Kinetics of Dissociation of the Cobalt(II) and Copper(II) Complexes of 2,2′,2″-tris(monomethylamino)triethylamine in Aqueous Acidic Solution
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Florian Thaler
Abstract
The stability constant of the complex formed between cobalt(II) and trimethyltren (Me3tren), 2,2′,2″-triaminotriethylamine monomethylated on each terminal amino group, in aqueous medium was determined (log Κ = 12.10 ± 0.01 at 25.0° C and ionic strength of 1.0 mol dm-3 (NaClO4)). The deprotonation constant of the aqua complex, [Co(Me3tren)(H2O)]2+, was also established (pKa = 9.31 ± 0.02 under the same conditions). It is concluded on the basis of these values and properties such as the UV/vis spectrum, that the complex possesses trigonal bipyramidal geometry, as does the corresponding copper(II) complex. Dissociation of both complexes, as a function of aqueous acid concentration, was monitored spectrophotometrically. For the copper(II) system there is a modest dependence on the acid concentration when [H+] < 0.4 mol dm-3 , and above this value the reaction is independent of acid concentration, with the firstorder rate constant reaching a limiting value of about 100 s-1 at 25.0°C. Dissociation of the cobalt(II) complex does not depend on the acid concentration and occurs at a rate of 34 s-1 . A mechanism accounting for these findings is proposed, and the rate and activation parameters are discussed in terms of the dissociation of other trigonal bipyramidal complexes.
© 2014 by Walter de Gruyter Berlin/Boston
Articles in the same Issue
- Tribute
- Kinetics of Dissociation of the Cobalt(II) and Copper(II) Complexes of 2,2′,2″-tris(monomethylamino)triethylamine in Aqueous Acidic Solution
- The Influence of Steric Effects on the Oxidation Kinetics of [FeII(aminopolycarboxylato)] Complexes with Dioxygen
- The Hydrolysis Kinetics of ds-diamminedichloroplatinum(II). 10. Activation Volumes for Halide Anation of Some czs-[Pt(N)2(OH2)2]2+ Systems
- The Dependence of the Copper Dissociation Rate Constants from Human(Serum)- and Ονο-Transferrin on pH and the Anions
- Kinetics of the Photosubstitution of ds-Bis(benzonitrile)dichloroplatinum(II) in Chloroform
- Kinetics and Mechanisms of the Reaction of Aluminium(III) with Polyaminocarboxylic Acids
- Kinetics and Mechanism of Oxidation of Tellurium(IV) by Alkaline Diperiodatonickelate(IV)
- Complexation of Pendant Arm Macrocycles with Cu(II) Hydroxo Complexes in Strongly Alkaline Solutions. Investigation of pH Dependences
- Kinetics and Mechanism of the Chromium(VI) Oxidation of Formic Acid in the Presence of Picolinic Acid and in the Presence and Absence of Surfactants
- Kinetics and Mechanism of Chromium(III) Catalysed Oxidation of Propan-1-ol and Butan-1-ol by Cerium(IV) in Aqueous Sulfuric acid Media
- Notes for Contributors. Inorganic Reaction Mechanisms
- Journal Order Form
Articles in the same Issue
- Tribute
- Kinetics of Dissociation of the Cobalt(II) and Copper(II) Complexes of 2,2′,2″-tris(monomethylamino)triethylamine in Aqueous Acidic Solution
- The Influence of Steric Effects on the Oxidation Kinetics of [FeII(aminopolycarboxylato)] Complexes with Dioxygen
- The Hydrolysis Kinetics of ds-diamminedichloroplatinum(II). 10. Activation Volumes for Halide Anation of Some czs-[Pt(N)2(OH2)2]2+ Systems
- The Dependence of the Copper Dissociation Rate Constants from Human(Serum)- and Ονο-Transferrin on pH and the Anions
- Kinetics of the Photosubstitution of ds-Bis(benzonitrile)dichloroplatinum(II) in Chloroform
- Kinetics and Mechanisms of the Reaction of Aluminium(III) with Polyaminocarboxylic Acids
- Kinetics and Mechanism of Oxidation of Tellurium(IV) by Alkaline Diperiodatonickelate(IV)
- Complexation of Pendant Arm Macrocycles with Cu(II) Hydroxo Complexes in Strongly Alkaline Solutions. Investigation of pH Dependences
- Kinetics and Mechanism of the Chromium(VI) Oxidation of Formic Acid in the Presence of Picolinic Acid and in the Presence and Absence of Surfactants
- Kinetics and Mechanism of Chromium(III) Catalysed Oxidation of Propan-1-ol and Butan-1-ol by Cerium(IV) in Aqueous Sulfuric acid Media
- Notes for Contributors. Inorganic Reaction Mechanisms
- Journal Order Form
