Synthesis, characterization, and lactide polymerization activity of group 4 metal complexes containing two bis(phenolate) ligands

Inorganic Chemistry
Andreas SauerJun Okuda

Abstract

A series of group 4 metal complexes Zr-(1)(2), Zr-(2)(2), Zr-(3)(2), Zr-(4)(2), Zr-(5)(2), Hf-(1)(2), and Hf-(4)(2) containing two bridged bis(phenolate) ligands of the (OSSO)-type were prepared by the reaction of the corresponding bis(phenol) and group 4 metal precursor MX(4) (X = O(i)Pr, CH(2)Ph) and isolated as robust, colorless crystals. NMR spectra indicate D(2) symmetry, in agreement with the solid state structure determined by single crystal X-ray diffraction study of the complexes Zr-(1)(2), Hf-(1)(2), Zr-(3)(2), Zr-(4)(2), and Zr-(5)(2). The complexes with the 1,4-dithiabutanediyl bridged ligands exhibit a highly symmetric coordination around the metal center. The introduction of the rigid trans-1,2-cyclohexanediyl bridged ligands led to a distorted coordination around the metal center in Zr-(4)(2) and Zr-(5)(2) when the ortho substituent is tert-butyl and the para substituent is larger than methyl. The complexes Zr-(1)(2), Zr-(2)(2), Zr-(3)(2), Zr-(4)(2) as well as Hf-(1)(2) and Hf-(4)(2) initiated the ring-opening polymerization of meso-lactide at 100 °C to give heterotactic polylactide with pronounced heterotacticity (>70%) and varying polydispersity (1.05 < M(w)/M(n) < 1.61). As shown by kinetic studies, zirconium ...Continue Reading

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Citations

Sep 22, 2015·Journal of the American Chemical Society·Jian-Bo Zhu, Eugene Y-X Chen
Mar 8, 2017·Inorganic Chemistry·Rosita LapentaCarmine Capacchione
Sep 11, 2012·Dalton Transactions : an International Journal of Inorganic Chemistry·Fabio MarchettiSirpa Vuorinen
May 6, 2017·Dalton Transactions : an International Journal of Inorganic Chemistry·Antonio OteroAna M Rodríguez
Dec 13, 2019·Dalton Transactions : an International Journal of Inorganic Chemistry·Swarup GhoshStephan Schulz
Apr 5, 2013·Dalton Transactions : an International Journal of Inorganic Chemistry·Andreas SauerJun Okuda
Feb 2, 2019·Accounts of Chemical Research·Junnian Wei, Paula L Diaconescu

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