National Institute of Standards and Technology
Computational Chemistry Comparison and Benchmark DataBase
Release 17bSeptember 2015
NIST Standard Reference Database 101
IIExperimental data
IIICalculated data
IVData comparisons
VCost comparisons
VIInput and output files
VIITutorials and Units
VIIILinks to other sites
XOlder CCCBDB versions
XIII Vibrations
XIVReaction data
XVEntropy data
XVIBibliographic data
XVIIIon data
XVIIIBad calculations
XIXIndex of properties
XXH-bond dimers

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II.A.1. (XV.A.)

Listing of experimental data for C8H6 (benzocyclobutadiene)

Other names
InChI=1S/C8H6/c1-2-4-8-6-5-7(8)3-1/h1-6H WHEATZOONURNGF-UHFFFAOYSA-N C12=C(C=C2)C=CC=C1
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
Information can also be found for this species in the NIST Chemistry Webbook
Vibrational levels (cm-1) vibrations
Mode Number Symmetry Frequency (cm-1) Frequency Reference Intensity (km mol-1) Int. unc. Intensity Reference Comment

Calculated vibrational frequencies for C8H6 (benzocyclobutadiene).
Rotational Constants (cm-1) rotational constants
See section I.F.4 to change rotational constant units
A B C reference comment

Calculated rotational constants for C8H6 (benzocyclobutadiene).

Product of moments of inertia moments of inertia
amu3Å6   0gm3 cm6
Geometric Data
picture of benzocyclobutadiene

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


Atom x (Å) y (Å) z (Å)

Atom - Atom Distances bond lengths
Distances in Å


Calculated geometries for C8H6 (benzocyclobutadiene).

Bond descriptions

Examples: C-C single bond, C=C, double bond, C#C triple bond, C:C aromatic bond
Bond Type Count
C:C 6
C-C 2
C=C 1
H-C 6


Atom 1 Atom 2
C1 C2
C1 C7
C1 H9
C2 C3
C2 H10
C3 C4
C3 H11
C4 N8
C4 H12
C5 C6
C5 N8
C5 H13
C6 C7
C6 H14
C7 N8
Electronic energy levels (cm-1)
Energy (cm-1) Degeneracy reference description

Ionization Energies (eV)

Ionization Energy I.E. unc. vertical I.E. v.I.E. unc. reference
7.500       webbook

Electron Affinity (eV)

Electron Affinity unc. reference
0.321 0.050 webbook
Dipole, Quadrupole and Polarizability
Electric dipole moment dipole
Calculated electric dipole moments for C8H6 (benzocyclobutadiene).
Electric quadrupole moment quadrupole
Calculated electric quadrupole moments for C8H6 (benzocyclobutadiene).

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