Abstract
The synthesis of bis(diethylamido){di(3-methylindol-2-yl)phenylmethane}titanium (1) was achieved in high yield (85%) by the treatment of 2,2′-di(3-methylindolyl)phenylmethane with Ti(NEt2)4 in toluene at reflux for 18 h. The ethylene polymerization activity of the 1/modified methylaluminoxane (MMAO) catalyst system was low (16.3 kg of polyethylene (PE)/mol of Ti•h), but pretreatment of 1 with ClSiMe3 followed by activation with MMAO improved the activity up to 154 kg of PE/mol of Ti•h. An NMR-scale reaction of 1 with ClSiMe3 in C6D6 at 80 °C for 22 h indicated the generation of an amido chlorido complex together with the formation of Et2N–SiMe3. Partial chlorination would facilitate methylation by MMAO. The polyethylenes obtained in this study are all monomodal by size exclusion chromatography and have linear structures by NMR spectroscopy. The catalyst system was also found to be active for ethylene/1-octene copolymerization (90 kg of copolymer/mol of Ti•h).
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Acknowledgements
This work was financially supported by the Foundation for Japanese Chemical Research, Hatakeyama Culture Foundation, Aomori Support Center for Industrial Promotion, and Hirosaki University Grant for Exploratory Research by Young Scientists and Newly-appointed Scientists. The authors thank Tosoh-Finechem Co., Ltd. for donating the MMAO. T.T. appreciates the Grant-in-Aid for Young Scientists (B) (No. 15K17866 and No. 17K17742) from JSPS, Nagaoka University of Technology Presidential Research Grant, The Foundation for The Promotion of Ion Engineering, LIXIL JS Foundation, and The Ogasawara Foundation for the Promotion of Science & Engineering.
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Ohta, S., Kasai, Y., Toda, T. et al. Ethylene polymerization and ethylene/1-octene copolymerization with a titanium complex supported by a bis(indolyl) ligand. Polym J 51, 345–349 (2019). https://doi.org/10.1038/s41428-018-0124-9
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DOI: https://doi.org/10.1038/s41428-018-0124-9
