Anthony KERMAGORET - THESES ET MEMOIRES DE L'UDS

Chapitre V
activated by MAO (Scheme 3). 21-25 The catalytic behavior of these Fe(II) and Co(II)
bis(imino)pyridine complexes could be changed into oligomerization catalysts by using less
bulky aryl substituents on the ligands. 26-30 These results inspired a considerable number of
studies. 17, 31-34 (for recent examples: 31-34)
R 3
R 1
N
N M N
R 2
X
X
R 1
R 2 R 3
M = Fe, Co
X = Cl, Br
R 1 = H, Me, i-Pr, t-Bu, CF 3
R 2 = H, F, Me, i-Pr, CF 3
R 3 = H, F
Scheme 3. Typical 2,6-bis(imino)pyridyl iron or cobalt complexes
Only few phosphine or phosphonite tridentate ligands have led to effective oligomerization
Ni(II) catalyst. 35, 36 The use of bis(oxazolinyl)phenylphosphonite NOPON Me2 has led to the
pentacoordinated mononuclear nickel complex [NiCl2(NOPON Me2 )] which is an effective
precatalyst with selectivities in C4 olefins higher than 90% when activated with AlEtCl2
(Scheme 4). 37
O
N
O
Cl
Ph
P
Ni
Scheme 4. NiCl2(NOPON Me2 ) complex
The tridentate ligands NOPON Me2 and NOPON iPr afforded active ruthenium complexes for the
catalytic transfer hydrogenation and the asymmetric cyclopropanation of olefins 38 and
displayed variable coordination behaviors with palladium complexes depending on the nature
39, 40
of counteranion and the solvent.
N,P,N-type phosphine ligands on ruthenium complexes displayed interesting hemilabile
40, 41
properties and good results for the catalytic transfer hydrogenation of ketones.
Only few nickel complexes coordinated by N,P,N ligands have been synthesized in the past 42
although they might have promising properties in oligomerization of ethylene. Also the
synthesis of iron and cobalt complexes with new tridentate N,P,N ligands could provide
Cl
O
N
O
5