Selected ATcT [1, 2] enthalpy of formation based on version 1.202 of the Thermochemical Network [3]

This version of ATcT results[3] was generated by additional expansion of version 1.176 in order to include species related to the thermochemistry of glycine[4].

Cyanooxidanyl

Formula: NCO (g)

CAS RN: 22400-26-6

ATcT ID: 22400-26-6*0

SMILES: N#C[O]

InChI: InChI=1S/CNO/c2-1-3

InChIKey: HKKDKUMUWRTAIA-UHFFFAOYSA-N

Hills Formula: C1N1O1

2D Image:

Aliases: Cyanooxidanyl; Cyanato; Cyanato radical; Isocyanato; Isocyanato radical; Cyanate radical; Isocyanate radical; Cyanatyl; Cyanooxy; NCO; OCN; O-C~N; N~C-O

Relative Molecular Mass: 42.01684 ± 0.00086

Δ_fH°(0 K)	Δ_fH°(298.15 K)	Uncertainty	Units
126.96	127.44	± 0.33	kJ/mol

3D Image of NCO (g)

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Top contributors to the provenance of Δ_fH° of NCO (g)

The 20 contributors listed below account only for 70.9% of the provenance of Δ_fH° of NCO (g).
A total of 83 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
17.3	5080.1	HNCO (g) → NCO (g) + H (g)	Δ_rH°(0 K) = 38370 ± 30 cm-1	Zyrianov 1996
15.0	5073.4	NCO (g) → N (g) + CO (g)	Δ_rH°(0 K) = 55.0 ± 0.2 kcal/mol	Cyr 1992, est unc
6.7	5078.1	NCO (g) + O (g) → CO2 (g) + N (g)	Δ_rH°(0 K) = -70.89 ± 0.3 kcal/mol	Schuurman 2004, est unc
5.8	5079.1	NCO (g) + OH (g) → CO2 (g) + NH (g)	Δ_rH°(0 K) = -47.42 ± 0.3 kcal/mol	Schuurman 2004, est unc
4.6	5037.7	HNCO (g) → NH (g) + CO (g)	Δ_rH°(0 K) = 30150 ± 60 cm-1	Zyrianov 1996
1.9	5039.8	HNCO (g) + H2O (g) → CO2 (g) + NH3 (g)	Δ_rH°(0 K) = -18.46 ± 0.3 kcal/mol	Schuurman 2004, est unc
1.9	8058.1	NH2C(O)NH2 (g) → [NH3]+ (g) + HNCO (g)	Δ_rH°(0 K) = 10.838 ± 0.010 eV	Bodi 2013
1.9	5031.11	HNCO (g) → H (g) + N (g) + C (g) + O (g)	Δ_rH°(0 K) = 420.73 ± 0.30 kcal/mol	Karton 2011
1.8	5037.8	HNCO (g) → NH (g) + CO (g)	Δ_rH°(0 K) = 30075 ± 25 (×3.748) cm-1	Sanov 1997
1.8	5083.1	HNCO (g) + N (g) → NCO (g) + NH (g)	Δ_rH°(0 K) = 31.39 ± 0.3 kcal/mol	Schuurman 2004, est unc
1.5	5040.6	HNCO (g) + O (g) → NH (g) + CO2 (g)	Δ_rH°(0 K) = -39.33 ± 0.3 kcal/mol	Schuurman 2004, est unc
1.4	5080.12	HNCO (g) → NCO (g) + H (g)	Δ_rH°(0 K) = 109.76 ± 0.3 kcal/mol	Schuurman 2004, est unc
1.4	5084.1	3 HNCO (g) + N (g) → 3 NCO (g) + NH3 (g)	Δ_rH°(0 K) = 52.38 ± 0.9 kcal/mol	Schuurman 2004, est unc
1.3	5037.9	HNCO (g) → NH (g) + CO (g)	Δ_rH°(0 K) = 30060 ± 25 (×4.362) cm-1	Zyrianov 1999
1.3	5036.1	NH3 (g) + CH4 (g) + H2O (g) → HNCO (g) + 4 H2 (g)	Δ_rH°(0 K) = 228.35 ± 1.50 kJ/mol	Klippenstein 2017
1.1	5072.1	NH3 (g) + CH4 (g) + H2O (g) → NCO (g) + 9/2 H2 (g)	Δ_rH°(0 K) = 471.25 ± 3.00 kJ/mol	Klippenstein 2017
0.9	5080.13	HNCO (g) → NCO (g) + H (g)	Δ_rH°(0 K) = 458.99 ± 1.50 kJ/mol	Klippenstein 2017
0.8	5082.8	HNCO (g) → [NCO]- (g) + H+ (g)	Δ_rH°(0 K) = 340.17 ± 0.3 kcal/mol	Schuurman 2004, est unc
0.8	5042.11	HOCN (g) → H (g) + N (g) + C (g) + O (g)	Δ_rH°(0 K) = 395.98 ± 0.30 kcal/mol	Karton 2011
0.8	5056.11	HONC (g) → H (g) + N (g) + C (g) + O (g)	Δ_rH°(0 K) = 336.83 ± 0.30 kcal/mol	Karton 2011

