Monochlorine monoxide

Formula: ClO
Molecular weight: 51.452
IUPAC Standard InChI: InChI=1S/ClO/c1-2
IUPAC Standard InChIKey: NHYCGSASNAIGLD-UHFFFAOYSA-N
CAS Registry Number: 14989-30-1
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:
- Gas phase thermochemistry data
- Reaction thermochemistry data
Data at other public NIST sites:
- Microwave spectra (on physics lab web site)
- Gas Phase Kinetics Database
Options:
- Switch to calorie-based units

Data at NIST subscription sites:

NIST / TRC Web Thermo Tables, professional edition (thermophysical and thermochemical data)

NIST subscription sites provide data under the NIST Standard Reference Data Program, but require an annual fee to access. The purpose of the fee is to recover costs associated with the development of data collections included in such sites. Your institution may already be a subscriber. Follow the links above to find out more about the data in these sites and their terms of usage.

Gas phase ion energetics data

Go To: Top, Constants of diatomic molecules, References, Notes

Data evaluated as indicated in comments:
L - Sharon G. Lias

Data compiled as indicated in comments:
LL - Sharon G. Lias and Joel F. Liebman
LLK - Sharon G. Lias, Rhoda D. Levin, and Sherif A. Kafafi
RDSH - Henry M. Rosenstock, Keith Draxl, Bruce W. Steiner, and John T. Herron
B - John E. Bartmess

View reactions leading to ClO⁺ (ion structure unspecified)

Quantity	Value	Units	Method	Reference	Comment
IE (evaluated)	10.89 ± 0.02	eV	N/A	N/A	L

Electron affinity determinations

EA (eV)	Method	Reference	Comment
2.2775 ± 0.0013	ZEKE	Distelrath and Boesl, 2000	B
2.2760 ± 0.0060	LPES	Gilles, Polak, et al., 1992	B
2.35 ± 0.15	EIAE	Baluev, Nikitin, et al., 1980	From Cl₂O; B
2.17 ± 0.23	LPD	Lee, Smith, et al., 1979	B
1.95 ± 0.25	IMRB	Dotan, Albritton, et al., 1978	B
>1.62 ± 0.22	R-A	Vogt, Dreves, et al., 1977	Cl^- + O₂ ->.; B

Ionization energy determinations

IE (eV)	Method	Reference	Comment
10.885 ± 0.016	PI	Thorn, Stief, et al., 1996	LL
11.08 ± 0.05	EI	Alekseev, Zyubina, et al., 1989	LL
11.0	EVAL	Huber and Herzberg, 1979	LLK
10.95	PE	Bulgin, Dyke, et al., 1979	LLK
11.1 ± 0.1	EI	Fisher, 1967	RDSH
11.01 ± 0.01	PE	Bulgin, Dyke, et al., 1979	Vertical value; LLK

Constants of diatomic molecules

Go To: Top, Gas phase ion energetics data, References, Notes

Data compiled by: Klaus P. Huber and Gerhard H. Herzberg

Data collected through September, 1976

Symbols used in the table of constants
Symbol	Meaning
State	electronic state and / or symmetry symbol
T_e	minimum electronic energy (cm^-1)
ω_e	vibrational constant – first term (cm^-1)
ω_ex_e	vibrational constant – second term (cm^-1)
ω_ey_e	vibrational constant – third term (cm^-1)
B_e	rotational constant in equilibrium position (cm^-1)
α_e	rotational constant – first term (cm^-1)
γ_e	rotation-vibration interaction constant (cm^-1)
D_e	centrifugal distortion constant (cm^-1)
β_e	rotational constant – first term, centrifugal force (cm^-1)
r_e	internuclear distance (Å)
Trans.	observed transition(s) corresponding to electronic state
ν₀₀	position of 0-0 band (units noted in table)

