Carbon monoxide

Formula: CO
Molecular weight: 28.0101
IUPAC Standard InChI: InChI=1S/CO/c1-2
IUPAC Standard InChIKey: UGFAIRIUMAVXCW-UHFFFAOYSA-N
CAS Registry Number: 630-08-0
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.
Other names: Carbon oxide (CO); CO; Exhaust gas; Flue gas; Carbonic oxide; Carbon oxide; Carbone (oxyde de); Carbonio (ossido di); Kohlenmonoxid; Kohlenoxyd; Koolmonoxyde; NA 9202; Oxyde de carbone; UN 1016; Wegla tlenek; Carbon monooxide
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Information on this page:
Other data available:
- Gas phase thermochemistry data
- Reaction thermochemistry data: reactions 51 to 100, reactions 101 to 150, reactions 151 to 200, reactions 201 to 249
- Henry's Law data
- Ion clustering data
- IR Spectrum
- Mass spectrum (electron ionization)
- Constants of diatomic molecules
- Fluid Properties
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Phase change data

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

Data compiled as indicated in comments:
TRC - Thermodynamics Research Center, NIST Boulder Laboratories, Chris Muzny director
AC - William E. Acree, Jr., James S. Chickos

Quantity	Value	Units	Method	Reference	Comment
T_boil	81.63	K	N/A	Mullins, Kirk, et al., 1963	Uncertainty assigned by TRC = 0.05 K; TRC
T_boil	81.61	K	N/A	Clayton and Giauque, 1932	Uncertainty assigned by TRC = 0.07 K; TRC
Quantity	Value	Units	Method	Reference	Comment
T_triple	67.95	K	N/A	Gill and Morrison, 1966	Crystal phase 1 phase; Uncertainty assigned by TRC = 0.06 K; TRC
T_triple	68.12	K	N/A	Mullins, Kirk, et al., 1963	Crystal phase 1 phase; Uncertainty assigned by TRC = 0.05 K; TRC
T_triple	68.09	K	N/A	Clayton and Giauque, 1932	Crystal phase 1 phase; Uncertainty assigned by TRC = 0.07 K; TRC
Quantity	Value	Units	Method	Reference	Comment
T_c	134.45	K	N/A	Cardoso, 1915	Uncertainty assigned by TRC = 0.4 K; 4 determinations with same result; TRC
Quantity	Value	Units	Method	Reference	Comment
P_c	34.5300	atm	N/A	Cardoso, 1915	Uncertainty assigned by TRC = 0.2999 atm; TRC
P_c	34.5300	atm	N/A	Cardoso, 1915	Uncertainty assigned by TRC = 0.2999 atm; TRC
P_c	34.6900	atm	N/A	Cardoso, 1915	Uncertainty assigned by TRC = 0.2999 atm; TRC
P_c	34.7500	atm	N/A	Cardoso, 1915	Uncertainty assigned by TRC = 0.2999 atm; TRC
Quantity	Value	Units	Method	Reference	Comment
ρ_c	11.1	mol/l	N/A	Cardoso, 1915	Uncertainty assigned by TRC = 0.04 mol/l; extrapolation of rectilinear diameter to Tc; TRC

Enthalpy of vaporization

Δ_vapH (kcal/mol)	Temperature (K)	Method	Reference	Comment
1.4	93.	A	Stephenson and Malanowski, 1987	Based on data from 68. to 108. K.; AC
1.4	81.	N/A	Clayton and Giauque, 1932, 2	Based on data from 69. to 83. K.; AC
1.4	81.	C	Clayton and Giauque, 1932, 2	AC

Enthalpy of sublimation

Δ_subH (kcal/mol)	Temperature (K)	Method	Reference	Comment
1.8	58.	N/A	Stephenson and Malanowski, 1987	Based on data from 54. to 61. K.; AC
1.9	60.	A	Stull, 1947	Based on data from 51. to 68. K.; AC
1.9	62.	A	Crommelin, Bijleveld, et al., 1931	Based on data from 57. to 68. K.; AC

In addition to the Thermodynamics Research Center (TRC) data available from this site, much more physical and chemical property data is available from the following TRC products:

Reaction thermochemistry data

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

Data compiled as indicated in comments:
MS - José A. Martinho Simões
M - Michael M. Meot-Ner (Mautner) and Sharon G. Lias
RCD - Robert C. Dunbar
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.

Reactions 1 to 50

(solution) + (solution) = C₁₄H₂₁MnO₂ (solution) + Carbon monoxide (solution)

By formula: C₈H₅MnO₃ (solution) + C₇H₁₆ (solution) = C₁₄H₂₁MnO₂ (solution) + CO (solution)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	47. ± 2.	kcal/mol	AVG	N/A	Average of 18 values; Individual data points

(solution) + (solution) = C₁₂H₁₆CrO₅ (solution) + Carbon monoxide (solution)

By formula: C₆CrO₆ (solution) + C₇H₁₆ (solution) = C₁₂H₁₆CrO₅ (solution) + CO (solution)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	27.1 ± 0.8	kcal/mol	AVG	N/A	Average of 13 values; Individual data points

(solution) = C₅CrO₅ (solution) + Carbon monoxide (solution)

