Cyclobutadiene

• Formula: C₄H₄
• Molecular weight: 52.0746
• IUPAC Standard InChI: InChI=1S/C4H4/c1-2-4-3-1/h1-4H Copy

  
• IUPAC Standard InChIKey: HWEQKSVYKBUIIK-UHFFFAOYSA-N Copy
• CAS Registry Number: 1120-53-2
• Chemical structure:
  This structure is also available as a 2d Mol file or as a computed 3d SD file
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• Information on this page:
  • Gas phase ion energetics data
  • Vibrational and/or electronic energy levels
  • References
  • Notes
• Other data available:
  • Gas phase thermochemistry data
• Data at other public NIST sites:
  • Gas Phase Kinetics Database
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Gas phase ion energetics data

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Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

Data compiled as indicated in comments:
LL - Sharon G. Lias and Joel F. Liebman
LBLHLM - Sharon G. Lias, John E. Bartmess, Joel F. Liebman, John L. Holmes, Rhoda D. Levin, and W. Gary Mallard
RDSH - Henry M. Rosenstock, Keith Draxl, Bruce W. Steiner, and John T. Herron

View reactions leading to C₄H₄⁺ (ion structure unspecified)

Ionization energy determinations

Vibrational and/or electronic energy levels

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Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

Data compiled by: Marilyn E. Jacox

State:   X

Additional references: Jacox, 1994, page 378; Jacox, 1998, page 338; Jacox, 2003, page 355

Notes

References

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

Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

Kohn and Chen, 1993
Kohn, D.W.; Chen, P., Vibrational structure in the photoelectron spectrum of cyclobutadiene as a probe of structure, J. Am. Chem. Soc., 1993, 115, 2844. [all data]

Li and McGee, 1969
Li, P.H.; McGee, H.A., Jr., Mass spectrum and ionization potential of condensed cyclobutadiene, Chem. Commun., 1969, 592. [all data]

Hedaya, Miller, et al., 1969
Hedaya, E.; Miller, R.D.; McNeil, D.W.; D'Angelo, P.F.; Schissel, P., Flash vacuum pyrolysis. V. Cyclobutadiene, J. Am. Chem. Soc., 1969, 91, 1875. [all data]

Dewar and Worley, 1969
Dewar, M.J.S.; Worley, S.D., Photoelectron spectra of molecules. I. Ionization potentials of some organic molecules and their interpretation, J. Chem. Phys., 1969, 50, 654. [all data]

Kreile, Munzel, et al., 1986
Kreile, J.; Munzel, N.; Schweig, A.; Specht, H., UV Photoelectron spectrum of cyclobutadiene. Free cyclobutadiene stable up to high temperatures, Chem. Phys. Lett., 1986, 124, 140. [all data]

Arnold, Radziszewski, et al., 1991
Arnold, B.R.; Radziszewski, J.G.; Campion, A.; Perry, S.S.; Michl, J., The Raman spectrum of matrix-isolated cyclobutadiene. Evidence for environmental hindrance to heavy-atom tunneling?, J. Am. Chem. Soc., 1991, 113, 2, 692, https://doi.org/10.1021/ja00002a058 . [all data]

Maier, 1988
Maier, G., Tetrahedran und Cyclobutadien, Angew. Chem., 1988, 100, 3, 317, https://doi.org/10.1002/ange.19881000304 . [all data]

Orendt, Arnold, et al., 1988
Orendt, A.M.; Arnold, B.R.; Radziszewski, J.G.; Facelli, J.C.; Malsch, K.D.; Strub, H.; Grant, D.M.; Michl, J., Carbon-13 NMR and polarized IR spectra of vicinally labeled cyclobutadiene-13C2 in an argon matrix: interconversion of valence tautomers, J. Am. Chem. Soc., 1988, 110, 8, 2648, https://doi.org/10.1021/ja00216a049 . [all data]

Arnold and Michl, 1993
Arnold, B.R.; Michl, J., Ultraviolet and polarized infrared spectroscopy of matrix-isolated cyclobutadiene and its isotopomers, J. Phys. Chem., 1993, 97, 50, 13348, https://doi.org/10.1021/j100152a046 . [all data]

Masamune, Souto-Bachiller, et al., 1978
Masamune, S.; Souto-Bachiller, F.A.; Machiguchi, T.; Bertie, J.E., Cyclobutadiene is not square, J. Am. Chem. Soc., 1978, 100, 15, 4889, https://doi.org/10.1021/ja00483a043 . [all data]

Chapman, McIntosh, et al., 1973
Chapman, O.L.; McIntosh, C.L.; Pacansky, J., Photochemical transformations. XLVIII. Cyclobutadiene, J. Am. Chem. Soc., 1973, 95, 2, 614, https://doi.org/10.1021/ja00783a066 . [all data]

Lin and Krantz, 1972
Lin, C.Y.; Krantz, A., J. Chem. Soc., 1972, Chem. Commun. 1111. [all data]

Maier, Hartan, et al., 1976
Maier, G.; Hartan, H.-G.; Sayrac, T., Cyclobutadien --- ein quadratisches Singulett-Molekül?, Angew. Chem., 1976, 88, 8, 252, https://doi.org/10.1002/ange.19760880805 . [all data]

Maier and Lautz
Maier, G.; Lautz, C., Eur. J. Org. Chem. 1998, 769.. [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]

Notes

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• Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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