Mercapto radical

Formula: HS
Molecular weight: 33.073
IUPAC Standard InChI: InChI=1S/HS/h1H
IUPAC Standard InChIKey: PXQLVRUNWNTZOS-UHFFFAOYSA-N
CAS Registry Number: 13940-21-1
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.
Isotopologues:
- Mercapto-d
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Other data available:
- Gas phase thermochemistry data
- Reaction thermochemistry data
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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:
B - John E. Bartmess
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

View reactions leading to HS⁺ (ion structure unspecified)

Quantity	Value	Units	Method	Reference	Comment
IE (evaluated)	10.422 ± 0.001	eV	N/A	N/A	L
Quantity	Value	Units	Method	Reference	Comment
Δ_fH°_{(+) ion}	273.3 ± 0.9	kcal/mol	N/A	N/A
Quantity	Value	Units	Method	Reference	Comment
Δ_fH_{(+) ion,0K}	273.2 ± 0.9	kcal/mol	N/A	N/A

Electron affinity determinations

EA (eV)	Method	Reference	Comment
2.31473	LPES	Chaibi, Delsart, et al., 2006	For H(32)S-. Given: 2.3147282(17) eV; B
2.3170 ± 0.0020	LPES	Breyer, Frey, et al., 1981	B
2.326 ± 0.091	D-EA	Bartmess, Scott, et al., 1979	value altered from reference due to change in acidity scale; B
2.32085	D-EA	Shiell, Hu, et al., 1900	0K:350.125±0.009 kcal/mol, corr to 298K from Gurvich, Veyts, et al., With EA( Breyer, Frey, et al., 1981)BDE(0K)=89.97±0.05; B
2.3140 ± 0.0030	LPD	Janousek and Brauman, 1981	B
2.3016 ± 0.0013	LPD	Eyler and Atkinson, 1974	B
2.319 ± 0.010	PD	Steiner, 1968	B
2.19422	R-A	Refaey, 1976	B
2.31521	N/A	Check, Faust, et al., 2001	MnO2-(t); ; ΔS(EA)=5.4; B
2.298 ± 0.039	SI	Page and Goode, 1969	The Magnetron method, lacking mass analysis, is not considered reliable.; B

Ionization energy determinations

IE (eV)	Method	Reference	Comment
10.4219	TE	Milan, Buma, et al., 1996	LL
10.4219 ± 0.0004	TE	Hsu, Baldwin, et al., 1994	LL
10.40 ± 0.01	END	Smith, Adams, et al., 1981	LLK
10.43	EVAL	Huber and Herzberg, 1979	LLK
10.37 ± 0.01	PE	Dunlavey, Dyke, et al., 1979	LLK
10.41 ± 0.03	S	Morrow, 1966	RDSH
10.5 ± 0.1	EI	Palmer and Lossing, 1962	RDSH

De-protonation reactions

S^- + = Mercapto radical

By formula: S^- + H⁺ = HS

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	350.150 ± 0.070	kcal/mol	D-EA	Blondel, Chaibi, et al., 2005	gas phase; (32)S: 2.0771040(9) eV: revised analysis of Blondel, Delsart, et al., 2001; B
Δ_rH°	350.2 ± 2.9	kcal/mol	Endo	Rempala and Ervin, 2000	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	344.61 ± 0.19	kcal/mol	H-TS	Blondel, Chaibi, et al., 2005	gas phase; (32)S: 2.0771040(9) eV: revised analysis of Blondel, Delsart, et al., 2001; B
Δ_rG°	344.7 ± 3.0	kcal/mol	H-TS	Rempala and Ervin, 2000	gas phase; B

