Ethylene tri-/tetramerization catalysts supported by diphosphinoindole ligands

Abstract A new class of diphosphinoindole ligands have been developed. Upon activation with MMAO-3A, Cr catalysts supported by these bisphosphine ligands are active for ethylene tri-/tetramerization. The best result was achieved by using the bisphosphine ligand containing a phenyl group at C3 position of indole, giving a high activity of up to 364 kg/(g Cr/h) with a total selectivity of up to 72% toward 1-hexene (23.5%) and 1-octene (48.4%). A representative chromium tetracarbonyl complex was synthesized and structurally characterized by single-crystal X-ray diffraction.