Kulyabin Pavel S, Uborsky Dmitry V, Voskoboynikov Alexander Z, Canich Jo Ann M, Hagadorn John R
Department of Chemistry, M. V. Lomonosov Moscow State University, Leninskie Gory, 1/3, Moscow 119991, Russian Federation.
Baytown Technology and Engineering Complex, ExxonMobil Chemical Company, Baytown, TX 77520, USA.
Dalton Trans. 2020 May 26;49(20):6693-6702. doi: 10.1039/d0dt01031f.
The synthesis and characterisation of six novel Cs-symmetric pyridylamido hafnium complexes with a silylene bridge of the type [ArPy(R2Si)NAr']HfAlk2 are reported. Four complexes have been structurally characterised using single crystal X-ray diffraction. Appreciable differences between the solid state structures of these complexes and the pyridylamido hafnium complexes with a CRR' bridge were noted. Reactions with B(C6F5)3, [Ph3C][B(C6F5)4] and [HMe2NPh][B(C6F5)4] yielded active catalysts for the homopolymerisations of propene and 1-hexene and ethene/1-octene copolymerization. In spite of the Cs-symmetry of the precatalysts, isotactically enriched polypropylene and poly(1-hexene) were obtained. The fact that the mechanism of the catalyst activation includes the insertion of alkene into the Hf-CAr bond was demonstrated. It was found that the structures of Ar and the R2Si bridge influence the activity, molecular weight capability and 1-octene affinity of the catalysts.
报道了六种新型具有[ArPy(R₂Si)NAr']HfAlk₂类型硅烯桥的Cs对称吡啶酰胺基铪配合物的合成与表征。使用单晶X射线衍射对四种配合物进行了结构表征。注意到这些配合物的固态结构与具有CRR'桥的吡啶酰胺基铪配合物之间存在明显差异。与B(C₆F₅)₃、[Ph₃C][B(C₆F₅)₄]和[HMe₂NPh][B(C₆F₅)₄]反应生成了用于丙烯和1-己烯均聚以及乙烯/1-辛烯共聚的活性催化剂。尽管预催化剂具有Cs对称性，但仍获得了等规富集的聚丙烯和聚(1-己烯)。证明了催化剂活化机制包括烯烃插入Hf-CAr键。发现Ar和R₂Si桥的结构影响催化剂的活性、分子量能力和对1-辛烯的亲和力。
