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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
Names
Preferred IUPAC name Potassium 1,1,1-trimethyl-N-(trimethylsilyl)silanaminide
Other names Potassium hexamethyldisilazide Potassium hexamethylsilazane
Identifiers
CAS Number
3D model (JSmol)
Abbreviations KHMDS
ChemSpider
ECHA InfoCard 100.102.263 Edit this at Wikidata
PubChem CID
UN number 3263
CompTox Dashboard (EPA)
InChI
  • InChI=1S/C6H18NSi2.K/c1-8(2,3)7-9(4,5)6;/h1-6H3;/q-1;+1Key: IUBQJLUDMLPAGT-UHFFFAOYSA-N
SMILES
  • C(C)(C)N()(C)(C)C
Properties
Chemical formula KSi
2C
6NH
18
Molar mass 199.4831 g mol
Appearance White, opaque crystals
Solubility in water Reacts
Hazards
GHS labelling:
Pictograms GHS05: Corrosive
Signal word Danger
Hazard statements H314
Precautionary statements P280, P305+P351+P338, P310
Related compounds
Other cations Lithium bis(trimethylsilyl)amide

Sodium bis(trimethylsilyl)amide

Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa). ☒N verify (what is  ?) Infobox references
Chemical compound

Potassium bis(trimethylsilyl)amide (commonly abbreviated as KHMDS, Potassium(K) HexaMethylDiSilazide) or potassium hexamethyldisilazane 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).

Structure

The methylsilyl groups give KHMDS good solubility in most organic solvents. Solution structures are either solvated monomers or dimers (or mixtures thereof) with this depending on the coordinating power, concentration, and temperature of the solvent. In general, weakly coordinating solvents such as toluene and N,N-dimethylethylamine give dimers, where as THF and diglyme gave monomers at high dilution. In the solid state, the unsolvated compound is dimeric, with two potassium and two nitrogen atoms forming a square. KHMDS conducts electricity poorly in solution and in the melt, which is attributed to very strong ion pairing.

See also

References

  1. ^ "Potassium Hexamethyldisilazane". sigmaaldrich.com. Retrieved 1 April 2023.
  2. ^ Potassium bis(trimethylsilyl)amide, Sigma-Aldrich
  3. ^ Spivey, Jesse A.; Collum, David B. (20 June 2024). "Potassium Hexamethyldisilazide (KHMDS): Solvent-Dependent Solution Structures". Journal of the American Chemical Society. 146 (26): 17827–17837. Bibcode:2024JAChS.14617827S. doi:10.1021/jacs.4c03418. PMC 11373885. PMID 38901126.
  4. Tesh, Kris F.; Hanusa, Timothy P.; Huffman, John C. (1990). "Ion pairing in potassium: The x-ray crystal structure of unsolvated 2". Inorg. Chem. 29 (8): 1584–1586. doi:10.1021/ic00333a029.
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