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

Listing of experimental data for I2 (Iodine diatomic)

InChI=1/I2/c1-2 II
State Conformation
1Σg D*H
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 62.42 0.08 kJ mol-1 Gurvich
Hfg(0K) enthalpy of formation 65.50 0.08 kJ mol-1 Gurvich
Entropy (298.15K) entropy 260.68   J K-1 mol-1 Gurvich
Integrated Heat Capacity (0 to 298.15K) integrated heat capacity 10.12   kJ mol-1 Gurvich
Heat Capacity (298.15K) heat capacity 36.89   J K-1 mol-1 Gurvich
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
1 Σ 215        

vibrational zero-point energy: 107.3 cm-1
Calculated vibrational frequencies for I2 (Iodine diatomic).
Rotational Constants (cm-1) rotational constants
See section I.F.4 to change rotational constant units
A B C reference comment
  0.03737 0.03737 webbook Be

Calculated rotational constants for I2 (Iodine diatomic).

Product of moments of inertia moments of inertia
451.1006amu Å2   7.490819E-38gm cm2

Geometric Data
picture of Iodine diatomic

Point Group D∞h

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
rII 2.665   1 2 Gurvich re

Atom x (Å) y (Å) z (Å)
I1 0.0000 0.0000 0.0000
I2 0.0000 0.0000 2.6655

Atom - Atom Distances bond lengths
Distances in Å
  I1 I2
I1   2.6655
I2 2.6655  

Calculated geometries for I2 (Iodine diatomic).

Bond descriptions
Examples: C-C single bond, C=C, double bond, C#C triple bond, C:C aromatic bond
Bond Type Count
I-I 1

Atom 1 Atom 2
I1 I2

Electronic energy levels (cm-1)
Energy (cm-1) Degeneracy reference description
0 1   1Σg

Ionization Energies (eV)
Ionization Energy I.E. unc. vertical I.E. v.I.E. unc. reference
9.307 0.000 9.356   webbook

Dipole, Quadrupole and Polarizability
Electric dipole moment dipole
For a molecule with D∞h symmetry there is no dipole.
Electric quadrupole moment quadrupole
Calculated electric quadrupole moments for I2 (Iodine diatomic).

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squib reference DOI
Gurvich Gurvich, L.V.; Veyts, I. V.; Alcock, C. B., Thermodynamic Properties of Individual Substances, Fouth Edition, Hemisphere Pub. Co., New York, 1989 10.1351/pac198961061027
webbook NIST Chemistry Webbook (  

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