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Copper(II), nickel(II), zinc(II), and molybdenum(VI) complexes of desferrioxamine B in aqueous solution

1997; Elsevier BV; Volume: 65; Issue: 4 Linguagem: Inglês

10.1016/s0162-0134(96)00144-4

1873-3344

Etelka Farkas, Hajnalka Csóka, Giovanni Micera, Alessandro Dessì,

Radioactive element chemistry and processing

Based on pH-metric, spectrophotometric, and EPR measurements, stability constants and bonding modes are reported for the complexes formed in aqueous solutions of the copper(II)-, nickel(II)-, zinc(II)-, and molybdenum(VI)-desferrioxamine B (DFA) systems. Besides the totally deprotonated species, several protonated mononuclear complexes were found in the copper(II)-, nickel(II)-, and zinc(II)-DFA systems, and also the dinuclear species [Cu2AH]2+. All three hydroxamate groups are able to coordinate to nickel(II) and zinc(II), but only two of them to the copper(II). Molybdenum(VI) yields only one complex species, [MoO2(H2DFA)]+. This species, which exists below pH 7, involves two hydroxamate groups coordinated to the metal ion. DFA completely prevents the formation of polyoxomolybdates below pH 7, but MoO42− and free DFA exist above this pH.