Potassium bis(trimethylsilyl)amide

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Potassium bis(trimethylsilyl)amide
Stereo, skeletal formula of potassium bis(trimethylsilyl)amide dimer
Ball and stick model of potassium bis(trimethylsilyl)amide dimer
Abbreviations KHMDS
CAS number 40949-94-8 YesY
PubChem 3251421
ChemSpider 21171158 N
UN number 3263
Jmol-3D images Image 1
Molecular formula KSi
Molar mass 199.4831 g mol-1
Appearance White, opaque crystals
Solubility in water Reacts
GHS pictograms The corrosion pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)
GHS signal word DANGER
GHS hazard statements H314[1]
GHS precautionary statements P280, P305+351+338, P310[1]
EU classification Corrosive C[1]
R-phrases R14, R34[1]
S-phrases S26, S36/37/39, S43, S45[1]
Related compounds
Other cations Lithium bis(trimethylsilyl)amide

Sodium bis(trimethylsilyl)amide

Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

Potassium bis(trimethylsilyl)amide (commonly abbreviated as KHMDS, Potassium(K) HexaMethylDiSilazide) is the chemical compound with the formula ((CH3)3Si)2NK. It is a strong, non-nucleophilic base with an approximate pKa of 26 (compare to lithium diisopropylamide, at 36).[citation needed]


In the solid state, the unsolvated compound is dimeric, with two potassium and two nitrogen atoms forming a square. This compound is soluble in hydrocarbon solvents, and conducts electricity poorly in solution and in the melt. This is attributed to very strong ion-pairing.[2]

See also[edit]


  1. ^ a b c d e Potassium bis(trimethylsilyl)amide, Sigma-Aldrich
  2. ^ Tesh, Kris F.; Hanusa, Timothy P.; Huffman, John C. (1990). "Ion pairing in [bis(trimethylsilyl)amido]potassium: The x-ray crystal structure of unsolvated [KN(SiMe3)2]2". Inorg. Chem. 29 (8): 1584–1586. doi:10.1021/ic00333a029.