Pentaborane(11) is inorganic compound with the chemical formula B5H11. It is an obscure boron hydride cluster, especially relative to the heavily studied pentaborane(9) (B5H9). With two more hydrogen atoms than nido-pentaborane(9), pentaborane(11) is classified as an arachno- cluster.[1]

Pentaborane(11)
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.038.447 Edit this at Wikidata
EC Number
  • 242-307-4
UNII
  • InChI=1S/B5H11/c1-3-4-2-5(1,3)4/h5H,3-4H2,1-2H3
    Key: OPSKXWPMAKCNOG-UHFFFAOYSA-N
  • [BH3]1[BH2]2[BH]13[BH2]2[BH3]3
Properties
B5H11
Molar mass 65.14 g·mol−1
Melting point −123 °C (−189 °F; 150 K)
Boiling point 63 °C (145 °F; 336 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Synthesis

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Like many boron hydride clusters, pentaborane(11) was originally obtained from the pyrolysis of diborane. A more systematic synthesis entails treatment of [B4H9] with boron tribromide. The Lewis acid abstracts hydride to give unstable B4H8, the precursor to B5H11:[2]

[B4H9] + BBr3 → B4H8 + HBBr3
2 B4H8 → B5H11 + "B3H5"

References

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  1. ^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.
  2. ^ Toft, Mark A.; Leach, J. B.; Himpsl, Francis L.; Shore, Sheldon G. (1982). "New, Systematic Syntheses of Boron Hydrides via Hydride ion Abstraction Reactions: Preparation of B2H6, B4H10, B5H11, and B10H14". Inorganic Chemistry. 21 (5): 1952–7. doi:10.1021/ic00135a048.