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1. Catalyzed Radical Termination (CRT) in the Metal-Mediated Polymerization of Acrylates: Experimental and Computational Studies

   https://doi.org/10.1021/bk-2018-1284.ch006  

   Ribelli, Thomas G.; Rahaman, S. M.; Matyjaszewski, Krzysztof; Poli, Rinaldo (August 2018, ACS symposium series)

   Metal complexes stabilized by appropriate ligands, particularly CuI/L systems, have proven powerful for the controlled polymerization of acrylates and other monomers by atom transfer radical polymerization (ATRP). The polymerization of acrylates by CuI/L systems, however, is haunted by interference of catalyzed radical termination (CRT), which reduces the chain-end fidelity. Other monomers do not appear to be affected by this phenomenon to any significant extent. The phenomenon appears to involve the formation of an organometallic intermediate by reversible radical trapping, as in organometallic mediated radical polymerization (OMRP). We summarize here the current knowledge and the efforts made to elucidate the CRT pathway and products. 

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2. Catalytic effect of DMSO in metal‐catalyzed radical polymerization mediated by disproportionation facilitates living and immortal radical polymerizations

   https://doi.org/10.1002/pol.20220632  

   Maurya, Devendra S.; Adamson, Jasper; Bensabeh, Nabil; Lligadas, Gerard; Percec, Virgil (February 2023, Journal of Polymer Science)

   Abstract DMSO, an interesting solvent for copper‐catalyzed living radical polymerization (LRP) mediated by disproportionation, does not exhibit the greatest disproportionation of Cu(I)X into Cu(0) and Cu(II)X₂. Under suitable conditions, DMSO provides 100% conversion and absence of termination, facilitating the development of complex‐architecture methodologies by living and immortal polymerizations. The mechanism yielding this level of precision is being investigated. Here we compare Cu(0)‐wire‐catalyzed LRP of methyl acrylate mediated by disproportionating ligands tris(2‐dimethylaminoethyl)amine, Me₆‐TREN, tris(2‐aminoethyl)amine, TREN, and Me₆‐TREN/TREN = 1/1 in presence of eight disproportionating solvents, some more efficient than DMSO in disproportionation. Unexpectedly, we observed that all solvents increased the rate of polymerization when monomer concentration decreased. This reversed trend from that of conventional LRPs demonstrates catalytic effect for disproportionating solvents. Above a certain concentration, the classic concentration‐rate dependence was observed. The external order of reaction of the apparent rate constant of propagation,k_p^appon solvent concentration demonstrated the highest order of reaction for the least disproportionating DMSO. Of all solvents investigated, DMSO has the highest ability to stabilize Cu(0) nanoparticles and therefore, yields the highest activity of Cu(0) nanoparticles rather than their greatest concentration. The implications of the catalytic effect of solvent in this and other reactions were discussed. 

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3. Impact of Organometallic Intermediates on Copper-Catalyzed Atom Transfer Radical Polymerization

   https://doi.org/10.1021/acs.macromol.9b00870  

   Fantin, Marco; Lorandi, Francesca; Ribelli, Thomas G.; Szczepaniak, Grzegorz; Enciso, Alan E.; Fliedel, Christophe; Thevenin, Lucas; Isse, Abdirisak A.; Poli, Rinaldo; Matyjaszewski, Krzysztof (May 2019, Macromolecules)
4. Catalyzed Radical Termination in the Presence of Tellanyl Radicals

   https://doi.org/10.1002/chem.201703064  

   Ribelli, Thomas G.; Rahaman, S. M.; Matyjaszewski, Krzysztof; Poli, Rinaldo (October 2017, Chemistry - A European Journal)
5. Transition metal-mediated reductive coupling of diazoesters

   https://doi.org/10.1039/C9CC03771C  

   Grass, Amanda; Stoian, Sebastian A.; Lord, Richard L.; Groysman, Stanislav (July 2019, Chemical Communications)

   The first transition metal mediated reductive coupling of diazoesters through the terminal nitrogens is reported. The resulting tetrazene-bridged bis(diazenylacetate) serves as a novel dinucleating ligand to iron(III). DFT calculations suggest that the reductive coupling takes place via a κ 2 intermediate, which induces significant radical character on the terminal nitrogen. 

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