Complexation of thorium(IV) with desmethyldesferrithiocin

The complexation of Th(IV) with desmethyl-desferrithiocin (H2DMDFT), a deri vative of the siderophore desferrithiocin (H2DFT), was studied by potentiom etry, spec trophotometry and NMR. Three protonation constants of the ligand were determined by potentiometric titrations and H-1-NMR and assigned to t he phenolate group, the nitrogen at the hydroxypyridine ring, and the carbo xylate group. The formation constant of the 1:2 complex, Th(DMDFT)(2), was determined by absorption spectrophotometry with oxalate as a competing liga nd. A tridentate complex with Th(IV) involving the phenolate oxygen, the th iazoline nitrogen and the carboxylate group of H2DMDFT was proposed.