Selected ATcT [1, 2] enthalpy of formation based on version 1.124 of the Thermochemical Network [3]

This version of ATcT results was generated by additional expansion of version 1.122x [4] to include additional information relevant to the study of thermophysical and thermochemical properties of CH2 and CH3 using nonrigid rotor anharmonic oscillator (NRRAO) partition functions [5], the development and benchmarking of a state-of-the-art computational approach that aims to reproduce total atomization energies of small molecules within 10–15 cm-1 [6], as well as the study of the reversible reaction C2H3 + H2 ⇌ C2H4 + H ⇌ C2H5 [7]

Isocyanic acid

Formula: HNCO (g)
CAS RN: 75-13-8
ATcT ID: 75-13-8*0
SMILES: N=C=O
InChI: InChI=1S/CHNO/c2-1-3/h2H
InChIKey: OWIKHYCFFJSOEH-UHFFFAOYSA-N
Hills Formula: C1H1N1O1

2D Image:

N=C=O
Aliases: Isocyanic acid; Carbimide; Hydrogen isocyanate; Methenamide; HNCO; OCNH; HN=C=O
Relative Molecular Mass: 43.02478 ± 0.00086

   ΔfH°(0 K)   ΔfH°(298.15 K)UncertaintyUnits
-115.96-118.95± 0.28kJ/mol

3D Image of HNCO (g)

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Top contributors to the provenance of ΔfH° of HNCO (g)

The 20 contributors listed below account only for 68.4% of the provenance of ΔfH° of HNCO (g).
A total of 106 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
11.44531.7 HNCO (g) → NH (g) CO (g) ΔrH°(0 K) = 30150 ± 60 cm-1Zyrianov 1996
6.14567.4 NCO (g) → N (g) CO (g) ΔrH°(0 K) = 55.0 ± 0.2 kcal/molCyr 1992, est unc
4.84533.8 HNCO (g) H2O (g) → CO2 (g) NH3 (g) ΔrH°(0 K) = -18.46 ± 0.3 kcal/molSchuurman 2004, est unc
4.86799.1 NH2C(O)NH2 (g) → [NH3]+ (g) HNCO (g) ΔrH°(0 K) = 10.838 ± 0.010 eVBodi 2013
4.74525.11 HNCO (g) → H (g) N (g) C (g) O (g) ΔrH°(0 K) = 420.73 ± 0.30 kcal/molKarton 2011
4.64531.8 HNCO (g) → NH (g) CO (g) ΔrH°(0 K) = 30075 ± 25 (×3.748) cm-1Sanov 1997
3.74534.6 HNCO (g) O (g) → NH (g) CO2 (g) ΔrH°(0 K) = -39.33 ± 0.3 kcal/molSchuurman 2004, est unc
3.64574.1 HNCO (g) → NCO (g) H (g) ΔrH°(0 K) = 38370 ± 30 cm-1Zyrianov 1996
3.44531.9 HNCO (g) → NH (g) CO (g) ΔrH°(0 K) = 30060 ± 25 (×4.362) cm-1Zyrianov 1999
3.34530.1 NH3 (g) CH4 (g) H2O (g) → HNCO (g) + 4 H2 (g) ΔrH°(0 K) = 228.35 ± 1.50 kJ/molKlippenstein 2017
2.74572.1 NCO (g) O (g) → CO2 (g) N (g) ΔrH°(0 K) = -70.89 ± 0.3 kcal/molSchuurman 2004, est unc
1.94536.11 HOCN (g) → H (g) N (g) C (g) O (g) ΔrH°(0 K) = 395.98 ± 0.30 kcal/molKarton 2011
1.94573.1 NCO (g) OH (g) → CO2 (g) NH (g) ΔrH°(0 K) = -47.42 ± 0.3 kcal/molSchuurman 2004, est unc
1.94550.11 HONC (g) → H (g) N (g) C (g) O (g) ΔrH°(0 K) = 336.83 ± 0.30 kcal/molKarton 2011
1.84531.6 HNCO (g) → NH (g) CO (g) ΔrH°(0 K) = 30022 ± 100 (×1.477) cm-1Brown 1996, Brazier 1986
1.84543.11 HCNO (g) → H (g) N (g) C (g) O (g) ΔrH°(0 K) = 352.25 ± 0.30 kcal/molKarton 2011
1.34541.1 NH3 (g) CH4 (g) H2O (g) → HOCN (g) + 4 H2 (g) ΔrH°(0 K) = 331.66 ± 1.50 kJ/molKlippenstein 2017
1.34553.1 NH3 (g) CH4 (g) H2O (g) → HONC (g) + 4 H2 (g) ΔrH°(0 K) = 579.20 ± 1.50 kJ/molKlippenstein 2017
1.34525.10 HNCO (g) → H (g) N (g) C (g) O (g) ΔrH°(0 K) = 420.71 ± 0.56 kcal/molKarton 2011
1.06801.3 NH2C(O)NH2 (cr,l) → NH2C(O)NH2 (g) ΔrH°(351.3 K) = 96.9 ± 0.6 kJ/molde Wit 1983a, est unc

