1
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Kumar N, Gupta P. DFT Struggles to Predict the Energy Landscape for Iron Pyridine Diimine-Catalyzed [2 + 2] Cycloaddition of Alkenes: Insights into the Problem and Alternative Solutions. J Phys Chem A 2024; 128:4114-4127. [PMID: 38659086 DOI: 10.1021/acs.jpca.3c08325] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
In recent years, noninnocent pyridine diimine (PDI) complexes featuring first-row transition metals have emerged as prominent catalysts, demonstrating efficacy in a diverse range of vital organometallic transformations. However, the inherent complexity of the fundamental reactivity paradigm in these systems arises from the presence of a noninnocent ligand and the multispin feasibility of 3d metals. While density functional theory (DFT) has been widely used to unravel mechanistic insights, its limitations as a single-reference method can potentially misrepresent spin-state energetics, compromising our understanding of these intricate systems. In this study, we employ extensive high-level ab initio state averaged-complete active space self-consistent field/N-electron valence state perturbation theory (SA-CASSCF/NEVPT2) calculations in combination with DFT to investigate an iron-PDI-catalyzed [2 + 2] cycloaddition reaction of alkenes. The transformation proceeds through two major steps: oxidative cyclization and reductive elimination. Contrary to the predictions of DFT calculations, which suggest two-state reactivity in the reaction and identify reductive elimination as the turnover-limiting step, SA-CASSCF/NEVPT2-corrected results unequivocally establish a single-state reactivity scenario with oxidative cyclization as the turnover-limiting step. SA-CASSCF/NEVPT2-based insights into electronic ground states and electron distribution elucidate the intriguing interactions between the PDI ligand and the iron center, revealing the highly multiconfigurational nature of these species and providing a precise depiction of metal-ligand cooperativity throughout the transformation. A comparative assessment of several widely recognized DFT functionals against SA-CASSCF/NEVPT2-corrected data indicates that single-point energy calculations using the modern density functional MN15 on TPSSh geometries offer the most reliable density functional methodology, in scenarios where SA-CASSCF/NEVPT2 computational cost is a consideration.
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Affiliation(s)
- Nikunj Kumar
- Computational Catalysis Center, Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand 247667, India
| | - Puneet Gupta
- Computational Catalysis Center, Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand 247667, India
- Center for Sustainable Energy, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand 247667, India
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2
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Wang Y, Zhang W, Wang X, Zuo W, Xue X, Ma Y, Sun WH. N-(2-(Diphenylphosphino)ethyl)-2-alkyl-5,6,7,8-tetrahydro-quinolin-8-amines iron(ii) complexes: structural diversity and the ring opening polymerization of ε-caprolactone. RSC Adv 2023; 13:29866-29878. [PMID: 37842685 PMCID: PMC10568405 DOI: 10.1039/d3ra05867k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Accepted: 09/27/2023] [Indexed: 10/17/2023] Open
Abstract
A series of N-(2-(diphenylphosphino)ethyl)-2-alkyl-5,6,7,8-tetrahydroquinolin-8-amines was prepared and used in individually reacting with iron chloride under nitrogen atmosphere to form their iron(ii) complexes Fe1-Fe6. All compounds were characterized using FT-IR spectroscopy and elemental analyses, the organic compounds were confirmed with NMR measurements, and the iron complexes were submitted to single-crystal X-ray diffraction, revealing Fe1, Fe2, Fe4, Fe5, and Fe6 as either mono- or di-nuclear forms. Forming a binary system in situ with two equivalents of LiCH2SiMe3, all iron complexes Fe1-Fe6 efficiently initiated the ring opening polymerization of ε-caprolactone, achieving the TOF up to 8.8 × 103 h-1. More importantly, the resultant polycaprolactone (PCL) possessed high molecular weights with the Mn range of 9.21-24.3 × 104 g mol-1, being a rare case of the iron(ii) catalyst in producing PCL with such high molecular weight. The 1H NMR and MALDI-TOF investigations demonstrated that the PCLs were linear features capped with a methoxy group or CH2SiMe3 or cyclic structure that varied with the molar ratio of [ε-CL]/Fe.
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Affiliation(s)
- Yun Wang
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University Shanghai 201620 China
- Beijing Key Laboratory of Clothing Materials R&D and Assessment, Beijing Engineering Research Center of Textile Nanofiber, School of Materials Science and Engineering, Beijing Institute of Fashion Technology Beijing 100029 China
- Key Laboratory of Engineering Plastics and Beijing National Laboratory for Molecular Science, Institute of Chemistry, Chinese Academy of Sciences Beijing 100190 China
| | - Wenjuan Zhang
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University Shanghai 201620 China
- Beijing Key Laboratory of Clothing Materials R&D and Assessment, Beijing Engineering Research Center of Textile Nanofiber, School of Materials Science and Engineering, Beijing Institute of Fashion Technology Beijing 100029 China
| | - Xing Wang
- Beijing Key Laboratory of Clothing Materials R&D and Assessment, Beijing Engineering Research Center of Textile Nanofiber, School of Materials Science and Engineering, Beijing Institute of Fashion Technology Beijing 100029 China
- Key Laboratory of Engineering Plastics and Beijing National Laboratory for Molecular Science, Institute of Chemistry, Chinese Academy of Sciences Beijing 100190 China
| | - Weiwei Zuo
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University Shanghai 201620 China
| | - Xiaopan Xue
- Beijing Key Laboratory of Clothing Materials R&D and Assessment, Beijing Engineering Research Center of Textile Nanofiber, School of Materials Science and Engineering, Beijing Institute of Fashion Technology Beijing 100029 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
| | - 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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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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Yu B, Xu X, Huang ZN, Tao K, Sun HL, Yang QZ, Wang W. Iron–Aryloxide Complex Bearing Bis(dipyrromethene) Ligands for the Ring-Opening Polymerization of ε-Caprolactone. Organometallics 2023. [DOI: 10.1021/acs.organomet.2c00618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/30/2023]
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5
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Li B, Hu C, Pang X, Chen X. Valence-variable Catalysts for Redox-controlled Switchable Ring-opening Polymerization. Chem Asian J 2023; 18:e202201031. [PMID: 36321213 DOI: 10.1002/asia.202201031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Revised: 10/25/2022] [Indexed: 11/25/2022]
Abstract
As a representative class of sustainable polymer materials, biodegradable polymers have attracted increasing interest in recent years. Despite significant advance of related polymerization techniques, realizing high sequence-control and easy-handling in ring-opening (co)polymerizations still remains a central challenge. To this end, a promising solution is the development of valence-variable metal-based catalysts for redox-induced switchable polymerization of cyclic esters, cyclic ethers, epoxides, and CO2 . Through a valence-determined electron effect, the switch between different catalytically active states as well as dormant state contributes to convenient formation of polymer products with desired microstructures and various practical performances. This redox-controlled switchable strategy for controlled synthesis of polymers is overviewed in this Review with a focus on potential applications and challenges for further studies.
