Compound I and Compound II Analogues from Porpholactones

The tetraaza macrocycles 2-oxa-3-oxotetramesitylporphine (|H2 1|) and 2-oxa-3-oxotetrakis(2,6-dichlorophenyl)porphine (|H2 2|) and the corresponding iron complexes (|FeIII(X) 1| and |FeIII(X) 2|; X= Cl-, OH-, or SO3CF3-) have been synthesized. These macrocycles are derived from porphyrins by transformation of one pyrrole ring to an oxazolone ring. The resulting lactone functionality serves to restrict but not completely block π-conjugation around the periphery. These complexes thus share properties with both porphyrins and chlorins. The ferric and high-valent iron complexes have been characterized by a variety of spectroscopic techniques. The molecular structure of |FeIII(Cl) 2| has been obtained by X-ray crystallography and shows that the structural changes at the macrocycle periphery do not perturb the coordination sphere of iron relative to the corresponding porphyrin complexes. This is illustrated by the observation that Fe−O frequencies in the resonance Raman spectra of the porpholactone analogues of...