Selected ATcT [1, 2] enthalpy of formation based on version 1.176 of the Thermochemical Network [3]

This version of ATcT results[3] was generated by additional expansion of version 1.172 to include species related to Criegee intermediates that are involved in several ongoing studies[4].

Oxomethylium

Formula: [HCO]+ (g)

CAS RN: 17030-74-9

ATcT ID: 17030-74-9*0

SMILES: [CH+]=O

InChI: InChI=1S/CHO/c1-2/h1H/q+1

InChIKey: XPRMKTHGXOVKEH-UHFFFAOYSA-N

Hills Formula: C1H1O1+

2D Image:

Aliases: Oxomethylium; Methylidyneoxidanium; Oxomethylium ion; Oxomethylium cation; Oxomethylium ion (1+); Formylium; Formylium ion; Formylium cation; Formylium ion (1+); Formyl cation; Formyl ion (1+); Hydrogen carbonyl cation; Hydrogen carbonyl ion (1+); Hydrogen carbonyl monocation; [HCO]+; HCO+; [CHO]+; CHO+; [OCH]+; OCH+

Relative Molecular Mass: 29.01749 ± 0.00086

Δ_fH°(0 K)	Δ_fH°(298.15 K)	Uncertainty	Units
827.763	827.179	± 0.095	kJ/mol

3D Image of [HCO]+ (g)

spin ON spin OFF

Top contributors to the provenance of Δ_fH° of [HCO]+ (g)

The 20 contributors listed below account only for 62.3% of the provenance of Δ_fH° of [HCO]+ (g).
A total of 272 contributors would be needed to account for 90% of the provenance.

Please note: The list is limited to 20 most important contributors or, if less, a number sufficient to account for 90% of the provenance. The Reference acts as a further link to the relevant references and notes for the measurement. The Measured Quantity is normaly given in the original units; in cases where we have reinterpreted the original measurement, the listed value may differ from that given by the authors. The quoted uncertainty is the a priori uncertainty used as input when constructing the initial Thermochemical Network, and corresponds either to the value proposed by the original authors or to our estimate; if an additional multiplier is given in parentheses immediately after the prior uncertainty, it corresponds to the factor by which the prior uncertainty needed to be multiplied during the ATcT analysis in order to make that particular measurement consistent with the prevailing knowledge contained in the Thermochemical Network.

Contribution (%)	TN ID	Reaction	Measured Quantity	Reference
20.3	3098.11	[HCO]+ (g) → H+ (g) + CO (g)	Δ_rH°(0 K) = 586.51 ± 0.2 kJ/mol	Czako 2008
10.2	3026.3	CO (g) + H2 (g) → CH2O (g)	Δ_rH°(0 K) = 8.39 ± 0.28 kJ/mol	Czako 2009
3.0	3100.9	CO (g) + [NH4]+ (g) → [HCO]+ (g) + NH3 (g)	Δ_rH°(0 K) = 259.89 ± 0.3 kJ/mol	Czako 2008
2.9	3025.7	2 CH2O (g) → CH4 (g) + CO2 (g)	Δ_rH°(0 K) = -59.44 ± 0.25 kcal/mol	Karton 2006
2.9	3025.8	2 CH2O (g) → CH4 (g) + CO2 (g)	Δ_rH°(0 K) = -59.44 ± 0.25 kcal/mol	Karton 2006
2.5	3006.1	[CH2OH]+ (g) → CH2O (g) + H+ (g)	Δ_rH°(0 K) = 704.98 ± 0.39 kJ/mol	Czako 2009
2.3	3091.9	HCO (g) → H (g) + O (g) + C (g)	Δ_rH°(0 K) = 1132.68 ± 0.56 kJ/mol	Harding 2008
2.0	3025.6	2 CH2O (g) → CH4 (g) + CO2 (g)	Δ_rH°(0 K) = -59.52 ± 0.30 kcal/mol	Karton 2006
1.6	3028.1	CH2O (g) + O2 (g) → CO2 (g) + H2O (cr,l)	Δ_rH°(299.65 K) = -570.69 ± 0.40 (×1.756) kJ/mol	Fletcher 1970, note std dev
1.5	1666.8	[NH4]+ (g) → NH3 (g) + H+ (g)	Δ_rH°(0 K) = 846.40 ± 0.3 kJ/mol	Czako 2008
1.5	3091.7	HCO (g) → H (g) + O (g) + C (g)	Δ_rH°(0 K) = 1133.05 ± 0.70 kJ/mol	Harding 2008
1.4	2286.9	C (graphite) + CO2 (g) → 2 CO (g)	Δ_rG°(1165 K) = -33.545 ± 0.058 kJ/mol	Smith 1946, note COf, 3rd Law
1.3	3091.8	HCO (g) → H (g) + O (g) + C (g)	Δ_rH°(0 K) = 1132.53 ± 0.74 kJ/mol	Harding 2008
1.2	3091.6	HCO (g) → H (g) + O (g) + C (g)	Δ_rH°(0 K) = 1132.11 ± 0.75 (×1.022) kJ/mol	Tajti 2004, est unc
1.2	3101.11	HCO (g) → H (g) + CO (g)	Δ_rH°(0 K) = 60.2 ± 0.8 kJ/mol	Marenich 2003
1.1	3017.10	CH2O (g) → C (g) + 2 H (g) + O (g)	Δ_rH°(0 K) = 1495.36 ± 0.80 kJ/mol	Feller 2018a
1.1	3025.4	2 CH2O (g) → CH4 (g) + CO2 (g)	Δ_rH°(0 K) = -59.37 ± 0.40 kcal/mol	Boese 2004
1.1	3025.5	2 CH2O (g) → CH4 (g) + CO2 (g)	Δ_rH°(0 K) = -59.52 ± 0.40 kcal/mol	Karton 2006
1.0	3091.12	HCO (g) → H (g) + O (g) + C (g)	Δ_rH°(0 K) = 1132.50 ± 0.84 kJ/mol	Harding 2008
1.0	3091.10	HCO (g) → H (g) + O (g) + C (g)	Δ_rH°(0 K) = 1132.87 ± 0.84 kJ/mol	Harding 2008

