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Li Y, Bao J, Liu Q, Tse MK, Chan MCW. Bis-[C(sp 3)-chelating] Ti 2 catalysts supported by arylene-1,4-diyl-2,3-X 2 bridges for olefin copolymerisation: X substituents impose conformational cooperative effects. Dalton Trans 2024; 53:14391-14398. [PMID: 39136437 DOI: 10.1039/d4dt02006e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/28/2024]
Abstract
The synthesis, spectroscopic characterisation and catalytic olefin polymerisation behaviour of a class of binuclear titanium bis(benzyl) complexes bearing bis-(pyridine-2-phenolate-6-methine)-[μ-(arylene-1,4-diyl-2,3-X2)] ligands [X2 = -C4H4- (1), F2 (2), H2 (3)], and mononuclear analogues, are described. These bimetallic catalyst frameworks are designed to exhibit a degree of conformational flexibility, which is regulated by steric effects and crucially permits tuning of intermetallic distances and geometry, yet their shape-persistent nature can also confer favourable entropic terms. Complexes 1-3 are characterised as two diastereomers [meso (RS) and rac (RR,SS)] in ratios of 1.32, 1.18 and 1.13 respectively, according to 1H NMR spectroscopy. In contrast to 3, [1H,1H]-ROESY experiments for 1 and 2 revealed that the X2 substituents can impose preferred conformations with syn orientations of Ti2 centres and benzyl groups, thus implying that the activated catalysts would present binding sites with the same direction of access. For ethylene-(1-octene) copolymerisation reactions, in conjunction with [Ph3C][B(C6F5)4], catalyst 1 displayed superior efficiencies and produced polymers with higher Mw values and enhanced comonomer incorporation ratios (up to 41%), when compared with the mononuclear 5m (22%). These results are indicative of enhanced comonomer enchainment and cooperative reactivity by the Ti2 sites.
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Affiliation(s)
- Yufang Li
- Department of Chemistry and Department of Materials Science and Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China.
| | - Junhui Bao
- Department of Chemistry and Department of Materials Science and Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China.
| | - Qian Liu
- Department of Chemistry and Department of Materials Science and Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China.
| | - Man-Kit Tse
- Department of Chemistry and Department of Materials Science and Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China.
| | - Michael C W Chan
- Department of Chemistry and Department of Materials Science and Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China.
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Liu J, Zhang J, Sun M, Li H, Lei M, Huang Q. Ethylene/Polar Monomer Copolymerization by [N, P] Ti Complexes: Polar Copolymers with Ultrahigh-Molecular Weight. ACS OMEGA 2024; 9:15030-15039. [PMID: 38585117 PMCID: PMC10993284 DOI: 10.1021/acsomega.3c09124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Revised: 03/09/2024] [Accepted: 03/11/2024] [Indexed: 04/09/2024]
Abstract
A series of novel titanium complexes (2a-2e) bearing [N, P] aniline-chlorodiphenylphosphine ligands (1a-1e) featuring CH3 and F substituents have been synthesized and characterized. Surprisingly, in the presence of polar additive, the complexes (2a-2e) all displayed high catalytic activities (up to 1.04 × 106 gPolymer (mol·Ti)-1·h-1 and produced copolymer with the ultrahigh molecular weight up to 1.37 × 106 g/mol. The catalytic activities are significantly enhanced by introducing electron-withdrawing group (F) into the aniline aromatic ring. Especially, the increase in activity based on different complexes followed the order of 2e > 2d > 2c > 2b > 2a. Simultaneously, density functional theory (DFT) calculations have been performed to probe the polymerization mechanism as well as the electronic and steric effects of various substituents on the catalyst backbone. DFT computation revealed that the polymerization behaviors could be adjusted by the electronic effect of ligand substituents; however, it has little to do with the steric hindrance of the substituents. Furthermore, theoretical calculation results keep well in accordance with experimental measurement results. The article provided an appealing design method that the employment of fluorine atom as electron-withdrawing to be studied is the promotive effect of transition-metal coordination polymerization.
