Tetracarbon

Formula: C₄
Molecular weight: 48.0428
IUPAC Standard InChI: InChI=1S/C4/c1-3-2-4(1)3
IUPAC Standard InChIKey: BEMJFDKMIISOFB-UHFFFAOYSA-N
CAS Registry Number: 12184-80-4
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.
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Data at other public NIST sites:
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Gas phase thermochemistry data

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

Quantity	Value	Units	Method	Reference	Comment
Δ_fH°_gas	970.69	kJ/mol	Review	Chase, 1998	Data last reviewed in December, 1969
Quantity	Value	Units	Method	Reference	Comment
S°_{gas,1 bar}	228.32	J/mol*K	Review	Chase, 1998	Data last reviewed in December, 1969

Gas Phase Heat Capacity (Shomate Equation)

C_p° = A + B*t + C*t² + D*t³ + E/t²
H° − H°_298.15= A*t + B*t²/2 + C*t³/3 + D*t⁴/4 − E/t + F − H
S° = A*ln(t) + B*t + C*t²/2 + D*t³/3 − E/(2*t²) + G
C_p = heat capacity (J/mol*K)
H° = standard enthalpy (kJ/mol)
S° = standard entropy (J/mol*K)
t = temperature (K) / 1000.

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Temperature (K)	298. to 1200.	1200. to 6000.
A	34.86640	84.02309
B	84.34818	1.746470
C	-55.64804	-0.340843
D	13.82762	0.022954
E	-0.468144	-8.928448
F	955.4373	924.1703
G	245.0837	300.4342
H	970.6880	970.6880
Reference	Chase, 1998	Chase, 1998
Comment	Data last reviewed in December, 1969	Data last reviewed in December, 1969

Gas phase ion energetics data

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

Data compiled as indicated in comments:
LL - Sharon G. Lias and Joel F. Liebman
RDSH - Henry M. Rosenstock, Keith Draxl, Bruce W. Steiner, and John T. Herron
B - John E. Bartmess

View reactions leading to C₄⁺ (ion structure unspecified)

Electron affinity determinations

EA (eV)	Method	Reference	Comment
3.882 ± 0.010	LPES	Arnold, Bradforth, et al., 1991	Linear structure for both anion and neutral. Bound state 37.063 kcal/mol up: Zhao, de Beer, et al., 1996; B
3.70 ± 0.10	LPES	Yang, Taylor, et al., 1989	EA given is Vertical Detachment Energy. probably linear structure.; B
2.10 ± 0.10	LPD	Vager, Feldman, et al., 1991	Cyclic isomer, by Coulomb explosion, Zhao, de Beer, et al., 1996 claims hot ions are the source.; B

Ionization energy determinations

IE (eV)	Method	Reference	Comment
12.54 ± 0.35	PE	Ramathan, Zimmerman, et al., 1993	LL
12.6	EI	Drowart, Burns, et al., 1959	RDSH

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: ³S_u^-

Energy (cm^-1)	Med.	Transition	λ_min (nm)	λ_max (nm)	References


T_o = 26384.9 ± 0.2	gas	³S_u--X	334	379	Linnartz, Vaizert, et al., 2000
T_o = 26323 ± 15	Ne	³S_u--X	325	380	Freivogel, Grutter, et al., 1996

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


Σ_g⁺	1	Sym. stretch	1821		gas	CR	Linnartz, Vaizert, et al., 2000
	1	Sym. stretch	1822 ± 20		Ne	AB	Freivogel, Grutter, et al., 1996
	2	C-C stretch	869		gas	CR	Linnartz, Vaizert, et al., 2000
	2	C-C stretch	903 ± 20		Ne	AB	Freivogel, Grutter, et al., 1996
Π_g	4	Bend	370 ± 20	H	Ne	AB	Freivogel, Grutter, et al., 1996
Π_u	5	Bend	175 ± 20	H	Ne	AB	Freivogel, Grutter, et al., 1996

State: ¹Π_g

Energy (cm^-1)	Med.	References


T_o = 11380	gas	Xu, Burton, et al., 1997

State: ¹Π_u

Energy (cm^-1)		Med.	References


T_o = 9360 ± 160	T	gas	Xu, Burton, et al., 1997

State: ³Π_u

Energy (cm^-1)	Med.	References


T = 7500 ± 160	gas	Xu, Burton, et al., 1997

State: 3Og

Energy (cm^-1)	Med.	References


T = 6620 ± 160	gas	Xu, Burton, et al., 1997

State: ¹S_g⁺

Energy (cm^-1)		Med.	References


T_o = 4030 ± 160	T	gas	Xu, Burton, et al., 1997

State: ¹D_g

Energy (cm^-1)	Med.	References


T_o = 2680 ± 120	gas	Arnold, Bradforth, et al., 1991
		Xu, Burton, et al., 1997

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


Σ_g⁺	1	Sym. stretch	2032 ± 50	gas	PE	Xu, Burton, et al., 1997
Π_g	4	Bend	331 ± 50	gas	PE	Xu, Burton, et al., 1997

