2‐(1‐(2,4‐Bis((di(4‐fluorophenyl)methyl)‐6‐methylphenylimino)ethyl)‐6‐(1‐(arylimino)ethyl)pyridylmetal (iron or cobalt) Complexes: Synthesis, Characterization, and Ethylene Polymerization Behavior

Abstract

A series of 2‐(1‐(2,4‐bis((di(4‐fluorophenyl)methyl)‐6‐methylphenylimino)ethyl)‐6‐(1‐(aryl­imino)ethyl)pyridines is synthesized and used to form their corresponding iron(II) and cobalt(II) chloride complexes thereof. All the organic compounds are fully characterized by elemental analysis, and IR and 1H/13C NMR spectroscopy, whereas the corresponding iron and cobalt complexes are characterized by elemental analysis and IR spectroscopy, as well as single‐crystal crystallography for the Fe2, Co1, and Co2 complexes, revealing a distorted trigonal bipyramidal structure. Upon activation with either methylaluminoxane (MAO) or modified methylaluminoxane (MMAO), all the iron complexes exhibit high activities toward ethylene polymerization at 60 °C; meanwhile, all the cobalt analogs demonstrate slightly lower activities at the optimized temperatures of 60 °C (MAO as cocatalyst) or 70 °C (MMAO as cocatalyst). All the polyethylenes obtained from cobalt precatalysts possess narrow polydispersity and lower molecular weights than those from their iron analogs.

Carbocyclic-fused N,N,N-pincer ligands as ring-strain adjustable supports for iron and cobalt catalysts in ethylene oligo-/polymerization

“…Over the last five years, our group has also been interested in improving the catalytic activity and thermal stability of bis(arylimino)pyridine-iron and -cobalt complexes [43,46,51]. In particular we have found that the introduction of sterically demanding benzhydryl groups and their derivatives into the N,N,N-ligand frame of their iron and cobalt catalysts can be influential (14-30, Figure 14) [70][71][72][73][74][75][76][77][78][79][80][81] for ethylene polymerization (see Table 2).…”

“…Benzhydryl-substituted bis(arylimino)pyridine-iron and -cobalt complexes 14-31 [70][71][72][73][74][75][76][77][78][79][80][81]…”

“…) possessed narrower molecular weight distributions, indicative of a single-site active species[71,74,76,77,79,80].…”

The 60th Birthday of Prof. Minoru Terano

“…[4] Moreover, late-transition-metal complexes are promising for industrial processes producing novel advanced polyolefi n materials, [5] while computation simulation is promising for the design and prediction of effective catalysts, along with the production of advanced polyolefi ns. [6] Furthermore, new techniques have been developed for the measurement of microstructures of polyoelfi ns.…”

Ethylene polymerization with homogeneous and heterogeneous catalysts based on bis(4‐fluorophenyl)methyl‐substituted bis(imino)pyridyliron complexes

“…To this end, we screened various modified bis(imino)pyridine derivatives. High thermal stability of corresponding bis(imino)pyridyl iron complexes was achieved by using bis(imino)pyridines with dibenzhydryl‐ and bis(4‐fluorophenyl)methyl‐substituents . The above catalysts displayed high apparent activities (recalculated from PE yields within 15 or 30 min) at temperatures up to 80°C upon the activation with MAO and MMAO, and the sophisticated ligand architectures provided rich opportunities for controlling the temperature stability, as well as molecular weights and polydispersities …”