1H-Indazole

Formula: C₇H₆N₂
Molecular weight: 118.1359
IUPAC Standard InChI: InChI=1S/C7H6N2/c1-2-4-7-6(3-1)5-8-9-7/h1-5H,(H,8,9)
IUPAC Standard InChIKey: BAXOFTOLAUCFNW-UHFFFAOYSA-N
CAS Registry Number: 271-44-3
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: Isoindazole; 1,2-Diazaindene; 1H-Benzopyrazole; 2-Azaindole; Indazole; Benzopyrazole
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Information on this page:
Other data available:
- Mass spectrum (electron ionization)
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Gas phase thermochemistry data

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Data compiled by: Hussein Y. Afeefy, Joel F. Liebman, and Stephen E. Stein

Quantity	Value	Units	Method	Reference	Comment
Δ_fH°_gas	58.08 ± 0.31	kcal/mol	Ccb	Jimenez, Roux, et al., 1987	see Jimenez, Roux, et al., 1986
Δ_fH°_gas	60.8 ± 1.1	kcal/mol	Ccb	Faour and Akasheh, 1985

Condensed phase thermochemistry data

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Data compiled as indicated in comments:
ALS - Hussein Y. Afeefy, Joel F. Liebman, and Stephen E. Stein
DH - Eugene S. Domalski and Elizabeth D. Hearing

Quantity	Value	Units	Method	Reference	Comment
Δ_fH°_solid	36.30 ± 0.31	kcal/mol	Ccb	Jimenez, Roux, et al., 1987	see Jimenez, Roux, et al., 1986; ALS
Δ_fH°_solid	39.79 ± 0.88	kcal/mol	Ccb	Faour and Akasheh, 1985	ALS
Quantity	Value	Units	Method	Reference	Comment
Δ_cH°_solid	-899.6 ± 0.2	kcal/mol	Ccb	Jimenez, Roux, et al., 1987	see Jimenez, Roux, et al., 1986; ALS
Δ_cH°_solid	-903.11 ± 0.84	kcal/mol	Ccb	Faour and Akasheh, 1985	ALS
Δ_cH°_solid	-899.5	kcal/mol	Ccb	Zimmerman and Geisenfelder, 1961	ALS

Constant pressure heat capacity of solid

C_p,solid (cal/mol*K)	Temperature (K)	Reference	Comment
30.78	298.15	Jimenez, Roux, et al., 1987	Cp given as 1.09 J K-1 g-1.; DH

Phase change data

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Data compiled as indicated in comments:
BS - Robert L. Brown and Stephen E. Stein
TRC - Thermodynamics Research Center, NIST Boulder Laboratories, Chris Muzny director
ALS - Hussein Y. Afeefy, Joel F. Liebman, and Stephen E. Stein
DRB - Donald R. Burgess, Jr.
AC - William E. Acree, Jr., James S. Chickos

Quantity	Value	Units	Method	Reference	Comment
T_fus	419.3	K	N/A	Rondestvedt and Blanchard, 1955	Uncertainty assigned by TRC = 0.6 K; TRC
Quantity	Value	Units	Method	Reference	Comment
Δ_subH°	21.8 ± 0.05	kcal/mol	V	Jimenez, Roux, et al., 1987	see Jimenez, Roux, et al., 1986; ALS
Δ_subH°	21.8	kcal/mol	N/A	Jimenez, Roux, et al., 1987	DRB
Δ_subH°	21.8 ± 0.05	kcal/mol	N/A	Jimenez, Roux, et al., 1987	See also Jimenez, Roux, et al., 1986, 2.; AC
Δ_subH°	21.0	kcal/mol	N/A	Faour and Akasheh, 1985	DRB
Δ_subH°	23.2	kcal/mol	V	Zimmerman and Geisenfelder, 1961	ALS

Reduced pressure boiling point

T_boil (K)	Pressure (atm)	Reference	Comment
543.2	0.978	Aldrich Chemical Company Inc., 1990	BS

Enthalpy of sublimation

Δ_subH (kcal/mol)	Temperature (K)	Method	Reference	Comment
21.7 ± 0.05	318.	ME	Jimenez, Roux, et al., 1987	Based on data from 308. to 317. 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

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Data compiled by: John E. Bartmess

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Individual Reactions

C₇H₅N₂^- + = 1H-Indazole

By formula: C₇H₅N₂^- + H⁺ = C₇H₆N₂

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	348.3 ± 2.1	kcal/mol	G+TS	Catalan, Claramunt, et al., 1988	gas phase
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	340.6 ± 2.0	kcal/mol	IMRE	Catalan, Claramunt, et al., 1988	gas phase

Gas phase ion energetics data

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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)	215.3	kcal/mol	N/A	Hunter and Lias, 1998	HL
Quantity	Value	Units	Method	Reference	Comment
Gas basicity	207.7	kcal/mol	N/A	Hunter and Lias, 1998	HL

