1H-1,2,3-Triazole

Formula: C₂H₃N₃
Molecular weight: 69.0653
IUPAC Standard InChI: InChI=1S/C2H3N3/c1-2-4-5-3-1/h1-2H,(H,3,4,5)
IUPAC Standard InChIKey: QWENRTYMTSOGBR-UHFFFAOYSA-N
CAS Registry Number: 288-36-8
Chemical structure:
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Other names: V-triazole; Osotriazole; Pyrrodiazole; Triazacyclopentadiene; 1,2,3-Triazole
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Gas phase ion energetics data

Data evaluated as indicated in comments:
HL - Edward P. Hunter and Sharon G. Lias

Data compiled as indicated in comments:
B - John E. Bartmess
LLK - Sharon G. Lias, Rhoda D. Levin, and Sherif A. Kafafi

Quantity	Value	Units	Method	Reference	Comment
Proton affinity (review)	210.2	kcal/mol	N/A	Hunter and Lias, 1998	HL
Quantity	Value	Units	Method	Reference	Comment
Gas basicity	202.5	kcal/mol	N/A	Hunter and Lias, 1998	HL

Ionization energy determinations

IE (eV)	Method	Reference	Comment
10.1	PE	Palmer, Simpson, et al., 1981	LLK
10.06	PE	Cradock, Findlay, et al., 1973	Vertical value; LLK

De-protonation reactions

C₂H₂N₃^- + = 1H-1,2,3-Triazole

By formula: C₂H₂N₃^- + H⁺ = C₂H₃N₃

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	346.4 ± 2.1	kcal/mol	G+TS	Catalan, Claramunt, et al., 1988	gas phase; The authors state the acidity is for the 2H isomer, which is more stable(G3MP2B3)in the gas phase than the 1H isomer by 3 kcal/mol. However, only the 1H isomer is commercially available; thus, this may not be a clean equilibrium.; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	339.1 ± 2.0	kcal/mol	IMRE	Catalan, Claramunt, et al., 1988	gas phase; The authors state the acidity is for the 2H isomer, which is more stable(G3MP2B3)in the gas phase than the 1H isomer by 3 kcal/mol. However, only the 1H isomer is commercially available; thus, this may not be a clean equilibrium.; B

References

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

Hunter and Lias, 1998
Hunter, E.P.; Lias, S.G., Evaluated Gas Phase Basicities and Proton Affinities of Molecules: An Update, J. Phys. Chem. Ref. Data, 1998, 27, 3, 413-656, https://doi.org/10.1063/1.556018 . [all data]

Palmer, Simpson, et al., 1981
Palmer, M.H.; Simpson, I.; Wheeler, J.R., Gas phase tautomerism in the triazoles and tetrazoles: A study by photoelectron spectroscopy and ab initio molecular orbital calculations, Z. Naturforsch. A:, 1981, 36, 1246. [all data]

Cradock, Findlay, et al., 1973
Cradock, S.; Findlay, R.H.; Palmer, M.H., The molecular energy levels of the azoles: A study by photoelectron spectroscopy and ab initio molecular orbital calculations, Tetrahedron, 1973, 29, 2173. [all data]

Catalan, Claramunt, et al., 1988
Catalan, J.; Claramunt, R.M.; Elguero, J.; Menedez, M.; Anvia, F.; Quian, J.H.; Taagepera, M.; Taft, R.W., Basicity and Acidity of Azoles. The Annelation Effect in Azoles., J. Am. Chem. Soc., 1988, 110, 13, 4107, https://doi.org/10.1021/ja00221a001 . [all data]

Notes

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

Symbols used in this document:

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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Δ_rG°	Free energy of reaction at standard conditions
Δ_rH°	Enthalpy of reaction at standard conditions