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Affiliation(s)
- Bokun Li
- Key Laboratory of Polymer Ecomaterials, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 130022, Changchun, P. R. China.,University of Science and Technology of China, 230026, Hefei, P. R. China
| | - Chenyang Hu
- Key Laboratory of Polymer Ecomaterials, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 130022, Changchun, P. R. China
| | - Xuan Pang
- Key Laboratory of Polymer Ecomaterials, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 130022, Changchun, P. R. China.,University of Science and Technology of China, 230026, Hefei, P. R. China
| | - Xuesi Chen
- Key Laboratory of Polymer Ecomaterials, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 130022, Changchun, P. R. China.,University of Science and Technology of China, 230026, Hefei, P. R. China
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6
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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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7
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de Vries F, Otten E. Reversible On/Off Switching of Lactide Cyclopolymerization with a Redox-Active Formazanate Ligand. ACS Catal 2022; 12:4125-4130. [PMID: 35391903 PMCID: PMC8981207 DOI: 10.1021/acscatal.1c05689] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 02/18/2022] [Indexed: 12/17/2022]
Abstract
![]()
Redox-switching of
a formazanate zinc catalyst in ring-opening
polymerization (ROP) of lactide is described. Using a redox-active
ligand bound to an inert metal ion (Zn2+) allows modulation
of the catalytic activity by reversible reduction/oxidation chemistry
at a purely organic fragment. A combination of kinetic and spectroscopic
studies, together with mass spectrometry of the catalysis mixture,
provides insight in the nature of the active species and the initiation
of lactide ring-opening polymerization. The mechanistic data highlight
the key role of the redox-active ligand and provide a rationale for
the formation of cyclic polymer.
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Affiliation(s)
- Folkert de Vries
- Stratingh Institute for Chemistry, University of Groningen, 9747 AG Groningen, The Netherlands
| | - Edwin Otten
- Stratingh Institute for Chemistry, University of Groningen, 9747 AG Groningen, The Netherlands
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8
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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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9
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Kaler S, Jones MD. Recent advances in externally controlled ring-opening polymerisations. Dalton Trans 2021; 51:1241-1256. [PMID: 34918735 DOI: 10.1039/d1dt03471e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Switchable catalysis is a powerful tool in the polymer chemist's toolbox as it allows on demand access to a variety of polymer architectures. Switchable catalysts operate by the generation of a species which is chemically distinct in behaviour and structure to the precursor. This difference in catalytic activity has been exploited to allow spatiotemporal control over polymerisations in the synthesis of (co)polymers. Although switchable methodologies have been applied to other polymerisation mechanisms for quite some time, for ring opening polymerisation (ROP) reactions it is a relatively young area of research. Despite its infancy, the field is accelerating rapidly. Here, we review recent developments for selected external stimuli for ROP, including redox chemistry, light, allosteric and mechanical control. Furthermore, a brief review on switch catalysis involving exogeneous gases will also be provided, although this area differs from traditional switchable catalysis techniques. An outlook on the future of switchable catalysis is also provided.
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Affiliation(s)
- Sandeep Kaler
- Department of Chemistry, University of Bath, Claverton Down, Bath, BA2 7AY, UK.
| | - Matthew D Jones
- Department of Chemistry, University of Bath, Claverton Down, Bath, BA2 7AY, UK.
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10
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Supej MJ, McLoughlin EA, Hsu JH, Fors BP. Reversible redox controlled acids for cationic ring-opening polymerization. Chem Sci 2021; 12:10544-10549. [PMID: 34447548 PMCID: PMC8356742 DOI: 10.1039/d1sc03011f] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Accepted: 07/02/2021] [Indexed: 11/25/2022] Open
Abstract
Advancements in externally controlled polymerization methodologies have enabled the synthesis of novel polymeric structures and architectures, and they have been pivotal to the development of new photocontrolled lithographic and 3D printing technologies. In particular, the development of externally controlled ring-opening polymerization (ROP) methodologies is of great interest, as these methods provide access to novel biocompatible and biodegradable block polymer structures. Although ROPs mediated by photoacid generators have made significant contributions to the fields of lithography and microelectronics development, these methodologies rely upon catalysts with poor stability and thus poor temporal control. Herein, we report a class of ferrocene-derived acid catalysts whose acidity can be altered through reversible oxidation and reduction of the ferrocenyl moiety to chemically and electrochemically control the ROP of cyclic esters.
