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

Treatment of [Cp<sub>2</sub>Ln(μ-Me)]<sub>2</sub> and Cp<sub>2</sub>LnPh with PhRCCN<sup><i>t</i></sup>Bu gives the insertion products Cp<sub>2</sub>Ln[<sup><i>t</i></sup>BuNC(R′)CRPh] (R = Ph, R′ = Me, Ln = Y (<b>1-Y</b>), Er (<b>1-Er</b>), Yb (<b>1-Yb</b>); R = Ph, R′ = Ph, Ln = Y (<b>2-Y</b>), Er (<b>2-Er</b>), Yb (<b>2-Yb</b>); R = H, R′= Me, Ln = Y (<b>3-Y</b>), Er (<b>3-Er</b>), Yb (<b>3-Yb</b>); R = H, R′ = Ph, Ln = Y (<b>4-Y</b>), Er (<b>4-Er</b>), Yb (<b>4-Yb</b>)), 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.