1
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Thierry T, Giuso V, Polo F, Mercandelli P, Chen YT, Chang CH, Mauro M, Bellemin-Laponnaz S. A stable and true-blue emissive hexacoordinate Si(IV) N-heterocyclic carbene complex and its use in organic light-emitting diodes. Dalton Trans 2024; 53:6445-6450. [PMID: 38511259 DOI: 10.1039/d4dt00420e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/22/2024]
Abstract
A neutral hexacoordinate Si(IV) complex containing two tridentate N-heterocyclic carbene ligands is synthesised and characterized by X-ray crystallography, optical spectroscopy, electrochemistry and computational methods. The stable compound exhibits remarkable deep-blue photoluminescence particularly in the solid state, which enables its use as an electroluminescent material in organic light-emitting diodes.
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Affiliation(s)
- Thibault Thierry
- Institut de Physique et Chimie des Matériaux de Strasbourg UMR 7504 - Université de Strasbourg & CNRS, 23 rue du Loess, 67034 Strasbourg, France.
| | - Valerio Giuso
- Institut de Physique et Chimie des Matériaux de Strasbourg UMR 7504 - Université de Strasbourg & CNRS, 23 rue du Loess, 67034 Strasbourg, France.
| | - Federico Polo
- Department of Molecular Sciences and Nanosystems, Ca' Foscari University of Venice, Via Torino 155, 30172 Venice, Italy
- European Centre for Living Technology (ECLT), Ca' Foscari University of Venice, Ca' Bottacin, 30124, Venice, Italy
| | | | - Yi-Ting Chen
- Department of Electrical Engineering, Yuan Ze University, 32003 Taoyuan, Taiwan
| | - Chih-Hao Chang
- Department of Electrical Engineering, Yuan Ze University, 32003 Taoyuan, Taiwan
| | - Matteo Mauro
- Institut de Physique et Chimie des Matériaux de Strasbourg UMR 7504 - Université de Strasbourg & CNRS, 23 rue du Loess, 67034 Strasbourg, France.
| | - Stéphane Bellemin-Laponnaz
- Institut de Physique et Chimie des Matériaux de Strasbourg UMR 7504 - Université de Strasbourg & CNRS, 23 rue du Loess, 67034 Strasbourg, France.
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2
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Neururer F, Huter K, Seidl M, Hohloch S. Reactivity and Structure of a Bis-phenolate Niobium NHC Complex. ACS ORGANIC & INORGANIC AU 2022; 3:59-71. [PMID: 36748079 PMCID: PMC9896488 DOI: 10.1021/acsorginorgau.2c00028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Revised: 11/18/2022] [Accepted: 11/21/2022] [Indexed: 12/12/2022]
Abstract
We report the facile synthesis of a rare niobium(V) imido NHC complex with a dianionic OCO-pincer benzimidazolylidene ligand (L 1 ) with the general formula [NbL 1 (N t Bu)PyCl] 1-Py. We achieved this by in situ deprotonation of the corresponding azolium salt [H 3 L 1 ][Cl] and subsequent reaction with [Nb(N t Bu)Py 2 Cl 3 ]. The pyridine ligand in 1-Py can be removed by the addition of B(C6F5)3 as a strong Lewis acid leading to the formation of the pyridine-free complex 1. In contrast to similar vanadium(V) complexes, complex 1-Py was found to be a good precursor for various salt metathesis reactions, yielding a series of chalcogenido and pnictogenido complexes with the general formula [ NbL 1 (N t Bu)Py(EMes)] (E = O (2), S (3), NH (4), and PH (5)). Furthermore, complex 1-Py can be converted to alkyl complex (6) with 1 equiv of neosilyl lithium as a transmetallation agent. Addition of a second equivalent yields a new trianionic supporting ligand on the niobium center (7) in which the benzimidazolylidene ligand is alkylated at the former carbene carbon atom. The latter is an interesting chemically "noninnocent" feature of the benzimidazolylidene ligand potentially useful in catalysis and atom transfer reactions. Addition of mesityl lithium to 1-Py gives the pyridine-free aryl complex 8, which is stable toward "overarylation" by an additional equivalent of mesityl lithium. Electrochemical investigation revealed that complexes 1-Py and 1 are inert toward reduction in dichloromethane but show two irreversible reduction processes in tetrahydrofuran as a solvent. However, using standard reduction agents, e.g., KC8, K-mirror, and Na/Napht, no reduced products could be isolated. All complexes have been thoroughly studied by various techniques, including 1H-, 13C{1H}-, and 1H-15N HMBC NMR spectroscopy, IR spectroscopy, and X-ray diffraction analysis.
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3
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Ring opening polymerization of lactide promoted by Zinc and Magnesium complexes with a N-heterocyclic carbene-phenoxy-imine hybrid non-innocent ligand. MOLECULAR CATALYSIS 2022. [DOI: 10.1016/j.mcat.2022.112799] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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4
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Stereoselective synthesis of biodegradable polymers by salen-type metal catalysts. Sci China Chem 2022. [DOI: 10.1007/s11426-022-1377-5] [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]
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5
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Poland EM, Ho CC. Photoactive N‐Heterocyclic Carbene Transition Metal Complexes in Bond‐Forming Photocatalysis: State‐of‐the‐Art and Opportunities. Appl Organomet Chem 2022. [DOI: 10.1002/aoc.6746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Eve M. Poland
- School of Natural Sciences – Chemistry University of Tasmania Hobart Tasmania Australia
| | - Curtis C. Ho
- School of Natural Sciences – Chemistry University of Tasmania Hobart Tasmania Australia
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6
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Watt FA, Sieland B, Dickmann N, Schoch R, Herbst-Irmer R, Ott H, Paradies J, Kuckling D, Hohloch S. Coupling of CO 2 and epoxides catalysed by novel N-fused mesoionic carbene complexes of nickel(II). Dalton Trans 2021; 50:17361-17371. [PMID: 34788774 DOI: 10.1039/d1dt03311e] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report the syntheses of two rigid mesoionic carbene (MIC) ligands with a carbazole backbone via an intramolecular Finkelstein-cyclisation cascade and investigate their coordination behavior towards nickel(II) acetate. Despite the nickel(II) carbene complexes 4a,b showing only minor differences in their chemical composition, they display curious differences in their chemical properties, e.g. solubility. Furthermore, the potential of these novel MIC complexes in the coupling of carbon dioxide and epoxides as well as the differences in reactivity compared to classical NHC-derived complexes are evaluated.
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Affiliation(s)
- Fabian A Watt
- Paderborn University, Faculty of Science, Department of Chemistry, Warburger Straße 100, 33098 Paderborn, Germany
| | - Benedikt Sieland
- Paderborn University, Faculty of Science, Department of Chemistry, Warburger Straße 100, 33098 Paderborn, Germany
| | - Nicole Dickmann
- Paderborn University, Faculty of Science, Department of Chemistry, Warburger Straße 100, 33098 Paderborn, Germany
| | - Roland Schoch
- Paderborn University, Faculty of Science, Department of Chemistry, Warburger Straße 100, 33098 Paderborn, Germany
| | - Regine Herbst-Irmer
- University of Göttingen, Institute of Inorganic Chemistry, Tammannstraße 4, 37077 Göttingen, Germany
| | - Holger Ott
- Bruker AXS GmbH, Östliche Rheinbrückenstraße 49, 76187 Karlsruhe, Germany
| | - Jan Paradies
- Paderborn University, Faculty of Science, Department of Chemistry, Warburger Straße 100, 33098 Paderborn, Germany
| | - Dirk Kuckling
- Paderborn University, Faculty of Science, Department of Chemistry, Warburger Straße 100, 33098 Paderborn, Germany
| | - Stephan Hohloch
- University of Innsbruck, Faculty of Chemistry and Pharmacy, Institute of General, Inorganic and Theoretical Chemistry, Innrain 80-82, 6020 Innsbruck, Austria.
