Bismuth Hypophosphite, Bi(H₂PO₂)₃.H₂O

Bismuth Hypophosphite, Bi(H₂PO₂)₃.H₂O, is obtained as a white crystalline powder by the action of potassium or barium hypophosphite upon a solution of bismuth nitrate. It is decomposed very readily by heat, phosphine being evolved at temperatures a little above 100° C. At higher temperatures some metallic bismuth is formed, and the reaction may possibly be represented by the equation

3Bi(H₂PO₂)₃ = 2Bi + Bi(PO₃)₃ + 6P + 9H₂O

It is also readily decomposed by water.

The use of bismuth hypophosphite in conjunction with hydrogen peroxide has been suggested for the quantitative separation of bismuth from other metals.

A basic hypophosphite, BiO.H₂PO₂, has also been described as resulting from the action of bismuthyl hydroxide, BiO.OH, upon hypophosphorous acid. It also is unstable and appears to resemble closely the normal hypophosphite.