Diphosphene

For the functional group, see Diphosphene (functional group).

Diphosphene is a compound having the formula (PH)₂. It exists as two geometric isomers, E and Z.^[1] Diphosphene is also the parent member of the entire class of diphosphene compounds with the formula (PR)₂, where R is an organyl group.^[2]

Diphosphene

Ball and stick model of diphosphene molecule
Identifiers
CAS Number	41916-72-7 Y
3D model (JSmol)	Interactive image
ChemSpider	125761 Y
PubChem CID	142559
CompTox Dashboard (EPA)	DTXSID50194680
InChI InChI=1S/H2P2/c1-2/h1-2H Y Key: SWJAOBXRZSMKNS-UHFFFAOYSA-N Y
SMILES P=P
Properties
Chemical formula	P2H2
Molar mass	63.96340 g·mol−1
Related compounds
Other anions	diazene
Other cations	diphosphenes
Related Binary azenes	triazene tetrazene
Related compounds	ammonia diazane triazane
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

Visible radiation induces cis-trans isomerization,^[3] although further irradiation can excite the molecule to a triplet diradical state. In triplet trans-HPPH, the P-P bond length is predicted to be 2.291 Å. It is not only longer than the P-P double bond in ground state trans-bis(2,4,6-tri-tert-butylphenyl)diphosphene, but also longer than that of P-P single bond in H₂P−PH₂. Calculation of the dihedral angle of trans-HPPH suggests that it is almost 90 degree, which means the formation of ${\displaystyle \pi }$ and ${\displaystyle \pi ^{*}}$ P-P bonds is forbidden and σ bond is enhanced.^[4]