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7
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Bawari D, Volodarsky S, Ginzburg Y, Jaiswal K, Joshi P, Dobrovetsky R. Phosphorus mediated imidazolinium to oxazolium ring rearrangement. Dalton Trans 2021; 50:16478-16482. [PMID: 34730572 DOI: 10.1039/d1dt03363h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
An unexpected rearrangement occurred when an imidazolinium based OCO pincer-type ligand (1) reacted with PCl3 producing a chlorophosphine with a pendant oxazolium "arm" (3). The mechanism of this rearrangement was studied both experimentally and by density functional theory (DFT) computations. The deprotonation of 3 led to further unexpected results.
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Affiliation(s)
- Deependra Bawari
- School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978, Israel.
| | - Solomon Volodarsky
- School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978, Israel.
| | - Yael Ginzburg
- School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978, Israel.
| | - Kuldeep Jaiswal
- School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978, Israel.
| | - Pooja Joshi
- School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978, Israel.
| | - Roman Dobrovetsky
- School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978, Israel.
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8
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Neururer F, Liu S, Leitner D, Baltrun M, Fisher KR, Kopacka H, Wurst K, Daumann LJ, Munz D, Hohloch S. Mesoionic Carbenes in Low- to High-Valent Vanadium Chemistry. Inorg Chem 2021; 60:15421-15434. [PMID: 34590834 PMCID: PMC8527456 DOI: 10.1021/acs.inorgchem.1c02087] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Indexed: 12/12/2022]
Abstract
We report the synthesis of vanadium(V) oxo complex 1 with a pincer-type dianionic mesoionic carbene (MIC) ligand L1 and the general formula [VOCl(L1)]. A comparison of the structural (SC-XRD), electronic (UV-vis), and electrochemical (cyclic voltammetry) properties of 1 with the benzimidazolinylidene congener 2 (general formula [VOCl(L2)]) shows that the MIC is a stronger donor also for early transition metals with low d-electron population. Since electrochemical studies revealed both complexes to be reversibly reduced, the stronger donor character of MICs was not only demonstrated for the vanadium(V) but also for the vanadium(IV) oxidation state by isolating the reduced vanadium(IV) complexes [Co(Cp*)2][1] and [Co(Cp*)2][2] ([Co(Cp*)2] = decamethylcobaltocenium). The electronic structures of the compounds were investigated by computational methods. Complex 1 was found to be a moderate precursor for salt metathesis reactions, showing selective reactivity toward phenolates or secondary amides, but not toward primary amides and phosphides, thiophenols, or aryls/alkyls donors. Deoxygenation with electron-rich phosphines failed to give the desired vanadium(III) complex. However, treatment of the deprotonated ligand precursor with vanadium(III) trichloride resulted in the clean formation of the corresponding MIC vanadium(III) complex 6, which undergoes a clean two-electron oxidation with organic azides yielding the corresponding imido complexes. The reaction with TMS-N3 did not afford a nitrido complex, but instead the imido complex 10. This study reveals that, contrary to popular belief, MICs are capable of supporting early transition-metal complexes in a variety of oxidation states, thus making them promising candidates for the activation of small molecules and redox catalysis.
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Affiliation(s)
- Florian
R. Neururer
- Institute
of Inorganic, General and Theoretical Chemistry, University of Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
| | - Shenyu Liu
- Faculty
of Science, Department of Chemistry, University
of Paderborn, Warburger Straße 100, 33098 Paderborn, Germany
| | - Daniel Leitner
- Institute
of Inorganic, General and Theoretical Chemistry, University of Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
| | - Marc Baltrun
- Faculty
of Science, Department of Chemistry, University
of Paderborn, Warburger Straße 100, 33098 Paderborn, Germany
| | - Katherine R. Fisher
- Department
Chemie, Ludwigs-Maximilians-University Munich, Butenandtstraße 5-13 Haus D, 81377 Munich, Germany
| | - Holger Kopacka
- Institute
of Inorganic, General and Theoretical Chemistry, University of Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
| | - Klaus Wurst
- Institute
of Inorganic, General and Theoretical Chemistry, University of Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
| | - Lena J. Daumann
- Department
Chemie, Ludwigs-Maximilians-University Munich, Butenandtstraße 5-13 Haus D, 81377 Munich, Germany
| | - Dominik Munz
- Fakultät
NT, Inorganic Chemistry: Coordination Chemistry, Saarland University, Campus C4.1, 66123 Saarbrücken, Germany
| | - Stephan Hohloch
- Institute
of Inorganic, General and Theoretical Chemistry, University of Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
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9
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Roux SL, Ori G, Bellemin-Laponnaz S, Boero M. Tridentate complexes of group 4 bearing bis-aryloxide N-heterocyclic carbene ligand: Structure, spin density and charge states. Chem Phys Lett 2021. [DOI: 10.1016/j.cplett.2021.138888] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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10
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Synthesis and Characterization of New Cyclam-Based Zr(IV) Alkoxido Derivatives. REACTIONS 2021. [DOI: 10.3390/reactions2030021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
In this study, new mono- and di-alkoxido zirconium(IV) complexes supported by tetradentate dianionic cyclam ligands were synthesized and characterized. These compounds were obtained by reaction of the parent Zr(IV) dichlorido species with one or two equivalents of the corresponding lithium alkoxido, whereas (3,5-Me2Bn2Cyclam)Zr(OPh)2 was prepared by protonolysis of the orthometallated species (3,5-Me-C6H4CH2)2Cyclam)Zr with phenol. The solid-state molecular structures of (Bn2Cyclam)ZrCl(OtBu) and (4-tBuBn2Cyclam)Zr(OiPr)2 show a trigonal prismatic geometry around the metal centers. (Bn2Cyclam)Zr(SPh)(OtBu) and (Bn2Cyclam)ZrMe(OiPr) were prepared by reaction of (Bn2Cyclam)ZrCl(OR) (R = iPr, tBu) with one equivalent of LiSPh or MeMgCl, respectively. The reactions of (Bn2Cyclam)Zr(OiPr)2 and (4-tBuBn2Cyclam)Zr(OiPr)2 with carbon dioxide suggested the formation of species that correspond to the addition of four CO2 molecules.
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11
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12
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Turner ZR, Lamb JV, Robinson TP, Mandal D, Buffet JC, O Hare D. Ring-opening polymerisation of l- and rac-lactide using group 4 permethylpentalene aryloxides and alkoxides. Dalton Trans 2021; 50:4805-4818. [PMID: 33877178 DOI: 10.1039/d1dt00252j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A new family of group 4 permethylpentalene (C8Me62-; Pn*) aryloxide and alkoxide complexes have been synthesised and fully characterised by multinuclear NMR spectroscopy and single-crystal X-ray diffraction; (η8-C8Me6)Zr(OR)2 (R = tBu (1), 2,6-Me-C6H3 (2), 2,6-iPr-C6H3 (3) and 4-OMe-C6H4 (4)), (η8-C8Me6)Zr (OR) (R = 2,6-tBu-C6H3 (5) and 2,6-tBu-4-Me-C6H2 (6)), (η8-C8Me6)ZrCp(OR) (R = tBu (7), 2,6-Me-C6H3 (8) and 2,6-iPr-C6H3 (9)), (η8-C8Me6)TiCp(O-2,6-Me-C6H3) (10) and (η8-C8Me6)ZrCpMe(OR) (R = 2,6-Me-C6H3 (11), 2,6-iPr-C6H3 (12) and 2,4-tBu-C6H3 (13)). 2, 3, 6, 7, 9, 10 and 12 were studied as initiators for the ring-opening polymerisation (ROP) of l-lactide, and 2, 3, 6, 7 and 10 were studied as initiators for the ROP of rac-lactide. 3 was found to be the most active initiator for the ROP of l-lactide (kobs = 0.35 h-1) and 2 for the ROP of rac-lactide (kobs = 0.21 h-1). These initiators produced isotactic PLA for the ROP of l-lactide and moderately heterotactic enriched (maximum Pr of 0.69) or atactic PLA for the ROP of rac-lactide with polymer chains consisting of polylactic acid repeat units with -OR and -OH end groups.
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Affiliation(s)
- Zoë R Turner
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, 12, Mansfield Road, OX1 3TA, Oxford, UK.
