1
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Münster K, Raeder J, Walter MD. Synthesis and characterisation of an enantiomerically pure scandium pentadienyl complex and its application in the polymerisation of rac-lactide. Dalton Trans 2021; 51:986-997. [PMID: 34931626 DOI: 10.1039/d1dt03920b] [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
The alkyl-functionalised scandium complex [(pdl*SiMe2NtBu)Sc(thf)(CH2SiMe3)] (2) was synthesised in enantiomerically pure form and characterised by NMR spectroscopy and X-ray diffraction analysis. Complex 2 features a chiral constrained geometry ligand derived from the natural compound (1R)-(-)-myrtenal, in which the pentadienyl (pdl*) fragment coordinates in η3:η2-allyl-en fashion to the scandium atom. Compound 2 catalyses the polymerisation of rac-lactide at 30 °C and 50 °C yielding amorphous poly(lactide) with slightly heterotactic enchainment (Pm = 0.36 and 0.37). In agreement with the data obtained from GPC and DSC measurements, a chain-end control mechanism is proposed with fast chain propagation relative to the initiation, which leads to broad molecular weight distributions (Đ ≈ 1.80) and higher than expected molecular weights. Furthermore, chain transfer processes are observed, but only small amounts of transesterification and racemisation occur. Kinetic studies reveal a second-order dependence in rac-lactide (monomer) concentration and a first-order dependence in the concentration of catalyst 2.
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Affiliation(s)
- Katharina Münster
- Technische Universität Braunschweig, Institut für Anorganische und Analytische Chemie, Hagenring 30, 38106 Braunschweig, Germany.
| | - Jan Raeder
- Technische Universität Braunschweig, Institut für Anorganische und Analytische Chemie, Hagenring 30, 38106 Braunschweig, Germany.
| | - Marc D Walter
- Technische Universität Braunschweig, Institut für Anorganische und Analytische Chemie, Hagenring 30, 38106 Braunschweig, Germany.
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2
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Münster K, Fecker AC, Raeder J, Freytag M, Jones PG, Walter MD. Enantiomerically Pure Constrained Geometry Complexes of the Rare-Earth Metals Featuring a Dianionic N-Donor Functionalised Pentadienyl Ligand: Synthesis and Characterisation. Chemistry 2020; 26:16098-16110. [PMID: 32735382 PMCID: PMC7756846 DOI: 10.1002/chem.202003170] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 07/31/2020] [Indexed: 11/07/2022]
Abstract
We report the preparation of enantiomerically pure constrained geometry complexes (cgc) of the rare-earth metals bearing a pentadienyl moiety (pdl) derived from the natural product (1R)-(-)-myrtenal. The potassium salt 1, [Kpdl*], was treated with ClSiMe2 NHtBu, and the resulting pentadiene 2 was deprotonated with the Schlosser-type base KOtPen/nBuLi (tPen=CMe2 (CH2 Me)) to yield the dipotassium salt [K2 (pdl*SiMe2 NtBu)] (3). However, 3 rearranges in THF solution to its isomer 3' by a 1,3-H shift, which elongates the bridge between the pdl and SiMe2 NtBu moieties by one CH2 unit. This is crucial for the successful formation of various monomeric C1 - or dimeric C2 -symmetric rare-earth cgc complexes with additional halide, tetraborohydride, amido and alkyl functionalities. All compounds have been extensively characterised by solid-state X-ray diffraction analysis, solution NMR spectroscopy and elemental analyses.
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Affiliation(s)
- Katharina Münster
- Institut für Anorganische und Analytische ChemieTechnische Universität BraunschweigHagenring 3038106BraunschweigGermany
| | - Ann Christin Fecker
- Institut für Anorganische und Analytische ChemieTechnische Universität BraunschweigHagenring 3038106BraunschweigGermany
| | - Jan Raeder
- Institut für Anorganische und Analytische ChemieTechnische Universität BraunschweigHagenring 3038106BraunschweigGermany
| | - Matthias Freytag
- Institut für Anorganische und Analytische ChemieTechnische Universität BraunschweigHagenring 3038106BraunschweigGermany
| | - Peter G. Jones
- Institut für Anorganische und Analytische ChemieTechnische Universität BraunschweigHagenring 3038106BraunschweigGermany
| | - Marc D. Walter
- Institut für Anorganische und Analytische ChemieTechnische Universität BraunschweigHagenring 3038106BraunschweigGermany
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3
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Raeder J, Reiners M, Baumgarten R, Münster K, Baabe D, Freytag M, Jones PG, Walter MD. Synthesis and molecular structure of pentadienyl complexes of the rare-earth metals. Dalton Trans 2018; 47:14468-14482. [DOI: 10.1039/c8dt03123a] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
In combination with small and difficult to reduce rare-earth metals pdl′ undergoes CH-bond activations instead of sterically induced reductions to form dimeric complexes with a unique bridging six-membered metallacycle as the central structural motif.