By formula: C₆CrO₆ (solution) = C₅CrO₅ (solution) + CO (solution)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	40.20 ± 0.60	kcal/mol	KinS	Graham and Angelici, 1967	solvent: Decalin; The reaction enthalpy and entropy were identified with the enthalpy and entropy of activation for the reaction of Cr(CO)6(solution) with PBu3(solution).; MS
Δ_rH°	38.10	kcal/mol	KinS	Werner and Prinz, 1966	solvent: n-Decane+cyclohexane mixture; The reaction enthalpy and entropy were identified with the enthalpy and entropy of activation for the reactions of Cr(CO)6(solution) with a phosphine and an amine. The results were quoted from Graham and Angelici, 1967.; MS

(solution) = C₅MoO₅ (solution) + Carbon monoxide (solution)

By formula: C₆MoO₆ (solution) = C₅MoO₅ (solution) + CO (solution)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	31.7 ± 1.4	kcal/mol	KinS	Graham and Angelici, 1967	solvent: Decalin; The reaction enthalpy and entropy were identified with the enthalpy and entropy of activation for the reaction of Mo(CO)6(solution) with PBu3(solution).; MS
Δ_rH°	30.21	kcal/mol	KinS	Werner and Prinz, 1966	solvent: n-Decane+cyclohexane mixture; The reaction enthalpy and entropy were identified with the enthalpy and entropy of activation for the reactions of Mo(CO)6(solution) with a phosphine and an amine. The results were quoted from Graham and Angelici, 1967.; MS

(solution) = C₅O₅W (solution) + Carbon monoxide (solution)

By formula: C₆O₆W (solution) = C₅O₅W (solution) + CO (solution)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	39.9 ± 1.6	kcal/mol	KinS	Graham and Angelici, 1967	solvent: Decalin; The reaction enthalpy and entropy were identified with the enthalpy and entropy of activation for the reaction of W(CO)6(solution) with PBu3(solution).; MS
Δ_rH°	39.01	kcal/mol	KinS	Werner and Prinz, 1966	solvent: n-Decane+cyclohexane mixture; The reaction enthalpy and entropy were identified with the enthalpy and entropy of activation for the reactions of W(CO)6(solution) with a phosphine and an amine. The results were quoted from Graham and Angelici, 1967.; MS

C₁₁H₂O₁₁Os (solution) + Carbon monoxide (solution) = (g) + (solution)

By formula: C₁₁H₂O₁₁Os (solution) + CO (solution) = H₂ (g) + C₁₂O₁₂Os₃ (solution)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-9.0 ± 2.3	kcal/mol	ES/KS	Poë, Sampson, et al., 1993	solvent: Decalin; Calculated from equilibrium and kinetic data Poë, Sampson, et al., 1993.; MS
Δ_rH°	-18.5 ± 2.3	kcal/mol	N/A	Poë, Sampson, et al., 1993	solvent: Decalin; Calculated from data for the reactions Os3(CO)10(H)2(solution) + CO(solution) = Os3(CO)11(H)2(solution) (hrxn [kJ/mol]=-39.7±1.3, srxn [J/(mol K)]=-80.3±3.8) and Os3(CO)11(H)2(solution) + CO(solution) = Os3(CO)12(solution) + H2(g) (hrxn [kJ/mol]=-37.7±9.6, srxn [J/(mol K)]=-32.6±27.6) Poë, Sampson, et al., 1993.; MS

(g) = C₄FeO₄ (g) + Carbon monoxide (g)

By formula: C₅FeO₅ (g) = C₄FeO₄ (g) + CO (g)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	41.5 ± 3.0	kcal/mol	LPHP	Lewis, Golden, et al., 1984	Please also see Smith and Laine, 1981. Temperature range: 670-780 K. The reaction enthalpy at 298 K relies on an activation energy of 40.01 kcal/mol and assumes a negligible activation barrier for product recombination. The enthalpy of formation relies on -173.0 ± 1.6 kcal/mol for the enthalpy of formation of Fe(CO)5(g). At least two other estimates of the activation energy for the Fe(CO)4(g) + CO(g) recombination have been reported: 1.7 kcal/mol Miller and Grant, 1985 and 3.99 kcal/mol Walsh, 1986. In Lewis, Golden, et al., 1984 authors have considered that the Fe(CO)4(g) fragment is in its singlet excited state. However, it has also been suggested that the fragment is formed in its triplet ground state Ray, Brandow, et al., 1988 Sunderlin, Wang, et al., 1992; MS
Δ_rH°	55. ± 11.	kcal/mol	N/A	Engelking and Lineberger, 1979	Please also see Compton and Stockdale, 1976. Method: LPS and collision with low energy electrons.; MS

(g) = C₅MoO₅ (g) + Carbon monoxide (g)

By formula: C₆MoO₆ (g) = C₅MoO₅ (g) + CO (g)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	34.9 ± 5.0	kcal/mol	KinG	Ganske and Rosenfeld, 1990	MS
Δ_rH°	40.5 ± 3.0	kcal/mol	LPHP	Lewis, Golden, et al., 1984	The reaction enthalpy at 298 K relies on an activation energy of 39.01 kcal/mol and assumes a negligible activation barrier for product recombination. The enthalpy of formation relies on -218.8 ± 0.50 kcal/mol for the enthalpy of formation of Mo(CO)6(g); MS
Δ_rH°	30.21	kcal/mol	KinG	Cetini and Gambino, 1963	Please also see Graham and Angelici, 1967. The reaction enthalpy and entropy were identified with the enthalpy and entropy of activation for the reaction of Mo(CO)6(g) with CO(g) Cetini and Gambino, 1963. The results were quoted from Graham and Angelici, 1967.; MS