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13
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Balint A, Naumann S. A comparison of zwitterionic and anionic mechanisms in the dual-catalytic polymerization of lactide. Polym Chem 2021. [DOI: 10.1039/d1py00992c] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Two different polymerization mechanisms for lactide are selectivity addressed to illuminate the respective role of organobase and Lewis acid component.
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Affiliation(s)
- Alexander Balint
- University of Stuttgart, Institute of Polymer Chemistry, 70569 Stuttgart, Germany
| | - Stefan Naumann
- University of Stuttgart, Institute of Polymer Chemistry, 70569 Stuttgart, Germany
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14
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Payne J, McKeown P, Driscoll O, Kociok-Köhn G, Emanuelsson EAC, Jones MD. Make or break: Mg( ii)- and Zn( ii)-catalen complexes for PLA production and recycling of commodity polyesters. Polym Chem 2021. [DOI: 10.1039/d0py01519a] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A series of Mg(ii) and Zn(ii) catalen complexes have been prepared for PLA formation and recycling.
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Affiliation(s)
- Jack Payne
- Centre for Sustainable and Circular Technologies
- University of Bath
- Claverton Down
- UK
| | - Paul McKeown
- Department of Chemistry
- University of Bath
- Claverton Down
- UK
| | | | | | | | - Matthew D. Jones
- Centre for Sustainable and Circular Technologies
- University of Bath
- Claverton Down
- UK
- Department of Chemistry
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15
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Roymuhury SK, Mandal M, Chakraborty D, Ramkumar V. Homoleptic titanium and zirconium complexes exhibiting unusual Oiminol–metal coordination: application in stereoselective ring-opening polymerization of lactide. Polym Chem 2021. [DOI: 10.1039/d1py00237f] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The synthesis and characterization of novel homoleptic Ti and Zr complexes with tridentate ONO-type Schiff base ligands and their catalytic activities towards the ring-opening polymerization (ROP) of lactide are reported.
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Affiliation(s)
- Sagnik K. Roymuhury
- Department of Chemistry
- Indian Institute of Technology Patna
- Bihta 801103
- India
| | - Mrinmay Mandal
- Department of Chemistry
- Indian Institute of Technology Patna
- Bihta 801103
- India
| | - Debashis Chakraborty
- Department of Chemistry
- Indian Institute of Technology Madras
- Chennai-600 036
- India
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16
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Chatterjee B, Chang W, Werlé C. Molecularly Controlled Catalysis – Targeting Synergies Between Local and Non‐local Environments. ChemCatChem 2020. [DOI: 10.1002/cctc.202001431] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Basujit Chatterjee
- Max Planck Institute for Chemical Energy Conversion Stiftstr. 34–36 45470 Mülheim an der Ruhr Germany
- Ruhr University Bochum Universitätsstr. 150 44801 Bochum Germany
| | - Wei‐Chieh Chang
- Max Planck Institute for Chemical Energy Conversion Stiftstr. 34–36 45470 Mülheim an der Ruhr Germany
- Ruhr University Bochum Universitätsstr. 150 44801 Bochum Germany
| | - Christophe Werlé
- Max Planck Institute for Chemical Energy Conversion Stiftstr. 34–36 45470 Mülheim an der Ruhr Germany
- Ruhr University Bochum Universitätsstr. 150 44801 Bochum Germany
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17
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Suresh L, Lalrempuia R, B. Ekeli J, Gillis-D’Hamers F, Törnroos KW, Jensen VR, Le Roux E. Unsaturated and Benzannulated N-Heterocyclic Carbene Complexes of Titanium and Hafnium: Impact on Catalysts Structure and Performance in Copolymerization of Cyclohexene Oxide with CO 2. Molecules 2020; 25:E4364. [PMID: 32977466 PMCID: PMC7582562 DOI: 10.3390/molecules25194364] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 09/18/2020] [Accepted: 09/21/2020] [Indexed: 01/13/2023] Open
Abstract
Tridentate, bis-phenolate N-heterocyclic carbenes (NHCs) are among the ligands giving the most selective and active group 4-based catalysts for the copolymerization of cyclohexene oxide (CHO) with CO2. In particular, ligands based on imidazolidin-2-ylidene (saturated NHC) moieties have given catalysts which exclusively form polycarbonate in moderate-to-high yields even under low CO2 pressure and at low copolymerization temperatures. Here, to evaluate the influence of the NHC moiety on the molecular structure of the catalyst and its performance in copolymerization, we extend this chemistry by synthesizing and characterizing titanium complexes bearing tridentate bis-phenolate imidazol-2-ylidene (unsaturated NHC) and benzimidazol-2-ylidene (benzannulated NHC) ligands. The electronic properties of the ligands and the nature of their bonds to titanium are studied using density functional theory (DFT) and natural bond orbital (NBO) analysis. The metal-NHC bond distances and bond strengths are governed by ligand-to-metal σ- and π-donation, whereas back-donation directly from the metal to the NHC ligand seems to be less important. The NHC π-acceptor orbitals are still involved in bonding, as they interact with THF and isopropoxide oxygen lone-pair donor orbitals. The new complexes are, when combined with [PPN]Cl co-catalyst, selective in polycarbonate formation. The highest activity, albeit lower than that of the previously reported Ti catalysts based on saturated NHC, was obtained with the benzannulated NHC-Ti catalyst. Attempts to synthesize unsaturated and benzannulated NHC analogues based on Hf invariably led, as in earlier work with Zr, to a mixture of products that include zwitterionic and homoleptic complexes. However, the benzannulated NHC-Hf complexes were obtained as the major products, allowing for isolation. Although these complexes selectively form polycarbonate, their catalytic performance is inferior to that of analogues based on saturated NHC.
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Affiliation(s)
- Lakshmi Suresh
- Department of Chemistry, University of Bergen, Allégaten 41, N-5007 Bergen, Norway; (L.S.); (R.L.); (J.B.E.); (F.G.-D.); (K.W.T.)
| | - Ralte Lalrempuia
- Department of Chemistry, University of Bergen, Allégaten 41, N-5007 Bergen, Norway; (L.S.); (R.L.); (J.B.E.); (F.G.-D.); (K.W.T.)
- School of Chemical Sciences, Dublin City University, Dublin 9, Ireland
| | - Jonas B. Ekeli
- Department of Chemistry, University of Bergen, Allégaten 41, N-5007 Bergen, Norway; (L.S.); (R.L.); (J.B.E.); (F.G.-D.); (K.W.T.)
| | - Francis Gillis-D’Hamers
- Department of Chemistry, University of Bergen, Allégaten 41, N-5007 Bergen, Norway; (L.S.); (R.L.); (J.B.E.); (F.G.-D.); (K.W.T.)
| | - Karl W. Törnroos
- Department of Chemistry, University of Bergen, Allégaten 41, N-5007 Bergen, Norway; (L.S.); (R.L.); (J.B.E.); (F.G.-D.); (K.W.T.)
| | - Vidar R. Jensen
- Department of Chemistry, University of Bergen, Allégaten 41, N-5007 Bergen, Norway; (L.S.); (R.L.); (J.B.E.); (F.G.-D.); (K.W.T.)
| | - Erwan Le Roux
- Department of Chemistry, University of Bergen, Allégaten 41, N-5007 Bergen, Norway; (L.S.); (R.L.); (J.B.E.); (F.G.-D.); (K.W.T.)
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18
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Hador R, Lipstman S, Rescigno R, Venditto V, Kol M. Aluminium complexes of salanol ligands: coordination chemistry and stereoselective lactide polymerization. Chem Commun (Camb) 2020; 56:13528-13531. [DOI: 10.1039/d0cc05957a] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Aluminium complexes of the new salanol ligands give rise to all PLA tacticities by different stereocontrol mechanisms.
