Anthony KERMAGORET - THESES ET MEMOIRES DE L'UDS

Chapitre IV
Scheme 1. Complexes with P,N-type ligands for the catalytic oligomerization or
O
Me
O
polymerization of ethylene (references given in the text)
Ph 2
P
N
Ph 2
P
R 2
P
N
Ni
Br
Br
R = Ph, t-Bu
Ni
4
BF 4
R 1 2
P
N
Pd
R 2 R 2
O
S
O
i-Pr
R 3
R 2
P
N
Ni
Me
Cl
R 1 = Ph, CH 3OMe
R 2 = H, Me, iPr
R 3 = H, Cl, OMe
R
R
Ph
O
Cl
Ni
Cl
N
R
R
R = H, Me
9
N
N
Ni
Ph N PR3 Ph
PR3 = PMe3, PMe2Ph, PMePh2 11
N
R2 Ni
P
Ph2 Cl
Cl
R1 = Me, t-Bu, Mes
R 2 = Me
10
Me
L
i-Pr
R = Ph, o-Tol, p-Tol, Et, C 6H 11, t-Bu
L = MeCN, PPh 3, Pyridine
5
Me
Ph
Mes *
P
N
Ar
6 7 8
R 1
Ph 2
P
Pd
Me
NCMe
B(Ar F) 4
The properties and applications of transition metal complexes with phosphinopyridine
ligands have been reviewed 38-41 and some of their Ni(II) complexes catalyze the
oligomerization of ethylene in the presence of MAO 42-45 or AlEtCl2 46 as cocatalyst. We have
recently reported Ni(II) complexes with phosphinopyridine ligands which led to high
selectivities for the dimerization of ethylene but modest selectivities for α−olefins, and some
ethylene trimerization was also noted. 47-50 We were therefore interested in the synthesis of
new Ni(II) catalyst precursors based on phosphinopyridine ligands with different substituents
on phosphorus to modify its electronic and steric effects and examine the consequences for
this catalytic reaction. Introducing t-butyl substituents on phosphorus will result in ligands
with a larger cone angle 51 and their influence on the stability of the complexes and their
catalytic properties has now been investigated.
4