1,3-Diazine

• Formula: C₄H₄N₂
• Molecular weight: 80.0880
• IUPAC Standard InChI:
  

  InChI=1S/C4H4N2/c1-2-5-4-6-3-1/h1-4H Download the identifier in a file.

• IUPAC Standard InChIKey: CZPWVGJYEJSRLH-UHFFFAOYSA-N
• CAS Registry Number: 289-95-2
• 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: Pyrimidine; m-Diazine; Metadiazine; Miazine; 1,3-Diazabenzene; Py; Pyr
• Permanent link for this species. Use this link for bookmarking this species for future reference.
• Information on this page:
  • Gas phase thermochemistry data
  • Condensed phase thermochemistry data
  • Phase change data
  • Reaction thermochemistry data
  • IR Spectrum
  • Mass spectrum (electron ionization)
  • References
  • Notes
• Other data available:
  • Gas phase ion energetics data
  • Ion clustering data
  • UV/Visible spectrum
  • Gas Chromatography
• Data at other public NIST sites:
  • Computational Chemistry Comparison and Benchmark Database
  • Gas Phase Kinetics Database
• Options:
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Gas phase thermochemistry data

Go To: Top, Condensed phase thermochemistry data, Phase change data, Reaction thermochemistry data, IR Spectrum, Mass spectrum (electron ionization), References, Notes

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

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

Quantity	Value	Units	Method	Reference	Comment
fH°gas	46.80 ± 0.36	kcal/mol	Ccr	Nabavian, Sabbah, et al., 1977	Reanalyzed by Pedley, Naylor, et al., 1986, Original value = 46.15 ± 0.47 kcal/mol
fH°gas	46.83 ± 0.33	kcal/mol	Ccb	Tjebbes, 1962	Reanalyzed by Cox and Pilcher, 1970, Original value = 46.99 ± 0.24 kcal/mol

Condensed phase thermochemistry data

Go To: Top, Gas phase thermochemistry data, Phase change data, Reaction thermochemistry data, IR Spectrum, Mass spectrum (electron ionization), References, Notes

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

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

Quantity	Value	Units	Method	Reference	Comment
fH°liquid	34.23 ± 0.44	kcal/mol	Ccr	Nabavian, Sabbah, et al., 1977
fH°liquid	35.04 ± 0.20	kcal/mol	Ccb	Tjebbes, 1962
Quantity	Value	Units	Method	Reference	Comment
cH°liquid	-547.06 ± 0.42	kcal/mol	Ccr	Nabavian, Sabbah, et al., 1977
cH°liquid	-547.88 ± 0.20	kcal/mol	Ccb	Tjebbes, 1962

Phase change 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:
BS - Robert L. Brown and Stephen E. Stein
AC - William E. Acree, Jr., James S. Chickos
ALS - Hussein Y. Afeefy, Joel F. Liebman, and Stephen E. Stein
DRB - Donald R. Burgess, Jr.

Quantity	Value	Units	Method	Reference	Comment
Tboil	396.7	K	N/A	Weast and Grasselli, 1989	BS
Quantity	Value	Units	Method	Reference	Comment
vapH°	12. ± 2.	kcal/mol	AVG	N/A	Average of 7 values; Individual data points

Reaction thermochemistry 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:
MS - José A. Martinho Simões
B - John E. Bartmess
RCD - Robert C. Dunbar

Note: Please consider using the reaction search for this species. This page allows searching of all reactions involving this species. A general reaction search form is also available. Future versions of this site may rely on reaction search pages in place of the enumerated reaction displays seen below.

