CATALYTIC REACTION ON BOTH SIDES OF A METALLOPORPHYRIN PLANE - ALTERNATING COPOLYMERIZATION OF PHTHALIC-ANHYDRIDE AND EPOXYPROPANE WITH AN ALUMINUM PORPHYRIN QUATERNARY SALT SYSTEM

The first example of the catalytic reaction occurring simultaneously on both sides of a metalloporphyrin plane was demonstrated in the copolymerization of phthalic anhydride and 1,2-epoxypropane by using the system of aluminum porphyrin coupled with quaternary ammonium or phosphonium salt as catalyst, to afford the copolymer with a highly regulated structure as to the sequence (alternating) and the number of the repeating units. The anion of the quaternary organic salt is activated as nucleophile by the metalloporphyrin, and the structure of the active growing species was confirmed by detailed spectroscopic investigations to be a novel six-coordinate aluminum porphyrin carrying one reactive axial ligand on both sides respectively of its square-planar N//4Al skeleton.