2,5-Norbornadiene

Formula: C₇H₈
Molecular weight: 92.1384
IUPAC Standard InChI: InChI=1S/C7H8/c1-2-7-4-3-6(1)5-7/h1-4,6-7H,5H2
IUPAC Standard InChIKey: SJYNFBVQFBRSIB-UHFFFAOYSA-N
CAS Registry Number: 121-46-0
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: Bicyclo[2.2.1]hepta-2,5-diene; Bicyclo[2.2.1]heptadiene; Norbornadiene; 3,6-Methano-1,4-cyclohexadiene; Dicycloheptadiene; Bicyclo[2.2.1]-2,5-heptadiene; NSC 13672; 8,9,10-trinorborna-2,5-diene
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Condensed phase thermochemistry data

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Data compiled as indicated in comments:
ALS - Hussein Y. Afeefy, Joel F. Liebman, and Stephen E. Stein
DH - Eugene S. Domalski and Elizabeth D. Hearing

Quantity	Value	Units	Method	Reference	Comment
Δ_fH°_liquid	51.10 ± 0.72	kcal/mol	Ccb	Steele, 1978	ALS
Δ_fH°_liquid	42.72 ± 0.24	kcal/mol	Ccb	Hall, Smith, et al., 1973	ALS
Quantity	Value	Units	Method	Reference	Comment
Δ_cH°_liquid	-982.72 ± 0.72	kcal/mol	Ccb	Steele, 1978	Corresponding Δ_fHº_liquid = 51.10 kcal/mol (simple calculation by NIST; no Washburn corrections); ALS
Δ_cH°_liquid	-974.35 ± 0.24	kcal/mol	Ccb	Hall, Smith, et al., 1973	Corresponding Δ_fHº_liquid = 42.73 kcal/mol (simple calculation by NIST; no Washburn corrections); ALS
Δ_cH°_liquid	-979.6	kcal/mol	Ccb	Skuratov, Kozina, et al., 1958	Corresponding Δ_fHº_liquid = 48.0 kcal/mol (simple calculation by NIST; no Washburn corrections); ALS

Constant pressure heat capacity of liquid

C_p,liquid (cal/mol*K)	Temperature (K)	Reference	Comment
38.53	298.15	Steele, 1978	DH
27.75	297.	Hall, Smith, et al., 1973	DH

Reaction thermochemistry data

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Data compiled as indicated in comments:
ALS - Hussein Y. Afeefy, Joel F. Liebman, and Stephen E. Stein
B - John E. Bartmess

Note: Please consider using the reaction search for this species. This page allows searching of all reactions involving this species. A general reaction search form is also available. Future versions of this site may rely on reaction search pages in place of the enumerated reaction displays seen below.

Individual Reactions

= 2,5-Norbornadiene

By formula: C₇H₈ = C₇H₈

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-22. ± 6.	kcal/mol	AVG	N/A	Average of 6 values; Individual data points

C₇H₇^- + = 2,5-Norbornadiene

By formula: C₇H₇^- + H⁺ = C₇H₈

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	399.5 ± 1.8	kcal/mol	G+TS	Lee and Squires, 1986	gas phase; Between EtNH₂, nPrNH₂; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	391.3 ± 1.5	kcal/mol	IMRB	Lee and Squires, 1986	gas phase; Between EtNH₂, nPrNH₂; B
Δ_rG°	389.0 ± 5.0	kcal/mol	IMRB	Wright and Beauchamp, 1981	gas phase; B

2,5-Norbornadiene + 2 =

By formula: C₇H₈ + 2H₂ = C₇H₁₂

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-70.8 ± 0.3	kcal/mol	Chyd	Doering, Roth, et al., 1988	gas phase; ALS
Δ_rH°	-69.77 ± 0.36	kcal/mol	Chyd	Rogers, Choi, et al., 1980	liquid phase; solvent: Hexane; ALS
Δ_rH°	-68.11 ± 0.41	kcal/mol	Chyd	Turner, Meador, et al., 1957	liquid phase; solvent: Acetic acid; ALS

