Nickel-based ethylene oligomerization catalysts supported by PNSiP ligands

Abstract

<p>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 <i>in situ</i> nickel precatalysts formed by mixing N-cyclopentyl-N-((diphenylphosphanyl)dimethylsilyl)-1,1-diphenylphosphanamine (<b>L2</b>) with NiBr₂(DME) showed high catalytic activity (2.40 × 10⁸ g/(mol_Ni<b>·</b>h)) and high product selectivity (88.6%) towards butene using methylcyclohexane as solvent at 1.0 MPa ethylene pressure and 45°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.</p