Synthesis, characterization, Co-S bond reactivity of a vitamin B ₁₂ model complex having pentafluorophenylthiolate as an axial ligand

Heptamethyl (aquo)(pentafluorophenylthiolate)cobyrinate perchlorate, [(H₂O)(C₆F₅S)Cob(iii)7C₁ester] ClO₄, was synthesized as a B₁₂ model complex having a thiolate ligand in the axial position. The axial ligand change in heptamethyl (diaquo)cobyrinate diperchlorate, [(H₂O)₂Cob(iii)7C ₁ester](ClO₄)₂, from H₂O to C ₆F₅S^- afforded the B₁₂-thiolate complex. The B₁₂-thiolate model complex was characterized by UV-vis, NMR and ESI-mass spectroscopies. The coordination of C₆F ₅S^- to the cobalt center affected the spectroscopic properties of the corrin ring through the electronic interaction between the axial ligand (C₆F₅S^-) and the equatorial ligand (corrin). The photolysis of the B₁₂-thiolate model complex led to the homolytic cleavage of the Co(iii)-S bond to form the Co(ii) complex and the phenyl thiyl radical. The thermolysis of the B₁₂-thiolate model complex also led to the homolytic cleavage of the Co(iii)-S bond. Furthermore, the reactivity of the Co(iii)-S bond of the B₁₂-thiolate model complex was applied to the catalytic oxidation of C₆F₅SH to C₆F₅S-SC₆F₅.