Selected ATcT [1, 2] enthalpy of formation based on version 1.156 of the Thermochemical Network [3]

This version of ATcT results[3] was generated by additional expansion of version 1.148 to include species relevant to a recent study of the oxidation of ethylene [4] as well as new measurements that led to refining the thermochemistry of CF and SiF and their cations [5].

Methylium

Formula: [CH3]+ (g)

CAS RN: 14531-53-4

ATcT ID: 14531-53-4*0

SMILES: [CH3+]

InChI: InChI=1S/CH3/h1H3/q+1

InChIKey: JUHDUIDUEUEQND-UHFFFAOYSA-N

Hills Formula: C1H3+

2D Image:

Aliases: [CH3]+; Methylium; Methylcarbonium; Methyl carbonium; Methyl cation; Methyl ion (1+)

Relative Molecular Mass: 15.03397 ± 0.00083

Δ_fH°(0 K)	Δ_fH°(298.15 K)	Uncertainty	Units
1099.354	1095.411	± 0.045	kJ/mol

3D Image of [CH3]+ (g)

spin ON spin OFF

Top contributors to the provenance of Δ_fH° of [CH3]+ (g)

The 20 contributors listed below account only for 65.0% of the provenance of Δ_fH° of [CH3]+ (g).
A total of 317 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
37.7	2359.1	2 H2 (g) + C (graphite) → CH4 (g)	Δ_rG°(1165 K) = 37.521 ± 0.068 kJ/mol	Smith 1946, note COf, 3rd Law
6.7	2357.7	CH4 (g) + 2 O2 (g) → CO2 (g) + 2 H2O (cr,l)	Δ_rH°(298.15 K) = -890.578 ± 0.078 kJ/mol	Schley 2010
6.1	2381.1	CH4 (g) → [CH3]+ (g) + H (g)	Δ_rH°(0 K) = 14.32271 ± 0.00013 eV	Chang 2017
5.7	125.2	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
1.0	2214.7	C (graphite) + O2 (g) → CO2 (g)	Δ_rH°(298.15 K) = -393.464 ± 0.024 kJ/mol	Hawtin 1966, note CO2e
0.9	2357.4	CH4 (g) + 2 O2 (g) → CO2 (g) + 2 H2O (cr,l)	Δ_rH°(298.15 K) = -890.61 ± 0.21 kJ/mol	Dale 2002
0.8	2252.11	CO (g) → C (g) + O (g)	Δ_rH°(0 K) = 1071.92 ± 0.10 (×1.242) kJ/mol	Thorpe 2021
0.6	2262.2	CO (g) → C+ (g) + O (g)	Δ_rH°(0 K) = 22.3713 ± 0.0015 eV	Ng 2007
0.6	2357.6	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
0.6	2357.8	CH4 (g) + 2 O2 (g) → CO2 (g) + 2 H2O (cr,l)	Δ_rH°(298.15 K) = -890.482 ± 0.260 kJ/mol	Haloua 2015
0.4	2270.9	C (graphite) + CO2 (g) → 2 CO (g)	Δ_rG°(1165 K) = -33.545 ± 0.058 kJ/mol	Smith 1946, note COf, 3rd Law
0.4	2371.12	CH3 (g) → C (g) + 3 H (g)	Δ_rH°(0 K) = 289.11 ± 0.10 kcal/mol	Feller 2016, note unc2
0.4	2214.4	C (graphite) + O2 (g) → CO2 (g)	Δ_rH°(298.15 K) = -393.462 ± 0.038 kJ/mol	Lewis 1965, note CO2d
0.4	2214.5	C (graphite) + O2 (g) → CO2 (g)	Δ_rH°(298.15 K) = -393.468 ± 0.038 kJ/mol	Fraser 1952, note CO2f
0.4	115.11	H2O (g) → O (g) + 2 H (g)	Δ_rH°(0 K) = 917.80 ± 0.15 kJ/mol	Thorpe 2021
0.3	2413.1	CH3 (g) → CH2 (g, triplet) + H (g)	Δ_rH°(0 K) = 109.26 ± 0.08 kcal/mol	Feller 2016, est unc, note unc2
0.3	157.1	OH (g) → [OH]+ (g)	Δ_rH°(0 K) = 104989 ± 5 (×2.327) cm-1	Wiedmann 1992, note unc
0.3	8842.1	5 CH4 (g) → HCCCCCH3 (g) + 8 H2 (g)	Δ_rH°(0 K) = 750.67 ± 2.00 kJ/mol	Klippenstein 2017
0.3	2357.5	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
0.3	2357.1	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

Top 10 species with enthalpies of formation correlated to the Δ_fH° of [CH3]+ (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
96.1	Methane	CH4 (g)	-66.541	-74.511	± 0.044	kJ/mol	16.04246 ± 0.00085	74-82-8*0
88.5	Methyl	CH3 (g)	149.882	146.481	± 0.050	kJ/mol	15.03452 ± 0.00083	2229-07-4*0
74.3	Methane cation	[CH4]+ (g)	1150.688	1144.305	± 0.057	kJ/mol	16.04191 ± 0.00085	20741-88-2*0
44.1	Carbonic acid	C(O)(OH)2 (aq, undissoc)		-698.670	± 0.028	kJ/mol	62.0248 ± 0.0012	463-79-6*1000
43.7	Water	H2O (cr, l, eq.press.)	-286.276	-285.804	± 0.022	kJ/mol	18.01528 ± 0.00033	7732-18-5*499
43.7	Water	H2O (l, eq.press.)		-285.804	± 0.022	kJ/mol	18.01528 ± 0.00033	7732-18-5*589
43.7	Water	H2O (l)		-285.802	± 0.022	kJ/mol	18.01528 ± 0.00033	7732-18-5*590
43.7	Oxonium	[H3O]+ (aq)		-285.802	± 0.022	kJ/mol	19.02267 ± 0.00037	13968-08-6*800
43.7	Water	H2O (cr,l)	-286.274	-285.802	± 0.022	kJ/mol	18.01528 ± 0.00033	7732-18-5*500
43.7	Water	H2O (g)	-238.904	-241.807	± 0.022	kJ/mol	18.01528 ± 0.00033	7732-18-5*0

