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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)
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

Quantity Value Units Method Reference Comment
IE (evaluated)9.26 ± 0.01eVN/AN/AL
Quantity Value Units Method Reference Comment
Proton affinity (review)930.kJ/molN/AHunter and Lias, 1998HL
Quantity Value Units Method Reference Comment
Gas basicity898.1kJ/molN/AHunter and Lias, 1998HL

Proton affinity at 298K

Proton affinity (kJ/mol) Reference Comment
936.5 ± 8.5Wind, Papp, et al., 2005T = 298K; MM

Protonation entropy at 298K

Protonation entropy (J/mol*K) Reference Comment
-1. ± 10.Wind, Papp, et al., 2005T = 298K; MM

Ionization energy determinations

IE (eV) Method Reference Comment
9.34 ± 0.03EIArimura and Yoshikawa, 1984LBLHLM
9.25TRPILifshitz, 1982LBLHLM
9.60PEKimura, Katsumata, et al., 1981LLK
9.26PEUtsunomiya, Kobayashi, et al., 1978LLK
9.25PIEland, Berkowitz, et al., 1978LLK
9.74 ± 0.05EIZaretskii, Oren, et al., 1976LLK
~9.5EIVan Veen and Plantenga, 1975LLK
9.9 ± 0.1EIStefanovic and Grutzmacher, 1974LLK
9.263PEKing, Murrell, et al., 1972LLK
9.66 ± 0.03EIJohnstone and Mellon, 1972LLK
9.70 ± 0.05EIDistefano, Foffani, et al., 1971LLK
9.70EIDistefano, Foffani, et al., 1971, 2LLK
9.30 ± 0.01PIPotapov and Sorokin, 1970RDSH
9.10PEGoffart, Momigny, et al., 1969RDSH
9.10 ± 0.01PIGoffart, Momigny, et al., 1969RDSH
9.31PEDewar and Worley, 1969RDSH
9.28PEAl-Joboury and Turner, 1964RDSH
9.20 ± 0.05PIAkopyan and Vilesov, 1964RDSH
9.4PITerenin, 1961RDSH
9.266SEl-Sayed, Kaaba, et al., 1961RDSH
9.23 ± 0.03PIWatanabe, 1957RDSH
9.8 ± 0.2EIHustrulid, Kusch, et al., 1938RDSH
9.51PEKlasinc, Novak, et al., 1978Vertical value; LLK
9.66PEKobayashi and Nagakura, 1974Vertical value; LLK
9.7PEBatich, Heilbronner, et al., 1973Vertical value; LLK
9.6 ± 0.5PEHeilbronner, Hornung, et al., 1972Vertical value; LLK
9.59PEGleiter, Heilbronner, et al., 1970Vertical value; RDSH

Appearance energy determinations

Ion AE (eV) Other Products MethodReferenceComment
C3H3+14.00 ± 0.10?EIMomigny, Urbain, et al., 1965RDSH
C3H3N+13.84 ± 0.10C2H2EIMomigny, Urbain, et al., 1965RDSH
C4H2+16.17 ± 0.10HCN+H2EIMomigny, Urbain, et al., 1965RDSH
C4H3+16.61 ± 0.10HCN+HEIMomigny, Urbain, et al., 1965RDSH
C4H4+11.84 ± 0.05HCNTRPILifshitz and Malinovich, 1984LBLHLM
C4H4+12.6 ± 0.1HCNEIBurgers and Holmes, 1984LBLHLM
C4H4+12.34 ± 0.05HCNEIBurgers and Holmes, 1984LBLHLM
C4H4+12.0 ± 0.2HCNTRPILifshitz, 1982LBLHLM
C4H4+12.15 ± 0.02HCNPIPECORosenstock, Stockbauer, et al., 1981LLK
C4H4+11.8HCNPIEland, Berkowitz, et al., 1978LLK
C4H4+12.3 ± 0.1HCNEIRosenstock, McCulloh, et al., 1977LLK
C4H4+13.41 ± 0.05HCNEIZaretskii, Oren, et al., 1976LLK
C4H4+13.28HCNEIBeynon, Hopkinson, et al., 1969RDSH
C5H3N+12.42 ± 0.10H2EIMomigny, Urbain, et al., 1965RDSH
C5H4N+14.00 ± 0.10HEIMomigny, Urbain, et al., 1965RDSH

