Synthetic Aspects of (C₅H₄SiMe₃)₃Ln Rare-Earth Chemistry: Formation of (C₅H₄SiMe₃)₃Lu via [(C₅H₄SiMe₃)₂Ln]⁺ Metallocene\nPrecursors

Abstract

New analogues of Cp′₃Ln (Cp′ = C₅H₄SiMe₃, Ln =\nrare earth) complexes have been\nsynthesized with the largest and smallest lanthanides, La and Lu.\nDue to the smaller size of Lu, the reaction of LuCl₃ with\n3 equiv of KCp′ produced only traces of Cp′₃Lu, yielding [Cp′₂Lu­(μ-Cl)]₂ as\nthe major product. An alternative route was developed in which [Cp′₂Lu­(μ-Cl)]₂ reacts with (C₃H₅)­MgCl to form the tetrameric allyl complex [Cp′₂Lu­(μ-η¹:η¹-C₃H₅)]₄. The allyl complex reacts with [HNEt₃]­[BPh₄] to generate [Cp′₂Lu­(THF)₂]­[BPh₄], which reacts with KCp′ to produce\nCp′₃Lu in good yield. The reaction of LaCl₃ with 3 equiv of KCp′ in Et₂O gave the unsolvated\nCp′₃La, while the same reaction in rigorously dry\nTHF gave solvated Cp′₃La­(THF). The reaction of LaCl₃ and KCp′ in improperly dried THF gave the mixed-ligand\ncomplex Cp′₂CpLa­(THF) (Cp = C₅H₅), rather than the expected hydrolysis product, [Cp′₂La­(μ-OH)]₂.