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Affiliation(s)
- Jingjiao Liu
- State
Key Laboratory of Chemical Resource Engineering, Key Laboratory of
Carbon Fiber and Functional Polymers, College of Material Science
and Technology, Beijing University of Chemical
Technology, Beijing 100029, P. R. China
| | - Jiaojiao Zhang
- State
Key Laboratory of Chemical Resource Engineering, Key Laboratory of
Carbon Fiber and Functional Polymers, College of Material Science
and Technology, Beijing University of Chemical
Technology, Beijing 100029, P. R. China
| | - Min Sun
- The
State Key Laboratory of Catalytic Materials and Reaction Engineering
(RIPP, SINPPEC), Beijing 100083, P. R. China
| | - Hongming Li
- Petrochemical
Research Institute, PetroChina, Beijing 102206, P. R. China
| | - Ming Lei
- College
of Chemistry, Beijing University of Chemical
Technology, Beijing 100029, P. R. China
| | - Qigu Huang
- State
Key Laboratory of Chemical Resource Engineering, Key Laboratory of
Carbon Fiber and Functional Polymers, College of Material Science
and Technology, Beijing University of Chemical
Technology, Beijing 100029, P. R. China
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Li Y, Liu Q, Bao J, Yiu SM, Chan MCW. Coplanar binuclear group 4 post-metallocene complexes supported by chelating μ-(σ 2-aryl) ligands: characterisation and olefin polymerisation catalysis. Dalton Trans 2023; 53:346-353. [PMID: 38050668 DOI: 10.1039/d3dt03641c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/06/2023]
Abstract
The report concerns expansion of the previously developed M-[O,N,C] [pyridine-2-phenolate-6-(σ-aryl)] catalyst system into rigid, coplanar bimetallic assemblies, which afford metal-metal distances that are predetermined yet amenable for cooperativity, as well as locked-in "syn" orientation of binding sites that offer the same direction of access for substrates. The binuclear complexes are generated in a regioselective manner to yield para hydrogen atoms (not ortho) at the central μ-aryl moiety, and have been characterised by multinuclear NMR spectroscopy. The "anti" (showing opposite directions of access) and mononuclear analogues have also been prepared for comparison purposes. Six syn-type bimetallic derivatives of Ti, Zr and Hf have been characterised by X-ray crystallography, to reveal metal-metal separations of 6.3-6.7 Å. For ethylene and ethylene/1-octene polymerisation reactions in conjunction with trityl borate, the syn-Ti2 catalysts display superior efficiencies and produced polymers with higher Mw values than for the anti and mono-Ti congeners, thus indicating the possibility of favourable enchainment interactions and cooperative reactivity.
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Affiliation(s)
- Yufang Li
- Department of Chemistry and Department of Materials Science and Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China.
| | - Qian Liu
- Department of Chemistry and Department of Materials Science and Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China.
| | - Junhui Bao
- Department of Chemistry and Department of Materials Science and Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China.
| | - Shek-Man Yiu
- Department of Chemistry and Department of Materials Science and Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China.
| | - Michael C W Chan
- Department of Chemistry and Department of Materials Science and Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China.
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Yu S, Zhang C, Wang F, Liang X, Yang M, An M. Promotion of B(C 6F 5) 3 as Ligand for Titanium (or Vanadium) Catalysts in the Copolymerization of Ethylene and 1-Hexene: A Computational Study. Polymers (Basel) 2023; 15:polym15112435. [PMID: 37299237 DOI: 10.3390/polym15112435] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Revised: 05/21/2023] [Accepted: 05/23/2023] [Indexed: 06/12/2023] Open
Abstract
Density functional theory (DFT) is employed to investigate the promotion of B(C6F5)3 as a ligand for titanium (or vanadium) catalysts in ethylene/1-hexene copolymerization reactions. The results reveal that (I) Ethylene insertion into TiB (with B(C6F5)3 as a ligand ) is preferred over TiH, both thermodynamically and kinetically. (II) In TiH and TiB catalysts, the 2,1 insertion reaction (TiH21 and TiB21) is the primary pathway for 1-hexene insertion. Furthermore, the 1-hexene insertion reaction for TiB21 is favored over TiH21 and is easier to perform. Consequently, the entire ethylene and 1-hexene insertion reaction proceeds smoothly using the TiB catalyst to yield the final product. (III) Analogous to the Ti catalyst case, VB (with B(C6F5)3 as a ligand) is preferred over VH for the entire ethylene/1-hexene copolymerization reaction. Moreover, VB exhibits higher reaction activity than TiB, thus agreeing with experimental results. Additionally, the electron localization function and global reactivity index analysis indicate that titanium (or vanadium) catalysts with B(C6F5)3 as a ligand exhibit higher reactivity. Investigating the promotion of B(C6F5)3 as a ligand for titanium (or vanadium) catalysts in ethylene/1-hexene copolymerization reactions will aid in designing novel catalysts and lead to more cost-effective polymerization production methods.
