Indene

Formula: C₉H₈
Molecular weight: 116.1598
IUPAC Standard InChI: InChI=1S/C9H8/c1-2-5-9-7-3-6-8(9)4-1/h1-6H,7H2
IUPAC Standard InChIKey: YBYIRNPNPLQARY-UHFFFAOYSA-N
CAS Registry Number: 95-13-6
Chemical structure:
This structure is also available as a 2d Mol file or as a computed 3d SD file
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Other names: 1H-Indene
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Gas phase thermochemistry data

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

Data compiled as indicated in comments:
DRB - Donald R. Burgess, Jr.
GT - Glushko Thermocenter, Russian Academy of Sciences, Moscow

Quantity	Value	Units	Method	Reference	Comment
Δ_fH°_gas	161.2 ± 2.3	kJ/mol	Review	Roux, Temprado, et al., 2008	There are sufficient literature values to make a qualified recommendation where the suggested value is in good agreement with values predicted using thermochemical cycles or from reliable estimates. In general, the evaluated uncertainty limits are on the order of (2 to 4) kJ/mol.; DRB

Constant pressure heat capacity of gas

C_p,gas (J/mol*K)	Temperature (K)	Reference	Comment
100.86	250.	Klots T.D., 1995	Recommended S(T) and Cp(T) values are based on experimental assignment of vibrational spectra and they agree within 1.2 J/mol*K with values calculated using statistical mechanics and the vibrational frequencies estimated from force field approximation for polycyclic aromatic hydrocarbons [ Dorofeeva O.V., 1986].; GT
123.14	298.15
123.97	300.
146.75	350.
168.12	400.
187.74	450.
205.29	500.
221.08	550.
235.13	600.
247.77	650.
259.08	700.

Condensed phase thermochemistry data

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

Data compiled as indicated in comments:
DRB - Donald R. Burgess, Jr.
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°_liquid	110.6 ± 1.8	kJ/mol	Review	Roux, Temprado, et al., 2008	There are sufficient literature values to make a qualified recommendation where the suggested value is in good agreement with values predicted using thermochemical cycles or from reliable estimates. In general, the evaluated uncertainty limits are on the order of (2 to 4) kJ/mol.; DRB
Δ_fH°_liquid	110. ± 1.	kJ/mol	Ccb	Stull, Sinke, et al., 1961	see Stull, Sinke, et al., 1959; ALS
Quantity	Value	Units	Method	Reference	Comment
Δ_cH°_liquid	-4795.5 ± 1.3	kJ/mol	Ccb	Stull, Sinke, et al., 1961	see Stull, Sinke, et al., 1959; Corresponding Δ_fHº_liquid = 110.6 kJ/mol (simple calculation by NIST; no Washburn corrections); ALS
Quantity	Value	Units	Method	Reference	Comment
S°_liquid	214.18	J/mol*K	N/A	Stull, Sinke, et al., 1961	DH
S°_liquid	215.35	J/mol*K	N/A	Stull, Sinke, et al., 1959, 2	DH

Constant pressure heat capacity of liquid

C_p,liquid (J/mol*K)	Temperature (K)	Reference	Comment
186.94	298.15	Stull, Sinke, et al., 1961	T = 15 to 320 K.; DH
186.94	298.15	Stull, Sinke, et al., 1959, 2	T = 15 to 320 K.; DH

Gas phase ion energetics data

Go To: Top, Gas phase thermochemistry data, Condensed phase 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:
B - John E. Bartmess
MM - Michael M. Meot-Ner (Mautner)
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 C₉H₈⁺ (ion structure unspecified)

Quantity	Value	Units	Method	Reference	Comment
IE (evaluated)	8.14 ± 0.01	eV	N/A	N/A	L
Quantity	Value	Units	Method	Reference	Comment
Proton affinity (review)	848.8	kJ/mol	N/A	Hunter and Lias, 1998	HL
Quantity	Value	Units	Method	Reference	Comment
Gas basicity	819.6	kJ/mol	N/A	Hunter and Lias, 1998	HL

