The Synthesis and Thermal Behavior of Hydrated Sodium Tetra-μ-imido-cyclo-tetraphosphate

Abstract Hydrated tetrasodium tetra-μ-imido-cyclo-tetraphosphate, (NaPO2NH)4·2.5H2O, has been prepared by hydrolyzing 2,2,4,4,6,6,8,8-octachloro-2λ5,4λ5,6λ5,8λ5-cyclotetraphosphaza-1,3,5,7-tetraene in an aqueous sodium acetate solution. The tetra-μ-imino-cyclo-tetraphosphate reorganized to produce trisodium tri-μ-imido-cyclo-triphosphate and then changed to make chain and ring condensed phosphates containing imino groups upon heating above 180 °C in air according to the following reactions: All kinds of the imidopolyphosphates were finally converted to sodium cyclo-triphosphate above 550 °C by the substitution of imino groups for bridging oxygens and reorganization of the thermal products.