Iron-catalysed homo- and copolymerisation of propylene: steric influence of bis(imino)pyridine ligands

Abstract

A series of iron complexes bearing a bis(imino)pyridine ligand were synthesised and examined as precatalysts for homopolymerisation of propylene. The alkyl substituents attached to the aryl group on the imine nitrogen atoms significantly affected the catalytic activity and molecular weight of the obtained polypropylenes. Copolymerisation of propylene and various allyl comonomers catalysed by iron/bis(imino)pyridine was also investigated.

A new family of complexes derived from bis(imino)pyridine‐type ligands: Crystal structures and bio‐molecular interaction studies

“…[ 33 ] In complex 2 , Fe‐Npy (Fe1‐N10) bond distance was found to be 2.076 Å, which is lower than the reported values by our previous reports [ 26 ] as well as Britovsek et al [ 34 ] The bond lengths of Fe1‐N4 and Fe‐N19 were 2.233 Å and 2.266 Å respectively which were lower than the values reported by Britovsek et al [ 34 ] However, these distances were observed to be higher than the values mentioned in our previous reports [ 26 ] as well as values reported by Nozaki and co‐workers. [ 35 ] The bond lengths of Fe1‐Cl2 and Fe‐Cl3 were observed in 2.299 Å and 2.294 Å, respectively, which were comparable with our previous reports [ 26 ] as well as other literature reports. [ 34,35 ] In complex 3 , Co‐N imine bond distances were observed to be 2.210 Å (Co1‐N2) and 2.210 Å (Co1‐N2′), which were same due to symmetry.…”

Palladium-Catalyzed Homo- and Copolymerization of Polar Monomers: Synthesis of Aliphatic and Aromatic Polymers

“…Although iron/bis(imino)-pyridine catalysts afford regioregular polypropylenes with high molecular weights, 67,68 they cannot be applied to polar monomer copolymerization because the iron catalysts are significantly deactivated in the presence of polar monomers. 69 The above background states that the copolymerization of propylene and polar monomers is much more difficult than that of ethylene and polar monomers. In fact, only two examples of late-transition-metal-catalyzed propylene/polar monomer copolymerization had been reported prior to 2015 (Figure 12).…”

Emerging Palladium and Nickel Catalysts for Copolymerization of Olefins with Polar Monomers

“…Palladium has been the dominant player in this field, with more high-performance nickel catalysts emerging.M eanwhile,the utilization of other transition metals such as iron, [98] titanium, [99] and rare-earth metals [100][101][102][103][104] has been investigated. Most research in this field has been focused on the identification of ac apable catalyst system, and subsequent improvements through modifications of the ligand electronics and sterics.The search for alternative and general strategies is highly desired, especially when dealing with the polar monomer problem.…”