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].

Cyanomethylene

Formula: HCCN (g, singlet)

CAS RN: 2612-62-6

ATcT ID: 2612-62-6*2

SMILES: [CH]C#N

InChI: InChI=1S/C2HN/c1-2-3/h1H

InChIKey: SZICEGNEOSKVLO-UHFFFAOYSA-N

Hills Formula: C2H1N1

2D Image:

Aliases: HCCN; Cyanomethylene; Cyanocarbene; CHCN

Relative Molecular Mass: 39.0361 ± 0.0016

Δ_fH°(0 K)	Δ_fH°(298.15 K)	Uncertainty	Units
529.4	530.4	± 1.3	kJ/mol

3D Image of HCCN (g, singlet)

spin ON spin OFF

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

The 20 contributors listed below account only for 74.1% of the provenance of Δ_fH° of HCCN (g, singlet).
A total of 36 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
11.7	8090.1	HCCN (g, triplet) → HCCN (g, singlet)	Δ_rH°(0 K) = 0.510 ± 0.015 eV	Vogelhuber 2011a
10.3	8090.2	HCCN (g, triplet) → HCCN (g, singlet)	Δ_rH°(0 K) = 0.515 ± 0.016 eV	Nimlos 2002
4.1	8084.5	HCCN (g, singlet) → 2 C (g) + H (g) + N (g)	Δ_rH°(0 K) = 376.95 ± 1.50 kcal/mol	Ruscic W1RO
4.1	8091.5	HCCN (g, triplet) + CH4 (g) → CH2 (g, triplet) + CH3CN (g)	Δ_rH°(0 K) = 13.72 ± 0.9 kcal/mol	Ruscic W1RO
3.9	8092.5	CH2CN (g) + CH2 (g, triplet) → HCCN (g, triplet) + CH3 (g)	Δ_rH°(0 K) = -5.82 ± 0.85 kcal/mol	Ruscic W1RO
3.6	8084.4	HCCN (g, singlet) → 2 C (g) + H (g) + N (g)	Δ_rH°(0 K) = 376.51 ± 1.60 kcal/mol	Ruscic CBS-n
3.6	8084.2	HCCN (g, singlet) → 2 C (g) + H (g) + N (g)	Δ_rH°(0 K) = 378.44 ± 1.60 kcal/mol	Ruscic G4
3.4	8092.4	CH2CN (g) + CH2 (g, triplet) → HCCN (g, triplet) + CH3 (g)	Δ_rH°(0 K) = -6.66 ± 0.90 kcal/mol	Ruscic CBS-n
3.4	8092.1	CH2CN (g) + CH2 (g, triplet) → HCCN (g, triplet) + CH3 (g)	Δ_rH°(0 K) = -5.56 ± 0.90 kcal/mol	Ruscic G3X
3.4	8092.2	CH2CN (g) + CH2 (g, triplet) → HCCN (g, triplet) + CH3 (g)	Δ_rH°(0 K) = -5.42 ± 0.90 kcal/mol	Ruscic G4
3.3	8091.2	HCCN (g, triplet) + CH4 (g) → CH2 (g, triplet) + CH3CN (g)	Δ_rH°(0 K) = 13.49 ± 1.0 kcal/mol	Ruscic G4
3.1	8084.1	HCCN (g, singlet) → 2 C (g) + H (g) + N (g)	Δ_rH°(0 K) = 378.77 ± 1.72 kcal/mol	Ruscic G3X
2.8	8092.3	CH2CN (g) + CH2 (g, triplet) → HCCN (g, triplet) + CH3 (g)	Δ_rH°(0 K) = -6.63 ± 1.0 kcal/mol	Ruscic CBS-n
2.7	8091.1	HCCN (g, triplet) + CH4 (g) → CH2 (g, triplet) + CH3CN (g)	Δ_rH°(0 K) = 13.47 ± 1.1 kcal/mol	Ruscic G3X
2.0	8091.4	HCCN (g, triplet) + CH4 (g) → CH2 (g, triplet) + CH3CN (g)	Δ_rH°(0 K) = 15.40 ± 1.0 (×1.269) kcal/mol	Ruscic CBS-n
2.0	8084.3	HCCN (g, singlet) → 2 C (g) + H (g) + N (g)	Δ_rH°(0 K) = 376.38 ± 2.16 kcal/mol	Ruscic CBS-n
1.5	8083.5	HCCN (g, triplet) → 2 C (g) + H (g) + N (g)	Δ_rH°(0 K) = 389.15 ± 1.50 kcal/mol	Ruscic W1RO
1.4	8091.3	HCCN (g, triplet) + CH4 (g) → CH2 (g, triplet) + CH3CN (g)	Δ_rH°(0 K) = 15.64 ± 1.3 (×1.164) kcal/mol	Ruscic CBS-n
1.4	8101.5	HCNC (g, singlet) → HCCN (g, singlet)	Δ_rH°(0 K) = -12.81 ± 1.2 kcal/mol	Ruscic W1RO
1.3	8083.2	HCCN (g, triplet) → 2 C (g) + H (g) + N (g)	Δ_rH°(0 K) = 389.54 ± 1.60 kcal/mol	Ruscic G4

