1,3-Diazine

Formula: C₄H₄N₂
Molecular weight: 80.0880
IUPAC Standard InChI: InChI=1S/C4H4N2/c1-2-5-4-6-3-1/h1-4H
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
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- Gas Phase Kinetics Database
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Phase change data

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

Gas phase ion energetics data

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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
LBLHLM - Sharon G. Lias, John E. Bartmess, Joel F. Liebman, John L. Holmes, Rhoda D. Levin, and W. Gary Mallard
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 C₄H₄N₂⁺ (ion structure unspecified)

Quantity	Value	Units	Method	Reference	Comment
IE (evaluated)	9.33 ± 0.07	eV	N/A	N/A	L
Quantity	Value	Units	Method	Reference	Comment
Proton affinity (review)	211.7	kcal/mol	N/A	Hunter and Lias, 1998	HL
Quantity	Value	Units	Method	Reference	Comment
Gas basicity	204.5	kcal/mol	N/A	Hunter and Lias, 1998	HL

Electron affinity determinations

EA (eV)	Method	Reference	Comment
>-0.24999	ETS	Nenner and Schultz, 1975	Pyrimidine. EA estimated as 0 eV, based on soln phase electrochemical correlations. G3MP2B3 calculations put EA at -4 kcal/mol; B

Ionization energy determinations

IE (eV)	Method	Reference	Comment
9.1	PE	Piancastelli, Keller, et al., 1983	LBLHLM
9.23	PE	Gleiter, Heilbronner, et al., 1972	LLK
9.32 ± 0.01	PE	Asbrink, Fridh, et al., 1972	LLK
9.42	PE	Dewar and Worley, 1969	RDSH
9.35 ± 0.01	PI	Yencha and El-Sayed, 1968	RDSH
9.73 ± 0.03	PE	Hush and Cheung, 1975	Vertical value; LLK
9.73	PE	Suffolk, 1974	Vertical value; LLK
9.73	PE	Gleiter, Heilbronner, et al., 1970	Vertical value; RDSH

Appearance energy determinations

Ion	AE (eV)	Other Products	Method	Reference	Comment
C₃H₂N⁺	15.01 ± 0.10	?	EI	Momigny, Urbain, et al., 1965	RDSH
C₃H₃N⁺	12.87 ± 0.10	HCN	EI	Momigny, Urbain, et al., 1965	RDSH
C₄H₃N₂⁺	13.01 ± 0.10	H	EI	Momigny, Urbain, et al., 1965	RDSH

De-protonation reactions

C₄H₃N₂^- + = 1,3-Diazine

By formula: C₄H₃N₂^- + H⁺ = C₄H₄N₂

Quantity	Value	Units	Method	Reference	Comment
Δ_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
Δ_rG°	376.80 ± 0.70	kcal/mol	N/A	Wren, Vogelhuber, et al., 2012	gas phase; B
Δ_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

Ion clustering data

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Data compiled as indicated in comments:
RCD - Robert C. Dunbar
B - John E. Bartmess

Note: Please consider using the reaction search for this species. This page allows searching of all reactions involving this species. Searches may be limited to ion clustering reactions. A general reaction search form is also available.

Clustering reactions

+ 1,3-Diazine = ( • )

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

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

+ 1,3-Diazine = ( • )

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

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

+ 1,3-Diazine = ( • )

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

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

+ 1,3-Diazine = ( • )

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

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

+ 1,3-Diazine = ( • )

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

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

+ 1,3-Diazine = ( • )

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

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

+ 1,3-Diazine = ( • )

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

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

+ 1,3-Diazine = C₄H₄N₃O^-

By formula: NO^- + C₄H₄N₂ = C₄H₄N₃O^-

Quantity	Value	Units	Method	Reference	Comment
Δ_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

+ 1,3-Diazine = ( • )

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

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

+ 1,3-Diazine = ( • )

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

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

+ 1,3-Diazine = ( • )

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

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

+ 1,3-Diazine = ( • )

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

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

+ 1,3-Diazine = ( • )

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

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

References

Go To: Top, Phase change data, Gas phase ion energetics data, Ion clustering data, Notes

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]

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]

Nenner and Schultz, 1975
Nenner, I.; Schultz, G.J., Temporary negative ions and electron affinities of benzene and N-heterocyclic molecules: Pyridine, pyridazine, pyrimidine, pyrazine, and s-triazine, J. Chem. Phys., 1975, 62, 1747. [all data]

Piancastelli, Keller, et al., 1983
Piancastelli, M.N.; Keller, P.R.; Taylor, J.W.; Grimm, F.A.; Carlson, T.A., Angular distribution parameter as a function of photon energy for some mono- and diazabenzenes and its use for orbital assignment, J. Am. Chem. Soc., 1983, 105, 4235. [all data]

Gleiter, Heilbronner, et al., 1972
Gleiter, R.; Heilbronner, E.; Hornung, V., Photoelectron spectra of azabenzenes azanaphthalenes: I. Pyridine, diazines s-triazine and s-tetrazine, Helv. Chim. Acta, 1972, 55, 255. [all data]

Asbrink, Fridh, et al., 1972
Asbrink, L.; Fridh, C.; Jonsson, B.O.; Lindholm, E., Rydberg series in small molecules. XVI. Photoelectron, UV, mass and electron impact spectra of pyrimidine, Int. J. Mass Spectrom. Ion Phys., 1972, 8, 215. [all data]

Dewar and Worley, 1969
Dewar, M.J.S.; Worley, S.D., Photoelectron spectra of molecules. II.The ionization potentials of azabenzenes and azanaphthalenes, J. Chem. Phys., 1969, 51, 263. [all data]

Yencha and El-Sayed, 1968
Yencha, A.J.; El-Sayed, M.A., Lowest ionization potentials of some nitrogen heterocyclics, J. Chem. Phys., 1968, 48, 3469. [all data]

Hush and Cheung, 1975
Hush, N.S.; Cheung, A.S., Ionization potentials and donor properties of nucleic acid bases and related compounds, Chem. Phys. Lett., 1975, 34, 11. [all data]

Suffolk, 1974
Suffolk, R.J., The photoelectron spectra of the perfluorodiazines, J. Electron Spectrosc. Relat. Phenom., 1974, 3, 53. [all data]

Gleiter, Heilbronner, et al., 1970
Gleiter, R.; Heilbronner, E.; Hornung, V., Lone pair interaction in pyridazine, pyrimidine, and pyrazine, Angew. Chem. Int. Ed. Engl., 1970, 9, 901. [all data]

Momigny, Urbain, et al., 1965
Momigny, J.; Urbain, J.; Wankenne, H., Les effets de l'impact electronique sur la pyridine et les diazines isomeres, Bull. Soc. Roy. Sci. Liege, 1965, 34, 337. [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]

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]

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]

Notes

Go To: Top, Phase change data, Gas phase ion energetics data, Ion clustering data, References

Symbols used in this document:

AE	Appearance energy
EA	Electron affinity
IE (evaluated)	Recommended ionization energy
T_boil	Boiling point
Δ_rG°	Free energy of reaction at standard conditions
Δ_rH°	Enthalpy of reaction at standard conditions
Δ_vapH°	Enthalpy of vaporization at standard conditions

Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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