Pentacoordinated Nitrogen Atoms in the Structure of Hexalithium Bis[methylsilyl-tris(methylimide)] Hexakis(tetrahydrofuran)

Z. Naturforsch. 54 b, 8-12 (1999); received September 1, 1998 Silylamines, Silylamides, Crystal Structure Lithiation of tris(methylamino)wt'f/7v/silane using an excess of n -butyllithium affords the cor­ responding trifunctional lithium amide in high yield. The compound crystallizes from tetrahydrofuran as a dimer with six donor molecules: {[MeSi(NMeLi)3]2(thf)6}. The cluster is a cage structure grouped around a crystallographic center of inversion. The silicon and lithium atoms are tetrahedrally tetracoordinated, but the nitrogen atoms are pentacoordinated and have a square pyramidal environment of one carbon, one silicon, and three lithium atoms. Parallels can be drawn to other species with polymetallated nitrogen functions. An analogous compound was prepared from tris(methylamino)vwv/silane.