Selected ATcT [1, 2] enthalpy of formation based on version 1.172 of the Thermochemical Network [3]

This version of ATcT results[3] was generated by additional expansion of version 1.156 to include species relevant to a study of photodissociation of formamide[4].

Vinylidene

Formula: CCH2 (g, triplet)

CAS RN: 2143-69-3

ATcT ID: 2143-69-3*1

SMILES: [C]=C

InChI: InChI=1S/C2H2/c1-2/h1H2

InChIKey: SNVLJLYUUXKWOJ-UHFFFAOYSA-N

Hills Formula: C2H2

2D Image:

Aliases: CCH2; Vinylidene; Ethenylidene; Methylenecarbene; Methylidenecarbene; CH2C; H2CC

Relative Molecular Mass: 26.0373 ± 0.0016

Δ_fH°(0 K)	Δ_fH°(298.15 K)	Uncertainty	Units
610.62	610.33	± 0.39	kJ/mol

3D Image of CCH2 (g, triplet)

spin ON spin OFF

Top contributors to the provenance of Δ_fH° of CCH2 (g, triplet)

The 20 contributors listed below account only for 81.8% of the provenance of Δ_fH° of CCH2 (g, triplet).
A total of 64 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
31.1	2622.1	[CCH2]- (g) → CCH2 (g, triplet)	Δ_rH°(0 K) = 20602 ± 24 cm-1	DeVine 2016, note unc
9.3	2625.1	HCCH (g) → CCH2 (g)	Δ_rH°(0 K) = 43.53 ± 0.15 kcal/mol	Lee 2013
8.7	2621.1	CCH2 (g) → CCH2 (g, triplet)	Δ_rH°(0 K) = 2.065 ± 0.006 eV	Ervin 1989
3.3	2625.4	HCCH (g) → CCH2 (g)	Δ_rH°(0 K) = 43.62 ± 0.25 kcal/mol	Karton 2011
3.3	2625.5	HCCH (g) → CCH2 (g)	Δ_rH°(0 K) = 43.62 ± 0.25 kcal/mol	Karton 2006, Karton 2008
2.6	2615.12	CCH2 (g) → 2 C (g) + 2 H (g)	Δ_rH°(0 K) = 345.10 ± 0.30 kcal/mol	Karton 2008
2.6	2615.11	CCH2 (g) → 2 C (g) + 2 H (g)	Δ_rH°(0 K) = 345.10 ± 0.30 kcal/mol	Karton 2011
2.6	2627.9	CH2CH2 (g) → CCH2 (g) + H2 (g)	Δ_rH°(0 K) = 83.71 ± 0.30 kcal/mol	Karton 2011
2.3	2626.12	CCH2 (g) → CCH (g) + H (g)	Δ_rH°(0 K) = 88.02 ± 0.30 kcal/mol	Karton 2011
2.1	2617.1	[CCH2]- (g) → CCH2 (g)	Δ_rH°(0 K) = 0.4866 ± 0.0008 eV	DeVine 2017
2.0	2566.9	CH2CH (g) → CCH2 (g) + H (g)	Δ_rH°(0 K) = 77.96 ± 0.30 kcal/mol	Karton 2008
2.0	2566.8	CH2CH (g) → CCH2 (g) + H (g)	Δ_rH°(0 K) = 77.96 ± 0.30 kcal/mol	Karton 2011
1.8	2627.11	CH2CH2 (g) → CCH2 (g) + H2 (g)	Δ_rH°(0 K) = 350.63 ± 1.5 kJ/mol	Klippenstein 2017
1.6	2626.13	CCH2 (g) → CCH (g) + H (g)	Δ_rH°(0 K) = 368.45 ± 1.5 kJ/mol	Klippenstein 2017
1.6	2624.10	HCCH (g) → CCH2 (g)	Δ_rH°(0 K) = 182.22 ± 1.5 kJ/mol	Klippenstein 2017
1.3	2625.3	HCCH (g) → CCH2 (g)	Δ_rH°(0 K) = 43.59 ± 0.40 kcal/mol	Karton 2011
0.7	2615.10	CCH2 (g) → 2 C (g) + 2 H (g)	Δ_rH°(0 K) = 344.97 ± 0.56 kcal/mol	Karton 2011
0.7	2627.8	CH2CH2 (g) → CCH2 (g) + H2 (g)	Δ_rH°(0 K) = 83.78 ± 0.56 kcal/mol	Karton 2011
0.6	2626.11	CCH2 (g) → CCH (g) + H (g)	Δ_rH°(0 K) = 88.08 ± 0.56 kcal/mol	Karton 2011
0.6	7719.6	CH2CCHO (g) → CCH2 (g) + HCO (g)	Δ_rH°(0 K) = 274.15 ± 2.0 kJ/mol	Klippenstein 2017

Top 10 species with enthalpies of formation correlated to the Δ_fH° of CCH2 (g, triplet)

