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Iron-catalysed ring-opening metathesis polymerization of olefins and mechanistic studies

Abstract

The olefin metathesis reaction is among the most widely applicable catalytic reactions for carbon–carbon double bond formation. Currently, Mo– and Ru–carbene catalysts are the most common choices for this reaction. It has been suggested that an iron-based catalyst would be a desirable economical and biocompatible substitute of the Ru catalysts; however, practical solutions in this regard are still lacking. Here, we report the discovery and mechanistic studies of three-coordinate iron(II) catalysts for ring-opening metathesis polymerization of olefins. Remarkably, their reactivity enabled the formation of polynorbornene with stereoregularity and high molecular weight (>107 g mol–1). The polymerization in the presence of styrene revealed cross metathesis reactivity with iron catalysts. Mechanistic studies suggest the possible role of metal–ligand cooperation in formation of the productive catalyst. This work opens the door to the development of iron complexes that can be economical and biocompatible catalysts for olefin metathesis reactions.

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Fig. 1: Preparation and structures of iron complexes.
Fig. 2: X-ray structures of 2-PtBu, 2-tipp and 3.
Fig. 3: Iron-catalysed ROMP of norbornene and characterization of the product.
Fig. 4: Investigations aimed at understanding the initiation mechanism of the ROMP.
Fig. 5: Attempts aimed at trapping catalytic intermediates.
Fig. 6: DFT calculations of the reaction mechanisms.

Data availability

Synthetic procedures, NMR spectra and characterization data for all the new compounds are available in the Supplementary Information. Synthetic procedures, NMR and infrared spectra, GPC traces, DLS cumulant fits, a TEM image and characterization data for the polymers are available within this article and its Supplementary Information. NMR and EPR spectra, a gas chromatography–mass spectrometry chromatogram and a mass spectrum, and kinetic data used for mechanistic studies are available in the Supplementary Information. Crystallographic data for the structures reported in this Article and its Supplementary Information were deposited at the Cambridge Crystallographic Data Centre under deposition numbers CCDC 1562562 (1), 1562561 (1-Br), 1562563 (1-PtBu), 1562560 (1-tipp), 1562567 (FeCl2(PNdipp-iPr-Me2)), 2562568 (2-PtBu), 1562565 (2-tipp), 1562564 (3), 1562566 (5), 1562569 (6), 1589216 (8), 1589215 (9), 2078786 (10) and 1589214 (11). Copies of the data can be obtained free of charge via https://www.ccdc.cam.ac.uk/structures/. Cartesian coordinates of calculated complexes are available as a Supplementary Data file. Any further relevant data are available from the authors upon reasonable request.

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Acknowledgements

This research was supported by the Israel Science Foundation (1721/13, D.M.) and the Japan Society for the Promotion of Science (18K14230, S.T.). Electron microscopy studies were supported in part by the Irving and Cherna Moskowitz Center for Nano and Bio-Nano Imaging at the Weizmann Institute of Science. This work was supported by Okinawa Institute of Science and Technology Graduate University instrumental analysis and engineering sections. S.T. thanks M. C. Roy for the assistance with solid-state NMR measurement. D.M. holds the Israel Matz Professorial Chair. All data are provided in the Supplementary Information. This manuscript is dedicated to the memory of Professor Robert H. Grubbs.

Author information

Authors and Affiliations

Authors

Contributions

S.T. discovered the iron-catalysed ROMP, designed and developed the iron catalysts and conducted the ROMP of olefins, characterization of the polymers and mechanistic studies. M.A.I. conducted the DFT calculations. M.F. examined the reproducibility of the iron-catalysed ROMP and was involved in the mechanistic studies. O.R.-W. was involved in the development of the iron catalysts. G.L., Y.D.-P. and L.J.W.S. conducted the X-ray diffraction measurements. G.L. conducted the superconducting quantum interference device magnetic field measurements. L.A. conducted the diffusion-ordered NMR spectroscopy measurements. R.C. conducted the EPR measurements. S.G.W. conducted the TEM measurements. I.C.-O. conducted the inductively coupled plasma mass spectrometry measurements. R.A.S., R.S. and M.E. conducted the GPC measurements. D.M. conceived and directed the research programme. S.T. and D.M. wrote the manuscript, with revisions provided by the other authors.

Corresponding authors

Correspondence to Satoshi Takebayashi or David Milstein.

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The authors declare no competing interests.

Peer review

Peer review information

Nature Catalysis thanks Ed Brothers and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary information

Supplementary Information

Supplementary Figs. 1–67, Tables 1–15, Methods, Notes 1–6 and references.

Supplementary Data 1

DFT coordinates.

Supplementary Data 2

X-ray diffraction data for complex 1.

Supplementary Data 3

X-ray diffraction data for complex 1-Br.

Supplementary Data 4

X-ray diffraction data for complex 1-PtBu.

Supplementary Data 5

X-ray diffraction data for complex 1-tipp.

Supplementary Data 6

X-ray diffraction data for complex 2-PtBu.

Supplementary Data 7

X-ray diffraction data for complex 2-tipp.

Supplementary Data 8

X-ray diffraction data for complex 3.

Supplementary Data 9

X-ray diffraction data for complex 5.

Supplementary Data 10

X-ray diffraction data for complex 6.

Supplementary Data 11

X-ray diffraction data for FeCl2PNdipp-iPrMe2.

Supplementary Data 12

X-ray diffraction data for complex 8.

Supplementary Data 13

X-ray diffraction data for complex 9.

Supplementary Data 14

X-ray diffraction data for complex 10.

Supplementary Data 15

X-ray diffraction data for complex 11.

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Takebayashi, S., Iron, M.A., Feller, M. et al. Iron-catalysed ring-opening metathesis polymerization of olefins and mechanistic studies. Nat Catal 5, 494–502 (2022). https://doi.org/10.1038/s41929-022-00793-4

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