Synthesis and characterization of tert-butylcyclopentadienyl derivatives of hafnium

Article abstract of DOI:10.1016/0022-328X(95)06020-W

Reaction of Si(C₅H₃-1,3-^tBu₂)Me₃ with HfCl₄ in toluene or hexane at room temperature afforded the new trichloro monocyclopentadienyl derivatives [Hf(η⁵-C₅H₃-1,3-^tBu₂)Cl₃] (1). Treatment of [Hf(η⁵-C₅H₃-1,3-^tBu₂)Cl₃] with the appropriate alkylating reagent in hexane gave the mono[1,3-di(tert-butyl)cyclopentadienyl] trialkyl hafnium complexes [Hf(η⁵-C₅H₃-1,3-^tBu₂)R₃] [R = CH₃ (2), CH₂C₆H₅ (3), CH₂Si(CH₃)₃ (4)]. When [Hf(η⁵-C₅H₃-1,3-^tBu₂)Cl₃] reacts with 1 equivalent of TlCp in toluene at room temperature the mixed dicyclopentadienyl complex [Hf(η⁵-C₅H₃-1,3-^tBu₂)(η⁵-C₅H₅)Cl₂] (5) was isolated in almost quantitative yield. Reaction of 5 with LiMe led to the dimethyl complex [Hf(η⁵-C₅H₃-1,3-^tBu₂)(η⁵-C₅H₅)(CH₃)₂] (6). However, the analogous reaction of a hexane solution of 5 with MgBz₂ · 2THF in the presence of traces of water afforded the μ oxo derivative [{Hf(η⁵-C₅H₃-1,3-^tBu₂)(η⁵-C₅H₅)(CH₂C₆H₅)}₂( μ-O)](7).