β-Hydrogen-Containing Zirconium Alkyls with the Doubly-Bridged Bis(dimethylsilanediyl)dicyclopentadienyl Ligand. X-ray Molecular Structures of [Zr{(SiMe2)2(η5-C5H3)2}ClEt] and [Zr{(SiMe2)2(η5-C5H3)2}Et]2(μ-CH2CH2)

Abstract

Alkylation of [Zr(CpSi2Cp)Cl2] (CpSi2Cp = (η5-C5H3)2[Si(CH3)2]2 with 1 equiv of RMgCl in THF at 10 °C gave the monoalkylated complexes [Zr(CpSi2Cp)ClR] (R = Et, n-Pr, i-Pr) in 80% yield, the isopropyl complex isomerizing to the n-propyl derivative above 10 °C. Addition of a second equivalent or an excess amount of the akylating agent resulted in the formation of the dialkyl compounds [Zr(CpSi2Cp)R2] (R = Et, n-Pr). Hydrolysis of [Zr(CpSi2Cp)ClR] led to the μ-oxo dinuclear complex [{Zr(CpSi2Cp)Cl}2(μ-O)]. Thermal decomposition of THF solutions of [Zr(CpSi2Cp)ClR] takes place with the evolution of an equimolar amount of alkane and alkene and the formation of [Zr(CpSi2Cp)Cl2] and an unidentified residue. Formation of [Zr(CpSi2Cp)Et2] is always accompanied by decomposition with the evolution of ethane to give [{Zr(CpSi2Cp)Et}2(μ-CH2CH2)] in 70% yield. A similar behavior was observed for [Zr(CpSi2Cp)(n-Pr)2]. All of the compounds were characterized by elemental analysis and NMR spectroscopy, and the molecular ...