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 cation

Formula: [C2]+ (g)

CAS RN: 12595-79-8

ATcT ID: 12595-79-8*0

SMILES: [C]=[C+]

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

InChIKey: ADIRGMFQWJHVBM-UHFFFAOYSA-N

Hills Formula: C2+

2D Image:

Aliases: [C2]+; Ethynylene cation; Ethynylene ion (1+); Ethynyliumyl; 2-Ethynylium-1-yl; 1,2-Ethynediyl cation; 1,2-Ethynediyl ion (1+); Carbon dimer cation; Carbon dimer ion (1+); Diatomic carbon cation; Diatomic carbon ion (1+); Dicarbon cation; Dicarbon ion (1+); Carbon molecule cation; Carbon molecule ion (1+); Carbon cluster cation; Carbon cluster ion (1+)

Relative Molecular Mass: 24.0209 ± 0.0016

Δ_fH°(0 K)	Δ_fH°(298.15 K)	Uncertainty	Units
1964.93	1971.52	± 0.40	kJ/mol

3D Image of [C2]+ (g)

spin ON spin OFF

Top contributors to the provenance of Δ_fH° of [C2]+ (g)

The 3 contributors listed below account for 92.4% of the provenance of Δ_fH° of [C2]+ (g).

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
61.6	2307.1	C2 (g, triplet) → [C2]+ (g)	Δ_rH°(0 K) = 11.791 ± 0.005 eV	Krechkivska 2016
15.4	2307.2	C2 (g, triplet) → [C2]+ (g)	Δ_rH°(0 K) = 11.795 ± 0.010 eV	Harper 2020
15.4	2307.3	C2 (g, triplet) → [C2]+ (g)	Δ_rH°(0 K) = 11.790 ± 0.010 eV	Krechkivska 2016

Top 10 species with enthalpies of formation correlated to the Δ_fH° of [C2]+ (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
20.6	Ethynylene	C2 (g, triplet)	827.185	833.890	± 0.082	kJ/mol	24.0214 ± 0.0016	12070-15-4*1
20.6	Ethynylene	C2 (g, singlet)	819.961	826.534	± 0.082	kJ/mol	24.0214 ± 0.0016	12070-15-4*2
20.6	Ethynylene	C2 (g)	819.961	828.427	± 0.082	kJ/mol	24.0214 ± 0.0016	12070-15-4*0
19.4	Carbon	C (g, quintuplet)	1114.944	1120.091	± 0.039	kJ/mol	12.01070 ± 0.00080	7440-44-0*3
19.4	Carbon	C (g, singlet)	833.312	838.459	± 0.039	kJ/mol	12.01070 ± 0.00080	7440-44-0*2
19.4	Carbon cation	C+ (g)	1797.834	1803.432	± 0.039	kJ/mol	12.01015 ± 0.00080	14067-05-1*0
19.4	Carbon	C (g, triplet)	711.381	716.866	± 0.039	kJ/mol	12.01070 ± 0.00080	7440-44-0*1
19.4	Carbon	C (g)	711.381	716.866	± 0.039	kJ/mol	12.01070 ± 0.00080	7440-44-0*0
19.3	Carbon dication	[C]+2 (g)	4150.451	4155.597	± 0.039	kJ/mol	12.00960 ± 0.00080	16092-61-8*0
19.3	Carbon anion	C- (g)	589.605	594.751	± 0.039	kJ/mol	12.01125 ± 0.00080	14337-00-9*0

Most Influential reactions involving [C2]+ (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
0.643	2307.1	C2 (g, triplet) → [C2]+ (g)	Δ_rH°(0 K) = 11.791 ± 0.005 eV	Krechkivska 2016
0.160	2307.3	C2 (g, triplet) → [C2]+ (g)	Δ_rH°(0 K) = 11.790 ± 0.010 eV	Krechkivska 2016
0.160	2307.2	C2 (g, triplet) → [C2]+ (g)	Δ_rH°(0 K) = 11.795 ± 0.010 eV	Harper 2020
0.010	2293.11	C2 (g) → [C2]+ (g)	Δ_rH°(0 K) = 11.880 ± 0.040 eV	Ruscic W1RO
0.006	2300.1	[C2]+ (g) → C (g) + C+ (g)	Δ_rH°(0 K) = 5.634 ± 0.050 eV	Shi 2013a, est unc
0.003	2297.8	[C2]+ (g) → 2 C (g)	Δ_rH°(0 K) = -130.55 ± 1.50 kcal/mol	Ruscic W1RO
0.003	2297.4	[C2]+ (g) → 2 C (g)	Δ_rH°(0 K) = -129.24 ± 1.60 kcal/mol	Ruscic G4
0.003	2297.7	[C2]+ (g) → 2 C (g)	Δ_rH°(0 K) = -130.86 ± 1.60 kcal/mol	Ruscic CBS-n
0.002	2297.3	[C2]+ (g) → 2 C (g)	Δ_rH°(0 K) = -128.41 ± 1.72 kcal/mol	Ruscic G3X
0.001	2297.6	[C2]+ (g) → 2 C (g)	Δ_rH°(0 K) = -130.91 ± 2.16 kcal/mol	Ruscic CBS-n
0.001	2311.1	HCCH (g) → [C2]+ (g) + H2 (g)	Δ_rH°(0 K) = 18.1 ± 0.1 (×1.091) eV	Hayaishi 1982
0.000	2293.13	C2 (g) → [C2]+ (g)	Δ_rH°(0 K) = 11.771 ± 0.15 eV	Harper 2020, est unc
0.000	2293.12	C2 (g) → [C2]+ (g)	Δ_rH°(0 K) = 11.80 ± 0.15 eV	Fura 2002
0.000	2293.3	C2 (g) → [C2]+ (g)	Δ_rH°(0 K) = 11.6 ± 0.4 eV	Gingerich 1994
0.000	2293.2	C2 (g) → [C2]+ (g)	Δ_rH°(0 K) = 11.4 ± 0.3 (×1.576) eV	Reid 1995

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.