Rapid-scan time-resolved FT-IR spectroelectrochemistry studies on the electrochemical redox process.
J Phys Chem B
; 111(7): 1517-22, 2007 Feb 22.
Article
en En
| MEDLINE
| ID: mdl-17256980
The electron transfer to or from molecules containing multiple redox centers has been extensively investigated. Rapid scan time-resolved FT-IR-RAS spectroelectrochemistry was used to investigate the electron-transfer mechanism in this report. The electron transfer of two typical compounds, 1,4-benzoquinone and 1,4-bis(2-ferrocenylvinyl)benzene, was examined with this method. Although the two compounds show two-electron transfer in the redox process, 1,4-benzoquinone exhibits two single electron waves while 1,4-bis(2-ferrocenylvinyl)benzene exhibits a single wave in cyclic voltammetric experiments. The IR absorption of the intermediate, BQ*- and p-(Fc-CH=CH)+2-benzene, at 1506 and 1589 cm(-1), respectively, appeared and disappeared on the experimental time scale in the oxidation and reduction process was observed. In the oxidation process of the p-(Fc-CH=CH)2-benzene molecule, one Fc was oxidated to Fc+ first and the electron-withdrawing ability of Fc+ was stronger than that of Fc, which resulted in the D-pi-A structure and the band at 1589 cm(-1) becoming visible. Then as the oxidation continues, the other Fc was oxidated to Fc+ too, which resulted in the reforming of the symmetry of the benzene ring A-pi-A, so the band at 1589 cm(-1) disappeared. Similar phenomenon can be elucidated in the reduction process but the configuration type changed from A-pi-A to D-pi-A and finally to D-pi-D. Hence, not only 1,4-benzoquinone but also 1,4-bis(2-ferrocenylvinyl)benzene show two consecutive one-electron processes. In addition, it is observed that the existing time of the electrochemical reaction intermediate (BQ*- and p-(Fc-CH=CH)+2-benzene) is prolonged at low temperatures due to slow reaction kinetics.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Compuestos Organometálicos
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Compuestos Ferrosos
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Benzoquinonas
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Espectroscopía Infrarroja por Transformada de Fourier
/
Estireno
Idioma:
En
Revista:
J Phys Chem B
Asunto de la revista:
QUIMICA
Año:
2007
Tipo del documento:
Article
Pais de publicación:
Estados Unidos