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Affiliation(s)
- Rami Hador
- The School of Chemistry
- Tel Aviv University
- Ramat Aviv
- Israel
| | | | - Raffaella Rescigno
- Department of Chemistry and Biology A. Zambelli
- and INSTM Research Unit
- University of Salerno
- 84084 Fisciano
- Italy
| | - Vincenzo Venditto
- Department of Chemistry and Biology A. Zambelli
- and INSTM Research Unit
- University of Salerno
- 84084 Fisciano
- Italy
| | - Moshe Kol
- The School of Chemistry
- Tel Aviv University
- Ramat Aviv
- Israel
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19
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Hador R, Botta A, Venditto V, Lipstman S, Goldberg I, Kol M. The Dual‐Stereocontrol Mechanism: Heteroselective Polymerization of
rac
‐Lactide and Syndioselective Polymerization of
meso
‐Lactide by Chiral Aluminum Salan Catalysts. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201906848] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Rami Hador
- School of Chemistry Tel Aviv University Ramat Aviv Tel Aviv 6997801 Israel
| | - Antonio Botta
- Department of Chemistry and Biology A. Zambelli, and INSTM Research Unit University of Salerno Fisciano 84084 Salerno Italy
| | - Vincenzo Venditto
- Department of Chemistry and Biology A. Zambelli, and INSTM Research Unit University of Salerno Fisciano 84084 Salerno Italy
| | - Sophia Lipstman
- School of Chemistry Tel Aviv University Ramat Aviv Tel Aviv 6997801 Israel
| | - Israel Goldberg
- School of Chemistry Tel Aviv University Ramat Aviv Tel Aviv 6997801 Israel
| | - Moshe Kol
- School of Chemistry Tel Aviv University Ramat Aviv Tel Aviv 6997801 Israel
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20
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Hador R, Botta A, Venditto V, Lipstman S, Goldberg I, Kol M. The Dual‐Stereocontrol Mechanism: Heteroselective Polymerization of
rac
‐Lactide and Syndioselective Polymerization of
meso
‐Lactide by Chiral Aluminum Salan Catalysts. Angew Chem Int Ed Engl 2019; 58:14679-14685. [DOI: 10.1002/anie.201906848] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2019] [Indexed: 11/12/2022]
Affiliation(s)
- Rami Hador
- School of Chemistry Tel Aviv University Ramat Aviv Tel Aviv 6997801 Israel
| | - Antonio Botta
- Department of Chemistry and Biology A. Zambelli, and INSTM Research Unit University of Salerno Fisciano 84084 Salerno Italy
| | - Vincenzo Venditto
- Department of Chemistry and Biology A. Zambelli, and INSTM Research Unit University of Salerno Fisciano 84084 Salerno Italy
| | - Sophia Lipstman
- School of Chemistry Tel Aviv University Ramat Aviv Tel Aviv 6997801 Israel
| | - Israel Goldberg
- School of Chemistry Tel Aviv University Ramat Aviv Tel Aviv 6997801 Israel
| | - Moshe Kol
- School of Chemistry Tel Aviv University Ramat Aviv Tel Aviv 6997801 Israel
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21
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22
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Lalrempuia R, Underhaug J, Törnroos KW, Le Roux E. Anionic hafnium species: an active catalytic intermediate for the coupling of epoxides with CO 2? Chem Commun (Camb) 2019; 55:7227-7230. [PMID: 31165803 DOI: 10.1039/c9cc02695a] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A series of hafnium complexes were structurally identified showing high activity (up to 500 h-1) in the selective alternated copolymerization of epoxides with CO2 under low pressure.
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Affiliation(s)
- Ralte Lalrempuia
- Department of Chemistry, University of Bergen, Allégaten 41, N-5007, Bergen, Norway.
| | - Jarl Underhaug
- Department of Chemistry, University of Bergen, Allégaten 41, N-5007, Bergen, Norway.
| | - Karl W Törnroos
- Department of Chemistry, University of Bergen, Allégaten 41, N-5007, Bergen, Norway.
| | - Erwan Le Roux
- Department of Chemistry, University of Bergen, Allégaten 41, N-5007, Bergen, Norway.
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23
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24
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Baltrun M, Watt FA, Schoch R, Wölper C, Neuba AG, Hohloch S. A new bis-phenolate mesoionic carbene ligand for early transition metal chemistry. Dalton Trans 2019; 48:14611-14625. [DOI: 10.1039/c9dt03099a] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
A new chelating mesoionic carbene ligand, derived from 1,2,3-triazoles, with two redox-active tert-butyl-phenolate linkers has been synthesized and explored towards its reactivity and electrochemical properties in early transition metal chemistry.
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Affiliation(s)
- Marc Baltrun
- Universität Paderborn
- Fakultät für Naturwissenschaften
- Department Chemie Warburger Straße 100
- 33098 Paderborn
- Germany
| | - Fabian A. Watt
- Universität Paderborn
- Fakultät für Naturwissenschaften
- Department Chemie Warburger Straße 100
- 33098 Paderborn
- Germany
| | - Roland Schoch
- Universität Paderborn
- Fakultät für Naturwissenschaften
- Department Chemie Warburger Straße 100
- 33098 Paderborn
- Germany
| | | | - Adam G. Neuba
- Universität Paderborn
- Fakultät für Naturwissenschaften
- Department Chemie Warburger Straße 100
- 33098 Paderborn
- Germany
| | - Stephan Hohloch
- Universität Paderborn
- Fakultät für Naturwissenschaften
- Department Chemie Warburger Straße 100
- 33098 Paderborn
- Germany
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25
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Mandal M, Ramkumar V, Chakraborty D. Salen complexes of zirconium and hafnium: synthesis, structural characterization and polymerization studies. Polym Chem 2019. [DOI: 10.1039/c8py01750f] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Salen complexes of zirconium and hafnium were synthesized and used as effective catalysts for the polymerization of lactide and ε-CL and homopolymerization, copolymerization and coupling of epoxides with CO2.
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Affiliation(s)
- Mrinmay Mandal
- Department of Chemistry
- Indian Institute of Technology Patna
- Bihta 801103
- India
| | | | - Debashis Chakraborty
- Department of Chemistry
- Indian Institute of Technology Madras
- Chennai-600 036
- India
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26
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Quadri CC, Lalrempuia R, Frøystein NÅ, Törnroos KW, Le Roux E. Steric factors on unsymmetrical O -hydroxyaryl N -Heterocyclic carbene ligands prevailing the stabilization of single stereoisomer of bis-ligated titanium complexes. J Organomet Chem 2018. [DOI: 10.1016/j.jorganchem.2018.02.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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27
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Hameury S, de Frémont P, Braunstein P. Metal complexes with oxygen-functionalized NHC ligands: synthesis and applications. Chem Soc Rev 2018; 46:632-733. [PMID: 28083579 DOI: 10.1039/c6cs00499g] [Citation(s) in RCA: 148] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Ligand design has met with considerable success with both categories of hybrid ligands, which are characterized by chemically different donor groups, and of N-heterocyclic carbenes (NHCs). Their spectacular development and diversity are attracting worldwide interest and offers almost unlimited diversity and potential in e.g. coordination/organometallic main group and transition metal chemistry, catalysis, medicinal chemistry and materials science. This review aims at providing a comprehensive update on a specific class of ligands that has enjoyed much attention in the past few years, at the intersection between the two categories mentioned above, that of hybrid NHC ligands in which the functionality associated with the carbene donor is of the oxygen-donor type. For each type of oxygen-donor present in such chelating (Section 1) or bridging (Section 2) hybrid ligands, we will examine the synthesis, structures and reactivity of their metal complexes and their applications, with a special focus on homogeneous catalysis (Section 3). Thus, hydrogenation, C-H bond activation, C-C, C-N, C-O bond formation, hydrolysis of silanes, oligomerization, polymerization, metathesis, hydrosilylation, C-C bond cleavage, acceptorless dehydrogenation, dehalogenation/hydrogen transfer, oxidation and reduction reactions will be successively presented in a tabular manner, to facilitate an overview and a rapid identification of the relevant publications describing which metals associated with a given oxygen functionality are most suitable. The literature coverage includes the year 2015.
