BINUCLEAR CHELATES OF DIETHYLENETRIAMINEPENTAACETIC ACID WITH CHROMIUM(III) AND OXOVANADIUM(IV) IONS

The reactions of diethylenetriaminepentaacetic acid (DTPA=H(5)L) or ch romium(III)-DTPA, a 'chelating agent', with oxovanadium(IV) were inves tigated in aqueous solution by potentiometric methods. Homo- and heter o-binuclear species were evidenced as well as mixed complexes with hyd rogen or hydroxide ions. The stability constants for these equilibria were calculated in 1.0 mol l(-1) NaClO4 solution at 20 degrees C. The mononuclear (VO)H(3)L . H2O and the heterobinuclear (VO)CrL . 5H(2)O c omplexes were also obtained as solid compounds and were characterized by IR spectroscopy and thermoanalytical techniques (TG and DSC).