Electron affinity determinations

EA (eV)	Method	Reference	Comment
<0.173 ± 0.026	ECD	Wojnarovits and Foldiak, 1981	EA is an upper limit: Chen and Wentworth, 1989; G3MP2B3 calculations indicate an EA of ca. -0.6 eV, unbound anion.; B

Proton affinity at 298K

Proton affinity (kJ/mol)	Reference	Comment
848.5	Aue, Guidoni, et al., 2000	Experimental literature data re-evaluated by the authors using ab initio protonation entropies; MM

Gas basicity at 298K

Gas basicity (review) (kJ/mol)	Reference	Comment
819.2	Aue, Guidoni, et al., 2000	Experimental literature data re-evaluated by the authors using ab initio protonation entropies; MM

Ionization energy determinations

IE (eV)	Method	Reference	Comment
8.33 ± 0.01	EI	Rakita, Hoffman, et al., 1973	LLK
8.14 ± 0.01	PE	Dewar, Haselbach, et al., 1970	RDSH
8.62	EI	Occolowitz and White, 1968	RDSH
8.13 ± 0.05	PE	Eland and Danby, 1968	RDSH
8.15 ± 0.015	PE	Gusten, Klasinc, et al., 1976	Vertical value; LLK

Appearance energy determinations

Ion	AE (eV)	Other Products	Method	Reference	Comment
C₉H₇⁺	12.62 ± 0.05	H	EI	Schwarz and Bohlmann, 1973	LLK
C₉H₇⁺	12.53	H	EI	Occolowitz and White, 1968	RDSH

De-protonation reactions

+ = Indene

By formula: C₉H₇^- + H⁺ = C₉H₈

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	1482. ± 10.	kJ/mol	TDEq	Meot-ner, Liebman, et al., 1988	gas phase; anchored to 88MEO scale, not the "87 acidity scale". The Kiefer, Zhang, et al., 1997 BDE is for ortho.; B
Δ_rH°	1472. ± 8.8	kJ/mol	G+TS	Taft and Bordwell, 1988	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	1451. ± 8.4	kJ/mol	TDEq	Meot-ner, Liebman, et al., 1988	gas phase; anchored to 88MEO scale, not the "87 acidity scale". The Kiefer, Zhang, et al., 1997 BDE is for ortho.; B
Δ_rG°	1442. ± 8.4	kJ/mol	IMRE	Taft and Bordwell, 1988	gas phase; B

References

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

Roux, Temprado, et al., 2008
Roux, M.V.; Temprado, M.; Chickos, J.S.; Nagano, Y., Critically Evaluated Thermochemical Properties of Polycyclic Aromatic Hydrocarbons, J. Phys. Chem. Ref. Data, 2008, 37, 4, 1855-1996. [all data]

Klots T.D., 1995
Klots T.D., Vibrational spectra of indene. Part 4. Calibration, assignment, and ideal gas thermodynamics, Spectrochim. Acta, 1995, A51, 2307-2324. [all data]

Dorofeeva O.V., 1986
Dorofeeva O.V., Thermodynamic properties of twenty-one monocyclic hydrocarbons, J. Phys. Chem. Ref. Data, 1986, 15, 437-464. [all data]

Stull, Sinke, et al., 1961
Stull, D.R.; Sinke, G.C.; McDonald, R.A.; Hatton, W.E.; Hildenbrand, D.L., Thermodynamic properties of indane and indene, Pure & Appl. Chem., 1961, 2, 315-322. [all data]

Stull, Sinke, et al., 1959
Stull, D.R.; Sinke, G.C.; McDonald, R.A.; Hatton, W.E.; Hildenbrand, D.L., Thermodynamic properties of indane and indene, Symposium uber Thermodynamik, 1959, 1-9. [all data]

Stull, Sinke, et al., 1959, 2
Stull, D.R.; Sinke, G.C.; McDonald, R.A.; Hatton, W.E.; Hildenbrand, D.L., Thermodynamic properties of indane and indene, Symp. Thermodynam. Fritens-Wattens, Tirol Austria, 1959, No. 48, 9p. [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]

