Living polymerization of higher 2-alkene with α-diimine nickel catalysts: Synthesis and characterization of high molecular weight poly(2-alkene)s

A continuing legend: the Brookhart-type α-diimine nickel and palladium catalysts

“…In the process of exploring various Brookhart catalysts, various olefinic monomers have been polymerized and copolymerized. 27,31,[125][126][127] The applicable monomers have also been rapidly growing to include linear 128,129 and branched 130,131 α-olefins, cycloalkyl substituted α-olefins, 132-136 cycloolefins, 137 dienes, 138 trienes, 139,140 internal olefins, [141][142][143][144] norbonene type monomers, [101][102][103][104] and different polar comonomers. 3,27,28 It should be noted that the continuous interest in Brookhart-type catalysts largely originates from their capabilities in copolymerizations of olefins with polar functionalized comonomers.…”

A mechanistic study on the synthesis of branched functional polyethylene through reactive co‐polymer approach

“…However, various methyl resonances arise from 1,2‐insertion of 1‐hexene monomer followed by divers enchainment modes. Simply put, ethyl, propyl and other branches are created by the insertion of monomer into the metal–carbon bond and complete or partial migration of the metal center along the growing polymer chain via continuous β‐hydride elimination and reinsertion steps . The methylene and methine resonances of the polymer chains are specified by 1.5 and 1.6–1.7 ppm peaks, respectively.…”

Branching Regulation in Olefin Polymerization via Lewis Acid Triggered Isomerization of Monomers

“…Chain‐walking of internal alkenes is of interest because it allows for highly branched polymers. However, polymerization of these monomers is more challenging than 1‐alkenes, which has been suggested to be due to steric and electronic barriers to insertion in the Cossee–Arlman mechanism . Early work by Gottfried and Brookhart showed that palladium catalysts polymerized trans ‐2‐hexene at a very slow rate, reporting only 0.8 % yield of polymer in a typical reaction time frame (Scheme ) .…”

“…Nickel catalysis has been shown to be more successful at polymerizing internal alkenes due to their higher activity, although initial work from Brookhart indicated a strong preference for trans isomer; no polymerization of cis ‐2‐butene was reported . In 2017 Shiono and co‐workers reported successful homopolymerization of a range of 2‐alkenes from a nickel diimine catalyst . Nickel catalysts have shown further potential in the polymerization of internal olefins, although block copolymers with 1‐alkenes have never been reported.…”