Development of new rare earth metal polymerization catalysts

C_5 Me_5 R配位的钐茂（II）配合物，（C_5Me_4R）_2Sm（THF）_x（1，R=Me ; 2，R=Et ; 3，R=i-Pr，4，R=n-Bu，5 ; R=TMS ; x=1或2），与改性甲基铝氧烷（MMAO）组合在环己烷中考察了它们对丁二烯聚合的催化性能。配合物2-5与母体化合物1相比，在催化活性和聚合物规整性方面均有明显的提高：活性3>>5 × 4>2>1 ;在50℃时，1，4-顺式选择性为3 ∶ 5>4 ∶ 2> 1.2。阳离子稀土茂金属配合物[（C_5Me_5）_2Ln][B（C_6F_5）_4]催化合成3-丁二烯（Ln=Pr，Nd，Gd）与^iBu_3Al的组合能有效地诱导丁二烯的1，4-顺式聚合。Gd配合物/^iBu_3Al体系的活性很高，即使在低温下也表现出良好的催化活性。在-78℃下聚合， ...更多信息 具有近乎完美的1，4-顺式微结构的聚丁二烯（>99.9%），具有尖锐的分子量分布（M_w/M_n=1.45），产率合理。3.含硅烯环戊二烯基膦配体的稀土烷基配合物的合成、结构表征及新型催化作用（CH_2SiMe_3）_3（THF_2）（Ln=Y，Yb，Lu）与1当量的Me_2Si（C_5Me_4H）（PHR）（R=Ph，Cy）反应，得到了第一个硅亚烷基环戊二烯基膦稀土烷基配合物[Me_2Si（C_5Me_4）（μ-PR）Ln（CH_2SiMe_3）]_2。与类似的环戊二烯基-酰胺基和茂金属配合物相比，这些配合物通过磷化物桥接采用二聚体结构，而烷基配体被置于末端位置。由于其独特的空间位阻和电子配体环境，大多数配合物对乙烯聚合和烯烃硅氢加成反应表现出比传统的茂金属或酰胺类似物高得多的活性。此外，当用[Ph_3C][B（C_6F_5）_4]处理时，这些配合物对异戊二烯的3，4-聚合表现出极高的区域和立体选择性，选择性地生成全同立构（> 99%mmmm）的3，4-聚异戊二烯。这是异戊二烯的立体定向3，4-聚合的第一个实例。少

1.1,4-Cis stereospecific polymerization of 1,3-butadiene by samarocene catalystsThe C_5Me_5R-ligated samarocene(II) complexes, (C_5Me_4R)_2Sm(THF)_x(1, R=Me ; 2, R=Et ; 3, R=i-Pr, 4, R=n-Bu, 5 ; R=TMS ; x=1 or 2), in combination with modified methylaluminoxane(MMAO) were examined in cyclohexane with respect to their catalytic performances for the polymerization of butadiene. Complexes 2-5 showed considerable promotion in both catalytic activity and regularity of the resulting polymer as compared to parent 1 : activity,3>>5〜4>2>1 ; 1,4-cis selectivity at 50℃,3〜5>4>2>1.2.1,4-Cis stereospecific polymerization of 1,3-butadiene by cationic rare earth metallocene catalystsCationic metallocene complexes[(C_5Me_5)_2Ln][B(C_6F_5)_4](Ln=Pr, Nd, Gd) in combination with ^iBu_3Al efficiently induce highly 1,4-cis specific polymerization of butadiene. The activity of the Gd complex/^iBu_3Al system is high enough to exhibit good catalytic activity even at low temperature. Polymerization at -78℃ gave … More polybutadiene with nearly perfect 1,4-cis microstructure (>99.9%) with sharp molecular weight distribution (M_w/M_n=1.45) and in reasonable yield.3.Synthesis, Structural Characterization, and Novel Catalysis of Rare Earth Alkyl Complexes Bearing Silylene-Linked Cyclopentadienyl-Phosphido LigandsThe reactions of Ln(CH_2SiMe_3)_3(THF_2)(Ln=Y, Yb, Lu) with 1 equiv of Me_2Si(C_5Me_4H)(PHR)(R=Ph, Cy) afforded the first silylene-linked cyclopentadienylphosphido rare earth alkyl complexes, [Me_2Si(C_5Me_4)(μ-PR)Ln(CH_2SiMe_3)]_2. In contrast with the analogous cyclopentadienyl-amido and metallocene complexes, these complexes adopt a dimeric structure through phosphide bridging, while the alkyl ligand is placed in a terminal position. Owing to their unique steric and electronic ligand environments, most of these complexes showed much higher activity for the polymerization of ethylene and hydrosilylation of olefins than that of the conventional metallocene or amido analogues. Moreover, when treated with [Ph_3C][B(C_6F_5)_4], these complexes showed extremely high regio- and stereoselectivity for the 3,4-polymerization of isoprene, which yielded the isotactic (>99% mmmm) 3,4-poly(isoprene) selectively. This is the first example of stereospecific 3,4-polymerization of isoprene. Less