Kinetics and mechanism of ligand interchange in the [RuIII(edta)L] complexes; L = Cysteine and related thiolates

Complexes of the [RuIII(edta)SR]n series, with SR- = deprotonated cysteine, N-acetylcysteine, 2-mercaptoethanol, glutathione and penicilamine, were prepared from [Ru(edta)H2O]- and the corresponding RSH thiols, at pH = 5.5. The complexes exhibit intense visible absorption bands at ca. 520 nm (ε ≅ 35...

Descripción completa

Detalles Bibliográficos
Autores principales: Povse, Vicente Gregorio, Olabe Iparraguirre, Jose Antonio
Publicado: 1998
Acceso en línea:https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_03404285_v23_n6_p657_Povse
http://hdl.handle.net/20.500.12110/paper_03404285_v23_n6_p657_Povse
Aporte de:
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
id paper:paper_03404285_v23_n6_p657_Povse
record_format dspace
spelling paper:paper_03404285_v23_n6_p657_Povse2023-06-08T15:33:57Z Kinetics and mechanism of ligand interchange in the [RuIII(edta)L] complexes; L = Cysteine and related thiolates Povse, Vicente Gregorio Olabe Iparraguirre, Jose Antonio Complexes of the [RuIII(edta)SR]n series, with SR- = deprotonated cysteine, N-acetylcysteine, 2-mercaptoethanol, glutathione and penicilamine, were prepared from [Ru(edta)H2O]- and the corresponding RSH thiols, at pH = 5.5. The complexes exhibit intense visible absorption bands at ca. 520 nm (ε ≅ 3500 M-1 cm-1), associated with LMCT from the sulfur ligands bound to RuIII. The kinetics of the formation reactions were first order in [RuIII(edta)H2O]- and thiol reactants, with k1 values ca. 1-5 × 102 M-1 s-1 (25°C) for all the sulfur ligands except penicilamine, which reacted slower by a factor of 10. Activation parameters suggest an associative mechanism, as for the coordination of other S-and N-bound ligands to [RuIII(edta)H2O]-. A reactivity decrease is apparent at low and high pH's (ranges 1-3 and 8-10, respectively), associated with acid-base equilibria involving the less reactive [RuIII(Hedta)H2O] and [RuIII(edta)OH]2- species. A significant rate increase was found for cysteine and penicilamine at ca. pH = 8.0, because the thiol reactants deprotonate. The equilibrium constants for all the ligands showed that robust complexes were formed, with K = ca. 1 × 105 M-1 (25°C). The dissociation rate constants, k-1, were in the 10-3-10-4 s-1 range. The influence of nucleophilic and steric effects increasing and decreasing the formation rates, respectively, is discussed for the thiolate ligands, with adequate comparisons with other L species bound to [RuIII(edta)H2O]-. Fil:Povse, V.G. 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. 1998 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_03404285_v23_n6_p657_Povse http://hdl.handle.net/20.500.12110/paper_03404285_v23_n6_p657_Povse
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
description Complexes of the [RuIII(edta)SR]n series, with SR- = deprotonated cysteine, N-acetylcysteine, 2-mercaptoethanol, glutathione and penicilamine, were prepared from [Ru(edta)H2O]- and the corresponding RSH thiols, at pH = 5.5. The complexes exhibit intense visible absorption bands at ca. 520 nm (ε ≅ 3500 M-1 cm-1), associated with LMCT from the sulfur ligands bound to RuIII. The kinetics of the formation reactions were first order in [RuIII(edta)H2O]- and thiol reactants, with k1 values ca. 1-5 × 102 M-1 s-1 (25°C) for all the sulfur ligands except penicilamine, which reacted slower by a factor of 10. Activation parameters suggest an associative mechanism, as for the coordination of other S-and N-bound ligands to [RuIII(edta)H2O]-. A reactivity decrease is apparent at low and high pH's (ranges 1-3 and 8-10, respectively), associated with acid-base equilibria involving the less reactive [RuIII(Hedta)H2O] and [RuIII(edta)OH]2- species. A significant rate increase was found for cysteine and penicilamine at ca. pH = 8.0, because the thiol reactants deprotonate. The equilibrium constants for all the ligands showed that robust complexes were formed, with K = ca. 1 × 105 M-1 (25°C). The dissociation rate constants, k-1, were in the 10-3-10-4 s-1 range. The influence of nucleophilic and steric effects increasing and decreasing the formation rates, respectively, is discussed for the thiolate ligands, with adequate comparisons with other L species bound to [RuIII(edta)H2O]-.
author Povse, Vicente Gregorio
Olabe Iparraguirre, Jose Antonio
spellingShingle Povse, Vicente Gregorio
Olabe Iparraguirre, Jose Antonio
Kinetics and mechanism of ligand interchange in the [RuIII(edta)L] complexes; L = Cysteine and related thiolates
author_facet Povse, Vicente Gregorio
Olabe Iparraguirre, Jose Antonio
author_sort Povse, Vicente Gregorio
title Kinetics and mechanism of ligand interchange in the [RuIII(edta)L] complexes; L = Cysteine and related thiolates
title_short Kinetics and mechanism of ligand interchange in the [RuIII(edta)L] complexes; L = Cysteine and related thiolates
title_full Kinetics and mechanism of ligand interchange in the [RuIII(edta)L] complexes; L = Cysteine and related thiolates
title_fullStr Kinetics and mechanism of ligand interchange in the [RuIII(edta)L] complexes; L = Cysteine and related thiolates
title_full_unstemmed Kinetics and mechanism of ligand interchange in the [RuIII(edta)L] complexes; L = Cysteine and related thiolates
title_sort kinetics and mechanism of ligand interchange in the [ruiii(edta)l] complexes; l = cysteine and related thiolates
publishDate 1998
url https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_03404285_v23_n6_p657_Povse
http://hdl.handle.net/20.500.12110/paper_03404285_v23_n6_p657_Povse
work_keys_str_mv AT povsevicentegregorio kineticsandmechanismofligandinterchangeintheruiiiedtalcomplexeslcysteineandrelatedthiolates
AT olabeiparraguirrejoseantonio kineticsandmechanismofligandinterchangeintheruiiiedtalcomplexeslcysteineandrelatedthiolates
_version_ 1768545330010259456

Ejemplares similares