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Buchard A, Davidson MG, Gobius du Sart G, Jones MD, Kociok-Köhn G, McCormick SN, McKeown P. Unexpected Periodicity in Cationic Group 5 Initiators for the Ring-Opening Polymerization of Lactones. Inorg Chem 2024; 63:27-38. [PMID: 38118120 PMCID: PMC10777398 DOI: 10.1021/acs.inorgchem.3c03854] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 11/23/2023] [Accepted: 12/04/2023] [Indexed: 12/22/2023]
Abstract
ε-Caprolactone (ε-CL) adducts of cationic, amine tris(phenolate)-supported niobium(V) and tantalum(V) ethoxides initiate the ring-opening polymerization of lactones. The Ta(V) species prepared and applied catalytically herein exhibits higher activity in the ring-opening polymerization (ROP) of ε-caprolactone than the previously reported, isostructural Nb(V) complex, contradicting literature comparisons of Nb(V)- and Ta(V)-based protocols. Both systems also initiate the ROP of δ-valerolactone and rac-β-butyrolactone, kinetic studies confirming retention of higher activity by the Ta congener. Polymerizations of rac-β-butyrolactone and δ-valerolactone were previously unrealized under Group V- or Ta-mediated conditions, respectively, although the former has afforded only low molecular weight, cyclic poly-3-hydroxybutyrate. Cationic ethoxo-Nb(V) and -Ta(V) δ-valerolactone adducts are also reported, demonstrating the facility of δ-valerolactone as a ligand and the generality of the synthetic method. Both δ-valerolactone-bearing complexes initiate the ROP of ε-caprolactone, δ-valerolactone, and rac-β-butyrolactone. Accordingly, we have elucidated trends in reactivity and investigated the initiation mechanism for such systems, the insertion event being predicated upon intramolecular nucleophilic attack on the coordinated lactone by the adjacent alkoxide moiety. This mechanism enables quantitative, stoichiometric installation of a single monomer residue distinct from the bulk of the polymer chain, and permits modification of polymer properties via both manipulation of the molecular architecture and tuning of the polymerization kinetics, and thus dispersity, through hitherto inaccessible independent control of the initiation event.
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Affiliation(s)
- Antoine Buchard
- Institute
for Sustainability, University of Bath, Bath BA2 7AY, United Kingdom
- Department
of Chemistry, University of Bath, Bath BA2 7AY, United Kingdom
| | - Matthew G. Davidson
- Institute
for Sustainability, University of Bath, Bath BA2 7AY, United Kingdom
- Department
of Chemistry, University of Bath, Bath BA2 7AY, United Kingdom
| | | | - Matthew D. Jones
- Institute
for Sustainability, University of Bath, Bath BA2 7AY, United Kingdom
- Department
of Chemistry, University of Bath, Bath BA2 7AY, United Kingdom
| | - Gabriele Kociok-Köhn
- Material
and Chemical Characterization and Analysis Facility (MC), University of Bath, Bath BA2 7AY, United Kingdom
| | - Strachan N. McCormick
- Institute
for Sustainability, University of Bath, Bath BA2 7AY, United Kingdom
- Department
of Chemistry, University of Bath, Bath BA2 7AY, United Kingdom
| | - Paul McKeown
- Department
of Chemistry, University of Bath, Bath BA2 7AY, United Kingdom
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2
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Buchard A, Davidson MG, Gobius du Sart G, Jones MD, Kociok-Köhn G, McCormick SN, Mckeown P. Coordination of ε-Caprolactone to a Cationic Niobium(V) Alkoxide Complex: Fundamental Insight into Ring-Opening Polymerization via Coordination-Insertion. Inorg Chem 2023; 62:15688-15699. [PMID: 37695575 PMCID: PMC10523432 DOI: 10.1021/acs.inorgchem.3c02491] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Indexed: 09/12/2023]
Abstract
We report three niobium-based initiators for the catalytic ring-opening polymerization (ROP) of ε-caprolactone, exhibiting good activity and molecular weight control. In particular, we have prepared on the gram-scale and fully characterized a monometallic cationic alkoxo-Nb(V) ε-caprolactone adduct representing, to the best of our knowledge, an unprecedented example of a metal complex with an intact lactone monomer and a functional ROP-initiating group simultaneously coordinated at the metal center. At 80 °C, all three systems initiate the immortal solution-state ROP of ε-caprolactone via a coordination-insertion mechanism, which has been confirmed through experimental studies, and is supported by computational data. Natural bond orbital calculations further indicate that polymerization may necessitate isomerization about the metal center between the alkoxide chain and the coordinated monomer. The observations made in this work are expected to inform mechanistic understanding both of amine tris(phenolate)-supported metal alkoxide ROP initiators, including various highly stereoselective systems for the polymerization of lactides and of coordination-insertion-type ROP protocols more broadly.
