STUDY ON COENZYME B-12 MODEL COMPOUNDS BY ELECTROCHEMISTRY AND QUANTUM-CHEMISTRY

It is now widely recognized that coenzyme B-12-dependent rearrangement s are caused by homolytic dissociation of the Co-C bond giving rise to a 5'-deoxyadenosyl radical. The Co-C bonding strength is related to t he electronic and steric effect of the 5'-deoxyadenosyl radical and th e axial organic base, playing a key role in the catalytic cycle. To cl arify the mechanism of Co-C bond breaking in coenzyme B-12, many exper imental and theoretic researches on B-12 Model compounds have been con ducted, especially on the effect of electronic and steric perturbation of axial group. In this article we study the B-12 compounds from the angle of electrochemistry and investigate the interaction between the axial ester group and porphyrin ring system from the angle of quantum chemistry.