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Affiliation(s)
- Sophie Hameury
- Université de Strasbourg, CNRS, CHIMIE UMR 7177, Laboratoire de Chimie de Coordination, 4 rue Blaise Pascal, 67081 Strasbourg, France. and Universität Freiburg, Makromolekulare Chemie, Stefan-Meier-Str. 31, 79104 Freiburg, Germany
| | - Pierre de Frémont
- Université de Strasbourg, CNRS, CHIMIE UMR 7177, Laboratoire de Chimie de Coordination, 4 rue Blaise Pascal, 67081 Strasbourg, France. and Université de Strasbourg, CNRS, CHIMIE UMR 7177, Laboratoire de Synthèse, Réactivité et Catalyse Organométalliques, 4 rue Blaise Pascal, 67081 Strasbourg, France
| | - Pierre Braunstein
- Université de Strasbourg, CNRS, CHIMIE UMR 7177, Laboratoire de Chimie de Coordination, 4 rue Blaise Pascal, 67081 Strasbourg, France.
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28
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Harinath A, Bhattacharjee J, Sarkar A, Nayek HP, Panda TK. Ring Opening Polymerization and Copolymerization of Cyclic Esters Catalyzed by Group 2 Metal Complexes Supported by Functionalized P–N Ligands. Inorg Chem 2018; 57:2503-2516. [DOI: 10.1021/acs.inorgchem.7b02847] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Adimulam Harinath
- Department of Chemistry, Indian Institute of Technology Hyderabad Kandi 502 285, Sangareddy, Telangana, India
| | - Jayeeta Bhattacharjee
- Department of Chemistry, Indian Institute of Technology Hyderabad Kandi 502 285, Sangareddy, Telangana, India
| | - Alok Sarkar
- Momentive Performance
Materials Pvt. Ltd., Bangalore 560 100, India
| | - Hari Pada Nayek
- Department of Applied Chemistry, Indian Institute of Technology (ISM), Dhanbad 826 004, Jharkhand, India
| | - Tarun K. Panda
- Department of Chemistry, Indian Institute of Technology Hyderabad Kandi 502 285, Sangareddy, Telangana, India
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29
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Probing the Effect of Six-Membered N-Heterocyclic Carbene—6-Mes—on the Synthesis, Structure and Reactivity of Me2MOR(NHC) (M = Ga, In) Complexes. INORGANICS 2018. [DOI: 10.3390/inorganics6010028] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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30
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Lalrempuia R, Breivik F, Törnroos KW, Le Roux E. Coordination behavior of bis-phenolate saturated and unsaturated N-heterocyclic carbene ligands to zirconium: reactivity and activity in the copolymerization of cyclohexene oxide with CO 2. Dalton Trans 2018; 46:8065-8076. [PMID: 28604887 DOI: 10.1039/c7dt01117b] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Tetravalent zirconium complexes supported by tridentate bis-phenolate imidazolidin-2-ylidene (L1), imidazol-2-ylidene (L2) and benzimidazol-2-ylidene (L3) NHC ligands were synthesized and evaluated as precursors for the copolymerization of cyclohexene oxide (CHO) with CO2. While the reactivity of the imidazolidinium [H3L1] chloride salt with Zr(OiPr)4(HOiPr), and subsequent ligand exchanges with either (CH3)3SiCl or LiOiPr lead to a series of heteroleptic compounds (κ3-O,C,O-L1)Zr(X)2(THF) (X = Cl, OiPr), both imidazolium [H3L2] and benzimidazolium [H3L3] chloride salts give a mixture of homoleptic (κ3-O,C,O-NHC)2Zr and zwitterionic (κ2-O,O-HL)ZrCl2(OiPr) compounds along with traces or the absence of the heteroleptic intermediate (κ3-O,C,O-NHC)Zr(Cl)(OiPr)(THF). Such dissimilar reactivity between the unsaturated and saturated NHC ligands is predominantly ascribed to the increased acidity of azolium salts along with the π-donor strength of the Ccarbene in L2 and L3-Zr moieties. The reactivity with the more acidic azolium salts (H3L2/3) and the destabilized Zr-Xtrans to NHCcarbene bond results in a significant increase in the amount of homoleptic compounds generating HCl. The released HCl reacts preferentially with the heteroleptic intermediates having non-planar NHC ligands (i.e. L2/3) promoting the formation of zwitterionic complexes. The in situ deprotonation of the isolated zwitterionic (κ2-O,O-HL3)ZrCl2(OiPr) compound by using Ag2O gives the homoleptic complex as the major component along with a bimetallic hydroxo-bridged [(κ3-O,C,O-L3)Zr(μ-OH)(OiPr)]2 compound. Of particular interest is that only the heteroleptic NHC-Zr(iv) complexes were identified to be active and highly selective towards the copolymerization of CHO with CO2 independently of the co-catalysts used (both anionic and neutral) under mild conditions (PCO2 < 1 bar, T = 60 °C), and gave atactic and completely alternating copolymers in a controlled manner (Mw/Mn ≈ 1.3-1.8). In contrast, the isolated homoleptic, zwitterionic and bimetallic zirconium species were found to be inactive under similar reaction conditions. Although the activity found for NHC-Zr(iv) complexes is nearly of the same order of magnitude as that of the NHC-Ti(iv) analogues, these results are the first examples of tetravalent zirconium complexes achieving high selectivity (99% in PCHC) in the catalyzed copolymerization of CHO with CO2.
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Affiliation(s)
- Ralte Lalrempuia
- University of Bergen, Department of Chemistry, Allégaten 41, N-5007, Bergen, Norway.
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31
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McKeown P, McCormick SN, Mahon MF, Jones MD. Highly active Mg(ii) and Zn(ii) complexes for the ring opening polymerisation of lactide. Polym Chem 2018. [DOI: 10.1039/c8py01369a] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Simple, highly active, Zn(ii) and Mg(ii) complexes for the industrial ring opening polymerisation (ROP) of lactide.
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Affiliation(s)
| | - Strachan N. McCormick
- Centre for Doctoral Training in Sustainable Chemical Technologies
- University of Bath
- Bath
- UK
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32
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Bhunia M, Vijaykumar G, Adhikari D, Mandal SK. Highly Active Carbene Potassium Complexes for the Ring-Opening Polymerization of ε-Caprolactone. Inorg Chem 2017; 56:14459-14466. [DOI: 10.1021/acs.inorgchem.7b01892] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Mrinal Bhunia
- Department of Chemical
Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, India
| | - Gonela Vijaykumar
- Department of Chemical
Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, India
| | - Debashis Adhikari
- Department
of Chemical Sciences, Indian Institute of Science Education and Research Mohali, SAS Nagar 140306, India
| | - Swadhin K. Mandal
- Department of Chemical
Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, India
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33
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Quadri CC, Lalrempuia R, Hessevik J, Törnroos KW, Le Roux E. Structural Characterization of Tridentate N-Heterocyclic Carbene Titanium(IV) Benzyloxide, Silyloxide, Acetate, and Azide Complexes and Assessment of Their Efficacies for Catalyzing the Copolymerization of Cyclohexene Oxide with CO2. Organometallics 2017. [DOI: 10.1021/acs.organomet.7b00705] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Coralie C. Quadri
- Department of Chemistry, University of Bergen, Allégaten 41, N-5007, Bergen, Norway
| | - Ralte Lalrempuia
- Department of Chemistry, University of Bergen, Allégaten 41, N-5007, Bergen, Norway
| | - Julie Hessevik
- Department of Chemistry, University of Bergen, Allégaten 41, N-5007, Bergen, Norway
| | - Karl W. Törnroos
- Department of Chemistry, University of Bergen, Allégaten 41, N-5007, Bergen, Norway
| | - Erwan Le Roux
- Department of Chemistry, University of Bergen, Allégaten 41, N-5007, Bergen, Norway
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34
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Synthesis of Li(I), Zn(II) and Mg(II) complexes of amine bis(phenolates) and their exploitation for the ring opening polymerisation of rac-lactide. J Organomet Chem 2017. [DOI: 10.1016/j.jorganchem.2017.08.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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35
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Rajashekhar B, Mandal M, Chakraborty D, Ramkumar V. Homoleptic Zr and Hf Complexes of Imino/Bis(imino)phenoxide Scaffolds: Synthesis, Structural Characterization and Their Catalytic Activity in the ROP of Cyclic Esters. ChemistrySelect 2017. [DOI: 10.1002/slct.201701602] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- Bijja Rajashekhar
- Department of Chemistry; Indian Institute of Technology Madras; Chennai- 600 036, Tamil Nadu India
| | - Mrinmay Mandal
- Department of Chemistry; Indian Institute of Technology Patna; Bihta 801103, Bihar India
| | - Debashis Chakraborty
- Department of Chemistry; Indian Institute of Technology Madras; Chennai- 600 036, Tamil Nadu India
| | - Venkatachalam Ramkumar
- Department of Chemistry; Indian Institute of Technology Madras; Chennai- 600 036, Tamil Nadu India
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36
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Liu N, Hao J, Cai K, Zeng M, Huang Z, Chen L, Peng B, Li P, Wang L, Song Y. Ratiometric fluorescence detection of superoxide anion based on AuNPs-BSA@Tb/GMP nanoscale coordination polymers. LUMINESCENCE 2017; 33:119-124. [PMID: 28776941 DOI: 10.1002/bio.3380] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 05/06/2017] [Accepted: 06/23/2017] [Indexed: 12/22/2022]
Abstract
A novel ratiometric fluorescence nanosensor for superoxide anion (O2•- ) detection was designed with gold nanoparticles-bovine serum albumin (AuNPs-BSA)@terbium/guanosine monophosphate disodium (Tb/GMP) nanoscale coordination polymers (NCPs) (AuNPs-BSA@Tb/GMP NCPs). The abundant hydroxyl and amino groups of AuNPs-BSA acted as binding points for the self-assembly of Tb3+ and GMP to form core-shell AuNPs-BSA@Tb/GMP NCP nanosensors. The obtained probe exhibited the characteristic fluorescence emission of both AuNPs-BSA and Tb/GMP NCPs. The AuNPs-BSA not only acted as a template to accelerate the growth of Tb/GMP NCPs, but also could be used as the reference fluorescence for the detection of O2•- . The resulting AuNPs-BSA@Tb/GMP NCP ratiometric fluorescence nanosensor for the detection of O2•- demonstrated high sensitivity and selectivity with a wide linear response range (14 nM-10 μM) and a low detection limit (4.7 nM).
