Reactions of Decamethylhafnocene with 1,3-Butadiynes: Formation of Hafnacyclocumulenes and C−H Activation at Pentamethylcyclopentadienyl Ligands

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• 作者：Torsten Beweries ; Vladimir V. Burlakov ; Stephan Peitz ; Marc A. Bach ; Perdita Arndt ; Wolfgang Baumann ; Anke Spannenberg ; Uwe Rosenthal
• 刊名：Organometallics
• 出版年：2007
• 出版时间：December 31, 2007
• 年：2007
• 卷：26
• 期：27
• 页码：6827 - 6831
• 全文大小：131K
• 年卷期：v.26,no.27(December 31, 2007)
• ISSN：1520-6041

文摘

The reduction of Cp*₂HfCl₂ with lithium in the presence of disubstituted butadiynes RCC−CCR (R = Ph, SiMe_3, t-Bu) in toluene leads, respectively, to the five-membered hafnacyclocumulene complexes Cp*₂Hf(η⁴-1,2,3,4-PhC₄Ph) (1-Hf) and Cp*₂Hf(η⁴-1,2,3,4-Me₃SiC₄SiMe₃) (2-Hf) and, in the case of 1,4-bis(tert-butyl)butadiyne by a 2-fold activation of the methyl groups of one pentamethylcyclopentadienyl ligand, to the complex Cp*Hf[−C(CCH-t-Bu)−CH(t-Bu)CH₂−η⁵-C₅Me₃−CH₂−] (3-Hf) containing a fulvene ligand that is coupled to the modified substrate (allenic subunit). The latter inserts 2 equiv of the isocyanide t-BuNC to give by coupling of the isocyanide molecules the complex Cp*Hf[−C(CCH-t-Bu)−CH(t-Bu)CH₂−η⁵-C₅Me₃−CH₂−C(N-t-Bu)−C(N-t-Bu)−] (4). The structures of complexes 3-Hf and 4 were determined by X-ray crystallography.