Coordination Selectivity in Oxovandium (IV) Complex with 7-(3, 5-Dihalo2-pyridylazo)-8-hydroxyquinoline-5-sulfonic Acid

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  • HUANG Hu
    Department of EnvironmentalS cience, Gradu a t e S choolo f Natural Sciencea nd Technology, K umamoto University;
  • ASAI Yoshifumi
    Department of Chemistry, Faculty of Science, Kumamoto University;
  • HIROHATA Masaaki
    Department of Chemistry, Faculty of Science, Kumamoto University;
  • NAKAMURA Masaaki
    Department of Chemistry, Faculty of Science, Kumamoto University;
  • KAI Fumiaki
    Department of EnvironmentalS cience, Gradu a t e S choolo f Natural Sciencea nd Technology, K umamoto University;

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Other Title
  • 7-(3,5-Dihalo-2-pyridylazo)-8-hydroxyquinoline-5-sulfonic acid のオキソバナジウム(IV)イオンに対する配位選択性
  • 7-(3,5-Dihalo-2-pyridylazo)-8-hydroxyquinoline-5-sulfonic acidのオキソバナジウム(4)イオンに対する配位選択性
  • 7 3 5 Dihalo 2 pyridylazo 8 hydroxyquin

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Description

The complexing equilibria of oxovanadium(IV) ion with the multidentate ligands, 7-(3, 5dihalo-2-pyridylazo)-8-hydroxyquinoline-5-sulfonic acid (diX-PAHQS, X=. C1, Br), which are expected to coordinate to oxovanadium(IV) ion either with N, N, O-(N-atom in pyridine ring, N-atom of adjacent one in azo group to quinolinol ring, O-atom of quinolinolate)terdentate sites or with N, O-bidentate moiety of the quinolinol, have been investigated both spectrophotometrically and polarographically focusing on the coordination selectivity of the chelate ring. The variations of the reduction potentials and electronic spectra with cornplexations are studied to see whether the azo group in the ligands participate in the cornplexations or not. The complexing equilibria of these complexes are analyzed and the stability constants of the complexes are calculated. It was found that the azo group in these ligands did not participate in the complexations, namely the complexations occurred by using only the quinolinol moiety to form stable N, O-chelate ring in lower pH ranges. On the contrary, in higher pH ranges the complexes were dissociated by the hydrolyses of the oxovanadium(IV) ion. ESR spectral data supported these results. The coordination modes of oxovanadium(IV) ion with the ligands, 2-(3, 5-d ihalo-2-py r idyl a zo)-1-h ydroxynaphthalen e-4sul f on ic acid (diX-αPANS, X=C1, Br), 1-(3, 5-dihalo-2-pyridylazo)-2-hydroxynaphthalene-6sulfonic acid (diX-βPANS, X=C1, Br) and 7-(4-X-phenylazo)-8-hydroxyquinoline-5-sulfonic acid (BAHQS for X=H and Cl-BAHQS for X=C1), are also studiedto see a role of N-atom in pyridine ring and that in quinolinol moiety.

Journal

  • NIPPON KAGAKU KAISHI

    NIPPON KAGAKU KAISHI 1990 (12), 1348-1354, 1990-12-10

    The Chemical Society of Japan

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