State: X

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


Σ_g⁺	1	Sym. stretch	2057 ± 50	gas	PE	Arnold, Bradforth, et al., 1991 Xu, Burton, et al., 1997
Σ_u	3	Asym. stretch	1548.61	gas	DL	Heath and Saykally, 1991
	3	Asym. stretch	1547.0	Ne	IR	Smith, Agreiter, et al., 1994 Forney, Jacox, et al., 1995 Tam, Macler, et al., 1997 Wu, Chen, et al., 2009
	3	Asym. stretch	1543.4	Ar	IR	Shen and Graham, 1989
	3	Asym. stretch	1539.5	Kr	IR	Szczepanski, Ekern, et al., 1996
Π_g	4	Bend	352 ± 15	gas	PE DL	Arnold, Bradforth, et al., 1991 Moazzen-Ahmadi and Thong, 1995 Xu, Burton, et al., 1997 Gakwaya, Abusara, et al., 2004
Π_u	5	Bend	160 ± 4	gas	DL	Moazzen-Ahmadi, Thong, et al., 1994
	5	Bend	172.4	Ar	IR	Withey, Shen, et al., 1991
	5	Bend	170.4	Ar	IR	Withey, Shen, et al., 1991

Additional references: Jacox, 1994, page 181; Jacox, 1998, page 245; Jacox, 2003, page 214; Cheung and Graham, 1989; Jiang and Graham, 1991

Notes

(1/2)(2ν)

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

Chase, 1998
Chase, M.W., Jr., NIST-JANAF Themochemical Tables, Fourth Edition, J. Phys. Chem. Ref. Data, Monograph 9, 1998, 1-1951. [all data]

Arnold, Bradforth, et al., 1991
Arnold, D.W.; Bradforth, S.E.; Kitsopoulos, T.N.; Neumark, D.M., Vibrationally Resolved Spectra of C2-C11 by Anion Photoelectron Spectroscopy, J. Chem. Phys., 1991, 95, 12, 8753, https://doi.org/10.1063/1.461211 . [all data]

Zhao, de Beer, et al., 1996
Zhao, Y.; de Beer, E.; Xu, C.; Taylor, T.; Neumark, D.M., Spectroscopy and Electron Detachment Dynamics of C4-, C6- and C8-, J. Chem. Phys., 1996, 105, 12, 4905, https://doi.org/10.1063/1.472341 . [all data]

Yang, Taylor, et al., 1989
Yang, S.; Taylor, K.J.; Craycraft, M.J.; Conceicao, J.; Pettiette, C.L.; Cherhnovsky, O.; Smalley, R.E., UPS of 2-30 Atom Carbon Clusters: Chains and Rings, Chem. Phys. Lett., 1989, 144, 5-6, 431, https://doi.org/10.1016/0009-2614(88)87291-9 . [all data]

Vager, Feldman, et al., 1991
Vager, Z.; Feldman, H.; Kella, D.; Malkin, E.; Miklazky, E.; Zajfman, J.; Naaman, R., The Structure of Small Carbon Clusters, Z. Phys. D, 1991, 19, 1-4, 413, https://doi.org/10.1007/BF01448341 . [all data]

Ramathan, Zimmerman, et al., 1993
Ramathan, R.; Zimmerman, J.A.; Eyler, J.R., Ionization potentials of small carbon clusters, J. Chem. Phys., 1993, 98, 7838. [all data]

Drowart, Burns, et al., 1959
Drowart, J.; Burns, R.P.; DeMaria, G.; Inghram, M.G., Mass spectrometric study of carbon vapor, J. Chem. Phys., 1959, 31, 1131. [all data]

Linnartz, Vaizert, et al., 2000
Linnartz, H.; Vaizert, O.; Motylewski, T.; Maier, J.P., The [sup 3]Σ[sub u][sup -]←X [sup 3]Σ[sub g][sup -] electronic spectrum of linear C[sub 4] in the gas phase, J. Chem. Phys., 2000, 112, 22, 9777, https://doi.org/10.1063/1.481615 . [all data]

Freivogel, Grutter, et al., 1996
Freivogel, P.; Grutter, M.; Forney, D.; Maier, J.P., The 3Σu- ← X3Σg- electronic absorption spectrum of linear C4 in a neon matrix, Chem. Phys. Lett., 1996, 249, 3-4, 191, https://doi.org/10.1016/0009-2614(95)01391-1 . [all data]

Xu, Burton, et al., 1997
Xu, C.; Burton, G.R.; Taylor, T.R.; Neumark, D.M., Photoelectron spectroscopy of C[sub 4][sup -], C[sub 6][sup -], and C[sub 8][sup -], J. Chem. Phys., 1997, 107, 9, 3428, https://doi.org/10.1063/1.474715 . [all data]

Heath and Saykally, 1991
Heath, J.R.; Saykally, R.J., The structure of the C4 cluster radical, J. Chem. Phys., 1991, 94, 4, 3271, https://doi.org/10.1063/1.459797 . [all data]

Smith, Agreiter, et al., 1994
Smith, A.M.; Agreiter, J.; Hartle, M.; Engel, C.; Bondybey, V.E., Rare gas matrix studies of absorption and fluorescence of reactive intermediates formed in discharges through acetylene, Chem. Phys., 1994, 189, 2, 315, https://doi.org/10.1016/0301-0104(94)00299-1 . [all data]

