Caesium dodecaborate

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Caesium dodecaborate
Names
IUPAC name
Caesium dodecaborate
Identifiers
3D model (
JSmol
)
EC Number
  • 601-668-1
  • InChI=1S/B12H12.2Cs/c1-3-5-7-9-11-12-10-8-6-4-2;;/h1-12H;;/q+2;2*-1
    Key: WMUPFLCRVFMECH-UHFFFAOYSA-N
  • [Cs+].[Cs+].[BH]1234[BH]567[BH]189[BH]2%10%11[BH]8%12%13[BH]%10%14%15[BH]%16%17%18[BH]35([BH]6%16%19[BH]%12%14%17[BH-]79%13%19)[BH-]4%11%15%18
Properties
B12H12Cs2
Molar mass 407.63 g·mol−1
Appearance Colourless solid
Melting point >650 °C
low
Solubility good in ethers
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
 flammable
GHS labelling:
Danger
H228, H315, H319, H335
P101, P102, P103, P210, P231+P232, P280, P403+P233, P501
Related compounds
Structure
Ih
0 D
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Caesium dodecaborate is an

anion has been of great theoretical interest to the chemistry community.[1]

Structure

The [B12H12]2− anion's B12 core is a regular

icosahedral molecular symmetry, and it belongs to the molecular point group Ih. Its icosahedral shape is consistent with the classification of this cage as "closo" in polyhedral skeletal electron pair theory
.

Crystals of Cs2B12H12 feature Cs+ ions in contact with twelve

bond distances are 178 pm, and the B-H distances are 112 pm.[2] Many other salts are known.[3]

Preparation

The dodecaborate anion was first prepared in modest yield by Pitochelli and

Hawthorne from iododecarborane.[4] It is more conventienly prepared in two steps from sodium borohydride. First the borohydride is converted into a triborate anion using the etherate of boron trifluoride
:

4 NaBH4 + BF3 → NaB3H8 + 3 NaF + 4 H2

Pyrolysis of the triborate gives the twelve boron cluster as the sodium salt, which is then treated with caesium hydroxide to precipitate Cs2B12H12.[5]

Reactions and proposed applications

Salts of B12H122− have been investigated for

boron neutron capture therapy and as fuels for airbags.[6]

Salts of B12H122− are precursors to related derivatives including B12(OH)122− and B12(CH3)122−. This closo boron hydride resists degradation more so than the isoelectronic carboranes.

See also

References

  1. ISBN 978-0-08-037941-8
    .
  2. doi:10.1002/(SICI)1521-3749(200002)626:2<323::AID-ZAAC323>3.0.CO;2-Q
    .
  3. doi:10.1002/zaac.200470138
    .
  4. ^ Anthony R. Pitochelli, Frederick M. Hawthorne "The Isolation of Icosahedral B12H122− Ion" J. Am. Chem. Soc. 1960, volume 82, pp 3228–3229.
    doi:10.1021/ja01497a069
  5. ^ H. C. Miller, E. L. Muetterties "Borane Anions" Inorganic Syntheses, 1967, Volume 10, pp. 81-91.
    doi:10.1002/9780470132418.ch16
  6. doi:10.1135/cccc20020679
    .
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