Top 10 species with enthalpies of formation correlated to the Δ_fH° of HCCN (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
73.1	Cyanomethylene	HCCN (g, triplet)	479.6	483.0	± 1.1	kJ/mol	39.0361 ± 0.0016	2612-62-6*1
73.1	Cyanomethylene	HCCN (g)	479.6	483.0	± 1.1	kJ/mol	39.0361 ± 0.0016	2612-62-6*0
55.1	Cyanomethylene anion	[HCCN]- (g)	286.3	286.8	± 1.5	kJ/mol	39.0366 ± 0.0016	12373-24-9*0
43.8	Isocyanomethylene	HCNC (g, singlet)	583.1	584.4	± 1.6	kJ/mol	39.0361 ± 0.0016	78694-65-2*1
43.8	Isocyanomethylene	HCNC (g)	583.1	585.3	± 1.6	kJ/mol	39.0361 ± 0.0016	78694-65-2*0
41.9	Isocyanomethylene	HCNC (g, triplet)	585.2	586.3	± 1.6	kJ/mol	39.0361 ± 0.0016	78694-65-2*2
35.6	Cyanomethyliumyl	[HCCN]+ (g)	1506.4	1507.9	± 2.3	kJ/mol	39.0355 ± 0.0016	34447-38-6*0
35.2	Isocyanomethylene anion	[HCNC]- (g)	401.3	402.0	± 2.0	kJ/mol	39.0366 ± 0.0016	144141-01-5*0
21.5	Isocyanomethyliumyl	[HCNC]+ (g)	1506.7	1508.6	± 3.2	kJ/mol	39.0355 ± 0.0016	99045-54-2*0
15.0	Cyanomethyl	CH2CN (g)	262.83	259.95	± 0.53	kJ/mol	40.0440 ± 0.0016	2932-82-3*0

Most Influential reactions involving HCCN (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
0.375	8090.1	HCCN (g, triplet) → HCCN (g, singlet)	Δ_rH°(0 K) = 0.510 ± 0.015 eV	Vogelhuber 2011a
0.329	8090.2	HCCN (g, triplet) → HCCN (g, singlet)	Δ_rH°(0 K) = 0.515 ± 0.016 eV	Nimlos 2002
0.092	8101.5	HCNC (g, singlet) → HCCN (g, singlet)	Δ_rH°(0 K) = -12.81 ± 1.2 kcal/mol	Ruscic W1RO
0.078	8101.4	HCNC (g, singlet) → HCCN (g, singlet)	Δ_rH°(0 K) = -12.29 ± 1.3 kcal/mol	Ruscic CBS-n
0.078	8101.2	HCNC (g, singlet) → HCCN (g, singlet)	Δ_rH°(0 K) = -12.44 ± 1.3 kcal/mol	Ruscic G4
0.067	8101.1	HCNC (g, singlet) → HCCN (g, singlet)	Δ_rH°(0 K) = -13.09 ± 1.4 kcal/mol	Ruscic G3X
0.059	8101.6	HCNC (g, singlet) → HCCN (g, singlet)	Δ_rH°(0 K) = -12.9 ± 1.5 kcal/mol	Koput 2003, est unc
0.052	8101.3	HCNC (g, singlet) → HCCN (g, singlet)	Δ_rH°(0 K) = -12.05 ± 1.6 kcal/mol	Ruscic CBS-n
0.041	8084.5	HCCN (g, singlet) → 2 C (g) + H (g) + N (g)	Δ_rH°(0 K) = 376.95 ± 1.50 kcal/mol	Ruscic W1RO
0.036	8084.2	HCCN (g, singlet) → 2 C (g) + H (g) + N (g)	Δ_rH°(0 K) = 378.44 ± 1.60 kcal/mol	Ruscic G4
0.036	8084.4	HCCN (g, singlet) → 2 C (g) + H (g) + N (g)	Δ_rH°(0 K) = 376.51 ± 1.60 kcal/mol	Ruscic CBS-n
0.031	8084.1	HCCN (g, singlet) → 2 C (g) + H (g) + N (g)	Δ_rH°(0 K) = 378.77 ± 1.72 kcal/mol	Ruscic G3X
0.031	8090.7	HCCN (g, triplet) → HCCN (g, singlet)	Δ_rH°(0 K) = 4267 ± 420 cm-1	Ruscic W1RO
0.027	8090.4	HCCN (g, triplet) → HCCN (g, singlet)	Δ_rH°(0 K) = 3881 ± 450 cm-1	Ruscic G4
0.026	8090.6	HCCN (g, triplet) → HCCN (g, singlet)	Δ_rH°(0 K) = 4574 ± 455 cm-1	Ruscic CBS-n
0.022	8090.3	HCCN (g, triplet) → HCCN (g, singlet)	Δ_rH°(0 K) = 4126 ± 490 cm-1	Ruscic G3X
0.022	8090.8	HCCN (g, triplet) → HCCN (g, singlet)	Δ_rH°(0 K) = 3763 ± 500 cm-1	Koput 2003, est unc
0.020	8084.3	HCCN (g, singlet) → 2 C (g) + H (g) + N (g)	Δ_rH°(0 K) = 376.38 ± 2.16 kcal/mol	Ruscic CBS-n
0.017	8090.5	HCCN (g, triplet) → HCCN (g, singlet)	Δ_rH°(0 K) = 4510 ± 560 cm-1	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.