Iodine monochloride

Formula: ClI
Molecular weight: 162.357
IUPAC Standard InChI: InChI=1S/ClI/c1-2
IUPAC Standard InChIKey: QZRGKCOWNLSUDK-UHFFFAOYSA-N
CAS Registry Number: 7790-99-0
Chemical structure:
This structure is also available as a 2d Mol file
Species with the same structure:
- iodine trichloride
Information on this page:
Other data available:
- Condensed phase thermochemistry data
- Henry's Law data
Data at other public NIST sites:
- Microwave spectra (on physics lab web site)
- Gas Phase Kinetics Database
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Gas phase thermochemistry data

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Quantity	Value	Units	Method	Reference	Comment
Δ_fH°_gas	17.51	kJ/mol	Review	Chase, 1998	Data last reviewed in September, 1965
Quantity	Value	Units	Method	Reference	Comment
S°_{gas,1 bar}	247.56	J/mol*K	Review	Chase, 1998	Data last reviewed in September, 1965

Gas Phase Heat Capacity (Shomate Equation)

C_p° = A + B*t + C*t² + D*t³ + E/t²
H° − H°_298.15= A*t + B*t²/2 + C*t³/3 + D*t⁴/4 − E/t + F − H
S° = A*ln(t) + B*t + C*t²/2 + D*t³/3 − E/(2*t²) + G
C_p = heat capacity (J/mol*K)
H° = standard enthalpy (kJ/mol)
S° = standard entropy (J/mol*K)
t = temperature (K) / 1000.

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View table.

Temperature (K)	1000. to 6000.
A	37.27622
B	0.564079
C	-0.032190
D	0.002749
E	-0.170462
F	5.795551
G	291.5466
H	17.50602
Reference	Chase, 1998
Comment	Data last reviewed in September, 1965

Reaction thermochemistry data

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Data compiled as indicated in comments:
B - John E. Bartmess
ALS - Hussein Y. Afeefy, Joel F. Liebman, and Stephen E. Stein

Note: Please consider using the reaction search for this species. This page allows searching of all reactions involving this species. A general reaction search form is also available. Future versions of this site may rely on reaction search pages in place of the enumerated reaction displays seen below.

Individual Reactions

+ Iodine monochloride = ( • )

By formula: F^- + ClI = (F^- • ClI)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	395.0	kJ/mol	Ther	Finch, Gates, et al., 1977	gas phase; This value is far more strongly bound than expected from other X3- data; B
Δ_rH°	181.2	kJ/mol	N/A	Check, Faust, et al., 2001	gas phase; FeH2-(q); ; ΔS(EA)=8.2; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	138.1	kJ/mol	N/A	Check, Faust, et al., 2001	gas phase; FeH2-(q); ; ΔS(EA)=8.2; B

+ = + Iodine monochloride

By formula: I₂ + CClF₃ = CF₃I + ClI

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	72.3 ± 1.1	kJ/mol	Eqk	Lord, Goy, et al., 1967	gas phase; Reanalyzed by Cox and Pilcher, 1970, Original value = 71.55 ± 0.71 kJ/mol; ALS

Gas phase ion energetics data

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

Data compiled as indicated in comments:
LBLHLM - Sharon G. Lias, John E. Bartmess, Joel F. Liebman, John L. Holmes, Rhoda D. Levin, and W. Gary Mallard
LLK - Sharon G. Lias, Rhoda D. Levin, and Sherif A. Kafafi
B - John E. Bartmess

Quantity	Value	Units	Method	Reference	Comment
IE (evaluated)	10.08 ± 0.01	eV	N/A	N/A	L

Electron affinity determinations

EA (eV)	Method	Reference	Comment
1.78487	R-A	Refaey and Franklin, 1977	I^- + NOCl ->.; B
2.41 ± 0.10	NBIE	Auerbach, Hubers, et al., 1973	B
1.480 ± 0.050	NBIE	Hubers, Kleyn, et al., 1976	Stated electron affinity is the Vertical Detachment Energy; B
3.04178	N/A	Check, Faust, et al., 2001	FeH-; ; ΔS(EA)=5.3; B

Ionization energy determinations

IE (eV)	Method	Reference	Comment
10.08	EVAL	Huber and Herzberg, 1979	LLK
10.09 ± 0.01	S	Venkateswarlu, 1975	LLK
9.95	PE	Potts and Price, 1971	LLK
10.07 ± 0.01	PI	Dibeler, Walker, et al., 1971	LLK
10.10	PE	Dyke, Josland, et al., 1984	Vertical value; LBLHLM
10.10 ± 0.02	PE	Potts and Price, 1971	Vertical value; LLK

Ion clustering data

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Data compiled by: John E. Bartmess

Note: Please consider using the reaction search for this species. This page allows searching of all reactions involving this species. Searches may be limited to ion clustering reactions. A general reaction search form is also available.

