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.