De-protonation reactions

C5H4N- + Hydrogen cation = Pyridine

By formula: C5H4N- + H+ = C5H5N

Quantity Value Units Method Reference Comment
Deltar1631. ± 8.4kJ/molIMRESchafman and Wenthold, 2007gas phase; B
Deltar1636. ± 10.kJ/molTDEqMeot-ner and Kafafi, 1988gas phase; anchored to 88MEO scale, not the "87 acidity scale". The Kiefer, Zhang, et al., 1997 BDE is for ortho.; B
Quantity Value Units Method Reference Comment
Deltar1601. ± 8.4kJ/molTDEqMeot-ner and Kafafi, 1988gas phase; anchored to 88MEO scale, not the "87 acidity scale". The Kiefer, Zhang, et al., 1997 BDE is for ortho.; B
Deltar1607. ± 13.kJ/molIMRBDePuy, Kass, et al., 1988gas phase; Comparable to water in acidity; B
Deltar<1574. ± 8.4kJ/molIMRBBruins, Ferrer-Correia, et al., 1978gas phase; O- deprotonates; B


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]

Wind, Papp, et al., 2005
Wind, J.J.; Papp, L.; Happel, M.; Hahn, K.; Andriole, E.J.; Poutsma, J.C., Proton Affinity of beta-Oxalylaminoalanine (BOAA): Incorporation of Direct Entropy Correction into the Single-Reference Kinetic Method, J. Am. Soc. Mass Spectrom., 2005, 16, 1151. [all data]

Arimura and Yoshikawa, 1984
Arimura, M.; Yoshikawa, Y., Ionization efficiency and ionization energy of cyclic compounds by electron impact, Mass Spectrosc. (Tokyo), 1984, 32, 375. [all data]

Lifshitz, 1982
Lifshitz, C., Time-dependent mass spectra and breakdown graphs. 2. The kinetic shift in pyridine, J. Phys. Chem., 1982, 86, 606. [all data]

Kimura, Katsumata, et al., 1981
Kimura, K.; Katsumata, S.; Achiba, Y.; Yamazaki, T.; Iwata, S., Ionization energies, Ab initio assignments, and valence electronic structure for 200 molecules in Handbook of HeI Photoelectron Spectra of Fundamental Organic Compounds, Japan Scientific Soc. Press, Tokyo, 1981. [all data]

Utsunomiya, Kobayashi, et al., 1978
Utsunomiya, C.; Kobayashi, T.; Nagakura, S., Photoelectron angular distribution measurements for some pyridines, Bull. Chem. Soc. Jpn., 1978, 451, 3482. [all data]

Eland, Berkowitz, et al., 1978
Eland, J.H.D.; Berkowitz, J.; Schulte, H.; Frey, R., Rates of unimolecular pyridine ion decay and the heat of formation of C4H4+, Int. J. Mass Spectrom. Ion Phys., 1978, 28, 297. [all data]

Zaretskii, Oren, et al., 1976
Zaretskii, Z.V.I.; Oren, D.; Kelner, L., Automatic method for the measurement of the electron impact ionization and appearance potentials, Appl. Spectrosc., 1976, 30, 366. [all data]

Van Veen and Plantenga, 1975
Van Veen, E.H.; Plantenga, F.L., Threshold electron-impact excitation spectrum of pyridine, Chem. Phys. Lett., 1975, 30, 28. [all data]

Stefanovic and Grutzmacher, 1974
Stefanovic, D.; Grutzmacher, H.F., The ionisation potential of some substituted pyridines, Org. Mass Spectrom., 1974, 9, 1052. [all data]

