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Equilibrium and High-Pressure Kinetic Study of Formation and Proton-Assisted Aquation of Monodentate Acetate, Propionate, and Glycolate Complexes of Palladium(II) in Aqueous Solution

Shi, Tiesheng LU and Elding, Lars Ivar LU (1996) In Inorganic Chemistry 1996(35). p.735-740
Abstract (Swedish)
Synopsis
Reversible formation and proton-assisted aquation of 1:1 monodentate carboxylate complexes of palladium(II) takes place via a transition state stabilized by hydrogen bonding in an activation process strongly dominated by bond making. Volume profiles have been established through high-pressure kinetic measurements.
Abstract
Abstract Image
Kinetics and equilibria for reversible formation of 1:1 monodentate complexes between Pd(H2O)42+ and acetic, propionic, and glycolic acid (RCOOH) according to the equation Pd(H2O)42+ + RCOOH ⇌ Pd(H2O)3OOCR+ + H3O+ (k1, k-1) have been studied as a function of temperature and pressure in an aqueous medium with 0.60 ≤ [H+] ≤ 1.00 M, [RCOOH]/[H+] ≤ 1.0, and ionic strength 1.00 M.... (More)
Synopsis
Reversible formation and proton-assisted aquation of 1:1 monodentate carboxylate complexes of palladium(II) takes place via a transition state stabilized by hydrogen bonding in an activation process strongly dominated by bond making. Volume profiles have been established through high-pressure kinetic measurements.
Abstract
Abstract Image
Kinetics and equilibria for reversible formation of 1:1 monodentate complexes between Pd(H2O)42+ and acetic, propionic, and glycolic acid (RCOOH) according to the equation Pd(H2O)42+ + RCOOH ⇌ Pd(H2O)3OOCR+ + H3O+ (k1, k-1) have been studied as a function of temperature and pressure in an aqueous medium with 0.60 ≤ [H+] ≤ 1.00 M, [RCOOH]/[H+] ≤ 1.0, and ionic strength 1.00 M. Stability constants β1 for the formation of acetate, propionate, and glycolate complexes are (2.19 ± 0.09) × 104, (2.10 ± 0.24) × 104, and (6.4 ± 0.1) × 103 M-1, repectively, at 25 °C and for a 1.00 M perchlorate medium. The rate expression, kobsd = k1[RCOOH] + k-1[H+], indicates that reaction between palladium and carboxylate anions is negligible under the experimental conditions used. Values for k1/M-1 s-1, k-1/M-1 s-1, ΔH1⧧/kJ mol-1, ΔH-1⧧/kJ mol-1, ΔS1⧧/J K-1 mol-1, ΔS-1⧧/J K-1 mol-1, ΔV1⧧/cm3 mol-1, and ΔV-1⧧/cm3 mol-1 at 25.0 °C are 19.3 ± 0.6, 32.8 ± 0.2, 52.5 ± 0.4, 57.5 ± 0.4, −44 ± 1, −23 ± 1, −8.1 ± 0.3, and −1.7 ± 0.2 for acetic acid; 12.0 ± 1.1, 26.4 ± 0.3, 55.3 ± 0.6, 56.8 ± 0.3, −32 ± 2, −34 ± 1, −8.9 ± 0.8, and −1.7 ± 0.2 for propionic acid; and 21.1 ± 0.3, 13.7 ± 0.1, 53.6 ± 0.4, 59.2 ± 0.6, −40 ± 1, −25 ± 2, −3.4 ± 0.2, and −2.3 ± 0.2 for glycolic acid. There is no relation between formation rate constants and pKa for these carboxylic acids. The nucleophilic properties of the carboxylic acids toward palladium(II) are similar to those of water molecules. A trigonal bipyramidal transition state stabilized by hydrogen bonding between the entering carboxylic acid and the leaving aqua ligand or (equivalent) between the entering oxonium ion and the leaving carboxylate ligand is suggested. Negative entropies, volumes of activation, and volume profiles support a strong contribution from bond making in the activation process. (Less)
Abstract
Synopsis
Reversible formation and proton-assisted aquation of 1:1 monodentate carboxylate complexes of palladium(II) takes place via a transition state stabilized by hydrogen bonding in an activation process strongly dominated by bond making. Volume profiles have been established through high-pressure kinetic measurements.
