Carbon anion
- Formula: C2-
- Molecular weight: 24.0219
- IUPAC Standard InChI: InChI=1S/CH3/h1H3/q-1
- IUPAC Standard InChIKey: LGRLWUINFJPLSH-UHFFFAOYSA-N
- CAS Registry Number: 50802-47-6
- Chemical structure:
This structure is also available as a 2d Mol file or as a computed 3d SD file
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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.
Data compiled as indicated in comments:
B - John E. Bartmess
| Quantity | Value | Units | Method | Reference | Comment |
|---|---|---|---|---|---|
| ΔfH°gas | 119.3 ± 3.8 | kcal/mol | R-EA | Ervin, Gronert, et al., 1990 | B |
| ΔfH°gas | <197.5 ± 4.6 | kcal/mol | EIAE | Collin and Locht, 1970 | From ketene; B |
| Quantity | Value | Units | Method | Reference | Comment |
| S°gas,1 bar | 46.989 | cal/mol*K | Review | Chase, 1998 | Data last reviewed in December, 1969 |
Reaction 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.
Data compiled by: John E. Bartmess
Note: Please consider using the reaction search for this species. This page allows searching of all reactions involving this species. A general reaction search form is also available. Future versions of this site may rely on reaction search pages in place of the enumerated reaction displays seen below.
Individual Reactions
+
= C2H
| Quantity | Value | Units | Method | Reference | Comment |
|---|---|---|---|---|---|
| ΔrH° | >349.0 ± 3.6 | kcal/mol | D-EA | Arnold, Bradforth, et al., 1991 | gas phase |
| ΔrH° | <375.8 ± 2.3 | kcal/mol | G+TS | Schiff and Bohme, 1975 | gas phase; No reaction with acetylene |
| Quantity | Value | Units | Method | Reference | Comment |
| ΔrG° | >341.7 ± 3.8 | kcal/mol | H-TS | Arnold, Bradforth, et al., 1991 | gas phase |
| ΔrG° | <368.5 ± 2.0 | kcal/mol | IMRB | Schiff and Bohme, 1975 | gas phase; No reaction with acetylene |
Constants of diatomic molecules
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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 compiled by: Klaus P. Huber and Gerhard H. Herzberg
Data collected through July, 1976
| Symbol | Meaning |
|---|---|
| State | electronic state and / or symmetry symbol |
| Te | minimum electronic energy (cm-1) |
| ωe | vibrational constant – first term (cm-1) |
| ωexe | vibrational constant – second term (cm-1) |
| ωeye | vibrational constant – third term (cm-1) |
| Be | rotational constant in equilibrium position (cm-1) |
| αe | rotational constant – first term (cm-1) |
| γe | rotation-vibration interaction constant (cm-1) |
| De | centrifugal distortion constant (cm-1) |
| βe | rotational constant – first term, centrifugal force (cm-1) |
| re | internuclear distance (Å) |
| Trans. | observed transition(s) corresponding to electronic state |
| ν00 | position of 0-0 band (units noted in table) |
| State | Te | ωe | ωexe | ωeye | Be | αe | γe | De | βe | re | Trans. | ν00 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| a 4Σu+ | (19448) | (1074) 1 | (25) | (1.135) 1 | (0.0035) | (1.573) | ||||||
| B 2Σu+ | 18390.88 | 1968.73 Z | 14.433 | -0.324 | 1.87745 2 | 0.01776 | -0.00037 | 0.00000684 3 | 1.22330 | B ↔ X 4 V | 18483.98 Z | |
| ↳missing citation | ||||||||||||
| A 2Πu 5 | A ← X | |||||||||||
| ↳Lineberger and Patterson, 1972 | ||||||||||||
| X 2Σg+ | 0 | 1781.04 Z | 11.585 | -0.027 | 1.74685 | 0.0167 | 0.00000669 | 1.26821 | ||||
Notes
| 1 | Constants derived Bondybey and Brus, 1975 from the perturbations Herzberg and Lagerqvist, 1968 in B 2Σu+. Ab initio calculations by Barsuhn, 1974 and Thulstrup and Thulstrup, 1974 independently predict the existence of a 4Σu+ state slightly above B 2Σu+ with re and ωe values near those derived from the perturbations. |
| 2 | Small perturbations by a 4Σu+. |
| 3 | Dv= +[1.0(v+1/2) + 0.08(v+1.2)2]E-7. |
| 4 | The spectrum was observed in flash discharges in CH4 Herzberg and Lagerqvist, 1968, behind reflected shock waves [fel ~ 0.017 Cathro and Mackie, 1973], and in rare gas matrices Milligan and Jacox, 1969, Frosch, 1971, Bondybey and Nibler, 1972, missing citation, Brus and Bondybey, 1975. Conclusive proof that it belongs to C2- was supplied by two-photon photodetachment spectroscopy Lineberger and Patterson, 1972. Franck-Condon factors Singh and Maheshwari, 1971. |
| 5 | Fragments of absorption bands. |
| 6 | From D00(C2) and the electron affinities of C2 and of C(=1.268 eV). |
| 7 | Photodetachment threshold Feldman, 1970. |
References
Go To: Top, Gas phase thermochemistry data, Reaction thermochemistry data, Constants of diatomic molecules, Notes
Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.
