Preparation of “Constrained Geometry” Titanium Complexes of [1,2]Azasilinane Framework for Ethylene/1-Octene Copolymerization

Lee, Seul; Park, Seung Soo; Kim, Jin Gu; Kim, Chung Sol; Lee, Hyun Ju

doi:10.3390/molecules22020258

Cited by 14 publications

(9 citation statements)

References 56 publications

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“…The ligand-metal interaction is tight and inflexible, which confers high stability. For homogeneous olefin polymerization, the initial zirconium (Zr)-based metallocene catalysts were followed by titanium (Ti)-based half-metallocenes and subsequently post-metallocenes with non-cyclopentadienyl ligands [3,4,5,6,7,8,9]. Among the post-metallocenes that have been developed, a pincer-type [C naphthyl , N pyridine , N amido ]HfMe 2 complex is a flagship catalyst.…”

Section: Introductionmentioning

confidence: 99%

Preparation of Pincer Hafnium Complexes for Olefin Polymerization

et al. 2019

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Pincer-type [Cnaphthyl, Npyridine, Namido]HfMe2 complex is a flagship among the post-metallocene catalysts. In this work, various pincer-type Hf-complexes were prepared for olefin polymerization. Pincer-type [Namido, Npyridine, Namido]HfMe2 complexes were prepared by reacting in situ generated HfMe4 with the corresponding ligand precursors, and the structure of a complex bearing 2,6-Et2C6H3Namido moieties was confirmed by X-ray crystallography. When the ligand precursors of [(CH3)R2Si-C5H3N-C(H)PhN(H)Ar (R = Me or Ph, Ar = 2,6-diisopropylphenyl) were treated with in situ generated HfMe4, pincer-type [Csilylmethyl, Npyridine, Namido]HfMe2 complexes were afforded by formation of Hf-CH2Si bond. Pincer-type [Cnaphthyl, Sthiophene, Namido]HfMe2 complex, where the pyridine moiety in the flagship catalyst was replaced with a thiophene unit, was not generated when the corresponding ligand precursor was treated with HfMe4. Instead, the [Sthiophene, Namido]HfMe3-type complex was obtained with no formation of the Hf-Cnaphthyl bond. A series of pincer-type [Cnaphthyl, Npyridine, Nalkylamido]HfMe2 complexes was prepared where the arylamido moiety in the flagship catalyst was replaced with alkylamido moieties (alkyl = iPr, cyclohexyl, tBu, adamantyl). Structures of the complexes bearing isopropylamido and adamantylamido moieties were confirmed by X-ray crystallography. Most of the complexes cleanly generated the desired ion-pair complexes when treated with an equivalent amount of [(C18H37)2N(H)Me]+[B(C6F5)4]−, which showed negligible activity in olefin polymerization. Some complexes bearing bulky substituents showed moderate activities, even though the desired ion-pair complexes were not cleanly afforded.

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Section: Introductionmentioning

confidence: 99%

Preparation of Pincer Hafnium Complexes for Olefin Polymerization

et al. 2019

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“…From a typical CGC [ 5 -Ti(CH 2 N(C 18 H 37 ) 2 )] + [B(C 6 F 5 ) 4 ] − , polymers with b-modal-molecular-weight distributions were also generated ( M w / M n , 13 and 7.3) with M w values of 150 and 100 kDa (entries 5 and 6). However, a polymer with relatively narrow and unimodal-molecular-weight distribution was generated with [ 5 -TiCl(N(H)(C 18 H 37 ) 2 )] + [B(C 6 F 5 ) 4 ] − ( M w , 210, M w / M n , 3.6) (entry 7), which might be attributed to relatively lower polymerization temperature (90–115 °C); it has been known that the typical CGC 5 -Ti species did not exhibit thermal stability above 110 °C [ 27 ]. In contrast, half-metallocene 6 -Ti and 7 -Ti species generated polymers with unimodal-molecular-weight distributions in all cases even when polymerization temperature exceeded 120 °C ( M w , 210–340 kDa; M w / M n , 2.3–3.5) (entries 8–15).…”

Section: Resultsmentioning

confidence: 99%

“…However, [PhN(Me) 2 -H] + [B(C 6 F 5 ) 4 ] − and [Ph 3 C] + [B(C 6 F 5 ) 4 ] − are either completely insoluble or sparingly soluble, respectively, in toluene [ 26 ], which still requires an excess amount (e.g., 4 equiv.) to achieve optimal productivity [ 27 , 28 , 29 ]. For a typical post-metallocene pyridylamido-Hf complex, the activation reaction was thoroughly investigated, and was more complicated than previously thought [ 30 , 31 , 32 ].…”