Forney, Jacox, et al., 1995
Forney, D.; Jacox, M.E.; Thompson, W.E., The Infrared and Near-Infrared Spectra of HCC and DCC Trapped in Solid Neon, J. Mol. Spectrosc., 1995, 170, 1, 178, https://doi.org/10.1006/jmsp.1995.1065 . [all data]

Tam, Macler, et al., 1997
Tam, S.; Macler, M.; Fajardo, M.E., Matrix isolation spectroscopy of laser ablated carbon species in Ne, D[sub 2], and H[sub 2] matrices, J. Chem. Phys., 1997, 106, 22, 8955, https://doi.org/10.1063/1.474028 . [all data]

Wu, Chen, et al., 2009
Wu, Y.-J.; Chen, H.-F.; Camacho, C.; Sitek, H.A.; Hsu, S.-C.; Lin, M.-Y.; Chou, S.-L.; Ogilvie, J.F.; Cheng, B.-M., FORMATION AND IDENTIFICATION OF INTERSTELLAR MOLECULE LINEAR C, Astrophys. J., 2009, 701, 1, 8, https://doi.org/10.1088/0004-637X/701/1/8 . [all data]

Shen and Graham, 1989
Shen, L.N.; Graham, W.R.M., Observation of an infrared frequency of the C4 molecule, J. Chem. Phys., 1989, 91, 8, 5115, https://doi.org/10.1063/1.457603 . [all data]

Szczepanski, Ekern, et al., 1996
Szczepanski, J.; Ekern, S.; Chapo, C.; Vala, M., Infrared spectroscopy of matrix-isolated carbon clusters, with emphasis on C8 and C9, Chem. Phys., 1996, 211, 1-3, 359, https://doi.org/10.1016/0301-0104(96)00212-1 . [all data]

Moazzen-Ahmadi and Thong, 1995
Moazzen-Ahmadi, N.; Thong, J.J., Infrared diode laser spectroscopy of C4. The ν3 + ν4 - ν4 sequence band, Chem. Phys. Lett., 1995, 233, 4, 471, https://doi.org/10.1016/0009-2614(94)01467-A . [all data]

Gakwaya, Abusara, et al., 2004
Gakwaya, S.; Abusara, Z.; Moazzen-Ahmadi, N., Vibrational hot bands of linear C4 and C5 arising from a bending vibration with two quanta in the lowest bend: the (ν3+2ν5)-2ν5 band of C4 and the (ν3+2ν7)-2ν7 band of C5, Chem. Phys. Lett., 2004, 398, 4-6, 564, https://doi.org/10.1016/j.cplett.2004.09.130 . [all data]

Moazzen-Ahmadi, Thong, et al., 1994
Moazzen-Ahmadi, N.; Thong, J.J.; McKellar, A.R.W., Infrared diode laser spectroscopy of the ν3 fundamental and ν3+ν5-ν5 sequence bands of the C4 radical in a hollow cathode discharge, J. Chem. Phys., 1994, 100, 6, 4033, https://doi.org/10.1063/1.466340 . [all data]

Withey, Shen, et al., 1991
Withey, P.A.; Shen, L.N.; Graham, W.R.M., Fourier transform far infrared spectroscopy of a C4 bending mode, J. Chem. Phys., 1991, 95, 2, 820, https://doi.org/10.1063/1.461088 . [all data]

Jacox, 1994
Jacox, M.E., Vibrational and electronic energy levels of polyatomic transient molecules, American Chemical Society, Washington, DC, 1994, 464. [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]

Cheung and Graham, 1989
Cheung, H.M.; Graham, W.R.M., Electron-spin-resonance characterization of nonlinear C4 trapped in solid argon, J. Chem. Phys., 1989, 91, 11, 6664, https://doi.org/10.1063/1.457385 . [all data]

Jiang and Graham, 1991
Jiang, Q.; Graham, W.R.M., Electron-paramagnetic-resonance study of the structure of C4 in solid Ne, J. Chem. Phys., 1991, 95, 5, 3129, https://doi.org/10.1063/1.460870 . [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

S°_{gas,1 bar} Entropy of gas at standard conditions (1 bar)

Δ_fH°_gas Enthalpy of formation of gas at standard conditions
Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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EA	Electron affinity
S°_{gas,1 bar}	Entropy of gas at standard conditions (1 bar)
Δ_fH°_gas	Enthalpy of formation of gas at standard conditions

Tetracarbon

Gas phase thermochemistry data

Gas Phase Heat Capacity (Shomate Equation)

Gas phase ion energetics data

Electron affinity determinations

Ionization energy determinations

Vibrational and/or electronic energy levels

State: 3Su-

State: 1Πg

State: 1Πu

State: 3Πu

State: 3Og

State: 1Sg+

State: 1Dg

State: X

Notes

References

Notes

State: ³S_u^-

State: ¹Π_g

State: ¹Π_u

State: ³Π_u

State: ¹S_g⁺

State: ¹D_g