Ethynyl radical

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Gas phase thermochemistry 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.

Quantity Value Units Method Reference Comment
Δfgas476.98kJ/molReviewChase, 1998Data last reviewed in March, 1967
Δfgas556. ± 8.kJ/molN/ATsang, 1996 
Quantity Value Units Method Reference Comment
gas,1 bar207.44J/mol*KReviewChase, 1998Data last reviewed in March, 1967

Gas Phase Heat Capacity (Shomate Equation)

Cp° = A + B*t + C*t2 + D*t3 + E/t2
H° − H°298.15= A*t + B*t2/2 + C*t3/3 + D*t4/4 − E/t + F − H
S° = A*ln(t) + B*t + C*t2/2 + D*t3/3 − E/(2*t2) + G
    Cp = heat capacity (J/mol*K)
    H° = standard enthalpy (kJ/mol)
    S° = standard entropy (J/mol*K)
    t = temperature (K) / 1000.

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Temperature (K) 298. to 1200.1200. to 6000.
A 33.4091639.29220
B 24.1133113.32081
C -6.600595-1.952364
D 0.2789120.086290
E -0.2594590.978203
F 465.1311464.3027
G 239.5148248.5949
H 476.9760476.9760
ReferenceChase, 1998Chase, 1998
Comment Data last reviewed in March, 1967 Data last reviewed in March, 1967

Gas phase ion energetics data

Go To: Top, Gas phase thermochemistry data, 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
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)753.kJ/molN/AHunter and Lias, 1998HL
Quantity Value Units Method Reference Comment
Gas basicity720.8kJ/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
Δr1580. ± 20.kJ/molAVGN/AAverage of 8 values; Individual data points
Quantity Value Units Method Reference Comment
Δr1550. ± 20.kJ/molAVGN/AAverage of 7 values; Individual data points

References

Go To: Top, Gas phase thermochemistry data, 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.

Chase, 1998
Chase, M.W., Jr., NIST-JANAF Themochemical Tables, Fourth Edition, J. Phys. Chem. Ref. Data, Monograph 9, 1998, 1-1951. [all data]

Tsang, 1996
Tsang, W., Heats of Formation of Organic Free Radicals by Kinetic Methods in Energetics of Organic Free Radicals, Martinho Simoes, J.A.; Greenberg, A.; Liebman, J.F., eds., Blackie Academic and Professional, London, 1996, 22-58. [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]

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, https://doi.org/10.1063/1.2768932 . [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, https://doi.org/10.1021/j100156a026 . [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, https://doi.org/10.1063/1.476462 . [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, https://doi.org/10.1016/0009-2614(70)85072-2 . [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]


Notes

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