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Affiliation(s)
- Jan Raeder
- Technische Universität Braunschweig
- Institut für Anorganische und Analytische Chemie
- 38106 Braunschweig
- Germany
| | - Matthias Reiners
- Technische Universität Braunschweig
- Institut für Anorganische und Analytische Chemie
- 38106 Braunschweig
- Germany
| | - Robert Baumgarten
- Technische Universität Braunschweig
- Institut für Anorganische und Analytische Chemie
- 38106 Braunschweig
- Germany
| | - Katharina Münster
- Technische Universität Braunschweig
- Institut für Anorganische und Analytische Chemie
- 38106 Braunschweig
- Germany
| | - Dirk Baabe
- Technische Universität Braunschweig
- Institut für Anorganische und Analytische Chemie
- 38106 Braunschweig
- Germany
| | - Matthias Freytag
- Technische Universität Braunschweig
- Institut für Anorganische und Analytische Chemie
- 38106 Braunschweig
- Germany
| | - Peter G. Jones
- Technische Universität Braunschweig
- Institut für Anorganische und Analytische Chemie
- 38106 Braunschweig
- Germany
| | - Marc D. Walter
- Technische Universität Braunschweig
- Institut für Anorganische und Analytische Chemie
- 38106 Braunschweig
- Germany
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4
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Fecker AC, Freytag M, Jones PG, Zhao N, Zi G, Walter MD. Preparation of enantiomerically pure open calcocene and strontocene complexes and their application in ring opening polymerizations of rac-lactide. Dalton Trans 2015; 44:16325-31. [PMID: 26299415 DOI: 10.1039/c5dt02851e] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The synthesis of C2 symmetric enantiomerically pure open Ca and Sr metallocenes, [(η(5)-pdl*)2Ca(thf)] (1) and [(η(5)-pdl*)2Sr(thf)2] (2) (pdl* = dimethylnopadienyl) is described and these complexes were fully characterized. The solid state structures confirm that the pdl* ligands coordinate exclusively with the less sterically demanding site to the Ca and Sr atoms. These complexes are active catalysts for the controlled ring opening polymerization (ROP) of rac-lactide to give heterotactically enriched polylactides (PL) with narrow polydispersities (PDI = 1.29-1.31) and without adding further activators.
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Affiliation(s)
- Ann Christin Fecker
- Institut für Anorganische und Analytische Chemie, Technische Universität, Braunschweig, Hagenring 30, 38106 Braunschweig, Germany.
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5
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Day BM, McDouall JJW, Clayden J, Layfield RA. Directed Lithiation of Pentadienylsilanes. Organometallics 2015. [DOI: 10.1021/om501144f] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- Benjamin M. Day
- School of Chemistry, The University of Manchester, Manchester, M13 9PL, U.K
| | | | - Jonathan Clayden
- School of Chemistry, The University of Manchester, Manchester, M13 9PL, U.K
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6
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Day BM, Chilton NF, Layfield RA. Molecular and electronic structures of donor-functionalized dysprosium pentadienyl complexes. Dalton Trans 2015; 44:7109-13. [DOI: 10.1039/c5dt00346f] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The molecular structures of two dysprosium complexes of donor-functionalized pentadienyl ligands are described. Electronic structure calculations reveal that the W-shaped pentadienyl ligand strongly influences the orientation of the main magnetic axis of the ground Kramers doublets in both complexes.
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7
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Fecker AC, Crăciun BF, Schweyen P, Freytag M, Jones PG, Walter MD. Synthesis and Characterization of N-Donor-Functionalized Enantiomerically Pure Pentadienyl Ligands Derived from (1R)-(−)-Myrtenal. Organometallics 2014. [DOI: 10.1021/om501024j] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ann Christin Fecker
- Institut für Anorganische
und Analytische Chemie, Technische Universität Braunschweig, Hagenring
30, 38106 Braunschweig, Germany
| | - Bogdan-Florin Crăciun
- Institut für Anorganische
und Analytische Chemie, Technische Universität Braunschweig, Hagenring
30, 38106 Braunschweig, Germany
| | - Peter Schweyen
- Institut für Anorganische
und Analytische Chemie, Technische Universität Braunschweig, Hagenring
30, 38106 Braunschweig, Germany
| | - Matthias Freytag
- Institut für Anorganische
und Analytische Chemie, Technische Universität Braunschweig, Hagenring
30, 38106 Braunschweig, Germany
| | - Peter G. Jones
- Institut für Anorganische
und Analytische Chemie, Technische Universität Braunschweig, Hagenring
30, 38106 Braunschweig, Germany
| | - Marc D. Walter
- Institut für Anorganische
und Analytische Chemie, Technische Universität Braunschweig, Hagenring
30, 38106 Braunschweig, Germany
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8
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Fecker AC, Crăciun BF, Freytag M, Jones PG, Walter MD. Synthesis and Coordination Chemistry of Pentadienyl Ligands Derived from (1R)-(−)-Myrtenal. Organometallics 2014. [DOI: 10.1021/om500513m] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Ann Christin Fecker
- Institut
für Anorganische
und Analytische Chemie, Technische Universität Braunschweig, Hagenring
30, 38106 Braunschweig, Germany
| | - Bogdan-Florin Crăciun
- Institut
für Anorganische
und Analytische Chemie, Technische Universität Braunschweig, Hagenring
30, 38106 Braunschweig, Germany
| | - Matthias Freytag
- Institut
für Anorganische
und Analytische Chemie, Technische Universität Braunschweig, Hagenring
30, 38106 Braunschweig, Germany
| | - Peter G. Jones
- Institut
für Anorganische
und Analytische Chemie, Technische Universität Braunschweig, Hagenring
30, 38106 Braunschweig, Germany
| | - Marc D. Walter
- Institut
für Anorganische
und Analytische Chemie, Technische Universität Braunschweig, Hagenring
30, 38106 Braunschweig, Germany
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9
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Eckert PK, Schnura B, Strohmann C. Unexpected structural motifs in diamine coordination compounds with allyllithium. Chem Commun (Camb) 2014; 50:2532-4. [DOI: 10.1039/c3cc48873j] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Affiliation(s)
- Prisca K Eckert
- TU Dortmund, Anorganische Chemie, Otto-Hahn-Str. 6, 44149 Dortmund, Germany.
