Aminochlorosilane, lithiated

After a fluorine/chlorine exchange, a lithiated aminochlorosilane is obtained. Lithium is bound to nitrogen, the strongest Lewis base in this compound. The SiN bond is enlarged (164.2 pm) and the SiNC angle of 138.7° shows the character of the amine.17,18... 

Lithiated aminochlorosilanes are obtained with MejSiCl by a fluorine-chlorine exchange, for example 3 (Figure 2) [2], LiCl is easily eliminated. Monomeric or dimeric iminosilanes are formed [3,4]. 

Summary Lithiated aminofluorosilanes can often be regarded as LiF adducts of iminosilanes on account of their structures [1], They are suitable precursors to iminosilanes after fluorine-chlorine exchange followed by elimination of lithium chloride [1,2]. This synthesis shows the following features (a) the method is a general one in the sense that it can be applied to differently substituted aminosilanes (b) the iminosilanes are obtained, either as THF adducts or as free imines in good yield (c) the tedious and sometimes complicated synthesis of aminochlorosilanes as precursors is avoided, since the fluorine-chlorine exchange takes place in one step in the lithium derivative. 

Summary One of the remarkable features of lithiated aminofluorosilanes and dilithiated diaminofluorosilanes with bulky substituents is that they do not undergo the expected substitution on treatment with MesSiCl on the nitrogen atom but instead on the silicon atom to give lithium derivatives of aminochlorosilanes. These salts are far less stable than the analogous fluorine compounds. LiCl elimination leads to the formation of iminosilanes and monomeric and dimeric silaamidides. 

Another stable silanimine (83) was obtained soon thereafter by thermal elimination of LiCl and of a molecule of THF from a solvated lithiated aminochlorosilane (equation 157)330. 

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See also in sourсe #XX -- [ ]

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