Mechanistic studies of the ethylene trimerization reaction with chromium-diphosphine catalysts: Experimental evidence for a mechanism involving metallacyclic intermediates
Mechanistic studies of the ethylene trimerization reaction with chromium-diphosphine catalysts: Experimental evidence for a mechanism involving metallacyclic intermediates
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DOI：
10.1021/ja038968t
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发表时间：
2004-02-11
影响因子：
15
通讯作者：
Bercaw, JE
中科院分区：
文献类型：
--
作者：
Agapie, T;Schofer, SJ;Bercaw, JE
研究了CrCl3(THF)3和二膦配体PNPOMe[= (o-MeO-C6H4)2PN(Me)P(o-MeO-C6H4)2]催化乙烯三聚反应体系。研究了铬与PNPOMe的配位化学反应，以铬（III）为前驱体，采用醚置换法制备了（PNPOMe） crcl3和（PNPOMe）CrPh3(3)。（PNPOMe） crcl3与o，o ' -联苯二基格氏盐反应得到（PNPOMe）Cr（o,o ' -联苯二基）Br(4)。用H(Et2O)2B[C6H3(CF3)2]活化3或用NaB[C6H3(CF3)2]活化4生成催化体系，并将c2d4和c2h4以1:1的比例三聚得到1-己烯的同位素体（C6D12、C6D8H4、C6D4H8和c6h12按1:3:3:1的比例进行H/D打乱）。缺乏交叉支持涉及金属环中间体的机制。通过NaB[C6H3(CF3)2]4活化后的反式、顺式和gemem -乙烯-d2with4反应，研究了乙烯三聚反应的机理。
A system for catalytic trimerization of ethylene utilizing CrCl3(THF)3and a diphosphine ligand PNPOMe[= (o-MeO-C6H4)2PN(Me)P(o-MeO-C6H4)2] has been investigated. The coordination chemistry of chromium with PNPOMehas been explored, and (PNPOMe)CrCl3and (PNPOMe)CrPh3(3) have been synthesized by ether displacement from chromium(III) precursors. Salt metathesis of (PNPOMe)CrCl3witho,o‘-biphenyldiyl Grignard affords (PNPOMe)Cr(o,o‘-biphenyldiyl)Br (4). Activation of3with H(Et2O)2B[C6H3(CF3)2]4or4with NaB[C6H3(CF3)2]4generates a catalytic system and trimerizes a 1:1 mixture of C2D4and C2H4to give isotopomers of 1-hexene without H/D scrambling (C6D12, C6D8H4, C6D4H8, and C6H12in a 1:3:3:1 ratio). The lack of crossover supports a mechanism involving metallacyclic intermediates. The mechanism of the ethylene trimerization reaction has also been studied by the reaction oftrans-,cis-, andgem-ethylene-d2with4upon activation with NaB[C6H3(CF3)2]4.