(g) = C₅O₅W (g) + Carbon monoxide (g)

By formula: C₆O₆W (g) = C₅O₅W (g) + CO (g)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	46.0 ± 3.0	kcal/mol	LPHP	Lewis, Golden, et al., 1984	The reaction enthalpy at 298 K relies on an activation energy of 44.50 kcal/mol and assumes a negligible activation barrier for product recombination. The enthalpy of formation relies on -211.3 ± 0.65 kcal/mol for the enthalpy of formation of W(CO)6(g); MS
Δ_rH°	39.79	kcal/mol	KinG	Cetini and Gambino, 1963, 2	Please also see Graham and Angelici, 1967. The reaction enthalpy and entropy were identified with the enthalpy and entropy of activation for the reaction of W(CO)6(g) with CO(g) Cetini and Gambino, 1963, 2. The results were quoted from Graham and Angelici, 1967.; MS

(g) = C₅CrO₅ (g) + Carbon monoxide (g)

By formula: C₆CrO₆ (g) = C₅CrO₅ (g) + CO (g)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	37.0 ± 5.0	kcal/mol	KinG	Fletcher and Rosenfeld, 1988	MS
Δ_rH°	36.8 ± 3.0	kcal/mol	LPHP	Lewis, Golden, et al., 1984	Temperature range: 740-820 K. The reaction enthalpy at 298 K relies on an activation energy of 35.30 kcal/mol and assumes a negligible activation barrier for product recombination.; MS
Δ_rH°	38.70	kcal/mol	KinG	Pajaro, Calderazzo, et al., 1960	Please also see Graham and Angelici, 1967. The reaction enthalpy and entropy were identified with the enthalpy and entropy of activation for the reaction of Cr(CO)6(g) with CO(g) Pajaro, Calderazzo, et al., 1960. The results were quoted from Graham and Angelici, 1967.; MS

C₁₀H₅CrNO₅ (solution) + Carbon monoxide (solution) = (solution) + (solution)

By formula: C₁₀H₅CrNO₅ (solution) + CO (solution) = C₆CrO₆ (solution) + C₄H₄N₂ (solution)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-14.8	kcal/mol	KinS	Wovkulich and Atwood, 1980	solvent: Hexane; The data rely on the enthalpy and entropy of activation for the forward reaction, 25.4 ± 1.1 kcal/mol and 13.0±14.6 J/(mol K) Dennenberg and Darensbourg, 1972, and also on the enthalpy and entropy of activation for the Cr-CO dissociation in Cr(CO)6, 40.20 ± 0.60 kcal/mol and 94.6±6.3 J/(mol K) Graham and Angelici, 1967. The latter data were obtained in decalin; MS

CO⁺ + Carbon monoxide = (CO⁺ • )

By formula: CO⁺ + CO = (CO⁺ • CO)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	16.	kcal/mol	PIPECO	Norwood, Guo, et al., 1988	gas phase; CO+ in state B, Δ_rH>; M
Δ_rH°	22.4	kcal/mol	PI	Linn, Ono, et al., 1981	gas phase; M
Δ_rH°	28. ± 7.	kcal/mol	EI	Munson and Franlin, 1962	gas phase; from IP'switching reaction and heats of formation; M
Δ_rH°	25.4	kcal/mol	PHPMS	Meot-Ner (Mautner) and Field, 1974	gas phase; Δ_rH>, DG>; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	20.	cal/mol*K	PHPMS	Meot-Ner (Mautner) and Field, 1974	gas phase; Δ_rH>, DG>; M

Free energy of reaction

Δ_rG° (kcal/mol)	T (K)	Method	Reference	Comment
4.9	340.	HPMS	Chong and Franklin, 1971	gas phase; equilibrium uncertain; M
11.5	695.	PHPMS	Meot-Ner (Mautner) and Field, 1974	gas phase; Δ_rH>, DG>; M

(cr) = 6 Carbon monoxide (g) + (cr)

By formula: C₆O₆W (cr) = 6CO (g) + W (cr)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	71.4 ± 1.1	kcal/mol	TD-HFC, HAL-HFC	Al-Takhin, Connor, et al., 1984	The reaction enthalpy corresponds to the TD experiments and leads to -229.9 ± 1.1 kcal/mol for the enthalpy of formation. The value -960±3 was recommended by the authors Al-Takhin, Connor, et al., 1984. Other values for the enthalpy of sublimation have been reported: 17.5 ± 0.2 kcal/mol Adedeji, Brown, et al., 1975, 17.7 ± 1.0 kcal/mol Hieber and Romberg, 1935, 16.7 ± 1.0 kcal/mol Rezukhina and Shvyrev, 1952, and 18.9 ± 0.26 kcal/mol Daamen, Ernsting, et al., 1979 Boxhoorn, Ernsting, et al., 1980. See also Pilcher, Ware, et al., 1975; MS
Δ_rH°	70.77 ± 0.43	kcal/mol	TD-HZC	Barnes, Pilcher, et al., 1974	Please also see Pedley and Rylance, 1977 and Tel'noi and Rabinovich, 1977.; MS

