Isocyanic acid

Formula: CHNO
Molecular weight: 43.0247
IUPAC Standard InChI: InChI=1S/CHNO/c2-1-3/h2H
IUPAC Standard InChIKey: OWIKHYCFFJSOEH-UHFFFAOYSA-N
CAS Registry Number: 75-13-8
Chemical structure:
This structure is also available as a 2d Mol file or as a computed 3d SD file
The 3d structure may be viewed using Java or Javascript.
Permanent link for this species. Use this link for bookmarking this species for future reference.
Information on this page:
Other data available:
Data at other public NIST sites:
- Computational Chemistry Comparison and Benchmark Database
- Gas Phase Kinetics Database
Options:
- Switch to calorie-based units

Vibrational and/or electronic energy levels

Data compiled as indicated in comments:
J - Marilyn E. Jacox
Shim - Takehiko Shimanouchi

State: ?

Energy (cm^-1)	Med.	λ_min (nm)	λ_max (nm)	References


T_d	gas	120	133	Okabe, 1970

State: ?

Energy (cm^-1)	Med.	λ_min (nm)	λ_max (nm)	References


72940	gas	134	137	Okabe, 1970

State: ?

Energy (cm^-1)	Med.	λ_min (nm)	λ_max (nm)	References


T_d	gas	147	163	Okabe, 1970

State: ?

Energy (cm^-1)	Med.	λ_min (nm)	λ_max (nm)	References


T_d	gas	163	185	Okabe, 1970

State: ?

Energy (cm^-1)	Med.	λ_min (nm)	λ_max (nm)	References


T_d = 41000	gas	200U	244	Dixon and Kirby, 1968

State: A

Energy (cm^-1)	Med.	Transition	λ_min (nm)	λ_max (nm)	References


T_o = 32449 ± 20	gas	A-X	228	282	Dixon and Kirby, 1968
					Berghout, Crim, et al., 2000

Vib. sym.	No.	Approximate type of mode	cm^-1	Med.	Method	References


a'	3	HNC bend	1192 ± 10	gas	PF	Berghout, Crim, et al., 2000
	4	NC stretch	1034 ± 20	gas	PF	Berghout, Crim, et al., 2000
	5	NCO bend	599 ± 7	gas	PF	Berghout, Crim, et al., 2000

State: X

Vib. sym.	No.	Approximate type of mode	cm^-1		Med.	Method	References


a'	1	NH stretch	3538.24	s	gas	IR Ra	Herzberg and Reid, 1950 Reid, 1950 Teles, Maier, et al., 1989 Yamada, Winnewisser, et al., 1990 Brown, Berghout, et al., 1997
	1	NH stretch	3516.8	w m	Ar	IR	Teles, Maier, et al., 1989
	1	NH stretch	3505.7	w m	Ar	IR	Teles, Maier, et al., 1989
	1	NH stretch	3514.7		Kr	IR	Pettersson, Khriachtchev, et al., 1999
	1	NH stretch	3500.6		Kr	IR	Pettersson, Khriachtchev, et al., 1999
	1	NH stretch	3485.2		Xe	IR	Pettersson, Khriachtchev, et al., 1999
	1	NH stretch	3483.0		Xe	IR	Pettersson, Khriachtchev, et al., 1999
	1	NH stretch	3479.9		Xe	IR	Pettersson, Khriachtchev, et al., 1999
	2	NCO a-stretch	2268.89	vs	gas	IR	Herzberg and Reid, 1950 Reid, 1950 Lemoine, Yamada, et al., 1982 Steiner, Polo, et al., 1983 Brown, Berghout, et al., 1997, 2
	2	NCO a-stretch	2259.0	vs	Ar	IR	Teles, Maier, et al., 1989 Crowley and Sodeau, 1989
	2	NCO a-stretch	2261.6		Kr	IR	Pettersson, Khriachtchev, et al., 1999
	2	NCO a-stretch	2254.4		Xe	IR	Pettersson, Khriachtchev, et al., 1999
	3	NCO s-stretch	1327	w	gas	IR	Herzberg and Reid, 1950 Reid, 1950 Brown, Berghout, et al., 1997, 2
	4	HNC, NCO bend	776.62	w m	gas	IR	Steiner, Wishah, et al., 1979
	4	HNC, NCO bend	769.8	w m	Ar	IR	Teles, Maier, et al., 1989 Crowley and Sodeau, 1989
	4	HNC, NCO bend	763.6		Kr	IR	Pettersson, Khriachtchev, et al., 1999
	4	HNC, NCO bend	765.1		Xe	IR	Pettersson, Khriachtchev, et al., 1999
	4	HNC, NCO bend	760.3		Xe	IR	Pettersson, Khriachtchev, et al., 1999
	5	HNC, NCO bend	577.35	w	gas	IR	Herzberg and Reid, 1950 Reid, 1950 Steiner, Wishah, et al., 1979
	5	HNC, NCO bend	573.7	w m	Ar	IR	Teles, Maier, et al., 1989 Crowley and Sodeau, 1989
	5	HNC, NCO bend	572.9		Kr	IR	Pettersson, Khriachtchev, et al., 1999
	5	HNC, NCO bend	571.3		Kr	IR	Pettersson, Khriachtchev, et al., 1999
	5	HNC, NCO bend	574.2		Xe	IR	Pettersson, Khriachtchev, et al., 1999
	5	HNC, NCO bend	570.3		Xe	IR	Pettersson, Khriachtchev, et al., 1999
a	6	Torsion	656.29		gas	IR	Steiner, Wishah, et al., 1979 Fusina, Carlotti, et al., 1984
	6	Torsion (1-0)	695.6		Kr	IR	Pettersson, Khriachtchev, et al., 1999
	6	Torsion (1-0)	694.7		Xe	IR	Pettersson, Khriachtchev, et al., 1999