2,5-Norbornadiene = +

By formula: C₇H₈ = C₅H₆ + C₂H₂

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	28.00 ± 0.50	kcal/mol	Kin	Walsh and Wells, 1975	gas phase; Reanalyzed by Pedley, Naylor, et al., 1986, Original value = 28.36 ± 0.32 kcal/mol; ALS

2,5-Norbornadiene =

By formula: C₇H₈ = C₇H₈

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	14. ± 1.	kcal/mol	Ciso	Harel, Adamson, et al., 1987	liquid phase; solvent: Cyclohexane; Photocalorimetry; ALS

+ = 2,5-Norbornadiene

By formula: C₅H₆ + C₂H₂ = C₇H₈

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-28.0 ± 0.5	kcal/mol	Eqk	Walsh and Wells, 1975	gas phase; ALS

Gas phase ion energetics data

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

Data compiled as indicated in comments:
B - John E. Bartmess
LBLHLM - Sharon G. Lias, John E. Bartmess, Joel F. Liebman, John L. Holmes, Rhoda D. Levin, and W. Gary Mallard
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 C₇H₈⁺ (ion structure unspecified)

Quantity	Value	Units	Method	Reference	Comment
IE (evaluated)	8.38 ± 0.04	eV	N/A	N/A	L
Quantity	Value	Units	Method	Reference	Comment
Proton affinity (review)	203.0	kcal/mol	N/A	Hunter and Lias, 1998	HL
Quantity	Value	Units	Method	Reference	Comment
Gas basicity	196.1	kcal/mol	N/A	Hunter and Lias, 1998	HL

Ionization energy determinations

IE (eV)	Method	Reference	Comment
8.4	PE	Ohno, Ishide, et al., 1985	LBLHLM
8.35	PI	Traeger and McLoughlin, 1978	LLK
8.35	PE	Traeger and McLoughlin, 1978	LLK
8.42	PE	Demeo and Yencha, 1970	RDSH
8.42 ± 0.02	PI	Demeo and El-Sayed, 1970	RDSH
8.69	PE	Houk, Rondan, et al., 1983	Vertical value; LBLHLM
8.7	PE	Bieri, Asbrink, et al., 1982	Vertical value; LBLHLM
8.73	PE	Worley and Webb, 1980	Vertical value; LLK
8.73	PE	Worley, Webb, et al., 1979	Vertical value; LLK
8.69	PE	Kobayashi, 1978	Vertical value; LLK
8.69	PE	Cowling, Johnstone, et al., 1973	Vertical value; LLK
8.6	PE	Palmer and Findlay, 1972	Vertical value; LLK
8.69	PE	Heilbronner and Martin, 1972	Vertical value; LLK
8.70	PE	Bischof, Heilbronner, et al., 1971	Vertical value; LLK

Appearance energy determinations

Ion	AE (eV)	Other Products	Method	Reference	Comment
C₇H₇⁺	9.25	H	PI	Traeger and McLoughlin, 1978	LLK
C₇H₇⁺	9.75	H	EI	Dolejsek, Hanus, et al., 1962	RDSH
C₇H₇⁺	9.6	H	EI	Meyerson, McCollum, et al., 1961	RDSH

De-protonation reactions

C₇H₇^- + = 2,5-Norbornadiene

By formula: C₇H₇^- + H⁺ = C₇H₈

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	399.5 ± 1.8	kcal/mol	G+TS	Lee and Squires, 1986	gas phase; Between EtNH₂, nPrNH₂; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	391.3 ± 1.5	kcal/mol	IMRB	Lee and Squires, 1986	gas phase; Between EtNH₂, nPrNH₂; B
Δ_rG°	389.0 ± 5.0	kcal/mol	IMRB	Wright and Beauchamp, 1981	gas phase; B