King, Murrell, et al., 1972
King, G.H.; Murrell, J.N.; Suffolk, R.J., The vacuum-ultraviolet photoelectron spectra of fluoropyridines, J. Chem. Soc. Dalton Trans., 1972, 564. [all data]

Johnstone and Mellon, 1972
Johnstone, R.A.W.; Mellon, F.A., Electron-impact ionization and appearance potentials, J. Chem. Soc. Faraday Trans. 2, 1972, 68, 1209. [all data]

Distefano, Foffani, et al., 1971
Distefano, G.; Foffani, A.; Innorta, G.; Pignataro, S., Mass spectrometric study of transition metal complexes with ligands having nitrogen or sulphur as donor atom, Adv. Mass Spectrom., 1971, 5, 696. [all data]

Distefano, Foffani, et al., 1971, 2
Distefano, G.; Foffani, A.; Innorta, G.; Pignataro, S., Electron impact ionization potentials of some manganese, chromium and tungsten organometallic derivatives, Int. J. Mass Spectrom. Ion Phys., 1971, 7, 383. [all data]

Potapov and Sorokin, 1970
Potapov, V.K.; Sorokin, V.V., Investigation of ionic molecular reactions proceeding during photoionization of aromatic compounds and alcohols, Dokl. Akad. Nauk SSSR, 1970, 195, 616, In original 848. [all data]

Goffart, Momigny, et al., 1969
Goffart, C.; Momigny, J.; Natalis, P., Photoionization studies by total ionization measurements and photoelectron spectra. II.Pyridine, Intern. J. Mass Spectrom. lon Phys., 1969, 3, 371. [all data]

Dewar and Worley, 1969
Dewar, M.J.S.; Worley, S.D., Photoelectron spectra of molecules. II.The ionization potentials of azabenzenes and azanaphthalenes, J. Chem. Phys., 1969, 51, 263. [all data]

Al-Joboury and Turner, 1964
Al-Joboury, M.I.; Turner, D.W., Molecular photoelectron spectroscopy. Part II. A summary of ionization potentials, J. Chem. Soc., 1964, 4434. [all data]

Akopyan and Vilesov, 1964
Akopyan, M.E.; Vilesov, F.I., Excited states of positive ions and dissociative photoionization of aromatic amines, Dokl. Akad. Nauk SSSR, 1964, 158, 1386, In original 965. [all data]

Terenin, 1961
Terenin, A., Charge transfer in organic solids, induced by light, Proc. Chem. Soc., London, 1961, 321. [all data]

El-Sayed, Kaaba, et al., 1961
El-Sayed, M.F.A.; Kaaba, M.; Tanaka, Y., Ionization potentials of benzene, hexadeuterobenzene, and pyridine from their observed Rydberg series in the region 600-2000 A, J. Chem. Phys., 1961, 34, 334. [all data]

Watanabe, 1957
Watanabe, K., Ionization potentials of some molecules, J. Chem. Phys., 1957, 26, 542. [all data]

Hustrulid, Kusch, et al., 1938
Hustrulid, A.; Kusch, P.; Tate, J.T., The dissociation of benzene (C6H6), pyridine (C5H5N) and cyclohexane (C6H12) by electron impact, Phys. Rev., 1938, 54, 1037. [all data]

Klasinc, Novak, et al., 1978
Klasinc, L.; Novak, I.; Scholz, M.; Kluge, G., Photoelektronenspektren substituierter Pyridine und Benzole und ihre Interpretation durch die CNDO/SWW-Methode, Croat. Chem. Acta, 1978, 51, 43. [all data]

Kobayashi and Nagakura, 1974
Kobayashi, T.; Nagakura, S., Photoelectron spectra of aminopyridines and cyanopyridines, J. Electron Spectrosc. Relat. Phenom., 1974, 4, 207. [all data]

Batich, Heilbronner, et al., 1973
Batich, C.; Heilbronner, E.; Hornung, V.; Ashe, A.J.; Clark, D.T.; Cobley, U.T.; Kilcast, D.; Scanlan, I., Photoelectron spectra of phosphabenzen, arsabenzene, and stibabenzene, J. Am. Chem. Soc., 1973, 95, 928. [all data]

