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C–H-Bond Activation and Isoprene Polymerization Studies Applying Pentamethylcyclopentadienyl-Supported Rare-Earth-Metal Bis(Tetramethylaluminate) and Dimethyl Complexes

机译:C–H键活化和异戊二烯聚合反应研究应用五甲基环戊二烯基支持的稀土金属双(四甲基铝酸酯)和二甲基配合物

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摘要

As previously shown for lutetium and yttrium, 1,2,3,4,5-pentamethylcyclopentadienyl (C Me = Cp*)-bearing rare-earth metal dimethyl half-sandwich complexes [Cp*LnMe ] are now also accessible for holmium, dysprosium, and terbium via tetramethylaluminato cleavage of [Cp*Ln(AlMe ) ] with diethyl ether (Ho, Dy) and tert-butyl methyl ether (TBME) (Tb). C–H-bond activation and ligand redistribution reactions are observed in case of terbium and are dominant for the next larger-sized gadolinium, as evidenced by the formation of mixed methyl/methylidene clusters [(Cp*Ln) (CH )(Me) ] and metallocene dimers [Cp* Ln(AlMe )] (Ln = Tb, Gd). Applying TBME as a “cleaving” reagent can result in both TBME deprotonation and ether cleavage, as shown for the formation of the 24-membered macrocycle [(Cp*Gd) (Me)(CH O Bu) (AlMe )] or monolanthanum complex [Cp*La(AlMe ){Me Al(CH )O Bu}] and monoyttrium complex [Cp*Y(AlMe )(Me AlO Bu)], respectively. Complexes [Cp*Ln(AlMe ) ] (Ln = Ho, Dy, Tb, Gd) and [Cp*LnMe ] (Ln = Ho, Dy) are applied in isoprene and 1,3-butadiene polymerization, upon activation with borates [Ph C][B(C F ) ] and [PhNHMe ][B(C F ) ], as well as borane B(C F ) . The trans-directing effect of AlMe in the binary systems [Cp*Ln(AlMe ) ]/borate is revealed and further corroborated by the fabrication of high-cis-1,4 polybutadiene (97%) with “aluminum-free” [Cp*DyMe ] /[Ph C][B(C F ) ]. The formation of multimetallic active species is supported by the polymerization activity of pre-isolated cluster [(Cp*Ho) Me (CH )(thf) ].
机译:如先前对和钇的显示,现在也可以使用含1,2,3,4,5-五甲基环戊二烯基(C Me = Cp *)的稀土金属二甲基半三明治复合物[Cp * LnMe]和ter通过四甲基氧化铝用二乙基醚(Ho,Dy)和叔丁基甲基醚(TBME)(Tb)裂解[Cp * Ln(AlMe)]。在ter的情况下,会观察到C–H键的活化和配体的再分布反应,并在下一个更大的ado中起主导作用,这由混合的甲基/亚甲基簇[[Cp * Ln)(CH)(Me)的形成证明。 ]和茂金属二聚体[Cp * Ln(AlMe)](Ln = Tb,Gd)。将TBME用作“裂解”试剂可导致TBME去质子化和醚裂解,如24元大环[(Cp * Gd)(Me)(CH O Bu)(AlMe)]或单镧配合物的形成所示[Cp * La(AlMe){Me Al(CH)O Bu}]和单钇配合物[Cp * Y(AlMe)(Me AlO Bu)]。配合物[Cp * Ln(AlMe)](Ln = Ho,Dy,Tb,Gd)和[Cp * LnMe](Ln = Ho,Dy)经硼酸酯活化后用于异戊二烯和1,3-丁二烯聚合。 Ph C] [B(CF)]和[PhNHMe] [B(CF)]以及硼烷B(CF)。通过制备具有“无铝” [Cp]的高顺式1,4聚丁二烯(97%),揭示并进一步证实了AlMe在二元体系[Cp * Ln(AlMe)] /硼酸酯中的反方向作用。 * DyMe] / [Ph C] [B(CF)]。预分离簇[[Cp * Ho)Me(CH)(thf)]的聚合活性支持了多金属活性物质的形成。

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