Anion protonation reactions

HS^- + =

By formula: HS^- + H⁺ = H₂S

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	351.4 ± 0.7	kcal/mol	AVG	N/A	Average of 6 out of 7 values; Individual data points
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	344.4 ± 3.0	kcal/mol	H-TS	Rempala and Ervin, 2000	gas phase; B
Δ_rG°	344.8 ± 2.0	kcal/mol	IMRE	Bartmess, Scott, et al., 1979	gas phase; value altered from reference due to change in acidity scale; B
Δ_rG°	344.90 ± 0.10	kcal/mol	H-TS	Shiell, Hu, et al., 1900	gas phase; 0K:350.125±0.009 kcal/mol, corr to 298K from Gurvich, Veyts, et al., With EA( Breyer, Frey, et al., 1981)BDE(0K)=89.97±0.05; B
Δ_rG°	345.6 ± 2.0	kcal/mol	IMRE	Cumming and Kebarle, 1978	gas phase; B
Δ_rG°	342.30	kcal/mol	N/A	Check, Faust, et al., 2001	gas phase; MnO2-(t); ; ΔS(EA)=5.4; B

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 July, 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 ³²S¹H
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
H ²Δ					[9.46]					[1.35₁]	H ← X	80847.5 1
H ²Δ	↳Morrow, 1966
G ²Δ					[9.01]					[1.38₄]	G ← X	79343.3 1
G ²Δ	↳Morrow, 1966
F ²Δ					[9.19]					[1.37₀]	F ← X	76707.9 1
F ²Δ	↳Morrow, 1966
E ²Σ					[9.076]					[1.378₈]	E ← X	71317.7 1
E ²Σ	↳Morrow, 1966
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 ²Δ					[9.215]			[6.1E-4]		[1.368₄]	D ← X	71194.7₂ 1
D ²Δ	↳Morrow, 1966
C ²Δ	2										C ← X	(64060)
C ²Δ	↳Morrow, 1966
B ²Σ	(59641)	[2557.03] Z	(56.8) 3		8.785	0.259		[8.2E-4]		1.401₄	B ← X R	59621.7₁ Z
B ²Σ	↳Morrow, 1966
A ²Σ⁺	(31038)	1979.8 Z	97.6₅		8.521 4 5	0.46₄	-0.02₂	6.3₆E-4	6.₀E-5	1.423₀	A ↔ X 6 R	30662.4₂ Z
A ²Σ⁺	↳missing citation; missing citation; Pathak and Palmer, 1969
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
X ²Π_i	0 7	(2711.₆) 8	(59.₉) 8		[9.461₁] 9	(0.27₀) 8		[4.8₀E-4]		1.340₉ 10
	↳Acquista and Schoen, 1970
										11
	↳Meerts and Dymanus, 1974; Meerts and Dymanus, 1975
										12
	↳McDonald, 1963; Radford and Linzer, 1963; Uehara and Morino, 1970; Brown and Thistlethwaite, 1972; Tanimoto and Uehara, 1973

Notes

The v₀₀ values refer to the zero-point of the Hill-Van Vleck expression for the lower state and are exclusive of the J independent terms -BΛ² in the upper states, contrary to definitions normally adopted in these tables. Only the X ²Π_3/2 subbands have been observed.

Weak diffuse band near 1561 ; sharper in SD.

From isotope shifts.

Spin-splitting constant γ₀ = +0.313.

The rotational lines of bands having v'≥1 are increasingly diffuse.

Observed in absorption (flash photolysis of H₂S and D₂S) by Ramsay, 1952, Johns and Ramsay, 1961, in matrix absorption by Acquista and Schoen, 1970, and in emission by Leach, 1950, Pathak and Palmer, 1969. Franck-Condon factors Nicholls, Fraser, et al., 1960.

A₀ = -376.9₆ Ramsay, 1952. On the basis of certain higher order corrections Veseth, 1971 gives A₀ = -378.5₃ Veseth, 1971 (and B₀ = 9.465, D₀ = 4.7E-4).

From the constants for SD Pathak and Palmer, 1969.

Λ-doubling and hfs parameters Meerts and Dymanus, 1975.

