Reaction of dimethylamine with Cl[sub 3]SiN(H)SiMe[sub 3] in hexane solution at 25[degrees]C gave the bulky disilazane [(Me[sub 2]N)[sub 3]Si]N(H)SiMe[sub 3] in 73% yield. Reactions of [(Me[sub 2]N)[sub 3]Si]N(H)SiMe[sub 3] with n-butyllithium in benzene at 0[degrees]C produced the lithium complex [(Me[sub 2]N)[sub 3]Si]N(Li)SiMe[sub 3] in 82% yield. LiN[Si(NMe[sub 2])[sub 3]][sub 2] was prepared in 92% yield from the reaction of HN(SiCl[sub 3])[sub 2] and 7 equiv of LiNMe[sub 2] in hexane. LiN[Si(NMe[sub 2])[sub 3]][sub 2] is converted to the amine (83% yield) by reaction with [H[sub 2]NMe[sub 2]]Cl in THF. The new compounds were characterized spectroscopically, and the X-ray crystal structures of [(Me[sub 2]N)[sub 3]Si]N(Li)SiMe[sub 3] and LiN[Si(NMe[sub 2])[sub 3]][sub 2] were determined. [(Me[sub 2]N)[sub 3]Si]N(Li)SiMe[sub 3] and LiN[Si(NMe[sub 2])[sub 3]][sub 2] are dimeric in the solid state, forming four-membered Li[sub 2]N[sub 2] rings. In both cases dimethylamido groups bridge between silicon and lithium, giving three-coordinate lithium in [[(Me[sub 2]N)[sub 3]Si]N(Li)SiMe[sub 3]][sub 2] and four-coordinate lithium in [LiN[Si(NMe[sub 2])[sub 3]][sub 2]][sub 2]. Crystal data at [minus]50[degrees]C (Mo K[alpha] radiation, [lambda] = 0.710 73 [angstrom]): [[(Me[sub 2]N)[sub 3]Si]N(Li)SiMe[sub 3]][sub 2], C[sub 18]H[sub 54]N[sub 8]Li[sub 2]Si[sub 4], a = 8.594(2) [angstrom], b = 17.185(3) [angstrom], c = 22.045(4) [angstrom], [beta] = 95.29(2)[degrees], monoclinic,more » space group C2/c, Z = 4, R = 0.045; [LiN[Si(NMe[sub 2])[sub 3]][sub 2]][sub 2], C[sub 24]H[sub 72]N[sub 14]Li[sub 2]Si[sub 4], a = 16.634(4) [angstrom], b = 21.169(7) [angstrom], c = 23.924(8) [angstrom], orthorhombic, space group Pbca, Z = 8, R = 0.044.« less