A tin(IV)-ruthenium(II)-tin(IV) cyclic porphyrin trimer with replaceable chiral linings

A series of cyclic metalloporphyrin trimers, Ru(CO)(py)[Sn(carboxylate)2](2)2, having cavities lined with different carboxylate groups are synthesized by adding the appropriate carboxylic acids to the mixed trimer Ru(CO)(py)-[Sn(OH)2](2)2. This methodology provides ready access to a wide range of cavities lined with substituents possessing chirality or hydrogen-bonding groups. The potential of such systems is illustrated by synergistic binding of a hydroxypyridine to the Ru(II)-CO center and to the hydroxyl groups of a D-quinate-lined cavity. The effect of changing the carboxylate lining of the cavity on the course of epoxidation reactions catalyzed by these trimers is also reported.