Publication Type Journal Article
Title New phenyl-nickel complexes of bulky 2-iminopyrrolyl chelates: synthesis, characterisation and application as aluminium-free catalysts for the production of hyperbranched polyethylene
Authors Claudia A. Figueira Patrícia S. Lopes Clara S. B. Gomes Joselaine C. S. Gomes Francisco Lemos Pedro T. Gomes
Groups IOARC
Journal DALTON TRANSACTIONS
Year 2018
Month November
Volume 47
Number 44
Pages 15857-15872
Abstract A family of mono(2-iminopyrrolyl) complexes with the general formula [Ni\N-2,N-5-(aryl)-NC4H2-2-C(H)?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)(2)Cl]. 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 kg(PE) mol(Ni)(-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 (M-n 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 11000 and 20000 g mol(-1), and branching degrees of 100-120 branches per 1000 C atoms.
DOI http://dx.doi.org/10.1039/c8dt02824a
ISBN
Publisher
Book Title
ISSN 1477-9226
EISSN 1477-9234
Conference Name
Bibtex ID ISI:000450208000027
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