Manjarrez Yvonne, Cheng-Tan Mary Dana Czarinah L, Fieser Megan E
Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States.
Department of Chemistry and Wrigley Institute for Environmental Studies, University of Southern California, Los Angeles, California 90089, United States.
Inorg Chem. 2022 May 9;61(18):7088-7094. doi: 10.1021/acs.inorgchem.2c00529. Epub 2022 Apr 28.
Monometallic yttrium β-diketiminate complexes are active and controlled catalysts for perfectly alternating ring-opening copolymerization of 1-butene oxide and phthalic anhydride under mild conditions. β-Diketiminate ligands with pendant neutral donors were targeted to identify both the impact of donor strength and number of donors on rates of polymerization and the presence of undesirable side reactions. Initiating groups were also varied between alkyls, chlorides, and alkoxides. In the presence of a cocatalyst, the catalysts studied were active for polymerization with minimal side reactions, whereas lack of cocatalysts led to competing homopolymerization of epoxides. While a greater donor strength and a larger number of donors both increase the rate of polymerization, donor strength generally had a bigger impact when a cocatalyst was used. Additionally, alkoxide and chloride initiators proved to be the fastest, with alkyls being more sluggish. These subtle ligand changes significantly impacting polymerization activity lend promise to the facile tunability of rare earth metal complexes to be highly active for the target copolymerization, which renders further research in this area attractive and timely.
单金属钇β-二酮亚胺配合物是在温和条件下实现1-丁烯氧化物与邻苯二甲酸酐完美交替开环共聚的活性可控催化剂。带有中性侧基供体的β-二酮亚胺配体旨在确定供体强度和供体数量对聚合速率的影响以及是否存在不良副反应。引发基团在烷基、氯和醇盐之间也有所不同。在助催化剂存在下，所研究的催化剂对聚合反应具有活性，且副反应最少，而缺乏助催化剂则会导致环氧化物发生竞争性均聚。虽然更强的供体强度和更多的供体数量都会提高聚合速率，但在使用助催化剂时，供体强度通常影响更大。此外，醇盐和氯化物引发剂被证明是最快的，而烷基引发剂则较为迟缓。这些对聚合活性有显著影响的细微配体变化表明，稀土金属配合物具有易于调节以对目标共聚反应具有高活性的潜力，这使得该领域的进一步研究具有吸引力且恰逢其时。