Vibration sp. 16

Hf Λ-doubling sp. 17 18

EPR sp. 19

From an extrapolation of the vibrational levels of A ²Σ⁺ to the limit ¹D + ²S Johns and Ramsay, 1961; consistent with the observed predissociation in A ²Σ⁺. Photoionization mass-spectrometry of H₂S Dibeler and Liston, 1968 gives D₀⁰C(S¹H) = 3.67 eV (recalculated using updated auxilliary data). See also Meyer and Rosmus, 1975.

Both D₀⁰ and I.P. refer to the lowest existing molecular level, in agreement with definitions but contrary to the values given by Johns and Ramsay, 1961 and Morrow, 1966, respectively, which refer to the zero-point of the Hill-Van Vleck expression for the ground state.

Extrapolation of a short Rydberg series Morrow, 1966.

In argon matrices at 20.4 K.

Molecular beam electric resonance study. The strongest Λ-doubling transitions in ²Π_3/2, J=3/2 occur at 111.4862 (F=1-1) and 111.5452 MHz (F=2-2), in J=5/2 at 442.4781(F=2-2) and 442.6277 MHz (F=3-3); these observations supersede earlier predictions Radford and Linzer, 1963, Brown and Thistlethwaite, 1972, Tanimoto and Uehara, 1973 from EPR measurements.

μ_el(v=0) = 0.7580 D Meerts and Dymanus, 1974, Meerts and Dymanus, 1975. Stark effect in EPR spectrum Carrington, Levy, et al., 1967, Byfleet, Carrington, et al., 1971 yields the less accurate value 0.62 D. Predicted dipole moment function Meyer and Rosmus, 1975. Theoretical charge distributions Cade, Bader, et al., 1969.

For the EPR spectrum of ³³SH and ³³S hf interaction see Miller, 1971.

Large electronic isotope shift.

Spin splitting constant γ₀ = +0.163. The lines of the 2-0 absorption band are diffuse.

A₀ = -376.7₅ Ramsay, 1952. Taking into account higher order corrections Veseth, 1971 derives A₀ = -378.32 Veseth, 1971 (and B₀ = 4.899, D₀ = 1.3E-4).

Estimates by Ramsay, 1952 and Pathak and Palmer, 1969.

μ_el(v=0) = 0.7571 D Meerts and Dymanus, 1975.

References

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

Chaibi, Delsart, et al., 2006
Chaibi, W.; Delsart, C.; Drag, C.; Blondel, C., High precision measurement of the (SH)-S-32 electron affinity by laser detachment microscopy, J. Molec. Spectros., 2006, 239, 1, 11-15, https://doi.org/10.1016/j.jms.2006.05.012 . [all data]

Breyer, Frey, et al., 1981
Breyer, F.; Frey, P.; Hotop, H., High Resolution Photoelectron Spectrometry of Negative Ions: Rotational Transitions in Laser-Photodetachment of OH-, SH-, and SD-, Z. Phys. A, 1981, 300, 1, 7, https://doi.org/10.1007/BF01412609 . [all data]

Bartmess, Scott, et al., 1979
Bartmess, J.E.; Scott, J.A.; McIver, R.T., Jr., The gas phase acidity scale from methanol to phenol, J. Am. Chem. Soc., 1979, 101, 6047. [all data]

Shiell, Hu, et al., 1900
Shiell, R.C.; Hu, X.K.; Hu, Q.J.; Hepburn, J.W., A determination of the bond dissociation energy (D-0(H-SH)): Threshold ion-pair production spectroscopy (TIPPS) of a triatomic molecule, J. Phys. Chem. A, 1900, 104, 19, 4339-4342, https://doi.org/10.1021/jp000025k . [all data]

Gurvich, Veyts, et al.
Gurvich, L.V.; Veyts, I.V.; Alcock, C.B., Hemisphere Publishing, NY, 1989, V. 1 2, Thermodynamic Properties of Individual Substances, 4th Ed. [all data]

Janousek and Brauman, 1981
Janousek, B.K.; Brauman, J.I., Electron Photodetachment from HS-. The Electron Affinity of HS, Phys. Rev. A, 1981, 23, 4, 1673, https://doi.org/10.1103/PhysRevA.23.1673 . [all data]