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Affiliation(s)
- Michael J Supej
- Department of Chemistry and Chemical Biology, Cornell University Ithaca New York 14853 USA
| | - Elizabeth A McLoughlin
- Department of Chemistry and Chemical Biology, Cornell University Ithaca New York 14853 USA
| | - Jesse H Hsu
- Department of Chemistry and Chemical Biology, Cornell University Ithaca New York 14853 USA
| | - Brett P Fors
- Department of Chemistry and Chemical Biology, Cornell University Ithaca New York 14853 USA
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11
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Qi M, Zhang H, Dong Q, Li J, Musgrave RA, Zhao Y, Dulock N, Wang D, Byers JA. Electrochemically switchable polymerization from surface-anchored molecular catalysts. Chem Sci 2021; 12:9042-9052. [PMID: 34276933 PMCID: PMC8261715 DOI: 10.1039/d1sc02163j] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2021] [Accepted: 05/27/2021] [Indexed: 11/21/2022] Open
Abstract
Redox-switchable polymerizations of lactide and epoxides were extended to the solid state by anchoring an iron-based polymerization catalyst to TiO2 nanoparticles. The reactivity of the molecular complexes and their redox-switching characteristics were maintained in the solid-state. These properties resulted in surface-initiated polymerization reactions that produced polymer brushes whose chemical composition is dictated by the oxidation state of the iron-based complex. Depositing the catalyst-functionalized TiO2 nanoparticles on fluorine-doped tin oxide resulted in an electrically addressable surface that could be used to demonstrate spatial control in redox-switchable polymerization reactions. By using a substrate that contained two electrically isolated domains wherein one domain was exposed to an oxidizing potential, patterns of surface-bound polyesters and polyethers were accessible through sequential application of lactide and cyclohexene oxide. The differentially functionalized surfaces demonstrated distinct physical properties that illustrated the promise for using the method to pattern surfaces with multiple, chemically distinct polymer brushes.
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Affiliation(s)
- Miao Qi
- Department of Chemistry, Boston College 2609 Beacon St., Chestnut Hill MA 02467 USA
| | - Haochuan Zhang
- Department of Chemistry, Boston College 2609 Beacon St., Chestnut Hill MA 02467 USA
| | - Qi Dong
- Department of Chemistry, Boston College 2609 Beacon St., Chestnut Hill MA 02467 USA
| | - Jingyi Li
- Department of Chemistry, Boston College 2609 Beacon St., Chestnut Hill MA 02467 USA
| | - Rebecca A Musgrave
- Department of Chemistry and Chemical Biology, Harvard University 12 Oxford Street Cambridge Massachusetts 02138 USA
| | - Yanyan Zhao
- Department of Chemistry, Boston College 2609 Beacon St., Chestnut Hill MA 02467 USA
| | - Nicholas Dulock
- Department of Chemistry, Boston College 2609 Beacon St., Chestnut Hill MA 02467 USA
| | - Dunwei Wang
- Department of Chemistry, Boston College 2609 Beacon St., Chestnut Hill MA 02467 USA
| | - Jeffery A Byers
- Department of Chemistry, Boston College 2609 Beacon St., Chestnut Hill MA 02467 USA
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12
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Wang K, Prior TJ, Hughes DL, Arbaoui A, Redshaw C. Coordination chemistry of [2 + 2] Schiff-base macrocycles derived from the dianilines [(2-NH 2C 6H 4) 2X] (X = CH 2CH 2, O): structural studies and ROP capability towards cyclic esters. Dalton Trans 2021; 50:8057-8069. [PMID: 34018513 DOI: 10.1039/d1dt00711d] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Reaction of the [2 + 2] Schiff-base macrocycles {[2-(OH)-5-(R)-C6H2-1,3-(CH)2][CH2CH2(2-C6H4N)2]}2 (R = Me, L1H2; tBu, L2H2) with FeBr2 afforded the complexes [FeBr(L1H2)]2[(FeBr3)2O]·2MeCN (1·2MeCN), [FeBr(L2H2)][X] (X = 0.5(FeBr3)2O, 2·0.5MeCN, X = Br, 3·5.5MeCN), respectively. Reaction of L2H2 with [KFe(OtBu)3(THF)] (formed in situ from FeBr2 and KOtBu), following work-up, led to the isolation of the complex [Fe(L2)(L2H)]·3MeCN (4·3MeCN), whilst with [CuBr2] afforded [CuBr(L2H2)][CuBr2]·2MeCN (5·2MeCN). Attempts to form mixed Co/Ti species by reaction of [CoBrL2][CoBr3(NCMe)] with TiCl4 resulted in [L2H4][CoBr4]·2MeCN (6·2MeCN). Use of the related oxy-bridged Schiff-base macrocycles {[2-(OH)-5-(R)-C6H2-1,3-(CH)2][O(2-C6H4N)2]}2 (R = Me, L3H2; tBu, L4H2) with CoBr2 led to the isolation of the complexes [(CoBr)2(L3)]·2C3H6O (7·2C3H6O), [Co(NCMe)2(L4H2)][CoBr4]·5MeCN (8·5MeCN), [Co(NCMe)6][CoBr3(MeCN)]2·2MeCN (9·2MeCN). For comparative structural/polymerisation studies, the complexes {CoBr(NCMe)L5}2·2MeCN (10·2MeCN) and [Co(NCMe)2L5]2[CoBr3(NCMe)]2 (11), [FeBr(NCMe)L5]2·2MeCN (12·2MeCN) where L5H = 2,6-(CHO)2-4-tBu-C6H2OH, as well as the chelate-free salt [Fe(NCMe)6][FeBr3OFeBr3] (13) have been isolated and structurally characterized. The ability of these complexes to act as catalysts for the ring opening polymerisation (ROP) of ε-caprolactone (ε-CL) and δ-valerolactone (δ-VL) was investigated, as well as co-polymerisation of ε-CL with rac-lactide (r-LA) and vice versa.
