Protonation effects on dynamic flux properties of aqueous metal complexes

H.P. van Leeuwen, R.M. Town

Research output: Contribution to journalArticleAcademicpeer-review

7 Citations (Scopus)

Abstract

The degree of (de)protonation of aqueous metal species has significant consequences for the kinetics of complex formation/dissociation. All protonated forms of both the ligand and the hydrated central metal ion contribute to the rate of complex formation to an extent weighted by the pertaining outer-sphere stabilities. Likewise, the lifetime of the uncomplexed metal is determined by all the various protonated ligand species. Therefore, the interfacial reaction layer thickness, µ, and the ensuing kinetic flux, Jkin, are more involved than in the conventional case. All inner-sphere complexes contribute to the overall rate of dissociation, as weighted by their respective rate constants for dissociation, kd. The presence of inner-sphere deprotonated H2O, or of outer-sphere protonated ligand, generally has a great impact on kd of the inner-sphere complex. Consequently, the overall flux can be dominated by a species that is a minor component of the bulk speciation. The concepts are shown to provide a good description of experimental stripping chronopotentiometric data for several protonated metal–ligand systems
Original languageEnglish
Pages (from-to)1543-1557
JournalCollection of Czechoslovak Chemical Communications
Volume74
Issue number10
DOIs
Publication statusPublished - 2009

Keywords

  • deposition potential sscp
  • reaction layer approximation
  • stripping chronopotentiometry
  • hydrolytic tendencies
  • speciation analysis
  • ligand protonation
  • chelate compounds
  • water exchange
  • voltammetric lability
  • perchlorate solution

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