Hydrocarboxyl radical

Formula: CHO₂
Molecular weight: 45.0174
IUPAC Standard InChI: InChI=1S/CHO2/c2-1-3/h(H,2,3)
IUPAC Standard InChIKey: ORTFAQDWJHRMNX-UHFFFAOYSA-N
CAS Registry Number: 2564-86-5
Chemical structure:
This structure is also available as a 2d Mol file or as a computed 3d SD file
The 3d structure may be viewed using Java or Javascript.
Isotopologues:
- Hydroxycarbonyl-d1
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Information on this page:
Other data available:
- Vibrational and/or electronic energy levels
Data at other public NIST sites:
- Gas Phase Kinetics Database
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Gas phase ion energetics data

Data evaluated as indicated in comments:
HL - Edward P. Hunter and Sharon G. Lias

Data compiled as indicated in comments:
LL - Sharon G. Lias and Joel F. Liebman
B - John E. Bartmess

View reactions leading to CHO₂⁺ (ion structure unspecified)

Quantity	Value	Units	Method	Reference	Comment
Proton affinity (review)	149.0	kcal/mol	N/A	Hunter and Lias, 1998	HL
Quantity	Value	Units	Method	Reference	Comment
Gas basicity	141.2	kcal/mol	N/A	Hunter and Lias, 1998	HL
Quantity	Value	Units	Method	Reference	Comment
Δ_fH°_{(+) ion}	143. ± 2.	kcal/mol	N/A	N/A
Quantity	Value	Units	Method	Reference	Comment
Δ_fH_{(+) ion,0K}	141. ± 2.	kcal/mol	N/A	N/A

Electron affinity determinations

EA (eV)	Method	Reference	Comment
1.510 ± 0.010	LPES	Johnson, Harding, et al., 2011	trans isomer. See Wang, Li, et al., 2014 for computational analysis; B
1.380 ± 0.010	LPES	Johnson, Harding, et al., 2011	cis isomer; B
3.4961 ± 0.0010	LPES	Garand, Klein, et al., 2010	B
1.18	LPES	Lu, Hu, et al., 2007	Stated EA is Vertical Detachment Energy. See also Johnson and Continetti, 2010 for cooled ions (same EA); B
2.180 ± 0.020	LPES	Clements, Continetti, et al., 2002	B
3.498 ± 0.015	LPES	Kim, Bradforth, et al., 1995	dHacid(0K) = 344.67±0.62 kcal/mol; B
3.54 ± 0.11	D-EA	Caldwell, Renneboog, et al., 1989	B

Ionization energy determinations

IE (eV)	Method	Reference	Comment
8.20	DER	Berkowitz, Ellison, et al., 1994	LL
8.486 ± 0.012	PI	Ruscic, Schwartz, et al., 1989	LL

References

Go To: Top, Gas phase ion energetics data, Notes

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]

Johnson, Harding, et al., 2011
Johnson, C.J.; Harding, M.E.; Poad, B.L.J.; Stanton, J.F.; Continetti, R.E., Electron Affinities, Well Depths, and Vibrational Spectroscopy of cis- and trans-HOCO, J. Am. Chem. Soc., 2011, 133, 49, 19606-19609, https://doi.org/10.1021/ja207724f . [all data]

Wang, Li, et al., 2014
Wang, J.; Li, J.; Ma, J.Y.; Guo, H., Full-dimensional characterization of photoelectron spectra of HOCO- and DOCO- and tunneling facilitated decay of HOCO prepared by anion photodetachment, Journal Of Chemical Physics, 2014, 140, 18, 184314, https://doi.org/10.1063/1.4874975 . [all data]

Garand, Klein, et al., 2010
Garand, E.; Klein, K.; Stanton, J.F.; Zhou, J.; Yacovitch, T.I.; Neumark, D.M., Vibronic Structure of the Formyloxyl Radical (HCO2) via Slow Photoelectron Velocity-Map Imaging Spectroscopy and Model Hamiltonian Calculations, J. Phys. Chem. A, 2010, 114, 3, 1374-1383, https://doi.org/10.1021/jp9067894 . [all data]

Lu, Hu, et al., 2007
Lu, Z.; Hu, Q.C.; Oakman, J.E.; Continetti, R.E., Dynamics on the HOCO potential energy surface studied by dissociative photodetachment of HOCO- and DOCO-, J. Chem. Phys., 2007, 126, 19, 194305, https://doi.org/10.1063/1.2731787 . [all data]

Johnson and Continetti, 2010
Johnson, C.J.; Continetti, R.E., Dissociative Photodetachment Studies of Cooled HOCO- Anions Revealing Dissociation Below the Barrier to H + CO2, J. Phys. Chem. Lett., 2010, 1, 12, 1895-1899, https://doi.org/10.1021/jz100621k . [all data]

Clements, Continetti, et al., 2002
Clements, T.G.; Continetti, R.E.; Francisco, J.S., Exploring the OH+CO - H+CO2 potential surface via dissociative photodetachment of (HOCO)(-), J. Chem. Phys., 2002, 117, 14, 6478-6488, https://doi.org/10.1063/1.1505439 . [all data]

Kim, Bradforth, et al., 1995
Kim, E.H.; Bradforth, S.E.; Arnold, D.W.; Metz, R.B.; Neumark, D.M., Study of HCO2 and DCO2 by Negative Ion Photoelectron Spectroscopy, J. Chem. Phys., 1995, 103, 18, 7801, https://doi.org/10.1063/1.470196 . [all data]

Caldwell, Renneboog, et al., 1989
Caldwell, G.; Renneboog, R.; Kebarle, P., Gas Phase Acidities of Aliphatic Carboxylic Acids, Based on Measurements of Proton Transfer Equilibria, Can. J. Chem., 1989, 67, 4, 661, https://doi.org/10.1139/v89-092 . [all data]

Berkowitz, Ellison, et al., 1994
Berkowitz, J.; Ellison, G.B.; Gutman, D., Three methods to measure RH bond energies, J. Phys. Chem., 1994, 98, 2744. [all data]

Ruscic, Schwartz, et al., 1989
Ruscic, B.; Schwartz, M.; Berkowitz, J., A photoionization study of the COOH species, J. Chem. Phys., 1989, 91, 6780. [all data]

Notes

Go To: Top, Gas phase ion energetics data, References

Symbols used in this document:

EA Electron affinity

Δ_fH_{(+) ion,0K} Enthalpy of formation of positive ion at 0K
Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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EA	Electron affinity
Δ_fH_{(+) ion,0K}	Enthalpy of formation of positive ion at 0K