Synthesis, Structure and Solution Studies on Mixed Aryl/Alkyl Lithium Zincates

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• 作者：Andrew J. Roberts ; Alan R. Kennedy ; Ross McLellan ; Stuart D. Robertson and Eva Hevia
• 刊名：European Journal of Inorganic Chemistry
• 出版年：2016
• 出版时间：October 2016
• 年：2016
• 卷：2016
• 期：29
• 页码：4752-4760
• 全文大小：2209K
• ISSN：1099-0682c

文摘

Novel homo- and heteroleptic lithium zincates have been prepared by cocomplexation reactions of Zn(CH₂SiMe₃)₂ and PhLi in low-polarity hydrocarbon solvents. X-ray crystallographic studies of products obtained by reacting the organometallic reagents in benzene or toluene yield the novel solvent-free solid-state arrangement [Li₄Zn₃Ph₅(CH₂SiMe₃)₅]_⋡ (1). Combining Zn(CH₂SiMe₃)₂ and PhLi in hexane in the presence of the polydentate N-donors PMDETA (N,N,N′,N′′,N′′-pentamethyldiethylenetriamine) or TMEDA (N,N,N′,N′-tetramethylethylenediamine) reveals monomeric heteroleptic [(PMDETA)LiZn(CH₂SiMe₃)₂Ph] (2) and homoleptic [(TMEDA)LiZn(CH₂SiMe₃)₃] (3), the result of a disproportionation process, respectively. NMR spectroscopic studies suggest that 2 and 3 retain their discrete contacted ion-pair solid-state structures in benzene solution. Variable-temperature NMR spectroscopic studies of 2 in [D₈]THF reveal a complex equilibrium also including [LiZn(CH₂SiMe₃)₃], [LiZn(CH₂SiMe₃)Ph₂] and [LiZnPh₃], an equilibrium process analogous to that of 1 in THF. This study further highlights the complexity of these reactions, which at first would appear simple.