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Affiliation(s)
- Kuiyuan Wang
- Plastics Collaboratory, Department of Chemistry, University of Hull, HU6 7RX, UK.
| | - Timothy J Prior
- Plastics Collaboratory, Department of Chemistry, University of Hull, HU6 7RX, UK.
| | - David L Hughes
- School of Chemistry, University of East Anglia, Norwich, NR4 7TJ, UK
| | | | - Carl Redshaw
- Plastics Collaboratory, Department of Chemistry, University of Hull, HU6 7RX, UK.
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13
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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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14
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Deng S, Diaconescu PL. A switchable dimeric yttrium complex and its three catalytic states in ring opening polymerization. Inorg Chem Front 2021. [DOI: 10.1039/d0qi01479f] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
A dimeric yttrium phenoxide complex can be oxidized in a stepwise fashion to access three oxidation states. The three states show different activity in the ring opening polymerization of cyclic esters and epoxides.
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Affiliation(s)
- Shijie Deng
- University of California
- Los Angeles
- Department of Chemistry and Biochemistry
- Los Angeles
- USA
| | - Paula L. Diaconescu
- University of California
- Los Angeles
- Department of Chemistry and Biochemistry
- Los Angeles
- USA
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15
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Dong HT, Chalkley MJ, Oyala PH, Zhao J, Alp EE, Hu MY, Peters JC, Lehnert N. Exploring the Limits of Dative Boratrane Bonding: Iron as a Strong Lewis Base in Low-Valent Non-Heme Iron-Nitrosyl Complexes. Inorg Chem 2020; 59:14967-14982. [PMID: 32989992 PMCID: PMC7640944 DOI: 10.1021/acs.inorgchem.0c01686] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
We previously reported the synthesis and preliminary characterization of a unique series of low-spin (ls) {FeNO}8-10 complexes supported by an ambiphilic trisphosphineborane ligand, [Fe(TPB)(NO)]+/0/-. Herein, we use advanced spectroscopic techniques and density functional theory (DFT) calculations to extract detailed information as to how the bonding changes across the redox series. We find that, in spite of the highly reduced nature of these complexes, they feature an NO+ ligand throughout with strong Fe-NO π-backbonding and essentially closed-shell electronic structures of their FeNO units. This is enabled by an Fe-B interaction that is present throughout the series. In particular, the most reduced [Fe(TPB)(NO)]- complex, an example of a ls-{FeNO}10 species, features a true reverse dative Fe → B bond where the Fe center acts as a strong Lewis-base. Hence, this complex is in fact electronically similar to the ls-{FeNO}8 system, with two additional electrons "stored" on site in an Fe-B single bond. The outlier in this series is the ls-{FeNO}9 complex, due to spin polarization (quantified by pulse EPR spectroscopy), which weakens the Fe-NO bond. These data are further contextualized by comparison with a related N2 complex, [Fe(TPB)(N2)]-, which is a key intermediate in Fe(TPB)-catalyzed N2 fixation. Our present study finds that the Fe → B interaction is key for storing the electrons needed to achieve a highly reduced state in these systems, and highlights the pitfalls associated with using geometric parameters to try to evaluate reverse dative interactions, a finding with broader implications to the study of transition metal complexes with boratrane and related ligands.
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Affiliation(s)
- Hai T. Dong
- Department of Chemistry and Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Matthew J. Chalkley
- Department of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Paul H. Oyala
- Department of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Jiyong Zhao
- Advanced Photon Source (APS), Argonne National Laboratory (ANL), Argonne, Illinois 60439, United States
| | - E. Ercan Alp
- Advanced Photon Source (APS), Argonne National Laboratory (ANL), Argonne, Illinois 60439, United States
| | - Michael Y. Hu
- Advanced Photon Source (APS), Argonne National Laboratory (ANL), Argonne, Illinois 60439, United States
| | - Jonas C. Peters
- Department of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Nicolai Lehnert
- Department of Chemistry and Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
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16
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Regenauer NI, Jänner S, Wadepohl H, Roşca D. Ein redoxaktives, heterobimetallisches N‐heterocyclisches Carben auf Basis eines Bis(imino)pyrazin‐Liganden. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202005865] [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)
- Nicolas I. Regenauer
- Anorganisch-Chemisches Insitut Universität Heidelberg Im Neuenheimer Feld 276 69120 Heidelberg Deutschland
| | - Sven Jänner
- Anorganisch-Chemisches Insitut Universität Heidelberg Im Neuenheimer Feld 276 69120 Heidelberg Deutschland
| | - Hubert Wadepohl
- Anorganisch-Chemisches Insitut Universität Heidelberg Im Neuenheimer Feld 276 69120 Heidelberg Deutschland
| | - Dragoş‐Adrian Roşca
- Anorganisch-Chemisches Insitut Universität Heidelberg Im Neuenheimer Feld 276 69120 Heidelberg Deutschland
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17
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Regenauer NI, Jänner S, Wadepohl H, Roşca D. A Redox-Active Heterobimetallic N-Heterocyclic Carbene Based on a Bis(imino)pyrazine Ligand Scaffold. Angew Chem Int Ed Engl 2020; 59:19320-19328. [PMID: 32672368 PMCID: PMC7590088 DOI: 10.1002/anie.202005865] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Indexed: 11/11/2022]
Abstract
A new redox-active N-heterocyclic carbene (NHC) architecture is obtained using N-methylated pyrazinediimine iron complexes as precursors. The new species exhibit strong π-accepting/σ-donating properties and are able to ligate two metal centres simultaneously. The redox activity was demonstrated by the reversible chemical oxidation of a heterobimetallic Fe0 /RhI example, which affords an isolable ligand-based radical cation. The reversible redox process was then applied in the catalytic hydrosilylation of 4,4'-difluorobenzophenone, where the reaction rate could be reversibly controlled as a function of the catalyst oxidation state. The new NHC exhibits high electrophilicity and nucleophilicity, which was demonstrated in the reversible activation of alcohols and amines. The electronic structure of the resulting complexes was investigated through various spectroscopic and computational methods.
