Selected ATcT [1, 2] enthalpy of formation based on version 1.124 of the Thermochemical Network [3]

This version of ATcT results was generated by additional expansion of version 1.122x [4] to include additional information relevant to the study of thermophysical and thermochemical properties of CH2 and CH3 using nonrigid rotor anharmonic oscillator (NRRAO) partition functions [5], the development and benchmarking of a state-of-the-art computational approach that aims to reproduce total atomization energies of small molecules within 10–15 cm^-1 [6], as well as the study of the reversible reaction C₂H₃ + H₂ ⇌ C₂H₄ + H ⇌ C₂H₅ [7]

Methane cation

Formula: [CH4]+ (g)

CAS RN: 20741-88-2

ATcT ID: 20741-88-2*0

SMILES: [CH4+]

InChI: InChI=1S/CH4/h1H4/q+1

InChIKey: DEMLYXWOPCFOLG-UHFFFAOYSA-N

Hills Formula: C1H4+

2D Image:

Aliases: [CH4]+; Methane cation; Methane ion (1+)

Relative Molecular Mass: 16.04191 ± 0.00085

Δ_fH°(0 K)	Δ_fH°(298.15 K)	Uncertainty	Units
1150.679	1144.296	± 0.061	kJ/mol

3D Image of [CH4]+ (g)

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Top contributors to the provenance of Δ_fH° of [CH4]+ (g)

The 20 contributors listed below account only for 76.9% of the provenance of Δ_fH° of [CH4]+ (g).
A total of 156 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
35.3	2240.1	CH4 (g) → [CH4]+ (g)	Δ_rH°(0 K) = 101752.2 ± 3.0 cm-1	Worner 2007, note unc
31.7	2245.1	2 H2 (g) + C (graphite) → CH4 (g)	Δ_rG°(1165 K) = 37.521 ± 0.068 kJ/mol	Smith 1946, note COf, 3rd Law
1.7	120.2	1/2 O2 (g) + H2 (g) → H2O (cr,l)	Δ_rH°(298.15 K) = -285.8261 ± 0.040 kJ/mol	Rossini 1939, Rossini 1931, Rossini 1931b, note H2Oa, Rossini 1930
1.5	2244.4	CH4 (g) + 2 O2 (g) → CO2 (g) + 2 H2O (cr,l)	Δ_rH°(298.15 K) = -890.61 ± 0.21 kJ/mol	Dale 2002
1.0	2244.6	CH4 (g) + 2 O2 (g) → CO2 (g) + 2 H2O (cr,l)	Δ_rH°(298.15 K) = -890.44 ± 0.26 kJ/mol	GOMB Ref Calorimeter, Alexandrov 2002
0.5	2244.1	CH4 (g) + 2 O2 (g) → CO2 (g) + 2 H2O (cr,l)	Δ_rH°(303.15 K) = -889.849 ± 0.350 kJ/mol	Rossini 1931a, Rossini 1931b, Prosen 1945, Rossini 1940, note CH4
0.5	2244.5	CH4 (g) + 2 O2 (g) → CO2 (g) + 2 H2O (cr,l)	Δ_rH°(298.15 K) = -890.43 ± 0.35 kJ/mol	Alexandrov 2002a, Alexandrov 2002
0.4	2149.2	CO (g) → C+ (g) + O (g)	Δ_rH°(0 K) = 22.3713 ± 0.0015 eV	Ng 2007
0.4	2101.7	C (graphite) + O2 (g) → CO2 (g)	Δ_rH°(298.15 K) = -393.464 ± 0.024 kJ/mol	Hawtin 1966, note CO2e
0.3	2244.2	CH4 (g) + 2 O2 (g) → CO2 (g) + 2 H2O (cr,l)	Δ_rH°(298.15 K) = -890.699 ± 0.430 kJ/mol	Pittam 1972, note CH4a
0.3	2257.13	CH3 (g) → C (g) + 3 H (g)	Δ_rH°(0 K) = 289.11 ± 0.10 kcal/mol	Feller 2016, note unc2
0.3	3615.1	4 CH4 (g) → CH3CHCCH2 (g) + 5 H2 (g)	Δ_rH°(0 K) = 442.41 ± 2.00 kJ/mol	Klippenstein 2017
0.3	3481.1	4 CH4 (g) → CH(CH3)3 (g) + 3 H2 (g)	Δ_rH°(0 K) = 160.33 ± 2.00 kJ/mol	Klippenstein 2017
0.3	3564.1	4 CH4 (g) → CH2CHCH2CH3 (g) + 4 H2 (g)	Δ_rH°(0 K) = 287.51 ± 2.00 kJ/mol	Klippenstein 2017
0.3	3473.1	4 CH4 (g) → CH3CH2CH2CH3 (g) + 3 H2 (g)	Δ_rH°(0 K) = 167.76 ± 2.00 kJ/mol	Klippenstein 2017
0.2	3541.1	4 CH4 (g) → CH2C(CH3)2 (g) + 4 H2 (g)	Δ_rH°(0 K) = 270.66 ± 2.00 kJ/mol	Klippenstein 2017
0.2	3586.1	4 CH4 (g) → CH2CHCHCH2 (g) + 5 H2 (g)	Δ_rH°(0 K) = 391.17 ± 2.00 kJ/mol	Klippenstein 2017
0.2	3548.1	4 CH4 (g) → CH3CHCHCH3 (g, trans) + 4 H2 (g)	Δ_rH°(0 K) = 275.78 ± 2.00 kJ/mol	Klippenstein 2017
0.2	3595.1	4 CH4 (g) → CH3CCCH3 (g) + 5 H2 (g)	Δ_rH°(0 K) = 425.36 ± 2.00 kJ/mol	Klippenstein 2017
0.2	2299.1	CH3 (g) → CH2 (g, triplet) + H (g)	Δ_rH°(0 K) = 109.26 ± 0.08 kcal/mol	Feller 2016, est unc, note unc2

