作者:Andrew J. Roering、Jillian J. Davidson、Samantha N. MacMillan、Joseph M. Tanski、Rory Waterman
DOI:10.1039/b718050k
日期:——
Triamidoamine-supported zirconium complexes have been demonstrated to catalyze a range of bond-forming events utilizing arsines. Three different mechanisms have been observed in these reactions. In the first mechanism, triamidoamine-supported zirconium complexes of the general type (N3N)ZrX (N3N = N(CH2CH2NSiMe3)33−; X = monoanionic ligand) catalyzed the dehydrogenative dimerization of diphenylarsine. Mechanistic analysis revealed that As–As bond formation proceeds via σ-bond metathesis steps similar to the previously reported dehydrocoupling of phosphines by the same catalysts. In the second mechanism, sterically encumbered primary arsines appear to be dehydrocoupled via α elimination of an arsinidene fragment. Dehydrocoupling of dmpAsH2 (dmp = 2,6-dimesitylphenyl) to form (dmp)As = As(dmp) by (N3N)Zr-complexes appeared to proceed via elimination of dmpAs: from the arsenido intermediate, (N3N)ZrAsH(dmp). Further support for α-arsinidene elimination came from the thermal decomposition of (N3N)ZrAsHMes (9) to (MesAs)4 (10), which obeyed first-order kinetics. In the third mechanism, the observation of stoichiometric insertion reactivity of the Zr–As bond with polar substrates, PhCH2NC, PhCN, (1-napthyl)NCS, and CS2, led to the development of intermolecular hydroarsination catalysis of terminal alkynes. Here, (N3N)ZrAsPh2 (2) catalyzed the addition of diphenylarsine to phenylacetylene and 1-hexyne to give the respective vinylarsine products. Arsenido complexes 2 and 9 and tetraarsine 10 have been structurally characterized.
三氨基胺支撑的锆复合物已被证实能够催化一系列利用胂进行成键反应,这些反应中观察到三种不同的机理。在第一种机理中,一般类型的三氨基胺支撑的锆复合物(N3N)ZrX(N3N = N(CH2CH2NSiMe3)33−;X = 单阴离子配体)催化二苯胂的脱氢二聚化。机理分析表明,As–As键的形成是通过类似以前报道的由相同催化剂催化的膦的脱氢偶联反应的σ键交换步骤进行的。在第二种机理中,空间位阻较大的初级胂似乎通过α消除一个胂代碎片而脱氢偶联。由(N3N)Zr-复合物催化的dmpAsH2(dmp = 2,6-二甲基苯基)脱氢偶联形成(dmp)As = As(dmp)似乎是通过从胂中间体(N3N)ZrAsH(dmp)消除dmpAs:进行的。对α-胂代消除的进一步支持来自(N3N)ZrAsHMes(9)的热分解为(MesAs)4(10),其遵循一级动力学。在第三种机理中,观察到Zr–As键与极性底物的计量插入反应,如PhCH2NC、PhCN、(1-萘基)NCS和CS2,这导致了末端炔烃的分子间胂氢化催化的发展。这里,(N3N)ZrAsPh2(2)催化二苯胂对苯乙炔和1-己炔的加成,生成相应的乙烯基胂产物。胂复合物2和9以及四胂10已被结构表征。