Individual Reactions

C₁₀H₅CrNO₅ (solution) +  (solution) =  (solution) +  (solution)

By formula: C₁₀H₅CrNO₅ (solution) + CO (solution) = C₆CrO₆ (solution) + C₄H₄N₂ (solution)

Quantity	Value	Units	Method	Reference	Comment
rH°	-14.8	kcal/mol	KinS	Wovkulich and Atwood, 1980	solvent: Hexane; The data rely on the enthalpy and entropy of activation for the forward reaction, 25.4 ± 1.1 kcal/mol and 13.0±14.6 J/(mol K) Dennenberg and Darensbourg, 1972, and also on the enthalpy and entropy of activation for the Cr-CO dissociation in Cr(CO)6, 40.20 ± 0.60 kcal/mol and 94.6±6.3 J/(mol K) Graham and Angelici, 1967. The latter data were obtained in decalin; MS

 (cr) +  (l) = C₁₀H₅NO₅W (cr) +  (g)

By formula: C₆O₆W (cr) + C₄H₄N₂ (l) = C₁₀H₅NO₅W (cr) + CO (g)

Quantity	Value	Units	Method	Reference	Comment
rH°	8.27	kcal/mol	N/A	Nakashima and Adamson, 1982	The reaction enthalpy was calculated from the enthalpy of the reaction W(CO)6(solution) + py(solution) = W(CO)5(py)(solution) + CO(solution) in cyclohexane, 6.55 ± 0.69 kcal/mol, together with the enthalpies of solution of W(CO)6(cr), W(CO)5(py)(cr), and py(l), 35.7, 36.4, and 1.9 kcal/mol, respectively Nakashima and Adamson, 1982.; MS

C₄H₃N₂^- +  =

By formula: C₄H₃N₂^- + H⁺ = C₄H₄N₂

Quantity	Value	Units	Method	Reference	Comment
rH°	385.2 ± 2.5	kcal/mol	TDEq	Meot-ner and Kafafi, 1988	gas phase; Acid: pyrimidine. Anchored to 88MEO scale, not "87 acidity scale; B
Quantity	Value	Units	Method	Reference	Comment
rG°	376.80 ± 0.70	kcal/mol	N/A	Wren, Vogelhuber, et al., 2012	gas phase; B
rG°	376.9 ± 2.0	kcal/mol	TDEq	Meot-ner and Kafafi, 1988	gas phase; Acid: pyrimidine. Anchored to 88MEO scale, not "87 acidity scale; B

 (solution) +  (solution) = C₁₀H₅NO₅W (solution) +  (solution)

By formula: C₆O₆W (solution) + C₄H₄N₂ (solution) = C₁₀H₅NO₅W (solution) + CO (solution)

Quantity	Value	Units	Method	Reference	Comment
rH°	6.55 ± 0.69	kcal/mol	PC	Nakashima and Adamson, 1982	solvent: Cyclohexane; MS
rH°	5.95 ± 0.69	kcal/mol	PC	Nakashima and Adamson, 1982	solvent: Benzene; MS
rH°	4.40 ± 0.1	kcal/mol	PC	Nakashima and Adamson, 1982	solvent: Tetrahydrofuran; MS

C₃₉H₆₈O₃P₂W (solution) +  (solution) = C₄₄H₇₁NO₃P₂W (solution) +  (g)

By formula: C₃₉H₆₈O₃P₂W (solution) + C₄H₄N₂ (solution) = C₄₄H₇₁NO₃P₂W (solution) + H₂ (g)

Quantity	Value	Units	Method	Reference	Comment
rH°	-9.49 ± 0.50	kcal/mol	RSC	Gonzalez, Zhang, et al., 1988	solvent: Toluene; MS
rH°	-9.99 ± 0.50	kcal/mol	RSC	Gonzalez, Zhang, et al., 1988	solvent: Tetrahydrofuran; MS

C₁₄H₁₀CrN₂O₄ (cr) = 2 (g) + 4 (g) +  (cr)

By formula: C₁₄H₁₀CrN₂O₄ (cr) = 2C₄H₄N₂ (g) + 4CO (g) + Cr (cr)

Quantity	Value	Units	Method	Reference	Comment
rH°	>47.6	kcal/mol	TD-HFC	Adedeji, Connor, et al., 1978	The reaction enthalpy is a low limit Adedeji, Connor, et al., 1978.; MS

