Very Active Neutral P,O-Chelated Nickel Catalysts for Ethylene Polymerization

Abstract

A series of highly active nickel-based neutral catalysts for ethylene polymerization is presented. These catalysts are obtained by direct complexation of simple fluorinated ketoylides onto bis(1,5-cyclooctadiene)nickel. Catalyst formation readily occurs in the presence of an olefin, but due to the electron deficiency of the ligand, it hardly happens in the absence of an olefin or another Lewis base. Activities greater than 2 × 106 (gPE/gNi)/h and productivities higher than 15 × 106 gPE/molNi are typically observed. These catalysts are also active for the polymerization of α-olefins such as 1-hexene and 1-propene. Polymer characterization indicates that highly linear, low molecular weight PEHD is formed by these complexes.

Investigation of Steric and Electronic Factors of (Arylsulfonyl)phosphane‐Palladium Catalysts in Ethene Polymerization

“…This is in good agreement with the observed high activity reported for late-transition-metal polymerization catalysts that bear electron-deficient ligands. [25,26] Furthermore, as a reviewer pointed out, for the catalyst that bears 2-[2,6-(MeO) 2 C 6 H 3 ]-C 6 H 4 -aryl groups, the bulk is mostly located in the axial faces. [12] By contrast, it is possible to imagine that catalysts 3Pd to 5Pd are encumbered in the complex plane, with the result that monomer coordination is slowed, but with no rate decrease for β-H elimination.…”

Synthesis and characterization of N-(2-pyridyl)benzamide-based nickel complexes and their activity for ethylene oligomerization

“…Recently, neutral nickel(II) complexes have attracted much attention because they are less sensitive to protonic solvents and polar monomers than cationic nickel analogues. The most famous example of neutral nickel(II) catalysts is the SHOP-type [12][13][14][15][16][17][18]. These nickel complexes contain an anionic [P, O] chelate ring and show high activity and selectivity for the conversion of ethylene to linear a-olefins and polymers.…”

Titanium (IV) and Nickel (II) Catalysts Based on Anilinotropone Ligands

“…(3) Many late-metal catalysts are compatible with protic solvents and nucleophilic impurities. Water compatibility has led to successful emulsion polymerization of ethylene [43][44][45][46]. (4) Expanded functional group tolerance has permitted the copolymerization of alkyl acrylates (polar monomers) with ethylene andolefins (non polar monomers) [47][48][49][50].…”

“…In view of the high sensitivity of the cationic Ni and Pd catalysts, there has been substantial interest in developing neutral Ni catalysts to overcome these limitations. Several examples of neutral Ni catalysts based on SHOP-type (Shell Higher Olefin Process) ligands have been reported, although productivities and molecular weights are often low [45,50,55,56]. Neutral Ni catalysts modeled after -diimine complexes, containing bulky ortho-disubstituted arylimine functionality, have been reported.…”