Uhl Werner, Bohnemann Jörg, Kappelt Benedikt, Hepp Alexander, Layh Marcus
Institut für Anorganische und Analytische Chemie der Universität Münster, Corrensstraße 30, D-48149 Münster, Germany.
Dalton Trans. 2014 Oct 14;43(38):14386-98. doi: 10.1039/c4dt00922c.
Hydrometallation of a pyrrolidyl functionalised trialkynylsilane, H8C4N-Si(C≡C-CMe3)3, with equimolar quantities of H-M(CMe3)2 (M = Al, Ga) resulted in the formation of mixed alkenyl-dialkynylsilanes (3a, 3b) which have a Lewis-acidic Al or Ga atom in the geminal position to the Si atom and form four-membered M-N-Si-C heterocycles by a strong interaction of the amine N atoms with the Lewis-acidic metal atoms. This interaction results in a concomitant lengthening and weakening of the Si-N bonds. Dual hydrometallation afforded alkynyl-dialkenylsilanes (4a, 4b) with two Lewis-acidic metal atoms. Al-N and Ga-N interactions to one of the Lewis-acidic centres led again to the formation of M-N-Si-C heterocycles. The second Al atom of 4a interacted with C-H bonds of the vinylic tert-butyl group, while the Ga atom of 4b was coordinated to the α-C atom of the remaining alkynyl substituent. Dual hydrometallation of the corresponding pyrrolyl-trialkynylsilane resulted in compounds with different structures (5a, 5b) due to the delocalisation of the lone pair of electrons at nitrogen in the aromatic ring. One metal atom is coordinated to the α-C atom of the alkynyl group, and the other has close contact to a C-H bond of the pyrrole ring. The synthesis of 4b gave an unprecedented bicyclic by-product (6) which has a Ga-H-Ga 3c-2e bond. It was formally formed by hydrogallation of the trialkyne with the sesquihydride [H2Ga-CMe3]2[H-Ga(CMe3)2]2 and was also obtained by the selective reaction with this starting material.
用等摩尔量的H-M(CMe₃)₂（M = Al、Ga）对吡咯烷基官能化的三炔基硅烷H₈C₄N-Si(C≡C-CMe₃)₃进行氢金属化反应，生成了混合的烯基 - 二炔基硅烷（3a、3b），这些化合物在与硅原子相连的偕位位置含有一个路易斯酸性的Al或Ga原子，并通过胺N原子与路易斯酸性金属原子的强相互作用形成四元M-N-Si-C杂环。这种相互作用导致Si-N键同时变长和变弱。双重氢金属化反应得到了含有两个路易斯酸性金属原子的炔基 - 二烯基硅烷（4a、4b）。与其中一个路易斯酸性中心的Al-N和Ga-N相互作用再次导致形成M-N-Si-C杂环。4a中的第二个Al原子与乙烯基叔丁基的C-H键相互作用，而4b中的Ga原子则与剩余炔基取代基的α-C原子配位。由于芳环中氮上孤对电子的离域，相应的吡咯基 - 三炔基硅烷的双重氢金属化反应生成了具有不同结构的化合物（5a、5b）。一个金属原子与炔基的α-C原子配位，另一个则与吡咯环的C-H键紧密接触。4b的合成产生了一种前所未有的双环副产物（6），它具有一个Ga-H-Ga 3c-2e键。它是通过三炔与倍半氢化物[H₂Ga-CMe₃]₂[H-Ga(CMe₃)₂]₂进行氢镓化反应正式形成的，也可通过与该起始原料的选择性反应得到。