(solution) + 3 Carbon monoxide (solution) = 3C₅O₅Ru (solution)

By formula: C₁₂O₁₂Ru₃ (solution) + 3CO (solution) = 3C₅O₅Ru (solution)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-3.11 ± 0.26	kcal/mol	EqS	Koelliker and Bor, 1991	solvent: Isooctane; Temperature range: 373-448 K; MS
Δ_rH°	-6.48 ± 0.45	kcal/mol	EqS	Bor, 1986	solvent: n-Hexane; Temperature range: ca. 348-448 K; MS

(solution) = C₇Co₂O₇ (solution) + Carbon monoxide (solution)

By formula: C₈Co₂O₈ (solution) = C₇Co₂O₇ (solution) + CO (solution)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	22.2	kcal/mol	KinS	Ungváry and Markó, 1974	solvent: Heptane; Temperature range: 298-328 K; MS
Δ_rH°	21.0	kcal/mol	KinS	Ungváry, 1972	solvent: Heptane; Temperature range: 307-337 K; MS

(cr) + (l) = C₁₀H₅NO₅W (cr) + Carbon monoxide (g)

By formula: C₆O₆W (cr) + C₄H₄N₂ (l) = C₁₀H₅NO₅W (cr) + CO (g)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	8.27	kcal/mol	N/A	Nakashima and Adamson, 1982	The reaction enthalpy was calculated from the enthalpy of the reaction W(CO)6(solution) + py(solution) = W(CO)5(py)(solution) + CO(solution) in cyclohexane, 6.55 ± 0.69 kcal/mol, together with the enthalpies of solution of W(CO)6(cr), W(CO)5(py)(cr), and py(l), 35.7, 36.4, and 1.9 kcal/mol, respectively Nakashima and Adamson, 1982.; MS

+ Carbon monoxide = ( • )

By formula: CHO⁺ + CO = (CHO⁺ • CO)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	10.8	kcal/mol	PHPMS	Jennings, Headley, et al., 1982	gas phase; M
Δ_rH°	12.8	kcal/mol	PHPMS	Hiraoka, Saluja, et al., 1979	gas phase; M
Δ_rH°	11.7	kcal/mol	PHPMS	Meot-Ner (Mautner) and Field, 1974	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	22.5	cal/mol*K	PHPMS	Jennings, Headley, et al., 1982	gas phase; M
Δ_rS°	24.	cal/mol*K	PHPMS	Hiraoka, Saluja, et al., 1979	gas phase; M
Δ_rS°	20.9	cal/mol*K	PHPMS	Meot-Ner (Mautner) and Field, 1974	gas phase; M

+ Carbon monoxide = ( • )

By formula: Co⁺ + CO = (Co⁺ • CO)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	41.6 ± 1.7	kcal/mol	CIDT	Rodgers and Armentrout, 2000	RCD
Δ_rH°	39. ± 3.	kcal/mol	MKER	Carpenter, van Koppen, et al., 1995	gas phase; M

Enthalpy of reaction

Δ_rH° (kcal/mol)	T (K)	Method	Reference	Comment
41.5 (+1.6,-0.)		CID	Goebel, Haynes, et al., 1995	gas phase; guided ion beam CID; M
39.0 (+4.8,-0.)		CID	Armentrout and Kickel, 1994	gas phase; guided ion beam CID; M

(solution) + (solution) = C₁₂H₁₆MoO₅ (solution) + Carbon monoxide (solution)

By formula: C₆MoO₆ (solution) + C₇H₁₆ (solution) = C₁₂H₁₆MoO₅ (solution) + CO (solution)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	32.3 ± 2.9	kcal/mol	PAC	Johnson, Popov, et al., 1991	solvent: Heptane; The reaction enthalpy relies on 0.67 for the quantum yield of CO dissociation.; MS
Δ_rH°	31.8 ± 1.3	kcal/mol	PAC	Morse, Parker, et al., 1989	solvent: Heptane; The reaction enthalpy relies on 0.67 for the quantum yield of CO dissociation; MS

C₂FeO₂ (g) = Carbon monoxide (g) + CFeO (g)

By formula: C₂FeO₂ (g) = CO (g) + CFeO (g)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	36.7 ± 3.5	kcal/mol	FA-SIFT	Sunderlin, Wang, et al., 1992	MS
Δ_rH°	>27.0	kcal/mol	N/A	Venkataraman, Bandukwalla, et al., 1989	Method: Velocity distributions of photofragments from Fe(CO)5.; MS
Δ_rH°	23.9 ± 6.9	kcal/mol	N/A	Engelking and Lineberger, 1979	Please also see Compton and Stockdale, 1976. Method: LPS and collision with low energy electrons.; MS

(g) = 4 Carbon monoxide (g) + (cr)

By formula: C₄NiO₄ (g) = 4CO (g) + Ni (cr)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	38.34 ± 0.60	kcal/mol	EqG	Monteil, Raffin, et al., 1988	The reaction enthalpy is the average of several 2nd and 3rd law results Monteil, Raffin, et al., 1988; MS

