Aluminum Complexes Containing the C–O–Al–O–C Framework as Efficient Initiators for Ring-Opening Polymerization of ε‑Caprolactone

Three aluminum complexes, LAl­(OCH2C6H4-2-NH2)2 (2), LAl­(9-OC13H9)2 (3), and LAl­(OC6H10-4-NH2)2 (4), were synthesized in good yield by reacting one equivalent of LAlH2 (1) (L = HC­(CMeNAr)2, Ar = 2,6-iPr2C6H3) with two equivalents of 2-aminobenzyl alcohol, 9-hydroxyfluorene, and trans-4-aminocyclohexanol, respectively. All complexes (2, 3, and 4) contain the C–O–Al–O–C framework. These complexes have been characterized by IR, 1H and 13C NMR, elemental analyses, and single-crystal X-ray structural analysis. Furthermore, the excellent catalytic activities of 2, 3, and 4 for ring-opening polymerization of ε-caprolactone in the presence of isopropyl alcohol were investigated.