Diatomic constants for ³⁵Cl¹⁶O
State	T_e	ω_e	ω_ex_e	ω_ey_e	B_e	α_e	γ_e	D_e	β_e	r_e	Trans.	ν₀₀
Several unclassified absorption bands in the region 67000 - 79000 cm^-1.
↳Basco and Morse, 1973
H	(74125)	(1025) H									H ← X V	74212 H
H	↳Basco and Morse, 1973
G (²Π)	73913	1075 H	10								G ← X V	73705 H
	↳missing citation
	73878	1075 H	10								G ← X V	73986 H
	↳missing citation
State	T_e	ω_e	ω_ex_e	ω_ey_e	B_e	α_e	γ_e	D_e	β_e	r_e	Trans.	ν₀₀
F (²Σ)	69109	[1001] 1 H									F ← X V	68869 H
	↳missing citation
	69109	[1001] 1 H									F ← X V	69181 H
	↳missing citation
E (²Σ)	67333	1070 H	4								E ← X V	67120 H
	↳missing citation
	67333	1070 H	4								E ← X V	67445 H
	↳missing citation
State	T_e	ω_e	ω_ex_e	ω_ey_e	B_e	α_e	γ_e	D_e	β_e	r_e	Trans.	ν₀₀
D (²Σ)	64486	1050 H	2								D ← X V	64269 H
	↳missing citation
	64486	1050 H	2								D ← X V	64582 H
	↳missing citation
C (²Σ)	58448	1062 H	3								C ← X V	58234 H
	↳missing citation
	58448	1062 H	3								C ← X V	58554 H
	↳missing citation
State	T_e	ω_e	ω_ex_e	ω_ey_e	B_e	α_e	γ_e	D_e	β_e	r_e	Trans.	ν₀₀
A ²Π_i	32169	519.₅ Z	7.2 2	-0.11	0.445₀ 3	0.006	0.00002₄	[1.31E-6]		1.858	A ↔ X R	31682.₉ 4 Z
	↳Pannetier and Gaydon, 1948; Porter, 1950; missing citation; missing citation; missing citation; missing citation
	31650	519.₅ Z	7.2 2	-0.11	0.445₀ 3	0.006	0.00002₄	[1.31E-6]		1.858	A ↔ X R	31482.₃ 4 Z
	↳Pannetier and Gaydon, 1948; Porter, 1950; missing citation; missing citation; missing citation; missing citation
X ²Π_i	318 5	853.₈ 6 Z	5.5	-0.02	0.62344₈ 7	0.0058	0.000016	[1.33E-6]		1.56963 8
	↳Andrews and Raymond, 1971; Chi and Andrews, 1973
	0	853.₈ 6 Z	5.5	-0.02	0.62344₈ 7	0.0058	0.000016	[1.33E-6]		1.56963 9
	↳Amano, Hirota, et al., 1968; Amano, Saito, et al., 1969
	EPR sp. 10
	↳Carrington, Dyer, et al., 1967; Carrington, Levy, et al., 1967; Uehara and Morino, 1970; Uehara, Tanimoto, et al., 1971

Notes

ΔG(3/2) = 950, ΔG(5/2) = 980.

see 3

In absorption observed to v'=25 of ²Π_3/2 [B_v, D_v values in Coxon and Ramsay, 1976, Coxon, Jones, et al., 1976] close to the dissociation limit at 38052 cm^-1 above X ²Π_3/2(v=0). The constants are for levels with v≤9. All absorption and emission bands are diffuse on account of predissociation. Linewidths in different bands vary from 0.3 to 3.1 cm^-1 and are >5 cm^-1 in v'=6 Coxon and Ramsay, 1976.

Note that there have been several changes of vibrational numbering [see, e.g., Briggs, 1972]; here we have used that of Coxon and Ramsay, 1976 and Coxon, Jones, et al., 1976.

From the VUV absorption spectrum Basco and Morse, 1973; confirmed by EPR spectrum Carrington, Dyer, et al., 1967, Uehara, Tanimoto, et al., 1971.

missing note

From combined microwave and ultraviolet data; the microwave values of Amano, Saito, et al., 1969 are B₀(²Π_3/2) = 0.6l9773 and B₀(²Π_1/2) = 0.621231. Λ-type doubling in the ²Π_1/2 component, Δv_fe = +0.02249(J+1/2).

Matrix IR and Raman sp.