+ Carbon monoxide = ( • )

By formula: Ni⁺ + CO = (Ni⁺ • CO)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	39. ± 3.	kcal/mol	MKER	Carpenter, van Koppen, et al., 1995	gas phase; determined from MKER and theory; M

Enthalpy of reaction

Δ_rH° (kcal/mol)	T (K)	Method	Reference	Comment
41.7 (+2.5,-0.)		CID	Khan, Steele, et al., 1995	gas phase; guided ion beam CID; M
42.5 (+2.2,-0.)		CID	Armentrout and Kickel, 1994	gas phase; guided ion beam CID; M

C₃FeO₃ (g) = Carbon monoxide (g) + C₂FeO₂ (g)

By formula: C₃FeO₃ (g) = CO (g) + C₂FeO₂ (g)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	29.0 ± 5.8	kcal/mol	FA-SIFT	Sunderlin, Wang, et al., 1992	MS
Δ_rH°	25.1	kcal/mol	N/A	Venkataraman, Bandukwalla, et al., 1989	Method: Velocity distributions of photofragments from Fe(CO)5.; MS
Δ_rH°	32.7 ± 6.9	kcal/mol	N/A	Engelking and Lineberger, 1979	Please also see Compton and Stockdale, 1976. Method: LPS and collision with low energy electrons.; MS

CFeO (g) = Carbon monoxide (g) + (g)

By formula: CFeO (g) = CO (g) + Fe (g)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	8.4 ± 3.5	kcal/mol	FA-SIFT	Sunderlin, Wang, et al., 1992	MS
Δ_rH°	<39.0	kcal/mol	N/A	Venkataraman, Bandukwalla, et al., 1989	Method: Velocity distributions of photofragments from Fe(CO)5.; MS
Δ_rH°	21. ± 6.9	kcal/mol	N/A	Engelking and Lineberger, 1979	Please also see Compton and Stockdale, 1976. Method: LPS and collision with low energy electrons.; MS

C₄FeO₄ (g) = C₃FeO₃ (g) + Carbon monoxide (g)

By formula: C₄FeO₄ (g) = C₃FeO₃ (g) + CO (g)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	28.0 ± 8.6	kcal/mol	FA-SIFT	Sunderlin, Wang, et al., 1992	MS
Δ_rH°	10.	kcal/mol	N/A	Venkataraman, Bandukwalla, et al., 1989	Method: Velocity distributions of photofragments from Fe(CO)5.; MS
Δ_rH°	4.5 ± 9.3	kcal/mol	N/A	Engelking and Lineberger, 1979	Please also see Compton and Stockdale, 1976. Method: LPS and collision with low energy electrons.; MS

(solution) = C₃NiO₃ (solution) + Carbon monoxide (solution)

By formula: C₄NiO₄ (solution) = C₃NiO₃ (solution) + CO (solution)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	22.6	kcal/mol	KinS	Turner, Simpson, et al., 1983	solvent: Liquid krypton; The reaction enthalpy relies on the experimental value for the activation enthalpy, 22.6 kcal/mol, and on the assumption that the activation enthalpy for product recombination is negligible Turner, Simpson, et al., 1983.; MS

(CAS Reg. No. 71564-27-7 • 4294967295 Carbon monoxide ) + = CAS Reg. No. 71564-27-7

By formula: (CAS Reg. No. 71564-27-7 • 4294967295CO) + CO = CAS Reg. No. 71564-27-7

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	34.7 ± 9.6	kcal/mol	N/A	Nakajima, Taguwa, et al., 1994	gas phase; Vertical Detachment Energy: 3.02±0.13 eV; B
Δ_rH°	36. ± 12.	kcal/mol	N/A	Engelking and Lineberger, 1979	gas phase; B
Δ_rH°	41.7 ± 2.5	kcal/mol	CIDT	Sunderlin, Wang, et al., 1992	gas phase; Affinity: CO..Fe(CO)3-; B

= + Carbon monoxide

By formula: C₁₅H₁₀O = C₁₄H₁₀ + CO

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-6.7 ± 1.2	kcal/mol	Cpha	Hung and Grabowski, 1992	liquid phase; solvent: Alkane; ALS
Δ_rH°	4.2 ± 2.5	kcal/mol	Cpha	Herman and Goodman, 1989	solid phase; solvent: Acetonitrile/water; ALS
Δ_rH°	-9.9 ± 2.9	kcal/mol	Cpha	Grabowski, Simon, et al., 1984	liquid phase; solvent: Benzene; ALS

( • 2 Carbon monoxide ) + = ( • 3)

By formula: (CHO⁺ • 2CO) + CO = (CHO⁺ • 3CO)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	4.7 ± 0.3	kcal/mol	PHPMS	Hiraoka and Mori, 1989	gas phase; M
Δ_rH°	6.3	kcal/mol	PHPMS	Hiraoka, Saluja, et al., 1979	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	15.8	cal/mol*K	PHPMS	Hiraoka and Mori, 1989	gas phase; M
Δ_rS°	26.	cal/mol*K	PHPMS	Hiraoka, Saluja, et al., 1979	gas phase; M

( • 3 Carbon monoxide ) + = ( • 4)