Top 10 species with enthalpies of formation correlated to the ΔfH° of HNCO (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 Image    ΔfH°(0 K)    ΔfH°(298.15 K) Uncertainty Units Relative
Molecular
Mass
ATcT ID
64.1 CyanooxidanylNCO (g)N#C[O]126.94127.41± 0.33kJ/mol42.01684 ±
0.00086
22400-26-6*0
55.8 Isocyanic acid cation[HNCO]+ (g)[NH+]=C=O1002.991000.32± 0.49kJ/mol43.02423 ±
0.00086
444010-28-0*0
42.4 Isofulminic acidHONC (g)O[N+]#[C-]235.24233.53± 0.43kJ/mol43.02478 ±
0.00086
506-85-4*0
42.1 Cyanic acidHOCN (g)OC#N-12.33-15.04± 0.43kJ/mol43.02478 ±
0.00086
420-05-3*0
41.0 Cyanate[NCO]- (g)N#C[O-]-221.18-221.40± 0.53kJ/mol42.01739 ±
0.00086
661-20-1*0
40.3 Fulminic acidHCNO (g)C#[N+][O-]170.71169.26± 0.44kJ/mol43.02478 ±
0.00086
51060-05-0*0
35.3 Cyanato cation[NCO]+ (g)N#C[O+]1261.501262.00± 0.58kJ/mol42.01629 ±
0.00086
17247-99-3*0
21.4 ImidogenNH (g)[NH]358.74358.79± 0.16kJ/mol15.014680 ±
0.000099
13774-92-0*0
21.4 ImidogenNH (g, triplet)[NH]358.74358.79± 0.16kJ/mol15.014680 ±
0.000099
13774-92-0*1
21.4 Imidogen anion[NH]- (g)[NH-]322.62322.67± 0.16kJ/mol15.015229 ±
0.000099
23841-33-0*0

