Metal bis(trimethylsilyl)amides

Due to the bulky hydrocarbon backbone metal bis(trimethylsilyl)amide complexes have low lattice energies and are lipophilic.

[7] The lithium reagent may be prepared from n-butyllithium and bis(trimethylsilyl)amine:[8] The direct reaction of these molten metals with bis(trimethylsilyl)amine at high temperature has also been described:[9] Alkali metal silylamides are soluble in a range of organic solvents, where they exist as aggregates, and are commonly used in organic chemistry as strong sterically hindered bases.

An improved synthesis involving the reaction of benzylpotassium with calcium iodide, followed by reaction with bis(trimethylsilyl)amine results in potassium-free material:[12] Magnesium silylamides can be prepared from dibutylmagnesium; which is commercially available as a mixture of n-Bu and s-Bu isomers.

It deprotonates the free amine to yield the magnesium bis(trimethylsilyl)amide, itself commercially available.

The group 13[16] and bismuth(III) bis(trimethylsilyl)amides[17] are prepared in the same manner; the aluminium complex may also be prepared by treating strongly basic lithium aluminium hydride with the parent amine:[16] An alternative synthesis of tetrasulfur tetranitride entails the use of a metal bis(trimethylsilyl)amide [(Me3Si)2N]2S as a precursor with pre-formed S–N bonds.

The metal bis(trimethylsilyl)amide [((CH3)3Si)2N]2S reacts with the combination of SCl2 and sulfuryl chloride (SO2Cl2) to form S4N4, trimethylsilyl chloride, and sulfur dioxide:[18] Tetraselenium tetranitride, Se4N4, is a compound analogous to tetrasulfur tetranitride and can be synthesized by the reaction of selenium tetrachloride with [((CH3)3Si)2N]2Se.

[20] The melting and boiling points of the complexes decrease across the series, with Group 12 metals being sufficiently volatile to allow purification by distillation.

[21] Iron complexes are notable for having been isolated in both the ferrous (II) and ferric (III) oxidation states.

[24] In the solid state it forms a dimer with trigonal planar iron centers and bridging amido groups.