Molecular structure, characterization and reactivity of dioxo complexes formed by vanadium(V) with alpha-hydroxycarboxylate ligands

The structure of the dioxovanadium(V) complexes of glycolic, lactic and mal ic acids Rb-2[{VO2(glyc)}(2)] [glyc = glycolato(2 - )] (1), Cs-2[{VO2(mal)} (2)] [mal = malato(2 - )] (2), and Cs-2[{VO2(lact)}(2)\.2H(2)O [lact = lact ato(2 - )] (3) has been studied by single-crystal X-ray diffraction. In ord er to assign the features of the peculiar arrangement adopted by these kind s of complexes, the metrical details of these compounds have been examined and compared to the data available in literature for analogous complexes. T he reactivity of the compounds has also been studied. In particular, the re duction of the metal ion by a biological reductant like cysteine, relevant to the role of these complexes in the constitution of the cofactor of the a ctive site of vanadium nitrogenase, has been followed by EPR spectroscopy i n an aqueous solution. In addition, the effect of peroxo complex formation on the structure of the dinuclear V2O2 cage has been analyzed by comparison with previously published results. (C) 2000 Elsevier Science B.V. All righ ts reserved.