Anthony KERMAGORET - THESES ET MEMOIRES DE L'UDS

Chapitre VI
C6D6): δ 0.79 (3H, br s, CH3), 1.45-1.67 (6H, br m, CH2), 4.81 (1H, br s, PCH), 6.28 (2H, br
s, aromatic H), 6.71 (1H, br s, aromatic H), 6.93-7.35 (12H, br m, aromatic H), 8.06 (2H, br s,
aromatic H), 8.37 (1H, br s, aromatic H), 8.55 (2H, br s, JPH = 7.2 Hz, aromatic H); 31 P{ 1 H}
NMR (C6D6, 121.5 MHz): δ 22.0 (s, PPh(n-Bu)).
[NiPh{Me 2PCH⋅⋅⋅C(⋅⋅⋅O)Ph}(Py)] 22
A solution of 0.072 g (0.26 mmol) of [Ni(COD)2] in 5 mL of toluene was added to a
solution of 0.067 g (0.26 mmol) of 11 and 1 mL of pyridine (12.66 mmol) in 5 mL of toluene
and the mixture was stirred overnight at room temperature. After reaction, complex 22 was
isolated as a pale yellow powder after elimination of the solvents under reduced pressure. The
1 H NMR spectrum indicated a yield of 83% based on [Ni(COD)2]. 1 H NMR (300 MHz,
C6D6): δ 0.87 (6H, d, 3 JPH = 8.4 Hz, CH3), 4.63 (1H, br s, PCH), 6.41 (2H, br s, aromatic H),
6.72 (1H, br s, aromatic H), 6.93-7.33 (7H, br m, aromatic H), 7.56 (2H, br s, aromatic H),
8.11 (1H, br s, aromatic H), 8.66 (2H, br s, aromatic H); 31 P{ 1 H} NMR (C6D6, 121.5 MHz): δ
4.0 (s, P(Me)2).
Oligomerization of ethylene. All catalytic reactions were carried out in a
magnetically stirred (900 rpm) 145 mL stainless steel autoclave. A 125 mL glass container
was used to protect the inner walls of the autoclave from corrosion. 0.20 mmol of [Ni(COD)2]
(0.055 g) was dissolved in10 mL of toluene and the solution was added to a 10 mL toluene
solution containing 0.20 mmol (0.052 g) of PPh3 and 0.20 mmol of ylid. The mixture was
immediately injected into the reactor under a constant low flow of ethylene and the reactor
was pressurized to 30 bar. The 30 bar working pressure were maintained during the
experiments through a continuous feed of ethylene from a reserve bottle. At the end of each
test, the gaseous phase was transferred into a 10 L polyethylene tank filled with water. An
aliquot of this gaseous phase was transferred into a Schlenk flask, previously evacuated, for
GC analysis. The products in the reactor were transferred into a Schlenk flask, and all
volatiles were separated from high weight oligomers or polymers and the metal complexes
before GC analysis by trap-to-trap evaporation (20 °C, 0.3 mm Hg) into a second Schlenk
flask previously immersed in liquid nitrogen in order to avoid any loss of product. Ethylene
consumption was calculated by addition of the mass of oligomers from the gas layer, the mass
of oligomers from the volatile liquid layer and the mass non-volatile products minus the mass
of complex.
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