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Affiliation(s)
- Antoine Buchard
- Institute
for Sustainability, University of Bath, Bath BA2 7AY, U.K.
- Department
of Chemistry, University of Bath, Bath BA2 7AY, U.K.
| | - Matthew G. Davidson
- Institute
for Sustainability, University of Bath, Bath BA2 7AY, U.K.
- Department
of Chemistry, University of Bath, Bath BA2 7AY, U.K.
| | | | - Matthew D. Jones
- Institute
for Sustainability, University of Bath, Bath BA2 7AY, U.K.
- Department
of Chemistry, University of Bath, Bath BA2 7AY, U.K.
| | - Gabriele Kociok-Köhn
- Material
and Chemical Characterization and Analysis Facility (MC2), University of Bath, Bath BA2 7AY, U.K.
| | - Strachan N. McCormick
- Institute
for Sustainability, University of Bath, Bath BA2 7AY, U.K.
- Department
of Chemistry, University of Bath, Bath BA2 7AY, U.K.
| | - Paul Mckeown
- Department
of Chemistry, University of Bath, Bath BA2 7AY, U.K.
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3
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Nagata K, Hino A, Ube H, Sato H, Shionoya M. Synthesis and molecular structural studies of racemic chiral-at-vanadium(V) complexes using an unsymmetric achiral phenolic bidentate ligand. Dalton Trans 2023; 52:3295-3299. [PMID: 36648316 DOI: 10.1039/d2dt03436k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Mononuclear oxovanadium(V) complexes [V(O)XL (1: X = Ot-Bu, 2: X = Cl)] [H2L: 2,2'-methylene bis(4,6-di-tert-butylphenol)(4'-tert-butyl-6'-(1-adamantyl)phenol)] directed towards asymmetric catalysis have been synthesised as racemic compounds using an unsymmetric and achiral phenolic bidentate ligand (H2L), and NMR and UV-vis absorption spectroscopies, single-crystal X-ray diffraction, and IR spectroscopy revealed their racemic chiral-at-vanadium structures in solution and in the crystal. In addition, theoretical calculations revealed that the HOMO-LUMO energy gap is smaller for unsymmetric ligands, which promotes d-orbital splitting of the metal centre.
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Affiliation(s)
- Koichi Nagata
- Department of Chemistry, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
| | - Ayako Hino
- Department of Chemistry, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
| | - Hitoshi Ube
- Department of Chemistry, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
| | - Hiroyasu Sato
- Rigaku Corporation, 3-9-12 Matsubara-cho, Akishima, Tokyo 196-8666, Japan
| | - Mitsuhiko Shionoya
- Department of Chemistry, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
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4
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Wu LJ, Lee W, Kumar Ganta P, Chang YL, Chang YC, Chen HY. Multinuclear metal catalysts in ring-opening polymerization of ε‑caprolactone and lactide: Cooperative and electronic effects between metal centers. Coord Chem Rev 2023. [DOI: 10.1016/j.ccr.2022.214847] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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5
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Białek M, Fryga J, Spaleniak G, Dziuk B. Ring opening polymerization of ε-caprolactone initiated by titanium and vanadium complexes of ONO-type schiff base ligand. JOURNAL OF POLYMER RESEARCH 2021. [DOI: 10.1007/s10965-021-02419-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
AbstractA phenoxy-imine proligand with the additional OH donor group, 4,6-tBu2-2-(2-CH2(OH)-C6H4N = CH)C6H3OH (LH2), was synthesized and used to prepare group 4 and 5 complexes by reacting with Ti(OiPr)4 (LTi) and VO(OiPr)3 (LV). All new compounds were characterized by the FTIR, 1H and 13C NMR spectroscopy and LTi by the single-crystal X-ray diffraction analysis. The complexes were used as catalysts in the ring opening polymerization of ε-caprolactone. The influence of monomer/transition metal molar ratio, reaction time, polymerization temperature as well as complex type was investigated in detail. The complexes showed high (LTi) and moderate (LV) activity in ε-caprolactone polymerization and the resultant polycaprolactones exhibited Mn and Mw/Mn values ranging from 4.0 · 103 to 18.7 · 103 g/mol and from 1.4 to 2.5, respectively.
