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].

Isocyanomethylene

Formula: HCNC (g, singlet)

CAS RN: 78694-65-2

ATcT ID: 78694-65-2*1

SMILES: [CH][N+]#[C-]

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

InChIKey: CFOKGMSNCIXEBP-UHFFFAOYSA-N

Hills Formula: C2H1N1

2D Image:

Aliases: HCNC; Isocyanomethylene; Isocyanocarbene; CHNC

Relative Molecular Mass: 39.0361 ± 0.0016

Δ_fH°(0 K)	Δ_fH°(298.15 K)	Uncertainty	Units
583.1	584.4	± 1.6	kJ/mol

3D Image of HCNC (g, singlet)

spin ON spin OFF

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

The 20 contributors listed below account only for 75.3% of the provenance of Δ_fH° of HCNC (g, singlet).
A total of 31 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
6.1	8093.5	HCNC (g, singlet) → 2 C (g) + H (g) + N (g)	Δ_rH°(0 K) = 364.13 ± 1.50 kcal/mol	Ruscic W1RO
5.9	8100.8	HCNC (g, singlet) → HCNC (g, triplet)	Δ_rH°(0 K) = 141 ± 80 cm-1	Stanton 2023
5.4	8093.2	HCNC (g, singlet) → 2 C (g) + H (g) + N (g)	Δ_rH°(0 K) = 366.00 ± 1.60 kcal/mol	Ruscic G4
5.4	8093.4	HCNC (g, singlet) → 2 C (g) + H (g) + N (g)	Δ_rH°(0 K) = 364.22 ± 1.60 kcal/mol	Ruscic CBS-n
4.6	8093.1	HCNC (g, singlet) → 2 C (g) + H (g) + N (g)	Δ_rH°(0 K) = 365.68 ± 1.72 kcal/mol	Ruscic G3X
4.4	8094.5	HCNC (g, triplet) → 2 C (g) + H (g) + N (g)	Δ_rH°(0 K) = 363.84 ± 1.50 kcal/mol	Ruscic W1RO
3.9	8101.5	HCNC (g, singlet) → HCCN (g, singlet)	Δ_rH°(0 K) = -12.81 ± 1.2 kcal/mol	Ruscic W1RO
3.9	8094.4	HCNC (g, triplet) → 2 C (g) + H (g) + N (g)	Δ_rH°(0 K) = 363.88 ± 1.60 kcal/mol	Ruscic CBS-n
3.9	8094.2	HCNC (g, triplet) → 2 C (g) + H (g) + N (g)	Δ_rH°(0 K) = 364.59 ± 1.60 kcal/mol	Ruscic G4
3.3	8094.1	HCNC (g, triplet) → 2 C (g) + H (g) + N (g)	Δ_rH°(0 K) = 364.61 ± 1.72 kcal/mol	Ruscic G3X
3.3	8101.4	HCNC (g, singlet) → HCCN (g, singlet)	Δ_rH°(0 K) = -12.29 ± 1.3 kcal/mol	Ruscic CBS-n
3.3	8101.2	HCNC (g, singlet) → HCCN (g, singlet)	Δ_rH°(0 K) = -12.44 ± 1.3 kcal/mol	Ruscic G4
3.1	8102.5	HCNC (g, triplet) → HCCN (g, triplet)	Δ_rH°(0 K) = -25.31 ± 1.2 kcal/mol	Ruscic W1RO
2.9	8093.3	HCNC (g, singlet) → 2 C (g) + H (g) + N (g)	Δ_rH°(0 K) = 364.33 ± 2.16 kcal/mol	Ruscic CBS-n
2.9	8101.1	HCNC (g, singlet) → HCCN (g, singlet)	Δ_rH°(0 K) = -13.09 ± 1.4 kcal/mol	Ruscic G3X
2.6	8102.2	HCNC (g, triplet) → HCCN (g, triplet)	Δ_rH°(0 K) = -24.95 ± 1.3 kcal/mol	Ruscic G4
2.6	8102.4	HCNC (g, triplet) → HCCN (g, triplet)	Δ_rH°(0 K) = -25.71 ± 1.3 kcal/mol	Ruscic CBS-n
2.5	8101.6	HCNC (g, singlet) → HCCN (g, singlet)	Δ_rH°(0 K) = -12.9 ± 1.5 kcal/mol	Koput 2003, est unc
2.2	8102.1	HCNC (g, triplet) → HCCN (g, triplet)	Δ_rH°(0 K) = -25.95 ± 1.4 kcal/mol	Ruscic G3X
2.2	8101.3	HCNC (g, singlet) → HCCN (g, singlet)	Δ_rH°(0 K) = -12.05 ± 1.6 kcal/mol	Ruscic CBS-n