Ionization energy determinations

IE (eV)	Method	Reference	Comment
8.35	PE	Kovac, Klasinc, et al., 1980	LLK
8.35	PE	Kovac, Klasinc, et al., 1980	Vertical value; LLK

De-protonation reactions

C₇H₅N₂^- + = 1H-Indazole

By formula: C₇H₅N₂^- + H⁺ = C₇H₆N₂

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	348.3 ± 2.1	kcal/mol	G+TS	Catalan, Claramunt, et al., 1988	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	340.6 ± 2.0	kcal/mol	IMRE	Catalan, Claramunt, et al., 1988	gas phase; B

Gas Chromatography

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Data compiled by: NIST Mass Spectrometry Data Center, William E. Wallace, director

Normal alkane RI, non-polar column, temperature ramp

View large format table.

Column type	Active phase	I	Reference	Comment
Capillary	Ultra-1	1260.	Okumura, 1991	25. m/0.32 mm/0.25 μm, He, 3. K/min; T_start: 80. C; T_end: 260. C

Normal alkane RI, polar column, custom temperature program

View large format table.

Column type	Active phase	I	Reference	Comment
Capillary	DB-Wax	2556.	Peng, Yang, et al., 1991	Program: not specified

References

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

Jimenez, Roux, et al., 1987
Jimenez, P.; Roux, M.V.; Turrion, C., Thermochemical properties of N-heterocyclic compounds. I. Enthalpies of combustion, vapour pressures and enthalpies of sublimation, and enthalpies of formation of pyrazole, imidazole, indazole, and benzimidazole, J. Chem. Thermodyn., 1987, 19, 985-992. [all data]

Jimenez, Roux, et al., 1986
Jimenez, P.; Roux, M.V.; Turrion, C.; Gomis, F., Thermochemical properties of some N-heterocyclic compounds, J. Calorim. Anal. Therm. Thermodyn. Chim., 1986, 17, 469-470. [all data]

Faour and Akasheh, 1985
Faour, M.; Akasheh, T.S., Heat of combustion of some N-heterocycle compounds. Part 1, J. Chem. Soc. Perkin Trans. 2, 1985, 811-713. [all data]

Zimmerman and Geisenfelder, 1961
Zimmerman, H.; Geisenfelder, H., Uber die Mesomerieenergie von Azolen, Z. Electrochem., 1961, 65, 368-371. [all data]

Rondestvedt and Blanchard, 1955
Rondestvedt, C.S.; Blanchard, H.S., Arylation of Unsaturated Systems by Free Radicals I. Arylation of Alkylbenzenes, J. Am. Chem. Soc., 1955, 77, 1769. [all data]

Jimenez, Roux, et al., 1986, 2
Jimenez, P.; Roux, M.V.; Turrion, C.; Gomis, F., Thermochemical properties of some N-heterocyclic compounds, J. Calorim. Anal. Therm. Thermodyn. Chim., 1986, 17, 469. [all data]

Aldrich Chemical Company Inc., 1990
Aldrich Chemical Company Inc., Catalog Handbook of Fine Chemicals, Aldrich Chemical Company, Inc., Milwaukee WI, 1990, 1. [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]

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]

Kovac, Klasinc, et al., 1980
Kovac, B.; Klasinc, L.; Stanovnik, B.; Tisler, M., Photoelectron spectroscopy of J. Heterocycl. Chem.. Azaindenes azaindolizines (1), J. Heterocycl. Chem., 1980, 17, 689. [all data]

Okumura, 1991
Okumura, T., retention indices of environmental chemicals on methyl silicone capillary column, Journal of Environmental Chemistry (Japan), 1991, 1, 2, 333-358, https://doi.org/10.5985/jec.1.333 . [all data]

Peng, Yang, et al., 1991
Peng, C.T.; Yang, Z.C.; Ding, S.F., Prediction of rentention idexes. II. Structure-retention index relationship on polar columns, J. Chromatogr., 1991, 586, 1, 85-112, https://doi.org/10.1016/0021-9673(91)80028-F . [all data]

Notes

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Symbols used in this document:

C_p,solid	Constant pressure heat capacity of solid
T_boil	Boiling point
T_fus	Fusion (melting) point
Δ_cH°_solid	Enthalpy of combustion of solid at standard conditions
Δ_fH°_gas	Enthalpy of formation of gas at standard conditions
Δ_fH°_solid	Enthalpy of formation of solid at standard conditions
Δ_rG°	Free energy of reaction at standard conditions
Δ_rH°	Enthalpy of reaction at standard conditions
Δ_subH	Enthalpy of sublimation
Δ_subH°	Enthalpy of sublimation at standard conditions

Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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