Ethynyl radical

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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
L - Sharon G. Lias

Data compiled as indicated in comments:
B - John E. Bartmess
LL - Sharon G. Lias and Joel F. Liebman
LLK - Sharon G. Lias, Rhoda D. Levin, and Sherif A. Kafafi

View reactions leading to C2H+ (ion structure unspecified)

Quantity Value Units Method Reference Comment
IE (evaluated)11.61 ± 0.07eVN/AN/AL
Quantity Value Units Method Reference Comment
Proton affinity (review)180.kcal/molN/AHunter and Lias, 1998HL
Quantity Value Units Method Reference Comment
Gas basicity172.3kcal/molN/AHunter and Lias, 1998HL

Electron affinity determinations

EA (eV) Method Reference Comment
2.9689 ± 0.0011N/AZhou, Garand, et al., 2007B
2.9690 ± 0.0060LPESErvin and Lineberger, 1991B
2.956 ± 0.020LPESTaylor, Xu, et al., 1998B
2.94 ± 0.10LPDJanousek, Brauman, et al., 1979Adiabatic EA: 3.18±0.25 eV; B
>2.30 ± 0.70EIAEThynne and MacNiel, 1971From C2H4; B
3.730 ± 0.050PDFeldman, 1970B
2.10 ± 0.30EIAELocht and Momigny, 1970From C2H2, C2H4; B
>2.79998EIAETrepka and Neuert, 1963From C2H4; B
2.64955SIPage and Goode, 1969The Magnetron method, lacking mass analysis, is not considered reliable.; B

Ionization energy determinations

IE (eV) Method Reference Comment
11.61 ± 0.07DERNorwood and Ng, 1989LL
11.7DERLias, Bartmess, et al., 1988LL
11.31 ± 0.13DEROno and Ng, 1981LLK
11.51DEROno and Ng, 1981Unpublished result of S.I.Miller and J.Berkowitz; LLK
11.96 ± 0.05DEROkabe and Dibeler, 1973LLK
11.96 ± 0.05DERDibeler, Walker, et al., 1973LLK
11.6 ± 0.5EIWyatt and Stafford, 1972LLK

Anion protonation reactions

C2H- + Hydrogen cation = Acetylene

By formula: C2H- + H+ = C2H2

Quantity Value Units Method Reference Comment
Deltar379. ± 5.kcal/molAVGN/AAverage of 8 values; Individual data points
Quantity Value Units Method Reference Comment
Deltar370. ± 5.kcal/molAVGN/AAverage of 7 values; Individual data points


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, . [all data]

Zhou, Garand, et al., 2007
Zhou, J.; Garand, E.; Neumark, D.M., Vibronic structure in C2H and C2D from anion slow electron velocity-map imaging spectroscopy, J. Chem. Phys., 2007, 127, 11, 114313, . [all data]

Ervin and Lineberger, 1991
Ervin, K.M.; Lineberger, W.C., Photoelectron Spectra of C2- and C2H-, J. Phys. Chem., 1991, 95, 3, 1167, . [all data]

Taylor, Xu, et al., 1998
Taylor, T.R.; Xu, C.S.; Neumark, D.M., Photoelectron spectra of the C2nH- (n=1-4) and C2nD- (n=1-3) anions, J. Chem. Phys., 1998, 108, 24, 10018-10026, . [all data]

Janousek, Brauman, et al., 1979
Janousek, B.K.; Brauman, J.I.; Simons, J., An experimental and theoretical determination of the electron affinity of the enhynyl radical HC2, J. Chem. Phys., 1979, 71, 2057. [all data]

Thynne and MacNiel, 1971
Thynne, J.C.J.; MacNiel, K.A.G., Negative ion formation by ethylene and 1,1-difluoroethylene, J. Phys. Chem., 1971, 75, 2584. [all data]

Feldman, 1970
Feldman, D., Photoablosung von Elektronen bei einigen Stabilen Negativen Ionen, Z. Naturfor., 1970, 25A, 621. [all data]

Locht and Momigny, 1970
Locht, R.; Momigny, J., Mass Spectrometric Determination of the Electron Affinities of Radicals, Chem. Phys. Lett., 1970, 6, 4, 273, . [all data]

Trepka and Neuert, 1963
Trepka, L.v.; Neuert, H., Uber die Entstehenung von Negativen Ionen aus einigen Kohlenwasserstoffen und Alkoholen durch Elektronenstoss, Z. Naturfor., 1963, 18A, 1295. [all data]

Page and Goode, 1969
Page, F.M.; Goode, G.C., Negative Ions and the Magnetron., Wiley, NY, 1969. [all data]

Norwood and Ng, 1989
Norwood, K.; Ng, C.Y., A state-selected study of the unimolecular decompoisition of C2H2+(A,B) using the photoion photoelectron coincidence method, J. Chem. Phys., 1989, 91, 2898. [all data]

Lias, Bartmess, et al., 1988
Lias, S.G.; Bartmess, J.E.; Liebman, J.F.; Holmes, J.L.; Levin, R.D.; Mallard, W.G., Gas-phase ion and neutral thermochemistry, J. Phys. Chem. Ref. Data, Suppl. 1, 1988, 17, 1-861. [all data]

Ono and Ng, 1981
Ono, Y.; Ng, C.Y., The heat of formation of C2H+, J. Chem. Phys., 1981, 74, 6985. [all data]

Okabe and Dibeler, 1973
Okabe, H.; Dibeler, V.H., Photon impact studies of C2HCN and CH3CN in the vacuum ultraviolet; heats of formation of C2H and CH3CN, J. Chem. Phys., 1973, 59, 2430. [all data]

Dibeler, Walker, et al., 1973
Dibeler, V.H.; Walker, J.A.; McCulloh, K.E., Observations on hot bands in the molecular and dissociative photoionization of acetylene and the heat of formation of the ethynyl ion, J. Chem. Phys., 1973, 59, 2264. [all data]

Wyatt and Stafford, 1972
Wyatt, J.R.; Stafford, F.E., Mass spectrometric determination of the heat of formation of ethynyl radical, C2H, and of some related species, J. Phys. Chem., 1972, 76, 1913. [all data]


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