Kinetics and mechanism of interactions of some monofunctional Au(III) complexes with sulphur nucleophiles

Kinetics of the substitution reactions between monofunctional Au(III) complexes, [Au(dien)Cl] 2+ , [Au(bpma)Cl] 2+ and [Au(terpy)Cl] 2+ (dien = 3-azapentane-1,5-diamine, bpma = di-(2-picolyl) amine, terpy = 2,2′;6′,2″-terpyridine), and biologically relevant sulphur ligands, namely glutathione (GSH),...

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Bibliographic Details
Published in:Transition metal chemistry (Weinheim) 2018-05, Vol.43 (4), p.331-338
Main Authors: Radisavljević, Snežana, Kesić, Ana Đeković, Jovanović, Snežana, Petrović, Biljana
Format: Article
Language:English
Subjects:
Catalysis
Chemistry
Chemistry and Materials Science
Glutathione
Inorganic Chemistry
Ligands
Methionine
Nucleophiles
Organometallic Chemistry
Physical Chemistry
Reaction kinetics
Spectrophotometry
Substitution reactions
Sulfur
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Summary:Kinetics of the substitution reactions between monofunctional Au(III) complexes, [Au(dien)Cl] 2+ , [Au(bpma)Cl] 2+ and [Au(terpy)Cl] 2+ (dien = 3-azapentane-1,5-diamine, bpma = di-(2-picolyl) amine, terpy = 2,2′;6′,2″-terpyridine), and biologically relevant sulphur ligands, namely glutathione (GSH), l -methionine ( l -Met) and l -cysteine ( l -Cys), were studied in 0.1 M HCl (pH = 1.0). The reactions were followed under pseudo -first-order conditions as a function of ligand concentration and temperature using stopped-flow spectrophotometry. The [Au(terpy)Cl] 2+ complex proved to be more reactive than the [Au(bpma)Cl] 2+ and [Au(dien)Cl] 2+ complexes. The reactivities of the nucleophiles follow the same order for all three complexes, viz. l -Met > GSH >  l -Cys. Values of the activation parameters of the reactions support an associative substitution mechanism. In order to confirm that these monofunctional Au(III) complexes undergo a single substitution process in strongly acidic medium, the reaction between [Au(terpy)Cl] 2+ and l -Met was studied by HPLC. At pH = 1.0, only one reaction product was detected.
ISSN:0340-4285
1572-901X
DOI:10.1007/s11243-018-0221-9