Top 10 species with enthalpies of formation correlated to the Δ_fH° of [CH4]+ (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
80.1	Methane	CH4 (g)	-66.551	-74.520	± 0.048	kJ/mol	16.04246 ± 0.00085	74-82-8*0
77.5	Methylium	[CH3]+ (g)	1099.345	1095.402	± 0.049	kJ/mol	15.03397 ± 0.00083	14531-53-4*0
70.0	Methyl	CH3 (g)	149.872	146.471	± 0.053	kJ/mol	15.03452 ± 0.00083	2229-07-4*0
27.1	Carbon	C (g)	711.404	716.889	± 0.044	kJ/mol	12.01070 ± 0.00080	7440-44-0*0
27.1	Carbon	C (g, triplet)	711.404	716.889	± 0.044	kJ/mol	12.01070 ± 0.00080	7440-44-0*1
27.1	Carbon cation	C+ (g)	1797.857	1803.455	± 0.044	kJ/mol	12.01015 ± 0.00080	14067-05-1*0
27.1	Carbon	C (g, quintuplet)	1114.967	1120.114	± 0.044	kJ/mol	12.01070 ± 0.00080	7440-44-0*3
27.1	Carbon	C (g, singlet)	833.335	838.482	± 0.044	kJ/mol	12.01070 ± 0.00080	7440-44-0*2
27.1	Carbon dication	[C]+2 (g)	4150.474	4155.620	± 0.044	kJ/mol	12.00960 ± 0.00080	16092-61-8*0
27.0	Carbon anion	C- (g)	589.628	594.774	± 0.044	kJ/mol	12.01125 ± 0.00080	14337-00-9*0

