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)	80.30	1.50	kJ mol-1	1998Rap/Ape
Hfg(0K)		1.50	kJ mol-1	1998Rap/Ape
Entropy (298.15K)	270.13	10.00	J K-1 mol-1	NA
Integrated Heat Capacity (0 to 298.15K)	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)

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)
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
113239.2	amu3Å6		5.18518961545594E-115	gm3 cm6

Geometric Data

Point Group D_3d

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

Cartesians

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
Distances in Å

	Si1	Si2	H3	H4	H5	H6	H7	H8
Si1		2.3200	1.4700	1.4700	1.4700	3.1319	3.1319	3.1319
Si2	2.3200		3.1319	3.1319	3.1319	1.4700	1.4700	1.4700
H3	1.4700	3.1319		2.4016	2.4016	4.3078	3.5763	3.5763
H4	1.4700	3.1319	2.4016		2.4016	3.5763	3.5763	4.3078
H5	1.4700	3.1319	2.4016	2.4016		3.5763	4.3078	3.5763
H6	3.1319	1.4700	4.3078	3.5763	3.5763		2.4016	2.4016
H7	3.1319	1.4700	3.5763	3.5763	4.3078	2.4016		2.4016
H8	3.1319	1.4700	3.5763	4.3078	3.5763	2.4016	2.4016

Calculated geometries for Si₂H₆ (disilane).

Experimental Bond Angles (degrees) from cartesians

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

Connectivity

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.	Electron Affinity	E.A. unc.	reference
9.740	0.020	10.530				webbook

Dipole, Quadrupole and Polarizability
Electric dipole moment
For a molecule with D_3d symmetry there is no dipole.
Electric quadrupole moment
Calculated electric quadrupole moments for Si₂H₆ (disilane).

References
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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 (http://webbook.nist.gov/chemistry)

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