Synthesis and Properties of Organocobalt(III)octaethylporphyrins

Abstract

Abstract The syntheses of alkylcobalt(III)octaethylporphyrins(OEP) via nucleophilic attack of the Co(I) complex to unsaturated compounds are reported. Olefins with an electron-withdrawing group and acetylenes react with Co(I)(OEP), whereas olefins with an electron-donating group such as propylene and cyclohexene are unreactive. A novel ring cleavage of cyclopropyl methy ketone initiated by Co(I)(OEP) affords alkylCo(III)(OEP). The reduction of cobalt(II) N-methyloctaethylporphyrin acetate results in intramolecular methyl migration from nitrogen to the central cobalt atom. Five-coordination has been established for the organocobalt(III)(OEP) complexes on the basis of their analytical, infrared and NMR data. Some anomalous behavior of the proton signals of the α-carbon atom in their NMR spectra has been discussed in terms of quadrupolar relaxation and electronegativity of the cobalt ion.