The Preparation of Protoheme Mono-N-[5-(2-methyl-1-imidazolyl)pentyl]amide and Its Oxygenation

Iron(II)protoporphyrin IX N-[5-(2-methyl-1-imidazolyl)pentyl]amide ethyl ester (1) and its derivatives (2–4) were prepared. They predominantly form pentacoordinate heme complexes in organic and aqueous solutions, based on their 2-methylimidazole-ligand and spacer N-pentylamide groups. Oxygen adducts of 1–4 were rapidly formed on exposure to oxygen in N,N-dimethylformamide (DMF) at −30 °C, and their life-times were more than 30 min.