University of Tasmania
Browse

File(s) not publicly available

Carbon-bridged diphosphine ligands for chromium-catalysed ethylene tetramerisation and trimerisation reactions

journal contribution
posted on 2023-05-16, 23:10 authored by Overett, MJ, Blann, K, Bollmann, A, de Villiers, R, Dixon, JT, Killian, E, Maumela, MC, Maumela, H, McGuinness, DS, Morgan, DH, Rucklidge, A, Slawin, AMZ
The use of carbon-bridged diphosphine ligands in chromium-catalysed ethylene tri- and tetramerisation reactions has been investigated. Two- and three-carbon spacer ligands all showed activity for selective oligomerisation, with a structure-selectivity correlation between P-Cr-P bite angle and 1-octene:1-hexene ratio evident. Activated chromium complexes of single carbon spacer diphosphines were also shown to be effective tetramerisation catalysts, provided that the ligand is innocent under the conditions of catalyst activation. A catalyst with the bis(diphenylphosphino)benzene ligand was found to be exceptionally active, although the combined 1-hexene and 1-octene selectivity was lower than with the best diphosphinoamine (PNP) ligands. The yield losses to by-products can to an extent be minimised by the use of high reaction temperatures and pressures. Unlike with the PNP-based systems, attempts to activate the Cr/bis(diphenylphosphino)benzene catalyst in situ from a chromium salt and free ligand resulted in low activity and high polymer formation. The effect of different phosphine substitution on catalyst selectivity was explored. Steric constraints around the catalytic centre (ortho-alkylphenyl phosphines) resulted in a shift towards 1-hexene formation, as with PNP catalysts. Additionally, the basicity of the phosphines appears to influence catalyst selectivity, with alkyl phosphines favouring trimerisation. An interplay between phosphine basicity and bridge structure is in evidence, however, as a catalyst containing a ligand with both basic phosphine atoms and a small bite angle was shown to be selective towards 1-octene. © 2007 Elsevier B.V. All rights reserved.

History

Publication title

Journal of Molecular Catalysis A: Chemical

Volume

283

Issue

1-2

Pagination

114-119

ISSN

1381-1169

Department/School

School of Natural Sciences

Publisher

Elsevier Science BV

Place of publication

Amsterdam

Repository Status

  • Restricted

Socio-economic Objectives

Organic industrial chemicals (excl. resins, rubber and plastics)

Usage metrics

    University Of Tasmania

    Exports

    RefWorks
    BibTeX
    Ref. manager
    Endnote
    DataCite
    NLM
    DC