National Institute of Standards and Technology
Computational Chemistry Comparison and Benchmark DataBase
Release 19April 2018
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

NIST policy on privacy, security, and accessibility.

Please rate our products
© 2013 copyright by the U.S. Secretary of Commerce on behalf of the United States of America. All rights reserved.

The National Institute of Standards and Technology (NIST) is an agency of the U.S. Department of Commerce.

Please send questions, comments, corrections, additions and suggestions to

return to home page

II.A.3. (XII.A.1.)

Listing of experimental geometry data for CH3CH(CH3)CH3 (Isobutane)

Rotational Constants (cm-1)

See section I.F.4 to change rotational constant units
0.25979 0.25171 0.14780
Rotational Constants from 1960Lide:1519
Calculated rotational constants for CH3CH(CH3)CH3 (Isobutane).

Point Group C3v

Internal coordinates

(distances (r) in Å) (angles (a) in degrees) (dihedrals (d) in degrees)
Description Value Connectivity Reference Comment
Atom 1 Atom 2 Atom 3 Atom 4
rCC 1.525 1 3 1976Hellwege(II/7)
rCH 1.108 1 2 1976Hellwege(II/7)
rCH 1.100 3 6 1976Hellwege(II/7) symmetric
rCH 1.092 3 9 1976Hellwege(II/7) anti
aCCC 111.15 3 1 4 1976Hellwege(II/7)
aHCC 109.4 2 1 3 1976Hellwege(II/7)
aHCH 108.5 9 3 10 1976Hellwege(II/7) anti-anti
aHCH 107.9 6 3 9 1976Hellwege(II/7) anti-sym
picture of Isobutane

Bond descriptions

Examples: C-C single bond, C=C, double bond, C#C triple bond, C:C aromatic bond
Bond Type Count
H-C 10
C-C 3

Atom x (Å) y (Å) z (Å)
C1 0.0000 0.0000 0.3650
H2 0.0000 0.0000 1.4730
C3 0.0000 1.4528 -0.0987
C4 1.2582 -0.7264 -0.0987
C5 -1.2582 -0.7264 -0.0987
H6 0.0000 1.4867 -1.1931
H7 1.2875 -0.7433 -1.1931
H8 -1.2875 -0.7433 -1.1931
H9 0.8941 1.9575 0.2821
H10 -0.8941 1.9575 0.2821
H11 1.2482 -1.7530 0.2821
H12 2.1422 -0.2045 0.2821
H13 -2.1422 -0.2045 0.2821
H14 -1.2482 -1.7530 0.2821

Atom - Atom Distances (Å)

  C1 H2 C3 C4 C5 H6 H7 H8 H9 H10 H11 H12 H13 H14

Calculated geometries for CH3CH(CH3)CH3 (Isobutane).
By selecting the following links, you may be leaving NIST webspace. We have provided these links to other web sites because they may have information that would be of interest to you. No inferences should be drawn on account of other sites being referenced, or not, from this page. There may be other web sites that are more appropriate for your purpose. NIST does not necessarily endorse the views expressed, or concur with the facts presented on these sites. Further, NIST does not endorse any commercial products that may be mentioned on these sites. Please address comments about this page to
squib reference DOI
1960Lide:1519 Dr Lide "STRUCTURE OF THE ISOBUTANE MOLECULE - CHANGE OF DIPOLE MOMENT ON ISOTOPIC SUBSTITUTION" J. Chem. Phys. 33(5) 1519-1522, 1960 10.1063/1.1731435
1976Hellwege(II/7) Hellwege, KH and AM Hellwege (ed.). Landolt-Bornstein: Group II: Atomic and Molecular Physics Volume 7: Structure Data of Free Polyatomic Molecules. Springer-Verlag. Berlin. 1976.  

Got a better number? Please email us at