“…Several other simple phases are known, e.g., AH 2 PO 2 , A ¼ K, Rb, Cs [10], Mg(H 2 O) 6 (H 2 PO 2 ) 2 [11], Mn(H 2 PO 2 ) 2 .H 2 O [12], Co(H 2 O) 6 (H 2 PO 2 ) 2 [9,13], and Cu(H 2 PO 2 ) 2 [14]. Some powder crystallographic data are also known: M(H 2 PO 2 ) 2, Co(H2PO2)2.0.53H2O [15], and VO(H 2 PO 2 ) 2 .H 2 O [16]. This class of materials was studied in both chemistry and material science due to their industrial applications as mild reducing agents, reagents in catalytic syntheses and antioxidants [17,18].…”