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(N<i>t</i>Bu)₂SiN­(SiMe₃)₂] (<b>1</b>) and [PhC­(N<i>t</i>Bu)₂GeN­(SiMe₃)₂] (<b>4</b>) with InCl₃ and InBr₃ that have resulted in the first silylene–indium complexes, [PhC­(N<i>t</i>Bu)₂Si­{N­(SiMe₃)₂}→InCl₃] (<b>2</b>) and [PhC­(N<i>t</i>Bu)₂Si­{N­(SiMe₃)₂}→InBr₃] (<b>3</b>), as well as the first germylene–indium complexes, [PhC­(N<i>t</i>Bu)₂Ge­{N­(SiMe₃)₂}→InCl₃] (<b>5</b>) and [PhC­(N<i>t</i>Bu)₂Ge­{N­(SiMe₃)₂}→InBr₃] (<b>6</b>). The solid-state structures of all species have been validated by single-crystal X-ray diffraction studies. Note that <b>5</b> and <b>6</b> 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 <b>2</b> and <b>3</b> and the Ge­(II)→In bonds in <b>5</b> and <b>6</b> are dative bonds