Aluminum Complexes with Bidentate N,N‐Dialkylaniline–arylamido Ligands: Synthesis, Structures, and Catalytic Properties for Efficient Ring‐Opening Polymerization of ϵ‐Caprolactone

Abstract

AbstractA number of Al complexes bearing bidentate N,N‐dialkylaniline–arylamido ligands, ortho‐(ArNCH2)C6H4NR2AlMe2 (R = Me, Ar = 2,6‐iPr2C6H3, 3a; 2,6‐Et2C6H3, 3b; 2,6‐Me2C6H3, 3c; 4‐MeC6H4, 3d; Ph, 3e; and R = Et, Ar = 2,6‐iPr2C6H3, 3f; 2,6‐Me2C6H3, 3g; Ph, 3h), have been synthesized from the reaction of the corresponding free ligands, ortho‐(ArNHCH2)C6H4NR2 (R = Me, Ar = 2,6‐iPr2C6H3, 2a; 2,6‐Et2C6H3, 2b; 2,6‐Me2C6H3, 2c; 4‐MeC6H4, 2d; Ph, 2e; and R = Et, Ar = 2,6‐iPr2C6H3, 2f; 2,6‐Me2C6H3, 2g; Ph, 2h), with AlMe3 (1 equiv.). All complexes were characterized by 1H and 13C NMR spectroscopy and elemental analysis. Single‐crystal X‐ray diffraction analysis of complexes 3c and 3e revealed that these Al complexes have a distorted tetrahedral geometry around the metal center. All complexes were found to be efficient catalysts for the ring‐opening polymerization of ϵ‐caprolactone (CL) in the presence of benzyl alcohol, and complexes 3a–h catalyze the polymerization of CL in a living fashion. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)