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. [Figure not available: see fulltext.]
Bibliographical noteFunding Information:
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.
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