Top 10 species with enthalpies of formation correlated to the Δ_fH° of NCO (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
63.9	Isocyanic acid	HNCO (g)	-115.93	-118.93	± 0.28	kJ/mol	43.02478 ± 0.00086	75-13-8*0
56.3	Cyanate	[NCO]- (g)	-221.16	-221.38	± 0.53	kJ/mol	42.01739 ± 0.00086	661-20-1*0
54.9	Cyanato cation	[NCO]+ (g)	1261.52	1262.02	± 0.58	kJ/mol	42.01629 ± 0.00086	17247-99-3*0
35.6	Isocyanic acid cation	[HNCO]+ (g)	1003.01	1000.35	± 0.49	kJ/mol	43.02423 ± 0.00086	444010-28-0*0
27.2	Isofulminic acid	HONC (g)	235.25	233.55	± 0.43	kJ/mol	43.02478 ± 0.00086	506-85-4*0
27.1	Cyanic acid	HOCN (g)	-12.32	-15.03	± 0.43	kJ/mol	43.02478 ± 0.00086	420-05-3*0
26.3	Fulminic acid	HCNO (g)	170.73	169.27	± 0.44	kJ/mol	43.02478 ± 0.00086	51060-05-0*0
15.9	Nitrosomethylidyne	CNO (g)	389.4	390.7	± 1.1	kJ/mol	42.01684 ± 0.00086	82267-15-0*0
13.8	Imidogen	NH (g)	358.75	358.80	± 0.16	kJ/mol	15.014680 ± 0.000099	13774-92-0*0
13.8	Imidogen	NH (g, triplet)	358.75	358.80	± 0.16	kJ/mol	15.014680 ± 0.000099	13774-92-0*1

Most Influential reactions involving NCO (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
0.801	5069.1	[NCO]- (g) → NCO (g)	Δ_rH°(0 K) = 3.609 ± 0.005 eV	Bradforth 1993
0.682	5068.1	NCO (g) → [NCO]+ (g)	Δ_rH°(0 K) = 11.759 ± 0.006 eV	Ruscic 1994b
0.524	5080.1	HNCO (g) → NCO (g) + H (g)	Δ_rH°(0 K) = 38370 ± 30 cm-1	Zyrianov 1996
0.245	5068.2	NCO (g) → [NCO]+ (g)	Δ_rH°(0 K) = 11.76 ± 0.01 eV	Dyke 1983
0.151	5073.4	NCO (g) → N (g) + CO (g)	Δ_rH°(0 K) = 55.0 ± 0.2 kcal/mol	Cyr 1992, est unc
0.118	5092.9	NCO (g) → CNO (g)	Δ_rH°(0 K) = 262.90 ± 3.00 kJ/mol	Klippenstein 2017
0.079	5101.8	C(NO) (g) → NCO (g)	Δ_rH°(0 K) = -77.01 ± 1.2 kcal/mol	Ruscic W1RO
0.079	5101.7	C(NO) (g) → NCO (g)	Δ_rH°(0 K) = -77.12 ± 1.2 kcal/mol	Ruscic CBS-n
0.075	5079.1	NCO (g) + OH (g) → CO2 (g) + NH (g)	Δ_rH°(0 K) = -47.42 ± 0.3 kcal/mol	Schuurman 2004, est unc
0.068	5101.4	C(NO) (g) → NCO (g)	Δ_rH°(0 K) = -76.92 ± 1.3 kcal/mol	Ruscic G4
0.067	5078.1	NCO (g) + O (g) → CO2 (g) + N (g)	Δ_rH°(0 K) = -70.89 ± 0.3 kcal/mol	Schuurman 2004, est unc
0.058	5101.3	C(NO) (g) → NCO (g)	Δ_rH°(0 K) = -78.49 ± 1.4 kcal/mol	Ruscic G3X
0.056	5083.1	HNCO (g) + N (g) → NCO (g) + NH (g)	Δ_rH°(0 K) = 31.39 ± 0.3 kcal/mol	Schuurman 2004, est unc
0.044	5101.6	C(NO) (g) → NCO (g)	Δ_rH°(0 K) = -77.31 ± 1.6 kcal/mol	Ruscic CBS-n
0.043	5084.1	3 HNCO (g) + N (g) → 3 NCO (g) + NH3 (g)	Δ_rH°(0 K) = 52.38 ± 0.9 kcal/mol	Schuurman 2004, est unc
0.042	5080.12	HNCO (g) → NCO (g) + H (g)	Δ_rH°(0 K) = 109.76 ± 0.3 kcal/mol	Schuurman 2004, est unc
0.042	5092.8	NCO (g) → CNO (g)	Δ_rH°(0 K) = 63.01 ± 1.2 kcal/mol	Ruscic W1RO
0.036	5092.7	NCO (g) → CNO (g)	Δ_rH°(0 K) = 62.49 ± 1.3 kcal/mol	Ruscic CBS-n
0.036	5092.4	NCO (g) → CNO (g)	Δ_rH°(0 K) = 62.55 ± 1.3 kcal/mol	Ruscic G4
0.031	5092.3	NCO (g) → CNO (g)	Δ_rH°(0 K) = 63.39 ± 1.4 kcal/mol	Ruscic G3X

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. 1.202 of the Thermochemical Network (2024); available at ATcT.anl.gov
4		B. Ruscic and D. H. Bross Accurate and Reliable Thermochemistry by Data Analysis of Complex Thermochemical Networks using Active Thermochemical Tables: The Case of Glycine Thermochemistry Faraday Discuss. (in press) (2024) [DOI: 10.1039/D4FD00110A]
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.