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6
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Ishikura H, Neven R, Lange T, Galetová A, Blom B, Romano D. Developments in vanadium-catalysed polymerisation reactions: A review. Inorganica Chim Acta 2021. [DOI: 10.1016/j.ica.2020.120047] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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7
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Xing T, Prior TJ, Elsegood MRJ, Semikolenova NV, Soshnikov IE, Bryliakov K, Chen K, Redshaw C. Vanadium complexes derived from oxacalix[6]arenes: structural studies and use in the ring opening homo-/co-polymerization of ε-caprolactone/δ-valerolactone and ethylene polymerization. Catal Sci Technol 2021. [DOI: 10.1039/d0cy01979h] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Oxacalix[6]arene vanadium complexes have been employed for the ROP of cyclic esters and ethylene polymerization.
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Affiliation(s)
- Tian Xing
- Plastics Collaboratory
- Department of Chemistry
- University of Hull
- Hull
- UK
| | - Timothy J. Prior
- Plastics Collaboratory
- Department of Chemistry
- University of Hull
- Hull
- UK
| | | | | | - Igor E. Soshnikov
- Boreskov Institute of Catalysis
- Novosibirsk 630090
- Russian Federation
- Novosibirsk State University
- Novosibirsk 630090
| | - Konstantin Bryliakov
- Boreskov Institute of Catalysis
- Novosibirsk 630090
- Russian Federation
- Novosibirsk State University
- Novosibirsk 630090
| | - Kai Chen
- Plastics Collaboratory
- Department of Chemistry
- University of Hull
- Hull
- UK
| | - Carl Redshaw
- Plastics Collaboratory
- Department of Chemistry
- University of Hull
- Hull
- UK
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8
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Yi J, Nakatani N, Nomura K. Solution XANES and EXAFS analysis of active species of titanium, vanadium complex catalysts in ethylene polymerisation/dimerisation and syndiospecific styrene polymerisation. Dalton Trans 2020; 49:8008-8028. [PMID: 32432279 DOI: 10.1039/d0dt01139h] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Mechanistic studies in homogeneous catalysis through the solution transition metal K Edge XANES (X-ray absorption near-edge structure) and EXAFS (Extended X-ray absorption fine structure) analysis for vanadium and titanium complex catalysts for ethylene polymerisation/dimerization, and syndiospecific styrene polymerisation, including interpretation of the XANES spectra, have been introduced. The core excitation spectra of the complexes based on the time-dependent density functional theory (TD-DFT) can be used to interpret the Ti and V K-edge features and to extract information on the electronic structure from the XANES spectra. Theoretical calculations and experimental XAS analysis should have great potential for analysing the active species.
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Affiliation(s)
- Jun Yi
- Department of Chemistry, Tokyo Metropolitan University, 1-1 Minami Osawa, Hachioji, Tokyo 192-0397, Japan.
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9
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Sun Z, Zhao Y, Prior TJ, Elsegood MRJ, Wang K, Xing T, Redshaw C. Mono-oxo molybdenum(vi) and tungsten(vi) complexes bearing chelating aryloxides: synthesis, structure and ring opening polymerization of cyclic esters. Dalton Trans 2019; 48:1454-1466. [DOI: 10.1039/c8dt04566f] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Mono-oxo Mo and W complexes bearing di- or tetra-phenolates were active for the ROP of small cyclic esters, albeit with poor control. Related metallocalix[4]arenes were less active.
