Basic lead phosphite is an

inorganic compound An inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds⁠that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as ''inorganic chemistry''. Inorgan ...

with the proposed composition Pb₃O(OH)₂(HPO₃). The compound contains the phosphite anion, which provides the reducing properties associated with the application of this material. It is widely used as a stabilizer for chlorine-containing polymers, especially polyvinylchloride.. Other lead phosphites are known, including normal lead phosphite, PbHPO₃, although the basic salt is especially effective.

References

Phosphites Inorganic phosphorus compounds Lead(II) compounds {{Inorganic-compound-stub