltammetry, Electron Microscopy, and X-ray Electron Probe Microanalysis at the Electrode-Aqueous Electrolyte Interface of Solid Microcrystalline cis- and trans-Cr(CO)₂(dpe)₂ and trans-[Cr(CO)₂(dpe)₂]⁺ Complexes (dpe = Ph₂PCH₂CH₂PPh₂) Mechanically Attached to Carbon Electrodes. In: Journal of the American Chemical Society. 1993 ; Vol. 115, No. 21. pp. 9556-9562.

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title = "Voltammetry, Electron Microscopy, and X-ray Electron Probe Microanalysis at the Electrode-Aqueous Electrolyte Interface of Solid Microcrystalline cis- and trans-Cr(CO)2(dpe)2 and trans-[Cr(CO)2(dpe)2]+ Complexes (dpe = Ph2PCH2CH2PPh2) Mechanically Attached to Carbon Electrodes",

abstract = "Microcrystalline forms (size range 0.1–10μm) of cis-Cr(CO)2(dpe)2 (cis0), trans-Cr(CO)2(dpe)2 (trans0), and trans-[Cr(CO)2(dpe)2]+ (trans+) (dpe = Ph2PCH2CH2PPh2) may be mechanically attached to carbon electrodes. The voltammetry of these water-insoluble materials produces exceedingly well defined processes over a wide scan rate range when the electrode is placed into aqueous media containing 0.1 M NaClO4 or 0.1 M KClO4 as the electrolyte. Electron probe microanalysis demonstrates that ClO4− partially covers the edges and the surface of the solid after oxidative electrolysis. This suggests that oxidative voltammetry of the uncharged complex occurs at the crystalelectrode-solution interface to form a perchlorate complex. The redox processes observed for the arrays of microcrystalline carbonyl compounds attached to the electrode may be summarized by the following reaction schemes: cis-Cr(CO)2-(dpe)2 ⇆ cis-Cr(CO)2(dpe)2 + e− and trans-Cr(CO)2(dpe)2 ⇆ trans-[Cr(CO)2(dpe)2]+ + e− ⇌ trans- [Cr(CO)2(dpe)2]+ + e− with cis-[Cr(CO)2(dpe)2]+ slowly isomerizing to trans-[Cr(CO)2(dpe)2]+. Interestingly, the trans0 complex may be reversibly oxidized to trans* and trans2+ under most conditions, but not as readily reduced from trans+ back to trans0 if the potential is held for short periods of time at potentials intermediate between the trans+/0 and trans2+/+ processes. This indicates that the presence of a pure trans+ phase hinders reduction; however stepping the potential to a value more negative than the reduction potential of the trans+/ trans0 couple and then scanning in the positive potential direction restores the current to its original value. The experimental results are in accord with an electrochemical process that takes place at the solid-solution interface to form a layer of oxidized material. Electron transfer is postulated to occur by electron hopping via self exchange and cross redox reactions with the rate (apparent diffusion coefficient) being dependent on the state of the electrode-compound-solution interface and the surface charge.",

author = "Bond, {Alan M.} and Ray Colton and Fred Daniels and Fernando, {Denise R.} and Frank Marken and Yukio Nagaosa and {Van Steveninck}, {Reinhard F.M.} and Walter, {Jacky N.}",

year = "1993",

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doi = "10.1021/ja00074a021",

language = "English",

volume = "115",

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journal = "Journal of the American Chemical Society",

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T1 - Voltammetry, Electron Microscopy, and X-ray Electron Probe Microanalysis at the Electrode-Aqueous Electrolyte Interface of Solid Microcrystalline cis- and trans-Cr(CO)2(dpe)2 and trans-[Cr(CO)2(dpe)2]+ Complexes (dpe = Ph2PCH2CH2PPh2) Mechanically Attached to Carbon Electrodes

AU - Bond, Alan M.

AU - Colton, Ray

AU - Daniels, Fred

AU - Fernando, Denise R.

AU - Marken, Frank

AU - Nagaosa, Yukio

AU - Van Steveninck, Reinhard F.M.

AU - Walter, Jacky N.

