Inhibitory Role of Carbon Monoxide in Palladium(II)-Catalyzed Nonalternating Ethene/Carbon Monoxide Copolymerizations and the Synthesis of Polyethene-<i>block</i>-poly(ethene-<i>alt</i>-carbon monoxide)

We report the first well-defined palladium-based system for the living homopolymerization of ethene, as well as the living copolymerization of ethene with carbon monoxide. We demonstrate this by the synthesis of polyethene-block-poly(ethene-alt-carbon monoxide). In addition, it has been possible to monitor chain growth by sequential insertions of carbon monoxide and ethene into palladium−carbon bonds. The mechanistic studies have also allowed us to pinpoint the hitherto not well-understood reason for the general failure to obtain alkene/carbon monoxide copolymers with low carbon monoxide content.本研究首次报道了结构明确的钯基催化体系，可实现乙烯的活性均聚以及乙烯与一氧化碳的活性共聚。我们通过合成聚乙烯嵌段聚(乙烯-alt-一氧化碳)（polyethene-block-poly(ethene-alt-carbon monoxide)）验证了该体系的活性聚合特性。此外，我们可通过一氧化碳与乙烯在钯-碳键中的依次插入反应，对链增长过程进行实时监测。同时，机理研究还帮助我们明确阐明了迄今尚未明晰的核心原因：为何通常难以获得一氧化碳含量较低的烯烃/一氧化碳共聚物。