Eyler and Atkinson, 1974
Eyler, J.R.; Atkinson, G.H., Dye laser-induced photodetachment of electrons from SH- studied by ICR spectroscopy, Chem. Phys. Lett., 1974, 28, 217. [all data]

Steiner, 1968
Steiner, B., Photodetachment of Electrons From SH^-, J. Chem. Phys., 1968, 49, 11, 5097, https://doi.org/10.1063/1.1670004 . [all data]

Refaey, 1976
Refaey, K.M.A., Endoergic ion-molecule-collision processes of negative ions. II. Collisions of I- on H₂S, CS₂, and COS, J. Chem. Phys., 1976, 65, 2002. [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]

Page and Goode, 1969
Page, F.M.; Goode, G.C., Negative Ions and the Magnetron., Wiley, NY, 1969. [all data]

Milan, Buma, et al., 1996
Milan, J.B.; Buma, W.J.; deLange, C.A., Zero-kinetic-energy pulsed-field ionization spectroscopy of the a ¹δ state of SH⁺ (CD⁺), J. Chem. Phys., 1996, 104, 521. [all data]

Hsu, Baldwin, et al., 1994
Hsu, C.-W.; Baldwin, D.P.; Liao, C.-L.; Ng, C.Y., Rotationally resolved nonresonant two-photon ionization of SH, J. Chem. Phys., 1994, 100, 8047. [all data]

Smith, Adams, et al., 1981
Smith, D.; Adams, N.G.; Lindinger, W., Reactions of the HnS ions (n = 0 to 3) with several molecular gases at thermal energies, J. Chem. Phys., 1981, 75, 3365. [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]

Dunlavey, Dyke, et al., 1979
Dunlavey, S.; Dyke, J.; Fayad, N.; Jonathan, N.; Morris, A., Vacuum ultraviolet photoelectron spectroscopy of transient species. Part 10. The SH(X2çi) radical and the S(3P) atom, Mol. Phys., 1979, 38, 729. [all data]

Morrow, 1966
Morrow, B.A., The absorption spectrum of SH and SD in the vacuum ultraviolet, Can. J. Phys., 1966, 44, 2447. [all data]

Palmer and Lossing, 1962
Palmer, T.F.; Lossing, F.P., Free radicals by mass spectrometry. XXVIII. The HS, CH₃S, and phenyl-S radicals: ionization potentials and heats of formation, J. Am. Chem. Soc., 1962, 84, 4661. [all data]

Blondel, Chaibi, et al., 2005
Blondel, C.; Chaibi, W.; Delsart, C.; Drag, C.; Goldfarb, F.; Kroger, S., The electron affinities of O, Si, and S revisited with the photodetachment microscope, Eur. Phys. J. D, 2005, 33, 3, 335-342, https://doi.org/10.1140/epjd/e2005-00069-9 . [all data]

Blondel, Delsart, et al., 2001
Blondel, C.; Delsart, C.; Goldfarb, F., Electron spectrometry at the mu eV level and the electron affinities of Si and F, J. Phys. B: Atom. Mol. Opt. Phys., 2001, 34, 9, L281-L288, https://doi.org/10.1088/0953-4075/34/9/101 . [all data]

Rempala and Ervin, 2000
Rempala, K.; Ervin, K.M., Collisional activation of the Endoergic Hydrogen Atom Transfer Reaction S-(2P) + H2 - SH- + H, J. Chem. Phys., 2000, 112, 10, 4579, https://doi.org/10.1063/1.481016 . [all data]

Cumming and Kebarle, 1978
Cumming, J.B.; Kebarle, P., Summary of gas phase measurements involving acids AH. Entropy changes in proton transfer reactions involving negative ions. Bond dissociation energies D(A-H) and electron affinities EA(A), Can. J. Chem., 1978, 56, 1. [all data]

Pathak and Palmer, 1969
Pathak, C.M.; Palmer, H.B., Chemical excitation of the A²Σ⁺-X²Π system of SH and SD, J. Mol. Spectrosc., 1969, 32, 157. [all data]