Additional references: Jacox, 1994, page 163; Jacox, 1998, page 236; Jacox, 2003, page 190; Ashby and Werner, 1966; Yamada, 1980; Steiner, Polo, et al., 1981

Notes

Weak

Medium

Strong

Very strong

Energy separation between the v = 0 levels of the excited and electronic ground states.

Photodissociation threshold

References

Go To: Top, Vibrational and/or electronic energy levels, Notes

Okabe, 1970
Okabe, H., J. Chem. Phys., 1970, 53, 3507. [all data]

Dixon and Kirby, 1968
Dixon, R.N.; Kirby, G.H., Ultra-violet absorption spectrum of isocyanic acid, Trans. Faraday Soc., 1968, 64, 2002, https://doi.org/10.1039/tf9686402002 . [all data]

Berghout, Crim, et al., 2000
Berghout, H.L.; Crim, F.F.; Zyrianov, M.; Reisler, H., The electronic origin and vibrational levels of the first excited singlet state of isocyanic acid (HNCO), J. Chem. Phys., 2000, 112, 15, 6678, https://doi.org/10.1063/1.481242 . [all data]

Herzberg and Reid, 1950
Herzberg, G.; Reid, C., Infra-red spectrum and structure of the HNCO molecule, Discuss. Faraday Soc., 1950, 9, 92, https://doi.org/10.1039/df9500900092 . [all data]

Reid, 1950
Reid, C., Rotation-Vibration Spectra of Diatomic and Simple Polyatomic Molecules with Long Absorbing Paths V. The Spectrum of Isocyanic Acid, J. Chem. Phys., 1950, 18, 12, 1544, https://doi.org/10.1063/1.1747538 . [all data]

Teles, Maier, et al., 1989
Teles, J.H.; Maier, G.; Hess, B.A., Jr.; Schaad, L.J.; Winnewisser, M.; Winnewisser, B.P., The CHNO Isomers, Chem. Ber., 1989, 122, 4, 753, https://doi.org/10.1002/cber.19891220425 . [all data]

Yamada, Winnewisser, et al., 1990
Yamada, K.M.T.; Winnewisser, M.; Johns, J.W.C., High-resolution spectrum of the ν1 fundamental band of isocyanic acid, HNCO, J. Mol. Spectrosc., 1990, 140, 2, 353, https://doi.org/10.1016/0022-2852(90)90147-I . [all data]

Brown, Berghout, et al., 1997
Brown, S.S.; Berghout, H.L.; Crim, F.F., Raman spectroscopy of the ν1 N--H stretch fundamental in isocyanic acid (HNCO): State mixing probed by photoacoustic spectroscopy and by photodissociation of vibrationally excited states, J. Chem. Phys., 1997, 106, 14, 5805, https://doi.org/10.1063/1.473246 . [all data]

