Synthesis and characterization of tert-butylcyclopentadienyl derivatives of hafnium

Abstract

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).