Reactivity of SiMe2H Substituents in Permethylated Titanocene Complexes: Dehydrocoupling and Ethene Hydrosilylation
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- 作者：Michal Horá ; č ; ek ; Jiř ; í ; Pinkas ; Ró ; bert Gyepes ; Jiř ; í ; Kubiš ; ta ; Karel Mach
- 刊名：Organometallics
- 出版年：2008
- 出版时间：June 9, 2008
- 年：2008
- 卷：27
- 期：11
- 页码：2635 - 2642
- 全文大小：182K
- 年卷期：v.27,no.11(June 9, 2008)
- ISSN：1520-6041
文摘
The complex [TiCl2{η5-C5Me4(SiMe2H)}2] (3) was prepared by reacting the lithium salt of 2,3,4,5-tetramethyl-1-(dimethylsilyl)cyclopenta-2,4-diene (1) with [TiCl3(THF)3] followed by chlorination of the formed [TiCl{η5-C5Me4(SiMe2H)}2] (2) with PbCl2. The reduction of 3 with excess magnesium in THF in the presence of excess bis(trimethylsilyl)ethyne (btmse) afforded the bivalent metal ansa disilylene complex with π-coordinated btmse [Ti{η5-C5Me4(SiMe2)}2(η2-btmse)] (4). The dehydrocoupling of the SiMe2H groups was accompanied by hydrogen transfer to the free btmse. Analogous reduction of 3 with magnesium in the presence of ethene gave a mixture of titanocene [Ti{η5-C5Me4(SiMe2Et)}2] (5) and its ethene complex [Ti{η5-C5Me4(SiMe2Et)}2(η2-C2H4)] (6). The latter complex is however unstable in this mixture and rearranges with evolution of ethane to [Ti{η5-C5Me4(SiMe2Et)}{η5:η2-C5Me4(SiMe2CH
CH2)}] (7), which has its vinyl group attached by π-coordination to Ti(II). The chlorination of 4 by PbCl2 yields ansa-[TiCl2{η5-C5Me4(SiMe2)}2] (8), liberating the btmse ligand. Complex 8 is reduced with a half-equivalent of Mg to give ansa-[TiCl{η5-C5Me4(SiMe2)}2] (9). Compounds 5, 6, and 7 were identified by 1H, 13C, and 29Si NMR spectra. The crystal structures of complexes 3, 4, and 9 have been determined by X-ray crystallography.
CH2)}] (7), which has its vinyl group attached by π-coordination to Ti(II). The chlorination of 4 by PbCl2 yields ansa-[TiCl2{η5-C5Me4(SiMe2)}2] (8), liberating the btmse ligand. Complex 8 is reduced with a half-equivalent of Mg to give ansa-[TiCl{η5-C5Me4(SiMe2)}2] (9). Compounds 5, 6, and 7 were identified by 1H, 13C, and 29Si NMR spectra. The crystal structures of complexes 3, 4, and 9 have been determined by X-ray crystallography.