Abstract
Kinetics and equilibria for reversible formation of 1:1 monodentate complexes between Pd(H2O)42+ and acetic, propionic, and glycolic acid (RCOOH) according to the equation Pd(H2O)42+ + RCOOH ⇌ Pd(H2O)3OOCR+ + H3O+ (k1, k-1) have been studied as a function of temperature and pressure in an aqueous medium with 0.60 ≤ [H+] ≤ 1.00 M, [RCOOH]/[H+] ≤ 1.0, and ionic strength 1.00 M. Stability constants β1... (More)
Synopsis
Reversible formation and proton-assisted aquation of 1:1 monodentate carboxylate complexes of palladium(II) takes place via a transition state stabilized by hydrogen bonding in an activation process strongly dominated by bond making. Volume profiles have been established through high-pressure kinetic measurements.
Abstract
Kinetics and equilibria for reversible formation of 1:1 monodentate complexes between Pd(H2O)42+ and acetic, propionic, and glycolic acid (RCOOH) according to the equation Pd(H2O)42+ + RCOOH ⇌ Pd(H2O)3OOCR+ + H3O+ (k1, k-1) have been studied as a function of temperature and pressure in an aqueous medium with 0.60 ≤ [H+] ≤ 1.00 M, [RCOOH]/[H+] ≤ 1.0, and ionic strength 1.00 M. Stability constants β1 for the formation of acetate, propionate, and glycolate complexes are (2.19 ± 0.09) × 104, (2.10 ± 0.24) × 104, and (6.4 ± 0.1) × 103 M-1, repectively, at 25 °C and for a 1.00 M perchlorate medium. The rate expression, kobsd = k1[RCOOH] + k-1[H+], indicates that reaction between palladium and carboxylate anions is negligible under the experimental conditions used. Values for k1/M-1 s-1, k-1/M-1 s-1, ΔH1⧧/kJ mol-1, ΔH-1⧧/kJ mol-1, ΔS1⧧/J K-1 mol-1, ΔS-1⧧/J K-1 mol-1, ΔV1⧧/cm3 mol-1, and ΔV-1⧧/cm3 mol-1 at 25.0 °C are 19.3 ± 0.6, 32.8 ± 0.2, 52.5 ± 0.4, 57.5 ± 0.4, −44 ± 1, −23 ± 1, −8.1 ± 0.3, and −1.7 ± 0.2 for acetic acid; 12.0 ± 1.1, 26.4 ± 0.3, 55.3 ± 0.6, 56.8 ± 0.3, −32 ± 2, −34 ± 1, −8.9 ± 0.8, and −1.7 ± 0.2 for propionic acid; and 21.1 ± 0.3, 13.7 ± 0.1, 53.6 ± 0.4, 59.2 ± 0.6, −40 ± 1, −25 ± 2, −3.4 ± 0.2, and −2.3 ± 0.2 for glycolic acid. There is no relation between formation rate constants and pKa for these carboxylic acids. The nucleophilic properties of the carboxylic acids toward palladium(II) are similar to those of water molecules. A trigonal bipyramidal transition state stabilized by hydrogen bonding between the entering carboxylic acid and the leaving aqua ligand or (equivalent) between the entering oxonium ion and the leaving carboxylate ligand is suggested. Negative entropies, volumes of activation, and volume profiles support a strong contribution from bond making in the activation process. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Palladium(II), Acetate, Propionate, Glycolate, Complex formation, Fast kinetics, High-pressure chemistry, Tetra aqua ion, Activation parameters, Reaction mechanism
in
Inorganic Chemistry
volume
1996
issue
35
pages
6 pages
publisher
The American Chemical Society
external identifiers
  • scopus:0000722271
ISSN
1520-510X
DOI
10.1021/ic950935u
language
English
LU publication?
