1
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Yousuf N, Ma Y, Mahmood Q, Zhang W, Wang Y, Saeed H, Sun WH. Enhancing isoprene polymerization with high activity and adjustable monomer enchainment using cyclooctyl-fused iminopyridine iron precatalysts. Dalton Trans 2024; 53:753-764. [PMID: 38086665 DOI: 10.1039/d3dt03674j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2024]
Abstract
In this study, a series of structurally rigid cyclooctyl-fused iminopyridine iron complexes, [L2FeCl][FeCl4] and [2L3Fe][Cl][3FeCl4], was synthesized via a one-pot method and investigated as precatalysts in conjunction with methylaluminoxane for isoprene (Ip) polymerization. Combined characterization through FTIR analysis, elemental analysis and single crystal XRD analysis fully verified the structure of these complexes. The most active iron complex, FeH, exhibited a trisligated nature, with its cation adopting an octahedral geometry around the metal center. In contrast, all the other iron complexes (Fe2Me, Fe2Et, Fe2iPr, Fe3Me, Fe2Et,Me) displayed bisligated configurations, with distorted trigonal bipyramidal geometry of cations. During isoprene polymerization, the extent of steric hindrance of the ligand framework exerted a significant impact on catalytic performance. The FeH precatalyst with less steric hindrance demonstrated excellent performance, producing high molecular weight polyisoprenes with conversions exceeding 99% for 4000 equiv. of monomer. Even at very low catalyst loadings, as low as 0.0025 mol% (Fe/Ip), the polymerization of isoprene could proceed smoothly with an exceptionally high activity of 4.0 × 106 gPI (molFe, h)-1. Moreover, this precatalyst exhibited good thermal stability, maintaining high activity levels (typically 105 gPI (molFe, h)-1) across a broad temperature range from -20 °C to 100 °C. Additionally, by adjusting steric substituents and the reaction temperature, the 1,4/3,4 regioselectivity could be modulated from 9/91 to 69/31 while maintaining a high stereoselectivity of cis-1,4 structures (cis/trans: >99/1).
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Affiliation(s)
- Nighat Yousuf
- Key Laboratory of Engineering Plastics and Beijing National Laboratory for Molecular Science, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
- Chemistry and Chemical Engineering Guangdong Laboratory, Shantou 515031, China.
- CAS Research/Education Center for Excellence in Molecular Sciences and International School, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yanping Ma
- Key Laboratory of Engineering Plastics and Beijing National Laboratory for Molecular Science, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
| | - Qaiser Mahmood
- Chemistry and Chemical Engineering Guangdong Laboratory, Shantou 515031, China.
| | - Wenjuan Zhang
- Beijing Key Laboratory of Clothing Materials R&D and Assessment, School of Materials Science and Engineering, Beijing Institute of Fashion Technology, Beijing 100029, China.
| | - Yizhou Wang
- Key Laboratory of Engineering Plastics and Beijing National Laboratory for Molecular Science, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
- CAS Research/Education Center for Excellence in Molecular Sciences and International School, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Hassan Saeed
- Key Laboratory of Engineering Plastics and Beijing National Laboratory for Molecular Science, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
- Chemistry and Chemical Engineering Guangdong Laboratory, Shantou 515031, China.
- CAS Research/Education Center for Excellence in Molecular Sciences and International School, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wen-Hua Sun
- Key Laboratory of Engineering Plastics and Beijing National Laboratory for Molecular Science, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
- Chemistry and Chemical Engineering Guangdong Laboratory, Shantou 515031, China.
- CAS Research/Education Center for Excellence in Molecular Sciences and International School, University of Chinese Academy of Sciences, Beijing 100049, China
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2
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Fu Y, Tang J, Hua J. Ultrahigh activity and broad temperature resistance of amine-imine cobalt precatalysts for butadiene polymerization. Dalton Trans 2023; 52:13146-13153. [PMID: 37655753 DOI: 10.1039/d3dt02460a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
Abstract
A series of amine-imine cobalt complexes (Co1-Co7) has been prepared and characterized. The complexes Co3, Co4, and Co6 have a distorted tetrahedral geometry, as determined by single crystal X-ray diffraction. In the presence of ethylaluminum sesquichloride (EASC), Co3 exhibited ultra-high activity toward butadiene (Bd) polymerization (up to 7813 kgpolymer mol-1 h-1). The activity is higher than any yet recorded for which yield high cis-1,4 polybutadiene by the well-defined late-transition metal catalytic system. The catalyst also exhibited excellent tolerance towards the ratio of Co/Bd and broad temperature stability. At a ratio of Bd/Co3 = 50 000, the complexes Co1-3 can afford polybutadiene with yields higher than 96% within 2 hours. At -20 °C to 100 °C, the complex Co3 afforded relatively high polymer yields at low catalyst concentrations (Bd/Co3 = 25 000). In addition, all polymers showed a relatively high molecular weight (up to 1.06 × 106 g mol-1).
