The Spectroscopic Properties and Organometallic Reactivities of Cobalt(III) Porphyrins

Article abstract of DOI:10.1246/bcsj.65.639

Chlorocobalt(III) porphyrins showed novel UV-vis and 1H NMR spectra in a non-coordinating solvent to suggest displacement of the cobalt out of the porphyrin plane toward the axial ligand in solution.They underwent insertion of alkynes into the Co-Cl bond to generate ?-(trans-2-chlorovinyl)cobalt(III) complexes.In a special case, novel <4+2>cycloaddition reaction between the Co-N-C(pyrrole-α)-C(meso) moiety of IIICl(oep)> and dimethyl acetylenedicarboxylate took place.The reaction behavior of chlorocobalt(III)porphyrins was compared with that of diaquaperchloratocobalt(III) porphyrins which also reacted with alkynes in the presence of 2,6-lutidine to give analogous ?-vinylcobalt(III) porphyrins with a 2,6-dimethyl-1-pyridinio substituent occupying the trans-β-position of the ?-vinyl group.While the methoxycarbonyl group of methyl propiolate was directed to the α side of these ?-vinylcobalt(III) complexes, the phenyl group of phenylacetylene was found to be directed to the α side of ?-(2-chlorovinyl)cobalt(III) porphyrin and to the β side of ?-<2-(2,6-dimethyl-1-pyridinio)vinyl>cobalt(III) porphyrin.