Olefin Polymerization by Vanadium Complex Catalysts

Reactions of (Arylimido)vanadium(V)–Trialkyl Complexes with Phenols: Effects of Arylimido Ligands and Phenols for Formation of the Vanadium Phenoxides

“…1−4 The metal alkyl species play a key role in olefin polymerization, the core technology for the production of polyolefins in the chemical industry. 5−18 Since classical Ziegler type vanadium catalyst systems display unique characteristics (highly reactive toward olefins exemplified as production of ultrahigh molecular weight polyethylene with narrow molecular weight distributions), 19−21 the reaction chemistry of vanadium–alkyl complexes 22−38 should be considered as an important subject in the field of catalysis 12,38−41 and organometallic chemistry. 42−44…”

“…Transition-metal alkyl complexes are among the most important reagents or intermediates in organic reactions, − and the study of their reaction chemistry has been recognized as an important subject for better understanding especially in catalysis cycles, reaction pathways, and design of efficient catalysts. − The metal alkyl species play a key role in olefin polymerization, the core technology for the production of polyolefins in the chemical industry. − Since classical Ziegler type vanadium catalyst systems display unique characteristics (highly reactive toward olefins exemplified as production of ultrahigh molecular weight polyethylene with narrow molecular weight distributions), − the reaction chemistry of vanadium–alkyl complexes − should be considered as an important subject in the field of catalysis ,− and organometallic chemistry. − …”

XAS Analysis of Reactions of (Arylimido)vanadium(V) Dichloride Complexes Containing Anionic NHC That Contains a Weakly Coordinating B(C6F5)3 Moiety (WCA-NHC) or Phenoxide Ligands with Al Alkyls: A Potential Ethylene Polymerization Catalyst with WCA-NHC Ligands

“…42 The observed facts also correspond to the facts that the activity in ethylene polymerization by 6a decreased upon addition of ETA, 45 whereas the activity by B increased upon addition of ETA, 42 as seen in most vanadium complex and classical Ziegler-type vanadium catalyst systems (as described in the Introduction section). 8,16,17,23−28 These also suggest that different catalytically active vanadium(III) species would play roles in these catalyses.…”

“…43 A similar effect of retardations (by increasing the temperature from 0 to 25 °C) was also observed in the (arylimido)vanadium(V) complexes containing iminoimidazolide or iminoimidazolidide ligands. 46 As described in the Introduction section, Al i Bu 3 has been considered as an ineffective Al cocatalyst in the metal-catalyzed olefin polymerization, 1−17,24−26,28,39−46 but the use of Al i Bu 3 should be favored in terms of practical viewpoints, especially for the establishment of a halogen-free process (without using halogenated Al) and for using an inexpensive Al cocatalyst compared to MAO.…”

“…Moreover, the complexes containing anionic N -heterocyclic carbenes (NHCs) that contain a weakly coordinating borate moiety (WCA-NHC, F ) exhibited high catalytic activities for ethylene polymerization in the presence of Al i Bu 3 , 47 which has been considered as an ineffective Al cocatalyst in the metal-catalyzed olefin polymerization. 1−17,24−26,28,39−46…”