Redox chemistry of 1,2-dihydroxynaphthalene, 1,2-naphthosemiquinone and 1,2-naphthoquinone and their complexes with manganese(II) and manganese(III)

Bodini M.E.; Arancibia, V

Abstract

Cyclic voltammetry and controlled-potential electrolyses were carried out on solutions of 1,2-naphthoquinone (1,2-NQ), 1,2-dihydroxynaphthalene [1,2-Di(OH)-Cat] and their reduction and oxidation products in dimethyl sulfoxide. A study of the interaction of these species with MnII and MnIII has been undertaken. The complexes MnIII(Cat2-)33-, MnII(Cat2-)22- and MnII-(Cat2-), where Cat2- represents the dianion of 1,2-dihydroxynaphthalene, were obtained in solution and the species MnIISQ has been detected only on the surface of the electrode. An attempt to obtain the latter complex quantitatively caused intramolecular charge-transfer yielding the more stable MnIII-catechol complex. The MnIII-semiquinone complex is unstable and the ligand is easily oxidized. The charge-transfer reaction between MnIII(Cat2-)33- and MnII(Cat2-)22- is observed at -0.54/-0.52 V versus s.c.e. whereas the MnII complexes are reduced beyond the electrochemical window (at a potential more negative than -2.00 V versus s.c.e). On the other hand, all these species are destroyed when the coordinated ligand is oxidized. U.V.-vis. spectroscopy and magnetic susceptibility measurements were performed on the compounds in solution in order to characterize and to confirm the oxidation states of the metal ion in the species.

Más información

Título de la Revista: TRANSITION METAL CHEMISTRY
Volumen: 22
Número: 2
Editorial: Springer
Fecha de publicación: 1997
Página de inicio: 150
Página final: 155
URL: http://www.scopus.com/inward/record.url?eid=2-s2.0-0039911929&partnerID=q2rCbXpz