Sulfur dimer

Formula: S₂
Molecular weight: 64.130
IUPAC Standard InChI: InChI=1S/S2/c1-2
IUPAC Standard InChIKey: MAHNFPMIPQKPPI-UHFFFAOYSA-N
CAS Registry Number: 23550-45-0
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.
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:
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 thermochemistry data

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

Quantity	Value	Units	Method	Reference	Comment
Δ_fH°_gas	128.60 ± 0.30	kJ/mol	Review	Cox, Wagman, et al., 1984	CODATA Review value
Δ_fH°_gas	128.60	kJ/mol	Review	Chase, 1998	Data last reviewed in September, 1977
Quantity	Value	Units	Method	Reference	Comment
S°_{gas,1 bar}	228.167 ± 0.010	J/mol*K	Review	Cox, Wagman, et al., 1984	CODATA Review value
S°_{gas,1 bar}	228.19	J/mol*K	Review	Chase, 1998	Data last reviewed in September, 1977

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.

View plot Requires a JavaScript / HTML 5 canvas capable browser.

View table.

Temperature (K)	298. to 6000.
A	33.51313
B	5.065360
C	-1.059670
D	0.089905
E	-0.211911
F	117.6855
G	266.0919
H	128.6003
Reference	Chase, 1998
Comment	Data last reviewed in September, 1977

Gas phase ion energetics data

Go To: Top, Gas phase thermochemistry data, References, Notes

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

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

View reactions leading to S₂⁺ (ion structure unspecified)

Quantity	Value	Units	Method	Reference	Comment
IE (evaluated)	9.356 ± 0.002	eV	N/A	N/A	L

Electron affinity determinations

EA (eV)	Method	Reference	Comment
1.670 ± 0.015	LPES	Moran and Ellison, 1988	B
1.663 ± 0.040	LPES	Celotta, Bennett, et al., 1974	B
1.565 ± 0.050	LPD	Hunsicker, Jones, et al., 1995	B
>0.86 ± 0.10	R-A	Dillard and Franklin, 1968	S^- + COS -> S₂^- + CO. Also S₂^- + COS -> S₃^- + CO, etc. to n=6; B
>2.50 ± 0.80	EIAE	Thynne, 1972	From CS₂; B

Ionization energy determinations

IE (eV)	Method	Reference	Comment
9.4	PE	Bender, Carnovale, et al., 1988	LL
9.356 ± 0.002	PI	Liao and Ng, 1986	LBLHLM
9.6 ± 0.2	EI	Rosinger, Grade, et al., 1983	LBLHLM
9.5 ± 0.2	EI	Grade, Wienecke, et al., 1983	LBLHLM
9.5 ± 0.3	EI	Lau, Brittain, et al., 1982	LBLHLM
9.38 ± 0.03	DER	Coppens, Reynaert, et al., 1979	LLK
9.36 ± 0.02	EI	Tal'roze, Butkovskaya, et al., 1978	LLK
9.8 ± 0.3	EI	Smoes, Drowart, et al., 1977	LLK
10.1 ± 0.3	EI	Piacente, Bardi, et al., 1976	LLK
9.4 ± 0.1	EI	Hildenbrand, 1975	LLK
9.38 ± 0.01	PE	Golob, Jonathan, et al., 1975	LLK
9.30	PE	Berkowitz, 1975	LLK
9.8 ± 0.5	EI	Muenow and Margrave, 1972	LLK
9.42 ± 0.10	EI	Hildenbrand, 1972	LLK
9.40 ± 0.05	S	Donovan, Husain, et al., 1970	RDSH
9.32	S	Barrow, duParcq, et al., 1969	RDSH
9.36 ± 0.02	PI	Berkowitz and Lifshitz, 1968	RDSH
9.55	PE	Wu and Fehlner, 1976	Vertical value; LLK
9.56	PE	Berkowitz, 1975	Vertical value; LLK

