Asymmetric alkylphosphanyl carbon-bridged diphosphine Ph₂PC = CPR₁(R₂)-type L¹-L⁵ ligand has been observed to have a distinct effect on the catalytic performance of the corresponding Cr(III) based catalysts in ethylene oligomerization. Precatalyst 1, bearing diethylphosphanyl moiety, exhibited a high catalytic activity of 3628 kg·g⁻¹·h⁻¹ accompanied by 65.5% high C₈ selectivity. Precatalyst 2 having diisopropylphosphanyl group afforded remarkably high catalytic activity of 4833 kg·g⁻¹·h⁻¹ with 91.8% combined (C₆ + C₈) product selectivity. Precatalysts 1–2 also showed good thermal stability and offer high catalytic activity at the high reaction temperature. Precatalyst 3 with sterically encumbered dicyclohexylphosphanyl substituent mainly offers C₆ selectivity at the expense of the C₈ fraction. Precatalyst 5 having isopropylphosphanyl moiety afforded poor catalytic activity and high C₆ selectivity. Density functional theory (DFT) calculations of precatalyst 2 showed that the rate-determining step in the trimerization pathway of the catalyst may face a low energy barrier and therefore produce more C₆ fraction.

已观察到不对称烷基膦基碳桥联二膦Ph ₂ PC = CPR ₁ (R ₂ )-型L ¹ -L ^{5配体对相应的基于Cr(III)的催化剂在乙烯齐聚中的催化性能具有明显影响。}带有二乙基磷酰基部分的预催化剂1表现出3628 kg·g -1 ·h -1 的高催化活性，同时^具有65.5 ^%的高C ₈选择性。具有二异丙基膦基的预催化剂2提供了4833 kg·g ^-1 ·h ^-1的非常高的催化活性，结合率为 91.8%（C₆  + C ₈ ) 产物选择性。预催化剂1-2也表现出良好的热稳定性，并在高反应温度下提供高催化活性。具有空间位阻二环己基膦基取代基的预催化剂 3 主要提供 C 6选择性_，但牺牲了 C ₈馏分。具有异丙基膦基部分的预催化剂5提供了差的催化活性和高的C ₆选择性。前催化剂2的密度泛函理论 (DFT) 计算表明，催化剂三聚化途径中的速率决定步骤可能面临低能垒，因此产生更多的 C₆分数。