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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

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 C4H4N2+ (ion structure unspecified)

Quantity Value Units Method Reference Comment
Proton affinity (review)877.1kJ/molN/AHunter and Lias, 1998HL
Quantity Value Units Method Reference Comment
Gas basicity847.0kJ/molN/AHunter and Lias, 1998HL

Electron affinity determinations

EA (eV) Method Reference Comment
>-0.065004ETSNenner and Schultz, 1975Pyrazine. EA estimated as 0.124 eV based on soln phase electrochemical correlations. G3MP2B3 calculations put EA ca. 0 eV; B

Ionization energy determinations

IE (eV) Method Reference Comment
9.0PEPiancastelli, Keller, et al., 1983LBLHLM
9.28 ± 0.01SScheps, Florida, et al., 1972LLK
9.29PEGleiter, Heilbronner, et al., 1972LLK
9.216PEAsbrink, Lindholm, et al., 1970RDSH
9.28 ± 0.05PEEland, 1969RDSH
9.36PEDewar and Worley, 1969RDSH
9.29 ± 0.01PIYencha and El-Sayed, 1968RDSH
9.29 ± 0.03SParkin and Innes, 1965RDSH
9.63PESuffolk, 1974Vertical value; LLK
9.63PEGleiter, Heilbronner, et al., 1970Vertical value; RDSH

Appearance energy determinations

Ion AE (eV) Other Products MethodReferenceComment
C3H2N+15.25 ± 0.10?EIMomigny, Urbain, et al., 1965RDSH
C3H3N+12.81 ± 0.10HCNEIMomigny, Urbain, et al., 1965RDSH
C4H3N2+13.68 ± 0.10HEIMomigny, Urbain, et al., 1965RDSH

De-protonation reactions

C4H3N2- + Hydrogen cation = Pyrazine

By formula: C4H3N2- + H+ = C4H4N2

Quantity Value Units Method Reference Comment
Deltar1643. ± 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
Deltar1604.6 ± 1.7kJ/molN/AWren, Vogelhuber, et al., 2012gas phase; B
Deltar1603. ± 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


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]

Nenner and Schultz, 1975
Nenner, I.; Schultz, G.J., Temporary negative ions and electron affinities of benzene and N-heterocyclic molecules: Pyridine, pyridazine, pyrimidine, pyrazine, and s-triazine, J. Chem. Phys., 1975, 62, 1747. [all data]

Piancastelli, Keller, et al., 1983
Piancastelli, M.N.; Keller, P.R.; Taylor, J.W.; Grimm, F.A.; Carlson, T.A., Angular distribution parameter as a function of photon energy for some mono- and diazabenzenes and its use for orbital assignment, J. Am. Chem. Soc., 1983, 105, 4235. [all data]

Scheps, Florida, et al., 1972
Scheps, R.; Florida, D.; Rice, S.A., Comments on the Rydberg spectrum of pyrazine, J. Mol. Spectrosc., 1972, 44, 1. [all data]

Gleiter, Heilbronner, et al., 1972
Gleiter, R.; Heilbronner, E.; Hornung, V., Photoelectron spectra of azabenzenes azanaphthalenes: I. Pyridine, diazines s-triazine and s-tetrazine, Helv. Chim. Acta, 1972, 55, 255. [all data]

Asbrink, Lindholm, et al., 1970
Asbrink, L.; Lindholm, E.; Edqvist, O., Jahn-Teller effect in the vibrational structure of the photoelectron spectrum of benzene, Chem. Phys. Lett., 1970, 5, 609. [all data]

Eland, 1969
Eland, J.H.D., Photoelectron spectra of conjugated hydrocarbons and heteromolecules, Intern. J. Mass Spectrom. Ion Phys., 1969, 2, 471. [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]

Yencha and El-Sayed, 1968
Yencha, A.J.; El-Sayed, M.A., Lowest ionization potentials of some nitrogen heterocyclics, J. Chem. Phys., 1968, 48, 3469. [all data]

Parkin and Innes, 1965
Parkin, J.E.; Innes, K.K., The vacuum ultraviolet spectra of pyrazine, pyrimidine, and pyridazine vapors. Part I. Spectra between 1550 A and 2000 A, J. Mol. Spectry., 1965, 15, 407. [all data]

Suffolk, 1974
Suffolk, R.J., The photoelectron spectra of the perfluorodiazines, J. Electron Spectrosc. Relat. Phenom., 1974, 3, 53. [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]

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]

Wren, Vogelhuber, et al., 2012
Wren, S.W.; Vogelhuber, K.M.; Garver, J.M.; Kato, S.; Sheps, L.; Bierbaum, V.M.; Lineberger, W.C., C-H Bond Strengths and Acidities in Aromatic Systems: Effects of Nitrogen Incorporation in Mono-, Di-, and Triazines, J. Am. Chem. Soc., 2012, 134, 15, 6584-6595, https://doi.org/10.1021/ja209566q . [all data]


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