Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA.
Angew Chem Int Ed Engl. 2017 Dec 11;56(50):15964-15968. doi: 10.1002/anie.201708797. Epub 2017 Nov 15.
Direct coordinative copolymerization of ethylene with functionalized co-monomers is a long-sought-after approach to introducing polyolefin functionality. However, functional-group Lewis basicity typically depresses catalytic activity and co-monomer incorporation. Finding alternatives to intensively studied group 4 d and late-transition-metal catalysts is crucial to addressing this long-standing challenge. Shown herein is that mono- and binuclear organoscandium complexes with a borate cocatalyst are active for ethylene + amino olefin [AO; H C=CH(CH ) NR ] copolymerizations in the absence of a Lewis-acidic masking reagent. Both activity (up to 4.2×10 kg mol ⋅h atm ) and AO incorporation (up to 12 % at 0.2 m [AO]) are appreciable. Linker-length-dependent (n) AO incorporation and mechanistic probes support an unusual functional-group-assisted enchainment mechanism. Furthermore, the binuclear catalysts exhibit enhanced AO tolerance and enhanced long chain AO incorporation.
直接配位共聚是一种将功能化共聚单体引入聚烯烃的理想方法。然而，功能基团的路易斯碱性通常会降低催化活性和共聚单体的掺入。寻找替代广泛研究的第 4 族 d 过渡金属和晚期过渡金属催化剂对于解决这一长期存在的挑战至关重要。本文表明，具有硼酸助催化剂的单核和双核有机钪配合物在没有路易斯酸性掩蔽试剂的情况下可用于乙烯+氨基烯烃（AO；H C=CH(CH ) NR ）共聚。活性（高达 4.2×10 kg·mol ⋅h ⋅atm）和 AO 掺入量（0.2 m [AO]时高达 12%）都很可观。链接器长度依赖性（n）AO 掺入和机理探针支持不寻常的功能基团辅助链增长机制。此外，双核催化剂表现出增强的 AO 耐受性和增强的长链 AO 掺入。
