m-Benzyne

Formula: C₆H₄
Molecular weight: 76.0960
CAS Registry Number: 1828-89-3
Information on this page:
Options:
- Switch to SI units

Gas phase thermochemistry data

Go To: Top, Gas phase ion energetics data, Vibrational and/or electronic energy levels, References, Notes

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

Quantity	Value	Units	Method	Reference	Comment
Δ_fH°_gas	116. ± 3.	kcal/mol	Ion	Wenthold, Paulino, et al., 1991	collision-induced dissociation

Gas phase ion energetics data

Go To: Top, Gas phase thermochemistry data, Vibrational and/or electronic energy levels, References, Notes

Data compiled by: John E. Bartmess

View reactions leading to C₆H₄⁺ (ion structure unspecified)

Electron affinity determinations

EA (eV)	Method	Reference	Comment
0.846 ± 0.013	CIDT	Wenthold, Hu, et al., 1996	Triplet state 21.0±0.3 kcal/mol up.
<0.990003	LPES	Wenthold, Squires, et al., 1998

Vibrational and/or electronic energy levels

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

Data compiled by: Marilyn E. Jacox

State: a

Energy (cm^-1)	Med.	References


T_o = 7350 ± 110	gas	Wenthold, Squires, et al., 1998, 2

Vib. sym.	cm^-1	Med.	Method	References


a₁	970 ± 15	gas	PE	Wenthold, Squires, et al., 1998, 2

State: X

Vib. sym.	No.	Approximate type of mode	cm^-1		Med.	Method	References


a₁	1	CH stretch	3037	w	Ar	IR	Marquardt, Sander, et al., 1996
	4	Mixed	1402	w m	Ar	IR	Marquardt, Sander, et al., 1996 Sander, Exner, et al., 2002
	9	Ring deform.	300	T	gas	PE	Wenthold, Squires, et al., 1998, 2
	9	Ring deform.	367	T	Ar	IR	Sander, Exner, et al., 2002
b₁	13	CH OPLA	824	w m	Ar	IR	Marquardt, Sander, et al., 1996 Sander, Exner, et al., 2002
	14	CH OPLA	751	m s	Ar	IR	Marquardt, Sander, et al., 1996 Sander, Exner, et al., 2002
	15	Ring deform.	561	w m	Ar	IR	Sander, Exner, et al., 2002
	16	Ring deform.	362	T	Ar	IR	Sander, Exner, et al., 2002
b₂	18	Mixed	1486	w m	Ar	IR	Marquardt, Sander, et al., 1996 Sander, Exner, et al., 2002
	23	HCC deform.	936	m	Ar	IR	Marquardt, Sander, et al., 1996 Sander, Exner, et al., 2002
	24	Ring deform.	547	vs	Ar	IR	Marquardt, Sander, et al., 1996 Sander, Exner, et al., 2002

Additional references: Jacox, 1998, page 346; Jacox, 2003, page 365

Notes

Weak

Medium

Strong

Very strong

Tentative assignment or approximate value

Energy separation between the v = 0 levels of the excited and electronic ground states.

References

Go To: Top, Gas phase thermochemistry data, Gas phase ion energetics data, Vibrational and/or electronic energy levels, Notes

Wenthold, Paulino, et al., 1991
Wenthold, P.G.; Paulino, J.A.; Squires, R.R., The absolute heats of formation of o-,m-, and p-benzyne, J. Am. Chem. Soc., 1991, 113, 7414-7415. [all data]

Wenthold, Hu, et al., 1996
Wenthold, P.G.; Hu, J.; Squires, R.R., o-, m-, and p-Benzyne Negative Ions in the Gas Phase: Synthesis, Authentication, and Thermochemistry, J. Am. Chem. Soc., 1996, 118, 47, 11865, https://doi.org/10.1021/ja960663+ . [all data]

Wenthold, Squires, et al., 1998
Wenthold, P.G.; Squires, R.R.; Lineberger, W.C., Ultraviolet photoelectron spectroscopy of the o-, m-, and p-benzyne negative ions. Electron affinities and singlet-triplet splittings for o-, m-, and p-benzyne, J. Am. Chem. Soc., 1998, 120, 21, 5279-5290, https://doi.org/10.1021/ja9803355 . [all data]

Wenthold, Squires, et al., 1998, 2
Wenthold, P.G.; Squires, R.R.; Lineberger, W.C., Ultraviolet Photoelectron Spectroscopy of the, J. Am. Chem. Soc., 1998, 120, 21, 5279, https://doi.org/10.1021/ja9803355 . [all data]

Marquardt, Sander, et al., 1996
Marquardt, R.; Sander, W.; Kraka, E., 1, 3-Didehydrobenzol (meta-Benzin), Angew. Chem., 1996, 108, 7, 825, https://doi.org/10.1002/ange.19961080719 . [all data]

Sander, Exner, et al., 2002
Sander, W.; Exner, M.; Winkler, M.; Balster, A.; Hjerpe, A.; Kraka, E.; Cremer, D., Vibrational Spectrum of, J. Am. Chem. Soc., 2002, 124, 44, 13072, https://doi.org/10.1021/ja012686g . [all data]

Jacox, 1998
Jacox, M.E., Vibrational and electronic energy levels of polyatomic transient molecules: supplement A, J. Phys. Chem. Ref. Data, 1998, 27, 2, 115-393, https://doi.org/10.1063/1.556017 . [all data]

Jacox, 2003
Jacox, M.E., Vibrational and electronic energy levels of polyatomic transient molecules: supplement B, J. Phys. Chem. Ref. Data, 2003, 32, 1, 1-441, https://doi.org/10.1063/1.1497629 . [all data]

Notes

Go To: Top, Gas phase thermochemistry data, Gas phase ion energetics data, Vibrational and/or electronic energy levels, References

Symbols used in this document:

EA Electron affinity

Δ_fH°_gas Enthalpy of formation of gas 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.

EA	Electron affinity
Δ_fH°_gas	Enthalpy of formation of gas at standard conditions