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Affiliation(s)
- Yuan Fu
- Key Laboratory of Rubber-Plastics, Ministry of Education/Shandong Provincial Key Laboratory of Rubber-Plastics, Qingdao University of Science and Technology, Qingdao 266042, P.R. China.
| | - Jian Tang
- Key Laboratory of Rubber-Plastics, Ministry of Education/Shandong Provincial Key Laboratory of Rubber-Plastics, Qingdao University of Science and Technology, Qingdao 266042, P.R. China.
| | - Jing Hua
- Key Laboratory of Rubber-Plastics, Ministry of Education/Shandong Provincial Key Laboratory of Rubber-Plastics, Qingdao University of Science and Technology, Qingdao 266042, P.R. China.
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3
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Kirchhecker S, Nguyen N, Reichert S, Lützow K, Eselem Bungu PS, Jacobi von Wangelin A, Sandl S, Neffe AT. Iron(ii) carboxylates and simple carboxamides: an inexpensive and modular catalyst system for the synthesis of PLLA and PLLA-PCL block copolymers. RSC Adv 2023; 13:17102-17113. [PMID: 37293470 PMCID: PMC10244980 DOI: 10.1039/d3ra03112h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Accepted: 05/30/2023] [Indexed: 06/10/2023] Open
Abstract
The combination of inexpensive Fe(ii) acetate with low molecular weight aliphatic carboxamides in situ generates an effective catalyst system for the ring opening polymerisation of lactones. PLLAs were produced in melt conditions with molar masses of up to 15 kg mol-1, narrow dispersity (Đ = 1.03), and without racemisation. The catalytic system was investigated in detail with regard to Fe(ii) source, and steric and electronic effects of the amide's substituents. Furthermore, the synthesis of PLLA-PCL block copolymers of very low randomness was achieved. This commercially available, inexpensive, modular, and user-friendly catalyst mixture may be suitable for polymers with biomedical applications.
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Affiliation(s)
- Sarah Kirchhecker
- Institute of Active Polymers, Helmholtz-Zentrum Hereon Kantstr. 55 14513 Teltow Germany
| | - Ngoc Nguyen
- Institute for Technical and Macromolecular Chemistry, University of Hamburg Bundesstrasse 55 20146 Hamburg Germany
| | - Stefan Reichert
- Department of Chemistry, University of Hamburg Martin-Luther-King-Platz 6 20146 Hamburg Germany
| | - Karola Lützow
- Institute of Active Polymers, Helmholtz-Zentrum Hereon Kantstr. 55 14513 Teltow Germany
| | - Paul S Eselem Bungu
- Institute of Active Polymers, Helmholtz-Zentrum Hereon Kantstr. 55 14513 Teltow Germany
| | | | - Sebastian Sandl
- Department of Chemistry, University of Hamburg Martin-Luther-King-Platz 6 20146 Hamburg Germany
| | - Axel T Neffe
- Institute of Active Polymers, Helmholtz-Zentrum Hereon Kantstr. 55 14513 Teltow Germany
- Institute for Technical and Macromolecular Chemistry, University of Hamburg Bundesstrasse 55 20146 Hamburg Germany
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4
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Kovel CB, Darmon JM, Stieber SCE, Pombar G, Pabst TP, Theis B, Turner ZR, Üngör Ö, Shatruk M, DeBeer S, Chirik PJ. Bimolecular Reductive Elimination of Ethane from Pyridine(diimine) Iron Methyl Complexes: Mechanism, Electronic Structure, and Entry into [2+2] Cycloaddition Catalysis. J Am Chem Soc 2023; 145:5061-5073. [PMID: 36821524 DOI: 10.1021/jacs.2c10547] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
The application of bimolecular reductive elimination to the activation of iron catalysts for alkene-diene cycloaddition is described. Key to this approach was the synthesis, characterization, electronic structure determination, and ultimately solution stability of a family of pyridine(diimine) iron methyl complexes with diverse steric properties and electronic ground states. Both the aryl-substituted, (MePDI)FeCH3 and (EtPDI)FeCH3 (RPDI = 2,6-(2,6-R2-C6H3N═CMe)2C5H3N), and the alkyl-substituted examples, (CyAPDI)FeCH3 (CyAPDI = 2,6-(C6H11N═CMe)2C5H3N), have molecular structures significantly distorted from planarity and S = 3/2 ground states. The related N-arylated derivative bearing 2,6-di-isopropyl aryl substituents, (iPrPDI)FeCH3, has an idealized planar geometry and exhibits spin crossover behavior from S = 1/2 to S = 3/2 states. At 23 °C under an N2 atmosphere, both (MePDI)FeCH3 and (EtPDI)FeCH3 underwent reductive elimination of ethane to form the iron dinitrogen precatalysts, [(MePDI)Fe(N2)]2(μ-N2) and [(EtPDI)Fe(N2)]2(μ-N2), respectively, while (iPrPDI)FeCH3 proved inert to C-C bond formation. By contrast, addition of butadiene to all three iron methyl complexes induced ethane formation and generated the corresponding iron butadiene complexes, (RPDI)Fe(η4-C4H6) (R = Me, Et, iPr), known precatalysts for the [2+2] cycloaddition of olefins and dienes. Kinetic, crossover experiments, and structural studies were combined with magnetic measurements and Mössbauer spectroscopy to elucidate the electronic and steric features of the iron complexes that enable this unusual reductive elimination and precatalyst activation pathway. Transmetalation of methyl groups between iron centers was fast at ambient temperature and independent of steric environment or spin state, while the intermediate dimer underwent the sterically controlled rate-determining reaction with either N2 or butadiene to access a catalytically active iron compound.
