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Thermodynamic and spectroscopic studies of cadmium(II)-N-(phosphonomethyl)glycine (PMG) complexes

Author:
  • M. Ramstedt
  • C. Norgren
  • J. Sheals
  • D. Bostrom
  • S. Sjoberg
  • Per Persson
Publishing year: 2004
Language: English
Pages: 1185-1192
Publication/Series: Inorganica Chimica Acta
Volume: 357
Document type: Journal article
Publisher: Elsevier
Additional info: 4

Abstract english

Speciation and equilibria in the H+-Cd2+-N-(phosphonomethyl)glycine (PMG, H3L) system have been studied in 0.1 M Na(Cl) medium at 25.0 degreesC. Formation constants for a series of mononuclear complexes, CdHL, CdL-, CdL24- and CdL(OH)(2)- were determined from potentiometric titrations. The structures of the predominating species CdL-, and CdL24- in solution were investigated using EXAFS and IR spectroscopic techniques. In the 1:1 complex bonds are formed between the Cd(II) ion and all three donor groups (amino, carboxylate, phosphonate) of the PMG molecule resulting in two 5-membered chelate rings. At the remaining three of the corners of the distorted Cd(II) octahedra oxygens were found which are replaced by donor groups of a second PMG molecule in the 1:2 complex. Furthermore, a solid phase consisting of Cd-9(PMG)(6)(H2O)(12) (.) 6H(2)O crystals was synthesized and the crystal structure was determined. The structure consists of six CdL- octahedra connected through a seventh Cd-O octahedron in the centre of the entity, with two additional Cd-O octahedra located at the apices of the unit formed. (C) 2003 Elsevier B.V. All rights reserved.

Keywords

  • Earth and Related Environmental Sciences

Other

Published
  • ISSN: 0020-1693
Per Persson
E-mail: per [dot] persson [at] biol [dot] lu [dot] se

Professor

MEMEG

+46 46 222 17 96

+46 70 266 38 79

E-C350

50

Professor

Centre for Environmental and Climate Research (CEC)

+46 46 222 17 96

+46 70 266 38 79

D350

Ekologihuset, Sölvegatan 37, Lund

50