Exploration of Homogeneous Ethylene Dimerization Mediated by Tungsten Mono(imido) Complexes

Abstract

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Selective dimerisation of 1-hexene mediated by aluminium alkyl chloride-activated tungsten imido complexes

“…The tungsten bis(imido) 1-3 and mono(imido) complexes 4-5 (Scheme 1) were synthesised according to previously published procedures from our group and others. 42,43 Subsequently, complexes 1-5 were tested as pro-catalysts for the dimerisation of 1hexene after activation with EtAlCl 2 (15 equivalents) at 60 C. These test conditions are the same as those previously optimised for the dimerisation of 1-pentene using the in situ WCl 6 /ArNH 2 /Et 3 N system reported by Hanton et al 40 Our previous work has demonstrated that the nature of the imido substituent in these types of ethylene dimerisation pro-catalysts has a significant impact on the performance of the resulting catalysts.…”

“…Therefore, initial tests were undertaken to probe if this is also the case using 1hexene as substrate. [42][43][44]…”

“…These systems are the most active, productive and selective tungsten-based catalysts for the dimerisation of ethylene to date, with performance paralleling that of Axens' commercial Ti-based AlphaButol process. 1,2,[42][43][44] Given the high level of ethylene dimerisation activity established for these types of tungsten imido pro-catalysts it was of interest to explore their potential for the dimerisation of heavier olefins. In this work we now demonstrate that both tungsten mono-and bis-(imido) complexes in combination with EtAlCl 2 are also commercially competitive pro-catalysts for the dimerisation of 1hexene with good productivities and selectivities towards the target dimer fraction.…”

Alkene oligomerization via metallacycles: Recent advances and mechanistic insights

“…In the case of mono-imido derivatives, the authors isolated a polymetallic W V complex after activation of (dippN)W VI Cl 4 (THF) with MeAlCl 2 (Scheme 33). [81] Moreover, by comparison of a series of W IV , W V and W IV complexes, they assessed that W V is the most probable catalytic active species. In another study, Grubbs and Miyashita used 1,1,4,4-tetradeuterated 1,1-dilithiobutane and showed an equilibrium between nickel bis-ethylene and nickelacyclopentane complexes (Scheme 38, bottom).…”

The influence of pore structure on reaction mechanism of propylene dimerization in zeolite: A theoretical viewpoint

“…Moreover, this reaction also involves the processes of proton migration, CC bond formation, and deprotonation, which are the key steps in olefin cyclization, aromatization, and other reactions, such as methanol to olefin . Thus, in‐depth study of alkene dimerization has been done by both experimental and theoretical methods . Alkene dimerization generally proceeds with the help of catalysts.…”