Direct synthesis of bis(n-alkylammonium) monohydrogen phosphates by solid–vapour reaction

n-Alkylamines (CnH2n+1NH2, n=2–6) have been intercalated into orthophosphoric acid by exposing the solid to the vapour of the amines. Compounds were obtained of both the (CnH2n+1NH3)(H2PO4) and (CnH2n+1NH3)2(HPO4)·H2O formulae. In the novel monohydrogen phosphates, n-alkylamines form a bimolecular film inclined an average of 42.6° with respect to the phosphate layer plane. These compounds are proposed as starting materials for the hydrothermal synthesis of new open-framework metal phosphates.