PY - 1993/10/1

Y1 - 1993/10/1

N2 - Microcrystalline forms (size range 0.1–10μm) of cis-Cr(CO)2(dpe)2 (cis0), trans-Cr(CO)2(dpe)2 (trans0), and trans-[Cr(CO)2(dpe)2]+ (trans+) (dpe = Ph2PCH2CH2PPh2) may be mechanically attached to carbon electrodes. The voltammetry of these water-insoluble materials produces exceedingly well defined processes over a wide scan rate range when the electrode is placed into aqueous media containing 0.1 M NaClO4 or 0.1 M KClO4 as the electrolyte. Electron probe microanalysis demonstrates that ClO4− partially covers the edges and the surface of the solid after oxidative electrolysis. This suggests that oxidative voltammetry of the uncharged complex occurs at the crystalelectrode-solution interface to form a perchlorate complex. The redox processes observed for the arrays of microcrystalline carbonyl compounds attached to the electrode may be summarized by the following reaction schemes: cis-Cr(CO)2-(dpe)2 ⇆ cis-Cr(CO)2(dpe)2 + e− and trans-Cr(CO)2(dpe)2 ⇆ trans-[Cr(CO)2(dpe)2]+ + e− ⇌ trans- [Cr(CO)2(dpe)2]+ + e− with cis-[Cr(CO)2(dpe)2]+ slowly isomerizing to trans-[Cr(CO)2(dpe)2]+. Interestingly, the trans0 complex may be reversibly oxidized to trans* and trans2+ under most conditions, but not as readily reduced from trans+ back to trans0 if the potential is held for short periods of time at potentials intermediate between the trans+/0 and trans2+/+ processes. This indicates that the presence of a pure trans+ phase hinders reduction; however stepping the potential to a value more negative than the reduction potential of the trans+/ trans0 couple and then scanning in the positive potential direction restores the current to its original value. The experimental results are in accord with an electrochemical process that takes place at the solid-solution interface to form a layer of oxidized material. Electron transfer is postulated to occur by electron hopping via self exchange and cross redox reactions with the rate (apparent diffusion coefficient) being dependent on the state of the electrode-compound-solution interface and the surface charge.

AB - Microcrystalline forms (size range 0.1–10μm) of cis-Cr(CO)2(dpe)2 (cis0), trans-Cr(CO)2(dpe)2 (trans0), and trans-[Cr(CO)2(dpe)2]+ (trans+) (dpe = Ph2PCH2CH2PPh2) may be mechanically attached to carbon electrodes. The voltammetry of these water-insoluble materials produces exceedingly well defined processes over a wide scan rate range when the electrode is placed into aqueous media containing 0.1 M NaClO4 or 0.1 M KClO4 as the electrolyte. Electron probe microanalysis demonstrates that ClO4− partially covers the edges and the surface of the solid after oxidative electrolysis. This suggests that oxidative voltammetry of the uncharged complex occurs at the crystalelectrode-solution interface to form a perchlorate complex. The redox processes observed for the arrays of microcrystalline carbonyl compounds attached to the electrode may be summarized by the following reaction schemes: cis-Cr(CO)2-(dpe)2 ⇆ cis-Cr(CO)2(dpe)2 + e− and trans-Cr(CO)2(dpe)2 ⇆ trans-[Cr(CO)2(dpe)2]+ + e− ⇌ trans- [Cr(CO)2(dpe)2]+ + e− with cis-[Cr(CO)2(dpe)2]+ slowly isomerizing to trans-[Cr(CO)2(dpe)2]+. Interestingly, the trans0 complex may be reversibly oxidized to trans* and trans2+ under most conditions, but not as readily reduced from trans+ back to trans0 if the potential is held for short periods of time at potentials intermediate between the trans+/0 and trans2+/+ processes. This indicates that the presence of a pure trans+ phase hinders reduction; however stepping the potential to a value more negative than the reduction potential of the trans+/ trans0 couple and then scanning in the positive potential direction restores the current to its original value. The experimental results are in accord with an electrochemical process that takes place at the solid-solution interface to form a layer of oxidized material. Electron transfer is postulated to occur by electron hopping via self exchange and cross redox reactions with the rate (apparent diffusion coefficient) being dependent on the state of the electrode-compound-solution interface and the surface charge.

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