Top 10 species with enthalpies of formation correlated to the Δ_fH° of [HCO]+ (g)

Please note: The correlation coefficients are obtained by renormalizing the off-diagonal elements of the covariance matrix by the corresponding variances.
The correlation coefficient is a number from -1 to 1, with 1 representing perfectly correlated species, -1 representing perfectly anti-correlated species, and 0 representing perfectly uncorrelated species.

Correlation Coefficent (%)	Species Name	Formula	Δ_fH°(0 K)	Δ_fH°(298.15 K)	Uncertainty	Units	Relative Molecular Mass	ATcT ID
99.8	Formyl	HCO (g)	41.388	41.762	± 0.094	kJ/mol	29.01804 ± 0.00086	2597-44-6*0
99.4	Formaldehyde	CH2O (g, triplet)	196.008	192.706	± 0.094	kJ/mol	30.02598 ± 0.00087	50-00-0*1
99.4	Formaldehyde	CH2O (g, ortho singlet)	-105.256	-109.222	± 0.094	kJ/mol	30.02598 ± 0.00087	50-00-0*22
99.4	Formaldehyde	CH2O (g, para singlet)	-105.382	-109.223	± 0.094	kJ/mol	30.02598 ± 0.00087	50-00-0*21
99.4	Formaldehyde	CH2O (g, singlet)	-105.382	-109.223	± 0.094	kJ/mol	30.02598 ± 0.00087	50-00-0*2
99.4	Formaldehyde	CH2O (g)	-105.382	-109.223	± 0.094	kJ/mol	30.02598 ± 0.00087	50-00-0*0
98.1	Formaldehyde cation	[CH2O]+ (g)	944.859	941.238	± 0.096	kJ/mol	30.02543 ± 0.00087	54288-05-0*0
43.3	Formaldehyde	CH2O (aq, unhydrol)		-165.65	± 0.22	kJ/mol	30.02598 ± 0.00087	50-00-0*1000
22.7	Hydroxymethylene	HCOH (g, trans)	112.70	108.93	± 0.27	kJ/mol	30.02598 ± 0.00087	19710-56-6*1
22.7	Hydroxymethylene	HCOH (g)	112.70	108.95	± 0.27	kJ/mol	30.02598 ± 0.00087	19710-56-6*0

Most Influential reactions involving [HCO]+ (g)

Please note: The list, which is based on a hat (projection) matrix analysis, is limited to no more than 20 largest influences.

