Synthesis and characterisation of alkali metal bis(dimethylsilyl)amides: infinite all-planar laddering in the unsolvated sodinm derivative

The synthesis of the bis(dimethylsilyl)amide complexes [MN(SiHMe2)(2)] (M = Li (1), Na (2), K (3)) was accomplished in high yield (>95%) by various standard procedures. Additionally, a novel trans-silylamination reaction has been applied to synthesize the sodium derivative 2. The alkali metal amide complexes which are readily soluble in aliphatic hydrocarbons were characterised by means of IR and H-1, C-13 and Si-29 NMR spectroscopy. A single crystal X-ray diffraction study of the sodium derivative 2 revealed the formation of an infinite, all-planar ladder structure. Compound 2 crystallizes from n-hexane at -35 degrees C in the orthorhombic space group Pnma with a = 5.4439(2) Angstrom, b = 15.7268(9) Angstrom, c = 10.9751(6) Angstrom, V = 939.63(8) Angstrom(3) and Z = 4. Least squares refinement of the model based on 873 reflections converged to a final omega R-2 = 0.1124. (C) 1998 Elsevier Science Ltd. All rights reserved.