Titanium, aluminum and zinc complexes containing diamine-bis(benzotriazole phenolate) ligands: Synthesis, structural characterization and catalytic studies for ring-opening polymerization of ε-caprolactone

Publication date: 15 April 2017
Source:Journal of Molecular Structure, Volume 1134
Author(s): Zheng-Tang Liu, Chen-Yu Li, Jhy-Der Chen, Wan-Ling Liu, Chen-Yen Tsai, Bao-Tsan Ko
Structurally diverse metal complexes bearing diamine-bis(benzotriazole phenolate) (DiBTP) ligands have been synthesized and fully characterized by single crystal X-ray crystallography. The reaction of Ti(OⁱPr)4 with ^C8MEADiBTP-H2 or ^C8BEADiBTP-H2 (1.0 mol equiv.) generated the monomeric titanium alkoxy complexes [(^C8MEADiBTP)Ti(OⁱPr)2] (1) and [(^C8BEADiBTP)Ti(OⁱPr)2] (2), respectively. Moreover, ^C8BEADiBTP-H2 reacted with 2.0 molar equiv. of AlMe3 to give the tetra-coordinated di-aluminum complex [(^C8BEADiBTP)Al2Me4] (3). Zinc complex [(^C8BEADiBTP)Zn2Et2] (4) could be obtained by the alkane elimination of ZnEt2 (2.0 equiv.) with ^C8BEADiBTP-H2 as the pro-ligand under similar synthetic methods in good yield. Single-crystal X-ray diffraction indicates that 3 is a bimetallic aluminum dimethyl complex with a tetradentate ^C8BEADiBTP moiety chelating two metal atoms, whereas complex 4 displays the dinuclear feature containing both tetra- and penta-coordinated zinc atoms bonded by one ONNON-pentadentate ^C8BEADiBTP ligand. Catalytic studies for ring-opening polymerization of ε-caprolactone of complex 1–4 were systematic explored; the comparative studies of such polymerization were also discussed.

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