Potassium tetraphenylborate

Potassium tetraphenylborate is the salt with the formula KB(C₆H₅)₄). It is a colourless salt that is a rare example of a water-insoluble salt of potassium.

Potassium tetraphenylborate

Names
IUPAC name Potassium tetraphenylboranuide
Identifiers
CAS Number	3244-41-5^N
3D model (JSmol)	Interactive image
ChemSpider	4937589^Y
ECHA InfoCard	100.156.375
PubChem CID	6432333
CompTox Dashboard (EPA)	DTXSID70635409
InChI InChI=1S/C24H20B.K/c1-5-13-21(14-6-1)25(22-15-7-2-8-16-22,23-17-9-3-10-18-23)24-19-11-4-12-20-24;/h1-20H;/q-1;+1^Y Key: MAMCUZQNCMYPCY-UHFFFAOYSA-N^Y InChI=1/C24H20B.K/c1-5-13-21(14-6-1)25(22-15-7-2-8-16-22,23-17-9-3-10-18-23)24-19-11-4-12-20-24;/h1-20H;/q-1;+1 Key: MAMCUZQNCMYPCY-UHFFFAOYAU
SMILES [K+].c1c(cccc1)[B-](c2ccccc2)(c3ccccc3)c4ccccc4
Properties
Chemical formula	C24H20BK
Molar mass	358.3249
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

The salt has a low solubility in water of only 1.8×10⁻⁴ g/L. It is, however, soluble in organic solvents. The insolubility of this compound has been used to determine the concentration of potassium ions by precipitation and gravimetric analysis:[1]

K⁺ + NaB(Ph)₄ → KB(Ph)₄ + Na⁺

The compound adopts a polymeric structure with bonds between the phenyl rings and potassium. As such it is classified as an organopotassium compound.[2]

References

1. Engelbrecht, R. M.; McCoy, F. A. (1956). "Determination of Potassium by Tetraphenylborate Method". Anal. Chem. 28 (11): 1772. doi:10.1021/ac60119a040.
2. Ulrich Behrens, Frank Hoffmann, and Falk Olbrich "Solid-State Structures of Base-Free Lithium and Sodium Tetraphenylborates at Room and Low Temperature: Comparison with the Higher Homologues MB(C₆H₅)₄ (M = K, Rb, Cs)" Organometallics 2012, volume 31, p. 905−913. doi:10.1021/om200943n

External links

• Potassium tetraphenylborate Jmol Page