Thermodynamic and spectroscopic studies of cadmium(II)–N-(phosphonomethyl)glycine (PMG) complexes
2004 (English)In: Inorganica Chimica Acta, ISSN 0020-1693, E-ISSN 1873-3255, Vol. 357, no 4, 1185-1192 p.Article in journal (Refereed) Published
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 °C. Formation constants for a series of mononuclear complexes, CdHL, CdL−, CdL2 4− and CdL(OH)2− were determined from potentiometric titrations. The structures of the predominating species CdL−, and CdL2 4− 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 Cd9(PMG)6(H2O)12 · 6H2O 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.
Speciation and equilibria in the H+–Cd2+–N-(phosphonomethyl)glycine (PMG, H3L) system have been studied using potentiometry, and formation constants for CdHL, CdL−, CdL2 4− and CdL(OH)2− were determined. The structures of CdL−, and CdL2 4− in solution were investigated using EXAFS and IR spectroscopic techniques. The results indicated chelating PMG molecules forming two 5-membered chelate rings.
Place, publisher, year, edition, pages
Elsevier , 2004. Vol. 357, no 4, 1185-1192 p.
IdentifiersURN: urn:nbn:se:umu:diva-2219DOI: doi:10.1016/j.ica.2003.10.029OAI: oai:DiVA.org:umu-2219DiVA: diva2:140115