Motivated by the need for a new generation of α-diimine Ni(II) and Pd(II) catalysts for tuning the catalytic activity, polymer molecular weight, comonomer incorporation, and branching density in ethylene polymerization and copolymerization with polar monomers, a family of α-diimine Ni(II) and Pd(II) catalysts Ipty-Ni1–4 and Ipty-Pd1–4 derived from sterically demanding and rotationally restricted pentiptycenyl
出于对新一代α-二亚胺Ni(II)和Pd(II)催化剂的需求的动机,这些催化剂可用于调节乙烯聚合和与极性单体的共聚反应中的催化活性,聚合物分子量,共聚单体的掺入量和支化密度。 α-二亚胺Ni(II)和Pd(II)催化剂Ipty-Ni1-4和Ipty-Pd1-4衍生自空间受限和旋转受限的戊烯基N合成了芳基取代基,并通过NMR,IR,MALDI-TOF,元素分析和X射线衍射对其进行了全面表征。戊烯基取代的Ni(II)和Pd(II)催化剂在乙烯(共)聚合反应中进一步探究,以与先前报道的旋转自由的二苯甲基取代基进行比较。在镍催化的乙烯聚合(20–80°C)中,催化活性((0.64–3.74)×10 6 g mol –1 h –1),聚合物分子量((1.1–37.7)×10 4 g mol – 1),支化密度(6-55 / 1000C)和熔点(94-135°C)可以在很宽的范围内进行调整。在Pd催化
Efficient Suppression of Chain Transfer and Branching via
<i>C</i>
<sub>s</sub>
‐Type Shielding in a Neutral Nickel(II) Catalyst
suppresses chain transfer and branch formation to such an extent that ultrahigh molecular weight polyethylenes (5×106 g mol−1) are accessible, with a strictly linear microstructure (<0.1 branches/1000C). Key features of this highly active (4.3×105 turnovers h−1) catalyst are an exceptionally facilepreparation, thermal robustness (up to 90 °C polymerization temperature), ability for living polymerization
二苯并环庚基可有效屏蔽中性 Ni II活性位点的两个顶端位置,这两个基团均通过C s型排列中的相同供体N芳基连接。关键的苯胺结构单元可以通过市售的二苯并环庚醇一步获得。这种屏蔽方法抑制链转移和支链形成,使得可以在严格线性微观结构(<0 id=30>5 转换 h -1 )催化剂下获得超高分子量聚乙烯(5×10 6 g mol -1 )。其制备方法极其简便,具有耐热性(聚合温度高达 90 °C)、活性聚合能力以及与作为极性反应介质的 THF 的兼容性。
Alternating ring-opening metathesis polymerization by Grubbs-type catalysts with <i>N</i>-pentiptycenyl, <i>N</i>-alkyl-NHC ligands
A Grubbs–Hoveyda type catalyst with a N-pentiptycenyl, N-cyclohexyl-NHC ligand provides poly(nbe-alt-coe) with an excellent degree of alternation while lacking significant activity in the homopolymerization of cyclooctene.
用甲格拉布加入Hoveyda型催化剂Ñ -pentiptycenyl,Ñ环己基- NHC配体提供了聚(nbe- ALT -COE)与交替的优异程度,而在环辛烯的均聚缺乏显著活性。
Systematic studies on dibenzhydryl and pentiptycenyl substituted pyridine-imine nickel(<scp>ii</scp>) mediated ethylene polymerization
Pyridine-imine nickel catalysts bearing different N-aryl/imine substituents were systematically studied for ethylene polymerization to produce low-molecular-weight and branched polyethylenes.