New diazasilaphosphetidines and their precursors

A series of aminosilanes (R'HN)(2)SiR2 have been prepared. In case of bulky substituents R' the aminolysis of Ph2SiCl2 stops at the (R'HN)ClSiPh2 stag e. Replacement of the Cl atom is achieved with LiNHR' which allows the synt hesis of mixed bisaminosilanes (R'HN)(R"HN)SiPh2. The X-ray structures of t hree of these compounds have been determined. There are no intermolecular N -H...N hydrogen bonds in these compounds in the solid state. Several 1,3,2, 4-diazaphosphetidines have been synthesized using bis(N-lithioamino)silanes and bis(N-lithioamino)phosphanes. Amongst these the heterocycle 18 possess es an almost planar four membered N2SiP ring system.