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:
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Gas phase ion energetics data
Go To: Top, Constants of diatomic molecules, References, Notes
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
Protonation 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
Go To: Top, Gas phase ion energetics data, References, Notes
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 ion energetics 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.
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 ion energetics data, Constants of diatomic molecules, References
- Symbols used in this document:
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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