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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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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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.
The authors declare no competing interests.
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Supplementary Figs. 1–67, Tables 1–15, Methods, Notes 1–6 and references.
X-ray diffraction data for complex 1.
X-ray diffraction data for complex 1-Br.
X-ray diffraction data for complex 1-PtBu.
X-ray diffraction data for complex 1-tipp.
X-ray diffraction data for complex 2-PtBu.
X-ray diffraction data for complex 2-tipp.
X-ray diffraction data for complex 3.
X-ray diffraction data for complex 5.
X-ray diffraction data for complex 6.
X-ray diffraction data for FeCl2PNdipp-iPrMe2.
X-ray diffraction data for complex 8.
X-ray diffraction data for complex 9.
X-ray diffraction data for complex 10.
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