Highly Active Ethene Polymerization Catalysts with Unusual Imine Ligands - Late Transition Metal Polymerization Catalysis - page 93

Tab. 3.10.

Initial screening with hydroxyimine nickel compounds.

R 1 R 2 ,R 3 Ligand R ,R Ni-R R= Complex Observation

102 Ph Me,Me Me,Me Ph 117 trace

103 Ph Me,Me Me,Et Ph 118 trace

104 Ph Me,Me iPr,iPr Me 126 polymer

105 Ph Ph,H H,H Ph 119 oligomer

106 Ph Ph,H Me,Me Ph 120 oligomer

107 Ph Ph,H Me,Et Ph 121 oligomer

108 Ph Ph,Me H,H Ph 122 oligomer

109 Ph Ph,Me Me,Me Me 127 polymer

109 Ph Ph,Me Me,Me Ph 123 polymer

110 m -tol m -tol,Me Me,Me Ph 124 -

111 Ph Ph,Me iPr,iPr Ph 125 trace

112 Ph Ph,iPr Me,Me

113 Ph Ph,Ph iPr,iPr Me 128 polymer

114 Ph Ph,naph iPr,iPr Me 129 polymer

115 Ph Ph,Ph Me,Me Me 130 polymer

116 Ph Ph,naph Me,Me Me 131 polymer

Experiments in toluene at 20 C at 15 bar ethene pressure and 60 min polymerization time, activation

with excess tritylborate.

Polymerization data of hydroxyimine nickel compounds. Tab. 3.11

R 2 ,R 3

Compound R ,R Activity

in g pol
[g Ni h] -1

Side chains/1000 carbon atoms

Total Methyl

126 Me,Me iPr,iPr 1000 5 5

127 Ph,Me Me,Me 3350 21 10

130 Ph,Ph Me,Me 800 - -

131 Ph,naph Me,Me 1050 - -

129 Ph,naph iPr,iPr 3400 9 6

128 Ph,Ph iPr,iPr 5050 8 6

123 Ph,Me Me,Me 1000 21 15

135 iPr,iPr 5000 4 4

Experiments in toluene at 20 C at 15 bar ethene pressure and 60 min polymerization time, stoichio-

metric activation with triphenylmethylenium tetrakis(pentafluorophenyl)borate.

sentation of the dependence of the activity on the steric bulk of the substituents
( z -axis: activity, x -axis: imine substituent, y -axis: alkoxy carbon substituent): Com-
plexes that carry secondary alkoxy instead of tertiary ligands and thus have less
bulky coordination sphere tend to give oligomers rather than polymers. Fig. 3.14B
is tentatively suggestive of a structure-activity relationship: a certain amount of
steric pressure is necessary to achieve polymerization, otherwise oligomers are ob-
tained.