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Affiliation(s)
- Carli B Kovel
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Jonathan M Darmon
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - S Chantal E Stieber
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Gisselle Pombar
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Tyler P Pabst
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Bastian Theis
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Zoë R Turner
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Ökten Üngör
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, United States
| | - Michael Shatruk
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, United States
| | - Serena DeBeer
- Max Planck Institute for Chemical Energy Conversion, Stiftstraße 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Paul J Chirik
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
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Ricci G, Leone G, Zanchin G, Masi F, Guelfi M, Pampaloni G. Dichloro(2,2'-bipyridine)copper/MAO: An Active and Stereospecific Catalyst for 1,3-Diene Polymerization. Molecules 2023; 28:molecules28010374. [PMID: 36615567 PMCID: PMC9822443 DOI: 10.3390/molecules28010374] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 12/23/2022] [Accepted: 12/28/2022] [Indexed: 01/03/2023] Open
Abstract
Dichloro(2,2'-bipyridine)copper was synthesized by reacting copper dichloride with bypyridine, and its behavior, in combination with methylaluminoxane (MAO), in the polymerization of butadiene, isoprene, 2,3-dimethyl-1,3 butadiene, and 3-methyl-1,3-pentadiene was examined. The purpose of this study is to find catalytic systems that are more sustainable than those currently used for the polymerization of butadiene and isoprene (e.g., Co and Ni), but that are comparable in terms of catalytic activity and selectivity. Predominantly, syndiotactic 1,2 polybutadiene, crystalline syndiotactic 3,4 polyisoprene, crystalline syndiotactic 1,2 poly(3-methyl-1,3-pentadiene), and crystalline cis-1,4 poly(2,3-dimethyl-1,3-butadiene) were obtained in a manner similar to that observed with the analogous iron complex. As far as we know, the investigated catalytic system represents the first example of a copper-based catalyst in the field of stereospecific polymerization. Given the great availability of copper, its extremely low toxicity (and therefore high sustainability), and the similarity of its behavior to that of iron, the result obtained seems to us of considerable interest and worthy of further investigation.
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Affiliation(s)
- Giovanni Ricci
- CNR—Istituto di Scienze e Tecnologie Chimiche “Giulio Natta” (SCITEC), Via A. Corti 12, I-20133 Milano, Italy
- Correspondence:
| | - Giuseppe Leone
- CNR—Istituto di Scienze e Tecnologie Chimiche “Giulio Natta” (SCITEC), Via A. Corti 12, I-20133 Milano, Italy
| | - Giorgia Zanchin
- CNR—Istituto di Scienze e Tecnologie Chimiche “Giulio Natta” (SCITEC), Via A. Corti 12, I-20133 Milano, Italy
| | - Francesco Masi
- Scientific Advisor, Via Galvani 7, I-26866 Sant’Angelo Lodigiano, Italy
| | - Massimo Guelfi
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via Moruzzi 13, I-56124 Pisa, Italy
| | - Guido Pampaloni
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via Moruzzi 13, I-56124 Pisa, Italy
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6
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Duan R, Hu C, Liu Y, Bian X, Pang X, Chen X. In Situ Initiation of Epoxides: Activated Metal Salt Catalysts for Cyclic Ester Polymerization. Ind Eng Chem Res 2022. [DOI: 10.1021/acs.iecr.2c03594] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Ranlong Duan
- University of Science and Technology of China, Hefei 230027, Anhui, China
- Key Laboratory of Polymer Ecomaterials, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
| | - Chenyang Hu
- Key Laboratory of Polymer Ecomaterials, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
| | - Yanlong Liu
- University of Science and Technology of China, Hefei 230027, Anhui, China
- Key Laboratory of Polymer Ecomaterials, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
| | - Xinchao Bian
- University of Science and Technology of China, Hefei 230027, Anhui, China
- Key Laboratory of Polymer Ecomaterials, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
| | - Xuan Pang
- University of Science and Technology of China, Hefei 230027, Anhui, China
- Key Laboratory of Polymer Ecomaterials, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
