It is an efficient way to introduce ortho-aryl dibenzosuberyl substituents into late-transition metal catalysts for retarding chain transfer in olefin polymerization. Here, we further found that dibenzosuberyl substituents could also suppress chain transfer and thus increase the molecular weight in ethylene polymerization with bis(imino)pyridyl Fe(II) catalysts. A series of bis(imino)pyridyl ligands with unilateral diarylmethyl or dibenzosuberyl moiety on the ortho-positions of N-aryl rings and their corresponding Fe(II) catalysts were synthesized and characterized. All these bis(imino)pyridyl Fe(II) catalysts exhibited high polymerization activity and could generate high weight-average molecular weight polyethylenes with very broad molecular weight distributions in most cases. Among them, the dibenzosuberyl Fe(II) catalysts could generate ultra-high weight-average molecular weight (M_w = 2038–2137 kg/mol) polyethylenes at low temperatures, significantly higher than the diarylmethyl catalysts. The obtained polyethylenes are all highly linear with almost no branching distribution.

在烯烃聚合中将邻芳基二苯并环戊基取代基引入后过渡金属催化剂是一种有效的延缓链转移的方法。在这里，我们进一步发现二苯并辛基取代基也可以抑制链转移，从而增加使用双（亚氨基）吡啶基 Fe（II）催化剂进行乙烯聚合的分子量。一系列双（亚氨基）吡啶基配体，在N的邻位具有单侧二芳基甲基或二苯并环戊基部分合成并表征了芳基环及其相应的 Fe(II) 催化剂。所有这些双（亚氨基）吡啶基 Fe（II）催化剂都表现出高聚合活性，并且在大多数情况下可以生成具有非常宽分子量分布的高重均分子量聚乙烯。其中，二苯并环庚基Fe(II)催化剂可以在低温下生成超高重均分子量（M _w  = 2038-2137 kg / mol）聚乙烯，显着高于二芳基甲基催化剂。得到的聚乙烯都是高度线性的，几乎没有支化分布。