Wojnarovits and Foldiak, 1981
Wojnarovits, L.; Foldiak, G., Electron capture detection of aromatic hydrocarbons, J. Chromatogr. Sci., 1981, 206, 511. [all data]

Chen and Wentworth, 1989
Chen, E.C.M.; Wentworth, W.E., Experimental Determination of Electron Affinities of Organic Molecules, Mol. Cryst. Liq. Cryst., 1989, 171, 271. [all data]

Aue, Guidoni, et al., 2000
Aue, D.H.; Guidoni, M.; Betowski, L.D., Ab initio calculated gas-phase basicities of polynuclear aromatic hydrocarbons, Int. J. Mass Spectrom., 2000, 201, 283. [all data]

Rakita, Hoffman, et al., 1973
Rakita, P.E.; Hoffman, M.K.; Andrews, M.N.; Bursey, M.M., σ-π Conjugation in group IVA compounds of indene and indane, J. Organomet. Chem., 1973, 49, 213. [all data]

Dewar, Haselbach, et al., 1970
Dewar, M.J.S.; Haselbach, E.; Worley, S.D., Calculated and observed ionization potentials of unsaturated polycyclic hydrocarbons; calculated heats of formation by several semiempirical s.c.f. m.o. methods, Proc. Roy. Soc. (London), 1970, A315, 431. [all data]

Occolowitz and White, 1968
Occolowitz, J.L.; White, G.L., Energetic considerations in the assignment of some fragment ion structures, Australian J. Chem., 1968, 21, 997. [all data]

Eland and Danby, 1968
Eland, J.H.D.; Danby, C.J., Inner ionization potentials of aromatic compounds, Z. Naturforsch., 1968, 23a, 355. [all data]

Gusten, Klasinc, et al., 1976
Gusten, H.; Klasinc, L.; Ruscic, B., Photoelectron spectroscopy of J. Heterocycl. Chem.. Indene analogs, Z. Naturforsch. A:, 1976, 31, 1051. [all data]

Schwarz and Bohlmann, 1973
Schwarz, H.; Bohlmann, F., Elektronenstossinduzierte fragmentierung von acetylenverbindungen. VI. Struktur und bildungsenthalpie der ionen [C₁₁H₉]⁺ und [C₉H₇]⁺, Org. Mass Spectrom., 1973, 7, 395. [all data]

Meot-ner, Liebman, et al., 1988
Meot-ner, M.; Liebman, J.F.; Kafafi, S.A., Ionic Probes of Aromaticity in Annelated Rings, J. Am. Chem. Soc., 1988, 110, 18, 5937, https://doi.org/10.1021/ja00226a001 . [all data]

Kiefer, Zhang, et al., 1997
Kiefer, J.H.; Zhang, Q.; Kern, R.D.; Yao, J.; Jursic, B., Pyrolysis of Aromatic Azines: Pyrazine, Pyrimidine, and Pyridine, J. Phys. Chem. A, 1997, 101, 38, 7061, https://doi.org/10.1021/jp970211z . [all data]

Taft and Bordwell, 1988
Taft, R.W.; Bordwell, F.G., Structural and Solvent Effects Evaluated from Acidities Measured in Dimethyl Sulfoxide and in the Gas Phase, Acc. Chem. Res., 1988, 21, 12, 463, https://doi.org/10.1021/ar00156a005 . [all data]

Notes

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

Symbols used in this document:

AE	Appearance energy
C_p,gas	Constant pressure heat capacity of gas
C_p,liquid	Constant pressure heat capacity of liquid
EA	Electron affinity
IE (evaluated)	Recommended ionization energy
S°_liquid	Entropy of liquid at standard conditions
Δ_cH°_liquid	Enthalpy of combustion of liquid at standard conditions
Δ_fH°_gas	Enthalpy of formation of gas at standard conditions
Δ_fH°_liquid	Enthalpy of formation of liquid 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
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