By formula: (CHO⁺ • 3CO) + CO = (CHO⁺ • 4CO)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	4.5 ± 0.3	kcal/mol	PHPMS	Hiraoka and Mori, 1989	gas phase; M
Δ_rH°	6.2	kcal/mol	PHPMS	Hiraoka, Saluja, et al., 1979	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	18.2	cal/mol*K	PHPMS	Hiraoka and Mori, 1989	gas phase; M
Δ_rS°	29.	cal/mol*K	PHPMS	Hiraoka, Saluja, et al., 1979	gas phase; M

( • 4 Carbon monoxide ) + = ( • 5)

By formula: (CHO⁺ • 4CO) + CO = (CHO⁺ • 5CO)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	4.2 ± 0.3	kcal/mol	PHPMS	Hiraoka and Mori, 1989	gas phase; M
Δ_rH°	5.8	kcal/mol	PHPMS	Hiraoka, Saluja, et al., 1979	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	22.9	cal/mol*K	PHPMS	Hiraoka and Mori, 1989	gas phase; M
Δ_rS°	32.	cal/mol*K	PHPMS	Hiraoka, Saluja, et al., 1979	gas phase; M

( • Carbon monoxide ) + = ( • 2)

By formula: (CHO⁺ • CO) + CO = (CHO⁺ • 2CO)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	4.9 ± 0.3	kcal/mol	PHPMS	Hiraoka and Mori, 1989	gas phase; M
Δ_rH°	6.6	kcal/mol	PHPMS	Hiraoka, Saluja, et al., 1979	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	15.0	cal/mol*K	PHPMS	Hiraoka and Mori, 1989	gas phase; M
Δ_rS°	24.	cal/mol*K	PHPMS	Hiraoka, Saluja, et al., 1979	gas phase; M

CNiO (g) = Carbon monoxide (g) + (g)

By formula: CNiO (g) = CO (g) + Ni (g)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	40.6 ± 5.8	kcal/mol	FA-SIFT	Sunderlin, Wang, et al., 1992	MS
Δ_rH°	25.8	kcal/mol	N/A	McQuaid, Morris, et al., 1988	Method: Chemiluminescence spectroscopy.; MS
Δ_rH°	29. ± 15.	kcal/mol	N/A	Stevens, Feigerle, et al., 1982	Please also see Compton and Stockdale, 1976. Method: LPS and collision with low energy electrons.; MS

( • Carbon monoxide ) + = ( • 2)

By formula: (Co⁺ • CO) + CO = (Co⁺ • 2CO)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	36.6 ± 2.2	kcal/mol	CIDT	Rodgers and Armentrout, 2000	RCD

Enthalpy of reaction

Δ_rH° (kcal/mol)	T (K)	Method	Reference	Comment
36.4 (+2.1,-0.)		CID	Goebel, Haynes, et al., 1995	gas phase; guided ion beam CID; M
32.9 (+4.8,-0.)		CID	Armentrout and Kickel, 1994	gas phase; guided ion beam CID; M

+ Carbon monoxide = ( • )

By formula: Fe⁺ + CO = (Fe⁺ • CO)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	30.8 ± 1.0	kcal/mol	CIDT	Rodgers and Armentrout, 2000	RCD
Δ_rH°	32. ± 3.	kcal/mol	MKER	Carpenter, van Koppen, et al., 1995	gas phase; determined from MKER and theory; M

Enthalpy of reaction

Δ_rH° (kcal/mol)	T (K)	Method	Reference	Comment
31.3 (+1.9,-0.)		CID	Armentrout and Kickel, 1994	gas phase; guided ion beam CID; M

(solution) + Carbon monoxide (solution) = (solution)

By formula: C₆H₃MnO₅ (solution) + CO (solution) = C₇H₃MnO₆ (solution)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-13.4 ± 1.0	kcal/mol	RSC	Nolan, López de la Vega, et al., 1986	solvent: Tetrahydrofuran; MS
Δ_rH°	-12.6	kcal/mol	EqS	Calderazzo, 1977	solvent: 2,2'-diethoxydiethyl ether; MS

(g) = 0.5 (g) + 4 Carbon monoxide (g) + (cr)

By formula: C₄HCoO₄ (g) = 0.5H₂ (g) + 4CO (g) + Co (cr)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	30.38 ± 0.50	kcal/mol	EqG	Bronshstein, Gankin, et al., 1966	Please also see Pedley and Rylance, 1977 and Cox and Pilcher, 1970. Temperature range: ca. 423-533 K; MS

( • Carbon monoxide ) + = ( • 2)

By formula: (Na⁺ • CO) + CO = (Na⁺ • 2CO)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	5.7 ± 0.7	kcal/mol	CIDT	Rodgers and Armentrout, 2000	RCD
Δ_rH°	5.7 ± 0.7	kcal/mol	CIDT	Walter, Sievers, et al., 1998	RCD
Δ_rH°	7.5	kcal/mol	HPMS	Castleman, Peterson, et al., 1983	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	15.1	cal/mol*K	HPMS	Castleman, Peterson, et al., 1983	gas phase; M

(solution) + (solution) = C₁₀H₅NO₅W (solution) + Carbon monoxide (solution)

