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].

Ethynylene

Formula: C2 (g, singlet)

CAS RN: 12070-15-4

ATcT ID: 12070-15-4*2

SMILES: [C]=[C]

InChI: InChI=1S/C2/c1-2

InChIKey: LBVWYGNGGJURHQ-UHFFFAOYSA-N

Hills Formula: C2

2D Image:

Aliases: C2; Ethynylene; Ethynediyl; 1,2-Ethynediyl; Carbon dimer; Diatomic carbon; Dicarbon radical; Dicarbon; Carbon molecule; Carbon cluster

Relative Molecular Mass: 24.0214 ± 0.0016

Δ_fH°(0 K)	Δ_fH°(298.15 K)	Uncertainty	Units
819.961	826.534	± 0.082	kJ/mol

3D Image of C2 (g, singlet)

spin ON spin OFF

Top contributors to the provenance of Δ_fH° of C2 (g, singlet)

The 20 contributors listed below account only for 47.9% of the provenance of Δ_fH° of C2 (g, singlet).
A total of 874 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
11.3	2306.1	C2 (g, triplet) → 2 C (g)	Δ_rH°(0 K) = 49786.7 ± 2.4 cm-1	Borsovszky 2021, Schmidt 2020, Haris 2017
8.2	2268.11	CO (g) → C (g) + O (g)	Δ_rH°(0 K) = 1071.92 ± 0.10 kJ/mol	Thorpe 2021
4.8	2375.1	2 H2 (g) + C (graphite) → CH4 (g)	Δ_rG°(1165 K) = 37.521 ± 0.068 kJ/mol	Smith 1946, note COf, 3rd Law
3.9	2278.2	CO (g) → C+ (g) + O (g)	Δ_rH°(0 K) = 22.3713 ± 0.0015 eV	Ng 2007
3.6	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
2.5	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
2.3	2228.7	C (graphite) + O2 (g) → CO2 (g)	Δ_rH°(298.15 K) = -393.464 ± 0.024 kJ/mol	Hawtin 1966, note CO2e
2.0	2262.1	CO (g) → C (g) + O (g)	Δ_rH°(0 K) = 89597.3 ± 12.0 (×1.384) cm-1	Kepa 2014, note unc2
1.1	2262.2	CO (g) → C (g) + O (g)	Δ_rH°(0 K) = 89592 ± 15 (×1.477) cm-1	Eidelsberg 1987
0.9	2228.4	C (graphite) + O2 (g) → CO2 (g)	Δ_rH°(298.15 K) = -393.462 ± 0.038 kJ/mol	Lewis 1965, note CO2d
0.9	2228.5	C (graphite) + O2 (g) → CO2 (g)	Δ_rH°(298.15 K) = -393.468 ± 0.038 kJ/mol	Fraser 1952, note CO2f
0.7	6863.8	C6H6 (g) → 6 C (g) + 6 H (g)	Δ_rH°(0 K) = 5463.0 ± 1.8 kJ/mol	Harding 2011
0.7	2265.5	CO (g) → C (g) + O (g)	Δ_rH°(0 K) = 89632 ± 27 cm-1	Ruscic 2003
0.6	2261.3	CO (g) → C (g) + O (g)	Δ_rH°(0 K) = 89620 ± 29 cm-1	Douglas 1955, Schmid 1935, note COj
0.6	9265.1	C60 (cr,l) + 60 O2 (g) → 60 CO2 (g)	Δ_rH°(298.15 K) = -25965 ± 20 kJ/mol	Kolesov 1996, est unc
0.6	2228.11	C (graphite) + O2 (g) → CO2 (g)	Δ_rH°(298.15 K) = -94.051 ± 0.011 kcal/mol	Prosen 1944a, Cox 1970, NBS TN270, NBS Tables 1989
0.6	2529.1	CH2CH2 (g) + 3 O2 (g) → 2 CO2 (g) + 2 H2O (cr,l)	Δ_rH°(298.15 K) = -1411.18 ± 0.30 kJ/mol	Rossini 1937
0.5	9229.6	C6H4(C2H2(CC(C4H4))) (g) → 14 C (g) + 10 H (g)	Δ_rH°(0 K) = 11890.6 ± 5.2 kJ/mol	Karton 2021
0.5	6863.5	C6H6 (g) → 6 C (g) + 6 H (g)	Δ_rH°(0 K) = 1305.43 ± 0.50 kcal/mol	Karton 2017
0.5	9225.6	C6H4(CH(CC(C4H4)CH)) (g) → 14 C (g) + 10 H (g)	Δ_rH°(0 K) = 11866.6 ± 5.2 kJ/mol	Karton 2021, Karton 2012a

Top 10 species with enthalpies of formation correlated to the Δ_fH° of C2 (g, singlet)

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
100.0	Ethynylene	C2 (g)	819.961	828.427	± 0.082	kJ/mol	24.0214 ± 0.0016	12070-15-4*0
100.0	Ethynylene	C2 (g, triplet)	827.185	833.890	± 0.082	kJ/mol	24.0214 ± 0.0016	12070-15-4*1
93.8	Carbon	C (g)	711.381	716.866	± 0.039	kJ/mol	12.01070 ± 0.00080	7440-44-0*0
93.8	Carbon	C (g, triplet)	711.381	716.866	± 0.039	kJ/mol	12.01070 ± 0.00080	7440-44-0*1
93.8	Carbon cation	C+ (g)	1797.834	1803.432	± 0.039	kJ/mol	12.01015 ± 0.00080	14067-05-1*0
93.8	Carbon	C (g, quintuplet)	1114.944	1120.091	± 0.039	kJ/mol	12.01070 ± 0.00080	7440-44-0*3
93.8	Carbon	C (g, singlet)	833.312	838.459	± 0.039	kJ/mol	12.01070 ± 0.00080	7440-44-0*2
93.7	Carbon dication	[C]+2 (g)	4150.451	4155.597	± 0.039	kJ/mol	12.00960 ± 0.00080	16092-61-8*0
93.4	Carbon anion	C- (g)	589.605	594.751	± 0.039	kJ/mol	12.01125 ± 0.00080	14337-00-9*0
92.3	Methyliumylidene	[CH]+ (g)	1619.738	1623.081	± 0.039	kJ/mol	13.01809 ± 0.00080	24361-82-8*0

Most Influential reactions involving C2 (g, singlet)

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
1.000	2304.1	C2 (g) → C2 (g, singlet)	Δ_rH°(0 K) = 0 ± 0 cm-1	Huber 1979, Martin 1992b
1.000	2305.1	C2 (g, singlet) → C2 (g, triplet)	Δ_rH°(0 K) = 603.817 ± 0.02 cm-1	Furtenbacher 2016, Chen 2015, est unc
0.000	2305.5	C2 (g, singlet) → C2 (g, triplet)	Δ_rH°(0 K) = 601.3 ± 5 cm-1	Martin 1992b, Tanabashi 2007, Davis 1988, Davis 1988a, Douay 1988a, est unc
0.000	2305.3	C2 (g, singlet) → C2 (g, triplet)	Δ_rH°(0 K) = 599.39 ± 5 cm-1	Huber 1979, est unc
0.000	2305.4	C2 (g, singlet) → C2 (g, triplet)	Δ_rH°(0 K) = 597.26 ± 5 (×1.325) cm-1	Dhumwad 1981, Huber 1979, est unc
0.000	2305.7	C2 (g, singlet) → C2 (g, triplet)	Δ_rH°(0 K) = 0.079 ± 0.005 eV	Harper 2020, est unc

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.