IS(2)SI(LI)-P(LI)SIR(3) (IS=2,4,6-(PR3C6H 2)-PR-I) - THE FIRST LITHIUMSILANIDYL-LITHIUMPHOSPHANIDES AND THEIR TRANSFORMATION INTO DISILAPHOSPHIRANES AND NOVEL MERCURIOPHOSPHANES

Upon addition of two mol equivalents lithium metal to the Si=P bond of the silylidenephosphanes (''phosphasilenes'') Is(2)Si=P((SiPr3)-Pr-i) and Is(2)Si=P(SiPh(2)Me) (Is=2,4,6(i)Pr(3)C(6)H(2)) in tetrahydrofura ne, the corresponding lithiumsilanidyl-lithiumsilylphosphanides are fo rmed, which have been isolated as pale yellow solids; each Li center i s solvated by two tetrahydrofurane molecules. The constitution of thes e compounds is established by multi nuclei NMR spectroscopy and deriva tization reactions with water, deuteriumoxide, dichlorodimethylsilane, and tert-butylmercuriochloride, respectively. The reaction with dichl orodimethylsilane yields, via cyclocondensation reaction and eliminati on of lithiumchloride, the first disilaphosphacyclopropane derivatives , and the reaction with tert-butylmercuriochloride gives, under loss o f the triorganosilyl group at phosphorus and via rearrangement process es, an unusual P, P-dimercuriosilylphosphane; the latter reacts with t ert-butyl-mercuriochloride and mercuriodichloride in the molar ratio o f 2:1:1 to give an molecular aggregate bearing a P2Hg6Cl3 framework, w hich can be regared as an Lewis-acid base complex of a mercuriophospha ne chelate ligand and mercuriodichloride.