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Affiliation(s)
- Nicolas I. Regenauer
- Anorganisch-Chemisches InstitutUniversität HeidelbergIm Neuenheimer Feld 27669120HeidelbergGermany
| | - Sven Jänner
- Anorganisch-Chemisches InstitutUniversität HeidelbergIm Neuenheimer Feld 27669120HeidelbergGermany
| | - Hubert Wadepohl
- Anorganisch-Chemisches InstitutUniversität HeidelbergIm Neuenheimer Feld 27669120HeidelbergGermany
| | - Dragoş‐Adrian Roşca
- Anorganisch-Chemisches InstitutUniversität HeidelbergIm Neuenheimer Feld 27669120HeidelbergGermany
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18
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Andrea KA, Kerton FM. Iron-catalyzed reactions of CO2 and epoxides to yield cyclic and polycarbonates. Polym J 2020. [DOI: 10.1038/s41428-020-00395-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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19
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Reinhart ED, Jordan RF. Synthesis and Ethylene Reactivity of Dinuclear Iron and Cobalt Complexes Supported by Macrocyclic Bis(pyridine-diimine) Ligands Containing o-Terphenyl Linkers. Organometallics 2020. [DOI: 10.1021/acs.organomet.0c00211] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Erik D. Reinhart
- Department of Chemistry, The University of Chicago, 5735 South Ellis Avenue, Chicago, Illinois 60637, United States
| | - Richard F. Jordan
- Department of Chemistry, The University of Chicago, 5735 South Ellis Avenue, Chicago, Illinois 60637, United States
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20
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Qin L, Cheng F, Eisen MS, Chen X. Unexpected substituent’s effects on catalytic activity in the ring-opening polymerization of ε-CL and δ-VL catalyzed by β-pyridyl-enamino Al complexes. Eur Polym J 2020. [DOI: 10.1016/j.eurpolymj.2020.109626] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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21
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Peterson PO, Rummelt SM, Wile BM, Stieber SCE, Zhong H, Chirik PJ. Direct Observation of Transmetalation from a Neutral Boronate Ester to a Pyridine(diimine) Iron Alkoxide. Organometallics 2020; 39:201-205. [PMID: 32728308 DOI: 10.1021/acs.organomet.9b00733] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Transmetallation of the neutral boronate esters, (2-benzofuranyl)BPin and (2-benzofuranyl)BNeo (Pin = pinacolato, Neo = neopentylglycolato) to a representative pyridine(diimine) iron alkoxide complex, (iPrPDI)FeOEt (iPrPDI = 2,6-(2,6-iPr2-C6H3N=CMe)2C5H3N; R = Me, Et, SiMe3), to yield the corresponding iron benzofuranyl derivative was studied. Synthesis of the requisite iron alkoxide complexes was accomplished either by salt metathesis between (iPrPDI)FeCl and NaOR (R = Me, Et, SiMe3) or by protonation of the iron alkyl, (iPrPDI)FeCH2SiMe3, by the free alcohol R'OH (R' = Me, Et). A combination of magnetic measurements, X-ray diffraction, NMR and Mössbauer spectroscopies and DFT calculations identified each (iPrPDI)FeOR compound as an essentially planar, high-spin, S = 3/2 compound engaged in antiferromagnetic coupling with a radical anion on the chelate (S Total = 3/2; S Fe = 2, S PDI = 1/2). The resulting iron benzofuranyl product, (iPrPDI)Fe(2-benzofuranyl) was characterized by X-ray diffraction and in combination with magnetic measurements, spectroscopic and computational data, was identified as an overall S = 1/2 compound, demonstrating that a net spin-state change accompanies transmetallation (S Fe = 1, S PDI = 1/2). These findings may be relevant to further development of iron-catalyzed Suzuki-Miyaura cross-coupling with neutral boronate esters and alkoxide bases.
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Affiliation(s)
- Paul O Peterson
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Stephan M Rummelt
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Bradley M Wile
- 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
| | - Hongyu Zhong
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Paul J Chirik
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
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22
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Xu X, Luo G, Hou Z, Diaconescu PL, Luo Y. Theoretical insight into the redox-switchable activity of group 4 metal complexes for the ring-opening polymerization of ε-caprolactone. Inorg Chem Front 2020. [DOI: 10.1039/c9qi01466g] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
DFT calculations indicate that the Lewis acidity of the catalytic metal center M (Ti, Zr, Hf) explains the redox-switchable activity observed for the ring-opening polymerization of ε-caprolactone by ferrocene derived metal complexes.
