A Bis(silylene)‐Substituted ortho ‐Carborane as a Superior Ligand in the Nickel‐Catalyzed Amination of Arenes

The synthesis and structure of the first 1,2‐bis(NHSi)‐substituted ortho ‐carborane [(LSi:)C] 2 B 10 H 10 (termed SiCCSi) is reported (NHSi= N ‐heterocyclic silylene; L=PhC(NtBu) 2 ). Its suitability to serve as a reliable bis(silylene) chelating ligand for transition metals is demonstrated by the formation of [SiCCSi]NiBr 2 and [SiCCSi]Ni(CO) 2 complexes. The CO stretching vibration modes of the latter indicate that the Si II atoms in the SiCCSi ligand are even stronger σ donors than the P III atoms in phosphines and C II atoms in N ‐heterocyclic carbene (NHC) ligands. Moreover, the strong donor character of the [SiCCSi] ligand enables [SiCCSi]NiBr 2 to act as an outstanding precatalyst (0.5 mol % loading) in the catalytic aminations of arenes, surpassing the activity of previously known molecular Ni‐based precatalysts (1–10 mol %).