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Homo- and copolymerization of norbornene with tridentate nickel complexes bearing o-aryloxide-N-heterocyclic carbene ligands. | LitMetric

Homo- and copolymerization of norbornene with tridentate nickel complexes bearing o-aryloxide-N-heterocyclic carbene ligands.

Dalton Trans

State Key Laboratory of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin 300071, P. R. China. and Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300071, P. R. China and State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, P. R. China.

Published: January 2018

A series of new pincer-type tridentate o-aryloxide-N-heterocyclic carbene nickel complexes Ni1-Ni3 were synthesized, and the molecular structure of Ni3 was confirmed by X-ray crystallography. In comparison with the above tridentate complexes, the bidentate bis(aryloxide-NHC) nickel complex Ni4 was also synthesized. On activation with either EtAlCl or MeAlCl, all nickel complexes showed low activity toward norbornene (NB) homopolymerization. Surprisingly, Ni1-Ni3 catalysts exhibited moderate to high activity toward the homopolymerization (up to 3.21 × 10 g PNB (mol of Ni) h) and copolymerization of norbornene with 1-octene (up to 1.39 × 10 g polymer (mol of Ni) h) with B(CF) as the cocatalyst even at 100 °C, showing that tridentate nickel catalysts have high thermal stability. Notably, the tridentate Ni1-Ni3 complexes showed better activities than the corresponding bidentate bis(aryloxide-NHC) nickel complex Ni4. The obtained poly(NB-co-1-octene)s were confirmed to be vinyl-addition copolymers, which exhibited high 1-octene insertion ratio (9%-17%), good thermal stability (T > 400 °C), high molecular weight (up to 10), and narrow molecular weight distribution (PDI ≤ 1.91).

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Source
http://dx.doi.org/10.1039/c7dt03928jDOI Listing

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