Most Influential reactions involving [CH3]+ (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
0.957	2381.1	CH4 (g) → [CH3]+ (g) + H (g)	Δ_rH°(0 K) = 14.32271 ± 0.00013 eV	Chang 2017
0.522	6222.2	CH3I (g) → [CH3]+ (g) + I (g)	Δ_rH°(0 K) = 12.251 ± 0.0024 eV	Lee 2007
0.411	2374.2	CH3 (g) → [CH3]+ (g)	Δ_rH°(0 K) = 79369.9 ± 3 cm-1	Schulenburg 2006, note CH3
0.411	2374.1	CH3 (g) → [CH3]+ (g)	Δ_rH°(0 K) = 79370.4 ± 3 cm-1	Schulenburg 2006, note CH3
0.198	6222.1	CH3I (g) → [CH3]+ (g) + I (g)	Δ_rH°(0 K) = 12.248 ± 0.003 (×1.297) eV	Bodi 2009, Bodi 2023
0.150	6200.1	CH3Br (g) → [CH3]+ (g) + Br (g)	Δ_rH°(0 K) = 12.834 ± 0.002 (×2.538) eV	Song 2001
0.079	2374.4	CH3 (g) → [CH3]+ (g)	Δ_rH°(0 K) = 79363 ± 3 (×2.278) cm-1	Blush 1993, note CH3
0.039	6222.3	CH3I (g) → [CH3]+ (g) + I (g)	Δ_rH°(0 K) = 12.243 ± 0.008 (×1.091) eV	Lee 2007, Bodi 2009
0.036	2375.12	CH3 (g) → [CH3]+ (g)	Δ_rH°(0 K) = 226.946 ± 0.029 kcal/mol	Feller 2017a
0.029	4576.1	CH3OO (g) → [CH3]+ (g) + O2 (g)	Δ_rH°(0 K) = 11.15 ± 0.02 eV	Tang 2020a
0.022	6222.5	CH3I (g) → [CH3]+ (g) + I (g)	Δ_rH°(0 K) = 12.24 ± 0.01 (×1.164) eV	Mintz 1976
0.020	2544.5	[CH2CH]+ (g) + CH4 (g) → [CH3]+ (g) + CH2CH2 (g)	Δ_rH°(0 K) = 25.65 ± 0.9 kcal/mol	Ruscic W1RO, Lago 2006
0.016	2544.4	[CH2CH]+ (g) + CH4 (g) → [CH3]+ (g) + CH2CH2 (g)	Δ_rH°(0 K) = 26.09 ± 1.0 kcal/mol	Ruscic CBS-n
0.016	2544.2	[CH2CH]+ (g) + CH4 (g) → [CH3]+ (g) + CH2CH2 (g)	Δ_rH°(0 K) = 25.09 ± 1.0 kcal/mol	Ruscic G4
0.016	2381.3	CH4 (g) → [CH3]+ (g) + H (g)	Δ_rH°(0 K) = 14.323 ± 0.001 eV	Weitzel 1999, Weitzel 2001
0.013	4576.2	CH3OO (g) → [CH3]+ (g) + O2 (g)	Δ_rH°(0 K) = 11.164 ± 0.030 eV	Voronova 2018, Tang 2020a, est unc
0.010	2362.4	[CH5]+ (g) → [CH3]+ (g) + H2 (g)	Δ_rH°(0 K) = 42.0 ± 1 kcal/mol	Muller 1997
0.009	6200.3	CH3Br (g) → [CH3]+ (g) + Br (g)	Δ_rH°(0 K) = 12.82 ± 0.02 eV	Traeger 1981, AE corr, note unc2
0.009	6222.4	CH3I (g) → [CH3]+ (g) + I (g)	Δ_rH°(0 K) = 12.269 ± 0.003 (×5.907) eV	Song 2001
0.008	2544.1	[CH2CH]+ (g) + CH4 (g) → [CH3]+ (g) + CH2CH2 (g)	Δ_rH°(0 K) = 24.36 ± 1.1 (×1.269) kcal/mol	Ruscic G3X

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. 1.156 of the Thermochemical Network (2024); available at ATcT.anl.gov
4		N. A. Seifert, B. Ruscic, R. Sivaramakrishnan, and K. Prozument, The C2H4O Isomers in the Oxidation of Ethylene J. Mol. Spectrosc. 398, 111847/1-8 (2023) [DOI: 10.1016/j.jms.2023.111847]
5		U. Jacovella, B. Ruscic, N. L. Chen, H.-L. Le, S. Boyé-Péronne, S. Hartweg, M. Roy-Chowdhury, G. A. Garcia, J.-C. Loison, and B. Gans, Refining Thermochemical Properties of CF, SiF, and Their Cations by Combining Photoelectron Spectroscopy, Quantum Chemical Calculations, and the Active Thermochemical Tables Approach Phys. Chem. Chem. Phys. 25, 30838-30847 (2023) [DOI: 10.1039/D3CP04244H]
6		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]
7		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 [6] and Ruscic and Bross[7]).
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.