Sterically modulated binuclear bis-α-diimine Pd(II) complexes: Synthesis, characterization, DFT studies and catalytic behavior towards ethylene oligomerization

A series of Pd(II) complexes of bis-α-diimine derivatives with substituent at 2,6-positions of aniline increasing sterically from Me < Et < iPr groups have been synthesized to act as a versatile set of catalytic precursors for oligomerization of ethylene in combination with aluminum activators. Treatment of the bimetallic Pd(II) complexes with ethylaluminum sesquichloride (EASC) or Methylalluminooxane (MAO) in toluene generates active cationic catalyst in situ that oligomerize ethylene to α-olefins. All the Pd(II) complexes efficiently oligomerize ethylene to produce C4C20 fractions at activities of up to 1218.4 kg-oligomer mol-Pd−1 bar−1 h−1 at 30 °C in combination with EASC.