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Equilibria, Kinetics and Mechanism for Complex Formation Between Hydrogen Sulfate/Sulfate and Palladium(II). Hydrolysis of Tetraaquapalladium(II)

Shi, Tiesheng LU and Elding, Lars Ivar LU (1998) In Acta Chemica Scandinavica 52 (1998). p.897-902
Abstract
Spectrophotometric equilibrium measurements indicate formation of the complexes [Pd(H2O)(3)HSO4](+) and [Pd(H2O)(3)SO4] in the reaction between [Pd(H2O)(4)](2+) and hydrogen sulfate/sulfate in the region: 0.10 less than or equal to [H+] less than or equal to 0.80 M. The stability constants are 0.7 +/- 0.2 and 19 +/- 6 M-1, respectively, at 25 degrees C and 1.00 M ionic strength. The protolysis constant for coordinated hydrogen sulfate, i.e. the equilibrium constant for the reaction [Pd(H2O)(3)HSO4](+) +H2O reversible arrow[Pd(H2O)(3)SO4] + H3O+, is 2.5 +/- 1.0 M. The stability constant for [Pd(H2O)(3)HSO4](+) and the protolysis constant for coordinated HSO4- are also derived from kinetic measurements as 0.6 +/- 0.2 M-1 and 2.3 +/- 1.3 M,... (More)
Spectrophotometric equilibrium measurements indicate formation of the complexes [Pd(H2O)(3)HSO4](+) and [Pd(H2O)(3)SO4] in the reaction between [Pd(H2O)(4)](2+) and hydrogen sulfate/sulfate in the region: 0.10 less than or equal to [H+] less than or equal to 0.80 M. The stability constants are 0.7 +/- 0.2 and 19 +/- 6 M-1, respectively, at 25 degrees C and 1.00 M ionic strength. The protolysis constant for coordinated hydrogen sulfate, i.e. the equilibrium constant for the reaction [Pd(H2O)(3)HSO4](+) +H2O reversible arrow[Pd(H2O)(3)SO4] + H3O+, is 2.5 +/- 1.0 M. The stability constant for [Pd(H2O)(3)HSO4](+) and the protolysis constant for coordinated HSO4- are also derived from kinetic measurements as 0.6 +/- 0.2 M-1 and 2.3 +/- 1.3 M, respectively. The kinetics for the reversible complex formation reaction, studied by use of stopped-flow spectrophotometry, is first order with respect to palladium complex and total concentration of sulfate, [S(VI)], with an observed pseudo-first-order rate constant k(obsd) = k(f)[S(VI)] + k(r) for excess sulfate. Here k(f) and k(r) denote observed forward second-order and reverse first-order rate constants, respectively. The kinetic data are interpreted in terms of a reaction mechanism which involves parallel and reversible reactions between [Pd(H2O)(4)](2+) and HSO4- and SO42-, respectively, and between [Pd(H2O)(3)OH](+) and HSO4-. Forward and reverse rate constants for complex formation between [Pd(H2O)(4)](2+) and HSO4- are 119 +/- 6 M-1 s(-1) and 210 +/- 60 s(-1) at 25 degrees C, indicating that HSO4- has a similar nucleophilicity as other oxygen-donor ligands. The rate constants for the reactions of [Pd(H2O)(4)](2+) with SO42- and of [Pd(H2O)(3)OH](+) with HSO4- cannot be resolved because of a proton ambiguity. The mononuclear protolysis constant of [Pd(H2O)(4)](2+) is pK(h) = 3.0 +/- 0.1 at 25 degrees C and 1.00 M ionic strength as determined from rapid spectrophotometric equilibrium measurements.
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Contribution to journal
publication status
published
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keywords
Palladium(II), Tetraaquapalladium(II), Hydrolysis, Complex formation, Sulfate, Palladium(II) tetraaqua ion, Protolysis constant, Sulfate, Complex formation, Kinetics, Reaction mechanism, Tetraaqua ion
in
Acta Chemica Scandinavica
volume
52 (1998)
pages
6 pages
publisher
Munksgaard International Publishers
external identifiers
  • scopus:0001259235
ISSN
0904-213X
DOI
10.3891/acta.chem.scand.52-0897
language
English
LU publication?
yes
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d0b3ed6d-d91a-4659-bcbe-cfe3d36ed6d5
date added to LUP
2016-12-27 20:41:53
date last changed
2017-03-20 20:55:09
@article{d0b3ed6d-d91a-4659-bcbe-cfe3d36ed6d5,
  abstract     = {Spectrophotometric equilibrium measurements indicate formation of the complexes [Pd(H2O)(3)HSO4](+) and [Pd(H2O)(3)SO4] in the reaction between [Pd(H2O)(4)](2+) and hydrogen sulfate/sulfate in the region: 0.10 less than or equal to [H+] less than or equal to 0.80 M. The stability constants are 0.7 +/- 0.2 and 19 +/- 6 M-1, respectively, at 25 degrees C and 1.00 M ionic strength. The protolysis constant for coordinated hydrogen sulfate, i.e. the equilibrium constant for the reaction [Pd(H2O)(3)HSO4](+) +H2O reversible arrow[Pd(H2O)(3)SO4] + H3O+, is 2.5 +/- 1.0 M. The stability constant for [Pd(H2O)(3)HSO4](+) and the protolysis constant for coordinated HSO4- are also derived from kinetic measurements as 0.6 +/- 0.2 M-1 and 2.3 +/- 1.3 M, respectively. The kinetics for the reversible complex formation reaction, studied by use of stopped-flow spectrophotometry, is first order with respect to palladium complex and total concentration of sulfate, [S(VI)], with an observed pseudo-first-order rate constant k(obsd) = k(f)[S(VI)] + k(r) for excess sulfate. Here k(f) and k(r) denote observed forward second-order and reverse first-order rate constants, respectively. The kinetic data are interpreted in terms of a reaction mechanism which involves parallel and reversible reactions between [Pd(H2O)(4)](2+) and HSO4- and SO42-, respectively, and between [Pd(H2O)(3)OH](+) and HSO4-. Forward and reverse rate constants for complex formation between [Pd(H2O)(4)](2+) and HSO4- are 119 +/- 6 M-1 s(-1) and 210 +/- 60 s(-1) at 25 degrees C, indicating that HSO4- has a similar nucleophilicity as other oxygen-donor ligands. The rate constants for the reactions of [Pd(H2O)(4)](2+) with SO42- and of [Pd(H2O)(3)OH](+) with HSO4- cannot be resolved because of a proton ambiguity. The mononuclear protolysis constant of [Pd(H2O)(4)](2+) is pK(h) = 3.0 +/- 0.1 at 25 degrees C and 1.00 M ionic strength as determined from rapid spectrophotometric equilibrium measurements.<br/> },
  author       = {Shi, Tiesheng and Elding, Lars Ivar},
  issn         = {0904-213X},
  keyword      = {Palladium(II),Tetraaquapalladium(II),Hydrolysis,Complex formation,Sulfate,Palladium(II) tetraaqua ion,Protolysis constant,Sulfate,Complex formation,Kinetics,Reaction mechanism,Tetraaqua ion},
  language     = {eng},
  pages        = {897--902},
  publisher    = {Munksgaard International Publishers},
  series       = {Acta Chemica Scandinavica},
  title        = {Equilibria, Kinetics and Mechanism for Complex Formation Between Hydrogen Sulfate/Sulfate and Palladium(II). Hydrolysis of Tetraaquapalladium(II)},
  url          = {http://dx.doi.org/10.3891/acta.chem.scand.52-0897},
  volume       = {52 (1998)},
  year         = {1998},
}