Electronic Structure and Substitution and Redox Reactivity of Imidazolate-Bridged Complexes of Pentacyanoferrate and Pentaammineruthenium

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-...

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Autores principales: Parise, Alejandro Rubén, Baraldo Victorica, Luis Mario, Olabe Iparraguirre, Jose Antonio
Publicado: 1996
Acceso en línea:https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00201669_v35_n17_p5080_Parise
http://hdl.handle.net/20.500.12110/paper_00201669_v35_n17_p5080_Parise
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Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
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spelling paper:paper_00201669_v35_n17_p5080_Parise2023-06-08T14:40:24Z Electronic Structure and Substitution and Redox Reactivity of Imidazolate-Bridged Complexes of Pentacyanoferrate and Pentaammineruthenium Parise, Alejandro Rubén Baraldo Victorica, Luis Mario Olabe Iparraguirre, Jose Antonio 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. Fil:Parise, A.R. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Baraldo, L.M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Olabe, J.A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. 1996 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00201669_v35_n17_p5080_Parise http://hdl.handle.net/20.500.12110/paper_00201669_v35_n17_p5080_Parise
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
description 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.
author Parise, Alejandro Rubén
Baraldo Victorica, Luis Mario
Olabe Iparraguirre, Jose Antonio
spellingShingle Parise, Alejandro Rubén
Baraldo Victorica, Luis Mario
Olabe Iparraguirre, Jose Antonio
Electronic Structure and Substitution and Redox Reactivity of Imidazolate-Bridged Complexes of Pentacyanoferrate and Pentaammineruthenium
author_facet Parise, Alejandro Rubén
Baraldo Victorica, Luis Mario
Olabe Iparraguirre, Jose Antonio
author_sort Parise, Alejandro Rubén
title Electronic Structure and Substitution and Redox Reactivity of Imidazolate-Bridged Complexes of Pentacyanoferrate and Pentaammineruthenium
title_short Electronic Structure and Substitution and Redox Reactivity of Imidazolate-Bridged Complexes of Pentacyanoferrate and Pentaammineruthenium
title_full Electronic Structure and Substitution and Redox Reactivity of Imidazolate-Bridged Complexes of Pentacyanoferrate and Pentaammineruthenium
title_fullStr Electronic Structure and Substitution and Redox Reactivity of Imidazolate-Bridged Complexes of Pentacyanoferrate and Pentaammineruthenium
title_full_unstemmed Electronic Structure and Substitution and Redox Reactivity of Imidazolate-Bridged Complexes of Pentacyanoferrate and Pentaammineruthenium
title_sort electronic structure and substitution and redox reactivity of imidazolate-bridged complexes of pentacyanoferrate and pentaammineruthenium
publishDate 1996
url https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00201669_v35_n17_p5080_Parise
http://hdl.handle.net/20.500.12110/paper_00201669_v35_n17_p5080_Parise
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