The bivalent metal hypophosphites Sr(H2PO2)2, Pb(H2PO2)2 and Ba(H2PO2)2

The structures of isomorphous monoclinic strontium and lead bis­(di­hydrogenphosphate), Sr(H₂PO₂)₂ and Pb(H₂PO₂)₂, and orthorhombic barium bis­(di­hydrogen­phos­phate), Ba(H₂PO₂)₂, consist of layers of hypophosphite anions and metal cations exhibiting square antiprismatic coordination by O atoms. The Sr and Pb atoms are located on sites with point symmetry 2, and the Ba atoms are on sites with point symmetry 222. Within the layers, each anion bridges four metal cations.