Untypical Regioselectivity of Carbon Dioxide Coupling with Titanocene Complexes of Phenyl(trimethylsilyl)acetylene by Using the meso-1,2-Ethylene-1,1′-bis(η5-tetrahydroindenyl) Ligand System
✍ Scribed by Dominique Thomas; Normen Peulecke; Vladimir V. Burlakov; Wolfgang Baumann; Anke Spannenberg; Rhett Kempe; Uwe Rosenthal
- Publisher
- John Wiley and Sons
- Year
- 1998
- Tongue
- English
- Weight
- 383 KB
- Volume
- 1998
- Category
- Article
- ISSN
- 1434-1948
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✦ Synopsis
The reaction of [meso-(ebthi)TiCl 2 ] [ebthi = 1,2-ethylene-6a. In the analogous reactions of the complexes [(thi) 2 Ti(η 2 -PhC 2 SiMe 3 )] (thi = η 5 -tetrahydroindenyl), [rac-(ebthi)Ti(η 2 -1,1Ј-bis(η 5 -tetrahydroindenyl)] with magnesium in the presence of the alkynes Me 3 SiCϵCSiMe 3 and PhCϵCSiMe 3 PhC 2 SiMe 3 )], and [Cp* 2 Ti(η 2 -PhC 2 SiMe 3 )] with carbon dioxide typical regioselectivity (insertion into the M-CSi resulted in the formation of the complexes [meso-(ebthi)Ti(η 2 -Me 3 SiC 2 SiMe 3 )] ( 1) and [meso-(ebthi)Ti(η 2 -bond of the titanacyclopropene) was observed, yielding the β-silyl-substituted titanafuranones 7, 8a, and 9. These results PhC 2 SiMe 3 )] (2a and 2b), which were isolated and then characterized by their NMR spectra. Due to incomplete show that insertion of carbon dioxide into the M-C bond of the titanacyclopropene structure of the alkynemetallocene reduction the Ti III complex [meso-(ebthi)Ti(THF)Cl] (3) was also obtained as a by-product of these reactions. By insertion complexes is governed by the substitution pattern of the alkyne and the steric enviroment around the metal center. into the Ti-CPh bond carbon dioxide reacted with the titanacyclopropene structure of the alkyne complex [meso-The complexes 3, 6a, and 7 were investigated by X-ray crystal structure analysis. (ebthi)Ti(η 2 -PhC 2 SiMe 3 )] (2a), with untypical regioselectivity to yield the α-silyl-substituted meso-(ebthi)titanafuranone