Cupric hypophosphite, Cu(H₂PO₂)₂

The solution of Cupric hypophosphite, Cu(H₂PO₂)₂, obtained by addition of slightly less than the equivalent proportion of barium hypophosphite to a solution of cupric sulphate yields, after removal of the barium sulphate and addition of alcohol, the hypophosphite in the form of white crystals. At ordinary temperatures the dry salt does not decompose for several days, but at 90° C. it explodes with evolution of phosphine. On warming in aqueous solution, it decomposes with formation of phosphorous acid, copper, and hydrogen. Its aqueous solution is also decomposed catalytically by palladium:

Cu(H₂PO₂)₂ + 2H₂O = 2H₃PO₃ + Cu + H₂.