ABSTRACT
This paper reports on a binuclear Co(ii)Pc which exhibits a previously unknown extremely high catalytic activity for the oxidation of a thiol to the corresponding disulfide. The high activity is explained by an electronic contact between the two Co centres in the complex.
Subject(s)
Coordination Complexes/chemistry , Indoles/chemistry , Sulfhydryl Compounds/chemistry , Catalysis , Cobalt/chemistry , Isoindoles , Models, Chemical , Oxidation-ReductionABSTRACT
The electrochemical characteristics of 2-mono(2,6-diisopropylphenylimino)acenaphthene-1-one (dpp-mian) have been investigated. One-electron reduction of dpp-mian involves the iminoketone fragment, which is revealed by the EPR spectrum obtained after the electrolysis of the dpp-mian solution in tetrahydrofuran (THF). The reduction of dpp-mian with one equivalent of metallic potassium leads to a similar EPR spectrum. The sodium complex [(dpp-mian)Na(dme)]2 (1) produces an EPR signal with hyperfine coupling on the nitrogen atom of the iminoketone fragment of the dpp-mian ligand. Dpp-mian can also be reduced in a one-electron process by SnCl2 ×(dioxane). In this case, complex (dpp-mian)2 SnCl2 (2) is formed, with the tin atom displaying an oxidation state of +4. Tin(II) chloride dihydrate, SnCl2 ×2(H2 O), also reduces dpp-mian, but the two ligands bound to tin in the product form a new carbon-carbon bond between the ketone moieties of the dpp-mian monoanions to form complex (bis-dpp-mian)HSnCl3 (3). Metallic tin reduces dpp-mian to form the (bis-dpp-mian)2 Sn (4) species. Compounds 1-4 were characterized by X-ray diffraction.
ABSTRACT
Ligand-oxidized annulated dinuclear phthalocyanine zinc(II) and lithium(I) complexes absorbing in the NIR region (lambda=1000-2200 nm) with high extinction coefficients are described. Analogous mononuclear Pc complexes were used for comparison. The oxidized Pcs were characterized in solution by electronic absorption, EPR and NMR spectra. The NIR transitions were explained by using MO diagrams calculated semiempirically. The reversible oxidation behavior of the phthalocyanine complexes was also estimated by cyclic voltammetry. These new extremely long wavelength absorbing phthalocyanines are interesting as materials with new electronic properties.
