Mixed-valence cyano-bridged complexes containing [M(CN)6]4 (M = Fe, Ru or Os) and [Runi(edta)]~ (edta = ethylenedinitrilotetraacetate): Synthesis, spectroscopic and kinetic characterization

The mixed-valence, cyanide-bridged complexes K5[(NC)jMII-CN-RuI(edta)] (M = Fe, Ru or Os; edta = ethylenedinitrilotetraacetate) were prepared by mixing the hexacyanide species with a solution of [Ru(edta)(H 22 O)]~. The complexes were characterized by chemical analysis, IR, Raman and VIS/NIR spectro...

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Publicado: 1997
Acceso en línea:https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_03009246_v_n9_p1595_Forlano
http://hdl.handle.net/20.500.12110/paper_03009246_v_n9_p1595_Forlano
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spelling paper:paper_03009246_v_n9_p1595_Forlano2023-06-08T15:27:35Z Mixed-valence cyano-bridged complexes containing [M(CN)6]4 (M = Fe, Ru or Os) and [Runi(edta)]~ (edta = ethylenedinitrilotetraacetate): Synthesis, spectroscopic and kinetic characterization The mixed-valence, cyanide-bridged complexes K5[(NC)jMII-CN-RuI(edta)] (M = Fe, Ru or Os; edta = ethylenedinitrilotetraacetate) were prepared by mixing the hexacyanide species with a solution of [Ru(edta)(H 22 O)]~. The complexes were characterized by chemical analysis, IR, Raman and VIS/NIR spectroscopy. They show an intense band in the 600-1000 nm region (dependent on M), associated with an intervalence (i.v.) transition from M to Ru1, as confirmed by electrochemical measurements of the redox potentials at both metal centres. The equilibrium constants for the formation of the binuclear species were similar for the three complexes, (1.5 ±0.1) x 103 dm3 mol1. These complexes were the predominant species in excess of free hexacyanide, but tri- and poly-nuclear species were obtained by increasing the concentration of [Ru(edta)(H 22 O)]~, as demonstrated through the electronic spectral shifts of the i.v. band and the redox potentials of the M couples, which were indicative of Ru(edta) co-ordination to the exposed nitrogen ends of cyanides in the precursor binuclear complexes. The kinetics of formation and dissociation of the binuclear complexes were also measured, with k, and kA showing values nearly independent of.M (ca. 10 dm3 mol1 s1 and 8 x 10~3 s1 respectively, at 25.0 °C, /= 0.1 mol dnT3), suggesting thé onset of associative mechanisms. The Hush model showed the three complexes to adopt a valence-trapped behaviour, with a moderate coupling between the metal centres. 1997 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_03009246_v_n9_p1595_Forlano http://hdl.handle.net/20.500.12110/paper_03009246_v_n9_p1595_Forlano
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, cyanide-bridged complexes K5[(NC)jMII-CN-RuI(edta)] (M = Fe, Ru or Os; edta = ethylenedinitrilotetraacetate) were prepared by mixing the hexacyanide species with a solution of [Ru(edta)(H 22 O)]~. The complexes were characterized by chemical analysis, IR, Raman and VIS/NIR spectroscopy. They show an intense band in the 600-1000 nm region (dependent on M), associated with an intervalence (i.v.) transition from M to Ru1, as confirmed by electrochemical measurements of the redox potentials at both metal centres. The equilibrium constants for the formation of the binuclear species were similar for the three complexes, (1.5 ±0.1) x 103 dm3 mol1. These complexes were the predominant species in excess of free hexacyanide, but tri- and poly-nuclear species were obtained by increasing the concentration of [Ru(edta)(H 22 O)]~, as demonstrated through the electronic spectral shifts of the i.v. band and the redox potentials of the M couples, which were indicative of Ru(edta) co-ordination to the exposed nitrogen ends of cyanides in the precursor binuclear complexes. The kinetics of formation and dissociation of the binuclear complexes were also measured, with k, and kA showing values nearly independent of.M (ca. 10 dm3 mol1 s1 and 8 x 10~3 s1 respectively, at 25.0 °C, /= 0.1 mol dnT3), suggesting thé onset of associative mechanisms. The Hush model showed the three complexes to adopt a valence-trapped behaviour, with a moderate coupling between the metal centres.
title Mixed-valence cyano-bridged complexes containing [M(CN)6]4 (M = Fe, Ru or Os) and [Runi(edta)]~ (edta = ethylenedinitrilotetraacetate): Synthesis, spectroscopic and kinetic characterization
spellingShingle Mixed-valence cyano-bridged complexes containing [M(CN)6]4 (M = Fe, Ru or Os) and [Runi(edta)]~ (edta = ethylenedinitrilotetraacetate): Synthesis, spectroscopic and kinetic characterization
title_short Mixed-valence cyano-bridged complexes containing [M(CN)6]4 (M = Fe, Ru or Os) and [Runi(edta)]~ (edta = ethylenedinitrilotetraacetate): Synthesis, spectroscopic and kinetic characterization
title_full Mixed-valence cyano-bridged complexes containing [M(CN)6]4 (M = Fe, Ru or Os) and [Runi(edta)]~ (edta = ethylenedinitrilotetraacetate): Synthesis, spectroscopic and kinetic characterization
title_fullStr Mixed-valence cyano-bridged complexes containing [M(CN)6]4 (M = Fe, Ru or Os) and [Runi(edta)]~ (edta = ethylenedinitrilotetraacetate): Synthesis, spectroscopic and kinetic characterization
title_full_unstemmed Mixed-valence cyano-bridged complexes containing [M(CN)6]4 (M = Fe, Ru or Os) and [Runi(edta)]~ (edta = ethylenedinitrilotetraacetate): Synthesis, spectroscopic and kinetic characterization
title_sort mixed-valence cyano-bridged complexes containing [m(cn)6]4 (m = fe, ru or os) and [runi(edta)]~ (edta = ethylenedinitrilotetraacetate): synthesis, spectroscopic and kinetic characterization
publishDate 1997
url https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_03009246_v_n9_p1595_Forlano
http://hdl.handle.net/20.500.12110/paper_03009246_v_n9_p1595_Forlano
_version_ 1768542362539130880