References

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Steele, 1978
Steele, W.V., The standard enthalpies of formation of a series of C₇, bridged-ring hydrocarbons: norbornane, norbornene, nortricyclene, norbornadiene, and quadricyclane, J. Chem. Thermodyn., 1978, 10, 919-927. [all data]

Hall, Smith, et al., 1973
Hall, H.K., Jr.; Smith, C.D.; Baldt, J.H., Enthalpies of formation of norticyclene, norbornene, norbornadiene, and quadricyclane, J. Am. Chem. Soc., 1973, 95, 3197-3201. [all data]

Skuratov, Kozina, et al., 1958
Skuratov, S.M.; Kozina, M.P.; Shtocher, S.M.; Prevalova, N.M.; Kamkina, L.S.; Zuko, V.D., Heats of combustion of cyclic compounds, Bull. Chem. Thermodyn., 1958, 1, 21. [all data]

Lee and Squires, 1986
Lee, R.E.; Squires, R.R., Anionic homoaromaticity: A gas phase experimental study, J. Am. Chem. Soc., 1986, 105, 5078. [all data]

Wright and Beauchamp, 1981
Wright, C.A.; Beauchamp, J.L., Infrared spectra of gas phase ions and their use in elucidating reaction mechanisms. Identification of C₇H₇- structural isomers by multiphoton electron detachment using a low-powered laser, J. Am. Chem. Soc., 1981, 103, 6499. [all data]

Doering, Roth, et al., 1988
Doering, W.E.; Roth, W.R.; Breuckmann, R.; Figge, L.; Lennartz, H.-W.; Fessner, W.-D.; Prinzbach, F.H., Verbotene Reaktionen. - [2 + 2]-Cycloreversion starrer Cyclobutane, Chem. Ber., 1988, 121, 1-9. [all data]

Rogers, Choi, et al., 1980
Rogers, D.W.; Choi, L.S.; Girellini, R.S., Heats of hydrogenation and formation of quadricyclene, norbornadiene, norbornene, and nortricyclene, J. Phys. Chem., 1980, 84, 1810-1814. [all data]

Turner, Meador, et al., 1957
Turner, R.B.; Meador, W.R.; Winkler, R.E., Heats of hydrogenation. I. Apparatus and the heats of hydrogenation of bicyclo[2,2,1]heptene, bicyclo[2,2,1]heptadiene, bicyclo[2,2,2]octene and bicyclo[2,2,2]octadiene, J. Am. Chem. Soc., 1957, 79, 4116-4121. [all data]

Walsh and Wells, 1975
Walsh, R.; Wells, J.M., The enthalpy of formation of bicyclo[2,2,1]hepta-2,5-diene. Thermodynamic functions of bicyclo[2,2,1]heptane and bicyclo[2,2,1]hepta-2,5-diene, J. Chem. Thermodyn., 1975, 7, 149-154. [all data]

Pedley, Naylor, et al., 1986
Pedley, J.B.; Naylor, R.D.; Kirby, S.P., Thermochemical Data of Organic Compounds, Chapman and Hall, New York, 1986, 1-792. [all data]

Harel, Adamson, et al., 1987
Harel, Y.; Adamson, A.W.; Kutal, C.; Grutsch, P.A.; Yasufuku, K., Photocalorimetry. 6. Enthalpies of isomerization of norbornadiene and of substituted norbornadienes to corresponding quadricyclenes, J. Phys. Chem., 1987, 91, 901-904. [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]

Ohno, Ishide, et al., 1985
Ohno, K.; Ishide, T.; Naitoh, Y.; Izumi, Y., Study of stereochemical properties of molecular orbitals by penning ionization electron spectroscopy, J. Am. Chem. Soc., 1985, 107, 8082. [all data]

Traeger and McLoughlin, 1978
Traeger, J.C.; McLoughlin, R.G., A photoionization study of the energetics of C₇H₇⁺ ion formed from C₇H₈ precursors, Int. J. Mass Spectrom. Ion Phys., 1978, 27, 319. [all data]

