Access to Silicon(II)– and Germanium(II)–Indium Compounds

Despite the remarkable ability of N-heterocyclic silylene to act as a Lewis base and form stable Lewis adducts with group 13 elements such as boron, aluminum, and gallium, there has been no such comparable investigation with indium and the realization of a stable silylene–indium complex has still remained elusive. Similarly, a germylene–indium complex is also presently unknown. We describe herein the reactions of [PhC­(NtBu)2SiN­(SiMe3)2] (1) and [PhC­(NtBu)2GeN­(SiMe3)2] (4) with InCl3 and InBr3 that have resulted in the first silylene–indium complexes, [PhC­(NtBu)2Si­{N­(SiMe3)2}→InCl3] (2) and [PhC­(NtBu)2Si­{N­(SiMe3)2}→InBr3] (3), as well as the first germylene–indium complexes, [PhC­(NtBu)2Ge­{N­(SiMe3)2}→InCl3] (5) and [PhC­(NtBu)2Ge­{N­(SiMe3)2}→InBr3] (6). The solid-state structures of all species have been validated by single-crystal X-ray diffraction studies. Note that 5 and 6 are the first structurally characterized organometallic compounds that feature a Ge–In single bond (apart from the compounds in Zintl phases). Theoretical calculations reveal that the Si­(II)→In bonds in 2 and 3 and the Ge­(II)→In bonds in 5 and 6 are dative bonds.尽管氮杂环硅烯（N-heterocyclic silylene）作为路易斯碱（Lewis base）展现出优异性能，可与硼、铝、镓等第13族元素（group 13 elements）形成稳定的路易斯加合物（Lewis adducts），但目前尚无针对铟的同类可比研究，且稳定的硅烯-铟配合物（silylene–indium complex）仍难以获得。同理，目前也尚未见锗烯-铟配合物（germylene–indium complex）的相关报道。本文报道了配体[PhC(NtBu)2SiN(SiMe3)2]（1）与[PhC(NtBu)2GeN(SiMe3)2]（4）分别与InCl3、InBr3的反应，成功得到首例硅烯-铟配合物[PhC(NtBu)2Si{N(SiMe3)2}→InCl3]（2）与[PhC(NtBu)2Si{N(SiMe3)2}→InBr3]（3），以及首例锗烯-铟配合物[PhC(NtBu)2Ge{N(SiMe3)2}→InCl3]（5）与[PhC(NtBu)2Ge{N(SiMe3)2}→InBr3]（6）。所有产物的固态结构均通过单晶X射线衍射（single-crystal X-ray diffraction）研究得到确证。值得注意的是，5和6是首例经结构表征的含有Ge-In单键的有机金属化合物（津特耳相（Zintl phases）化合物除外）。理论计算表明，2和3中的Si(II)→In键以及5和6中的Ge(II)→In键均为配位键（dative bonds）。