Ringing the Changes: Effects of Heterocyclic Ring Size on Stereoselectivity in [(η-CMe)RhCl], [(η-CMe)IrCl] and [Ru(η-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 [(η-CMe)MCl] cores where M = Rh, Ir and [Ru(η-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.