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 CH3I (methyl iodide)

Other names
Methane, iodo-; Iodomethane; Halon 10001; UN 2644; Monoiodomethane;
State Conformation
1A1 C3V
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 15.50 0.80 kJ mol-1 2005Rus/Bog:573
Hfg(0K) enthalpy of formation   0.80 kJ mol-1 2005Rus/Bog:573
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 A1 2933 webbook       2969.8 and 2861.0 Fermi resonance with 2nu5
2 A1 1252 webbook      
3 A1 533 webbook      
4 E 3060 webbook      
5 E 1436 webbook      
6 E 882 webbook      

vibrational zero-point energy: 8013.2 cm-1
Calculated vibrational frequencies for CH3I (methyl iodide).
Rotational Constants (cm-1) rotational constants
See section I.F.4 to change rotational constant units
A B C reference comment
5.17340 0.25021 0.25021 1975mal:94

Calculated rotational constants for CH3I (methyl iodide).

Product of moments of inertia moments of inertia
14791.37amu3Å6   6.77292606649336E-116gm3 cm6
Geometric Data
picture of methyl iodide

Point Group C3v

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 1.084 0.003 1 3 1998Kuc rs
rCI 2.136 0.002 1 2 1998Kuc rs
aHCI 107.47 0.2 2 1 3 1998Kuc
aHCH 111.4 0.2 3 1 4 by symmetry


Atom x (Å) y (Å) z (Å)
C1 0.0000 0.0000 -1.8100
I2 0.0000 0.0000 0.3258
H3 0.0000 1.0340 -2.1354
H4 0.8955 -0.5170 -2.1354
H5 -0.8955 -0.5170 -2.1354

Atom - Atom Distances bond lengths
Distances in Å

  C1 I2 H3 H4 H5
C1   2.13581.08401.08401.0840
I2 2.1358   2.66962.66962.6696
H3 1.08402.6696   1.79091.7909
H4 1.08402.66961.7909   1.7909
H5 1.08402.66961.79091.7909  

Calculated geometries for CH3I (methyl iodide).

Experimental Bond Angles (degrees) from cartesians bond angles

atom1 atom2 atom3 angle         atom1 atom2 atom3 angle
I2 C1 H3 107.470 I2 C1 H4 107.470
I2 C1 H5 107.470 H3 C1 H4 111.396
H3 C1 H5 111.396 H4 C1 H5 111.396

Bond descriptions

Examples: C-C single bond, C=C, double bond, C#C triple bond, C:C aromatic bond
Bond Type Count
C-I 1
H-C 3


Atom 1 Atom 2
C1 I2
C1 H3
C1 H4
C1 H5
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
9.540 0.020     webbook

Electron Affinity (eV)

Electron Affinity unc. reference
0.110 0.020 webbook
Dipole, Quadrupole and Polarizability
Electric dipole moment dipole
Dipole (Debye) Reference comment
1.620 NSRDS-NBS10  

Calculated electric dipole moments for CH3I (methyl iodide).
Electric quadrupole moment quadrupole
Calculated electric quadrupole moments for CH3I (methyl iodide).
Electric dipole polarizability (Å3) polarizability
alpha unc. Reference
7.325   1997Oln/Can:59

Calculated electric dipole polarizability for CH3I (methyl iodide).

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squib reference DOI
1975mal:94 PD Mallinson "The microwave spectrum of CH2DI" J. Molecular Spectroscopy 55, 94-107 (1975) 10.1016/0022-2852(75)90255-6
1997Oln/Can:59 TN Olney, NM Cann, G Cooper, CE Brion, Absolute scale determination for photoabsorption spectra and the calculation of molecular properties using dipole sum-rules, Chem. Phys. 223 (1997) 59-98 10.1016/S0301-0104(97)00145-6
1998Kuc K Kuchitsu(ed) "Structure of Free Polyatomic Molecules - Basic Data" Springer, Berlin, 1998  
2005Rus/Bog:573 B Ruscic, JE Boggs, A Burcat,AG Csaszar,J Demaison, R Janoschek, JML Martin, ML Morton, MJ Rossi, JF Stanton, PG Szalay, PR Westmoreland, F Zabel, T Berces "IUPAC Critical Evaluation of Thermochemical Properties of Selected Radicals. Part I" J. Phys. Chem. Ref. Data, Vol. 34, No. 2, 2005, 573 10.1063/1.1724828
NSRDS-NBS10 R. D. Nelson Jr., D. R. Lide, A. A. Maryott "Selected Values of electric dipole moments for molecules in the gas phase" NSRDS-NBS10, 1967  
webbook NIST Chemistry Webbook (  

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