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Affiliation(s)
- Nan Liu
- Key Laboratory of Functional Small Organic Molecule, Ministry of Education, College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang, P. R. China
| | - Juan Hao
- Key Laboratory of Functional Small Organic Molecule, Ministry of Education, College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang, P. R. China
| | - Keying Cai
- Key Laboratory of Functional Small Organic Molecule, Ministry of Education, College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang, P. R. China
| | - Mulan Zeng
- Key Laboratory of Functional Small Organic Molecule, Ministry of Education, College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang, P. R. China
| | - Zhenzhong Huang
- Key Laboratory of Functional Small Organic Molecule, Ministry of Education, College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang, P. R. China
| | - Lili Chen
- Key Laboratory of Functional Small Organic Molecule, Ministry of Education, College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang, P. R. China
| | - Bingxian Peng
- Key Laboratory of Functional Small Organic Molecule, Ministry of Education, College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang, P. R. China
| | - Ping Li
- Key Laboratory of Functional Small Organic Molecule, Ministry of Education, College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang, P. R. China
| | - Li Wang
- Key Laboratory of Functional Small Organic Molecule, Ministry of Education, College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang, P. R. China
| | - Yonghai Song
- Key Laboratory of Functional Small Organic Molecule, Ministry of Education, College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang, P. R. China
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37
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Group 4 Metal Complexes of Phenylene-Salalen Ligands in rac
-Lactide Polymerization Giving High Molecular Weight Stereoblock Poly(lactic acid). Chemistry 2017; 23:11540-11548. [DOI: 10.1002/chem.201701007] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2017] [Indexed: 01/19/2023]
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38
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Catalytic Systems for the Production of Poly(lactic acid). SYNTHESIS, STRUCTURE AND PROPERTIES OF POLY(LACTIC ACID) 2017. [DOI: 10.1007/12_2017_20] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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39
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Lizundia E, Makwana VA, Larrañaga A, Vilas JL, Shaver MP. Thermal, structural and degradation properties of an aromatic–aliphatic polyester built through ring-opening polymerisation. Polym Chem 2017. [DOI: 10.1039/c7py00695k] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The novel biodegradable aromatic–aliphatic polyester, poly(2-(2-hydroxyethoxy)benzoate), was explored through thermal analysis, X-ray diffraction, dynamic mechanical analysis and comparative bio and catalysed degradation.
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Affiliation(s)
- Erlantz Lizundia
- Department of Graphic Design and Engineering Projects
- Bilbao Faculty of Engineering
- University of the Basque Country (UPV/EHU)
- Bilbao 48013
- Spain
| | | | - Aitor Larrañaga
- SGIker
- General Research Services
- University of the Basque Country (UPV/EHU)
- Spain
| | - José Luis Vilas
- Macromolecular Chemistry Research Group
- Dept. of Physical Chemistry
- Faculty of Science and Technology
- University of the Basque Country (UPV/EHU)
- Leioa 48940
| | - Michael P. Shaver
- EaStCHEM School of Chemistry
- University of Edinburgh
- Edinburgh EH9 3FJ
- UK
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40
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Hu M, Han F, Zhang W, Ma W, Deng Q, Song W, Yan H, Dong G. Preparation of zirconium and hafnium complexes containing chiral N atoms from asymmetric tertiary amine ligands, and their catalytic properties for polymerization of rac-lactide. Catal Sci Technol 2017. [DOI: 10.1039/c6cy02618d] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Preparation of Zr and Hf complexes containing chiral N atoms, and their use in polymerization of rac-lactide.
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Affiliation(s)
- Minggang Hu
- College of Chemistry and Chemical Engineering
- Qiqihar University
- Qiqihar 161006
- China
| | - Fuzhong Han
- College of Chemistry and Chemical Engineering
- Qiqihar University
- Qiqihar 161006
- China
| | - Wenzhi Zhang
- College of Chemistry and Chemical Engineering
- Qiqihar University
- Qiqihar 161006
- China
| | - Wenhui Ma
- College of Chemistry and Chemical Engineering
- Qiqihar University
- Qiqihar 161006
- China
| | - Qigang Deng
- College of Chemistry and Chemical Engineering
- Qiqihar University
- Qiqihar 161006
- China
| | - Weiming Song
- College of Chemistry and Chemical Engineering
- Qiqihar University
- Qiqihar 161006
- China
| | - Hailong Yan
- Qiqihar Environmental Protection Bureau Monitoring Center
- Qiqihar 161005
- China
| | - Guohua Dong
- College of Chemistry and Chemical Engineering
- Qiqihar University
- Qiqihar 161006
- China
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41
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Otero A, Fernández-Baeza J, Garcés A, Sánchez-Barba LF, Lara-Sánchez A, Martínez-Ferrer J, Carrión MP, Rodríguez AM. Highly thermally stable and robust enantiopure zirconium NNN-scorpionates for the controlled ring-opening polymerization of rac-lactide. Dalton Trans 2017; 46:6654-6662. [DOI: 10.1039/c7dt01050h] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
An enantiopure NNN-scorpionate zirconium alkoxide as the highest active group 4-based initiator in ROP of unpurified rac-LA under industrially preferred conditions.