Microwave sp. 10

Dipole moment from Stark effect of microwave spectrum μ_el(v=0) = 1.23₉ D Amano, Saito, et al., 1969, from Stark effect of EPR spectrum 1.1₈D Carrington, Levy, et al., 1967. eqQ and other hyperfine structure constants in Amano, Saito, et al., 1969, Uehara, Tanimoto, et al., 1971

From the convergence limit of the A ← X, ²Π_3/2 ← ²Π_3/2 subbands Coxon and Ramsay, 1976 assuming dissociation into ²P_3/2 + ¹D

Mass-spectrometric studies and theoretical calculations; see O'Hare and Wahl, 1971.

The effective w_e values for ²Π_1/2 and ²Π_3/2 are 853.₀ and 854.9 cm^-1, respectively Coxon, Jones, et al., 1976.

Indirectly from thermochemical data and mass-spectrometric studies; also theoretical calculations; see O'Hare and Wahl, 1971.

References

Go To: Top, Gas phase ion energetics data, Constants of diatomic molecules, Notes

Distelrath and Boesl, 2000
Distelrath, V.; Boesl, U., Mass selective gas phase study of ClO, OClO, ClOO and ClAr by anion-ZEKE-photoelectron spectroscopy, Faraday Disc. Chem. Soc., 2000, 115, 161-174, https://doi.org/10.1039/a909618c . [all data]

Gilles, Polak, et al., 1992
Gilles, M.K.; Polak, M.L.; Lineberger, W.C., Photoelectron Spectroscopy of the Halogen Oxide Anions FO-, ClO-, BrO-, IO-, OClO-, and OIO-, J. Chem. Phys., 1992, 96, 11, 8012, https://doi.org/10.1063/1.462352 . [all data]

Baluev, Nikitin, et al., 1980
Baluev, A.V.; Nikitin, I.M.; Fedorova, L.I.; Rossolovskii, V.Ya., Mass Spectrometric Study of Chlorine Pentafluoride Ionization by Electron Impact, Izv. Akad. Nauk SSR Ser. Khim. 487, 1980. [all data]

Lee, Smith, et al., 1979
Lee, L.C.; Smith, G.P.; Moseley, J.T.; Cosby, P.C.; Guest, J.A., Photodissociation and photodetachment of Cl₂-, ClO-, Cl₃-, and BrCl₂-, J. Chem. Phys., 1979, 70, 3237. [all data]

Dotan, Albritton, et al., 1978
Dotan, I.; Albritton, D.L.; Fehsenfeld, F.C.; Streit, G.E.; Ferguson, E.E., Rate constants for the reactions of O^-, O₂^-, NO₂^-, CO₃^-, and CO₄^- with HCl and ClO- with NO, NO₂, SO₂, and CO₂ at 300K, J. Chem. Phys., 1978, 68, 5414. [all data]

Vogt, Dreves, et al., 1977
Vogt, D.; Dreves, W.; Mischke, J., Energy dependence of differential cross sections in endoergic ion-molecule collision processes of negative ions, Int. J. Mass Spectrom. Ion Phys., 1977, 24, 285. [all data]

Thorn, Stief, et al., 1996
Thorn, R.P., Jr.; Stief, L.J.; Kuo, S.-C.; Klemm, R.B., Ionization energy of Cl₂O and ClO, appearance energy of ClO⁺(Cl₂O), and heat of formation of Cl₂O, J. Phys. Chem., 1996, 100, 14178. [all data]

Alekseev, Zyubina, et al., 1989
Alekseev, V.I.; Zyubina, T.S.; Zyubin, A.S.; Baluev, A.V., Mass-spectrometric and quantum-chemical investigation of thermochemical characteristics of chlorine oxides, J. Am. Chem. Soc., 1989, 2092. [all data]

Huber and Herzberg, 1979
Huber, K.P.; Herzberg, G., Molecular Spectra and Molecular Structure. IV. Constants of Diatomic Molecules,, Van Nostrand Reinhold Co., 1979, ,1. [all data]

Bulgin, Dyke, et al., 1979
Bulgin, D.K.; Dyke, J.M.; Jonathan, N.; Morris, A., Vacuum ultraviolet photoelectron spectroscopy of transient species, J. Chem. Soc. Faraday Trans. 2, 1979, 75, 456. [all data]