| | - Xuesi Chen
- University of Science and Technology of China, Hefei 230027, Anhui, China
- Key Laboratory of Polymer Ecomaterials, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
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7
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Hashmi OH, Capet F, Visseaux M, Champouret Y. Homoleptic and Heteroleptic Substituted Amidomethylpyridine Iron Complexes: Synthesis, Structure and Polymerization of rac‐Lactide. Eur J Inorg Chem 2022. [DOI: 10.1002/ejic.202200073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Obaid H. Hashmi
- Universite de Lille Faculte des Sciences et Technologies UMR 8181 Campus Scientifique 59655 Villeneuve d'Ascq FRANCE
| | - Frederic Capet
- Universite de Lille Faculte des Sciences et Technologies UMR 8181 Campus Scientifique 59655 Villeneuve d'Ascq FRANCE
| | - Marc Visseaux
- Universite de Lille Faculte des Sciences et Technologies UMR 8181 Campus Scientifique 59655 Villeneuve d'Ascq FRANCE
| | - Yohan Champouret
- Universite de Lille Faculte des Sciences et Technologies UMR 8181 Campus Scientifique 59655 Villeneuve d'Ascq FRANCE
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8
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Disentangled UHMWPE@silica powders for potential use in power bed fusion based additive manufacturing. Eur Polym J 2022. [DOI: 10.1016/j.eurpolymj.2021.110936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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9
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Nylund PVS, Monney B, Weder C, Albrecht M. N-Heterocyclic carbene iron complexes catalyze the ring-opening polymerization of lactide. Catal Sci Technol 2022; 12:996-1004. [PMID: 35222940 PMCID: PMC8819372 DOI: 10.1039/d1cy02143e] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Accepted: 01/05/2022] [Indexed: 12/02/2022]
Abstract
Poly(lactic acid), PLA, which holds great promise as a biodegradable substitute of fossil resource-derived polyolefins, is industrially produced by the ring-opening polymerization of lactide using a potentially harmful tin catalyst. Based on mechanistic insights into the reaction of N-heterocyclic carbene (NHC) iron complexes with carbonyl substrates, we surmised and demonstrate here that such complexes are excellent catalysts for the bulk polymerization of lactide. We show that an iron complex with a triazolylidene NHC ligand is active at lactide/catalyst ratios of up to 10 000 : 1, produces polylactide with relatively high number-average molecular weights (up to 50 kg mol−1) and relatively narrow dispersity (Đ ∼ 1.6), and features an apparent polymerization rate constant kapp of up to 8.5 × 10−3 s−1, which is more than an order of magnitude higher than that of the industrially used tin catalyst. Kinetic studies and end-group analyses support that the catalytically active species is well defined and that the polymerization proceeds via a coordination–insertion mechanism. The robustness of the catalyst allows technical grade lactide to be polymerized, thus offering ample potential for application on larger scale in an industrially relevant setting. Iron(ii) complexes containing a mesoionic triazolylidene ligand are highly efficient catalyst precursors for the ring opening polymerization of lactide to poly(lactic acid), surpassing other iron complexes and also industrially utilized Sn(oct)2.![]()
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Affiliation(s)
- Pamela V. S. Nylund
- Department of Chemistry, Biochemistry & Pharmaceutical Sciences, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland
| | - Baptiste Monney
- Adolphe Merkle Institute, University of Fribourg, Chemin des Verdiers 4, 1700 Fribourg, Switzerland
| | - Christoph Weder
- Adolphe Merkle Institute, University of Fribourg, Chemin des Verdiers 4, 1700 Fribourg, Switzerland
| | - Martin Albrecht
- Department of Chemistry, Biochemistry & Pharmaceutical Sciences, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland
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Chen J, Wu X, Zhang L, Duan Z, Liu B. Ring-Opening Polymerization of ε-Caprolactone Mediated by Di-Zinc Complex Bearing Macrocyclic Thioether-phenolate [OSSO]-type Ligand. Polym Chem 2022. [DOI: 10.1039/d2py00115b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A unique example of zinc bromide complexes bearing macrocyclic [OSSO]-type thioetherphenolate ligand (Di-[OSSO]ZnBr) has been successfully explored toward ring-opening polymerization (ROP) of -caprolactone (ε-CL) in the presence of epoxides and...
