1,3-Cyclopentadiene
- Formula: C5H6
- Molecular weight: 66.1011
- IUPAC Standard InChIKey: ZSWFCLXCOIISFI-UHFFFAOYSA-N
- CAS Registry Number: 542-92-7
- 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: Cyclopentadiene; Pentole; Pyropentylene; R-Pentine
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Gas phase ion energetics data
Go To: Top, References, Notes
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:
B - John E. Bartmess
MM - Michael M. Meot-Ner (Mautner)
LL - Sharon G. Lias and Joel F. Liebman
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 C5H6+ (ion structure unspecified)
Quantity | Value | Units | Method | Reference | Comment |
---|---|---|---|---|---|
IE (evaluated) | 8.57 ± 0.01 | eV | N/A | N/A | L |
Quantity | Value | Units | Method | Reference | Comment |
Proton affinity (review) | 196.4 | kcal/mol | N/A | Hunter and Lias, 1998 | HL |
Quantity | Value | Units | Method | Reference | Comment |
Gas basicity | 190.8 | kcal/mol | N/A | Hunter and Lias, 1998 | HL |
Proton affinity at 298K
Proton affinity (kcal/mol) | Reference | Comment |
---|---|---|
197.9 | Aue, Guidoni, et al., 2000 | Experimental literature data re-evaluated by the authors using ab initio protonation entropies; MM |
Gas basicity at 298K
Gas basicity (review) (kcal/mol) | Reference | Comment |
---|---|---|
190.8 | Aue, Guidoni, et al., 2000 | Experimental literature data re-evaluated by the authors using ab initio protonation entropies; MM |
Ionization energy determinations
IE (eV) | Method | Reference | Comment |
---|---|---|---|
8.44 | PE | Kiselev, Sakhabutdinov, et al., 1992 | LL |
8.58 ± 0.02 | PE | Bieri, Burger, et al., 1977 | LLK |
8.56 ± 0.01 | EI | Holmes and McGillivray, 1971 | LLK |
8.57 ± 0.01 | PI | Derrick, Asbrink, et al., 1971 | LLK |
8.57 ± 0.01 | PI | Demeo and El-Sayed, 1970 | RDSH |
9.0 | EI | Hedaya, Kent, et al., 1968 | RDSH |
8.55 | PI | Dewar and Worley, 1968 | RDSH |
8.53 | PE | Kiselev, Sakhabutdinov, et al., 1992 | Vertical value; LL |
8.61 | PE | Bock and Kaim, 1980 | Vertical value; LLK |
8.6 | PE | Cradock, Ebsworth, et al., 1975 | Vertical value; LLK |
8.56 | PE | Cradock, Findlay, et al., 1974 | Vertical value; LLK |
Appearance energy determinations
Ion | AE (eV) | Other Products | Method | Reference | Comment |
---|---|---|---|---|---|
C5H5+ | 12.62 | H | EI | Occolowitz and White, 1968 | RDSH |
C5H5+ | 12.9 | H | EI | Harrison, Haynes, et al., 1965 | RDSH |
C5H5+ | 11.9 ± 0.5 | H | EI | Dorman, 1965 | RDSH |
C5H5+ | 12.6 | H | EI | Harrison, Honnen, et al., 1960 | RDSH |
De-protonation reactions
Quantity | Value | Units | Method | Reference | Comment |
---|---|---|---|---|---|
ΔrH° | 353.9 ± 2.2 | kcal/mol | G+TS | Bartmess, Scott, et al., 1979 | gas phase; value altered from reference due to change in acidity scale; B |
ΔrH° | 354.9 ± 2.9 | kcal/mol | G+TS | Cumming and Kebarle, 1978 | gas phase; B |
ΔrH° | 357.2 ± 2.0 | kcal/mol | D-EA | Engelking and Lineberger, 1977 | gas phase; B |
Quantity | Value | Units | Method | Reference | Comment |
ΔrG° | 347.7 ± 2.0 | kcal/mol | IMRE | Bartmess, Scott, et al., 1979 | gas phase; value altered from reference due to change in acidity scale; B |
ΔrG° | 348.7 ± 2.0 | kcal/mol | IMRE | Cumming and Kebarle, 1978 | gas phase; B |
References
Go To: Top, Gas phase ion energetics data, Notes
Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.