C₈H₆MoO₃ (solution) + 3 (solution) = C₁₈H₁₅MoN₃O₃ (solution) +  (solution)

By formula: C₈H₆MoO₃ (solution) + 3C₄H₄N₂ (solution) = C₁₈H₁₅MoN₃O₃ (solution) + C₅H₆ (solution)

Quantity	Value	Units	Method	Reference	Comment
rH°	-16.7 ± 0.69	kcal/mol	RSC	Nolan, Hoff, et al., 1985	solvent: Pyridine; Reaction temperature: 323 K; MS

 +  = C₄H₄N₃O^-

By formula: NO^- + C₄H₄N₂ = C₄H₄N₃O^-

Quantity	Value	Units	Method	Reference	Comment
rH°	16.6 ± 2.3	kcal/mol	N/A	Le Barbu, Schiedt, et al., 2002	gas phase; Affinity is difference in EAs of lesser solvated species; B

C₉H₉CrN₃O₃ (solution) + 3 (solution) = C₁₈H₁₅CrN₃O₃ (solution) + 3 (solution)

By formula: C₉H₉CrN₃O₃ (solution) + 3C₄H₄N₂ (solution) = C₁₈H₁₅CrN₃O₃ (solution) + 3C₂H₃N (solution)

Quantity	Value	Units	Method	Reference	Comment
rH°	-11.5 ± 0.91	kcal/mol	RSC	Mukerjee, Lang, et al., 1992	solvent: Tetrahydrofuran; MS

C₇H₉Cl₂NPd (solution) +  (l) = (PdCl₂(C₅H₅N)₂) (solution) +  (solution)

By formula: C₇H₉Cl₂NPd (solution) + C₄H₄N₂ (l) = (PdCl₂(C₅H₅N)₂) (solution) + C₂H₄ (solution)

Quantity	Value	Units	Method	Reference	Comment
rH°	-13.8 ± 0.41	kcal/mol	RSC	Partenheimer and Durham, 1974	solvent: Dichloromethane; MS

C₁₀H₅NO₅W (cr) +  (g) =  (g) +  (g)

By formula: C₁₀H₅NO₅W (cr) + CO (g) = C₆O₆W (g) + C₄H₄N₂ (g)

Quantity	Value	Units	Method	Reference	Comment
rH°	20. ± 2.4	kcal/mol	DSC	Daamen, van der Poel, et al., 1979	Please also see Meester, Vriends, et al., 1976.; MS

C₁₂H₁₆CrO₅ (solution) +  (solution) =  (solution) + C₁₀H₅CrNO₅ (solution)

By formula: C₁₂H₁₆CrO₅ (solution) + C₄H₄N₂ (solution) = C₇H₁₆ (solution) + C₁₀H₅CrNO₅ (solution)

Quantity	Value	Units	Method	Reference	Comment
rH°	-20.1 ± 0.41	kcal/mol	PAC	Yang, Vaida, et al., 1988	solvent: Heptane; MS

C₃₉H₆₆MoO₃P₃ (solution) +  (solution) = C₄₄H₇₁MoNO₃P₂ (solution)

By formula: C₃₉H₆₆MoO₃P₃ (solution) + C₄H₄N₂ (solution) = C₄₄H₇₁MoNO₃P₂ (solution)

Quantity	Value	Units	Method	Reference	Comment
rH°	-16.9 ± 0.60	kcal/mol	RSC	Zhang, Gonzalez, et al., 1991	solvent: Toluene; MS

 (cr) + 3 (g) = C₁₈H₁₅MoN₃O₃ (cr) + 3 (g)

By formula: C₆MoO₆ (cr) + 3C₄H₄N₂ (g) = C₁₈H₁₅MoN₃O₃ (cr) + 3CO (g)

Quantity	Value	Units	Method	Reference	Comment
rH°	-12.0 ± 1.7	kcal/mol	HFC	Adedeji, Connor, et al., 1978	MS

 (cr) + 3 (g) = C₁₈H₁₅N₃O₃W (g) + 3 (g)

