A series of cobalt(II) phenoxy‐imine complexes (Co^II(FI)₂) have been synthesized to mediate the radical polymerization of vinyl acetate (VAc) and methyl acrylate (MA) to evaluate the influence of chelating atoms and configuration to the control of polymerization. The VAc polymerizations showed the properties of controlled/living radical polymerization (C/LRP) with complexes 1a and 3a, but the catalytic chain transfer (CCT) behaviors with complexes 2a, 1b, 2b, and 3b. The control of VAc polymerization mediated by complex 1a could be improved by decreasing the reaction temperature to approach the molecular weights that not only linearly increased with conversions but also matched the theoretical values and relatively narrow molecular weight distributions. The catalytic chain transfer polymerizations (CCTP) mediated by complexes 2a, 1b, 2b, and 3b were characterized by Mayo plots and the polymer chain end double bonds were observed by ¹H NMR spectra. The tendency toward C/LRP or CCTP in VAc polymerization mediated by Co^II(FI)₂ could be determined by the ligand structure. Cobalt complex coordinated by the ligand with more steric hindered and less electron‐donating substituents favored the controlled/living radical polymerization. In contrast, the efficiency of CCT process could be enhanced by less steric hindered, more electron‐donating ligands. The controlled/living radical polymerization of MA, however, could not be achieved by the mediation of these cobalt(II) phenoxy‐imine complexes. Associated with the results of polymerization mediated by other cobalt complexes, this study implied that the configuration and spin state of cobalt complexes were more critical than the chelating atoms to the control behavior of radical polymerization. © 2019 Wiley Periodicals, Inc. J. Polym. Sci. 2020, 58, 101–113

中文翻译：

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乙酸乙烯酯自由基聚合中的钴（II）苯氧基亚胺配合物：催化链转移与受控/活性自由基聚合的相互作用

合成了一系列钴（II）苯氧基亚胺配合物（Co ^II（FI）₂），以介导乙酸乙烯酯（VAc）和丙烯酸甲酯（MA）的自由基聚合作用，以评估螯合原子和构型对该化合物的影响。控制聚合。VAc聚合反应显示出配合物1a和3a具有受控/活性自由基聚合（C / LRP）的特性，但配合物2a，1b，2b和3b具有催化链转移（CCT）行为。配合物1a介导的VAc聚合反应的控制可以通过降低反应温度以达到不仅随转化率线性增加的分子量而且与理论值和相对窄的分子量分布相匹配的分子量来改进。配合物2a，1b，2b和3b介导的催化链转移聚合反应（CCTP）通过Mayo图进行表征，并通过¹ H NMR光谱观察到聚合物链端双键。Co ^II（FI）₂介导的VAc聚合中C / LRP或CCTP的趋势可以由配体结构决定。配位体配位的钴配合物具有更多的空间位阻和更少的供电子取代基，有利于受控/活性自由基聚合。相比之下，较少的位阻，更多的供电子配体可以提高CCT的效率。但是，通过这些钴（II）苯氧基亚胺配合物的介导不能实现MA的受控/活性自由基聚合。与其他钴配合物介导的聚合结果相关，这项研究表明，钴配合物的构型和自旋态比螯合原子对自由基聚合的控制行为更为关键。©2019 Wiley Periodicals，Inc.J.Polym。科学 2020，58，101-113