Acquista and Schoen, 1970
Acquista, N.; Schoen, L.J., Matrix isolation spectrum of the SH radical, J. Chem. Phys., 1970, 53, 1290. [all data]

Meerts and Dymanus, 1974
Meerts, W.L.; Dymanus, A., The hyperfine Λ-doubling spectrum of sulfur hydride in the ²Π_3/2 state, Astrophys. J., 1974, 187, 45. [all data]

Meerts and Dymanus, 1975
Meerts, W.L.; Dymanus, A., A molecular beam electric resonance study of the hyperfine Λ doubling spectrum of OH, OD, SH, and SD, Can. J. Phys., 1975, 53, 2123. [all data]

McDonald, 1963
McDonald, C.C., EPR spectra of SH, SD, and SO radicals in the gaseous state, J. Chem. Phys., 1963, 39, 2587. [all data]

Radford and Linzer, 1963
Radford, H.E.; Linzer, M., Radio spectrum of SH, Phys. Rev. Lett., 1963, 10, 443. [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]

Brown and Thistlethwaite, 1972
Brown, J.M.; Thistlethwaite, P.J., A measurment of the λ-doubling transition frequencies for SH in its second rotational level, Mol. Phys., 1972, 23, 635. [all data]

Tanimoto and Uehara, 1973
Tanimoto, M.; Uehara, H., Proton hyperfine interactions in the gas-phase E.P.R. spectra of SH (²Π_3/2) in two lowest rotational levels, Mol. Phys., 1973, 25, 1193. [all data]

Ramsay, 1952
Ramsay, D.A., Absorption spectra of SH and SD produced by flash photolysis of H₂S and D₂S, J. Chem. Phys., 1952, 20, 1920. [all data]

Johns and Ramsay, 1961
Johns, J.W.C.; Ramsay, D.A., The absorption spectrum and dissociation energy of SH, Can. J. Phys., 1961, 39, 210. [all data]

Leach, 1950
Leach, M.S., Sur les spectres d'emission de l'hydrogene sulfure excites par chocs electroniques. Spectre d'emission du radical SH, Compt. Rend., 1950, 230, 2181. [all data]

Nicholls, Fraser, et al., 1960
Nicholls, R.W.; Fraser, P.A.; Jarmain, W.R.; McEachran, R.P., Vibrational transition probabilities of diatomic molecules: collected results. IV. BeO, BO, CH⁺, CO, NO, SH, O₂, O₂⁺, Astrophys. J., 1960, 131, 399. [all data]

Veseth, 1971
Veseth, L., Corrections to the spin-orbit splitting in ²Π states of diatomic molecules, J. Mol. Spectrosc., 1971, 38, 228. [all data]

Dibeler and Liston, 1968
Dibeler, V.H.; Liston, S.K., Mass-spectrometric study of photoionization. XI.Hydrogen sulfide and sulfur dioxide, J. Chem. Phys., 1968, 49, 482. [all data]

Meyer and Rosmus, 1975
Meyer, W.; Rosmus, P., PNO-Cl and CEPA studies of electron correlation effects. III. Spectroscopic constants and dipole moment functions for the ground states of the first-row and second-row diatomic hydrides, J. Chem. Phys., 1975, 63, 2356. [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]

Byfleet, Carrington, et al., 1971
Byfleet, C.R.; Carrington, A.; Russell, D.K., Electric dipole moments of open-shell diatomic molecules, Mol. Phys., 1971, 20, 271. [all data]

Cade, Bader, et al., 1969
Cade, P.E.; Bader, R.F.W.; Henneker, W.H.; Keaveny, I., Molecular charge distributions and chemical binding. IV. The second-row diatomic hydrides AH, J. Chem. Phys., 1969, 50, 5313. [all data]

Miller, 1971
Miller, T.A., Sulfur-33 hyperfine interactions in the gas-phase electron resonance spectra of ²Π SH and ¹Δ SO, J. Chem. Phys., 1971, 54, 1658. [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
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

Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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