2-Phosphinophenolate Nickel Catalysts: Formation of Ethylene Copolymers with Isolated sec-Alkyl, Aryl, and Functionally Substituted Alkyl Groups

Abstract

The 2-phosphinophenolate nickel catalyzed oligo- or polymerization of ethylene in the presence of olefins usually leads to improved conversion or copolymerization. The outcome depends strongly on the nature of the P-substituents and olefins. The diphenylphosphinophenolate ligand (PPHH) favors improved yields of waxy linear ethylene oligomers, whereas the more P-basic dicyclohexylphosphinophenolate (CCHH) induces incorporation of alkyl-, aryl-, and ester-substituted α-olefins into a growing ethylene polymer chain and larger molar masses of the polymers. Depending on the nature of the olefin, the reaction rate and the conversion are lowered by olefin incorporation. Ester groups are tolerated if distant to the CC bond but block the catalyst if close to the olefinic group. A remarkable increase of activity accompanied by small branching was observed in the copolymerization with ethyl undecenoate by the nickel diphenylphosphinophenolate catalyst. 13C and 1H NMR spectra give evidence that ethylene copolymers with isolated side groups, imbedded into linear polyethylene blocks with vinyl end groups, are formed.

Well-defined phosphino-phenolate neutral nickel(ii) catalysts for efficient (co)polymerization of norbornene and ethylene

“…4,69 As part of ongoing research in our group, we are interested in the properties of [P,O] chelate neutral nickel catalysts for (co)polymerization of norbornene. While SHOP type catalysts have been rigorously studied for ethylene oligomerization or polymerization as in situ catalysts, 51,70,71 well-defined catalysts based on phosphino-phenolate ligands were rarely reported, [72][73][74][75] especially their activity towards norbornene and its derivatives. In this report, well-defined phosphino-phenolate Ni(II)-Me pyridine complexes 1-3 (Scheme 1) were examined in combination with a low dosage of B(C 6 F 5 ) 3 in norbornene (co)polymerization, yielding high molecular weight PNB or functionalized PNB.…”

Nickel and Palladium Complexes with New Phosphinito-Imine Ligands and Their Application as Ethylene Oligomerization Catalysts

“…17 Despite the important developments achieved in this area, metal catalysts producing short-chain -olefins with narrow Schulz-Flory distributions are still main targets. [18][19][20] Nickel and palladium catalysts containing P,N ligands have received much attention in the context of ethylene oligomerization 8,10,[21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] or polymerization. 28.29,35 In general, the presence of a phosphorus donor enhances the stability of the complexes, while the imine fragment can be used for tuning the activity and selectivity of the catalyst.…”

Neutral Nickel Oligo‐ and Polymerization Catalysts: The Importance of Alkyl Phosphine Intermediates in Chain Termination

“…[20][21][22] The tolerance for polar functional groups also makes random copolymerization of nonpolar and polar olefins appear to be a realistic objective, [4,[23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39] a goal that is particularly desirable if it can be obtained with the normally quite active and cost-efficient nickel catalysts. [12,[40][41][42][43][44][45][46][47][48][49] Modern catalyst and process technology allows for polymers to be tailored according to specific needs. One of the tunable properties of a polymer is the molecular weight, which significantly influences the physical properties of materials.…”