Synthesis, characterization, Co–S bond reactivity of a vitamin B12 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)7C1ester](ClO4)2, from H2O to C6F5S− afforded the B12–thiolate complex. The B12–thiolate model complex was characterized by UV-vis, NMR and ESI-mass spectroscopies. The coordination of C6F5S− 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.