title: A Bis(silylene)-Substituted ortho-Carborane as a Superior Ligand in the Nickel-Catalyzed Amination of Arenes.
abstract: The synthesis and structure of the first 1,2-bis(NHSi)-substituted ortho-carborane [(LSi:)C]2 B10 H10 (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]NiBr2 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]NiBr2 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 %).
authors.affiliation: Technische Universität Berlin, Department of Chemistry: Metalorganics and Inorganic Materials, Sekr. C2, Strasse des 17. Juni 135, 10623, Berlin, Germany.
authors.forename: Yu-Peng
authors.initials: YP
authors.lastname: Zhou
authors.affiliation: Technische Universität Berlin, Department of Chemistry: Metalorganics and Inorganic Materials, Sekr. C2, Strasse des 17. Juni 135, 10623, Berlin, Germany.
authors.forename: Saeed
authors.initials: S
authors.lastname: Raoufmoghaddam
authors.affiliation: Department of Inorganic and Analytical Chemistry, Budapest University of Technology and Economics, Szent Gellért tér 4, 1111, Budapest, Hungary.
authors.forename: Tibor
authors.initials: T
authors.lastname: Szilvási
authors.affiliation: Technische Universität Berlin, Department of Chemistry: Metalorganics and Inorganic Materials, Sekr. C2, Strasse des 17. Juni 135, 10623, Berlin, Germany. matthias.driess@tu-berlin.de.
authors.forename: Matthias
authors.identifier: 0000-0002-9873-4103
authors.initials: M
authors.lastname: Driess
keywords: N-heterocyclic silylenes; homogeneous catalysis; ligand design; nickel; o-carboranes