Pyrophosphite

Phosphite anion

Names
Systematic IUPAC name Phosphite
Identifiers
CAS Number	14901-63-4 N
3D model (JSmol)	Interactive image Interactive image
ChEBI	CHEBI:45064 N
ChEMBL	ChEMBL1235376 N
ChemSpider	97035 N
Gmelin Reference	68617
MeSH	Phosphorite
PubChem CID	107908
InChI InChI=1S/O3P/c1-4(2)3/q-3 N Key: AQSJGOWTSHOLKH-UHFFFAOYSA-N N
SMILES [O-]P([O-])[O-] P([O-])([O-])[O-]
Properties
Chemical formula	PO3− 3
Molar mass	78.9720 g mol−1
Related compounds
Other anions	Phosphinite Phosphonite
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N  (what is YN ?)
Infobox references

Phosphonite

A phosphite anion or 'phosphite in inorganic chemistry usually refers to [HPO₃]²⁻ but includes [H₂PO₃]⁻ ([HPO₂(OH)]⁻). These anions are the conjugate bases of phosphorous acid (H₃PO₃). The corresponding salts, e.g. sodium phosphite (Na₂HPO₃) are reducing in character.

The IUPAC recommended name for phosphorous acid is phosphonic acid. Correspondingly, the IUPAC-recommended name for the HPO²⁻
₃ ion is phosphonate. In the US the IUPAC naming conventions for inorganic compounds are taught at high school, but not as a 'required' part of the curriculum. A well-known university-level textbook follows the IUPAC recommendations. In practise any reference to "phosphite" should be investigated to determine the naming convention being employed.

From the commercial perspective, the most important phosphite salt is basic lead phosphite, Many salts containing the phosphite ion have been investigated structurally, these include sodium phosphite pentahydrate (Na₂HPO₃·5H₂O). (NH₄)₂HPO₃·H₂O, CuHPO₃·H₂O, SnHPO₃ and Al₂(HPO₃)₃·4H₂O. The structure of HPO²⁻
₃ is approximately tetrahedral.

HPO²⁻
₃ has a number of canonical resonance forms making it isoelectronic with bisulfite ion, HSO⁻
₃, which has a similar structure.