γ-Deprotonation of Anionic Bis(trimethylsilyl)amidolanthanide Complexes with a Countered [(Tp^Me2)₂Ln]⁺ Cation

TpMe2LnCl2 (1) reacts with 2 equiv of KN(SiMe3)2 in tetrahydrofuran at room temperature to yield the ligand redistribution/γ-deprotonation products [(TpMe2)2Ln]+[((Me3Si)2N)2Ln(CH2)SiMe2N(SiMe3)]− [Ln = Er (2), Y (3)]. Complex 2 can also be obtained by reacting [(Me3Si)2N]2ErCl with KTpMe2. However, 1 reacts with 1.5 and 1 equiv of KN(SiMe3)2 to yield [(TpMe2)2Er]+[((Me3Si)2N)3ErCl]− (4) and [(TpMe2)2Er]+{[(Me3Si)2N)TpMe2ErCl]2(μ-Cl)2K}− (5), respectively. Furthermore, it is found that 2 reacts with 2 equiv of CyNCNCy (Cy = cyclohexyl) to give the tandem HN(SiMe3)2 elimination and Ln−C insertion product (TpMe2)Er[(CyN)2CCH2SiMe2N(SiMe3)] (6) in 71% isolated yield. The results reveal that the γ-deprotonation degree of advancement increases with an increase of the steric hindrance around the central metal ion. All new complexes have been characterized by elemental analysis and spectroscopic properties, and their solid-state structures have also been determined through single-crystal X-ray diffraction analysis.