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
IUPAC Standard InChIKey: USBVLEBZPMQADS-UHFFFAOYSA-N
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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Gas phase ion energetics data

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)

Quantity	Value	Units	Method	Reference	Comment
IE (evaluated)	9.90 ± 0.03	eV	N/A	N/A	L
Quantity	Value	Units	Method	Reference	Comment
Proton affinity (review)	699.4	kJ/mol	N/A	Hunter and Lias, 1998	HL
Quantity	Value	Units	Method	Reference	Comment
Gas basicity	666.9	kJ/mol	N/A	Hunter and Lias, 1998	HL

Ionization energy determinations

IE (eV)	Method	Reference	Comment
9.87 ± 0.02	PE	Lloyd, Lynaugh, et al., 1975	LLK
9.94	PE	Fehlner, 1975	LLK
9.90	PE	Jones and Koski, 1973	LLK
10.54 ± 0.01	EI	Murphy and Enrione, 1970	RDSH
10.5	EI	Hollins and Stafford, 1970	RDSH
10.5	EI	Fehlner and Koski, 1964	RDSH
10.38	EI	Kaufman, Koski, et al., 1963	RDSH
10.8	EI	Margrave, 1960	RDSH
10.5	PE	Ulman and Fehlner, 1978	Vertical value; LLK

Appearance energy determinations

Ion	AE (eV)	Other Products	Method	Reference	Comment
B₄H⁺	20.0 ± 1.0	?	EI	Kaufman, Koski, et al., 1963	RDSH
B₄H₂⁺	18.0 ± 0.2	?	EI	Kaufman, Koski, et al., 1963	RDSH
B₄H₃⁺	16.0 ± 0.5	?	EI	Kaufman, Koski, et al., 1963	RDSH
B₄H₄⁺	14.1 ± 0.1	?	EI	Kaufman, Koski, et al., 1963	RDSH
B₄H₅⁺	15.1 ± 0.3	?	EI	Kaufman, Koski, et al., 1963	RDSH
B₄H₆⁺	12.3 ± 0.2	BH₃?	EI	Kaufman, Koski, et al., 1963	RDSH
B₅H₄⁺	13.0 ± 0.3	2H₂+H	EI	Kaufman, Koski, et al., 1963	RDSH
B₅H₅⁺	12.5 ± 0.5	2H₂	EI	Hollins and Stafford, 1970	RDSH
B₅H₅⁺	12.8 ± 0.2	2H₂	EI	Fehlner and Koski, 1964	RDSH
B₅H₅⁺	12.67 ± 0.03	2H₂	EI	Kaufman, Koski, et al., 1963	RDSH
B₅H₆⁺	12.1 ± 0.3	H₂+H	EI	Kaufman, Koski, et al., 1963	RDSH
B₅H₇⁺	11.4 ± 0.5	H₂	EI	Hollins and Stafford, 1970	RDSH
B₅H₇⁺	11.6 ± 0.2	H₂	EI	Fehlner and Koski, 1964	RDSH
B₅H₇⁺	11.4 ± 0.1	H₂	EI	Kaufman, Koski, et al., 1963	RDSH
B₅H₈⁺	11.84 ± 0.01	H	EI	Murphy and Enrione, 1971	LLK

References

Go To: Top, Gas phase ion energetics data, Notes

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 ion energetics data, References

Symbols used in this document:

AE Appearance energy

IE (evaluated) Recommended ionization energy
Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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AE	Appearance energy
IE (evaluated)	Recommended ionization energy