Most Influential reactions involving [CH4]+ (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
0.988	2240.1	CH4 (g) → [CH4]+ (g)	Δ_rH°(0 K) = 101752.2 ± 3.0 cm-1	Worner 2007, note unc
0.007	2250.1	[CH4]+ (g) + H2 (g) → [CH5]+ (g) + H (g)	Δ_rH°(0 K) = -12.7 ± 5.2 kJ/mol	Wang 2005
0.005	2240.10	CH4 (g) → [CH4]+ (g)	Δ_rH°(0 K) = 12.616 ± 0.005 eV	Rabalais 1971, est unc
0.003	2240.4	CH4 (g) → [CH4]+ (g)	Δ_rH°(0 K) = 101781 ± 50 cm-1	Berkowitz 1987
0.001	2240.5	CH4 (g) → [CH4]+ (g)	Δ_rH°(0 K) = 12.615 ± 0.010 eV	Chupka 1971
0.001	2256.1	[CH4]+ (g) + [CH3CH2]+ (g) + 2 CH4 (g) + H2 (g) → 2 [CH5]+ (g) + CH3 (g) + CH3CH3 (g)	Δ_rG°(298.15 K) = 0. ± 6 kcal/mol	Munson 1965, est unc
0.001	2249.1	[CH4]+ (g) + CH4 (g) → [CH5]+ (g) + CH3 (g)	Δ_rH°(0 K) = -1.78 ± 3 kcal/mol	Hess 1990, est unc
0.000	2240.8	CH4 (g) → [CH4]+ (g)	Δ_rH°(0 K) = 12.63 ± 0.02 eV	Potts 1972a, est unc
0.000	2241.4	CH4 (g) → [CH4]+ (g)	Δ_rH°(0 K) = 12.640 ± 0.022 (×1.114) eV	Boese 2004
0.000	2241.5	CH4 (g) → [CH4]+ (g)	Δ_rH°(0 K) = 12.617 ± 0.035 eV	Lau 2006a
0.000	2241.2	CH4 (g) → [CH4]+ (g)	Δ_rH°(0 K) = 12.642 ± 0.040 eV	Parthiban 2001
0.000	2241.3	CH4 (g) → [CH4]+ (g)	Δ_rH°(0 K) = 12.643 ± 0.040 eV	Parthiban 2001
0.000	2403.1	CH2CH2 (g) → [CH4]+ (g) + C- (g)	Δ_rH°(0 K) = 17.40 ± 0.16 eV	Plessis 1987
0.000	2241.1	CH4 (g) → [CH4]+ (g)	Δ_rH°(0 K) = 12.724 ± 0.073 (×1.509) eV	Ruscic G4

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. 1.124 of the Thermochemical Network, Argonne National Laboratory, Lemont, Illinois 2022; available at ATcT.anl.gov [DOI: 10.17038/CSE/1885923]
4		Y. Ren, L. Zhou, A. Mellouki, V. Daële, M. Idir, S. S. Brown, B. Ruscic, Robert S. Paton, M. R. McGillen, and A. R. Ravishankara, Reactions of NO3 with Aromatic Aldehydes: Gas-Phase Kinetics and Insights into the Mechanism of the Reaction. Atmos. Chem. Phys. 21, 13537-13551 (2021) [DOI: 10.5194/acp2021-228]
5		B. Ruscic and D. H. Bross, Active Thermochemical Tables: The Thermophysical and Thermochemical Properties of Methyl, CH3, and Methylene, CH2, Corrected for Nonrigid Rotor and Anharmonic Oscillator Effects. Mol. Phys. e1969046 (2021) [DOI: 10.1080/00268976.2021.1969046]
6		J. H. Thorpe, J. L. Kilburn, D. Feller, P. B. Changala, D. H. Bross, B. Ruscic, and J. F. Stanton, Elaborated Thermochemical Treatment of HF, CO, N2, and H2O: Insight into HEAT and Its Extensions J. Chem. Phys. 155, 184109 (2021) [DOI: 10.1063/5.0069322]
7		T. L. Nguyen, D. H. Bross, B. Ruscic, G. B. Ellison, and J. F. Stanton, Mechanism, Thermochemistry, and Kinetics of the Reversible Reactions: C2H3 + H2 ⇌ C2H4 + H ⇌ C2H5. Faraday Discuss. , (Advance Article) (2022) [DOI: 10.1039/D1FD00124H]
8		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]
9		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 [8,9]).
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.