Rare Earth Metal Alkyl Complexes with Methyl-Substituted Triazacyclononane-amide Ligands: Ligand Variation and Ethylene Polymerization Catalysis
作者:Sergio Bambirra、Daan van Leusen、Cornelis G. J. Tazelaar、Auke Meetsma、Bart Hessen
DOI:10.1021/om060870a
日期:2007.2.1
Comparative testing in catalytic ethylene polymerization showed that the catalyst activity is most strongly influenced by the metal ionic radius, but that variations in the ligand backbone and substitution pattern do influence other factors, such as polymer molecular weight and catalyst stability. Catalysts with the intermediately sized rare earth metal yttrium generally showed the highest activity, but
制备了一系列具有通式[Me 2 TACN-(B)-NR] M(CH 2 SiMe 3)2(TACN = 1,4,7-三氮杂环壬烷,B =(CH 2)的稀土金属二烷基配合物2,SiMe 2 ; R = t Bu,sec Bu,n卜; M = Sc,Y,Nd,La)。对于M = Sc,也可以使用混合的单烷基一氯配合物。这些配合物的选定实例在结构上得到了表征,并显示出畸变的八面体环境中的金属。使用路易斯或布朗斯台德酸活化剂,可以将二烷基化合物转化为相应的单烷基阳离子,并通过NMR光谱对其进行表征。催化乙烯聚合的比较测试表明,催化剂活性受金属离子半径的影响最大,但是配体主链和取代方式的变化确实会影响其他因素,例如聚合物分子量和催化剂稳定性。具有中等大小的稀土金属钇的催化剂通常显示出最高的活性,但是其中一些催化剂会产生分子量分布较宽的聚乙烯,表明存在多点行为。从理论上讲,这可能是由于分子间配体加扰过