Pentaborane(9)

• Formula: B₅H₉
• Molecular weight: 63.126
• IUPAC Standard InChI: InChI=1S/B5H9/c6-1-5-2(6)8-4(5)9-3(5)7-1/h1-5H Copy

  
• IUPAC Standard InChIKey: USBVLEBZPMQADS-UHFFFAOYSA-N Copy
• CAS Registry Number: 19624-22-7
• Chemical structure:
  This structure is also available as a 2d Mol file or as a computed 3d SD file
  The 3d structure may be viewed using Java or Javascript.
• Other names: Pentaborane; UN 1380; B5H9
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• Information on this page:
  • Condensed phase thermochemistry data
  • Gas phase ion energetics data
  • References
  • Notes
• Other data available:
  • Gas phase thermochemistry data
  • Mass spectrum (electron ionization)
• Data at other public NIST sites:
  • Gas Phase Kinetics Database
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Condensed phase thermochemistry data

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Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

Liquid Phase Heat Capacity (Shomate Equation)

C_p° = A + B*t + C*t² + D*t³ + E/t²
H° − H°_298.15= A*t + B*t²/2 + C*t³/3 + D*t⁴/4 − E/t + F − H
S° = A*ln(t) + B*t + C*t²/2 + D*t³/3 − E/(2*t²) + G
    C_p = heat capacity (J/mol*K)
    H° = standard enthalpy (kJ/mol)
    S° = standard entropy (J/mol*K)
    t = temperature (K) / 1000.

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Gas phase ion energetics data

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Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

Data evaluated as indicated in comments:
HL - Edward P. Hunter and Sharon G. Lias
L - Sharon G. Lias

Data compiled as indicated in comments:
LLK - Sharon G. Lias, Rhoda D. Levin, and Sherif A. Kafafi
RDSH - Henry M. Rosenstock, Keith Draxl, Bruce W. Steiner, and John T. Herron

View reactions leading to H₉B₅⁺ (ion structure unspecified)

Ionization energy determinations

Appearance energy determinations

References

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Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

Chase, 1998
Chase, M.W., Jr., NIST-JANAF Themochemical Tables, Fourth Edition, J. Phys. Chem. Ref. Data, Monograph 9, 1998, 1-1951. [all data]

Hunter and Lias, 1998
Hunter, E.P.; Lias, S.G., Evaluated Gas Phase Basicities and Proton Affinities of Molecules: An Update, J. Phys. Chem. Ref. Data, 1998, 27, 3, 413-656, https://doi.org/10.1063/1.556018 . [all data]

Lloyd, Lynaugh, et al., 1975
Lloyd, D.R.; Lynaugh, N.; Roberts, P.J.; Guest, M.F., Photoelectron studies of boron and compounds, Part 5. -Higher boron hydrides B₄H₁₀, B₅H₉, B₁₀H₁₄, J. Chem. Soc. Faraday Trans. 2, 1975, 71, 1382. [all data]

Fehlner, 1975
Fehlner, T.P., Photoelectron spectroscopy of closo-carboranes. Observation of exo-polyhedral molecular orbitals, Inorg. Chem., 1975, 14, 934. [all data]

Jones and Koski, 1973
Jones, R.W.; Koski, W.S., Photoelectron spectrum of pentaborane, J. Chem. Phys., 1973, 59, 1228. [all data]

Murphy and Enrione, 1970
Murphy, C.B., Jr.; Enrione, R.E., Ionization potentials of pentaborane(9) derivatives by electron impact and molecular orbital calculations, Intern. J. Mass Spectrom. Ion Phys., 1970, 5, 157. [all data]

Hollins and Stafford, 1970
Hollins, R.E.; Stafford, F.E., Molecular beam mass spectra and pyrolysis of pentaborane(9), tetraborane carbonyl, and pentaborane(ll). Formation and mass spectrum of tetraborane(8), Inorg. Chem., 1970, 9, 877. [all data]

Fehlner and Koski, 1964
Fehlner, T.P.; Koski, W.S., The fragmentation of some boron hydrides by electron impact, J. Am. Chem. Soc., 1964, 86, 581. [all data]

Kaufman, Koski, et al., 1963
Kaufman, J.J.; Koski, W.S.; Kuhns, L.J.; Wright, S.S., Appearance and ionization potentials of selected fragments from isotopically labeled pentaboranes, J. Am. Chem. Soc., 1963, 85, 1369. [all data]

Margrave, 1960
Margrave, J.L., Ionization potentials of B₅H₉, B₅H₈I, B₁₀H₁₄, and B₁₀H₁₃C₂H₅ from electron impact studies, J. Chem. Phys., 1960, 32, 1889. [all data]

Ulman and Fehlner, 1978
Ulman, J.A.; Fehlner, T.P., Ultraviolet photoelectron spectroscopy of boranes and carboranes. Five-, six-, and seven- atom frameworks, J. Am. Chem. Soc., 1978, 100, 449. [all data]

Murphy and Enrione, 1971
Murphy, C.B., Jr.; Enrione, R.E., Bond dissociation energies of the 1- and 2- isomers of pentaborane derivatives by electron impact by extended Huckel calculations, Int. J. Mass Spectrom. Ion Phys., 1971, 7, 327. [all data]

Notes

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• Symbols used in this document:
  

  AE	Appearance energy
  IE (evaluated)	Recommended ionization energy
  S°liquid,1 bar	Entropy of liquid at standard conditions (1 bar)
  ΔfH°liquid	Enthalpy of formation of liquid at standard conditions

• Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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