By formula: C₆O₆W (cr) + 3C₄H₄N₂ (g) = C₁₈H₁₅N₃O₃W (g) + 3CO (g)

Quantity	Value	Units	Method	Reference	Comment
rH°	-13.1 ± 2.0	kcal/mol	HFC	Adedeji, Connor, et al., 1978	MS

C₁₀H₅CrNO₅ (cr) +  (g) =  (g) +  (g)

By formula: C₁₀H₅CrNO₅ (cr) + CO (g) = C₆CrO₆ (g) + C₄H₄N₂ (g)

Quantity	Value	Units	Method	Reference	Comment
rH°	18. ± 1.	kcal/mol	DSC	Daamen, van der Poel, et al., 1979	MS

C₁₀H₅MoNO₅ (cr) +  (g) =  (g) +  (g)

By formula: C₁₀H₅MoNO₅ (cr) + CO (g) = C₆MoO₆ (g) + C₄H₄N₂ (g)

Quantity	Value	Units	Method	Reference	Comment
rH°	14. ± 0.7	kcal/mol	DSC	Daamen, van der Poel, et al., 1979	MS

 +  = (  )

By formula: Fe⁺ + C₄H₄N₂ = (Fe⁺  C₄H₄N₂)

Quantity	Value	Units	Method	Reference	Comment
rH°	47.5 ± 1.9	kcal/mol	CIDT	Amunugama and Rodgers, 2001	RCD

 +  = (  )

By formula: Cr⁺ + C₄H₄N₂ = (Cr⁺  C₄H₄N₂)

Quantity	Value	Units	Method	Reference	Comment
rH°	42.4 ± 1.5	kcal/mol	CIDT	Amunugama and Rodgers, 2001	RCD

 +  = (  )

By formula: Ti⁺ + C₄H₄N₂ = (Ti⁺  C₄H₄N₂)

Quantity	Value	Units	Method	Reference	Comment
rH°	51.1 ± 2.5	kcal/mol	CIDT	Amunugama and Rodgers, 2001	RCD

 +  = (  )

By formula: Mn⁺ + C₄H₄N₂ = (Mn⁺  C₄H₄N₂)

Quantity	Value	Units	Method	Reference	Comment
rH°	38.0 ± 2.3	kcal/mol	CIDT	Amunugama and Rodgers, 2001	RCD

 +  = (  )

By formula: Sc⁺ + C₄H₄N₂ = (Sc⁺  C₄H₄N₂)

Quantity	Value	Units	Method	Reference	Comment
rH°	51.2 ± 2.2	kcal/mol	CIDT	Amunugama and Rodgers, 2001	RCD

 +  = (  )

By formula: Mg⁺ + C₄H₄N₂ = (Mg⁺  C₄H₄N₂)

Quantity	Value	Units	Method	Reference	Comment
rH°	41.5 ± 1.4	kcal/mol	CIDT	Amunugama and Rodgers, 2001	RCD

 +  = (  )

By formula: V⁺ + C₄H₄N₂ = (V⁺  C₄H₄N₂)

Quantity	Value	Units	Method	Reference	Comment
rH°	48.8 ± 1.7	kcal/mol	CIDT	Amunugama and Rodgers, 2001	RCD

 +  = (  )

By formula: Ni⁺ + C₄H₄N₂ = (Ni⁺  C₄H₄N₂)

Quantity	Value	Units	Method	Reference	Comment
rH°	58.3 ± 2.3	kcal/mol	CIDT	Amunugama and Rodgers, 2001	RCD

 +  = (  )

By formula: Al⁺ + C₄H₄N₂ = (Al⁺  C₄H₄N₂)

Quantity	Value	Units	Method	Reference	Comment
rH°	38.0 ± 1.4	kcal/mol	CIDT	Amunugama and Rodgers, 2001	RCD

 +  = (  )

By formula: Zn⁺ + C₄H₄N₂ = (Zn⁺  C₄H₄N₂)

