Dimethylaluminum complexes bearing a chiral diketiminate ligand: Synthesis, characterization and ring-opening polymerization of ε-caprolactone

Reaction of the chiral aliphatic N-substituted diketiminate ligand, N,N'-Di(R-phenylethyl)-2-amino-4-iminopent-2-ene (R,R-nacnac(CH(Me)Ph)H), with AlMe3 affords the monomeric dimethylaluminum complex R,R-nacnac(CH(Me)Ph)AlMe(2) (R,R-1). Complex S,S-nacnac(CH(i-Pr)Ph)AlMe(2) (S,S-2) is prepared by S,S-nacnac(CH(i-Pr)Ph)H and AlMe3. Complexes R,R-1 and S,S-2 are the first examples of chiral beta-diketiminate ligands with main group metals. All these two complexes exhibit activity for the ring-opening polymerization of epsilon-caprolactone in the absence of alcohol, and complex R,R-1 shows a higher activity with a narrow molecular weight distribution (PDI = 1.17) in toluene. (C) 2012 Elsevier B.V. All rights reserved.