Tris(triorganosilyl)methyl derivatives of potassium and lithium bearing dimethylamino or methoxy substituents at silicon. Crystal structures of KC(SiMe3)2(SiMe2NMe2), KC(SiMe2NMe2)3 and [LiC(SiMe3)(SiMe2OMe)2]2

Abstract

The compounds HC(SiMe₃)(SiMe₂X)₂, X = NMe₂ or OMe, have been synthesized in several steps from the phenyl derivative HC(SiMe₃)(SiMe₂Ph)₂ and metallated to give organometallic compounds of the type MC(SiMe₃)(SiMe₂X)₂, M = K or Li. The structures of the compounds KC(SiMe₃)₂(SiMe₂NMe₂) and KC(SiMe₂NMe₂)₃ consist of infinite chains in which cations are co-ordinated to both nitrogen and carbon centres, whereas the lithium compound [LiC(SiMe₃)(SiMe₂OMe)₂]₂ crystallises in a lattice of dimeric cage molecules. Structural trends in the series MC(SiMe₃)_n(SiMe₂X)_3-n, n = 0–3, M = K or Li, X = NMe₂ or OMe, are discussed.