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10
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Day BM, Clayden J, Layfield RA. Structural Influences in Lithium Pentadienylsilane Complexes. Organometallics 2013. [DOI: 10.1021/om400596y] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Benjamin M. Day
- School of Chemistry, The University of Manchester, Oxford
Road, Manchester M13 9PL, U.K
| | - Jonathan Clayden
- School of Chemistry, The University of Manchester, Oxford
Road, Manchester M13 9PL, U.K
| | - Richard A. Layfield
- School of Chemistry, The University of Manchester, Oxford
Road, Manchester M13 9PL, U.K
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11
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Fecker AC, Glöckner A, Daniliuc CG, Freytag M, Jones PG, Walter MD. Synthesis and Coordination Chemistry of an Enantiomerically Pure Pentadienyl Ligand. Organometallics 2013. [DOI: 10.1021/om301189g] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Ann Christin Fecker
- Institut für Anorganische und Analytische Chemie, Technische Universität Braunschweig, Hagenring 30, 38106 Braunschweig, Germany
| | - Andreas Glöckner
- Institut für Anorganische und Analytische Chemie, Technische Universität Braunschweig, Hagenring 30, 38106 Braunschweig, Germany
| | - Constantin G. Daniliuc
- Institut für Anorganische und Analytische Chemie, Technische Universität Braunschweig, Hagenring 30, 38106 Braunschweig, Germany
| | - Matthias Freytag
- Institut für Anorganische und Analytische Chemie, Technische Universität Braunschweig, Hagenring 30, 38106 Braunschweig, Germany
| | - Peter G. Jones
- Institut für Anorganische und Analytische Chemie, Technische Universität Braunschweig, Hagenring 30, 38106 Braunschweig, Germany
| | - Marc D. Walter
- Institut für Anorganische und Analytische Chemie, Technische Universität Braunschweig, Hagenring 30, 38106 Braunschweig, Germany
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12
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Glöckner A, Bannenberg T, Ibrom K, Daniliuc CG, Freytag M, Jones PG, Walter MD, Tamm M. Flexibility of an Open Indenyl Ligand in Iron(II) Complexes. Organometallics 2012. [DOI: 10.1021/om3003009] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- Andreas Glöckner
- Institut für Anorganische
und Analytische Chemie, Technische Universität Braunschweig, Hagenring 30, 38106 Braunschweig, Germany
| | - Thomas Bannenberg
- Institut für Anorganische
und Analytische Chemie, Technische Universität Braunschweig, Hagenring 30, 38106 Braunschweig, Germany
| | - Kerstin Ibrom
- NMR-Labor der Chemischen Institute, Technische Universität Braunschweig, Hagenring
30, 38106 Braunschweig, Germany
| | - Constantin G. Daniliuc
- Institut für Anorganische
und Analytische Chemie, Technische Universität Braunschweig, Hagenring 30, 38106 Braunschweig, Germany
| | - Matthias Freytag
- Institut für Anorganische
und Analytische Chemie, Technische Universität Braunschweig, Hagenring 30, 38106 Braunschweig, Germany
| | - Peter G. Jones
- Institut für Anorganische
und Analytische Chemie, Technische Universität Braunschweig, Hagenring 30, 38106 Braunschweig, Germany
| | - Marc D. Walter
- Institut für Anorganische
und Analytische Chemie, Technische Universität Braunschweig, Hagenring 30, 38106 Braunschweig, Germany
| | - Matthias Tamm
- Institut für Anorganische
und Analytische Chemie, Technische Universität Braunschweig, Hagenring 30, 38106 Braunschweig, Germany
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13
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