Hydride and Proton Transfer Reactions of Niobium-Bound Ligands. Synthetic and Thermodynamic Studies of Ketene, Enacyl, and Vinylketene Complexes
| العنوان: | Hydride and Proton Transfer Reactions of Niobium-Bound Ligands. Synthetic and Thermodynamic Studies of Ketene, Enacyl, and Vinylketene Complexes |
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| المؤلفون: | Azzam S. Hneihen, a Joseph W. Bruno, a Niladri Sarker, b and Gayle K. Schulte, a Margaret E. Kerr |
| المصدر: | Organometallics. 19:901-912 |
| بيانات النشر: | American Chemical Society (ACS), 2000. |
| سنة النشر: | 2000 |
| مصطلحات موضوعية: | Allylic rearrangement, Addition reaction, Tetrafluoroborate, Chemistry, Hydride, Ligand, Organic Chemistry, Substituent, Ketene, Medicinal chemistry, Inorganic Chemistry, chemistry.chemical_compound, Electrophile, Organic chemistry, Physical and Theoretical Chemistry |
| الوصف: | The niobium ketene complexes Cp‘2Nb(Cl)(OCC(R‘)CH2R) (1; Cp‘ = η5-C5H4SiMe3) exhibit complexation of the ketene CO bond. Upon treatment with an appropriate triarylcarbenium tetrafluoroborate they donate a hydride, a process constituting a useful synthesis of the η2-enacyl salts [Cp‘2Nb(Cl)(η2-OCC(R‘)CHR)][BF4] (3). The reactions involve transfer of a γ-hydride and are specific for the generation of the (E)-enacyl isomers; one derivative (3b, R‘ = Ph, R = Me) was the subject of an X-ray diffraction study. The cationic enacyls are strong electrophiles and are susceptible to conjugate addition reactions and [4 + 2] cycloadditions. If the substituent R contains allylic protons, the enacyl complex is also very acidic; treatment with a suitable base converts these enacyls to the η2(C,O)-vinylketene complexes Cp‘2Nb(Cl)(η2-OCC(R‘)CHCH2) (7). These compounds are relatively electron-rich, and the vinyl terminus constitutes a site for addition of electrophiles. The overall conversion of ketene ligand to vinylketene... |
| تدمد: | 1520-6041 0276-7333 |
| DOI: | 10.1021/om9907066 |
| URL الوصول: | https://explore.openaire.eu/search/publication?articleId=doi_________::8ed680354505ad1319ea6ed36558294b https://doi.org/10.1021/om9907066 |
| رقم الانضمام: | edsair.doi...........8ed680354505ad1319ea6ed36558294b |
| قاعدة البيانات: | OpenAIRE |
| تدمد: | 15206041 02767333 |
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| DOI: | 10.1021/om9907066 |