Insertion of Ketenimines into the Ln−C σ-Bond of Organolanthanides: A New Strategy for Synthesis of Lanthanide 1-Azaallyl Complexes

Treatment of [Cp₂Ln(μ-Me)]₂ and Cp₂LnPh with PhRCCN^tBu gives the insertion products Cp₂Ln[^tBuNC(R′)CRPh] (R = Ph, R′ = Me, Ln = Y (1-Y), Er (1-Er), Yb (1-Yb); R = Ph, R′ = Ph, Ln = Y (2-Y), Er (2-Er), Yb (2-Yb); R = H, R′= Me, Ln = Y (3-Y), Er (3-Er), Yb (3-Yb); R = H, R′ = Ph, Ln = Y (4-Y), Er (4-Er), Yb (4-Yb)), which represents the first example of ketenimine insertion into a lanthanide−carbon bond and provides an efficient method for the synthesis of organometallic complexes with the 1-azaallyl ligands. It is found that an excess of ketenimine does not affect the nature of the final complexes, with only a monoinsertion product being observed. All these complexes are characterized by elemental analysis and spectroscopic properties. The structures of these complexes have also been determined through X-ray single-crystal diffraction analysis, revealing a novel bonding mode of aryl-substituted azaallyls to a metal.