Nickel-based ethylene oligomerization catalysts supported by PNSiP ligands

摘要

A series of nickel (II) complexes bearing silicon bridged diphosphines ligands (PNSiP) have been synthesized and characterized. All nickel precatalysts, activated with ethylaluminum dichloride (EtAlCl2), exhibited moderate to high activities for ethylene dimerization to butylene. The in situ nickel precatalysts formed by mixing N-cyclopentyl-N-((diphenylphosphanyl)dimethylsilyl)-1,1-diphenylphosphanamine (L2) with NiBr2(DME) showed high catalytic activity (2.40 x 10(8) g/(mol(Ni)h)) and high product selectivity (88.6%) towards butene using methylcyclohexane as solvent at 1.0MPa ethylene pressure and 45 degrees C temperature, no polyethylene(PE) was observed. Ligand backbone tuning of PNSiP-based catalytic systems help in precise understanding of steric bulk variation effects on catalytic performance.