Influence Coefficient	TN ID	Reaction	Measured Quantity	Reference
0.999	3092.1	HCO (g) → [HCO]+ (g)	Δ_rH°(0 K) = 65735.9 ± 0.5 cm-1	Mayer 1995, Foltynowicz 2001
0.442	3100.9	CO (g) + [NH4]+ (g) → [HCO]+ (g) + NH3 (g)	Δ_rH°(0 K) = 259.89 ± 0.3 kJ/mol	Czako 2008
0.230	2485.3	[C2H7]+ (g) + CO (g) → [HCO]+ (g) + CH3CH3 (g)	Δ_rG°(298.15 K) = 1.43 ± 0.3 kcal/mol	Mackay 1981, 3rd Law, note unc5
0.218	3098.11	[HCO]+ (g) → H+ (g) + CO (g)	Δ_rH°(0 K) = 586.51 ± 0.2 kJ/mol	Czako 2008
0.156	3122.4	[HCO]+ (g) → [COH]+ (g)	Δ_rH°(0 K) = 37.81 ± 0.5 kcal/mol	Martin 1993
0.138	9715.7	[OS(OH)O]+ (g) + CO (g) → OS(O)O (g) + [HCO]+ (g)	Δ_rH°(0 K) = -0.27 ± 0.8 kcal/mol	Ruscic W1RO
0.123	1218.1	[HBrH]+ (g) + CO (g) → [HCO]+ (g) + HBr (g)	Δ_rH°(300 K) = -2.0 ± 2 kcal/mol	Tichy 1989, 2nd Law, est unc
0.119	3122.5	[HCO]+ (g) → [COH]+ (g)	Δ_rH°(0 K) = 13224 ± 200 cm-1	Mladenovic 1998, est unc
0.108	3122.3	[HCO]+ (g) → [COH]+ (g)	Δ_rH°(0 K) = 37.78 ± 0.6 kcal/mol	Martin 1993
0.088	9715.4	[OS(OH)O]+ (g) + CO (g) → OS(O)O (g) + [HCO]+ (g)	Δ_rH°(0 K) = -0.15 ± 1.0 kcal/mol	Ruscic G4
0.079	3122.8	[HCO]+ (g) → [COH]+ (g)	Δ_rH°(0 K) = 38.12 ± 0.7 kcal/mol	Grunenberg 2003, Ruscic G3B3, est unc
0.068	2385.2	[CH5]+ (g) + CO (g) → [HCO]+ (g) + CH4 (g)	Δ_rH°(441 K) = -11.5 ± 0.4 kcal/mol	Szulejko 1993, 2nd Law, note unc5
0.061	9715.3	[OS(OH)O]+ (g) + CO (g) → OS(O)O (g) + [HCO]+ (g)	Δ_rH°(0 K) = -1.11 ± 1.2 kcal/mol	Ruscic G3X
0.061	3122.6	[HCO]+ (g) → [COH]+ (g)	Δ_rH°(0 K) = 37.66 ± 0.8 kcal/mol	Yamaguchi 1994, est unc
0.052	9715.6	[OS(OH)O]+ (g) + CO (g) → OS(O)O (g) + [HCO]+ (g)	Δ_rH°(0 K) = -1.23 ± 1.3 kcal/mol	Ruscic CBS-n
0.049	3107.2	HC(O)OH (g, syn) → [HCO]+ (g) + OH (g)	Δ_rH°(0 K) = 12.81 ± 0.01 eV	Traeger 1985, AE corr
0.045	4750.2	HC(O)OH (g) → [HCO]+ (g) + OH (g)	Δ_rH°(0 K) = 1235.7 ± 1.0 kJ/mol	Shuman 2010a, Bomble 2006
0.044	2385.1	[CH5]+ (g) + CO (g) → [HCO]+ (g) + CH4 (g)	Δ_rG°(441 K) = -8.6 ± 0.5 kcal/mol	Szulejko 1993, 3rd Law, note unc5
0.042	2485.2	[C2H7]+ (g) + CO (g) → [HCO]+ (g) + CH3CH3 (g)	Δ_rG°(337 K) = 1.7 ± 0.7 kcal/mol	Szulejko 1993, 3rd Law, note unc5
0.041	2001.1	[HONO]+ (g) + CO (g) → [HCO]+ (g) + ONO (g)	Δ_rG°(298.15 K) = -2 ± 2 kcal/mol	Polley 1984

References

1		B. Ruscic, R. E. Pinzon, M. L. Morton, G. von Laszewski, S. Bittner, S. G. Nijsure, K. A. Amin, M. Minkoff, and A. F. Wagner, Introduction to Active Thermochemical Tables: Several "Key" Enthalpies of Formation Revisited. J. Phys. Chem. A 108, 9979-9997 (2004) [DOI: 10.1021/jp047912y]
2		B. Ruscic, R. E. Pinzon, G. von Laszewski, D. Kodeboyina, A. Burcat, D. Leahy, D. Montoya, and A. F. Wagner, Active Thermochemical Tables: Thermochemistry for the 21^st Century. J. Phys. Conf. Ser. 16, 561-570 (2005) [DOI: 10.1088/1742-6596/16/1/078]
3		B. Ruscic and D. H. Bross, Active Thermochemical Tables (ATcT) values based on ver. 1.176 of the Thermochemical Network (2024); available at ATcT.anl.gov
4		T. L. Nguyen et al, ongoing studies (2024)
5		B. Ruscic, Uncertainty Quantification in Thermochemistry, Benchmarking Electronic Structure Computations, and Active Thermochemical Tables. Int. J. Quantum Chem. 114, 1097-1101 (2014) [DOI: 10.1002/qua.24605]
6		B. Ruscic and D. H. Bross, Thermochemistry Computer Aided Chem. Eng. 45, 3-114 (2019) [DOI: 10.1016/B978-0-444-64087-1.00001-2]

Formula

The aggregate state is given in parentheses following the formula, such as: g - gas-phase, cr - crystal, l - liquid, etc.

Uncertainties

The listed uncertainties correspond to estimated 95% confidence limits, as customary in thermochemistry (see, for example, Ruscic [5] and Ruscic and Bross[6]).
Note that an uncertainty of ± 0.000 kJ/mol indicates that the estimated uncertainty is < ± 0.000₅ kJ/mol.

Website Functionality Credits

The reorganization of the website was developed and implemented by David H. Bross (ANL).
The find function is based on the complete Species Dictionary entries for the appropriate version of the ATcT TN.
The molecule images are rendered by Indigo-depict.
The XYZ renderings are based on Jmol: an open-source Java viewer for chemical structures in 3D. http://www.jmol.org/.

Acknowledgement

This work was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences under Contract No. DE-AC02-06CH11357.