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Affiliation(s)
- Xiaowei Xu
- State Key Laboratory of Fine Chemicals
- School of Chemical Engineering
- Dalian University of Technology
- Dalian 116024
- China
| | - Gen Luo
- State Key Laboratory of Fine Chemicals
- School of Chemical Engineering
- Dalian University of Technology
- Dalian 116024
- China
| | - Zhaomin Hou
- Organometallic Chemistry Laboratory
- RIKEN Cluster for Pioneering Research
- and Advanced Catalysis Research Group
- RIKEN Center for Sustainable Resource Science
- Wako
| | - Paula L. Diaconescu
- Department of Chemistry and Biochemistry
- University of California
- Los Angeles
- Los Angeles
- USA
| | - Yi Luo
- State Key Laboratory of Fine Chemicals
- School of Chemical Engineering
- Dalian University of Technology
- Dalian 116024
- China
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23
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Lai A, Hern ZC, Diaconescu PL. Switchable Ring‐Opening Polymerization by a Ferrocene Supported Aluminum Complex. ChemCatChem 2019. [DOI: 10.1002/cctc.201900747] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Amy Lai
- Department of Chemistry and Biochemistry University of California, Los Angeles 607 Charles E. Young Drive East Los Angeles CA 90095 USA
| | - Zachary C. Hern
- Department of Chemistry and Biochemistry University of California, Los Angeles 607 Charles E. Young Drive East Los Angeles CA 90095 USA
| | - Paula L. Diaconescu
- Department of Chemistry and Biochemistry University of California, Los Angeles 607 Charles E. Young Drive East Los Angeles CA 90095 USA
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24
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Champouret Y, Hashmi OH, Visseaux M. Discrete iron-based complexes: Applications in homogeneous coordination-insertion polymerization catalysis. Coord Chem Rev 2019. [DOI: 10.1016/j.ccr.2019.03.015] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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25
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Kawamura A, Filatov AS, Anderson JS. Sulfonate‐Ligated Coordination Polymers Incorporating Paramagnetic Transition Metals. Eur J Inorg Chem 2019. [DOI: 10.1002/ejic.201900285] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Airi Kawamura
- Department of Chemistry The University of Chicago 929 E. 57th St 60637 Chicago IL USA
| | - Alexander S. Filatov
- Department of Chemistry The University of Chicago 929 E. 57th St 60637 Chicago IL USA
| | - John S. Anderson
- Department of Chemistry The University of Chicago 929 E. 57th St 60637 Chicago IL USA
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26
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Hakey BM, Darmon JM, Zhang Y, Petersen JL, Milsmann C. Synthesis and Electronic Structure of Neutral Square-Planar High-Spin Iron(II) Complexes Supported by a Dianionic Pincer Ligand. Inorg Chem 2019; 58:1252-1266. [PMID: 30608668 DOI: 10.1021/acs.inorgchem.8b02730] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Two square-planar high-spin FeII complexes bearing a dianionic pyridine dipyrrolate pincer ligand and a diethyl ether or tetrahydrofuran ligand were synthesized and structurally characterized, and their electronic structures were elucidated by a combined spectroscopic and computational approach. In contrast to previous examples, the S = 2 ground states of these square-planar FeII complexes do not require an overall anionic charge of the compounds or incorporation of alkali metal cations. The tetrahydrofuran complex exhibits an equilibrium between four- and five-coordinate species in solution, which was supported by 1H NMR and 57Fe Mössbauer spectroscopy and comparison to a structurally characterized five-coordinate pyridine dipyrrolate iron bis-pyridine adduct. A detailed computational analysis of the electronic structures of the four- and five-coordinate species via density functional theory provides insight into the origins of the unusual ground state configurations for FeII in a square-planar ligand field and explains the associated characteristic spectroscopic parameters.
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Affiliation(s)
- Brett M Hakey
- C. Eugene Bennett Department of Chemistry , West Virginia University , 100 Prospect Street , Morgantown , West Virginia 26506 , United States
| | - Jonathan M Darmon
- Department of Chemistry , Princeton University , Princeton , New Jersey 08544 , United States
| | - Yu Zhang
- C. Eugene Bennett Department of Chemistry , West Virginia University , 100 Prospect Street , Morgantown , West Virginia 26506 , United States
| | - Jeffrey L Petersen
- C. Eugene Bennett Department of Chemistry , West Virginia University , 100 Prospect Street , Morgantown , West Virginia 26506 , United States
| | - Carsten Milsmann
- C. Eugene Bennett Department of Chemistry , West Virginia University , 100 Prospect Street , Morgantown , West Virginia 26506 , United States
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27
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Praban S, Piromjitpong P, Balasanthiran V, Jayaraj S, Chisholm MH, Tantirungrotechai J, Phomphrai K. Highly efficient metal(iii) porphyrin and salen complexes for the polymerization of rac-lactide under ambient conditions. Dalton Trans 2019; 48:3223-3230. [DOI: 10.1039/c8dt04699a] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Metal(iii) complexes supported by porphyrin and salen ligands were highly efficient for rac-lactide polymerization at room temperature giving isotactic-enriched PLA.
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Affiliation(s)
- Siriwan Praban
- Center for Catalysis
- Department of Chemistry and Center of Excellence for Innovation in Chemistry
- Faculty of Science
- Mahidol University
- Bangkok 10400
| | - Parichat Piromjitpong
- Center for Catalysis
- Department of Chemistry and Center of Excellence for Innovation in Chemistry
- Faculty of Science
- Mahidol University
- Bangkok 10400
| | | | - Savithra Jayaraj
- Department of Chemistry and Biochemistry
- The Ohio State University
- Columbus
- USA
| | - Malcolm H. Chisholm
- Department of Chemistry and Biochemistry
- The Ohio State University
- Columbus
- USA
| | - Jonggol Tantirungrotechai
- Center for Catalysis
- Department of Chemistry and Center of Excellence for Innovation in Chemistry
- Faculty of Science
- Mahidol University
- Bangkok 10400
| | - Khamphee Phomphrai
- Department of Materials Science and Engineering
- School of Molecular Science and Engineering
- Vidyasirimedhi Institute of Science and Technology
- Wangchan
- Thailand
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28
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Driscoll OJ, Hafford-Tear CH, McKeown P, Stewart JA, Kociok-Köhn G, Mahon MF, Jones MD. The synthesis, characterisation and application of iron(iii)–acetate complexes for cyclic carbonate formation and the polymerisation of lactide. Dalton Trans 2019; 48:15049-15058. [DOI: 10.1039/c9dt03327k] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Cracking the whip: Simple iron(iii) acetate complexes have been applied to the catalytic cyclic carbonate formation and lactide ROP.
