- SYNTHESE UND DYNAMISCHES VERHALTEN VON EINIGEN PENTAMETHYLCYCLOPENTADIENYLSILANEN UND -GERMANEN
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By reaction of pentamethylcyclopentadienyllithium (pcpLi) with the corresponding chloro-silanes and -germanes, the h1-pcp-silanes and -germanes I-IX are synthesized.Nucleophilic substitution reactions at the pcp-chlorogermane VII lead to the h1-pcp-germanes X-XIII.The activation parameters for the sigmatropic rearrangements in these compounds have been evaluated from the 1H DNMR data.They show little incluence of the remaining ligands at silicon or germanium on the speed of these dynamic processes.
- Jutzi, Peter,Saleske, Hartmut,Buehl, Dittmar,Grohe, Hildegard
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- On the regioselectivity of alkylation of the (trimethylsilyl) tetramethylcyclopentadienide anion. A new approach to the synthesis of 1,2,3,4-tetramethylfulvene
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The regioselectivity of alkylation of lithium (trimethylsilyl) tetramethylcyclopentadienide C5Me4SiMe3 -Li+ was studied by 1H and 13C NMR spectroscopy using its reactions with MeI, MeOTs, ClCH2CH 2Br, and ClCH2CH2I in different solvents as representative examples. Sterically non-hindered MeI and MeOTs presumably attack the C atom bonded to the silyl group giving 1,2,3,4,5- pentamethylcyclopentadienylsilane. For bulkier alkyl halides, such as ClCH 2CH2Br and ClCH2CH2I, the regioselectivity of alkylation changes to form preferentially gem-dialkyl-substituted cyclopentadienes. The reaction of C5Me 4SiMe3 -Li+ with formaldehyde affords 1,2,3,4-tetramethylfulvene in a high yield, providing an alternative synthetic approach to a number of ω-functionalized peralkylated cyclopentadienes. The quantum-chemical calculations of the C5Me 4SiMe3 - anion by the RHF and DFT (RMPW1PW91) methods in the valence-split 6-311+G(d,p) basis set are in good agreement with the experimental data.
- Krut'ko,Borzov,Veksler
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p. 2182 - 2186
(2007/10/03)
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- Facile Reduction of Organometallic Halides with Bis(pentamethylcyclopentadienyl)ytterbium and the X-Ray Structure of (C5Me5)2YbCl(THF)
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Reduction of (C5H5)2MCl2 (M=Ti, Zr) and TiCl4 with one equiv. of (C5Me5)2Yb(THF)2 gave rise to the formation of 2 and TiCl3(THF)3, respectively, together with (C5Me5)2YbCl(THF).The molecular structure of (C5Me5)2YbCl(THF) has been determined by the X-ray analysis.The reaction of (C5Me5)2Yb(THF)2 with Me3SiCl yielded a mixture composed of n and C5Me5(CH2)4OSiMe3.
- Yasuda, Hajime,Yamamoto, Hitoshi,Yokota, Kiyohiko,Nakamura, Akira
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p. 1309 - 1312
(2007/10/02)
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- (C5Me5)SiMe3 as a mild and effective reagent for transfer of the C5Me5 ring: an improved route to monopentamethylcyclopentadienyl trihalides of the group 4 elements
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The reaction between (C5Me5)SiMe3 and group 4 element tetrahalides MX4 (M=Ti, X=Cl, Br, I; M=Zr and Hf, X=Cl) gives the corresponding (η5-C5Me5)MX3 derivatives in nearly quantitative yields in a one-step procedure without the need for further purification.
- Llinas, Gerardo Hidalgo,Mena, Miguel,Palacios, Federico,Royo, Pascual,Serrano, Ricardo
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