Heilbronner, Hornung, et al., 1972
Heilbronner, E.; Hornung, V.; Pinkerton, F.H.; Thames, S.F., 31. Photoelectron spectra of azabenzenes and azanaphthalenes: III. The orbital sequence in methyl- and trimethylsilyl- substituted pyridines, Helv. Chim. Acta, 1972, 55, 289. [all data]

Gleiter, Heilbronner, et al., 1970
Gleiter, R.; Heilbronner, E.; Hornung, V., Lone pair interaction in pyridazine, pyrimidine, and pyrazine, Angew. Chem. Int. Ed. Engl., 1970, 9, 901. [all data]

Momigny, Urbain, et al., 1965
Momigny, J.; Urbain, J.; Wankenne, H., Les effets de l'impact electronique sur la pyridine et les diazines isomeres, Bull. Soc. Roy. Sci. Liege, 1965, 34, 337. [all data]

Lifshitz and Malinovich, 1984
Lifshitz, C.; Malinovich, Y., Time resolved photoionization mass spectrometry in the millisecond range, Int. J. Mass Spectrom. Ion Processes, 1984, 60, 99. [all data]

Burgers and Holmes, 1984
Burgers, P.C.; Holmes, J.L., Fragmentation rate constants and appearance energies for reactions having a large kinetic shift and the energy partitioning in their metastable decomposition, Int. J. Mass Spectrom. Ion Processes, 1984, 58, 15. [all data]

Rosenstock, Stockbauer, et al., 1981
Rosenstock, H.M.; Stockbauer, R.; Parr, A.C., Unimolecular kinetis of pyridine ion fragmentation, Int. J. Mass Spectrom. Ion Phys., 1981, 38, 323. [all data]

Rosenstock, McCulloh, et al., 1977
Rosenstock, H.M.; McCulloh, K.E.; Lossing, F.P., On the mechanisms of C6H6 ionization fragmentation, Int. J. Mass Spectrom. Ion Phys., 1977, 25, 327. [all data]

Beynon, Hopkinson, et al., 1969
Beynon, J.H.; Hopkinson, J.A.; Lester, G.R., Mass spectrometry-the appearance potentials of "meta-stable peaks" in some aromatic nitro compounds - a chemical reaction in the mass spectrometer, Intern. J. Mass Spectrom. Ion Phys., 1969, 2, 291. [all data]

Schafman and Wenthold, 2007
Schafman, B.S.; Wenthold, P.G., Regioselectivity of pyridine deprotonation in the gas phase, J. Org. Chem., 2007, 72, 5, 1645-1651, https://doi.org/10.1021/jo062117x . [all data]

Meot-ner and Kafafi, 1988
Meot-ner, M.; Kafafi, S.A., Carbon Acidities of Aromatic Compounds, J. Am. Chem. Soc., 1988, 110, 19, 6297, https://doi.org/10.1021/ja00227a003 . [all data]

Kiefer, Zhang, et al., 1997
Kiefer, J.H.; Zhang, Q.; Kern, R.D.; Yao, J.; Jursic, B., Pyrolysis of Aromatic Azines: Pyrazine, Pyrimidine, and Pyridine, J. Phys. Chem. A, 1997, 101, 38, 7061, https://doi.org/10.1021/jp970211z . [all data]

DePuy, Kass, et al., 1988
DePuy, C.H.; Kass, S.R.; Bean, G.P., Formation and Reactions of Heteroaromatic Anions in the Gas Phase, J. Org. Chem., 1988, 53, 19, 4427, https://doi.org/10.1021/jo00254a001 . [all data]

Bruins, Ferrer-Correia, et al., 1978
Bruins, A.P.; Ferrer-Correia, A.J.; Harrison, A.G.; Jennings, K.R.; Mithcum, R.K., Negative ion chemical ionization mass spectrometry of some aromatic compounds using O-. as the reagent ion, Adv. Mass Spectrom., 1978, 7, 355. [all data]


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