Fisher, 1967
Fisher, I.P., Mass spectrometry study of intermediates in thermal decomposition of perchloric acid and chlorine dioxide, J. Chem. Soc. Faraday Trans., 1967, 63, 684. [all data]

Basco and Morse, 1973
Basco, N.; Morse, R.D., The vacuum ultraviolet absorption spectrum of ClO, J. Mol. Spectrosc., 1973, 45, 35. [all data]

Pannetier and Gaydon, 1948
Pannetier, G.; Gaydon, A.G., Band spectrum of ClO in flames, Nature (London), 1948, 161, 242. [all data]

Porter, 1950
Porter, G., The absorption spectroscopy of substances of short life, Discuss. Faraday Soc., 1950, 9, 60, https://doi.org/10.1039/df9500900060 . [all data]

Andrews and Raymond, 1971
Andrews, L.; Raymond, J.I., Argon matrix infrared spectrum of the ClO radical, J. Chem. Phys., 1971, 55, 3087. [all data]

Chi and Andrews, 1973
Chi, F.K.; Andrews, L., Argon matrix Raman spectra of dichlorine monoxide and its photolysis products monochlorine monoxide and chlorine-monochlorine monoxide. Infrared matrix spectra of monochlorine monoxide and dimeric monochlorine monoxide, J. Phys. Chem., 1973, 77, 26, 3062, https://doi.org/10.1021/j100644a007 . [all data]

Amano, Hirota, et al., 1968
Amano, T.; Hirota, E.; Morino, Y., Microwave spectrum of the ClO radical, J. Mol. Spectrosc., 1968, 27, 257. [all data]

Amano, Saito, et al., 1969
Amano, T.; Saito, S.; Hirota, E.; Morino, Y., Microwave spectrum of the ClO radical, J. Mol. Spectrosc., 1969, 30, 275. [all data]

Carrington, Dyer, et al., 1967
Carrington, A.; Dyer, P.N.; Levy, D.H., Gas-phase electron resonance spectrum of ClO, J. Chem. Phys., 1967, 47, 1756. [all data]

Carrington, Levy, et al., 1967
Carrington, A.; Levy, D.H.; Miller, T.A., Stark effect in gas-phase electron resonance. The dipole moments of ClO, BrO, SH, and ¹ΔSO, J. Chem. Phys., 1967, 47, 3801. [all data]

Uehara and Morino, 1970
Uehara, H.; Morino, Y., Gas-phase EPR spectra of rotationally excited states of SH and ClO free radicals, J. Mol. Spectrosc., 1970, 36, 158. [all data]

Uehara, Tanimoto, et al., 1971
Uehara, H.; Tanimoto, M.; Morino, Y., Hyperfine interactions in the gas-phase E.P.R. spectra of ³⁵ClO (²Π_3/2) in the J=5/2 and J=3/2 levels, Mol. Phys., 1971, 22, 799. [all data]

Coxon and Ramsay, 1976
Coxon, J.A.; Ramsay, D.A., The A²Π_i-X²Π_i band system of ClO: reinvestigation of the absorption spectrum, Can. J. Phys., 1976, 54, 1034. [all data]

Coxon, Jones, et al., 1976
Coxon, J.A.; Jones, W.E.; Skolnik, E.G., Rotational analysis of emission bands of the A²Π_i-X²Π_i system of ³⁵ClO, Can. J. Phys., 1976, 54, 1043. [all data]

Briggs, 1972
Briggs, A.G., Vibrational reassignments in the A²Π-X²Π system of ClO, Nature (London), 1972, 239, 13. [all data]

O'Hare and Wahl, 1971
O'Hare, P.A.G.; Wahl, A.C., Dissociation energy, ionization potential, electron affinity, dipole and quadrupole moments of chlorine monoxide (ClO,²Π) from ab initio molecular orbital calculations, J. Chem. Phys., 1971, 54, 3770. [all data]

Notes

Go To: Top, Gas phase ion energetics data, Constants of diatomic molecules, References

Symbols used in this document:

EA Electron affinity

IE (evaluated) Recommended ionization energy
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.

EA	Electron affinity
IE (evaluated)	Recommended ionization energy