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]
Aue, Guidoni, et al., 2000
Aue, D.H.; Guidoni, M.; Betowski, L.D.,
Ab initio calculated gas-phase basicities of polynuclear aromatic hydrocarbons,
Int. J. Mass Spectrom., 2000, 201, 283. [all data]
Kiselev, Sakhabutdinov, et al., 1992
Kiselev, V.D.; Sakhabutdinov, A.G.; Shakirov, I.M.; Zverev, V.V.; Konovalov, A.I.,
Bis reactants in Diels-Alder reactions. VII. Preparation and properties of polyadducts of reactions of bis(polymethylcyclopentadienes) and bis(maleimides),
Zh. Org. Khim., 1992, 28, 2244. [all data]
Bieri, Burger, et al., 1977
Bieri, G.; Burger, F.; Heilbronner, E.; Maier, J.P.,
Valence ionization enrgies of hydrocarbons,
Helv. Chim. Acta, 1977, 60, 2213. [all data]
Holmes and McGillivray, 1971
Holmes, J.L.; McGillivray, D.,
The mass spectra of isomeric hydrocarbons-I: Norbornene and nortricyclene; The mechanisms and energetics of their fragmentations,
Org. Mass Spectrom., 1971, 5, 1349. [all data]
Derrick, Asbrink, et al., 1971
Derrick, P.J.; Asbrink, L.; Edqvist, O.; Jonsson, B.-O.; Lindholm, E.,
Rydberg series in small molecules. XIII. Photoelectron spectroscopy and electronic structure of cyclopentadiene,
Intern. J. Mass Spectrom. Ion Phys., 1971, 6, 203. [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]
Hedaya, Kent, et al., 1968
Hedaya, E.; Kent, M.E.; McNeil, D.W.; Lossing, F.P.; McAllister, T.,
The thermal rearrangement of phenylnitrene to cyanocyclopentadiene,
Tetrahedron Lett., 1968, 30, 3415. [all data]
Dewar and Worley, 1968
Dewar, M.J.S.; Worley, S.D.,
Ionization potential of cis-1,3-butadiene,
J. Chem. Phys., 1968, 49, 2454. [all data]
Bock and Kaim, 1980
Bock, H.; Kaim, W.,
Radical ions. 37. Ionization and one-electron oxidation of electron-rich silylalkyl olefins,
J. Am. Chem. Soc., 1980, 102, 4429. [all data]
Cradock, Ebsworth, et al., 1975
Cradock, S.; Ebsworth, E.A.V.; Moretto, H.; Rankin, D.W.H.,
Photoelectron spectra and fluxional behaviour in some σ-cyclopentadienes,
J. Chem. Soc. Dalton Trans., 1975, 390. [all data]
Cradock, Findlay, et al., 1974
Cradock, S.; Findlay, R.H.; Palmer, M.H.,
Bonding in methyl- and silyl-cyclopentadiene compounds: a study by photoelectron spectroscopy ab initio molecular-orbital calculations,
J. Chem. Soc. Dalton Trans., 1974, 1650. [all data]
Occolowitz and White, 1968
Occolowitz, J.L.; White, G.L.,
Energetic considerations in the assignment of some fragment ion structures,
Australian J. Chem., 1968, 21, 997. [all data]
Harrison, Haynes, et al., 1965
Harrison, A.G.; Haynes, P.; McLean, S.; Meyer, F.,
The mass spectra of methyl-substituted cyclopentadienes,
J. Am. Chem. Soc., 1965, 87, 5099. [all data]
Dorman, 1965
Dorman, F.H.,
Second differential ionization-efficiency curves for fragment ions by electron impact,
J. Chem. Phys., 1965, 43, 3507. [all data]
Harrison, Honnen, et al., 1960
Harrison, A.G.; Honnen, L.R.; Dauben, H.J., Jr.; Lossing, F.P.,
Free radicals by mass spectrometry. XX. Ionization potentials of cyclopentadienyl and cycloheptatrienyl radicals,
J. Am. Chem. Soc., 1960, 82, 5593. [all data]
Bartmess, Scott, et al., 1979
Bartmess, J.E.; Scott, J.A.; McIver, R.T., Jr.,
The gas phase acidity scale from methanol to phenol,
J. Am. Chem. Soc., 1979, 101, 6047. [all data]
Cumming and Kebarle, 1978
Cumming, J.B.; Kebarle, P.,
Summary of gas phase measurements involving acids AH. Entropy changes in proton transfer reactions involving negative ions. Bond dissociation energies D(A-H) and electron affinities EA(A),
Can. J. Chem., 1978, 56, 1. [all data]
Engelking and Lineberger, 1977
Engelking, P.C.; Lineberger, W.C.,
Laser photoelectron spectrometry of C5H5-: A determination of the electron affinity and Jahn-Teller coupling in cyclopentadienyl,
J. Chem. Phys., 1977, 67, 1412. [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 ΔrG° Free energy of reaction at standard conditions ΔrH° Enthalpy of reaction at standard conditions - Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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