Appearance energy determinations

Ion	AE (eV)	Other Products	Method	Reference	Comment
S⁺	14.732 ± 0.005	S	PI	Liao and Ng, 1986	LBLHLM
S⁺	13.5 ± 0.5	S	EI	Piacente, Bardi, et al., 1976	LLK
S⁺	14.74 ± 0.01	S	PI	Berkowitz and Chupka, 1969	RDSH

Anion protonation reactions

S₂^- + = HS₂

By formula: S₂^- + H⁺ = HS₂

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	1380. ± 15.	kJ/mol	D-EA	Moran and Ellison, 1988	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	>1441.8	kJ/mol	IMRB	Goodings, Bohme, et al., 1986	gas phase; S- deprotonates H2S, Sn- for n≥2, does not.; B

References

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

Cox, Wagman, et al., 1984
Cox, J.D.; Wagman, D.D.; Medvedev, V.A., CODATA Key Values for Thermodynamics, Hemisphere Publishing Corp., New York, 1984, 1. [all data]

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

Moran and Ellison, 1988
Moran, S.; Ellison, G.B., Photoelectron Spectroscopy of Sulfur Ions, J. Phys. Chem., 1988, 92, 7, 1794, https://doi.org/10.1021/j100318a021 . [all data]

Celotta, Bennett, et al., 1974
Celotta, R.S.; Bennett, R.A.; Hall, J.L., Laser Photodetachment Determination of the Electron Affinities of OH, NH₂, NH, SO₂, and S₂, J. Chem. Phys., 1974, 60, 5, 1740, https://doi.org/10.1063/1.1681268 . [all data]

Hunsicker, Jones, et al., 1995
Hunsicker, S.; Jones, R.O.; Gantefor, G., Rings and chains in sulfur cluster anions S- to S-9(-): Theory (simulated annealing) and experiment (photoelectron detachment), J. Chem. Phys., 1995, 102, 15, 5917, https://doi.org/10.1063/1.469326 . [all data]

Dillard and Franklin, 1968
Dillard, J.G.; Franklin, J.L., Ion-Molecule Reactions of Negative Ions. I. Negative Ions of Sulfur, J. Chem. Phys., 1968, 48, 5, 2349, https://doi.org/10.1063/1.1669435 . [all data]

Thynne, 1972
Thynne, J.C.J., Negative Ion Studies with a Time-of-Flight Mass Spectrometer., Dyn. Mass Spectrom., 1972, 3, 67. [all data]

Bender, Carnovale, et al., 1988
Bender, H.; Carnovale, F.; Peel, J.B.; Wentrup, C., Dinitrogen sulfide, N₂S, revealed by photoelectron spectroscopy, J. Am. Chem. Soc., 1988, 110, 3458. [all data]

Liao and Ng, 1986
Liao, C.; Ng, C., Molecular beam photoionization study of S₂, J. Chem. Phys., 1986, 84, 788. [all data]

Rosinger, Grade, et al., 1983
Rosinger, W.; Grade, M.; Hirschwald, W., Detection of ion states of S₂ to S₈ by electron impact, Int. J. Mass Spectrom. Ion Processes, 1983, 47, 239. [all data]

Grade, Wienecke, et al., 1983
Grade, M.; Wienecke, J.; Rosinger, W.; Hirschwald, W., Electron impact investigation of the molecules SeS(g) and TeSe(g) under high-temperature equilibrium conditions, Ber. Bunsen-Ges. Phys. Chem., 1983, 87, 355. [all data]

Lau, Brittain, et al., 1982
Lau, K.H.; Brittain, R.D.; Hildenbrand, D.L., Vaporization of As₂S₃ and the dissociation energy of AsS, J. Phys. Chem., 1982, 86, 4429. [all data]

Coppens, Reynaert, et al., 1979
Coppens, P.; Reynaert, J.C.; Drowart, J., Mass spectrometric study of the photoionization of carbon disulphide in the wavelength interval 125-60nm, J. Chem. Soc. Faraday Trans. 2, 1979, 75, 292. [all data]

