Methanediylium anion
- Formula: CH2-
- Molecular weight: 14.0271
- CAS Registry Number: 50928-07-9
- Information on this page:
- Options:
Gas phase thermochemistry data
Go To: Top, Reaction thermochemistry data, Gas phase ion energetics data, Vibrational and/or electronic energy levels, 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
| Quantity | Value | Units | Method | Reference | Comment |
|---|---|---|---|---|---|
| ΔfH°gas | 78.47 ± 0.40 | kcal/mol | R-EA | Leopold, Murray, et al., 1985 | Singlet-triplet splitting of CH2 = 9.0 kcal |
| ΔfH°gas | <78.4 ± 9.2 | kcal/mol | EIAE | Collin and Locht, 1970 | From ketene |
| ΔfH°gas | <69.30 | kcal/mol | EIAE | Trepka and Neuert, 1963 | From CH4 |
Reaction thermochemistry data
Go To: Top, Gas phase thermochemistry data, Gas phase ion energetics data, Vibrational and/or electronic energy levels, 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
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
CH2- + =
| Quantity | Value | Units | Method | Reference | Comment |
|---|---|---|---|---|---|
| ΔrH° | 409.11 ± 0.41 | kcal/mol | D-EA | Leopold, Murray, et al., 1985 | gas phase; Singlet-triplet splitting of CH2 = 9.0 kcal |
| Quantity | Value | Units | Method | Reference | Comment |
| ΔrG° | 401.42 ± 0.48 | kcal/mol | H-TS | Leopold, Murray, et al., 1985 | gas phase; Singlet-triplet splitting of CH2 = 9.0 kcal |
Gas phase ion energetics data
Go To: Top, Gas phase thermochemistry data, Reaction thermochemistry data, Vibrational and/or electronic energy levels, 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
CH2- + =
| Quantity | Value | Units | Method | Reference | Comment |
|---|---|---|---|---|---|
| ΔrH° | 409.11 ± 0.41 | kcal/mol | D-EA | Leopold, Murray, et al., 1985 | gas phase; Singlet-triplet splitting of CH2 = 9.0 kcal |
| Quantity | Value | Units | Method | Reference | Comment |
| ΔrG° | 401.42 ± 0.48 | kcal/mol | H-TS | Leopold, Murray, et al., 1985 | gas phase; Singlet-triplet splitting of CH2 = 9.0 kcal |
Vibrational and/or electronic energy levels
Go To: Top, Gas phase thermochemistry data, Reaction thermochemistry data, 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: Marilyn E. Jacox
State: A
| Energy (cm-1) |
Med. | Transition | λmin (nm) |
λmax (nm) |
References | ||
|---|---|---|---|---|---|---|---|
| Td = 5260 ± 50 | gas | Leopold, Murray, et al., 1985 | |||||
| Bunker and Sears, 1985 | |||||||
State: X
| Vib. sym. |
No. | Approximate type of mode |
cm-1 | Med. | Method | References | |
|---|---|---|---|---|---|---|---|
| a1 | 2 | Bend | 1230 ± 30 | gas | PE | Leopold, Murray, et al., 1985 Bunker and Sears, 1985 | |
Additional references: Jacox, 1994, page 21
Notes
| d | Photodissociation threshold |
References
Go To: Top, Gas phase thermochemistry data, Reaction thermochemistry data, Gas phase ion energetics data, Vibrational and/or electronic energy levels, Notes
Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.
Leopold, Murray, et al., 1985
Leopold, D.G.; Murray, K.K.; Miller, A.E.S.; Lineberger, W.C.,
Methylene: A study of the X3B1 and the 1A1 states by photoelectron spectroscopy of CH2- and CD2-,
J. Chem. Phys., 1985, 83, 4849. [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]
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]
Bunker and Sears, 1985
Bunker, P.R.; Sears, T.J.,
Analysis of the laser photoelectron spectrum of CH-2,
J. Chem. Phys., 1985, 83, 10, 4866, https://doi.org/10.1063/1.449747
. [all data]
Jacox, 1994
Jacox, M.E.,
Vibrational and electronic energy levels of polyatomic transient molecules, American Chemical Society, Washington, DC, 1994, 464. [all data]
Notes
Go To: Top, Gas phase thermochemistry data, Reaction thermochemistry data, Gas phase ion energetics data, Vibrational and/or electronic energy levels, References
- Symbols used in this document:
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
- The National Institute of Standards and Technology (NIST) uses its best efforts to deliver a high quality copy of the Database and to verify that the data contained therein have been selected on the basis of sound scientific judgment. However, NIST makes no warranties to that effect, and NIST shall not be liable for any damage that may result from errors or omissions in the Database.
- Customer support for NIST Standard Reference Data products.