A series of novel bisphosphinoamine ligands: Synthesis, characterization and application in ethylene tetramerization

A series of novel N-halogen-substituted-aryl bisphosphinoamine ligands were synthesized and characterized by elemental analysis, H-1 NMR and mass spectrometry. The combination of these ligands with Cr(III) and activation by methylaluminoxane leads to highly active catalytic systems for the tetramerization of ethylene to form 1-octene. The catalytic activities and product selectivities depend on the aryl ring substituents and the reaction conditions. We found that the location and size of the substituents are important in determining the catalytic activity and selectivity toward 1-octene. This trend is similar to that observed for their alkyl-substituted analogues.