Clustering reactions

+ Iodine monochloride = ( • )

By formula: F^- + ClI = (F^- • ClI)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	395.0	kJ/mol	Ther	Finch, Gates, et al., 1977	gas phase; This value is far more strongly bound than expected from other X3- data
Δ_rH°	181.2	kJ/mol	N/A	Check, Faust, et al., 2001	gas phase; FeH2-(q); ; ΔS(EA)=8.2
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	138.1	kJ/mol	N/A	Check, Faust, et al., 2001	gas phase; FeH2-(q); ; ΔS(EA)=8.2

Constants of diatomic molecules

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

Data collected through January, 1977

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 ¹²⁷I³⁵Cl
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
Fragments of many Rydberg series in the absorption spectrum above 60000 cm^-1 have been observed and tabulated by Venkateswarlu, 1975; see also Donovan and Robertson, 1972. The intensities in these series are most irregular, possibly because of perturbations by valence states in this region. The Rydberg series are believed to converge to two limits at 81362 and 85996 cm^-1 corresponding to the ²Π_3/2 and ²Π_1/2, v=0 components of the ground state of ICl⁺.
↳missing citation
L	71006	[420] H 1									L ← X V	71024
L	↳missing citation; missing citation
G	66484	[421] H 2									G ← X V	66503 H
G	↳missing citation; missing citation
Extensive system of absorption bands in the region 60250 - 63300 cm^-1, not yet analyzed.
↳Venkateswarlu, 1975
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	58167	[445] H 3									F ↔ X V	58198 H
F	↳Cordes and Sponer, 1932; Haranath and Rao, 1957; missing citation; missing citation
E	53477	[434] H 4									E ↔ X V	53502 H
E	↳Cordes and Sponer, 1932; Haranath and Rao, 1957; missing citation; missing citation
Continuous absorption with maximum at 41600 cm^-1.
↳Seery and Britton, 1964
D	37585	173.2 H	1.1 5								D → A 6 R	23824 H
	↳missing citation
	7
	↳Asundi and Venkateswarlu, 1947
	8
	↳Seery and Britton, 1964
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
B' 0⁺	(18157)	[32] 9									B' ← X R	17981 H
B' 0⁺	↳Brown and Gibson, 1932
B ³Π₀₊	17363.₁	221.1 10 Z	9.62		0.0872 10 11	0.0017		(10E-8)		2.66	B ← X 12 R	17279.₅ 10 Z
B ³Π₀₊	↳Brown and Gibson, 1932; Hulthen, Jarlsater, et al., 1961
A ³Π₁	13742	212.3 13 H	2.39 14	-0.012	0.084832 15			(5.4E-8)		2.6923	A ↔ X 16 17 R	13656 13 H
A ³Π₁	↳missing citation; Hulthen, Johansson, et al., 1958; Hulthen, Jarlsater, et al., 1961; missing citation
X ¹Σ⁺	0	384.29₃ Z	1.501		0.1141587 18	0.0005354		(4.03E-8)		2.32087₈ 19
	↳Brooks and Crawford, 1955
	Raman sp. 20
	↳Holzer, Murphy, et al., 1970
	Microwave sp. 21
	↳Townes, Merritt, et al., 1948; Herbst and Steinmetz, 1972

Notes

Strong progression, F ← X of Donovan and Husain, 1968, n₅ of Venkateswarlu, 1975.

Strong progression, E ← X of Donovan and Husain, 1968, g₅ of Venkateswarlu, 1975.

Extensive band system, formerly D - X, b₆ of Venkateswarlu, 1975.

Extensive band system, formerly C - X, a₆ of Venkateswarlu, 1975.

Extensive band system.

Constants of Haranath and Rao, 1957, for the lower state (ω"_e= 209.7, ω"_ex"_e = 1.9), are not in agreement with the work of Clyne and Coxon, 1967 and Cummings and Klemperer, 1974 concerning the A ³Π₁ state; see Clyne and Coxon, 1967. This system was also observed in fluorescence following two-step laser excitation D←A←X Barnes, Moeller, et al., 1974. (Note that ν_e given by Haranath and Rao, 1957 does not match their observed ν₀₀.)

Diffuse emission bands between 18700 and 21700 cm^-1.

