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.
This is a preview of subscription content, access via your institution
Access Nature and 54 other Nature Portfolio journals
Get Nature+, our best-value online-access subscription
$29.99 / 30 days
cancel any time
Subscribe to this journal
Receive 12 digital issues and online access to articles
$119.00 per year
only $9.92 per issue
Rent or buy this article
Get just this article for as long as you need it
Prices may be subject to local taxes which are calculated during checkout
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.
Grubbs, R. G., Wenzel, A. G., O’Leary, D. J. & Khosravi, E. (eds) Handbook of Metathesis 2nd edn (Wiley-VCH, 2015).
Eisenstein, O., Hoffmann, R. & Rossi, A. R. Some geometrical and electronic features of the intermediate stages of olefin metathesis. J. Am. Chem. Soc. 103, 5582–5584 (1981).
Bielawski, C. W. & Grubbs, R. H. Living ring-opening metathesis polymerization. Prog. Polym. Sci. 32, 1–29 (2007).
Bauer, I. & Knölker, H.-J. Iron catalysis in organic synthesis. Chem. Rev. 115, 3170–3387 (2015).
Vasiliu, M., Arduengo, A. J. III & Dixon, D. A. Role of electronegative substituents on the bond energies in the Grubbs metathesis catalysts for M = Fe, Ru, Os. J. Phys. Chem. C 118, 13563–13577 (2014).
Poater, A., Vummaleti, S. V. C., Pump, E. & Cavallo, L. Comparing Ru and Fe-catalyzed olefin metathesis. Dalton Trans. 2014, 11216–11220 (2014).
Yang, B. & Truhlar, D. G. Computational design of an iron catalyst for olefin metathesis. Organometallics 37, 3917–3927 (2018).
De Brito Sá, É., Rodríguez-Santiago, L., Sodupe, M. & Solans-Monfort, X. Toward olefin metathesis with iron carbene complexes: benefits of tridentate σ-donating ligands. Organometallics 35, 3914–3923 (2016).
Mauksch, M. & Tsogoeva, S. B. Iron-catalyzed olefin metathesis with low-valent iron alkylidenes. Chem. Eur. J. 23, 10264–10269 (2017).
Sacchi, M. C. et al. Vinylic polymerization of norbornene by late transition metal-based catalysis. Macromol. Chem. Phys. 202, 2052–2058 (2001).
Belov, D. S., Mathivathanan, L., Beazley, M. J., Martin, W. B. & Bukhryakov, K. Stereospecific ring-opening metathesis polymerization of norbornene catalyzed by Iron complexes. Angew. Chem. Int. Ed. 60, 2934–2938 (2021).
Belov, D. S., Tejeda, G. & Bukhryakov, K. V. Olefin metathesis by first-row transition metals. ChemPlusChem 86, 924–937 (2021).
Louie, J. & Grubbs, R. H. Reaction of diazoalkanes with iron phosphine complexes affords novel phosphazine complexes. Organometallics 20, 481–484 (2001).
Russell, S. K. et al. Synthesis, electronic structure and reactivity of bis(imino)pyridine iron carbene complexes: evidence for a carbene radical. Chem. Sci. 5, 1168–1174 (2014).
Lindley, B. M., Jacobs, B. P., MacMillan, S. N. & Wolczanski, P. T. Neutral Fe(IV) alkylidenes, including some that bind dinitrogen. Chem. Commun. 52, 3891–3894 (2016).
Hoffbauer, M. R. & Iluc, V. M. [2+2] cycloadditions with an iron carbene: a critical step in enyne metathesis. J. Am. Chem. Soc. 143, 5592–5597 (2021).
Gunanathan, C. & Milstein, D. Bond activation and catalysis by ruthenium pincer complexes. Chem. Rev. 114, 12024–12087 (2014).
Khusnutdinova, J. R. & Milstein, D. Metal-ligand cooperation. Angew. Chem. Int. Ed. 54, 12236–12273 (2015).
Mol, J. C. Industrial applications of olefin metathesis. J. Mol. Catal. A Chem. 213, 39–45 (2004).
Vela, J. et al. Reversible beta-hydrogen elimination of three-coordinate iron(II) alkyl complexes: mechanistic and thermodynamic studies. Organometallics 23, 5226–5239 (2004).
Mathies, G. et al. High-frequency EPR study of the high-spin FeII complex Fe[(SPPh2)2N]2. J. Magn. Reson. 224, 94–100 (2012).
Pranckevicius, C., Iovan, D. A. & Stephan, D. W. Three and four coordinate Fe carbodiphosphorane complexes. Dalton Trans. 45, 16820–16825 (2016).
Holland, P. L. Electronic structure and reactivity of three-coordinate iron complexes. Acc. Chem. Res. 41, 905–914 (2008).
Smith, J. M., Lachicotte, R. J. & Holland, P. L. Three-coordinate, 12-electron organometallic complexes of iron(II) supported by a bulky β-diketiminate ligand: synthesis and insertion of CO to give square-pyramidal complexes. Organometallics 21, 4808–4814 (2002).
Schrock, R. R. & Copéret, C. Formation of high-oxidation-state metal–carbon double bonds. Organometallics 36, 1884–1892 (2017).
Andres, H. et al. Planar three-coordinate high-spin FeII complexes with large orbital angular momentum: Mössbauer, electron paramagnetic resonance, and electronic structure studies. J. Am. Chem. Soc. 124, 3012–3025 (2002).
Ott, J. C., Wadepohl, H., Enders, M. & Gade, L. H. Taking solution proton NMR to its extreme: prediction and detection of a hydride resonance in an intermediate-spin iron complex. J. Am. Chem. Soc. 140, 17413–17417 (2018).
