我们报告了包含不同供体取代基E(E = C:苯基阴离子; E = O:羧酸根,醇盐; E = N:杂环碳或氮上的吡啶)的各种C,E异构三唑基钌配合物的合成。这些供体功能的引入极大地促进了三唑的合成多功能性及其简便的制备途径。五种不同的以C,E为特征的络合物制备了具有氯/苏木精观众配体的三价钌配合中心,以及具有MeCN观众配体的三种类似的溶剂配合物,并将其评估为直接无碱和无氧化剂醇脱氢的催化剂前体,并使用碱性iPrOH作为二氢源进行了转移氢化。在这两个催化反应中,具有氯/苏木精观众配体的中性/单阳离子配合物的性能均优于溶剂钌配合物。供体的功能性对催化活性有进一步的深远影响。对于醇脱氢,C,C-双齿苯基-三唑基配体诱导最高的转化率,而羧酸盐或吡啶供体位点仅给出中等活性,或根本不给出活性。相反,当吡啶基供体基团通过杂环碳原子与三唑基亚烷基相连时,转移氢化是最有效的,对于环己酮转移氢化而言,提供高达1400
Wingtip substituents tailor the catalytic activity of ruthenium triazolylidene complexes in base-free alcohol oxidation
作者:Daniel Canseco-Gonzalez、Martin Albrecht
DOI:10.1039/c3dt32939a
日期:——
A series of RuII (η6-arene) complexes with 1,2,3-triazolylidene ligands comprising different aryl and alkyl wingtip groups have been prepared and characterized by NMR spectroscopy, microanalysis, and in one case by X-ray diffraction. All complexes are active catalyst precursors for the oxidation of alcohols to the corresponding aldehydes/ketones without the need of an oxidant or base as additive. The wingtip groups have a direct impact on the catalytic activity, alkyl wingtips providing the most active species while aryl wingtip groups induce lower activity. An N-bound phenyl group was the most inhibiting wingtip group due to cyclometalation. Arene dissociation was observed as a potential catalyst deactivation pathway.
Regioselective Electrophilic C–H Bond Activation in Triazolylidene Metal Complexes Containing a N-Bound Phenyl Substituent
作者:Kate F. Donnelly、Ralte Lalrempuia、Helge Müller-Bunz、Martin Albrecht
DOI:10.1021/om300983m
日期:2012.12.10
Transmetalation of a 1,4-diphenyl-substituted 1,2,3-triazolylidene silver complex with an electrophilic metal center, e.g., RuII, IrIII, or RhIII, induces spontaneous and chemoselective cyclometalation involving C–H bond activation of the N-bound phenyl group exclusively. Less electrophilic metals such as IrI, RhI, and PtII yield a monodentate triazolylidene complex, while cyclometalation with borderline