By formula: C₆O₆W (solution) + C₄H₄N₂ (solution) = C₁₀H₅NO₅W (solution) + CO (solution)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	6.55 ± 0.69	kcal/mol	PC	Nakashima and Adamson, 1982	solvent: Cyclohexane; MS
Δ_rH°	5.95 ± 0.69	kcal/mol	PC	Nakashima and Adamson, 1982	solvent: Benzene; MS
Δ_rH°	4.40 ± 0.1	kcal/mol	PC	Nakashima and Adamson, 1982	solvent: Tetrahydrofuran; MS

+ Carbon monoxide = ( • )

By formula: Na⁺ + CO = (Na⁺ • CO)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	7.6 ± 1.9	kcal/mol	CIDT	Rodgers and Armentrout, 2000	RCD
Δ_rH°	7.6 ± 1.9	kcal/mol	CIDT	Walter, Sievers, et al., 1998	RCD
Δ_rH°	12.6	kcal/mol	HPMS	Castleman, Peterson, et al., 1983	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	20.4	cal/mol*K	HPMS	Castleman, Peterson, et al., 1983	gas phase; M

(g) = C₃NiO₃ (g) + Carbon monoxide (g)

By formula: C₄NiO₄ (g) = C₃NiO₃ (g) + CO (g)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	25. ± 2.	kcal/mol	N/A	Stevens, Feigerle, et al., 1982	Please also see Compton and Stockdale, 1976. The enthalpy of formation relies on -144.0 ± 0.62 kcal/mol for the enthalpy of formation of Ni(CO)4(g) Method: LPS and collision with low energy electrons.; MS

(CO⁺ • 2 Carbon monoxide ) + = (CO⁺ • 3)

By formula: (CO⁺ • 2CO) + CO = (CO⁺ • 3CO)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	7.21	kcal/mol	PHPMS	Hiraoka and Mori, 1991	gas phase; two isomers, at low and high temperatures; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	24.5	cal/mol*K	PHPMS	Hiraoka and Mori, 1991	gas phase; two isomers, at low and high temperatures; M

(CO⁺ • 5 Carbon monoxide ) + = (CO⁺ • 6)

By formula: (CO⁺ • 5CO) + CO = (CO⁺ • 6CO)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	2.70	kcal/mol	PHPMS	Hiraoka and Mori, 1991	gas phase; two isomers, at low and high temperatures; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	19.1	cal/mol*K	PHPMS	Hiraoka and Mori, 1991	gas phase; two isomers, at low and high temperatures; M

C₃₄H₅₂OTh (solution) + Carbon monoxide (solution) = C₃₅H₅₂O₂Th (solution)

By formula: C₃₄H₅₂OTh (solution) + CO (solution) = C₃₅H₅₂O₂Th (solution)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-5.9 ± 1.5	kcal/mol	EqS	Moloy and Marks, 1984	solvent: Toluene; Temperature range: ca. 180-200 K; MS

C₂₉H₅₀OTh (solution) + Carbon monoxide (solution) = C₃₀H₅₀O₂Th (solution)

By formula: C₂₉H₅₀OTh (solution) + CO (solution) = C₃₀H₅₀O₂Th (solution)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-4.49 ± 0.91	kcal/mol	EqS	Moloy and Marks, 1984	solvent: Toluene; Temperature range: ca. 180-220 K; MS

(cr) = 6 Carbon monoxide (g) + (cr)

By formula: C₆MoO₆ (cr) = 6CO (g) + Mo (cr)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	77.89 ± 0.36	kcal/mol	TD-HZC	Barnes, Pilcher, et al., 1974, 2	Please also see Pedley and Rylance, 1977 and Tel'noi and Rabinovich, 1977.; MS
Δ_rH°	71.0 ± 1.0	kcal/mol	TD-HFC	Connor, Skinner, et al., 1972	Please also see Pedley and Rylance, 1977 and Tel'noi and Rabinovich, 1977.; MS

( • 14 Carbon monoxide ) + = ( • 15)

By formula: (CHO⁺ • 14CO) + CO = (CHO⁺ • 15CO)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	1.76	kcal/mol	PHPMS	Hiraoka and Mori, 1989	gas phase; Entropy change calculated or estimated; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	23.	cal/mol*K	N/A	Hiraoka and Mori, 1989	gas phase; Entropy change calculated or estimated; M

(solution) + Carbon monoxide (solution) = C₁₁H₁₀CrO (solution)

By formula: C₁₀H₁₀Cr (solution) + CO (solution) = C₁₁H₁₀CrO (solution)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-18.8 ± 0.50	kcal/mol	EqS	Wong and Brintzinger, 1975	solvent: Toluene; Temperature range: 280-308 K; MS

(cr) = 6 Carbon monoxide (g) + (cr)

By formula: C₆CrO₆ (cr) = 6CO (g) + Cr (cr)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	63.6 ± 1.	kcal/mol	TD-HFC	Al-Takhin, Connor, et al., 1984, 2	MS
Δ_rH°	75.3 ± 0.2	kcal/mol	TD-HZC	Pittam, Pilcher, et al., 1975	Please also see Pedley and Rylance, 1977 and Tel'noi and Rabinovich, 1977.; MS
Δ_rH°	64.4 ± 1.1	kcal/mol	TD-HFC	Connor, Skinner, et al., 1972	MS

