Synthesis, structural characterization and reactivity of aluminium complexes supported by benzotriazole phenoxide ligands: Air-stable alumoxane as an efficient catalyst for ring-opening polymerization of l-lactide

Chen Yu Li, Chen Yen Tsai, Chia Her Lin, Bao Tsan Ko*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

44 Citations (Scopus)

Abstract

Aluminium complexes bearing sterically bulky benzotriazole-phenoxide ligands are synthesized and characterized structurally. The reaction of 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol ( CMe2PhBTP-H) or 2-(2H-benzotriazol-2-yl)-4,6-di-tert-butylphenol (t-BuBTP-H) with AlMe3 (1.2 molar equiv.) in toluene yields [(CMe2PhBTP)AlMe2] (1) or [(t-BuBTP) AlMe2] (2) as a four-coordinated monomeric aluminium complex. Compound 1 reacts further with CMe2PhBTP-H in a stoichiometric proportion, affording penta-coordinated monomeric aluminium methyl complex [(CMe2PhBTP)2AlMe] (3). Complex 3 is also obtained directly upon treatment of AlMe3 with CMe2PhBTP-H (two molar equiv.) in refluxing toluene in high yield. In the presence of H 2O (half a molar equiv.), hydrolysis of 3 in a mixed solvent of THF and toluene at ambient temperature affords [{(CMe2PhBTP) 2Al}2(μ-O)] (4), in which the oxo ligand acts as a chelating group linearly bridging two aluminium centers. Air-stable alumoxane 4 is an efficient catalyst for the ring-opening polymerization of l-lactide (l-LA) in the presence of 9-anthracenemethanol (9-AnOH). Complex 4 catalyzes the polymerization of l-LA in a controlled manner, yielding PLLAs with the expected molecular weights and narrow polydispersity indices (PDIs).

Original languageEnglish
Pages (from-to)1880-1887
Number of pages8
JournalDalton Transactions
Volume40
Issue number9
DOIs
Publication statusPublished - 2011 Mar 7
Externally publishedYes

ASJC Scopus subject areas

  • Inorganic Chemistry

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