Ervin, Gronert, et al., 1990
Ervin, K.M.; Gronert, S.; Barlow, S.E.; Gilles, M.K.; Harrison, A.G.; Bierbaum, V.M.; DePuy, C.H.; Lin, W.C.,
Bonds Strengths of Ethylene and Acetylene,
J. Am. Chem. Soc., 1990, 112, 15, 5750, https://doi.org/10.1021/ja00171a013
. [all data]
Collin and Locht, 1970
Collin, J.E.; Locht, R.,
Positive and negative ion formation in ketene by electron impact,
Intern. J. Mass Spectrom. Ion Phys., 1970, 3, 465. [all data]
Chase, 1998
Chase, M.W., Jr.,
NIST-JANAF Themochemical Tables, Fourth Edition,
J. Phys. Chem. Ref. Data, Monograph 9, 1998, 1-1951. [all data]
Arnold, Bradforth, et al., 1991
Arnold, D.W.; Bradforth, S.E.; Kitsopoulos, T.N.; Neumark, D.M.,
Vibrationally Resolved Spectra of C2-C11 by Anion Photoelectron Spectroscopy,
J. Chem. Phys., 1991, 95, 12, 8753, https://doi.org/10.1063/1.461211
. [all data]
Schiff and Bohme, 1975
Schiff, H.I.; Bohme, D.K.,
Flowing afterglow studies at York University,
Int. J. Mass Spectrom. Ion Phys., 1975, 16, 167. [all data]
Lineberger and Patterson, 1972
Lineberger, W.C.; Patterson, T.A.,
Two photon photodetachment spectroscopy: the C2--2Σ states,
Chem. Phys. Lett., 1972, 13, 40. [all data]
Bondybey and Brus, 1975
Bondybey, V.E.; Brus, L.E.,
Photophysics of C2-(B2Σu+) in rare gas lattices: vibrational relaxation through intermediate a4Σu+ levels,
J. Chem. Phys., 1975, 63, 2223. [all data]
Herzberg and Lagerqvist, 1968
Herzberg, G.; Lagerqvist, A.,
A new spectrum associated with diatomic carbon,
Can. J. Phys., 1968, 46, 2363. [all data]
Barsuhn, 1974
Barsuhn, J.,
Nonempirical calculations on the electronic spectrum of the molecular ion C2-,
J. Phys. B:, 1974, 7, 155. [all data]
Thulstrup and Thulstrup, 1974
Thulstrup, P.W.; Thulstrup, E.W.,
A theoretical investigation of the low-lying states of the C2- ion,
Chem. Phys. Lett., 1974, 26, 144. [all data]
Cathro and Mackie, 1973
Cathro, W.S.; Mackie, J.C.,
Oscillator strength of the C2-B2Σ - X2Σ transition: a shock-tube determination,
J. Chem. Soc. Faraday Trans. 2, 1973, 69, 237. [all data]
Milligan and Jacox, 1969
Milligan, D.E.; Jacox, M.E.,
Studies of the photoproduction of electrons in inert solid matrices. The electronic spectrum of the species C2-,
J. Chem. Phys., 1969, 51, 1952. [all data]
Frosch, 1971
Frosch, R.P.,
C2 and C2- spectra produced by the X irradiation of acetylene in rare-gas matrices,
J. Chem. Phys., 1971, 54, 2660. [all data]
Bondybey and Nibler, 1972
Bondybey, V.; Nibler, J.W.,
Laser excited fluorescence studies of matrix isolated C2-,
J. Chem. Phys., 1972, 56, 4719. [all data]
Brus and Bondybey, 1975
Brus, L.E.; Bondybey, V.E.,
Molecular ions and electron transport in rare gas lattices: C2- formation mechanism and X2Σg+ = B2Σu+ spectroscopy,
J. Chem. Phys., 1975, 63, 3123. [all data]
Singh and Maheshwari, 1971
Singh, I.D.; Maheshwari, R.C.,
Isotope/effect on Franck-Condon factors & r-centroids for the new (1Σu+-1Σg+) system of isotopic C2 molecule,
Indian J. Pure Appl. Phys., 1971, 9, 296. [all data]
Feldman, 1970
Feldman, D.,
Photoablosung von Elektronen bei einigen Stabilen Negativen Ionen,
Z. Naturfor., 1970, 25A, 621. [all data]
Notes
Go To: Top, Gas phase thermochemistry data, Reaction thermochemistry data, Constants of diatomic molecules, References
- Symbols used in this document:
S°gas,1 bar Entropy of gas at standard conditions (1 bar) ΔfH°gas Enthalpy of formation of gas at standard conditions 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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