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Abstract Construction of robust, stereocomplexed (sc) crystalline material, based on a recently discovered infinitely recyclable polymer system, requires blending of enantiomeric polymer chains produced from respective enantiopure, fused six‐five bicyclic lactones. Herein, the stereoselective polymerization of the racemic monomer by yttrium catalysts bearing tetradentate ligands is reported, where the tethered donor sidearm switches the heteroselectivity of the catalyst to isoselectivity when it is changed from the β‐OMe to β‐NMe2sidearm. The latter catalyst produces an isotactic stereoblock polymer (Pmup to 0.95) that forms the crystalline sc‐material with aTmof up to 171 °C. This sc‐material can be fully depolymerized back to rac‐monomer in a quantitative yield and purity, thus establishing its circular life cycle.
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Ring Expansion Metathesis Polymerization (REMP) Initiators with an Unusual Ancillary Ligand
Abstract Tethered tungsten‐alkylidenes bearing azoimido ligands (M≡Nγ‐Nβ=NαR) are synthesized, characterized, and tested as initiators for ring expansion metathesis polymerization (REMP). While these ligands are typically unstable and prone to dinitrogen loss, this work demonstrates that tethered alkylidene complexes bearing azoimido ligands are stable enough to be REMP initiators. Moreover, they are more efficient, long‐lived, and stereoselective than their corresponding imido derivatives (M≡NR). Density Functional Theory (DFT) analysis of the azoimido complexes provides insight into their unusual stability.
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- Award ID(s):
- 2154377
- PAR ID:
- 10642274
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- ChemCatChem
- Volume:
- 16
- Issue:
- 13
- ISSN:
- 1867-3880
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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