Top 10 species with enthalpies of formation correlated to the Δ_fH° of HCNC (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	Isocyanomethylene	HCNC (g)	583.1	585.3	± 1.6	kJ/mol	39.0361 ± 0.0016	78694-65-2*0
85.4	Isocyanomethylene	HCNC (g, triplet)	585.2	586.3	± 1.6	kJ/mol	39.0361 ± 0.0016	78694-65-2*2
80.3	Isocyanomethylene anion	[HCNC]- (g)	401.3	402.0	± 2.0	kJ/mol	39.0366 ± 0.0016	144141-01-5*0
49.0	Isocyanomethyliumyl	[HCNC]+ (g)	1506.7	1508.6	± 3.2	kJ/mol	39.0355 ± 0.0016	99045-54-2*0
43.8	Cyanomethylene	HCCN (g, singlet)	529.4	530.4	± 1.3	kJ/mol	39.0361 ± 0.0016	2612-62-6*2
41.4	Cyanomethylene	HCCN (g)	479.6	483.0	± 1.1	kJ/mol	39.0361 ± 0.0016	2612-62-6*0
41.4	Cyanomethylene	HCCN (g, triplet)	479.6	483.0	± 1.1	kJ/mol	39.0361 ± 0.0016	2612-62-6*1
31.2	Cyanomethylene anion	[HCCN]- (g)	286.3	286.8	± 1.5	kJ/mol	39.0366 ± 0.0016	12373-24-9*0
20.1	Cyanomethyliumyl	[HCCN]+ (g)	1506.4	1507.9	± 2.3	kJ/mol	39.0355 ± 0.0016	34447-38-6*0
8.6	Cyanomethyl	CH2CN (g)	262.83	259.95	± 0.53	kJ/mol	40.0440 ± 0.0016	2932-82-3*0

Most Influential reactions involving HCNC (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	8099.1	HCNC (g) → HCNC (g, singlet)	Δ_rH°(0 K) = 0 ± 0 cm-1	triv, Ruscic W1RO, Ruscic G4, Ruscic CBS-n, Ruscic G3X
0.849	8096.1	[HCNC]- (g) → HCNC (g, singlet)	Δ_rH°(0 K) = 1.883 ± 0.013 eV	Nimlos 2002
0.771	8100.8	HCNC (g, singlet) → HCNC (g, triplet)	Δ_rH°(0 K) = 141 ± 80 cm-1	Stanton 2023
0.517	8095.5	HCNC (g, singlet) → [HCNC]+ (g)	Δ_rH°(0 K) = 9.568 ± 0.040 eV	Ruscic W1RO
0.155	8095.2	HCNC (g, singlet) → [HCNC]+ (g)	Δ_rH°(0 K) = 9.587 ± 0.073 eV	Ruscic G4
0.147	8095.4	HCNC (g, singlet) → [HCNC]+ (g)	Δ_rH°(0 K) = 9.576 ± 0.075 eV	Ruscic CBS-n
0.095	8095.1	HCNC (g, singlet) → [HCNC]+ (g)	Δ_rH°(0 K) = 9.580 ± 0.093 eV	Ruscic G3X
0.092	8101.5	HCNC (g, singlet) → HCCN (g, singlet)	Δ_rH°(0 K) = -12.81 ± 1.2 kcal/mol	Ruscic W1RO
0.084	8095.3	HCNC (g, singlet) → [HCNC]+ (g)	Δ_rH°(0 K) = 9.560 ± 0.099 eV	Ruscic CBS-n
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
0.061	8093.5	HCNC (g, singlet) → 2 C (g) + H (g) + N (g)	Δ_rH°(0 K) = 364.13 ± 1.50 kcal/mol	Ruscic W1RO
0.059	8101.6	HCNC (g, singlet) → HCCN (g, singlet)	Δ_rH°(0 K) = -12.9 ± 1.5 kcal/mol	Koput 2003, est unc
0.057	8096.6	[HCNC]- (g) → HCNC (g, singlet)	Δ_rH°(0 K) = 1.889 ± 0.050 eV	Ruscic W1RO
0.054	8093.2	HCNC (g, singlet) → 2 C (g) + H (g) + N (g)	Δ_rH°(0 K) = 366.00 ± 1.60 kcal/mol	Ruscic G4
0.054	8093.4	HCNC (g, singlet) → 2 C (g) + H (g) + N (g)	Δ_rH°(0 K) = 364.22 ± 1.60 kcal/mol	Ruscic CBS-n
0.052	8101.3	HCNC (g, singlet) → HCCN (g, singlet)	Δ_rH°(0 K) = -12.05 ± 1.6 kcal/mol	Ruscic CBS-n
0.047	8093.1	HCNC (g, singlet) → 2 C (g) + H (g) + N (g)	Δ_rH°(0 K) = 365.68 ± 1.72 kcal/mol	Ruscic G3X
0.038	8096.3	[HCNC]- (g) → HCNC (g, singlet)	Δ_rH°(0 K) = 1.901 ± 0.061 eV	Ruscic G4

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.