Alkyl Alkyne Mono((trimethylsilyl)cyclopentadienyl) Niobium Complexes. Synthesis and Chemical Behavior in Insertion Processes. X-ray Crystal Structures of [NbCp‘(CH2SiMe3)2(Me3SiCCSiMe3)] and [NbCp‘(NAr){η4-CH(SiMe3)C(SiMe3)C(CH2SiMe3)CH(SiMe3)}], (Cp‘ = η5-C5H4SiMe3, Ar = 2,6-Me2C6H3). DFT Studies of the Model Complexes [Nb(η5-C5H5)R2(HCCH)] (R = Cl, Me)
| Autor: | Manuel Gómez, Diego Del Rio, Avelino Martín, Agustin Galindo, Pilar Gómez-Sal, Fernando Sánchez |
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| Rok vydání: | 2001 |
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| Zdroj: | Organometallics. 21:293-304 |
| ISSN: | 1520-6041 0276-7333 |
| DOI: | 10.1021/om010521a |
| Popis: | The dichloro niobium complex [NbCp‘Cl2(R‘CCR‘)] (Cp‘ = η5-C5H4SiMe3; R‘ = SiMe3; 1) can be obtained by reduction of NbCp‘Cl4 with excess of aluminum in the presence of 1 equiv of bis(trimethylsilyl)acetylene. The dialkyl derivatives [NbCp‘R2(R‘CCR‘)] (Cp‘ = η5-C5H4SiMe3; R‘ = SiMe3; R = Me (2), CH2SiMe3 (3), CH2CMe3 (4), CH2C6H5 (5)) were obtained by treating 1 with the stoichiometric amounts of the appropriate alkylating reagents. Reactions of the dialkyl alkyne complexes [NbCp‘R2(R‘CCR‘)] (2−5) with 1 equiv of 2,6-Me2C6H3NC in C6D6 resulted in migration of only one of the two alkyl groups to give the alkyl alkyne η2-iminoacyl complexes [NbCp‘R{η2-C(R)NAr}(R‘CCR‘)] (Cp‘ = η5-C5H4SiMe3; R‘ = SiMe3; Ar = 2,6-Me2C6H3; R = Me (6), CH2SiMe3 (7), CH2CMe3 (8)). However, when hexane solutions of the dialkylated complexes 2 and 3 were treated with 1 equiv of isocyanide at 40−50 °C (2) and 80 °C (3), respectively, the imido niobacyclopent-3-ene [NbCp‘(NAr){η4-CH(SiMe3)C(SiMe3)C(Me)CH2}] (9) and the imido niobacycl... |
| Databáze: | OpenAIRE |
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