Preparation and characterization of the layered borophosphates MII(H2O)2[B2P2O8(OH)2]·H2O (MII = Fe, Co, Ni)

The crystal structure of MII(H2O)2[B2P2O8(OH)2]·H2O (MII = Fe, Co, Ni) contains a layered anionic partial structure, which is rare in the field of borophosphates (see figure). It comprises a two-dimensional arrangement of distorted PO4 and HBO4 groups that are connected in an alternating fashion via common corners. This arrangement is described as wavy 63 (figure bottom) net in the field of silicate structural chemistry.