Dehydrogenation of formic acid by Ir–bisMETAMORPhos complexes: experimental and computational insight into the role of a cooperative ligand
作者:Sander Oldenhof、Martin Lutz、Bas de Bruin、Jarl Ivar van der Vlugt、Joost N. H. Reek
DOI:10.1039/c4sc02555e
日期:——
oxidative addition of the ligand to IrIII(L) monohydride complexes 2a–c. The rate for this step strongly depends on the ligand employed. IrIII complexes 2a–c were applied in the base-freedehydrogenation of formicacid, reaching turnover frequencies of 3090, 877 and 1791 h−1, respectively. The dual role of the ligand in the mechanism of the dehydrogenation reaction was studied by 1H and 31P NMR spectroscopy
报道了三种基于呫吨的 bisMETAMORPhos 配体 ( La-Lc )的合成和互变异构性质。这些双(磺胺基膦)与 Ir(acac)(cod) 的配位最初导致形成 Ir I ( L H ) 物质 ( 1a ),其通过配体的正式氧化加成转化为 Ir III ( L ) 一氢化物配合物2a -c。此步骤的速率很大程度上取决于所使用的配体。Ir III配合物2a-c用于甲酸的无碱脱氢,达到 3090、877 和 1791 h -1的周转频率, 分别。通过1 H 和31 P NMR 光谱和 DFT 计算研究了配体在脱氢反应机理中的双重作用。除了作为内部碱基外,bisMETAMORPhos 还有助于甲酸在 Ir 配位范围内的预组装,并通过氢键帮助稳定速率决定过渡态。