Abstract: ¹¹³Cd NMR spectra have been obtained on several Cd-polyaminocarboxylic acid complexes Cd-N-(2-Hydroxycthyl) ethylene diaminetriacetate (Cd-HEDTA), Cd-1,2-Propanediaminetetraacetate (Cd-PDTA) and Cd-Diethylenetriaminepentaacetatc (Cd-DTPA). The spectra revealed that Cd-HEDTA and Cd-PDTA have the same solution structure as the Cd-EDTA. The two lines of Cd-PDTA spectrum come from its two isomers and are indicative of the existance of more strained structure having the axial CH₃ group. The large chemical shift of Cd-DTPA shows that it is seven coordinated because in that case, three nitrogen atoms rather than two are bound to Cd atom. ¹¹³Cd nuclear Ovcrhauscr effect, η, and spin lattice relaxation time were determined for Cd-DTPA and Cd-HEDTA and used in the analysis of the contribution to the relaxation mechanism from the dipolar interaction with protons.

Key words: ¹¹³Cd NMR, Polyaminocarboxylate-Cadmium complexes