Combination of Spectroscopic Methods: In Situ NMR and UV/Vis Measurements To Understand the Formation of Group 4 Metallacyclopentanes from the Corresponding Metallacyclopropenes

详细信息    查看全文

• 作者：Torsten Beweries ; Christian Fischer ; Stephan Peitz ; Vladimir V. Burlakov^† ; ; Perdita Arndt ; Wolfgang Baumann ; Anke Spannenberg ; Detlef Heller* ; Uwe Rosenthal*
• 刊名：Journal of the American Chemical Society
• 出版年：2009
• 出版时间：April 1, 2009
• 年：2009
• 卷：131
• 期：12
• 页码：4463-4469
• 全文大小：242K
• 年卷期：v.131,no.12(April 1, 2009)
• ISSN：1520-5126

文摘

By reaction of the dichloride rac-(ebthi)HfCl₂ [ebthi = 1,2-ethylene-1,1′-bis(η⁵-tetrahydroindenyl)] with lithium in the presence of bis(trimethylsilyl)acetylene, the hafnacyclopropene rac-(ebthi)Hf(η²-Me₃SiC₂SiMe₃) (1-Hf) was obtained. The reaction of the blue-green complex 1-Hf with an excess of ethylene at room temperature leads by insertion of the olefin to the yellow-green hafnacyclopentene 2-Hf which is only stable in solution and eliminates the alkyne at 100 °C under ethylene to form the corresponding yellow hafnacyclopentane 3-Hf, which was characterized by X-ray crystal structure analysis. The reaction of 1-Hf to give stepwise via 2-Hf the complex 3-Hf was investigated in detail and compared to the formation and stability of the corresponding zirconacyclopropene 1-Zr, zirconacyclopentene 2-Zr, and zirconacyclopentane 3-Zr. Moreover, the reaction of the titanocene alkyne complex 1-Ti with ethylene was studied. For investigating the reaction behavior of the alkyne complexes 1-M, NMR spectroscopy was used and the results were compared with UV/vis spectroscopy, suggesting the existence of a bis-π-complex prior to the formation of the hafnacyclopentene 2-Hf.