yes
id
b7b23da0-f17c-4938-bc7f-fd13ecd1eb7f
date added to LUP
2017-01-04 21:39:32
date last changed
2017-07-30 05:19:54
@article{b7b23da0-f17c-4938-bc7f-fd13ecd1eb7f,
  abstract     = {Synopsis<br/>Reversible formation and proton-assisted aquation of 1:1 monodentate carboxylate complexes of palladium(II) takes place via a transition state stabilized by hydrogen bonding in an activation process strongly dominated by bond making. Volume profiles have been established through high-pressure kinetic measurements.<br/>Abstract<br/>Kinetics and equilibria for reversible formation of 1:1 monodentate complexes between Pd(H2O)42+ and acetic, propionic, and glycolic acid (RCOOH) according to the equation Pd(H2O)42+ + RCOOH ⇌ Pd(H2O)3OOCR+ + H3O+ (k1, k-1) have been studied as a function of temperature and pressure in an aqueous medium with 0.60 ≤ [H+] ≤ 1.00 M, [RCOOH]/[H+] ≤ 1.0, and ionic strength 1.00 M. Stability constants β1 for the formation of acetate, propionate, and glycolate complexes are (2.19 ± 0.09) × 104, (2.10 ± 0.24) × 104, and (6.4 ± 0.1) × 103 M-1, repectively, at 25 °C and for a 1.00 M perchlorate medium. The rate expression, kobsd = k1[RCOOH] + k-1[H+], indicates that reaction between palladium and carboxylate anions is negligible under the experimental conditions used. Values for k1/M-1 s-1, k-1/M-1 s-1, ΔH1⧧/kJ mol-1, ΔH-1⧧/kJ mol-1, ΔS1⧧/J K-1 mol-1, ΔS-1⧧/J K-1 mol-1, ΔV1⧧/cm3 mol-1, and ΔV-1⧧/cm3 mol-1 at 25.0 °C are 19.3 ± 0.6, 32.8 ± 0.2, 52.5 ± 0.4, 57.5 ± 0.4, −44 ± 1, −23 ± 1, −8.1 ± 0.3, and −1.7 ± 0.2 for acetic acid; 12.0 ± 1.1, 26.4 ± 0.3, 55.3 ± 0.6, 56.8 ± 0.3, −32 ± 2, −34 ± 1, −8.9 ± 0.8, and −1.7 ± 0.2 for propionic acid; and 21.1 ± 0.3, 13.7 ± 0.1, 53.6 ± 0.4, 59.2 ± 0.6, −40 ± 1, −25 ± 2, −3.4 ± 0.2, and −2.3 ± 0.2 for glycolic acid. There is no relation between formation rate constants and pKa for these carboxylic acids. The nucleophilic properties of the carboxylic acids toward palladium(II) are similar to those of water molecules. A trigonal bipyramidal transition state stabilized by hydrogen bonding between the entering carboxylic acid and the leaving aqua ligand or (equivalent) between the entering oxonium ion and the leaving carboxylate ligand is suggested. Negative entropies, volumes of activation, and volume profiles support a strong contribution from bond making in the activation process.},
  author       = {Shi, Tiesheng and Elding, Lars Ivar},
  issn         = {1520-510X},
  keyword      = {Palladium(II),Acetate,Propionate,Glycolate,Complex formation,Fast kinetics,High-pressure chemistry,Tetra aqua ion,Activation parameters,Reaction mechanism},
  language     = {eng},
  month        = {01},
  number       = {35},
  pages        = {735--740},
  publisher    = {The American Chemical Society},
  series       = {Inorganic Chemistry},
  title        = {Equilibrium and High-Pressure Kinetic Study of Formation and Proton-Assisted Aquation of Monodentate Acetate, Propionate, and Glycolate Complexes of Palladium(II) in Aqueous Solution},
  url          = {http://dx.doi.org/10.1021/ic950935u},
  volume       = {1996},
  year         = {1996},
}