The structure of tetrakis(melaminium) bis(dihydrogenphosphate) monohydrogenphosphate trihydrate from X-ray powder diffraction and solid-state NMR spectroscopy,

V. Brodski, R. Peschar, H. Schenk, A. Brinkmann, E. R. H. van Eck, and A. P. M. Kentgens,
J. Phys. Chem. C 112, 12515-12523, (2008).
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The crystal structure of the melamine phosphate salt tetrakis-​(melaminium) bis-​(di-​hydrogen-​phosphate) mono-​hydrogen-​phosphate tri-​hydrate with as much as ten independent moieties in the unit cell was determined by a direct-​space global optimization technique from X-ray powder diffraction data using additional geometry constraints obtained by 31P double-​quantum solid-​state NMR spectroscopy. The structure analysis of the compound and its comparison with other melamine phosphates reveals the packing and bonding characteristics that are important for melamine-​phosphate salts with a melamine-​to-​phosphor ratio larger than one, which are promising environmental-​friendly flame retardants.