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11
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Lianrong F, Yan-Bing W, Hui J, Xin-Qi H, Mao-Ping S. Applications of Cobalt Complexes in Olefin Polymerization. CHINESE J ORG CHEM 2022. [DOI: 10.6023/cjoc202204036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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12
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Ricci G, Leone G, Zanchin G, Palucci B, Boccia AC, Sommazzi A, Masi F, Zacchini S, Guelfi M, Pampaloni G. Highly Stereoregular 1,3-Butadiene and Isoprene Polymers through Monoalkyl- N-Aryl-Substituted Iminopyridine Iron Complex-Based Catalysts: Synthesis and Characterization. Macromolecules 2021. [DOI: 10.1021/acs.macromol.1c01291] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Giovanni Ricci
- CNR-Istituto di Scienze e Tecnologie Chimiche “Giulio Natta” (SCITEC), via A. Corti 12, I-20133 Milano, Italy
| | - Giuseppe Leone
- CNR-Istituto di Scienze e Tecnologie Chimiche “Giulio Natta” (SCITEC), via A. Corti 12, I-20133 Milano, Italy
| | - Giorgia Zanchin
- CNR-Istituto di Scienze e Tecnologie Chimiche “Giulio Natta” (SCITEC), via A. Corti 12, I-20133 Milano, Italy
| | - Benedetta Palucci
- CNR-Istituto di Scienze e Tecnologie Chimiche “Giulio Natta” (SCITEC), via A. Corti 12, I-20133 Milano, Italy
| | - Antonella Caterina Boccia
- CNR-Istituto di Scienze e Tecnologie Chimiche “Giulio Natta” (SCITEC), via A. Corti 12, I-20133 Milano, Italy
| | - Anna Sommazzi
- Versalis S.P.A.─Centro Ricerca Novara, Via G. Fauser 4, I-28100 Novara, Italy
| | - Francesco Masi
- Versalis S.p.A.─R&D Partner Catalysis, Piazza Boldrini 1, I-20097 San Donato Milanese, Italy
| | - Stefano Zacchini
- Università di Bologna, Dipartimento di Chimica Industriale “Toso Montanari”, Viale Risorgimento 4, I-40136 Bologna, Italy
| | - Massimo Guelfi
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via Moruzzi 13, I-56124 Pisa, Italy
| | - Guido Pampaloni
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via Moruzzi 13, I-56124 Pisa, Italy
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13
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Zhu G, Wang L, Kuang J, Xu G, Zhang Y, Wang Q. High Double Bond Content of Polyisoprene Synthesis via Cationic Polymerization Synergistically Catalyzed by Tf 2NH-Ionic Liquids. Macromolecules 2021. [DOI: 10.1021/acs.macromol.1c00418] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Guangqian Zhu
- Key Laboratory of Biobased Materials, Qingdao Institute of Bio-energy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Liang Wang
- Key Laboratory of Biobased Materials, Qingdao Institute of Bio-energy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
| | - Jia Kuang
- Key Laboratory of Biobased Materials, Qingdao Institute of Bio-energy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
| | - Guangqiang Xu
- Key Laboratory of Biobased Materials, Qingdao Institute of Bio-energy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yongqiang Zhang
- Key Laboratory of Biobased Materials, Qingdao Institute of Bio-energy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
| | - Qinggang Wang
- Key Laboratory of Biobased Materials, Qingdao Institute of Bio-energy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
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14
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Ricci G, Pampaloni G, Sommazzi A, Masi F. Dienes Polymerization: Where We Are and What Lies Ahead. Macromolecules 2021. [DOI: 10.1021/acs.macromol.1c00004] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Giovanni Ricci
- CNR-Istituto di Scienze e Tecnologie Chimiche “Giulio Natta” (SCITEC), Via A. Corti 12, I-20133 Milano, Italy
| | - Guido Pampaloni
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via Moruzzi 13, I-56124 Pisa, Italy
| | - Anna Sommazzi
- Centro Ricerca Novara, Versalis S.p.A., Via G. Fauser 4, I-28100 Novara, Italy
| | - Francesco Masi
- R&D Partner Catalysis, Versalis S.p.A., Piazza Boldrini 1, I-20097 San Donato Milanese (MI), Italy
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15
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Ring-Opening Copolymerization of Cyclohexene Oxide and Cyclic Anhydrides Catalyzed by Bimetallic Scorpionate Zinc Catalysts. Polymers (Basel) 2021; 13:polym13101651. [PMID: 34069623 PMCID: PMC8161297 DOI: 10.3390/polym13101651] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2021] [Revised: 05/13/2021] [Accepted: 05/14/2021] [Indexed: 11/24/2022] Open
Abstract
The catalytic activity and high selectivity reported by bimetallic heteroscorpionate acetate zinc complexes in ring-opening copolymerization (ROCOP) reactions involving CO2 as substrate encouraged us to expand their use as catalysts for ROCOP of cyclohexene oxide (CHO) and cyclic anhydrides. Among the catalysts tested for the ROCOP of CHO and phthalic anhydride at different reaction conditions, the most active catalytic system was the combination of complex 3 with bis(triphenylphosphine)iminium as cocatalyst in toluene at 80 °C. Once the optimal catalytic system was determined, the scope in terms of other cyclic anhydrides was broadened. The catalytic system was capable of copolymerizing selectively and efficiently CHO with phthalic, maleic, succinic and naphthalic anhydrides to afford the corresponding polyester materials. The polyesters obtained were characterized by spectroscopic, spectrometric, and calorimetric techniques. Finally, the reaction mechanism of the catalytic system was proposed based on stoichiometric reactions.
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17
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Investigations on the Ethylene Polymerization with Bisarylimine Pyridine Iron (BIP) Catalysts. Catalysts 2021. [DOI: 10.3390/catal11030407] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The kinetics and terminations of ethylene polymerization, mediated by five bisarylimine pyridine (BIP) iron dichloride precatalysts, and activated by large amounts of methyl aluminoxane (MAO) was studied. Narrow distributed paraffins from initially formed aluminum polymeryls and broader distributed 1-polyolefins and (bimodal) mixtures, thereof, were obtained after acidic workup. The main pathway of olefin formation is beta-hydrogen transfer to ethylene. The rate of polymerization in the initial phase is inversely proportional to the co-catalyst concentration for all pre-catalysts; a first-order dependence was found on ethylene and catalyst concentrations. The inhibition by aluminum alkyls is released to some extent in a second phase, which arises after the original methyl groups are transformed into n-alkyl entities and the aluminum polymeryls partly precipitate in the toluene medium. The catalysis is interpretable in a mechanism, wherein, the relative rate of chain shuttling, beta-hydrogen transfer and insertion of ethylene are determining the outcome. Beta-hydrogen transfer enables catalyst mobility, which leads to a (degenerate) chain growth of already precipitated aluminum alkyls. Stronger Lewis acidic centers of the single site catalysts, and those with smaller ligands, are more prone to yield 1-olefins and to undergo a faster reversible alkyl exchange between aluminum and iron.
