Hydrophobic Vitamin B12. Part 20: Supernucleophilicity of Co(I) Heptamethyl Cobyrinate toward Various Organic Halides

  • Hisashi Shimakoshi
    Department of Chemistry and Biochemistry, Graduate School of Engineering, Kyushu University
  • Yasunori Maeyama
    Department of Chemistry and Biochemistry, Graduate School of Engineering, Kyushu University
  • Takeshi Kaieda
    Department of Chemistry and Biochemistry, Graduate School of Engineering, Kyushu University
  • Takashi Matsuo
    Department of Chemistry and Biochemistry, Graduate School of Engineering, Kyushu University
  • Eiki Matsui
    Institute for Materials Chemistry and Engineering, Kyushu University
  • Yoshinori Naruta
    Institute for Materials Chemistry and Engineering, Kyushu University
  • Yoshio Hisaeda
    Department of Chemistry and Biochemistry, Graduate School of Engineering, Kyushu University

Abstract

<jats:title>Abstract</jats:title> <jats:p>Heptamethyl cobyrinate, hydrophobic vitamin B12, was reduced to its Co(I) species by a reaction with sodium tetrahydroborate, which reacted with various organic halides, such as CH2Cl2, CHCl3, CCl4, CHBrCl2, CHBr3, CCl3CH3, CFCl3, and BrCH2CH2CH3, to form the corresponding alkylated complexes with dehalogenation. The alkylated complexes were characterized by elemental analyses and ESI-MS, and the photo-lability of the alkylated complexes was confirmed by the UV–vis absorption spectral change. The fashion for cleavage of the cobalt–carbon bond under irradiation with visible light was investigated by an ESR spin-trapping technique. The redox behavior of a series of alkylated complexes was investigated by cyclic voltammetry. The alkylated complexes showed an irreversible reduction peak at −1.21 to −1.29 V vs Ag–AgCl, which showed cleavage of the cobalt–carbon bond by electrolysis.</jats:p>

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