Ringing the Changes: Effects of Heterocyclic Ring Size on Stereoselectivity in [(η5-C5Me5)RhCl], [(η5-C5Me5)IrCl] and [Ru(η6-cymene)Cl] Complexes of Chiral 3-Amino-1-Azacycles

Ring size-dependent diastereoselective coordination of unsymmetrical diamines containing one azacyclic nitrogen and one exocyclic nitrogen to [(η5-C5Me5MCl]+ cores where M = Rh, Ir and [Ru(η6-cymene)Cl]+ is reported herein. Total stereoselectivity was observed with the six- and seven-membered azacycles, whereas the five derivative proved poorly selective. All complexes were active for transfer hydrogenation but showed no enantioselectivity with prochiral ketones.