were employed. Such dinuclear penta-coordinated yttrium complexes were evaluated as initiators in the polymerization of 2-vinylpyridine (2-VP). High activity and excellent isotacticity (mm > 99%) were observed. DSC analysis of poly(2-VP) showed a Tm = 221 °C, which is the highest value reported to date. Attempts to improve the low initiation efficiency of the present system were made by co-use with several
从Y(CH 2 SiMe 3)3(THF)2和在3,3'-位带有大取代基的易于获得的双
酚开始,首次合成了双核有机
钇双
酚复合物。XRD分析表明,即使使用外消旋双
酚,这些复合物仍以同手性二聚体形式形成。评价这种双核五配位
钇配合物作为
2-乙烯基吡啶(2-VP)聚合中的
引发剂。观察到高活性和优异的全同立构规整度(mm> 99%)。聚(2-VP)的
DSC分析显示T m= 221°C,这是迄今为止报告的最高值。通过与几种有机主族
金属试剂共同使用来尝试提高本系统的低引发效率。具体地说,通过添加Et 3 Al(Al / Y = 10),可以在高M n区内实现良好的分子量控制。