Syntheses and structures of an unsolvated tetrakisimidophosphate {Li-3[P(NBut)(3)(NSiMe3)]}(2) and the face-sharing double-cubane {Li-2(THF)[P(O)(NBut)(2)(NHBut)]}(2)

The treatment of Me3SiN=P(NHBut)(3) with three equivalents of LiBun in toluene produces {Li-3[P(NBut)(3)(NSiMe3)]}(2) comprised of a Li6N6 cyclic ladder capped on the two hexagonal faces by mu(3)-PNSiMe3 groups; the corresponding reaction of O=P(NHBut)(3) yields the face-sharing double-cubane {Li-2(THF)P(O)(NBut)(2)(NHBut)}(2) with a central Li2O2 ring.