2019
DOI: 10.3390/polym11071093
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Preparation of Half- and Post-Metallocene Hafnium Complexes with Tetrahydroquinoline and Tetrahydrophenanthroline Frameworks for Olefin Polymerization

Abstract: Hafnium complexes have drawn attention for their application as post-metallocene catalysts with unique performance in olefin polymerization. In this work, a series of half-metallocene HfMe2 complexes, bearing a tetrahydroquinoline framework, as well as a series of [Namido,N,Caryl]HfMe2-type post-metallocene complexes, bearing a tetrahydrophenanthroline framework, were prepared; the structures of the prepared Hf complexes were unambiguously confirmed by X-ray crystallography. When the prepared complexes were re… Show more

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Cited by 5 publications
(8 citation statements)
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“…(Polyolefinyl) 2 Zn was prepared via coordinative chain transfer copolymerizations (CCTcoPs) performed using a pyridylamidohafnium catalyst (1 in Scheme 1) in methylcyclohexane at high temperatures of 90-110 • C by feeding ethylene/propylene mixed gases. Catalyst 1 is the best in performing CCTcoPs [22,33,[41][42][43]. It undergoes fast alkyl exchange with Zn sites to generate PO chains with a narrow molecular weight distribution [21,44].…”
Section: Attempts To Synthesize Block Copolymersmentioning
confidence: 99%
“…(Polyolefinyl) 2 Zn was prepared via coordinative chain transfer copolymerizations (CCTcoPs) performed using a pyridylamidohafnium catalyst (1 in Scheme 1) in methylcyclohexane at high temperatures of 90-110 • C by feeding ethylene/propylene mixed gases. Catalyst 1 is the best in performing CCTcoPs [22,33,[41][42][43]. It undergoes fast alkyl exchange with Zn sites to generate PO chains with a narrow molecular weight distribution [21,44].…”
Section: Attempts To Synthesize Block Copolymersmentioning
confidence: 99%
“…The prepared complexes along with comparison compound I were screened using 1.0 µmol of the Hf complex as a catalyst and 150 µmol of (hexyl) 2 Zn as a chain transfer agent under identical conditions after Hf complexes were activated with anhydrous [(C 18 H 37 ) 2 N(H)Me] + [B(C 6 F 5 ) 4 ] − [5,7,28]. Catalysts derived from 19 and 20 bearing the 2-iPrC 6 H 4 C(H)-moiety and a cycloheptyl or cyclohexyl substituent survived for longer periods than did the catalyst derived from I, as was expected, and, consequently, those complexes (19 and 20) manifested somewhat higher activity than I did (10 vs. 8.5 g).…”
Section: Polymerization Experimentsmentioning
confidence: 99%
“…A representative flagship catalyst among postmetallocenes is a pyridylamido hafnium complex (I in Scheme 1) discovered by high-throughput screening in the early 2000s [1][2][3][4]. It shows advantageous performance in ethylene and α-olefin (co)polymerization reactions, though its activation reaction is rather tricky [5][6][7]. In ethylene/α-olefin copolymerization reactions, it is capable of incorporating a large amount of α-olefins (uniquely among Hf catalysts) [8,9].…”
Section: Introductionmentioning
confidence: 99%
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“…Activated complexes generated with [Me(C 18 H 37 ) 2 N-H] + [B(C 6 F 5 ) 4 ] − may be soluble and stable through the coordination of Me(C 18 H 37 ) 2 N (a byproduct generated in the activation reaction) with the metal center (i.e., formation of [ L -M(Me)(NMe(C 18 H 37 ) 2 )] + [B(C 6 F 5 ) 4 ] − -type species; Scheme 1 c) [ 35 , 36 ]. However, [Me(C 18 H 37 ) 2 N-H] + [B(C 6 F 5 ) 4 ] − is highly soluble, cannot be purified by recrystallization, and is contaminated with either water or Cl − salt impurities, which interfere with the activation reaction [ 37 ]. In this work, we report on a method to prepare high-purity trialkylammonium tetrakis(pentafluorophenyl)borate in an aliphatic hydrocarbon solvent and the activation reactions of some typical metallocene and half-metallocene complexes.…”
Section: Introductionmentioning
confidence: 99%