ISSN:
1040-0397
Keywords:
Speciation
;
DPP
;
Polarographic complex formation curves
;
Labile metal complexes
;
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The ligand N-(2-hydroxyethyl)ethylenediamine (HEEN) was studied with CdII by differential pulse polarography (DPP) at fixed total ligand (LT) to total metal (MT) concentration ratios and varied pH at 25°C and an ionic strength μ = 0.5 mol dm-3. The polarographic experimental complex formation curve (ECFC) and calculated complex formation curve (CCFC) were used for modeling of the metal-ligand system and the refinement of stability constants. The ECFC, in which experimental parameters of polarographic peaks are included (a shift in a peak potential and a variation in a peak height) appears to be a characteristic function for a particular metal-ligand system studied at a particular LT : MT ratio. The CCFC is a theoretical curve calculated for the assumed metal-ligand model from mass-balance equations. The final model of metal species formed is the one for which the CCFC fits best the ECFC. Four cadmium complexes CdL2+, CdL22+, CdL32+, and CdL2 (OH)+ and their stability constants as log β found from DPP 5.08 ± 0.03, 9.44 ± 0.04, 11.25 ± 0.05, 12.06 ± 0.03, respectively, are reported. The complex CdL32+ was found for the first time. Results obtained in this work are compared with literature data.
Additional Material:
5 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/elan.1140091507
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