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Affiliation(s)
- Shuyuan Yu
- College of Chemistry and Material Science, Langfang Normal University, Langfang 065000, China
| | - Chenggen Zhang
- College of Chemistry and Material Science, Langfang Normal University, Langfang 065000, China
| | - Fei Wang
- College of Chemistry and Material Science, Langfang Normal University, Langfang 065000, China
| | - Xinru Liang
- College of Chemistry and Material Science, Langfang Normal University, Langfang 065000, China
| | - Mengyao Yang
- College of Chemistry and Material Science, Langfang Normal University, Langfang 065000, China
| | - Mengyu An
- College of Chemistry and Material Science, Langfang Normal University, Langfang 065000, China
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Half-sandwich chromium(III) complexes containing salicylbenzoxazole and salicylbenzothiazole ligands for ethylene polymerization. INORG CHEM COMMUN 2021. [DOI: 10.1016/j.inoche.2021.108885] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Carvalho RL, de Miranda AS, Nunes MP, Gomes RS, Jardim GAM, Júnior ENDS. On the application of 3d metals for C-H activation toward bioactive compounds: The key step for the synthesis of silver bullets. Beilstein J Org Chem 2021; 17:1849-1938. [PMID: 34386103 PMCID: PMC8329403 DOI: 10.3762/bjoc.17.126] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Accepted: 06/28/2021] [Indexed: 01/24/2023] Open
Abstract
Several valuable biologically active molecules can be obtained through C-H activation processes. However, the use of expensive and not readily accessible catalysts complicates the process of pharmacological application of these compounds. A plausible way to overcome this issue is developing and using cheaper, more accessible, and equally effective catalysts. First-row transition (3d) metals have shown to be important catalysts in this matter. This review summarizes the use of 3d metal catalysts in C-H activation processes to obtain potentially (or proved) biologically active compounds.
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Affiliation(s)
- Renato L Carvalho
- Institute of Exact Sciences, Department of Chemistry, Federal University of Minas Gerais - UFMG, CEP 31270-901, Belo Horizonte, MG, Brazil
| | - Amanda S de Miranda
- Institute of Exact Sciences, Department of Chemistry, Federal University of Minas Gerais - UFMG, CEP 31270-901, Belo Horizonte, MG, Brazil
| | - Mateus P Nunes
- Institute of Exact Sciences, Department of Chemistry, Federal University of Minas Gerais - UFMG, CEP 31270-901, Belo Horizonte, MG, Brazil
| | - Roberto S Gomes
- Department of Pharmaceutical Sciences, North Dakota State University, Fargo, ND, United States
| | - Guilherme A M Jardim
- Institute of Exact Sciences, Department of Chemistry, Federal University of Minas Gerais - UFMG, CEP 31270-901, Belo Horizonte, MG, Brazil
- Centre for Excellence for Research in Sustainable Chemistry (CERSusChem), Department of Chemistry, Federal University of São Carlos – UFSCar, CEP 13565-905, São Carlos, SP, Brazil
| | - Eufrânio N da Silva Júnior
- Institute of Exact Sciences, Department of Chemistry, Federal University of Minas Gerais - UFMG, CEP 31270-901, Belo Horizonte, MG, Brazil
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