Triazacyclohexane chromium triflate complexes as precursors for the catalytic selective olefin trimerisation and its investigation by mass spectrometry
作者:Randolf D. Köhn、Alexander G.N. Coxon、Samaphon Chunawat、Callum Heron、Shahram Mihan、Catherine L. Lyall、Shaun B. Reeksting、Gabriele Kociok-Köhn
DOI:10.1016/j.poly.2020.114572
日期:2020.7
synthesised from R3TACCrCl3 in neat TfOH or by addition of R3TAC to Cr(OTf)3 or better Cr(OTf)3(THF)3, the synthesis and structure of which is presented here. The use of this highly defined system allowed the identification of 2-methyl-1-hexene as a side product of activation with AlMe3, in agreement with the proposed metallacyclic mechanism. Isomer distribution of the trimer product is similar to R3TACCrCl3/MAO
摘要提出了一套新颖的线性α-烯烃三聚前体催化剂。R3TACCr(OTf)3(R3TAC = 1,3,5-三烷基-1,3,5-三氮杂环己烷)配合物在活化后,会以少于10当量的三烷基铝产生一个活性系统。在许多情况下都观察到异构化,这被认为是通过π-烯丙基络合物机理发生的,尽管通过优化反应条件可以将其最小化。可以在纯TfOH中由R3TACCrCl3合成预催化剂,也可以将R3TAC添加到Cr(OTf)3或更佳的Cr(OTf)3(THF)3中,在此介绍其合成和结构。与提出的金属环机理一致,使用这种高度定义的系统可以鉴定出2-甲基-1-己烯作为AlMe3活化的副产物。三聚体产物的异构体分布类似于R3TACCrCl3 / MAO活化系统,并且主要取决于配体取代基R。在反应的不同阶段分析了活化催化剂的邻二氟苯溶液的ESI质谱。观察到一系列信号,这些信号与金属环机理预测的阳离子铬物种的预期信号匹配。特别是,观察到[R3TACCrMe2]