Pettersson, Khriachtchev, et al., 1999
Pettersson, M.; Khriachtchev, L.; Jolkkonen, S.; Rasanen, M., Photochemistry of HNCO in Solid Xe: Channels of UV Photolysis and Creation of H, J. Phys. Chem. A, 1999, 103, 45, 9154, https://doi.org/10.1021/jp992224d . [all data]

Lemoine, Yamada, et al., 1982
Lemoine, B.; Yamada, K.; Winnewisser, G., Diode Laser Spectrum of the Fundamental v2 Band of HNCO, Ber. Bunsenges. Phys. Chem., 1982, 86, 9, 795, https://doi.org/10.1002/bbpc.19820860906 . [all data]

Steiner, Polo, et al., 1983
Steiner, D.A.; Polo, S.R.; McCubbin, T.K.; Wishah, K.A., Infrared spectrum of the fundamental ν2 of isocyanic acid, J. Mol. Spectrosc., 1983, 98, 2, 453, https://doi.org/10.1016/0022-2852(83)90254-0 . [all data]

Brown, Berghout, et al., 1997, 2
Brown, S.S.; Berghout, H.L.; Crim, F.F., Raman spectroscopy of the N--C--O symmetric (ν[sub 3]) and antisymmetric (ν[sub 2]) stretch fundamentals in HNCO, J. Chem. Phys., 1997, 107, 23, 9764, https://doi.org/10.1063/1.475274 . [all data]

Crowley and Sodeau, 1989
Crowley, J.N.; Sodeau, J.R., Reaction between hydrocyanic acid and O(1D2) or O(3P) oxygen atoms in low-temperature matrixes, J. Phys. Chem., 1989, 93, 8, 3100, https://doi.org/10.1021/j100345a044 . [all data]

Steiner, Wishah, et al., 1979
Steiner, D.A.; Wishah, K.A.; Polo, S.R.; McCubbin, T.K., Infrared spectrum of isocyanic acid between 465 and 1100 cm-1, J. Mol. Spectrosc., 1979, 76, 1-3, 341, https://doi.org/10.1016/0022-2852(79)90233-9 . [all data]

Fusina, Carlotti, et al., 1984
Fusina, L.; Carlotti, M.; Carli, B., Infrared spectrum of HNCO between 8 and 80 cm, Can. J. Phys., 1984, 62, 12, 1452, https://doi.org/10.1139/p84-192 . [all data]

Jacox, 1994
Jacox, M.E., Vibrational and electronic energy levels of polyatomic transient molecules, American Chemical Society, Washington, DC, 1994, 464. [all data]

Jacox, 1998
Jacox, M.E., Vibrational and electronic energy levels of polyatomic transient molecules: supplement A, J. Phys. Chem. Ref. Data, 1998, 27, 2, 115-393, https://doi.org/10.1063/1.556017 . [all data]

Jacox, 2003
Jacox, M.E., Vibrational and electronic energy levels of polyatomic transient molecules: supplement B, J. Phys. Chem. Ref. Data, 2003, 32, 1, 1-441, https://doi.org/10.1063/1.1497629 . [all data]

Ashby and Werner, 1966
Ashby, R.A.; Werner, R.L., The infra-red absorption spectrum of DNCO, Spectrochim. Acta, 1966, 22, 7, 1345, https://doi.org/10.1016/0371-1951(66)80038-3 . [all data]

Yamada, 1980
Yamada, K., Molecular structure and centrifugal distortion constants of isocyanic acid from the microwave, millimeter wave, and far-infrared spectra, J. Mol. Spectrosc., 1980, 79, 2, 323, https://doi.org/10.1016/0022-2852(80)90217-9 . [all data]

Steiner, Polo, et al., 1981
Steiner, D.A.; Polo, S.R.; McCubbin, T.K.; Wishah, K.A., Infrared spectrum of the fundamental ν, Can. J. Phys., 1981, 59, 10, 1313, https://doi.org/10.1139/p81-172 . [all data]

Notes

Go To: Top, Vibrational and/or electronic energy levels, References

Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
The National Institute of Standards and Technology (NIST) uses its best efforts to deliver a high quality copy of the Database and to verify that the data contained therein have been selected on the basis of sound scientific judgment. However, NIST makes no warranties to that effect, and NIST shall not be liable for any damage that may result from errors or omissions in the Database.
Customer support for NIST Standard Reference Data products.