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A Dinuclear Mechanism Implicated in Controlled Carbene Polymerization
- Zhukhovitskiy, Aleksandr V., Kobylianskii, Ilia J., Thomas, Andy A., Evans, Austin M., Delaney, Connor P., Flanders, Nathan C., Denmark, Scott E., Dichtel, William R., Toste, F. Dean
- Journal of the American Chemical Society 2019 v.141 no.16 pp. 6473-6478
- carbenes, molecular weight, olefin, palladium, polymerization
- Carbene polymerization provides polyolefins that cannot be readily prepared from olefin monomers; however, controlled and living carbene polymerization has been a long-standing challenge. Here we report a new class of initiators, (π-allyl)palladium carboxylate dimers, which polymerize ethyl diazoacetate, a carbene precursor in a controlled and quasi-living manner, with nearly quantitative yields, degrees of polymerization >100, molecular weight dispersities 1.2–1.4, and well-defined, diversifiable chain ends. This method also provides block copolycarbenes that undergo microphase segregation. Experimental and theoretical mechanistic analysis supports a new dinuclear mechanism for this process.