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18
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Zanchin G, Leone G. Polyolefin thermoplastic elastomers from polymerization catalysis: Advantages, pitfalls and future challenges. Prog Polym Sci 2021. [DOI: 10.1016/j.progpolymsci.2020.101342] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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19
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Hashmi OH, Visseaux M, Champouret Y. Evidence of coordinative chain transfer polymerization of isoprene using iron iminopyridine/ZnEt 2 catalytic systems. Polym Chem 2021. [DOI: 10.1039/d1py00433f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Herein, the first example of a reversible iron-mediated chain transfer polymerisation of isoprene with ZnEt2 as the chain transfer agent is reported.
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Affiliation(s)
- Obaid H. Hashmi
- Univ. Lille, CNRS, Centrale Lille, Univ. Artois, UMR 8181 – UCCS – Unité de Catalyse et de Chimie du Solide, F-59000 Lille, France
| | - Marc Visseaux
- Univ. Lille, CNRS, Centrale Lille, Univ. Artois, UMR 8181 – UCCS – Unité de Catalyse et de Chimie du Solide, F-59000 Lille, France
| | - Yohan Champouret
- Univ. Lille, CNRS, Centrale Lille, Univ. Artois, UMR 8181 – UCCS – Unité de Catalyse et de Chimie du Solide, F-59000 Lille, France
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20
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Ejarque D, Calvet T, Font-Bardia M, Pons J. Steric crowding of a series of pyridine based ligands influencing the photophysical properties of Zn( II) complexes. CrystEngComm 2021. [DOI: 10.1039/d1ce00833a] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The combination of α-acetamidocinnamic acid (HACA) and different N, N,N and N,N,N pyridines (dPy) leads to crowded Zn(ii) metal centers. The increasing bulkiness competes with the chelation enhanced effect (CHEF) in the resulting quantum yields.
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Affiliation(s)
- Daniel Ejarque
- Departament de Química, Universitat Autònoma de Barcelona, 08193-Bellaterra, Barcelona, Spain
| | - Teresa Calvet
- Departament de Mineralogia, Petrologia i Geologia Aplicada, Universitat de Barcelona, Martí i Franquès s/n, 08028 Barcelona, Spain
| | - Mercè Font-Bardia
- Unitat de Difracció de Raig-X, Centres Científics i Tecnològics de la Universitat de Barcelona (CCiTUB), Universitat de Barcelona, Solé i Sabarís, 1-3, 08028 Barcelona, Spain
| | - Josefina Pons
- Departament de Química, Universitat Autònoma de Barcelona, 08193-Bellaterra, Barcelona, Spain
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21
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Jing C, Wang L, Zhu G, Hou H, Zhou L, Wang Q. Enhancing Thermal Stability in Aminopyridine Iron(II)-Catalyzed Polymerization of Conjugated Dienes. Organometallics 2020. [DOI: 10.1021/acs.organomet.0c00591] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Chuyang Jing
- Key Laboratory of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
| | - Liang Wang
- Key Laboratory of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
| | - Guangqian Zhu
- Key Laboratory of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Hongbin Hou
- Key Laboratory of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
| | - Li Zhou
- Key Laboratory of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
| | - Qinggang Wang
- Key Laboratory of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
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22
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Wang L, Wang X, Hou H, Zhu G, Han Z, Yang W, Chen X, Wang Q. An unsymmetrical binuclear iminopyridine-iron complex and its catalytic isoprene polymerization. Chem Commun (Camb) 2020; 56:8846-8849. [PMID: 32633282 DOI: 10.1039/d0cc04122j] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A series of chloride-bridged unsymmetrical mixed Fe(ii)-HS/Fe(ii)-LS binuclear structures has been prepared and characterized. Upon activation with MAO, highly efficient catalytic polymerization of isoprene was achieved, delivering an ultra-high molecular weight (catalyst loading = 2.5 ppm, Mn = 1.8 × 106 g mol-1, Mw/Mn = 1.4).
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Affiliation(s)
- Liang Wang
- Key Laboratory of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, China.
| | - Xiaowu Wang
- Key Laboratory of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, China.
| | - Hongbin Hou
- Key Laboratory of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, China.
| | - Guangqian Zhu
- Key Laboratory of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, China. and Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Zhenyu Han
- Key Laboratory of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, China. and Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Weiying Yang
- Key Laboratory of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, China. and Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Xiao Chen
- Key Laboratory of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, China.
| | - Qinggang Wang
- Key Laboratory of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, China.
