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Lookup NU author(s): Dr Mark Elsegood
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A series of bis(imino)pyridyliron and -cobalt complexes [{2,6-(CR=NAr)2C5H3N}MX2] (R = H, Me; M = Fe, Co; X = Cl, Br) 8-16 containing imino-aryl rings (Ar) with at least one small ortho substituent, as well as Ar = biphenyl and Ar = naphthyl, has been synthesised. Crystallographic analyses of complexes 9 (Ar = 2,3-dimethylphenyl), 13 and 14 (Ar = biphenyl; X = Cl or Br, respectively) reveal a distorted trigonal-bipyramidal geometry in the solid state. These complexes, in combination with methyl aluminoxane (MAO), are active catalysts for the oligomerisation of ethylene, yielding >99% linear α-olefin mixtures that follow a Schulz-Flory distribution. Iron ketimine (R = Me) precatalysts give the highest activities and a greater α-value than their aldimine (R = H) analogues. Cobalt precatalysls follow a similar trend, though their activities are almost two orders of magnitude lower than those of the corresponding iron catalysts. Ethylene pressure studies on cobalt precatalyst 15 reveal a first-order dependence on ethylene for both the rate of propagation and the rate of chain transfer, and a pressure independence of the α value.
Author(s): Britovsek GJP, Mastroianni S, Solan GA, Baugh SPD, Redshaw C, Gibson VC, White AJP, Williams DJ, Elsegood MRJ
Publication type: Article
Publication status: Published
Journal: Chemistry - A European Journal
Year: 2000
Volume: 6
Issue: 12
Pages: 2221-2231
ISSN (print): 0947-6539
ISSN (electronic): 1521-3765
Publisher: Wiley - VCH Verlag GmbH & Co
URL: http://dx.doi.org/10.1002/1521-3765(20000616)6:12<2221::AID-CHEM2221>3.0.CO;2-U
DOI: 10.1002/1521-3765(20000616)6:12<2221::AID-CHEM2221>3.0.CO;2-U
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