Continuous absorption with maximum at 21000 cm^-1. 24

Potential well arising from the avoided crossing of the "original" B ³Π₀₊ curve going to I (²P_3/2) + Cl (²P_1/2) and the repulsive 0⁺ curve coming from unexcited atoms; see also Child and Bernstein, 1973. 25

Extrapolated from data with v'= 1,2,3.

v'=4 is strongly predissociated and gives rise to broad, diffuse absorption bands; no higher levels are observed. At high resolution Olson and Innes, 1976 even v'=3 shows appreciable broadening of the individual lines which rapidly increases above J'=37 and is presumably caused by predissociation into the 0⁺ state arising from ²P_3/2 + ²P_3/2; see B' 0⁺. The non-radiative lifetime varies from ~0.2 ns at low J to 0.02 ns at J=42 Olson and Innes, 1976.

The f value is estimated to be (f= 0.0026) Olson and Innes, 1976 corresponding to a radiative lifetime of τ= 1 μs Olson and Innes, 1976.

Vibrational constants from Clyne and Coxon, 1967, whose measurements of the I + Cl chemiluminescence spectrum include bands with v'= 1...18. Cummings and Klemperer, 1974, extrapolating from the data (zero lines) of Hulthen, Jarlsater, et al., 1961 for 3 ≤ v' ≤ 19, ν₀₀ = 13655.23 Cummings and Klemperer, 1974. Earlier, from band origins with 7≤v'≤19, Hulthen, Jarlsater, et al., 1961, derived ω_e = 209.111 Hulthen, Jarlsater, et al., 1961, ω_ex_e = 1.886 Hulthen, Jarlsater, et al., 1961, ω_ey_e = -0.03558 Hulthen, Jarlsater, et al., 1961, ν₀₀ = 13660.29 Hulthen, Jarlsater, et al., 1961. See 14.

Clyne and Coxon, 1967. T_v values for 38 levels (v≥3) are listed in Hulthen, Jarlsater, et al., 1961. There is a strong vibrational perturbation above v=34, but the last few levels are again regular and converge to 17366.0 cm^-1.

B_e = B₀ = 0.084583, 3≤v≤19 Cummings and Klemperer, 1974, B₁ = 0.083995, 3≤v≤19 Cummings and Klemperer, 1974, B₂ = 0.083308, 3≤v≤19 Cummings and Klemperer, 1974, have been extrapo1ated by Cummings and Klemperer, 1974, from the B_v values of Hulthen, Jarlsater, et al., 1961 for 3≤v≤19. B_v values up to v=40 are tabulated in Hulthen, Jarlsater, et al., 1961. The Λ-type doubling constant q [~B(R,P)-B(Q)] increases from +1.32E-5 for v=10 to +11.0E-5 for v=27, but the doubling becomes irregular at higher v values Hulthen, Jarlsater, et al., 1961. The dipole moment in A ³Π₁ varies from 2.0₀ D at v=7 to 0.6 D at v=27 Cummings and Klemperer, 1974; sign opposite to that in X ¹Σ⁺. RKR potential curve Coxon, 1973.

Fluorescence lifetimes of 110 and 76 μs have been measured. Holleman and Steinfeld, 1971 following laser excitation at 6068 and 5922 Å, respectively.

Magnetic rotation spectrum Eberhardt, Cheng, et al., 1959; its intensity drops sharply above v'=28. See also Stalder and Eberhardt, 1967. Laser induced fluorescence series in argon matrix Wight, Ault, et al., 1975.

From the microwave spectrum Herbst and Steinmetz, 1972; in excellent agreement with the much earlier values from the electronic spectrum Curtis and Patkowski, 1934.

Infrared sp. 21

Resonance Raman spectrum in argon matrix Wight, Ault, et al., 1975.

μ_el(v=0) 1.24 D Herbst and Steinmetz, 1972; dipole derivative 2.1 D/Å Brooks and Crawford, 1955. Electric quadrupole coupling constants for I and Cl in Herbst and Steinmetz, 1972, also iodine spin-rotation constant.

From the convergence limit of A ³Π₁, see 14.

Average value obtained by photoelectron spectroscopy Potts and Price, 1971, Cornford, 1971 and photoion mass- spectrometry Dibeler, Walker, et al., 1971.

At least partly due to B←X; see the discussion in Coxon, 1973.

There are fragments of fairly sharp branches at places corresponding to extrapolated levels of B ³Π₀₊.