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23
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A new complex compound of chromium(III) with 5-aminopyridine-2-carboxylate anions – Structure, physicochemical and catalytic properties. Polyhedron 2020. [DOI: 10.1016/j.poly.2020.114616] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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24
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Huo S, Wang Q, Zuo W. An iron variant of the Noyori hydrogenation catalyst for the asymmetric transfer hydrogenation of ketones. Dalton Trans 2020; 49:7959-7967. [PMID: 32497166 DOI: 10.1039/d0dt01204a] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
We report the design of a new iron catalyst for the asymmetric transfer hydrogenation of ketones. This type of iron catalyst combines the structural characteristics of the Noyori hydrogenation catalyst (an axially chiral 2,2'-bis(phosphino)-1,1'-binaphthyl fragment and the metal-ligand bifunctional motif) and an ene(amido) group that can activate the iron center. After activation by 8 equivalents of potassium tert-butoxide, (SA,RP,SS)-7a and (SA,RP,SS)-7b are active but nonenantioselective catalysts for the transfer hydrogenation of acetophenone and α,β-unsaturated aldehydes at room temperature in isopropanol. A maximum turnover number of 14480 was observed for (SA,RP,SS)-7a in the reduction of acetophenone. The right combination of the stereochemistry of the axially chiral 2,2'-bis(phosphino)-1,1'-binaphthyl group and the carbon-centered chiral amine-imine moiety in (SA,RP,RR)-7b' afforded an enantioselective catalyst for the preparation of chiral alcohols with moderate to good yields and a broad functional group tolerance.
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Affiliation(s)
- Shangfei Huo
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of materials science and engineering, Donghua University, China.
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25
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Zhang Q, Zhang R, Han M, Yang W, Liang T, Sun WH. 4,4'-Difluorobenzhydryl-modified bis(imino)-pyridyliron(ii) chlorides as thermally stable precatalysts for strictly linear polyethylenes with narrow dispersities. Dalton Trans 2020; 49:7384-7396. [PMID: 32427253 DOI: 10.1039/d0dt01344g] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The 4,4'-difluorobenzhydryl-modified bis(imino)pyridylferrous chlorides, [2-{CMeN(2,6-(4-FC6H4)2CH2-4-t-BuC6H2)}-6-(CMeNAr)C5H3N] FeCl2 (Ar = 2,6-Me2C6H3Fe1, 2,6-Et2C6H3Fe2, 2,6-i-Pr2C6H3Fe3, 2,4,6-Me3C6H2Fe4, 2,6-Et-4-MeC6H2Fe5 and 2,6-(4-FC6H4)2CH2-4-t-BuC6H2Fe6), were synthesized in good yields. All iron complexes were characterized by 1H/19F NMR and elemental analysis, and the molecular structures of representative complexes Fe1 and Fe6 were determined by single crystal X-ray diffraction, which revealed a slightly distorted square pyramid around the iron center. Activated with either MAO or MMAO, Fe1-Fe5 exhibited very high activities (up to 17.2 × 106 g (PE) mol-1 (Fe) h-1 for Fe1/MMAO) toward ethylene polymerization, producing highly linear polyethylenes with narrow dispersities as required by industry and value added PEs. Importantly, the Fe1/MAO maintained an activity of 9.5 × 106 g (PE) mol-1 (Fe) h-1 at 100 °C of operating temperature, making the catalytic system suitable for practical application. Simulation quantitatively revealed the mechanism of the enhanced catalytic performance from the electronic and steric point of view.
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Affiliation(s)
- Qiuyue Zhang
- Key Laboratory of Engineering Plastics and Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China. and CAS Research/Education Center for Excellence in Molecular Sciences and International School, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Randi Zhang
- Key Laboratory of Engineering Plastics and Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China. and CAS Research/Education Center for Excellence in Molecular Sciences and International School, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Mingyang Han
- Key Laboratory of Engineering Plastics and Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China. and CAS Research/Education Center for Excellence in Molecular Sciences and International School, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wenhong Yang
- Key Laboratory of Engineering Plastics and Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
| | - Tongling Liang
- Key Laboratory of Engineering Plastics and Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
| | - Wen-Hua Sun
- Key Laboratory of Engineering Plastics and Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China. and CAS Research/Education Center for Excellence in Molecular Sciences and International School, University of Chinese Academy of Sciences, Beijing 100049, China and State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China
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26
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Lin W, Zhang L, Suo H, Vignesh A, Yousuf N, Hao X, Sun WH. Synthesis of characteristic polyisoprenes using rationally designed iminopyridyl metal (Fe and Co) precatalysts: investigation of co-catalysts and steric influence on their catalytic activity. NEW J CHEM 2020. [DOI: 10.1039/d0nj00942c] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
A series of iminopyridyl ligand-based iron and cobalt complexes are utilized as catalysts in isoprene polymerization, in which the microstructure of resultant polyisoprenes was investigated.
