Unprecedented Isospecific 3,4-Polymerization of Isoprene by Cationic Rare Earth Metal Alkyl Species Resulting from a Binuclear Precursor
摘要:
The isospecific 3,4-polymerization of isoprene has been achieved for the first time by use of a combination of a binuclear rare earth metal dialkyl complex, such as [Me2Si(C5Me4)(mu-PCy)YCH2SiMe3]2 (Cy = cyclohexyl), and an equimolar amount of [Ph3C][B(C6F5)4] as a catalyst system. A DFT calculation suggested that a binuclear monocationic monoalkyl species, such as [Me2Si(C5Me4)(mu-PCy)Y(mu-CH2SiMe3)Y(mu-PCy)(C5Me4)SiMe2]+, in which the alkyl group bridges the two metal centers, could be the true catalyst species.
Me 2 Si(C 5 Me 4)(PR')LnR(Ln = Y,Yb,Lu; R'= Ph,Cy,C 6 H合成了2 t Bu 3 -2,4,6; R = CH 2 SiMe 3,H)并对其结构进行了表征,并研究了它们在乙烯聚合和烯烃氢化硅烷化中的活性。这些配合物代表了带有环戊二烯基-磷基配体的稀土烷基和氢化物配合物的第一个例子,它们在结构和化学上都与类似的环戊二烯基-酰胺基和茂金属配合物形成鲜明对比。