References

Go To: Top, Gas phase thermochemistry data, Reaction thermochemistry data, Gas phase ion energetics data, Ion clustering data, Constants of diatomic molecules, Notes

Chase, 1998
Chase, M.W., Jr., NIST-JANAF Themochemical Tables, Fourth Edition, J. Phys. Chem. Ref. Data, Monograph 9, 1998, 1-1951. [all data]

Finch, Gates, et al., 1977
Finch, A.; Gates, P.N.; Peake, S.J., Thermochemistry of polyhalides. III. Cesium and rubidium tetrachloroiodates, J. Inorg. Nucl. Chem., 1977, 39, 2135. [all data]

Check, Faust, et al., 2001
Check, C.E.; Faust, T.O.; Bailey, J.M.; Wright, B.J.; Gilbert, T.M.; Sunderlin, L.S., Addition of Polarization and Diffuse Functions to the LANL2DZ Basis Set for P-Block Elements, J. Phys. Chem. A,, 2001, 105, 34, 8111, https://doi.org/10.1021/jp011945l . [all data]

Lord, Goy, et al., 1967
Lord, A.; Goy, C.A.; Pritchard, H.O., The heats of formation of trifluoromethyl chloride and bromide, J. Phys. Chem., 1967, 71, 2705-2707. [all data]

Cox and Pilcher, 1970
Cox, J.D.; Pilcher, G., Thermochemistry of Organic and Organometallic Compounds, Academic Press, New York, 1970, 1-636. [all data]

Refaey and Franklin, 1977
Refaey, K.M.A.; Franklin, J.L., Endoergic ion-molecule collision processes of negative ions. VI. Collisions of I- on (CN)₂ and NOCl, Int. J. Mass Spectrom. Ion Phys., 1977, 23, 13. [all data]

Auerbach, Hubers, et al., 1973
Auerbach, D.J.; Hubers, M.M.; Baeda, A.P.M.; Los, J., Chemi-ionization in alkali-heteronuclear halogen collisions: Role of excited molecular ion states, Chem. Phys., 1973, 2, 107. [all data]

Hubers, Kleyn, et al., 1976
Hubers, M.M.; Kleyn, A.W.; Los, J., Ion pair formation in alkali-halogen collisions at high velocities, Chem. Phys., 1976, 17, 303. [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]

Venkateswarlu, 1975
Venkateswarlu, P., The vacuum ultraviolet spectrum of ICl, Can. J. Phys., 1975, 53, 812. [all data]

Potts and Price, 1971
Potts, A.W.; Price, W.C., Photoelectron spectra of the halogens and mixed halides ICI and lBr, J. Chem. Soc. Faraday Trans., 1971, 67, 1242. [all data]

Dibeler, Walker, et al., 1971
Dibeler, V.H.; Walker, J.A.; McCulloh, K.E.; Rosenstock, H.M., Effect of hot bands on the ionization threshold of some diatomic halogen molecules, Intern. J. Mass Spectrom. Ion Phys., 1971, 7, 209. [all data]

Dyke, Josland, et al., 1984
Dyke, J.M.; Josland, G.D.; Snijders, J.G.; Boerrigter, P.M., Ionization energies of the diatomic halogens and interhalogens studied with relativistic hartree-fock-slater calculations, Chem. Phys., 1984, 91, 419. [all data]

Donovan and Robertson, 1972
Donovan, R.J.; Robertson, P.J., Vacuum ultraviolet spectrum of ICl, Spectrosc. Lett., 1972, 5, 281. [all data]

Cordes and Sponer, 1932
Cordes, H.; Sponer, H., Die molekulabsorption der gemischten halogenmolekule im vakuumultraviolett. II. Mitteilung, Z. Phys., 1932, 79, 170. [all data]

Haranath and Rao, 1957
Haranath, P.B.V.; Rao, P.T., Emission spectra of mixed halogens. Part I: ICl, Indian J. Phys., 1957, 31, 156. [all data]

Seery and Britton, 1964
Seery, D.J.; Britton, D., The continuous absorption spectra of chlorine, bromine, bromine chloride, iodine chloride, and iodine bromide, J. Phys. Chem., 1964, 68, 2263. [all data]

Asundi and Venkateswarlu, 1947
Asundi, R.K.; Venkateswarlu, P., On continous emission bands of ICl and IBr, Indian J. Phys., 1947, 21, 76-82. [all data]

Brown and Gibson, 1932
Brown, W.G.; Gibson, G.E., Predissociation in the spectrum of iodine chloride, Phys. Rev., 1932, 40, 529. [all data]

Hulthen, Jarlsater, et al., 1961
Hulthen, E.; Jarlsater, N.; Koffman, L., On the absorption spectrum of ICl. Part II. Chlorine isotopes in iodine chloride, Ark. Fys., 1961, 18, 479. [all data]

