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
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• Other names: Pentaborane; UN 1380; B5H9
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• Information on this page:
  • Gas phase thermochemistry data
  • Condensed phase thermochemistry data
  • Gas phase ion energetics data
  • Mass spectrum (electron ionization)
  • References
  • Notes
• Data at other public NIST sites:
  • Gas Phase Kinetics Database
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Gas 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.

Gas 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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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

Mass spectrum (electron ionization)

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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 compiled by: NIST Mass Spectrometry Data Center, William E. Wallace, director

Spectrum

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Additional Data

References

Go To: Top, Gas phase thermochemistry data, Condensed phase thermochemistry data, Gas phase ion energetics data, Mass spectrum (electron ionization), Notes

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

Go To: Top, Gas phase thermochemistry data, Condensed phase thermochemistry data, Gas phase ion energetics data, Mass spectrum (electron ionization), References

• Symbols used in this document:
  

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

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