Highly Stereoselective Heterogeneous Diene Polymerization by Co-MFU-4
Author(s)
Wu, Zhenwei
Zhang, Guanghui
Miller, Jeffrey T.
Dubey, Romain
Comito, Robert J
Rieth, Adam Joseph
Hendon, Christopher H
Dinca, Mircea
Date Issued
August 2017
Journal
Journal of the American Chemical Society
Publisher
American Chemical Society (ACS)
Citation
Dubey, Romain J.-C. et al. “Highly Stereoselective Heterogeneous Diene Polymerization by Co-MFU-4l: A Single-Site Catalyst Prepared by Cation Exchange.” Journal of the American Chemical Society 139, 36 (August 2017): 12664–12669 © 2017 American Chemical Society
Version
Author's final manuscript
Abstract
Molecular catalysts offer tremendous advantages for stereoselective polymerization because their activity and selectivity can be optimized and understood mechanistically using the familiar tools of organometallic chemistry. Yet, this exquisite control over selectivity comes at an operational price that is generally not justifiable for the large-scale manufacture of polyfolefins. In this report, we identify Co-MFU-4l, prepared by cation exchange in a metal–organic framework, as a solid catalyst for the polymerization of 1,3-butadiene with high stereoselectivity (>99% 1,4-cis). To our knowledge, this is the highest stereoselectivity achieved with a heterogeneous catalyst for this transformation. The polymer’s low polydispersity (PDI ≈ 2) and the catalyst’s ready recovery and low leaching indicate that our material is a structurally resilient single-site heterogeneous catalyst. Further characterization of Co-MFU-4l by X-ray absorption spectroscopy provided evidence for discrete, tris-pyrazolylborate-like coordination of Co(II). With this information, we identify a soluble cobalt complex that mimics the structure and reactivity of Co-MFU-4l, thus providing a well-defined platform for studying the catalytic mechanism in the solution phase. This work underscores the capacity for small molecule-like tunability and mechanistic tractability available to transition metal catalysis in metal–organic frameworks.
MIT Department
Massachusetts Institute of Technology. Department of Chemistry
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DOI of Published Version
https://doi.org/10.1021/jacs.7b06841