Quantity	Value	Units	Method	Reference	Comment
rH°	49.8 ± 1.8	kcal/mol	CIDT	Amunugama and Rodgers, 2001	RCD

 +  = (  )

By formula: Co⁺ + C₄H₄N₂ = (Co⁺  C₄H₄N₂)

Quantity	Value	Units	Method	Reference	Comment
rH°	58.6 ± 3.2	kcal/mol	CIDT	Amunugama and Rodgers, 2001	RCD

 +  = (  )

By formula: Cu⁺ + C₄H₄N₂ = (Cu⁺  C₄H₄N₂)

Quantity	Value	Units	Method	Reference	Comment
rH°	59.6 ± 2.3	kcal/mol	CIDT	Amunugama and Rodgers, 2001	RCD

IR Spectrum

Go To: Top, Gas phase thermochemistry data, Condensed phase thermochemistry data, Phase change data, Reaction thermochemistry data, Mass spectrum (electron ionization), References, Notes

Data compiled by: Coblentz Society, Inc.

• LIQUID (NEAT); PERKIN-ELMER 521 (GRATING); (ADJUSTED subtractcm-1misc); 2 cm^-1 resolution
• SOLUTION (10% IN CCl4 FOR 3800-1370, 10% IN CS2 FOR 1370-450 CM^-1); DOW KBr FOREPRISM-GRATING; DIGITIZED BY NIST FROM HARD COPY (FROM TWO SEGMENTS); 2 cm^-1 resolution

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

• gas

Mass spectrum (electron ionization)

Go To: Top, Gas phase thermochemistry data, Condensed phase thermochemistry data, Phase change data, Reaction thermochemistry data, IR Spectrum, References, Notes

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

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

Spectrum

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Additional Data

References

Go To: Top, Gas phase thermochemistry data, Condensed phase thermochemistry data, Phase change data, Reaction thermochemistry data, IR Spectrum, Mass spectrum (electron ionization), Notes

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

Nabavian, Sabbah, et al., 1977
Nabavian, P.M.; Sabbah, R.; Chastel, R.; Laffitte, M., Thermodynamique de composes azotes. II. Etude thermochimique des acides aminobenzoiques, de la pyrimidine, de l'uracile et de la thymine., J. Chim. Phys., 1977, 74, 115-126. [all data]

Pedley, Naylor, et al., 1986
Pedley, J.B.; Naylor, R.D.; Kirby, S.P., Thermochemical Data of Organic Compounds, Chapman and Hall, New York, 1986, 1-792. [all data]

Tjebbes, 1962
Tjebbes, J., The heats of combustion and formation of the three diazines and their resonance energies, Acta Chem. Scand., 1962, 16, 916-921. [all data]

Cox and Pilcher, 1970
Cox, J.D.; Pilcher, G., Thermochemistry of Organic and Organometallic Compounds, Academic Press, New York, 1970, 1-636. [all data]

Weast and Grasselli, 1989
CRC Handbook of Data on Organic Compounds, 2nd Editon, Weast,R.C and Grasselli, J.G., ed(s)., CRC Press, Inc., Boca Raton, FL, 1989, 1. [all data]

Wovkulich and Atwood, 1980
Wovkulich, M.J.; Atwood, J.D., J. Organometal. Chem., 1980, 184, 77. [all data]

Dennenberg and Darensbourg, 1972
Dennenberg, R.J.; Darensbourg, D.J., Inorg. Chem., 1972, 11, 72. [all data]

Graham and Angelici, 1967
Graham, J.R.; Angelici, R.J., Inorg. Chem., 1967, 6, 2082. [all data]

Nakashima and Adamson, 1982
Nakashima, M.; Adamson, A.W., J. Phys. Chem., 1982, 86, 2905. [all data]

Meot-ner and Kafafi, 1988
Meot-ner, M.; Kafafi, S.A., Carbon Acidities of Aromatic Compounds, J. Am. Chem. Soc., 1988, 110, 19, 6297, https://doi.org/10.1021/ja00227a003 . [all data]

