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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Data at other public NIST sites:
- Gas Phase Kinetics Database
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Gas phase ion energetics data

Go To: Top, Vibrational and/or electronic energy levels, References, Notes

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

Vibrational and/or electronic energy levels

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

Data compiled by: Marilyn E. Jacox

State: X

Vib. sym.	No.	Approximate type of mode	cm^-1		Med.	Method	References


a'	1	OH stretch	3635.70		gas	LD	Petty and Moore, 1993
	1	OH stretch	3628.0	w m	Ne	IR	Forney, Jacox, et al., 2003
	1	OH stretch	3602.9		Ar	IR	Jacox, 1988
	1	OH stretch	3570.8		N₂	IR	Mielke, Olbert-Majkut, et al., 2003
	1	OH stretch	3456		CO	IR	Milligan and Jacox, 1971
	2	C=O stretch	1852.57		gas	DL	Sears, Fawzy, et al., 1992
	2	C=O stretch	1848.0	s	Ne	IR	Forney, Jacox, et al., 2003
	2	C=O stretch	1843.6		Ar	IR	Jacox, 1988
	2	C=O stretch	1837.8		N₂	IR	Mielke, Olbert-Majkut, et al., 2003
	2	C=O stretch	1833		CO	IR	Milligan and Jacox, 1971
	3	HOC bend	1194 ± 10		gas	PE	Johnson, Poad, et al., 2011
	3	HOC bend	1210.4	m	Ne	IR	Forney, Jacox, et al., 2003
	3	HOC bend	1211.2		Ar	IR	Jacox, 1988
	3	HOC bend	1241.1		N₂	IR	Mielke, Olbert-Majkut, et al., 2003
	3	HOC bend	1261		CO	IR	Milligan and Jacox, 1971
	4	C-O stretch	1048 ± 10		gas	PE	Johnson, Poad, et al., 2011
	4	C-O stretch	1050.4	w m	Ne	IR	Forney, Jacox, et al., 2003
	4	C-O stretch	1064.6		Ar	IR	Jacox, 1988
	4	C-O stretch	1062.8		N₂	IR	Mielke, Olbert-Majkut, et al., 2003
	4	C-O stretch	1077		CO	IR	Milligan and Jacox, 1971
	5	OCO bend	629 ± 5		gas	PE	Johnson, Poad, et al., 2011
	5	OCO bend	615		CO	IR	Milligan and Jacox, 1971
a	6	Torsion	508.1	w m	Ne	IR	Forney, Jacox, et al., 2003
	6	Torsion	515		Ar	IR	Jacox, 1988

Additional references: Jacox, 1994, page 167; Jacox, 1998, page 236; Radford, Wei, et al., 1992; Sears, Radford, et al., 1993; Petty and Moore, 1993, 2; Radford, Moore, et al., 1994; Oyama, Funato, et al., 2011

Notes

Weak

Medium

Strong

References

Go To: Top, Gas phase ion energetics data, Vibrational and/or electronic energy levels, 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]

Petty and Moore, 1993
Petty, J.T.; Moore, C.B., Transient Infrared Absorption Spectrum of the ν1 Fundamental of trans-HOCO, J. Mol. Spectrosc., 1993, 161, 1, 149, https://doi.org/10.1006/jmsp.1993.1223 . [all data]

Forney, Jacox, et al., 2003
Forney, D.; Jacox, M.E.; Thompson, W.E., Infrared spectra of trans-HOCO, HCOOH[sup +], and HCO[sub 2][sup -] trapped in solid neon, J. Chem. Phys., 2003, 119, 20, 10814, https://doi.org/10.1063/1.1621382 . [all data]

Jacox, 1988
Jacox, M.E., The vibrational spectrum of the t-HOCO free radical trapped in solid argon, J. Chem. Phys., 1988, 88, 8, 4598, https://doi.org/10.1063/1.453772 . [all data]

Mielke, Olbert-Majkut, et al., 2003
Mielke, Z.; Olbert-Majkut, A.; Tokhadze, K.G., Photolysis of the OC...HONO complex in low temperature matrices: Infrared detection and ab initio calculations of nitrosoformic acid, HOC(O)NO, J. Chem. Phys., 2003, 118, 3, 1364, https://doi.org/10.1063/1.1528897 . [all data]

Milligan and Jacox, 1971
Milligan, D.E.; Jacox, M.E., Infrared Spectrum and Structure of Intermediates in the Reaction of OH with CO, J. Chem. Phys., 1971, 54, 3, 927, https://doi.org/10.1063/1.1675022 . [all data]

Sears, Fawzy, et al., 1992
Sears, T.J.; Fawzy, W.M.; Johnson, P.M., Transient diode laser absorption spectroscopy of the ν2 fundamental of trans-HOCO and DOCO, J. Chem. Phys., 1992, 97, 6, 3996, https://doi.org/10.1063/1.462939 . [all data]

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

Jacox, 1998
Jacox, M.E., Vibrational and electronic energy levels of polyatomic transient molecules: supplement A, J. Phys. Chem. Ref. Data, 1998, 27, 2, 115-393, https://doi.org/10.1063/1.556017 . [all data]

Radford, Wei, et al., 1992
Radford, H.E.; Wei, W.; Sears, T.J., The rotational spectrum of trans-HOCO and DOCO, J. Chem. Phys., 1992, 97, 6, 3989, https://doi.org/10.1063/1.462938 . [all data]

Sears, Radford, et al., 1993
Sears, T.J.; Radford, H.E.; Moore, M.A., b-dipole transitions in trans-HOCO observed by far infrared laser magnetic resonance, J. Chem. Phys., 1993, 98, 9, 6624, https://doi.org/10.1063/1.465098 . [all data]

Petty and Moore, 1993, 2
Petty, J.T.; Moore, C.B., Transient infrared absorption spectrum of the ν1 fundamental of trans-DOCO, J. Chem. Phys., 1993, 99, 1, 47, https://doi.org/10.1063/1.465773 . [all data]

Radford, Moore, et al., 1994
Radford, H.E.; Moore, M.A.; Sears, T.J.; Grussdorf, J.; Nolte, J.; Temps, F., Far-Infrared Laser Magnetic Resonance of X2A´ trans-DOCO, J. Mol. Spectrosc., 1994, 165, 1, 137, https://doi.org/10.1006/jmsp.1994.1116 . [all data]

Oyama, Funato, et al., 2011
Oyama, T.; Funato, W.; Sumiyoshi, Y.; Endo, Y., Observation of the pure rotational spectra of trans- and cis-HOCO, J. Chem. Phys., 2011, 134, 17, 174303, https://doi.org/10.1063/1.3578179 . [all data]

Notes

Go To: Top, Gas phase ion energetics data, Vibrational and/or electronic energy levels, 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