The stereoselectivity of bipyrrolidine-based sequential polydentate ligands around Ru(II)

The Ru(II) coordination chemistry of the sequential hexadentate, tetradentate and the novel hybrid pentadentate ligands assembled around the chiral bipyrrolidine core and including bipyridyl and pyridyl periphery units is described. The bipyridine group exhibited priority in binding over the bipyrrolidine group, which led to a diastereomer mixture in the case of the hexadentate ligand 1. Employing only monopyridyl or a combination of monopyridyl and bipyridyl peripheral groups restored the chiral induction ability to the bipyrrolidine core resulting in predetermined chiral-at-metal complexes for the ligands 3 and 4.