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Affiliation(s)
- Wenhua Lin
- School of Textiles and Clothing
- Jiangnan University
- Wuxi
- China
- Key Laboratory of Engineering Plastics and Beijing National Laboratory for Molecular Science
| | - Liping Zhang
- School of Textiles and Clothing
- Jiangnan University
- Wuxi
- China
| | - Hongyi Suo
- Key Laboratory of Engineering Plastics and Beijing National Laboratory for Molecular Science
- Institute of Chemistry
- Chinese Academy of Sciences
- Beijing 100190
- China
| | - Arumugam Vignesh
- Key Laboratory of Engineering Plastics and Beijing National Laboratory for Molecular Science
- Institute of Chemistry
- Chinese Academy of Sciences
- Beijing 100190
- China
| | - Nighat Yousuf
- CAS Research/Education Center for Excellence in Molecular Sciences
- University of Chinese Academy of Sciences
- Beijing 100049
- China
| | - Xiang Hao
- Key Laboratory of Engineering Plastics and Beijing National Laboratory for Molecular Science
- Institute of Chemistry
- Chinese Academy of Sciences
- Beijing 100190
- China
| | - Wen-Hua Sun
- Key Laboratory of Engineering Plastics and Beijing National Laboratory for Molecular Science
- Institute of Chemistry
- Chinese Academy of Sciences
- Beijing 100190
- China
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27
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Affiliation(s)
- Dylan J. Walsh
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
| | - Michael G. Hyatt
- Department of Chemistry, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
| | - Susannah A. Miller
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
| | - Damien Guironnet
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
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28
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Hashmi OH, Champouret Y, Visseaux M. Highly Active Iminopyridyl Iron-Based Catalysts for the Polymerization of Isoprene. Molecules 2019; 24:molecules24173024. [PMID: 31438501 PMCID: PMC6749290 DOI: 10.3390/molecules24173024] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Revised: 07/28/2019] [Accepted: 08/07/2019] [Indexed: 11/17/2022] Open
Abstract
A series of iminopyridyl-based ligands, 6-[(Ar)N=C(R)]-2-C6H5N [(Ar = 2,6-Me2-C6H3, R = Me (L1); Ar = 2,6-iPr2-C6H3, R = Me (L2); Ar = 2,6-Me2-C6H3, R = H (L3); Ar = 2,6-iPr2-C6H3, R = H (L4); Ar = 3,5-(CF3)2-C6H3, R = Me (L5); Ar = C6F5, R = Me (L6)], and their corresponding iron (II) complexes were developed to investigate their application in the controlled coordinative polymerization of isoprene. The modulation of steric and electronic properties within this family of ligands/pre-catalysts has shown to influence the stereo-selectivity and activity of the polymerization of isoprene after activation. Upon activation with various co-catalysts such as AliBu3/[Ph3C][B(C6F5)4], AlEt3/[Ph3C][B(C6F5)4] or MAO, the resulting catalysts produced polyisoprenes with an excellent conversion (>99% of 500–5000 equiv.) within less than 1 h (TOF > 500 h−1) and having a variety of stereo-/regio-regularities. The presence of electron-donating and withdrawing groups drastically impacted the activity and the stereoselectivity of the catalysts during the course of the polymerization of isoprene. When activated with AliBu3/[Ph3C][B(C6F5)4], the complexes {6-[(2,6-Me2-C6H3)N=C(Me)]-2-C6H5N}FeCl2 (C1) and {6-[(2,6-iPr2-C6H3)N=C(Me)]-2-C6H5N}FeCl2 (C2) exhibited moderate trans-1,4 selectivity (>67%) while the iron-based systems bearing related aldiminopyridyl ligands {6-[(2,6-Me2-C6H3)N=C(H)]-2-C6H5N}FeCl2 (C3) and {6-[(2,6-iPr2-C6H3)N=C(H)]-2-C6H5N}FeCl2 (C4) were found to afford significant cis-1,4 selectivity at low temperature (>86% at −40 °C). On the other hand, the ternary {6-[(3,5-(CF3)2-C6H3)N=C(Me)]-2-C6H5N}FeCl2 (C5) or {6-[(C6F5)N=C(Me)]-2-C6H5N}FeCl2 (C6)/AliBu3/[Ph3C][B(C6F5)4] catalytic combinations showed exceptional activity for the polymerization of isoprene (TOF > 1,000,000 h−1), albeit providing less stereoselectivity.
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Affiliation(s)
- Obaid H Hashmi
- UMR 8181-UCCS-Unité de Catalyse et de Chimie du Solide, ENSCL, Centrale Lille, University of Artois, University of Lille, CNRS, F-59000 Lille, France
| | - Yohan Champouret
- UMR 8181-UCCS-Unité de Catalyse et de Chimie du Solide, ENSCL, Centrale Lille, University of Artois, University of Lille, CNRS, F-59000 Lille, France.
| | - Marc Visseaux
- UMR 8181-UCCS-Unité de Catalyse et de Chimie du Solide, ENSCL, Centrale Lille, University of Artois, University of Lille, CNRS, F-59000 Lille, France.
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