Section: Introductionmentioning

confidence: 99%

Preparation of High-Purity Ammonium Tetrakis(pentafluorophenyl)borate for the Activation of Olefin Polymerization Catalysts

et al. 2021

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Homogeneous olefin polymerization catalysts are activated in situ with a co-catalyst ([PhN(Me)2-H]+[B(C6F5)4]− or [Ph3C]+[B(C6F5)4]−) in bulk polymerization media. These co-catalysts are insoluble in hydrocarbon solvents, requiring excess co-catalyst (>3 eq). Feeding the activated species as a solution in an aliphatic hydrocarbon solvent may be advantageous over the in situ activation method. In this study, highly pure and soluble ammonium tetrakis(pentafluorophenyl)borates ([Me(C18H37)2N-H]+[B(C6F5)4]− and [(C18H37)2NH2]+[B(C6F5)4]−) containing neither water nor Cl− salt impurities were prepared easily via the acid–base reaction of [PhN(Me)2-H]+[B(C6F5)4]− and the corresponding amine. Using the prepared ammonium salts, the activation reactions of commercial-process-relevant metallocene (rac-[ethylenebis(tetrahydroindenyl)]Zr(Me)2 (1-ZrMe2), [Ph2C(Cp)(3,6-tBu2Flu)]Hf(Me)2 (3-HfMe2), [Ph2C(Cp)(2,7-tBu2Flu)]Hf(Me)2 (4-HfMe2)) and half-metallocene complexes ([(h5-Me4C5)Si(Me)2(k-NtBu)]Ti(Me)2 (5-TiMe2), [(h5-Me4C5)(C9H9(k-N))]Ti(Me)2 (6-TiMe2), and [(h5-Me3C7H1S)(C10H11(k-N))]Ti(Me)2 (7-TiMe2)) were monitored in C6D12 with 1H NMR spectroscopy. Stable [L-M(Me)(NMe(C18H37)2)]+[B(C6F5)4]− species were cleanly generated from 1-ZrMe2, 3-HfMe2, and 4-HfMe2, while the species types generated from 5-TiMe2, 6-TiMe2, and 7-TiMe2 were unstable for subsequent transformation to other species (presumably, [L-Ti(CH2N(C18H37)2)]+[B(C6F5)4]−-type species). [L-TiCl(N(H)(C18H37)2)]+[B(C6F5)4]−-type species were also prepared from 5-TiCl(Me) and 6-TiCl(Me), which were newly prepared in this study. The prepared [L-M(Me)(NMe(C18H37)2)]+[B(C6F5)4]−-, [L-Ti(CH2N(C18H37)2)]+[B(C6F5)4]−-, and [L-TiCl(N(H)(C18H37)2)]+[B(C6F5)4]−-type species, which are soluble and stable in aliphatic hydrocarbon solvents, were highly active in ethylene/1-octene copolymerization performed in aliphatic hydrocarbon solvents.

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“…The use of homogeneous single-site catalysts originated with the serendipitous discovery of methylaluminoxane (MAO) by Kaminsky [1]. The initial Zr-based metallocene catalysts, Ti-based half-metallocenes, and post-metallocenes with non-cyclopentadienyl ligands, were developed successively (Scheme 1) [2,3]. A typical example of half-metallocenes is [Me 2 Si(η 5 -Me 4 C 5 )(N t Bu)]TiCl 2 , which was discovered in the early 1990s at Dow ( II Scheme 1) [4].…”

Section: Introductionmentioning

confidence: 99%

Preparation of Half- and Post-Metallocene Hafnium Complexes with Tetrahydroquinoline and Tetrahydrophenanthroline Frameworks for Olefin Polymerization

et al. 2019

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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 reacted with anhydrous [(C18H37)2N(H)Me]+[B(C6F5)4]−, desired ion-pair complexes, in which (C18H37)2NMe coordinated to the Hf center, were cleanly afforded. The activated complexes generated from the half-metallocene complexes were inactive for the copolymerization of ethylene/propylene, while those generated from post-metallocene complexes were active. Complex bearing bulky isopropyl substituents (12) exhibited the highest activity. However, the activity was approximately half that of the prototype pyridylamido-Hf Dow catalyst. The comonomer incorporation capability was also inferior to that of the pyridylamido-Hf Dow catalyst. However, 12 performed well in the coordinative chain transfer polymerization performed in the presence of (octyl)2Zn, converting all the fed (octyl)2Zn to (polyolefinyl)2Zn with controlled lengths of the polyolefinyl chain.

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Preparation of “Constrained Geometry” Titanium Complexes of [1,2]Azasilinane Framework for Ethylene/1-Octene Copolymerization

Cited by 14 publications

References 56 publications

Preparation of Pincer Hafnium Complexes for Olefin Polymerization

Preparation of Pincer Hafnium Complexes for Olefin Polymerization

Preparation of High-Purity Ammonium Tetrakis(pentafluorophenyl)borate for the Activation of Olefin Polymerization Catalysts

Preparation of Half- and Post-Metallocene Hafnium Complexes with Tetrahydroquinoline and Tetrahydrophenanthroline Frameworks for Olefin Polymerization

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