Symmetric and Asymmetric Binuclear α-Diimine Nickel(II) Complexes for Ethylene Polymerization

Abstract

<em>A series of symmetric and asymmetric binuclear α-diimine nickel(II) complexes toward ethylene polymerization were successfully synthesized and characterized by ¹HNMR. </em><em>All the catalysts were typically activated with MAO and displayed good activity at room temperature</em><em> under 1atm ethylene pressure. The symmetric catalyst containing </em><em>isopropyl on </em><em>ligand-activated with</em><em> 500 </em><em>equiv</em><em> MAO produced high molecular weight polyethylene with a PDI=1.75, while the symmetric</em><em> catalyst containing </em><em>methyl on ligand produced relatively low molecular weight polyethylene with a PDI=1.74. By contrast, the molecular weight, branching density of resultant polymer </em><em>produced by asymmetric catalyst decrease roughly somewhere between that of polymers prepared by</em><em> two symmetric catalysts.</em>