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Affiliation(s)
- Antonio Otero
- Universidad de Castilla-La Mancha
- Departamento de Química Inorgánica
- Orgánica y Bioquímica
- Centro de Innovación en Química Avanzada (ORFEO-CINQA) Campus Universitario
- 13071-Ciudad Real
| | - Juan Fernández-Baeza
- Universidad de Castilla-La Mancha
- Departamento de Química Inorgánica
- Orgánica y Bioquímica
- Centro de Innovación en Química Avanzada (ORFEO-CINQA) Campus Universitario
- 13071-Ciudad Real
| | - Andrés Garcés
- Universidad Rey Juan Carlos
- Departamento de Biología y Geología
- Física y Química Inorgánica
- Móstoles-28933-Madrid
- Spain
| | - Luis F. Sánchez-Barba
- Universidad Rey Juan Carlos
- Departamento de Biología y Geología
- Física y Química Inorgánica
- Móstoles-28933-Madrid
- Spain
| | - Agustín Lara-Sánchez
- Universidad de Castilla-La Mancha
- Departamento de Química Inorgánica
- Orgánica y Bioquímica
- Centro de Innovación en Química Avanzada (ORFEO-CINQA) Campus Universitario
- 13071-Ciudad Real
| | - Jaime Martínez-Ferrer
- Universidad de Castilla-La Mancha
- Departamento de Química Inorgánica
- Orgánica y Bioquímica
- Centro de Innovación en Química Avanzada (ORFEO-CINQA) Campus Universitario
- 13071-Ciudad Real
| | - María P. Carrión
- Universidad de Castilla-La Mancha
- Departamento de Química Inorgánica
- Orgánica y Bioquímica
- Centro de Innovación en Química Avanzada (ORFEO-CINQA) Campus Universitario
- 13071-Ciudad Real
| | - Ana M. Rodríguez
- Universidad de Castilla-La Mancha
- Departamento de Química Inorgánica
- Orgánica y Bioquímica
- Centro de Innovación en Química Avanzada (ORFEO-CINQA) Campus Universitario
- 13071-Ciudad Real
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42
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Kirk SM, Kociok-Köhn G, Jones MD. Zirconium vs Aluminum Salalen Initiators for the Production of Biopolymers. Organometallics 2016. [DOI: 10.1021/acs.organomet.6b00718] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Sarah M. Kirk
- Doctoral Training
Centre in Sustainable Chemical Technologies and ‡Department of
Chemistry, University of Bath, Bath BA2 7AY, U.K
| | - Gabriele Kociok-Köhn
- Doctoral Training
Centre in Sustainable Chemical Technologies and ‡Department of
Chemistry, University of Bath, Bath BA2 7AY, U.K
| | - Matthew D. Jones
- Doctoral Training
Centre in Sustainable Chemical Technologies and ‡Department of
Chemistry, University of Bath, Bath BA2 7AY, U.K
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43
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Chang YN, Lee PY, Zou XR, Huang HF, Chen YW, Liang LC. Aluminum complexes containing biphenolate phosphine ligands: synthesis and living ring-opening polymerization catalysis. Dalton Trans 2016; 45:15951-15962. [PMID: 27406437 DOI: 10.1039/c6dt02143c] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
This report describes the synthesis, structure, and reactivity of aluminum complexes containing tridentate biphenolate phosphine ligands of the type [RP(2-O-3,5-C6H2tBu2)2]2- (R = tBu (2a), Ph (2b)). Alkane elimination of AlMe3 with one equiv. of H2[2a] or H2[2b] in THF at 0 °C cleanly affords colorless crystalline [2a]AlMe(THF) (3a) and [2b]AlMe(THF) (3b), respectively. An X-ray diffraction study of 3a showed it to be a five-coordinate THF-bound species, whose coordination geometry is best described as trigonal bipyramidal, having the phosphorus donor and THF at axial positions. Treatment of either in situ prepared or isolated methyl complexes 3a,b with one equiv. of benzyl alcohol in toluene or THF generated their corresponding benzyloxides {[2a,b]Al(μ2-OCH2Ph)}2 (4a,b). An X-ray diffraction study of 4a revealed a dimeric structure, in which the coordination geometry of aluminum is also distorted trigonal bipyramidal with the tridentate 2a ligand being facially bound. In the presence of one equiv. of benzyl alcohol, complex 3a is a competent catalyst precursor for the living ring-opening polymerization of ε-caprolactone (ε-CL) and rac-lactide (rac-LA), producing poly(ε-caprolactone) and poly(rac-lactide), respectively, in a controlled manner. As such, well-defined block copolymers of ε-CL with rac-LA can also be prepared by catalytic 3a. Kinetic studies revealed that 3a catalyzes the polymerization of rac-lactide at a rate 2-fold faster than that of 3b, indicating the significance of the P-substituent effect on this catalysis. Interestingly, the polymerization rate of rac-lactide by 3a is 16.5 times faster than that of l-lactide under otherwise identical conditions.
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Affiliation(s)
- Yu-Ning Chang
- Department of Chemistry and Center for Nanoscience & Nanotechnology, National Sun Yat-sen University, Kaohsiung 80424, Taiwan.
| | - Pei-Ying Lee
- Department of Chemistry and Center for Nanoscience & Nanotechnology, National Sun Yat-sen University, Kaohsiung 80424, Taiwan.
| | - Xue-Ru Zou
- Department of Chemistry and Center for Nanoscience & Nanotechnology, National Sun Yat-sen University, Kaohsiung 80424, Taiwan.
| | - Han-Fan Huang
- Department of Chemistry and Center for Nanoscience & Nanotechnology, National Sun Yat-sen University, Kaohsiung 80424, Taiwan.
| | - Yi-Wei Chen
- Department of Chemistry and Center for Nanoscience & Nanotechnology, National Sun Yat-sen University, Kaohsiung 80424, Taiwan.
| | - Lan-Chang Liang
- Department of Chemistry and Center for Nanoscience & Nanotechnology, National Sun Yat-sen University, Kaohsiung 80424, Taiwan. and Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, Kaohsiung 80708, Taiwan
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44
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Chakraborty D, Chokkapu ER, Mandal M, Gowda RR, Ramkumar V. Zwitterionic Complexes of Group 4 Metal Chlorides Containing a Bis(imino)phenoxide Scaffold: Synthesis, Characterization and Polymerization Studies. ChemistrySelect 2016. [DOI: 10.1002/slct.201600909] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- Debashis Chakraborty
- Department of Chemistry; Indian Institute of Technology Madras; Chennai-600 036, Tamil Nadu India
| | - Eswara Rao Chokkapu
- Department of Chemistry; Indian Institute of Technology Madras; Chennai-600 036, Tamil Nadu India
| | - Mrinmay Mandal
- Department of Chemistry; Indian Institute of Technology Patna; Patna-800 013, Bihar India
| | - Ravikumar R. Gowda
- Department of Chemistry; Indian Institute of Technology Madras; Chennai-600 036, Tamil Nadu India
| | - Venkatachalam Ramkumar
- Department of Chemistry; Indian Institute of Technology Madras; Chennai-600 036, Tamil Nadu India
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45
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Group 4 complexes of salicylbenzoxazole ligands as effective catalysts for the ring-opening polymerization of lactides, epoxides and copolymerization of ε-caprolactone with L-lactide. POLYMER 2016. [DOI: 10.1016/j.polymer.2016.08.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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46
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Cybularczyk M, Dranka M, Zachara J, Horeglad P. Effect of In–CNHC Bonds on the Synthesis, Structure, and Reactivity of Dialkylindium Alkoxides: How Indium Compares to Gallium. Organometallics 2016. [DOI: 10.1021/acs.organomet.6b00510] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Martyna Cybularczyk
- Centre
of New Technologies, University of Warsaw, Banacha 2c, 02-097 Warsaw, Poland
- Faculty
of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw, Poland
| | - Maciej Dranka
- Faculty
of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664 Warsaw, Poland
| | - Janusz Zachara
- Faculty
of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664 Warsaw, Poland
| | - Paweł Horeglad
- Centre
of New Technologies, University of Warsaw, Banacha 2c, 02-097 Warsaw, Poland
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47
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Rosen T, Popowski Y, Goldberg I, Kol M. Zinc Complexes of Sequential Tetradentate Monoanionic Ligands in the Isoselective Polymerization of rac
-Lactide. Chemistry 2016; 22:11533-6. [DOI: 10.1002/chem.201601979] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Indexed: 11/09/2022]
Affiliation(s)
- Tomer Rosen
- School of Chemistry; Tel Aviv University; Ramat Aviv Tel Aviv 69978 Israel
| | - Yanay Popowski
- School of Chemistry; Tel Aviv University; Ramat Aviv Tel Aviv 69978 Israel
| | - Israel Goldberg
- School of Chemistry; Tel Aviv University; Ramat Aviv Tel Aviv 69978 Israel
| | - Moshe Kol
- School of Chemistry; Tel Aviv University; Ramat Aviv Tel Aviv 69978 Israel
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48
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Duan YL, He JX, Wang W, Zhou JJ, Huang Y, Yang Y. Synthesis and characterization of dinuclear rare-earth complexes supported by amine-bridged bis(phenolate) ligands and their catalytic activity for the ring-opening polymerization of l-lactide. Dalton Trans 2016; 45:10807-20. [PMID: 27294827 DOI: 10.1039/c6dt01486k] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Reactions of amine-bridged bis(phenolate) protio-ligands N,N-bis(3,5-di-tert-butyl-2-hydroxybenzyl)aminoacetic acid (L(1)-H3) and N,N-bis[3,5-bis(α,α'-dimethylbenzyl)-2-hydroxybenzyl]aminoacetic acid (L(2)-H3), with 1 equiv. M[N(SiMe3)2]3 (M = La, Nd, Sm, Gd, Y) in THF at room temperature yielded the neutral rare-earth complexes [M2(L)2(THF)4] (L = L(1), M = La (), Nd (), Sm (), Gd (), Y (); L = L(2), M = La (), Nd (), Sm (), Gd (), Y ()). All of these complexes were characterized by single-crystal X-ray diffraction, elemental analysis and in the case of yttrium and lanthanum complexes, (1)H NMR spectroscopy. The molecular structure of revealed dinuclear species in which the eight-coordinate lanthanum centers were bonded to two oxygen atoms of two THF molecules, to three oxygen atoms and one nitrogen atom of one L(1) ligand, and two oxygen atoms of the carboxyl group of another. Complexes were also dinuclear species containing seven-coordinate metal centers similar to , albeit with bonding to one rather than two carboxyl group oxygens of another ligand. Further treatment of with excess benzyl alcohol provided dinuclear complex [La2(L(1))2(BnOH)6] (), in which each lanthanum ion is eight-coordinate, bonded to three oxygen atoms and one nitrogen atom of one ligand, three oxygen atoms of three BnOH molecules, as well as one oxygen atom of bridging carboxyl group of the other ligand. In the presence of BnOH, complexes efficiently catalyzed the ring-opening polymerization of l-lactide in a controlled manner and gave polymers with relatively narrow molecular weight distributions. The kinetic and mechanistic studies associated with the ROP of l-lactide using /BnOH initiating system have been performed.
