Chemistry of Dienyl Anions. IV. Geometry of Pentadienyl Anions in Solution and in the Solid State Determined by Regioselective Trimethylsilylation and NMR
| Autor: | Michihide Yamauchi, Hajime Yasuda, Akira Nakamura, Yasuo Ohnuma |
|---|---|
| Rok vydání: | 1981 |
| Předmět: | |
| Zdroj: | Bulletin of the Chemical Society of Japan. 54:1481-1491 |
| ISSN: | 1348-0634 0009-2673 |
| DOI: | 10.1246/bcsj.54.1481 |
| Popis: | The configurational analysis of a series of alkyl substituted pentadienyl anions in THF was examined by trimethylsilylation and from the variable temperature 1H- and 13C-NMR spectra. Potassium pentadienide, -2-methylpentadienide or -2,4-dimethylpentadienide produced preferentially (Z)-2,4-pentadienyltrimethylsilane or its methyl substituted analogues to indicate that these compounds have the “U”-shaped structure in solution. By contrast, trimethylsilylation of potassium pentadienide and -2-methylpentadienide in the crystalline state produced the (E)- and the (E),(Z)-isomers, respectively, suggesting that the geometry is drastically changed to the “W”- or “S”-shaped by the medium effect. The W-shaped structure of potassium 3-methylpentadienide in THF and in the solid state is exceptional. Geometry of trapped products of potassium cycloheptadienide and -cyclooctadienide is also (Z) but the silylation occurred on the central carbon in contrast to the terminal silylation seen for the open-chain pentadienides.... |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|