ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 40, Number 1
JKCSEZ 40(1)
February 20, 1996 

The cadmium(Ⅱ)-carboxylate complexes of monocarboxylates and poly(acrylic acid) (PAA) in an aqueous solution were investigated using 113Cd NMR spectroscopy. From these spectral data the chemical shifts of the monocarboxylate (e.g. acetate, benzoate and propanoate) complexes of Cd(Ⅱ) were evaluated (CdL+: -22 to -24 ppm range; CdL2: -39 to -40 ppm range; L: carboxylate). The chemical shift of cadmium(Ⅱ) bound on PAA changed in value from -36.6 to -38.2 ppm when the [PAA]/[Cd] ratios were varied from 12 to 118 eq/mol at a constant pH of 6. The 113Cd chemical shift was sensitive to the change in solution pH: the chemical shift changed from 1.6 to -37.6 ppm when the pH was rasied from 1 to 6 at a constant [PAA]/[Cd] ratio of 39 eq/mol. These results show that under these conditions, the dominant species formed in solution is 1 : 2 complex (CdL2), and 1 : 1 complex (CdL+) is only formed at low pH, when polyanion concentration is low.