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29
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Fazekas E, Nichol GS, Garden JA, Shaver MP. Iron III Half Salen Catalysts for Atom Transfer Radical and Ring-Opening Polymerizations. ACS OMEGA 2018; 3:16945-16953. [PMID: 31458318 PMCID: PMC6643736 DOI: 10.1021/acsomega.8b02432] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Accepted: 11/22/2018] [Indexed: 06/10/2023]
Abstract
A series of monometallic pentacoordinate FeIII chloride complexes have been prepared and characterized by high-resolution mass spectrometry and elemental analysis. X-ray diffraction analysis showed that the bis-chelated FeIII complexes bear distorted trigonal bipyramidal geometries. The air- and moisture-stable FeIII complexes were screened as mediators in the reverse atom transfer radical polymerization (ATRP) of styrene and methyl methacrylate. Moderate to excellent control was achieved with dispersities as low as 1.1 for both poly(methyl methacrylate) and polystyrene. Kinetic studies showed living characteristics, and end group analysis revealed the presence of olefin-terminated polymer chains, suggesting catalytic chain transfer as a competing polymerization mechanism. Although the catalysts are not the fastest Fe ATRP mediators, they are robust and flexible. Using propylene oxide as an initiator, the complexes were active catalysts for the ring-opening polymerization of rac-lactide with moderate control. While the addition of propylene oxide has been reported as an efficient method of converting a metal-halide bond to a metal-alkoxide bond in situ, we show herein that this initiation mechanism can limit polymerization reproducibility and introduce an induction period.
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31
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Hu M, Zhang W, Ma W, Han F, Song W. Preparation of titanium complexes containing unsymmetric N2O2-ligands and their catalytic properties for polymerization of rac-lactide. POLYMER 2018. [DOI: 10.1016/j.polymer.2018.08.043] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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32
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Martínez J, Martínez de Sarasa Buchaca M, de la Cruz-Martínez F, Alonso-Moreno C, Sánchez-Barba LF, Fernandez-Baeza J, Rodríguez AM, Rodríguez-Diéguez A, Castro-Osma JA, Otero A, Lara-Sánchez A. Versatile organoaluminium catalysts based on heteroscorpionate ligands for the preparation of polyesters. Dalton Trans 2018; 47:7471-7479. [PMID: 29786721 DOI: 10.1039/c8dt01553h] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
A series of alkyl aluminium complexes based on heteroscorpionate ligands were designed as catalysts for the ring-opening polymerisation of cyclic esters and ring-opening copolymerisation of epoxides and anhydrides. Treatment of AlX3 (X = Me, Et) with ligands bpzbeH [bpzbe = 1,1-bis(3,5-dimethylpyrazol-1-yl)-3,3-dimethyl-2-butoxide], bpzteH [bpzte = 2,2-bis(3,5-dimethylpyrazol-1-yl)-1-para-tolylethoxide], and (R,R)-bpzmmH [(R,R)-bpzmm = (1R)-1-{(1R)-6,6-dimethyl-bicyclo[3.1.1]-2-hepten-2-yl}-2,2-bis(3,5-dimethylpyrazol-1-yl)ethoxide] for 2 hours at 0 °C afforded the mononuclear dialkyl aluminium complexes [AlMe2{κ2-bpzbe}] (1), [AlEt2{κ2-bpzbe}] (2), [AlMe2{κ2-(R,R)-bpzmm}] (3) and [AlEt2{κ2-(R,R)-bpzmm}] (4), and the dinuclear dialkyl complexes [AlMe2{κ2-bpzte}]2 (5) and [AlEt2{κ2-bpzte}]2 (6). The molecular structures of the new complexes were determined by spectroscopic methods and confirmed by X-ray crystallography. The alkyl-containing aluminium complexes can act as highly efficient single-component initiators for the ring-opening polymerisation of ε-caprolactone and l-lactide and for the ring-opening copolymerisation of cyclohexene oxide and phthalic anhydride to give a range of biodegradable polyesters.
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Affiliation(s)
- J Martínez
- Universidad de Castilla-La Mancha, Dpto. de Química Inorgánica, Orgánica y Bioquímica, Facultad de Ciencias y Tecnologías Químicas, 13071-Ciudad Real, Spain.
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33
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Daneshmand P, Jiménez-Santiago JL, Aragon--Alberti M, Schaper F. Catalytic-Site-Mediated Chain-End Control in the Polymerization of rac-Lactide with Copper Iminopyrrolide Complexes. Organometallics 2018. [DOI: 10.1021/acs.organomet.8b00196] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Pargol Daneshmand
- Centre in Green Chemistry and Catalysis, Department of Chemistry, Université de Montréal, C. P. 6128 Succ. Centre-Ville, Montréal, Quebec H3T 3J7, Canada
| | - José L. Jiménez-Santiago
- Centre in Green Chemistry and Catalysis, Department of Chemistry, Université de Montréal, C. P. 6128 Succ. Centre-Ville, Montréal, Quebec H3T 3J7, Canada
| | - Maxime Aragon--Alberti
- Centre in Green Chemistry and Catalysis, Department of Chemistry, Université de Montréal, C. P. 6128 Succ. Centre-Ville, Montréal, Quebec H3T 3J7, Canada
| | - Frank Schaper
- Centre in Green Chemistry and Catalysis, Department of Chemistry, Université de Montréal, C. P. 6128 Succ. Centre-Ville, Montréal, Quebec H3T 3J7, Canada
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34
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Mukherjee A, Pattanayak S, Sen Gupta S, Vanka K. What drives the H-abstraction reaction in bio-mimetic oxoiron-bTAML complexes? A computational investigation. Phys Chem Chem Phys 2018; 20:13845-13850. [PMID: 29717729 DOI: 10.1039/c8cp01333k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Monomeric iron-oxo units have been confirmed as intermediates involved in the C-H bond activation in various metallo-enzymes. Biomimetic oxoiron complexes of the biuret modified tetra-amido macrocyclic ligand (bTAML) have been demonstrated to oxidize a wide variety of unactivated C-H bonds. In the current work, density functional theory (DFT) has been employed to investigate the hydrogen abstraction (HAT) reactivity differences across a series of bTAML complexes. The cause for the differences in the HAT energy barriers has been found to be the relative changes in the energy of the frontier molecular orbitals (FMOs) induced by electronic perturbation.
