A comparison between the chelating properties of some dihydroxamic acids, desferrioxamine B and acetohydroxamic acid

Etelka Farkas, Éva A. Enyedy, Hajnalka Csóka

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Abstract

The complexes of hexanedioic acid bis(3-hydroxycarbamoyl-methyl)amide (Dha1) and hexanedioic acid bis(3-hydroxycarbamoyl-propyl)amide (Dha2) with cobalt(II), nickel(II), copper(II), zinc(II), iron(III), calcium(II) and magnesium(II) have been studied by pH-metric and spectrophotometric methods. All the complexes formed with Dha2 are soluble in water, but a very insoluble complex is formed in the copper(II)-Dha1 system. Besides the 1:1 species complexes with 2:3 stoichiometry are also formed in the cobalt(II)-, nickel(II)-, zinc(II)- and iron(III)-containing systems. Dha2 generally forms more stable complexes than those of Dha1 (e.g. log β values for their iron(III) 1:1 complexes are 17.9 and 19.1, respectively). A comparison of the data with those on the complexes of a simple monohydroxamate, (acetohydroxamate, Aha), nonano-dihydroxamate (Dha3) and the natural trihydroxamate-based siderophore, desferrioxamine B (DFB) revealed that the stability sequence of the complexes is generally: DFB>Dha2≥Dha3~Dha1>Aha. The shorter but more flexible connecting chain of Dha3 results in the ca. same stability of complexes of Dha1 and Dha3. The above sequence, however, did not hold for copper(II) allowing the coordination of at most two hydroxamates and for calcium(II). In this latter case, Dha2, containing the longest connecting chain, formed the most stable complexes.

Original languageEnglish
Pages (from-to)2391-2398
Number of pages8
JournalPolyhedron
Volume18
Issue number18
DOIs
Publication statusPublished - Jul 30 1999

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Keywords

  • Acetohydroxamic acid
  • Ca(II) and Mg(II) complexes
  • Desferrioxamine B
  • Dihydroxamic acids
  • Transition metal complexes

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry
  • Materials Chemistry

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