Chromium Ethylene Tri-/Tetramerization Catalysts Supported by Iminophosphine Ligands
Xing Zhao1, Jihe Wang1, Dongchang Liu1
1Key Laboratory for Advanced Materials and Institute of Fine Chemicals, School of Chemistry & Molecular Engineering, East China University of Science and Technology, 130 Mei Long Road, Shanghai 200237, China.
Abstract:
A new class of highly active ethylene tri-/tetramerization chromium catalysts supported by iminophosphine ligands has been studied. The impact of electronic and steric changes of these ligands on selectivity and activity has been investigated by varying P- and/or N-substituents. Upon activation with MMAO, the ligand bearing a P-cyclohexyl group displayed a high activity of 307 kg/(g Cr/h) with a high trimerization selectivity of 92.6%. Decreasing the steric hindrance of N-aryl group led to a decrease in 1-hexene selectivity (74.5%), producing more 1-octene (10.3%). X-ray diffraction analysis verifies that the ligands coordinate with the chromium center in a κ2-P,N mode.
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