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
75.8	Vinylidene anion	[CCH2]- (g)	364.25	364.06	± 0.31	kJ/mol	26.0378 ± 0.0016	66295-36-1*0
74.4	Vinylidene	CCH2 (g)	411.21	412.12	± 0.30	kJ/mol	26.0373 ± 0.0016	2143-69-3*0
22.1	Acetylene	HCCH (g)	228.86	228.30	± 0.12	kJ/mol	26.0373 ± 0.0016	74-86-2*0
22.1	Acetylene cation	[HCCH]+ (g)	1328.88	1328.21	± 0.12	kJ/mol	26.0367 ± 0.0016	25641-79-6*0
17.4	Ethynylium	[CCH]+ (g)	1687.62	1690.95	± 0.15	kJ/mol	25.0288 ± 0.0016	16456-59-0*0
17.4	1-Propenylidene	CH3CHC (g, triplet)	630.5	623.0	± 1.7	kJ/mol	40.0639 ± 0.0024	70277-78-0*2
17.2	Ethynyl	CCH (g)	563.73	567.85	± 0.15	kJ/mol	25.0293 ± 0.0016	2122-48-7*0
16.2	Carbon	C (g)	711.381	716.866	± 0.039	kJ/mol	12.01070 ± 0.00080	7440-44-0*0
16.2	Carbon	C (g, triplet)	711.381	716.866	± 0.039	kJ/mol	12.01070 ± 0.00080	7440-44-0*1
16.2	Carbon cation	C+ (g)	1797.834	1803.432	± 0.039	kJ/mol	12.01015 ± 0.00080	14067-05-1*0

Most Influential reactions involving CCH2 (g, triplet)

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
0.782	2622.1	[CCH2]- (g) → CCH2 (g, triplet)	Δ_rH°(0 K) = 20602 ± 24 cm-1	DeVine 2016, note unc
0.213	3490.5	CH3CHC (g, triplet) + HCCH (g) → CCH2 (g, triplet) + CH3CCH (g)	Δ_rH°(0 K) = -13.16 ± 0.85 kcal/mol	Ruscic W1RO
0.201	2621.1	CCH2 (g) → CCH2 (g, triplet)	Δ_rH°(0 K) = 2.065 ± 0.006 eV	Ervin 1989
0.190	3490.1	CH3CHC (g, triplet) + HCCH (g) → CCH2 (g, triplet) + CH3CCH (g)	Δ_rH°(0 K) = -13.72 ± 0.90 kcal/mol	Ruscic G3X
0.190	3490.2	CH3CHC (g, triplet) + HCCH (g) → CCH2 (g, triplet) + CH3CCH (g)	Δ_rH°(0 K) = -13.27 ± 0.90 kcal/mol	Ruscic G4
0.154	3490.3	CH3CHC (g, triplet) + HCCH (g) → CCH2 (g, triplet) + CH3CCH (g)	Δ_rH°(0 K) = -14.18 ± 1.00 kcal/mol	Ruscic CBS-n
0.081	2623.5	HCCH (g, cis-triplet) → CCH2 (g, triplet)	Δ_rH°(0 K) = 770 ± 420 cm-1	Ruscic W1RO
0.070	2623.2	HCCH (g, cis-triplet) → CCH2 (g, triplet)	Δ_rH°(0 K) = 1006 ± 450 cm-1	Ruscic G4
0.069	2623.4	HCCH (g, cis-triplet) → CCH2 (g, triplet)	Δ_rH°(0 K) = 789 ± 455 cm-1	Ruscic CBS-n
0.059	2623.1	HCCH (g, cis-triplet) → CCH2 (g, triplet)	Δ_rH°(0 K) = 910 ± 490 cm-1	Ruscic G3X
0.045	2623.3	HCCH (g, cis-triplet) → CCH2 (g, triplet)	Δ_rH°(0 K) = 527 ± 560 cm-1	Ruscic CBS-n
0.008	2621.7	CCH2 (g) → CCH2 (g, triplet)	Δ_rH°(0 K) = 16720 ± 230 cm-1	Sherrill 2000
0.002	2621.6	CCH2 (g) → CCH2 (g, triplet)	Δ_rH°(0 K) = 2.057 ± 0.052 eV	Ruscic W1RO
0.002	2621.3	CCH2 (g) → CCH2 (g, triplet)	Δ_rH°(0 K) = 2.070 ± 0.056 eV	Ruscic G4
0.002	2621.5	CCH2 (g) → CCH2 (g, triplet)	Δ_rH°(0 K) = 2.063 ± 0.057 eV	Ruscic CBS-n
0.002	2621.2	CCH2 (g) → CCH2 (g, triplet)	Δ_rH°(0 K) = 2.060 ± 0.061 eV	Ruscic G3X
0.001	2621.4	CCH2 (g) → CCH2 (g, triplet)	Δ_rH°(0 K) = 2.048 ± 0.070 eV	Ruscic CBS-n

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. 1.172 of the Thermochemical Network (2024); available at ATcT.anl.gov
4		K. L. Caster, N. A. Seifert, B. Ruscic, A. W. Jasper, and K. Prozument, Dynamics of HCN, NHC, and HNCO Formation in the 193 nm Photodissociation of Formamide J. Phys. Chem. A (in press) (2024) [DOI: 10.1021/acs.jpca.4c02232]
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.