back to
 all Research Projects,
|
 Research Projects of Physics,
|
 this Research Project
|
|
all Research Projects,
|
Research Projects of Physics,
|
this Research Project
|
Treatment of dichloromethyl-tris(trimethylsilyl)silane (1) with organolithium compounds leads to the formation of bis(trimethylsilyl)silanes 2. This process, which will be discussed in detail, involves transient silenes as intermediates, which are trapped by excess organolithium reagent to give 2 as the final products [1].
 |
When organolithium derivatives are used in this reaction, bearing substituents R which due to their bulkiness or by intramolecular donor acceptor interactions provide a sufficient stabilization to the Si=C system, the reaction can be stopped at that stage and indefinitely stable silenes can be isolated and characterized. Thus, kinetically stabilized silenes were prepared and characterized by the formation of several resultant products. The concept proved to be particularly successful in the synthesis of intramolecularly amine-stabilized silenes.
In very straightforward one-pot processes the compounds 3-6 were obtained by the reaction of dichloromethyl-tris(trimethylsilyl)silane with two molar equivalents of 2- (dimethylaminomethyl)phenyllithium, 8-dimethylamino-1-naphthyllithium or 2,6- bis(dimethylaminomethyl)phenyllithium, respectively, in yields between 58 % and 80 % as colorless (3, 6) or yellow (4) crystals. 3-6 are indefinitely stable at room temperature, and also heating for a short time up to 140 °C leaves the compounds unchanged.
 |
The results of X-ray structural analyses clearly characterize 3-5 as intramolecularly amine-stabilized silenes with four-coordinate silicon centers. In 5 only one dimethylamino group of the 2,6-bis(dimethylaminomethyl)phenyl ligand is coordinated to the electrophilic silicon atom. The structural parameters of the silenes 3-5 will be discussed and compared with the available data of known kinetically stabilized Si=Csystems.
 |
The chemical behavior of 3-5 agrees with our notion on an ylide-like nature of the three donor-stabilized silenes. The N¨Si coordination dramatically reduces the reactivity of the Si=C derivatives and prevents dimerization. Treatment of 3-5 with water or alcohols affords silanols or alkoxysilanes, respectively. Results of the reaction of 3-5 with alkyl halides and carbonyl compounds will be presented.
[1] K. Schmohl, H. Reinke, H. Oehme, Eur.J.Inorg.Chem. 2001, 481.
|
all Research Projects,
|
Research Projects of Physics,
|
this Research Project
|