Wren, Vogelhuber, et al., 2012
Wren, S.W.; Vogelhuber, K.M.; Garver, J.M.; Kato, S.; Sheps, L.; Bierbaum, V.M.; Lineberger, W.C., C-H Bond Strengths and Acidities in Aromatic Systems: Effects of Nitrogen Incorporation in Mono-, Di-, and Triazines, J. Am. Chem. Soc., 2012, 134, 15, 6584-6595, https://doi.org/10.1021/ja209566q . [all data]

Gonzalez, Zhang, et al., 1988
Gonzalez, A.A.; Zhang, K.; Nolan, S.P.; Lopez de la Vega, R.; Mukerjee, S.L.; Hoff, C.D., Organometallics, 1988, 7, 2429. [all data]

Adedeji, Connor, et al., 1978
Adedeji, F.A.; Connor, J.A.; Demain, C.P.; Martinho Simões, J.A.; Skinner, H.A.; Zafarani- Moattar, M.T., J. Organometal. Chem., 1978, 149, 333. [all data]

Nolan, Hoff, et al., 1985
Nolan, S.P.; Hoff, C.D.; Landrum, J.T., J. Organometal. Chem., 1985, 282, 357. [all data]

Le Barbu, Schiedt, et al., 2002
Le Barbu, K.; Schiedt, J.; Weinkauf, R.; Schlag, E.W.; Nilles, J.M.; Xu, S.J.; Thomas, O.C.; Bowen, K.H., Microsolvation of small anions by aromatic molecules: An exploratory study, J. Chem. Phys., 2002, 116, 22, 9663-9671, https://doi.org/10.1063/1.1475750 . [all data]

Mukerjee, Lang, et al., 1992
Mukerjee, S.L.; Lang, R.F.; Ju, T.; Kiss, G.; Hoff, C.D.; Nolan, S.P., Inorg. Chem., 1992, 31, 4885. [all data]

Partenheimer and Durham, 1974
Partenheimer, W.; Durham, B., J. Am. Chem. Soc., 1974, 96, 3800. [all data]

Daamen, van der Poel, et al., 1979
Daamen, H.; van der Poel, H.; Stufkens, D.J.; Oskam, A., Thermochim. Acta, 1979, 34, 69. [all data]

Meester, Vriends, et al., 1976
Meester, M.A.M.; Vriends, R.C.J.; Stufkens, D.J.; Vrieze, K., Inorg. Chim. Acta, 1976, 19, 95. [all data]

Yang, Vaida, et al., 1988
Yang, G.K.; Vaida, V.; Peters, K.S., Polyhedron, 1988, 7, 1619. [all data]

Zhang, Gonzalez, et al., 1991
Zhang, K.; Gonzalez, A.A.; Murkerjee, S.L.; Chou, S.-J.; Hoff, C.D.; Kubat- Martin, K.A.; Barnhart, D.; Kubas, G.J., J. Am. Chem. Soc., 1991, 113, 9170. [all data]

Amunugama and Rodgers, 2001
Amunugama, R.; Rodgers, M.T., Periodic Trends in the Binding of Metal Ions to Pyrimidine Studied by Threshold Collision-Induced Dissociation and Density Functional Theory, J. Phys. Chem. A, 2001, 105, 43, 9883, https://doi.org/10.1021/jp010663i . [all data]

Notes

Go To: Top, Gas phase thermochemistry data, Condensed phase thermochemistry data, Phase change data, Reaction thermochemistry data, IR Spectrum, Mass spectrum (electron ionization), References

• Symbols used in this document:
  

  Tboil	Boiling point
  cH°liquid	Enthalpy of combustion of liquid at standard conditions
  fH°gas	Enthalpy of formation of gas at standard conditions
  fH°liquid	Enthalpy of formation of liquid at standard conditions
  rG°	Free energy of reaction at standard conditions
  rH°	Enthalpy of reaction at standard conditions
  rS°	Entropy of reaction at standard conditions
  vapH°	Enthalpy of vaporization at standard conditions

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