FROM MONOMERIC AND DIMERIC LIF ADDUCTS TO FREE IMINOSILANE

The mono-lithium derivatives of the silylamines R(CMe(3))(2)SiNH2 form dimers [R(CMe(3))(2)SiNHLi . TMEDA](2) (R = Ph (1), Me(2)). 1 and 2 react with (CMe(3))(2)SiF2 to give R(CMe(3))(2)Si-NH-Si(CMe(3))(2)F (R = Ph(3), R = Me (4). A trisilazane 6 (R = Ph) is obtained as a by-product. Ph(CMe(3))(2)Si-NH-Si(CMe(3))(2)Ph (5) is formed in the reaction of 1 with Ph(CMe(3))(2)SiF. The lithium derivative of 3 crystallizes from thf as a momomeric LiF-adduct of an iminosilane (Ph(CMe(3))(2)Si-N=Si(CMe(3))(2)FLi(thf)(3), 7). In the presence of tmeda a salt like amid is isolated ([Ph(CMe(3))(2)SiNSi(CMe(3))(2)F](-)-[Li(tmeda)(2)](+), 8). The lithium derivative of 4 forms a dimer ([Me(CMe(3))(2)SiNLi-FSi(CMe(3))(2)](2), 9) associated via Li-F contacts. 9 adds tmeda with formation of Me(CMe(3))(2)SiNLi(tmeda)Si(CMe(3))(2)F (10). In 12-crown-4 the salt [Me(CMe(3))(2)SiNSiF(CMe(3))(2)](-)[Li(12-crown-(4))(2)](+) (11) results from 9. 7 reacts with Me(3)SiCl in the presence of thf by a fluorine/chlorine exchange. The free iminosilane 12 is thus obtained. The crystal structures of 7, 8 and 9 have been determined.