Ligand Modification for Selectivity Control in Selective Ethylene Oligomerization

A series of aminophosphine ligands were synthesized by in situ combination of CrCl 3 (THF) 3 and dry methylaluminoxane and examined for their catalytic behavior in chromium-catalyzed selective ethylene oligomerization. Variations of the ligand scaffold obtained by modifying the diarylphosphine moiety affected the steric bulkiness, which resulted in remarkable changes in the selectivity for 1-hexene vs. 1-octene. Based on our experimental results, we evaluated two different mechanisms proposed for selective ethylene oligomerization.