Nickel indenyl complexes as catalysts for the dimerization and polymerization of ethylene

Citation
Ma. Dubois et al., Nickel indenyl complexes as catalysts for the dimerization and polymerization of ethylene, ORGANOMETAL, 20(4), 2001, pp. 663-666
Citations number
23
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Organic Chemistry/Polymer Science
Journal title
ORGANOMETALLICS
ISSN journal
0276-7333 → ACNP
Volume
20
Issue
4
Year of publication
2001
Pages
663 - 666
Database
ISI
SICI code
0276-7333(20010219)20:4<663:NICACF>2.0.ZU;2-5
Abstract
The nickel indenyl compounds md(PR3)Ni-X (Ind = indenyl and its substituted derivatives; R = Ph, Cy, Me; X = Cl, Me, CCPh) can dimerize and/or polymer ize ethylene in the presence of suitable activators. For example, poly(meth ylaluminoxanes) (PMAO) combine with these Ni precursors to produce catalyti cally active species for both the dimerization and polymerization of ethyle ne. The polymers obtained from these reactions;are mostly linear polyethyle nes which contain a small number of ethyl branches and exhibit molecular we ights in the range of M-w = 10(5) (M-w/M-n ca. 2). On the other hand; using activators such as AgBF4, AlCl3, and B(C6F5)(3) leads to the exclusive for mation of butenes. It is proposed that the latter activators convert the Ni -precursors to the highly electrophilic cations [IndNi(PR3)](+), which effi ciently catalyze the dimerization of ethylene to butenes; in contrast, Ni/P MAO combinations- give both the aforementioned cationic species as well as neutral species bearing a Ni(mu -Me)Al core, which is thought to be the act ive site for the polymerization reactions.