Highly active and easily accessible catalysts for vinyl polymerization of norbornene obtained by oxidative addition of salicylaldimine ligands to bis(1,5‐cyclooctadiene)nickel(0) and methylaluminoxane

Abstract

Highly active, cheap, and easy to synthesize catalytic systems, obtained in situ by the oxidative addition of salicylaldimine ligands to bis(1,5‐cyclooctadiene)nickel(0) and activated by methylaluminoxane (MAO), are now reported for the vinyl polymerization of norbornene. Their activity resulted mainly influenced by the nature of the substituents present both on the phenolate moiety and on the N‐aryl ring as well as the content of free trimethylaluminum (TMA) present in the commercial MAO. In particular, the maximum activity, up to about 78,000 kg polynorbornene/mol Ni × h, was ascertained when 3,5‐dinitro‐N‐(2,6‐diisopropylphenyl)salicylaldimine ligand was adopted in conjunction with Ni(cod)2 and TMA‐depleted MAO. This remarkable performance, to the best of our knowledge, the highest never reported working in toluene instead of chlorinated aromatics, was reached adopting this more sustainable reaction medium. The influence of the main reaction parameters such as reaction time, temperature, monomer/Ni, and Al/Ni molar ratios on the catalytic performances and polymer characteristics was studied as well. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

Neutral Nickel Catalysts for Olefin Homo- and Copolymerization: Relationships between Catalyst Structures and Catalytic Properties

“…2-Phosphinophenol ligands combined with Ni­(COD) 2 are used in the copolymerization of ethylene with α-olefins and alkyl-, aryl-, and ester-substituted α-olefins, yielding copolymer with isolated side groups . In addition, the combination of salicylaldimine ligands with Ni­(COD) 2 gives active catalysts for the homopolymerization of ethylene, MMA, NBE, and also the copolymerization of ethylene with MMA, incorporating up to 6 mol % polar comonomer into the high molecular weight polymer chain. Apart from these typical in situ catalysts generated by free ligands and nickel source complexes such as Ni­(COD) 2 , we introduce here some unconventional in situ nickel catalysts.…”

Nickel(II) Complexes with Three-Dimensional Geometry α-Diimine Ligands: Synthesis and Catalytic Activity toward Copolymerization of Norbornene

“…Different catalysts can lead to different polymerization methods of norbornene; thus, the design and synthesis of catalysts are very important. It is well-known that the vinyl addition polymerization of norbornene can be efficiently carried out using conventional Ziegler–Natta catalysts, , metallocene catalysts, − and late-transition-metal catalysts. , Recently, because of the lower oxophilicity and resistance toward deactivation by polar functionalities, the design of late-transition-metal catalysts has received renewed interest. − The common late-transition-metal catalysts are Ni(II) and Pd(II) complexes. Extensive investigations have favored Ni(II) complexes, because of their better catalytic performance and their illustrated reaction mechanisms …”