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Experimental data for C4H4N2 (1,3-Diazine)

22 02 02 11 45
Other names
1,3-Diazabenzene; 1,3-Diazine; m-Diazine; Metadiazine; Miazine; Pyrimidine;
INChI INChIKey SMILES IUPAC name
InChI=1S/C4H4N2/c1-2-5-4-6-3-1/h1-4H CZPWVGJYEJSRLH-UHFFFAOYSA-N N1=CC=CN=C1 Pyrimidine
State Conformation
1A1 C2V
Enthalpy of formation (Hfg), Entropy, Integrated heat capacity (0 K to 298.15 K) (HH), Heat Capacity (Cp)
Property Value Uncertainty units Reference Comment
Hfg(298.15K) enthalpy of formation 195.94 1.38 kJ mol-1 webbook
Hfg(0K) enthalpy of formation   1.38 kJ mol-1 webbook
Entropy (298.15K) entropy     J K-1 mol-1  
Integrated Heat Capacity (0 to 298.15K) integrated heat capacity     kJ mol-1  
Information can also be found for this species in the NIST Chemistry Webbook
Vibrational levels (cm-1) vibrations
Mode Number Symmetry Frequency Intensity Comment Description
Fundamental(cm-1) Harmonic(cm-1) Reference (km mol-1) unc. Reference
1 A1 3082   1998Bil/Mik:225      
2 A1 3053   1998Bil/Mik:225      
3 A1 3049   1998Bil/Mik:225      
4 A1 1572   1998Bil/Mik:225      
5 A1 1465   1998Bil/Mik:225      
6 A1 1155   1998Bil/Mik:225      
7 A1 1065   1998Bil/Mik:225      
8 A1 969   1998Bil/Mik:225      
9 A1 679   1998Bil/Mik:225      
10 A2 960   1998Bil/Mik:225      
11 A2 398   1998Bil/Mik:225      
12 B1 1033   1998Bil/Mik:225      
13 B1 980   1998Bil/Mik:225      
14 B1 804   1998Bil/Mik:225      
15 B1 719   1998Bil/Mik:225      
16 B1 347   1998Bil/Mik:225      
17 B2 3047   1998Bil/Mik:225      
18 B2 1569   1998Bil/Mik:225      
19 B2 1411   1998Bil/Mik:225      
20 B2 1356   1998Bil/Mik:225      
21 B2 1224   1998Bil/Mik:225      
22 B2 1158   1998Bil/Mik:225      
23 B2 1071   1998Bil/Mik:225      
24 B2 621   1998Bil/Mik:225      

vibrational zero-point energy: 16393.5 cm-1 (from fundamental vibrations)
Calculated vibrational frequencies for C4H4N2 (1,3-Diazine).
Gas-phase IR spectra can be found in the NIST Chemistry Webbook here.
Rotational Constants (cm-1) rotational constants
See section I.F.4 to change rotational constant units
A B C reference comment
0.20937 0.20238 0.10288 1966Herzberg

Calculated rotational constants for C4H4N2 (1,3-Diazine).
Product of moments of inertia moments of inertia
1098947amu3Å6   5.0320458253695E-114gm3 cm6
Geometric Data
picture of 1,3-Diazine

Point Group C2v


Internal coordinates
distances (r) in Å, angles (a) in degrees, dihedrals (d) in degrees
Description Value unc. Connectivity Reference Comment
Atom 1 Atom 2 Atom 3 Atom 4
rCH 1.087   1 7 1992Kuchitsu(II/21) center C of 3
rCH 1.079   3 9 1992Kuchitsu(II/21) next to N
rCH 1.082   2 8 1992Kuchitsu(II/21) between N
rCC 1.393   1 4 1992Kuchitsu(II/21)
rCN 1.350   3 5 1992Kuchitsu(II/21) from 3C side
rCN 1.328   2 6 1992Kuchitsu(II/21) to C inbetween
aCCC 117.8 4 1 3 1992Kuchitsu(II/21)
aHCC 120.9 1 4 10 1992Kuchitsu(II/21) towards N
aCCN 121.2 1 4 6 1992Kuchitsu(II/21)
aHCC 121.1 3 1 7 1992Kuchitsu(II/21) by symmetry
aHCN 117.9 6 4 10 1992Kuchitsu(II/21) by symmetry

Cartesians
Atom x (Å) y (Å) z (Å)

Atom - Atom Distances bond lengths
Distances in Å
 

Calculated geometries for C4H4N2 (1,3-Diazine).

Bond descriptions


Examples: C-C single bond, C=C, double bond, C#C triple bond, C:C aromatic bond
Bond Type Count
H-C 4
C:C 2
C:N 4

Connectivity
Atom 1 Atom 2
C1 C3
C1 C4
C1 H7
C2 N5
C2 N6
C2 H8
C3 N5
C3 H9
C4 N6
C4 H10
Electronic energy levels (cm-1)
Energy (cm-1) Degeneracy reference description
0 1   1A1

Ionization Energies (eV)
Ionization Energy I.E. unc. vertical I.E. v.I.E. unc. reference
9.330 0.070 9.730 0.030 webbook
Dipole, Quadrupole and Polarizability
Electric dipole moment dipole
State Config State description Conf description Exp. min. Dipole (Debye) Reference comment Point Group Components
x y z total dipole quadrupole
1 1 1A1 C2v True           C2v 1 2
Experimental dipole measurement abbreviations: MW microwave; DT Dielectric with Temperature variation; DR Indirect (usually an upper limit); MB Molecular beam
Calculated electric dipole moments for C4H4N2 (1,3-Diazine).
Electric quadrupole moment quadrupole
State Config State description Conf description Exp. min. Quadrupole (D Å) Reference comment Point Group Components
xx yy zz dipole quadrupole
1 1 1A1 C2v True       C2v 1 2

Calculated electric quadrupole moments for C4H4N2 (1,3-Diazine).

References
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squib reference DOI
1966Herzberg Herzberg, G., Electronic spectra and electronic structure of polyatomic molecules,Van Nostrand,New York, 1966  
1992Kuchitsu(II/21) Kuchitsu (ed.), Landolt-Bornstein: Group II: Atomic and Molecular Physics Volume 21: Structure Data of Free Polyatomic Molecules. Springer-Verlag, Berlin, 1992.  
1998Bil/Mik:225 F Billes, H Mikosch, S Holly "A comparative study on the vibrational spectroscopy of pyridazine, pyrimidine and pyrazine" J. Mol. Struct. THEOCHEM 423(3) 225-234, 1998 10.1016/S0166-1280(97)00143-7
webbook NIST Chemistry Webbook (http://webbook.nist.gov/chemistry) 10.18434/T4D303

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