Tal'roze, Butkovskaya, et al., 1978
Tal'roze, V.L.; Butkovskaya, N.I.; Larichev, M.N.; Leipunskii, I.O.; Morozov, I.I.; Dodonov, A.F.; Kudrov, B.V.; Zelenov, V.V.; Raznikov, V.V., Advances in the mass spectrometry of free radicals, Adv. Mass Spectrom., 1978, 7, 693. [all data]

Smoes, Drowart, et al., 1977
Smoes, S.; Drowart, J.; Welter, J.M., Thermodynamic study of the vaporization of europium monosulfide by Knudsen-cell mass spectrometry atomization energies of EuS(g), Eu₂S(g), EuS₂(g), Eu₂O(g), Eu₂O₂(g), Eu₂OS(g), and Eu₂S₂(g), J. Chem. Thermodyn., 1977, 9, 275. [all data]

Piacente, Bardi, et al., 1976
Piacente, V.; Bardi, G.; di Paolo, V.; Ferro, D., The vapour pressure over Ga₂S₂ and Ga₂Se₂, J. Chem. Thermodyn., 1976, 8, 391. [all data]

Hildenbrand, 1975
Hildenbrand, D.L., Vertical ionization potential of the CF₂ radical, Chem. Phys. Lett., 1975, 32, 30. [all data]

Golob, Jonathan, et al., 1975
Golob, L.; Jonathan, N.; Morris, A.; Okuda, M.; Ross, K.J.; Smith, D.J., Vacuum ultraviolet photoelectron spectroscopy of transient species, J. Chem. Soc. Faraday Trans. 2, 1975, 71, 1026. [all data]

Berkowitz, 1975
Berkowitz, J., PES of high temperature vapors. VII. S₂ and Te₂, J. Chem. Phys., 1975, 62, 4074. [all data]

Muenow and Margrave, 1972
Muenow, D.W.; Margrave, J.L., Mass spectrometric observations of gaseous phosphorus sulfides and oxysulfides, J. Inorg. Nucl. Chem., 1972, 34, 89. [all data]

Hildenbrand, 1972
Hildenbrand, D.L., Thermochemistry of the molecules CS and CS⁺, Chem. Phys. Lett., 1972, 15, 379. [all data]

Donovan, Husain, et al., 1970
Donovan, R.J.; Husain, D.; Stevenson, C.D., Vacuum ultra-violet spectra of transient molecules and radicals. Part 1. CS and S₂, J. Chem. Soc. Faraday Trans., 1970, 66, 1. [all data]

Barrow, duParcq, et al., 1969
Barrow, R.F.; duParcq, R.P.; Ricks, J.M., Rotational analysis of the C 3Σ_u--X 3g- system of ³²S₂, J. Phys. B:, 1969, 2, 413. [all data]

Berkowitz and Lifshitz, 1968
Berkowitz, J.; Lifshitz, C., Photoionization of high temperature vapors. II. Sulfur molecular species, J. Chem. Phys., 1968, 48, 4346. [all data]

Wu and Fehlner, 1976
Wu, M.; Fehlner, T.P., Valence level photoelectron spectra of some heavy group 4-6 diatomic molecules, J. Am. Chem. Soc., 1976, 98, 7578. [all data]

Berkowitz and Chupka, 1969
Berkowitz, J.; Chupka, W.A., Photoionization of high-temperature vapors. VI. S₂, Se₂, and Te₂, J. Chem. Phys., 1969, 50, 4245. [all data]

Goodings, Bohme, et al., 1986
Goodings, J.M.; Bohme, D.K.; Elguindi, K.; Fox, A., Sulphur Anion Chemistry in Hydrocarbon Flames with H₂S, OCS, and SO₂ Additives, Can. J. Chem., 1986, 64, 4, 689, https://doi.org/10.1139/v86-110 . [all data]

Notes

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

Symbols used in this document:

AE	Appearance energy
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
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.