return to home page

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

Listing of experimental data for Si2H6 (disilane)

Other names
Disilane; Silicoethane;
InChI=1/H6Si2/c1-2/h1-2H3 [SiH3][SiH3] Disilane
State Conformation
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 80.30 1.50 kJ mol-1 1998Rap/Ape
Hfg(0K) enthalpy of formation   1.50 kJ mol-1 1998Rap/Ape
Entropy (298.15K) entropy 270.13 10.00 J K-1 mol-1 NA
Integrated Heat Capacity (0 to 298.15K) integrated heat capacity 15.02 10.00 kJ mol-1 NA
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 A1g 2152 1957Bet/Wil:1107      
2 A1g 909 1957Bet/Wil:1107      
3 A1g 434 1957Bet/Wil:1107      
4 A1u 131 2003Lat/DiL:2895      
5 A2u 2154 1957Bet/Wil:1107      
6 A2u 844 1957Bet/Wil:1107      
7 Eg 2155 1957Bet/Wil:1107       Eg and Eu modes switched
8 Eg 929 1957Bet/Wil:1107      
9 Eg 625 1957Bet/Wil:1107      
10 Eu 2179 1957Bet/Wil:1107       Eg and Eu modes switched
11 Eu 940 1957Bet/Wil:1107      
12 Eu 379 1957Bet/Wil:1107      

vibrational zero-point energy: 10519.0 cm-1
Calculated vibrational frequencies for Si2H6 (disilane).
Rotational Constants (cm-1) rotational constants
See section I.F.4 to change rotational constant units
A B C reference comment
1.43000 0.17200 0.17200 1957Bet/Wil:1107

Calculated rotational constants for Si2H6 (disilane).

Product of moments of inertia moments of inertia
113239.2amu3Å6   5.18518961545594E-115gm3 cm6

Geometric Data
picture of disilane

Point Group D3d

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
rSiSi 2.320   1 2 1998Gup/Pra:1607
rSiH 1.470   1 3 1998Gup/Pra:1607
aHSiSi 109.4 1 2 6 1998Gup/Pra:1607
aHSiH 109.5 3 1 4 1998Gup/Pra:1607 by symmetry

Atom x (Å) y (Å) z (Å)
Si1 0.0000 0.0000 1.1600
Si2 0.0000 0.0000 -1.1600
H3 0.0000 1.3865 1.6483
H4 -1.2008 -0.6933 1.6483
H5 1.2008 -0.6933 1.6483
H6 0.0000 -1.3865 -1.6483
H7 -1.2008 0.6933 -1.6483
H8 1.2008 0.6933 -1.6483

Atom - Atom Distances bond lengths
Distances in Å
  Si1 Si2 H3 H4 H5 H6 H7 H8
Si1   2.32001.47001.47001.47003.13193.13193.1319
Si2 2.3200   3.13193.13193.13191.47001.47001.4700
H3 1.47003.1319   2.40162.40164.30783.57633.5763
H4 1.47003.13192.4016   2.40163.57633.57634.3078
H5 1.47003.13192.40162.4016   3.57634.30783.5763
H6 3.13191.47004.30783.57633.5763   2.40162.4016
H7 3.13191.47003.57633.57634.30782.4016   2.4016
H8 3.13191.47003.57634.30783.57632.40162.4016  

Calculated geometries for Si2H6 (disilane).

Experimental Bond Angles (degrees) from cartesians bond angles
atom1 atom2 atom3 angle         atom1 atom2 atom3 angle
Si1 Si2 H6 109.400 Si1 Si2 H7 109.400
Si1 Si2 H8 109.400 Si2 Si1 H3 109.400
Si2 Si1 H4 109.400 Si2 Si1 H5 109.400
H3 Si1 H4 109.542 H3 Si1 H5 109.542
H4 Si1 H5 109.542 H6 Si2 H7 109.542
H6 Si2 H8 109.542 H7 Si2 H8 109.542

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

Atom 1 Atom 2
Si1 Si2
Si1 H3
Si1 H4
Si1 H5
Si2 H6
Si2 H7
Si2 H8

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

Ionization Energies (eV)
Ionization Energy I.E. unc. vertical I.E. v.I.E. unc. reference
9.740 0.020 10.530   webbook

Dipole, Quadrupole and Polarizability
Electric dipole moment dipole
For a molecule with D3d symmetry there is no dipole.
Electric quadrupole moment quadrupole
Calculated electric quadrupole moments for Si2H6 (disilane).

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
1957Bet/Wil:1107 GW Bethke, MK Wilson "Vibrational Spectrum of Disilane" J. Chem. Phys. 26(5), 1107, 1957 10.1063/1.1743480
1998Gup/Pra:1607 Gupte, Prasad, Ground State Geometries and Vibrational Spectra of Small Hyrdogenated Silicon Clusters Using Nonorthogonal Tight-binding Molecular Dynamics, Inter. J. of Mod. Phys. B, Vol. 12, #15, pgs. 1607-1622 10.1142/S0217979298000880
1998Rap/Ape Z Rappoprt, Y Apeloig, "The chemistry of organic silicon compounds Volume 2 Part 1" Chapter 4, Wiley  
2003Lat/DiL:2895 F Lattanzi, C Di Lauro, V-M Horneman "The nu6, nu8, 3nu4+nu12 infrared system of Si2H6 under high resolution: rotational and torsional analysis" Mol. Phys. 101(18), 2895, 2003 10.1080/00268970310001598722
webbook NIST Chemistry Webbook (  

Got a better number? Please email us at