Aluminium dihydrogenphosphate describes inorganic compounds with the formula Al(H2PO4)3.xH2O where x = 0 or 3. They are white solids. Upon heating these materials convert sequentially to a family of related polyphosphate salts including aluminium triphosphate (AlH2P3O10.2H2O), aluminium hexametaphosphate (Al2P6O18), and aluminium tetrametaphosphate (Al4(P4O12)3). Some of these materials are used for fireproofing and as ingredients in specialized glasses.[1]
According to analysis by X-ray crystallography, the structure consists of a coordination polymer featuring octahedral Al3+ centers bridged by tetrahedral dihydrogen phosphate ligands. The dihydrogen phosphate ligands are bound to Al3+ as monodentate ligands.[2]