期刊
ACS CATALYSIS
卷 5, 期 1, 页码 456-464出版社
AMER CHEMICAL SOC
DOI: 10.1021/cs5016029
关键词
palladium; diimine; ethylene; living polymerization; methyl aaylate
资金
- NSF [CHE-1010170]
- Welch Foundation [E-1571]
- Spanish Ministry of Education [AP20080256]
- Direct For Mathematical & Physical Scien
- Division Of Chemistry [1010170] Funding Source: National Science Foundation
Cationic Pd(II) catalysts incorporating bulky 8-p-tolylnaphthyl substituted diimine ligands have been synthesized and investigated for ethylene polymerization and ethylene/methyl acrylate copolymerization. Homopolymerization of ethylene at room temperature resulted in branched polyethylene with narrow M-w/M-n values (ca. 1.1), indicative of a living polymerization. A mechanistic study revealed that the catalyst resting state was an alkyl olefin complex and that the turnover-limiting step was migratory insertion, thus the turnover frequency is independent of ethylene concentration. Copolymerization of ethylene and methyl acrylate (MA) was also achieved. MA incorporation was found to increase linearly with MA concentration, and copolymers with up to 14 mol % MA were prepared. Mechanistic studies revealed that acrylate insertion into a PdCH3 bond occurs at -70 degrees C to yield a four-membered chelate, which isomerizes first to a five-membered chelate and then to a six-membered chelate. Barriers to migratory insertion of both the (diimine)PdCH3(C2H4)(+) (19.2 kcal/mol) and (diimine)PdCH3(eta(2)-C2H3CO2Me)(+) (15.2 kcal/mol) were measured by low-temperature NMR kinetics.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据