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Affiliation(s)
- Anagh Mukherjee
- Physical and Material Chemistry Division, CSIR-National Chemical Laboratory, Pune-411008, India.
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35
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Affiliation(s)
- Changle Chen
- CAS Key Laboratory of Soft Matter Chemistry, iChEM (Collaborative Innovation Center of Chemistry for Energy Materials), Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei 230026, People’s Republic of China
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36
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Qi M, Dong Q, Wang D, Byers JA. Electrochemically Switchable Ring-Opening Polymerization of Lactide and Cyclohexene Oxide. J Am Chem Soc 2018; 140:5686-5690. [DOI: 10.1021/jacs.8b02171] [Citation(s) in RCA: 108] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Miao Qi
- Department of Chemistry, Eugene F. Merkert Chemistry Center, Boston College, 2609 Beacon Street, Chestnut Hill, Massachusetts 02467, United States
| | - Qi Dong
- Department of Chemistry, Eugene F. Merkert Chemistry Center, Boston College, 2609 Beacon Street, Chestnut Hill, Massachusetts 02467, United States
| | - Dunwei Wang
- Department of Chemistry, Eugene F. Merkert Chemistry Center, Boston College, 2609 Beacon Street, Chestnut Hill, Massachusetts 02467, United States
| | - Jeffery A. Byers
- Department of Chemistry, Eugene F. Merkert Chemistry Center, Boston College, 2609 Beacon Street, Chestnut Hill, Massachusetts 02467, United States
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37
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Ortuño MA, Dereli B, Chiaie KRD, Biernesser AB, Qi M, Byers JA, Cramer CJ. The Role of Alkoxide Initiator, Spin State, and Oxidation State in Ring-Opening Polymerization of ε-Caprolactone Catalyzed by Iron Bis(imino)pyridine Complexes. Inorg Chem 2018; 57:2064-2071. [PMID: 29381341 DOI: 10.1021/acs.inorgchem.7b02964] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Density functional theory (DFT) is employed to characterize in detail the mechanism for the ring-opening polymerization (ROP) of ε-caprolactone catalyzed by iron alkoxide complexes bearing redox-active bis(imino)pyridine ligands. The combination of iron with the non-innocent bis(imino)pyridine ligand permits comparison of catalytic activity as a function of oxidation state (and overall spin state). The reactivities of aryl oxide versus alkoxide initiators for the ROP of ε-caprolactone are also examined. An experimental test of a computational prediction reveals an Fe(III) bis(imino)pyridine bis-neopentoxide complex to be competent for ROP of ε-caprolactone.
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Affiliation(s)
- Manuel A Ortuño
- Department of Chemistry, Chemical Theory Center, and Supercomputing Institute, University of Minnesota , 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
| | - Büsra Dereli
- Department of Chemistry, Chemical Theory Center, and Supercomputing Institute, University of Minnesota , 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
| | - Kayla R Delle Chiaie
- Eugene F. Merkert Chemistry Center, Department of Chemistry, Boston College , 2609 Beacon Street, Chestnut Hill, Massachusetts 02467, United States
| | - Ashley B Biernesser
- Eugene F. Merkert Chemistry Center, Department of Chemistry, Boston College , 2609 Beacon Street, Chestnut Hill, Massachusetts 02467, United States
| | - Miao Qi
- Eugene F. Merkert Chemistry Center, Department of Chemistry, Boston College , 2609 Beacon Street, Chestnut Hill, Massachusetts 02467, United States
| | - Jeffery A Byers
- Eugene F. Merkert Chemistry Center, Department of Chemistry, Boston College , 2609 Beacon Street, Chestnut Hill, Massachusetts 02467, United States
| | - Christopher J Cramer
- Department of Chemistry, Chemical Theory Center, and Supercomputing Institute, University of Minnesota , 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
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Cozzolino M, Leo V, Tedesco C, Mazzeo M, Lamberti M. Salen, salan and salalen iron(iii) complexes as catalysts for CO2/epoxide reactions and ROP of cyclic esters. Dalton Trans 2018; 47:13229-13238. [DOI: 10.1039/c8dt03169j] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Salan, salen and salalen iron complexes as catalysts in CO2/epoxide reactions and in the ROP of ε-caprolactone and l-lactide.
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Affiliation(s)
| | - Vincenza Leo
- Dipartimento di Chimica e Biologia “A. Zambelli”
- Università di Salerno
- Fisciano
- Italy
| | - Consiglia Tedesco
- Dipartimento di Chimica e Biologia “A. Zambelli”
- Università di Salerno
- Fisciano
- Italy
| | - Mina Mazzeo
- Dipartimento di Chimica e Biologia “A. Zambelli”
- Università di Salerno
- Fisciano
- Italy
| | - Marina Lamberti
- Dipartimento di Fisica “E. Caianiello”
- Università di Salerno
- Fisciano
- Italy
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39
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Tamura M, Matsuda K, Nakagawa Y, Tomishige K. Ring-opening polymerization of trimethylene carbonate to poly(trimethylene carbonate) diol over a heterogeneous high-temperature calcined CeO2 catalyst. Chem Commun (Camb) 2018; 54:14017-14020. [DOI: 10.1039/c8cc08405j] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
CeO2 calcined at 1273 K was an effective reusable heterogeneous catalyst for the synthesis of poly(trimethylene carbonate) diol by ring-opening polymerization of trimethylene carbonate under neat conditions without any additives.
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