Most Influential reactions involving HNCO (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
0.6944526.1 HNCO (g) → [HNCO]+ (g) ΔrH°(0 K) = 11.595 ± 0.005 eVRuscic 1994b
0.5254574.1 HNCO (g) → NCO (g) H (g) ΔrH°(0 K) = 38370 ± 30 cm-1Zyrianov 1996
0.3814527.5 [HNCO]- (g) → HNCO (g) ΔrH°(0 K) = -0.646 ± 0.050 eVRuscic W1RO
0.2564527.2 [HNCO]- (g) → HNCO (g) ΔrH°(0 K) = -0.605 ± 0.061 eVRuscic G4
0.2286799.1 NH2C(O)NH2 (g) → [NH3]+ (g) HNCO (g) ΔrH°(0 K) = 10.838 ± 0.010 eVBodi 2013
0.1734526.3 HNCO (g) → [HNCO]+ (g) ΔrH°(0 K) = 11.60 ± 0.01 eVRowland 1968, est unc
0.1624531.7 HNCO (g) → NH (g) CO (g) ΔrH°(0 K) = 30150 ± 60 cm-1Zyrianov 1996
0.1554547.11 HCNO (g) → HNCO (g) ΔrH°(0 K) = -68.48 ± 0.25 kcal/molKarton 2011
0.1464576.8 HNCO (g) → [NCO]- (g) H+ (g) ΔrH°(0 K) = 340.17 ± 0.3 kcal/molSchuurman 2004, est unc
0.1464542.11 HOCN (g) → HNCO (g) ΔrH°(0 K) = -24.75 ± 0.25 kcal/molKarton 2011
0.1434554.11 HONC (g) → HNCO (g) ΔrH°(0 K) = -83.90 ± 0.25 kcal/molKarton 2011
0.1324527.1 [HNCO]- (g) → HNCO (g) ΔrH°(0 K) = -0.667 ± 0.085 eVRuscic G3X
0.1174527.4 [HNCO]- (g) → HNCO (g) ΔrH°(0 K) = -0.667 ± 0.090 eVRuscic CBS-n
0.1124527.3 [HNCO]- (g) → HNCO (g) ΔrH°(0 K) = -0.634 ± 0.092 eVRuscic CBS-n
0.1014542.13 HOCN (g) → HNCO (g) ΔrH°(0 K) = -24.58 ± 0.3 kcal/molSchuurman 2004, est unc
0.0994554.13 HONC (g) → HNCO (g) ΔrH°(0 K) = -83.97 ± 0.3 kcal/molSchuurman 2004, est unc
0.0714542.14 HOCN (g) → HNCO (g) ΔrH°(0 K) = -103.31 ± 1.50 kJ/molKlippenstein 2017
0.0706836.5 [NH2CO]+ (g) NH3 (g) → HNCO (g) [NH4]+ (g) ΔrH°(0 K) = -30.92 ± 0.8 kcal/molRuscic W1RO
0.0706837.5 [NH2CO]+ (g) H2O (g) → HNCO (g) [H3O]+ (g) ΔrH°(0 K) = 8.16 ± 0.8 kcal/molRuscic W1RO
0.0694554.14 HONC (g) → HNCO (g) ΔrH°(0 K) = -350.85 ± 1.50 kJ/molKlippenstein 2017


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 21st 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. 1.124 of the Thermochemical Network, Argonne National Laboratory, Lemont, Illinois 2022; available at ATcT.anl.gov
[DOI: 10.17038/CSE/1885923]
4   Y. Ren, L. Zhou, A. Mellouki, V. Daële, M. Idir, S. S. Brown, B. Ruscic, Robert S. Paton, M. R. McGillen, and A. R. Ravishankara,
Reactions of NO3 with Aromatic Aldehydes: Gas-Phase Kinetics and Insights into the Mechanism of the Reaction.
Atmos. Chem. Phys. 21, 13537-13551 (2021) [DOI: 10.5194/acp2021-228]
5   B. Ruscic and D. H. Bross,
Active Thermochemical Tables: The Thermophysical and Thermochemical Properties of Methyl, CH3, and Methylene, CH2, Corrected for Nonrigid Rotor and Anharmonic Oscillator Effects.
Mol. Phys. e1969046 (2021) [DOI: 10.1080/00268976.2021.1969046]
6   J. H. Thorpe, J. L. Kilburn, D. Feller, P. B. Changala, D. H. Bross, B. Ruscic, and J. F. Stanton,
Elaborated Thermochemical Treatment of HF, CO, N2, and H2O: Insight into HEAT and Its Extensions
J. Chem. Phys. 155, 184109 (2021) [DOI: 10.1063/5.0069322]
7   T. L. Nguyen, D. H. Bross, B. Ruscic, G. B. Ellison, and J. F. Stanton,
Mechanism, Thermochemistry, and Kinetics of the Reversible Reactions: C2H3 + H2 ⇌ C2H4 + H ⇌ C2H5.
Faraday Discuss. , (Advance Article) (2022) [DOI: 10.1039/D1FD00124H]
8   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]
9   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 [8,9]).
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.