Jump to main content
Jump to site search

Issue 44, 2018
Previous Article Next Article

New phenyl–nickel complexes of bulky 2-iminopyrrolyl chelates: synthesis, characterisation and application as aluminium-free catalysts for the production of hyperbranched polyethylene

Author affiliations

Abstract

A family of mono(2-iminopyrrolyl) complexes with the general formula [Ni{κ2N,N′-5-(aryl)-NC4H2-2-C(H)[double bond, length as m-dash]N-2,6-(aryl)}(C6H5)(PPh3)] were obtained from the reaction of the sodium salts of the newly synthesised 5-aryl-2-(N-arylformimino)pyrroles with the square planar complex trans-[Ni(C6H5)(PPh3)2Cl]. These new iminopyrrole ligand precursors, designed with increasing bulkiness and different electronic properties, and their corresponding nickel(II) complexes were characterised by NMR spectroscopy and elemental analysis, and their structural features were analysed by single crystal X-ray diffraction. The nickel complexes were tested as aluminium-free catalysts for the polymerisation of ethylene, at low to moderate pressures and different temperatures and in the absence or presence of the phosphine scavenger [Ni(COD)2], giving rise to catalytic activities in the range of 3.61–73.12 kgPE molNi−1 h−1 bar−1. The polyethylene products formed in these catalytic reactions were characterised by GPC/SEC and NMR spectroscopy. Generally, low molecular weight (Mn 510–1300 g mol−1) low viscosity oils were obtained, presenting high branching degrees (80–125 branches per 1000 C atoms), which are characteristic of hyperbranched polyethylene products. In particular, polymerisation reactions using catalyst 7 led to higher viscosity oils with molecular weights between 11 000 and 20 000 g mol−1, and branching degrees of 100–120 branches per 1000 C atoms.

Graphical abstract: New phenyl–nickel complexes of bulky 2-iminopyrrolyl chelates: synthesis, characterisation and application as aluminium-free catalysts for the production of hyperbranched polyethylene

Back to tab navigation

Supplementary files

Publication details

The article was received on 10 Jul 2018, accepted on 10 Sep 2018 and first published on 25 Oct 2018


Article type: Paper
DOI: 10.1039/C8DT02824A
Citation: Dalton Trans., 2018,47, 15857-15872
  •   Request permissions

    New phenyl–nickel complexes of bulky 2-iminopyrrolyl chelates: synthesis, characterisation and application as aluminium-free catalysts for the production of hyperbranched polyethylene

    C. A. Figueira, P. S. Lopes, C. S. B. Gomes, J. C. S. Gomes, F. Lemos and P. T. Gomes, Dalton Trans., 2018, 47, 15857
    DOI: 10.1039/C8DT02824A

Search articles by author

Spotlight

Advertisements