Phosphorus dioxide

Phosphorus dioxide (PO₂) is a gaseous oxide of phosphorus. It is a free radical that plays a role in the chemiluminescence of phosphorus and phosphine.^[1] It is produced when phosphates are heated to high temperatures.^[2]

Phosphorus dioxide

Names
IUPAC name Phosphorus(IV) oxide
Other names Phosphorus dioxide
Identifiers
CAS Number	12164-97-5
3D model (JSmol)	Interactive image
ChEBI	CHEBI:37370
ChemSpider	122825
Gmelin Reference	1065
PubChem CID	139273
CompTox Dashboard (EPA)	DTXSID60153329
InChI InChI=1S/O2P/c1-3-2 Key: CJDZTJNITSFKRE-UHFFFAOYSA-N
SMILES O=P[O]
Properties
Chemical formula	O2P
Molar mass	62.972 g·mol−1
ThermochemistryCRC Handbook of Chemistry and Physics, 2005
Heat capacity (C)	39.5 joules (9.4 cal) per mole per K
Std molar entropy (S⦵298)	252.1 joules (60.3 cal) per mole per K
Std enthalpy of formation (ΔfH⦵298)	−279.9 joules (−66.9 cal) per mole
Gibbs free energy (ΔfG⦵)	−281.6 joules (−67.3 cal) per mole
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

In the ground state the molecule is bent, like nitrogen dioxide, but there is an excited state that is linear.^[1]