UNUSUAL METALLOPORPHYRINS VIII: Synthesis of Ruthenium Mesoporphyrin IX Dimethylester Carbonyl and its Imidazole Derivatives; Observation of a new type of Tautaumerism—Metal Shuttling

Ruthenium (II) porphyrin complexes have been made with mesoporphyrin IX dimethyl ester and tetraphenylporphine in which one axial position is occupied by a carbonyl group. The other axial position is shown to be either occupied by a loosely bound ligand or entirely empty. The imidazole,4,5-dimethylimidazole, and 3,5-dimethylpyrazole complexes of the mesoporphyrin complex, I, are made. Variable temperature pmr studies on the imidazole and 3,5-dimethylimidazole complexes show the metal nitrogen bond to be moving rapidly between the two imidazole nitrogens at high temperatures.