Artículo
Abstract:
The mixed-valence compound [(NC)5FeII-Im-RuIII(NH3) 5]-,Mi, was prepared in solution and as a solid sodium salt from [Fe(CN)5H2O]3- and [Ru(NH3)5Im]2+. The binuclear complex shows two bands at 366 nm (∈ = 3350 M-1 cm-1) and 576 nm (∈ = 1025 M-1 cm-1), assigned as LMCT transitions, as well as a near-IR band at 979 nm (∈ = 962 M-1 cm-1) associated with an intervalence transition. By calculation of the Hush model parameters α2 and Hab (delocalization and electronic coupling factors, respectively), the complex is defined as a valence-trapped FeII-RuIII system; this is confirmed by the measured redox potentials at -0.20 V and 0.30 V, associated with redox processes at the ruthenium and iron center, respectively. The formation stability constant of the mixed-valence ion was obtained through independent measurements of kf and kd, the formation and dissociation specific rate constants, respectively. The stabilization of Mi with respect to disproportionation into the isovalent states, as well as toward the formation of the electronic isomer, FeIII-Im-RuII, was also estimated. The fully reduced (Ri) and fully oxidized (Oi) binuclear complexes were prepared in solution and characterized by UV-vis spectroscopy. The kinetics of the reactions of Ri and Mi with peroxydisulfate were measured and a mechanistic analysis was performed, showing the relevance of electronic isomerization in completing the full conversion to Oi, through the assistance of the RuII(NH3)52+ center in the oxidation of the neighboring FeII(CN)53- moiety. The latter results are compared with those obtained with related complexes comprising different X5M-L moieties bound to RuII(NH3)52+. A linear correlation is displayed by plotting In ket against E°Ru, associated with the intramolecular oxidation rate constant of RuII in the ion pair (binuclear species + peroxydisulfate) and the reduction potential of the corresponding RuIII,II couple in the ion pair.
Registro:
| Documento: | Artículo |
| Título: | Electronic Structure and Substitution and Redox Reactivity of Imidazolate-Bridged Complexes of Pentacyanoferrate and Pentaammineruthenium |
| Autor: | Parise, A.R.; Baraldo, L.M.; Olabe, J.A. |
| Filiación: | Depto. de Quim. Inorgánica, Fac. de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 2, Capital Federal 1428, Argentina |
| Año: | 1996 |
| Volumen: | 35 |
| Número: | 17 |
| Página de inicio: | 5080 |
| Página de fin: | 5086 |
| Título revista: | Inorganic Chemistry |
| Título revista abreviado: | Inorg. Chem. |
| ISSN: | 00201669 |
| CODEN: | INOCA |
| Registro: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00201669_v35_n17_p5080_Parise |
Referencias:
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- A 10-2 M solution of Mi was diluted to 10-4 M and made to react rapidly with peroxydisulfate, thus avoiding the presence of significant amounts of Ru(NH3)5Im2+ (the Ru(III) mononuclear species may catalyze the oxidation reaction of Mi through an intermolecular path; see below); Kuehn, C.G., Taube, H., (1976) J. Am. Chem. Soc., 98, p. 689
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- By considering the species ImH2+, FeIII(CN)5ImH2-, and FeII(CN)5ImH3-, we can use the pKa data (7.1, ref 13; 10.5, ref 5; ca. 14, respectively) to estimate the relative electron-withdrawing abilities of the corresponding moieties toward ImH. By the replacement of H by the RuIII(NH3)53+ moiety in the above series, reduction potentials at the Ru site have been measured for RuIII(NH3)5ImH3+ (0.11 V, ref 26) and for [(NC)5FeIIImRuIII(NH3) 5]- (-0.20 V, this work). By interpolating in the linear correlation of E°Ru against pKa, we estimate E = -0.05 V for the reduction at [(NC)5FeIIIImRuIII(NH3) 5]; The experiment showing the conversion Ri → Mi was performed qualitatively, by mixing equimolar amounts of Ri and peroxydisulfate; as the Ri complex is unstable, the mixture contains significant amounts of the mononuclear species. However, an unmeasurable rising trace was observed at 820 nm, followed by a slower decay (conversion Mi → Oi); Haim, A., (1985) Comments Inorg. Chem., 4, p. 113
- Ram, M.S., Haim, A., (1991) Inorg. Chem., 30, p. 1319
- Almaraz, A.E., Gentil, L.A., Baraldo, L.M., Olabe, J.A., Submitted for publication; Miralles, A.J., Armstrong, R.E., Haim, A., (1977) J. Am Chem. Soc., 99, p. 1416
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Citas:
---------- APA ----------
Parise, A.R., Baraldo, L.M. & Olabe, J.A. (1996) . Electronic Structure and Substitution and Redox Reactivity of Imidazolate-Bridged Complexes of Pentacyanoferrate and Pentaammineruthenium. Inorganic Chemistry, 35(17), 5080-5086.Recuperado de https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00201669_v35_n17_p5080_Parise [ ]
---------- CHICAGO ----------
Parise, A.R., Baraldo, L.M., Olabe, J.A. "Electronic Structure and Substitution and Redox Reactivity of Imidazolate-Bridged Complexes of Pentacyanoferrate and Pentaammineruthenium" . Inorganic Chemistry 35, no. 17 (1996) : 5080-5086.Recuperado de https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00201669_v35_n17_p5080_Parise [ ]
---------- MLA ----------
Parise, A.R., Baraldo, L.M., Olabe, J.A. "Electronic Structure and Substitution and Redox Reactivity of Imidazolate-Bridged Complexes of Pentacyanoferrate and Pentaammineruthenium" . Inorganic Chemistry, vol. 35, no. 17, 1996, pp. 5080-5086.Recuperado de https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00201669_v35_n17_p5080_Parise [ ]
---------- VANCOUVER ----------
Parise, A.R., Baraldo, L.M., Olabe, J.A. Electronic Structure and Substitution and Redox Reactivity of Imidazolate-Bridged Complexes of Pentacyanoferrate and Pentaammineruthenium. Inorg. Chem. 1996;35(17):5080-5086.Available from: https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00201669_v35_n17_p5080_Parise [ ]
