Issue 5, 2002
From the journal:

New Journal of Chemistry

NiCl2(1,2-Diiminophosphorane) complexes: a new family of readily accessible and tuneable catalysts for oligomerisation of ethylene

Mathieu Sauthier,a   François Leca,a   Roberto Fernando de Souza,*b   Katia Bernardo-Gusmão,b   Luiz Fernando Trevisan Queiroz,b   Loïc Toupetc  and  Régis Réau*a  

* Corresponding authors

a Organométalliques et Catalyse, Chimie et Electrochimie Moléculaires, (CNRS UMR 6509), Institut de Chimie, CNRS - Université de Rennes 1, Campus de Beaulieu, Rennes cedex, France
E-mail: regis.reau@univ-rennes1.fr

b Instituto de Química, UFRGS, Av. Bento Gonçalves 9500, P.O. Box 15003, Porto Alegre, Brazil
E-mail: rfds@if.ufrgs.br

c Groupe Matière Condensée et Matériaux, (CNRS UMR 6626), CNRS-Université de Rennes 1, Rennes cedex, France

Abstract

1,2-Diiminophosphoranes 1–4 featuring either ethane, benzene, cyclohexane or 1,2-diphenylethane carbon backbones act as tightly bonded 1,4-chelating ligands towards NiCl2, affording the corresponding paramagnetic complexes 5–8 in high yield. X-Ray diffraction studies performed on compounds 5 and 6 revealed that the conformation of the five-membered metallacycle depends on the rigidity of the carbon backbone. For both complexes, the coordination sphere of the Ni atom is a distorted tetrahedron with bond lengths and angles around nickel similar to those observed for related Ni(II)(α-diimine) complexes. Complexes 5–8 are active for ethylene oligomerisation under mild reaction conditions (0 °C, 1.1 bar) upon activation by alkylaluminum derivatives (Et2AlCl or MAO). The nature of the carbon backbone of the 1,2-diiminophosphorane ligands has a profound impact on the selectivity of the catalytic systems. The selectivity for trimers and higher oligomers varies from 10% (pre-catalyst 8) to 81% (pre-catalyst 5). Effects of varying ethylene pressure, temperature and aluminium co-catalyst/nickel ratios with pre-catalyst 6 are reported. Tailoring the reaction parameters has a modest effect on the oligomer distribution but allows quite high catalytic activities to be achieved with turnover frequencies up to 135 × 103 h−1.

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Article information

DOI
https://doi.org/10.1039/B109992M
Article type
Paper
Submitted
29 Oct 2001
Accepted
26 Dec 2001
First published
23 May 2002

New J. Chem., 2002,26, 630-635

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NiCl2(1,2-Diiminophosphorane) complexes: a new family of readily accessible and tuneable catalysts for oligomerisation of ethylene

M. Sauthier, F. Leca, R. Fernando de Souza, K. Bernardo-Gusmão, L. F. Trevisan Queiroz, L. Toupet and R. Réau, New J. Chem., 2002, 26, 630 DOI: 10.1039/B109992M

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