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Affiliation(s)
- Yu-Lai Duan
- Key Laboratory of Nonferrous Metals Chemistry and Resources Utilization of Gansu Province, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, Gansu, P. R. China.
| | - Jia-Xuan He
- Key Laboratory of Nonferrous Metals Chemistry and Resources Utilization of Gansu Province, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, Gansu, P. R. China.
| | - Wei Wang
- Key Laboratory of Nonferrous Metals Chemistry and Resources Utilization of Gansu Province, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, Gansu, P. R. China.
| | - Jing-Jing Zhou
- Key Laboratory of Nonferrous Metals Chemistry and Resources Utilization of Gansu Province, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, Gansu, P. R. China.
| | - Yong Huang
- Key Laboratory of Nonferrous Metals Chemistry and Resources Utilization of Gansu Province, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, Gansu, P. R. China.
| | - Ying Yang
- Key Laboratory of Nonferrous Metals Chemistry and Resources Utilization of Gansu Province, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, Gansu, P. R. China.
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49
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Rajashekhar B, Roymuhury SK, Chakraborty D, Ramkumar V. Group 4 metal complexes of Trost's semi-crown ligand: synthesis, structural characterization and studies on the ring-opening polymerization of lactides and ε-caprolactone. Dalton Trans 2016; 44:16280-93. [PMID: 26262508 DOI: 10.1039/c5dt02267c] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The synthesis of titanium(IV), zirconium(IV) and hafnium(IV) complexes of Trost's semi-crown ligand is described. All complexes were fully characterized by 1H and 13C NMR and mass spectroscopy. The molecular structures of the representative complexes 2, 3 and 4 were determined by single-crystal X-ray diffraction studies. The X-ray diffraction studies reveal that complexes 2, 3 and 4 crystallized in an orthorhombic crystal system. Complexes 2 and 3 have a monomeric structure in the solid state with distorted octahedral geometry around the metal center, whereas complex 4 was found to crystallize in a trimeric structure bridging with an oxygen atom, where the geometry around the titanium is distorted trigonal bipyramidal. The activities and stereoselectivities of these complexes toward the ring-opening polymerization (ROP) of lactides (L-LA and rac-LA) and ε-caprolactone (CL) have been investigated. Complexes 1–4 were found to be efficient single-component initiators for the ring-opening polymerization of cyclic esters and yielded high molecular weight polymers (Mn) with narrow molecular weight distributions (MWD).The microstructure of the resultant polylactides (PLAs) from rac-LA was determined. Complexes 2 and 3 afforded isotactic-enriched PLA (Pm = 0.78–0.71) with narrow MWD (1.07–1.04), on the other hand complexes 1 and 4 produced atactic PLA. Kinetic and post polymerization studies confirm that the polymerization proceeds through the coordination–insertion mechanism.
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Affiliation(s)
- Bijja Rajashekhar
- Department of Chemistry, Indian Institute of Technology Madras, Chennai-600 036, Tamil Nadu, India.
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50
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Fliedel C, Rosa V, Alves FM, Martins AM, Avilés T, Dagorne S. P,O-Phosphinophenolate zinc(II) species: synthesis, structure and use in the ring-opening polymerization (ROP) of lactide, ε-caprolactone and trimethylene carbonate. Dalton Trans 2016; 44:12376-87. [PMID: 25847079 DOI: 10.1039/c5dt00458f] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The P,O-type phosphinophenol proligands (1·H, 2-PPh2-4-Me-6-Me-C6H2OH; 2·H, 2-PPh2-4-Me-6-(t)Bu-C6H2OH) readily react with one equiv. of ZnEt2 to afford in high yields the corresponding Zn(II)-ethyl dimers of the type [(κ(2)-P,O)Zn-Et]2 (3 and 4) with two μ-OPh bridging oxygens connecting the two Zn(II) centers, as determined by X-ray diffraction (XRD) studies in the case of 3. Based on diffusion-ordered NMR spectroscopy (DOSY), both species 3 and 4 retain their dimeric structures in solution. The alcoholysis reaction of Zn(II) alkyls 3 and 4 with BnOH led to the high yield formation of the corresponding Zn(II) benzyloxide species [(κ(2)-P,O)Zn-OBn]2 (5 and 6), isolated in a pure form as colorless solids. The centrosymmetric and dimeric nature of Zn(II) alkoxides 5 and 6 in solution was deduced from DOSY NMR experiments and multinuclear NMR data. Though the heteroleptic species 5 is stable in solution, its analogue 6 is instable in CH2Cl2 solution at room temperature to slowly decompose to the corresponding homoleptic species 8via the transient formation of (κ(2)-P,O)2Zn2(μ-OBn)(μ–κ(1):κ(1)-P,O) (6′). Crystallization of compound 6 led to crystals of 6′, as established by XRD analysis. The reaction of ZnEt2 with two equiv. of 1·H and 2·H allowed access to the corresponding homoleptic species of the type [Zn(P,O)2] (7 and 8). All gathered data are consistent with compound 7 being a dinuclear species in the solid state and in solution. Data for species 8, which bears a sterically demanding P,O-ligand, are consistent with a mononuclear species in solution. The Zn(II) alkoxide species 5 and the [Zn(P,O)2]-type compounds 7 and 8 were evaluated as initiators of the ring-opening polymerization (ROP) of lactide (LA), ε-caprolactone (ε-CL) and trimethylene carbonate (TMC). Species 5 is a well-behaved ROP initiator for the homo-, co- and ter-polymerization of all three monomers with the production of narrow disperse materials under living and immortal conditions. Though species 7 and 8 are ROP inactive on their own, they readily polymerize LA in the presence of a nucleophile such as BnOH to produce narrow disperse PLA, presumably via an activated-monomer ROP mechanism.
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Affiliation(s)
- Christophe Fliedel
- LAQV, REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa, Caparica, 2829-516, Portugal
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