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)			kJ mol-1	webbook
Hfg(0K)	-12.54		kJ mol-1	webbook
Entropy (298.15K)			J K-1 mol-1
Integrated Heat Capacity (0 to 298.15K)			kJ mol-1

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

Calculated vibrational frequencies for P₂H₄ (H2PPH2).

Rotational Constants (cm^-1)
See section I.F.4 to change rotational constant units

A	B	C	reference	comment

Calculated rotational constants for P₂H₄ (H2PPH2).

Product of moments of inertia
	amu3Å6		0	gm3 cm6

Geometric Data

Point Group C₂

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
rPH	1.414		1	4			1976Hellwege(II/7)	outside
rPH	1.417		1	3			1976Hellwege(II/7)	inside
rPP	2.219		1	2			1976Hellwege(II/7)
aHPH	92		3	1	4		1976Hellwege(II/7)
aHPP	94.3		1	2	5		1976Hellwege(II/7)	outside H
aHPP	99.1		1	2	6		1976Hellwege(II/7)	inside H
dHPPH	74		3	1	2	6	1976Hellwege(II/7)	Hs on different Ps
dHPPH	97.1		3	1	2	4		from HF/6-31G*, Hs on same P

Cartesians

Atom	x (Å)	y (Å)	z (Å)
P1	0.0000	1.1096	-0.0080
P2	0.0000	-1.1096	-0.0080
H3	0.8420	1.3337	1.1094
H4	1.0127	1.2156	-0.9891
H5	-0.8420	-1.3337	1.1094
H6	-1.0127	-1.2156	-0.9891

Atom - Atom Distances
Distances in Å

	P1	P2	H3	H4	H5	H6
P1		2.2191	1.4170	1.4140	2.8155	2.7193
P2	2.2191		2.8155	2.7193	1.4170	1.4140
H3	1.4170	2.8155		2.1088	3.1545	3.7871
H4	1.4140	2.7193	2.1088		3.7871	3.1643
H5	2.8155	1.4170	3.1545	3.7871		2.1088
H6	2.7193	1.4140	3.7871	3.1643	2.1088

Calculated geometries for P₂H₄ (H2PPH2).

Experimental Bond Angles (degrees) from cartesians

atom1	atom2	atom3	angle		atom1	atom2	atom3	angle
P1	P2	H5	99.100		P1	P2	H6	94.300
P2	P1	H3	99.100		P2	P1	H4	94.300
H3	P1	H4	96.298		H5	P2	H6	96.298

Bond descriptions
Examples: C-C single bond, C=C, double bond, C#C triple bond, C:C aromatic bond

Bond Type	Count
H-P	4
P-P	1

Connectivity

Atom 1	Atom 2
P1	P2
P1	H3
P1	H4
P2	H5
P2	H6

Electronic energy levels (cm^-1)

Energy (cm-1)	Degeneracy	reference	description
0	1		1A

Ionization Energies (eV)

Ionization Energy	I.E. unc.	vertical I.E.	v.I.E. unc.	Electron Affinity	E.A. unc.	reference
8.800		9.690				webbook

Dipole, Quadrupole and Polarizability
Electric dipole moment
Calculated electric dipole moments for P₂H₄ (H2PPH2).
Electric quadrupole moment
Calculated electric quadrupole moments for P₂H₄ (H2PPH2).

References
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squib	reference	DOI
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.
webbook	NIST Chemistry Webbook (http://webbook.nist.gov/chemistry)

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