Hydrophobic vitamin B₁₂. Part 20: Supernucleophilicity of Co(I) heptamethyl cobyrinate toward various organic halides

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, CHCl ₃, CCl₄, CHBrCl₂, CHBr₃, CCl ₃CH₃, CFCl₃, and BrCH₂CH ₂CH₃, 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.