Demeo and Yencha, 1970
Demeo, D.A.; Yencha, A.J., Photoelectron spectra of bicyclic and exocyclic olefins, J. Chem. Phys., 1970, 53, 4536. [all data]

Demeo and El-Sayed, 1970
Demeo, D.A.; El-Sayed, M.A., Ionization potential and structure of olefins, J. Chem. Phys., 1970, 52, 2622. [all data]

Houk, Rondan, et al., 1983
Houk, K.N.; Rondan, N.G.; Paddon-Row, M.N.; Jefford, C.W.; Huy, P.T.; Burrow, P.D.; Jordan, K.D., Ionization potentials, electron affinities, and molecular orbitals of 2-substituted norbornadienes. Theory of 1,2 and homo-1,4 carbene cycloaddition selectivities, J. Am. Chem. Soc., 1983, 105, 5563. [all data]

Bieri, Asbrink, et al., 1982
Bieri, G.; Asbrink, L.; Von Niessen, W., 30.4-nm He(II) photoelectron spectra of organic molecules, J. Electron Spectrosc. Relat. Phenom., 1982, 27, 129. [all data]

Worley and Webb, 1980
Worley, S.D.; Webb, T.R., The electronic structure of transition-metal carbonyl complexes of norbornadiene and mesitylene, J. Organomet. Chem., 1980, 192, 139. [all data]

Worley, Webb, et al., 1979
Worley, S.D.; Webb, T.R.; Gibson, D.H.; Ong, T.-S., On the electronic structures of cyclobutadiene trimethylenemethane, J. Organomet. Chem., 1979, 168, 16. [all data]

Kobayashi, 1978
Kobayashi, T., A new rule for photoelectron angular distributions of molecules, Phys. Lett. A, 1978, 69, 31. [all data]

Cowling, Johnstone, et al., 1973
Cowling, S.A.; Johnstone, R.A.W.; Gorman, A.A.; Smith, P.G., Photoelectron spectrum of 5-methylenenorborn-2-ene and through-space interactions (homobutadiene conjugation), J. Chem. Soc., Chem. Commun., 1973, 627. [all data]

Palmer and Findlay, 1972
Palmer, M.H.; Findlay, R.H., Ab initio molecular orbital calculations, the electronic structure and electron spectrum of norbornadiene, Chem. Phys. Lett., 1972, 15, 416. [all data]

Heilbronner and Martin, 1972
Heilbronner, E.; Martin, H.D., The π-orbital sequence in norbornadiene and related hydrocarbons, Helv. Chim. Acta, 1972, 55, 1490. [all data]

Bischof, Heilbronner, et al., 1971
Bischof, P.; Heilbronner, E.; Prinzbach, H.; Martin, H.D., A photoelectron-spectroscopic investigation of the homoconjugative interaction between π- and Walsh-orbitals in endo- and exo- cyclopropano-norbornene, Helv. Chim. Acta, 1971, 54, 1072. [all data]

Dolejsek, Hanus, et al., 1962
Dolejsek, Z.; Hanus, V.; Prinzbach, H., Das massenspektrometrische Verhalten von Quadricyclen, Angew. Chem., 1962, 74, 902. [all data]

Meyerson, McCollum, et al., 1961
Meyerson, S.; McCollum, J.D.; Rylander, P.N., Organic ions in the gas phase. VIII. Bicycloheptadiene, J. Am. Chem. Soc., 1961, 83, 1401. [all data]

Notes

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Symbols used in this document:

AE	Appearance energy
C_p,liquid	Constant pressure heat capacity of liquid
IE (evaluated)	Recommended ionization energy
Δ_cH°_liquid	Enthalpy of combustion of liquid at standard conditions
Δ_fH°_liquid	Enthalpy of formation of liquid at standard conditions
Δ_rG°	Free energy of reaction at standard conditions
Δ_rH°	Enthalpy of reaction at standard conditions

Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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