Ethylene tri-/tetramerization catalysts supported by diphosphinothiophene ligands
Ethylene tri-/tetramerization catalysts supported by diphosphinothiophene ligands
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二膦基噻吩配体负载的乙烯三聚/四聚催化剂
DOI：
10.1039/c7dt01060e
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发表时间：
2017
影响因子：
4
通讯作者：
Zhang Jun
中科院分区：
文献类型：
--
作者：
Zhang Chengye;Song Liubing;Wu Hongfei;Ji Xiaoyu;Jiao Jiajun;Zhang Jun
已经开发出由一系列二膦基噻吩配体负载的 Cr(III) 催化剂，所有这些催化剂在用 MMAO-3A 活化后，都具有乙烯三聚/四聚活性。已经检查了配体取代对催化性能的影响。由C2位上含有一个三甲基甲硅烷基的二膦基噻吩配体负载的Cr预催化剂实现了高达686 kg（g Cr h−1）−1的高活性，对1-己烯（29.5%）和1-辛烯（39.5%）的总选择性高达69%。合成了两种带有二膦噻吩配体的代表性 Cr 配合物，并通过单晶 X 射线衍射进行了结构表征。将两种 Cr 配合物与类似的二膦 Cr 配合物的配位结构数据进行比较，揭示了两个相邻桥接碳原子的键长与催化活性之间的直接相关性：较短的键长和较小的配体咬角导致较高的催化活性。这些具有微调主链的二膦噻吩配体为精确理解配体变化对催化性能的影响提供了一个模型。
Cr(III) catalysts supported by a series of diphosphinothiophene ligands have been developed, all of which, upon activation with MMAO-3A, are active for ethylene tri-/tetramerization. The effect of ligand substitution on the catalytic performance has been examined. The Cr precatalyst supported by the diphosphinothiophene ligand containing one trimethylsilyl group at the C2 position achieved a high activity of up to 686 kg (g Cr h−1)−1 with a total selectivity of up to 69% toward 1-hexene (29.5%) and 1-octene (39.5%). Two representative Cr complexes bearing the diphosphinothiophene ligand were synthesized and structurally characterized by single-crystal X-ray diffraction. Comparison of the coordination structure data of the two Cr complexes with those of an analogous diphosphine Cr complex reveals a direct correlation between the bond length of two adjacent bridging carbon atoms and catalytic activity: a shorter bond length and hence smaller ligand bite angle lead to higher catalytic activity. These diphosphinothiophene ligands featuring a fine-tuned backbone provide a model for the precise understanding of the impact of ligand variations on the catalytic performance.