2 (solution) = C₁₂Co₄O₁₂ (solution) + 4 Carbon monoxide (solution)

By formula: 2C₈Co₂O₈ (solution) = C₁₂Co₄O₁₂ (solution) + 4CO (solution)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	29.49 ± 0.50	kcal/mol	EqS	Bor and Dietler, 1980	solvent: Hexane; Temperature range: 378-418 K; MS

Gas phase ion energetics data

Go To: Top, Phase change data, Reaction thermochemistry data, References, Notes

Data evaluated as indicated in comments:
HL - Edward P. Hunter and Sharon G. Lias
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 CO⁺ (ion structure unspecified)

Quantity	Value	Units	Method	Reference	Comment
IE (evaluated)	14.014 ± 0.0003	eV	N/A	N/A	L
Quantity	Value	Units	Method	Reference	Comment
Proton affinity (review)	142.	kcal/mol	N/A	Hunter and Lias, 1998	at C; HL
Proton affinity (review)	101.9	kcal/mol	N/A	Hunter and Lias, 1998	at O; HL
Quantity	Value	Units	Method	Reference	Comment
Gas basicity	134.5	kcal/mol	N/A	Hunter and Lias, 1998	at C; HL
Gas basicity	96.13	kcal/mol	N/A	Hunter and Lias, 1998	at O; HL
Quantity	Value	Units	Method	Reference	Comment
Δ_fH°_{(+) ion}	296.7	kcal/mol	N/A	N/A
Quantity	Value	Units	Method	Reference	Comment
Δ_fH_{(+) ion,0K}	296.0	kcal/mol	N/A	N/A

Electron affinity determinations

EA (eV)	Method	Reference	Comment
1.32608	R-A	Refaey and Franklin, 1976	G3MP2B3 calculations indicate an EA of ca.-1.6 eV, anion unbound; B

Ionization energy determinations

IE (eV)	Method	Reference	Comment
14.0142 ± 0.0003	LS	Erman, Karawajczyk, et al., 1993	LL
14.1	PE	Kimura, Katsumata, et al., 1981	LLK
14.014	S	Fock, Gurtler, et al., 1980	LLK
14.07 ± 0.05	EI	Hille and Mark, 1978	LLK
14.0	PI	Rabalais, Debies, et al., 1974	LLK
14.01	PE	Natalis, 1973	LLK
14.0139	S	Ogawa and Ogawa, 1972	LLK
14.01	PE	Hotop and Niehaus, 1970	RDSH
14.01	PE	Collin and Natalis, 1969	RDSH
14.00	PE	Turner and May, 1966	RDSH
14.013 ± 0.004	S	Krupenie, 1966	RDSH
13.985	PI	Cook, Metzger, et al., 1965	RDSH
14.01	PE	Potts and Williams, 1974	Vertical value; LLK
14.01	PE	Katrib, Debies, et al., 1973	Vertical value; LLK
14.0	PE	Thomas, 1970	Vertical value; RDSH

Appearance energy determinations

Ion	AE (eV)	Other Products	Method	Reference	Comment
C⁺	20.94 ± 0.02	O^-	PI	Oertel, Schenk, et al., 1980	LLK
C⁺	20.89	O^-(2P)	EI	Smyth, Schiavone, et al., 1974	LLK
C⁺	20.88 ± 0.02	O^-	EI	Locht and Momigny, 1971	LLK
C⁺	22.45 ± 0.10	O	EI	Hierl and Franklin, 1967	RDSH
C⁺	20.82 ± 0.05	O^-	EI	Hierl and Franklin, 1967	RDSH
C⁺	22.57 ± 0.20	O	EI	Fineman and Petrocelli, 1961	RDSH
C⁺	20.89 ± 0.09	O^-	EI	Fineman and Petrocelli, 1961	RDSH
CO⁺	19.5 ± 0.2	O^-?	PI	Weissler, Samson, et al., 1959	RDSH
O⁺	23.44	C^-	EI	Smyth, Schiavone, et al., 1974	LLK
O⁺	23.20 ± 0.05	C^-	EI	Hierl and Franklin, 1967	RDSH
O⁺	24.65 ± 0.05	C	EI	Hierl and Franklin, 1967	RDSH
O⁺	23.41 ± 0.17	C^-	EI	Fineman and Petrocelli, 1961	RDSH
O⁺	24.78 ± 0.23	C	EI	Fineman and Petrocelli, 1961	RDSH

References

Go To: Top, Phase change data, Reaction thermochemistry data, Gas phase ion energetics data, Notes

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Notes

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Symbols used in this document:

AE	Appearance energy
EA	Electron affinity
IE (evaluated)	Recommended ionization energy
P_c	Critical pressure
T	Temperature
T_boil	Boiling point
T_c	Critical temperature
T_triple	Triple point temperature
Δ_fH_{(+) ion,0K}	Enthalpy of formation of positive ion at 0K
Δ_rG°	Free energy of reaction at standard conditions
Δ_rH°	Enthalpy of reaction at standard conditions
Δ_rS°	Entropy of reaction at standard conditions
Δ_subH	Enthalpy of sublimation
Δ_vapH	Enthalpy of vaporization
ρ_c	Critical density

Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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