Hulthen, Johansson, et al., 1958
Hulthen, E.; Johansson, N.; Pilsater, U., On the absorption spectrum of ICl. Part I, Ark. Fys., 1958, 14, 31. [all data]

Brooks and Crawford, 1955
Brooks, W.V.F.; Crawford, B., Jr., Vibrational intensities. V. BrCl and ICl, J. Chem. Phys., 1955, 23, 363. [all data]

Holzer, Murphy, et al., 1970
Holzer, W.; Murphy, W.F.; Bernstein, H.J., Resonance Raman effect and resonance fluoroscence in halogen gases, J. Chem. Phys., 1970, 52, 399. [all data]

Townes, Merritt, et al., 1948
Townes, C.H.; Merritt, F.R.; Wright, B.D., The pure rotational spectrum of ICl, Phys. Rev., 1948, 73, 1334. [all data]

Herbst and Steinmetz, 1972
Herbst, E.; Steinmetz, W., Dipole moment of ICl, J. Chem. Phys., 1972, 56, 5342. [all data]

Donovan and Husain, 1968
Donovan, R.J.; Husain, D., Photochemical studies of IBr, ICl and BrCl by kinetic spectroscopy in the vacuum ultra-violet, Trans. Faraday Soc., 1968, 64, 2325. [all data]

Clyne and Coxon, 1967
Clyne, M.A.A.; Coxon, J.A., The formation and detection of some low-lying excited electronic states of BrCl and other halogens, Proc. R. Soc. London A, 1967, 298, 424. [all data]

Cummings and Klemperer, 1974
Cummings, F.E.; Klemperer, W., Vibrational dependence of the dipole moment in the A³Π₁ state of ICl, J. Chem. Phys., 1974, 60, 2035. [all data]

Barnes, Moeller, et al., 1974
Barnes, R.H.; Moeller, C.E.; Kircher, J.F.; Verber, C.M., Two-step excitation of fluorescence in iodine monochloride vapor, Appl. Phys. Lett., 1974, 24, 610. [all data]

Child and Bernstein, 1973
Child, M.S.; Bernstein, R.B., Diatomic interhalogens: systematics and implications of spectroscopic interatomic potentials and curve crossings, J. Chem. Phys., 1973, 59, 5916. [all data]

Olson and Innes, 1976
Olson, C.D.; Innes, K.K., Single-rotational-level lifetimes from measurements of linewidths in the B³Π_o⁺ ← X¹Σ⁺ system of ICl, J. Chem. Phys., 1976, 64, 2405. [all data]

Coxon, 1973
Coxon, J.A., Chapt. 4. Low-lying electronic states of diatomic halogen molecules in Molecular Spectroscopy. Volume 1, Barrow,R.F.; Long,D.A.; Millen,D.J., ed(s)., The Chemical Society, Burlington House, London, W1V 0BN, 1973, 177-228. [all data]

Holleman and Steinfeld, 1971
Holleman, G.W.; Steinfeld, J.I., Time-resolved fluorescence of iodine monochloride, Chem. Phys. Lett., 1971, 12, 431. [all data]

Eberhardt, Cheng, et al., 1959
Eberhardt, W.H.; Cheng, W.-C.; Renner, H., The magnetic rotation spectrum of ICl and IBr, J. Mol. Spectrosc., 1959, 3, 664. [all data]

Stalder and Eberhardt, 1967
Stalder, A.F.; Eberhardt, W.H., Magnetically induced circular dichroism and birefringence in single lines of the electronic spectrum of ICl, J. Chem. Phys., 1967, 47, 1445. [all data]

Wight, Ault, et al., 1975
Wight, C.A.; Ault, B.S.; Andrews, L., Laser-induced fluorescence and resonance Raman spectra of interhalogen diatomics isolated in inert matrices at 12 K, J. Mol. Spectrosc., 1975, 56, 239. [all data]

Curtis and Patkowski, 1934
Curtis, W.E.; Patkowski, J., XI. Rotational analysis of the absorption bands of ICl, Philos. Trans. R. Soc. London A, 1934, 232, 395. [all data]

Cornford, 1971
Cornford, Thesis, University of British Columbia, 1971, 0. [all data]

Notes

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Symbols used in this document:

EA	Electron affinity
IE (evaluated)	Recommended ionization energy
S°_{gas,1 bar}	Entropy of gas at standard conditions (1 bar)
Δ_fH°_gas	Enthalpy of formation of gas at standard conditions
Δ_rG°	Free energy of reaction at standard conditions
Δ_rH°	Enthalpy of reaction at standard conditions

Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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