Reissmann Matti, Schäfer André, Panisch Robin, Schmidtmann Marc, Bolte Michael, Müller Thomas
Institut für Chemie, Carl von Ossietzky Universität Oldenburg , Carl von Ossietzky Strasse 9-11, D-26129 Oldenburg, Federal Republic of Germany.
Inorg Chem. 2015 Mar 2;54(5):2393-402. doi: 10.1021/ic502968z. Epub 2015 Feb 9.
Five- and six-membered cyclic silylated onium ions of group 15 elements I were synthesized by intramolecular cyclization of transient silylium ions II. Silylium ions II were prepared by the hydride transfer reaction from silanes III using trityl cation as hydride acceptor. It was found that smaller ring systems could not be obtained by this approach. In these cases tritylphosphonium ions IV were isolated instead. Cations I and IV were isolated in the form of their tetrakispentafluorphenyl borates and characterized by multinuclear NMR spectroscopy and, in two cases, by X-ray diffraction analysis. Cyclic onium ions I showed no reactivity similar to that of isoelectronic intramolecular borane/phosphane frustrated Lewis pairs (FLPs). The results of DFT computations at the M05-2X level suggest that the strength of the newly formed Si-E linkage is the major reason for inertness of I[B(C6F5)4] versus molecular hydrogen.
通过瞬态硅鎓离子II的分子内环化反应合成了第15族元素I的五元及六元环状硅烷化鎓离子。硅鎓离子II是通过使用三苯甲基阳离子作为氢化物受体，由硅烷III进行氢化物转移反应制备的。发现通过这种方法无法获得更小的环系。在这些情况下，分离得到的是三苯甲基鏻离子IV。阳离子I和IV以其四（五氟苯基）硼酸盐的形式分离出来，并通过多核NMR光谱进行表征，在两个实例中还通过X射线衍射分析进行了表征。环状鎓离子I没有表现出与等电子分子内硼烷/膦受阻路易斯对（FLP）类似的反应活性。在M05-2X水平上进行的DFT计算结果表明，新形成的Si-E键的强度是I[B(C6F5)4]对分子氢惰性的主要原因。
