Bimetallic Effects on Ethylene Polymerization in the Presence of Amines: Inhibition of the Deactivation by Lewis Bases

Dinickel complexes supported by terphenyl ligands appended
with
phenoxy and imine donors were synthesized. Full substitution of the
central arene blocks rotation around the aryl–aryl bond and
allows for the isolation of atropisomers. The reported complexes perform
ethylene polymerization in the presence of amines. The inhibiting
effect of polar additives is up to 250 times lower for the syn isomer
than the anti isomer. Comparisons with mononuclear systems indicate
that the proximity of the metal centers leads to the observed inhibitory
effect on the deactivation of the catalysts.

本研究合成了一类由联有苯氧基（phenoxy）与亚胺给体（imine donors）的三联苯配体（terphenyl ligands）配位稳定的二镍配合物（Dinickel complexes）。中心芳烃环的全取代阻断了芳基-芳基键的旋转运动，因此可分离得到该配合物的阻旋异构体（atropisomers）。上述合成的配合物可在胺类助剂存在下催化乙烯聚合反应。极性添加剂的抑制效应在顺式异构体（syn isomer）中较反式异构体（anti isomer）低至多250倍。与单核体系（mononuclear systems）的对照研究表明，金属中心（metal centers）的空间邻近性是观测到的催化剂失活抑制效应的成因。