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Affiliation(s)
- Ziyue Sun
- College of Chemistry and Material Science
- Northwest University
- 710069 Xi'an
- China
| | - Yanxia Zhao
- College of Chemistry and Material Science
- Northwest University
- 710069 Xi'an
- China
| | | | | | - Kuiyuan Wang
- Department of Chemistry
- The University of Hull
- Hull
- UK
| | - Tian Xing
- Department of Chemistry
- The University of Hull
- Hull
- UK
| | - Carl Redshaw
- College of Chemistry and Material Science
- Northwest University
- 710069 Xi'an
- China
- Department of Chemistry
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10
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Controlled random copolymerization of rac
-lactide and ɛ
-caprolactone by well-designed phenoxyimine Al complexes. ACTA ACUST UNITED AC 2017. [DOI: 10.1002/pola.28932] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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11
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Pappuru S, Chakraborty D, Ramkumar V. Nb and Ta benzotriazole or benzoxazole phenoxide complexes as catalysts for the ring-opening polymerization of glycidol to synthesize hyperbranched polyglycerols. Dalton Trans 2017; 46:16640-16654. [PMID: 29168518 DOI: 10.1039/c7dt02839c] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A series of novel mononuclear (1a-7a and 1b-6b) as well as tetranuclear (8a and 9a) niobium (Nb) and tantalum (Ta) complexes of benzotriazole or benzoxazole phenoxide pro-ligands bearing different substituents at the ortho and para positions of the phenol rings were synthesized and characterized. The reaction of NbCl5 or TaCl5 with one equivalent of benzotriazole or benzoxazole phenoxide pro-ligands (L1H-L6H) in dry toluene or chloroform produced the corresponding chloride (1a-6a and 1b-6b) and ethoxy (7a) mononuclear Nb and Ta complexes in high yields. Furthermore, from the mononuclear Nb complexes (1a or 4a), a new structural form of tetrameric niobium complexes (8a and 9a) was synthesized through a controlled hydrolysis reaction. The molecular structures of complexes 1b, 4b, 7a, 8a and 9a were unambiguously confirmed by single crystal X-ray diffraction analyses. Furthermore, all these complexes (1a-9a and 1b-6b) were tested as catalysts for the ring-opening polymerisation (ROP) of glycidol to synthesize hyperbranched polyglycerols (HPG) by using 1,1,1-tris(hydroxymethyl)propane (TMP) as an initiator. The degree of branching (DB) observed was 0.30-0.54, which is an indication of hyperbranched structures. In particular, for the niobium complex with electron-withdrawing substituents on the benzoxazole phenoxide pro-ligand (5a), we achieved superior behavior for the ROP of glycidol in terms of activity, control of molecular weight (Mn) and molecular weight distributions (MWDs) (92% of glycidol to HPG, Mn = 10.52 kg mol-1, MWDs <1.33, DB = 0.53 and Tg = -57 °C). A highly hydrophilic nature was observed for the synthesized HPG polymer by water contact angle measurement (20° to 35°).
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Affiliation(s)
- Sreenath Pappuru
- Department of Chemistry, Indian Institute of Technology Madras, Chennai 600 036, Tamil Nadu, India.
| | - Debashis Chakraborty
- Department of Chemistry, Indian Institute of Technology Madras, Chennai 600 036, Tamil Nadu, India.
| | - Venkatachalam Ramkumar
- Single Crystal XRD Lab, Department of Chemistry, Indian Institute of Technology Madras, Chennai 600 036, Tamil Nadu, India
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12
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Use of Metal Catalysts Bearing Schiff Base Macrocycles for the Ring Opening Polymerization (ROP) of Cyclic Esters. Catalysts 2017. [DOI: 10.3390/catal7050165] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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13
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Lee SL, Hu FL, Shang XJ, Shi YX, Tan AL, Mizera J, Clegg JK, Zhang WH, Young DJ, Lang JP. Efficient ring-opening polymerization (ROP) of ε-caprolactone catalysed by isomeric pyridyl β-diketonate iron(iii) complexes. NEW J CHEM 2017. [DOI: 10.1039/c7nj03571c] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A series of FeL3 complexes of dipyridyl β-diketones were structurally characterized and their catalytic properties investigated.
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Affiliation(s)
- Sze-Ling Lee
- Faculty of Science
- Universiti Brunei Darussalam
- Brunei
| | - Fei-Long Hu
- College of Chemistry
- Chemical Engineering and Materials Science
- Soochow University
- Suzhou 215123
- People's Republic of China
| | - Xiu-Juan Shang
- College of Chemistry
- Chemical Engineering and Materials Science
- Soochow University
- Suzhou 215123
- People's Republic of China
| | - Yi-Xiang Shi
- College of Chemistry
- Chemical Engineering and Materials Science
- Soochow University
- Suzhou 215123
- People's Republic of China
| | - Ai Ling Tan
- Faculty of Science
- Universiti Brunei Darussalam
- Brunei
| | - Jens Mizera
- Department of Chemistry and Food Chemistry
- Technical University Dresden
- 01062 Dresden
- Germany
| | - Jack K. Clegg
- School of Chemistry and Molecular Biosciences
- The University of Queensland, Brisbane
- St. Lucia
- Australia
| | - Wen-Hua Zhang
- College of Chemistry
- Chemical Engineering and Materials Science
- Soochow University
- Suzhou 215123
- People's Republic of China
| | - David J. Young
- Faculty of Science, Health, Education and Engineering
- University of the Sunshine Coast
- Maroochydore DC
- Australia
| | - Jian-Ping Lang
- College of Chemistry
- Chemical Engineering and Materials Science
- Soochow University
- Suzhou 215123
- People's Republic of China
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14
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Molecular Catalysis for Precise Olefin Polymerization and ROP 2015. Catalysts 2016. [DOI: 10.3390/catal6040053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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