Schwab, P., Grubbs, R. H. & Ziller, J. W. Synthesis and applications of RuCl2(=CHR′)(PR3)2: the influence of the alkylidene moiety on metathesis activity. J. Am. Chem. Soc. 118, 100–110 (1996).
Johns, A. M., Ahmed, T. S., Jackson, B. W., Grubbs, R. H. & Pederson, R. L. High trans kinetic selectivity in ruthenium-based olefin cross-metathesis through stereoretention. Org. Lett. 18, 772–775 (2016).
Nguyen, T. T. et al. Kinetically controlled E-selective catalytic olefin metathesis. Science 352, 569–575 (2016).
Wo, S. K., Lucki, J., Rabek, J. F. & Rånby, B. Photo-oxidative degradation of polynorbornene (part I). Polym. Photochem. 2, 73–85 (1982).
Hyvl, J., Autenrieth, B. & Schrock, R. R. Proof of tacticity of stereoregular ROMP polymers through post polymerization modification. Macromolecules 48, 3148–3152 (2015).
Flook, M. M., Börner, J., Kilyanek, S. M., Gerber, L. C. H. & Schrock, R. R. Five-coordinate rearrangements of metallacyclobutane intermediates during ring-opening metathesis polymerization of 2,3-dicarboalkoxynorbornenes by molybdenum and tungsten monoalkoxide pyrrolide initiators. Organometallics 31, 6231–6243 (2012).
Autenrieth, B. & Schrock, R. R. Stereospecific ring-opening metathesis polymerization (ROMP) of norbornene and tetracyclododecene by Mo and W initiators. Macromolecules 48, 2493–2503 (2015).
Rosebrugh, L. E., Marx, V. M., Keitz, B. K. & Grubbs, R. H. Synthesis of highly cis, syndiotactic polymers via ring-opening metathesis polymerization using ruthenium metathesis catalysts. J. Am. Chem. Soc. 135, 10032–10035 (2013).
Gonsales, S. A. et al. Highly tactic cyclic polynorbornene: stereoselective ring expansion metathesis polymerization of norbornene catalyzed by a new tethered tungsten-alkylidene catalyst. J. Am. Chem. Soc. 138, 4996–4999 (2016).
Nadif, S. S. et al. Introducing “ynene” metathesis: ring-expansion metathesis polymerization leads to highly cis and syndiotactic cyclic polymers of norbornene. J. Am. Chem. Soc. 138, 6408–6411 (2016).
Ogawa, K. A., Goetz, A. E. & Boydston, A. J. Metal-free ring-opening metathesis polymerization. J. Am. Chem. Soc. 137, 1400–1403 (2015).
Nomura, K. & Hou, X. Cis-specific chain transfer ring-opening metathesis polymerization using a vanadium(V) alkylidene catalyst for efficient synthesis of end-functionalized polymers. Organometallics 36, 4103–4106 (2017).
Mutch, A., Leconte, M., Lefebvre, F. & Basset, J.-M. Effect of alcohols and epoxides on the rate of ROMP of norbornene by a ruthenium trichloride catalyst. J. Mol. Catal. A 133, 191–199 (1998).
Fitzgerald, R. P. & Rooney, A. D. Novel co-catalytic activity of zinc metal with classical initiators for the ring opening polymerisation of norbornene. J. Mol. Catal. A 261, 24–28 (2007).
Wang, D. et al. Cationic RuII complexes with N-heterocyclic carbene ligands for UV induced ring-opening metathesis polymerization. Angew. Chem. Int. Ed. 47, 3267–3270 (2008).
Hartwig, J. F. Organotransition Metal Chemistry: from Bonding to Catalysis (University Science Books, 2010).
Zhang, Z., Zhang, Y. & Wang, J. Carbonylation of metal carbene with carbon monoxide: generation of ketene. ACS Catal. 1, 1621–1630 (2011).
Butschke, B., Feller, M., Diskin-Posner, Y. & Milstein, D. Ketone hydrogenation catalyzed by a new iron(II)–PNN complex. Catal. Sci. Technol. 6, 4428–4437 (2016).
Iron, M. A., Ben-Ari, E., Cohen, R. & Milstein, D. Metal–ligand cooperation in the trans addition of dihydrogen to a pincer Ir(I) complex: a DFT study. Dalton Trans. 2009, 9433–9439 (2009).
Montag, M., Zhang, J. & Milstein, D. Aldehyde binding through reversible C–C coupling with the pincer ligand upon alcohol dehydrogenation by a PNP–ruthenium catalyst. J. Am. Chem. Soc. 134, 10325–10328 (2012).
Nerush, A. et al. Template catalysis by metal–ligand cooperation. C–C bond formation via conjugate addition of non-activated nitriles under mild, base-free conditions catalyzed by a manganese pincer complex. J. Am. Chem. Soc. 138, 6985–6997 (2016).
Vogt, M. et al. A new mode of activation of CO2 by metal–ligand cooperation with reversible C—C and M—O bond formation at ambient temperature. Chem. Eur. J. 18, 9194–9197 (2012).
Manganiello, F. J., Radcliffe, M. D. & Jones, W. M. Rotation barriers around the carbene–metal bond of transition metal complexes of cycloheptatrienylidenes. J. Organomet. Chem. 228, 273–279 (1982).
Rosebrugh, L. E. et al. Probing stereoselectivity in ring-opening metathesis polymerization mediated by cyclometalated ruthenium-based catalysts: a combined experimental and computational study. J. Am. Chem. Soc. 138, 1394–1405 (2016).
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.
Peer review information
Nature Catalysis thanks Ed Brothers and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Supplementary Figs. 1–67, Tables 1–15, Methods, Notes 1–6 and references.
Supplementary Data 1
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.
Rights and permissions
About this article
Cite this article
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